This invention relates to substantially non-aqueous acoustic sealant compositions exhibiting superior sound dampening properties consisting essentially of a polymeric component in combination with a major level of a benzoate plasticizer. In more detail, the compositions herein primarily contain a ternary essential component matrix, to wit: a major level of a polymeric component; a major amount of a benzoate plasticizer and additives including fillers, solvents, pigments and adhesion promoters. The polymeric component can be selected from polyvinylchloride, acrylic polymers and cured epoxy resins. The benzoate plasticizer can be used as such or, optionally, in combination with conventional plasticizers, with the proviso that the benzoate species represents, at least 30 % by weight or more of the total plasticizer (100 %) . In preferred executions, the benzoate plasticizer can be represented by a dibenzoate in combination with a mono-benzoate plasticizer. In another approach, the benzoate plasticizer ^■ can be used beneficially in combination with substantial levels of conventional plasticizers other than benzyl phthalates or with levels of benzylphthalate plasticizers.

Various technologies aiming at mitigating acoustic nuisances are known and have found established commercial application. The pertinent state of the art, and its shortcomings, is consequently well known. Japanese patent

application JP 10237250 discloses coating compositions with good sound insulating properties containing vinyl chloride polymers in combination with a mixture of conventional plasticizers, namely diheptyl phthalate and diisononyl phthalate, fillers and additives. Japanese patent application JP 10237249 discloses comparable compositions having sound insulating properties containing vinyl chloride resins, phthalate plasticizers, fillers, liquid asphalt and adhesives. Japanese patent application JP 05279623 describes compositions for automotive application comprising elastomers embodying vinyl polymer and diolefin polymer blocks and hydrogenated indene resins. RO 100918 patent application pertains to anticorrosive and sound absorbing epoxy resin compositions prepared by mixing epoxy resin, butyl glycidyl and phenyl glycidyl ethers and dehydrated coal tar pitch. Japanese patent application JP 03144195 concerns compositions for vibration damping and sound attenuation containing a bituminous sheet and a thermosetting resin layer, optionally protected with an outer layer. The resin layer contains an epoxy resin and fillers. WO 99/58597 divulges water-based acoustic dampening compostions containing acrylic resin-based plastisol into which is incorporated a recycled paint polymer containing uncured resin and conventional plasticizers. DE 43 18 712 describes sprayable plastisol formulations exhibiting acoustic dampening properties. These formulations contain a major level of a crosslinkable, during application, mixture of a styrene polymer and a major level of a plasticizer together with fillers, reactive additives and other components in additicve levels which are used for their established

functionality within the borders of plastisol technologies. The plasticizers are conventional. JP 2000-169756 pertains to known automotive coatings capable of providing a barrier against corrosion, mechanical damage and high frequency noise originating from factors different from the automotive body e.g. stone projections. The JP technology provides, in an incidental manner, acoustic dampening at very low temperatures, contrary to the object of the inventive technology seeking significantly enhanced dampening over a completely different range of temperatures, namely ambient temperatures of from 0 to 50 ⁰ C. JP 05009355 discloses a plastisol composition consisting of a vinyl chloride-type resin and a plasticizer containing a major amount of a benzoic acid ester of a CT _-15 alkylene glycol or a C _4-12 oxy-alkylene glycol. The composition can be used as a coating on cars to provide a barrier against chipping and mechanical damage originating from sources different from the automotive body. EP 0 416 822 describes esters from a specific class of pentanediols and benzoic acid/alkyl-substituted benzoic acid. These esters are used as stain-resistant plasticizers in floor coverings. These esters impart, upon use in plastisols, a high degree of stain resistance and stable viscosity properties during storage. The esters can also be used as synthetic lubricants and as functional fluids such as automatic transmission fluids.

The prior art is, as shown above, diverse and expresses a standing desire for optimizing, improving and mitigating acoustic inconveniences, for example in relation to automotive application.

It is a major object of this invention to provide compositions exhibiting superior sound dampening properties. It is another object of this invention to provide sound dampening compositions primarily based on non-phthalate plasticizers . Yet another object of this invention aims at providing compositions exhibiting superior sound dampening compared to comparable formulations containing conventional plasticizers. Yet a further object of this invention aims at dampening acoustic inconveniences of low frequencies, usually in the range of from 20 to 500 Hz, at ambient temperature e.g. in the range of from 0 to 50 ⁰ C. Yet another object of the invention aims at mitigating the adsorption of low frequency noise originating from the automotive body. The above and other objects can now be achieved by means of the inventive technology described hereinafter.

The "percentage" or "%" indications used in the description stand, unless defined differently, for "percent by weight" .

It has now been discovered that beneficially superior, nonaqueous, easily applicable, particularly sprayable, acoustic sealant compositions can be formulated. In more detail, the compositions herein are substantially nonaqueous sealants, particularly suitable for automotive application, and consist essentially of:

(a) from about 20 % to about 80 % of a polymeric component;

(b) from about 5 % to about 60 % of a benzoate plasticizer; and

(c) from about 15 % to about 65 % of additives including fillers, organic diluents including solvents and rheology adjusters, pigments and adhesion promoters;

whereby the ponderal ratio of the polymeric component to the plasticizer is, at least 0.8.

The most preferred plasticizers are represented by dibenzoates, mixtures of dibenzoates and a second plasticizer selected from the group of mono- benzoates, conventional plasticizers other than benzyl phthalate species and benzyl phthalates . Preferred polymeric components can be represented by polyvinyl chloride, acrylic polymers, cured epoxy resins and mixtures of such polymeric components.

Unless indicated to the contrary, the terms "percent" or "%" as used throughout the description mean "percent by weight" or "% by weight" .

Non-aqueous sealant compositions are well-known and well- established in the domain of the technology. Within the context of the claimed technology, the term "non-aqueous" represents a level of water in the claimed compositions of less than 2 %, preferably less than 0.5 %, most preferably less than 0.2 %.

A first essential component is a polymeric ingredient that is compatible with a plasticizer for application on a surface that can be subject to acoustic nuisances, such as a metal surface. It is understood that the composition will frequently be sprayed onto the surface which thus implies selected rheological properties of the composition. Such physical state optimizations are routine undertakings based on day-to-day practice. Preferred polymeric species herein are selected from the group of polyvinyl chloride, acrylic polymers, cured epoxy resins and mixtures thereof. The polymers can be represented by homopolymers and copolymers . The acrylic polymer component can comprise homo- or copolymers derived from monomers comprising alkylmethacrylates and alkylacrylates . The alkyl moieties in both, the methacrylates and the acrylates, species can be represented by C]-C ₁₀ alkyl, more preferably C ₁ -C ₁ alkyl radicals. The epoxy resins, which are cured during application, are based on: bisphenol A which has been reacted with epichlorhydrin; or an aliphatic polyglycol that has also been reacted with epichlorhydrin. The preferred aliphatic polyglycol can be represented by polypropylene glycol. Both epoxy resins can be reacted with curing agents such as primary and secondary amines, anhydrides, polyamides and catalytic curing agents such as tertiary amines, amine salts, boron trifluoride complexes and amine borates. The epoxy curing agents are added to the compositions and the curing (crosslinking) takes place during application, in the case of acoustic application frequently at temperatures equal to or greater than 100 ⁰ C.

Latent catalysts, such as BF ₃ -MEA (borontrifluoride monoethylamine) complex or dicyandiamide can be used to obtain very long, up to several months, potlives. Dicyandiamide can be used as a suitable curing agent. Tertiary amines can be used to accelerate the curing. The selection of epoxy resins and curing agents can be done routinely and the domain of such cured resins is eminently well known. The polymeric component represents broadly from 20 % to 80 %, more preferably from 30 % to 70 %, of the inventive compositions. In one preferred execution, the polymeric component can be represented by a mixture of, expressed on a 100 % basis, from 50-80 % of polyvinyl chloride and from 50-20 % of the acrylic polymer.

The benzoate plasticizer can be represented by known species. The benzoate plasticizer component is used in levels of from 5 % to 60 %, preferably of from 40 % to 15 % of the inventive compositions. Preferred benzoate plasticizers comprise mono- and di-benzoate species corresponding to the formula:

R ₁ C(O)OR ₇

wherein R ₁ represents a phenyl radical, R _? represents - RjO(O)CR ₁ wherein R ₃ is a divalent radical of the formula - RWORJ _1n -, wherein R ₄ is an alkyl radical containing from 2 to 4 carbon atoms and m represents 0 or the integer 1 or 2 ; or R _? represents an alkyl radical containing from 3 to 21 carbon atoms. The individual benzoate plasticizer species e.g. can be used in any (ponderal) proportion. In one preferred execution a monobenzoate plasticizer is used in a

ponderal proportion of up to 40 % based on the total weight (100 %) of the sum of the mono- and di-benzoate species.

Preferred benzoate plasticizers are dibenzoate esters, most preferably (propyleneglycol) _1-4 dibenzoates and

(ethyleneglycol) i _-4 dibenzoates. The dibenzoate plasticizers can, in preferred embodiments, be used in mixture with a second (non-benzoate) plasticizer including benzylphthalates and conventional plasticizer species other than benzylphthalates. The ponderal proportions of the second plasticizer are, expressed in relation to the total level (benzoate + second plasticizer) of plasticizer (100 %) , as follows :

-benzylphthalate : up to 50 % ; and

-conventional plasticizer, other than benzylphthalates: up to 70 %, preferably up to 40 %.

Preferred monobenzoate plasticizers can be represented by a monobenzoate ester of a C ₃ -C _2I alcohol and benzoic acid, more preferably a C ₄ -Ci ₆ alcohol and benzoic acid.

Benzylphthalate plasticizers are well known and have found widespread commercial application. Benzylphthalates are alkylbenzylphthalates wherein the alkyl chain, possibly branched and/or substituted, contains from 2 to 16 carbon atoms. Examples of other conventional plasticizers are dialkyl phthalates such as di (2-ethylhexyl ) phthalate, di- isononyl phthalate, di-isodecyl phthalate, diundecyl phthalate, dibutyl phthalate, dioctyl phthalate, C ₂ -C ₂ , esters of adipic, azelaic, sebacic, trimellitic, citric and

phosphoric acid, alkyl esters of fatty acids, alkyl sulfonic acid esters of phenols and epoxidized triglycerides. A preferred conventional plasticizer, other than benzylphthalates, can be represented by (ethylene glycol) 2-i-di (C ₆ -C _6? alcanoate) , more preferably

-di (C ₄ -C ₁ G alcanoate) . The ponderal ratio of the polymer component to the total plasticizer component is, at least, 0.8, preferably in the range of from 1.0 to 4.0, more preferably of from 1.2 to 2.5. In such ponderal ratios, the plasticizer is based on the total level of plasticizer i.e. the sum of the benzoate species and the second non-benzoate plasticizer

The compositions herein further contain of from about 15 % to about 65 % of additives, including fillers, organic diluents including solvents and rheology adjusters, pigments and adhesion promoters. The filler component as such represents generally of from 7 % to 62 %, more preferably of from 10 % to 60 % of the compositions. The filler serves to, among others, increase the density of the coating and also to enhance the dampening efficacy. The filler can be represented by chemically inert materials. While usually inorganic fillers are exemplified, it goes without saying that various other e.g. compatible polymeric fillers can be used. The sum of the non-filler additives is preferably used in levels ranging from 2 % to 15 % of the composition. The non-filler additives generally are used for their art established functionalities in application conventional levels. Examples of non- filler additives are organic diluents, including solvents, and rheology adjusters. The organic diluents can be represented by C ₈ -C _n ;

alcanes, Cg-C ₂₂ iso- and normal-paraffins, alkylbenzenes having from 3 to 21 carbon atoms in the alkyl chain and alpha-olefins with 4 to 21 carbon atoms and naphthenic solvents. Suitable fillers can be represented by calcium carbonate, magnesium carbonate and metal oxides such as zinc oxide, calcium oxide, silica and mixtures thereof are frequently used in levels ranging from 10 % to 60 %. Adhesion promoters and pigments can be used usually in amounts of from 0.1 to 5 %, preferably of from 0.3 to 0.5 % for each of such individual additives. Preferred adhesion promoters can be polyamidoamines .

The acoustic behavior of the compositions of this invention can be measured with the Oberst bar as, for instance, described in the Renault method D45 1809/. This method is used to study the dampening properties of coated metal bars. The coating consists of a plastisol formulation.

It is known that there is a good correlation between the Oberst bar and a DMTA (Dynamic Mechanical Thermal Analysis) testing. In this latter method, the fused plastisol formulation or the cured epoxy resin formulation is studied without the metal bar. The change in internal molecular mobility is actually measured. The results are expressed in "tangens delta" values that define the acoustic dampening. Maximum dampening occurs at the glass transition temperature (Tg) .

Plastisols in accordance with this invention and prior art plastisols were evaluated by means of the DMTA method. The plastisols were fused in a mold at 160 ⁰ C for 45 minutes to

thereby yield samples having a thickness of 2 mm (millimeters) . The DMTA test was run under the following conditions: dynamic temperature sweeps between -100 °C and +150 ⁰ C with a heating rate of 4 °C/minute at a constant frequency of 5 Hz (31.4 rad/sec) . The components in the compositions tested were, in parts by weight, as follows.

Example 1 (c) 2

Polyvinylchloride (emulsion grade) 70 70

Polyvinylchloride (extender grade) 30 30

Diisononylphthalate 50

Dipropyleneglycol dibenzoate - 50

Dearomatized hydrocarbon fluid 10 10

Calcium carbonate 30 30

Calcium oxide 4 4

(c) = comparative.

The testing data, measuring the tangens delta values, were as follows :

Example Tangens delta at ⁰ C 0 10 20 30 40

1 0.3 0.33 0.38 0.4 0.3

2 0.3 0.65 0.85 0.8 0.35

The results show that the tangens delta, a measure of the dampening properties, is unexpectedly and significantly superior for the dibenzoate execution of this invention as compared to the general purpose plasticizer in accordance with the art .

Acoustic polyalkylmethacrylate plastisol sealants having the listed compositions, in parts by weight, were tested as described for Example 1.

Example 3 4 (c)

Polymethylmethacrylate

(emulsion resin) (i) 70 70

Polymethylmethacrylate

(extender bead) (ii) 30 30

Dipropylene glycol dibenzoate 100

Diisoheptyl phthalate - 100

Dearomatized hydrocarbon fluid 10 10

Calcium carbonate 30 3 ₀

Calcium oxide 4 ₄

(i) : DEGALAN ™ BM 310, Rohm GmbH & Co. Germany (ii) : DEGALAN ™ 8744, Rohm GmbH & Co. Germany

The DMTA testing results were as follows:

Example Tangens delta at ⁰ C

0 10 20 40 60 80

3 0.6 0.95 1.4 0.65 0.2 0

4 0.18 0.2 0.22 0.38 1.1 0.25

The results show that the sound dampening properties of the dibenzoate compositions of this invention were significantly superior, in particular within conventional automotive usage temperature ranges, as compared to a phthalate plasticizer. In addition, conventional phthalate plasticizers are subject to exudation which can move the maximum tangens delta values, or effective sound dampening, out of the temperature range of the contemplated application .

Another series of comparative tests were run thereby using the recited formulations (components expressed in parts by weight) to illustrate the benefits attached to the claimed technology. The data were generated as described in Example l.

Example 5(c) 6(c) 7 8

Polymethylmethacrylate (emulsion resin) (i) 35 35 35 35

Polymethylmethacrylate

(extender bead) (ii) 15 15 15 15

Polyvinylchloride (emulsion grade) 35 35 35 35

Polyvinylchloride (extender grade) 15 15 15 15

Diisodecylphthalate 75

Isononylbenzylphthalate - 75 -

Diethyleneglycol dibenzoate - - 75 -

Dipropyleneglycol dibenzoate - - - 75

Dearomatized hydrocarbon fluid 10 10 10 10

Calcium carbonate 30 30 30 30

Calcium oxide 4 4 4 4

The testing data, expressed in tangens delta, were as follows :

Example Tangens delta at °C

0 10 20 30 40 50 70

5 0.25 0.25 0.25 0.25 0.25 0.25 0.2

6 0.3 0.3 0.35 0.35 0.4 0.5 0.3

7 ^' 0.4 0.7 1.0 0.95 0.6 0.3 0.2

8 0.4 0.7 1.1 1.0 0.7 0.35 0.2

The results confirm the significantly superior dampening properties of the inventive formulations as compared to state-of-the-art technology. It is particularly noteworthy that the inventive compositions produce benefits over a broad range of usage temperatures .

Acoustic sealants based on epoxy resins, having the listed compositions expressed in parts by weight, were performance tested as described in Example 1.

Example 9 10 ( c '

Bisphenol A liquid epoxy resin 40 40

Propyleneglycol liquid epoxy resin 60 60

Dicyandiamide curing agent 10 10

Tertiary amine accelerator 5 5

Calcium oxide 15 15

Calcium carbonate 200 200

Dipropyleneglycol dibenzoate 30

Diisononylphthalate - 30

The DMTA testing results were as follows:

Example Tangens delta at ⁰ C -10 0 10 20 30 70

9 0.2 0.42 0.55 0.57 0.38 0.26

10 0.2 0.26 0.33 0.38 0.38 0.26

The testing data confirm the beneficial dampening superiority of the claimed arrangement, particularly with respect to conditions prevailing in moderate climates.

The beneficial acoustic use of dibenzoate plasticizers or mixed dibenzoate/monobenzoate plasticizers in the claimed compositions is further illustrated in specific executions as follows. These compositions, expressed in parts by weight, were performance tested as described in Example 1.

Example 11 12 13

Polyvinyl chloride (emulsion grade) 70 70 70

Polyvinyl chloride (extender grade) • 30 30 30

Dipropylene glycol dibenzoate 50 50 50

Dearomatized hydrocarbon fluid 10

2-Ethylhexyl benzoate - 15

Benzoate ester of 2,2,4

Trimethylpentane diol isobutyrate - - 15

Calcium carbonate 30 30 30

Calcium oxide 4 4 4

The DMTA data were as follows.

Example Tangens delta at ⁰ C.

-10 0 +10 +20 +30 +40

11 0.2 0.3 0.44 0.52 0.54 0.38

12 0.3 0.48 0.72 0.68 0.40 0.36

13 0.2 0.35 0.60 0.68 0.48 0.42

The data evidence the acoustic benefits attached to the use of the claimed compositions.

To provide further showings of the beneficial sound dampening properties of the inventive technology, Example 7 of JP-A-2000-169756 was evaluated and compared to Examples 1 (c) and 2 described in this patent document.

The composition in accordance with the Japanese patent contained the listed ingredients, expressed in parts by weight, as follows.

PVC Emulsion grade 70

PVC Extender 30

Calcium carbonate 150

Calcium oxide 30 Dipropyleneglycol dibenzoate 150

Tricresyl phosphate 150

Diluent (Exxsol DlOO) 30

Various (TiO ₂ ; foamer; amine; etc.) 24.5 Total 634.5

Ingredients in the comparative compositions vary, expressed in % by weight, as follows:

Ingredient Japanese Example 1 Example 2

PVC 15 .8 54 54

Plasticizer 47 .3 27 -

Filler 32 18 .5 18.5

Di -benzoate 23 .5 _ 27

The comparative testing data, measuring the tangens delta values, were as follows.

Temperature ⁰ C Japanese Example 1 Example 2

-40 0.8 0 0

-30 1.4 0 0

-20 0.7 0 0

-10 0.2 0 0 0 0 0.3 0.3

10 0 0.33 0.65

20 0 0.38 0.85

30 0 0.4 0.8

40 0 ' 0.3 0.35

These data show that the Japanese technology does not suppress acoustic inconveniences at low frequencies, preferably in the range of from 20 to 500 Hz, more preferably 150 to 250 Hz, at ambient temperature contrary to the inventive technology.