JPS62252456A - Room temperature-curable organopolysiloxane composition - Google Patents

Abstract

PURPOSE:To contemplate improvements in surface film forming rate and storage stability under sealed conditions, by blending a specified organopolysiloxane with silica having a treated surface, an alkoxysilane and a titanium chelate catalyst. CONSTITUTION:A room temperature-curable organopolysiloxane compsn. is obtd. by blending the following four components A-D. Namely, 100pts.wt. organopolysiloxane (A) having at least two trialkoxysilyl groups per molecule and a viscosity of 20-1,000,000cP at 25 deg.C, 1-50pts.wt. silica (B) having a treated surface, 0.5-15pts.wt. alkoxysilane (C) of the formula Ra<1>Si(OR<2>)4-a (wherein R<1> is a monovalent hydrocarbon group; R<2> is a monovalent hydrocarbon group or an alkoxy-substd. hydrocarbon group; and a is 0 or 1) or partial hydrolyzate condensate thereof and 0.1-10pts.wt. titanium chelate catalyst (D).

Description

Detailed Description of the Invention [Industrial Application Field 1] The present invention relates to a room-temperature curable organopolysiloxane composition, which has excellent storage stability especially under sealed conditions and which forms a surface film extremely quickly. The present invention relates to novel siloxane compositions that are room temperature curable.

[Prior Art and Problems to be Solved 1 Various types of room-temperature-curable or-novolisiloxane compositions that cure into an elastomer at room temperature upon contact with moisture in the air have been known. In particular, the type that hardens by emitting alcohol has the characteristics of no unpleasant odor and does not corrode metals, and is therefore preferred for sealing, adhesion, and coating of electrical and electronic equipment. There is. A representative example of this type is Japanese Patent Publication No. 39-27,643, which discloses a composition comprising a hydroxyl end-capped organopolysiloxane, a flukoxysilane, and an organotitanium compound. Further, JP-A No. 55-43,119 discloses a composition comprising an alkoxysilyl end-blocked polysiloxane, an alkoxydisilane, and an alkoxytitanium. However, these compositions have problems in storage stability under sealed conditions and also have the drawbacks of slow surface film formation.

The present invention solves the above-mentioned drawbacks, provides an elastomer-like cured product that has excellent storage stability under sealed conditions, shows little change in physical properties even after storage under harsh conditions, and forms a surface film extremely quickly. It is an object of the present invention to provide a novel siloxane composition that has a room temperature curing speed.

[Means for solving the problem and its effects 1 This purpose is to use an organopolysiloxane having a trialkoxysilyl group as the base component of the composition, and to add surface-treated silica as a filler and titanium as a catalyst. This is accomplished through the use of chelating compounds.

That is, the present invention provides: (8) a viscosity at 25°C of 20 to 1,000,000;
(B) 1 to 50 parts by weight of surface-treated silica (C) General formula % Formula %) , R1 is a monovalent hydrocarbon group, R2 is a monovalent hydrocarbon group or a hydrocarbon group substituted with an alkoxy group, a is 0 or 1) or a partially hydrolyzed condensate thereof 0.5 ~15 parts by weight (D>Relating to a room temperature curable organopolysiloxane composition comprising 0.1 to 10 parts by weight of a titanium chelate catalyst.

Component (A) used in the present invention is a base material of the present composition, and in order to obtain improved storage stability and an extremely fast surface film formation rate, it is necessary to include trialkoxysilyl groups in each molecule. It is necessary that the organopolysiloxane has at least two . Preferred component (8) is the general formula (1) (wherein R2 is a monovalent hydrocarbon group or an alkoxy-substituted hydrocarbon group, and R3 is a monovalent hydrocarbon group, a halogenated hydrocarbon group, or a cyanoalkyl group). The selected group, Y is an oxygen atom or a divalent hydrocarbon group, and ■ represents a positive number such that the viscosity at 25°C is 20 to 1,000°000 centipoise. The straight-chain organ having this is novolisiloxane. However, the present invention is not limited thereto, and organopolysiloxanes having a linear basic structure and branched, cyclic or network portions can also be used.

In the organopolysiloxane represented by general formula (1), examples of R3 include methyl, ethyl, propyl,
Examples include alkyl groups such as butyl, hexyl, octyl, decyl, and octadecyl, cycloalkyl groups such as cyclopentyl and cyclohexyl, fulkenyl groups such as vinyl and allyl, and aralkyl groups such as pencil, phenylethyl, and phenylpropyl. Examples of carbonized hydrocarbon groups include chloromethyl, trifluoromethyl, chloropropyl, 3,3.3-)lifluoropropyl, chlorophenyl, dibromophenyl, tetrachlorophenyl, and difluorophenyl groups, and examples of cyanoalkyl groups include β- Cyanoechinosu γ-cyanoprovir, β-
Examples include a pyl group.

Examples of R2 include alkyl groups such as methyl, ethyl, propyl, butyl, hexyl, and octyl, and flufoxy-substituted alkyl groups such as methoxyethyl, ethoxyethyl, methoxypropyl, and methoxybutyl. R
It is preferred that 2 and R3 each have 1 to 3 carbon atoms, and more preferably a methyl group. Y is an oxygen atom or a divalent hydrocarbon group, and the divalent hydrocarbon group is CII.

-CH2C1(2-1-CH2C)12Cl12-1-
Examples include alkylene groups such as Cl12CH-.

000 centipoise, because smaller than 20 centipoise cannot give the cured elastomer good physical properties, especially flexibility and high elongation, and larger than 1°ooo, ooo centipoise This is because the viscosity of the composition increases and workability during construction becomes significantly worse. Therefore, more preferably 100
~ soo, ooo centipoise range.

In order to obtain a composition with improved storage stability and extremely fast surface film formation rate, which is the object of the present invention, (
^) The molecular chain terminals of the components must be trialfoxysilylated, and if silanol-terminated or-novolisiloxane, which is commonly used in room-temperature-curable organopolysiloxane compositions, is used, sufficient Storage stability cannot be achieved. In addition, when an organo-novolisiloxane terminated with a monoalkoxydiorganosilyl group or a diflukoximo7organosilyl group is used, an extremely fast surface film formation rate cannot be obtained.

Component (A), a trialfoxysilyl group-terminated organopolysiloxane, can be produced by various conventionally known methods. For example, when Y in general formula (1) is an oxygen atom, it is produced by condensing the corresponding silanol-terminated ornovolisiloxane and tetraalfoxydisilane in the absence or presence of a catalyst. Catalysts used include amines, carboxylic acids, and metal carboxylates such as zinc, tin, and iron. When the condensation reaction is carried out in the absence of a catalyst, it is preferable to heat the reaction mixture to the reflux temperature of the tetraalkoxysilane, and when a catalyst is used, the reaction can be carried out at a temperature ranging from room temperature to the reflux temperature of the tetraalkoxysilane.

The molar ratio of tetraalfukidisilane/5iOH in the condensation reaction should be at least 1, preferably in the range from 5 to 15. Although not essentially necessary, it is preferable to remove the by-product alcohol.

Another synthetic reaction method for producing trialkoxysilyl-terminated or-novolisiloxanes of (^) includes the reaction of the corresponding silanol-terminated or-novolisiloxanes with the formula Cl5
A method of reacting a chlorosilane represented by i(OR2)- (wherein R2 is the same as above) in the presence of a hydrogen halide acceptor such as pyridine, α-bifrin or other tertiary amine, or , a method in which an organopolysiloxane having a halogen bonded to a silicon atom at the end of the molecular chain and a monohydric alcohol represented by 2R20H (R2 is the same as above) are subjected to a condensation reaction in the presence of the above-mentioned hydrogen halide acceptor, etc. There is.

Moreover, when Y in general formula (1) is a fullkylene group,
A corresponding alkenyl group-terminated or-terminated novolisiloxane is subjected to an addition reaction with a triflukoxysilane represented by the formula H-Si(OR2)3 (in the formula, R2 is the same as above) in the presence of a pt catalyst, or a corresponding Si ■Terminal organopolysiloxane and formula R'5i(OR2)s (in the formula, R
4 is an alkenyl group, and R2 is the same as above. ) Component (A) can be produced by an addition reaction with (A) or the like.

The surface-treated silica, which is component (B) used in the present invention, provides the composition with improved storage stability and a good surface film formation rate, as well as imparts appropriate viscosity and rubber physical properties. It is an essential component of

Examples of surface treatment agents for silica include organosilazanes, organocyclosiloxanes, organochlorosilanes,
Preferred are organosilicon compounds conventionally known as hydrophobizing agents for silica, such as organoalphoxydisilanes and low-molecular-weight linear siloxanes. In addition, the surface film formation rate,
In order to adjust the flow characteristics, etc., two or more types of surface treatment agents may be used in combination. When untreated silica is used, a composition with good storage stability and surface film formation rate, which is the object of the present invention, cannot be obtained. As the silica, dry silica is preferable from the viewpoint of storage stability of the present composition, imparting appropriate viscosity, imparting rubber physical properties, and water content.

For (B), previously treated silica may be used, or silica may be surface-treated while being mixed with component (A). In order to significantly improve the storage stability of the present composition, it is important to ensure that substantially no surface treatment agent, treatment by-products, catalysts, etc. remain in the composition.

The amount of component (B) added is 1 to 50 parts by weight, preferably 3 to 30 parts by weight. This is because if the amount is too large, the viscosity of the composition will increase too much, resulting in poor workability during mixing and construction, while if it is too small, the physical properties of the rubber after curing will deteriorate.

Component (C) used in the present invention acts as a crosslinking agent for the present composition, and is a component for curing the composition to become a rubber elastic body. This has the general formula R'aSi(OR2)4-
a (wherein R1 is a monovalent hydrocarbon group, R2 is a monovalent hydrocarbon group or an alkoxy group-substituted hydrocarbon group, a is 0 or 1
It is. Examples of the -valent hydrocarbon group and the alkoxy-substituted hydrocarbon group are the same as those listed in the explanation of the component (^). ) or a partially hydrolyzed condensate thereof is used.

Specific examples of component (C) include tetramethoxysilane,
Tetramethoxysilane, methyl cellosolve orthosilicate, and other tetrafunctional alphoxysilanes; methyltriethoxysilane, methyltriethoxysilane, ethyltrino)oxysilane, vinyltrimethoxysilane, phenyltrimethoxysilane, methyltrimethoxyethoxysilane, and other trifunctional silanes. Examples include functional alphoxydisilanes and partially hydrolyzed condensates thereof. These may be used alone or in combination of two or more. Furthermore, in order to impart low modulus to the rubber elastic body after curing, difunctional alkoxysilanes such as diphenyldimethoxysilane and dimethyldimethoxysilane may be additionally added.

The amount of component (C) added is in the range of 0.5 to 15 parts by weight, preferably 1 to 1 parts by weight, per 100 parts by weight of component (A).
It is in the range of 0 parts by weight. If the amount added is too small, the composition may not harden sufficiently or may thicken or thicken during storage when packaged in one package.
This is because gelation tends to occur, and if the amount is too large, curing may be delayed, resulting in an economical disadvantage.

(D) used in the present invention is a catalyst for curing the present composition, and must be a titanium cure-Y catalyst in order to obtain improved storage stability of the present composition. be. The titanium chelate-Y catalyst is at least one selected from the general formula (X represents a group selected from a monovalent hydrocarbon group, an alkoxy group, and an ami7 group, and R1, R2, and R1 are the same as above). Preferably, it is a titanium chelate-Y catalyst.

Specific examples of component (D) include diisopropoxy bis(ethyl acetoacetate) titanium, diisopropoxy bis(methyl acetoacetate) titanium, diisopropoxy bis(acetyl 7
Setone) titanium, dibutoxybis(ethyl acetoacetate)
Examples include titanium, dimethoxybis(methyl 7cetoacetate) titanium, and the like.

(1)) The amount of component (8) added is in the range of 0.1 to 10 parts by weight per 100 parts by weight, preferably 0.3 parts by weight.
~6 parts by weight. This is because if the amount added is too small, the curing of the composition will be slow, and if it is too large, the storage stability will be poor.

In addition to the components (8) to (1) described above, the composition of the present invention further improves the flow characteristics before curing and provides the mechanical properties necessary for the rubber-like elastomer after curing, if necessary. For this purpose, finely powdered inorganic fillers can also be added.

Inorganic fillers include fine quartz powder, calcium carbonate, atomized titanium dioxide, diatomaceous earth, aluminum hydroxide,
Examples include fine particulate alumina, magnesia, zinc oxide, zinc carbonate, and those surface-treated with silanes, silazane, low polymerization degree siloxanes, organic compounds, etc.

Furthermore, the composition of the present invention contains an organic solvent, a fungicide, an it
Flame retardants, heat resistant agents, plasticizers, titanium properties imparters, adhesion promoters,
Curing accelerators, pigments, etc. can be added.

2*n 11111IXill Is & 14
/ Masa ~ (IN+jy4b) tt, +
7. It can be obtained by mixing various additives depending on the condition while keeping moisture out. The resulting composition can be stored as it is in a closed container and used as a so-called one-pack room-temperature-curing organopolysiloxane M product, which hardens into a rubber-like elastic body when exposed to moisture in the air during use. can.

[Example 1] Hereinafter, the present invention will be explained with reference to Examples. In Examples, Comparative Examples, and Reference Examples, all parts mean parts by weight, and the viscosity is the value at 25°C.

Reference Example 1 (Production method of Polymer A) 100 parts of a,ω-dihydroxy-dimethylpolysiloxane having a viscosity of 15,000 centivoids and 10 parts of tetramethoxysilane were charged into a reactor equipped with a reflux condenser and stirred. While heating at 140° C. for 8 hours. Thereafter, the mixture was heated to 120° C. under a reduced pressure of 20 o+mHg, and by-produced methanol and excess tetramethoxysilane were distilled off.

The resulting polymer had a viscosity of 17,600 centibois and was mixed with tetrabutyl titanate at 10 cm in a dry N2 atmosphere.
When mixed at a ratio of 0:1, it was stable without thickening,
- When mixed in the air in the blade chamber, the viscosity rapidly increased and hardened. From this, the OH group at the polymer end is -OS i (QC)
It can be confirmed that the compound was substituted with l3)- group. This polymer will be referred to as Polymer A.

Reference Example 2 (Production method for Polymer B) 100 parts of α,ω-dimethylvinyldimethylpolysiloxane with a viscosity of 10,000 centivoids, 7 parts of trimethoxysilane, and 1 part of a 1% isopropanol solution of chloroplatinic acid as a catalyst. was added and mixed for 9 hours at room temperature under a stream of N2.

Thereafter, the mixture was heated to 50° C. under a reduced pressure of 10 mmHH to distill off excess trimethoxysilane.

The resulting polymer had a viscosity of 10,800 centiboise and was mixed with tetrabutyl titanate at 10,800 cm in a dry N2 atmosphere.
When mixed at a ratio of 0:1, it was stable without thickening,
On the other hand, when mixed in air, the viscosity rapidly increased and hardened. This confirms that trimethoxysilane was added to the vinyl group at the end of the polymer. This polymer will be referred to as Polymer B.

Reference Example 3 (Production method of Polymer C) 100 parts of α,ω-dihydroxydimethylpolysiloxane having a viscosity of 12,000 centivoids, 10 parts of tetrameroxysilane and 0.02 part of acetic acid as a catalyst,
The mixture was charged into a reactor equipped with a reflux condenser and heated at 70° C. for 6 hours while stirring. Thereafter, the mixture was heated to 130° C. under a reduced pressure of 10+amHg, and by-produced methanol, excess tetramethoxysilane, and acetic acid were distilled off.

The resulting polymer had a viscosity of 14,500 centiboise and was mixed with tetrabutyl titanate at 10 cm in a dry N2 atmosphere.
When mixed at a ratio of 0:1, the viscosity did not increase and the mixture was stable.On the other hand, when mixed in air, the viscosity rapidly increased and hardened.

From this, the 0■ group at the end of the polymer is 105i (OCL).
It can be confirmed that it was substituted with an s group. This polymer will be referred to as Polymer C.

Reference Example 4 (Production method of surface-treated silica A) 100 parts by weight of dry silica having a specific surface area of 200 ma+''/g by the BET method and a water content of 1% by weight and 10 parts by weight of dimethyldimethoxysilane were mixed at room temperature. After uniformly mixing for 2 hours, 15 parts by weight of hexamethyldisilazane was added and further uniformly mixed for 1 hour at room temperature.Then, this mixture was heated to 150°C and mixed for 3 hours at the same temperature. Surface-treated silica A was obtained.

Example 1 100 parts of Polymer A and 12 parts of dry silica having a specific surface area of 110 2/g by the BET method and surface-treated with hexamethyldisilazane were mixed at room temperature for 30 minutes, and further heated at 180°C.
The mixture was mixed under a reduced pressure of 401 inf.Hg while heating to a uniform temperature. 5 parts of methyltrimethoxysilane and 1.5 parts of diisopropoxy-bis(ethyl acetoacetate) titanium were mixed into this mixture under moisture protection until homogeneous.

This was placed in an aluminum tube and sealed.

A sheet with a thickness of 3III11 was prepared from the composition obtained above, cured at room temperature for 7 days, and measured for rubber physical properties (hardness, tensile strength, elongation) according to JIS-6301.

The results are shown in Table 1. Next, this composition sealed in an aluminum tube was stored in an oven at 50° C. for 8 weeks, and the physical properties of the rubber were measured in the same manner as above. Together with this result, the first
Shown in the table.

Comparative Example 1 A composition was prepared in the same manner as in Example 1, except that 12 parts of untreated dry silica was used instead of the hexamethyldisilazane-treated dry silica. Using this composition, the same test as in Example 1 was conducted and the results are shown in Table 1.

Comparative Example 2 In Example 1, the viscosity was 15.0 instead of Polymer A.
An IT product was prepared in the same manner as in Example 1, except that 100 parts of α,ω-dihydroxy-dimethylpolysiloxane (precursor of Polymer A) of 0.00 centipoise was used. Table 1 shows the results of a test similar to Example 1 using this composition.

Comparative Example 3 In Example 1, teF-butyl titanate 1 was used instead of diisopropoxy-bis(ethyl 7cetoacetate) titanium.
．． A composition was prepared in the same manner as in Example 1 except that 5 parts were used. Table 1 shows the results of a test similar to Example 1 using this composition.

Table 1 Example 2 100 parts of polymer A and a specific surface area of 200 parts by BET method
m2/g and 20 parts of dry silica surface-treated with dimethyldichlorosilane were mixed at room temperature for 30 minutes, and further mixed under reduced pressure of 40 mm/g until uniform. 6 parts of methyltriethoxysilane and 1.5 parts of diisopropoxy-bis(methyl acetoacetate) titanium were mixed into this mixture under moisture protection until homogeneous. This was placed in an aluminum tube and sealed. The obtained composition was subjected to the same test as in Example 1, and the results are shown in Table 2.

Example 3 A composition was prepared in the same manner as in Example 2, except that 20 parts of surface-treated silica A was used instead of dimethyldichlorosilane-treated silica. Table 2 shows the results of a test similar to Example 2 using this composition.

Comparative Example 4 A composition was prepared in the same manner as in Example 2, except that 1.5 parts of tetraisopropoxy titanate was used instead of diisopropoxy-bis(methyl acetoacetate) titanium. Example 2 using this composition
Table 2 shows the results of a test similar to the above.

Comparative Example 5 Composed in the same manner as in Example 2, except that in Example 2, 12 parts of untreated dry silica was used instead of dimethyldichlorosilane-treated silica (20 parts would make mixing difficult). I prepared something. Using this composition, the same test as in Example 3 was conducted and the results are shown in Table 2.

Table 2 Example 4 100 parts of polymer C and a specific surface area of 200 parts according to the BET method
m2/g and 15 parts of dry silica surface-treated with hexamethyldisilazane were mixed at room temperature for 30 minutes and then heated to 180"C under reduced pressure of 40 mm and 11 g until homogeneous. A composition was prepared by mixing 4 parts of vinyltrimethoxysilane and 1.5 parts of dibutoxybis(methyl acetoacetate) titanium with a homogenizer under moisture exclusion.This composition was used to prepare the Examples. Table 13 shows the results of a test similar to 1.

Example 5 A composition was prepared in the same manner as in Example 4, except that 15 parts of surface-treated silica A was used instead of the hexamethyldisilazane-treated silica. A test similar to that of Example 4 was conducted using this composition, and the results were tJ!
, shown in Table 3.

Comparative Example 6 In Example 4, a composition was prepared and tested in the same manner as in Example 4, except that 1.5 parts of tetrabutyl titanate was used instead of methyl titanium acetoacetate. The results are shown in Table 3.

Comparative Example 7 Composition was made in the same manner as in Example 4, except that 12 parts of untreated dry silica was used instead of the hexamethyldisilazane-treated silica (15 parts would make mixing difficult). The products were prepared and tested, and the results are shown in Table 3.

Table 3 Example 6 8100 parts of polymer, specific surface area 110g by BET method
+2/g and 15 parts of dry silica surface-treated with hexamethyldisilazane are uniformly mixed, and 5 parts of methyltrimethoxysilane and 2 parts of diisopropoxy-bis(ethyl acetoacetate) titanium are added to the mixture with moisture. The composition was prepared by mixing under shielding until homogeneous. Table 4 shows the results of a test similar to that of Example 1 using this composition.

Example 7 In Example 6, instead of hexamethyldisilazane,
A composition was prepared and tested in the same manner as in Example 6, except that 15 parts of surface-treated silica A was used. The results are shown in Table 4.

Comparative Example 8 A composition was prepared in the same manner as in Example 6, except that 12 parts of untreated dry silica was used instead of the hexamethyldisilazane-treated silica (15 parts would make mixing difficult). were prepared and tested, and the results are shown in Table 4.

Table 4 [Effects of the Invention 1 The IT product of the present invention has an extremely fast surface film formation rate compared to conventional one-pack Wi, Flucor type room temperature curable organopolysiloxane compositions, and also has sealing conditions. Because of its excellent storage stability under harsh conditions, it has the characteristic of providing an elastomer-like cured product with little change in physical properties even after storage under harsh conditions. Therefore, it is easy to handle, such as not having to deal with temperature changes during storage indoors and outdoors, and since the by-product is alcohol, it has almost no odor and does not attack metals or plastics. ,
As a building sealant, as a sealant for electrical and electronic parts,
It is useful as an adhesive or moisture-proof coating agent, and as a coating agent or adhesive for textile products, glass products, metal products, plastic products, etc.

Claims (1)

[Claims] 1 (A) Viscosity at 25°C is 20 to 1,000.0
00 centipoise, and the trialkoxysilyl group is 1
100 parts by weight of organopolysiloxane having at least two molecules in the molecule (B) 1 to 50 parts by weight of surface-treated silica (C) General formula R^1aSi(OR^2)_4_-_a (wherein R^1 is a monovalent hydrocarbon group, R^2 is a monovalent hydrocarbon group or an alkoxy group-substituted hydrocarbon group, a is 0 or 1) or a partially hydrolyzed condensate thereof 0.5 to 15 weight Part (D) A room temperature curable organopolysiloxane composition comprising 0.1 to 10 parts by weight of a titanium chelate catalyst.