JP2001348482A - Radiation-curable silicone-containing releasable composition and release film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a releasable composition which excels in photocurability and can be cured by irradiation with active energy rays such as light, electron rays, and x-rays in a short period of time, and further is advantageous in the total cost aspect due to its easy preparation, and furthermore can give a cured film usable in a release paper, a release film and the like. SOLUTION: The radiation-curable silicone-containing releasable composition comprises (A) a liquid cationically polymerizable silicone compound, (B) a photocationic polymerization initiator having an onium salt structure, and (C) a sensitizer having a solubility at 25 deg.C of >=0.1 pt.wt. based on 100 pts.wt. silicone compound of component (A).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radiation-curable silicone-containing release composition having excellent photocurability and a release film.

[0002]

2. Description of the Related Art Conventionally, radiation-curable silicone-containing release compositions have been used in the production of release films (release papers). In this case, various photoinitiators have been proposed and used, but are disclosed in JP-A-50-151997 and JP-A-50-1997.
JP-A-158680 and JP-A-50-151996 describe that an onium salt compound can be used as a photoinitiator for curing a cationically polymerizable compound such as an epoxy compound by radiation such as light, electron beam and X-ray. Have been. However, many of these onium salt compounds are highly toxic and those that are hardly compatible with various monomers.
It is known that compatibility with cationically polymerizable silicone compounds such as epoxy silicone is extremely low. In order to improve the compatibility of these onium salts, a long-chain alkyl group may be introduced into the onium salt itself or disclosed in JP-A-1-29742.
In JP-A No. 1 (KOKAI), improvement is made by introducing an aromatic ring into epoxy silicone.

[0003] However, since the above-mentioned onium salt-based photoinitiator is often expensive, a case where a sensitizer is used in combination is often seen. It is known that a polycyclic aromatic compound such as a naphthalene compound or an anthracene compound is effective as a sensitizer used in combination with a photoinitiator. However, since they have a rigid structure, applicable monomers and oligomers are limited in terms of compatibility, and the solubility in silicone oil such as epoxy silicone is particularly low.

[0004] JP-A-11-269107, JP-A-11-279213, JP-A-11-322900
In order to improve the compatibility of a photoinitiator and a sensitizer, Japanese Patent Application Publication No. H11-163171 discloses a method of chemically binding any or all of a cationically polymerizable compound, a photoinitiator, and a sensitizer to form a photopolymerizable composition. Although it is described that it is used as a product, the compounding amount of each component cannot be freely changed, and an extra reaction step is required, which is disadvantageous in cost.

[0005] The present invention has been made in view of the above circumstances,
An object of the present invention is to provide a radiation-curable silicone-containing release composition and a release film that are sensitive to active energy rays such as light, electron beams, and X-rays and can be cured in a short time.

[0006]

Means for Solving the Problems and Embodiments of the Invention The present inventors have conducted intensive studies in order to achieve the above object, and as a result, have shown good solubility in a cationically polymerizable silicone compound as a sensitizer. By using compounds, light,
It can be cured in a short time by irradiation with an active energy ray such as an electron beam or an X-ray. Even if such a sensitizer is blended, no influence on the peeling performance is observed, and the composition has good peeling performance, and It has been found that a radiation-curable silicone-containing release composition that can be easily adjusted is obtained, and the present invention has been accomplished.

Accordingly, the present invention provides (A) a liquid cationically polymerizable silicone compound, (B) a photocationic polymerization initiator having an onium salt structure, and (C) 100 parts by weight of the silicone compound (A). A radiation-curable silicone-containing release composition comprising a sensitizer having a solubility of 0.1 part by weight or more at 25 ° C., and a cured film of the release composition formed on a substrate. To provide a coated release film. In this case, as the component (A), the following formula (R ¹ ) _m (R ² ) _n SiO _{(4-mn) / 2} (wherein R ¹ is a group having no cationically polymerizable group, A substituted or unsubstituted monovalent hydrocarbon group which may be different, R ² is a monovalent hydrocarbon group having a cationically polymerizable group which may be the same or different from each other,
m and n are each an integer of 0 to 3, and m + n = 0 to 3
Is an integer. ) Having at least two R ² in one molecule and having an average number of silicon atoms of 10 to 10000, of which ² to 40% of the total number of silicon atoms having R ² is It is preferably an organopolysiloxane, and in the above formula, R ²
Is preferably a group containing an epoxy group, a group containing an oxetanyl group, or a group containing a vinyl ether group. Further, the component (B) is preferably a diaryliodonium salt derivative or a triarylsulfonium salt derivative.

Hereinafter, the present invention will be described in more detail.
The releasable composition of the present invention comprises (A) a cationically polymerizable silicone compound, (B) a photocationic polymerization initiator having an onium salt structure, and (C) 100 parts by weight of the cationically polymerizable silicone compound. A sensitizer that dissolves in a weight part or more is included as an essential element.

Here, the cationically polymerizable silicone compound as the component (A) is a base polymer as a main component for forming a peelable composition, and is an organopolysiloxane having at least two cation-polymerizable groups in one molecule. And the following formula: (R ¹ ) _m (R ² ) _n SiO _{(4-mn) / 2} (wherein, R ¹ is a group having no cationically polymerizable group and may be the same or different from each other. Or an unsubstituted monovalent hydrocarbon group, R ² is a monovalent hydrocarbon group having a cationically polymerizable group which may be the same or different from each other,
m and n are each an integer of 0 to 3, and m + n = 0 to 3
Is an integer. Consists constituent units represented by), containing as having at least two R ^2, i.e. the unit is used in which n is 1, 2 or 3 having at least two R ² are in one molecule in the molecule The organopolysiloxane is preferably

In this case, the structure may be linear or branched, or may have a wholly or partially cyclic structure.

R ¹ is a group bonded to a silicon atom and having no cationically polymerizable group, and is a substituted or unsubstituted monovalent hydrocarbon group which may be the same as or different from each other;
Examples thereof include a linear or branched alkyl group such as ethyl, propyl, and butyl, an alkenyl group such as vinyl and allyl, and an aryl group such as phenyl and tolyl. Examples thereof include those substituted by atoms or groups, for example, substituted hydrocarbon groups such as chloromethyl, 3-chloropropyl, and 3,3,3-trifluoropropyl groups. Of these, since the methyl group giving the synthesis is easy, and good release properties, 85 of all the R ¹
Preferably, at least mol% is a methyl group, and practically it is particularly preferable that all of R ¹ are methyl groups. Part of R ¹ may be a hydrogen atom, a hydroxyl group, or an alkoxy group having 1 to 4 carbon atoms such as methoxy, ethoxy, and propoxy. These functional groups can be used to react with another functional group to introduce a new function or to change the molecular structure.

R ² is a monovalent hydrocarbon group having a cationically polymerizable group which may be the same or different. As the cationic polymerizable group, a 3,4-epoxybutyl group,
A group containing an epoxy group such as a glycidyloxypropyl group and a 2- (3,4-epoxycyclohexyl) ethyl group; a 3-ethyl-3-oxetanylethoxy group;
A group containing an oxetanyl group such as (3-ethyl-3-oxetanylethoxy) propyl group, a vinyl ether group such as a 2-vinyloxyethyl group, a 3-vinyloxypropyl group, a 2-vinyloxyethoxy group, or a 4-vinyloxybutoxy group; And a group having a polymerizable internal olefin such as a 2-butenyloxy group and an allenyloxy group. Other examples include groups containing a cyclic siloxane such as a 2- (pentamethylcyclotrisiloxanyl) ethyl group and a 2- (pentamethylcyclotrisiloxanyl) ethoxy group.

M and n in the siloxane unit are each 0 to
3, and m + n = 0 to 3. In order to achieve both good releasability and mechanical strength, it is preferable to have a linear siloxane unit in which m = 2 and n = 0 in the entire siloxane unit. Also, by introducing a unit having m = 1 and n = 0 to have a branched structure, it is often effective to control curability and viscosity.

The proportion of the siloxane unit having R ² is preferably from 2 to 40 mol% based on all siloxane units. 2
If it is less than mol%, the curability decreases, and if it exceeds 40 mol%, the releasability is low, and unreacted residual groups during curing may adversely affect the pressure-sensitive adhesive. More preferably 5-
25 mol%.

(A) comprising such a siloxane unit
The number of silicon atoms of the component is 10 to 10,000 on average, preferably 10 to 500. If it is less than 10, a cured film cannot be obtained, and if it exceeds 10,000, there is a problem in coatability.

The viscosity of the component (A) at 25 ° C. is 20
It is preferably from 500 to 500,000 mPa · s, and more preferably from 20 to 100,000 mPa · s. 20mPa ・
If it is less than s, cissing may occur on the coated surface, and 500
If it exceeds 000 mPa · s, it becomes difficult to perform coating with a current coating machine.

Among the above-mentioned cationically polymerizable silicone compounds, epoxy-modified, vinyl ether-modified, and oxetane-modified silicone compounds are preferred.

[0018] cationic photopolymerization initiator having a component (B) an onium salt structure contained in the present invention is represented by the following general formula _{^{(R 3) x E + ·}} Y - ( wherein, R ³ is either the same or different Represents an optionally substituted monovalent group selected from an aromatic carbocyclic group and an aromatic heterocyclic group in which an aromatic ring carbon atom is directly bonded to E, wherein E is I, S, Represents a central element selected from Se and P, and Y ⁻ represents BF ₄ ⁻ , PF ₆ ⁻ , AsF ₆ ⁻ , Sb
Represents an abasic and non-nucleophilic anion selected from F ₆ ⁻ , ClO ₄ ⁻ , HSO ₄ ⁻ and B (C ₆ F ₅ ) ₄ ⁻ , and x is 2, S or Se when E is I 3 for P and 4 for P)
Are preferred.

The above aromatic carbocyclic groups include phenyl
And monovalent aromatic carbocyclic groups such as naphthyl,
, Ethyl, propyl, butyl, octyl, decyl, do
Alkyl groups such as decyl, methoxy, ethoxy, pro
Alkoxy group such as oxy group, chlorine atom, bromine atom
Halogen atoms, cyano groups, mercapto, thiol, etc.
Group selected from sulfur-containing groups such as phenyl
A substituted monovalent aromatic carbocyclic group is exemplified. Special
In addition, E is preferably I or S because of its high reactivity, and Y is preferably ^-age
PF₆ ^-, SbF₆ ^-, B (C₆F_Five)_Four ^-Is preferred. Ma
R^ThreeIs good solubility in silicone?
An alkyl group having 8 to 20 carbon atoms or 1 to 1 carbon atoms
0 is an aromatic carbocyclic group substituted by an alkoxy group
Is preferred.

Among the above initiators, diaryl iodonium salt derivatives and triarylsulfonium salt derivatives are preferred.

The compounding amount of the component (B) may be an effective amount as a photoinitiator, and is not particularly limited. However, from the viewpoint of curing speed and economy, 100 parts by weight of the component (A) is used. On the other hand, 0.3 to 5 parts by weight is preferable.

The sensitizer of the component (C) used in the present invention has a solubility of 0.1 part by weight or more with respect to 100 parts by weight of the liquid cationically polymerizable silicone compound at 25 ° C. Yes, any sensitizer compatible with the cationically polymerizable silicone may be used.However, when used as a release paper or release film, there is a problem of coloring, so a dye such as benzoflavin is used. Can not. For example, when the onium salt compound is an iodonium salt compound or the like, known sensitizers such as 1-naphthol and 2-
Naphthalene derivatives such as naphthol, 1-methoxynaphthalene and 1,4-dihydroxynaphthalene, anthracene derivatives such as 2-ethylanthracene and 9,10-dimethoxyanthracene, 9-hydroxyphenanthrene, 9
Phenanthrene derivatives such as -methoxyphenanthrene have low solubility in silicone and do not show a sufficient sensitizing effect. When about 0.1 parts by weight of 2-ethyl-9,10 dimethoxyanthracene and 9,10-dimethoxyphenanthrene are mixed with 100 parts by weight of the cation polymerizable silicone, they dissolve when heated, but become turbid at low temperatures. Or occur.

The most preferably used sensitizer is PST-06 manufactured by Nippon Kayaku Co., Ltd. When about 0.1 to 1 part by weight of PST-06 manufactured by Nippon Kayaku Co., Ltd. is mixed with 100 parts by weight of the cationically polymerizable silicone, it dissolves without heating and exhibits a remarkable sensitizing effect. In addition, the addition does not impair the inherent releasability of silicone.

The amount of addition is determined from the balance between economy and effect.
With respect to 100 parts by weight of the cation polymerizable silicone, 0.1 parts by weight.
1 to 0.5 parts by weight is preferred. In addition, since PST-06 has excellent solubility and dispersibility even in onium salts,
For example, PST-06 for 100 parts by weight of onium salt
10 to 50 parts by weight can be mixed and dissolved in advance, and there is also a great advantage that the degree of freedom of the product supply form is high.

The peelable composition obtained according to the present invention may contain an epoxy diluent, a vinyl ether diluent, an adhesion improver to a substrate, a leveling agent, an antistatic agent, an antifoaming agent, a pigment, if necessary. Alternatively, other types of organopolysiloxanes may be added, or they may be diluted with an organic solvent before use.

The composition of the present invention is easily cured by irradiation with ultraviolet light for a short time, and its cured film has a releasing property, so that it can be used as a releasing agent for an adhesive.

The release film (release paper) of the present invention is obtained by forming a cured film of the above-mentioned release composition on a substrate.

In this case, examples of the base material include paper base materials such as glassine paper, kraft paper and clay-coated paper, laminated paper such as polyethylene-laminated high-quality paper and polyethylene-laminated kraft paper, polyester, polypropylene, polyethylene, polyvinyl chloride, and the like. Metal foils such as aluminum, such as plastic films and sheets obtained from synthetic resins such as polytetrafluoroethylene and polyimide.

For coating the composition of the present invention on 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 is 0.1 to 20 g / m
² Tosureba well, the coating is readily cured by irradiating ultraviolet rays, radiation such as an electron beam. As a light source for photocuring the composition of the present invention, a low-pressure mercury lamp, a medium-pressure mercury lamp, a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, a metal halide lamp, a xenon lamp, a carbon arc lamp, and the like are used. Further, it can be easily cured by a laser beam such as a semiconductor laser, an argon laser, a He-Cd laser, or an ionizing radiation such as an α-ray, a β-ray, a γ-ray, a neutron beam, an X-ray, and an accelerating electron beam. . When a high-pressure mercury lamp (80 W / cm) is used to cure the above coating film, 5 to 2
Irradiation may be performed from a distance of 0 cm for 0.01 to 10 seconds.

[0030]

The strippable composition of the present invention is excellent in photocurability and can be cured in a short time by irradiation with active energy rays such as light, electron beam, X-ray and the like. Further, since the preparation of the composition is easy, it is advantageous in terms of total cost. The cured film obtained by the present composition can be used for a release paper, a release film or the like.

[0031]

EXAMPLES The present invention will be described below in detail with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples.

Examples 1 to 5 The viscosity at 25 ° C. represented by the following formula (1) was 150 mPa · s and the epoxy equivalent was 1
For 100 parts by weight of 200 epoxy-modified silicone,
PST-06 manufactured by Nippon Kayaku Co., Ltd. as a sensitizer, and an iodonium salt represented by the following formula (2) as a photo-cationic polymerization agent were dissolved in the amounts shown in Tables 1 and 2, respectively, and contained radiation-curable silicone. A peelable composition was obtained. (Me ₃ SiO _1/2 ) _0.067 (MeESiO) _0.099 (Me ₂ SiO) _0.833 (MeSio _3/2 ) _0.001 (1) (where Me is a methyl group and E is (3,4-epoxycyclohexyl) ) represents an ethyl _{group) (C 10-14 -C 6 H 4} ) I + · SbF 6 -. ··· (2) Next, to evaluate the performance of the release composition in the following manner.

(Evaluation 1) The peelable composition obtained above.
56 g was placed in a flat aluminum petri dish having a diameter of 6 cm, and cured by irradiating ultraviolet rays from a distance of 30 cm with two high-pressure mercury lamps (80 W / cm). The irradiation time was changed, and the state of curing was judged by finger touch. The judgment was made in five stages, 5: completely cured, 4: almost completely cured, 3: surface cured, 2: uncured part on the surface, 1: whole uncured. The results are also shown in Table 1.

(Evaluation 2) The release composition obtained above was
It was applied to a polyethylene laminated paper at 0.7 g / m ² using a transfer printing machine, and a high-pressure mercury lamp (80 W /
cm) and cured by irradiating ultraviolet rays from a distance of 20 cm. After varying the irradiation time, the cured film was rubbed back and forth 10 times with an index finger, and then red magic ink (registered trademark) was applied to observe the surface condition. Judgment is performed in five steps. 5: The whole surface is repelled with magic ink. 4: The magic ink is slightly applied to the rubbed portion. 3: The magic ink is applied to the rubbed portion. 2: The magic ink is applied. 〜Release film falls off. 1: Release film falls off. The results are also shown in Table 2.

(Evaluation 3) The releasable composition obtained on the peeling force was applied to a polyethylene laminated paper at 0.7 g / m ² using a transfer type printing machine, and a high pressure mercury lamp (80 W / cm) was applied. ) Curing was performed by irradiating ultraviolet rays from a distance of 13 cm with two lamps. Then 25 ° C
Aging for 20 hours, and the cured film surface is Tesa7
475 tape (25 mm width) was stuck. 2 at 50 ° C
After aging for 0 hour, the force required to peel the tape after the aging by pulling the tape at 180 ° C. at a peeling speed of 0.3 m / min using a tensile tester (N / 25)
mm), and this value was taken as the peeling force. Table 2 shows the results.

(Evaluation 4) Residual Adhesion Rate In the same manner as in the case of the peeling force, the peelable composition was applied to a polyethylene laminated paper at 0.7 g / m ² by using a transfer printing machine, and a high pressure mercury lamp was used. (80 W / cm) Curing was performed by irradiating ultraviolet rays from a distance of 13 cm with two lamps. After that, it was aged and Nitto No. 31B
Attach tape [Nitto Denko Corporation product name], 20g /
After applying a load of ² cm ² and heating at 70 ° C. for 20 hours, the tape was peeled off and affixed to a stainless steel plate, and then the force (N / 25 mm) required to peel off the treated tape and peel it off from the stainless steel plate ) Was measured, and the percentage of the force required to peel off the untreated standard tape was defined as the residual adhesion ratio. Table 2 shows the results.

COMPARATIVE EXAMPLE 1 0.5 parts by weight of 2-ethylanthracene and 1 part by weight of an iodonium salt of the formula (2) were mixed with 100 parts by weight of the epoxy-modified silicone used in the examples. , But most of the 2-ethylanthracene remained undissolved.

Comparative Example 2 2-Ethyl-9, 100 parts by weight of the epoxy-modified silicone used in the Examples was used.
When 0.5 part by weight of 10-dimethoxyanthracene and 1 part by weight of the iodonium salt of the formula (2) were mixed and heated to 50 ° C., they were once dissolved but turned cloudy when the temperature was returned to room temperature.

Comparative Example 3 A peelable composition was prepared by mixing 1 part by weight of the iodonium salt of the formula (2) with 100 parts by weight of the epoxy-modified silicone used in the example. evaluated. The results are also shown in Tables 1 and 2.

[0040]

[Table 1]

[0041]

[Table 2]

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) // C08L 23:04 C08L 23:04 F term (Reference) 4F006 AA12 AB39 BA13 CA07 4F100 AA05 AK52B AT00A BA02 BA07 GB90 JB14 JB14B 4J002 CP121 CP131 CP141 EA067 EB116 ED017 EJ017 EV296 FD206 FD207 GT00 4J035 BA04 CA112 CA142 GB02 LB10

Claims (5)

[Claims] 1. (A) a liquid cationically polymerizable silicone compound, (B) a cationic photopolymerization initiator having an onium salt structure, and (C) a silicone compound 10 of the component (A).
A radiation-curable silicone-containing release composition comprising a sensitizer having a solubility of 0.1 part by weight or more at 25 ° C. based on 0 part by weight. 2. The method according to claim 1, wherein the silicone compound of the component (A) has the following formula (R ¹ ) _m (R ² ) _n SiO _{(4-mn) / 2 wherein} R ¹ is a group having no cationically polymerizable group. A substituted or unsubstituted monovalent hydrocarbon group which may be the same or different from each other, R ² is a monovalent hydrocarbon group having a cationically polymerizable group which may be the same or different from each other,
m and n are each an integer of 0 to 3, and m + n = 0 to 3
Is an integer. ) Having at least two R ² in one molecule and having an average number of silicon atoms of 10 to 10000, of which ² to 40% of the total number of silicon atoms having R ² is The strippable composition according to claim 1, which is an organopolysiloxane. 3. The strippable composition according to claim 1, wherein R ² is a group containing an epoxy group, a group containing an oxetanyl group, or a group containing a vinyl ether group. 4. The peelable composition according to claim 1, wherein the component (B) is a diaryliodonium salt derivative or a triarylsulfolium salt derivative. 5. A release film comprising a substrate and a cured film of the release composition according to claim 1 formed on the substrate.