JP2632606B2 - Curable organopolysiloxane 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 curable organopolysiloxane composition having good tackiness, adhesion and fluidity, and a cured product obtained by curing the composition.

[0002]

2. Description of the Related Art A curing reaction by an addition reaction between an organopolysiloxane containing a vinyl group bonded to a silicon atom and an organohydrogenpolysiloxane containing a hydrogen atom bonded to a silicon atom in the presence of a platinum catalyst. Curable organopolysiloxanes utilizing are known in the art. However, the cured products of these curable organopolysiloxanes have a drawback that their adhesion to metals, glass, rubber, plastics, and the like is weak.
For this reason, there has been a problem that the formed cured product is easily peeled in coating, sealing, potting, and the like of the electric component. For the purpose of remedying the drawbacks, various adhesion aids have already been proposed (JP-B-53-13508).
No., JP-B-58-26376, JP-B-59-5219).

[0003]

However, the curable organopolysiloxane composition to which these adhesion aids are added needs to be cured and adhered in a short time under low temperature conditions and in a short time under high temperature conditions. In some cases, sufficient adhesion to the substrate cannot be obtained, and the above-mentioned disadvantages have not been solved. In addition, when the injection material, the injection material, and the coating material are used with high loading of alumina or silica for imparting thermal conductivity and / or carbon or the like for imparting conductivity, the fluidity of the composition is reduced. There is a drawback that the operation is difficult on the work surface. Therefore, an object of the present invention is to provide a curable organopolysiloxane composition having improved adhesion and fluidity, and a cured product obtained by curing the composition.

[0004]

The present invention provides: (a) an organopolysiloxane having two or more alkenyl groups in one molecule; (b) a general composition formula (1):

Embedded image (Wherein, R ¹ , R ² and R ³ represent a substituted or unsubstituted monovalent hydrocarbon group containing no aliphatic unsaturated bond;
c, e, f and g are each independently a positive number, d is 0 or a positive number, c + d + e + f + g is 1 and (c + d
+ E + f) / g is from 0.3 to 4. ), And contains not more than 30 SiO _4/2 units in one molecule, and 0.01 to 0.5 mol of SiOH groups per 100 g of component (b).
And (b) SiCH = CH ₂ groups per 100 g of component
Organopolysiloxane from 0.05 to 0.34 molar content, composition containing (c) organohydrogenpolysiloxane having at least two hydrogen atoms bonded to silicon atoms within each molecule, and (d) a platinum catalyst It provides things. Further, the present invention provides a cured product obtained by curing the composition.

The organopolysiloxane (a) has at least two alkenyl groups in one molecule, and preferably has a viscosity at 25 ° C. of 50 to 200,000 cSt, more preferably 100 to 200 cSt. 100,00
It is in the range of 0cSt. An alkenyl group is, for example, a alkenyl group having 2 to 8 carbon atoms such as a vinyl group, an allyl group, a 1-methyl-2-propenyl group, a hexenyl group, a γ- (meth) acryloxypropyl group, and preferably a vinyl group. Can be mentioned. Further, as an organic group other than an alkenyl group, an alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group, an aryl group such as a phenyl group and a tolyl group, an aralkyl group such as a benzyl group and a β-phenylethyl group, or an aralkyl group such as these. A substituted or unsubstituted chloromethyl group in which some or all of the hydrogen atoms of the group have been substituted with a halogen atom or the like, or a 3,3,3-trifluoropropyl group, having 1 to 1 carbon atoms
It may contain 0, preferably a monovalent hydrocarbon group having 1 to 8 carbon atoms.

As such an organopolysiloxane,
Specifically, the following chemical formula:

Embedded image (In the above formula, p represents 2 or 3, s, u and w represent positive integers, t, v and x represent 0 or positive integers, s
+ T, u + v, and w + x each represent a positive integer of 2000 or less. ) Can be exemplified.

The structure of the organopolysiloxane (a) is as follows:
It may have a linear or partially branched structure. The organopolysiloxane may be used alone or as a mixture of two or more.

[0008] The organopolysiloxane of (b) is a component that characterizes the present invention, and improves the adhesiveness and flowability of the composition. In particular, when a large amount of filler is blended in the composition, the fluidity is significantly improved.

The organopolysiloxane (b) is SiO
It is an organopolysiloxane having a three-dimensional structure having _4/2 units as a basic constituent unit. In the general composition formula (1) representing the organopolysiloxane of (b), g representing the blending ratio of SiO _4/2 units is a positive number, and SiO contained in one molecule is represented by g.
The number of _4/2 units is 30 or less, preferably 3-20. If it exceeds 30, the compatibility with the organopolysiloxane (a) decreases. Although less than 3 can be used, there is a disadvantage that the proportion of volatile components in the organopolysiloxane (b) increases.

The following chemical formula:

Embedded image C, which represents the compounding ratio of the unit represented by the formula, is such that the organopolysiloxane of (b) is crosslinked with the organopolysiloxane of (a) by an addition reaction so that bleeding from the cured product is reduced. Therefore, it must be a positive number, the number of SiCHＣＨCH ₂ groups contained in the molecule is
0.05 g in 100 g of the organopolysiloxane of (b)
~ 0. A range of 34 mol, especially 0.07 to 0.12 mol is preferable.

E must be a positive number in order to improve tackiness and adhesion, and must be a positive number, that is, a specific amount of hydroxyl groups (SiOH groups) bonded to silicon atoms in the molecule. By containing, the tackiness and adhesion to the adherend are greatly improved, and even in a cured product obtained by curing for a short time under the above-mentioned high temperature conditions, sufficient tackiness and adhesion to the adherend are achieved. Can be obtained. Moreover, even when a large amount of filler is blended, the fluidity of the resulting composition is remarkably improved. Particularly, when the organopolysiloxane composition obtained by the addition reaction is used as an injection material, an injection material, and a coating material, for example, alumina or silica for imparting thermal conductivity, and / or carbon or the like for imparting conductivity. When using a large amount of filler,
There is a problem that the fluidity of the composition is reduced and the operation becomes difficult on the working surface.However, in the composition of the present invention, the viscosity of the composition is significantly reduced due to the presence of the SiOH group of the component (b),
Fluidity is improved. These SiOH groups are present in an amount of 0.01 to 0.5 mol, preferably 0.1 mol, per 100 g of the organopolysiloxane (b).
01-0.2 mole. If the amount of the SiOH groups is less than 0.01 mol, sufficient adhesiveness and fluidity cannot be obtained.
If the content is more than mole, the curability is adversely affected and the cured product is inferior in heat resistance.

F is a positive number, d is 0 or a positive number,
The sum of c + d + e + f + g is one. Also, the ratio of (c + d + e + f) / g is
It is 0.3-4, preferably 0.5-2. (c + d + e +
If f) / g is less than 0.3, good adhesion cannot be obtained, and if f / g is more than 4, it becomes substantially difficult to produce.

R ¹ and R ² are each a substituted or unsubstituted monovalent saturated hydrocarbon group having 1 to 8 carbon atoms, preferably 1 to 6 carbon atoms, excluding an aliphatic unsaturated bond. Groups, ethyl groups, and alkyl groups such as propyl groups,
Examples include an aryl group such as a phenyl group. Among them, a methyl group is preferable from the viewpoint of production, economy, and the like.

R ³ is a group excluding an aliphatic unsaturated bond.
A substituted or unsubstituted monovalent saturated hydrocarbon group having 1 to 6, preferably 1 to 4 carbon atoms, such as a methyl group,
Examples include an ethyl group, a propyl group, a methoxyethyl group, an ethoxyethyl group and the like, and among them, a methyl group is preferable.

The amount of component (b) is 3 to 20 parts by weight, more preferably 5 to 15 parts by weight, per 100 parts by weight of component (a).

The organohydrogenpolysiloxy of (c)
The organohydrogenpolysiloxane of sun (c) is as described above.
Acts as a crosslinking agent for the organopolysiloxanes of (a) and (b). The structure of the organohydrogenpolysiloxane (c) may be linear, branched, or cyclic, or may be a mixture thereof. For example, the following general formula:

Embedded image (In the above formula, b, c, d, e, f, g, i represent 0 or a positive integer, h represents an integer of 2 or more, and the number of silicon atoms in the molecule is usually 400 or less. .)

Embedded image

Embedded image (In the above formula, R ⁴ is a hydrogen atom, a methyl group, a propyl group,
Or a trimethylsiloxy group. ) And the like.

The amount of the organohydrogenpolysiloxane (c) to be used is such that the hydrogen atom bonded to the silicon atom is 1.0 to 1.0 with respect to the total amount of the alkenyl groups contained in the organopolysiloxanes (a) and (b). The amount is preferably 20.0 mol times, more preferably 1.2 to 10.0 times.

The platinum-based catalyst (d) is added as a catalyst for addition reaction between the organopolysiloxanes (a) and (b) and the organohydrogenpolysiloxane (c). There is a need to.

Examples of the platinum-based catalyst include solid platinum supported on a carrier such as platinum black, alumina and silica; chloroplatinic acid; alcohol-modified chloroplatinic acid; complexes of chloroplatinic acid and olefin; Platinum or a platinum compound such as a complex with vinylsiloxane is exemplified.

In the use of a platinum catalyst, when a solid catalyst is used, it is preferable to use the catalyst in a state where the particle diameter is small and the specific surface area is large in order to improve dispersibility.
When chloroplatinic acid or a complex of chloroplatinic acid and an olefin is used as a catalyst, it is preferable to use these after dissolving them in an organic solvent such as alcohol, ketone or ether.

The amount of the catalyst used is usually 0.1 to 0.1% in terms of platinum.
500 ppm. Specifically, for example, those which are compatible with the siloxane component, such as a complex of chloroplatinic acid and an olefin, include the organopolysiloxanes (a) and (b) and the organohydrogenpolysiloxane (c). 0.1 to 100 ppm (in terms of platinum) based on the total amount, and 20 to 500 ppm (in terms of platinum) for solid catalysts such as platinum black
It is preferred to use an amount.

Other Compounding Agents In addition to the components (a) to (d), a filler may be added to the composition of the present invention, if necessary. As the filler, all of those generally used in addition-type silicone rubber compositions can be used, for example, fumed silica, precipitated silica, hydrophobized silica, carbon black,
Titanium dioxide, ferric oxide, alumina, zinc oxide, quartz powder, diatomaceous earth, calcium silicate, talc, bentonite, asbestos, glass fiber, organic fiber, and the like. One or more of these may be used. Is also good.

The amount of the filler used is appropriately selected depending on the kind of the filler, and usually, the organopolysiloxane (a) 1
It is preferably 600 parts by weight or less per 100 parts by weight. Specifically, for example, when fumed silica is used, the content is preferably 25 parts by weight or less, and in the case of alumina, it is 300 to 50 parts by weight.
A range of 0 parts by weight is preferred.

Furthermore, it is preferable to add an adhesion aid to the composition of the present invention, whereby the shear adhesive strength is further improved. As an adhesion aid, for example,
No. 53-21026 having an alkoxysiloxy group, Japanese Patent Publication No. 53-13508 having an epoxy-containing hydrocarbon group, and Japanese Patent Publication No. 59-5219-disclosed alkoxysiloxy group and epoxy-containing Those having a hydrocarbon group are preferably used. More specifically, but not exclusively, the following chemical formula:

Embedded image

Embedded image Can be exemplified. Further, these can be used by appropriately increasing the degree of polymerization according to the use.

The above-mentioned organopolysiloxane comprises (a)
It is preferred to use 0.5 to 20 parts by weight, particularly 1 to 10 parts by weight, per 100 parts by weight of the organopolysiloxane. Furthermore, in order to further improve the adhesiveness of the composition of the present invention, for example, trialkyl isocyanurate, triallyl trimellitate, or a compound obtained by modifying these with siloxane can be added. More specifically,
For example, the following chemical formula:

Embedded image

Embedded image

Embedded image

Embedded image Are represented.

The amount of the above compound is not particularly limited, but is usually about 0.5 to 3 parts by weight based on 100 parts by weight of the organopolysiloxane (a). The composition of the present invention may further contain a coloring agent, a heat-resistant agent, a flame-retardant-imparting agent, an addition-reaction controlling agent, a foaming agent, and the like, as appropriate, depending on the intended use.

[0027]

EXAMPLES Example 1 1,3-Divinyl-1,1,3,3-tetramethyldisiloxane 4
For a mixture of 6.6 g (0.25 mol) and 40.6 g (0.25 mol) of hexamethyldisiloxane, ethyl silicate 40 (SiO ₂ content 40%) (manufactured by Tama Chemical Industry Co., Ltd.) 150.0 g (as SiO ₂ unit) 1.0 mol) and 5.0 g of paratoluenesulfonic acid.

The mixture was cooled to 0 to 15 ° C., and 20 g of water was added dropwise with stirring for 1 hour.
g was added. Thereafter, the mixture was stirred under reflux at 80 ° C. for 5 hours, and then neutralized with Na ₂ CO ₃ to obtain an ethanol solution. This solution was replaced with toluene and separated, and a toluene solution of 50% by weight of an organosiloxane was prepared. As a result, 125 g of an organopolysiloxane was obtained (organopolysiloxane 1).

[(CH ₂ = C) of this organopolysiloxane 1
H) (CH ₃ ) ₂ SiO _1/2 ], [(CH ₃ ) ₃ SiO _1/2 ] and Si
The molar ratio of the O ₂ units is 0.5: 0.5: 1.0, and further, in 100 g of the resin component, 0.02 mol of SiOH groups and 0.15 mol of SiOC ₂ H ₅ groups are contained.
Molar content. In the general composition formula (1), c, d, e, f, and g representing the mixing ratio of each unit are (c + d + e + f) / g.
And the ratio of SiO _{4/2 in} one molecule is 25.
Was individual.

Next, 100 parts by weight of linear polydimethylsiloxane (both ends were blocked with a dimethylvinylsilyl group, viscosity 5,000 c
St (25 ° C.)) and at least 20 parts by weight of the above-mentioned organopolysiloxane were mixed, and toluene was removed under reduced pressure. Then, 350 parts by weight of fine alumina powder (AS-40, manufactured by Showa Denko KK) was added. Added and mixed.

Further, 0.02 parts by weight of an octanol solution of chloroplatinic acid (2% by weight as platinum amount) and 0.2 parts by weight of tetravinyltetramethyltetrasiloxane (control agent) are added and mixed.

Embedded image The composition 1 was prepared by adding 2.5 parts by weight of an organohydrogenpolysiloxane represented by the following formula.

Example 2 Composition 1 prepared in Example 1 has the following chemical formula:

Embedded image A composition 2 was prepared by adding 2.0 parts by weight of an adhesion aid represented by

Example 3 100 parts by weight of linear polydimethylsiloxane (both ends were blocked with dimethylvinylsilyl group, viscosity: 1,000 c
St (25 ° C.)) 12 parts by weight of the organopolysiloxane of Example 1 was mixed, and toluene was removed under reduced pressure. After that, 15 parts by weight of acetylene black (trade name: HS-100, manufactured by Denki Kagaku KK) was added. Added and mixed.

Further, 0.1 part by weight of an octanol solution of chloroplatinic acid (2% by weight in terms of platinum) and 0.1 part by weight of tetravinyltetramethyltetrasiloxane (control agent) were added and mixed.

Embedded image 2.5 parts by weight of an organohydrogenpolysiloxane represented by the following formula and the following chemical formula:

Embedded image 2.0 parts by weight of an adhesion aid represented by the formula:
Was prepared.

Example 4 The polysiloxane 1 used in Example 1 for preparing 1,3-
Divinyl-1,1,3,3-tetramethyldisiloxane 46.6g
Instead of 1,3-divinyl-1,1,3,3-tetramethyldisiloxane 18.7 g (0.10 mol) and 1,3-divinyl-1,1,
3,3-diphenyldimethyldisiloxane 10.9 g (0.025
Mol), a toluene solution of 50% by weight of an organopolysiloxane was prepared in the same manner as in Example 1 to obtain 110 g of an organopolysiloxane (organopolysiloxane 2).

This organopolysiloxane 2 has [(CH ₂ = C
_{H) (CH 3) 2 SiO} 1/2], [(CH 2 = CH) (C 6 H 5) (CH 3) S
The molar ratio of iO _1/2 ], [(CH ₃ ) ₃ SiO _1/2 ] and SiO ₂ units is 0.20: 0.05: 0.5: 1.0, and the resin content is 100
g contained 0.03 mol of SiOH groups and 0.12 mol of SiOC ₂ H ₅ groups. C, d, e, f, and g representing the mixing ratio of each unit in the general formula (1) are 0.9 in a ratio of (c + d + e + f) / g, and one molecule The number of SiO _4/2 units therein was 28.

Except that 12 parts by weight of this organopolysiloxane 2 was used instead of the organopolysiloxane 1,
Composition 4 was prepared in the same manner as in Example 3.

Comparative Example 1 During the synthesis of organopolysiloxane 1 of Example 1, the amount of water added dropwise for 1 hour was 9 g, and after the addition was completed, 35 g of water and 50 g of toluene were added, and then water and ethanol were gradually removed. A 50% by weight toluene solution of organopolysiloxane was prepared in the same manner as in Example 1, except that the mixture was stirred at a final temperature of 95 ° C. for 5 hours, neutralized, replaced with toluene, and filtered. However, 120 g of an organopolysiloxane was obtained (organopolysiloxane 3).

[(CH ₂ = C) of this organopolysiloxane 3
H) (CH ₃ ) ₂ SiO _1/2 ], [(CH ₃ ) ₂ SiO _1/2 ] and SiO ₂
The molar ratio of the units is 0.5: 0.5: 1.0, and the resin content is 100
g contained 0.004 mol of SiOH groups and 0.12 mol of SiOC ₂ H ₅ groups. C, d, e, f, and g representing the blending ratio of each unit in the general formula (1) are 1.1 in the ratio of (c + d + e + f) / g, and The number of SiO _4/2 units was 28.

Comparative composition 1 was prepared in the same manner as in Example 1 except that 20 parts by weight of organopolysiloxane was used instead of organopolysiloxane 1.

Comparative Example 2 Comparative composition 2 was prepared in the same manner as in Example 2 except that 20 parts by weight of organopolysiloxane 3 of Comparative Example 1 was used.

Comparative Example 3 A comparative composition 3 was prepared in the same manner as in Example 3 except that 12 parts by weight of the organopolysiloxane 3 of Comparative Example 1 was used.

With respect to the compositions 1 to 4 and the comparative compositions 1 to 3, the viscosity was determined as the physical property before curing, and a sheet having a thickness of 2 mm was prepared by curing at 120 ° C. for 60 minutes. The specific gravity and hardness, elongation, and tensile strength were measured according to JIS K6301.

The compositions 1 and 2 and the comparative compositions 1 and 2 were subjected to curing at 120 ° C. for 60 minutes to measure the shear adhesive strength of aluminum and glass by preparing test pieces as shown in FIG.

For composition 3 and comparative compositions 3-4,
By curing at 150 ° C./30 minutes and 150 ° C./5 minutes, the shear adhesion by aluminum was measured by preparing a test piece as shown in FIG. This test piece was prepared by laminating the ends of an aluminum plate or glass plate 1 or 2 having a width of 25 mm over a length of 10 mm via a composition 3 having a thickness of 2 mm and curing under the above conditions. Table 1 shows the measurement results.

[0046]

[Table 1]

As shown in Table 1, compositions 1 to 4 had good flowability and had self-leveling properties, whereas comparative compositions 1 to 3 had poor flowability and did not have self-leveling properties. Further, in terms of adhesiveness, compositions 1 to 4 showed a value showing sufficient adhesive strength in the measurement results of shear adhesive strength, whereas comparative compositions 1 and 3 exhibited (HO _1/2 ) units. Since the number was smaller than that of the compositions 1 to 4, the adhesive strength was insufficient. In addition, comparative composition 2
Although it has a sufficient adhesive strength, it is difficult to operate on a work surface due to the above-mentioned poor fluidity, which is industrially disadvantageous. In measuring the shear adhesion of Compositions 3 to 4 and Comparative Composition 3, the curing conditions were 150 ° C./30 minutes and 150 ° C.
The measurement was performed in two ways at 5 ° C./5 minutes, but the measured values were not so different.

[0048]

The curable organopolysiloxane composition and its cured product according to the present invention are a curable organopolysiloxane composition having good tackiness, adhesion and fluidity, and its cured product.

[Brief description of the drawings]

FIG. 1 shows a test piece used in a method for measuring a shear adhesive force.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Aluminum plate or glass plate 2 Aluminum plate or glass plate 3 Cured composition

Claims (2)

(57) [Claims] (A) an organopolysiloxane having at least two alkenyl groups in one molecule; (b) a general composition formula (1): (Wherein, R ¹ , R ² and R ³ represent a substituted or unsubstituted monovalent hydrocarbon group containing no aliphatic unsaturated bond;
c, e, f and g are each independently a positive number, d is 0 or a positive number, c + d + e + f + g is 1 and (c + d
+ E + f) / g is from 0.3 to 4. ), And contains not more than 30 SiO _4/2 units in one molecule, and 0.01 to 0.5 mol of SiOH groups per 100 g of component (b).
And (b) SiCH = CH ₂ groups per 100 g of component
Organopolysiloxane from 0.05 to 0.34 molar content, composition containing (c) organohydrogenpolysiloxane having at least two hydrogen atoms bonded to silicon atoms within each molecule, and (d) a platinum catalyst Stuff. 2. A cured product obtained by curing the curable organopolysiloxane composition of claim 1.