JPH0258587A - Production of silicone pressure-sensitive adhesive composition of one-pack type - Google Patents

Abstract

PURPOSE:To obtain the title composition showing high cohesive force by removal of solvent and high bond strength in a high-temperature atmosphere by heat- treating a solution of an organopolysiloxane composition and dissolving a specific amount of an organopolysiloxane resin. CONSTITUTION:An organopolysiloxane composition consisting of (A) 100 pts.wt. diorganopolysiloxane containing 1-3 alkenyl groups on the average, (B) an organohydrogen polysiloxane containing 2 or 3 Si bonded hydrogens on the average and (C) a catalyst for hydrosiylation reaction is dissolved in an organic solvent. Then the solution is reacted by heating and (D) 20-200 pst.wt. organopolysiloxane resin which consists of R1/3 SiO1/2 unit (R<1> is alkyl, alkenyl or OH and >=90mol.% R<1> is methyl) and SiO2 unit and has <=10% Si bonded OH content is dissolved in the reaction mixture to give the aimed composition.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a one-component silicone pressure-sensitive adhesive composition, and more particularly, the present invention relates to a one-component silicone pressure-sensitive adhesive composition, and more particularly, it has high cohesive strength and high adhesive strength in a high-temperature atmosphere due to the removal of an organic solvent. The present invention relates to a one-component silicone pressure-sensitive adhesive composition.

[Conventional technology]

Silicone pressure-sensitive adhesives have excellent properties such as tackiness, adhesive strength, and adhesion at room temperature, and in addition, they have properties unique to silicone such as heat resistance, cold resistance, and electrical properties, so they can be used for advanced It is widely used in electrical insulation tapes that require reliability, adhesives that require heat resistance and cold resistance, and various adhesives.

Such a silicone pressure-sensitive adhesive composition is generally a two-component type that is made of a mixture of dimethylpolysiloxane raw rubber and methylpolysiloxane resin, and is cured by adding an organic peroxide as a curing catalyst immediately before use. Silicone pressure sensitive adhesive compositions have been used. Separately from this, there is also a two-component type, which is made of a mixture of alkenyl group-containing diorganopolysiloxane, organohydrodiene polysiloxane, and organopolysiloxane resin, and is cured by adding and blending a platinum-based catalyst as a curing catalyst immediately before use. Silicone pressure sensitive adhesive compositions have been used.

However, in all of these pressure-sensitive adhesive compositions, a curing catalyst is added and blended immediately before use, but in order to uniformly disperse this curing catalyst into the pressure-sensitive adhesive composition, long stirring is required. In addition, the workability was poor, as it required defoaming of the air trapped during stirring.

In addition, all of the above pressure-sensitive adhesive compositions exhibit strong tackiness and high adhesion and adhesion at room temperature, so when they are applied to the surface of various base materials and processed into tape-like adhesives, had the disadvantage that the coated surface and the back surface of the tape-like base material adhered to each other and could not be peeled off. Therefore, in order to put this into practical use, it was necessary to perform a mold release treatment on the back surface of the tape-like base material. Furthermore, when processing sheet-like adhesives and storing them in a stacked manner, it is necessary to insert a release material between the adhesive-coated surface and the back surface of the sheet-like base material.

[Problem to be solved by the invention]

The present inventors have made extensive studies to solve the above problems, and as a result, have arrived at the present invention.6 An object of the present invention is to provide a one-component silicone pressure-sensitive adhesive composition with excellent storage stability, and The object of the present invention is to provide a method for producing a one-component silicone pressure-sensitive adhesive composition that exhibits high cohesive strength and high adhesive strength in a high-temperature atmosphere by removing an organic solvent.

[Means for solving problems and their effects]

The present invention consists of 1 (Δ) 100 parts by weight of a diorganopolysiloxane having an average of 1 to 3 alkenyl groups in one molecule; (B) an average of 2 to 3 silicon-bonded hydrogen atoms in one molecule; Organopolysiloxane containing atoms The molar ratio of silicon atom-bonded water in the main component to alkenyl groups in the diorganopolysiloxane in component (A) is (1:0.1) to (1:0.8). ) within the range.

(C) Dissolving an organopolysiloxane composition comprising a catalytic amount of a catalyst for a hydrosilylation reaction in an organic solvent, and then heating the organic solvent solution to react the diorganopolysiloxane and the organohydrodiene polysiloxane. A mixture is prepared, and then the reaction mixture is added with (D)R", 5iO07□ units, where R1 is selected from alkyl, alkenyl, and hydroxyl groups, and all R
At least 90 mole percent of one group is a methyl group. ) and S
It consists of iO□ units and the silicon atom-bonded hydroxyl group content is 1.
0% by weight or less of organopolysiloxane resin as described above (
The present invention relates to a one-component silicone pressure-sensitive adhesive composition characterized in that 20 to 200 parts by weight of component A) are dissolved in 100 parts by weight.

To explain this, the diorganopolysiloxane (A) component used in the present invention has an average of 1 to 3 parts per molecule.
alkenyl groups.

The molecular structure of this component may be linear, mono-branched, cyclic, bi-network, or three-dimensional.Although its molecular weight is not particularly limited, it may be difficult to mix with other components or exhibit adhesive properties. From the viewpoint of ease of handling, it is preferable that at least half of it is linear or branched, and that the viscosity at 25° C. is 1,000,000 centivoise or less.

Examples of the alkenyl group bonded to the silicon atom of this diorganopolysiloxane include a vinyl group, an allyl group, a propenyl group, a butenyl group, and a pentenyl group.

Examples include hexenyl group, heptenyl group, and octenyl group. The bonding position of the alkenyl group is preferably at the end opposite to the silicon atom because the reactivity of the curing reaction is better. In addition to alkenyl groups, organo groups bonded to silicon atoms include alkyl groups such as methyl, ethyl, and propyl M+butyl groups; aryl groups such as phenyl, tolyl, and xylyl; benzyl, and phenethyl groups; Examples include aralkyl groups such as; halogenated alkyl groups such as chloromethyl group. In addition, the groups bonded to silicon atoms may contain small amounts of hydrogen atoms, hydroxyl groups, and alkoxy groups. From the viewpoint of economy and good adhesion, more than half of the organo groups bonded to silicon atoms are A methyl group is preferred.

The organohydrodiene polysiloxane (B) used in the present invention is a component that reacts with the diorganopolysiloxane (A) in the presence of the hydrosilylation reaction catalyst (C). On average 2 in 1 molecule
It is an organopolysiloxane having ~3 hydrogen atoms bonded to silicon atoms, and there are no particular restrictions on its molecular structure or molecular weight.

Examples of the organo group bonded to the silicon atom include the same organo groups as mentioned in the explanation of component (A,), but it is preferable that most of them are methyl groups. Specific examples of this component include: 1) dimethylsiloxane-methylhydrodienesiloxane copolymer with trimethylsiloxy groups blocked at both ends; 1) dimethylpolysiloxane with dimethylhydrodiensiloxy groups blocked at both ends; Siloxane-methylhydrodienesiloxane copolymer, cyclic dimethylsiloxane-methylhydrodienesiloxane copolymer+
(CHl) x tlsiot tz unit + (CHi)
Examples include copolymers consisting of 3S101,2 units and Sin units.

The amount of this component added is such that the moles of silicon-bonded hydrogen atoms in one component and alkenyl groups in component (A) are (1:o, 1
) to (1:0.8).

Also, the number of silicon-bonded hydrogen atoms in one component and the above (
It is preferred that the total number of alkenyl groups in the diorganopolysiloxane of component A) is less than 6. This is because when the total amount is 6 or more, the pressure-sensitive adhesive composition obtained by the production method of the present invention tends to gel during storage, and its fluidity decreases, making it uniform on various substrates. This is because there is a tendency for coating to become impossible.

The organic solvent used in the present invention is for facilitating the reaction between component (A) and component (B), and is for the purpose of facilitating the reaction between component (A) and component (B). It is a diluent to make it easier to coat on various substrates, and it contains component (A) ~
Any substance that dissolves component (D) may be used; a specific example thereof is toluene.

Examples include xylene, benzene, mineral spirit, solvent naphtha, n-hexane, n-hebutane, isopropyl alcohol, perchloroethylene, trichloroethylene, and the like. Further, these organic solvents may be used alone or in combination.

The amount of such an organic solvent to be used is appropriately selected upon use, and is therefore not particularly limited and is an arbitrary amount.

The hydrosilylation reaction catalyst used in the present invention is (A
This is a catalyst for promoting the reaction between component ) and component (B), that is, the addition reaction between the alkenyl group in component (A) and the silicon-bonded hydrogen atom in component (B). Such a catalyst is platinum chloride NI.

Examples include complexes of chloroplatinic acid and olefins, complexes of chloroplatinic acid and vinyl siloxane, platinum supported on fine supports such as alumina, and complexes of rhodium and vinyl siloxane. In addition, the amount added is sufficient for component (A) and component (B) to react,
It is the amount of catalyst.

In the present invention, the above-mentioned components (A) to (C) are dissolved in an organic solvent to obtain an organic solvent solution of the organopolysiloxane composition, but the dissolution method is not particularly limited, but in general, the (A) component An advantageous method is to uniformly dissolve the component (B) and (C) in an organic solvent, and then add the component (B) and the component (C) to uniformly mix and dissolve.

In the production method of the present invention, by heating the organic solvent solution of the organobosiloxane composition (Δ
The reaction mixture of the organopolysiloxane composition is produced by reacting the components () and (B), and the heating temperature may be any temperature that allows the above reaction to proceed, and is usually 3.
It is carried out within the range of 0°C to 120°C.

In the production method of the present invention, R13SIO□12 is added as component (D) to the reaction mixture obtained as described above.
(wherein R1 is selected from alkyl groups, alkenyl groups and hydroxyl groups, and at least 90 mol% of all R'' groups are methyl groups) and 810. units.

An organopolysiloxane resin having a silicon atom-bonded hydroxyl group content of io% by weight or less is added and dissolved. 1 exemplified by alkyl groups such as, alkenyl groups such as allyl group
-R1ff510x is a valent hydrocarbon group or hydroxyl group
The molar ratio of /22 parts and SiO□ units is (0,6:1) ~
It is preferably within the range of (1,0: 1.0).

This is because when the R13SIOI 72 unit is less than 0.5 or exceeds 1.0, the adhesive strength and cohesive strength of the pressure sensitive adhesive composition obtained by the production method of the present invention tend to decrease. Further, the content of hydroxyl groups bonded to silicon atoms in component (D) is 10% by weight or less, preferably 6% by weight or less. In addition, the amount added is (A) component 1
The amount is 20 to 200 parts by weight per 00 parts by weight. There are many methods for dissolving such an organopolysiloxane resin in the above reaction mixture, but generally speaking, it is effective to add the organopolysiloxane resin to the reaction mixture and stir it at room temperature or under heating. .

〔Example〕

Next, the present invention will be explained using examples. In the examples, parts represent weight parts, 1% represents weight %, and C8 represents centistokes. Further, each characteristic shown in the examples was measured using the following method θ;

○ After applying a heat-adhesive silicone adhesive composition to the surface of the measurement substrate of the ball tank to a thickness of 5.0 cm solids, leave it in a dryer at 110°C for 5 minutes to remove the organic solvent and make it sticky. A sheet was prepared. This adhesive sheet was pasted on a ball tack tester (manufactured by Tester Sangyo Sou) with an inclined surface of 30°, with the adhesive side facing up. Next, steel balls of various sizes were rolled using a run-up path of 10 cm length, and the diameter of the largest steel ball that stopped on a sticky surface of 1.10 cm length was shown in 1/32 inches. For example, a designation of 10 indicates that a 10/32 inch diameter steel ball was the largest steel ball that could be stopped on this sticky surface.

O Measurement of adhesion force The adhesive sheet made by the pole tack measurement method was
Stainless steel plate polished with No. 0 waterproof abrasive paper (SUS3
04) Attach on top using a 2 kg rubber roller at 25°C (room temperature adhesion). Further, the adhesive surface of the adhesive sheet and the stainless steel plate were overlapped and bonded together using an iron heated to about 110° C. (thermal adhesion).
After leaving it at 25°C for 1 hour, it was tested using a tensile tester [Tensilon: Toyo Baldwin 11] at 0.3 m/+++.
The adhesive force when peeled off was measured at a tensile speed of g/2
．． Displayed in units of 5 cm.

○Measurement of cohesive force Adhesive tape made using the same method as above for measuring adhesive force was placed on a stainless steel plate whose surface had been polished with No. 280 water-resistant abrasive paper (
SIJS304), length 20++n+, width 10m
The area is heated and bonded using an iron at approximately 110°C. Apply a load of 500g to the bottom end of this adhesive tape,
The displacement distance after hanging in a dryer at 100℃ for 2 hours is
It was measured using a reading microscope and expressed in meters.

Example 1 100 parts of dimethylpolysiloxane crude rubber with dimethylvinylsiloxy groups blocked at both ends and 0.8 parts of dimethylpolysiloxane blocked with dimethylhydrodiene siloxy groups at both ends having a viscosity of 15CS were dissolved in 300 parts of toluene and mixed with 6th chloroplatinic acid. A complex with divinyltetramethylsiloxane of 15 (lpp+mjt) in terms of platinum was added and reacted by heating at 90°C for 30 minutes.Next, to this solution (CH3), Si
Consists of n, /□ unit and Sin, unit, the molar ratio of which is 0
．． 7: 1.0, hydroxyl group content is 1.0% by weight
A silicone pressure-sensitive adhesive was prepared by dissolving 70 parts of methylpolysiloxane resin.

This was applied to a polyester film having a thickness of 38μ to a thickness of 50μ in terms of solid content. Next, the solvent was removed at 10°C to prepare a pressure-sensitive adhesive sheet. Adhesive force, cohesive force, and pole tack were measured using this pressure-sensitive adhesive sheet.

The results are shown in Table 1. For comparison, in the above,
The properties of a silicone pressure-sensitive adhesive composition prepared in the same manner as above except that the complex of chloroplatinic acid and divinyltetramethyldisiloxane were not used were measured in the same manner as above. The results are also listed in Table 1.

(The following is a blank space) Table 1 The silicone pressure-sensitive adhesive composition obtained by the production method of the present invention has excellent cohesive force, but the cohesive force of the comparative example was so low that it could not be put to practical use.

Example 2 100 parts of dimethylpolysiloxane with a viscosity of 100,000 C8 and endblocked with dimethylvinylsiloxy groups at both ends and 1.2 parts of dimethylpolysiloxane endblocked with dimethylvinylsiloxy groups at both ends and a viscosity of 50C5 were dissolved in 250 parts of xylene. Next, chloroplatinic acid in an amount of 200 ppffl (calculated as platinum) was added and reacted at 90°C for 1 hour while stirring.Next, this solution was composed of (CHI)3S101/22 parts and SjQ units, and their molar ratio was 0. 871. , O, and 100 parts of a methylpolysiloxane resin having a content of 0.3'Rit% was dissolved in hydroxyl to obtain a silicone pressure-sensitive adhesive composition. This was coated onto a 15-thick aluminum foil to a thickness of 50 μm in terms of the solid content of the adhesive. Next, the solvent was removed in a dryer at 100°C to prepare a pressure-sensitive adhesive sheet. Adhesive force, cohesive force, and ball tack were measured using this pressure-sensitive adhesive sheet. The measured values were as shown in Table 2. For comparison, a sample was prepared in the same manner as above except that a dimethylsiloxane/methylhydrogensiloxane copolymer containing five silicon-bonded hydrogen atoms in one molecule was used instead of the dimethylpolysiloxane used above. A silicone pressure sensitive adhesive composition was prepared. Similarly, a silicone pressure-sensitive adhesive composition was prepared using a dimethylsiloxane/methylhydrogensiloxane copolymer containing 25 silicon-bonded hydrogen atoms in the molecule. All of these silicone pressure-sensitive adhesive compositions increased in viscosity and eventually became gel-like, and could not be used as silicone pressure-sensitive adhesives.

Table 2 Example 3 100 parts of methylphenylsiloxane/dimethylsiloxane copolymer raw rubber (phenyl group content: 3 mol %) with dimethylvinylsiloxy groups endblocked at both ends and dimethyl endblocked with dimethylhydrogensiloxy groups at both ends with a viscosity of 50 centistokes. 1.6 parts of polysiloxane was dissolved in 300 parts of xylene. Next, a complex of chloroplatinic acid and divinyltetramethylsiloxane was added in an amount of 120 ppm in terms of platinum, and the mixture was reacted at 90° C. for 1 hour with stirring. Next, to this solution was added (CH3)□Sin, consisting of /z units and 5L02 units, with a molar ratio of 0.7:1.
A silicone pressure-sensitive adhesive composition was prepared by dissolving 80 parts of methylpolysiloxane resin having a hydroxyl group content of 1.0% by weight. A pressure-sensitive adhesive sheet was prepared from this composition in the same manner as in Example 1, and its adhesive strength, cohesive force, and ball tack were measured, and the results shown in Table 3 were obtained. For comparison, the procedure was the same as above except that instead of the methylphenylsiloxane/dimethylsiloxane copolymer blocked at both ends with dimethylvinylsiloxy groups, methylphenylsiloxane/dimethylsiloxane copolymer raw rubber with one end blocked with trimethylsiloxy groups was used. A silicone pressure sensitive adhesive composition was prepared. The properties of this composition were measured in the same manner as in Example 1. The results are also listed in Table 3.

Table 3 Example 4 100 parts of dimethylpolysiloxane with a viscosity of 110,000 C8, which has both ends capped with dimethylvinylsiloxy groups and contains an average of one vinyl group in the side chain, and a dimethylpolysiloxane with a viscosity of 5 acs and with hydroxyl groups capped at both ends. 1.2 parts of siloxane to 2 parts of xylene
A complex of chloroplatinic acid and divinyltetramethylsiloxane dissolved in 50 parts was added in an amount to give 120 ppm in terms of platinum, and reacted with stirring at 90°C for 1 hour. ), SiO, consists of 2 units and 5in2 units, and their molar ratio is 0.7:
A silicone pressure-sensitive adhesive composition was prepared by dissolving 80 parts of a methylpolysiloxane resin with a hydroxyl content of 1.0% and a hydroxyl group content of 1.0% by weight. An adhesive tape was prepared from this composition in the same manner as in Example 1.

When its properties were measured, the results shown in Table 4 were obtained. For comparison, we measured the properties of a composition prepared in the same manner as above except that dimethylpolysiloxane with a viscosity of 110,000 C8 was not used, and the results were summarized in the fourth section.
Also listed in the table.

(Margin below) Table 4 It has the characteristic that it can be easily manufactured.

Claims (1)

[Scope of Claims] 1 (A) 100 parts by weight of a diorganopolysiloxane having an average of 1 to 3 alkenyl groups per molecule; (B) an average of 2 to 3 silicon groups per molecule; Organohydrodiene polysiloxane containing atomically bonded hydrogen atoms The molar ratio of the silicon-bonded hydrogen atoms in the main component to the alkenyl groups in the diorganopolysiloxane in component (A) is (
An organopolysiloxane composition consisting of an amount within the range of 1:0.1) to (1:0.8) and (C) a catalytic amount of a hydrosilylation reaction catalyst is dissolved in an organic solvent, and then the organic The diorganopolysiloxane and the organohydrodiene polysiloxane are reacted by heating a solvent solution to form a reaction mixture of the organopolysiloxane composition, and then the reaction mixture is treated with (D)R^. 1_3SiO_1_/_2 units (in the formula, R^
1 is selected from alkyl groups, alkenyl groups and hydroxyl groups, and at least 90 mol% of all R^1 groups are methyl groups. ) and SiO_2 units, and the content of silicon-bonded hydroxyl groups is 10% by weight or less.
1. A method for producing a one-component silicone pressure-sensitive adhesive composition, which comprises dissolving 0.00 parts by weight.