JP2892290B2 - UV curable protective coating composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a silicone composition which is rapidly cured by short-time ultraviolet irradiation. The composition of the present invention is useful as a protective coating agent, an antifouling coating agent, a coating agent for preventing sticking paper, a release agent, a release agent, a water / oil repellent, and the like.

[0002]

2. Description of the Related Art Conventionally, a release silicone coating agent is applied to a substrate such as plastic, glass, metal, etc. for the purpose of protective coating, antifouling coating, etc., to form a cured release layer having releasability. There was something. However, such a cured film layer may have poor adhesion to the substrate, or may have low hardness of the film and poor scratch resistance. On the other hand, in the cured film of the silicone hard coating agent, the adhesive tape, poor releasability to the adhesive, easily adhere to oily or aqueous dirt components,
Sometimes it was difficult to remove. In addition, these silicone coating agents are often applied by diluting them in an organic solvent. In this case, a method of removing the solvent by heating and baking to form a coating film layer on the substrate is not suitable. However, in this process, many organic solvents are discharged, and there is a problem that much heat energy is required for film formation. In addition, because of the influence of heating, it cannot be applied to a substrate having poor heat resistance. There was something.

[0003] Therefore, in order to improve productivity and save energy, and to apply to a substrate having poor heat resistance, curing at a low temperature and in a short time is required. In consideration of preventing such a situation, it is advantageous to form a cured film on the substrate by irradiating ultraviolet rays. As a curable composition which can be cured by ultraviolet rays, a composition comprising an organopolysiloxane having an epoxy group and an onium salt-based photoinitiator is known (see JP-A-56-38350). This composition is said to have excellent release properties with the adhesive substance, but the adhesion to the substrate is insufficient, or a good release property cannot be obtained depending on the type of the adhesive substance, There was a disadvantage that workability was poor because the surface of the cured film had no slipperiness. Further, there is an example in which a photocationically curable silicone composition is used for producing an antifouling coating sheet (see JP-A-6-87190), but this has a problem in that the cured film has low hardness and abrasion resistance.

[0004]

Under the circumstances described above, the present invention is excellent in curability, and the formed film has excellent release properties, has slipperiness, has high hardness, and has excellent scratch resistance. It is an object of the present invention to provide an ultraviolet-curable protective coating composition having good adhesion to a substrate, particularly to a plastic.

[0005]

SUMMARY OF THE INVENTION The ultraviolet curable protective coating composition of the present invention solves the above-mentioned problems. (A) Addition reaction between an organopolysiloxane having a SiH group and an epoxy resin having an alkenyl group. Product: 1 to 99 parts by weight (B) Vinyl ether compound 99 to 1 part by weight (C) Photocationic initiator 0.01 to 20 parts by weight (D) Photoradical initiator 0.1 to 40 parts by weight It is. Hereinafter, the present invention will be described in more detail.

The component (A) is an addition reaction product of a SiH group-containing organopolysiloxane and an alkenyl group-containing epoxy resin, and the SiH group-containing organopolysiloxane used in the production thereof is linear, branched or cyclic. Any of them may be used having at least two structural units (I) shown below in one molecule. R _p H _q SiO _{(4-pq) / 2} (I) In the formula, p is an integer of 0 to 2, q is an integer of 1 to 3, p + q ≦
3. R is an unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms, specifically, an alkyl group such as a methyl group, an ethyl group, a propyl group, or a butyl group; a cycloalkyl group such as a cyclohexyl group; An aryl group such as a tolyl group, or a hydroxypropyl group in which part or all of the hydrogen atoms bonded to carbon atoms of these groups have been substituted with a hydroxyl group, a cyano group, a halogen atom, or the like;
Cyanoethyl group, 3-chloropropyl group, 3,3,3-
Examples thereof include a trifluoropropyl group. Further, the organopolysiloxane contains 0.1 to 10 mol%, more preferably 1 to 5 mol% of the unit of the above formula (I) in all units.
It is preferred to contain. In this case, as the other units, R ¹ ₃ SiO _1/2 units, R ¹ ₂ SiO units, R ¹ SiO _3/2 units, SiO ₂
Any one or more of the units may be included. Note that R ¹ is the same group as R or an alkoxy group.

As specific examples of the organopolysiloxane having a SiH group, Me ₃ SiO- (MeHSiO) _5- (Me ₂ SiO) ₁₀₀ -SiMe ₃ , Me
₂ HSiO- (Me ₂ SiO) ₁₀₀ -SiMe ₂ H, Me ₂ HSiO- (MeHSiO) _2- (Me ₂ Si
_{O) 50 -SiMe 2 H, (} Me 2 HSiO 1/2) 4 - (Me 2 SiO) 50 - (MeSi
O _3/2 ) ₂ , Me ₂ HSiO- (Me ₂ SiO) _30- (MePhSiO) ₅ -SiMe ₂ H, (Me
O) Me ₂ SiO- (Me ₂ SiO) _30- (MeHSiO) ₃ -SiMe ₂ (OMe), (MeHSi
O) ₂ (Me ₂ SiO) ₂ (cyclic body) and the like, and these can be used alone or in combination of two or more.
In the above formula, Me represents a methyl group and Ph represents a phenyl group (the same applies hereinafter).

The alkenyl group-containing epoxy resin is not particularly limited as long as it has an alkenyl group and an epoxy group, but an alkenyl group-containing epoxy resin having an aromatic ring is preferred, and an alkenyl group-containing epoxidized phenol novolak resin is particularly preferred. And epoxidized cresol novolak epoxy resin. The alkenyl group-containing epoxy resin can be obtained by epoxidizing an alkenyl group-containing phenol resin with epichlorohydrin, or partially reacting a conventionally known epoxy resin with 2-allylphenol, allyl alcohol, or the like. Specific examples of such an alkenyl group-containing epoxy resin include those represented by the following formula. In the following formula, x and y are integers of 1 <x <50 and 1 <y <50, respectively, and it is desirable that y / (x + y) = 0.01 to 0.2.

[0009]

Embedded image

The component (A) can be obtained by subjecting the organopolysiloxane containing SiH group and epoxy resin containing alkenyl group to an addition reaction in the presence of a platinum-based addition reaction catalyst. The weight ratio of the organopolysiloxane containing SiH groups to the epoxy resin containing alkenyl groups is 2/8 by weight.
８8/2 is desirable. The reaction conditions may be those usually employed for the addition reaction.

The component (B) is a vinyl ether compound. By using this component, the adhesion to the substrate and the curability can be improved. Further, the viscosity of the composition can be reduced, and the workability during coating can be improved. This vinyl ether compound is a compound having at least one vinyl ether group in one molecule, and examples thereof include those represented by the following formula. (R ² CH = CH-0) _n -X (II) In the formula, R ² is a hydrogen atom or a methyl group, n is an integer of 1 to 8, X is a residue of an organic polyhydric alcohol or an organic polyhydric alcohol. It is a residue of an ester composed of a polyhydric alcohol and a polybasic acid.

In this case, examples of the organic polyhydric alcohol include ethylene glycol, polyethylene glycol having a polymerization degree of 2 to 30, propylene glycol, polypropylene glycol having a polymerization degree of 2 to 30, 2,2,4-trimethyl-
1,3-pentanediol, 1,4-cyclohexanedimethanol, 2,2-bis [4- (2-hydroxyethoxy) phenyl] propane, 2,2-bis [4- (2-
Hydroxypropoxy) phenyl] propane, 2,2-
Bis (4-hydroxyphenyl) propane, 2,2-bis (4-hydroxycyclohexyl) propane, 1,6
-Hexanediol, 1,5-pentanediol, 2-
Ethyl hexanediol, glycerin, trimethylolpropane and the like can be mentioned. Examples of polybasic acids include phthalic acid, adipic acid, sebacic acid, maleic acid, fumaric acid, and the like.

Specific examples of the component (B) include propylene glycol divinyl ether, polyethylene glycol divinyl ether, trimethylolpropane trivinyl ether and the like, and CH ₂ CHCH—O— (CH ₂ ) ₆ —O—CHCH CH ₂ , CH ₂ = CH-O- (CH ₂ CH ₂ O) ₆ -CH = C
H ₂ , CH ₂ = CH-O-CH ₂ -C ₆ H ₄ -CH ₂ -O-CH = CH ₂ , CH ₂ = CH-O- (CH ₂ ) ₆ -O
H, (CH ₂ = CH-O-CH ₂ CH ₂ CH ₂ ) Me ₂ SiO- (Me ₂ SiO) ₁₀ -SiMe ₂ (CH ₂ CH ₂
CH ₂ -O-CH = CH ₂ ), Me ₃ SiO- (Me ₂ SiO) ₅ -[(CH ₂ = CH-O-CH ₂ CH ₂ CH ₂ ) MeSiO] ₅ -SiMe
₃ ,

Embedded image And the like. The mixing ratio of the vinyl ether compound as the component (B) and the addition reaction product as the component (A) is such that the component (A) / the component (B) = 1/99 to 99 / parts by weight.
1, preferably 40/60 to 95/5.

The component (C) is a photocationic initiator. Among them, an onium salt-based photoinitiator is preferred. As specific examples of the formula _{^{R 3 2 I + X -,}} R 3 3 S + X -, R 3 2 R 4 S + X -, R 3 R 4 2 S + X
_{^{-, R 3 3 Se + X}} -, R 3 4 P + X -, R 3 N 2 + X - ( wherein, R ³ is an aryl group, R ⁴ is an alkyl group, X ^- is SbF ₆ ^-, AsF _{6 ^{-, PF 6 -, BF 4}} -, HSO 4
_{^{-, ClO 4 -, Cl -}} , CF 3 SO 3 - diaryl iodonium salt represented by the anion) such as a triarylsulfonium salt,
Monoaryldialkylsulfonium salts, triarylselenonium salts, tetraarylphosphonium salts, aryldiazonium salts and the like can be mentioned. The addition amount of this photocationic initiator is 100% in total of the component (A) and the component (B).
0.01 to 20 parts by weight, preferably 0.5 to
It may be 10 parts by weight. When the amount is less than 0.01 part by weight, the curability becomes insufficient, and when the amount is more than 20 parts by weight, the surface condition of the cured film is adversely affected and the releasability of the cured film is deteriorated.

The component (D) is a photoradical initiator. By using the component (D) in combination with the component (C) as a photoinitiator, the curability is improved and the hardness of the cured film is increased. Can be. Among the photoradical initiators, acetophenone-based photoinitiators are preferable, and examples thereof include those represented by the following formula.

Embedded image R ⁵ in the formula is a hydrogen atom or a hydrocarbon group having 1 to 4 carbon atoms,
R ⁶ is a hydrogen atom, an alkyl group having 1 to 4 carbon atoms,
An aryl group of 8 or both R ⁶ are linked by a carbon-carbon bond to an alkylene group having 4 to 5 carbon atoms and bonded to the same carbon atom, and R ⁷ represents a hydroxyl group or an alkoxy group having 1 to 6 carbon atoms. as,

[0016]

Embedded image And the like. The addition amount of this photo radical initiator is
0.1 with respect to 100 parts by weight of the total of the components (A) and (B)
To 40 parts by weight, preferably 0.5 to 20 parts by weight. If the amount is less than 0.1 part by weight, the curability becomes insufficient, and if the amount is more than 40 parts by weight, the surface condition of the cured film is adversely affected, and the releasability of the cured film is deteriorated.

The composition of the present invention can be obtained by uniformly mixing predetermined amounts of the components (A), (B), (C) and (D) described above. The composition of the present invention may further contain an epoxy diluent, an acrylate monomer, an acrylate oligomer, a sensitizer, an adhesion enhancer to a substrate, a leveling agent, an antistatic agent, an antifoaming agent, a pigment, etc., if necessary. May be added, or when an organic solvent may be used, it may be diluted with an organic solvent before use.

The substrate on which the composition of the present invention can be coated includes plastic films and sheets obtained from synthetic resins such as polyester, polypropylene, polyethylene, polyvinyl chloride, polytetrafluoroethylene, polyimide and polyamide. Synthetic resin and composite material of synthetic fiber, inorganic fiber, non-woven fabric, etc., paper base such as glassine paper, kraft paper, clay coated paper,
Examples thereof include laminated paper such as polyethylene-laminated high-quality paper, polyethylene-laminated kraft paper, and the like, metals such as aluminum and copper, ceramics, and glass, and are particularly useful for plastic films such as polyester, polypropylene, polyethylene, and polyvinyl chloride.

For applying the composition of the present invention to a substrate, known methods such as roll coating, gravure coating, wire doctor coating, air knife coating, and dipping coating can be used. The coating amount may be 0.1 to 200 g / m ² , and this coating film is easily cured by irradiating ultraviolet rays. Examples of the ultraviolet light source include a mercury arc lamp, a high-pressure mercury lamp, a medium-pressure mercury lamp, a low-pressure mercury lamp, and a metal halide lamp. 8cm when using a high pressure mercury lamp (80W / cm) to cure the above coating
Irradiation may be performed from the distance of 0.01 to 10 seconds.

[0020]

Next, examples of the present invention will be described. Parts in the examples indicate parts by weight. The obtained coating composition was evaluated by the following method. Peeling force: The coating composition was applied to a polyvinyl chloride sheet using a wire bar so that the solid content became 15 g / m ^2, and irradiated with a 80 W / cm high-pressure mercury lamp from a distance of 8 cm to form a cured film. Formed. On the surface of this cured film, apply polypropylene adhesive tape No.835 (Sekisui Chemical Co., Ltd., 50
mm width), aged at 25 ° C for 24 hours, aged at 180 ° using a tensile tester at a peeling rate of 0.3m / min. The force (g / 50 mm) was measured. Curability: In the same manner as in the case of the peeling force measurement, the silicone composition is applied to the surface of the base material, and irradiated with a high-pressure mercury lamp of 80 W / cm from a distance of 8 cm while moving using a conveyor to cure. The conveyor speed was determined. Adhesion: A cured film of the silicone composition was formed on the surface of the substrate in the same manner as in the case of the peel force measurement. The surface of the cured film was strongly rubbed with a finger to examine whether the film had fallen off. Magic ink repellency: A cured film of the silicone composition was formed on the surface of the substrate in the same manner as in the case of the peel force measurement. A magic ink was applied to the surface of the cured film, wiped off with a gauze after air-drying, and examined for the presence of residual ink.

Example 1 Average composition formula

Embedded image 30 parts of an addition reaction product of an organopolysiloxane having a SiH group and an epoxy resin having an alkenyl group represented by the following, 70 parts of the above-listed vinyl ether compounds marked with * 2, the formula (tC ₄ H _{9 -C 6 H 4) 2 I} + (SbF 6) - 1.5 parts cationic photoinitiator represented by was mixed with 5 parts asterisked 3 marks of the photoradical initiator exemplified above process A liquid was prepared. The curability of this treatment liquid, the peel strength of the cured film, the adhesion, the repellency of the magic ink, and the pencil hardness were measured. Table 1 shows the results.

Example 2 Average composition formula

Embedded image 40 parts of the addition reaction product of the SiH group-containing organopolysiloxane and the alkenyl group-containing epoxy resin shown in the above, 60 parts of the above-listed vinyl ether compounds marked with * 1, used in Example 1. Photo cation initiator
1.5 parts and 5 parts of the photoradical initiator used in Example 1 were mixed to prepare a treatment liquid. The curability of this treatment liquid, the peel strength of the cured film, the adhesion, the repellency of the magic ink, and the pencil hardness were measured. Table 1 shows the results.

Example 3 Average composition formula

Embedded image 30 parts of an addition reaction product of an organopolysiloxane having a SiH group and an epoxy resin having an alkenyl group represented by, 70 parts of a vinyl ether compound used in Example 1, 1.5 parts of a photocationic initiator used in Example 1, 5 parts of the photoradical initiator used in Example 1 were mixed to prepare a treatment liquid. The curability of this treatment liquid, the peel strength of the cured film, the adhesion, the repellency of the magic ink, and the pencil hardness were measured. Table 1 shows the results.

Comparative Example 1 The addition reaction product 30 of the organopolysiloxane containing SiH groups and the epoxy resin containing alkenyl groups used in Example 1
Parts, 70 parts of the vinyl ether compound used in Example 1 and 1.5 parts of the photocationic initiator used in Example 1 were mixed to prepare a treatment liquid. The curability of this treatment liquid, the peeling force of the cured film,
The adhesion, magic ink repulsion, and pencil hardness were measured. Table 1 shows the results.

Comparative Example 2 A treatment liquid was prepared by mixing 100 parts of an ultraviolet-curable epoxy resin KRM-2110 (trade name, manufactured by Asahi Denka Kogyo KK) and 2 parts of an iodonium salt photoinitiator. Curability of this treatment liquid,
The peel strength, adhesion, magic ink repellency, and pencil hardness of the cured film were measured. Table 1 shows the results.

[0026]

[Table 1]

[0027]

The ultraviolet-curable protective coating composition of the present invention has excellent curability, and the formed film has excellent release properties, slip properties, high hardness and excellent scratch resistance, and Since the adhesiveness to the material, particularly plastic, is good, it is extremely advantageous in practice.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-7-331175 (JP, A) JP-A-7-196948 (JP, A) JP-A-6-87190 (JP, A) JP-A-4- 136022 (JP, A) JP-A-6-207023 (JP, A) JP-A-63-238125 (JP, A) JP-A-64-26693 (JP, A) (58) Fields investigated (Int. ⁶ , DB name) C09D 163/00-163/10 C09D 183/05 C09D 4/00 C08G 59/14 C08G 77/38

Claims (2)

(57) [Claims] 1. An addition reaction product of (A) a SiH group-containing organopolysiloxane and an alkenyl group-containing epoxy resin in an amount of 1 to 99 parts by weight (B) a vinyl ether compound in an amount of 99 to 1 part by weight (C) a photocationic initiator 0.01 UV curable protective coating composition comprising 0.1 to 40 parts by weight of (D) a photo-radical initiator. 2. The ultraviolet curable protective coating composition according to claim 1, wherein the alkenyl group-containing epoxy resin is an alkenyl group-containing epoxidized phenol novolak epoxy resin and / or an alkenyl group-containing epoxidized cresol novolak epoxy resin. .