JP4307458B2 - Hard coat agent for insert molding and hard coat film for insert molding - Google Patents

Description

  The present invention relates to a resin composition, a hard coat agent, and a hard coat film.

A hard coat film used for insert molding in which a back surface of a PET (polyethylene terephthalate) film coated with a hard coat resin is printed is attached to a mold, and the whole film is painted at the same time as molding.
JP-A-6-240108 JP 11-34248 A

  However, a high molecular weight urethane-modified acrylate having excellent flexibility as a resin was mainly used, but the surface physical properties were not satisfied. On the other hand, development using a hard coat resin or the like has been performed in order to satisfy the surface hardness. However, since it is too hard, there has been a problem that cracks are generated in the curved surface portion during molding. Therefore, a film having both surface hardness (pencil hardness, scratch resistance) and flexibility (bendability) is desired.

The present invention has been studied in view of such a situation, and is synthesized in one step from an aminotriazine compound, paraformaldehyde, and a hydroxyl group-containing (meth) acrylate, into a triazine ring-containing (meth) acrylate prepolymer having an average molecular weight of 200 to 20000. The above-mentioned problem can be solved by using a hard coat agent made of a resin composition obtained by reacting the remaining unreacted hydroxyl group with an isocyanate compound.

The present invention has been studied in view of such a situation, and is synthesized in one step from an aminotriazine compound, paraformaldehyde, and a hydroxyl group-containing (meth) acrylate, into a triazine ring-containing (meth) acrylate prepolymer having an average molecular weight of 200 to 20000. Use a hard coating agent for insert molding comprising a resin composition obtained by reacting a remaining unreacted hydroxyl group with a compound containing two or more isocyanate groups, and comprising an organic solvent and a radical polymerization initiator. Thus, the above problem can be solved.

  The triazine ring-containing (meth) acrylate prepolymer according to the present invention is a prepolymer having an average molecular weight of 200 to 20000 synthesized by a condensation reaction from an aminotriazine compound, paraformaldehyde, and a hydroxyl group-containing (meth) acrylate. When the average molecular weight is less than the lower limit, sufficient performance for hard coat cannot be obtained, and when it exceeds 20000, the viscosity becomes too high and the use becomes difficult.

An aminotriazine compound is a compound having a structure in which an amino group is bonded to three carbon atoms of a triazine ring composed of C ₃ N ₃ , and the aminotriazine compound refers to aminotriazine itself or an aminotriazine derivative.

  Examples of aminotriazines include melamine, and examples of aminotriazine derivatives include benzoguanamine, acetoguanamine, cyclohexanecarboguanamine, cyclohexenecarboguanamine, norbornanecarboguanamine, and nobornenecarboguanamine.

  As the hydroxyl group-containing (meth) acrylate, a hydroxyl group-containing (meth) acrylate, for example, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, and optionally, an ethylenically unsaturated group having at least one hydroxysil group. Compounds having a bond, such as 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl acrylate, polyethylene glycol mono (meth) acrylate, polypropylene glycol mono (meth) acrylate, trimethylolpropane mono (meth) acrylate, trimethylolpropane di (Meth) acrylate, allyl alcohol, ethylene glycol allyl ether, glycerin (mono, di) allyl ether, N-methylol (meth) acrylamide etc. or this Mixture can be added. Among these, 2-hydroxyethyl (meth) acrylate is preferable from the viewpoint of cost and ease of handling.

  The prepolymer is synthesized by the following method. Synthetic reactions include the formation of methylol groups by addition of formaldehyde to aminotriazine compounds and the condensation reaction of methylol groups with hydroxyl groups of hydroxyl group-containing (meth) acrylates, or aminotriazine compounds and hydroxyl group-containing (meth) acrylates, formaldehyde It is understood that the reaction proceeds with a condensation reaction by reaction with hemiacetal. The degree of progress of the condensation reaction can be determined by the amount of water released by these condensation reactions. The condensation reaction can be controlled by grasping the amount of water over time and stopping the water distillation at a predetermined stage.

The hard molding agent for insert molding of the present invention contains a resin composition obtained by reacting an isocyanate compound with an unreacted hydroxyl group remaining in a triazine ring-containing (meth) acrylate prepolymer .

  The isocyanate compound used in the present invention is a compound containing two or more isocyanate groups such as 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 1,3-xylylene diisocyanate, 1, 4-xylylene diisocyanate, 1,5-naphthalene diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate, 3,3′-dimethyl-4,4′-diphenylmethane diisocyanate, 4,4′-diphenylmethane diisocyanate, 4,4 ′ -Diphenylmethane triisocyanate, 3,3'-dimethylphenylene diisocyanate, 4,4'-biphenylene diisocyanate, 1,6-hexane diisocyanate, isophorone diisocyanate, methylene bis (4-cyclohexyl isocyanate) Nate), 2,2,4-trimethylhexamethylene diisocyanate, bis (2-isocyanatoethyl) fumarate, 6-isopropyl-1,3-phenyl diisocyanate, 4-diphenylpropane diisocyanate, tolidine diisocyanate, hydrogenated diphenylmethane diisocyanate, hydrogenated Xylylene diisocyanate, tetramethylxylylene diisocyanate, 2,5 (or 6) -bis (isocyanate methyl) -bicyclo [2.2.1] heptane, trimethylolpropane adduct of triethylene diisocyanate, isocyanurate of triethylene diisocyanate , Diphenylmethane-4,4′-diisocyanate oligomer, hexamethylene diisocyanate biuret, hexamethylene diisocyanate Isocyanurate body, uretdione of hexamethylene diisocyanate, isocyanurate of isophorone diisocyanate. Moreover, these polyisocyanates can be used individually or in combination of 2 or more types.

  In order to promote the reaction with the isocyanate group of the isocyanate component, an organotin-based urethanization catalyst is used, but as the organotin-based urethanization catalyst, any catalyst that is generally used in a urethanization reaction may be used. For example, dibutyltin dilaurate, dibutyltin diacetate, dibutyltin dialkylmalate, tin stearate, tin octylate and the like can be mentioned.

  The amount of the organotin-based urethanization catalyst used is not particularly limited, but is suitably used within the range of 0.005 to 3% by weight. If the lower limit is not reached, the urethane reaction does not proceed sufficiently. If the upper limit is exceeded, the reaction control becomes difficult due to heat generation during the urethane reaction.

The hard molding agent for insert molding of the present invention is cured by a known method such as a gravure coating method, a bar coating method, a knife coating method, a roll coating method, a blade coating method, or a die coating method with or without adding a curing agent. It is applied to the film so that the thickness of the subsequent coating film is 1 to 10 μm. If it is less than 1 μm, scratch resistance and pencil hardness tend to be poor, and if it exceeds 10 μm, bendability tends to be poor.

  As the film, in addition to a vinyl chloride film, an acrylic film, and a polycarbonate film, a polypropylene film, a low stretch polyester film, a polybutylene terephthalate film, a polystyrene film, an acrylonitrile butadiene styrene film, a nylon film, and the like can be used.

  As the curing agent, known radical polymerization initiators such as organic peroxides and azo compounds are used. Examples of the organic peroxide include ketone peroxides such as methyl ethyl ketone peroxide and acetylacetone peroxide, hydroperoxides such as cumene hydroperoxide, t-butyl hydroperoxide, diisopropylpyroxide, acetyl peroxide, Diacyl peroxides such as isobutyl peroxide, lauroyl peroxide, benzoyl peroxide, dialkyl peroxides such as dicumyl peroxide, t-butylcumyl peroxide, di-t-butyl peroxide, 1, 1, 3, Alkyl pares such as 3-tetramethylbutylperoxy-2-ethylhexanoate, t-butylperoxy-2-ethylhexanoate, t-butylperoxybenzoate Peroxydicarbonates such as diisopropyl peroxydicarbonate, di-2-ethylhexyl peroxydicarbonate, bis (4-t-butylcyclohexyl) peroxydicarbonate, t-butyl peroxyacetate, t- Organic peroxides such as peroxyesters such as butylperoxyisobutyrate, 2,2-azobis (2,4-dimethylvaleronitrile), 2,2-azobisisobutyronitrile, 1,1- Examples include azo compounds such as azobis (cyclohexane-1-carbonitrile), and these can be used alone or in combination of two or more. An organic peroxide having a low decomposition temperature is preferred from the viewpoint of curability, and specifically, methyl ethyl ketone peroxide and lauroyl peroxide are preferably used.

  The photoinitiator for radical polymerization is not particularly limited and known types can be used. For example, benzoin monomethyl ether, benzoin isopropyl ether, benzophenone, benzyl dimethyl ketal, 2,2-jet xylacetophenone, 1- Examples thereof include hydroxycyclohexyl phenyl ketone, and examples of the photosensitizer include 2-chlorothioxanthone, 2,4-diethylthioxanthone, and 2,4-diisopropylthioxanthone.

  The hard coat agent applied to the film is cured by irradiation with active energy rays such as ultraviolet rays and electron beams. In the case of curing by ultraviolet rays, it is necessary to include a photoinitiator, and in some cases, a photosensitizer and a photoaccelerator in the composition.

  Examples of the photoaccelerator include ethyl p-dimethylaminobenzoate, isoamyl p-dimethylaminobenzoate, 2-n-ptoxyethyl p-dimethylaminobenzoate, and 2-dimethylaminoethyl benzoate.

  Furthermore, examples of the initiator for photocationic polymerization include diallyliodonium salts and triarylsulfonium salts.

As the ultraviolet irradiation device, available device such as a known high-pressure mercury lamp or a metal halide lamp irradiation energy is 100 to 2000 mJ / cm ^2, further 300~700mJ / cm ² is more preferable.

Moreover, when hardening with an electron beam, a conventionally well-known hardening apparatus can be used, 10 kGy-200 kGy are preferable, and also 30 kGy-100 kGy are more preferable. If it is less than 10 kGy, complete curing cannot be achieved, and if it exceeds 200 kGy, the life of the electron beam irradiation tube is remarkably shortened, which is not economical.
Moreover, although an acceleration voltage is set with the coating-film thickness and density which are provided on a base material, 50 kv to 300 kv, Furthermore, 150 kv-250 kv are more preferable.

  EXAMPLES Hereinafter, although an Example and a comparative example are given and demonstrated in detail about this invention, a specific example is shown and it does not specifically limit to these.

(1) Triazine ring-containing (meth) acrylate prepolymer (A)
In a 2 liter separable flask equipped with a stirrer, thermometer, gas inlet tube, and reflux condenser, 2-hydroxyethyl acrylate, 696 g (6 mol), melamine 126 g (1 mol), 95 wt% paraformaldehyde 189 g ( 6 mol) as formaldehyde, 3.0 g of paratoluenesulfonic acid and 0.2 g of hydroquinone monomethyl ether were added, and the temperature was raised while blowing air. At 80 to 100 ° C., melamine and paraformaldehyde were dissolved in 2-hydroxyethyl acrylate, and then the reaction was continued while maintaining the internal temperature at 105 to 115 ° C. until the amount of distilled water reached 108 g (6 mol). The resulting triazine ring-containing acrylate prepolymer has a viscosity 2 Pa · s at 20 ° C., a bromine number 92.1 _(gBr 2 / 100g), and a molecular weight 3200.
(2) Urethane melamine acrylate prepolymer (a)
To 100 parts by weight of the triazine ring-containing (meth) acrylate prepolymer, 28.7 parts by weight of isophorone diisocyanate (IPDI) and 0.1 part by weight of di-n-butyltin dilaurate (DBTDL) as a catalyst were added and stirred at room temperature for 24 hours. Later, isopropanol was added. The reaction of the isocyanate group was confirmed by IR, and unreacted isopropanol was removed by an evaporator to obtain a urethanized melamine acrylate prepolymer (a).
(3) Hard coat agent Next, with respect to 100 parts by weight of the urethanized melamine acrylate prepolymer, 150 parts by weight of MEK and 5 parts by weight of 1-hydroxycyclohexyl phenyl ketone as an initiator were added to obtain a hard coat agent.
(4) Hard coat film Next, the hard coat agent was applied to a 100 μm PET (polyethylene terephthalate) film by a bar coat method so that the cured film thickness was 1.5 μm, and then heated at 100 ° C. for 2 minutes with a hot air dryer. It dried on the conditions of. After that, a hard coat film (1) was obtained by irradiating ultraviolet rays with an integrated light amount of about 200 mJ / cm ² using an ultraviolet irradiation device (Fusion lamp manufactured by Fusion UV Systems Japan Co., Ltd.).

  A hard coat film (2) was obtained in the same manner as in Example 1 except that the cured film thickness was 2.6 μm.

  A hard coat film (3) was obtained in the same manner as in Example 1 except that the cured film thickness was 4.7 μm.

  A hard coat film (4) was obtained in the same manner as in Example 1 except that the cured film thickness was 6.3 μm.

  A hard coat film (5) was obtained in the same manner as in Example 1 except that the cured film thickness was 8.9 μm.

Comparative Example 1
In Example 1, it was carried out in the same manner except that the cured film thickness was 0.9 μm, but the scratch resistance and pencil hardness were inferior.

Comparative Example 2
In Example 1, it was carried out in the same manner except that the cured film thickness was 10.8 μm, but the bendability was poor.

Comparative Example 3
(1) Hard coat agent dipentaerythritol hexaacrylate (Nippon Kayaku Co., Ltd., trade name Kayarad DPHA nonvolatile content 100%) 100 parts by weight MEK 150 parts by weight, 1-hydroxycyclohexyl phenyl ketone as an initiator 5 parts by weight was added to obtain a hard coat agent.
(2) Hard coat film Next, the hard coat agent was applied to a 100 μm PET (polyethylene terephthalate) film by a bar coat method so as to have a cured film thickness of 1.4 μm, and then heated at 100 ° C. for 2 minutes with a hot air dryer. It dried on the conditions of. Thereafter, ultraviolet rays were irradiated with an integrated light amount of about 200 mJ / cm ² using an ultraviolet irradiation device (Fusion lamp manufactured by Fusion UV Systems Japan Co., Ltd.), but the scratch resistance and pencil hardness were inferior.

Comparative Example 4
In Comparative Example 3, it was carried out in the same manner except that the cured film thickness was 2.4 μm, but the bendability was poor.

Comparative Example 5
In Comparative Example 3, instead of dipentaerythritol hexaacrylate (Nippon Kayaku Co., Ltd., trade name Kayarad DPHA non-volatile content 100%), pentaerythritol triacrylate (Nippon Kayaku Co., Ltd., trade name Kayrad PET-30 non-volatile) This was carried out in the same manner except that the cured film thickness was 2.3 μm, but the scratch resistance and pencil hardness were poor.

Comparative Example 6
In the comparative example 5, although it implemented similarly except having applied so that the cured film thickness might be set to 4.0 micrometers, bendability was inferior.

Comparative Example 7
(1) Hard coat agent High molecular weight urethane acrylate (manufactured by Negami Kogyo Co., Ltd., trade name Art Resin HDP-4T nonvolatile content 70%) 100 parts by weight MEK 75 parts by weight, 1-hydroxycyclohexyl phenyl ketone as an initiator Of 3.5 parts by weight to obtain a hard coating agent.
(2) Hard molding film for insert molding Next, the hard coating agent was applied to a 100 μm PET (polyethylene terephthalate) film by a bar coating method so as to have a cured film thickness of 2.5 μm, and 100 ° C. with a hot air dryer. Dried for 2 minutes. Thereafter, ultraviolet rays were irradiated with an integrated light amount of about 200 mJ / cm ² using an ultraviolet irradiation device (Fusion lamp manufactured by Fusion UV Systems Japan Co., Ltd.), but the scratch resistance and pencil hardness were inferior.

Comparative Example 8
In Comparative Example 7, the same procedure was performed except that the cured film thickness was 5.0 μm, but the bendability and scratch resistance were poor.

The evaluation results are shown in Table 1.

The evaluation method was as follows.
Test / Evaluation Method (1) Total light transmittance: Measured with a haze meter (manufactured by Suga Test Instruments Co., Ltd.) based on the provisions of JIS K 7361-1 (2000 edition) 3.2.
(2) Degree of haze: Measured with a haze meter (manufactured by Suga Test Instruments Co., Ltd.) according to JIS K 7136 (2000 version).
(3) Measurement of bendability A hard coat film with the hard coat agent coated surface outside is wound around the outer periphery of a tube having a radius of 1R to 6R, and evaluation is made based on whether or not a crack is generated in the resin layer. The minimum radius without cracks was taken as the value of bendability. It is determined that 1R to 3R is an allowable range, and 4R or more is inferior in bendability.
(4) Measurement of scratch resistance The surface of the hard coat film was rubbed with steel wool # 0000 manufactured by Nippon Steel Wool Co., Ltd. with a load of ² kg / cm ² , and the degree of scratch was visually evaluated. It was divided into four stages according to the way of scratching, and evaluation was performed as follows.
◎ or ○ is acceptable, and below △ is judged to be inferior in scratch resistance.
(Double-circle): A crack does not enter at all.
○: 1 to 5 scratches enter.
(Triangle | delta): 5-15 scratches enter.
X: 15 or more scratches enter.
(5) Measurement of pencil hardness It was performed based on the provisions of JIS K 5600-5-4 (1999 edition). As a measuring apparatus, a pencil scratch coating film hardness tester (type P) manufactured by Toyo Seiki Seisakusho Co., Ltd. was used. A pencil hardness of H or higher is considered acceptable, and F or lower is judged to be inferior.

Claims (3)

An unreacted hydroxyl group synthesized in one step from an aminotriazine compound, paraformaldehyde, and a hydroxyl group-containing (meth) acrylate and remaining in the triazine ring-containing (meth) acrylate prepolymer having an average molecular weight of 200 to 20,000 is converted into two or more isocyanates. A hard coating agent for insert molding, comprising as a main component a resin composition obtained by reacting with a group-containing compound, and comprising an organic solvent and a radical polymerization initiator. A hard coat film for insert molding, wherein the hard coat agent according to claim 1 is applied to a plastic film and cured, and the thickness of the cured coating film is 1 to 10 µm. The total light transmittance is 90% or more and 3R or less bendability, and the hard coat layer has a pencil hardness measured according to JIS K 5600-5-4 (1999 edition) of H or more. The hard coat film for insert molding according to claim 2.