JPH0350268A - Curable composition - Google Patents

Abstract

PURPOSE:To significantly shorten the curing time while retaining the suitable pot life by compounding two specific organopolysiloxanes and a condensation catalyst. CONSTITUTION:100 pts.wt. organopalysiloxane with both molecular terminals represented by a general formula SiRnX3-n (wherein X is a hydrolyzable group; R is upsilon monovalent hydrocarbon group; and n is 0 or 1), 3-500 pts.wt. organopolysiloxane with at least two silanol groups in the molecule, and 0.01-5 pts.wt. condensation catalyst are compounded as essential components. As the condensation catalyst, a generally known one may be used.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a condensation type curable composition, and in particular, the slow curing time, which was considered a fatal drawback of the condensation type, has been significantly improved. The present invention relates to a fast-curing condensation type curable composition.

(Prior art and its problems) Conventionally, condensation-curable compositions containing organopolysiloxanes are well known, and they have excellent heat resistance, weather resistance, electrical properties, etc., and have been used in various applications. used in the field. Many curing methods have been proposed, including acetic acid removal type, oxime removal type, alcohol removal type, and acetone removal type. However, these are all types that react with moisture in the air and gradually harden from the surface to the inside; for example, it takes about 7 to 10 days to harden 10 mm, and about 1 month to harden 20 mm. . Especially FIP for oil pan of automobile engine.
C: When used as a sealing material, the test run of the engine is performed within about an hour after sealing, so only the surface is hardened, so there is a risk of problems such as oil leakage. Ta. In addition, when used to adhesively fix electrical and electronic parts, it is usually used on a production line, so it needs to be shipped within a few hours after sealing, but it must be left overnight to cure. There were some inconveniences.

In order to solve these problems, it is known to separate the conventional composition into a two-component composition into a base resin and a curing agent, but the amount of curing agent relative to the base resin is very small, making it difficult to mix and curing uniformly. It is difficult to balance the base agent and curing agent, and if the ratio changes even slightly, the pot life will be extremely shortened and gelation may occur during mixing. It has the disadvantage that it is a one-component type, which makes it almost impractical.

(Means for Solving the Problems) The present invention provides a curable composition that has a long pot life and quick curability by blending the following three components (Δ) to (C) as essential components. It was successfully obtained.

That is, according to the present invention, (A) the following -ritual, -3+ RIIX) -11... (1) in the formula,
X is a hydrolyzable group, R is a monovalent hydrocarbon group, n is a number of 1 or 0, an organopolysiloxane having the following groups at both ends of the molecular chain; (B) a silanol group in one molecule; There is provided a curable composition comprising at least two organopolysiloxanes and (C) a condensation catalyst as essential components.

Further, according to the present invention, an organopolysiloxane having a silanol group at the end of the molecule and the following ceremony: 1? , S i X□7 ...... (2) In the formula, Mix and heat to the end of the molecular chain using the following ritual: -s r RIIX:1-11 --------
0) Organopolysiloxane (A) into which a group represented by the formula, R, X and n represent the above-mentioned meanings has been introduced.
A curable composition characterized in that an organopolysiloxane (B) having at least two silanol groups in the molecule and a condensation catalyst (C) are blended into the organopolysiloxane (A). A manufacturing method is provided.

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

According to research by the present inventors, in such a curable composition, the rate at which the silanol groups of the organopolysiloxane and the curing agent react, and the rate at which the hydrolyzable groups at the end of the polymer produced by the reaction and the organopolysiloxane It is recognized that the reaction rate of the siloxane with the silanol group differs greatly, which basically causes the disadvantage that the curing reaction does not occur uniformly.

According to the present invention, a terminally reactive diorganopolysiloxane (component (A)) is prepared in advance by reacting a diorganopolysiloxane with a curing agent, and this and a terminally silanol-containing diorganopolysiloxane (component (A)) are prepared in advance. Ingredient (B))
Since these are mixed in the presence of a curing catalyst (component (C)), inconveniences caused by differences in reaction rates are avoided, and curing progresses evenly and quickly to the depths, resulting in long pot life and workability. A composition with excellent properties can be obtained.

(Preferred Embodiment of the Invention) /A Organopolysiloxane used as the essential component (A) has the above-mentioned general formula at both ends of the molecular chain, i.e., -s 1RIIX3-11... −・
It has a group represented by (t).

Here, the group R is a monovalent hydrocarbon group, and specific examples include a methyl group, an ethyl group, a propyl group, a vinyl group, a phenyl group, and a trifluoropropyl group.

Examples of the hydrolyzable group represented by Alkoxy groups such as ethoxy group and propoxy group, isopropenyloxy group, 1-ethyl-
Alkenyloxy groups such as 2-notylvinyloxy group, dimethylamino group, diethylamino group, butylamino group,
Amino groups such as cyclohexylamino groups, aminoxy groups such as dimethylaminoxy groups, diethylaminoxy groups, N-
Methylacetamide group, N-ethylacetamide group, N
- Amide groups such as methylbenzamide groups, etc. can be mentioned.

Such an organopolysiloxane having a reactive group at the molecular end is an organopolysiloxane containing a terminal silanol group corresponding to the organopolysiloxane and the following -Rn
SiX4 Rn S r X a-n ・・・・・・
It can be easily obtained by mixing and heating a silane represented by the formula (2), in which R, X and n represent the meanings 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 restriction on the type of organic group bonded to the silicon atom in this organopolysiloxane, and examples thereof include alkyl groups such as methyl, ethyl, propyl, and butyl groups, and cycloalkyl groups such as cyclopentyl and cyclohexyl groups. groups, alkenyl groups such as vinyl groups and allyl groups, aryl groups such as phenyl groups, tolyl groups, and naphthyl groups, aralkyl groups such as 2-phenylethyl groups, alkoxy groups such as methoxy groups, ethoxy groups, and propoxy groups; Examples include groups in which some or all of the hydrogen atoms of the group are substituted with halogen atoms such as chlorine atoms, amino groups, etc. This organopolysiloxane has a strength of 100 to 1.000.000 cSt at 25°C,
Preferably, the degree of polymerization is such that the diorganopolysiloxane has a viscosity of 1,000 to 50,000 cSt.
If the viscosity is below, it will be difficult to obtain a cured product with excellent physical strength;
．． (loOcst (25°C) or higher), the viscosity of the composition containing it becomes too high, resulting in poor workability during use of the composition.

The organopolysiloxane used as component (B) in the present invention has at least two silanol groups in one molecule.
For example, it includes an organopolysiloxane containing a terminal silanol group, which is a raw material for producing the reactive organopolysiloxane of component (A), but in addition to this, 011 etc. can be used, and A material with a low viscosity of 100 cSt or less can also be used.

Component (B) is 3 parts by weight to 100 parts by weight of component (A)
It is used in an amount of 500 parts by weight, preferably 50 to 150 parts by weight, and if it is less than 3 parts by weight, a sufficient amount of silanol cannot be provided to the reactive groups of component (A), resulting in poor physical properties after curing. Moreover, if it exceeds 500 parts by weight, silanol groups remain unreacted, resulting in extremely poor heat resistance. It is preferable that (A) and (B) be at a ratio of 1:1 to facilitate blending using an automatic mixer.

'C-4. Also, as the curing catalyst for component (C) in this composition, any known catalyst that has been conventionally used in this type of composition may be used, including lead-2 ethyl octoate, lead-2 ethyl octoate, Dibutyltin dioctoate, dibutyltin diacetate, dibutyltin dilaurate, butyltin-2-ethylhexoate 1-1 iron-2-ethylhexoate, cobalt-2-ethylhexoate, manganese-2-ethylhexoate Organic carboxylates such as ester, zinc-2-ethylhexoate, stannous caprylate, tin naphthenate, tin oleate, tin butyrate, titanium naphthenate, zinc naphthenate, cobalt naphthenate, zinc stearate, etc. Metal salts of acids, organic titanate esters such as tetrabutyl titanate, tetra-2-ethylhexyl titanate, triethanolamine titanate, tetra(isopropenyloxy) titanate, organic titanium compounds such as organosiloxy titanium, β-carbonyl titanium , alkoxyaluminum compounds, aminoalkyl group-substituted alkoxysilanes such as 3-aminopropyltriethoxysilane, N-(trimethoxysilylpropyl)ethylenediamine,
Amine compounds and their salts such as hexylamine and dodecylamine phosphate, quaternary ammonium salts such as benzyltriethylammonium acetate, potassium acetate,
Examples include alkali metal lower fatty acid salts such as sodium acetate and lithium oxalate, dialkylhydroxylamines such as dimethylhydroxylamine and diethylhydroxylamine, guanidine compounds such as the formula, and guanidyl group-containing silanes or siloxanes. The use thereof is not limited to one type, but may be used as a mixture of two or more types.

In addition, if the amount of component (C) used is too small, it will take a long time to cure, and if the material is thick, it will be difficult to harden it uniformly to the deep part. If the curing time is too high, the curing time will be extremely short, causing various inconveniences on the work surface, and the resulting cured product will have poor heat resistance or weather resistance. 0.0
The amount may range from 1 to 5 parts by weight, preferably from 0.1 to 3 parts by weight.

In addition to the above-mentioned essential components (A) to (C), various fillers may be added to the present composition.

These include finely powdered silica, silica airgel, precipitated silica, diatomaceous earth, metal oxides such as iron oxide, zinc oxide, and titanium oxide, or those whose surfaces have been treated with silane, calcium carbonate, magnesium carbonate, zinc carbonate, etc. Examples include metal carbonates, asbestos, glass wool, carbon black, finely divided mica, fused silica powder, and synthetic resin powders such as polystyrene, polyvinyl chloride, and polypropylene. ) If the total amount of components is less than 1 part by weight per 100 parts by weight of the components, the cured product obtained from this composition will not exhibit sufficient mechanical strength, and if it is more than 400 parts by weight, the room temperature curable organopolymer will not exhibit sufficient mechanical strength. The viscosity of siloxane increases, which not only worsens workability, but also reduces the rubber strength after curing, making it difficult to obtain the desired rubber elastic body, so it is necessary to keep the amount in the range of 1 to 400 parts by weight. , this preferred range is 5-2
00 parts by weight.

The composition of the present invention thus obtained may further contain thixotropy agents such as polyethylene glycol and derivatives thereof, pigments, dyes, anti-aging agents,
It is optional to add antioxidants, antistatic agents, flame retardants such as antimony oxide and chlorinated paraffin, thermal conductivity improvers such as boron nitride and aluminum oxide, and antifungal agents. Various conventionally known additives such as so-called carbon functional silanes having properties imparting agents, amino groups, epoxy groups, thiol groups, etc., metal salts of carboxylic acids, metal alcoholades, etc. may be mixed. For convenience, this may be diluted with a hydrocarbon solvent such as toluene or petroleum ether, a ketone, an ester, or the like.

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

The curable composition of the present invention can be used for adhesion and fixation of electric/electronic parts, FIPG sealing materials for automobiles, etc., and is particularly suitable for line adhesives that cannot be cured for a long time (on the order of days). Suitable as a sealing material.

It can also be used in applications where the so-called addition type two-component type using a platinum catalyst cannot be applied due to catalyst poisoning.

For example, solder flux (Shirokanemae) for electrical and electronic parts.
Suitable for use in seals and bottings in areas that may come into contact with water, and FIPG sealing materials for automobile engines and transmissions where gear oil, auto transmission oil, etc. may adhere, as well as various base materials. Sealants, caulking agents, coatings, water repellents,
It can be widely used as a mold release treatment agent and as a fiber treatment agent.

(Example) and 5 parts by weight of methyltribucunooxime silane were added,
The mixture was heated at 80° C. for about 3 hours to synthesize a polysiloxane end-capped with methyldibutanoxime silane.

then were uniformly mixed under a N2 stream (mixture a).

Further, 10 parts by weight of R-972 was mixed with 90 parts by weight of the dimethylpolysiloxane used above whose molecular chain ends were blocked with silanol to prepare a mixture (mixture b).

Then, when equal amounts of these mixtures a and b were mixed uniformly, the mixture could be mixed and stirred at 20° C. for 20 minutes, and after 3 hours, the entire mixture was uniformly hardened.

Furthermore, the mixture of equal amounts of a/b was formed into a sheet with a thickness of 2M, and after 3 hours, the physical properties of the rubber were measured based on JIS 4-6301, and the hardness (JIS A) was 25 and the tensile strength was 18 kgf/ cffl, elongation was 420%.

and the aforementioned fumed silica [? -972 A homogeneous mixture of 10 parts by weight was prepared.

Furthermore, Methyltributanoxime silane 5 parts by weight and Dibutyltin dilaurate 0.3 parts by weight This was mixed into the previously prepared mixture.

Even after 6 hours had passed after mixing, the mixture did not harden to the deep part, and only the surface part was hardened.

In addition, when the same process was repeated by reducing the total amount of methyltributanoxime silane and dibutyltin dilaurate from 5.3 parts by weight to 1.8 parts by weight, the mixture gelled in about 5 minutes after mixing. .

X House 712”” Atsushi Takumi as well as to a homogeneous mixture of As a condensation catalyst, was added to prepare a homogeneous mixture aO).

Furthermore, the following average composition e esio (SiMezO)! (Sin) 3S
Trisilanol (component b) having iMe30++ was mixed with the mixture a at the blending ratio shown in Table 1, and the rubber physical properties and shear adhesive strength were evaluated.

Spray iJIM- and 1.01 parts of vinyltrialkoxysilane were mixed and heated and mixed at 150°C for 6 hours.

Next, 80 parts by weight of surface-treated calcium carbonate and 0.2 parts by weight of dibutyltin dioctoate were added to prepare a homogeneous mixture a.6 Furthermore, 10 parts by weight of the methylphenylpolysiloxane used above
80 parts by weight of surface-treated calcium carbonate was added to 0 parts by weight to prepare a homogeneous mixture.

When these mixtures a and b were mixed in equal amounts, the temperature was 20°C.
It was possible to mix for 15 minutes at a temperature of 1.5 hours, and was completely cured after 1.5 hours.

In addition, when the physical properties of the rubber were measured in the same manner as in Example 1, Hardness (JIS 8) 20, Tensile strength 1 6kgf/ C, The elongation was 580%.

Claims (3)

[Claims] (1) (A) The following general formula -SiR_nX_3_-_n In the formula, X is a hydrolyzable group, R is a monovalent hydrocarbon group, and n is a number of 1 or 0. (B) an organopolysiloxane having at least two silanol groups in one molecule; and (C) a condensation catalyst as essential components. (2) Organopolysiloxane 100 of the component (A)
Per part by weight, the organopolysiloxane as component (B) is 3 to 500 parts by weight, and the condensation catalyst as component (C) is 0.
The curable composition according to claim 1, wherein the curable composition contains 01 to 5 parts by weight. (3) An organopolysiloxane having a silanol group at the end of the molecule, and the following general formula: -R_nSiX_4_-_n In the formula, X is a hydrolyzable group, R is a monovalent hydrocarbon group, and n is a number of 1 or 0. , an organopolymer having a group represented by the following general formula, -SiR_nX_3_-_n, where R, Siloxane (A) is prepared, and then an organopolysiloxane (B) having at least two silanol groups in one molecule and a condensation catalyst (C) are blended into the organopolysiloxane (A). Method for producing curable composition.