JPH06322295A - Exposure-resistant release agent composition - Google Patents

Abstract

PURPOSE:To obtain a compsn. capable of forming a coating film of a release agent high in residual adhesion, free of migration of the release agent, and excellent in resistance to outside air exposure, by using predetermined amts. of a specific poylorganosiloxame, a specific poylyorganohydrogensiloxane, and platinum (compd.). CONSTITUTION:The compsn. comprises (A) a polyorganosiloxane having at least 2 vinyl groups bonded to Si per molecule and CH3 or phenyl groups as the rest of org. groups bonded to Si and having a viscosity (at 25 deg.C) of at least 50cP; a predetermined amt., based on the component (A), of a linear polyorganohydrogensiloxane of the formula I (wherein R<2> is CH3 or phenyl; R<1> is H or R<2>; an and b are each a positive integer; and the ratio of the no. of Si-H bond-contg. siloxane units to the no. of all siloxane units is 0.45 to 0.85) and/or a branched polyorganohydrogensiloxane of the formula II [wherein R<3> is R<2>; y is 0 or a; and the ratio of x to the no. of all siloxane units (x+y+z) is 0.2 to 0.8]; and a catalytic amt. of platinum (compd.).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stripping composition, and more particularly to a composition which is cured by a hydrosilylation reaction to form a stripping agent film showing stripping property to an adhesive or tacky substance. Therefore, the present invention relates to a composition for forming a release agent film, which prevents a phenomenon that the release property is lost when the coated surface is exposed to the outside air.

[0002]

2. Description of the Related Art Utilizing the fact that polyorganosiloxane does not show an affinity for various substances but has a releasability for adhesive or tacky substances, various fibers such as paper, synthetic It is well known that the surface of various base materials such as a resin film is treated and a cured film is formed by a crosslinking reaction to be used as a release agent film for an adhesive or tacky substance.

Such a curable polyorganosiloxane composition contains a vinyl group-containing polyorganosiloxane and a polyorganohydrogensiloxane having a hydrogen atom bonded to a silicon atom as main components and cures by a hydrosilylation reaction. An addition reaction-type stripping composition that allows the addition of a silanol group-containing polyorganosiloxane and the above-described polyorganohydrogensiloxane as a main component, and a condensation reaction-type stripping composition that is cured by dehydrogenative condensation are known. ing. The addition reaction type is widely used as a peeling composition because it has advantages such as a higher curing speed and a smaller peeling speed dependency of the peeling force than the condensation reaction type. However, the addition reaction type peeling composition has a phenomenon that the peeling performance is lost when the coating film obtained by curing is exposed to the outside air. Therefore, in the process of producing a label or an adhesive tape using a release paper or a release film on which a release agent coating is formed using an addition reaction type release composition, the coating is exposed to the atmosphere. Then, these products can no longer exhibit the original peeling property and cannot be peeled off, resulting in a serious deterioration in quality.

In order to solve such a problem, a method of blending an alcohol-modified polyorganosiloxane or a polyether-modified polyorganosiloxane with an addition reaction type stripping composition (JP-A-55-3460), And as part of the polyorganohydrogensiloxane,
A method (Japanese Patent Laid-Open No. 1-217068) in which a compound having a hydrosilyl group only on one terminal silicon atom is blended is known. However, these methods have some effect on the stability against exposure to the atmosphere (hereinafter referred to as “exposure resistance”), but they are not sufficient, and the amount of transfer of the release agent to the adhesive layer is not sufficient. However, there is a problem that the residual adhesive strength is reduced.

[0005]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems of the addition reaction type stripping composition, and the purpose thereof is to suppress the migration of the stripping agent and to improve the residual adhesive strength. It is an object of the present invention to provide an addition reaction type stripping composition that gives a stripping agent film having exposure resistance without causing deterioration.

[0006]

Means for Solving the Problems As a result of intensive studies to solve this problem, the present inventors have found that in a stripping composition that cures by an addition reaction, the following molecular structure (I) is used as the component (B). ) And (II), the content of the Si-H bond-containing siloxane unit in the component (B) is selected; the specific amount of the component (B) with respect to the component (A) described below is selected. By including, by curing, a release composition that provides a release agent film having excellent exposure resistance specifically, low migration of the release agent, and high residual adhesive strength, and the present invention, It came to completion.

That is, the present invention provides the following component (A),
The present invention relates to an exposure-resistant peeling composition containing the component (B) and the component (C). (A) It has two or more vinyl groups bonded to a silicon atom in one molecule, the remaining organic group bonded to a silicon atom is a methyl group or a phenyl group, and the viscosity at 25 ° C. is 50.
a polyorganosiloxane having a cP or more; (B) a straight chain represented by the formula (I) and / or a branch represented by the formula (II), which has an average of at least 3 hydrogen atoms bonded to silicon atoms in one molecule. The amount of hydrogen atom bonded to the silicon atom of the component (B) is 2.3 to 4.0 with respect to one vinyl group in the component (A);

[Chemical 3] (In the formula, R ¹ may be the same or different from each other,
Represents a hydrogen atom, a methyl group or a phenyl group; R ^{2 s} may be the same or different from each other and represent a methyl group or a phenyl group; a and b each represent a positive integer; a Si—H bond-containing siloxane unit The ratio of the number to the total number of siloxane units is 0.45 to 0.85);

[Chemical 4] (In the formula, R ³ may be the same or different from each other,
Represents a methyl group or a phenyl group; y represents 0 or a positive integer; the ratio of x to the total number of siloxane units (x + y + z) is 0.2 to 0.8); (C) Platinum or platinum compound Catalytic amount .

<Component (A)> The polyorganosiloxane of component (A) is a component used as a base polymer in the stripping composition of the present invention. This component (A) contains a vinyl group directly bonded to a silicon atom in 2 molecules per molecule.
By having at least one of these vinyl groups and forming a network structure by the reaction with the hydrosilyl group of the component (B) described later,
It can be cured to form a coating. The vinyl groups are preferably bonded to different silicon atoms, and may be bonded to either the terminal silicon atom of the siloxane chain or the intermediate silicon atom. In order to obtain a film having excellent mechanical strength, it is more preferable that a vinyl group is bonded to at least a terminal silicon atom of a siloxane chain.

As described above, the amount of vinyl groups is 2 or more in one molecule, the curability, the physical properties of the coating film after curing, the amount of components that migrate from the coating film to the adhesive layer are small, and the residual adhesion ratio is low. Since it is high and the base polymer is easily produced, the vinyl group-containing siloxane unit is preferably in the range of 0.5 to 10 mol% in all siloxane units.

The organic group other than the vinyl group bonded to the silicon atom means that the coating film obtained by curing has excellent releasability, mechanical strength and fluidity before curing, and further has the exposure resistance which is the object of the present invention. Therefore, it is substantially a methyl group or a phenyl group. In particular, 85% or more of the organic groups are preferably methyl groups, and more preferably all methyl groups, in order to impart excellent exposure resistance to the film.

The siloxane skeleton of the component (A) may be linear or branched and may be used as a mixture thereof in order to impart excellent mechanical properties to the coating. As described above, the viscosity at 25 ° C. is 50 cP or more, preferably 100 cP or more. If the viscosity is less than 50 cP, sufficient peelability and mechanical strength cannot be given to the cured film. Especially when using a base material such as glassine paper or kraft paper, if the viscosity is low, it will not penetrate the base material. Tends to be crowded,
The peelability is poor when the same treatment amount is used.

<Component (B)> The polyorganohydrogensiloxane of component (B) is a component used as a crosslinking agent in the stripping composition of the present invention. That is, the hydrosilyl group contained in the component (B) undergoes an addition reaction with the vinyl group in the component (A) to form a network structure. Therefore, the average number of hydrogen atoms directly bonded to silicon atoms in the component (B) is at least 3 in one molecule, and due to the ease of synthesis and reactivity, the above-mentioned general formulas (I) and ( As shown in II), each such hydrogen atom bonds with a different silicon atom to form a Si-H bond-containing siloxane unit.

Further, the polyorganohydrogensiloxane has a specific molecular structure and Si in order to cure the composition to give a release agent film excellent in exposure resistance.
It is necessary to have a ratio of the number of -H bond containing siloxane units to the total number of siloxane units. Such a polyorganohydrogensiloxane is a linear polyorganohydrogensiloxane represented by the following formula (I) or a branched polyorganohydrogensiloxane represented by the following formula (II), and a mixture thereof is also possible. Good.

[0014]

[Chemical 5]

(In the formula, R ¹ , R ² , a and b are as described above) The formula (I) simply represents the constitutional ratio of the siloxane unit, and the linear polyorganohydrogensiloxane is The former is generally used regardless of whether it is a random copolymer or a block copolymer. In the formula (I), the siloxy groups at both terminals may be hydrogen atoms, methyl groups or phenyl groups as R ¹ . When R ^{1 at} both ends is a hydrogen atom, the number a ′ of Si—H-containing siloxane units in the polyorganohydrogensiloxane is a + 2. When R ^{1 at} one end is a hydrogen atom, a ′ is a + 1, and when R ^{1 at} both ends is a methyl group or a phenyl group, a ′ is equal to a. A characteristic of the present invention is that the ratio a ′ / (a + b + 2) of the number of all siloxane units is a ′ / (a +
b + 2) is 0.45 to 0.85, preferably 0.45
When it is 0.75, excellent exposure resistance can be given to the release agent layer obtained by curing.

[0016]

[Chemical 6]

(Wherein R ³ , x, y and z are as described above) In the formula (II), R ³ ₂ HSiO _1/2 unit and R 3
^{All 3} ₃ SiO _1/2 units are bonded to SiO ₂ units in any combination to form a branched polysiloxane.
In the polyorganohydrogensiloxane, S
The number of i-H containing siloxane units is x. In order to give excellent release resistance to the release agent layer obtained by curing, the ratio of x to the number of all siloxane units (x + y + z) is x / (x + y).
+ Z) is required to be in the range of 0.20 to 0.80, preferably 0.30 to 0.70.

In any of the formulas (I) and (II), the organic group bonded to the silicon atom, that is, R ¹ (except when it is a hydrogen atom), R ² and R ³ are contained in the release agent layer. From the viewpoint of providing excellent exposure resistance, it is preferably a methyl group or a phenyl group, and 85% or more of the organic groups in the molecule are preferably methyl groups, and more preferably all methyl groups.

The viscosity is not particularly limited, but the viscosity at 25 ° C. is 500 because it is easy to synthesize and handle.
It is preferably cP or less.

The blending amount of such a component (B) is (B)
The amount of hydrogen atoms bonded to silicon atoms in the component is 2.3 to 4.0 with respect to one vinyl group in the component (A), whereby a release agent obtained by curing is obtained. The coating has excellent resistance to exposure. Also, within the above range,
The amount of the component (B) is 0.5 to 100 parts by weight with respect to 100 parts by weight of the component (A), the average molecular weight of both components, and the vinyl group content of the component (A) and (B).
It is preferable to select the content of hydrogen atoms bonded to the silicon atoms of the component. If this amount is less than 0.5 parts by weight,
It is difficult to uniformly disperse the component (B) in the component (A) in a short period of time, which causes work restrictions. Also, this amount is 1
If the combination exceeds 00 parts by weight, the residual adhesion rate is lowered and the transferability is deteriorated.

<Component (C)> The platinum or platinum compound of the component (C) acts as a catalyst for the hydrosilylation reaction between the vinyl group in the component (A) and the Si-H bond in the component (B). It is a curing catalyst, and a platinum compound is preferable from the viewpoint of catalytic effect. Examples of the platinum compound include chloroplatinic acid, a reaction product of chloroplatinic acid and an alcohol, platinum-olefin complex, platinum-
Examples thereof include vinyl siloxane complex, platinum-phosphorus complex, platinum coordination compound and the like.

The blending amount of the component (C) is an effective amount as a catalyst, and is usually in the range of 1 to 500 ppm as platinum atom based on the total amount of the components (A) and (B).
300 ppm is preferred. If it is less than 1 ppm, the curing is very slow and there is a practical disadvantage, and if it exceeds 300 ppm, the corresponding improvement in the curing rate cannot be expected, which is not preferable in terms of economy and stability.

<Other Additives> If desired, known additives may be added to the composition of the present invention as long as the functions of the composition of the present invention are not impaired. Such additives include polydimethylsiloxane, inorganic fillers such as fumed silica, pigments such as red iron oxide, cure inhibitors such as 2-methyl-3-butyn-2-ol, and 2-hydroxy. -2-Methyl-1-phenylpropane-
A photosensitizer like 1-one can be illustrated.

<Usage> The composition of the present invention may be applied directly to a substrate when the apparent viscosity of the system is low, but it may be diluted with a solvent in consideration of workability of application and treatment. It is generally used. Examples of the solvent include aromatic hydrocarbons such as benzene, toluene and xylene; aliphatic hydrocarbons such as heptane and hexane; halogenated hydrocarbons such as tetrachloroethylene; esters such as ethyl acetate and butyl acetate; and methyl ethyl ketone and methyl isobutyl ketone. Of ketones; and mixtures thereof.

In the composition of the present invention, the component (A) and the component (B), and optionally additives and solvents are mixed and the component (C) prepared separately or a solution thereof is used immediately before use. And then applied to the substrate. If necessary,
The component (B) may be stored separately, or a mixture of the components (A) and (B) in the presence of a curing inhibitor or a solution thereof may be stored.

As the substrate, glassine paper, kraft paper,
Examples include, but are not limited to, paper or paper composite materials such as parchment paper and polyethylene laminated paper; and plastic films such as polyethylene film and polypropylene film.

After coating, when a solvent is present, the solvent is dried to remove the solvent and then heated and cured to form a release agent film on the surface of the substrate. The heating condition is usually a temperature of 100 to 1
It is 10 to 30 seconds at 50 ° C.

[0028]

The release agent coating obtained by curing the composition of the present invention has a high residual adhesion ratio and no migration of the release agent, and is also characterized by excellent exposure resistance. ing. That is, a release paper or a release film having such a release agent coating formed thereon, even if the release agent surface is exposed to the outside air,
The force required for peeling (peeling force) does not become heavy, and the initial residual adhesive ratio and transferability are maintained, which is advantageous in terms of quality stabilization and has great industrial significance.

[0029]

The present invention will be described in more detail with reference to the following examples and comparative examples. The invention is not limited by these examples. In the following Examples and Comparative Examples, parts represent parts by weight, and the viscosity shows a value at 25 ° C.

In Examples and Comparative Examples, the following components A-1 to A-4 as the component (A) and B-1 to B as the component (B) were used.
-8 was used. However, B-5 to B-8 are polyorganohydrogensiloxanes for comparison. In addition,
In the description below and the unit formulas in Table 1, siloxane units are represented by the following abbreviations. The unit formula means a constitutional ratio of siloxane units, and each polysiloxane is a random copolymer. _{M: (CH 3) 3 SiO} 1/2 units _{M': (CH 3) 2 HSiO} 1/2 units ^{_{M v: (CH 3) 2}} (CH 2 = CH) SiO 1/2 units D: (CH _{3) 2} SiO units D': (CH ₃₎ HSiO units _{^{D v: (CH 3) (}} CH 2 = CH) SiO unit ^{_{D ph2: (C 6 H 5}} ) 2 SiO units _{^{M OH: HO (CH 3)}} 2 SiO 1 _{/ 2} unit Q: SiO ₂ unit

B-2 is a branched polymethylhydrogensiloxane composed of M'units and Q units, having a weight average molecular weight of about 900 and a content of hydrogen atoms bonded to silicon atoms of 1.029 weight. %Met.

C-1 used as the component (C) is a platinum-vinylsiloxane complex obtained from chloroplatinic acid and tetravinyltetramethylcyclotetrasiloxane, and has a platinum content of 4,000 ppm. D-2 used as a curing inhibitor is 2-methyl-3-butyn-2-ol.

According to the compounding ratio shown in Table 1, the component (A),
Component (B) and C-1, and, if necessary, toluene, D-1 and D-2 are mixed, stirred and mixed until uniform, and the treatment liquids of Examples 1 to 10 and Comparative Examples 1 to 5 are mixed. Were prepared respectively.

These treatment liquids were applied to polyethylene laminated paper having a density of 75 g / m ² so that the coating amount after drying would be 0.8 g / m ² and heated at 110 ° C. for 30 seconds to cure, A release agent coating was formed on the surface of polyethylene laminated paper.

[0035]

[Table 1]

The release coating film thus obtained was evaluated as follows. As a result, the results shown in Table 2 were obtained.

[0037]

[Table 2]

<Peeling Force (Initial)> On the surface of the release agent coating,
Acrylic solvent type adhesive Olivine BPS-8170 (trade name, manufactured by Toyo Ink Co., Ltd.) was applied so as to have an undried thickness of 88 μm and dried at 100 ° C. for 3 minutes.

Next, a high-quality paper having a unit weight of 60 g / m ² was stuck on it, and the whole was cut into a strip shape having a width of 5 cm. Under a load of 20 g / cm ² , this is at a temperature of 25 ° C and a relative humidity of 5
The sample was aged for 1 day under the condition of 0%. This sample was tested by a tensile tester at a speed of 180 m in a direction of 0.3 m / mi.
It was pulled at n and the force required for peeling was measured.

<Peeling power (after exposure)> A sample having a release agent coating film was exposed outdoors to the atmosphere for 4 hours with its treated surface facing upward. Using this, the peeling force was measured by the same method as in the initial stage.

<Residual adhesive strength> A 2.5 cm wide Nitto 31B adhesive tape (Nitto Denko Corp.) was applied to the surface of the release agent film.
Made, product name) is pasted. This was left at 70 ° C. for 20 hours under a load of 20 g / cm ² , the tape was peeled from the surface of the release agent coating, and the surface in contact with the release agent was attached to a stainless steel plate (JIS C2107). Attached and pressed with a 2 kg roller. What was aged at 25 ° C. for 3 hours was pulled in a direction of 180 ° by a tensile tester, and the peeling force (f) of the tape was measured. On the other hand, attach the same type of adhesive tape to the polytetrafluoroethylene film,
After that, by the same operation, the standard peeling force (f
_o ) was measured. The residual adhesion rate was calculated by the following formula.

[0042]

[Equation 1]

<Transition property> The polyethylene laminated paper provided with the release agent coating as described above was cut into a strip shape having a width of 5 cm. A 25 μm-thick PET film is attached to the release agent coating surface, a load of 100 g / cm ² is applied, and pressure bonding is performed at 65 ° C. for 20 hours, then peeled off, and the PET film surface of the side in contact with the release agent is treated with a magic marker. A line was drawn with ink (Hi Mackey: product name, manufactured by Zebra Corp.), and the degree of ink repellency was observed, and evaluation was performed in four levels.

Claims (1)

[Claims] 1. An exposure-resistant peeling composition comprising the following component (A), component (B) and component (C). (A) It has two or more vinyl groups bonded to a silicon atom in one molecule, the remaining organic group bonded to a silicon atom is a methyl group or a phenyl group, and the viscosity at 25 ° C. is 50.
a polyorganosiloxane having a cP or more; (B) a straight chain represented by the formula (I) and / or a branch represented by the formula (II), which has an average of at least 3 hydrogen atoms bonded to silicon atoms in one molecule. Of the polyorganohydrogensiloxane in the form of (B), in which the number of hydrogen atoms bonded to the silicon atom of the component (B) is 2.3 to 4.0 per one vinyl group in the component (A); 1] (In the formula, R ¹ may be the same or different from each other,
Represents a hydrogen atom, a methyl group or a phenyl group; R ^{2 s} may be the same or different from each other and represent a methyl group or a phenyl group; a and b each represent a positive integer; a Si—H bond-containing siloxane unit The ratio of the number to the total number of siloxane units is 0.45 to 0.85); (In the formula, R ³ may be the same or different from each other,
Represents a methyl group or a phenyl group; y represents 0 or a positive integer; the ratio of x to the total number of siloxane units (x + y + z) is 0.2 to 0.8); (C) Platinum or platinum compound Catalytic amount .