JPH04272959A - Releasing silicone composition - Google Patents

Abstract

PURPOSE:To provide a silicone composition for heavy-duty release paper which changes little in release force with time and is good in adhesion to a substrate and its cured product. CONSTITUTION:The title composition comprises 100 pts.wt. organopolysiloxane having at least two Si-bonded vinyl groups in the molecule, 0.1-20 pts.wt. organohydrogenpolysiloxane having at least two Si-bonded hydrogen atoms in the molecule, 3-50 pts.wt.addition reaction-type silicone tackifier, and an addition reaction catalyst in an amount sufficient to form a cured film, and its cured product.

Description

[Detailed description of the invention]

0001

FIELD OF THE INVENTION This invention relates to silicone compositions, and more particularly to silicone compositions used in release papers.

0002

[Prior Art] Addition-reactive organopolysiloxane compositions with releasable properties are widely used as adhesives for pressure-sensitive adhesive labels, pressure-sensitive adhesive tapes, wallpapers, solar-shielding films, etc. that do not require a relatively large peeling force. It is used.

However, when this is used as an adhesive for process papers, double-sided adhesive tapes, etc. that require a relatively large peeling force, the peeling force decreases over time, and the adhesion is also insufficient. There were drawbacks. Therefore, attempts have been made to incorporate other resins such as urethane resins and inorganic fillers in addition to siloxane, but it has been difficult to uniformly mix these. In addition, attempts have been made to change the blending ratio of each component that makes up the composition and to change the organic groups bonded to the organopolysiloxane, the main component, but the peeling force still changes too much over time to be practical. Intolerable.

[0004] Addition reaction type organopolysiloxane compositions include, for example, solvent-soluble polysiloxanes consisting of (CH3)3 SiO1/2 units and SiO2 units, and (CH3)3 SiO1/2 units, (CH3)2
(CH2 = CH)SiO1/2 unit and SiO2
It has also been proposed to blend a solvent-soluble copolymer consisting of R3 SiO1/2 units (R represents a hydrocarbon group) and SiO2 units (JP-A-52-8
No. 6985).

[0005]

[Problems to be Solved by the Invention] However, since most of these copolymers do not cure, they have the drawback of greatly reducing the adhesive strength and tack of the pressure-sensitive adhesive itself. When a hydrogen atom, a vinyl group, an allyl group, etc. are used, the reduction in curability, adhesive strength as a pressure-sensitive adhesive, and tack is improved, but there is a drawback that the peeling force changes significantly over time. Furthermore, since the solution of the solvent-soluble polysiloxane and the like has a low viscosity, adding a large amount of this solution has the disadvantage that the viscosity of the treatment liquid decreases, resulting in a decrease in coating properties.

On the other hand, it is possible to use a condensation reaction type organopolysiloxane instead of an addition reaction type organopolysiloxane composition to change the type of organic group bonded to the silicon atom of the siloxane in the composition. It is also possible to change the blending ratio of each component in the product, or to add resins such as urethane resin, melamine resin, polyvinyl alcohol, ethyl cellulose, etc., since it is a condensation reaction type and it is easy to mix resins. Although attempts have been made, these methods have the disadvantage that they have insufficient curability, tend to increase the viscosity of the coating solution, and furthermore have the disadvantage that the coating solution becomes non-uniform, resulting in a decrease in coating properties.

[0007] As a result of intensive studies in order to solve these drawbacks, the inventors of the present invention found that by adding an addition reaction type silicone adhesive to a conventional addition reaction type organopolysiloxane composition, a heavy-duty release agent can be easily obtained. The present invention was achieved based on the discovery that it can be made into a silicone composition and that the peeling force changes little over time.

[0008] Accordingly, the first object of the present invention is to provide a silicone composition for release paper, which shows little change in release force over time, has a good residual adhesion rate, and has good adhesion to a base material such as paper. It is in. A second object of the present invention is to provide a silicone composition for heavy-duty release with little change in release force over time.

[0009]

[Means for Solving the Problems] The above-mentioned objects of the present invention are as follows: (a): 100 parts by weight of an organopolysiloxane having at least two vinyl groups directly bonded to silicon atoms in one molecule; (b): 1 0.1 to 20 parts by weight of an organohydrodiene polysiloxane having at least two hydrogen atoms directly bonded to silicon atoms in the molecule, (c): 3 to 50 parts by weight of an addition reaction silicone adhesive, and (d): cured film This was achieved by a release paper silicone composition comprising an addition reaction catalyst in an amount sufficient to form an addition reaction catalyst.

The organopolysiloxane that can be used as component (a) of the invention has at least two vinyl groups in one molecule that are directly bonded to a silicon atom. There are no particular limitations on monovalent groups other than vinyl groups that are directly bonded to silicon atoms. Specific examples of monovalent groups other than vinyl include alkyl groups such as methyl, ethyl, propyl, and butyl, cycloalkyl groups such as cyclopentyl and cyclohexyl, cycloalkyl groups such as cyclohexyl, and phenyl. aryl groups such as naphthyl groups, and monovalent hydrocarbon groups such as naphthyl groups.
In particular, it is preferable that 80 mol% or more of the organic groups other than vinyl groups are methyl groups.

The molecular structure of the organopolysiloxane is not particularly limited, but it should have a linear molecular structure, have a viscosity of 50 cs or more at 25° C., and have a methyl group or a vinyl group at the end of the molecular chain. It is preferable that the compound is blocked with a phenyl group, a hydroxyl group, or an alkoxy group.

The organohydrodiene polysiloxane that can be used as component (b) of the present invention is not particularly limited, except that it must have at least two hydrogen atoms directly bonded to a silicon atom in one molecule. The molecular structure may be linear, branched or cyclic. The viscosity may also be in the range of several cs to several hundred thousand cs. Specific examples of the organohydrodiene polysiloxane include the following siloxanes.

[Chemical formula 1]

[Case 2]

[Chemical formula 3]

[C4]

[C5]

[C6]

Average compositional formula (MeSiO3/2)i
(MeHSiO)j (Me3 SiO1/2)k
A cohydrolyzed condensate represented by However, in the above compositional formula, Me represents a methyl group, and i, j, and k each represent a positive integer.

The amount of the organohydrodiene polysiloxane as the component (b) is from 0.1 to 100 parts by weight of the organopolysiloxane as the component (a).
The range is 20 parts by weight. (b) The blending amount of the component is 0.1
If it is less than 20 parts by weight, the curability of the silicone composition for release paper of the present invention will be insufficient, while if it is added in excess of 20 parts by weight, there will be no noticeable increase in the effect, and instead it will cause poor curing, and it will also be economically disadvantageous. It is also disadvantageous.

[0015] The addition reaction type silicone adhesive as component (c) used in the composition of the present invention is not particularly limited, but one with high adhesive strength and strong cohesive force is preferable. is 500g/25mm width or more (measured on a SUS304 stainless steel plate in an atmosphere of 25°C and 65%RH) and has a holding force of 0.
It is preferable that the width is 3 mm/25 mm or less (when a static load of 1 kg is applied).

[0016] The method for producing the silicone adhesive described above is known, and generally consists of vinyl group-containing diorganopolysiloxane and (R3 SiO0.5)a (R2 SiO)b.
(RSiO1.5)C (SiO2)d (wherein,
R is a monovalent hydrocarbon group, and a, b, c, and d represent the mole fraction of each siloxane unit. a=0.1-0.6,
b=0-0.45, c=0-0.3, d=0.3-2.
It can be produced by carrying out an equilibration reaction with an organopolysiloxane represented by 0).

[0017] The blending amount of the silicone adhesive is as follows (
The amount ranges from 3 to 50 parts by weight per 100 parts by weight of the organopolysiloxane as component (a). If it is less than 3 parts by weight, there is almost no effect on the peeling force, and if it is used in excess of 50 parts by weight, the curing properties of the coating of the composition will decrease, making it impossible to separate the coating from the base material such as paper. .

The addition reaction catalyst used as component (2) in the composition of the present invention promotes the addition reaction between component (a) and component (b) or component (c) and component (b), resulting in curing. Used to form a coating. Examples of such addition reaction catalysts include platinum black, chloroplatinic acid, chloroplatinic acid-olefin complex, chloroplatinic acid-alcohol coordination compound, rhodium, rhodium-olefin complex, and the like.

[0019] The addition reaction catalyst described above is based on the total weight of the organopolysiloxane as the component (a), the organohydrodiene polysiloxane as the component (b), and the addition reaction type silicone adhesive as the component (c). , 5 to 1,000 ppm as the amount of platinum or the amount of rhodium (
Weight ratio) is preferable in order to form a sufficiently cured film, but the amount can be increased or decreased as appropriate depending on the reactivity of the components or the desired curing speed.

The composition of the present invention can be easily produced by uniformly mixing each of the components (a) to (d) above. The composition of the present invention may further contain a known reaction control agent, an inorganic filler such as silica, or a pigment, if necessary.

When producing a release paper or the like using the composition of the present invention, the composition of the present invention may be used directly or after diluting with a suitable organic solvent and then coated with a bar coater, roll coater, reverse coater, or gravure coater. It is applied to a base material such as paper by a known application method such as .

The amount of the composition of the present invention to be applied to the substrate varies depending on the type of material of the substrate to be applied, but it is preferably 0.2 to 2.0 g/m 2 in terms of solid content. The base material coated with the composition of the present invention as described above was
By heating at ~180°C for 5 to 60 seconds, a cured film can be formed on the surface of the composition, and a release paper having desired peel strength, residual adhesive strength, etc. can be obtained. Therefore,
By using the composition of the present invention, it is possible to produce a process paper or a double-sided adhesive tape with good performance.

[0023]

[Effects of the Invention] Since the silicone composition for release paper of the present invention uses addition reaction type silicone, it has good adhesion to substrates such as paper. In addition, since the addition reaction type silicone adhesive used as an additive has a high viscosity, even if a large amount of it is added, the viscosity of the composition will not be reduced.
Furthermore, since the release force can be changed depending on the amount added, a release paper having a desired release force from light release force to heavy release force can be easily produced.

[0024]

EXAMPLES The present invention will be explained in more detail with reference to Examples below, but the present invention is not limited thereto. In addition, "parts" indicating the amount added indicate "parts by weight", and the viscosity is 2
The value is shown at 5°C. In addition, the peeling force shown in this example,
The residual adhesion rate, adhesion and curing properties were measured as follows.

(1) Peeling force 1-1. After applying the initial peel strength composition, the substrate on which a cured film was formed by heat treatment was left in a room at 25°C for 24 hours, and an acrylic solvent-based adhesive (Olivine BPS) was applied to the surface of the cured film.
-8170 manufactured by Toyo Ink Manufacturing Co., Ltd. (trade name) was applied uniformly using an applicator to a thickness of 130 μm in a wet state.

[0026] After the obtained coated material was heated at 100°C for 3 minutes, a 64 g/m2 high-quality paper (hereinafter referred to as surface paper) was pasted on the top surface of the coated material and left in a room at 25°C for 1 day. . Next, using a tensile tester, the tensile speed was 0.
The surface paper was pulled at 3 m/min at a pulling angle of 180°, and the force (g/5 cm) required for peeling at this time was measured.
This was taken as the initial peel force value.

1-2. Aging release force After applying the composition, heat treatment was performed to form a cured film, and the substrate was left in a constant temperature bath at room temperature or 70°C for a predetermined period of time (referred to as aging). It was measured. This measured value was defined as the aging peeling force value.

(2) Residual adhesion rate After applying the composition and heat-treating the base material to form a cured film, leave it in a room at 25°C for 24 hours, and then apply Nitto Polyester Tape No. 1 on the cured film surface. 31B (manufactured by Nitto Denko Corporation, trade name) was pasted. Next, the tape was left in a constant temperature bath at 70°C for 20 hours with a load of 20 g/cm2 applied to the tape, and then the tape was peeled off.Then, the peeled tape was pasted on a stainless steel plate again, and a 2 kg tape roller was applied to the tape. I made one round trip on the top. After the tape was left indoors for 30 minutes, the force required for peeling was measured in exactly the same manner as in 1-1 above, and this value was taken as the peeling force value of the stainless steel plate. Further, the peeling force was measured in the same manner as in 2-1 except that a Teflon plate was used instead of the substrate on which the cured film was formed, and this value was used as a blank value. The value expressed as a percentage of the peeling force value of the stainless steel plate with respect to the blank value was defined as the residual adhesion rate.

(3) A fixed amount of the adhesive composition was applied to polyethylene laminate paper and heated at 100° C. for 20 seconds to form a cured film. Rub the resulting film with your fingers and visually observe the condition of the cured film. If the cured film does not fall off or become cloudy, it is rated ○, if it does not fall off but is cloudy, it is △, if it falls off, it is marked ×.
Adhesion was evaluated as follows.

(4) Curing property After applying a certain amount of the prepared silicone composition to a polyethylene laminate paper, it is cured under certain conditions.
I let it happen. Rub the surface of the cured silicone with your fingers for 5 to 10 minutes.
Visually observe the hardened surface after rubbing several times. If there is no falling off or clouding, ◎, if there is no falling off but there is slight clouding, ○, if there is no falling off but there is slight clouding, △.
The curing property was evaluated with a score of "x" when there was no shedding but there was cloudiness.

[0031]

[Example 1] Vinyl group-containing dimethylpolysiloxane with both ends capped with vinyl dimethylsilyl groups (vinyl value 0)
．． 02 mol/100g, degree of polymerization 8,000) 30 parts, viscosity 20 cp, 0.5 methylhydrodiene polysiloxane with both ends capped with trimethylsiloxy groups
Composition A was prepared by uniformly dissolving 1 part and 1 part of 3-methyl-1-butyn-3-ol in 68.5 parts of toluene. The viscosity of Composition A was 5,600 cp.

On the other hand, vinyl group-containing dimethylpolysiloxane (vinyl value 0.05 mol/100 g, degree of polymerization approximately 8,000) 4 whose both ends are blocked with vinyl dimethylsilyl groups
0 part is replaced with trimethylsiloxy group unit and SiO2 unit (
3 of polymethylsiloxane with a molar ratio of 0.8/1)
Composition B was prepared by adding an appropriate amount of potassium hydroxide as a catalyst to 60 parts of a 0% by weight toluene solution, followed by heat treatment at 100° C. for 5 hours, and then neutralizing the catalyst. The composition B has a viscosity of 50,000 cp and an adhesive strength of 1.1
00g/25mm width, holding force is 0.15mm/25mm
It was wide.

A mixture of Composition A and Composition B in various proportions was diluted with toluene to give a solid content of 5% by weight, and 50 pp by weight of platinum-vinylsiloxane complex was added to the solution.
liquids having various compositions shown in Table 1 were prepared. The obtained liquid was applied to polyethylene laminate paper using a wire bar in a coating amount of approximately 0.6 g/m2 (dry weight) to obtain coated products having the respective compositions described above. Table 2 shows the results of measuring the adhesion, peeling force, and residual adhesion rate (referred to as characteristics) of the obtained coating.

[0034]

[Comparative Example 1] Instead of liquid B (containing addition-type silicone adhesive) used in Example 1, (CH3)3SiO1
60% by weight of toluene-soluble methylpolysiloxane with /2 units/SiO2 units = 42/58 (mole ratio)
A coated product was obtained in the same manner as in Example 1 except that a toluene solution (referred to as liquid C) was used, and the properties were measured. Table 2 shows the results.

[0035]

[Comparative Example 2] Instead of liquid B (containing addition-type silicone adhesive) used in Example 1, (CH3)3SiO1
/2 unit/(CH2 = CH)(CH3)2 Si
A toluene solution containing 60% by weight of toluene-soluble vinylmethylpolysiloxane with O1/2 units/SiO2 units = 46/4/50 (mole ratio) (referred to as liquid D)
A coated product was obtained in the same manner as in Example 1, except that the following was used, and the properties were measured. Table 2 shows the results.

[0036]

[Comparative Example 3] A coated product was obtained in the same manner as in Example 1 except that the B liquid (containing an addition-type silicone adhesive) used in Example 1 was not used, and the properties were measured. Table 2 shows the results.

[Table 1] ──────────────────────────
──────────── Compound Fruit
Example 1 Comparative example 1 Comparative example 2 Comparative example 3 Sample No.
1 2 3 4 5
6 7 8 9──────
──────────────────────────
────── Composition A 100
100 100 100 100
100 100 100 100
──────────────
──────────────── Same B
1.5 2.5 5
10 ──────────
──────────────────── Liquid C

5 10
──────────────────
────────────── D liquid

5 10
────────────
────────────────── Catalyst
1 1 1
1 1 1 1
1 1
──────────────────────────
──── Toluene 500
500 500 500 500
500 500 500 500 ────
──────────────────────────
────────

[0037]

[Table 2] ──────────────────────────
──────────── Compound
Implementation example 1
Comparative example 1 Same 2 Same 3 Sample No.
1 2 3
4 5 6 7 8
9────────────────────────
──────────── Adhesion
○ ○ ○ ○
× × △ △ ○─────
──────────────────────────
──────Peeling force (g/5cm) A Room temperature 1 day 95 100
170 305 110 200
140 210 80 Zing
──────────────────────
───────Same room temperature 7 days 85
100 170 300 10
0 180 110 200 65
──────────
────────────────── Same room temperature 30 days 73 95 160
300 95 170 90
140 40
──────────────────────────
───Same 70℃ 1 day 65 9
0 160 295 90
160 45 60 24 ──────
──────────────────────────
─────Residual adhesion rate (%) 100 10
0 100 100 88
83 100 98 100──────
──────────────────────────
──────

[0038]

[Example 2] 100 parts of dimethylsiloxane having a viscosity of 1,000 cp and having both ends capped with vinyldimethylsilyl groups was mixed with methylhydrodiene polyamide having a viscosity of 20 cp and having both ends capped with trimethyl groups. Composition E was prepared by uniformly mixing 12 parts of siloxane.

On the other hand, Composition F was prepared by removing the solvent of Composition B in Example 1 by distillation. Next, a certain amount of composition E was taken, and a predetermined amount of composition F was added to each of them, and then a vinylsiloxane complex of chloroplatinic acid (catalyst) was added to each of them so that the amount of platinum was 50 ppm by weight. Coating liquids Nos. 10 to 12 were prepared. Approximately 6 g/approx. of each coating solution was applied to polyethylene laminate paper.
Coating was carried out using an offset printing machine so that the coating thickness was 2 m2, thereby obtaining coated products of each coating solution. Table 3 shows the results of measuring the properties of each of the obtained coated products.

[0040]

[Comparative Example 4] A coated product was obtained in exactly the same manner as in Example 2 except that Composition F was not added, and the results of measuring the above characteristics are shown in Table 3.
It was shown to.

[Table 3] ────────────────────
─────── Compound
Comparative example implementation
Example Sample No.
10 11 12
────────────────────
──────── Composition E
100 100
100 Composition F
0 5 1
0 ──────────────────
───────── Adhesion
○ ○
○ ──────────
──────────────── Peeling force Room temperature January 140
200 300 Room temperature July
76 190 2
90 70℃ 1 day
30 180 29
0 ────────────────────
──────── Residual adhesion rate (%)
100 100
100 ──────────────
───────────── These results demonstrate that the change in release force of the silicone composition of the present invention over time is extremely small.

Claims (2)

[Claims] Claim 1: (a): 100 parts by weight of an organopolysiloxane having at least two vinyl groups directly bonded to silicon atoms in one molecule; (b): at least two hydrogen atoms directly bonding to silicon atoms in one molecule; 0.1 to 20 parts by weight of an organohydrodiene polysiloxane, (c): 3 to 50 parts by weight of an addition reaction silicone adhesive, and (d):
A release silicone composition comprising an addition reaction catalyst in an amount sufficient to form a cured film. 2. A cured product obtained by curing the composition of claim 1.