JPH0687190A - Nonadhesive stain-resistant sheet - Google Patents

Abstract

PURPOSE:To obtain a nonadhesive stain-resistant sheet being excellent in setup and release characteristics by a method wherein a composition constituted of an epoxy denatured silicone prepolymer containing one or more cation- polymerizable epoxy groups in a molecule and of initiators is applied by coating on a plastic sheet and set by radiation. CONSTITUTION:A composition constituted of three constituents, i.e., an epoxy denatured silicone prepolymer containing one or more cation-polymerizable epoxy groups in a molecule, a photo-cationic polymerization initiator and a photo-radical polymerization initiator, is applied by coating at least on one surface of a plastic sheet. The sheet thus prepared is set by irradiation with radiation and thereby a nonadhesive stain-resistant sheet is obtained. Compared with a usual sheet prepared by using a silicone release agent of a photo-radical polymerization type or a heat setting type, the sheet thus prepared does not impair a release resistance, has excellent setup characteristics and does not have surface transfer properties nearly at all. Since the epoxy denatured silicone prepolymer is used, besides, this sheet shows little setting shrinkage and has excellent adhesion to a base material.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-adhesive, antifouling sheet, and more specifically, it can be cured by irradiation with low illuminance radiation, and has excellent durability and releasability in addition to adhesion with a plastic sheet. The present invention relates to a non-adhesive, antifouling sheet which is excellent and has little migration of low molecular weight silicone oil to the surface.

[0002]

2. Description of the Related Art Non-adhesive, anti-fouling sheets are conventionally formed on stretched polypropylene resin sheets, polyethylene terephthalate resin sheets, polyethylene resin sheets, polyvinyl chloride resin, and other plastic sheets by heating and irradiating radiation. Since these sheets provide non-adhesion and anti-fouling properties, they are able to exert their performance simply by being attached to the surface of the base material to which they are required to have non-adhesion and anti-fouling properties. It's starting.

As these non-adhesive and antifouling sheets, heat-curing type plastic sheets such as heat-curing type silicone resin using a platinum compound as a curing catalyst have been used. Many of them have poor mechanical stability, and many of them are subject to dimensional changes and deformations due to the heat history during processing.Therefore, it is necessary to be very careful when forming a non-adhesive coating film by heating. However, there is also a drawback that the cost of heating and heating is high.

In order to improve this, a non-adhesive, antifouling sheet mainly made of a photo-radical-curable silicone resin has been developed, which is prepared by curing a silicone resin coated on a plastic sheet with radiation such as ultraviolet rays. Although it forms a non-adhesive coating film, this sheet is slightly heated at the time of radiation curing, but it is not the ratio of the above-mentioned heat-curing type sheet, and therefore it is not necessary to consider deformation due to heat, etc. Moreover, there are advantages such as reduction of utility costs.

[0005]

However, since these photo-radical-curable silicone resins have a large shrinkage due to curing, they have poor adhesion to the plastic sheet as the base material and may fall off in some cases.

In order to improve the adhesion, corona discharge treatment and surface modification by ultraviolet irradiation are generally performed, and a primer layer such as a silane coupling agent is provided as a base of the non-adhesive coating film. The method is JP-A-62-227.
Although disclosed in Japanese Patent Laid-Open No. 469 and Japanese Patent Laid-Open No. 64-5838, all of them have a large number of working steps, and thus have problems in cost and process control.

Further, a heat-curable silicone resin using a platinum compound as a curing catalyst and a photo-radical-curable silicone resin easily cause curing inhibition under the influence of a plasticizer as an additive depending on the type of plastic, In some cases, a cured product may not be obtained under the above curing conditions, or the adhesiveness to the plastic sheet as the base material may be significantly deteriorated after curing, or in some cases a cured product may not be obtained at all. In particular, the curing performance was not sufficiently exhibited on the soft vinyl chloride sheet.

Further, in the conventional photo-radical curable silicone resin for releasing, a low molecular weight unreactive silicone oil is often added or left in order to improve the releasing property. After the film is formed, it may be transferred to the surface and dust or the like may be attached to the surface to impair the appearance, or it may be transferred to another area and contaminated.

[0009]

On the other hand, in order to improve the adhesion to a plastic sheet as a base material, the inventors of the present invention used an epoxy-modified silicone resin having a small shrinkage at the time of curing, and plasticized it. In order to eliminate the effect of curing inhibition by agents and the like, the above problems could be overcome by using a cationic curing type curing mechanism.

Therefore, in the present invention, on at least one surface of the plastic sheet, (a) an epoxy-modified silicone prepolymer containing at least one cationically polymerizable epoxy group in the molecule, (b) a photocationic polymerization initiator, and (c). Applying a composition consisting of three components of a photo radical polymerization initiator,
It proposes a non-adhesive, antifouling sheet obtained by curing by irradiation with radiation.

Examples of the plastic sheet to which the present invention can be applied include thermosetting resin sheets such as epoxy resin, unsaturated polyester and polyurethane, and thermoplastic resin sheets such as vinyl chloride resin, polyethylene and saturated polyester.

As additives to these resins, plasticizers,
A stabilizer, a colorant, an ultraviolet absorber, etc. may be contained, and it may be transparent, semi-transparent, or opaque, and a sheet on which figures, characters, patterns, etc. are printed in advance can be used.

The epoxy-modified silicone prepolymer as the component (a) used in the present invention is an organopolysiloxane containing at least one cationically polymerizable epoxy group in the molecule, and specifically, an organopolysiloxane of the following structural formula: Polysiloxanes can be enumerated.

[0014]

[Chemical 5]

These may, of course, be used alone or in combination of two or more, and may be diluted with an organic solvent such as benzene, toluene, xylene or the like for adjusting the viscosity. Considering the effect on
It is desirable to use -100%, preferably 100% non-volatile content.

Although it is generally said that photo-cationic polymerization has a slower curing rate than photo-radical polymerization, the epoxy-modified silicone prepolymer used in the present invention is (b)
As the photocationic polymerization initiator of the component, a diallyliodonium salt of the following general formula (I), and as the photoradical polymerization initiator of the component (c), one or two of the following general formulas (II), (III) and (IV)
By using at least one kind, the curing rate can be made higher than that of the photo-radical polymerization type silicone without adversely affecting the releasability, adhesion, surface transferability and the like of the cured coating film.

[0017]

[Chemical 1]

(Wherein R is an alkyl group, X is BF ₄ , P
(One kind selected from the group consisting of F ₆ , SbF ₆ , and AsF ₆ is shown)

[0019]

[Chemical 2]

[0020]

[Chemical 3]

[0021]

[Chemical 4]

(In the formula, R ¹ is a hydrogen atom or an alkyl group having 3 or less carbon atoms, and R ² and R ³ are methyl groups or ethyl groups)

The photocationic polymerization initiator represented by the above general formula (I) easily generates a Lewis acid upon irradiation with radiation such as ultraviolet rays to polymerize the epoxy-modified silicone prepolymer. .

Further, the photoradical polymerization initiator represented by the general formulas (II), (III) and (IV), which is another component according to the present invention, specifically includes the following compounds. Representative structural formulas of these compounds that can be obtained are shown below.

The compounds of the general formula (II) include 2-hydroxy-2-methyl-1-phenylpropan-1-one (a), 2-hydroxy-2-methyl-1-phenylbutan-1-one, 2-Ethyl-2-hydroxy-1-phenylbutan-1-one (b), 1- (4-methylphenyl) -2-hydroxy-2-methylpropan-1-one (c), 1- (4- Methylphenyl) -2-hydroxy-2-methylbutan-1-one, 1- (4-methylphenyl) -2-ethyl-2-hydroxybutan-1-one, 1- (4-ethylphenyl) -2-hydroxy -2
-Methylpropan-1-one, 1- (4-ethylphenyl) -2-hydroxy-2-methylbutan-1-one (d), 1- (4-ethylphenyl) -2-ethyl-2
-Hydroxybutan-1-one, 1- (4-propylphenyl) -2-hydroxy-2-methylpropan-1-
On, 1- (4-propylphenyl) -2-hydroxy-2-methylbutan-1-one, 1- (4-propylphenyl) -2-ethyl-2-hydroxybutan-1-one, 1- (4- Isopropylphenyl) -2-hydroxy-2-methylpropan-1-one (e), 1- (4-
Isopropylphenyl) -2-hydroxy-2-methylbutan-1-one, 1- (4-isopropylphenyl)
2-ethyl-2-hydroxybutan-1-one and the like can be listed.

Examples of the compound of the general formula (III) include 1-hydroxycyclohexyl-phenylmethanone (f) and 1-
Hydroxycyclohexyl-4-methylphenylmethanone (g), 4-ethylphenyl-1-hydroxycyclohexylmethanone, 1-hydroxycyclohexyl-4
-Isopropylphenylmethanone and the like can be listed.

Examples of the compound of the general formula (IV) include 2,2-dimethoxy-1,2-diphenylethanone (h), 2-ethoxy-2-methoxy-1,2-diphenylethanone,
2,2-diethoxy-1,2-diphenylethanone (i) and the like can be listed.

[0028]

[Chemical 6]

These compounds may be used alone or, of course, one kind or a combination of two or more kinds.

The thickness of the plastic sheet used in the present invention is not particularly limited, but from the viewpoint of workability, handleability, workability, etc., it is about 0.01 to 30 mm, preferably 0.05 to 10 mm.

The amount of the cationic photopolymerization initiator which is the component (b) in the present invention may be 0.1 to 10 parts by weight, preferably 0.1 to 10 parts by weight, relative to 100 parts by weight of the epoxy modified silicone prepolymer which is the component (a). 5 parts by weight, and the addition amount of the photoradical polymerization initiator which is the component (c) to 100 parts by weight of the photocationic polymerization initiator which is the component (b) at this time may be 5 to 1000 parts by weight. It is preferably 10 to 800 parts by weight.

Furthermore, at this time, the sum of the photocationic polymerization initiator which is the component (b) and the photoradical polymerization initiator which is the component (c) is 100 parts by weight of the epoxy-modified silicone prepolymer which is the component (a). It is preferably 10 parts by weight or less.

The coating film thickness after curing the silicone layer comprising the components (a), (b) and (c) is
There is no particular problem as long as the anti-adhesion and antifouling effects can be exhibited, but the range is preferably 0.5 to 50 μm.
When the film thickness is less than this range, it is difficult to exert the original non-adhesive and antifouling effect, and when the film thickness is more than this range, the adhesive force and cohesive force of silicone are reduced.

The non-adhesive, antifouling sheet according to the present invention has excellent releasability, and therefore, it is not necessary to include a low-molecular weight unreacted silicone oil for improving the releasability, and therefore the curing is not necessary. There is almost no surface migration afterwards.

[0035]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples, and all "parts" are hereinafter referred to as "parts by weight".

Example 1 A coating agent was prepared according to Table 1 below using the following samples as a photo-cationic polymerization type silicone which is an epoxy-modified silicone prepolymer, a photo-cationic polymerization initiator and a photo-radical initiator. , And each was diluted with the same weight of toluene. This was coated on a polyethylene terephthalate sheet using a No. 3 bar coater, dried with a solvent, and shown in Table 1 below.
A release coating film (non-adhesive, antifouling sheet) was prepared under the curing conditions of. An adhesive tape as shown below was attached to this sheet, and the peel resistance was measured after pressure bonding with a 5 Kgf rubber roller. The results are shown in Table 1 below.

(Samples of Examples) UV9300 (photo-cationic polymerization type silicone / manufactured by Toshiba Silicone) UV9310C (photo-cationic polymerization type initiator / manufactured by Toshiba Silicone) Darocur 1116 (photoradical polymerization initiator / Ciba Geigy) Darocur 1173 (photo-radical polymerization initiator / manufactured by Ciba-Geigy) Irgacure 184 (photo-radical polymerization initiator / manufactured by Ciba-Geigy) Irgacure 651 (photo-radical polymerization initiator / manufactured by Ciba-Geigy)

(Adhesive Tape) No. 51B (acrylic adhesive / manufactured by Nitto Denko) No. 525K (Rubber adhesive / Nitto Denko)

Comparative Example 1 Using the above sample and the photoradical polymerization type silicone, the heat curing type silicone, and the sample shown below as a curing catalyst,
A coating agent was prepared in the same manner as in Example 1 based on Table 1 below, and applied on a polyethylene terephthalate sheet in the same manner as in Example 1, and a release coating film (non-adhesive, Antifouling sheet) was created. The adhesive tape as shown above was attached to this sheet, and the peel resistance was measured after pressure bonding with a 5 Kgf rubber roller. The results are shown in Table 1 below. The blank in Table 1 is the peel resistance value of the polyethylene terephthalate sheet that has not been subjected to the non-adhesive treatment.

(Samples of Comparative Examples) KNS5100 (photo-radical polymerization type silicone / manufactured by Shin-Etsu Chemical Co., Ltd.) KNS5300 (photo-radical polymerization type silicone / manufactured by Shin-Etsu Chemical Co., Ltd.) KS847H (heat curing type silicone / manufactured by Shin-Etsu Chemical Co., Ltd.) LTC750A (heating) Curable Silicone / Toray Dow Corning Silicone SRX212 (Curing Catalyst / Toray Dow Corning Silicone)

[0041]

[Table 1]

As is clear from Table 1, it is possible to obtain a low peeling resistance value below the measurement limit of the measuring device for most of the sheets, and in the present invention, the peeling resistance value can be obtained even if a photo radical initiator is added. It has become clear that it will not have any adverse effects.

Example 2 Using the same sample as in Example 1, a coating agent was prepared according to Table 2 below. This was coated on a soft vinyl chloride sheet using a No. 3 bar coater, and a release coating film (non-adhesive, antifouling sheet) was prepared under the curing conditions shown in Table 2. This sheet is overlaid with polyethylene terephthalate sheet, 100Kgf / cm ²
It was left for 30 minutes in an atmosphere of 25 ° C. next,
The polyethylene terephthalate was peeled off, a line was drawn with a magic ink on the surface that was in contact with the non-adhesive, antifouling sheet, and the repellency was observed. The same experiment was performed on the comparative example based on Table 2.

The results are shown in Table 2 below. The symbols in the table were ◯ = no repellency. Δ = There was some repellency. × = There was a significant repellency. Are shown respectively.

[0045]

[Table 2]

As is clear from Table 2, the non-adhesive, antifouling sheet prepared by using the cationic photopolymerizable silicone has a smaller surface migration property than other sheets. It should be noted that the non-adhesive, antifouling sheet prepared by using the heat-curable silicone has a particularly remarkable surface migration property, suggesting that the soft vinyl chloride sheet as the base material inhibits the curing by the plasticizer.

Example 3 The ultraviolet curing type curing mechanism of Example 1 was used.
A coating material was prepared based on Table 3 below. This is No.3
Coating on a soft vinyl chloride sheet using a bar coater,
As shown in Table 3, 100 mJ / cm ² and 300 mJ / cm ² of cumulative light intensity was applied and the curability of the coating liquid was observed. The same experiment was performed on the comparative example based on Table 3.

The curability was evaluated by visually observing the surface of the sheet after ultraviolet irradiation and rubbing with a finger. The results are shown in Table 3. The symbol in the table is ◯ = completely cured. Δ = The coating film was partially peeled off when rubbed with a finger. X =
Most of the coating peeled off when rubbed with a finger. XX = Almost uncured and oily. Are shown respectively.

[0049]

[Table 3]

As is clear from Table 3, the non-adhesive, antifouling sheet according to the present invention can be sufficiently cured even with ultraviolet rays of very low illuminance.

[0051]

In summary, the non-adhesiveness according to the present invention,
The antifouling sheet does not impair the peeling resistance, has excellent curability, has almost no surface migration, and has an epoxy-modified silicone prepolymer, compared to the one using conventional photoradical polymerization type or heat curing type silicone release agents. Since it uses a polymer, it has a small curing shrinkage and excellent adhesion to the substrate.

Further, in the present invention, the above-mentioned various performances are not achieved even on the soft vinyl chloride sheet which is not cured even under the influence of the plasticizer added in the conventional silicone mold release agent, especially the heat-curable silicone mold release agent. Can be fully demonstrated.

Therefore, in the present invention, the heat resistance is improved by coating on the surface of a plastic which is conventionally weak against heat, and the non-adhesive, antifouling sheet according to the present invention is a transparent sheet or a sheet with a pattern. Processed into molded products, glass,
By sticking it on a pillar, a wall, a vertical wall, etc., not only the antifouling effect of these can be obtained, but also the effect of improving the texture and easiness of cleaning can be obtained.

Furthermore, by using the non-adhesive, anti-fouling sheet according to the present invention in a processing factory for foods, pastes, adhesives, etc., it is possible to improve hygiene, danger prevention and work efficiency in the workplace. Worth using.

Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location C09D 163/00 PJD 8830-4J 183/06 PMT 8319-4J

Claims (4)

[Claims] 1. A (a) cationically polymerizable epoxy group in a molecule is formed on at least one surface of a plastic sheet in an amount of 1 in the molecule.
A non-characterized product obtained by applying a composition comprising three components of the epoxy-modified silicone prepolymer (b) a photocationic polymerization initiator (c) and a photoradical polymerization initiator contained above and curing the composition by irradiation with radiation. Adhesive, antifouling sheet. 2. The non-adhesive, antifouling sheet according to claim 1, wherein the component (a) has a nonvolatile content of 20 to 100%. 3. The non-adhesive, antifouling sheet according to claim 1, wherein the component (b) is a diallyliodonium salt of the following general formula (I) which generates a Lewis acid upon irradiation with radiation. [Chemical 1] (In the formula, R is an alkyl group, X is BF ₄ , PF ₆ , SbF
₆ shows one kind selected from the group consisting of AsF ₆ ) 4. The component (c) is represented by the following general formulas (II) and (II
The non-adhesive, antifouling sheet according to claim 1, which is a photoradical polymerization initiator defined by one or more of I) and (IV). [Chemical 2] [Chemical 3] [Chemical 4] (In the formula, R ¹ is a hydrogen atom or an alkyl group having 3 or less carbon atoms, and R ² and R ³ are methyl groups or ethyl groups)