PREPARING THE SAME

Cross Reference To Related Application

This application claims the benefit of Chinese Patent Application No. 201510504419.5, filed August 17, 2015, the disclosure of which is incorporated by reference herein in its entirety.

Technical Field of the Invention

The present invention relates to a slip resistant liquid, a slip resistant article, and the method for preparing the same.

Background

The surface of ceramic tile substrates, glass substrates, and stone substrates will become slippery after experiencing water, which makes people tend to slip and get injured or the like. Therefore, it is important for the surface of the above substrates to be treated for improved slip resistance.

One of the common approaches for slip resistant treatment is to dispose a slip resistant coating on the surface of the substrate to increase the surface friction of the substrate. As a result, the coefficient of friction is increased to a safe level so as to achieve the slip resistant effect, thereby reducing accidents of slipping and getting injured and the like.

Currently, the slip resistant coating usually uses alkyd resin, chlorinated rubber, phenolic resin, epoxy resin, or urethane resin as film-forming resin, which is filled with slip resistant pellets of quartz sand, corundum, titanium oxide, aluminum oxide or rubber grains and the like. These pellets have irregular shapes and protrude from the surface of the coating, which can increase surface roughness and friction to reduce the sliding tendency of a person or other objects on the surface, so as to achieve slip resistance.

In order to meet requirements of better appearance, nano-technology has been used to form ultra-thin slip resistant coatings with transparent appearance. CN201410196078.5 discloses a slip resistant liquid, a slip resistant article, and a method for preparing the slip resistant article by using the slip resistant liquid. A slip resistant liquid in this invention can be obtained by combining a polymer emulsion or the like with silica particles, and then disposed to the surface of a substrate to form a slip resistant coating after drying. CN201410103305.5 discloses another slip resistant article and a method of preparing the same. A slip resistant liquid in this invention can be prepared by dissolving an epoxy functional group-containing silane (i.e., a silane containing an epoxy functional group) and/or tetraalkoxysilane directly into a solvent, and then disposed to the surface of substrate to form a slip resistant coating after drying.

US5853809 discloses a coating composition having good scratch resistance and a method of improving the scratch resistance of the coating composition. This coating composition is obtained by mixing a crosslinkable resin, a crosslinking agent and a solvent with carbide or inorganic microparticles which are reactive with the crosslinkable portion of the film forming binder system by its inherent reactivity (e.g., presence of SiOH groups) or after being modified by alkoxy silane coupling agents, wherein the second functionality of the alkoxy silane coupling agents is selected from the group consisting of: carbamate, isocyanate, carboxyl, epoxy, amine, urea, amide, silane and aminoplast functionalities.

SUMMARY OF THE INVENTION

The present invention aims to provide a new slip resistant liquid whereby the slip resistant coatings and the slip resistant articles further prepared from this slip resistant liquid have good slip resistance performance under both dry and wet conditions, good abrasion resistance performance as well as good gloss.

According to one aspect of the present invention, a slip resistant liquid is provided, comprising a reaction product of the following reaction components, based on the total weight of the slip resistant liquid as 100 wt.%:

1) a first reaction solution comprising a reaction product of the following reaction components: 3-75 wt.% of a first silane, wherein the first silane is represented by a general formula of R^Si

(OR) 4 a-bR ² b, wherein the value of a is 1 to 3; when the value of a is 1, the value of b is 0 to 2; when the value of a is 2, the value of b is 0 to 1 ; when the value of a is 3, the value of b is 0; R represents an alkyl group having 1 to 4 carbon atoms, R ¹ represents an organic group with at least one epoxy functional group, and R ² represents a hydrogen atom or an alkyl group having 1 to 20 carbon atoms;

20-96 wt.% of water; and an acid; wherein the first reaction solution has a pH value of less than or equal to 5;

2) 0.5-4 wt.% of a second silane, wherein the second silane is represented by a general formula of R ³ _c Si (OR) 4 c-dR ⁴ d, wherein the value of c is 1 to 3; when the value of c is 1, the value of d is 0 to 2; when the value of c is 2, the value of d is 0 to 1; when the value of c is 3, the value of d is 0; R represents an alkyl group having 1 to 4 carbon atoms, R ³ represents an organic group with at least one primary amino functional group, secondary amino functional group or tertiary amino functional group, and R ⁴ represents a hydrogen atom or an alkyl group having 1 to 20 carbon atoms; and

3) 0.5-11 wt.% of surface epoxy-modified silica particles, wherein the surface epoxy-modified silica particles have an average particle size of less than or equal to 50 nm.

According to another aspect of the present invention, a slip resistant article comprising a substrate and a slip resistant coating disposed on the substrate is provided, wherein the slip resistant coating is obtained by disposing a layer of the slip resistant liquid to the surface of the substrate and then drying the layer.

According to another aspect of the present invention, a method for preparing the slip resistant article is provided, which includes the steps of: disposing the slip resistant liquid described above to the surface of the substrate, forming a layer of wet slip resistant coating on the surface of the substrate, and drying the layer of wet slip resistant liquid coating to form a slip resistant coating attached to the surface of the substrate. Detailed Description of the Invention

It should be understood that without departing from the scope or spirit of the present invention, a person skilled in the art can conceive other various embodiments according to the teachings of this specification and can modify them. Therefore, the following embodiments are not in a limiting sense.

Unless otherwise indicated, all numbers used in this specification and claims for expressing the quantity and physicochemical properties should be understood as in all cases to be modified by the term "about". Accordingly, unless indicated to the contrary, the numerical parameters listed in the foregoing specification and attached claims are all approximations, a person skilled in the art can use the teachings disclosed herein to obtain the desired properties, and to appropriately change these approximations. The use of numerical range represented by endpoints includes all numbers within that range and any range within that range, e.g., 1, 2, 3, 4 and 5 include 1, 1.1, 1.3, 1.5, 2, 2.75, 3, 3.80, 4 and 5, and so on. Slip Resistant Liquid

The slip resistant liquid provided by the present invention comprises a reaction product of the following reaction components, based on the total weight of the slip resistant liquid as 100 wt.%:

1) a first reaction solution comprising a reaction product of the following reaction components:

3-75 wt.% of a first silane, wherein the first silane is represented by a general formula of R^Si (OR) 4 a-bR ² b, wherein the value of a is 1 to 3; when the value of a is 1, the value of b is 0 to 2; when the value of a is 2, the value of b is 0 to 1 ; when the value of a is 3, the value of b is 0; R represents an alkyl group having 1 to 4 carbon atoms, R ¹ represents an organic group with at least one epoxy functional group, and R ² represents a hydrogen atom or an alkyl group having 1 to 20 carbon atoms;

20-96 wt.% of water; and

an acid, wherein the first reaction solution has a pH value of less than or equal to 5;

2) 0.5-4 wt.% of a second silane, wherein the second silane is represented by a general formula of R ³ _c Si (OR) 4 c-dR ⁴ d, wherein the value of c is 1 to 3; when the value of c is 1, the value of d is 0 to 2; when the value of c is 2, the value of d is 0 to 1 ; when the value of c is 3, the value of d is 0; R represents an alkyl group having 1 to 4 carbon atoms, R ³ represents an organic group with at least one primary amino functional group, secondary amino functional group or tertiary amino functional group, and R ⁴ represents a hydrogen atom or an alkyl group having 1 to 20 carbon atoms; and

3) 0.5-11 wt.% of surface epoxy-modified silica particles, wherein the surface epoxy-modified silica particles have an average particle size of less than or equal to 50 nm.

The first silane is represented by a general formula of R^Si (OR) 4- _a -bR ² t _> . In some embodiments, R is often an alkyl group having 1 to 2 carbon atoms, R ¹ is often an organic group with a single epoxy group having 3 to 18, or 4 to 12 carbon atoms, and R ² is often an alkyl group having 1 to 10, 1 to 6, or 1 to 4 carbon atoms.

The first silane comprises one or more selected from the group consisting of:

3-glycidoxypropyltrimethoxysilane, 3 -glycidoxypropyltriethoxy silane,

3 -glycidoxypropylmethyldimethoxy silane, 3-glycidoxypropylmethyldiethoxysilane,

3 -glycidoxypropylethyldimethoxysilane, 3 -glycidoxypropylethyldiethoxysilane, and

2-(3,4-epoxycyclohexyl)ethyltriethoxy silane, and preferably 3-glycidoxypropyltrimethoxysilane and 3 -glycidoxypropyltriethoxy silane . The amount of the first silane is typically in a range of 3-75 wt.%, based on the total weight of the slip resistant liquid as 100 wt.%. In some embodiments, the amount of the first silane is often at least 3 wt.%, at least 5 wt.%, at least 7 wt.%, at least 10 wt.%, or at least 15 wt.%, based on the total weight of the slip resistant liquid as 100 wt.%. If the amount of the first silane is less than 3 wt.%, it may be difficult to form a slip resistant coating with sufficient thickness on the surface of the substrate, so that the slip resistance performance and abrasion resistance performance possessed by the slip resistant article of the present invention cannot be achieved. In some embodiments, the amount of the first silane is often up to 75 wt.%, up to 70 wt.%, up to 60 wt.%, up to 40 wt.%, or up to 20 wt.%, based on the total weight of the slip resistant liquid as 100 wt.%. If the amount of the first silane is greater than 75 wt.%, the appearance of the slip resistant coating obtained accordingly may have more defects, resulting in significant drawbacks in the appearance of the slip resistant article obtained. Generally the amount of the first silane is preferably 3-40 wt.%, and more preferably 3-20 wt.%, based on the total weight of the slip resistant liquid as 100 wt.%.

The amount of water is typically in a range of 20-96 wt.%, based on the total weight of the slip resistant liquid as 100 wt.%. In some embodiments, the amount of water is often at least 20 wt.%, at least 40 wt.%, at least 60 wt.%, or at least 80 wt.%, based on the total weight of the slip resistant liquid as 100 wt.%. If the amount of water is less than 20 wt.%, the appearance of the slip resistant coating obtained accordingly may have more defects, resulting in significant drawbacks in the appearance of the slip resistant article obtained. In some embodiments, the amount of water is often up to 96 wt.%, up to 94 wt.%, up to 92 wt.%, or up to 90 wt.%, based on the total weight of the slip resistant liquid as 100 wt.%. If the amount of water is greater than 96 wt.%, it may be difficult to form a slip resistant coating with sufficient thickness on the surface of the substrate, so that the slip resistance performance and abrasion resistance performance possessed by the slip resistant article of the present invention cannot be achieved. Generally the amount of water is preferably 40-96 wt.%, and more preferably 60-90 wt.%, based on the total weight of the slip resistant liquid as 100 wt.%.

The acid may be inorganic acid or organic acid. The inorganic acid comprises one or more selected from the group consisting of: hydrochloric acid, sulfuric acid, phosphoric acid and nitric acid, and more preferably hydrochloric acid and phosphoric acid. The organic acid comprises one or more selected from the group consisting of: formic acid, acetic acid, propionic acid, oxalic acid, citric acid, benzoic acid and benzenesulfonic acid, and more preferably formic acid, acetic acid, oxalic acid and citric acid. The slip resistant liquid may also comprise the combination of inorganic acid and organic acid. The amount of the acid is not particularly limited, as long as it enables the pH value of the first reaction solution to be less than or equal to 5, preferably less than or equal to 4, and more preferably less than or equal to 3. If the pH value of the first reaction solution is greater than 5, when the first reaction solution reacts with the second silane and the surface epoxy-modified silica particles to obtain the slip resistant liquid, the slip resistant coating and the slip resistant article further prepared from this slip resistant liquid may have both poor slip resistance performance and poor abrasion resistance performance, so that the slip resistance performance and abrasion resistance performance possessed by the slip resistant article of the present invention cannot be achieved.

The second silane is represented by a general formula of R ³ _c Si (OR) 4-c-dR ⁴ d- In some embodiments,

R is often an alkyl group having 1 to 2 carbon atoms, R ³ is often an organic group with one or more primary amino functional group, secondary amino functional group or tertiary amino functional group having 3 to 20, or 3 to 10 carbon atoms, and R ⁴ is often an alkyl group having 1 to 10, 1 to 6, or 1 to 4 carbon atoms.

The second silane comprises one or more selected from the group consisting of:

3 -aminopropyltriethoxysilane, 3 -aminopropylmethyldiethoxysilane,

3-(2-aminoethyl)-aminopropyltrimethoxysilane, 3-(2-aminoethyl)-aminopropylmethyldimethoxysilane, and 3-(N,N-dimethyl aminopropyl)-aminopropylmethyldimethoxysilane.

The amount of the second silane is typically in a range of 0.5-4 wt.%, based on the total weight of the slip resistant liquid as 100 wt.%. In some embodiments, the amount of the second silane is often at least 0.5 wt.%, at least 0.6 wt.%, at least 0.7 wt.%, at least 0.8 wt.%, or at least 0.9 wt.%, based on the total weight of the slip resistant liquid as 100 wt.%. If the amount of the second silane is less than 0.5 wt.%, when the second silane reacts with the first reaction solution to obtain the slip resistant liquid, this slip resistant liquid may be difficult to completely cure after being disposed to the surface of the substrate, and the slip resistant coating and the slip resistant article obtained from it may have both poor slip resistance performance and poor abrasion resistance performance, so that the slip resistance performance and abrasion resistance performance possessed by the slip resistant article of the present invention cannot be achieved. In some embodiments, the amount of the second silane is often up to 4 wt.%, up to 3 wt.%, up to 2 wt.%, or up to 1 wt.%, based on the total weight of the slip resistant liquid as 100 wt.%. If the amount of the second silane is greater than 4 wt.%, when the second silane reacts with the first reaction solution to obtain the slip resistant liquid, the slip resistant coating and the slip resistant article further prepared from this slip resistant liquid may have both poor slip resistance performance and poor abrasion resistance performance, so that the slip resistance performance and abrasion resistance performance possessed by the slip resistant article of the present invention cannot be achieved. Generally the amount of the second silane is preferably 0.5-2 wt.%, and more preferably 0.5- 1 wt.%, based on the total weight of the slip resistant liquid as 100 wt.%.

The surface epoxy-modified silica particles may comprise surface epoxy-modified silica particles with a single average particle size, and may also comprise the combination of surface epoxy-modified silica particles with two or more average particle sizes. The "particle size" herein and in the claims refers to the length of the longest axis of the particle. The "surface epoxy-modified" herein and in the claims refers to the inherent reactive groups on the surface of silica particles (e.g., SiOH groups) being replaced by organic groups with at least one epoxy functional group. The average particle size of the surface epoxy-modified silica particles is less than or equal to 50 nm, preferably less than or equal to 20 nm, and more preferably less than or equal to 15 nm. The example of commercially available surface

epoxy-modified silica sol comprises silica sol with surface modified by epoxy agents in water or aqueous alcohol solution obtained from AkzoNobel Company under the trade name of BINDZIL. A useful surface epoxy-modified silica sol is the one having the average particle size of 7 nm and a nominal solid content of 28 wt.%, which is available from AkzoNobel Company as BINDZIL CC301. Other useful commercially available surface epoxy-modified silica sols comprise those available from AkzoNobel Company as BINDZIL CC 151 HS and BINDZIL CC401.

The amount of the surface epoxy-modified silica particles is typically in a range of 0.5-11 wt.%, based on the total weight of the slip resistant liquid as 100 wt.%. In some embodiments, the amount of the surface epoxy-modified silica particles is often at least 0.5 wt.%, at least 1 wt.%, at least 1.5 wt.%, at least 2 wt.%, or at least 2.5 wt.%, based on the total weight of the slip resistant liquid as 100 wt.%. If the amount of the surface epoxy-modified silica particles is less than 0.5 wt.%, when the surface

epoxy-modified silica particles react with the first react solution and the second silane to obtain the slip resistant liquid, the slip resistant coating further prepared from this slip resistant liquid may have poor abrasion resistance performance, so that the abrasion resistance performance possessed by the slip resistant article of the present invention cannot be achieved. In some embodiments, the amount of the surface epoxy-modified silica particles is often up to 11 wt.%, up to 10 wt.%, up to 9 wt.%, up to 8 wt.%, or up to 7 wt.%, based on the total weight of the slip resistant liquid as 100 wt.%. If the amount of the surface epoxy-modified silica particles is greater than 11 wt.%, when the surface epoxy-modified silica particles react with the first react solution and the second silane to obtain the slip resistant liquid, the slip resistant coating further prepared from this slip resistant liquid may have poor appearance, so that the good appearance possessed by the slip resistant article of the present invention cannot be achieved.

Generally the amount of the surface epoxy-modified silica particles is preferably 0.5-10 wt.%, and more preferably 0.5-5 wt.%, based on the total weight of the slip resistant liquid as 100 wt.%.

The slip resistant liquid according to the present invention can further comprise an organic solvent. The organic solvent is miscible with water, and can improve the wettability of the slip resistant liquid to the surface of the substrate. The organic solvent comprises one or more selected from the group consisting of: alcohols, ketones, esters, and ethers having a molecular weight less than 250. The alcohols are preferably methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, sec-butanol, tert-butanol, ethylene glycol, propylene glycol, glycerol, and triethylene glycol. The ketones are preferably acetone and butanone. The esters are preferably methyl acetate and ethyl acetate. The ethers are preferably ethylene glycol monomethyl ether, propylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol methyl ether, diethylene glycol ethyl ether, dipropylene glycol methyl ether, dipropylene glycol ethyl ether, ethylene glycol dimethyl ether, propylene glycol dimethyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, tripropylene glycol monomethyl ether, and tripropylene glycol monoethyl ether.

The amount of the organic solvent is typically in a range of 0.01-5 wt.%, based on the total weight of the slip resistant liquid as 100 wt.%. In some embodiments, the amount of the organic solvent is often at least 0.01 wt.%, at least 0.02 wt.%, at least 0.03 wt.%, at least 0.04 wt.%, or at least 0.05 wt.%, based on the total weight of the slip resistant liquid as 100 wt.%. In some embodiments, the amount of the organic solvent is often up to 5 wt.%, up to 4 wt.%, up to 3 wt.%, up to 2 wt.%, or up to 1 wt.%, based on the total weight of the slip resistant liquid as 100 wt.%. If the amount of the organic solvent is greater than 5 wt.%, the slip resistant coating further prepared according to this slip resistant liquid may have poor slip resistance performance, so that it may be difficult to achieve the slip resistance performance possessed by the slip resistant article of the present invention. Generally the amount of the organic solvent is preferably 0.05-3 wt.%, and more preferably 0.05-2 wt.%, based on the total weight of the slip resistant liquid as 100 wt.%. The slip resistant liquid according to the present invention can further comprise a nonionic surfactant. The nonionic surfactant can improve the wettability of the slip resistant liquid to the surface of the substrate. The nonionic surfactant comprises one or more selected from the group consisting of: a polyoxyethylene-type nonionic surfactant, a polyol-type nonionic surfactant, an alkanolamide-type nonionic surfactant, a fluorocarbon-type nonionic surfactant, a silicone-type nonionic surfactant, and a modified silicone-type nonionic surfactant.

The amount of the nonionic surfactant is typically in a range of 0.01-2 wt.%, based on the total weight of the slip resistant liquid as 100 wt.%. In some embodiments, the amount of the nonionic surfactant is often at least 0.01 wt.%, at least 0.02 wt.%, at least 0.03 wt.%, at least 0.04 wt.%, or at least 0.05 wt.%, based on the total weight of the slip resistant liquid as 100 wt.%. In some embodiments, the amount of the nonionic surfactant is often up to 2 wt.%, up to 1.6 wt.%, up to 1.2 wt.%, up to 0.8 wt.%, or up to 0.4 wt.%, based on the total weight of the slip resistant liquid as 100 wt.%. If the amount of the nonionic surfactant is greater than 2 wt.%, the slip resistant coating further prepared from this slip resistant liquid may have poor slip resistance performance, therefore it may be difficult to achieve the slip resistance performance possessed by the slip resistant article of the present invention. Generally the amount of the nonionic surfactant is preferably 0.01-1 wt.%, and more preferably 0.05-0.5 wt.%, based on the total weight of the slip resistant liquid as 100 wt.%.

Slip Resistant Article

The slip resistant article provided by the present invention comprises a substrate and slip resistant coating disposed to the substrate. The substrate comprises one or more selected from the group consisting of: ceramic tile substrate, glass substrate, and stone substrate. The "ceramic tile" herein and in the claims is suitable for ceramic material including those prepared from fire-resistant clay, brick material, concrete, ceramics, marble, limestone, other rock material, and slate. The ceramic tile substrate comprises one or more selected from the group consisting of: vitrified tiles, glazed tiles, archaized tiles, microlite stones, polished tiles, imitation granite tiles, and imitation marble tiles. The stone substrate comprises one or more selected from the group consisting of: marble, granite, and artificial stones.

The slip resistant coating comprises the coating obtained by disposing a layer of any slip resistant liquid provided by the present invention to the surface of the substrate and then drying the layer. The slip resistant coating is completely or partially free of water, and preferably completely free of water. The description of the slip resistant liquid can be found in the "slip resistant liquid" section of the description of the present invention in detail.

The slip resistant coating can significantly improve the slip resistance performance of the substrate under dry and wet conditions. The slip resistant coating can be of any suitable thickness as required, and the slip resistant coating can have a thickness of 100-5,000 nm, or 100-3,000 nm, or 100-2,000 nm.

Method for Preparing the Slip Resistant Article

The method for preparing the slip resistant article provided by the present invention comprises the steps of: disposing the slip resistant liquid provided by the present invention to the surface of the substrate, forming a layer of wet slip resistant liquid coating on the surface of the substrate, and drying the wet slip resistant liquid coating to obtain a slip resistant coating, the slip resistant coating being attached to the surface of the substrate.

The description of the slip resistant liquid, the substrate, the slip resistant coating and the slip resistant article can be found in the "slip resistant liquid" and "slip resistant article" sections of the description of the present invention in detail.

The known methods in the art can be used to dispose the slip resistant liquid to the surface of the substrate, and the method preferably comprises one or more selected from the group consisting of: bar coating, wipe coating, brush coating, dip coating, and spray coating.

Suitable drying methods known in the art can be used to dry the slip resistant liquid, and this drying process can be performed at room temperature or higher temperature, e.g., 20- 180 °C, or 20-150 °C, or 20-120 °C.

The present invention provides a plurality of preferred embodiments about the slip resistant liquid, the slip resistant article, and the methods for preparing the same.

The preferred embodiment 1 is a slip resistant liquid comprising a reaction product of the following reaction components, based on the total weight of the slip resistant liquid as 100 wt.%:

1) a first reaction solution comprising a reaction product of the following reaction components:

3-75 wt.% of a first silane, wherein the first silane is represented by a general formula of R^Si (OR)

4 a-bR ² b, wherein the value of a is 1 to 3; when the value of a is 1, the value of b is 0 to 2; when the value of a is 2, the value of b is 0 to 1 ; when the value of a is 3, the value of b is 0; R represents an alkyl group having 1 to 4 carbon atoms, R ¹ represents an organic group with at least one epoxy functional group, and R ² represents a hydrogen atom or an alkyl group having 1 to 20 carbon atoms;

20-96 wt.% of water; and

an acid, wherein the first reaction solution has a pH value of less than or equal to 5;

2) 0.5-4 wt.% of a second silane, wherein the second silane is represented by a general formula of R ³ _c Si (OR) 4 c-dR ⁴ d, wherein the value of c is 1 to 3; when the value of c is 1, the value of d is 0 to 2; when the value of c is 2, the value of d is 0 to 1 ; when the value of c is 3, the value of d is 0; R represents an alkyl group having 1 to 4 carbon atoms, R ³ represents an organic group with at least one primary amino functional group, secondary amino functional group or tertiary amino functional group, and R ⁴ represents a hydrogen atom or an alkyl group having 1 to 20 carbon atoms; and

3) 0.5-11 wt.% of surface epoxy-modified silica particles, wherein the surface epoxy-modified silica particles have an average particle size of less than or equal to 50 nm.

The preferred embodiment 2 is a slip resistant liquid according to the preferred embodiment 1, wherein the first silane is represented by a general formula of R^Si (OR) 4- _a -bR ² t _> , wherein R is often an alkyl group having 1 to 2 carbon atoms, R ¹ is often an organic group with a single epoxy group having 3 to 18, or 4 to 12 carbon atoms, and R ² is often an alkyl group having 1 to 10, 1 to 6, or 1 to 4 carbon atoms.

The preferred embodiment 3 is a slip resistant liquid according to the preferred embodiment 2, wherein the first silane comprises one or more selected from the group consisting of:

3-glycidoxypropyltrimethoxysilane, 3 -glycidoxypropyltriethoxy silane,

3 -glycidoxypropylmethyldimethoxysilane, 3 -glycidoxypropylmethyldiethoxysilane,

3 -glycidoxypropylethyldimethoxysilane, 3 -glycidoxypropylethyldiethoxysilane, and

2-(3 ,4-epoxycyclohexyl)ethyltriethoxysilane .

The preferred embodiment 4 is a slip resistant liquid according to the preferred embodiment 1, wherein the second silane is represented by a general formula of R ³ _c Si (OR) 4- _c -dR ⁴ d, wherein R is often an alkyl group having 1 to 2 carbon atoms, R ³ is often an organic group with one or more primary amino functional group, secondary amino functional group or tertiary amino functional group having 3 to 20, or 3 to 10 carbon atoms, and R ⁴ is often an alkyl group having 1 to 10, 1 to 6, or 1 to 4 carbon atoms.

The preferred embodiment 5 is a slip resistant liquid according to the preferred embodiment 4, wherein the second silane comprises one or more selected from the group consisting of:

3 -aminopropyltriethoxysilane, 3 -aminopropylmethyldiethoxysilane, 3-(2-aminoethyl)-aminopropyltrimethoxysilane, 3-(2-aminoemyl)-aminopropylmemyldimethoxysilane, and 3 -(N,N-dimethylaminopropyl)-aminopropylmethyldimethoxysilane .

The preferred embodiment 6 is a slip resistant liquid according to the preferred embodiment 1, wherein the surface epoxy -modified silica particles have an average particle size of less than or equal to 15 nm.

The preferred embodiment 7 is a slip resistant liquid according to any one of the preferred embodiments 1 to 6, wherein the slip resistant liquid further comprises 0.01-5 wt.% of an organic solvent, based on the total weight of the slip resistant liquid as 100 wt.%, and the organic solvent comprises one or more selected from the group consisting of: alcohols, ketones, esters, and ethers having a molecular weight less than 250.

The slip resistant coatings or slip resistant articles further prepared by using the slip resistant liquid according to the preferred embodiments 1 to 7 have good slip resistance performance, abrasion resistance performance and surface gloss.

The preferred embodiment 8 is a slip resistant liquid according to any one of the preferred embodiments 1 to 7, wherein the slip resistant liquid further comprises 0.01-2 wt.% of a nonionic surfactant, based on the total weight of the slip resistant liquid as 100 wt.%.

The preferred embodiment 9 is a slip resistant liquid according to the preferred embodiment 8, wherein the nonionic surfactant comprises one or more selected from the group consisting of: a polyoxyethylene-type nonionic surfactant, a polyol-type nonionic surfactant, an alkanolamide-type nonionic surfactant, a fluorocarbon-type nonionic surfactant, a silicone-type nonionic surfactant, and a modified silicone-type nonionic surfactant.

The slip resistant coatings or slip resistant articles further prepared by using the slip resistant liquid according to the preferred embodiments 8 to 9, which can wet the surface of the substrate better, have good slip resistance performance, abrasion resistance performance and surface gloss.

The preferred embodiment 10 is a slip resistant article comprising a substrate and a slip resistant coating disposed on the substrate, wherein the slip resistant coating is obtained by disposing a layer of any slip resistant liquid according to the preferred embodiments 1 to 9 to the surface of the substrate and then drying the layer.

The preferred embodiment 11 is a slip resistant article according to the preferred embodiment 10, wherein the substrate comprises one or more selected from the group consisting of: ceramic tile substrate, glass substrate, and stone substrate.

The preferred embodiment 12 is a slip resistant article according to the preferred embodiment 11, wherein the ceramic tile substrate comprises one or more selected from the group consisting of: vitrified tiles, glazed tiles, archaized tiles, microlite stones, polished tiles, imitation granite tiles, and imitation marble tiles.

The preferred embodiment 13 is a slip resistant article according to the preferred embodiment 11, wherein the stone substrate comprises one or more selected from the group consisting of: marble, granite, and artificial stones.

The slip resistant articles according to the preferred embodiments 10 to 13 have good slip resistance performance, abrasion resistance performance and surface gloss.

The preferred embodiment 14 is a method for preparing the slip resistant article comprising the steps of: disposing the slip resistant liquid according to embodiments 1 to 9 to the surface of the substrate, forming a layer of wet slip resistant liquid coating on the surface of the substrate, and drying the wet slip resistant liquid coating to obtain a slip resistant coating, the slip resistant coating being attached to the surface of the substrate.

The preferred embodiment 15 is a preparation method according to the preferred embodiment 14, wherein the slip resistant liquid is disposed to the surface of the substrate by the following methods: bar coating, wipe coating, brush coating, dip coating, and spray coating.

The slip resistant articles prepared by using the methods according to the preferred embodiments 14 to 15 have good slip resistance performance, abrasion resistance performance and surface gloss.

EXAMPLES

The following Examples and Comparative Examples are provided to help understand the present invention, and these Examples and Comparative Examples should not be construed as the limitation for the scope of the invention. Unless otherwise indicated, all parts and percentages are calculated by weight.

The raw materials used in Examples and Comparative Examples of the present invention are shown in Table 1.

Table 1. Raw materials used in Examples and Comparative Examples Chemical Property /

Product Name Supplier

Specification

Sinopharm Chemical Reagent

3-Glycidoxypropyltrimethoxysilane Purity > 98 wt.%

Co., Ltd.

3 -Aminopropyltriethoxy silane Purity > 98 wt.%

3-(2-Aminoethyl)-aminopropyltrim

Purity > 97 wt.%

ethoxysilane

Hydrochloric acid Purity = 36-38 wt.%

Jiangsu Qiangsheng Chemical

Nitric acid Purity = 65-68 wt.%

Co., Ltd.

An aqueous dispersion of

surface unmodified silica

nanoparticles, sodium

NALCO 1115 NALCO Company

stabilized, with a solid

content of 15 wt.%, and an

average particle size of 4 nm

An aqueous dispersion of

surface deionized modified

silica nanoparticles, with a

BINDZIL 2034/DI AkzoNobel Company

solid content of 34 wt.%,

and an average particle size

of 15 nm

An aqueous dispersion of surface aluminum ion modified silica nanoparticles, chloride

LEVASIL 200S/30

stabilized, with a solid content of 30 wt.%, and an average particle size of 17 nm

An aqueous dispersion of surface aluminate modified silica nanoparticles, sodium

LEVASIL 200A/30 stabilized, with a solid content of 30 wt.%, and an average particle size of 17 nm

An aqueous dispersion of surface epoxy-modified silica nanoparticles, sodium

BINDZIL CC 151 HS

stabilized, with a solid content of 15 wt.%, and an average particle size of 5 nm

An aqueous dispersion of surface epoxy-modified silica nanoparticles, sodium

BINDZIL CC301

stabilized, with a solid content of 28 wt.%, and an average particle size of 7 nm An aqueous dispersion of

surface epoxy-modified

silica nanoparticles, sodium

BINDZIL CC401 stabilized, with a solid

content of 37 wt.%, and an

average particle size of 12

nm

Alkylpolyglucoside

surfactant, TRITON BG-10,

Nonionic surfactant Dow Chemical Company with water solution of 70

wt.%

Shanghai Bohao Building

Vitrified tile 225 mm ^χ 150 mm ^χ 10 mm

Materials Co., Ltd.

Glazed tile 300 mm ^χ 300 mm ^χ 10 mm

Microlite stone 300 mm ^χ 300 mm ^χ 10 mm

Artificial stone 200 mm ^χ 200 mm ^χ 20 mm

Shanghai Yangguang

Marble 200 mm ^χ 150 mm ^χ 15 mm Decoration Materials Co.,

Ltd.

Shanghai Jinqia Trading Co.,

Glass substrate 180 mm ^χ 100 mm ^χ 3 mm

Ltd.

The present invention evaluates the slip resistance performance of the slip resistant coatings or slip resistant articles provided by the Examples and Comparative Examples mainly through dry and wet static coefficient of friction tests. Meanwhile, the present invention evaluates the abrasion resistance performance of the slip resistant coatings or slip resistant articles provided by the Examples and

Comparative Examples through dry abrasion tests. On this basis, through surface gloss tests, the present invention further assesses the influence of slip resistant coatings provided by the Examples and Comparative Examples on the appearance of the substrate. Slip Resistance Performance Test

A static coefficient of friction is an important indicator for evaluating the slip resistance safety performance of a surface. The slip resistance performance of slip resistant coatings or slip resistant articles under dry conditions is characterized by dry static coefficient of friction in the present invention. The slip resistance performance of slip resistant coatings or slip resistant articles under wet conditions is characterized by wet static coefficient of friction in the present invention.

The equipment for testing the dry and wet static coefficient of friction is ASM 825A, commercially available from American Slip Meter Company. The friction medium for testing the dry and wet static coefficient of friction is Neolite rubber (Shore hardness of 93-96, commercially available from Goodyear Tire and Rubber Company).

A slip resistant liquid is disposed to the surface of the substrate, and the dried slip resistant liquid forms a slip resistant coating on the surface of the substrate, to obtain a slip resistant article comprising the substrate and the slip resistant coating.

The dry static coefficient of friction of the surface of the slip resistant article is measured by using the ASM 825A static coefficient of friction tester. Three different regions are randomly selected from the surface of the slip resistant article, and the dry static coefficient of friction is measured respectively to calculate the average.

After the surface of the slip resistant article has been completely wetted by deionized water, the wet static coefficient of friction of the surface of the slip resistant article is measured by using the ASM 825A static coefficient of friction tester. Three different regions are randomly selected from the surface of the slip resistant article, and the wet static coefficient of friction is measured respectively to calculate the average.

According to the standards once provided by Underwriters Laboratories (UL) and the American Society for Testing and Materials (ASTM):

0.50-0.59 Basically safe

Above 0.60 Very safe

If the average of the dry static coefficient of friction is greater than 0.6, it indicates that the surface of this slip resistant article has good slip resistance performance under dry conditions. The larger the value, the better the slip resistance performance.

If the average of the wet static coefficient of friction is greater than 0.6, it indicates that the surface of this slip resistant article has good slip resistance performance under wet conditions. The larger the value, the better the slip resistance performance.

The test results of the dry and wet static coefficient of friction of the slip resistant coatings and slip resistant articles provided by the Examples and Comparative Examples of the present invention are listed in Table 3.

Abrasion Resistance Performance Test

The abrasion resistance performance of the slip resistant coatings or slip resistant articles is characterized by the dry abrasion test in the present invention.

The equipment for testing the abrasion resistance performance is BYK Abrasion Tester, which is commercially available from BYK Company.

The slip resistant liquid is disposed on the surface of the substrate, forming a slip resistant coating on the surface of the substrate after drying, to obtain a slip resistant article comprising the substrate and the slip resistant coating.

Under the condition of 2.2 kg load, the surface of the slip resistant article is scrubbed by an abrasion medium which is a 3M 5100 pad commercially available from 3M Company. The wet static coefficient of friction is measured per 500 times of abrasion. The test is stopped when the wet static coefficient of friction is less than or equal to 0.6, and the number of tested abrasion cycles is recorded (one abrasion cycle refers to scrubbing back and forth once). If the number of abrasion cycles reaches 20,000 and the wet static coefficient of friction is still greater than 0.6, stop the test and record the number of abrasion cycles as 20,000.

If the number of abrasion cycles of a certain slip resistant article is tested to be greater than 5,000, it indicates that this slip resistant article has good abrasion resistance performance. The test results of the abrasion resistance performance of the slip resistant coatings and slip resistant articles provided by the Examples and Comparative Examples of the present invention are listed in Table 3. Surface Gloss Test

The present invention characterizes the influence of the slip resistant coatings on the appearance of the substrate through the surface gloss test.

The equipment for testing the surface gloss is Micro-Tri-Gloss gloss meter, commercially available from BYK-Gardner Company.

The slip resistant liquid is disposed on the surface of the substrate, forming a slip resistant coating on the surface of the substrate after drying, to obtain a slip resistant article comprising the substrate and the slip resistant coating.

The Micro-Tri-Gloss gloss meter is used to measure the surface gloss value of the slip resistant article. Three different regions are randomly selected from the surface of the slip resistant article, and the surface gloss values of 20°, 60°, and 85° are measured respectively, taking the average of the gloss values at respective angles.

The test results of the surface gloss of the slip resistant coatings and slip resistant articles provided by the Examples and Comparative Examples of the present invention are listed in Table 3. Preparation of Slip Resistant Liquid

Example 1

1.50 g of 3-glycidoxypropyltrimethoxysilane and 46.55 g of deionized water are added to a 100 ml glass bottle;

0.80 g of 5.48 wt.% aqueous solution of hydrochloric acid is added dropwise while stirring on a magnetic stirrer, and the pH is adjusted to 2-3;

After stirring continuously at room temperature for 1 hour, 0.25 g of

3-(2-aminoethyl)-aminopropyltrimethoxysilane is added;

After stirring continuously for 30 minutes, 0.90 g of aqueous dispersion of BINDZIL CC301 surface epoxy-modified silica nanoparticles (a solid content of 28 wt.%) is added; After stirring continuously for 15 minutes, a slightly cloudy slip resistant liquid is obtained.

Example 2

3.56 g of 3-glycidoxypropyltrimethoxysilane and 44.49 g of deionized water are added to a 100 ml glass bottle;

1.10 g of 5.48 wt.% aqueous solution of hydrochloric acid is added dropwise while stirring on a magnetic stirrer, and the pH is adjusted to 1-2;

After stirring continuously at room temperature for 1 hour, 0.85 g of 3-aminopropyltriethoxysilane is added;

After stirring continuously for 30 minutes, 1.79 g of aqueous dispersion of BINDZIL CC301 surface epoxy-modified silica nanoparticles (a solid content of 28 wt.%) is added;

After stirring continuously for 15 minutes, 1.00 g of 10 wt.% water solution of TRITON BG-10 surfactant is added;

After stirring continuously for 10 minutes, a slightly cloudy slip resistant liquid is obtained. Examples 3 to 12

The slip resistant liquid of Examples 3 to 12 is prepared in the same method as in Example 1, wherein the types and amounts of components included in the slip resistant liquid are listed in Table 2.

Comparative Example 1

15.00 g of 3-glycidoxypropyltrimethoxysilane and 190.00 g of deionized water are added to a 500 ml glass bottle;

2.00 g of 5.48 wt.% aqueous solution of hydrochloric acid is added dropwise while stirring on a magnetic stirrer, and the pH is adjusted to 2-3;

After stirring continuously at room temperature for 1 hour, 3.56 g of 3-aminopropyltriethoxysilane is added;

After stirring continuously for 30 minutes, 7.24 g of 10 wt.% water solution of TRITON BG-10 surfactant is added;

After stirring continuously for 10 minutes, a slightly cloudy slip resistant liquid is obtained. Comparative Example 2

The slip resistant liquid of Comparative Example 2 is prepared in the same method as in Comparative Example 1, wherein the types and amounts of components included in the slip resistant liquid are listed in Table 2.

Table 2. Slip resistant liquid formulations

In Example 12, the solution quickly becomes white and opaque after BINDZIL 2034/D is added.

Preparation and Performance Test for Slip Resistant Article

Example 13

The slip resistant article is prepared using the bar coating method, comprising the following steps: A vitrified tile (225 mm ^χ 150 mm ^χ 10 mm) is used as the substrate of the slip resistant article. The surface of the vitrified tile is first cleaned with liquefied detergent (White Cat brand, commercially available from SHANGHAI HEHUANG White Cat Ltd.), and then rinsed clean with deionized water, and subsequently blow-dried with compressed air;

10 g of the slip resistant liquid obtained in Example 1 is filtered twice through a 200-mesh filter screen.

The winding bar of the automatic bar coater (K303 Multicoater, commercially available from RK PrintCoat Instruments Ltd.) is placed at one end of the vitrified tile, and 5 g of the slip resistant liquid filtered out is dropped uniformly to the gap between the winding bar and the vitrified tile by a dropper;

At room temperature, the slip resistant liquid is bar-coated on the surface of the vitrified tile by using an automatic bar coater;

During the bar-coating process, the wet film thickness of the slip resistant liquid is about 6 μπι, and is recorded as T-6, as shown in Table 3;

The bar-coated vitrified tile is dried at room temperature for 18 hours to obtain a slip resistant article.

The slip resistance performance, abrasion resistance performance and surface gloss of the obtained slip resistant article are tested, and the results are listed in Table 3.

Examples 14 to 19

The slip resistant articles are prepared using the same method as in Example 13, wherein the types of the substrates, the bar coating conditions and heat treatment conditions of the slip resistant articles are listed in Table 3.

As shown in Table 3, if the wet film thickness during the bar-coating process is 1.5 μπι, it is recorded as T- 1.5; if the wet film thickness during the bar-coating process is 3 μπι, it is recorded as T-3; if the wet film thickness of the slip resistant liquid during the bar-coating process is 6 μπι, it is recorded as T-6; if the wet film thickness of the slip resistant liquid during the bar-coating process is 12 um, it is recorded as T-12.

The slip resistance performance, abrasion resistance performance and surface gloss of the obtained slip resistant article are tested, and the results are listed in Table 3.

Example 20

The slip resistant article is prepared by using the dip coating method, comprising the following steps:

A glass substrate (180 mm ^χ 100 mm ^χ 3 mm) is used as the substrate of a slip resistant article. The surface of the glass substrate is first cleaned with a liquefied detergent (White Cat brand, commercially available from SHANGHAI HEHUANG White Cat Ltd.), and then rinsed clean with deionized water, and subsequently blow-dried with compressed air;

200 g of slip resistant liquid obtained in Example 3 is poured into a 400 ml stainless steel tank (150 mm x 150 mm ^χ 20 mm);

At room temperature, by using an automatic dip coater (SKVDX2S-500, commercially available from KSV NIMA Company), the glass substrate is dip-coated in the slip resistant liquid;

The immersion speed of the dip coating process is 300 mm/min, the immersion time is 1 minute, and the pulling speed is 300 mm/min, as listed in Table 3 in detail.

The dip-coated glass substrate is heated in an oven to dry at 120 °C for 10 minutes and then taken out, and cooled to room temperature to obtain a slip resistant article.

The slip resistance performance, abrasion resistance performance and surface gloss of the obtained slip resistant article are tested, and the results are listed in Table 3.

Example 21

The slip resistant article is prepared by using the wipe coating method, comprising the following steps:

A vitrified tile (225 mm ^χ 150 mm ^χ 10 mm) is used as the substrate of the slip resistant article. The surface of the vitrified tile is first cleaned with liquefied detergent (White Cat brand, commercially available from SHANGHAI HEHUANG White Cat Ltd.), and then rinsed clean with deionized water, and subsequently blow-dried with compressed air.

Spun-bonded polypropylene non-woven fabric (commercially available from 3M Company) is cut into a 50 mm ^χ 20 mm strip. 6 g of the slip resistant liquid obtained in Example 4 is drawn off with a dropper. 3 g of the slip resistant liquid is dropped to one end of the vitrified tile, and the other 3 g is dropped to the middle of the vitrified tile. The non-woven fabric is pressed by hand on the vitrified tile, and the substrate is coated once uniformly from the end with the slip resistant liquid to the end without the liquid.

The wipe-coated vitrified tile is dried at room temperature for 24 hours to obtain a slip resistant article.

The slip resistance performance, abrasion resistance performance and surface gloss of the obtained slip resistant article are tested, and the results are listed in Table 3.

Examples 22 to 29

The slip resistant articles are prepared using the same method as in Example 13, wherein the types of the substrates, the bar coating conditions and heat treatment conditions of the slip resistant articles are listed in Table 3.

The slip resistance performance, abrasion resistance performance and surface gloss of the obtained slip resistant articles are tested, and the results are listed in Table 3.

Comparative Example 3

The slip resistant article is prepared using the bar coating method, comprising the following steps: A vitrified tile (225 mm ^χ 150 mm ^χ 10 mm) is used as the substrate of the slip resistant article. The surface of the vitrified tile is first cleaned with liquefied detergent (White Cat brand, commercially available from SHANGHAI HEHUANG White Cat Ltd.), and then rinsed clean with deionized water, and subsequently blow-dried with compressed air.

10 g of the slip resistant liquid obtained in Comparative Example 1 is filtered twice through a 200-mesh filter screen.

The winding bar of the automatic bar coater (K303 Multicoater, commercially available from RK PrintCoat Instruments Ltd.) is placed at one end of the vitrified tile, and 5 g of the slip resistant liquid filtered out is dropped uniformly to the gap between the winding bar and the vitrified tile by a dropper;

At room temperature, the slip resistant liquid is bar-coated on the surface of the vitrified tile by using an automatic bar coater. During the bar-coating process, the wet film thickness of the slip resistant liquid is about 6 μιη, and is recorded as T-6, as shown in Table 3.

The bar-coated vitrified tile is dried at room temperature for 18 hours to obtain a slip resistant article.

The slip resistance performance, abrasion resistance performance and surface gloss of the obtained slip resistant article are tested, and the results are listed in Table 3.

Comparative Example 4

The slip resistant article used as Comparative Example 4 is prepared using the same method as in Comparative Example 3, wherein the types of the substrates, the bar coating conditions and heat treatment conditions of the slip resistant article are listed in Table 3.

The slip resistance performance, abrasion resistance performance and surface gloss of the obtained slip resistant article are tested, and the results are listed in Table 3. Comparative Examples 5 to 10

The vitrified tile, glazed tile, microlite stone, artificial stone, marble and glass substrate uncoated with the slip resistant coating are used as Comparative Examples 5 to 10, and the detailed information thereof is listed in Table 3.

The slip resistance performance and surface gloss of the substrate uncoated with the slip resistant coating are tested, and the results are listed in Table 3.

Table 3. Preparation of the slip resistant articles and tests of slip resistance performance, abrasion resistance performance and surface gloss

Comparative Glass

1.14 0.31

Example 10 substrate

Note: ^{( )} T-1.5: The wet film thickness is controlled to be approximately 1.5 um by the bar used during the bar coating process;

( ²⁾ T-12: The wet film thickness is controlled to be approximately 12 μιη by the bar used during the bar coating process;

In Example 26, a lot of powders drop off the coating surface after bar coating and heat treatment so that the slip resistance, abrasion resistance and surface gloss cannot be tested;

In Example 27, a lot of powders drop off the coating surface after bar coating and heat treatment so that the slip resistance, abrasion resistance and surface gloss cannot be tested;

In Example 28, a lot of powders drop off the coating surface after bar coating and heat treatment so that the slip resistance, abrasion resistance and surface gloss cannot be tested;

In Example 29, a lot of powders drop off the coating surface after bar coating and heat treatment so that the slip resistance, abrasion resistance and surface gloss cannot be tested.

As shown in Table 3, the substrates uncoated with the slip resistant coating provided by

Comparative Examples 5 to 10 show wet static coefficient of friction less than 0.6, and thus have poor slip resistance performance under wet conditions. The dry static coefficient of friction of slip resistant articles provided according to Examples 13 to 22 can slightly increase or remain unchanged compared to that of the substrates uncoated with slip resistant coating, and the wet static coefficient of friction thereof increases dramatically compared to that of the substrates uncoated with slip resistant coating, and is all significantly greater than 0.6. Therefore, these slip resistant articles have good slip resistance performance under both dry and wet conditions.

As shown in Table 3, the slip resistant article provided according to Comparative Example 3 has a cycle number of 3,500 for the abrasion resistance performance test. The slip resistant article provided according to Comparative Example 4 has a cycle number of 4,000 for the abrasion resistance performance test. The slip resistant articles provided according to Examples 13 to 22 have a dramatically increased cycle number for the abrasion resistance performance test than those without surface epoxy-modified silica particles provided according to Comparative Examples 3 to 4, and their cycle numbers are all significantly greater than 5,000. Therefore, these slip resistance articles have good abrasion resistance performance.

As shown in Table 3, the surface gloss of the slip resistant articles provided according to Examples 13 to 22 can increase or remain unchanged compared to that of the substrates uncoated with the slip resistant coating provided by Comparative Examples 5 to 10. Therefore, these slip resistant articles have good appearance.

As shown in Table 3, since the percentage amounts of some reaction components in the slip resistant liquid are out of claimed ranges of the present invention, the slip resistant articles provided according to Examples 23 to 25 have poor appearance. Their slip resistance performance and/or abrasion resistance performance cannot meet the use requirements of the present invention.

As shown in Table 3, since surface unmodified silica particles or surface non-epoxy modified silica particles have poor compatibility with the slip resistant liquid system, the slip resistant articles provided according to Examples 26 to 29 cannot form a film on the surface of the substrate. Therefore, the slip resistance performance, abrasion resistance performance and surface gloss of these slip resistant articles cannot be tested.

Although for purposes of illustration, the specific embodiments described above contain many specific details, but a skilled person in the art will appreciate that many variations, modifications, substitutions and changes of such details fall within the protection scope of the present invention, which is indicated by the claims. Therefore, the disclosure described in the embodiments does not make any restriction of the protection scope of the present invention, which is indicated by the claims. The appropriate scope of the present invention should be defined by the claims and the appropriate legal equivalents.