JPH0112786B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention provides a silicone composition for release paper, which has good storage stability at room temperature even after the addition of a catalyst, and cures at low temperatures and in a short time when applied to various substrates. be able to. This invention relates to a silicone composition for release paper that has good peeling stability. (Prior art) A silicone composition for release paper is applied to the surface of a base material such as a film, sheet, or nonwoven fabric made of cellulose, synthetic resin, or synthetic fiber in order to make the surface non-adhesive. is already well known, and for this purpose, vinyl group-containing organopolysiloxane and hydrogen-
So-called addition reaction type silicone compositions, which are mainly composed of organohydrodiene polysiloxanes having silicon bonds, are widely used. However, in order to apply this addition reaction type silicone composition and form a peelable cured film on the surface of the substrate, heat treatment at 130 to 150°C for 30 to 60 seconds is usually required. In order to make paper with poor heat resistance and synthetic resin films such as polyethylene, polypropylene, and vinyl chloride releasable, there was a need for a composition that could form a cured film at low temperatures and in a short time. Therefore, a large amount of platinum-based catalyst was added to cure this silicone composition.
A method of forming a cured film in a short period of time at temperatures below .degree. For this reason, a method of adding an acetylene compound for the purpose of improving storage stability has been proposed (see Japanese Patent Publication No. 44-31476), but 3-methyl-1-butyne-3- Alkyl alcohols such as ol, 3-methyl-1-pentyn-3-ol and 2,5-dimethyl-3-hexyne-2,5-diol have poor compatibility with organopolysiloxanes, and therefore their dispersibility is poor. There is a problem in that the peeling force of a cured film cured in a short time at low temperature is unstable, and in particular, the peeling force over time when adhesive is bonded has a disadvantage that there is a large variation in the peeling force. Another disadvantage is that the dehydrogenation reaction between the alcohol and the organohydrodiene polysiloxane occurs in the presence of a platinum catalyst, resulting in a marked deterioration in the low temperature curing properties of the treatment bath over time. (Structure of the Invention) The present invention relates to a silicone composition for release paper that solves the above-mentioned disadvantages.
An organopolysiloxane having a substantially linear structure having a viscosity of 50 cS or more at °C and at least two vinyl group-silicon bonds in one molecule.
100 parts by weight, (2) organopolysiloxane having at least two hydrogen-silicon bonds in one molecule
0.2 to 50 parts by weight, (3) General formula or (Here, R ¹ , R ² , R ³ , R ⁴ , and R ⁵ are hydrogen atoms or the same or different unsubstituted or substituted aliphatic monovalent hydrocarbon groups having 1 to 10 carbon atoms.)
0.1 to 10 parts by weight of an organosilicon compound having an acetylenically unsaturated group that is compatible with the first component described above and the organopolysiloxane as the second component at 250°C or less, (4) component (1) above as the amount of platinum. 2~
It is characterized by consisting of 500 ppm of platinum-based compounds. That is, the present inventors conducted various studies on silicone compositions for release paper that do not have the disadvantages described above, have good storage safety, and cure at low temperatures and in a short time. When an organosilicon compound having an acetylenically unsaturated group having the general formula shown above is added to the above-mentioned compound, this compound becomes an organosilicon compound and is completely compatible with the organopolysiloxane constituting the addition-reactive silicone composition. Therefore, it acts as an addition reaction inhibitor at room temperature, but this inhibitory effect is immediately released under heating, and it can also react with organohydrodiene polysiloxanes like the acetylene alcohol mentioned above. The inventors have discovered that, by adding this compound, a cured film with peelability can be obtained quickly even at a low temperature of 100°C or less, since it does not inhibit the curing reaction of this composition. The present invention was completed by conducting research on the types and blending ratios of each of these components. The organopolysiloxane as component (1) constituting the composition of the present invention has a vinyl group bonded to at least two silicon atoms in its molecule, and this vinyl group exists both at the end of the molecular chain and in the chain. A substantially linear diorganopolysiloxane having a vinyldimethylsilyl group or a trimethylsilyl group at the end of the molecular chain is exemplified by the following formula. In addition, R ⁶ in this formula is an alkyl group such as a methyl group, ethyl group, propyl group, butyl group, an aryl group such as a phenyl group or tolyl group, or a part or all of the hydrogen atoms bonded to the carbon atoms of these groups. Monovalent hydrocarbon groups other than the same or different unsubstituted or substituted aliphatic unsaturated groups substituted with halogen atoms, cyano groups, etc., preferably at least 50 mol% of which are methyl groups, m, n is an integer, but this diorganopolysiloxane may be used alone or in a mixture of two or more. This diorganopolysiloxane has a low viscosity due to the ease of coating and the performance of the film formed.
50cS or more is preferable. In addition, this (2) component is an organopolysiloxane that has at least two hydrogen-silicon bonds (≡SiH bonds) in the molecule, but from a practical standpoint, it is considered to be an organopolysiloxane that has two ≡SiH bonds in the molecule. is the total amount of 50
% by weight, and the remainder preferably contains at least three ≡SiH bonds in the molecule. This organopolysiloxane includes (CH ₃ )HSiO units, HSiO _1.5 units,
Homopolymers of (CH ₃ ) ₂ HSiO _0.5 units or these and CH ₃ SiO _1.5 units, (CH ₃ ) ₂ SiO units,
An example is a copolymer containing _0.5 units of (CH ₃ ) ₃ SiO, which may be linear, cyclic, or branched.
500cS is preferred. The amount of organopolysiloxane added is preferably 0.2 to 50 parts by weight per 100 parts by weight of component (1) in view of the formation of a cured film and the peelability of the film. Next, as the component (3) constituting the composition of the present invention, the organosilicon compound has the general formula

[expression] or

[Potsutolife]

Put 250g of the composition into a 500ml glass beaker,
Leave to stand at 25°C with stirring, and measure viscosity, curing properties, and peel resistance at predetermined intervals. [Curability] After applying a predetermined amount of the composition to the surface of a thin film or sheet-like substrate, the time (seconds) required for a completely cured film to be formed in a hot air circulation drying oven at a predetermined temperature. Measure. However, this curing test can be done by checking whether the coated surface does not fall off even if you rub it with your fingers.
and when it is not cloudy. [Peel resistance] A predetermined amount of the composition is applied to the surface of a thin film or sheet-like base material, and after heating in a hot air dryer at a predetermined temperature for a predetermined time to form a cured film,
On the cured film surface, apply an acrylic solvent-based adhesive Olivine BPS-5127 (trade name manufactured by Toyo Ink Manufacturing Co., Ltd.), an acrylic emulsion-type adhesive Olivine BPW-3110H (trade name manufactured by Toyo Ink Manufacturing Co., Ltd.), or a rubber solvent. Mold adhesive/Olivine BPS-2411
(product name manufactured by the company) and heat treated at 100℃ for 30 minutes. Next, a laminated paper with a basis weight of 40 g/m ² is pasted on this treated surface, and aged at 25°C under a load of 20 g/cm ² for a predetermined period of time. Using a machine, pull the bonded paper at a peeling speed of 300 mm/min at an angle of 180° and measure the force (g) required to peel it off. [Residual adhesion rate] After forming a cured film of the composition on the surface of the sheet-like base material in the same manner as in the case of peel resistance, polyester tape Lumirror 31B [trade name manufactured by Nitto Electric Industry Co., Ltd.] was applied to the surface. The tape was pasted together and heated at 70°C for 20 hours under a load of 20 g/cm ² , then the tape was removed and pasted onto a stainless steel plate. Next, this treated tape was peeled off from the stainless steel plate at an angle of 180° at a peeling speed of 300 mm/min, and the force (g) required for peeling was measured. The force (g) is measured and expressed as a percentage of the force (g) required to peel the untreated standard tape. Example 1 Dimethylsiloxane, methylvinylsiloxane and rubbery copolymer (vinyl group content 1.0 mol%) 100
25 parts of methylhydrodiene polysiloxane with a viscosity of 100 CP and whose molecular chain ends are blocked with trimethylsilyl groups and the formula

After premixing and dissolving 2.0 parts of an organosilicon compound as a control agent represented by the formula (boiling point 115°C) in 240 parts of toluene,
Immediately before use, 100 parts of the above-mentioned rubbery copolymer was uniformly dissolved in 498 parts of toluene, and a complex salt of platinum and vinyl siloxane was added at 100 ppm in terms of platinum.
Composition A of the present invention was prepared by adding the following. Then, for comparison, instead of the above control agent, the formula

Composition B of Comparative Example 1 was prepared by adding 2.0 parts of 3-methyl-1-butyne represented by the formula (boiling point 104°C);
40 parts to make Composition C of Comparative Example 2 and formula Composition D of Comparative Example 3 was prepared by adding 3.0 parts of 1-ethynyl-1-cyclohexanol (boiling point 180°C) and 3,5 dimethyl-1- (boiling point 150℃)
Composition E of Comparative Example 4 was made by adding 3.0 parts of hexyne-3-ol. Next, the pot life, curability, peel resistance, and residual adhesion rate of these compositions A to E were examined using the methods described above, and the results shown in Tables 1 to 3 were obtained. This curing property was measured by coating 0.8 g/m ² of these compositions on polyethylene laminated kraft paper at 80°C or 100°C. The peel resistance and residual adhesion rate were measured by coating 0.8 g/m ² of these compositions on polyethylene laminated kraft paper. This shows the results obtained when coated on laminated kraft paper and heat-treated at 100°C for 30 seconds. In addition, in Comparative Examples 1 to 4, the viscosity change after addition of the catalyst was similar to that in Example 1 as shown in Table 3, but as shown in Tables 1 and 2, these Two hours after addition of the catalyst, the curing properties were completely poor, and the peeling stability and residual adhesion rate were also extremely poor. In addition, for comparison, the physical properties of the composition (Comparative Example 5) F in which no control agent was added were examined under the same conditions as above, but in this case, a platinum compound as a catalyst was added and mixed. This gelatinized during the process, and it also cured quickly enough that it could not be coated on paper.

【table】

【table】

[Table] Example 2 100 parts of a copolymer of dimethylsiloxane and methylvinylsiloxane with a viscosity of 1000 cp (vinyl group content: 2.0 mol%) and whose molecular chain terminals were blocked with dimethylvinylsilyl groups. 7 parts of methylhydrodiene polysiloxane capped with trimethylsilyl groups and having a viscosity of 40 cp are mixed with the formula After adding 1.0 part of an organosilicon compound with a boiling point of 195°C as a control agent and mixing uniformly, 1.0 parts of an organosilicon compound with a boiling point of 195°C was added to 100 parts of the above siloxane copolymer in terms of platinum.
A complex salt of platinum and vinyl siloxane in an amount of 120 ppm was added and mixed well to prepare composition G of the present invention. Then, for comparison, in place of the control agent in the above formula

1 part of 2-butyl-1,4-diol with the formula (boiling point 238°C), 1.0 part of 2,4-hexadiyne-1,6-diol with the formula HOCH ₂ C≡C-C≡CCH ₂ OH part, expression Composition H as Comparative Examples 6, 7, and 8 by adding 1.0 part of an organosilicon compound having a boiling point of 255 ° C.
I made I and J. Next, Example 1 regarding these compositions G to J
When the physical properties of these compositions were investigated using the same method as above, the results shown in Tables 4 and ⁵ were obtained. 80 after coating
℃, measured at 100℃, and peel resistance and residual adhesion rate of 1.0g/m ² were applied to polyethylene laminated kraft paper and heated at 100℃ for 30 seconds to form a film. The adhesive used to measure peel resistance was the above-mentioned olivine.
BPS-5127 and Olivine BPS-2411.

【table】

[Table] Example 3 Compositions G to J prepared in Example 2 were coated on polyethylene laminated kraft paper in the same manner as in Example 2, and the coating was coated with an 80 W/cm ultraviolet irradiation machine -HI.
-20N (trade name manufactured by Nippon Battery Co., Ltd.) Two lamps were irradiated with ultraviolet rays from a distance of 8cm from the lamps to cure them, and the curing properties at this time were examined, and the results were as shown in Table 6. Obtained.

【table】

Claims (1)

[Scope of Claims] 1 (1) An organopolysiloxane having a viscosity of 50 cS or more at 25°C and at least two vinyl group-silicon bonds in one molecule and having a substantially linear structure 100% by weight Part (2) Organopolysiloxane having at least two hydrogen-silicon bonds in one molecule 0.2-50
Parts by weight (3) General formula or (Here, R ¹ , R ² , R ³ , R ⁴ , and R ⁵ are hydrogen atoms or the same or different unsubstituted or substituted aliphatic monovalent hydrogen groups having 1 to 10 carbon atoms) whose boiling point is 250 An organosilicon compound having an acetylenically unsaturated group that is compatible with the organopolysiloxane as the first and second components described above at a temperature of ℃ or less
0.1 to 10 parts by weight (4) 2 to 10 parts by weight of platinum based on component (1) above
A silicone composition for release paper characterized by comprising 500 ppm of a platinum-based compound.