JP2010275344A - Coating agent for polyester film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coating agent capable of forming a coating layer of good adhesion to a polyester film such as polyethylene terephthalate, without treatment such as primer coating to give adhesion to the film surface. <P>SOLUTION: This resin composition for coating the polyester film includes a polymer (A) produced by radical polymerization of vinyl monomers which include an aromatic group-containing vinyl monomer (for example styrene) and an α,β-unsaturated dicarboxylic acid derivative (especially a fumarate derivative) as essential components. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a coating agent particularly suitable for surface coating of plastic such as PET (polyethylene terephthalate) film.

In recent years, applications of liquid crystal displays such as televisions, personal computers and mobile phones have been expanded, and brighter liquid crystal displays have been demanded. In order to improve the brightness of the liquid crystal display, light diffusibility and light transmittance in the light diffusing film of the backlight unit are important. About 90% of the liquid crystal display uses PET film. The light diffusibility is further enhanced by applying a coating agent in which an acrylic resin is used as a binder and a filler such as acrylic beads to a PET film on an actual base film. However, since the PET film itself is a base material that hardly adheres to the coating agent, a method for attaching these coating agents is required.
At present, it has been relatively easy to attach the coating agent to the PET film itself by performing surface modification such as plasma surface treatment or chemical treatment. For example, in order to provide adhesion, a polyester film having good adhesion has been proposed by forming a coating layer of aqueous urethane, aqueous acrylic, aqueous polyester or the like in the form of a biaxially stretched polyester film, and then stretching again. For example, see Patent Document 1.)
However, although the above method is effective for imparting adhesiveness, it needs to be stretched again at a high temperature, and there is a problem that high adhesion cannot be obtained if the stretching operation is omitted. Therefore, liquid crystal display manufacturers are pursuing cost reduction and are shifting to untreated PET films that do not undergo surface modification. This makes it difficult to attach the coating agent.

Japanese Patent No. 3211350

  An object of the present invention is to provide a coating agent capable of forming a coating layer with good adhesion on a polyester film such as polyethylene terephthalate without treatment such as primer application for adhesion to the film surface. is there.

  As a result of intensive studies, the present inventor has applied a coating agent containing a copolymer having fumaric acid diesters and an aromatic vinyl compound as essential components as a result of intensive studies. The inventors found that the adhesion was good and completed the invention.

  That is, the present invention provides a polymer (A) obtained by radical polymerization of vinyl monomers having an aromatic group-containing vinyl monomer and an α, β-unsaturated dicarboxylic acid derivative as essential components. A polyester film coating resin composition is provided.

  By using the resin composition of the present invention as a binder, it becomes possible to form various coating layers having good adhesion regardless of the presence or absence of surface treatment of the polyester film (for example, PET film) itself. It was possible to attach a coating agent for the purpose of improving light diffusibility such as acrylic beads to PET film.

Examples of the α, β-unsaturated dicarboxylic acid derivative used in the present invention include those having the structure of the following general formula (1). (R ₁ and R ₂ in the following general formula (1) each independently represent a hydrogen atom or an alkyl group having 1 to 12 carbon atoms.)

Examples of the compound represented by the general formula (1) include maleic acid or fumaric acid, or dialkyl esters obtained by esterifying maleic acid or fumaric acid with an alcohol having 1 to 12 carbon atoms. Specific examples thereof include dimethyl fumarate, diethyl fumarate, di-n-propyl fumarate, di-iso-propyl fumarate, di-n-butyl fumarate, di-iso-butyl fumarate, fumaric acid. Di-tert-butyl, di (2-ethylhexyl) fumarate, dimethyl maleate, diethyl maleate, di-n-propyl maleate, di-iso-propyl maleate, di-n-butyl maleate, maleic acid Examples include di-iso-butyl, di-tert-butyl maleate, and di (2-ethylhexyl) maleate.
Among these, fumaric acid dialkyl esters are preferable in that they have a remarkable effect in improving the adhesion of the polyester film.

  Examples of the aromatic group-containing vinyl monomer used in the present invention include p-methylstyrene, α-methylstyrene, p-chlorostyrene, chloromethylstyrene, vinyltoluene and the like.

If the polymer used in the present invention contains the α, β-unsaturated dicarboxylic acid derivative (a) and the aromatic group-containing vinyl monomer (b), other monomers May be used in combination to produce a copolymer. The total content of (a) and (b) is preferably 40 parts by weight or more per 100 parts by weight (solid content) of the copolymer.
The blending ratio [(a) / (b)] (weight ratio) of the α, β-unsaturated dicarboxylic acid derivative (a) and the aromatic group-containing vinyl monomer (b) is 0.4 to 2.4 is preferable. It is especially preferable that it is 0.5-1.0.

  The other monomers other than the above are not particularly limited as long as they are compounds copolymerizable with the α, β-unsaturated dicarboxylic acid derivative (a) and the aromatic group-containing vinyl monomer (b). .

  For example, methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, hexyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, nonyl (meth) Acrylic unsaturated monomers of alkyl (meth) acrylates having 1 to 30 carbon atoms such as acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate;

Maleic acid or its monoester, fumaric acid monoester, itaconic acid or its monoester, carboxylic acid group-containing unsaturated monomers such as crotonic acid, p-vinylbenzoic acid, and salts thereof; 2- (meth) acrylamide 2-Methylpropanesulfonic acid, vinylsulfonic acid, styrenesulfonic acid, (meth) allylsulfonic acid, sulfoethyl (meth) acrylate, sulfopropyl (meth) acrylate, α-methylstyrenesulfonic acid-containing unsaturated Monomers and their salts;

Dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, vinylpyrrolidone, N-methylvinylpyridium chloride, (meth) allyltriethylammonium chloride, 2-hydroxy-3- (meth) acryloyloxypropyltrimethylammonium chloride, etc. A tertiary or quaternary amino group-containing unsaturated monomer; a hydroxyl-containing unsaturated monomer such as hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, or polyethylene glycol mono (meth) acrylate; ) Amide-containing unsaturated monomers such as acrylamide, N-hydroxyalkyl (meth) acrylamide, N-alkyl (meth) acrylamide, N, N-dialkyl (meth) acrylamide, vinyl lactams

Nitrile unsaturated monomers such as acrylonitrile and methacrylonitrile; conjugated diolefin unsaturated monomers such as butadiene and isoprene; divinylbenzene, ethylene glycol diacrylate, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, allyl methacrylate, Polyfunctional unsaturated monomers such as diallyl phthalate, trimethylolpropane triacrylate, glyceryl diallyl ether, polyethylene glycol dimethacrylate, and polyethylene glycol diacrylate; vinyl unsaturated monomers such as ethylene, propylene, and isobutylene; vinyl acetate , Vinyl propionate, octyl vinyl ester, Veova 9, Veova 10, Veova 11 [Beova: Trademark of Shell Chemical Company, Ltd.] Monomers: Vinyl ether unsaturated monomers such as ethyl vinyl ether, propyl vinyl ether, butyl vinyl ether, cyclohexyl vinyl ether; Allyl ether unsaturated monomers such as ethyl allyl ether; Vinyl chloride, vinyl bromide, vinylidene chloride, vinylidene fluoride Halogen-containing unsaturated monomers such as chlorotrifluoroethylene, tetrafluoroethylene, hexafluoropropylene, pentafluoropropylene, perfluoro (propyl vinyl ether), perfluoroalkyl acrylate and fluoromethacrylate;

Epoxy group-containing unsaturated monomers such as glycidyl acrylate and glycidyl methacrylate; vinyl silanes such as vinyltrichlorosilane, vinyltriethoxysilane, vinyltris (β-methoxyethoxy) silane, and γ-methacryloxypropyltrimethoxysilane Unsaturated monomers containing carbonyl groups such as acrolein, diacetone acrylamide, vinyl methyl ketone, vinyl butyl ketone, diacetone acrylate, acetonitrile acrylate, acetoacetoxyethyl (meth) acrylate, vinyl acetophenone, vinyl benzophenone Examples include the body.

  As a weight average molecular weight of a polymer (A), it is preferable that it is 3000-100000 that adhesiveness is favorable. Moreover, it is also preferable for the said reason that a glass transition temperature is 0 degreeC-90 degreeC. The glass transition temperature was measured by the method described later.

  A polymer obtained by polymerizing an aromatic group-containing vinyl monomer used in the present invention and a polymerizable monomer having an α, β-unsaturated dicarboxylic acid derivative as an essential component is polymerized to an appropriate molecular weight and remains as it is. It may be dissolved in various organic solvents and used as an organic solvent solution.

  Further, a monomer having a reactive functional group (for example, a hydroxyl group) may be copolymerized and used in combination with a corresponding curing agent.

  As an example of the above, in combination with a hydroxyl group-containing unsaturated monomer such as hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, polyethylene glycol mono (meth) acrylate, and the like, an active hydrogen-containing group (hydroxyl group) and A reactive isocyanate group-containing compound or blocked isocyanate may be blended and applied and then cured. Examples of the isocyanate compound include aromatic diisocyanates such as tolylene diisocyanate and diphenylmethane diisocyanate; various aliphatic diisocyanates such as hexamethylene diisocyanate and trimethylhexamethylene diisocyanate; and alicyclic diisocyanates such as isophorone diisocyanate; Diisocyanates, polyhydric alcohols such as ethylene glycol, trimethylolethane or trimethylolpropane, polyether polyols such as polyethylene glycol or polypropylene glycol, and polycaprolactone polyols having functional groups that react with isocyanate groups Low molecular weight polyester resins (including oil-modified types) and acrylic copolymers Or an isocyanate having a burette structure; isocyanurate ring-containing isocyanates obtained by cyclizing diisocyanates; and those obtained by blocking isocyanates with a known and conventional blocking agent.

  Examples of typical commercially available isocyanates include “Bernock DN-950, Burnock DN-980, Burnock DN-981, Burnock DN-992, Burnock D-550” [all Dainippon Ink and Chemicals, Inc. ) Product], "Duranate 24A-100, Duranate THA-100, Duranate TPA-B80X" [Asahi Kasei Kogyo Co., Ltd. product], "Coronate HK, Coronate 2507" [All Japan Polyurethane Urethane Industry Co., Ltd.] Product], “Takenate D-140N” [Takeda Pharmaceutical Co., Ltd. product] and the like.

  With regard to the amount of the isocyanate compound used, in view of the curability of the resulting coating composition, the coating price, etc., the isocyanate group has a content of 0.2 with respect to 1 equivalent of the hydroxyl group of the vinyl copolymer according to the present invention. The range in which the equivalent ratio [OH group] / [NCO group] is 1 / 0.2 to 1 / 1.5 is preferable.

  The polymer (A) used in the present invention is preferably used after being dissolved in an organic solvent. Examples of these organic solvents include toluene, xylene, “Solvesso 150” [product of Exxon Chemical Co., Ltd.] and the like. Aromatic hydrocarbon solvents such as: acetate solvents such as ethyl acetate and butyl acetate; ketone solvents such as methyl ethyl ketone and methyl isobutyl ketone; aliphatic hydrocarbons such as n-hexane and n-heptane; Examples include glycol ether ester solvents.

  The non-volatile content used as the organic solvent solution is not particularly limited as long as it is smoothly applied to the polyester film, but is preferably 20 to 80% by weight, for example.

  Specific examples of the polyester film according to the present invention include polyethylene terephthalate, polyethylene isophthalate, polyethylene isophthalate, polybutylene terephthalate, poly (1,4-cyclohexylenedimethylene terephthalate), and polyethylene-2,6-naphthalate. These copolymers or blends thereof with a small proportion of other resins may also be used. Among these polyesters, polyethylene terephthalate and polyethylene-2,6-naphthalate are preferable because of a good balance between mechanical properties and optical properties.

  Hereinafter, the present invention will be described more specifically with reference to examples. Unless otherwise specified, “part” is “part by weight” and “%” is “% by weight”.

Example 1
A four-necked flask equipped with a thermometer, a stirrer, a reflux condenser and a nitrogen gas inlet tube was charged with 45 parts of butyl acetate and heated to 110 ° C. When the temperature reached 110 ° C., a mixture of monomers consisting of 32 parts of styrene, 11 parts of 2-hydroxyethyl methacrylate, 25 parts of dibutyl fumarate and 32 parts of methyl methacrylate, 0.5 part of perbutyl O, and perbutyl D95 A solution prepared by dissolving 0.3 part of the above in 14 parts of butyl acetate was dropped at the same time over 5 hours, and while stirring at 110 ° C., stirring and reaction were continued for 90 minutes. Next, 0.5 part of butyl acetate and 0.2 part of perbutyl O were added. Thereafter, non-volatile content of 65% or more, a viscosity (Gardner) of the reaction was continued until the above Z _8. After completion of the reaction, the reaction mixture was cooled to room temperature, and 41 parts of butyl acetate was added to obtain the desired polymer (A). The obtained polymer had a hydroxyl value of 47 mg KOH / g, a weight average molecular weight of 40000, and a calculated glass transition temperature of 65 ° C.
Next, a coating agent was prepared by blending the polymer (A) shown below, and a polyester film was applied by the following coating method, and an adhesion test was performed. The obtained results are shown in Table 1.

Example 2
A polymer was obtained in the same manner as in Example except that the monomers were changed to 42 parts of styrene, 23 parts of 2-hydroxyethyl methacrylate, and 35 parts of dibutyl fumarate. The obtained polymer had a hydroxyl value of 100 mgKOH / g, a weight average molecular weight of 40000, and a calculated glass transition temperature of 49 ° C. Next, a coating agent was prepared in the same manner as in Example 1, and applied to a polyester film by the following coating method to conduct an adhesion test. The obtained results are shown in Table 1.

Example 3
A polymer was obtained in the same manner as in Example except that the monomers were changed to 20 parts of styrene, 10 parts of 2-hydroxyethyl methacrylate, 10 parts of dibutyl fumarate, 59 parts of methyl methacrylate, and 1 part of methacrylic acid. . The obtained polymer had a hydroxyl value of 43 mg KOH / g, a weight average molecular weight of 20000, and a calculated glass transition temperature of 84 ° C. Next, a coating agent was prepared in the same manner as in Example 1, and applied to a polyester film by the following coating method to conduct an adhesion test. The obtained results are shown in Table 1.

Comparative Example 1
A polymer was obtained in the same manner as in the Examples except that the monomers were replaced with 25 parts of styrene, 5 parts of 2-hydroxyethyl methacrylate, 57 parts of methyl methacrylate, 12 parts of n-butyl acrylate, and 1 part of methacrylic acid. It was. The obtained polymer had a hydroxyl value of 22 mgKOH / g, a weight average molecular weight of 30000, and a calculated glass transition temperature of 69 ° C. Next, a coating agent was prepared in the same manner as in Example 1, and applied to a polyester film by the following coating method to conduct an adhesion test. The obtained results are shown in Table 1.

Comparative Example 2
A polymer was obtained in the same manner as in Example 1 except that the monomers were changed to 11 parts of 2-hydroxyethyl methacrylate, 33 parts of methyl methacrylate, 1 part of methacrylic acid, and 55 parts of ethyl acrylate. The obtained polymer had a hydroxyl value of 47 mg KOH / g, a weight average molecular weight of 65,000, and a calculated glass transition temperature of 17 ° C. Next, a coating agent was prepared in the same manner as in Example 1, and applied to a polyester film by the following coating method to conduct an adhesion test. The obtained results are shown in Table 1.

Comparative Example 3
A polymer was prepared in the same manner as in Example 1 except that the monomers were replaced with 8 parts of 2-hydroxyethyl methacrylate, 65 parts of methyl methacrylate, 15 parts of dibutyl fumarate, 10 parts of dibutyl maleate and 2 parts of methacrylic acid. Got. The obtained polymer had a hydroxyl value of 35 mg KOH / g, a weight average molecular weight of 10,000, and a calculated glass transition temperature of 70 ° C. Next, a coating agent was prepared in the same manner as in Example 1, and applied to a polyester film by the following coating method to conduct an adhesion test. The obtained results are shown in Table 1.

[Measurement of weight average molecular weight]
In addition, the measurement of the weight average molecular weight (polystyrene conversion) by GPC in this invention was performed on condition of the following using the HLC8220 system by Tosoh Corporation.
Separation column: 4 TSKgelGMH _HR- N manufactured by Tosoh Corporation are used. Column temperature: 40 ° C. Moving layer: Tetrahydrofuran manufactured by Wako Pure Chemical Industries, Ltd. Flow rate: 1.0 ml / min. Sample concentration: 1.0% by weight. Sample injection volume: 100 microliters. Detector: differential refractometer.

[Calculation method of glass transition temperature]
The glass transition temperature was determined by the following formula.
Tg ⁻¹ = ΣXi · Tgi ⁻¹ (K)
Here, it is assumed that n monomer components from i = 1 to n are copolymerized in the polymer. Xi is the weight fraction of the i-th monomer, and Tgi is the glass transition temperature of the homopolymer of the i-th monomer. The glass transition temperature of the homopolymer of the monomer is described in Polymer Handbook (4th Edition) J. MoI. Brandrup, E .; H. Immergut, E .; A. Values described by Gulke (Wiley Interscience) were used. For those not listed above, values assumed as appropriate were used.

[Coating agent formulation example]
10g vinyl copolymer
Thinner (butyl acetate) 23.3g
Curing agent * 1 1.2g
* 1; Burnock DN-980; Polyisocyanate manufactured by DIC Corporation (mixed at [(OH) / (NCO)] = 1.0 (in terms of solid content))

[Coating method]
The substrate [untreated polyethylene terephthalate (PET) film] was coated with a bar coater to a dry film thickness of 2 to 5 μm, dried by heating at 80 ° C. for 30 minutes in a dryer, and then at room temperature for 1 day. The adhesion test was performed after drying.

[Test method]
(Primary adhesion test)
10 × 10 cuts were made on a 1 mm square with a cutter on the surface of the coating, a peel test with a cellophane tape was performed, and the number of remaining eyes was evaluated according to the following evaluation criteria.
Evaluation criteria A: 100
○: 85-99
Δ: 65-84
X: 35-64
XX: 34 or less

Claims (5)

For polyester film coating containing a polymer (A) obtained by radical polymerization of vinyl monomers having aromatic group-containing vinyl monomers and α, β-unsaturated dicarboxylic acid derivatives as essential components Resin composition Claims containing 10 to 50 parts of an aromatic group-containing vinyl monomer and 5 to 50 parts of an α, β-unsaturated dicarboxylic acid derivative with respect to a total of 100 parts by weight of the vinyl monomers. Item 1. The polyester film coating resin composition according to Item 1. Furthermore, the resin composition for polyester film coating of Claim 1 or 2 containing the hydroxyalkyl (meth) acrylate as a vinyl-type monomer. A resin composition for polyester film coating, wherein the polymer (A) according to claim 1, 2 or 3 has a weight average molecular weight of 3000 to 100,000 and a glass transition temperature of 0C to 90C. Furthermore, the resin composition for polyester film coating of Claim 3 which mix | blended the isocyanate hardening | curing agent.