PREPARING PRESSURE-SENSITIVE ADHESIVE LAYER

TECHNICAL FIELD

The present invention relates to a pressure-sensitive adhesive composition, a pressure-sensitive adhesive, a pressure-sensitive adhesive layer, a method for preparing a pressure-sensitive adhesive, and a method for preparing a pressure-sensitive adhesive layer.

BACKGROUND

A pressure-sensitive adhesive is an adhesive that is sensitive to pressure. When in use, the pressure-sensitive adhesive can be securely bonded to the adherend without the help of solvent, heat, or any other means. The most widely used pressure-sensitive adhesive is an acrylate pressure-sensitive adhesive.

The pressure-sensitive adhesive tape can be used to bond and secure screens of mobile phones, tablets, laptops, etc. For early phones with small screens, MP3s, MP4s, and PDAs, their screens and housings are often bonded with cotton paper double-sided adhesive tape or double-sided polyester tape. However, as the display screens of mobile phones and tablets become larger and heavier, when these devices fall in the shear direction, the double- sided tape used to bond the screen may fail, resulting in damage to the device.

WO 2017/205444 Al provides an acrylate rubber foam and a double-sided tape comprising the acrylate rubber foam. The acrylate elastomer contained in this acrylate rubber foam, however, is an acrylate rubber (which is usually used to prepare automotive gaskets).

The present invention aims to provide a pressure-sensitive adhesive composition, and a pressure-sensitive adhesive layer prepared by using the pressure-sensitive adhesive composition at least has great shear strength and drop-impact resistance.

SUMMARY

The present invention aims to provide a new pressure-sensitive adhesive composition, and a pressure-sensitive adhesive layer prepared by using the pressure- sensitive adhesive composition at least has great shear strength and drop-impact resistance. A first aspect of the present invention provides a pressure-sensitive adhesive composition, comprising:

(a) a first slurry polymer formed from a first reaction mixture, wherein the first reaction mixture comprises:

(1) a non-tertiary alcohol (meth)acrylate monomer;

(2) an acid functional ethylenically unsaturated monomer;

(3) an alkaline monomer;

based on 100 wt% of a total weight of the monomers in the first reaction mixture, the first slurry polymer comprising:

(i) 1-30 wt% of partially polymerized acid functionalized (meth)acrylate copolymer, wherein the partially polymerized acid functionalized (meth) acrylate copolymer has a weight average molecular weight of more than 500,000 g/mol (Dalton); and

(ii) 70 to 99 wt% of unreacted monomers;

(b) an acrylic block copolymer elastomer; and

(c) an ultraviolet photoinitiator.

A second aspect of the present invention provides a pressure-sensitive adhesive, and the pressure-sensitive adhesive comprises the mixed pressure-sensitive adhesive composition according to the first aspect of the present invention.

A third aspect of the present invention provides a pressure-sensitive adhesive layer, and the pressure-sensitive adhesive layer comprises an ultraviolet curing reaction product of the pressure-sensitive adhesive according to the second aspect of the present invention.

A fourth aspect of the present invention provides a method for preparing a pressure-sensitive adhesive, and the method comprises a step of mixing the pressure- sensitive adhesive composition according to the first aspect of the present invention.

A fifth aspect of the present invention provides a method for preparing a pressure- sensitive adhesive layer, and the method comprises a step of using ultraviolet radiation to cure the pressure-sensitive adhesive according to the third aspect of the invention.

The pressure-sensitive adhesive layer provided by the present invention at least has great shear strength and drop-impact resistance. BRIEF DESCRIPTION OF THE DRAWINGS

FIG. l is a schematic structural diagram of test samples used in a shear strength and drop-impact resistance test and a forward drop-impact resistance test for tapes provided in some embodiments or comparative examples of the present invention;

FIG. 2a is a schematic diagram of a method for performing a shear strength and drop- impact resistance test on tapes provided in certain embodiments or comparative examples of the present invention;

FIG. 2b is a schematic diagram of a method for performing a forward drop-impact resistance test on tapes provided in certain embodiments or comparative examples of the present invention;

FIG. 3 is a schematic structural diagram of tapes provided in certain embodiments or comparative example;

FIGs. 4a, 4b, and 4c are schematic structural diagrams of tapes provided in certain embodiments or comparative examples; and

FIG. 5 is a schematic structural diagram of tapes provided in certain comparative examples of the present invention.

DETAILED DESCRIPTION

The present invention provides a pressure-sensitive adhesive composition, a pressure-sensitive adhesive, a pressure-sensitive adhesive layer, a curable adhesive composition used for preparing a pressure-sensitive adhesive, and a method for preparing a pressure-sensitive adhesive.

As used herein, the terms "polymer," "polymeric," and "polymerized product" refer to materials that are homopolymers, copolymers, terpolymers, and the like. As used herein, the terms "copolymer" and "of copolymer" refer to a polymeric material formed from at least two monomers. That is, the copolymer is a subset of polymers that exclude only homopolymers.

As used herein, the term "slurry polymer" refers to a composition formed partially, but not completely, by polymerization of a reaction mixture including one or more types of monomers. That is, the slurry polymer includes partially polymerized polymer material and unpolymerized residual monomer (i.e., unreacted monomer). Partially polymerized polymer materials are soluble in the remaining monomers and can be referred to as solute polymers. Partially polymerized polymeric materials typically do not crosslink or have small amounts of crosslinking that do not adversely affect their solubility in the remaining monomers. That is, the slurry polymer is usually in single phase. The partially polymerized product is typically at least 1% polymerized, at least 5% polymerized, at least 10% polymerized, at least 15% polymerized, or at least 20% polymerized. The partially polymerized product may have any desired amount of polymerization as long as the remaining monomers have not been polymerized and the remaining monomers form a single phase with the partially polymerized polymer material.

As used herein, the term "(meth)acrylate" refers to both methacrylate and acrylate monomers. Similarly, the term "(meth)acrylic" refers to both acrylic acid and methacrylic acid. When a range is mentioned, the range end values should be understood as being included in the range. For example, expressions such as "in the range from x to y," "in the amount from x to y," or the like include end values x and y.

The first slurry polymer

In the present invention, the first slurry polymer refers to a partially polymerized acid functional (meth)acrylate copolymer.

The first slurry polymer is prepared from a first reaction mixture. An initiator may typically be added to the first reaction mixture (the initiator may be a photoinitiator, such as an ultraviolet photoinitiator) to partially, but not completely, polymerize the first reaction mixture to prepare a first slurry polymer. That is, the first slurry polymer includes a partially polymerized acid functional (meth)acrylate copolymer and an unreacted monomer for forming an acid functionalized (meth)acrylate copolymer.

The first reaction mixture may include one or more monomers. For example, the first reaction mixture may include: (1) a non-tertiary alcohol (meth)acrylate monomer; (2) an acid functional ethylenically unsaturated monomer; and (3) an alkali monomer.

The non-tertiary alcohol has up to 20 carbon atoms, up to 18 carbon atoms, up to 12 carbon atoms, or up to 10 carbon atoms. The non-tertiary alcohol often has 1 to 20 carbon atoms, 1 to 18 carbon atoms, 2 to 18 carbon atoms, 4 to 18 carbon atoms, 1 to 12 carbon atoms, 4 to 12 carbon atoms, 1 to 10 carbon atoms, or 4 to 10 carbon atoms. The non-tertiary alcohol can be linear, branched, or a combination thereof. The exemplary non-tertiary alcohol (meth)acrylate monomers may include: methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, butyl acrylate, isobornyl acrylate, 2-(2-ethoxyethoxy) acrylate ethyl ester, n-amyl acrylate, isoamyl acrylate, 2-methylbutyl acrylate, n-hexyl acrylate, 4-methyl-2-pentyl acrylate, 2- ethylhexyl acrylate, 2-methylhexyl acrylate, n-octyl acrylate, isooctyl acrylate, acrylic acid - 2-octyl ester, isodecyl acrylate, isoamyl acrylate, n-decyl acrylate, isodecyl acrylate, 2-propyl heptyl acrylate, isotridecyl acrylate, isostearyl acrylate, octadecyl acrylate, 2-octadecyl acrylate, dodecyl acrylate, lauryl acrylate, or heptadecyl acrylate. An amount of the non- tertiary alcohol (meth)acrylate monomer is usually in the range of from 40 to 80 wt% based on 100 wt% of the total weight of the monomers in the first reaction mixture. In some embodiments, the amount of the non-tertiary alcohol (meth)acrylate monomer is at least 45 wt%, at least 50 wt%, at least 55 wt%, at least 60 wt%, or at least 70 wt% of the total monomer in the first reaction mixture. The amount of the non-tertiary alcohol (meth)acrylate monomer is up to 80 wt%, up to 75 wt%, or up to 70 wt% of the total monomer in the first reaction mixture.

Each of the acid functional groups of the acid functional ethylenically unsaturated monomer may exist as an acidic group or as a salt of an acidic group. The salt may include an ammonium ion, an alkyl-substituted ammonium ion, or a cation of an alkali metal cation. The acid functional ethylenically unsaturated monomer may include: an ethylenically unsaturated acid, an ethylenically unsaturated sulfonic acid, or an ethylenically unsaturated linonic acid, preferably, acrylic acid, methacrylic acid, itaconic acid, crotonic acid, citraconic acid, maleic acid, oleic acid, bismuth methacrylate, ethyl styrene, styrene sulfonic acid, 2-acrylamido-2- methylpropane Sulfonic acid, or vinyl linonic acid, and more preferably, (methyl)acrylic acid, acrylic acid, ethylenically unsaturated sulfonic acid, or ethylenically unsaturated linonic acid. The content of the acid functional ethylenically unsaturated monomer is usually in the range of from 0.1 to 15 wt% based on 100 wt% of the total weight of the monomers in the first reaction mixture. In some embodiments, the amount of the acid functional ethylenically unsaturated monomer is at least 0.5 wt%, at least 1 wt%, at least 2 wt%, or at least 5 wt%. The amount of the acid functional ethylenically unsaturated monomer is at most 15 wt%, at most 10 wt%, at most 8 wt%, or at most 5 wt%.

The alkali monomer may include: acrylamide, N-vinyl caprolactam, N-vinyl pyrrolidone, or mono- or di-N-alkyl substituted acrylamide (such as N-methyl acrylamide, N- Ethyl acrylamide, N,N-dimethyl acrylamide, N,N-dimethyl methacrylamide, N,N- diethylacrylamide, N,N-diethylmethacrylamide, or N,N- dimethylaminopropylmethacrylamide), or a methylamino-containing acrylate (such as N,N- dimethylamino methacrylate, N,N-dimethylaminopropyl acrylate, N,N-dimethylaminoethyl acrylate, or N,N-dimethylaminopropyl acrylate). In some preferred embodiments, the alkaline monomer may also be N,N-dimethylacrylamide, N-vinylcaprolactam, or N-vinylpyrrolidone. Based on 100 wt% of the total weight of the monomers in the first reaction mixture, an amount of the alkali monomer may be from 19 to 55 wt%, preferably from 20 to 45 wt%, more preferably from 20 to 35 wt%.

The first reaction mixture may also include a vinyl monomer. The vinyl monomer may include: a vinyl ester (such as vinyl acetate and vinyl propionate), styrene, substituted styrene (such as a-methyl styrene), vinyl chloride, or an olefmic monomer (such as ethylene, propylene and butene). These optional vinyl monomers do not include any of the aforementioned non-tertiary alcohol (meth)acrylate monomers or acid functional monomers. Based on 100 wt% of the total weight of the monomers in the first reaction mixture, an amount of the vinyl monomer is from 0.01 to 5 wt%, preferably from 0.1 to 5 wt%, more preferably from 0.5 to 5 wt%.

The slurry polymer may be prepared by using photoinitiated free radical polymerization. The photopolymerization method has the advantages in that: (1) it is not necessary to heat the monomer solution; (2) when the activated light source is turned off, the light emission is completely stopped. The monomer conversion in the system (the ratio of the weight of the polymerized monomer to the weight of all monomers used to prepare the slurry polymer) can be achieved by controlling the amount of photoinitiator. When the slurry polymer reaches the desired conversion and viscosity, the polymerization is terminated by removing the light source and by introducing air (oxygen) into the solution so as to quench the growing free radicals. When the polymerization reaches a coatable viscosity, the highest monomer conversion in the system is about 30%.

Preferably, the ultraviolet polymer-induced free radical polymerization can be used to prepare a slurry polymer. An ultralight photoinitiator for preparing slurry polymers includes: benzoin or substituted acetophenone. The benzoin oxime includes, but is not limited to, benzoin formazan or benzoin isopropanium. The substituted acetophenone includes: 2,2-dimethoxyacetophenone (for example, Irgacure 651 photoinitiator, commercially available from BASF, New Jersey, USA) or 2,2-dimethoxy- 2-Phenyl-l- acetophenone (for example, Esacure KB-l photoinitiator, commercially available from Sartomer Corporation, Pennsylvania, USA). The ultraviolet photoinitiator may further include: dimethoxy hydroxyacetophenone, substituted a keto alcohol (for example, 2- methyl-2-hydroxypropiophenone), aromatic sulfonyl chloride (for example, 2-Cai-sulfonyl chloride), photo-sensitized loss (for example, 1 -phenyl- l,2bikedione-2-(0-ethoxy group) monthly loss), 1 -hydroxy cyclohexyl phenyl ketone (for example, Irgacure 184, commercially available from BASF, Inc., New Jersey, USA), l-[4-(2- hydroxyethoxy)phenyl]-2-hydroxy-2-methyl-l-prop-l- Ketones (for example, Irgacure 2959, commercially available from BASF, NJ, USA), (4-thiobenzoyl)-l gram-l-yl hydrazine ethane (for example, Irgacure 907, commercially available from BASF, New Jersey, USA), (4- morphinyl benzoyl))- 1 -phenyl- l-dimethylaminopropane (for example, Irgacure 369, commercially available from BASF, New Jersey, USA), (4-Olinyl benzoyl)- l-(4-methylbenzyl)- l-dimethylaminopropane (for example, Irgacure 379, commercially available from BASF, New Jersey, USA), II (2,4,6-Trimethylbenzoyl)phenyl phosphine oxide (for example, Irgacure 819, commercially available from BASF, New Jersey, USA), or 1 -hydroxy cyclohexyl benzophenone (for example, Duracure 1173, Commercially available from Ciba Specialty Chemicals, Inc., New York, USA). Substituted acetophenone is particularly preferable for the ultraviolet photoinitiator. Based on 100 wt% of the total weight of the monomers in the first reaction mixture, an amount of the ultraviolet photoinitiator is in an amount of from 0.001 to 3.0 wt%, preferably from 0.005 to 1.0 wt%, and more preferably from 0.01 to 0.5 wt%.

During the ultraviolet irradiation, the conversion rate of the monomer reaction to the copolymer can be monitored by measuring the refractive index of the polymerization medium of the acid-functional (meth)acrylate copolymer. A suitable coating viscosity is obtained with a conversion rate of up to 30%, preferably from 2% to 20%, more preferably from 5% to 15%, and most preferably from 7% to 12%. The polymer solute has a weight average molecular weight of at least 500,000 Daltons (Daltons, grams per mole), preferably at least 750,000 Daltons, and more preferably at least 1,000,000 Daltons. The polymer solute has a weight average molecular weight of no more than 5,000,000 Daltons, preferably no more than 6,000,000 Daltons, and more preferably no more than 10,000,000 Daltons.

Suitable ultraviolet light sources may include: (1) low intensity light sources such as black light, which typically has an intensity in the wavelength range of from 280 to 400 nanometers of 10 milliwatts per square centimeter or less (for example, an Ultraviolet IMAPTM UM 365 LS radiometer manufactured by Virginia General Electric Instrument Technology Co., Ltd.) measured in accordance with the procedures approved by the United States National Institute of Standards and Technology; or (2) high intensity light sources, such as medium pressure mercury lamps, typically having a strength greater than 10 milliwatts per square centimeter, preferably between 15 and 450 milliwatts per square centimeter. In the case of completely or partially polymerizing the slurry polymer composition using actinic radiation, high strength and short exposure time are preferred. For example, an intensity of 600 mW/cm ² and an exposure time of about 1 second can be used. The strength may range from about 0.1 to 150 mW/cm ² , preferably from about 0.5 to 100 mW/cm ² , and more preferably from about 0.5 to 50 mW/cm ² .

Pressure-sensitive adhesive composition

The pressure-sensitive adhesive composition provided by the present invention includes: (a) the first slurry polymer as described above; (b) an acrylic block copolymer elastomer; and (c) an ultraviolet photoinitiator. In other words, the pressure-sensitive adhesive composition includes a partially polymerized acid functionalized (meth)acrylate copolymer from the first slurry polymer, an unreacted monomer from the first slurry polymer, an acrylic block copolymer elastomer, and an ultraviolet photoinitiator.

More specifically, the pressure-sensitive adhesive composition includes: (a) a first slurry polymer formed from a first reaction mixture; (b) an acrylic block copolymer elastomer; and (c) an ultraviolet photoinitiator. The first reaction mixture used for forming the first slurry polymer includes (1) a non-tertiary alcohol (meth)acrylate monomer; and (2) an acid functional ethyl enically unsaturated monomer. Based on 100 wt% of the total weight of the monomers in the first reaction mixture, the first slurry polymer includes: (i) 1 to 30 wt% of partially polymerized acid functionalized (meth)acrylate copolymer; the partially polymerized acid functionalized (meth)acrylate copolymer has a weight average molecular weight of more than 500,000 g/mol (Dalton); and (ii) 70 to 99 wt% of unreacted monomers.

In the pressure-sensitive adhesive composition provided by the present invention, the description of the first slurry polymer is detailed in "The first slurry polymer" section of this description. In the pressure-sensitive adhesive composition provided by the present invention, the acrylic block copolymer elastomer is an acrylic block copolymer elastomer including an ABA block polymerization unit; the A block polymerization unit (hard block polymerization unit) may be poly(methyl methacrylate); the B block polymerization unit (soft block polymerization unit) may be poly(n-butyl acrylate). In the pressure-sensitive adhesive composition provided by the present invention, based on 100 wt% of the total weight of the first reaction mixture, the amount of the acrylic block copolymer elastomer is from 56 to 110 wt%, preferably from 60 to 100 wt%, more preferably from 65 to 80 wt%, and still more preferably from 65 to 75 wt% (i.e., 100 wt% based on the total weight of the first slurry polymer).

In the pressure-sensitive adhesive composition provided by the present invention, the ultraviolet photoinitiator may include: a scented scent (for example, benzoin or benzoin isopropyl), a substituted benzoin (for example, anthocyanin). The ultraviolet photoinitiator may also be a substituted acetophenone (for example, 2,2-diethoxyacetophenone or 2,2- dimethoxy -2 -phenyl- 1 -acetophenone (commercially available under the trade name IRGACURE 651 from BASF Corporation, New Jersey, USA, or commercially available under the trade name ESACUREKB-l from the Sartomer Corporation of Pennsylvania, USA). The ultraviolet photoinitiator may also be a substituted alpha-keto alcohol (for example, 2-methyl-2-hydroxypropiophenone), an aromatic sulfonyl chloride (for example, 2- cesulfonyl chloride), and a photoactive oxime (for example, 1 -Phenyl- l,2-propanedi one-2- (O-ethoxycarbonyl)anthracene). The ultraviolet photoinitiator may also include: 1 -hydroxy cyclohexyl phenyl ketone (commercially available under the trade name IRGACURE 184 from BASF Corporation, New Jersey, USA), bis (2,4,6- trimethylbenzoyl)phenyl phosphine oxide (commercially available under the trade name IRGACURE 819 from BASF Corporation, New Jersey, USA), l-[4-(2-Hydroxyethoxy)- phenyl]-2-hydroxy-2-methyl-l-propanone (commercially available under the trade name IRGACURE 2959 from BASF Corporation, New Jersey, USA) 2-mercapto-2- (dimethylamino)- l-(4-indolyl phenyl )butanone (commercially available under the trade name IRGACURE 369 from BASF Corporation, New Jersey, USA), 2-Methyl- 1 -[4- (methylthio)phenyl-2-mercapto-propan-l-one (commercially available under the trade name IRGACURE 907 from BASF Corporation, New Jersey, USA), and 2-Hy droxy -2 -methyl- 1- phenylpropan-l-one (commercially available under the trade name DAROCUR 1173 from Ciba Specialty Chemicals, Inc., Tarrytown, NY). In the pressure-sensitive adhesive composition provided by the present invention, based on 100 wt% of the total weight of the first reaction mixture, the amount of the ultraviolet photoinitiator is from 0.001 to 3 wt% (i.e., 100 wt% based on the total amount of the first slurry polymer). Preferably, based on 100 wt% of the total weight of the first reaction mixture, the amount of the ultraviolet photoinitiator is at least 0.001 wt%, at least 0.005 wt%, at least 0.01 wt%, at least 0.05 wt%, or at least 0.1 wt% (i.e., 100 wt% based on the total weight of the first slurry polymer). Preferably, based on 100 wt% of the total weight of the first reaction mixture, the amount of the ultraviolet photoinitiator is up to 3 wt%, up to 2 wt%, up to 1 wt%, or up to 0.5 wt% (i.e., 100 wt% based on the total weight of the first slurry polymer).

The pressure-sensitive adhesive composition provided by the present invention may further include a tackifying resin. The tackifying resin may increase the bond strength of the pressure-sensitive adhesive. Based on 100 wt% of the total weight of the first reaction mixture, (i.e., 100 wt% based on the total weight of the first slurry polymer), the amount of the tackifying resin is up to about 35 wt%, preferably less than 30 wt%, and more preferably, less than 25 wt%. Preferably, based on 100 wt% of the total weight of the first reaction mixture, (i.e., 100 wt% based on the total weight of the first slurry polymer), the amount of the tackifying resin is from 0.01 to 16 wt%. In some embodiments, the tackifying resin may not be used. The premise of using a tackifying resin is that it does not affect the on-line polymerization or the performance of the prepared tape. Tackifying resins may be used alone or in combination. Suitable tackifying resins may include: hydrogenated rosin resin Foral 85 LB (commercially available from Pinova, Georgia, USA), hydrogenated mushroom phenolic resin TH130 (commercially available from Yasuhara Chemical Co., Hiroshima, Japan), or carbon hydrogen resin tackifying resin Regreltz 6108 (commercially available from Eastman Chemical Company, Tennessee, USA). Similarly, in addition to the above conventional tackifying resins, the pressure-sensitive adhesive composition provided by the present invention may also include an acrylate polymer tackifying resin as provided in U.S. Patent No. US20150044457 or Chinese Patent No. CN2014074139.

The pressure-sensitive adhesive composition provided by the present invention may further include a crosslinking agent. The crosslinking agent can improve the cohesive force of the pressure-sensitive adhesive layer prepared by using the pressure-sensitive adhesive composition. A suitable crosslinking agent is a photosensitive crosslinking agent, such as the photosensitive crosslinking agent mentioned in U.S. Patent No. 4,737,559. The photosensitive crosslinking agent can be activated by strong ultraviolet radiation; and the common photosensitive crosslinking agent includes benzophenone and copolymerizable aromatic ketone. Another effective photosensitive crosslinking agent is a triazine (e.g., 2,4- bis(trichloromethyl)-6-(4-methoxyphenyl)-triazine as mentioned in U.S. Patent No. 439, 168), which can be added into the slurry polymer, and activated by ultraviolet light for further crosslinking. Another type of non-photosensitive crosslinking agent is polyfunctional (meth)acrylate (for example, as disclosed in U.S. Patent No. 4,379,201, the addition of poly functional (meth)acrylate to an ultraviolet curing acrylate pressure-sensitive adhesive formulation can effectively increase the cohesive strength of the pressure-sensitive adhesive). Examples of suitable polyfunctional (meth)acrylates may include: di(meth)acrylate, tri(meth)acrylate, or tetra(meth)acrylate (such as l,6-hexanediol di(meth)acrylate, polyethylene glycol) di(meth)acrylate, polybutadiene di(meth)acrylate, polyurethane di(meth)acrylate, or propoxylated tris(meth)acrylate).

The pressure-sensitive adhesive composition provided by the present invention may further include a crosslinking agent. The crosslinking agent is preferably polyfunctional (meth)acrylate. The amount of the crosslinking agent depends on the formulation employed and the performance desired. Preferably, based on 100 wt% of the total weight of the first reaction mixture (i.e., 100 wt% based on the total weight of the first slurry polymer), the amount of the crosslinking agent is from 0.01 to 5 wt%, preferably from 0.01 to 2%, and more preferably from 0.03 to 1 wt%.

The pressure-sensitive adhesive composition provided by the present invention may further include a pigment. The pigment includes, but is not limited to, a black pigment. The black pigment may be selected from 9B117 produced and sold by Penn Color, Pennsylvania, USA. Based on 100 wt% of the total weight of the first reaction mixture (i.e., 100 wt% based on the total weight of the first slurry polymer), the pigment has an amount of from 0.01 to 10 wt%. Based on 100 wt% of the total weight of the first reaction mixture (i.e., 100 wt% based on the total weight of the first slurry polymer), the pigment has an amount of at least 0.5 wt%, or at least 1 wt%. Based on 100 wt% of the total weight of the first reaction mixture (i.e., 100 wt% based on the total weight of the first slurry polymer), the pigment has an amount of at most 10 wt%, at most 8 wt%, or at most 7 wt%. The pressure-sensitive adhesive composition provided by the present invention may further include expanded polymer particles or expanded polymer microspheres, so as to improve the forward drop-impact resistance of the prepared pressure-sensitive adhesive layer. These expanded polymer particles or expanded polymer microspheres typically have a particle size of from 10 to 100 microns. For example, metalized expanded polymer particles provided in Chinese Patent No. CN 104559827 A can be used to impart the desired color appearance and additional foam-like properties to the pressure-sensitive adhesive layer. As another example, the expanded polymer microspheres provided in Chinese patent CN 103320037B can also be used to impart the foam-like properties of the pressure- sensitive adhesive layer, thereby further improving its resistance to forward drop-impact. Based on 100 wt% of the total weight of the first reaction mixture (i.e., 100 wt% based on the total weight of the first slurry polymer), the amount of the expanded polymer particles or expanded polymer microspheres is from 0 to 10 wt%. Preferably, based on 100 wt% of the total weight of the first reaction mixture (i.e., 100 wt% based on the total weight of the first slurry polymer), the amount of the expanded polymer particles or expanded polymer microspheres is at least 0.01 wt%, at least 0.1 wt%, or at least 0.5 wt%. Preferably, based on 100 wt% of the total weight of the first reaction mixture (i.e., 100 wt% based on the total weight of the first slurry polymer), the amount of the expanded polymer particles or expanded polymer microspheres is at most 10 wt%, at most 9 wt%, or at most 8 wt%.

The pressure-sensitive adhesive composition provided by the present invention may further include a plasticizer, a dye, an antioxidant, a coupling agent, a dispersing agent, an anti-settling agent, etc., as long as the properties of the pressure-sensitive adhesive and the pressure-sensitive adhesive layer further prepared by using the pressure- sensitive adhesive composition are not affected. In order to improve the die-cutting performance of the pressure-sensitive adhesive layer, some short synthetic fibers may be added to the pressure-sensitive adhesive composition as long as the drop-impact resistance of the pressure-sensitive adhesive layer is not affected.

Pressure-sensitive adhesive and preparation method thereof

The pressure-sensitive adhesive can be obtained by mixing the components of the pressure-sensitive adhesive composition provided by the present invention. Preferably, the pressure-sensitive adhesive is obtained by mixing the components of the pressure- sensitive adhesive composition provided by the present invention in a glass container at a temperature in the range of from 20 to 30°C and a pressure of 1 atmosphere.

See the section of "The pressure-sensitive adhesive composition" for the description of the pressure-sensitive adhesive composition.

Pressure-sensitive adhesive layer and preparation method thereof

Upon exposure to ultraviolet radiation, the pressure-sensitive adhesive reacts and is cured to form the pressure-sensitive adhesive layer. That is, the pressure-sensitive adhesive layer is a reaction product obtained by exposing the pressure-sensitive adhesive to ultraviolet radiation.

More specifically, the pressure-sensitive adhesive layer is an ultraviolet curing reaction product of the pressure-sensitive adhesive. The pressure-sensitive adhesive is formed by mixing the pressure-sensitive adhesive compositions. See the section of "The pressure- sensitive adhesive composition" for the description of the pressure-sensitive adhesive composition. See the section of "The pressure-sensitive adhesive and preparation method thereof for the description of the pressure-sensitive adhesive.

The ultraviolet radiation may include the steps of: (1) free radical generation: after exposure to ultraviolet light, the ultraviolet light initiator is excited and decomposed to generate free radicals; (2) chain initiation: free radicals generated by the ultraviolet photoinitiator initiate the unsaturated double bonds in the resin and monomer molecules to form new free radicals; (3) chain extension: a free radical generated by a resin and a monomer can further initiate an unsaturated double bond in a resin and a monomer molecule to generate a free radical for a free radical chain reaction; and (4) chain termination: in chemical reactions, free radicals are susceptible to free radical coupling or acidification due to their uncoupled electrons and terminate the chain reaction. As a result of the above reaction, the pressure-sensitive adhesive is cured to form the pressure-sensitive adhesive layer.

There are three suitable UV sources: (1) low-intensity sources, such as black light, typically having an intensity of 10 mW/cm ² or less in the wavelength range of from 280 to 400 nm (for example, measured with an ultraviolet IMAPTM UM 365 L-S radiometer manufactured by General Electronic Instrument Technology Co., Ltd (Virginia, USA) according to the method approved by the United States National Institute of Standards and Technology); (2) high-intensity light sources, such as medium-pressure mercury lamps, typically having an intensity greater than 10 mW/cm ² and having an intensity of up to 600 mW/cm ² or greater; and (3) light emitting diode light (LED), which has many advantages, such as achieving significantly longer life, relatively low heat generation, being environmentally friendly, having lower energy consumption and high intensity. Some UV sources have an intensity of between 15 and 450 mW/cm ² . In some embodiments, shorter exposure times and high intensity ultraviolet radiation can be used. For example, an intensity of 600 mW/cm ² and an exposure time of 1 second can be used. The intensity range can be from 0.1 to 150 mW/cm ² , from 0.5 to 100 mW/cm ² , or from 0.5 to 50 mW/cm ² .

The pressure-sensitive adhesive can be applied to a suitable carrier and the coated pressure-sensitive adhesive composition is then exposed to ultraviolet radiation to form the pressure-sensitive adhesive layer. The carrier can be rigid, flexible, transparent, or opaque, and can be prepared from any suitable material, such as polymeric materials, glass or ceramic materials, metals, and the like. In some preferred embodiments, the carrier can be a polymeric material, such as a flexible polymeric film that can be a flexible backing. Suitable polymeric materials may include: polyalkylenes (e.g., polyethylene, or polypropylene (including isotactic polypropylene)), polystyrene, polyester (e.g., poly(ethylene terephthalate), poly(butylene terephthalate), polylactide, or poly(caprolactam)), nylon, polyvinyl alcohol, poly(vinylidene fluoride), or cellulose (e.g., cellulose acetate or ethyl cellulose). The flexible carrier can have a specific micro structured surface such as those mentioned in US patent Nos. 5141790, 5296277, or 5362516. These microstructured surfaces are typically available through microreplication techniques. The carrier may also be prepared from a fabric such as a fabric formed of synthetic fibers or natural fibers. The fabric may be woven or non-woven. Suitable fibers can include cotton, nylon, rayon, glass, or ceramic. In addition, other suitable carriers may also include metal sheets, metal foils, metalized polymeric films, ceramic sheets, or foams (such as acrylic foams, polyethylene foams, polyurethane foams or neoprene foams).

The pressure-sensitive adhesive composition may be applied to a carrier with any suitable method (for example, roll coating, flow coating, dip coating, spin coating, spray coating, knife coating, or die coating). These different coating methods allow application of various suitable thicknesses of the pressure-sensitive adhesive composition onto the carrier. The coating thickness may vary, and the typical thickness of the pressure-sensitive adhesive layer can range from 2 to 500 microns, and can also range from 25 to 250 microns.

The present invention provides the pressure-sensitive adhesive composition, the pressure-sensitive adhesive, the pressure-sensitive adhesive layer, the method of preparing the pressure-sensitive adhesive, and various embodiments for preparing the pressure- sensitive adhesive layer.

Embodiment 1 provides a pressure-sensitive adhesive composition, including:

(a) a first slurry polymer formed from a first reaction mixture, wherein the first reaction mixture comprises:

(1) a non-tertiary alcohol (meth)acrylate monomer;

(2) an acid functional ethylenically unsaturated monomer;

(3) an alkaline monomer; and

based on 100 wt% of a total weight of the monomers in the first reaction mixture, the first slurry polymer comprises:

(i) 1-30 wt% of partially polymerized acid functionalized (meth)acrylate copolymer, wherein the partially polymerized acid functionalized (meth) acrylate copolymer has a weight average molecular weight of more than 500,000 g/mol (Dalton); and

(ii) 70 to 99 wt% of unreacted monomers;

(b) an acrylic block copolymer elastomer; and

(c) an ultraviolet photoinitiator.

Embodiment 2 provides the pressure-sensitive adhesive composition according to Embodiment 1, wherein based on 100 wt% of the total weight of the monomers in the first reaction mixture, an amount of the non-tertiary alcohol (meth)acrylate monomer is from 40 to 80 wt%.

Embodiment 3 provides the pressure-sensitive adhesive composition according to Embodiment 1 or 2, wherein based on 100 wt% of the total weight of the monomers in the first reaction mixture, an amount of the acid functional ethylenically unsaturated monomer is from 0.1 to 15 wt%.

Embodiment 4 provides the pressure-sensitive adhesive composition according to Embodiments 1 to 3, wherein based on 100 wt% of the total weight of the monomers in the first reaction mixture, an amount of the alkaline monomer is from 19 to 55 wt%. Embodiment 5 provides the pressure-sensitive adhesive composition according to Embodiments 1 to 4, wherein based on 100 wt% of the total weight of the monomers in the first reaction mixture, the pressure-sensitive adhesive composition further comprises 0.01- 5 wt% of a vinyl monomer.

Embodiment 6 provides the pressure-sensitive adhesive composition according to any one of Embodiments 1 to 5, wherein the acrylic block copolymer elastomer comprises a poly(methyl methacrylate) block polymerization unit and a poly(n-butyl acrylate) block polymerization unit.

Embodiment 7 provides the pressure-sensitive adhesive composition according to Embodiments 1 to 6, wherein based on 100 wt% of the total weight of the first reaction mixture, an amount of the acrylic block copolymer elastomer is from 56 to 110 wt%.

Embodiment 8 provides the pressure-sensitive adhesive composition according to Embodiments 1 to 7, wherein based on 100 wt% of the total weight of the first reaction mixture, an amount of the acrylic block copolymer elastomer is from 65 to 75 wt%.

Embodiment 9 provides the pressure-sensitive adhesive composition according to Embodiments 1 to 8, wherein based on 100 wt% of the total weight of the first reaction mixture, an amount of the ultraviolet photoinitiator is from 0.001 to 3 wt%.

Embodiment 10 provides the pressure-sensitive adhesive composition according to Embodiments 1 to 9, wherein based on 100 wt% of the total weight of the first reaction mixture, the pressure-sensitive adhesive composition further comprises 0.01-16 wt% of tackifying resin.

Embodiment 11 provides the pressure-sensitive adhesive composition according to Embodiments 1 to 10, wherein based on 100 wt% of the total weight of the first reaction mixture, the pressure-sensitive adhesive composition further comprises 0.01-5 wt% of a crosslinking agent.

Embodiment 12 provides the pressure-sensitive adhesive composition according to Embodiments 1 to 11, wherein based on 100 wt% of the total weight of the first reaction mixture, the pressure-sensitive adhesive composition further comprises 0.01-10 wt% of expanded polymer particles or expanded polymer microspheres.

Embodiment 13 provides a pressure-sensitive adhesive composition, including: (a) a first slurry polymer formed from a first reaction mixture, wherein based on 100 wt% of the total weight of the monomers in the first reaction mixture, the first reaction mixture comprises:

(1) 40-80 wt% of the non-tertiary alcohol (meth)acrylate monomer;

(2) 0.1-15 wt% of the acid functional ethylenically unsaturated monomer;

(3) 19-55 wt% of the alkaline monomer;

based on 100 wt% of a total weight of the monomers in the first reaction mixture, the first slurry polymer comprises:

(i) 1-30 wt% of partially polymerized acid functionalized (meth)acrylate copolymer, wherein the partially polymerized acid functionalized (meth) acrylate copolymer has a weight average molecular weight of more than 500,000 g/mol (Dalton); and

(ii) 70 to 99 wt% of unreacted monomers;

(b) 56-110 wt% of acrylic block copolymer elastomer based on 100 wt% of the total weight of the first reaction mixture;

(c) 0.001-3 wt% of ultraviolet photoinitiator based on 100 wt% of the total weight of the first reaction mixture.

Embodiment 14 provides the pressure-sensitive adhesive composition according to Embodiment 13, and the pressure-sensitive adhesive composition includes:

(a) a first slurry polymer formed from a first reaction mixture, wherein based on 100 wt% of the total weight of the monomers in the first reaction mixture, the first reaction mixture comprises:

(1) 40-80 wt% of the non-tertiary alcohol (meth)acrylate monomer;

(2) 0.1-15 wt% of the acid functional ethylenically unsaturated monomer;

(3) 19-55 wt% of the alkaline monomer;

based on 100 wt% of a total weight of the monomers in the first reaction mixture, the first slurry polymer comprises:

(i) 1-30 wt% of partially polymerized acid functionalized (meth)acrylate copolymer, wherein the partially polymerized acid functionalized (meth) acrylate copolymer has a weight average molecular weight of more than 500,000 g/mol (Dalton); and

(ii) 70 to 99 wt% of unreacted monomers; (b) 56-110 wt% of acrylic block copolymer elastomer based on 100 wt% of the total weight of the first reaction mixture;

(c) 0.001-3 wt% of ultraviolet photoinitiator based on 100 wt% of the total weight of the first reaction mixture.

(d) 0.01-16 wt% of the tackifying resin based on 100 wt% of the total weight of the first reaction mixture;

(e) 0.01-2 wt% of the crosslinking agent based on 100 wt% of the total weight of the first reaction mixture; and

(f) 0.01-10 wt% of expanded polymer particles or expanded polymer microspheres based on 100 wt% of the total weight of the first reaction mixture.

Embodiment 15 provides a pressure-sensitive adhesive, wherein the pressure- sensitive adhesive includes the mixed pressure-sensitive adhesive composition according to any one of Embodiments 1 to 14.

Embodiment 16 provides a pressure-sensitive adhesive layer, wherein the pressure-sensitive adhesive layer includes an ultraviolet curing reaction product of the pressure-sensitive adhesive according to Embodiment 15.

Embodiment 17 provides a method for preparing a pressure-sensitive adhesive, wherein the method includes a step of: mixing the pressure-sensitive adhesive composition of any one of Embodiments 1 to 14.

Embodiment 18 provides a method for preparing a pressure-sensitive adhesive layer, wherein the method includes a step of: performing ultraviolet radiation to cure the pressure-sensitive adhesive according to Embodiment 15.

Embodiments

The objectives and advantages of the present invention will be further illustrated with reference to the following embodiments. The specific materials, amounts and other conditions and details of the following embodiments are set forth to illustrate the present invention and should not be construed as limiting the invention in any way. Percentages, ratios, parts, and the like referred to in the present disclosure are by weight, unless otherwise indicated.

All amounts are expressed as wt% unless otherwise indicated. Table 1: Material terms

Test Method

The performance tests performed on and characterizations of the pressure-sensitive adhesive layer samples provided in the embodiments and comparative examples of the present invention are carried out in accordance with the following test methods.

Glass transition temperature (T ) determination

The glass transition temperature (Tg) is determined by using a differential scanning calorimeter (DSC) (Q100, commercially available from TA Co. Ltd., Delaware, USA). Each sample is lowered to -80°C, maintained at -80°C for 2 minutes, and then heated to 40°C (or to l00°C) at a rate of lO°C/minute. Tg corresponds to the peak temperature from the glassy state to the liquid state.

Percent conversion rate determination

The slurry polymer conversion percentage is determined by measuring the solid content (solid%). The measurement process includes: weighing each sample in an aluminum plate; heating the sample in an oven through forced convection heating for 60±30 minutes under the condition of " l05±3°C"; removing the sample out of the oven; cooling the sample for 5 minutes; and then weighing the sample. The following equation is used to calculate the conversion percentage.

Solid% = [(Ml - M2) - Ml] x 100%

In this equation, Ml refers to the mass of the sample before heating, and M2 refers to the mass of the sample after heating. Ml and M2 do not include the weight of the aluminum plate.

Molecular weight determination

The molecular weight (Mw) of the (meth)acrylate tackifier and partially polymerized acid functionalized (meth)acrylate copolymer can be measured by using gel permeation chromatography (GPC) with an instrument commercially available from Wdters Co. Ltd., (Milford, MA, USA). The measurement procedure consists of weighing 0.1 gram of the sample, placing the sample in a 5 mL vial, and dissolving the sample with 3 mL of tetrahydrofuran; further diluting the sample as needed for chromatographic analysis; filtering the sample solution through a 0.45 micron membrane; injecting the filtered solution into the GPC and calculating the Mw; calibrating GPC by using polystyrene standards of known molecular weight and establishing a calibration curve by using linear least squares analysis.

Drop-impact resistance test

Test samples for drop-impact resistance are shown in FIG. 1. The preparation procedure for this test sample is as follows: taking two polymethyl methyl acrylate plates (PMMA plate, size 108 mm (length) x 57 mm (width) x 6 mm (height), weight 38 g) 100 and 300; removing the protective film on one side respectively; wiping it three times with isopropyl alcohol (commercially available from Sinopharm Chemical Reagent Co., Ltd., Shanghai, China) and ensuring that the solvent is completely evaporated; using a cutting knife to carefully cut two 1.5 mm x 15 mm sample strips 200 from the tape sample (film or double- sided tape); and removing the release paper (film) on one side; adhering the sample strips to the ends of one of the PMMA plates 100 in a direction parallel to the width; and carefully pressing them with a rubber roller to avoid air bubbles between the bonding faces, the edge of the tape being 5 mm away from the edge of the PMMA plate 100; and cutting off the excess parts at both ends of the tape; removing the other release paper (film) of the above two tape samples; and aligning the two sides of the cleaning surface of the other PMMA plate 300 to the two sides of the PMMA plate; and bonding the two plates together by using the tapes 200; placing a 4 kg weight (of the same area as the PMMA plate) on the above two PMMA plates for 30 seconds; and finally performing the drop-impact resistance test on the to-be-tested sample after the sample is placed under the conditions of "23 +/- 2°C and a relative humidity of 50 +/- 5 %" for 24 hours.

The test method for drop-impact resistance is shown in FIGs. 2a and 2b. During the test, the above samples are subjected to the shear resistance and drop-impact test and the forward drop-impact test in the directions respectively shown in FIGs. 2a and 2b, where the drop height is 2 meters, and the ground is cement floor. The number of drops when a failure occurs (the drop is repeated three times, and the number of failures is averaged) and the failure mode (P0 means that the pressure-sensitive adhesive layer is detached from PMMA; FS means foam layering, 2-Bond means that the film is falling off from the intermediate substrate) are recorded. Shear resistance and drop-impact is used to simulate the lateral drop of handheld electronic devices such as mobile phones, while forward drop-impact is used to simulate the forward drop of handheld electronic devices such as mobile phones.

Preparation of the first slurry polymers S-l, S-2, S-3, S-4, S-5, and S-6

Six first slurry polymers (S-l, S-2, S-3, S-4, S-5, and S-6) are prepared. For each sample, the monomers of the types and amounts listed in Table 2 are placed in a 1 quart glass jar. An ultraviolet photoinitiator IRGACURE 651 (0.04 phr, equivalent to 0.04 wt%, based on 100 wt% of the total weight of the monomers in the first slurry polymer) is added to the monomer of each sample. Each mixture is purged with nitrogen for 15 minutes under magnetic stirring and then exposed to a low intensity ultraviolet ray source (365 nm, with an intensity of about 1.5 mW/cm ² ) until a slurry polymer having a viscosity of about 500-5,000 centipoise at room temperature (RT) is obtained. The conversion rate of S-l is 7.7%; the conversion rate of S-2 is 5.3%; the conversion rate of S-3 is 6.2%; the conversion rate of S-4 is 8.5%; the conversion rate of S-5 is 4.1%; and the conversion rate of S-6 is 9.7%. The conversion rate here is the weight percent of the partially polymerized acid functional (meth)acrylate copolymer (i.e., the conversion rate and weight percent are numerically consistent). The Mw of S-l is 3,491,000 g/mol; the Mw of S-2 is 5,208,000 g/mol; the Mw of S-3 is 6,236,000 g/mol; the Mw of S-4 is 1,152,000 g/mol; the Mw of S-5 is 2,364,000 g/mol; and the Mw of S-6 is 4,215,000 g/mol. These Mw (molecular weight) are determined by using the GPC.

Table 2: Compositions of the first slurry polymers S-l, S-2, S-3, S-4, S-5 and S-6

Embodiments 1-6 and Comparative Examples C1-C5

Per the formula of Table 3a, the slurry polymer S-l, the black pigment 9B 117, the photoinitiator Irgacure 651, the multifunctional acrylate HDD A, and the tackifying resin Foral 85LB were added to a 1 quart wide-mouth glass bottle while being stirred at high speed (800 rpm); stirring thoroughly to disperse the components evenly; adding the acrylic block copolymer elastomer LA2330 to fully dissolve the components; if the formulation contains expanded polymeric microspheres, adding the expanded polymeric microspheres to distribute the microspheres uniformly therein to obtain a pressure-sensitive adhesive. The values in Table 3 a are all based on 100 wt% of the total weight of the slurry polymer S-l .

The prepared pressure-sensitive adhesive was applied onto the surfaces of the two release films of CP Film T10 PET (commercially available from Solutia, Tennessee, ETSA) having a thickness of 0.05 mm. The thickness of the film was controlled to be 0.15 mm, and complete polymerization was carried out through irradiation with the aforementioned low- intensity ultraviolet light (365 nm, 1.5 mW/cm ² ) for 5 to 10 minutes to obtain an acrylate pressure-sensitive adhesive layer. Specifically, in order to improve the performance of the pressure-sensitive adhesive tape, for Embodiments 2 and 3, when a pressure-sensitive adhesive is applied, a layer of Cerex 23030 nylon fabric (commercially available from Cerex Performance Fibers, Inc., Florida, ETSA) may be added.

Both sides of the above acrylate pressure-sensitive adhesive layer were each coated with a layer of a primer, and the composition thereof includes a solute: Macromelt 6240 (Henkel, Diisseldorf, Germany); a solvent: 47.5 parts by weight of isopropanol (Sinopharm Chemical Reagent Co. Ltd., Shanghai, China), 47.5 parts by weight of n- propanol (Sinopharm Chemical Reagent Co. Ltd., Shanghai, China), 5 parts by weight of water; solute content is 10%. After 10 min of drying at 80°C, a prime coat of a thickness of 5 pm to 10 pm could be obtained.

A pressure sensitive adhesive tapes 9458 (3M Corporation, Minnesota State, U.S.A.) with a thickness of 0.025 mm were respectively applied onto the undercoat layer at both sides; and pressed by hand with a 2-kg rubber roller to obtain a double-sided adhesive tape with a total thickness of 0.20 mm.

The structure of the tape provided in Embodiment 1 is as shown in FIG. 3, including, from bottom to top, a backing layer 40 (the backing layer of the pressure-sensitive adhesive tape 9482PC) and the pressure-sensitive adhesive layer 30, (the pressure-sensitive adhesive layer of pressure-sensitive adhesive tape 9482PC), the undercoat layer 20, the pressure- sensitive adhesive layer 10 provided by the present invention, the undercoat layer 20, the pressure-sensitive adhesive layer 30 (the pressure-sensitive adhesive layer of the pressure- sensitive adhesive tape 9482PC), the backing layer 40 (the backing layer of the pressure- sensitive adhesive tape 9482PC).

Embodiment 2 includes Embodiments 2a, 2b, and 2c.In the Embodiments 2a, 2b, and 2c, the pressure-sensitive adhesive layer 10 has the same formulation; the structures of the tapes, however, are different. The structure of the tape provided in Embodiment 2a is as shown in FIG. 4a, including, from bottom to top, a backing layer 40 (the backing layer of the pressure-sensitive adhesive tape 9482PC), a pressure-sensitive adhesive layer 30 (the pressure-sensitive adhesive layer of the pressure-sensitive adhesive tape 9482PC), an undercoat layer 20, the pressure- sensitive adhesive layer 10, the undercoat layer 20, and the pressure-sensitive adhesive layer 30 provided by the present invention (the pressure-sensitive adhesive layer of the pressure-sensitive adhesive tape 9482PC), the backing layer 40 (the backing layer of the pressure-sensitive adhesive tape 9482PC); a nylon fabric 50 (Cerex 23030 nylon fabric) is included in the pressure- sensitive adhesive layer 10. The structure of the tape provided in Embodiment 2b is as shown in FIG. 4b, and includes the pressure-sensitive adhesive layer 10 provided by the present invention; the pressure-sensitive adhesive layer 10 includes a nylon fabric 50 (the Cerex 23030 nylon fabric). The structure of the tape provided in Embodiment 2c is as shown in FIG. 4c, and includes the pressure-sensitive adhesive layer 10 provided by the present invention.

Embodiment 3 includes Embodiments 3 a, 3b, and 3 c. In the Embodiments 3 a, 3b, and 3c, the pressure-sensitive adhesive layer 10 has the same formulation; the structures of the tapes, however, are different. The structure of the tape provided in Embodiment 3a is as shown in FIG. 4a, including, from bottom to top, a backing layer 40 (the backing layer of the pressure-sensitive adhesive tape 9482PC), a pressure-sensitive adhesive layer 30 (the pressure-sensitive adhesive layer of the pressure-sensitive adhesive tape 9482PC), an undercoat layer 20, the pressure- sensitive adhesive layer 10, the undercoat layer 20, and the pressure-sensitive adhesive layer 30 provided by the present invention (the pressure-sensitive adhesive layer of the pressure-sensitive adhesive tape 9482PC), the backing layer 40 (the backing layer of the pressure-sensitive adhesive tape 9482PC); a nylon fabric 50 (Cerex 23030 nylon fabric) is included in the pressure- sensitive adhesive layer 10. The structure of the tape provided in Embodiment 3b is as shown in FIG. 4b, and includes the pressure-sensitive adhesive layer 10 provided by the present invention; the pressure-sensitive adhesive layer 10 includes a nylon fabric 50 (the Cerex 23030 nylon fabric). The structure of the tape provided in Embodiment 3c is as shown in FIG. 4c, and includes the pressure-sensitive adhesive layer 10 provided by the present invention.

The structures of the tapes provided in Embodiments 4-6 and Comparative Examples C1-C4 are as shown in FIG. 3, and include, from bottom to top, a backing layer 40 (the backing layer of the pressure-sensitive adhesive tape 9482PC) and the pressure-sensitive adhesive layer 30, (the pressure-sensitive adhesive layer of pressure-sensitive adhesive tape 9482PC), the undercoat layer 20, the pressure-sensitive adhesive layer 10 provided by the present invention, the undercoat layer 20, the pressure-sensitive adhesive layer 30 (the pressure-sensitive adhesive layer of the pressure-sensitive adhesive tape 9482PC), the backing layer 40 (the backing layer of the pressure-sensitive adhesive tape 9482PC).

The structure of the tape provided in Comparative Example C5 is as shown in Fig. 5, and includes, from bottom to top, a backing layer 40 (backing layer of pressure-sensitive adhesive tape 9482PC), the pressure-sensitive adhesive layer 30 (the pressure-sensitive adhesive layer of the pressure-sensitive adhesive tape 9482PC), black polyethylene (PE) foam 60, the pressure-sensitive adhesive layer 30 (the pressure-sensitive adhesive layer of the pressure-sensitive adhesive tape 9482PC), the backing layer 40 (the backing layer of the pressure-sensitive tape 9482PC). The preparation method is as follows: a black polyethylene (PE) foam having a thickness of 0.15 mm (commercially available from Hubei Xiangyuan New Material Technology Co., Ltd., Xiaogan City, Hubei Province, China) was respectively covered with a pressure-sensitive tape 9482PC; double-sided corona treatment (Softal corona machine, Hamburg, Germany) was performed before the bonding, the surface energy being greater than 52 dynes/cm; and hand-pressing with a 2 kg rubber roller was performed to ensure that the film and the polyethylene foams were completely bonded to each other to obtain a double-sided foam tape having a total thickness of 0.20 mm.

After the above various samples were stood in the conditions of the temperature being at 23±2°C and the relative humidity being 50±5% for 24 h, they were tested for the drop- impact resistance. The results are shown in Table 3b.

Table 3 a Compositions of Embodiments 1-6 and Comparative Examples C1-C4

Table 3b Drop-impact resistance of the pressure-sensitive adhesive tapes provided by

Embodiments 1-6 and Comparative Examples C1-C5

The data in Table 3a and Table 3b show that the pressure-sensitive adhesive layers in comparative Examples Cl, C2, and C4 contain insufficient acrylate elastomer, leading to the corresponding pressure-sensitive adhesive tapes having insufficient shear and drop-impact resistance.

In the tapes provided in Embodiments 1-6, the pressure-sensitive adhesive layer contains an appropriate amount of acrylate elastomer (all of which is 60 parts by weight or more); as a result, the tapes have good shear and drop-impact resistance.

In the tapes provided in Embodiments 1, 2a, 2b, 2c, 3a, 3b, 3c, 5, and 6, the pressure-sensitive adhesive layers contain the dissolved expanded polymer microspheres. The tapes provided by these Embodiments therefore not only have good shear and drop- impact resistance, they also have good forward drop-impact resistance.

Embodiments 7 and Comparative Examples C6-C8

Per the formula in Table 4a, the slurry polymer S-2, the black pigment 9B1 17, the photoinitiator Irgacure 651, and the multifunctional acrylate HDD A were added to a 1 quart wide-mouth glass bottle while being stirred at high speed (800 rpm); stirring thoroughly to disperse the components evenly; adding the acrylic block copolymer elastomer LA2140 to fully dissolve the components; finally the expanded polymer microspheres 46lDE20d70 were added therein to have the microspheres fully dissolved, so as to obtain a pressure-sensitive adhesive. The values in Table 4a are all based on 100 wt% of the total weight of the slurry polymer S-2.

The prepared pressure-sensitive adhesive was applied onto the release surfaces of the two release films of CP Film T10 PET (commercially available from Solutia, Tennessee, ETSA) having a thickness of 0.05 mm. The thickness of the adhesive film was controlled to be 0.10 mm, and complete polymerization was carried out through irradiation with the aforementioned low-intensity ultraviolet light (365 nm, 1.5 mW/cm ² ) for 5 to 10 minutes to obtain an acrylate pressure-sensitive adhesive layer.

A layer of primer was applied to both sides of the above acrylate pressure-sensitive adhesive layer (the primer is the same as the primer in Embodiments 1-7); then, a pressure- sensitive adhesive tape 9458 (3M Company, Minnesota, ETSA) having a thickness of 0.025 mm was applied onto the undercoat layers on both sides to obtain a double-sided tape having a total thickness of 0.15 mm. The stmctures of the tapes provided in Embodiment 7 and Comparative Examples C6- C7 are as shown in FIG. 3, and include, from bottom to top, a backing layer 40 (the backing layer of the pressure-sensitive adhesive tape 9458), the pressure-sensitive adhesive layer 30, (the pressure-sensitive adhesive layer of pressure-sensitive adhesive tape 9458), the undercoat layer 20, the pressure-sensitive adhesive layer 10 provided by the present invention, the undercoat layer 20, the pressure-sensitive adhesive layer 30 (the pressure-sensitive adhesive layer of the pressure-sensitive adhesive tape 9458), the backing layer 40 (the backing layer of the pressure- sensitive adhesive tape 9458).

The structure of the tape provided in Comparative Example C8 is as shown in Fig. 5, and includes, from bottom to top, a backing layer 40 (backing layer of pressure-sensitive adhesive tape 9458), the pressure-sensitive adhesive layer 30 (the pressure-sensitive adhesive layer of the pressure-sensitive adhesive tape 9458), black polyethylene (PE) foam 60, the pressure-sensitive adhesive layer 30 (the pressure-sensitive adhesive layer of the pressure-sensitive adhesive tape 9458), the backing layer 40 (the backing layer of the pressure-sensitive tape 9458). The preparation method is as follows: a black polyethylene (PE) foam having a thickness of 0.10 mm (commercially available from Hubei Xiangyuan New Material Technology Co., Ltd., Xiaogan City, Hubei Province, China) was respectively covered with a pressure-sensitive tape 9458; double-sided corona treatment (Softal corona machine, Hamburg, Germany) was performed before the bonding, the surface energy being greater than 52 dynes/cm; and hand-pressing with a 2 kg rubber roller was performed to ensure that the film and the polyethylene foams were completely bonded to each other to obtain a double-sided foam tape having a total thickness of 0.15 mm.

After the above various samples were stood in the conditions of the temperature being at 23±2°C and the relative humidity being 50±5% for 24 h, they were tested for the drop-impact resistance. The results are shown in Table 4b.

Table 4a Compositions of Embodiment 7 and Comparative Examples C6-C8

Table 4b Comparisons of drop-impact resistance of pressure-sensitive tapes of

Embodiment 7 and Comparative examples C6-C8

The data in Table 4a and Table 4b show that the acrylate elastomer contained in the pressure-sensitive adhesive layer in the adhesive tapes provided by Comparative Examples C6 and C7 is insufficient, leading to the adhesive tapes having insufficient shear and drop-impact resistance.

The tape provided in Comparative Example C8 is based on polyethylene foam; the tape therefore has insufficient shear and drop-impact resistance.

In the tape provided in Embodiment 7, the pressure-sensitive adhesive layer contains an appropriate amount of acrylate elastomer (equal to 65 parts by weight); as a result, the tape has good shear and drop-impact resistance.

Embodiments 8 and Comparative Examples C9-C10

Per the formula in Table 5a, the slurry polymer S-3, the black pigment 9B117, the photoinitiator Irgacure 651, and the multifunctional acrylate HDD A were added to a 1 quart wide-mouth glass bottle while being stirred at high speed (800 rpm); stirring thoroughly to disperse the components evenly; adding the acrylic block copolymer elastomer LA2140 to fully dissolve the components; finally the expanded polymer microspheres 46lDE20d70 were added therein to have the microspheres fully dissolved, so as to obtain a pressure-sensitive adhesive. The values in Table 5a are all based on 100 wt% of the total weight of the slurry polymer S-3.

The above solution was applied onto the release surfaces of the two release films of CP Film T10 PET having a thickness of 0.05 mm. The thickness of the adhesive film was controlled to be 0.10 mm, and complete polymerization was carried out through irradiation with the aforementioned low-intensity ultraviolet light (365 nm, 1.5 mW/cm2) for 5 to 10 minutes to obtain an acrylate pressure-sensitive adhesive layer. The stmcture of the tapes provided in Embodiment 8 and Comparative Examples C9- C10 is as shown in FIG. 4c and includes: the pressure-sensitive adhesive layer 10 provided by the present invention.

After the above various samples were stood in the conditions of the temperature being at 23±2°C and the relative humidity being 50±5% for 24 h, they were tested for the drop-impact resistance. The results are shown in the table.

Table 5a Compositions of Embodiment 8 and Comparative Examples C9-C10

Table 5b Comparisons of drop-impact resistance of pressure-sensitive tapes of

Embodiment 8 and Comparative examples C9-C10

The data in Table 5a and Table 5b show that the acrylate elastomer contained in the pressure-sensitive adhesive layer in the adhesive tapes provided by Comparative Examples C9 and C10 is insufficient, leading to the adhesive tapes having insufficient shear and drop-impact resistance.

In the tape provided in Embodiment 8, the pressure-sensitive adhesive layer contains an appropriate amount of acrylate elastomer (equal to 60 parts by weight); as a result, the corresponding pressure-sensitive adhesive tape has good shear and drop-impact resistance. Embodiments 9-10 and Comparative Examples Cl 1

Per the formula in Table 6a, the slurry polymer S-4, the black pigment 9B117, the photoinitiator Irgacure 651, and the multifunctional acrylate DPHA were added to a 1 quart wide-mouth glass bottle while being stirred at high speed (800 rpm); stirring thoroughly to disperse the components evenly; adding the acrylic block copolymer elastomer LA2250 and the expanded polymer microspheres 46lDE20d70 therein to have the components fully dissolved, so as to obtain a pressure-sensitive adhesive. The values in Table 6a are all based on 100 wt% of the total weight of the slurry polymer S-4.

The prepared pressure-sensitive adhesive was applied onto the release surfaces of the two release films of CP Film T10 PET (commercially available from Solutia, Tennessee, USA) having a thickness of 0.05 mm. The thickness of the adhesive film was controlled to be 0.10 mm, and complete polymerization was carried out through irradiation with the aforementioned low-intensity ultraviolet light (365 nm, 1.5 mW/cm ² ) for 5 to 10 minutes to obtain an acrylate pressure-sensitive adhesive layer.

A layer of primer was applied to both sides of the above acrylate pressure-sensitive adhesive layer (the primer is the same as the primer in Embodiments 1-7); then, a pressure- sensitive adhesive tape 9458 (3M Company, Minnesota, USA) having a thickness of 0.025 mm was applied onto the undercoat layers on both sides to obtain a double-sided tape having a total thickness of 0.15 mm.

The structures of the tapes provided in Embodiments 9-10 and Comparative Example Cl 1 are as shown in FIG. 3, and include, from bottom to top, a backing layer 40 (the backing layer of the pressure-sensitive adhesive tape 9458), the pressure-sensitive adhesive layer 30, (the pressure-sensitive adhesive layer of pressure-sensitive adhesive tape 9458), the undercoat layer 20, the pressure-sensitive adhesive layer 10 provided by the present invention, the undercoat layer 20, the pressure-sensitive adhesive layer 30 (the pressure-sensitive adhesive layer of the pressure-sensitive adhesive tape 9458), the backing layer 40 (the backing layer of the pressure- sensitive adhesive tape 9458).

After the above various samples were stood in the conditions of the temperature being at 23±2°C and the relative humidity being 50±5% for 24 h, they were tested for the drop-impact resistance. The results are shown in Table 6b.

Table 6a Compositions of Embodiments 9-10 and Comparative Example Cl 1

Table 6b Comparisons of drop-impact resistance of pressure-sensitive tapes of Embodiments 9-10 and Comparative example Cl 1

The data in Table 6a and Table 6b show that the acrylate elastomer contained in the pressure-sensitive adhesive layer in the adhesive tape provided by Comparative Example Cl 1 is insufficient, leading to the adhesive tapes having insufficient shear and drop-impact resistance.

In the tapes provided in Embodiments 9-10, the pressure-sensitive adhesive layer contains an appropriate amount of acrylate elastomer (all of which is 56 parts by weight or more); as a result, the tapes have good shear and drop-impact resistance.

Further, the test results for Embodiments 9 and 10 indicate that increasing the acrylate elastomer within a certain range in the pressure-sensitive adhesive layer can effectively improve the shear drop-impact resistance of the tape and maintain its forward drop-impact resistance.

Embodiments 11-13

Per the formula in Table 7a, the slurry polymer S-5, the black pigment 9B117, the photoinitiator Irgacure 651, and the multifunctional acrylate DPHA were added to a 1 quart wide-mouth glass bottle while being stirred at high speed (800 rpm); stirring thoroughly to disperse the components evenly; adding the acrylic block copolymer elastomer therein to fully dissolve the components; finally the expanded polymer microspheres FN-80SDE were added therein to have the microspheres uniformly dispersed, so as to obtain a pressure- sensitive adhesive. The values in Table 7a are all based on 100 wt% of the total weight of the slurry polymer S-5.

The prepared pressure-sensitive adhesive was applied onto the release surfaces of the two release films of CP Film T10 PET (commercially available from Solutia, Tennessee, ETSA) having a thickness of 0.05 mm. The thickness of the adhesive film was controlled to be 0.20 mm, and complete polymerization was carried out through irradiation with the aforementioned low-intensity ultraviolet light (365 nm, 1.5 mW/cm ² ) for 5 to 10 minutes to obtain an acrylate pressure-sensitive adhesive layer.

A layer of primer was applied to both sides of the above acrylate pressure-sensitive adhesive layer (the primer is the same as the primer in Embodiments 1-7); then, a pressure- sensitive adhesive tape 467MP (3M Company, Minnesota, USA) having a thickness of 0.05 mm was applied onto the undercoat layers on both sides to obtain a double-sided tape having a total thickness of 0.30 mm.

The structure of the tapes provided by the Embodiments 11-13 is as shown in FIG. 3, and includes, from bottom to top: a backing layer 40 (the backing layer of the pressure- sensitive adhesive tape 467MP), a pressure-sensitive adhesive layer 30 (the pressure- sensitive adhesive layer of the pressure-sensitive tape 467MP), an undercoat layer 20, and a pressure-sensitive adhesive layer 10 provided by the present invention, an undercoat layer 20, and a pressure-sensitive adhesive layer 30 (the pressure-sensitive adhesive layer of the pressure-sensitive adhesive tape 467MP), a backing layer 40 (the backing layer of the pressure-sensitive adhesive tape 467MP).

After the above various samples were stood in the conditions of the temperature being at 23±2°C and the relative humidity being 50±5% for 24 h, they were tested for the drop-impact resistance. The results are shown in Table 7b.

Table 7a Compositions of Embodiments 11-13

Table 7b Comparisons of drop-impact resistance of pressure-sensitive tapes of Embodiments

14-16

The data in Table 7a and Table 7b show that in the tapes provided in Embodiments 11-13, the pressure-sensitive adhesive layer contains a sufficient amount of acrylate elastomer (equivalent to 65 parts by weight). Therefore, the tape has good shear and drop- impact resistance.

In addition, in the tapes provided in Embodiments 12 and 13, the pressure-sensitive adhesive layer contains two different acrylic block copolymer elastomers. As a result, the tapes not only have good shear and drop-impact resistance, they also have good forward drop-impact resistance.

Embodiment 14 and Comparative Example C12

Per the formula in Table 8a, the slurry polymer S-6, the black pigment 9B1 17, the photoinitiator Irgacure 651, and the multifunctional acrylate DPHA were added to a 1 quart wide-mouth glass bottle while being stirred at high speed (800 rpm); stirring thoroughly to disperse the components evenly; adding the acrylic block copolymer elastomer LA2140 to fully dissolve the components; finally the expanded polymer microspheres 46lDET80d25 were added therein to have the microspheres fully dissolved, so as to obtain a pressure-sensitive adhesive. The values in Table 8a are all based on 100 wt% of the total weight of the slurry polymer S-6.

The prepared pressure-sensitive adhesive was applied onto the release surfaces of the two release films of CP Film T10 PET (commercially available from Solutia, Tennessee, ETSA) having a thickness of 0.05 mm. The thickness of the adhesive film was controlled to be 0.30 mm, and complete polymerization was carried out through irradiation with the aforementioned low-intensity ultraviolet light (365 nm, 1.5 mW/cm ² ) for 5 to 10 minutes to obtain an acrylate pressure-sensitive adhesive layer.

A layer of primer was applied to both sides of the above acrylate pressure-sensitive adhesive layer (the primer is the same as the primer in Embodiments 1-7); then, a pressure- sensitive adhesive tape 9471LE (3M Company, Minnesota, ETSA) having a thickness of 0.05 mm was applied onto the undercoat layers on both sides to obtain a double-sided tape having a total thickness of 0.40 mm.

The structures of the tapes provided in Embodiment 14 and Comparative Example C12 are as shown in FIG. 3, and include, from bottom to top, a backing layer 40 (the backing layer of the pressure-sensitive adhesive tape 9471LE) and the pressure-sensitive adhesive layer 30, (the pressure-sensitive adhesive layer of pressure-sensitive adhesive tape 9471LE), the undercoat layer 20, the pressure-sensitive adhesive layer 10 provided by the present invention, the undercoat layer 20, the pressure-sensitive adhesive layer 30 (the pressure-sensitive adhesive layer of the pressure-sensitive adhesive tape 9471LE), the backing layer 40 (the backing layer of the pressure-sensitive adhesive tape 9471LE).

After the above various samples were stood in the conditions of the temperature being at 23±2°C and the relative humidity being 50±5 % for 24 h, they were tested for the drop-impact resistance. The results are shown in Table 8b.

Table 8a Compositions of Embodiment 14 and Comparative Example C12

Table 8b Comparisons of drop-impact resistance of pressure-sensitive tapes of

Embodiment 14 and Comparative example C12

The data in Table 6a and Table 8b show that the acrylate elastomer contained in the pressure-sensitive adhesive layer in the pressure-sensitive adhesive tape provided by Comparative Example C12 is insufficient, leading to the adhesive tapes having insufficient shear and drop-impact resistance.

In the tape provided in Embodiment 14, the pressure-sensitive adhesive layer contains an appropriate amount of acrylate elastomer (equal to 65 parts by weight); as a result, the tape has good shear and drop-impact resistance.

In conclusion, the pressure-sensitive adhesive layer provided by the present invention at least has great shear strength and drop-impact resistance.