JPS6350374B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention provides a thermosetting organopolysiloxane composition that is stable for a long period of time at room temperature, and that is stable at 120°C.
The above description relates to a thermosetting organopolysiloxane composition that cures in a short time. (Prior art) Thermosetting organopolysiloxane compositions are one-component thermosetting liquid rubbers that can be stored stably for long periods of time at room temperature, but quickly harden when heated. Development has been underway. Regarding such a composition, for example, (1) a composition in which an inorganic filler and an organic peroxide are arranged in a polysiloxane containing an alkenyl group or a mercapto group has been proposed (see JP-A-57-96045); It is stable for more than 6 months at room temperature.
It cures in 10 minutes at 150℃, but has the disadvantage that the open surface does not cure in air. Regarding so-called addition reaction type compositions consisting of a diene polysiloxane and a platinum-based catalyst, in order to extend the pot life, a composition containing triorganophosphine or acetylene alcohol, which inactivates the platinum-based catalyst, is added. This product has a pot life of more than one month and can be cured within 30 minutes when heated above 120°C, but these additives volatilize from the open surface during curing, causing surface damage. It has the disadvantage that internal curing is significantly delayed compared to curing, and therefore wrinkles are likely to occur on the surface. Regarding this type of curing reaction control agent, (3) a method of adding a curing inhibitor containing a -COOH group in the molecule (see Japanese Patent Publication No. 57-20340) is also known; Although it is possible to increase the pot life of addition-reactive compositions, this has the disadvantage that it takes too much time from the onset of gelation to the end of curing. In addition, if this conventional composition is mixed with ppm of sulfur, sulfur compounds, amine compounds, phosphorus compounds, or heavy metal salts, curing will be significantly inhibited by the catalyst poison. Even if the compound is present in the object rather than mixed in, curing is inhibited on the contact surface, so there is also the problem that its range of use and applications are limited. (Structure of the Invention) The present invention provides a thermosetting organopolysiloxane composition that does not have such disadvantages, has a long pot life at room temperature, and hardens to the inside of a molded product in a short time when heated at 120°C or higher. This is (A) general formula

[Formula] (where R is a group selected from an alkyl group having 1 to 8 carbon atoms, a vinyl group, a phenyl group, a perfluoroalkyl group having 3 to 10 carbon atoms, and a is 1.98 to 3.0) base
100 parts by weight of a vinyl group-containing organopolysiloxane containing 0.005 mol% or more, (B) at least an organohydrodiene polysiloxane having at least two ≡SiH groups in one molecule which is compatible with component A;
0.01 part by weight, (C) a catalytic amount of platinum or a platinum compound;
(D) 0.001 to 10 parts by weight of a curing inhibitor compound containing at least one hydroperoxy group in the molecule; and (E) 0.01 to 10 parts by weight of an organic peroxide. . To explain this, the present inventors have investigated thermosetting organopolysiloxane compositions for the above-mentioned purpose, and as a result, they have found that a vinyl group-containing polysiloxane and a ≡SiH group-containing organohydrodiene polysiloxane composition have been developed. When an organic peroxide is added to a thermosetting organopolysiloxane composition in which a hydroperoxide is added to an addition reaction type siloxane composition consisting of ,
A one-component thermosetting organopolysiloxane that can be heated to 120°C or higher can cure the inside of the molded product extremely quickly at the same time as the surface, making it easier to process as it eliminates the need for mixing operations in a two-component type. After confirming that injection molding of liquid rubber can be easily performed by simplifying the machine used for the injection molding, the present invention was completed by conducting research on the types, amounts, and methods of mixing each component. The organopolysiloxane as component (A) constituting the composition of the present invention has the general formula

[Formula], and this R is an alkyl group having 1 to 8 carbon atoms such as a methyl group, an ethyl group, a propyl group, a butyl group, a vinyl group, a phenyl group, or a 3,3,3-
3 or more carbon atoms such as trifluoropropyl group
The same or different monovalent hydrocarbons selected from 10 perfluoroalkyl groups, preferably at least 50 mol% of which are methyl groups, and at least 0.005 mol% of which are vinyl groups, and a is 1.98 to
3.0, but if the viscosity is too low, the cured product obtained from it will have poor elasticity, and if the viscosity is too high, the fluidity will be poor and mixing and molding will be difficult, so it should be 300 to 500,000 cS. ,
Preferably it is 1000 to 100000 cS. In addition, the structure of this material may be either linear or branched, but in order to obtain a cured product with excellent elasticity, it is preferably linear, and preferably at both ends of the molecular chain. is preferably capped with a vinyl group. In addition, the organohydrodiene polysiloxane as the component (B) constituting this composition serves as a crosslinking agent for the component (A), and this contains ≡ as a hydrogen atom bonded to a silicon atom in its molecule. Although it is required to have at least two SiH groups, there is no particular restriction on its molecular structure as long as it is compatible with component (A). Preferably, this organohydrodiene polysiloxane has an average molecular weight of 134 to 30,000, but if the amount added is too small relative to 100 parts by weight of component (A), the composition will not cure, and if it is too large, the composition will not be cured. Since foaming occurs during or during curing, and the cured product deteriorates significantly over time, the amount is desirably 0.01 to 10 parts by weight. Note that various known siloxanes can be used, but the following are typical examples: Examples include (CH ₃ )HSiO units, copolymers consisting of _1.5 units of (CH ₃ )SiO and (CH ₃ ) ₂ SiO units, and copolymers consisting of _0.5 units of (CH ₃ ) ₂ HSiO and SiO ₂ units. Ru. Next, the platinum-based catalyst as component (C) in this composition may be a known catalyst added to ordinary addition reaction compositions, such as chloroplatinic acid, alcohol-modified chloroplatinic acid (U.S. Pat. 3220972), complexes of chloroplatinic acid and olefins (US Pat. Nos. 3159601 and 3159662)
(see specification), solid platinum supported on a carrier such as platinum black, alumina, or silica. This chloroplatinic acid or its complex with olefin is preferably used after being dissolved in an alcohol, ketone, ether, or hydrocarbon solvent. The amount of platinum-based catalyst to be used may be adjusted as appropriate depending on the desired curing speed, but based on pharmaceutical knowledge and in order to obtain a good cured product, it is recommended to For soluble catalysts, the amount may be 1 to 30 ppm relative to component (A), and for solid catalysts such as platinum black, the amount may be 20 to 500 ppm. The curing inhibitor compound used here as component (D) is a known one, and any compound containing at least one hydroperoxy group in the molecule may be used. These include methyl ethyl ketone hydroperoxide, tertiary butyl hydroperoxide, cumene hydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide, 2,5-dimethyl-2,5-dimethyl Hydroperoxide, 1-hydroxycyclohexyl hydroperoxide, decalin hydroperoxide, 1,1,2,2-tetramethylpropyl hydroperoxide, p-
Examples include methane hydroperoxide and pinane hydroperoxide, with methyl ethyl ketone hydroperoxide being particularly preferred. The blending amount of this curing inhibitor is 100% vinyl group-containing organopolysiloxane as component (A).
It is necessary to add at least 0.001 part to part by weight; if it is too small, the inhibitory effect will be insufficient, and if it is too large, it will not be necessary to cure, but for many applications, vinyl group-containing organopolysiloxane The amount may be in the range of 0.001 to 10 parts by weight, and this amount may be determined depending on the intended pot life of the organopolysiloxane composition. The composition of the present invention is a composition consisting of the above-mentioned components (A) to (D) and further contains an organic peroxide as the component (E). This is a curing catalyst that is commonly used for curing various rubbers, synthetic pure resins, etc., but the decomposition temperature must be low due to handling, storage stability after addition, and danger. It is recommended that the temperature be 50℃ or higher. Examples of the organic peroxide include benzoyl peroxide, 2,4-dichlorobenzoyl peroxide, dicumyl peroxide, t-butyl peroxybenzoate, di-t-
-Butyl peroxide, 2,5-dimethyl-
2,5-di(t-butylperoxy)hexane,
Examples include 3-hexylene glycol benzoate, t-alkyl peroxyalkyl carbonate, hydroxymethyl-t-butyl peroxide, t-bityl-2-hydroxyethyl peroxide, and the amount used is 100% of component (A). Range of 0.01 to 10 parts by weight, preferably 0.5 to 10 parts by weight
It may be in the range of 3 parts by weight. The composition of the present invention can be obtained by mixing predetermined amounts of the above-mentioned components (A) to (E) and kneading them uniformly. Since the added composition may foam during heat curing in an open system, a predetermined amount of this hydroperoxide compound is mixed in advance with the vinyl group-containing organopolysiloxane as the main component (A). It is best to heat treat the
For example, if the mixture of component (A) and component (D) is 40 to 120
By heating and mixing at ℃ for 1 to 72 hours, foaming can be completely prevented by adding component (D), but if this heat treatment is performed under reduced pressure, the treatment time can be greatly shortened. . It should be noted that the above-mentioned foaming problem does not occur during pre-squeezing, which is usually used in many cases. In addition, the composition of the present invention consisting of the above-mentioned components (A) to (E) can reduce heat shrinkage during curing, improve weather resistance, chemical resistance, flame retardance, or mechanical strength, and improve gas permeability. A filler may be added for the purpose of lowering the content, such as fumed silica, quartz powder, glass fiber, carbon black, metal oxides such as iron oxide and titanium oxide, and metal carbonates such as calcium carbonate and magnesium carbonate. However, various additives may be added to this, specifically SiO ₂ units to reinforce the strength of the elastic body obtained as a cured product,
Organopolysiloxane with a resin structure consisting of _0.5 units of CH ₂ = CH (R' ₂ ) SiO and _0.5 units of R' ₃ SiO (R' is a monovalent hydrocarbon group that does not contain unsaturated groups), thermal shock resistance, and flexibility. In order to improve the properties, a non-tubular organopolysiloxane may be appropriately added, and if necessary, a suitable pigment, dye, or antioxidant may be added. In addition, when putting this composition into practical use, it may be used at a desired concentration by dissolving it in an appropriate organic solvent such as toluene or xylene depending on its purpose and use. Next, examples of the present invention will be given, in which parts are parts by weight, and viscosity is a value measured at 25°C. Examples 1 to 4, Comparative Examples 1 to 3 100 parts of a linear dimethylpolysiloxane with a viscosity of 40000 cS containing 3 x 10 ^-5 mol/g of vinyl groups whose molecular chain ends are capped with vinyldimethylsilyl groups (component To 1), 120 parts of quartz powder (component 2) with an average particle size of 5 μm and 12 parts of fumed silica (component 3) with a specific surface area of 200 m ² /g that was surface-treated with hexamethyldisilazane were added, and three rolls were added. After uniformly mixing with the
Add 2 parts and mix uniformly, then put this mixture into a 300 x 200 x 50 mm aluminum container,
Treatment mixture A was prepared by heat treatment in a ventilated oven at 60° C. for 48 hours. Then, ≡SiH groups were added to this treatment mixture A by 1.56×
0.8 part of methylhydrodiene polysiloxane (component 5) containing 10 ^-2 mol/g and 2-chloroplatinic acid.
Ethylhexanol solution (platinum concentration 2%, component 6) 0.12 parts, (CH ₂ = CH) (CH ₃ ) ₂ SiO _0.5 units 8 mol %, (CH ₃ ) ₃ SiO _0.5 units, 46 mol %, SiO ₂ units
3 parts of organopolysiloxane (component 7) consisting of 46 mol % and 2.4 parts of 2,5-dimethyl-2,5-di(t-butylperoxy)hexane (component 8)
A thermosetting liquid silicone rubber composition was obtained. Next, this composition was pre-cured at 170°C for 10 minutes and post-cured at 200°C for 4 hours, and the physical properties of the sheet obtained were determined according to JIS-K-6301.
In addition, the curability of this composition was measured using a disk rheometer ASTM 100 type (trade name manufactured by Toyo Seiki Co., Ltd.) at a temperature of 170°C, a swing angle of ±3°, a sweep time of 3 minutes, Sample temperature 25℃,
Measured with a sample amount of 20g, and this is 90% of the maximum torque after 3 minutes of sweet time.
Find it as the time required for torque, and then calculate this viscosity.
Measurements were made using a BS type viscometer according to the method specified in JIS-K-6833 under the conditions of rotor No. 7, rotation speed 10 rpm, and measurement temperature 25°C ± 0.1°C, and the results were as shown in Table 1. The results were obtained. In addition, the viscosity of this composition when left in an atmosphere of 25°C and 60% RH for 30 days, 90 days, and 180 days,
When the curability and hardness of the cured product were measured according to the above method, the results shown in Table 1 were obtained. For this composition, we observed the hardening state of the burr part (open part) and the pressed part during pre-curing, and in order to confirm the curing property against catalyst poison, we used a silicone rubber sheet containing 0.5% dibutyltin dilaurate [Shin-Etsu Chemical Co., Ltd.] KE manufactured by Kogyo Co., Ltd.
-17] was inserted and the hardening state of the contact surface was observed after precuring, and the results shown in Table 1 were obtained. Next, the treatment mixture A in the above composition is
A composition was prepared by treating in the same manner as the composition, except that Mixture B was not heat-treated at 60°C for 48 hours, and Component 4 was replaced with t-butyl hydroperoxide perbutyl H [NOF
Co., Ltd. product name] (composition as component 10), component 4
cumene hydroperoxide, percmil H
[Product name (component 11) made by the company] and these were heated at 60℃.
The composition was prepared by heat treatment for 48 hours. On the other hand, for comparison, component 4,
The composition was prepared without adding Components 5 and 6 and therefore without heat treatment at 60°C for 48 hours, and in the composition, component 4 was not added and instead of the commonly used inhibitor Tetra. Addition of 0.4 parts of methyltetravinylcyclotetrasiloxane (component 9) to the composition without heat treatment at 60°C for 48 hours; A composition was prepared by carrying out a heat treatment. In addition, when the various physical properties of this composition were examined in the same manner as for the above-mentioned composition, the results as listed in Table 1 were obtained, and from this result,
All of the compositions of the present invention had a long pot life and good heat curability, but it was confirmed that the compositions of the comparative examples had problems in curability.

【table】

[Table] Examples 5 to 7, Comparative Examples 4 to 6 Viscosity containing 5 x 10 ^-5 mol/g of vinyl groups whose molecular chain ends are blocked with vinyldimethylsilyl groups
10000cS dimethylpolysiloxane (component 12)
To 100 parts, 30 parts of component 3 of Example 1 was added and mixed uniformly with three rolls, then 1 part of component 4 of Example 1 was added thereto, mixed uniformly, and heated under reduced pressure of 30 mmHg. A stirring and mixing treatment was carried out at 60° C. for 12 hours to prepare a treated mixture C, and then 0.8 parts of component 5, 0.05 parts of component 6, 5 parts of component 7, and 1.6 parts of component 8 in Example 1 were added thereto. A thermosetting organopolysiloxane composition was prepared by uniformly mixing the compositions, and the physical properties of this composition were measured in the same manner as in Example 1. The results shown in Table 2 were obtained. In addition, treatment mixture C in the above composition was added to 60
A composition was prepared by processing in the same manner as the composition except that Mixture D was not heat-treated at ℃ for 12 hours.
3,3-tetramethylbutyl hydroperoxide peroctaH [manufactured by NOF Corporation, product name (components)
13)] and mixed under a reduced pressure of 30 mmHg at 60°C for 12 hours to prepare a composition. On the other hand, for comparison, component 4,
Composition XI was prepared without adding Components 5 and 6 and therefore without heat treatment at 60° C. for 12 hours, and also without adding component 4 in this composition, which was instead used in Comparative Example 2 above. Add 0.2 part of ingredient 9,
Composition XII was prepared by stirring and mixing at 60°C for 12 hours under reduced pressure of 30mmHg, and then stirring and mixing at 30mmHg, 60°C for 12 hours without adding component 8 of the composition to prepare a composition. Ivy. The various properties of this composition are shown in Example 1.
When examined using the same method as above, these results were shown in Table 2.

【table】

【table】

Claims (1)

[Claims] 1 (A) General formula [Formula] (wherein R is selected from an alkyl group having 1 to 8 carbon atoms, a vinyl group, a phenyl group, and a perfluoroalkyl group having 3 to 10 carbon atoms) 100 parts by weight of a vinyl group-containing organopolysiloxane containing 0.005 mol% or more of vinyl groups represented by the following formula (a is 1.98 to 3.0) (B) At least two ≡SiH groups in one molecule that are compatible with component A. an organohydrodiene polysiloxane having at least 0.01 part by weight (C) a catalytic amount of platinum or a platinum compound (D) a curing inhibitor compound containing at least one hydroperoxy group in the molecule;
A thermosetting organopolysiloxane composition comprising: 0.001 to 10 parts by weight (E) and 0.01 to 10 parts by weight of an organic peroxide.