JPH048469B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention provides a room-temperature curable composition for sealing filter devices, particularly for producing a clean gas body required in the production of semiconductor crystals, devices, various electronic equipment, hospitals, biological laboratories, etc. It is said to be useful for sealing filter devices used for The present invention relates to a filter device sealing composition that is room temperature curable, highly adhesive, and has good injection workability. (Prior art) The use of silicone gel compositions for sealing filter devices is disclosed in Japanese Patent Application Laid-open No. 59-193112.
It has been proposed in the Publication No. However, since this silicone gel composition was developed for use in semiconductor device coatings, artificial breast materials, bedsore prevention agents for long-term care patients, shock absorbers for automobiles, etc., it has not been possible to use it in filter devices. When used for sealing, for example, compositions containing difunctional organohydrodiene polysiloxane as a crosslinking agent (see U.S. Pat. No. 3,020,260)
When cured at room temperature after a pot life of about 8 hours, hydrogen atoms bonded to silicon atoms (≡SiH bonds) partially hydrolyze, resulting in poor surface curing properties and making it difficult to obtain a suitable room temperature curable composition. There is a disadvantage that it becomes
The silicone gels disclosed in JP-A-51-126387 and JP-A-56-143241 all relate to thermosetting compositions, and no explanation is given regarding room temperature curability. (Structure of the Invention) The present invention relates to a room-temperature curable silicone gel composition that is particularly suitable for sealing a filter device for gas purification.
formula (Here, R ¹ and R ² are methyl or phenyl groups,
The viscosity at 25°C, where n is a positive integer, is
Organopolysiloxane with a size of 100 to 5000 cS, both ends of the molecular chain are blocked with diorganovinylsilyl groups.
100 parts by weight, 2) A formula for supplying 0.4 to 2.0 moles of hydrogen atoms bonded to silicon atoms (≡SiH bonds) per mole of vinyl groups in the first component.

[Formula] (where R ³ is the same or different unsubstituted or substituted saturated monovalent hydrocarbon group, a = 1.3 to 2.0, b =
0.02 to 1.0 and a+b=1.8 to 3.0). Organohydrodiene polysiloxane which also contains at least two ≡SiH bonds in one molecule and is compatible with the first component, 3) consisting of (CH ₃ ) ₃ SiO _0.5 unit and SiO ₂ unit, (CH ₃ ) ₃ SiO _0.5 /SiO ₂ =0.4 to 1.0 mol/
It is a mole. It consists of 1 to 50 parts by weight of methylsiloxane that is compatible with the first component, 4) a catalytic amount of a platinum compound, and 5) 0 to 5 parts by weight of a reaction inhibitor, and has an elastic modulus of 5 x 10 ³ to 50 parts by weight after curing. It is characterized by having a density of 5×10 ⁴ dynes/cm ² . That is, as a result of various studies by the present inventors regarding silicone compositions as sealants for gas purification filter devices, we have found that this silicone composition is suitable for sealing air filters at room temperature so that it can be applied not only in factories but also on-site. It has a moderate pot life at 25°C and 24°C when used.
It must have room temperature curing performance to cure without oil bleed on the surface within hours, it must have moderate tackiness to adhere well to the adherend and exhibit a sufficient sealing effect, and after curing, it must be rated at 5x 10 ³ ~
It becomes an elastic body with a modulus of elasticity of 5 × 10 ⁴ dynes/cm ² ,
The gel must be able to withstand thermal expansion in summer and winter, and when it hardens, it generates organic nitrogen compounds, sulfur compounds, or low-molecular silicone compounds, which can cause damage to microswitches, grounding parts, and prints incorporated in filter devices. In order to avoid having a negative impact on the substrate or disadvantageous gel curing, an addition reaction type is used.
Focusing on the fact that it is best to have a volatile content of 1% or less, we have conducted research on compositions that meet this condition. It has been shown that a composition comprising an organohydrodiene polysiloxane represented by formula (2) and methylsiloxane as the third component, which is subjected to an addition reaction in the presence of a platinum-based catalyst, satisfies these conditions. They discovered this and completed the composition of the present invention. The organopolysiloxane as the first component constituting the composition of the present invention is represented by the above formula (1). where R ₁ and R ² are each a methyl group or a phenyl group, and n is a positive integer. It is said that both ends of the molecular chain are blocked with diorganovinylsilyl groups, but if the viscosity at 25°C is less than 100 cS, the cured product obtained from this composition will have poor elasticity, but if it is more than 5000 cS, The fluidity of this composition deteriorates and it becomes difficult to dilute it with an organic solvent for coating or potting, so it needs to be in the range of 100 to 5000 cS, and this includes the following formula: is exemplified. (n=80-600), (k, l are positive integers, k+l=30~600, k/
l≧1.0) (q, r are positive integers, q+r=30 to 600) Furthermore, the organohydrodiene polysiloxane as the second component constituting this composition is expressed by the above formula (2).

[Formula] This R is an alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group, a phenyl group,
Aryl groups such as tolyl groups, cycloalkyl groups such as cyclohexyl groups, and some or all of the hydrogen atoms bonded to carbon atoms of these groups are replaced with halogen atoms, cyano groups, phenyl groups, alkoxysilyl groups, epoxy groups, etc. The same or different unsubstituted or substituted saturated monovalent hydrocarbons selected from substituted chloromethyl groups, trifluoropropyl groups, epoxidized propyl groups, etc., preferably 50 mol% of which are methyl groups, a is 1.3~
2.0, b is 0.02 to 1.0, and a+b is 1.8 to 3.0, which is included here. Since it forms a structure, it is necessary to contain at least two ≡SiH bonds in one molecule. This organohydrodiene polysiloxane may be linear, branched, or cyclic, as long as it is compatible with the first component, and examples thereof include the following.

【formula】

(CH ₃ ) ₂ Copolymer of _0.5 units of HSiO and ₂ units of SiO (where c is 0 or a positive integer, d is a positive integer of 2 or more, o+d≧3, e and f are positive integers, R ⁴ R ⁵
teeth −C ₃ H ₇ , −CH ₂ CH ₂ Si(OCH ₃ ) ₃ ,

The amount of this organohydrodiene polysiloxane blended is such that the number of ≡SiH bonds contained therein is 0.4 mol or less per 1 mol of vinyl groups in the organopolysiloxane as the first component. If the amount exceeds 2.0 mol, the cured product obtained from this composition will become too soft, and if the amount exceeds 2.0 mol, it will easily foam during curing, and the hardness of the cured product obtained from this will change over time, causing the composition to become too soft. This ≡SiH bond is the primary
It is necessary to set the amount to 0.4 to 2.0 mol per mol of vinyl group in the component, but this preferred range is
The amount is 1.0 to 1.3 moles. Next, methylsiloxane as a third component constituting this composition is for imparting excellent adhesiveness to the composition of the present invention, and this addition further strengthens the adhesiveness of the composition. . This methylsiloxane is said to consist of _0.5 units of (CH ₃ ) ₃ SiO and ₂ units of SiO, but their molar ratio is
If the molar ratio of (CH ₃ ) ₃ SiO _0.5 /SiO ₂ is 0.4, the compatibility with the organopolysiloxane as the first component deteriorates, and if it exceeds 1.0, the tackiness of the composition decreases. ~1.0, this preferred range is
It is considered to be 0.5 to 0.8. This methylsiloxane is produced by combining, for example, trimethylchlorosilane or hexamethyldisiloxane to obtain _0.5 units of (CH ₃ ) ₃ SiO with silicon tetrachloride, methyl silicate, ethyl polysilicate, or sodium silicate as a source of SiO ₂ in alcohol under acidic conditions with hydrochloric acid. It can be obtained by cohydrolysis using a solvent. If the amount of this methylsiloxane is less than 1 part by weight, the tackifying effect will be insufficient, and if it is more than 50 parts by weight, the viscosity of the entire composition will increase. and make this the first
When mixed with the component and the second component, it becomes difficult for air bubbles to escape, and this component is a resin with a moderate amount of silanol groups, and if a large amount of this component is added, the composition tends to foam during curing. The preferred range is 5 to 30 parts by weight, but since this is usually a solid, it can be prepared as a solution in xylene, toluene, etc. It is preferable to add it to one component. Further, the platinum compound as the fourth component in this composition is used as a catalyst for promoting the addition reaction between the first component and the second component, and therefore this is not suitable for ordinary hydrosilation. Examples of these include chloroplatinic acid, alcohol-modified chloroplatinic acid, and complex salts of chloroplatinic acid and olefins and vinyl siloxanes.
It is preferable to use it by dissolving it in a ketone, ether, or hydrocarbon solvent. The amount of the fourth component to be used may be a catalytic amount, and this amount may be adjusted as appropriate depending on the desired curing speed, but from an economic point of view, it is difficult to obtain good room temperature curing performance. The amount of platinum may be in the range of 1 to 30 ppm based on 100 parts by weight of the first component. The fifth component in this composition is a catalyst that promotes the addition reaction between the first component and the second component, and controls the catalytic ability of platinum or a platinum compound as the fourth component to cure the composition. An optional component added to adjust the time, which may also be a known component, such as a vinyl group-containing siloxane or an acetylene compound represented by the formula CH ₂ =CHR ¹ SiO (R ¹ is the same as above). , ionic compounds of heavy metals, etc., but the amount added should be 5 parts by weight or less per 100 parts by weight of organopolysiloxane as the first component, since it gives a preferable curing speed to this composition. Often, this preferred range is between 0.003 and 3 parts by weight. The composition of the present invention can be obtained by mixing predetermined amounts of the above-described first to fifth components, and these blending amounts have a pot life of 12 at 25°C.
The structure and amount of the second component as a crosslinking agent, the fourth component as a catalyst, and the amount of the fifth component as a reaction control agent are adjusted so that the curing occurs within 24 hours at room temperature. This is desirable. This composition usually has a first component as a main component, for example, a first liquid in which a third component, a fourth component, and a fifth component are added to the above-mentioned first component, and a second component as a crosslinking agent as a main component. For example, a second liquid obtained by adding a third component and a part of the first component to the second component is mixed at 1:1.
It is often stored and sold as a two-part type that is mixed at a mixing ratio of 1:1, and if an automatic mixing and dispensing machine is used, the pot life at 25℃ is 5 to 20 days.
It is possible to obtain a product with good workability that has a curing time of 20 to 60 minutes. This composition is made sticky by the addition of the third component, and the gel has an elastic modulus of 5,000 to 50,000 dynes/cm ² . It is best to adjust the amount of functional groups and degree of polymerization of the component, and in order to give it strong adhesive strength, the organohydrodiene polysiloxane as the second component must have two ≡SiH bonds in one molecule. It is better to use one with three or more. In addition, since this composition is used for filter devices, it is necessary to ensure that it does not adversely affect the various electronic devices used in the filter device. It is preferable that the amount of volatile components of each constituent component be as low as possible. It should be noted that it is optional to add non-functional organopolysiloxane to the composition of the present invention in order to lower its viscosity and improve workability, and to lower the gel elastic modulus after curing. This reduces thermal shrinkage during curing of this composition, reduces the coefficient of thermal expansion of the cured elastomer, improves thermal stability, weather resistance, chemical resistance, flame retardance, and mechanical strength.
Fillers may be added for the purpose of lowering gas permeability, such as fumed silica, quartz powder, glass fiber, carbon black, iron oxide,
Examples include metal oxides such as titanium oxide and cerium oxide, and metal carbonates such as calcium carbonate and magnesium carbonate, but suitable pigments, dyes, or antioxidants may also be added to these as necessary. . Furthermore, since the composition of the present invention is room temperature curable, sealing of filter devices with it is usually carried out at room temperature, but this application may be carried out under heating if necessary. Accordingly, the curing time can be shortened. 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. Example 1 (CH ₃ ) ₃ SiO _0.5 /SiO 2 = _0.7 is added to 100 parts of linear dimethylpolysiloxane having a viscosity of 1000 cS and containing 0.012 mol/100 g of vinyl groups with both ends of the molecular chain capped with dimethylvinylsilyl groups. After adding 200 parts of a 50% toluene solution of methylsiloxane resin consisting of _0.5 units of (CH ₃ ) ₃ SiO and ₂ units of SiO (mol/mol) and uniformly dissolving it, the mixture was maintained at 1 mmHg and 150°C for 5 hours. When the solvent was stripped, a yellow transparent oily liquid (hereinafter abbreviated as stripping liquid A) having a specific gravity of 1.07, a viscosity of 200 P, and a volatile content of 0.7% was obtained. Next, add 90 parts of the linear dimethylpolysiloxane described above to 20 parts of this stripping solution A, and add When the SiH content is 0.0050 mol/g, the viscosity is
0.5 parts of methylhydrodiene polysiloxane with 100cS, formula When the SiH content is 0.0013 mol/g, the viscosity is
5 parts of 18cS methylhydrodiene polysiloxane, a complex salt of chloroplatinic acid and 1,1,3,3-tetramethyl-1,3-divinyldisiloxane (platinum content 0.5%, Cl/Pt = 1.2 mol/mol) ) 0.15 parts and formula When 0.03 part of methylvinyl cyclic siloxane shown by was added and mixed uniformly to make a composition,
This product has a pot life of 30 minutes at 25℃;
After 60 minutes, it cured without oil bleed on the surface, resulting in a cured product with an elastic modulus of 15,000 dynes/cm ² and a volatile content of 0.6%, which exhibited favorable tackiness to the touch. Example 2 To 10 parts of the stripping solution A prepared in Example 1, the formula 95 parts of a linear methylphenylpolysiloxane with a vinyl group weight of 0.015 mol/100 g and a viscosity of 700 cS, with the formula The SiH content is 0.0013 mol/g and the viscosity is
6.5 parts of methylhydrodiene polysiloxane of 30cS, 0.03 part of 2-methylhexanol modified product of chloroplatinic acid (platinum content: 2% by weight) and Example 1
When 0.03 part of the methylvinyl cyclic siloxane used in was added and mixed uniformly to make a composition,
This product has a pot life of about 3 hours at 25℃.
After a period of time, it hardens without any oil bleed on the surface, resulting in a cured product with an elastic modulus of 10,000 dynes/cm ² and a volatile content of 0.02%.

[Sealing construction of filter device]

Clean pliers filter device whose work table size is 620 x 1850 mm (3 x 620 x 1850 mm)
As shown in Fig. 1, the lower part 3 of the support frame 2 supporting the filter unit is sealed with a sealant. The compositions prepared in Examples 1 and 2 and the commercially available silicone rubber KE45RTV (trade name manufactured by Shin-Etsu Chemical Co., Ltd.) as Comparative Example 3 were used as compositions, and these were placed in a glass shear dish and poured. When the composition was allowed to stand for 20 hours at 25°C to cure, the results shown in Table 1 were obtained.
When a 100 μm and 25 mm wide polyethylene terephthalate film was bonded together and cured at 25°C for 24 hours, they were peeled off and the peeling force was measured, and the results shown in Table 1 were obtained. Ta.

[Table] From this result, the adhesive strength of Examples 1 and 2 is strong and is satisfactory as a sealant, but the adhesive strength of Comparative Examples 1 and 2 is insufficient, and that of Comparative Example 3. It was confirmed that none of the compounds in this comparative example were satisfactory as sealants because they emitted a small amount of toxic gas when cured, which inhibited the curing of the addition type gel.

[Brief explanation of drawings]

FIG. 1 shows a longitudinal sectional view of a method for testing the sealing of a filter device. 1... Filter unit, 2... Support frame,
3...Sealing agent.

Claims (1)

[Claims] 1 Formula (1) (Here, R ¹ and R ² are methyl groups or phenyl groups, and n is a positive integer), an organopolymer with a viscosity of 100 to 5000 cS at 25°C and whose molecular chain ends are blocked with diorganovinylsilyl groups. 100 parts by weight of siloxane, (2) 0.4 hydrogen atoms bonded to silicon atoms (≡SiH bond) per mole of vinyl group in the first component
~2.0 moles of the formula [Formula] (where R ³ is the same or different unsubstituted or substituted saturated monovalent hydrocarbon group, a = 1.3 to 2.0, b = 0.02 to 1.0, and a + b = 1.8
~3.0), an organohydrodiene polysiloxane containing at least two ≡SiH bonds in one molecule and compatible with the first component, (3) (CH ₃ ) ₃ SiO _0.5 unit and SiO ₂ unit. (CH ₃ ) ₃ SiO _0.5 /SiO ₂ =0.4 to 1.0 mol/mol, 1 to 50 parts by weight of methylsiloxane which is compatible with the first component, (4) a catalytic amount of a platinum compound (5 ) reaction inhibitor 0 to 5 parts by weight, and the elastic modulus after curing is 5 x 10 ³ to 5 x 10 ⁴
A room temperature curable silicone gel composition for sealing a filter device, characterized in that it has a dynes/cm ² .