JP2805825B2 - leather - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to leather.

[Prior Art] Conventionally, leathers that have been protectively coated with a coating material having relatively excellent weather resistance, such as acrylic resin, are often used for the purpose of improving durability and antifouling properties.

[Problems to be Solved by the Invention] Conventionally, what is known as weather-resistant leather is superior in antifouling property and durability as compared with non-coated leather, but is protected for long-term use. The adhesion between the coat and the sheet was poor, and it was not sufficiently usable.

An object of the present invention is to solve the above-mentioned problems of the prior art, that is, to provide a leather having excellent weather resistance, long-term antifouling property, and excellent protective coat adhesion.

Means for Solving the Problems The present invention comprises, on a thermoplastic resin sheet, a fluorine-containing copolymer (a) having a crosslinked site and an acrylic polymer (b) compatible with (a) as a main component. The present invention provides a leather formed by forming a paint film.

Examples of the thermoplastic resin as the base material of the leather of the present invention include a vinyl chloride resin, a polyethylene resin, and a polyester resin. Among them, a vinyl chloride resin, particularly a soft vinyl chloride resin, is most generally used.

As such a vinyl chloride resin, in addition to a vinyl chloride homopolymer, vinyl chloride and vinyl acetate, ethylene, propylene, (meth) acrylic acid ester [acrylic acid ester and methacrylic acid ester, the same applies hereinafter] Copolymers of at least 40% by weight, preferably 30% by weight or less, of one or more monomers such as, and polymers which are compatible with these homopolymers or copolymers, for example, An ethylene-vinyl acetate copolymer, a vinyl chloride-vinyl acetate copolymer, or the like may be blended.

In addition, an appropriate amount of a plasticizer is blended with the vinyl chloride resin, and is often used as a soft vinyl chloride resin.
The amount of the plasticizer is preferably about 30 to 70 parts by weight per 100 parts by weight of the vinyl chloride resin.
Examples of the plasticizer include dibutyl phthalate, dioctyl phthalate, diisodecyl adipate, tricresyl phosphate, epoxidized soybean oil, and epoxidized linseed oil. Ordinary additives such as a lubricant, an antioxidant, an antistatic agent, a heat stabilizer, a colorant, and a flame retardant may be added to the vinyl chloride resin.

Further, a surfactant may be added to the vinyl chloride resin for the purpose of preventing fogging. As the surfactant, a nonionic surfactant is preferably employed.

In the present invention, as a coating material for forming a film on the thermoplastic resin sheet, a fluorinated copolymer (a) having a crosslinked site and an acrylic polymer (b) compatible with (a) are mainly used. Is adopted.

Here, as the fluorine-containing copolymer (a) having a cross-linking site, a solvent-soluble fluorine-containing copolymer having a fluorine content of 10% by weight or more based on a fluoroolefin unit is preferably employed.

The fluorine-containing copolymer (a) has a fluorine content of 10% by weight or more, preferably 10 to 70% by weight, more preferably 15 to 50% by weight based on the fluoroolefin unit, and is in an uncured state. And an intrinsic viscosity measured in tetrahydrofuran of 0.01 to 4.0 dl / g.

If the fluorine content is less than 10% by weight, the intended effect of improving weather resistance is reduced. Further, when the intrinsic viscosity is within the above range, the paintability as a coating material is good, and the physical properties of the formed film are also excellent. As such a fluorinated copolymer, a copolymer with an ethylenically unsaturated compound is preferably employed as a fluoroolefin and a comonomer copolymerizable with the fluoroolefin.

Examples of such a fluoroolefin include tetrafluoroethylene, chlorotrifluoroethylene, trifluoroethylene, vinylidene fluoride, hexafluoropropylene, pentafluoropropylene and the like. Of these, tetrafluoroethylene, chlorotrifluoroethylene, vinylidene fluoride and hexafluoropropylene are particularly preferably employed.

Further, as the ethylenically unsaturated compound as a monomer copolymerizable with a fluoroolefin, olefins,
Examples thereof include vinyl ethers, vinyl esters, allyl ethers, allyl esters, and compounds containing a (meth) acryloyl group.

Among these, olefins having excellent copolymerizability with fluoroolefins, vinyl ethers, vinyl esters, allyl ethers having a linear, branched or alicyclic alkyl group having about 1 to 10 carbon atoms. Are preferred.

In the fluorinated copolymer (a), the unit based on the fluoroolefin preferably contains 30 to 70 mol%,
If it is less than 30 mol%, the effect of improving weather resistance is not sufficient,
If it is more than 70 mol%, the solubility in a solvent tends to decrease, which may hinder the application operation as a paint. In the copolymer, the fluoroolefin and the ethylenically unsaturated compound may be used alone or in combination of two or more.

Among the main components of the paint of the present invention, the fluorine-containing copolymer (a) having a cross-linking site reacts with another component, a curing agent, or a copolymer to form a three-dimensional network structure, A film having a cross-linking site is preferably employed because it gives a favorable result of improving the solvent resistance, acid resistance and alkali resistance of the coating.

As the crosslinking site, a hydroxyl group, a carboxylic acid group, an acid amide group, an amino group, an active hydrogen-containing group such as a mercapto group,
Examples include epoxy groups, carbon-carbon unsaturated groups, active halogens such as bromine and iodine. Of these, active hydrogen-containing groups are preferred in that they have excellent reactivity with isocyanate-based curing agents, aminoplast-based curing agents, and the like, which are usually used as curing agents, and hydroxyl groups are particularly preferred.

The method for introducing such a cross-linking site into the copolymer includes, for example, cross-linking of hydroxyalkyl vinyl ether, hydroxyalkyl allyl ether, hydroxyallyl vinyl ether, hydroxyalkyl allyl ether, glycidyl vinyl ether, (meth) acrylic acid, aryl vinyl ether, diaminoethyl vinyl ether, etc. A method in which a monomer having a reactive site is copolymerized, or a method in which an acid anhydride, an isocyanate, an alkyl (meth) acrylate, or the like is added to a fluorinated copolymer by reacting the same is employed.

In addition, as a method of decomposing a part of the copolymer, after copolymerizing a monomer having a hydrolyzable ester group, a carboxylic acid group or a carboxylic acid group in the copolymer is obtained by hydrolyzing the copolymer. A method of generating a hydroxyl group is also employed.

Furthermore, a method of introducing a carboxylic acid group by reacting a divalent carboxylic anhydride such as succinic acid with a hydroxyl group-containing copolymer is also employed.

The acrylic polymer (b) compatible with the fluorinated copolymer (a), which is a main component of the paint of the present invention, is an alcohol ester of (meth) acrylic acid having 1 to 12 carbon atoms, It is an acrylic polymer having a molecular weight of 500 to 80,000.

Monomers for constituting such an acrylic polymer include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl methacrylate,
Examples include tert-butyl (meth) acrylate and (meth) acrylonitrile.

Preferably, a copolymer of two or more of these monomers, or a copolymer with an alcoholic ester of acrylic acid other than those described above, styrene, maleic acid, vinyl esters (eg, vinyl acetate), vinyl silane, or the like is used. Coalescing is used. More preferably, in the acrylic polymer, a polymer having a cross-linking site is cross-linked by a reaction with a cross-linking site of a fluorinated copolymer, and a coating film of the coating material has a three-dimensional network structure and exhibits excellent characteristics.

Here, in the acrylic polymer (b), the cross-linking site is preferably a hydroxyl group, a glycidyl group, an amide group, a silanol group, or the like.

For example, the introduction of a hydroxyl group is performed by 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate,
-Hydroxybutyl (meth) acrylateo, 4-hydroxybutyl (meth) acrylate, 3-chloro-2-hydroxypropyl (meth) acrylate and the like, and glycidyl group is introduced by glycidyl (meth) acrylate,
(Β-methyl) glycidyl (meth) acrylate, etc.
Furthermore, the introduction of an amide group is (meth) acrylamide, dimethyl (meth) acrylamide, N-tert-butyl (meth) acrylamide, N-octyl (meth) acrylamide, diacetone (meth) acrylamide, and the introduction of a silanol group is vinylsilane. And a comonomer that gives the acrylic polymer or copolymer described above.

The silanol group can also be introduced by a method of adding an isocyanate silane or a silane coupling agent to a hydroxyl group-containing acrylic polymer.

Here, the acrylic polymer (b) may be a mixture of a polymer having a cross-linking site and a polymer having no cross-linking site. Does not include a copolymer with a monomer having a hydroxyl group, a glycidyl group, an amide group, or the like.

The proportion of the acrylic polymer having no crosslinking site is preferably 50% by weight based on the acrylic polymer having the crosslinking site.
Up to.

Further, a curing agent can be blended with (a) and (b), which are the main components of the paint, and they are compatible with the fluorine-containing copolymer (a) and the acrylic polymer (b), and are cured. What is used is used.

As such a curing agent, polyisocyanates, for example, non-yellowing diisocyanates such as hexamethylene diisocyanate and isophorone diisocyanate, and adducts thereof, and blocked isocyanates in which isocyanate groups are blocked with a blocking agent such as phenol are preferably used. Can.

Various curing agents such as melamine, metal alkoxide, urea resin, polybasic acid, epoxy and silanol can also be used.

Here, when the crosslinking site of the fluorinated copolymer (a) is a hydroxyl group, a polyisocyanate-based or metal alkoxide-based is preferred. Melamine partially etherified with one or more lower alcohols such as methanol, ethanol, propanol and butanol is particularly preferable as the melamine-based curing agent.

Such a curing agent has a very useful effect on formation of a three-dimensional network structure of a copolymer or a polymer having a crosslinking site.

For the purpose of accelerating the curing together with the curing agent, a catalyst may be used in combination.Examples of such curing assistants include dibutyltin dilaurate as an isocyanate-based curing agent and a paratoluenesulfonic acid-based catalyst as a melamine-based curing agent. It is used in a ratio of 0.001 to 2 parts by weight based on 100 parts by weight of the fluorocopolymer.

The respective proportions of the main constituent components in the coating material of the present invention are preferably 30 to 90% by weight of the fluorine-containing copolymer (a) and 10 to 70% by weight of the acrylic polymer (b).
If the fluorine-containing copolymer is small, the fluorine content decreases,
The desired effect of improving the weather resistance is not achieved. On the other hand, when the amount of the acrylic polymer is small, the adhesiveness to the substrate is reduced.

Each of the fluorine-containing copolymer and the acrylic polymer is not limited to one type within the above range, and two or more types may be used in combination. The curing agent is used at a ratio of 0 to 20% by weight based on the total amount of the fluorocopolymer and the acrylic polymer.

In addition to the main constituent components, the coating material contains a UV absorber in an amount of 0.5 to 20% based on the total amount of the fluorine-containing copolymer and the acrylic polymer, so that the weather resistance can be further improved.

Examples of such ultraviolet absorbers include conventionally known or well-known 2-hydroxybenzophenone, 2,4-dihydroxybenzophenone, 2-hydroxy-4-n-octoxybenzophenone, and 2-hydroxy-4- (1-methyl-2).
Benzophenones such as -hydroxy) ethoxybenzophenone, 2-hydroxy-4- (2-hydroxy-3-methacryloxy) propoxybenzophenone, or 2- (2'-hydroxy-5'-methylphenyl) benzotriazole, 2- (2 '-Hydroxy-3', 5'-
A benzotriazole-based compound such as di-tert-butylphenyl) benzotriazole is used alone or in combination.

Furthermore, an acrylic polymer (c) having a fluoroalkyl group may be added to such a paint to improve the water repellency of the leather. When the acrylic polymer (c) having such a fluoroalkyl group has a crosslinking site similar to that of the fluorinated copolymer (a) or the acrylic polymer (b), the water repellency and the like are long. Is preferable because it is held over

The addition amount of the acrylic polymer (c) having such a fluoroalkyl group is in the range of about 0.1 to 30 parts by weight per 100 parts by weight of the total of the fluorine-containing copolymer (a) and the acrylic polymer (b). Is preferred.

In addition, for the purpose of specific improvement, paints include, for example, an antifoaming agent, an antistatic agent, a pigment, a dispersion stabilizer, a viscosity modifier,
Additives such as a leveling agent and an anti-gelling agent can also be added. The compounding of the pigment has the effect of hiding the coating. In addition, a primer can be used for the purpose of obtaining necessary bending adhesion and the like.

The coating material of the present invention comprises the above-mentioned main components such as the fluorine-containing copolymer (a) and the acrylic copolymer (b), and if necessary, a curing agent, an ultraviolet absorber, and an acrylic having a fluoroalkyl group. It can be obtained by dissolving the system polymer (c) and other additives in an organic solvent.

Examples of the solvent used include aromatic hydrocarbons such as toluene and xylene, alcohols such as propanol and butanol, esters such as ethyl acetate and butyl acetate, ketones such as methyl ethyl ketone and methyl isobutyl ketone, and ethyl cellosolve. Various general organic solvents such as glycol ethers and various commercially available thinners. The concentration of the coating component is adjusted to 1 to 60% by weight, preferably 5 to 50% by weight, which is suitable for workability of forming a coating.

In preparing the paint, for example, ball mill, paint shaker, sand mill, jet mill, three rolls,
It is carried out by using various devices used for ordinary coating, such as a kneader, and is not particularly limited. At this time, additives such as those described above can be added.

In the present invention, the method of forming a coating film of the coating on the thermoplastic resin sheet, brush coating the molded article, spray spraying, applying by a flow coater or the like, or applying by dipping the sheet in the coating, The film is dried sufficiently to evaporate the solvent, and then heated or left at room temperature to form a film. The heat treatment at this time is performed at a temperature not higher than the temperature at which the molded body is not deformed, and for example, treatment at 60 ° C. for 10 minutes is sufficient.

A sufficient effect is recognized when the thickness of the formed coating film is 2 to 100 μm. The adjustment of the thickness of the film is determined by the component concentration of the paint and the application conditions, but there is no problem even if it is formed into a multilayer film. The shape of the molded body is not limited at all.

[Examples] Examples 1 to 11, Comparative Examples 1 to 3 Fluorine-containing copolymer (a), acrylic polymer (b), acrylic polymer having fluoroalkyl group (c) shown in Table 1 , Xylene as solvent (d), coronate EH (manufactured by Nippon Polyurethane) as isocyanate-based curing agent (e), benzophenone-based ultraviolet absorber (f)
Coatings 1 to 13 having the composition (numerical value: parts by weight) consisting of Biosorb 130 (manufactured by Kyodo Yakuhin) as a sample were prepared.

In Table 1, the fluorinated copolymer (a) and acrylic polymer (b) used are as follows.

FA: a copolymer having a ratio of TFE (tetrafluoroethylene) / HBVE (ω-hydroxybutyl vinyl ether) / n-BVE (n-butyl vinyl ether) = 48.1 / 12.5 / 39.4 (% by weight); A copolymer having an intrinsic viscosity (referred to as [η]) at 30 ° C. of 0.15 dl / g (hereinafter the same).

FB: CTFE (chlorotrifluoroethylene) / HBVE / CHVE
(Cyclohexyl vinyl ether) / EVE (ethyl vinyl ether) = 56.4 / 5.7 / 12.4 / 25.5, [η] = 0.21 dl / g.

FC: HFP (Hexafluoropropylene) / HBVE / n-BVE
= 66.7 / 8.0 / 25.3, [η] = 0.08 dl / g.

FD: TFE / vinyl acetate / CH ₂ = CHCH ₂ OCH ₂ CH ₂ OH = 5
3.7 / 23.1 / 23.2, [η] = 0.18 dl / g.

FE: CTFE / EVE / HBVE / Veova 9 (vinyl ether having a branched alkyl group having 9 carbon atoms manufactured by Shell Chemical Co.) =
39.4 / 17.2 / 9.5 / 33.9, [η] = 0.40dl / g.

FF: TFE / EVE / HBVE / CH ₂ = CHOCH ₂ CF ₂ CF ₂ H = 57.0 / 22.4 / 1
0.8 / 9.8, [η] = 0.10 dl / g.

M-1: Copolymer copolymerized at a ratio of isobutyl methacrylate / n-butyl acrylate / 2-hydroxyethyl methacrylate = 7/2/1 (molar ratio) (hereinafter the same).

M-2: methyl acrylate / n-butyl acrylate / glycidyl acrylate = 8/1/1.

M-3: n-butyl methacrylate / isobutyl methacrylate / acrylonitrile / 2-hydroxyethyl methacrylate = 1/7/1/1.

M-4: methyl methacrylate / n-butyl methacrylate = 5/5.

In addition, the acrylic polymer (c) having a fluoroalkyl group is as follows: CH ₂ = CHCOOCH ₂ CH ₂ (CF ₂ ) ₁₀ F / isobutyl methacrylate / n-butyl acrylate / 2-hydroxyethyl methacrylate = 20/60/10 / 10% by weight of the copolymer.

Coatings 1 to 13 are applied to the surface of the leather by adjusting the thickness of the coating formed by a gravure coater to 10 μm, dried at room temperature, and then heated at 60 ° C. for 10 minutes to form a cured coating. did.

Table 2 shows the results of the following evaluation tests performed on the leather having the coating film formed as described above.

Contact angle: The contact angle of water and n- hexadecane (in the table referred to as C ₁₆₎ (unit: °) is measured.

Adhesion: The adhesion of the coating is measured in accordance with the method of ASTM-3359 initially, after immersion in warm water (60 ° C. × 30 days), and after treatment for 1000 hours with a sunshine weather meter, and evaluated based on the number of squares remaining.

Weather resistance: Measured by a color measuring device (SM-3 manufactured by Suga Test Instruments Co., Ltd.) before and after the treatment with the sunshine weather meter for 1000 hours, and its yellowing deterioration is determined as a difference (ΔE) between before and after the treatment.

Example 12 The same procedure as in Example 1 was carried out except that the drying conditions were changed to 120 ° C. for 1 minute, and almost the same effects as in Example 1 were obtained.

[Effects of the Invention] The leather of the present invention is extremely excellent in weather resistance because a coating of a specific paint is formed while maintaining good adhesion.

Continuation of the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) D06N 7/04 E04F 15/16 A B32B 27/30 D B32B 27/30 A C08J 7/04 D06N 3/08

Claims (4)

(57) [Claims] 1. A coating film mainly composed of a fluorine-containing copolymer (a) having a cross-linking site and an acrylic polymer (b) compatible with (a) is formed on a thermoplastic resin sheet. Leather. 2. The leather according to claim 1, wherein the acrylic polymer (b) has a crosslinked site. 3. The leather according to claim 1, wherein the coating further comprises an acrylic polymer (c) having a fluoroalkyl group. 4. The leather of claim 1, 2 or 3, wherein the paint further comprises a curing agent.