JP2011021164A - Primer composition for plastic - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a primer composition for plastics having excellent designability, and being excellent in water resistance and improved in the tight adhesiveness to plastic substrate materials. <P>SOLUTION: The primer composition for plastics comprises a (meth)acrylate copolymer (A) and a film-forming auxiliary, wherein the (meth)acrylate copolymer (A) contains no hydroxy groups and has 50-75°C glass transition temperature and 10,000-60,000 weight average molecular weight, and the film forming auxiliary is a cellulose ester resin (B) or a photocurable resin (C), and a photopolymerization initiator (D). <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a primer for plastics.

Plastic molded products made by molding plastics such as acrylic resin, polycarbonate resin, polystyrene resin, and ABS resin are light and have excellent impact resistance and molding processability, and are used in various fields. .
In general, plastic molded products are covered with a coating film for the purpose of protecting the surface from damage.
As coating with such a coating film, for example, an undercoat agent called an undercoat or base coat is applied on a plastic substrate to form an undercoat layer, and tin, aluminum, nickel, copper are formed thereon. In order to impart wear resistance and scratch resistance, a metal such as a metal is vacuum deposited to form a vapor deposition layer, and a middle coat agent called middle coat is further coated thereon to form a middle coat layer. It is known that a top coat layer called a top coat or a hard coat is coated thereon to form a top coat layer.

  Specifically, the present applicant has disclosed, in Patent Document 1, as a curable resin composition that can be used as a primer composition, an undercoat agent composition, a topcoat agent composition, a middle coat agent composition, or the like. ) Copolymer (A) obtained by polymerizing a monomer component containing an acrylic acid alkyl ester (a1) and a compound (a2) each having at least one unsaturated double bond, hydroxy group and aromatic ring And a curable resin (B) ”([Claim 1] [0091]).

JP 2008-56813 A

As a result of studying the curable resin composition described in Patent Document 1, the present inventor has excellent designability (surface smoothness) when this curable resin composition is used as an undercoat agent. It is inferior in water resistance, and it is clear that the adhesion between the plastic substrate and the undercoat layer may be inferior depending on the weight average molecular weight of the acrylic copolymer, the glass transition point, and the type of the plastic substrate. became.
Accordingly, an object of the present invention is to provide a primer composition for plastics that retains excellent design properties, is excellent in water resistance, and improves adhesion to a plastic substrate.

As a result of intensive studies, the inventor has found that a curable resin composition containing a (meth) acrylate copolymer having a specific weight average molecular weight and a glass transition point, and a film forming aid such as a cellulose ester resin. However, the present inventors have found that it is excellent in water resistance and can improve the adhesion to a plastic substrate without adversely affecting the design properties, thereby completing the present invention.
That is, the present invention provides the following (1) to (8).

(1) A plastic primer composition containing a (meth) acrylate copolymer (A) and a film-forming aid,
The (meth) acrylate copolymer (A) does not have a hydroxyl group, has a glass transition point of 50 to 75 ° C., and a weight average molecular weight of 10,000 to 60000,
The primer composition for plastics whose said film-forming auxiliary | assistance is a cellulose-ester resin (B) or a photocurable resin (C), and a photoinitiator (D).

  (2) The primer composition for plastic according to (1), wherein the cellulose ester resin (B) is cellulose acetate butyrate or cellulose acetate propyrate.

  (3) The said (1) or (2) whose mass ratio (A / B) of the said (meth) acrylate type copolymer (A) and the said cellulose-ester resin (B) is 70 / 30-90 / 10. ) Primer composition for plastics.

  (4) The primer composition for plastics according to (1), wherein the photocurable resin (C) is a polyester acrylate having two or more (meth) acryloyloxy groups in one molecule.

  (5) The primer composition for plastics according to (1) or (4), wherein the photopolymerization initiator (D) is an alkylphenone compound.

  (6) Said (1), (4) whose mass ratio (A / C) of said (meth) acrylate type copolymer (A) and said photocurable resin (C) is 80 / 20-50 / 50. ) And the primer composition for plastics in any one of (5).

  (7) The (meth) acrylate copolymer (A) comprises a compound (a1) having a phenyl group and a vinyl group in one molecule, methyl (meth) acrylate (a2), alkyl (meth) acrylate ( The primer composition for plastics in any one of said (1)-(6) which is a copolymer obtained by polymerizing the monomer component containing a3).

  (8) The primer composition for plastics according to (7), wherein the alkyl (meth) acrylate (a3) is an alkyl (meth) acrylate having an alkyl group having 2 to 10 carbon atoms.

  As will be described below, according to the present invention, it is possible to provide a primer composition for plastics that maintains good design properties, is excellent in water resistance, and improves adhesion to a plastic substrate.

Hereinafter, the present invention will be described in more detail.
The primer composition for plastics of the present invention (hereinafter referred to as “the composition of the present invention”) is a primer composition for plastics containing a (meth) acrylate copolymer (A) and a film-forming aid. The (meth) acrylate copolymer (A) does not have a hydroxyl group, has a glass transition point of 50 to 75 ° C., a weight average molecular weight of 10,000 to 60,000, and the film forming aid is , Cellulose ester resin (B), or a primer composition for plastics which is a photocurable resin (C) and a photopolymerization initiator (D).
Next, each component of the composition of the present invention will be described in detail.

<(Meth) acrylate copolymer (A)>
The (meth) acrylate copolymer (A) (hereinafter also referred to as “copolymer (A)”) used in the composition of the present invention contains a (meth) acrylate compound as a monomer component. And it will not specifically limit if it is a copolymer which does not have a hydroxyl group, a glass transition point is 50-75 degreeC, and a weight average molecular weight is 10,000-60000.
Here, in this specification, the expression “(meth) acrylate” indicates acrylate or methacrylate.
Moreover, a weight average molecular weight is a weight average molecular weight (polystyrene conversion) measured by the gel permeation chromatography (Gel permeation chromatography (GPC)), and it is preferable to use tetrahydrofuran (THF) as a solvent for a measurement.
Similarly, the glass transition point is a value measured using a differential thermal analyzer (DSC) according to ASTM D3418-82 at a heating rate of 10 ° C./min.

In this invention, the glass transition point of the said copolymer (A) is 50-75 degreeC, It is preferable that it is 55-65 degreeC, and it is more preferable that it is 57-63 degreeC.
Moreover, the weight average molecular weights of the said copolymer (A) are 10000-60000, it is preferable that it is 20000-40000, and it is more preferable that it is 25000-35000.
When the glass transition point and the weight average molecular weight of the copolymer (A) are within this range, the design of the present invention containing the copolymer (A) is not adversely affected by coating. In addition, the adhesion to the plastic substrate can be improved.
This is because the glass transition point is in the above range, toughness and flexibility are imparted to the coating film formed by coating the composition of the present invention, and the weight average molecular weight is in the above range. This is thought to be because high film-forming properties are imparted to the coating film.

Moreover, in this invention, the said copolymer (A) does not have a hydroxyl group, The water resistance of the coating film formed by coating the composition of this invention becomes favorable.
This is considered because the hydrophobicity is imparted to the coating film because the copolymer (A) does not have a hydroxyl group which is a hydrophilic group.

  On the other hand, the (meth) acrylate compound that is a monomer component of the copolymer (A) is other than a compound (for example, 2-hydroxy-3-phenoxypropyl acrylate) that introduces a hydroxyl group into the obtained copolymer. If it is, it will not specifically limit, (meth) acrylic acid, the alkylester of (meth) acrylic acid, etc. can be mentioned as the specific example.

In the present invention, the above copolymer (A) has good viscosity and workability of the composition of the present invention, and more adhesiveness to the plastic substrate is obtained by coating the composition of the present invention. The compound (a1) (hereinafter referred to as “compound (a1)”) having a phenyl group and a vinyl group in one molecule, and methyl, for the reason of improving and further imparting toughness to the coating film. (Meth) acrylate (a2) (hereinafter referred to as “compound (a2)”) and alkyl (meth) acrylate (a3) (hereinafter referred to as “compound (a3)”) are combined with the above (meth) acrylate type. A copolymer used as a compound is preferred.
Here, the mass ratio of the compound (a1), the compound (a2), and the compound (a3) in the copolymer (A) is not particularly limited, but compound (a1): compound (a2): compound (A3) is preferably 45: 50: 5 to 40:30:30.

  Specific examples of the compound (a1) include styrene (ethenylbenzene) and vinyltoluene (1-methyl-4-ethenylbenzene).

The alkyl group of the compound (a3) is not particularly limited and may be linear, branched or cyclic, but is preferably an alkyl group having 2 to 10 carbon atoms.
Specific examples of the compound (a3) include, for example, ethyl (meth) acrylate (ethyl (meth) acrylate), propyl (meth) acrylate (protyl (meth) acrylate), butyl (meth) acrylate (( (Meth) butyl acrylate), butyl (meth) acrylate (butyl (meth) acrylate), isobutyl (meth) acrylate (isobutyl (meth) acrylate), cyclohexyl (meth) acrylate (cyclohexyl (meth) acrylate), etc. Can be mentioned.

<Cellulose ester resin (B)>
The cellulose ester resin (B) used in the composition of the present invention is not particularly limited as long as the hydroxyl group of cellulose is esterified with an acid, and a conventionally known coating material can be used.
Specific examples of the cellulose ester resin (B) include cellulose / acetate, cellulose / acetate / butylate, and cellulose / acetate / propylate. These may be used alone or in combination of two types. You may use the above together.

In the present invention, by using the cellulose ester resin (B), the drying time after coating of the composition of the present invention can be shortened and the adhesion to the plastic substrate can be improved.
This is considered to be because the formation speed of the coating film formed by applying the composition of the present invention is improved, and the impact due to peeling is alleviated by imparting plasticity to the coating film. .

Moreover, in this invention, content of the said cellulose-ester resin (B) can shorten the drying time after the coating of the composition of this invention more, and can improve adhesiveness with a plastic base material more. From the reason which can be done, it is preferable that it is 11-42 mass parts with respect to 100 mass parts of said copolymers (A), It is more preferable that it is 15-40 mass parts, It is further that it is 20-30 mass parts preferable.
Similarly, the mass ratio (A / B) between the (meth) acrylate copolymer (A) and the cellulose ester resin (B) is preferably 70/30 to 90/10, and 75/25. More preferably, it is -85/15.

<Photocurable resin (C)>
The said photocurable resin (C) used for the composition of this invention is not specifically limited, A conventionally well-known photocurable resin can be used.
As said photocurable resin (C), a photocurable acrylic resin can be mentioned from a compatible viewpoint with the said copolymer (A), for example.

Examples of the photo-curable acrylic resin include one or more carboxy groups (—COOH) and one or two (meth) acryloyloxy groups (CH ₂ ═CR—COO—, R: H in one molecule. Or a compound having —CH ₃ ) (hereinafter referred to as “compound (c1)”), a compound having three or more (meth) acryloyloxy groups in one molecule (hereinafter referred to as “compound (c2)”). These may be used alone or in combination of two or more.

As for the said compound (c1), what has a carboxy group at the terminal is mentioned as one of the preferable aspects.
Here, the number of carboxy groups is preferably 1 to 3 because the compatibility with the copolymer (A) is excellent and the adhesion to the plastic substrate can be further improved.
In addition, the number of (meth) acryloyloxy groups in one molecule of the compound (c1) is preferably one because the adhesion to the plastic substrate can be further improved.

  Specific examples of the compound (c1) include a reaction product of hydroxy (meth) acrylate and a polybasic acid and / or an acid anhydride thereof, ω-carboxypolycaprolactone mono (meth) acrylate, (meth) ) Acrylic acid dimer.

Here, the reaction of hydroxy (meth) acrylate with a polybasic acid and / or an acid anhydride thereof is not particularly limited, and examples thereof include conventionally known methods.
Moreover, as hydroxy (meth) acrylate used in the case of reaction with hydroxy (meth) acrylate, a polybasic acid, and / or its anhydride, specifically, for example, 2-hydroxyethyl (meth) acrylate 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, glycerin mono (meth) acrylate, pentaerythritol mono (meth) acrylate, and mixtures thereof. Can be mentioned.
On the other hand, specific examples of polybasic acid and anhydride used in the reaction of hydroxy (meth) acrylate with polybasic acid and / or acid anhydride thereof include, for example, succinic acid, maleic acid, Phthalic acid, isophthalic acid, terephthalic acid, sebacic acid, adipic acid, azelaic acid, glutaric acid, suberic acid, malonic acid, tetrahydrophthalic acid, hexahydrophthalic acid, phthalic anhydride, tetrahydrophthalic anhydride, maleic anhydride, methyl Examples include hexahydrophthalic acid, methyltetrahydrophthalic acid, methylhexahydrophthalic anhydride, methyltetrahydrophthalic anhydride, and mixtures thereof.

  Specific examples of the compound (c1) obtained by reacting a polybasic acid and / or acid anhydride thereof with hydroxy (meth) acrylate include, for example, 2-hydroxypropyl (meth) acrylate and tetrahydrophthalic anhydride. Examples include 2- (meth) acryloyloxypropyl monotetrahydrophthalate synthesized.

  The ω-carboxypolycaprolactone mono (meth) acrylate as the compound (c1) can be obtained as a commercial product. An example of such a commercially available product is M-5400 manufactured by Toagosei Co., Ltd.

  Specific examples of the compound (c1) include compounds represented by the following formula (1) or (2).

  In the formula (1), m represents an integer of 0 to 10, and is preferably 0 or 1 because the adhesiveness with the plastic substrate can be further improved.

Among these compounds (c1), it is a compound represented by the above formula (1) or (2) because the raw materials are easily available and the adhesion with the plastic substrate can be further improved. Is preferable, and a compound represented by the above formula (1) is more preferable.
A mixture of a compound (acrylic acid) in which m in the above formula (1) is 0 and a compound in which m in the above formula (1) is 1 can be obtained as a commercial product. An example of such a commercial product is M-5600 manufactured by Toagosei Co., Ltd.
Moreover, the compound represented by the said Formula (2) can be obtained as a commercial item. Examples of such commercially available products include M-5400 manufactured by Toagosei Co., Ltd. and HOA-MPL manufactured by Kyoeisha Chemical Co., Ltd.

In the present invention, the compound (c1) may be used alone or in combination of two or more.
A combination of two or more kinds of compounds (c1) is a compound in which m in the above formula (1) is 0 because the raw materials can be easily obtained and the adhesion to the plastic substrate can be further improved. A combination of (acrylic acid) and a compound in which m in the above formula (1) is 1 is preferred.

  On the other hand, the compound (c2) is not particularly limited as long as it has three or more (meth) acryloyloxy groups in one molecule.

  Specific examples of the compound (c2-1) having three (meth) acryloyloxy groups in one molecule include, for example, trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, dipenta Examples include erythritol tri (meth) acrylate.

  Specific examples of the compound (c2-2) having four (meth) acryloyloxy groups in one molecule include pentaerythritol tetra (meth) acrylate, dipentaerythritol tetra (meth) acrylate, Examples include tripentaerythritol tetra (meth) acrylate.

  Furthermore, as the compound (c2-3) having 5 or more (meth) acryloyloxy groups in one molecule, specifically, for example, a compound represented by the following formula (5), dipentaerythritol penta ( (Meth) acrylate, dipentaerythritol hexa (meth) acrylate, tripentaerythritol penta (meth) acrylate, tripentaerythritol hexa (meth) acrylate, tripentaerythritol hepta (meth) acrylate, tripentaerythritol octa (meth) acrylate, etc. Can be mentioned.

  Among these, trimethylolpropane triacrylate represented by the following formula (3), represented by the following formula (4), from the viewpoint of fast curability, coating film hardness, water resistance, solvent resistance, chemical resistance, and the like. The pentaerythritol tetraacrylate, the compound represented by the following formula (5), and dipentaerythritol tetra (meth) acrylate are preferable.

Examples of commercially available products of trimethylolpropane triacrylate represented by the above formula (3) include M-309 (manufactured by Toagosei Co., Ltd.), light acrylate TMP-A (manufactured by Kyoeisha Chemical Co., Ltd.), Ebecryl TEMPT (Daicel Cytec Co., Ltd.). Product), NK ester A-TMPT (manufactured by Shin-Nakamura Chemical Co., Ltd.).
Examples of the pentaerythritol tetraacrylate represented by the above formula (4) include, for example, M-450 (manufactured by Toagosei Co., Ltd.), light acrylate PE-4A (manufactured by Kyoeisha Chemical Co., Ltd.), Ebecryl PETAK (manufactured by Daicel Cytec Co., Ltd.), NK An ester ATMMT (manufactured by Shin-Nakamura Chemical Co., Ltd.) can be mentioned.
Examples of commercially available products containing dipentaerythritol hexaacrylate represented by the above formula (5) include M-402 (manufactured by Toagosei Co., Ltd.), light acrylate DPE-6A (manufactured by Kyoeisha Chemical Co., Ltd.), and Ebecryl DDHA (Daicel Cytec). And NK ester A-PPH (manufactured by Shin-Nakamura Chemical Co., Ltd.).
The said compound (c2) can be used individually or in combination of 2 types or more, respectively.

In the present invention, by using the photocurable resin (C), the drying time after coating of the composition of the present invention can be shortened and the adhesion to the plastic substrate can be improved.
This is considered to be because toughness is imparted to the coating film as the photocurable resin (C) is cured, and the impact due to peeling is alleviated.

Moreover, in this invention, content of the said photocurable resin (C) is 30-300 with respect to 100 mass parts of said copolymers (A) from a viewpoint of coexistence with adhesive improvement and workability | operativity. It is preferable that it is a mass part, It is more preferable that it is 30-200 mass parts, It is further more preferable that it is 40-100 mass parts.
Similarly, the mass ratio (A / C) between the (meth) acrylate copolymer (A) and the photocurable resin (C) is preferably 80/20 to 50/50, and 75 / More preferably, it is 25-55 / 45.

<Photopolymerization initiator (D)>
Examples of the photopolymerization initiator (D) used in the composition of the present invention together with the photocurable resin (C) include carbonyl compounds such as alkylphenone compounds, benzoin ether compounds, and benzophenone compounds, sulfur Examples thereof include compounds, azo compounds, peroxide compounds, and phosphine oxide compounds.
More specifically, for example, acetophenone, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, acetoin, butyroin, toluoin, benzyl, benzophenone, p-methoxybenzophenone, diethoxyacetophenone, α, α-dimethoxy-α -Phenylacetophenone, methylphenylglyoxylate, ethylphenylglyoxylate, 4,4'-bis (dimethylaminobenzophenone), 2-hydroxy-2-methyl-1-phenylpropan-1-one, the following formula (6) A carbonyl compound such as 1-hydroxycyclohexyl phenyl ketone; a sulfur compound such as tetramethylthiuram monosulfide and tetramethylthiuram disulfide; azobisisobutyronitrite Le, azo compounds such as azobis-2,4-dimethylvaleronitrile; benzoyl peroxide, ditertiary butyl peroxide, such as peroxide compounds: and the like.

Of these, 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl are preferred from the viewpoints of photostability, high efficiency of photocleavage, compatibility with the copolymer (A), low volatility, and low odor. -1-Phenyl-propan-1-one, 1- [4- (2-hydroxyethoxy) -phenyl] -2-hydroxy-2-methyl-1-propan-1-one are preferred.
Examples of commercially available 1-hydroxycyclohexyl phenyl ketone include Irgacure 184 (manufactured by Ciba Specialty Chemicals).

  The said photoinitiator (D) can be used individually or in combination of 2 types or more, respectively.

  In this invention, content of the said photoinitiator (D) is 1 with respect to 100 mass parts of said photocurable acrylic resins, when the said photocurable resin (C) is the said photocurable acrylic resin. It is preferable that it is -10 mass parts, and it is more preferable that it is 2-8 mass parts.

<Solvent, additive>
The composition of the present invention preferably further contains a solvent from the viewpoint of workability.
Specific examples of the solvent include ethanol, isopropanol, butanol, toluene, xylene, acetone, methyl ethyl ketone, ethyl acetate, butyl acetate, and cyclohexanone.

  In addition, the composition of the present invention is various additives such as a filler, an anti-aging agent, an antioxidant, an antistatic agent, a flame retardant, an adhesion-imparting agent, and a leveling as long as the object of the present invention is not impaired. Agents, dispersants, antifoaming agents, matting agents, light stabilizers (eg, hindered amine compounds), dyes, pigments and the like.

  Examples of the filler include wax stone clay, kaolin clay, calcined clay; fumed silica, calcined silica, precipitated silica, ground silica, fused silica; diatomaceous earth; iron oxide, zinc oxide, titanium oxide, barium oxide, oxidized Magnesium; calcium carbonate, magnesium carbonate, zinc carbonate; organic or inorganic fillers such as carbon black; these fatty acids, resin acids, fatty acid ester treated products, and fatty acid ester urethane compound treated products.

Examples of the antiaging agent include hindered phenol compounds and hindered amine compounds.
Examples of the antioxidant include butylhydroxytoluene (BHT) and butylhydroxyanisole (BHA).
Examples of the antistatic agent include quaternary ammonium salts; hydrophilic compounds such as polyglycols and ethylene oxide derivatives.

Examples of the flame retardant include chloroalkyl phosphate, dimethyl / methylphosphonate, bromine / phosphorus compound, ammonium polyphosphate, neopentyl bromide-polyether, and brominated polyether.
Examples of the adhesion imparting agent include terpene resins, phenol resins, terpene-phenol resins, rosin resins, xylene resins, and epoxy resins.

  Examples of the leveling agent include silicone leveling agents, acrylic leveling agents, vinyl leveling agents, and fluorine leveling agents.

  The production method of the composition of the present invention is not particularly limited. For example, the above-described essential components and optional components are put in a reaction vessel and sufficiently kneaded using a stirrer such as a mixing mixer under reduced pressure. Can be manufactured.

Next, a laminate using the composition of the present invention (hereinafter referred to as “laminate of the present invention”) will be described in detail.
The laminate according to the first aspect of the present invention includes a plastic substrate, a primer layer coated with the composition of the present invention and cured, an undercoat layer, a metal vacuum deposition layer, and a middle coat layer. , A laminate having a top coat layer in this order.
Moreover, the laminated body which concerns on the 2nd aspect of this invention is a laminated body which has a plastic base material, the primer layer which apply | coated and hardened the composition of this invention, and a topcoat layer in this order.

As the plastic substrate, various plastic substrates can be used regardless of thermoplastic plastics and thermosetting plastics.
Specific examples include polymethyl methacrylate resin, polycarbonate resin, polystyrene resin, acrylonitrile / styrene copolymer resin, polyvinyl chloride resin, acetate resin, ABS resin, polyester resin, polyamide resin, and the like.

The method for applying the composition of the present invention is not particularly limited, and for example, known application methods such as brush coating, flow coating, dip coating, spray coating, and spin coating can be employed.
Moreover, the curing method of the composition of the present invention can be performed by heating or ultraviolet rays according to the film-forming aid described above.

  The coating amount of the composition of the present invention is not particularly limited, but the thickness of the formed primer layer is preferably in the range of 1 to 30 μm, more preferably in the range of 2 to 25 μm, More preferably, it is in the range of 15 μm.

  Further, the formation method and materials of the undercoat layer, metal vacuum deposition layer, middle coat layer, and topcoat layer are not particularly limited, and conventionally known methods and materials can be employed.

  The laminate of the present invention can be used, for example, as an outer frame of various electric / electronic devices and communication devices (for example, mobile phones), and as an electromagnetic wave shield.

  Hereinafter, the present invention will be specifically described with reference to examples. However, the present invention is not limited to these.

<Synthesis of copolymer (A)>
Each monomer component shown in Table 1 below is mixed at a mass ratio shown in Table 1, and polymerized in methyl ethyl ketone in the presence of a polymerization initiator (AIBN (azobisisobutyronitrile)). Copolymers A1 to A9 (40% methyl ethyl ketone solution) shown in the table were obtained.
The copolymers A6 to A9 do not correspond to the (meth) acrylate copolymer (A) used in the composition of the present invention.

<Examples 1-8, Comparative Examples 1-4>
Each component shown in the following Table 2 was mixed using a stirrer with the composition (parts by mass) shown in Table 2 to obtain each primer composition. In Table 2 below, the composition ratio represents the mass ratio between each copolymer and each cellulose ester resin.
The design property, adhesiveness, and water resistance of each obtained primer composition were evaluated by the following methods. The results are shown in Table 2.

(Creativity)
Each obtained primer composition was apply | coated with the spray with respect to the polycarbonate-made board | substrate of the state which inclined the application surface at 45 degree | times, and the sample (film thickness: 4 micrometers) was obtained.
After spray coating, the coated surface of the obtained sample was leveled and dried at 70 ° C. for 5 minutes, and then the sample was observed with the naked eye at an angle of 45 ° with respect to the coated surface of the sample.
The evaluation criteria for the design properties were “◯” when the coating film was excellent in gloss and having little unevenness, and “X” when there were abnormal appearance such as conspicuous unevenness.

(Adhesion)
The adhesion was evaluated by a cross-cut tape peeling test.
Specifically, first, a UV curable urethane acrylate-based paint is applied on the application surface of the sample used in the evaluation of the design properties, and after application, dried with hot air at 60 ° C. for 3 minutes. GS UV SYSTEM manufactured by Battery Co., Ltd. is irradiated with UV so that the integrated light quantity becomes 900 mJ / cm ² , UV cured, and further dried at 60 ° C. for the time shown in Table 2 below (5 minutes, 15 minutes, 60 minutes). Thus, an undercoat layer was formed.
Next, a test piece for a cross-cut tape peeling test was produced on the undercoat layer.
100 pieces of 1 mm substrate (10 × 10) are made on the obtained specimen, cellophane adhesive tape (width 18 mm) is completely adhered on the substrate, and one end of the tape is immediately perpendicular to the polycarbonate substrate. The number of base eyes remaining without being completely peeled off was examined.
Those in which 95 or more remained out of 100 were regarded as acceptable.

(water resistant)
First, an undercoat layer was formed on the coated surface of the sample used in the design evaluation by the same method as the adhesion evaluation.
Subsequently, it was immersed in warm water of 70 ° C. for 2 hours, and then a cross-cut tape peeling test was performed in the same manner as in the evaluation of adhesion to evaluate water resistance.

<Examples 9 to 15 and Comparative Examples 5 to 8>
The components shown in Table 3 below were mixed using the stirrer with the composition (parts by mass) shown in Table 3 to obtain each primer composition. In Table 3 below, the composition ratio represents the mass ratio of each copolymer to the photocurable resin.
The design properties and adhesion of each of the obtained primer compositions were evaluated by the same method as in Example 1. The results are shown in Table 3.

The components shown in Table 2 and Table 3 are as follows.
Copolymers (A1) to (A8): those shown in Table 1 Cellulose ester resin (B1): cellulose acetate butyrate (CAB-38-01-01, manufactured by Eastman Chemical Products)
Cellulose ester resin (B2): Cellulose acetate acetate (CAP-504-0.2, manufactured by Eastman Chemical Products)
-Photocurable resin (C1): Trimethylolpropane triacrylate (M-309, manufactured by Toagosei Co., Ltd.)
Photopolymerization initiator (D): 1-hydroxycyclohexyl phenyl ketone (Irgacure 184 (manufactured by Ciba Specialty Chemicals)

As is apparent from the results shown in Table 2 and Table 3, the copolymers (A6) to (A8) not corresponding to the (meth) acrylate copolymer (A) used in the composition of the present invention are used. It was found that the primer compositions of Comparative Examples 1 to 3 and Comparative Examples 5 to 7 prepared using both were inferior in adhesion to a plastic substrate and water resistance, and in particular, the primer compositions of Comparative Examples 1 and 5 As for, it was found that the design properties are also adversely affected.
Moreover, it turned out that the primer composition of the comparative example 4 prepared without using the film-forming aid used by the composition of this invention is inferior to adhesiveness with a plastic base material, and water resistance.
Furthermore, the primer composition of Comparative Example 8 prepared using a copolymer (A9) that does not correspond to the (meth) acrylate copolymer (A) used in the composition of the present invention has an adhesive property with a plastic substrate. Although it was excellent, it was found that the water resistance was poor.

  On the other hand, the primer compositions of Examples 1 to 15 prepared using the copolymers (A1) to (A5) corresponding to the (meth) acrylate copolymer (A) used in the composition of the present invention are It was also found that the excellent design properties were maintained, the adhesion with a polycarbonate plastic substrate which is a difficult-to-adhere substrate was improved, and the water resistance was also improved.

Claims (6)

A primer composition for plastics containing a (meth) acrylate copolymer (A) and a film-forming aid,
The (meth) acrylate-based copolymer (A) does not have a hydroxyl group, has a glass transition point of 50 to 75 ° C., and has a weight average molecular weight of 10,000 to 60000,
A primer composition for plastics, wherein the film-forming aid is a cellulose ester resin (B), or a photocurable resin (C) and a photopolymerization initiator (D).   The primer composition for plastics according to claim 1, wherein the cellulose ester resin (B) is cellulose acetate butyrate or cellulose acetate propylate.   The plastic primer according to claim 1 or 2, wherein a mass ratio (A / B) of the (meth) acrylate copolymer (A) and the cellulose ester resin (B) is 70/30 to 90/10. Composition.   The primer composition for plastics according to claim 1, wherein the photocurable resin (C) is a polyester acrylate having two or more (meth) acryloyloxy groups in one molecule.   The primer composition for plastics according to claim 1 or 4, wherein the photopolymerization initiator (D) is an alkylphenone compound.   The mass ratio (A / C) of the (meth) acrylate copolymer (A) and the photocurable resin (C) is 80/20 to 50/50. The primer composition for plastics described in 1.