JP3073893B2 - Peelable silicone composition - Google Patents

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 peels off at a low release speed and a high release speed with a light release force and gives a release film with a small decrease in the residual adhesive ratio. And a release silicone composition that can be used as a release liner for labels.

[0002]

2. Description of the Related Art Conventionally, a film of a silicone composition has been formed on a base material surface to prevent adhesion and sticking of a base material such as paper, processed paper, plastic film or the like to an adhesive substance, thereby improving releasability. Grants have been made. In this case, as a method of forming a silicone film on the substrate surface, a release compound is formed by an addition reaction between an organopolysiloxane containing an aliphatic unsaturated group and an organohydrogenpolysiloxane using a platinum compound as a catalyst. How to form a
There is known 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. All of the silicone compositions used in these methods are of the heat-curing type in which a film is formed by heating, and depending on their properties, a solvent type in which silicone is dissolved in an organic solvent such as toluene, or a dispersion in water. Emulsion type and solventless type consisting of silicone only. Further, in these releasable silicone compositions, a phenyl group-containing non-functional compound is used in order to improve workability in a rewinding step in the production of an adhesive paper, a scrap removing step and a label attaching step in the production of an adhesive label. It has been proposed in Japanese Patent Publication No. 3-52498 to add an organopolysiloxane to achieve light peeling during high-speed peeling.

[0003]

However, when a non-functional organopolysiloxane containing a phenyl group is added to the peelable silicone composition, the peeling force is reduced, but the residual adhesion rate is greatly reduced due to blooming of the non-reactive component. At present, it is difficult to improve the workability. The present invention has been made in order to solve the above problems, and provides a release silicone composition which gives an excellent release film which is light at the time of low-speed and high-speed release and has a small decrease in the residual adhesion rate. The purpose is to:

[0004]

Means for Solving the Problems The present inventors have conducted intensive studies to achieve the above object, and as a result, have found that a main component containing an organopolysiloxane which cures to form a peelable film.
At 25 ° C. having parts by weight and a group represented by the following formula (where m is an integer of 2 to 12, x is an integer of 2 to 5) bonded to at least one silicon atom in one molecule. Viscosity 10-10
^A release silicone composition comprising 0.1 to 50 parts by weight of an organopolysiloxane that is ⁵ cp can give a light release force at the time of peeling at a low speed and a high speed. Therefore, the present invention was found to be able to streamline the process by speeding up the rewinding process in the production of adhesive paper and the scrap removal process and the label attaching process in the production of the adhesive label, and improve the workability, and completed the present invention. did.

[0005]

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As the main component in the present invention, a conventionally known release composition can be used as it is. In addition to the above-described addition-reaction type and condensation-reaction type compositions, for example, acrylic silicone is cured with an electron beam. A composition or a composition obtained by curing a composition obtained by adding a photopolymerization initiator to acrylic silicone with ultraviolet rays can also be used. Among such compositions, addition-reaction-type ones have a low release force and a high residual adhesion rate. Therefore, in the present invention, the addition-reaction type is added as a main component of a composition that cures to form a release film. A reactive organopolysiloxane was used.

The addition reaction type organopolysiloxane compositions which can be used as the main components in the present invention are each known, and comprise the following three components. (A) an organopolysiloxane having at least two alkenyl groups bonded to at least two silicon atoms in one molecule and having a viscosity of 50 cp or more at 25 ° C. (B) hydrogen bonded to at least two silicon atoms in one molecule Organohydrogenpolysiloxane having atoms (C) Platinum-based addition reaction catalyst Here, the organopolysiloxane of the 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, and a dodecenyl group, and the alkenyl group is preferably a vinyl group from the viewpoint of economy. The alkenyl group accounts for 0.05 to 50 mol%, especially 0.2 to 10 mol%, based on the total organic groups in the organopolysiloxane.
It is preferred that the content be contained in a mole%. Alkenyl group content is 0.
If the amount is less than 05 mol%, a substantial curing rate may not be obtained. If the amount exceeds 50 mol%, the synthesis becomes difficult and the peeling force becomes heavy.

The organic group other than the alkenyl group bonded to the silicon atom includes, for example, an alkyl group such as a methyl group, an ethyl group and a propyl group; an aryl group such as a phenyl group and a tolyl group; Same or different substituted or unsubstituted monovalent hydrocarbon groups in which part or all of the hydrogen atoms have been substituted with halogen atoms, cyano groups, and the like can be mentioned. The organic group other than the alkenyl group bonded to the silicon atom is preferably 50% by mole of the total organic group as a methyl group.

The organopolysiloxane is desirably linear, and the substituent bonded to the terminal silicon atom may be, 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. Further, the above organopolysiloxane is 25% in view of the performance of the formed film.
As long as the viscosity at 50 ° C. is 50 cp or more, any form from oily to raw rubber may be used.

The organohydrogenpolysiloxane as the component (B) has at least two, preferably three or more hydrogen atoms bonded to silicon atoms in one molecule. Here, other organic groups of the organohydrogenpolysiloxane are not particularly limited, but it is preferable that 90 mol% or more of all organic groups are methyl groups. Specific examples of such an organohydrogenpolysiloxane include (CH ₃ ) HS _i O units, HS _i O _3/2 units, (CH ₃ ) ₂ S
_i O _{units, (CH 3) 3 S i} O 1/2 composed of units homopolymer - like or copolymers are exemplified, these linear, branched, may be any of circular. The organohydrogenpolysiloxane has a viscosity of 10 at 25 ° C.
-500 cp, particularly preferably 15-200 cp.

The amount of the organohydrogenpolysiloxane of the component (B) is determined according to the alkenyl group content of the alkenyl group-containing organopolysiloxane of the component (A). Must be in the range of 0.1 to 30 parts by weight. When the amount is less than 0.1 part by weight, the formation of the peelable film is impaired, and when the amount is more than 30 parts by weight, the peeling becomes heavy.

As the platinum compound as the component (C), those known as addition reaction catalysts can be used. For example, chloroplatinic acid, an alcohol solution or aldehyde solution of chloroplatinic acid, or a mixture of chloroplatinic acid with various olefins or vinylsiloxanes can be used. Complexes and the like. The addition amount of the platinum compound may be a catalyst amount, but from the viewpoint of obtaining a good cured film and from an economic viewpoint, 100 parts by weight of the component (A) is 1 to 1 in terms of platinum amount.
It is preferred to be in the range of 1,000 ppm.

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

[0014]

Embedded image (Where m is an integer of 2 to 12, x is an integer of 2 to 5). A preferred organopolysiloxane containing a cyclosiloxane pendant is represented by the following general formula.

[0015]

Embedded image [Where R is at least one group represented by the formula (1), and the remaining Rs are substituents selected from the same or different alkyl groups, aryl groups, alkoxy groups, and hydroxyl groups; Is a positive integer. ] The viscosity of the 25 ° C. of the organopolysiloxane containing cyclosiloxane pendant 10 to 10 ⁵ cp are preferred. The viscosity at 25 ° C of organopolysiloxane containing cyclosiloxane pendant is 10cp
If it is less than 50, the effect of lightening the peeling is small. If it is larger than 10 ⁵ cp, it is difficult to obtain the effect of lightening the peeling when the film is peeled at a high speed.

As described above, the organopolysiloxane containing a cyclosiloxane pendant can be obtained by subjecting an organohydrogenpolysiloxane to an addition reaction of a cyclodiorganosiloxane having one alkenyl group using a platinum-based catalyst. As specific examples, the following formulas (Chem. 5), (Chem. 6), (Chem. 7), (Chem. 8), (Chem. 9), and (Chem. 10) are exemplified.

[0017]

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

A method for producing a release paper using the silicone composition of the present invention comprises mixing a predetermined amount of the above-mentioned main component and an additive component, applying the mixture to a base material such as paper, plastic film, or the like. Next, the desired release paper can be obtained by heating and curing according to a conventional method. The method for 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. Although the composition of the present invention may be used as it is, toluene,
It is also possible to use it after diluting it with an organic solvent such as xylene, hexane or heptane.

[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, the viscosities are all 25 ° C. The peeling force and the residual adhesion of the silicone composition were measured by the following methods.

(Release Force) A predetermined amount of the releasable 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 that, an acrylic solvent adhesive, Olivine BPS-5127 (manufactured by Toyo Ink Manufacturing Co., Ltd.) or an acrylic emulsion type adhesive, Olivine BPW-3110H (manufactured by Toyo Ink Manufacture, Inc.) is applied to the cured film surface. Then, heat treatment was performed at 100 ° C. for 3 minutes. Next, high-quality paper with a basis weight of 64 g / m ² was stuck to the treated surface, aged at 25 ° C for 20 hours, the sample was cut into 5 cm widths, and peeled at a 180 ^° angle using a tensile tester. The force (g) required to pull and peel the bonded paper at a speed of 0.3 m / min and 60 m / min was measured.

(Residual Adhesion Rate) After a cured film of the silicone composition was formed on the surface of the substrate in exactly the same manner as in the case of the peeling force measurement, a polyester tape mirror 31 was formed on the surface.
B [manufactured by Nitto Denko Corporation] was adhered, heated and aged at 70 ° C. for 20 hours under a load of 20 g / cm ² , and then the tape was peeled off and adhered to a stainless steel plate. Next, the treated paper is peeled off from the stainless steel plate at an angle of 180 ^° at a peeling speed of 0.3 m / min, 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 was determined 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 terminal capped with a dimethylvinylsilyl group, and 100 mol% of a molecular chain terminal capped with a trimethylsilyl group, containing 20 mol% of dimethylsiloxane units Methyl hydrogen polysiloxane 2.0 with viscosity 20cp
Parts by weight, 10 parts by weight of dimethylpolysiloxane having a cyclosiloxane at the end of the molecular chain (formula 5), and 0.25 parts by weight of 1-ethynyl-1-cyclohexanol are mixed and stirred uniformly. A silicone composition was prepared by adding the complex so as to be 100 ppm in terms of platinum. Next, this composition was applied to polyethylene-laminated paper so that the amount of silicone applied was 0.8 g / m ^2, and cured at 140 ° C. for 30 seconds, and the peeling force and the residual adhesion rate were measured. Table 1 shows the results.

(Example 2) A molecular chain terminal was blocked with a dimethylvinylsilyl group, and a methylvinylsiloxy unit was 1.5
Mol% rubbery methylvinyldimethylpolysiloxane
100 parts by weight, methyl hydrogen polysiloxane with a viscosity of 30 cp, whose molecular chain ends are blocked with trimethylsilyl groups
2.4 parts by weight, 20 parts by weight of dimethyldiphenylpolysiloxane having a cyclosiloxane at the terminal and side chains of the above-mentioned molecular chain, 1-ethynyl-1-cyclohexanol
0.25 parts by weight was dissolved in 900 parts by weight of toluene, and a complex of platinum and vinylsiloxane was added to the entire system in an amount of 10% in terms of platinum.
A silicone composition was prepared by adding 0 ppm. Next, this composition was applied to polyethylene laminated paper so that the silicone coating amount was 0.8 g / m ^2, and 140 ° C.
And cured for 30 seconds, and their peeling force and residual adhesion rate were measured. Table 1 shows the results.

Comparative Example 1 Dimethylpolysiloxane having cyclosiloxane at a molecular chain terminal in Example 1
A silicone composition was prepared in the same manner as in Example 1 except that no was blended, and a coating film was formed in the same manner as in Example 1, and the peeling force and the residual adhesion rate were measured. Table 1 shows the results.

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

[0027]

[Table 1]

[0028]

As described above, the peelable silicone composition of the present invention can be peeled lightly at the time of peeling at a low speed and a high speed, and gives a peeling film with a small decrease in the residual adhesive ratio. Therefore, by using the composition of the present invention, it is possible to speed up the rewinding step in the production of pressure-sensitive adhesive paper and the scrap removal step in the production of the pressure-sensitive adhesive label, the label sticking step, etc. Can be improved.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-62-25128 (JP, A) JP-A-8-3450 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08L 83/04 C08L 83/05 C08L 83/07 C08G 77/04

Claims (2)

(57) [Claims] 1. A resin composition comprising 100 parts by weight of a main component containing an organopolysiloxane which cures to form a peelable film, and a group represented by the following formula (1) bonded to at least one silicon atom in one molecule. Here, m is an integer of 2 to 12, and x is 2 to
5 integer), peelable silicone composition, wherein the viscosity of 25 ° C. consists organopolysiloxane 0.1 to 50 parts by weight of the additive component is 10 to 10 ⁵ cp with. Embedded image 2. A main component containing an organopolysiloxane which cures to form a peelable film, (A) having at least two alkenyl groups bonded to silicon atoms in one molecule, and having a viscosity at 25 ° C. An organopolysiloxane of 50 cp or more, (B) an organohydrogenpolysiloxane having at least two hydrogen atoms bonded to one silicon atom in one molecule, and (C) a platinum-based addition reaction catalyst. 2. The peelable silicone composition according to 1.