JPH0625602A - Curable silicone composition for release paper - Google Patents

Abstract

PURPOSE:To provide a curable silicon compsn. which gives a release paper suffering little change in release characteristics with a change in cure conditions (temp., rate of air blow). CONSTITUTION:This compsn. comprises 100 pts.wt. unsatd. organopolysiloxane having at least two unsatd. groups directly bonded to Si atoms in the molecule, 0.1-20 pts.wt. organosilicon compd. having at least three H atoms directly bonded to Si atoms in the molecule and having a wt. loss after heating at 105 deg.C for 3 hr of 1% or lower, a catalytic amt. of a platinum catalyst, and a catalytic activity regulator.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a curable silicone composition for release paper, and more particularly to a curable silicone composition for release paper, which gives a release paper with little difference in release characteristics caused by curing conditions such as temperature and air flow. Is.

[0002]

2. Description of the Related Art Conventionally, a silicone composition film is formed on the surface of a base material for the purpose of preventing adhesion and sticking between a paper base material such as paper, processed paper and plastic film and an adhesive substance. It has been performed to impart releasability to this, and this is generally called release paper.

Various methods are known for forming a film of a silicone composition on the surface of a base material, but recently, an organopolysiloxane containing an aliphatic unsaturated group and an organohydrogenpolysiloxane have been used. A method of forming a releasable film by subjecting a platinum-based compound as a catalyst to an addition reaction is widely used, and the silicone composition used here is called a heat cure type in which a film is formed by heating. However, depending on their properties, they are classified into a solvent type dissolved in an organic solvent such as toluene, an emulsion type emulsified, and a solventless type consisting only of silicone.

[0004]

However, in the above-mentioned conventionally known curable silicone composition for release paper, when the composition is applied to various papers, processed papers, substrates such as plastic films, and processed, However, there is a problem in that the release property of the release paper obtained changes because the amount of the cross-linking agent that comes out of the system varies depending on processing conditions such as temperature and air flow.

[0005]

SUMMARY OF THE INVENTION The present invention relates to a curable silicone composition for release paper which has solved the above disadvantages and problems, and it relates to the problem that A) a silicon atom is bonded to one molecule. 100 parts by weight of unsaturated-group-containing organopolysiloxane having at least two saturated groups, B) Weight loss rate after heating at 105 ° C for 3 hours having at least 3 hydrogen atoms bonded to silicon atoms in one molecule Is 1% or less, 0.1 to 20 parts by weight of an organic silicon compound, C) a catalytic amount of a platinum-based catalyst, and D) a control agent.

That is, the inventors of the present invention have conducted various studies to develop a curable silicone composition for release paper which can reduce the difference in release property caused by the difference in processing conditions. An organic silicon compound (organohydrogenpolysiloxane) having at least three hydrogen atoms bonded to silicon atoms in one molecule, which is used as a component, usually has an average molecular weight of several thousand or less, and is based on JIS K7117. Since the measured weight loss rate after heating at 105 ℃ for 3 hours is 2 to 15%,
It was found that when this is applied to a base material and processed, the release properties of the release paper obtained are changed because the amount of the cross-linking agent that comes out of the system changes depending on the processing conditions. Therefore, this is used here. Organosilicon compounds at 105 ° C
× If the weight loss rate after heating for 3 hours is 1% or less, the change in the release property of this release agent will be small, and it will be confirmed that it can be made substantially uniform. Completed the invention. This will be described in more detail below.

[0007]

The present invention relates to a curable silicone composition for release paper, which comprises A) 100 parts by weight of an unsaturated group-containing organopolysiloxane having at least two unsaturated groups bonded to a silicon atom in one molecule. , B) having at least three hydrogen atoms bonded to silicon atoms in one molecule, 105 ° C
× 0.1 to 20 parts by weight of an organic silicon compound having a weight loss rate of 1% or less after heating for 3 hours, C) a catalytic amount of a platinum-based catalyst,
D) It is characterized by comprising a control agent,
According to this, since the weight loss rate of component B) at 105 ° C x 3 hours is 1% or less, the change in the release characteristics of the release agent after processing is small, and therefore a product with stable release properties should be supplied. The advantage of being able to

The present invention relates to an addition reaction type curable silicone composition for release papers. The organopolysiloxane as the component A) constituting this composition is unsaturated with a silicon atom bonded in one molecule. It is assumed that it has at least two groups, and these unsaturated groups are preferably bonded to different silicon atoms in the molecule.

This organopolysiloxane is represented, for example, by the following general formula (1) R ¹ _a R ² _b SiO _{4 -ab / 2} (1), wherein R ¹ is an aliphatic non-aliphatic group such as a vinyl group or an allyl group. Saturated group, formula

[Chemical 1] Alicyclic unsaturated hydrocarbon group represented by, or CH ₂ = CH
COOR ^3- (R ³ is a methylene group, ethylene group, propylene group,
A divalent organic group) unsaturated represented by like such as a phenylene group, R ² is a methyl group, an ethyl group, a propyl group, an alkyl group such as butyl group, cycloalkyl groups such as a cyclohexyl group, a phenyl group, a tolyl Aryl groups such as groups,
Or a chloromethyl group in which a part or all of hydrogen atoms bonded to carbon atoms of these groups are substituted with a halogen atom, a cyano group, 3,3,3-trifluoropropyl group,
An unsubstituted or substituted monovalent hydrocarbon group selected from cyanoethyl group and the like, a is 1, 2 or 3, b is 0, 1 or 2 and 1 ≦ a + b ≦ 3, which is 1
It is preferable that 90% or more of all organic groups in the molecule are methyl groups.

The organopolysiloxane may be linear, branched, or cyclic, but is preferably linear, in which the end of the molecular chain is blocked with a vinyl group and the side chain is Also has a vinyl group, but the vinyl group may contain a plurality of vinyl groups. In addition, this unsaturated group-containing organopolysiloxane has ≡Si—O—Si≡, ≡Si—R ⁴ —Si≡ (R ⁴ is a methylene group, an ethylene group, a propylene group, a phenylene group, a polyoxyethylene group) in the molecule. It may be a copolymer containing a divalent organic group such as), but this one has a viscosity (25 ° C) of 100 cp.
As described above, it is preferable to make a gum-like substance having several million to several tens of million cp.

Further, the organosilicon compound as the component B) constituting the composition of the present invention is supposed to have at least three hydrogen atoms bonded to silicon atoms in one molecule, which is JIS 105 ° C measured according to K7117
The weight reduction rate after heating for 3 hours must be 1% or less.

This organosilicon compound is represented by, for example, the following general formula (2) R ⁵ _c H _d SiO _{4 -cd / 2} (2), wherein R ⁵ is the same unsubstituted or substituted as the above R ^2. A monovalent hydrocarbon group of (50)% or more of which is a methyl group, and c and d are 0 <c <3, 0 <d <3 and 0
<C + d ≦ 3, preferably 1 ≦ c ≦ 2, 0 <d <
In the case of 1, 1.98 ≦ c + d ≦ 2.02.

The organosilicon compound is a linear, branched,
It may be cyclic, block polymer-like, or graft polymer-like, and the preferable one is linear.
If the average molecular weight of this product is less than 500, the weight loss rate after heating becomes large and the loss in the purification process becomes large.
If it is more than 3,000, the weight loss rate after heating will be small, but the compatibility with the component A) may be poor. Therefore, it is preferable that the average molecular weight is 500 to 3,000.

As described above, the organic silicon compound is assumed to have a weight loss rate of 1% or less after heating at 105 ° C. for 3 hours, which is 150 to 250 ° C. and 10 mmHg or less. It is only necessary to evaporate and remove the volatile siloxane beforehand by treating it under high temperature and high vacuum. When it is highly heat-reactive, it is inferior in stability at temperatures higher than 250 ° C.
Thin film distillation may be carried out in an inert gas at a temperature of 0 ° C. or lower, but low molecular siloxane may be removed by a solvent extraction method, a supercritical extraction method or the like.

The blending amount of the organosilicon compound as the component B) is 100 parts by weight of the component A).
If the amount is less than 0.1 part by weight, the effect of adding the component B) may not be exhibited, and if it exceeds 20 parts by weight, the curability of the resulting composition may be deteriorated and the release performance of the cured product of this composition may be impaired. Therefore, it is necessary to add 0.1 to 20 parts by weight, and the preferable range is 1 to 10 parts by weight.

Next, the platinum-based catalyst as the component C) which constitutes this composition is a catalyst for promoting the addition reaction between the above-mentioned components A) and B). Examples thereof include chloroplatinic acid, alcohol solutions of chloroplatinic acid, aldehyde solutions, complexes of chloroplatinic acid with various olefins, and vinylsiloxanes. It should be noted that the amount of this added may be a catalytic amount, but from this point of view of reactivity and economical efficiency, the amount of platinum is 1 to 100 parts by weight of the total amount of the components A) and B). 1,
The range may be 000 ppm.

Further, the control agent as the component D) which constitutes this composition is for suppressing the catalytic activity of the platinum-based catalyst as the component C), and it may be a known substance. Are various organic nitrogen compounds, organic phosphorus compounds,
Examples thereof include acetylene compounds, oxynium compounds, and organic chromium compounds. Among these, acetylene compounds such as 3-methyl-1-butyl-3-ol and silyl compounds thereof are useful. In addition, it is desirable that the addition amount of these is within a range of 0.01 to 3 parts with respect to 100 parts by weight of the total amount of the components A) and B).

The curable silicone composition for release paper of the present invention can be obtained by mixing a predetermined amount of each of the above-mentioned components A), B), C) and D). It is applied to a material to form a cured film with releasability, but the viscosity of this is approximately 1,000 cp if the viscosity at 25 ° C is not diluted with an organic solvent from the viewpoint of workability during application and control of coating amount. Hereinafter, when diluted with an organic solvent, it may be 100 cp or less after dilution.

The composition of the present invention is applied to a base material to form a peelable cured film on the surface of the base material.
As the base material, films and sheets made of celluloses, synthetic resins, synthetic fibers, etc., such as polyester film, glassine paper, kraft paper, clay coated paper,
Examples thereof include polyethylene laminated paper, and films, sheets and the like of polyethylene, polypropylene, vinyl chloride and the like. If this substrate is heated at 80 to 200 ° C. for several seconds to several minutes after the composition of the present invention is applied, the B) component has a weight loss rate after heating at 105 ° C. for 3 hours. Since the content is 1% or less, the release paper can have a small difference in release characteristics.

[0020]

EXAMPLES Examples and comparative examples of the present invention will be given below.
The parts in the examples are parts by weight, the viscosity is the measured value at 25 ° C., and the peeling force, the residual adhesion ratio, and the weight loss on heating in the examples are the following values.

<Peeling power> A predetermined amount of the silicone composition is applied to the surface of a thin film or sheet-like substrate and heated in a hot air dryer at a predetermined temperature for a predetermined time to form a cured film, which is then cured. Acrylic solvent-based pressure sensitive adhesive, Olivene BPS-5127 [manufactured by Toyo Ink Mfg. Co., Ltd.] was applied to the surface of the film and heat-treated at 100 ° C. for 3 minutes. Next, a high-quality paper weighing 64 g / m ² was attached to this treated surface, aged at 25 ° C. under a load of 20 g / cm ² for 20 hours, and then the sample was cut into a width of 5 cm, and a tensile tester was used. Peeling speed 0.3 at an angle of 180 °
The laminated paper was pulled at m / min and 60 m / min, and the force (g) required for peeling was measured.

<Residual Adhesion Rate> After a cured coating of a silicone composition was formed on the surface of a substrate in the same manner as in the case of measuring the peeling force, polyester Lumirror 31B tape (manufactured by Nitto Denko Corporation) was coated on the surface. The pieces were pasted together, a load of 20 g / cm ² was applied, and after heat aging at 70 ° C. for 20 hours, the tape was peeled off and the piece was attached to a stainless steel plate. Next, peel the treated paper from the stainless steel plate at an angle of 180 ° at peeling speeds of 0.3 m / min and 60 m / min, measure the force (g) required for peeling, and measure the untreated tape (silicone curing). The force (g) required for peeling (unbonded to the coating) from the stainless steel plate was measured, and the ratio thereof was taken and expressed as a percentage.

<Weight loss by heating> About 1.5 g of a sample was placed in an aluminum dish having a diameter of 50 mm and a depth of 7 mm, and the weight change was calculated after heating for 3 hours in a hot air circulation dryer at a temperature of 105 ° C.

Examples and Comparative Examples 1 liter of methylhydrogenpolysiloxane A having a viscosity of 4.6 cs, both ends of the molecular chain being blocked with trimethylsilyl groups, and a weight reduction rate measured according to JIS K7117 of 10.4%. In a separable flask of 800 g, 170
When N ₂ gas was flowed under stirring at ℃ and heated under reduced pressure of 5 mmHg for 24 hours, the weight loss rate after heating was
It became 0.5% of methyl hydrogen polysiloxane B.

Then, 100 parts of dimethylpolysiloxane having a viscosity of 400 cp and having both ends of the molecular chain blocked with dimethylvinylsilyl groups, 3.5 parts of the above-mentioned methylhydrogenpolysiloxane B and 3-methyl-1-butyne as a control agent. After uniformly mixing 1.5 parts of 3--3-ol, a complex salt of chloroplatinic acid and vinyl siloxane was added in an amount of 0.01 in terms of platinum.
Is added to prepare a curable silicone composition (I) for release paper, and the same treatment as described above is performed except that this organohydrogenpolysiloxane B is changed to organohydrogenpolysiloxane A for comparison. A curable silicone composition (II) for paper was prepared.

Next, about 1 g of this curable silicone composition for release paper (I) and (II) as a silicone amount was applied to glassine paper [made by Tomoegawa Paper Co., Ltd.] having a weight of 80 g / m ² and circulated with hot air. A release paper was made by heat-treating at 180 ° C for 5 seconds in a drying oven to form a cured film. At this time, the hot air velocity in the drying oven was 0.2 m / sec and 2.0 m / sec. When the peeling characteristics (peeling force, residual adhesion rate) were examined under different conditions, the results shown in Table 1 below were obtained.

[0027]

[Table 1]

[0028]

Industrial Applicability The present invention relates to a curable silicone composition for release paper, which comprises, as described above, A) an unsaturated group having at least two unsaturated groups bonded to a silicon atom in one molecule. 100 parts by weight of contained organopolysiloxane, B) An organosilicon compound having at least 3 hydrogen atoms bonded to silicon atoms in one molecule and having a weight loss rate of 1% or less after heating at 105 ° C. for 3 hours. It is characterized by comprising 0.1 to 20 parts by weight, C) a catalytic amount of a platinum-based catalyst, and D) a control agent, which is curable by the addition reaction between the components A) and B). Since it becomes a silicone composition, when it is applied to a base material and cured by heating, it exhibits peelability. However, the component B) used here has a weight loss rate of 1% or less after heating. Peeling obtained here because it has been The paper is given the advantage that it has a small release property and exhibits stable release performance.

Claims (1)

[Claims] 1. A) 100 parts by weight of an unsaturated group-containing organopolysiloxane having at least two unsaturated groups bonded to a silicon atom in one molecule, B) a hydrogen atom bonded to a silicon atom in one molecule. 0.1 to 20 parts by weight of an organosilicon compound having a weight loss rate of 1% or less after heating at 105 ° C. for 3 hours, having at least 3 of C, a catalytic amount of a platinum-based catalyst, and D) a control agent. A curable silicone composition for release paper, comprising: