JPH04110356A - Actinic radiation-curable coating material - Google Patents

Abstract

PURPOSE:To obtain the title material excellent in antistatic properties and mar resistance by mixing a specified poly(meth)acrylate monomer with a quat. ammonium salt monomer. CONSTITUTION:An actinic radiation-curing coating material which can impart excellent antistatic properties and mar resistance to many plastics is obtained by mixing a poly(meth)acrylate monomer having at least four (meth)acryloyloxy groups [e.g. trimethylolmethane tetra(meth)acrylate] with a quat. ammonium salt monomer (e.g. methacryloyloxyethyltrimethylammonium chloride). To form a crosslinked cured film on the surface of a plastic by applying this material thereto, irradiation with ultraviolet rays, electron beams or the like is necessary. Irradiation with ultraviolet rays is desirable from practical use, and it is necessary in this case to add a photopolymerization initiator (e.g. benzophenone) which forms free radicals upon irradiation with ultraviolet rays in advance.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an active energy ray-curable coating agent for various plastics that has excellent antistatic properties and scratch resistance.

(Conventional technology) Plastics are recognized for their excellent mechanical and electrical properties such as light weight, toughness, transparency, workability, and electrical insulation.
It is widely used as an industrial material in fields such as electronics, architecture, home appliances, and vehicles.

However, these plastic materials have the drawbacks that, due to their electrical insulation properties and low moisture absorption, they tend to generate static electricity, are easily contaminated by dirt and dust, and are easily scratched by friction.

As methods for preventing the generation of static electricity, methods such as kneading or coating a surfactant-type antistatic agent, or coating a siloxane-based antistatic agent are known.

In addition, methods for imparting scratch resistance include thermosetting, moisture-curing, active energy ray-curing coatings, etc.
A method of forming a crosslinked film on the surface is well known, and in this method, polyfunctional (meth)acrylate monomers containing 2 to 3 (meth)acryloyloxy groups in the molecular chain and quaternary ammonium salt-containing A method using a monomer is known (Japanese Unexamined Patent Publication No. 49-51371).

(Problems to be Solved by the Invention) However, with these methods, it is not possible to obtain a coating agent that is sufficiently excellent in both antistatic ability and scratch resistance, and there is a strong desire for the emergence of a coating agent that is particularly excellent in scratch resistance. It is rare.

(Means for Solving the Problems) In view of the above circumstances, the present inventors have conducted intensive research and found that a specific quaternary ammonium-containing monomer and a specific polyfunctional (meth)acrylate monomer are The present inventors discovered that adding a photopolymerization initiator makes it possible to obtain a coating agent for plastics with excellent antistatic ability and scratch resistance, leading to the completion of the present invention.

That is, the present invention contains a polyfunctional (meth)acrylate monomer (A) containing at least four (meth)acryloyloxy groups and a quaternary ammonium salt-containing monomer (B). The present invention provides an active energy ray-curable coating agent characterized by the following properties.

Single polyfunctional (meth)acrylate used in the present invention (
As A), any (meth)acrylate monomer having at least four (meth)acryloyloxy groups can be used, such as trimethylolmethanetetra(meth)
acrylate, pentaerythritol tetra(meth)acrylate), dipentaerythritol tetra(meth)
Examples include acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, and the like. The most preferable ones are
Trimethylolmethane tetra(meth)acrylate, pentaerythritol tetraacrylate, dipentaerythritol tetraacrylate, dipentaerythritol hexaacrylate, and particularly preferred is dipentanistriol hexaacrylate 1. .

As the quaternary ammonium salt-containing monomer (B), quaternary
Any monomer having a class ammonium salt can be used,
For example, methacryloyloxy lower alkyl tri-lower alkyl ammonium chloride such as methacryloyloxymethyl trimethyl ammonium chloride and methacryloyloxyethyl trimethyl ammonium chloride; methacryloyloxy lower alkyl tri-lower alkyl such as methacryloyloxymethyl trimethyl ammonium sulfate and methacryloyloxyethyl trimethyl ammonium sulfate. Examples include ammonium sulfate. Among them, methacryloyloxy lower alkyl tri-lower alkyl ammonium chloride is preferred because of its excellent antistatic ability, and methacryloyloxyethyl trimethyl ammonium chloride is particularly preferred.

Weight ratio (A) of polyfunctional (meth)acrylate monomer (A) and quaternary ammonium salt-containing monomer (B) in coating agent
/ (B) is usually in the range of 50150 to 9515, but it is 65/35 because it has excellent antistatic ability, coating hardness, adhesion, and water resistance, and is less likely to become cloudy due to moisture absorption.
A range of 9515 to 9515 is particularly preferred.

A solvent can be further added to the coating agent of the present invention, if necessary. Examples of the solvent include alcohols such as methanol, ethanol, isopropyl alcohol, and N-butyl alcohol; aromatic hydrocarbons such as toluene and xylene; and esters such as ethyl acetate, ethyl cellosolve, methyl cellosolve, and cellosolve acetate. . These solvents may be used alone or in combination of two or more, but from the viewpoint of solubility, it is desirable to use 50% by weight or more of alcohol in the solvent. Among these, methanol is particularly preferred.

In order to apply a coating with excellent antistatic properties and scratch resistance to a plastic surface using the coating agent of the present invention to form a crosslinked cured film, irradiation with ultraviolet rays, electron beams, or radiation is necessary. Among these, a curing method using ultraviolet rays is particularly preferred from a practical standpoint; in this case, it is necessary to add a photopolymerization initiator that generates radicals by irradiation with ultraviolet rays.

Specific examples of the photopolymerization initiator (C) include hensifhenone, p-chlorobenzophenone, 4゜4'-bis(diethylamino)hensifhenone, benzoino, benzoin ethyl ether, acetofuvenone, 2-chlorothioxanthone, 2-ethyl anthraquinone. , 2-amine anthraquinone, 2-chloroanthraquinone, α-hydroxybutylphenone and other abstracted and cleaved carbonyl compounds, tetramethylthiuram, disulfide and other sulfur compounds. These photopolymerization initiators may be used alone or in combination of two or more.

The usage amount of these photopolymerization initiators (C) is as follows:
B) Based on 100 parts by weight of resin solid content consisting of both components,
Usually 0. The amount is 1 to 5 parts by weight, and the range of 0.5 to 3 parts by weight is particularly preferable in terms of not reducing the weather resistance or discoloring the coating film.

In addition, this coating agent may further contain acrylic prepolymers such as polyester acrylate prepolymers, epoxy acrylate prepolymers, acrylic urethane prepolymers, leveling agents, antifoaming agents, matting agents, ultraviolet absorbing agents, etc., as necessary. Known additives such as antioxidants and antioxidants may also be added.

Examples of plastics for which the coating agent having excellent antistatic properties and scratch resistance of the present invention can be used include acrylic resin, polycarbonate resin, polyvinyl chloride resin, polyethylene terephthalate resin, acrylonitrile-butadiene-styrene resin, etc. Can be mentioned. Applications include electronics materials such as tape cases and ■C transportation containers;
Building materials such as plastic panels; Home appliance materials such as lighting equipment, audio equipment, etc.; Vehicle parts materials such as instrument housings and interior parts; Other stores (including industrial materials).

Examples of methods for applying the coating agent of the present invention having excellent antistatic properties and scratch resistance to plastic materials include roll-two coating, flow coater coating, gravure coater coating, spray coating, and dipping coating. You can select it as appropriate.

The appropriate coating thickness is 3 to 10 μm, especially 4 to 7 μm from the viewpoint of antistatic ability, adhesion, scratch resistance, and durability.
m is preferred.

(Examples) The present invention will be specifically explained below using Examples and Comparative Examples. All parts in the examples are parts by weight.

Examples] to 8 and Comparative Examples 1 to 5 Each raw material was blended with the composition shown in Table 1 to prepare antistatic coating agents for the present invention and for comparison.

Next, this coating agent was applied to the base sheet shown in Table 1 using a bar coater, and after drying at 60°C for 3 minutes,
A plastic sheet with a cured coating was obtained by irradiating ultraviolet rays for 5 seconds using a w/cm high-pressure mercury lamp [manufactured by Nippon Battery Co., Ltd.], and its performance was evaluated by the following test. Display the results -
Shown in 2.

Adhesion test: Make 100 1.0 mm square cuts from the painted surface to the underlying plastic, apply cellophane tape on top of it, then peel it off vigorously. was counted and expressed with the denominator as 100.

Paint film hardness test: According to J'IS K-5400,
Measure the pencil hardness under a load of 1 kg.

Scratch resistance test: The painted surface was strongly scratched with a fingernail, and the degree of scratching was visually evaluated on the following four scales.

◎---No scratches are observed.

○---Some scratches are observed.

Δ---Flaws are observed.

×-11 Significant scratches are observed.

Antistatic ability test 0 Surface resistance value: Measured using an ultra-high insulation resistance meter (manufactured by Kasuga Denki) in an atmosphere with a relative humidity of 30% and a temperature of 20°C.

■Half-life: Static Honest Meter (manufactured by Kyogatsu Shokai)
Measurements were made in an atmosphere with an applied voltage of 10 kV, relative humidity of 55%, and temperature of 20°C.

Humidity test = 40°C 1 relative humidity 95% constant temperature and humidity chamber (
After leaving the material in the Takeda Riken (manufactured by Takeda Riken) for 100 hours, and leaving it at room temperature for 24 hours, the adhesion, coating hardness, and
The antistatic ability was evaluated.

In addition, polyfunctional (meth)acrylate single substance A- in Table-1
1 to A-5, quaternary ammonium salt-containing monomer B-1 to
B-3, photopolymerization initiators C-1 to C-2, and various base sheets are as follows, respectively.

A-1 Nidipentaerythritol hexaacrylate A-2 = Pentaerythritol tetraacrylate A-3: ) Limethylolmethane tetraacrylate A-4: l-1,1 Methylolpropane triacrylate A-5: h Liethylene glycol dimethacrylate B -1: Methacryloyloxymethyltrimethylammonium sulfate B-2 = Methacryloyloxyethyltrimethylammonium chloride B-3: Methacryloyloxymethyltrimethylammonium sulfate C-1: 2-Hydroxy-2-methyl-1-phenyl-
Propan-1-one C,-2:1-Hydroxycyclohexylphenylketone ABS: Acrylonitrile-butadiene-styrene resin AC; Acrylic resin Pc: Polycarbonate resin PVC: Polyvinyl chloride resin (effects of the invention) Book The coating film obtained from the active energy ray-curable coating agent of the invention has the advantage of having extremely excellent antistatic ability and scratch resistance, excellent adhesion, and good coating film physical properties such as moisture resistance. be.

Claims (1)

[Claims] 1. Contains a polyfunctional (meth)acrylate monomer (A) containing at least four (meth)acryloyloxy groups and a quaternary ammonium salt-containing monomer (B). An active energy ray-curable coating agent that is characterized by the following properties: 2. The coating agent according to claim 1, further comprising a photopolymerization initiator (C). 3. The coating agent according to claim 1 or 2, wherein the quaternary ammonium salt-containing monomer (B) is methacryloyloxy lower alkyl tri-lower alkyl ammonium chloride. 4. The coating agent according to claim 1 or 2, wherein the quaternary ammonium salt-containing monomer (B) is methacryloyloxyethyltrimethylammonium chloride. 5. Weight ratio (A)/(
The coating agent according to claim 1, 2 or 3, wherein B) is 65/35 to 95/5.