JPH0892371A - Releasable silicone composition - Google Patents

Abstract

PURPOSE: To obtain the subject composition capable of giving release films with low release force and low residual adhesion fall, useful for release paper, comprising the main component including an organopolysiloxane capable of forming cured releasable film and a component containing cyclosiloxane side chain. CONSTITUTION: This composition capable of giving release films with low release force at both low and high speed release and low residual adhesion fall, is obtained by incorporating 100 pts.wt. of the main component including an organopolysiloxane capable of forming releasable films after cured, composed of an organopolysiloxane having in one molecule at least two alkenyl groups bound to a Si atom and >=50cp in viscosity at 25 deg.C, an organohydrogenpolysiloxane having in one molecule at least two H atoms bound to a Si atom, and a platinum-based addition reaction catalyst, with 0.1-50 pts.wt. of an organopolysiloxane as an ingredient 10-10<5> cp in viscosity at 25 deg.C having in one molecule at least one group of the formula ((m) is an integer of 2-12; (x) is an integer of 2-5) bound to a Si atom.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a silicone composition for release paper, which provides a release film which is released with a light release force at low speed and high speed release and has a small reduction in residual adhesion ratio. The present invention relates to a peelable silicone composition that can be used as a release liner for labels and labels.

[0002]

2. Description of the Related Art Conventionally, a silicone composition film is formed on the surface of a base material to prevent releasability for the purpose of preventing adhesion and sticking of the base material such as paper, processed paper, and plastic film to an adhesive substance. Granting is done. In this case, as a method for forming a silicone film on the surface of the base material, a release film is formed by addition-reacting an organopolysiloxane containing an aliphatic unsaturated group with an organohydrogenpolysiloxane using a platinum compound as a catalyst. How to form,
A method of forming a releasable film by subjecting an organopolysiloxane to a condensation reaction using an organic acid metal salt catalyst such as an organic tin compound is known. The silicone compositions used in these methods are all called a heat cure type in which a film is formed by heating, and depending on their properties, a silicone type dissolved in an organic solvent such as toluene, a solvent type, dispersed in water. It is classified into the emulsion type and the solventless type consisting only of silicone. Furthermore, in these releasable silicone compositions, in order to improve workability in the rewinding step in the production of adhesive paper, the dust removing step in the production of an adhesive label, the label sticking step, etc., a phenyl group-containing non-functional composition is used. It is proposed in Japanese Patent Publication No. 3-52498 to add an organopolysiloxane to achieve lighter peeling at high speed peeling.

[0003]

However, when a non-functional organopolysiloxane containing a phenyl group is added to a peelable silicone composition, the peeling force is reduced, but the residual adhesion rate is also greatly reduced due to blooming of the non-reactive component. The current situation is that it is difficult to improve workability due to the problem that it does. The present invention has been made to solve the above-mentioned problems, and provides a peelable silicone composition that gives an excellent release coating that is lightly peeled at low speed and high speed peeling and has a small reduction in residual adhesion rate. The purpose is to

[0004]

Means for Solving the Problems As a result of intensive studies to achieve the above object, the present inventor has found that a main component 100 containing an organopolysiloxane that cures to form a peelable film.
25 parts by weight having a part by weight and a group represented by the following (Chemical Formula 2) bonded to at least one silicon atom in one molecule (where m is an integer of 2 to 12 and x is an integer of 2 to 5). Viscosity 10-10
^A peelable silicone composition consisting of 0.1 to 50 parts by weight of an organopolysiloxane of ⁵ cp can give a light peeling force at the time of peeling at low speed and high speed, and a release film with little reduction in residual adhesion rate. Therefore, it was found that the rewinding process in the production of adhesive paper and the dust removing process in the production of adhesive labels, the label attaching process, etc. can be speeded up to streamline the process and improve the workability, thus completing the present invention. did.

[0005]

[Chemical 2]

As the main component in the present invention, a conventionally known peelable composition can be used as it is, but in addition to the above addition reaction type and condensation reaction type compositions, for example, acrylic silicone is cured by electron beam. It is also possible to use a composition, a composition in which a photopolymerization initiator is added to acrylic silicone, and the composition is cured with ultraviolet rays. Among such compositions, the addition reaction type has a low peeling force and a high residual adhesion rate, and therefore, in the present invention, it is added as a main component of the composition which is cured to form a peelable film. A reactive organopolysiloxane was used.

Addition reaction type organopolysiloxane compositions which can be used as a main component in the present invention are known ones, and they are composed of the following three components. (A) Organopolysiloxane having alkenyl groups bonded to at least two silicon atoms in one molecule and having a viscosity at 25 ° C. of 50 cp or more (B) Hydrogen bonded to at least two silicon atoms in one molecule Organohydrogenpolysiloxane having atoms (C) Platinum-based addition reaction catalyst The organopolysiloxane of component (A) has at least two alkenyl groups bonded to silicon atoms in one molecule. Examples of the alkenyl group include a vinyl group, an allyl group, a hexenyl group, a dodecenyl group, and the like, and an economically preferable alkenyl group is a vinyl group. The alkenyl group is 0.05 to 50 mol%, especially 0.2 to 10 mol% based on all the organic groups in the organopolysiloxane.
It is preferable to contain it by mol%. Alkenyl group content is 0.
If it is less than 05 mol%, a substantial curing rate may not be obtained, and if it exceeds 50 mol%, the synthesis becomes difficult and the peeling force becomes heavy.

Examples of the organic group other than the alkenyl group bonded to the silicon atom include alkyl groups such as methyl group, ethyl group and propyl group; aryl groups such as phenyl group and tolyl group; or those bonded to these carbon atoms. Examples thereof include the same or different substituted or unsubstituted monovalent hydrocarbon groups in which a part or all of hydrogen atoms are substituted with halogen atoms, cyano groups and the like. In addition, it is preferable that 50 mol% of the organic groups other than the alkenyl group bonded to the silicon atom are methyl groups with respect to all the organic groups.

The organopolysiloxane is preferably linear, and the substituent bonded to the silicon atom at the terminal is, for example, an alkenyl group, an alkyl group, a hydroxyl group,
It may be any group such as an alkoxy group, but preferably has one or more alkenyl groups. Furthermore, the above organopolysiloxane has a 25
As long as the viscosity at 50 ° C. is 50 cp or more, it may be in any form from oily to raw rubber.

The organohydrogenpolysiloxane which is the component (B) has at least 2, preferably 3 or more, hydrogen atoms bonded to silicon atoms in one molecule. Here, the other organic groups of the organohydrogenpolysiloxane are not particularly limited, but 90 mol% or more of all the organic groups are preferably methyl groups. Specific examples of such an organohydrogenpolysiloxane include (CH ₃ ) HS _i O unit, HS _i O _3/2 unit, (CH ₃ ) ₂ S
Examples thereof include homopolymers or copolymers composed of _i O units and (CH ₃ ) ₃ S _i O _1/2 units, which may be linear, branched or cyclic. Also, this organohydrogenpolysiloxane has a viscosity of 10 at 25 ° C.
˜500 cp, especially 15 to 200 cp is preferred.

The blending amount of the organohydrogenpolysiloxane as the component (B) is determined according to the alkenyl group amount of the alkenyl group-containing organopolysiloxane as the component (A), and is 100 parts by weight of the amount of the component (A). It is necessary that the total amount be 0.1 to 30 parts by weight. If it is less than 0.1 part by weight, the peeling film formation is impaired, and if it is more than 30 parts by weight, the peeling becomes heavy.

As the platinum compound as the component (C), known compounds as an addition reaction catalyst can be used. For example, chloroplatinic acid, an alcohol solution of chloroplatinic acid or an aldehyde solution, chloroplatinic acid and various olefins and vinylsiloxanes can be used. Examples thereof include complexes. The platinum-based compound may be added in a catalytic amount, but from the viewpoint of obtaining a good cured film and economically, 1 to 100 parts by weight of the component (A) in terms of platinum is calculated.
It is preferably in the range of 1,000 ppm.

The following additional components are combined with the main component of the above organopolysiloxane composition. The additive component of the present invention has the following formula in which at least one silicon atom is bonded to one molecule.

[0014]

[Chemical 3] Is an organopolysiloxane having a group represented by (where m is an integer of 2 to 12 and x is an integer of 2 to 5). Organopolysiloxanes containing preferred cyclosiloxane pendants are represented by the general formula:

[0015]

[Chemical 4] [Wherein at least one R is a group represented by Chemical formula 1, the remaining R is a substituent selected from the same or different alkyl groups, aryl groups, alkoxy groups, and hydroxyl groups, and n Is a positive integer. The organopolysiloxane containing a cyclosiloxane pendant preferably has a viscosity at 25 ° C. of 10 to 10 ⁵ cp. The organopolysiloxane containing cyclosiloxane pendant has a viscosity of 10 cp at 25 ° C.
If it is less than 10 ⁵ cp, the effect of lightening the peeling is small, and if it is more than 10 ⁵ cp, it becomes difficult to obtain the effect of lightening the peeling when peeling at a high speed.

The organopolysiloxane containing a cyclosiloxane pendant can be obtained by subjecting an organohydrogenpolysiloxane to a cyclodiorganosiloxane having one alkenyl group for addition reaction using a platinum catalyst. The following formulas (formula 5), (formula 6), (formula 7), (formula 8), (formula 9), and (formula 10) are illustrated as specific examples.

[0017]

[Chemical 5]

[Chemical 6]

[Chemical 7]

Embedded image

[Chemical 9]

[Chemical 10]

The amount of the organopolysiloxane containing a cyclosiloxane pendant as an additive component is 0.1 to 50 parts by weight, preferably 1 part by weight per 100 parts by weight of the main component composition.
~ 20 parts by weight. If it is less than 0.1 part by weight, the effect of lightening the peeling cannot be obtained, and if it is more than 50 parts by weight, the residual adhesion rate decreases. It is free to add other optional components to the above composition, for example, activity inhibitors such as various organic nitrogen compounds, organophosphorus compounds, acetylene compounds, and organic chloro compounds for the purpose of suppressing the catalytic activity of platinum compounds. May be added if necessary.

A method for producing a release paper using the silicone composition of the present invention is to mix a predetermined amount of the above-mentioned main component and additive components and apply the mixture to a substrate such as paper or plastic film. Then, the desired release paper can be obtained by heat curing according to a conventional method. The method of mixing the above components is not particularly limited, but it is preferable to add the platinum catalyst last. Each component may be a single compound or a mixture of two or more kinds. Although the composition of the present invention may be used as it is, toluene,
It is also possible to dilute with an organic solvent such as xylene, hexane, or heptane before use.

[0020]

EXAMPLES The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited to these examples. In the following examples, all viscosities are values at 25 ° C. Further, the peeling force and the residual adhesion rate of the silicone composition were measured by the following methods.

(Peeling Force) A predetermined amount of the peelable silicone composition of the present invention is applied to the surface of a thin film or sheet substrate and heated in a hot air dryer at a predetermined temperature for a predetermined time to form a cured film. After this, apply an acrylic solvent adhesive, Olivine BPS-5127 (manufactured by Toyo Ink Mfg. Co., Ltd.) or an acrylic emulsion type adhesive, Olivain BPW-3110H (manufactured by Toyo Ink Mfg. Co., Ltd.) to the cured film surface. And heat-treated at 100 ° C. for 3 minutes. Next, a high-quality paper with a basis weight of 64 g / m ² was attached to the treated surface, aged at 25 ° C. for 20 hours, and then the sample was cut into a width of 5 cm and peeled at an angle of 180 ^° using a tensile tester. The force (g) required to pull the laminated paper at a speed of 0.3 m / min and 60 m / min and peel it was measured.

(Residual Adhesion Rate) A cured film 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, and then a polyester tape / lumirror 31 was formed on the surface.
B [manufactured by Nitto Denko Co., Ltd.] was attached, 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 attached to a stainless steel plate. Next, the treated paper is peeled from the stainless steel plate at an angle of 180 ^° at a peeling speed of 0.3 m / min, and the force (g) required for peeling is measured, and a separate untreated standard tape is peeled from the stainless steel plate. The force (g) required for was measured, and these ratios were taken and expressed as a percentage.

(Example 1) 100 parts by weight of dimethylpolysiloxane having a viscosity of 400 cp and having a molecular chain end blocked with a dimethylvinylsilyl group, the molecular chain end blocked with a trimethylsilyl group, and containing 20 mol% of a dimethylsiloxane unit. Methyl hydrogen polysiloxane 2.0 with a viscosity of 20 cp
Parts by weight, 10 parts by weight of dimethylpolysiloxane (Chemical Formula 5) having cyclosiloxane at the terminal of the above-mentioned molecular chain, and 0.25 parts by weight of 1-ethynyl-1-cyclohexanol are mixed and stirred uniformly. The silicone composition was prepared by adding the complex to 100 ppm in terms of platinum amount. Next, this composition was coated on polyethylene laminated paper so that the silicone coating amount would be 0.8 g / m ² and cured at 140 ° C. for 30 seconds, and the peeling force and the residual adhesion rate of these were measured. The results are shown in Table 1.

Example 2 The end of the molecular chain was blocked with a dimethylvinylsilyl group, and the methylvinylsiloxy unit was 1.5.
Mol% rubbery methyl vinyl dimethyl polysiloxane
Methyl hydrogen polysiloxane with a viscosity of 30 parts by weight, 100 parts by weight of which the molecular chain ends are blocked with trimethylsilyl groups.
2.4 parts by weight, 20 parts by weight of dimethyldiphenylpolysiloxane (Chemical Formula 9) having cyclosiloxane at the above-mentioned molecular chain end and side chain, 1-ethynyl-1-cyclohexanol
Dissolve 0.25 parts by weight of toluene in 900 parts by weight, and further add platinum-vinylsiloxane complex to the entire system in an amount of 10 in terms of platinum.
A silicone composition was prepared by adding so that the concentration would be 0 ppm. Next, this composition was applied to polyethylene laminated paper so that the amount of silicone applied would be 0.8 g / m ² and applied at 140 ° C.
After being cured for 30 seconds, the peeling force and the residual adhesion rate were measured. The results are shown in Table 1.

(Comparative Example 1) Dimethylpolysiloxane having cyclosiloxane at the molecular chain terminal in Example 1 (Chemical formula 5)
A silicone composition was prepared in the same manner as in Example 1 except that the above was not blended, and a coating film was formed in the same manner as in Example 1, and the peeling force and the residual adhesion rate thereof were measured. The results are shown in Table 1.

Comparative Example 2 Except that in Example 2, 60 parts by weight of dimethyldiphenylpolysiloxane having cyclosiloxane at the end and side chain of the molecular chain was blended.
A silicone composition was prepared in the same manner as above, a coating film was formed in the same manner as in Example 2, and the peeling force and the residual adhesion rate of these were measured. The results are shown in Table 1.

[0027]

[Table 1]

[0028]

As described above, the peelable silicone composition of the present invention provides a peeling film which can be peeled off lightly at the time of peeling at low speed and high speed, and has a small decrease in residual adhesion rate. Therefore, by using the composition of the present invention, it is possible to speed up the rewinding step during adhesive paper production, the dust removing step during adhesive label production, the label sticking step, etc., and streamline the process to improve workability. Can be improved.

Claims (2)

[Claims] 1. A 100 parts by weight of a main component containing an organopolysiloxane that cures to form a peelable film, and a group represented by the following (Chemical Formula 1) bonded to at least one silicon atom in one molecule ( Where m is an integer from 2 to 12 and x is 2
An integer of 5) and a viscosity at 25 ° C. of 10 to 10 ⁵ cp as an additive component of organopolysiloxane (0.1 to 50 parts by weight). [Chemical 1] 2. A main component containing an organopolysiloxane that cures to form a peelable film has (A) an alkenyl group bonded to at least two silicon atoms in one molecule, and has a viscosity at 25 ° C. 5. An organopolysiloxane of 50 cp or more, (B) an organohydrogenpolysiloxane having at least two hydrogen atoms bonded to silicon atoms in one molecule, and (C) a platinum-based addition reaction catalyst. The peelable silicone composition according to 1.