JP2016011365A - Ultraviolet-curable hard coat agent - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a hard coat agent that has low shrinkage, is excellent in pencil hardness and abrasion resistance and is also excellent in flexibility.SOLUTION: An ultraviolet-curable hard coat agent is used, which includes a component (A): a polyfunctional urethane(meth)acrylate oligomer; a component (B): a colloidal silica modified with an acrylic group; a component (C): a polyfunctional thiol compound; and a component (D): a photopolymerization initiator. Additionally, a component (E): a fluorine-based surfactant having an ultraviolet reactive group is blended. The polyfunctional urethane(meth)acrylate oligomer is composed essentially of a dipentaerythritol hexaacrylate (DPHA) and a hexamethylene diisocyanate (HDI). As a polyfunctional thiol compound, a polyfunctional secondary thiol compound is used.

Description

  The present invention relates to an ultraviolet curable hard coat agent.

Plastic film is used in various industries such as the automobile industry and home appliance industry because it is lightweight and inexpensive in addition to its workability and transparency, but it is softer than glass and scratches on the surface. It has drawbacks such as easy attachment. In order to improve this defect, it is common practice to apply a hard coat agent. Regarding the formation of the hard coat layer, a system is adopted in which a hard coat agent is applied to a plastic film, dried, and then irradiated with radiation such as an electron beam or ultraviolet rays as necessary.
JP 2010-24255 A

  However, the conventional hard coat agent has a large curl after being applied to a film and cured, resulting in poor flexibility and cracks.

The present invention comprises (A) component: polyfunctional urethane (meth) acrylate oligomer,
(B) component: colloidal silica modified with an acrylic group,
(C) component: polyfunctional thiol compound,
(D) component: photopolymerization initiator,
And an ultraviolet curable hard coating agent.

The ultraviolet curable hard coat agent of the present invention can act as a curing accelerating catalyst with a polyfunctional secondary thiol compound and can provide flexibility, and as a result of blending colloidal silica modified with an acrylic group, it has low shrinkage, Excellent pencil hardness, abrasion resistance, and flexibility.
Hereinafter, the present invention will be described in detail. In the present specification, “(meth) acrylate” means “acrylate or methacrylate”.

  Component (A): The polyfunctional urethane (meth) acrylate oligomer comprises an aliphatic and / or alicyclic isocyanate compound and an active hydrogen capable of reacting with an isocyanate group (for example, a carboxyl group, a hydroxyl group, or an amino group hydrogen). It can be obtained by (meth) acryl modification of a compound obtained by reacting with a compound having the same.

  Examples of the hydroxyl group-containing (meth) acrylate compound include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, glycerin (meth) acrylate, trimethylolpropane (meth) acrylate, pentaerythritol (meth) acrylate, and glycerin. Examples include di (meth) acrylate, trimethylolpropane di (meth) acrylate, pentaerythritol tri (meth) acrylate, ditrimethylolpropane tri (meth) acrylate, and dipentaerythritol penta (meth) acrylate. It can also be used in combination.

  Examples of the aliphatic and / or alicyclic isocyanate compounds include hexamethylene diisocyanate, 4,4′-methylenebiscyclohexyl isocyanate, isophorone diisocyanate, trimethylhexamethylene diisocyanate, 1,3- (isocyanatomethyl) cyclohexane, norbornene diisocyanate, and the like. Polymers such as these bullets, nurates and adducts can be mentioned. These can be used alone or in combination. Particularly preferred are hexamethylene diisocyanate, isophorone diisocyanate, 4,4'-methylenebiscyclohexyl isocyanate, and their uretrates.

  In particular, a 10-functional urethane acrylate compound having a number average molecular weight of 600 to 800 and a peak of 2000 to 3000 composed of dipentaerythritol hexaacrylate (DPHA) and hexamethylene diisocyanate (HDI) as essential components, as a commercial product KUA-10H (manufactured by KS Corporation, product name) is preferably used.

  As inorganic particles, those having a hydroxyl group on the surface, especially colloidal silica particles obtained by a sol-gel method using alkoxysilane as a raw material, have a modifying group having a polymerizable functional group bonded to the surface hydroxyl group through a covalent bond. Since it is easy, it can be used suitably. Examples of the modifying group include a (meth) acrylic group or a vinyl group, and an acrylic group is particularly preferable. Examples of the compound into which the modifying group can be introduced include various alkoxysilane compounds having a polymerizable functional group. Can do. When the particle diameter of the acrylic group-modified silica particles is 1 to 50 nm, more preferably 5 to 30 nm, the dispersibility is good and the transparency is excellent.

Moreover, when the blending ratio is 50 to 100 parts by weight with respect to 100 parts by weight of the solid content of the polyfunctional urethane (meth) acrylate, the hardness is high and the curling property is excellent. As a commercially available product, (B) OSCAL1842 (average particle diameter 12 nm, SiO ₂ concentration 40.5 wt%, dispersion medium, methyl isobutyl ketone) from JGC Catalysts & Chemicals Co., Ltd. is recommended as colloidal silica modified with acrylic groups. The

  Component (C): A polyfunctional thiol compound is a compound having two or more thiol groups (-SH) in one molecule, and when used with a photopolymerization initiator, the reaction rate of double bonds is increased and curability is increased. Increases, the crosslinking density increases, and a harder cured product can be formed. By using a polyfunctional thiol compound, an ultraviolet curing reaction can be promoted with a small amount of photopolymerization initiator, and there is an advantage that curing shrinkage is small. In general, in the ene-thiol reaction, peroxide radicals due to oxygen react with thiol groups to generate thiyl radicals, so that they are not subjected to curing inhibition and exhibit good curing characteristics when irradiated with ultraviolet rays.

  Among polyfunctional thiol compounds, trifunctional or tetrafunctional thiol compounds are preferable, and examples of trifunctional thiols include 1,2,6-hexanetriol trithioglycolate, 1,3,5-trithiocyanuric acid, 1, 3,5-tris (3-mercaptobutyloxyethyl) -1,3,5-triazine-2,4,6, trimethylolpropane tris (3-mercaptopropionate), trimethylolpropane tristhioglycolate, Examples include trimethylolpropane tristhiopropionate, trihydroxyethyltriisocyanuric acid tristhiopropionate, tris-[(ethyl-3-mercaptopropionyloxy) -ethyl] isocyanurate, and the like.

  Examples of tetrafunctional thiols include pentaerythritol tetrakis (3-mercaptopropionate), pentaerythritol tetrakis (3-mercaptobutyrate), pentaerythritol tetrakisthioglycolate, dipentaerythritol hexakis-3-mercaptopropionate, and the like. Can be mentioned. Among these, a tetrafunctional secondary thiol group is preferable because of high crosslinking efficiency.

  Commercially available products include pentaerythritol tetrakis (3-mercaptobutyrate) (trade name, Karenz (registered trademark) MT-PE-1, manufactured by Showa Denko KK), 1,3,5-tris [2- (3 -Mercaptobutyryloxy) ethyl] -1,3,5-triazine-2,4,6 (1H, 3H, 5H) -trione (trade name: Karenz MT-NR-1 (manufactured by Showa Denko KK)) 1,4-bis (3-mercaptobutyryloxy) butane (trade name: Karenz MT BD1 (manufactured by Showa Denko KK)).

  As a compounding quantity of a polyfunctional thiol compound, it is 1-30 weight part with respect to solid content of 100 weight part of polyfunctional urethane (meth) acrylate, More preferably, it is 10-20 weight part, The compounding quantity of a polyfunctional thiol compound Is less than the lower limit, the curling property is inferior and cracks are likely to occur. On the other hand, when the upper limit is exceeded, the hardness of the coating film is lowered, and there is a risk that the odor tends to drift.

  By adding a small amount of the component (D) photopolymerization initiator, curing proceeds sufficiently, and light resistance of the coating film is improved. There are various photopolymerization initiators such as acetophenone, 2,2-diethoxyacetophenone, p-dimethylacetophenone, p-dimethylaminopropiophenone, benzophenone, 2-chlorobenzophenone, benzoin, benzoin methyl ether, benzoin ethyl ether. And carbonyl compounds such as benzoin isopropyl ether, and sulfur compounds such as thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, and tetramethylthiuram disulfide. A photoinitiator may be used independently or may use 2 or more types together.

  Commercially available photoinitiators include DASFURE 1116, DAROCURE 1173, IRGACURE 184, IRGACURE 369, IRGACURE 651, IRGACURE 651, IRGACURE 754, IRGACURE 819, IRGACURE 907, IRGACURE 1300, IRGACURE 907, IRGACURE 907 Can be used.

  Among these, it is preferable to mainly use an alkylphenone photopolymerization initiator from the viewpoints of curability, light stability, compatibility, low volatility, and low odor of the curable resin composition. 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy 2-methyl-1-phenyl-propan-1-one, 1- [4- (2-hydroxyethoxy) -phenyl] -2-hydroxy-2-methyl-1-propan-1-one, and the like. In addition, 2,4,6-trimethylbenzoyldiphenylphosphine oxide may be used in combination. When used in combination, the absorption wavelength of light is wide, and ultraviolet rays penetrate deeper to improve the curing of the coating film.

  Among the components (D), (d1) Irgacure 184 (1-hydroxy-cyclohexyl-phenyl-ketone) and (d2) Lucillin (LUCIRIN) TPO (diphenyl (2,4,6-trimethylbenzoyl) phosphine) are particularly preferable. It is an oxide, and the blending ratio of the component (d1) and the component (d2) is preferably 5: 0.5 to 2, and when it is less than the lower limit or exceeds the upper limit, the adhesion as shown in the comparative example Tends to be inferior.

  The blending ratio of the photopolymerization initiator is 0.5 to 20 parts by weight, more preferably 1 to 10 parts by weight with respect to 100 parts by weight of the solid content of the polyfunctional urethane (meth) acrylate. If the upper limit is exceeded, the irradiated ultraviolet light is absorbed by the photopolymerization initiator, the ultraviolet light permeability to the component (A) becomes insufficient, and the curability may be lowered.

  Component (E): When a fluorine-based surfactant having an ultraviolet reactive group is added, it forms a strong bond with the polyfunctional urethane (meth) acrylate, thus forming a hard coat layer with excellent durability and fingerprint resistance. be able to. Examples of commercially available products include KY-1200, X-71-1203M (trade name, manufactured by Shin-Etsu Chemical Co., Ltd.), Megafuck RS-72-K, Megafuck RS-75, Megafuck RS-76-E, Mega Fuck RS-76-NS, Mega Fuck RS-77 (all are trade names, manufactured by DIC Corporation) and the like. The content of the fluorine-based surfactant having an ultraviolet reactive group is preferably 1 to 5 parts by weight with respect to 100 parts by weight of the solid content of the polyfunctional urethane (meth) acrylate compound.

  The above components are diluted with a solvent to adjust the solid content to 45 to 55%. Any solvent may be used as long as it can dissolve or disperse a polyfunctional urethane (meth) acrylate, a polyfunctional secondary thiol compound, a photopolymerization initiator, and can uniformly disperse colloidal silica modified with an acrylic group. Alcohol solvents such as methanol, ethanol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, sec-butyl alcohol, tert-butyl alcohol, methyl cellosolve, ethyl cellosolve, butyl cellosolve, n-propyl cellosolve, etc. Cellosolve solvents, ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, isophorone, ester solvents such as methyl formate, butyl formate, methyl acetate, butyl acetate, diethyl Ether, ether solvents such as diisopropyl ether, N, N- dimethylformamide, N, amide solvents such as N- dimethylacetamide.

  The ultraviolet curable hard coat agent essentially comprising the above components is a plastic film such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyethylene film, polypropylene film, cellophane, diacetyl cellulose film, triacetyl cellulose film, acetyl cellulose butyrate. Rate film, polyvinyl chloride film, polyvinylidene chloride film, polyvinyl alcohol film, ethylene-vinyl acetate copolymer film, polystyrene film, polycarbonate film, polymethylpentene film, polysulfone film, polyether ether ketone film, polyether sulfone film , Polyetherimide film, polyimide film, fluorine resin film Beam, nylon film, can be applied to an acrylic resin film or the like.

When curing the ultraviolet curable hard coat agent, an ultraviolet lamp is used as an ultraviolet ray generation source. Specific examples include a low pressure mercury lamp, a high pressure mercury lamp, an ultrahigh pressure mercury lamp, a xenon lamp, and a metal halide lamp. In the case of irradiation, it may be in air or in an inert gas such as nitrogen or argon. Irradiation intensity ^{at 500mW / cm 2 ~3000mW / cm 2} , the amount of work with ultraviolet processing in 50~400mJ / cm ^2.

(A) component: As polyfunctional urethane (meth) acrylate, dipentaerythritol hexaacrylate (DPHA) and hexamethylene diisocyanate (HDI) as essential components, a number average molecular weight of 600 to 800 and a peak of 2000 to 3000 100 parts by weight of a 10-functional urethane acrylate compound having a peak of (KUA-10H, manufactured by KS Corporation, product name),
Component (B): As colloidal silica modified with an acrylic group, OSCAL 1842 (silica organosol dispersion, average particle diameter 12 nm, SiO ₂ concentration 40.5 wt%, dispersion medium: methyl isobutyl ketone, particle refractive index 1.46 250 parts by weight of JGC Catalysts &Chemicals;
(C) Component: 10 parts by weight of pentaerythritol tetrakis (3-mercaptobutyrate) (trade name, Karenz (registered trademark) MT-PE-1, Showa Denko KK) as a tetrafunctional secondary thiol compound,
Component (D): As a photopolymerization initiator, 4.5 parts by weight of Irgacure 184 (manufactured by BASF Japan, 1-hydroxy-cyclohexyl-phenyl-ketone), LUCIRINTPO (manufactured by BASF Japan, 2,4,6- 4.5 parts by weight of trimethylbenzoyldiphenylphosphine oxide)
(E) component: 2.2 parts by weight of X-71-1203M (active ingredient 20% manufactured by Shin-Etsu Chemical Co., Ltd.) as a fluorine-based surfactant having an ultraviolet-reactive group,
As a solvent, 225 parts by weight of methyl ethyl ketone (MEK) was blended to obtain an ultraviolet curable hard coat agent having a solid content of 50%.

  In Example 1, it implemented similarly except having made pentaerythritol tetrakis (3-mercaptobutyrate) into 15 weight part.

  In Example 1, it implemented similarly except having made pentaerythritol tetrakis (3-mercaptobutyrate) into 20 weight part.

  In Example 1, in place of KUA-10H, a peak having a number average molecular weight of 600 to 800 and a peak of 2000 to 3000 composed of dipentaerythritol hexaacrylate (DPHA) and hexamethylene diisocyanate (HDI) as essential components It implemented similarly except having used the 10 functional urethane acrylate compound (KUA-10H-M, the KSM Co., Ltd. make, product name) which has NO.

  In Example 4, it implemented similarly except having made pentaerythritol tetrakis (3-mercaptobutyrate) into 15 weight part.

  In Example 4, it carried out similarly except having made pentaerythritol tetrakis (3-mercaptobutyrate) into 20 weight part.

Comparative Example 1
In Example 1, the same except that colloidal silica having a methacrylic group (MIBK-SD-L, nonvolatile content 30%, manufactured by Nissan Chemical Industries, Ltd., product name) was used instead of colloidal silica modified with acrylic group. Implemented.

Comparative Example 2
In Comparative Example 1, the same procedure was performed except that the colloidal silica having a methacryl group was changed to 15 parts by weight.

Comparative Example 3
In Comparative Example 1, the same procedure was performed except that the colloidal silica having a methacryl group was 20 parts by weight.

Comparative Example 4
In Example 4, it implemented similarly except not having used pentaerythritol tetrakis (3-mercaptobutyrate).

The evaluation results are shown in Table 1.

The evaluation method was as follows.
Preparation of test piece: A composition having a dry film thickness of 20 μm is applied on a thickness of 400 μm made of polycarbonate and polymethyl methacrylate resin, dried at 80 ° C. for 5 minutes in a hot air circulating dryer, and then 800 Curing was performed with ultraviolet rays of ˜1200 mJ / cm ² .

(1) Pencil hardness: Based on JIS K5600-5-4, it evaluated by 1 kg load.
(2) Abrasion resistance: Steel wool (trade name Bonstar # 0000, manufactured by Nippon Steel Wool Co., Ltd.) was used, and a load of 500 g / cm ² was applied, and the coating film was rubbed 100 times. After the test, it was evaluated by the number of scratches entered. ○: No scratch ×: Scratched (3) Impact resistance: A 130 g iron ball was dropped from a height of 30 cm.
○: No cracking x: Cracking (4) Flexibility: A composition having a dry film thickness of 20 μm is applied on a thickness of 200 μm made of polymethyl methacrylate resin, cured with ultraviolet rays, and then cylindrical with a diameter of 32 mm Folded along the mandrel and evaluated. (Test equipment: BYK Gardner No. 5710)
○: No abnormality.
X: There is a crack.

Claims (5)

(A) component: polyfunctional urethane (meth) acrylate oligomer,
(B) component: colloidal silica modified with an acrylic group,
(C) component: polyfunctional thiol compound,
(D) component: photopolymerization initiator,
And an ultraviolet curable hard coat agent. The ultraviolet curable hard coating agent according to claim 1, wherein the polyfunctional urethane (meth) acrylate oligomer is composed of dipentaerythritol hexaacrylate (DPHA) and hexamethylene diisocyanate (HDI) as essential components. 2. The ultraviolet curable hard coat agent according to claim 1, wherein the polyfunctional thiol compound is a polyfunctional secondary thiol compound. The ultraviolet curable hard coat agent according to claim 3, wherein the polyfunctional secondary thiol compound is pentaerythritol tetrakis (3-mercaptobutyrate). Furthermore, (E) component: The ultraviolet curable hard-coat agent of Claims 1-4 containing the fluorine-type surfactant which has an ultraviolet-reactive group.