JPH0733446B2 - Method for producing curable composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for producing a condensation-type curable composition, and in particular, the curing time, which is a fatal drawback of the condensation-type, is significantly reduced. The present invention relates to a method for producing a rapidly curable condensation-type curable composition improved.

(Conventional Technology and Its Problems) Conventionally, condensation-curable compositions containing an organopolysiloxane as a component are well known and, in addition, they are very excellent in heat resistance, weather resistance, electrical characteristics, etc. It is used in various fields. Many curing methods have been proposed, including deacetic acid type, deoxime type, dealcohol type, and deacetone type. However, all of these are types that react with moisture in the air to gradually cure from the surface to the inside. For example, it takes about 7 to 10 days to cure 10 mm and about 1 month to cure 20 mm. . Especially when it is used as a FIPG Neil material for oil pans of automobile engines, almost all the surface is hardened because the engine is run for a test within about 1 hour after sealing. I was afraid to do it. When used to bond and fix electrical and electronic components, most of them are used on the line, so they need to be shipped within a few hours after sealing, but there is the inconvenience that they have to be left overnight for curing and curing. It was

In order to solve these problems, a method of dividing a conventional composition into a two-component type by dividing a main component into a curing agent is known, but the amount of the curing agent relative to the main component is very small, it is difficult to mix, and uniform curing It is difficult to balance the main agent and the curing agent, and even if the quantity ratio changes even a little, the pot life becomes extremely short, gelation occurs during mixing, and two-liquid curing does not occur There was a drawback that it became a one-liquid type, and there was a drawback that it was hardly practical.

(Means for Solving the Problems) In the present invention, a curable composition having a long pot life and quick curability is obtained by adding the following four components (A) to (D) as essential components. Has been successfully obtained.

That is, according to the method of the present invention, (A) the following general formula, X _3- nRnSiO (R ₂ SiO) mSiRnX _3- n [wherein, X is a hydrolyzable group and R may be the same or different. It is a monovalent hydrocarbon group, n is a number of 1 or 0, m is a corresponding organopolysiloxane terminated with silanol groups at both ends: HO (R ₂ SiO) mH has a viscosity of 100 to 1,000,000 cSt at 25 ° C. An organopolysiloxane represented by the formula: (B) the following average compositional formula, (R ¹ ) aSiO _{(4-a) / 2} [wherein R ¹ may be the same or different, and a monovalent hydrocarbon And a is a number of 1.90 to 2.05], and an organopolysiloxane having at least two hydroxyl groups bonded to a silicon atom in one molecule, (C) a condensation catalyst, and (D) a silica-based packing A curable composition containing an agent as an essential component is provided.

That is, according to the present invention, the above composition has the following general formula (1): HO (R ₂ SiO) mH (1) [wherein, R may be the same or different and is a monovalent hydrocarbon group. , M is a number at which the viscosity at 25 ° C. is 100 to 1,000,000 cSt], and an organopolysiloxane having a silicon atom-bonded hydroxyl group at the molecular end, represented by the following general formula (2): RnSiX _4- n ( 2) [wherein X is a hydrolyzable group, R may be the same or different, is a monovalent hydrocarbon group, and n is a number of 1 or 0] and mixed and heated. Then, an organopolysiloxane (A) represented by the following general formula, X _3- nRnSiO (R ₂ SiO) mSiRnX _3- n [wherein R, X, m and n have the above-mentioned meanings] is prepared. and then, the organopolysiloxane (a), the following average composition _{^{formula, (R 1) aSiO (4}} -a) / 2 wherein, R ¹ is the same Or a monovalent hydrocarbon group, and a is a number of 1.90 to 2.05], and an organopolysiloxane (B) having at least two hydroxyl groups bonded to a silicon atom in one molecule, It is produced by a method for producing a curable composition, which comprises blending a condensation catalyst (C) and a silica-based filler (D).

Component (A) Organopolysiloxane In the general formula representing the organopolysiloxane that is the essential component (A), the group R is a monovalent hydrocarbon group, specifically, methyl group, ethyl group, propyl group, vinyl. Examples thereof include a group, a phenyl group and a trifluoropropyl group.

As the hydrolyzable group represented by X, for example, acetoxy group, octanoyloxy group, acyloxy group such as benzoyloxy group, dimethylketoxime group, methylethylketoxime group, ketoxime group such as diethylketoxime group, methoxy group, Alkoxy group such as ethoxy group and propoxy group, isopropenyloxy group, 1-ethyl-
Alkenyloxy group such as 2-methylvinyloxy group, dimethylamino group, diethylamino group, butylamino group,
Amino group such as cyclohexylamino group, dimethylaminoxy group, aminoxy group such as diethylaminoxy group, N-
Methylacetamide group, N-ethylacetamide group, N
Examples thereof include an amide group such as a methylbenzamide group.

Among these, preferred are acetoxy group, methoxy group, ethoxy group, isopropenyloxy group and methylethylketoxime group.

The organopolysiloxane (A) having a reactive group at such a molecular end includes an organopolysiloxane having a terminal silanol group of the general formula (1) corresponding to the organopolysiloxane, and the following general formula (2): RnSiX _{4 -} in n ...... (2) formula, R, X and n are readily obtained by mixing heated and silane represented in, meaning described above.

The terminal silanol group-containing organopolysiloxane used here is conventionally known as a main raw material for silicone rubber, and is usually one in which both ends of its molecular chain are blocked with hydroxyl groups. There is no particular limitation on the type of organic group bonded to the silicon atom in this organopolysiloxane, and examples thereof include alkyl groups such as methyl group, ethyl group, propyl group and butyl group, cycloalkyl groups such as cyclopentyl group and cyclohexyl group. Group, vinyl group, alkenyl group such as allyl group, phenyl group, tolyl group, aryl group such as naphthyl group, aralkyl such as 2-phenylethyl group, alkoxy group such as methoxy group, ethoxy group, propoxy group, or the like. Examples thereof include a group in which some or all of the hydrogen atoms of the group are substituted with a halogen atom such as a chlorine atom or an amino group. This organopolysiloxane
100 to 1,000,000 cSt at 25 ° C, preferably 1,000 to 5
It must have a degree of polymerization such that it has a viscosity of 0,000 cSt, which means that the diorganopolysiloxane has a viscosity of 100 cSt.
When the viscosity is less than (25 ° C), it becomes difficult to obtain a cured product having excellent physical strength.
When it exceeds 000,000 cSt (25 ° C.), the viscosity of the composition containing it becomes too high, and as a result, the workability during use of the composition deteriorates.

Component (B) Silanol Group-Containing Organopolysiloxane The organopolysiloxane used as the component (B) in the present invention is represented by the above general formula (2) and has at least 2 hydroxyl groups bonded to a silicon atom in one molecule. And a terminal silanol group-containing organopolysiloxane which is a raw material for producing the reactive organopolysiloxane of the component (A). Etc. can be used, and the viscosity is preferably 100,000 cSt or less (25 ° C.), and even a low viscosity of 100 cSt or less can be used.

Component (B) is preferably 3 per 100 parts by weight of component (A).
It is used in a proportion of from 500 to 500 parts by weight, more preferably from 50 to 150 parts by weight. If the amount is too small, a sufficient amount of silanol cannot be given to the reactive groups of the component (A), so that the physical properties after curing deteriorate, and if the amount is too large, the silanol groups remain unreacted, resulting in extremely high heat resistance. Will be inferior to. When using an automatic mixer, it is preferable that the ratio of (A) and (B) is 1: 1 in view of ease of blending.

Condensation catalyst of component (C) Further, the curing catalyst of the component (C) in the resulting composition may be a known catalyst conventionally used in compositions of this type, and lead-2- Ethyl octoate, dibutyltin dioctoate, dibutyltin acetate, dibutyltin dilaurate, butyltin-2-ethylhexoate, iron-2-ethylhexoate, cobalt-2-ethylhexoate, manganese-2-ethylhexyl Organic carboxylic acids such as xoate, zinc-2-ethylhexoate, stannous caprylate, tin naphthenate, tin oleate, tin butyrate, titanium naphthenate, zinc naphthenate, cobalt naphthenate, and zinc stearate Metal salts of tetrabutyl titanate, tetra (2-ethylhexyl) titanate, triethanolamine Organic titanate esters such as tannate, tetra (isopropenyloxy) titanate, organosiloxy titanium, β
-Organotitanium compounds such as carbonyltitanium, alkoxyaluminum compounds, 3-aminopropyltriethoxysilane, aminoalkyl group-substituted alkoxysilanes such as N- (trimethoxysilylpropyl) ethylenediamine, hexylamine, amine compounds such as dodecylamine phosphate And salts thereof, quaternary ammonium salts such as benzyltriethylammonium acetate, lower fatty acid salts of alkali metals such as potassium acetate, sodium acetate and lithium oxalate, dialkylhydroxylamines such as dimethylhydroxylamine and diethylhydroxylamine, formulas Examples thereof include guanidine compounds and guanidyl group-containing silanes or siloxanes, but these are not limited to one kind and may be used as a mixture of two or more kinds.

If the amount of component (C) used is too small, it will take a long time to cure, and if it is thick, it will be difficult to uniformly cure it to the deep part. On the other hand, if the amount is too large, the curing time becomes extremely short, resulting in various inconveniences in workability, and the resulting cured product becomes inferior in heat resistance or weather resistance. Preferably relative to parts by weight
It is 0.01 to 5 parts by weight, and more preferably 0.1 to 3 parts by weight.

Component (D) Silica Filler Examples of the component (D) silica filler include finely powdered silica, silica airgel, precipitated silica, or those whose surfaces are treated with silane, and fused silica powder. This blending amount is the total amount of the above components (A) to (C)
If it is too small relative to 100 parts by weight, the cured product obtained from this composition will not exhibit sufficient mechanical strength, and if it is too large, the viscosity of the room temperature curable organopolysiloxane will increase and the workability will deteriorate. Not only that, but the rubber strength after curing is lowered, and it becomes difficult to obtain the desired rubber elastic body. 1 to
A range of 400 parts by weight is preferable, and a more preferable range is 5 to 2.
00 parts by weight.

Other compounding agents In addition, if necessary, the composition obtained by the method of the present invention may further include thixotropy-imparting agents such as polyethylene glycol and its derivatives, pigments, dyes, antioxidants, antioxidants, antistatic agents, antimony oxide. , Flame retardants such as chlorinated paraffin, boron nitride, thermal conductivity improvers such as aluminum oxide, antifungal agents, etc. are optional, and adhesion promoters, amino groups, epoxy groups, It is possible to mix various conventionally known additives such as so-called carbon functional silanes having a thiol group, metal salts of carboxylic acids, metal alcoholates, etc., which are also toluene, petroleum ether, etc. for convenience in use. It may be diluted with the hydrocarbon solvent, ketone, ester or the like.

(Operation) That is, in a conventional curable composition, an organopolysiloxane having hydroxyl groups at both ends of a molecular chain is used as a main agent, and a silane having a polyfunctional hydrolyzable group and a curing catalyst are used as a curing agent. Was used.

According to the studies of the present inventors, in such a curable composition, the rate at which the silanol group of the organopolysiloxane reacts with the curing agent, the hydrolyzable group at the polymer end formed by the reaction and the organopolysiloxane. It is recognized that there is a disadvantage that the curing reaction basically does not occur uniformly because the reaction rate of the siloxane with the silanol group is significantly different.

Therefore, according to the present invention, the end-reactive diorganopolysiloxane (component (A)) is prepared in advance by reacting the diorganopolysiloxane and the curing agent, and this is combined with the terminal silanol-containing diorganopolysiloxane ( Ingredient (B))
Since the silica filler and the silica filler (component (D)) are mixed in the presence of a curing catalyst (component (C)), the inconvenience caused by the difference in reaction rate is avoided, and the curing progresses uniformly and rapidly to a deep portion. However, a composition having a long pot life and excellent workability can be obtained.

(Example) Example 1 100 parts by weight of dimethylpolysiloxane Then, 5 parts by weight of methyltributanooxime silane was added, and the mixture was heated at 80 ° C. for about 3 hours to synthesize a polysiloxane in which both ends of the molecular chain were blocked with methyldibutanooxime silyl.

Next, a terminal methyldibutanoxime silyl-capped polysiloxane
90 parts by weight Surface-treated fumed silica R972 10 parts by weight (manufactured by Nippon Aerosil Co., Ltd.) 0.3 parts by weight of dibutyltin dilaurate (condensation catalyst) were uniformly mixed under N ₂ gas flow (mixture a).

Further, 1 part of R-972 was added to 90 parts by weight of dimethylpolysiloxane whose molecular chain ends were capped with silanol as used above.
A mixture of 0 parts by weight was prepared (mixture b).

Next, when equal amounts of these mixtures a and b were uniformly mixed, they could be mixed and stirred at 20 ° C. for 20 minutes, and after 3 hours, the whole was uniformly cured.

Further, form an a / b equivalent mixture into a sheet with a thickness of 2 mm and
After curing for 3 hours, the rubber physical properties were measured in accordance with JIS-K-6301. Hardness (JIS A) 25, tensile strength 1
It was 8 kgf / cm ² and the elongation was 420%.

Comparative Example 1 90 parts by weight of dimethylpolysiloxane And a homogeneous mixture of 10 parts by weight of the above fumed silica R-972 was prepared.

Further, 5 parts by weight of methyltributanooxime silane and 0.3 parts by weight of dibutyltin dilaurate were mixed, and an equal amount of this was mixed with the mixture b prepared above.

Even after 6 hours from the mixing, it did not harden to the deep portion, and only the surface portion was hardened.

When the total amount of methyltributanooxime silane and dibutyltin dilaurate was reduced from 5.3 parts by weight to 1.8 parts by weight and the same procedure was repeated, gelation occurred in about 5 minutes after mixing.

Examples 2-4 and Comparative Example 2 90 parts by weight of dimethylpolysiloxane Vinyltriisopropenyloxysilane 3 parts by weight Tetramethylguanidinopropyltrimethoxysilane 1.
5 parts by weight was added, and the mixture was heated at 80 ° C. for about 3 hours to synthesize a polysiloxane in which both ends of the molecular chain were blocked with vinyldiisopropenyloxysilyl groups.

Then, a homogeneous mixture of polysiloxane (both ends of which are blocked with vinyldiisopropenyloxysilyl groups) and fumed silica (supra) R-972 10 parts by weight was added as a condensation catalyst with vinyltriisopropenyloxysilane 3 Parts by weight Tetramethylguanidinopropyltrimethoxysilane 1.
5 parts by weight γ-aminopropyltriethoxysilane 1 part by weight was added to prepare a homogeneous mixture a.

Further, the following average composition Trisilanol (component b) having the above was mixed with the mixture a in the compounding ratio as shown in Table 1 to evaluate rubber physical properties and shear adhesive strength.

The shear adhesive strength is measured as shown in Fig. 1 by 25 mm ×
Two 100 mm x 1 mm aluminum plates 1 and 2 with thickness
Laminating with composition layer 3 having a length of 1 mm and a length of 10 mm,
A test piece was prepared. After leaving this test piece at 20 ° C. for 3 hours, the shear adhesive strength was measured by a tensile test.

(Effect of the Invention) According to the present invention, in a condensation-type curable composition, it is possible to significantly condense the curing time while maintaining an appropriate pot life.

The curable composition of the present invention can be used for adhesion / fixing of electric / electronic parts, FIPG sealing material for automobiles,
In particular, it is suitable as an adhesive or sealant for lines that cannot take a long time (unit of day) for curing and curing.

Further, the so-called addition type two-pack type using a platinum catalyst can be used for applications that cannot be applied due to catalyst poison.

For example, for electric and electronic parts, solder fuchs (platinum poison)
It is suitable for use in seals and pottings where there is a possibility of touching, as well as in automobile engines and FIPG seal materials for missions where gear oil, auto transmission oil, etc. may adhere. It can be widely used as a material, a caulking agent, a coating agent, a water repellent, a release treatment agent, and also as a fiber treatment agent.

[Brief description of drawings]

FIG. 1 shows the test pieces used for measuring the shear adhesive strength of the compositions in Examples 2 to 4 and Comparative Example 2.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tsuneo Kimura 2-13-1, Isobe, Annaka-shi, Gunma Shin-Etsu Chemical Co., Ltd. Silicone Electronic Materials Research Laboratory (56) Reference JP-A-54-116055 (JP, A) JP-A-57-179243 (JP, A) JP-A-61-127718 (JP, A) JP-B-45-20915 (JP, B1) JP-B-35-13496 (JP, B1)

Claims (1)

[Claims] 1. The following general formula: HO (R ₂ SiO) mH [wherein, R may be the same or different and is a monovalent hydrocarbon group, and m is a number such that the viscosity at 25 ° C. is 100 to 1,000,000 cSt. And an organopolysiloxane having a silicon atom-bonded hydroxyl group at the molecular end represented by the following general formula, RnSiX _4- n [wherein, X is a hydrolyzable group, and R is the same or different. It is also a monovalent hydrocarbon group, and n is a number of 1 or 0] and mixed with a silane compound represented by the formula: X _3- nRnSiO (R ₂ SiO) mSiRnX _3- n [ In the formula, R, X, m and n have the above-mentioned meanings], an organopolysiloxane (A) represented by the following formula is prepared, and then the organopolysiloxane (A) is mixed with the following average compositional formula (R ¹ ) aSiO in _{(4-a) / 2} formula, R ¹ is the same or different, is a monovalent hydrocarbon radical, a is 1.90 to 2.05 Of the organopolysiloxane (B) having at least two hydroxyl groups bonded to a silicon atom in one molecule, a condensation catalyst (C), and a silica-based filler (D). A method for producing a curable composition.