JPH08134404A - UV curable protective coating composition - Google Patents

Abstract

(57) [Summary] (Modified) [Purpose] To provide a UV-curable protective coating composition which gives a high-hardness film excellent in curability, mold releasability, slipperiness, and adhesion to a substrate. [Structure] (A) Addition reaction product 1 of SiH group-containing organopolysiloxane and alkenyl group-containing epoxy resin
UV-curable protective coating agent comprising 99 parts by weight, (B) vinyl ether compound 99 to 1 part by weight, (C) photocation initiator 0.01 to 20 parts by weight, and (D) photoradical initiator 0.1 to 40 parts by weight Composition.

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 irradiation with ultraviolet rays for a short time. The composition of the present invention is useful as a protective coating agent, an antifouling coating agent, a coating agent for preventing paper sticking, a release agent, a release agent, a water / oil repellent agent, and the like.

[0002]

2. Description of the Related Art Conventionally, a releasable silicone coating agent is applied to a substrate such as plastic, glass or metal for the purpose of protective coating, antifouling coating, etc. to form a cured film layer having releasability. There was an occasion. However, such a cured coating layer may be inferior in adhesiveness to the substrate, or may be inferior in scratch resistance due to low hardness of the coating. On the other hand, a cured film of a silicone hard coating agent has poor releasability from adhesive tapes and adhesives, and oily or water-based stain components tend to adhere,
Sometimes it was hard to remove. In addition, these silicone coating agents are often diluted with an organic solvent and applied, and in this case, in order to form a coating film layer on a substrate, a method of removing the solvent by heating and baking is taken. However, in addition to the problem that a lot of organic solvent is discharged in this process and more heat energy is required to form the film, it cannot be applied to a substrate with poor heat resistance due to the influence of heating. There was an occasion.

Therefore, from the viewpoint of productivity improvement and energy saving, and in order to be applied to a base material having poor heat resistance, it is required to cure at a low temperature for a short time. In particular, the base material is deformed by heat. In consideration of prevention of the above, it is advantageous to form a cured film on the substrate by irradiating with ultraviolet rays. As a curable composition that can be cured by ultraviolet rays, a composition comprising an organopolysiloxane having an epoxy group and an onium salt photoinitiator is known (see JP-A-56-38350). This composition is said to have excellent releasability with an adhesive substance, but the adhesion to the substrate is insufficient, or good releasability cannot be obtained depending on the type of the adhesive substance, Since the surface of the cured film has no slipperiness, there is a drawback that workability is poor. In addition, there is an example in which a photocationically curable silicone composition is used for the production of an antifouling coating sheet (see JP-A-6-87190), but this has a problem that the cured film has a low hardness and scratch resistance.

[0004]

In view of the above-mentioned circumstances, the present invention has excellent curability, the formed film has excellent releasability, slipperiness, high hardness and excellent scratch resistance. The present invention is intended to provide a UV-curable protective coating composition having good adhesion to a substrate, especially to plastic.

[0005]

The UV-curable protective coating agent composition of the present invention solves the above-mentioned problems. (A) Addition reaction of SiH group-containing organopolysiloxane and alkenyl group-containing epoxy resin 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 Is. The present invention will be described in more detail below.

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 for its production is linear, branched or cyclic. Any of them may be used, and one having at least two structural units (I) shown below in one molecule can be used. 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 ≦
It is 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, a butyl group, a cycloalkyl group such as a cyclohexyl group, or a phenyl group. , An aryl group such as a tolyl group, or a hydroxypropyl group obtained by substituting a part or all of hydrogen atoms bonded to carbon atoms of these groups with a hydroxyl group, a cyano group, a halogen atom or the like,
Cyanoethyl group, 3-chloropropyl group, 3,3,3-
Examples thereof include trifluoropropyl group. 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, other units include R ¹ ₃ SiO _1/2 unit, R ¹ ₂ SiO unit, R ¹ SiO _3/2 unit, and SiO ₂
Any one of the units may be contained alone or in combination of two or more. Examples of R ¹ include the same groups as R or alkoxy groups.

Specific examples of the SiH group-containing organopolysiloxane include 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 can be mentioned, and these can be used alone or in combination of two or more kinds.
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 preferable, and an alkenyl group-containing epoxidized phenol novolac resin is particularly preferable. Epoxidized cresol novolac epoxy resin is preferred. This alkenyl group-containing epoxy resin can be obtained by epoxidizing an alkenyl group-containing phenol resin with epichlorohydrin, or by 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) is obtained by subjecting the above-mentioned SiH group-containing organopolysiloxane and an alkenyl group-containing epoxy resin to an addition reaction in the presence of a platinum-based addition reaction catalyst. The weight ratio of the SiH group-containing organopolysiloxane to the alkenyl group-containing epoxy resin is 2/8.
~ 8/2 is desirable. The reaction conditions may be those normally used for addition reactions.

The component (B) is a vinyl ether compound, and by using this component, it is possible to improve the adhesion to the substrate and the curability. In addition, 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 an ester residue 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 degree of polymerization of 2 to 30, propylene glycol, polypropylene glycol having a degree of polymerization of 2 to 30, and 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-
Examples thereof include ethylhexanediol, glycerin, and trimethylolpropane. 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 = CH-O- (CH ₂ ) ₆ -O-CH = 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 which is the component (B) and the addition reaction product which is the component (A) is (A) component / (B) component = 1/99 to 99 / part by weight.
1, preferably 40/60 to 95/5.

The component (C) is a photocationic initiator, and among these, an onium salt photoinitiator is preferable. 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,
Examples thereof include monoaryldialkylsulfonium salts, triarylselenonium salts, tetraarylphosphonium salts and aryldiazonium salts. The amount of the photocationic initiator added is 100 in total of the components (A) and (B).
0.01 to 20 parts by weight, preferably 0.5 to
It should be 10 parts by weight. If this amount is less than 0.01 parts by weight, the curability will be insufficient, and if it is more than 20 parts by weight, the surface condition of the cured film will be adversely affected and the releasability of the cured film will be deteriorated.

The component (D) is a photoradical initiator, and 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. You can Among the photo-radical initiators, acetophenone-based photo-initiators are preferable, and those represented by the following formula can be exemplified.

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, or 6 to 6 carbon atoms
8 aryl groups or both R ⁶ are linked by a carbon-carbon bond and are bonded to the same carbon atom and have 4 to 5 carbon atoms, and R ⁷ is a hydroxyl group or a C 1 to 6 alkoxy group. as,

[0016]

[Chemical 4] And the like. The addition amount of this photo radical initiator is
0.1 per 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 this amount is less than 0.1 parts by weight, the curability will be insufficient, and if it is more than 40 parts by weight, the surface condition of the cured film will be adversely affected and the releasability of the cured film will be 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 further contains, if necessary, an epoxy diluent, an acrylate monomer, an acrylate oligomer, a sensitizer, an adhesion improver to a substrate, a leveling agent, an antistatic agent, an antifoaming agent, a pigment, etc. May be added, or when an organic solvent may be used, it may be diluted with the organic solvent before use.

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

To apply 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 irradiation with 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. 8 cm when a high pressure mercury lamp (80 W / cm) is used to cure the above coating film
Irradiate from the distance of 0.01 to 10 seconds.

[0020]

EXAMPLES Next, examples of the present invention will be described. Parts in the examples indicate parts by weight. In addition, the obtained coating agent composition was evaluated by the following methods. Peeling power: The coating composition was applied to a polyvinyl chloride sheet using a wire bar so that the solid content was 15 g / m ^2, and the cured film was irradiated by irradiating a high pressure mercury lamp of 80 W / cm from a distance of 8 cm. Formed. Polypropylene adhesive tape No. 835 (Sekisui Chemical Co., Ltd., 50
mm width) and aged at 25 ° C for 24 hours, then peel the sample tape at an angle of 180 ° using a tensile tester at a peeling speed of 0.3 m / min, and peeling is required. The force (g / 50 mm) was measured. Curing property: In the same manner as in the case of measuring the peeling force, 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. 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 measurement of peeling force. The surface of this cured film was rubbed strongly with a finger to check whether the film was removed. Magic ink repulsion: A cured film of the silicone composition was formed on the surface of the substrate in the same manner as in the measurement of peeling force. Magic ink was applied to the surface of this cured film, and after air-drying, it was wiped off with gauze and examined for the presence of residual ink.

Example 1 Average composition formula

Embedded image 30 parts of the addition reaction product of the SiH group-containing organopolysiloxane represented by and the alkenyl group-containing epoxy resin, 70 parts of the vinyl ether compounds exemplified above 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 the treatment liquid, the peeling force of the cured film, the adhesion, the repulsion of the magic ink, and the pencil hardness were measured. The results are shown in Table 1.

Example 2 Average composition formula

[Chemical 6] 40 parts of an addition reaction product of an SiH group-containing organopolysiloxane represented by and an alkenyl group-containing epoxy resin, 60 parts of the vinyl ether compounds exemplified above marked with * 1, used in Example 1 Photocationic initiator
A treatment liquid was prepared by mixing 1.5 parts of the photoradical initiator used in Example 1 with 5 parts of the photoradical initiator. The curability of the treatment liquid, the peeling force of the cured film, the adhesion, the repulsion of the magic ink, and the pencil hardness were measured. The results are shown in Table 1.

Example 3 Average composition formula

[Chemical 7] 30 parts of the addition reaction product of the SiH group-containing organopolysiloxane represented by the formula and the alkenyl group-containing epoxy resin, 70 parts of the vinyl ether compound used in Example 1, 1.5 parts of the photocationic initiator used in Example 1 A treatment liquid was prepared by mixing 5 parts of the photo-radical initiator used in Example 1. The curability of the treatment liquid, the peeling force of the cured film, the adhesion, the repulsion of the magic ink, and the pencil hardness were measured. The results are shown in Table 1.

Comparative Example 1 Addition reaction product of the SiH group-containing organopolysiloxane used in Example 1 and the alkenyl group-containing epoxy resin 30
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, the repulsion of the magic ink, and the pencil hardness were measured. The results are shown in Table 1.

Comparative Example 2 A treatment liquid was prepared by mixing 100 parts of an ultraviolet curable epoxy resin KRM-2110 [trade name of Asahi Denka Kogyo KK] and 2 parts of an iodonium salt photoinitiator. The curability of this treatment liquid,
The peel strength, adhesion, magic ink repulsion and pencil hardness of the cured film were measured. The results are shown in Table 1.

[0026]

[Table 1]

[0027]

The UV-curable protective coating composition of the present invention is excellent in curability, the formed film has excellent releasability, has slipperiness, high hardness and excellent scratch resistance. Since it has good adhesion to materials, especially plastics, it is extremely advantageous in practical use.

Claims (2)

[Claims] 1. An addition reaction product of (A) an SiH group-containing organopolysiloxane and an alkenyl group-containing epoxy resin 1 to 99 parts by weight (B) a vinyl ether compound 99 to 1 parts by weight (C) a photocationic initiator 0.01 ~ 20 parts by weight (D) UV curable protective coating composition comprising 0.1 to 40 parts by weight of a photoradical 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 novolac epoxy resin and / or an alkenyl group-containing epoxidized cresol novolac epoxy resin. .