JP3130176B2 - Pressure sensitive adhesive 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 pressure-sensitive adhesive composition, and more particularly to a silicone pressure-sensitive adhesive composition which is cured by an addition reaction and exhibits excellent tackiness.

[0002]

2. Description of the Related Art Silicone pressure-sensitive adhesives have excellent adhesive strength, adhesive strength, tackiness and cohesive strength, and also have excellent heat resistance, cold resistance and weather resistance characteristic of silicone. It is widely used in tapes and other adhesive products that require heat resistance and cold resistance.

[0003] Conventionally, such a silicone pressure-sensitive adhesive composition comprises (CH ₃ ) ₃ SiO _1/2 units and SiO _2.
A composition is known in which a condensate of a copolymer composed of units and a polyorganosiloxane having a high degree of polymerization in which both molecular chain terminals are blocked with hydroxyl groups is crosslinked with an organic peroxide (for example, benzoyl peroxide). ing. However, pressure-sensitive adhesives that cure using organic peroxides generally need to be cross-linked by heating at a high temperature of 130 ° C or higher, making it difficult to apply to substrates that do not have heat resistance. There was a problem.

In order to solve these problems, a silicone composition obtained by an addition reaction is prepared by preparing (CH ₃ ) ₃ SiO _1/2 units and Si
A composition has been proposed in which a copolymer composed of O ₂ units and a polyorganosiloxane having an alkenyl group at a molecular chain terminal are crosslinked by an addition reaction in the presence of a polyorganohydrogensiloxane and a platinum catalyst (particularly). JP-A-51-127132 and JP-A-63-22886), however, the adhesive strength and the holding power were not sufficiently satisfactory.

Japanese Patent Application Laid-Open No. 64-45467 discloses a polydiorganosiloxane in which the terminal is blocked by a hydroxyl group and contains an aryl group and an alkenyl group, R ₃ SiO _1/2 unit and S
A composition has been proposed in which a condensate of a copolymer comprising iO ₂ units and a polyorganohydrogensiloxane are crosslinked by an addition reaction in the presence of a platinum catalyst. ,
Poor compatibility with the copolymer consisting of R ₃ SiO _1/2 units and SiO ₂ units weakens the cohesive strength of the resulting pressure-sensitive adhesive, and increases costs due to the inclusion of aryl groups It had disadvantages such as.

Further, a polyorganosiloxane and a copolymer comprising R ₃ SiO _1/2 units and SiO ₂ units, which can include those whose terminals are blocked by a hydroxyl group, described in JP-A-54-61242. A composition which crosslinks a polycondensate with a polyorganosiloxane by an addition reaction in the presence of a platinum catalyst does not itself exhibit the properties as a pressure-sensitive adhesive, and is a primer for a known silicone pressure-sensitive adhesive. Compositions, the compositions of which are shown in the examples,
The function as an adhesive could not be sufficiently exhibited.

Japanese Patent Application Laid-Open No. 4-335083 discloses a copolymer comprising an organopolysiloxane having a hydroxyl group at the terminal or an organopolysiloxane having a vinyl group, and R ₃ SiO _1/2 units and SiO ₂ units. And a polysiloxane of
Consisting of an organohydrogen polysiloxane, a platinum-based catalyst, and a polysiloxane containing a high vinyl group,
Although silicone pressure-sensitive adhesive compositions are shown, polysiloxanes containing both alkenyl groups and hydroxyl groups are not specifically exemplified. Therefore, the introduction of an alkenyl group by the condensation reaction between the copolymer and the hydroxyl group-containing polysiloxane was not shown, and such a pressure-sensitive adhesive composition was desired to further improve cohesive strength and holding power.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned conventional problems and to provide a silicone pressure-sensitive adhesive excellent in tack, tackiness and cohesion.

[0009]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to obtain the above-mentioned composition, and as a result, have found that polydiorganosiloxane and R ₃ SiO _1/2 units and SiO ₂ units are composed of the same. In a pressure-sensitive adhesive composition containing a condensate with a polymer and being crosslinked by an addition reaction, both ends are blocked with hydroxyl groups (hereinafter also referred to as hydroxyl groups) as polydiorganosiloxane, and the organo groups are alkenyl groups and alkyl groups. It has been found that an excellent pressure-sensitive adhesive composition which solves these problems can be obtained by using a group containing no aryl group, and the present invention has been accomplished.

Further, in a condensate of a polydiorganosiloxane and a copolymer, a polydiorganosiloxane having both ends blocked with a hydroxyl group and containing no alkenyl group is added as one of the components to be condensed.
The present inventors have found that a pressure-sensitive adhesive composition having better characteristics can be obtained, and have accomplished the present invention.

That is, the pressure-sensitive adhesive composition of the present invention comprises: (A) the following components (1), a polyorganosiloxane obtained by condensing components (2) and (3), (1) both ends Has an hydroxyl group, and 0.01 to 10 mol% of the organic group bonded to the silicon atom is an alkenyl group, the remainder is an alkyl group, and the average degree of polymerization is 50 to 10,000.
15 to 70 parts by weight of a polydiorganosiloxane of (2) having a hydroxyl group at both ends, an organic group bonded to a silicon atom is a monovalent alkyl group, and an average degree of polymerization of 50
0 to 55 parts by weight of polydiorganosiloxane of up to 10,000, (3) R ₃ SiO _1/2 unit (where R is a monovalent hydrocarbon group)
Or a hydroxyl group or an alkoxy group ) and SiO ₂ units, and the molar ratio of R ₃ SiO _1/2 units to SiO ₂ units is 0.5: 1.0 to 1.0: 1.0, and is bonded to silicon in one molecule. 70 to 30 parts by weight of a polyorganosiloxane copolymer having at least one hydroxyl or alkoxy group, and (B) an organohydrogensiloxane having an average of two or more hydrogen atoms bonded to silicon atoms in one molecule.
(A) an amount that gives 0.01 to 20 silicon-bonded hydrogen atoms per alkenyl group in component (A), and (C) a platinum-based catalyst, based on the total amount of components (A) and (B), consisting of 0.1~1,000ppm in terms of when the door
In addition, polysiloxane components other than the components (A) to (C)
It is characterized by not containing .

The polyorganosiloxane of the component (A) is
It is a base polymer that is a feature of the composition of the present invention, and is a condensate of the alkenyl group-containing polydiorganosiloxane of the component (1) and the copolymer of the component (3), or the component (1) and the component (2). It is a condensate of a polydialkylsiloxane and a copolymer of component (3). The polydiorganosiloxane of component (1) is essentially of the formula

[0013]

Embedded image Which has a hydroxyl group bonded to a silicon atom at both ends of the molecular chain. If at least one is not a hydroxyl group, the adhesive function of component (A), which is a condensate with components (2) and (3), is undesirably reduced. Wherein R ¹ is an alkyl group or an alkenyl group,
It does not include aryl groups such as phenyl groups. When R ¹ is such a substituent, the condensation reaction of the components (1), (2) and (3) is carried out favorably, and the cohesive force and the like of the obtained pressure-sensitive adhesive are improved. . Examples of the alkyl group include a methyl group, an ethyl group, and a propyl group, and examples of the alkenyl group include a vinyl group and an allyl group. When containing an aryl group such as a phenyl group, components (1) and (2)
The reaction of (3) is not performed well, and the properties of the obtained pressure-sensitive adhesive are insufficient. n is a number from 50 to 10,000, preferably from 500 to 6,000. If n is greater than 10,000, the final composition will have a very high viscosity silicone pressure sensitive adhesive and will be difficult to handle. On the other hand, when n is less than 50, the viscosity becomes extremely low, and it becomes difficult to apply uniformly to a coating film thickness required as a pressure-sensitive adhesive. The component (A) must be cured by an addition reaction with the polyorganohydrogensiloxane (B) in the presence of a platinum-based catalyst (C).
Of the organic groups represented by R ¹ in the polyorganosiloxane of
0.01 to 10 mol% must be alkenyl groups. The preferred alkenyl group content is 0.05 to 5 mol%.
It is. If it is less than 0.01 mol%, the crosslink density becomes small, and the cohesive force as a pressure-sensitive adhesive becomes insufficient, and it is impossible to obtain a material having excellent holding power and adhesive strength. And the adhesive layer becomes hard, resulting in poor tack and tack. Also ingredients
The structure of (1) is preferably linear, but may include some branched structures. The polydiorganosiloxane of component (2) has essentially the formula:

[0014]

Embedded image Which has a hydroxyl group bonded to a silicon atom at both ends of the molecular chain. When at least one of the two terminals is not a hydroxyl group, the adhesive function of the component (A) is undesirably reduced as described in the component (1).
In the formula, R ² represents a monovalent alkyl group, and examples thereof include an alkyl group such as a methyl group, an ethyl group, and a propyl group. n is 5
The number is from 0 to 10,000, preferably from 500 to 6,000. If n is greater than 10,000, the final composition of the silicone pressure-sensitive adhesive will have a very high viscosity and will be difficult to handle. On the other hand, when n is less than 50, the viscosity becomes extremely low, and it becomes difficult to apply uniformly to a coating film thickness required as a pressure-sensitive adhesive. The structure of the component (2) is preferably linear, but may include some branched structures.

The component (3) gives tackiness by a condensation reaction with the component (1) or the components (1) and (2), and comprises R ₃ SiO _1/2 units and SiO ₂ units. Which is a copolymer having at least one hydroxyl group bonded to a silicon atom in one molecule. Where R is a monovalent charcoal
Examples of the hydride group include an alkyl group such as a methyl group, an ethyl group, and a propyl group, and an alkenyl group such as a vinyl group and an allyl group. Also, R ₃ SiO _1/2 units and Si
The molar ratio of O ₂ units is 0.5: 1.0 to 1.0: 1.0. S
i O ₂ units often the adhesive strength, tackiness is lowered, Si O ₂
When the number of units is small, the cohesive strength is reduced. The method for synthesizing such a polyorganosiloxane is as follows: triorganochlorosilane or triorganoalkoxysilane and tetrachlorosilane or tetraalkoxysilane in a solvent:
A method of co-hydrolyzing / condensing at a molar ratio of 1.0 to 1.0: 1.0 is exemplified, and is generally obtained as a solution of an organic solvent such as toluene.

The component (A) can be obtained by heating and mixing the components (1) and (2) and the polyorganosiloxane copolymer of the component (3) for condensation. Components (1) and (2) that are polydiorganosiloxanes
If the amount is too small, the adhesive strength and tack will be poor,
If the amount is too large, the cohesive strength becomes poor. For this reason, it is preferable that the compounding amount is 70 to 30 parts by weight of the component (3) of the polyorganosiloxane copolymer based on 30 to 70 parts by weight of the total amount of the components (1) and (2). .

Here, the mixing ratio of the component (1) of the alkenyl group-containing polydiorganosiloxane and the component (2) of the polydiorganosiloxane is such that if the amount of the component (1) is too small, the cohesive strength becomes poor. It is preferred that component (2) be used in an amount of 0 to 55 parts by weight based on 15 to 70 parts by weight of component (1). In particular, since good adhesive strength and tack are obtained, and cohesive strength becomes preferable, the component (2) should be used in an amount of 10 to 30 parts by weight based on 60 to 30 parts by weight of the component (1). preferable.

The component (B) is a component that functions as a crosslinking agent.
A polyorganohydrogensiloxane having at least two hydrogen atoms bonded to silicon atoms in the molecule, wherein the alkenyl group in the component (A) and the component (B) in the presence of the platinum catalyst as the component (C) The hydrogen atoms bonded to the silicon atoms are crosslinked by an addition reaction. Examples of the organic group bonded to the silicon atom of the polyorganohydrogensiloxane (B) include an alkyl group such as a methyl group and an ethyl group, but a methyl group is generally preferred.

The component (B) is an alkenyl group in the component (A).
It suffices if there is an amount which gives 0.01 to 20 hydrogen atoms bonded to silicon atoms per one. The structure of the component (B) may be in any form such as a chain, a ring, and a net.

The component (C) is a catalyst for the addition reaction between the components (A) and (B). This may be a catalyst conventionally used as an addition reaction catalyst between a vinyl group-containing polyorganosiloxane and a polyorganohydrogensiloxane, such as chloroplatinic acid, a complex of chloroplatinic acid and an olefin, and chloroplatinic acid. Examples include a complex with vinyl siloxane, and solid platinum supported on a carrier such as alumina or silica.

The added amount of the component (C) is 0.1 to 1,000 p as a platinum element with respect to the total amount of the components (A) and (B).
pm, preferably 5 to 200 ppm. If the addition amount of the component (C) is too small, crosslinking becomes insufficient, and sufficient cohesive strength cannot be obtained. If the addition amount is too large, the pot life is shortened and there is a problem in cost.

The composition of the present invention basically comprises (A) to (C)
Although it is composed of components, additives that give sufficient pot life to the composition may be used. Examples of such additives include carboxylic acid diesters such as diallyl maleate, diallyl phthalate, and dimethyl maleate;
Acetylene compounds such as 2-methyl-3-butyn-2-ol;

In applying the composition composed of the components (A) to (C), the composition may be diluted with a solvent or mixed with a filler such as silica or calcium carbonate to facilitate application. It is.

[0024]

Next, the present invention will be described by way of examples. In the examples, “parts” indicates parts by weight, and the viscosity indicates a value at 25 ° C.

Example 1 0.8 mole of (CH ₃ ) ₃ SiO _1/2 units and ₂ SiO ₂ units 1
83.3 parts of a 60% xylene solution of a polymethylsiloxane copolymer consisting of moles and 0.2 mole% of all organic groups
Is a vinyl group and the remainder is a methyl group.25 parts of polydimethylsiloxane having both ends hydroxyl-blocked with a polymerization degree of 6,000, and 25 parts of a polydimethylsiloxane having both ends hydroxyl group with a polymerization degree of 6,000 where the organic group is a methyl group. After mixing in toluene and heating at reflux for 6 hours in the presence of an alkali catalyst,
The solution was neutralized with an acid to obtain a 40% solution of a polyorganosiloxane condensate having a vinyl group. To this 40% solution was added 0.4 part of polymethylhydrogensiloxane having trimethylsilyl groups at both ends and 2-methyl-3-butyne- as a reaction inhibitor.
0.3 part of 2-ol was added and dissolved. Next, a complex of chloroplatinic acid and vinyl siloxane was added to and mixed with platinum in an amount of 20 ppm as a platinum element with respect to the total amount of the polysiloxane to obtain a pressure-sensitive adhesive composition.

This composition was applied to a substrate such that the film thickness after heating became 40 μm, and was cured by heating for 2 minutes.
The heating was performed under two conditions of 80 ° C and 120 ° C. The adhesive strength, ball tack and holding power of the obtained adhesive tape were measured, and the results shown in Table 1 were obtained. The pressure-sensitive adhesive composition of the present invention had good adhesive strength, ball tack, and holding power, which are the properties required as an adhesive.

The above characteristic values were measured by the following test methods. (1) Adhesive strength measurement method Adhesive tape obtained by coating and heat-curing the silicone pressure-sensitive adhesive composition on a PET film with a thickness of 50 μm and a width of 25 mm so that the thickness after curing becomes 40 μm. 2k on stainless steel plate (SUS304) whose surface is polished with No. 280 waterproof abrasive paper
(g) using a rubber roller. After standing at room temperature for 3 hours, the adhesive strength when peeled off at a speed of 0.3 m / min using a tensile tester was measured and indicated in units of g / 2.5 cm. (2) Measuring method of holding force A pressure-sensitive adhesive tape obtained by coating and heat-curing a silicone pressure-sensitive adhesive composition on a PET film having a thickness of 50 μm and a width of 25 mm so that the cured thickness becomes 40 μm. Was adhered to a stainless steel plate (SUS304) whose surface was polished with No. 280 water-resistant abrasive paper with an area of 25 mm in length and 25 mm in width using a 2 kg rubber roller. A 1 kg load was applied to the lower end of the pressure-sensitive adhesive tape, suspended in an oven at 100 ° C., and the drop distance after 1 hour was measured. (3) Measurement method of ball tack
JIS Z 0237 with a 30 ° tilt angle with the adhesive side up
On the specified ball tack tester, give a 10 cm long runway, roll various steel balls, and measure the diameter of the largest steel ball stopped on a 10 cm long adhesive surface in 1/32 inch increments. Indicated.

COMPARATIVE EXAMPLE 1 The same procedure as in Example 1 was repeated, except that the polydimethylsiloxane containing a hydroxyl group at both ends and having a polymerization degree of 6,000 and the polydimethylsiloxane having both ends and a hydroxyl group having a polymerization degree of 6,000 were substituted with vinyl groups having both ends and a polymerization degree of 6,000. A pressure-sensitive adhesive composition was obtained in the same manner as in Example 1 except that the group-containing polydimethylsiloxane and the polydimethylsiloxane having a vinyl group blocked at both terminals were not heated and refluxed in the presence of an alkali catalyst.

This composition was evaluated in the same manner as in Example 1 and also shown in Table 1. However, heat curing was performed at 120 ° C. The pressure-sensitive adhesive composition using the polysiloxane blocked with a vinyl group at both ends of this example was inferior in tackiness and holding power.

[0030]

[Table 1] *: Shows mol% of vinyl group to all organic groups in polydiorganosiloxane. **: G1 indicates parts by weight of component (1), G2 indicates parts by weight of component (2), and R indicates parts by weight of component (3).

Example 2 0.8 mole of (CH ₃ ) ₃ SiO _1/2 units and ₂ SiO ₂ units 1
Moles of polymethylsiloxane resin
Example 1 except that 83.3 parts of a 50% xylene solution and 50 parts of a polydimethylsiloxane containing a hydroxyl group at both ends hydroxyl-blocked and having a polymerization degree of 6,000 in which 0.1 mol% of all the organic groups were vinyl groups and the remainder were methyl groups were used. In the same manner as in the above, a pressure-sensitive adhesive composition was obtained.

This composition was evaluated in the same manner as in Example 1 to obtain the results shown in Table 2. However, heat curing was performed at 120 ° C.

Comparative Example 2 In Example 2, the polymerization degree was changed to 6,0 instead of the polydimethylsiloxane having both ends hydroxyl-blocked vinyl group having a polymerization degree of 6,000.
A pressure-sensitive adhesive composition was obtained in the same manner as in Example 2, except that the polydimethylsiloxane having a vinyl group blocked at both ends was used and the reflux was not carried out in the presence of an alkali catalyst.

This composition was evaluated in the same manner as in Example 2, and the results are shown in Table 2. The pressure-sensitive adhesive composition using the polysiloxane blocked with a vinyl group at both ends of this example was inferior in tackiness and holding power.

[0035]

[Table 2] *: Shows mol% of vinyl group to all organic groups in polydiorganosiloxane. **: G1 indicates parts by weight of component (1), G2 indicates parts by weight of component (2), and R indicates parts by weight of component (3).

Example 3 A pressure-sensitive adhesive composition was obtained in the same manner as in Example 1, except that 0.08 part of polymethylhydrogensiloxane was used. This composition was evaluated in the same manner as in Example 2 to obtain the results shown in Table 3.

Comparative Example 3 Comparative Example 1 was carried out in the same manner as in Comparative Example 1, except that 0.08 part of polymethylhydrogensiloxane was used.
A pressure-sensitive adhesive composition was obtained.

This composition was evaluated in the same manner as in Example 2, and the results are shown in Table 3. As shown in the table, the pressure-sensitive adhesive composition of Example 3 has a bonding force, a ball tack and a holding force of Comparative Example 3 in which both ends vinyl-blocked polysiloxane is used.
It was found to be superior to the pressure-sensitive adhesive composition.

Comparative Example 4 A solution prepared by dissolving 2 parts of benzoyl peroxide in a small amount of toluene was added to the 40% vinyl group-containing polyorganosiloxane solution of Example 1 and mixed to obtain a pressure-sensitive adhesive composition. This composition was evaluated in the same manner as in Example 2 to obtain the results shown in Table 3.

At the curing temperature of 120 ° C., the holding power obtained by the pressure-sensitive adhesive composition of the present invention could not be obtained with the silicone pressure-sensitive adhesive cured with benzoyl peroxide.

Comparative Example 5 In Example 1, the polymerization degree was changed in place of the polydimethylsiloxane having both ends hydroxyl-blocked vinyl groups having a polymerization degree of 6,000.
A pressure-sensitive adhesive composition was obtained in the same manner as in Example 1 except that 6,000 polydimethylsiloxanes containing vinyl groups having both terminal vinyl groups blocked were used.

This composition was evaluated in the same manner as in Example 2 to obtain the results shown in Table 3.

As can be seen from Tables 1 and 3, the adhesive properties obtained by the pressure-sensitive adhesive composition of the present invention can also be obtained by refluxing under heating in the presence of an alkali catalyst using a polydimethylsiloxane having a vinyl group blocked at both ends with vinyl groups. It turned out that it could not be obtained.

[0044]

[Table 3] *: Shows mol% of vinyl group to all organic groups in polydiorganosiloxane. **: G1 indicates parts by weight of component (1), G2 indicates parts by weight of component (2), and R indicates parts by weight of component (3).

Example 4 A polydimethylsiloxane having a hydroxyl-terminated vinyl group at both ends having a vinyl group content of 4.2 mol% of all organic groups and a degree of polymerization of 5,000 was obtained by the same procedure as in Example 1. A pressure-sensitive adhesive composition was obtained in the same manner as in Example 1, except that the polydimethylsiloxane was used instead of the polydimethylsiloxane.

The composition was evaluated in the same manner as in Example 2 to obtain the results shown in Table 4.

Comparative Example 6 A pressure-sensitive adhesive composition was obtained in the same manner as in Example 4, except that a vinyl group-containing polydimethylsiloxane whose both terminals were blocked with a methyl group was used.

This composition was evaluated in the same manner as in Example 2 and is shown in Table 4.

As shown in Table 4, the pressure-sensitive adhesive composition of the present invention
It was found that the adhesive strength, ball tack and holding power were superior to the pressure-sensitive adhesive composition using the polydimethylsiloxane containing a vinyl group having a methyl group blocked at both ends.

[0050]

[Table 4] *: Shows mol% of vinyl group to all organic groups in polydiorganosiloxane. **: G1 indicates parts by weight of component (1), G2 indicates parts by weight of component (2), and R indicates parts by weight of component (3).

Example 5 In Example 1, the amount of each component was changed to 100 parts of a 60% xylene solution of a polysiloxane copolymer, 20 parts of a polydimethylsiloxane containing a hydroxyl-terminated vinyl group at both ends, and both ends hydroxyl-terminated polydimethylsiloxane. A pressure-sensitive adhesive composition was obtained in the same manner as in Example 1, except that 20 parts and 0.32 parts of polymethylhydrogensiloxane were used.

This composition was evaluated in the same manner as in Example 2 to obtain the results shown in Table 5.

Comparative Example 7 A pressure-sensitive adhesive composition was obtained in the same manner as in Example 5, except that polydimethylsiloxane having both ends blocked with vinyl groups and polydimethylsiloxane having both ends methyl groups were used. Was. This composition was evaluated in the same manner as in Example 2 and also shown in Table 5.

[0054]

[Table 5] *: Shows mol% of vinyl group to all organic groups in polydiorganosiloxane. **: G1 indicates parts by weight of component (1), G2 indicates parts by weight of component (2), and R indicates parts by weight of component (3).

Example 6 The same procedure as in Example 1 was carried out except that a polydimethylsiloxane having a polymerization degree of 1,000 and a hydroxyl group-capped double-terminal hydroxyl group containing a vinyl group and a polymerization degree of 1,000 was used. To obtain a pressure-sensitive adhesive composition.

This composition was evaluated in the same manner as in Example 2 to obtain the results shown in Table 6.

Comparative Example 8 A pressure-sensitive adhesive composition was obtained in the same manner as in Example 6, except that a polysiloxane having a degree of polymerization of 1,000 and both ends blocked with vinyl groups was used.

This composition was evaluated in the same manner as in Example 2 to obtain the results shown in Table 6.

As shown in the table, the pressure-sensitive adhesive composition of the present invention
Adhesive strength, ball tack and holding power were good, and it was found that a pressure-sensitive adhesive composition using a polysiloxane blocked at both ends with vinyl group could not obtain the same properties.

[0060]

[Table 6] *: Shows mol% of vinyl group to all organic groups in polydiorganosiloxane. **: G1 indicates parts by weight of component (1), G2 indicates parts by weight of component (2), and R indicates parts by weight of component (3). Comparative Example 9 The following was used for comparison with an adhesive using the silicone pressure-sensitive adhesive composition of Example 2 as a primer and a peroxide-curable silicone pressure-sensitive adhesive composition as an adhesive composition. An evaluation was performed. The silicone pressure-sensitive adhesive composition of Example 1 was applied to a substrate such that the film thickness after heating was 5 μm.
After heating and curing at 0 ° C. for 2 minutes, and then adding 1.2% of benzoyl peroxide to a silicone-based pressure-sensitive adhesive composition SH-4280 (trade name, manufactured by Dow Corning Incorporated) and mixing with toluene, the mixture was heated. Was coated so as to have a film thickness of 35 μm, cured by heating at 90 ° C. for 2 minutes and at 180 ° C. for 2 minutes, and evaluated in the same manner as in Example 1. The results shown in Table 7 were obtained. From Tables 1 and 7, the silicone pressure-sensitive adhesive composition of the present invention had an adhesive strength that could not be obtained with an adhesive using this as a primer.

Comparative Example 10 In Example 2, instead of polydimethylsiloxane having a polymerization degree of 6,000 and having both ends hydroxyl-blocked vinyl groups, 0.1 mol% of all organic groups were vinyl groups, 10 mol% were phenyl groups, and the balance was A pressure-sensitive adhesive composition was obtained in the same manner as described above, except that a polysiloxane having hydroxyl groups at both ends and having a polymerization degree of 6,000, which is a methyl group, was used.

This composition was evaluated in the same manner as in Example 2, and the results are shown in Table 7.

From Tables 2 and 7, it was found that when a polysiloxane having a hydroxyl group at both ends containing a phenyl group was used, the holding power was inferior.

[0064]

[Table 7] *: Shows mol% of vinyl group to all organic groups in polydiorganosiloxane. **: G1 indicates parts by weight of component (1), G2 indicates parts by weight of component (2), and R indicates parts by weight of component (3).

[0065]

As described above, the silicone pressure-sensitive adhesive composition of the present invention uses a specific polydiorganosiloxane containing hydroxyl groups at both ends of a molecular chain, and is characterized by using an addition type silicone pressure-sensitive adhesive composition. It is a pressure-sensitive adhesive composition, and has a characteristic that it can be cured at a relatively low temperature and has an excellent tack, adhesive strength, and an adhesive having cohesive strength, polyester,
Plastic films such as polyethylene and polyimide,
It is extremely useful as a material for adhesive products based on materials such as paper such as Japanese paper and synthetic paper, cloth, glass wool, and metal foil.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-56-155257 (JP, A) JP-A-63-22886 (JP, A) JP-A-47-32047 (JP, A) JP-A-66861 (JP, A) JP-A-6-322354 (JP, A) JP-A-5-214316 (JP, A) JP-A-3-17178 (JP, A) JP-A-52-154856 (JP, A) JP-A-2-189383 (JP, A) JP-A-62-218466 (JP, A) JP-A-53-81565 (JP, A) Patent 2734809 (JP, B2) (58) Fields investigated (Int. . ^7, DB name) C09J 1/00 - 201/10 C08L 1/00 - 101/16 C08G 77/00 - 7/62 CA (STN) REGISTRY (STN)

Claims (1)

(57) [Claims] [Claim 1] becomes from (A) ~ (C) components of the following preparative
In addition, polysiloxane components other than the components (A) to (C)
No pressure-sensitive adhesive composition (A) Polyorganosiloxane obtained by condensing the following components (1), (2) and (3), (1) having a hydroxyl group at both ends and silicon Of the organic groups bonded to the atoms, 0.01 to 10 mol% are alkenyl groups, the rest are alkyl groups, and the average degree of polymerization is 50 to 10,000.
15 to 70 parts by weight of a polydiorganosiloxane of (2) having a hydroxyl group at both ends, an organic group bonded to a silicon atom is a monovalent alkyl group, and an average degree of polymerization of 50
0 to 55 parts by weight of polydiorganosiloxane of up to 10,000, (3) R ₃ SiO _1/2 unit (where R is a monovalent hydrocarbon group)
Or a hydroxyl group or an alkoxy group ) and SiO ₂ units, and the molar ratio of R ₃ SiO _1/2 units to SiO ₂ units is 0.5: 1.0 to 1.0: 1.0, and is bonded to silicon in one molecule. 70 to 30 parts by weight of a polyorganosiloxane copolymer having at least one hydroxyl or alkoxy group, and (B) an organohydrogensiloxane having an average of two or more hydrogen atoms bonded to silicon atoms in one molecule.
(A) an amount that gives 0.01 to 20 silicon-bonded hydrogen atoms per alkenyl group in component (A), and (C) a platinum-based catalyst, based on the total amount of components (A) and (B), Converted to 0.1 to 1,000 ppm.