JP2934118B2 - Exposure resistant release agent - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a release composition, and more particularly, to a composition which is cured by a hydrosilylation reaction to form a release agent film exhibiting releasability to an adhesive or tacky substance. In addition, the present invention relates to a composition for forming a release agent film, which prevents a phenomenon in which releasability is lost due to exposure of an application surface to outside air.

[0002]

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

Such a curable polyorganosiloxane composition is mainly composed of a vinyl-containing polyorganosiloxane and a polyorganohydrogensiloxane having a hydrogen atom bonded to a silicon atom, and is cured by a hydrosilylation reaction. There is known an addition-reaction-type stripping composition to be cured; and a condensation-reaction-type stripping composition comprising a silanol group-containing polyorganosiloxane and the above-mentioned polyorganohydrogensiloxane as main components and cured by dehydrogenation condensation. ing. The addition reaction type is widely used as a release composition because it has advantages such as a higher curing speed and a smaller release speed dependency of the release force than the condensation reaction type. However, the addition-removable release composition exhibits a phenomenon in which the release performance is lost when the cured film is exposed to the open air. Therefore, using a release paper or a release film on which a release agent film is formed using an addition-reaction type release composition, the film is exposed to the air in the process of manufacturing labels and adhesive tapes. In such a case, these products cannot exhibit their original peeling property, and cannot be peeled, 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 (Japanese Patent Application Laid-Open No. 55-3460), And as part of the polyorganohydrogensiloxane,
There is known a method of blending a compound having a hydrosilyl group only at one silicon atom at one end (Japanese Patent Application Laid-Open No. Hei 217068). However, these methods have a certain effect on the stability to exposure to air as described above (hereinafter referred to as exposure resistance), but they are not sufficient, and the transfer amount of the release agent to the adhesive layer is reduced. In addition, there is a problem that the residual adhesive strength decreases.

[0005]

SUMMARY OF THE INVENTION The present invention solves the above-described problems of the addition-removable release composition, and its object is to suppress the migration of the release agent and reduce the residual adhesive force. An object of the present invention is to provide an addition-removable release composition which gives a release agent film having exposure resistance without causing a decrease.

[0006]

Means for Solving the Problems The present inventors have made intensive studies to solve this problem, and as a result, in a peeling composition which is cured by an addition reaction, the following molecular structure (I) is used as the component (B). ) And (II), the content of the siloxane unit containing a Si—H bond in the component (B) is selected; the component (B) is added in a specific amount relative to the component (A) described below. By including, it has been found that by curing, a release composition that gives a release agent film having a specific excellent exposure resistance, a small migration property of the release agent, and a large residual adhesive force can be obtained. It was completed.

That is, the present invention provides the following component (A):
The present invention relates to an exposure-resistant stripping composition containing the component (B) and the component (C). (A) two or more vinyl groups bonded to a silicon atom in one molecule, and the remaining organic group bonded to the silicon atom is a methyl group or a phenyl group;
a polyorganosiloxane having cP or more; (B) a linear group represented by the formula (I) and / or a branch represented by the formula (II) having an average of at least three hydrogen atoms bonded to silicon atoms in one molecule. The amount of the hydrogenated hydrogen bonded to the silicon atom of the component (B) is 2.3 to 4.0 per one vinyl group in the component (A);

Embedded image (Wherein R ¹ may be the same or different from each other;
R ² represents a hydrogen atom, a methyl group or a phenyl group; R ² may be the same or different, and represents a methyl group or a phenyl group; a and b each represent a positive integer; The ratio of the number to the total number of siloxane units is from 0.45 to 0.85);

Embedded image (Wherein, R ³ may be the same or different from each other;
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 .

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

As described above, the amount of the vinyl group is two or more in one molecule, the curability, the physical properties of the cured film, the amount of the component which migrates from the film to the adhesive layer is small, and the residual adhesion ratio is low. It is preferable that the vinyl group-containing siloxane unit is in the range of 0.5 to 10 mol% based on the total siloxane unit, because of its high cost and easy production of the base polymer.

An organic group other than a vinyl group bonded to a silicon atom is required that a film obtained by curing has excellent releasability, mechanical strength and fluidity before curing, and also has exposure resistance, which is the object of the present invention. From is substantially a methyl or phenyl group. In particular, in order to give the film excellent exposure resistance, it is preferable that 85% or more of the organic groups are methyl groups, and it is more preferable that all of the organic groups are methyl groups.

The siloxane skeleton of the component (A) may be linear or branched, and these may be used in combination to give the coating excellent mechanical properties. As described above, the viscosity is 50 cP or more at 25 ° C., and preferably 100 cP or more. If the viscosity is less than 50 cP, it is not possible to impart sufficient peelability and mechanical strength to the cured film. In particular, when a base material such as glassine paper or kraft paper is used, if the viscosity is low, it will not penetrate the base material. Tend to be
Inferior peelability when using the same processing amount.

<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, a network structure is formed by performing an addition reaction between the hydrosilyl group contained in the component (B) and the vinyl group contained in the component (A). Therefore, the number of hydrogen atoms directly bonded to silicon atoms in the component (B) is an average of at least three in one molecule, and the above-mentioned general formulas (I) and ( As shown in II), such hydrogen atoms combine with different silicon atoms to form Si-H bond-containing siloxane units.

Further, the polyorganohydrogensiloxane is required to have a specific molecular structure and a specific molecular structure in order to cure the composition to give a release agent film having excellent exposure resistance.
It is necessary to have a ratio of the number of siloxane units containing -H bonds 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). Good.

[0014]

Embedded image

(Wherein R ¹ , R ² , a and b are as described above) Note that the formula (I) simply shows the constitutional ratio of siloxane units, and the linear polyorganohydrogensiloxane is Any of a random copolymer and a block copolymer may be used, and the former is generally used. In the formula (I), the siloxy groups at both terminals may be such that R ¹ is a hydrogen atom, a methyl group or a phenyl group. When R ^{1 at} both ends is a hydrogen atom, the number a ′ of the 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. When R ^{1 at} both ends is a methyl group or a phenyl group, a ′ is equal to a. What is characteristic in the present invention is that the ratio a '/ (a +) of such a' to the number of all siloxane units (a + b + 2).
b + 2) is from 0.45 to 0.85, preferably from 0.45 to
When it is 0.75, this makes it possible to impart excellent exposure resistance to the release agent layer obtained by curing.

[0016]

Embedded image

(Wherein R ³ , x, y and z are as described above) In the formula (II), R ³ ₂ HSiO _1/2 units and R
³ ₃ SiO _1/2 units are bonded in any combination in any SiO ₂ units to form a branched polysiloxane.
In the polyorganohydrogensiloxane, S
The number of i-H containing siloxane units is x. In order to impart excellent exposure resistance to the cured release agent layer, the ratio of x to the total number of siloxane units (x + y + z) x / (x + y)
+ Z) must be in the range of 0.20 to 0.80, preferably 0.30 to 0.70.

In each 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 added to the release agent layer. In order to provide excellent exposure resistance, a methyl group or a phenyl group is preferred, and 85% or more of the organic groups in the molecule are preferably methyl groups, and more preferably all are methyl groups.

The viscosity is not particularly limited, but the viscosity at 25 ° C. is 500 due to the ease of synthesis and handling.
It is preferably cP or less.

The amount of the component (B) is as follows:
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). The coating has excellent exposure resistance. Also, within the above range,
The amount of the component (B) is 0.5 to 100 parts by weight per 100 parts by weight of the component (A).
It is preferable to select the content of the hydrogen atom bonded to the silicon atom 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 time, which imposes operational restrictions. Also, this amount is 1
If the amount exceeds 00 parts by weight, the residual adhesion rate decreases, and the migration property deteriorates.

<Component (C)> The platinum or platinum compound of the component (C) functions 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 preferred from the viewpoint of catalytic effect. Platinum compounds include chloroplatinic acid, reaction products of chloroplatinic acid and alcohol, platinum-olefin complexes, platinum-
Examples thereof include a vinylsiloxane complex, a platinum-phosphorus complex, and a platinum coordination compound.

The compounding 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 with respect to the total amount of the components (A) and (B).
300 ppm is preferred. If it is less than 1 ppm, curing is extremely slow, which is disadvantageous in practical use. If it exceeds 300 ppm, a corresponding improvement in curing speed cannot be expected, which is not preferable in terms of economy and stability.

<Other Additives> Known additives may be added to the composition of the present invention, if necessary, as long as the function of the composition of the present invention is not impaired. Such additives include inorganic fillers such as polydimethylsiloxane, fumed silica, pigments such as red iron, curing inhibitors such as 2-methyl-3-butyn-2-ol, and 2-hydroxy -2-methyl-1-phenylpropane-
Photosensitizers such as 1-one can be exemplified.

<Usage Method> The composition of the present invention may be applied to a substrate as it is when the apparent viscosity of the system is low, but it is diluted with a solvent in consideration of workability of application and processing. 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. And mixtures thereof.

The composition of the present invention is usually prepared by mixing the components (A) and (B), and additives and solvents as required, and then preparing the separately prepared component (C) or a solution thereof immediately before use. And apply to the substrate. If necessary,
The component (B) may be stored separately, or a mixture of the components (A) and (B) or a solution thereof may be stored in the presence of a curing inhibitor.

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

After the application, if a solvent is present, it 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 at a temperature of 100 to 1
10 to 30 seconds at 50 ° C.

[0028]

The release agent film obtained by curing the composition of the present invention has a high residual adhesiveness, no migration of the release agent, and in particular, has excellent exposure resistance. ing. That is, a release paper or a release film on which such a release agent film is formed, even if the release agent surface is exposed to the outside air,
Since the force required for peeling (peeling force) is not increased, and the initial residual adhesion rate and migration property are maintained, it is advantageous in terms of quality stabilization and has great industrial significance.

[0029]

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

Examples and comparative examples include the following components A-1 to A-4 as components (A) and components B-1 to B-4 as components (B).
-8 was used. However, B-5 to B-8 are polyorganohydrogensiloxanes for comparison. In addition,
In the following description and in the unit formula in Table 1, siloxane units are represented by the following abbreviations. The unit formula means the composition 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 unit D ': (CH ₃ ) H SiO unit D ^v : (CH ₃ ) (CH ₂ ^ＣＨCH ) SiO unit D ^ph2 : (C ₆ H ₅ ) ₂ SiO unit 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 hydrogen atom content bonded to silicon atoms of 1.029% by 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)
(B) The component and C-1 and, if necessary, toluene, D-1 and D-2 are blended, and the mixture is stirred and mixed until the mixture becomes uniform. Was prepared respectively.

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

[0035]

[Table 1]

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

[0037]

[Table 2]

<Release Force (Initial)>
Acrylic solvent-type pressure-sensitive adhesive Olivine BPS-8170 (trade name, manufactured by Toyo Ink Co., Ltd.) was applied so as to have a wet thickness of 88 μm, and dried at 100 ° C. for 3 minutes.

Next, high-quality paper having a unit weight of 60 g / m ² was peeled off thereon, and the whole was cut into a strip having a width of 5 cm. This was applied under a load of 20 g / cm ² at a temperature of 25 ° C. and a relative humidity of 5
After curing for 1 day under the condition of 0%, a sample was obtained. The sample was subjected to a tensile tester at a speed of 0.3 m / mi in the 180 ° direction.
n and the force required for peeling was measured.

<Release Force (After Exposure)> The sample having the release agent coating was exposed outdoors to the air for 4 hours with the treated surface facing upward. Using this, the peeling force was measured by the same method as in the initial stage.

<Residual adhesive strength> Nitto 31B adhesive tape (width 2.5 cm) (Nitto Denko Corporation)
Product name). After leaving this at 70 ° C. for 20 hours under a load of 20 g / cm ² , the tape was peeled off 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). And pressed with a 2 kg roller. This was cured at 25 ° C. for 3 hours, pulled in a 180 ° direction by a tensile tester, and the peeling force (f) of the tape was measured. On the other hand, the same kind of adhesive tape is stuck on polytetrafluoroethylene film,
Thereafter, by the same operation, the reference peeling force (f
_o ) was measured. The residual adhesion rate was calculated by the following equation.

[0042]

(Equation 1)

<Migration> The polyethylene laminated paper provided with the release agent coating as described above was cut into a strip having a width of 5 cm. A 25 μm-thick PET film was stuck on the release agent coating surface, a load of 100 g / cm ² was applied, and the film was pressed at 65 ° C. for 20 hours. A line was drawn with ink (Hi Mackey: manufactured by Zebra Corp., trade name), the degree of repelling of the ink was observed, and a four-stage evaluation was performed.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-4-20570 (JP, A) JP-A-2-298550 (JP, A) JP-A-58-19370 (JP, A) (58) Investigation Field (Int.Cl. ⁶ , DB name) C09D 183/05 C09D 183/07 C09D 5/20 C09J 7/02

Claims (1)

(57) [Claims] 1. Exposure resistance of an adhesive or tacky substance containing the following components (A), (B) and (C)
paint remover. (A) two or more vinyl groups bonded to a silicon atom in one molecule, and the remaining organic group bonded to the silicon atom is a methyl group or a phenyl group;
a polyorganosiloxane having cP or more; (B) a linear group represented by the formula (I) and / or a branch represented by the formula (II) having an average of at least three hydrogen atoms bonded to silicon atoms in one molecule. The amount of hydrogen in the form of polyorganohydrogensiloxane in the form of 2.3 to 4.0 hydrogen atoms bonded to silicon atoms in component (B) per vinyl group in component (A); 1) (Wherein R ¹ may be the same or different from each other;
R ² represents a hydrogen atom, a methyl group or a phenyl group; R ² may be the same or different from each other, and represents a methyl group or a phenyl group; a and b each represent a positive integer; The ratio of the number to the total number of siloxane units is from 0.45 to 0.85); (Wherein, R ³ may be the same or different from each other;
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 a platinum compound .