JPS604555A - Room temperature curable silicone rubber composition - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a room-temperature-curable silicone rubber composition, particularly a room-temperature-curable silicone IJ cone rubber composition having low compression set.

Various types of room temperature curable silicone rubber compositions are known; The main component is the condensation type σ] which is formed by adding an organosilane or organosiloxane having 23 or more alkoxy groups and a catalyst. Shisuzu dioctoate is used.

However, this kind of room-temperature-curable silicone rubber composition has a property that if the cured product is kept under pressure for a long time, it will not return to its previous state even after the pressure is released.
The drawback is that it has poor compression set and is significantly thicker than heat-vulcanized silicone rubber.

That is, if this room temperature curing silicone rubber is used, for example, in a gas get, the gasket will loosen after a long period of time and will no longer be able to perform its function satisfactorily. If a roll of type 3 is rotated after being in pressure contact with another roll for a long period of time, there are disadvantages such as the distortion causing abnormal noise and the inability to obtain the desired design pressure in that part. In order to overcome this disadvantage, a mechanical device is required to apply pressure to the rubber portion g2 only when in use.

Therefore, this room-temperature-curable silicone rubber composition has better workability, adhesion, and mold releasability than heat-vulcanized silicone rubber, and has the advantage of having a short half-life of static electricity. It has the disadvantage that it cannot be applied to industrial applications where distortion occurs, and this improvement has been the subject of automotive equipment. Therefore, a method has been proposed for this purpose, for example, to reduce the use of the organotin compound catalyst mentioned above, but although this W1 case can extend the pot life, it significantly lengthens the curing time, so it is not suitable for industrial use. There is a disadvantage that it will no longer be possible.

The method of using this organic tin compound as tin ogtylate (...) is said to be effective in improving compression set, but since the amount used is very small, measurement errors are likely to occur, and the pot life is In addition to becoming noticeably rectangular.

This tin compound itself lacks moisture resistance and is therefore unsuitable for industrial use.

The present invention relates to a room-temperature curable silicone rubber composition which solves these disadvantages, and which A) has silicon-bonded hydroxyl groups at both ends of the molecular chain.

Viscosity at 25°C is 500 to 1,000,000aS
a, fljl-like organopolyi/Cl xane 10
B) Organosilane and/or organosiloxane 1 to 30i [LO] Inorganic filler O to 30i as a crosslinking agent having three or more alkoxy groups in one molecule
300 parts by weight and R1-R2, R5-R in formula D)
6 is a monovalent hydrocarbon group, R3-R4-R7, and R8 are a hydrocarbon wing ester group of a dicarboxylic acid.
It is characterized in that it consists of 0.03 to 0.4 parts by weight - per 100 parts by weight of B)+O).

To explain this, the present inventors have conducted extensive studies on measures to improve the compression set properties of room-temperature curable silicone rubbers with condensed rings. When a compound containing a hydrocarbon ester group is used, this compression set can be reduced to 20 to 30
Based on this fact, we conducted research on the release of organic tin compounds, the amount of addition, etc., and completed the present invention.

The organopolysilochitin used as component A), which is the base material constituting the composition of the present invention, may be one conventionally known for use in room temperature curable silicone rubber compositions. Bonded hydroxyl hydrocarbon group - m is a positive number)
A linear diorganopolysiloxane represented by R-R is an alkyl group such as a methyl group, an ethyl group, or a globyl group, a cycloalkyl group such as a cyclohexyl group or a cyclohegtyl group, a vinyl group, or an allyl group. Alkani such as groups/1
It consists of an aryl group such as a 4-phenyl group, a phenylmethyl group, an aralkyl group such as a phenylglopyl group, and the like.

It is preferred that at least 50% of the groups are methyl groups.

In addition, the self-organosilane and organosiloxane as the crosslinking agent as component B, which is blended into the organopolysilochitin as the base material, are also known for use in condensation type room temperature curable silicone rubber compositions. For example, the formula (R
110) In SIR12, R is a monovalent hydrocarbon group, and R is a group selected from an alkyl group, an aryl group, an alkenyl group, and an alkoxy group). It is necessary to use an organosilane having the following or an organosilochitin obtained by hydrolyzing this. Examples of this alkoxysilane include methyltrimethoxysilane-methyltriethoxysilane and phenyltrimethoxysilane.

Examples include phenyltriethoxysilane, vinyltrimethoxysilane-vinyltriethoxysilane, tetraethoxysilane, and 7-)lagropoxysilane. Examples of the silochitin include ethyl polysilicate, but these silanes have a boiling point When this composition is used in the form of a thin film, the surface may not be sufficiently cured, so the silane must be mixed with the organosiloxane mentioned above, or the silane must be used in a conventional manner. Therefore, it is preferable to partially hydrolyze the siloxane to form a liquid low molecular weight siloxane before use.

The inorganic filler as component C) constituting the composition of the present invention may be selected from quartz powder-diatomaceous earth, titanium dioxide-pengara, calcium carbonate, fumed silica, wet silica, etc., or any conventionally known room temperature curing silicone rubber. It is commonly used as a silicone rubber composition, but its pH should be within a suitable range - outside this range, the silicone rubber composition will not cure well or compress. Since the permanent deformation may become significantly large, it is preferable to set it in the range of 3 to 1O.

The organotin compound catalyst as component D) constituting the composition of the present invention is of this kind for use in curable silicone rubber compositions, and is represented by the following general formula: - This R-Ft -R-R is an alkyl group such as a methyl group, an ethyl group, a globyl group, a butyl group, an ogtyl group, an alkenyl group such as a vinyl group or an allyl group,
Aryl groups such as phenyl groups, phenylethyl groups, aralkyl groups such as phenylethyl groups, etc.'/:c
A monovalent hydrocarbon, R3, R4-R7, R8 are aromatic dicarboxylic acids such as phthalic acid and isophthalic acid, aliphatic unsaturated dicarboxylic acids such as maleic acid and fumaric acid, i
/ R' + R2 as described above of dicarboxylic acids such as aliphatic saturated dicarboxylic acids such as uric acid, malonic acid, and succinic acid.
, R5+R6, which is considered to be a monoester group of a hydrocarbon wing as shown in Oil dibutyltin) oxide Dibutyltin dihexyl maleate 0 111 00 Dibutyltin dibenzyl maleate 0 0 0 0 Dibutyltin diogtylphthalate 1 etc.

The room temperature softening silicone rubber composition of the present invention has the above-mentioned A
It can be obtained by mixing the components ) to D), but generally it can be used as a two-part type of A) + O) and B) + D) after mixing and defoaming. In these formulations, if the crosslinking agent as component B) is less than 1 part by weight with respect to x0ONM parts of organosiloxane as component A), the composition will have poor curing or the curing time will be too long. If this is 30 parts or more, the pot life will be short.

Also, since the elastomer obtained by this curing becomes brittle, the amount is preferably in the range of -1 to 30 parts by weight.C)
Regarding the inorganic filler as a component, A) If the amount is 300 parts by weight or more based on the weight of the organo1/'a Since it becomes brittle, it is necessary to keep the filler below 300M, but depending on the purpose and use of this FX, it may be additive-free, so the amount of this filler added is 10% organopolysiloxane.
It is sufficient to set θ to 300 vehicle volume parts for the 0-layer assembly part. Also,
If the amount of the organic tin compound as component D) is too small, the curing time of this composition will be long, making it unsuitable for industrial use; if it is too large, the curing time will be too fast, making it unsuitable for industrial use. The pot life of the elastomer will be shortened, and in both cases, the shrinkage set of the obtained elastomer will become significantly large. Range of 0.03 to 0.4 parts by weight, preferably 0.05 to 0.4 parts by weight
The range is preferably 0.2 parts by weight.

Furthermore, in order to extend the pot life of the composition of the present invention, a low molecular weight linear diorganoborilyloquitin having silicon-bonded hydroxyl groups at both ends of the molecule β is added. In addition, the addition of i/'I core Jyl whose molecular end is blocked with a triorganosilyl group as a mold release agent, and the addition of water to impart deep curing properties to this composition, You can do whatever you want depending on the situation.

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 6 - Comparative Examples 1 to 4 Both terminals of the molecular chain have Cnicht'roxysilyl groups.
f 1,500 O8 dimethylpolysiloxane 100
To 100 parts of a mixture of 9 parts of phenyltriethoxysilane and 0.1 part of water, 0.2 parts of various organotin compound catalysts shown in Table 1 (2) were added to form a room-temperature curable silicone rubber composition. When these β] were prepared, their pot life was as listed in Table 1, and these were poured into a mold and kept at room temperature for 24 hours.

The curing condition when the elastomer was slope-mounted for 96 hours was as shown in Table 1-12, and the compression set of the elastomer obtained by this curing was as shown in Table 1.

That is, in Examples 1 to 6, all waiting time curing state and compression set were good, but Comparative Example 1
Although the products listed in items 4 to 4 had sufficient pot life, they were poorly cured and had poor compression set of 45 to 70%.

Example 7. Comparative Examples 5 to 6 Example 1 except that the amount of bis(methylmaleoyldibutyltin) oxide added in Example 1 was changed to 0.3 parts.
A silicone rubber composition was prepared in the same manner as in C2 (Example 7).
), and the added amounts of dibutyltin dipenzoate and dibutyltin dilaurate in Comparative Examples 1 and 3 were increased to 0.5 parts and 0.6 parts, respectively, so that they had an industrial pot life and a time of 24 hours. A-acid (Comparative Examples 5 and 6) was made into a rubber-like substance, and Example 1 was prepared from these.
When a rubber-like material was made in the same manner as above and the permanent set by 70 degrees was measured, the results shown in Table 2 (g) were obtained.

Examples 8 to 10 - Comparative Examples 7 to 8 Molecular chain both ends 1: Having hydroxysilyl group, viscosity is 5
000 cs dimethylpolysiloxane 1,00 ic
, ethyl phosphoricate 40 (manufactured by Union Carbide Co., Ltd.)
(Product name) 5 parts 1 Bis(methyloleoyldibutyltin) oxide as a catalyst was added to 100 parts of a mixture of 3.3 parts of dimethylpolysiloxane with a viscosity of 20 as, in which both ends of the molecular chain were blocked with hydroxydimethylsilyl groups. 0.
When a silicone rubber composition was prepared by adding 0.01 to 0.60 parts and its condition was examined, the compression set of the elastomer thus obtained was measured, and the results shown in Table 3 below were obtained. Good results were obtained with compositions in which the amount of organotin compound added as a catalyst was 0.05 to 0.20 parts (Examples 8 to 10);
The composition containing 1 part (Comparative Example 7) has a long pot life, but hardening is poor and the compression set is very low.The composition containing 0.6 part of this (Comparative Example 8) has a long pot life. was short and the compression set was large.

Examples 11-15. Reference Examples 1 to 3 Okunyoko 1 with dihydroxysilyl groups at both ends of the molecular chain
+ 500 as dimethylpolysiloxane 100m (
2. 7.0 parts of tetraethoxysilane, 50 parts of various inorganic fillers, and 0.0 parts per 100 parts g of a mixture thereof.
A silicone rubber composition was prepared by adding 1 part of dibutyltin dibenzyl maleate, and the pot life, cured state after 24 hours and 96 hours, and compression set were measured. The results shown in g2 were obtained.

Although good results were obtained for Examples 11 to 15,
A composition using silica oxide with a pH of 2 as the filler (Reference Example 1), and a composition using wet silica and diatomaceous earth with a pH of 11 (Reference Example 2-3)
The curing condition after 24 hours was poor and the compression set was large.

Example 16 - Comparative Example 9-i.

Has a hydroxysilyl group at both ends of the molecular chain and has a viscosity of 1.
100 parts of 500 c8 dimethylpolyi/Cl chitin to 17 parts of phenyltriethoxysilane.

200 parts of quartz powder at pH 7 - 3 parts of fumed silica (pH 6σ) 20 parts of dimethylboryliloxane with a viscosity of 1,000 as, the molecular chain ends of which are capped with trimethylsilyl groups, and both molecular chain ends of which are capped with hydroxyl/dimethylsilyl groups. 7 parts of dimethylpolysiloxane having a viscosity IW of 15 cS were added to this mixture, and 0.1 part of nidibutyltin dibenzyl maleate was added to 100 ffil of this mixture to form a composition (Example 16). A composition (Comparative Example 9.10) was made by adding 0.1 part and 0.5 part of dibutyltin dilaure.

Next, we investigated the pot life of these compositions and their curing states after 24 hours and 96 hours.2 We measured the compression set, and the results shown in Table 5 below were obtained. While the composition of Example 16 showed good results in both cases, the composition of Comparative Example 9 had poor pot life, poor curing state, and poor compression set, and the composition of Comparative Example io had poor results. The pot life and cured condition were good, but the compression set was extremely large.

Example 17. Comparative Example 11-12 Viscous acid 1 having hydroxyl/zolyl groups at both ends of the molecule
, 500 cs of dimethylborisaxane, 7 parts of methyltrimethoxysilane, and 10 parts of quartz powder at pH 7.
0 part - molecular weight Dimethyl I/l with a viscosity of 25 as with both ends capped with trimethyl I/lyl groups + Corn oil 1
5 parts and 0.1 part of water were added, and 0.01 parts and 0.05 parts of dibutyltin dibenzyl maleate were added to 100 parts of this mixture to prepare the silicone rubber compositions of Comparative Example 11 and Example 17. Comparative G1i 1 was prepared by adding 0.5 parts of dibutyltin dilaurate to 100 parts of this mixture.
Two compositions were made.

Next, when we examined the curing state of these compositions after 24 to 96 hours, we found that the composition of Comparative Example 1 had poor curing, and the compositions of Example 17 and Comparative Example 12 (
When the compression set of the elanuttomer thus obtained was measured, as shown in Table 6, the elanuttomer of Example 17 showed a good hardening condition. The results are shown in Comparative Example 12σ]
J showed a large value.

・r-Continued amendment July 28, 1980 Manabu Shiga, Commissioner of the Patent Office 1.19 indications Patent Application No. 111448 1982 2 Title of invention Room temperature curable silicone rubber composition 3 Amended Things to do on the beach 1. Which relationship is the name of the patent applicant? (206) Shin-Etsu Chemical Co., Ltd. 4, agent 5, amendment order 11i.j "Volunteer" 1) 1 Hydrocarbon 2s described in line 609 of the specification ``is corrected to ``1 hydrocarbon monovarnish''.

2) [Methyloleoyldi'butyl] described on page 21, lines 8 to 9fT of the specification has been amended to "methylmaleoyloxydibutyl".

3) In Table 4 of Picture 25 of the Specification, reference example 11 is supplemented with [silicon oxide J'i=r fused silica].

4) Specification page 11, line 13, section 12, line 1, line 4, line 1
In Table 1 on page 8, Examples %1-3, 19th stroke, 2nd line, 20th
1"...Oil...] written on the 3rd line of the image, respectively.
Goiroxy..." he corrected.

Claims (1)

[Scope of Claims] 1.A) A linear organopolysiloxane having a hydroxyl group bonded to C disilicone at both ends of the molecule and having a viscosity of 500 to 1,000,000 as at -25°C. 100 parts by weight B) Organosilane and/or organosiloxane as a crosslinking agent having three or more alkoxy groups in one molecule 1 to 30 parts by weight C) Inorganic filler θ to 300 parts by weight Organotin compound represented by R' Receptacle R' 0.0 per 100 parts by weight of the above A) 10 B) + O) of the system catalyst
A room temperature curable silicone rubber composition comprising 3 to 0.4 parts by weight. 2. Organotin compounds include bis(methyl remaleoyldibutyltin) oxide, bis(ethylmaleoyldibutyltin) oxide, and bis(isoglobilmaleoyldibutyltin) oxide. Dibutyltin dihexyl maleate 1, dibutyltin dibenzyl maleate, dibutyltin diogtylphthalene 1-
The room-temperature curable v'J cone rubber composition 3 according to claim 1, wherein the inorganic filler has a pH of 3 to 10σ). Curable silicone rubber composition.