JPH07113082B2 - 1-pack type room temperature curable organopolysiloxane composition - Google Patents

Description

TECHNICAL FIELD The present invention relates to a one-pack type room temperature curable organopolysiloxane composition, which is particularly excellent in long-term storage stability under sealed conditions. The present invention relates to a packaged room temperature curable organopolysiloxane composition.

[Prior Art and Problems to Be Solved] Conventionally, various types of one-pack type room temperature curable organopolysiloxane compositions which are cured into an elastomer at room temperature by contact with moisture in the air are known. But
In particular, those that release alcohol and cure are characterized by not having an unpleasant odor and by not corroding metals, and are preferably used for sealing, bonding and coating of electric and electronic devices. There is. As a representative example of this type, Japanese Patent Publication No. 39-27,643 is disclosed, which discloses a composition comprising a hydroxyl end-blocked organopolysiloxane, an alkoxysilane and an organotitanium compound. Further, JP-A-55-43,119 discloses a composition comprising an alkoxysilyl end-capped organopolysiloxane, an alkoxysilane and an alkoxytitanium. However, these compositions have a problem in long-term storage stability under sealed conditions. That is, there is a drawback in that the mechanical strength of a cured product that has been stored for a long time under sealed conditions is significantly lower than the mechanical strength of the cured product before storage.

An object of the present invention is to provide a one-pack type room temperature curable organopolysiloxane composition which is free from the above-mentioned drawbacks and has excellent long-term storage stability under sealed conditions.

[Means for Solving Problems and Its Action] This object is to provide a one-pack type organopolysiloxane composition that cures at room temperature while releasing alcohol.
This is achieved by using a titanium chelate compound as a curing catalyst and further adding β-diketone or β-ketonic acid ester.

That is, the present invention provides (A) a substantially linear organopolysiloxane having a viscosity of 20 to 1,000,000 centistokes at 25 ° C. and a molecular chain end blocked with a hydroxyl group, an alkoxy group or an alkoxysilylalkyl group. 100 parts by weight (B) General formula RaSi (OR ¹ ) ₄ -a (wherein R is a monovalent hydrocarbon group, R ¹ is an alkyl group or an alkoxylated alkyl group, a
Is 0.5 or 15 parts by weight (C) Titanium chelate catalyst 0.1 to 10 parts by weight (D) β-diketone or β-ketone ester 0.01 to 5 The present invention relates to a one-pack type room temperature curable organopolysiloxane composition comprising 1 part by weight.

The component (A) used in the present invention has a viscosity at 25 ° C. of 20.
A substantially linear organopolysiloxane having a molecular chain terminal of ˜1,000,000 centistokes and having a molecular chain terminal blocked with a hydroxyl group, an alkoxy group or an alkoxysilylalkyl group serves as a base material for the composition of the present invention. The term “substantially straight chain” means not only a completely straight chain but also a slightly branched straight chain.

Examples of the organic group in this organopolysiloxane include an alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group, and an octyl group; an alkenyl group such as a vinyl group and an allyl group; a phenyl group, a tolyl group, and the like. Aryl group; benzyl group; substituted alkyl groups such as 3,3,3-trifluoropropyl group, 3-chloropropyl group and 3-cyanoalkyl group are exemplified. As the organopolysiloxane, dimethylpolysiloxane, methylethylpolysiloxane, methyloctylpolysiloxane, methylvinylpolysiloxane, methylphenylpolysiloxane,
Examples include methyl (3,3,3-trifluoropropyl) polysiloxane, copolymers of dimethylsiloxane and methylphenylsiloxane, and copolymers of dimethylsiloxane and methyl (3,3,3-trifluoropropyl) siloxane. . The end of the molecular chain of this organopolysiloxane is blocked with a hydroxyl group, an alkoxy group or an alkoxysilylalkyl group. As the molecular chain end blocked by the hydroxyl group Is exemplified, and as a molecular chain end blocked by an alkoxy group, Is exemplified, and as a molecular chain end blocked by an alkoxysilylalkyl group, Is exemplified.

This organopolysiloxane has a poor rubber elasticity at the time of curing when the viscosity is too low, and the extrusion work becomes difficult when the viscosity is too high, so that it is 20 to 1,000,000 centistokes at 25 ° C, but preferably 100 to 100,000 centistokes. Is.

Component (B) used in the present invention has the general formula RaSi (OR ¹ ) ₄ -a (wherein R is a monovalent hydrocarbon group, R ¹ is an alkyl group or an alkoxylated alkyl group, and a is 0 or 1). The alkoxysilane represented by) or its partial hydrolysis-condensation product acts as a crosslinking agent for the component (A). The composition of the present invention is produced by contacting with moisture in the air (A).
The component is crosslinked and cured by the component (B). At that time, the component (C) acts as a catalyst.

Specific examples of the component (B) include tetramethoxysilane,
Tetraethoxysilane, tetrafunctional alkoxysilanes such as methyl cellosolve orthosilicate, trifunctional such as methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, vinyltrimethoxysilane, phenyltrimethoxysilane, and methyltrimethoxyethoxysilane. Examples thereof include alkoxysilanes and their partial hydrolysis-condensation products. These may be used alone or in combination of two or more. Further, in order to impart a low modulus to the rubber elastic body after curing, bifunctional alkoxysilanes such as diphenyldimethoxysilane and dimethyldimethoxysilane may be additionally added.

The amount of component (B) added is 100 parts by weight of component (A).
Although it is 0.5 to 15 parts by weight, when the end of the component (A) is blocked with a hydroxyl group, the number of moles of the alkoxy group in the component (B) exceeds the number of moles of the hydroxyl group in the component (A). It is preferable to adjust the amount. When each end of the component (A) is blocked with one alkoxy group, the amount of the component (B) added is preferably 2 to 15 parts by weight.

The component (C) used in the present invention is a catalyst for curing the composition of the present invention in the presence of moisture, and is a titanium chelate catalyst from the viewpoint of storage stability under sealed conditions. The titanium chelate catalyst has a general formula (X represents a group selected from a monovalent hydrocarbon group, an alkoxy group and an amino group, R ¹ is as described above, R ² is an alkyl group or a halogenated alkyl group, R ³ is a hydrogen atom or a lower alkyl group. Group or a lower acyl group, R ⁴ is a hydrogen atom or a lower alkyl group, and m is a positive number from 1 to 6), bis (β-diketone) titanium, bis (β-ketonic acid) Ester) titanium is illustrated. Specific examples of the component (C) include diisopropoxybis (ethylacetoacetate) titanium, diisopropoxybis (acetylacetone) titanium, dibutoxybis (methylacetoacetate) titanium and formulas. A compound represented by, bis (acetylacetone) titanium,
There is bis (ethyl acetoacetate) titanium.

The amount of component (C) added is 0.1 with respect to 100 parts by weight of component (A).
To 10 parts by weight, preferably 0.3 to 6 parts by weight. This is because if the addition amount is too small, the composition of the present invention will be cured slowly, and if it is too large, the curing will be too early or the storage stability will be deteriorated.

Component (D) used in the present invention, β-diketone or β
The ketonic acid ester is an essential component for improving the long-term storage stability of the composition of the present invention under sealed conditions.

Specific examples of the component (D) include β-diketones such as acetylacetone, propionylacetone, butyrylacetone, isobutyrylacetone and caproylacetone, β-ketones such as ethyl acetoacetate, methyl acetoacetate and β-ketobutyrate. There are acid esters. These compounds are
It can be a chelate ligand of the titanium chelate compound, and it is preferable to use the same compound as the chelate ligand of the titanium chelate compound of the component (C).

The amount of component (D) added is in the range of 0.01 to 5 parts by weight, preferably 0.02 to 100 parts by weight, of component (A).
It is in the range of 3 parts by weight. This is because if the addition amount is too small, the effect of improving the storage stability is insufficient, and if it is too large, the curability of the composition deteriorates.

There is no particular limitation on the method of adding the component (D), and the component (D) may be added alone, or β- which may be the component (D) as a chelate ligand during the production of the titanium chelate compound of the component (C). The diketone and / or β-ketonate ester may be used in excess and left as it is for use. Further, β-diketone and β-ketone ester may be used in combination, two or more different β-diketones may be used in combination, or two or more different β-ketone esters may be used in combination.

In addition to the above-mentioned components (A) to (D), the composition of the present invention may be in the form of fine powder in order to improve the flow characteristics before curing and the mechanical strength after curing, if necessary. Inorganic fillers can also be added. As the inorganic filler, dry silica, wet silica, fine quartz powder, calcium carbonate, fumed titanium dioxide, diatomaceous earth, aluminum hydroxide,
Examples thereof include fine particle alumina, magnesia, zinc oxide, zinc carbonate, and those obtained by surface-treating these with silanes, silazanes, low polymerization degree polysiloxanes, organic compounds and the like.

Furthermore, an organic solvent, an antifungal agent, a flame retardant, a heat-resistant agent, a plasticizer, a thixotropy imparting agent, an adhesion promoter, a curing accelerator, a pigment and the like can be added to the composition of the present invention.

The composition of the present invention can be easily produced by mixing the components (A) to (D) and, if necessary, various additives in a state where moisture is blocked. The composition of the present invention is
It is a so-called one-pack type room temperature curable organopolysiloxane composition that can be stored for a long period of time of not less than one year, and is cured into a rubber-like elastic body by being exposed to moisture in the air during use.

The composition of the present invention is used as a sealing agent for electric / electronic parts, an adhesive or a moisture-proof coating agent, as an adhesive or coating agent for glass products, ceramic products, metal products and plastic products, or as a coating agent for glass cloth, or It is useful as a sealing agent for construction.

[Examples] Hereinafter, the present invention will be described with reference to Examples. In the examples and comparative examples, all parts mean parts by weight,
Viscosity is the value at 25 ° C, and cs means centistokes.

Example 1 80 parts of α, ω-dihydroxydimethylpolysiloxane having a viscosity of 15,000 cs, 20 parts of α, ω-di (trimethylsiloxy) dimethylpolysiloxane having a viscosity of 50 cs, and 100 parts of fatty acid-treated light calcium carbonate were depressurized. Mix until uniform below. To this mixture, 5.0 parts of methyltrimethoxysilane, 2.0 parts of titanium diisopropoxy-bis (ethylacetoacetate) and 1.0 part of ethyl acetoacetate were added and mixed under a moisture barrier until uniform. From the obtained one-pack type room temperature curable organopolysiloxane composition, thickness
Create a 3mm sheet and cure at room temperature for 7 days, then use JIS K 6
According to 301, physical properties of rubber (hardness, tensile strength, elongation) were measured. The measurement results are shown in Table 1. Then, the composition was sealed and stored at room temperature for 1 year, and then the rubber physical properties were measured in the same manner as above. The results are also shown in Table 1.

Comparative Example 1 A one-pack type room temperature curable organopolysiloxane composition was prepared under the same conditions as in Example 1 except that ethyl acetoacetate was not added. Using this composition, the same test as in Example 1 was conducted and the results are shown in Table 1.

It can be seen that the cured product of Example 1 has far less reduction in hardness and tensile strength with storage for one year than the cured product of Comparative Example 1.

Example 2 100 parts of α, ω-dihydroxy-dimethylpolysiloxane having a viscosity of 4,000 cs and 100 parts of fatty acid-treated light calcium carbonate were mixed under reduced pressure until uniform. To this mixture, 4.0 parts of methyltrimethoxysilane, 1.5 parts of diisopropoxy-bis (acetylacetone) titanium and 0.10 parts of acetylacetone were added and mixed under a moisture barrier until uniform.

The same test as in Example 1 was carried out on the obtained one-pack type room temperature curable organopolysiloxane composition, and the results are shown in Table 1.

Comparative Example 2 A one-pack type room temperature curable organopolysiloxane composition was prepared under the same conditions as in Example 2 except that acetylacetone was not added. Using this composition, the same test as in Example 1 was carried out and the results were
Shown in the table.

It can be seen that the cured product of Example 2 has far less decrease in hardness and tensile strength with storage for one year than the cured product of Comparative Example 2.

Example 3 100 parts of α, ω-di (methyldimethoxysiloxy) -dimethylpolysiloxane having a viscosity of 12,000 cs and 100 parts of ground calcium carbonate were mixed under reduced pressure until uniform. To this mixture, 4.0 parts of methyltrimethoxysilane, 2.0 parts of titanium diisopropoxy-bis (ethylacetoacetate) and 0.5 parts of ethyl acetoacetate were added and mixed under a moisture barrier until uniform.

The 1-pack type room temperature curable organopolysiloxane composition thus obtained was tested in the same manner as in Example 1 and the results are shown in Table 1.

Comparative Example 3 A composition was prepared under the same conditions as in Example 3 except that ethyl acetoacetate was not added. Table 1 shows the results of the same tests as in Example 1 performed on this composition.

It can be seen that the cured product of Example 3 has far less decrease in hardness and tensile strength with storage for one year than the cured product of Comparative Example 3.

[Effects of the Invention] Since the one-pack type room temperature-curable organopolysiloxane composition of the present invention comprises the above-mentioned predetermined amounts of each of the components (A) to (D), the conventional one-pack type dealcohol type room temperature-curable composition. Compared with the organopolysiloxane composition, it is characterized by excellent long-term storage stability under sealed conditions.
That is, the mechanical properties of the cured product after long-term storage under sealed conditions are almost the same as the mechanical properties of the cured product before storage.

Claims (1)

[Claims] 1. A) The viscosity at 25 ° C. is 20 to 1,000,000.
Centistokes, substantially linear organopolysiloxane whose molecular chain ends are blocked with a hydroxyl group, an alkoxy group or an alkoxysilylalkyl group 100 parts by weight (B) General formula RaSi (OR ¹ ) ₄ -a (formula Wherein R is a monovalent hydrocarbon group, R ¹ is an alkyl group or an alkoxylated alkyl group, a
Is 0.5 or 15 parts by weight (C) Titanium chelate catalyst 0.1 to 10 parts by weight (D) β-diketone or β-ketone ester 0.01 to 5 A one-pack type room temperature curable organopolysiloxane composition comprising 1 part by weight.