JP2622216B2 - Method for producing room temperature curable organopolysiloxane composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

FIELD OF THE INVENTION The present invention relates to a process for producing a room-temperature-curable organopolysiloxane composition, and more particularly to a room-temperature-curable organopolysiloxane composition having improved transparency, storage stability, slumping property and movement crack resistance. It relates to a manufacturing method.

[0002]

2. Description of the Related Art Conventionally, various room-temperature-curable organopolysiloxane compositions which are easily cured by moisture to form a rubber elastic body have been known, but these are known as adhesives, coating materials, and the like. It is widely used as an electrical insulating sealing material and a building sealing material. Then
As an industrial or architectural sealing material, it is important that no slump is present when uncured.
This composition is usually added with an anti-slump agent.However, in recent years, high-rise buildings tend to increase in this building sealant material, and the amount of displacement applied to joints is large. Are required to have a performance (movement crack resistance) that can favorably follow a movement.

[0003]

As the anti-slump agent, phenyl group-containing polysiloxanes (see U.S. Pat. No. 4,100,129), polyoxyalkylene compounds (see JP-A-56-853), Polyoxyalkylene compounds having a hydrolyzable organosilicon compound (see Japanese Patent Application Laid-Open No. 62-135560) are known. These compounds are used in combination with an organopolysiloxane as a base polymer of the composition. Poor compatibility, there is a problem of significantly lowering the transparency of the composition, and fine powder silica as a filler must be surface-treated with an organosilicon compound such as dimethyldichlorosilane,
An unprocessed product having a low cost has a disadvantage that the effect of preventing slump is extremely small and is not practical.

[0004] Therefore, a method of obtaining a composition without slump without adding a slump inhibitor to this composition has also been studied. For this purpose, an organopolysiloxane having a hydroxyl group and a crosslinking agent are mixed in advance, and then finely divided. A method of adding powdered silica or the like has also been proposed (see Japanese Patent Application Laid-Open No. 2-41361). However, this method has a short tack-free time and thus has poor workability, and also has a problem with movement crack resistance. There is a disadvantage that there is.

[0005]

The present invention SUMMARY OF] is a method for producing a room temperature vulcanizable organopolysiloxane composition which solves the above disadvantage, which is (A) the general formula HO- (SiR ¹ ₂
O) _n -H (wherein the R ¹ are identical or unsubstituted or substituted monovalent hydrocarbon group of heterogeneous, n represents 100 parts by weight of an organopolysiloxane represented by a natural number), (B) the general formula R ² _4-a Si (ON = CR ³ _2)
a or

Embedded image (Where R ² and R ³ are the same or different unsubstituted or substituted monovalent hydrocarbon groups, R ⁴ is an unsubstituted or substituted divalent hydrocarbon group, and a is 2, 3 or 4) The organic silicon compound having a molar ratio of 3 to 20 equivalents relative to the hydroxyl group of the organopolysiloxane of the component (A), and (C) a specific surface area of 70 m ²
In preparing a room-temperature-curable organopolysiloxane comprising 1 to 50 parts by weight of a silica fine powder having an adsorbed moisture of 0.5% or less and (D) a condensation catalyst of 0.5% or less, the organopolysiloxane of the component (A) is used. For the hydroxyl group of the polysiloxane,
The following formula (A _oH + kC _oH ) × B _Mw (g) (1) where A _oH : the amount (mol) of the hydroxyl group of the organopolysiloxane of the component (A), B _MW : (B ) Molecular weight of component iminoxysilane, _CoH : total amount of OH groups (mol) of silica of component (C), k: iminoxysilane as component (B) in an amount calculated from 0 <k <1.5
And the component (A) are mixed in advance, and then the mixture is mixed with the component (C).
A predetermined amount of silica as a component is mixed, and then the remaining iminoxysilane of component (B) and, if necessary, a predetermined amount of a condensation catalyst as component (D) are mixed.

That is, the present inventors have developed transparency, storability,
As a result of various studies to develop a method for producing a room temperature-curable organopolysiloxane composition having improved movement crack resistance, the components (A), (B), and (C) described above and, if necessary, are blended. In preparing the room-temperature-curable organopolysiloxane composition comprising the component (D), the component (A) was calculated from the above formula (1) with respect to the terminal hydroxyl group of the organopolysiloxane. The iminoxysilane as the component (B) is preliminarily mixed, and a predetermined amount of the silica fine particles as the component (C) whose water adsorbed thereon has been cut to 0.5% or less, and then the remaining component (B) is mixed. When a composition is produced by mixing a predetermined amount of the iminoxysilane and, if necessary, the condensation catalyst as the component (D),
Since this composition has a long tack-free time, it has good workability, which has a remarkably improved movement crack resistance, and furthermore, it has no slump even without using a slump inhibitor. The present invention was completed by studying these components. This will be described in more detail below.

[0007]

The present invention relates to a method for producing a room temperature-curable organopolysiloxane composition, which is described above.
In the method for producing a room-temperature-curable organopolysiloxane composition comprising the components (A), (B) and (C) and the component (D) which is optionally added, (A) After adding the iminoxysilane as the component (B) in a specific amount range, first add silica fine particles as the component (C), and finally add the remaining iminoxysilane as the component (B) and, if necessary, a condensation catalyst. The gist is to do.

[0008] The organopolysiloxane as the composition constituting component (A) of the present invention is intended to be a base polymer of the composition of the present invention, the general formula HO- this thing (SiR ¹ ₂ O ) _n -H wherein R ¹ is methyl, ethyl, propyl,
Butyl group, hexyl group, alkyl group such as octyl group,
Alkenyl group such as vinyl group and allyl group, phenyl group,
Aryl groups such as tolyl groups and cyclohexyl groups, aralkyl groups such as benzyl group and phenylethyl group, or some or all of the hydrogen atoms bonded to carbon atoms of these groups are halogen atoms, cyano groups, etc. Selected from chloromethyl group, trifluoropropyl group, cyanoethyl group and the like, the same or different unsubstituted or substituted, usually 1 to 10 carbon atoms, preferably 1 to 8 carbon atoms, monovalent hydrocarbon group, n is 50-2, depending on viscosity and workability.
000 is a preferable natural number, and examples thereof include the following. _{HO- [Si (CH 3) 2} O] n -H, HO- [Si (C 6 H 5) 2 O] n - [Si (CH 3) 2 O] m -H, HO- [Si (CH 2 CH ₂ CF ₃ ) ₂ O] _n -H, (m is an integer of 0 or more)

Further, although the composition constituting (B) organosilicon compound as the component of the present invention serves as a crosslinking agent in the compositions of the present invention, this compound has the general formula R ² _{4-a ^{Si (ON = CR 3 2)}} a or

Embedded image Wherein R ² and R ³ are the same or different unsubstituted or substituted monovalent hydrocarbon groups as defined above for R ^1, and R ₄ is an ethylene group, a propylene group, a tetramethylene group, Alkylene groups such as methylene group, pentamethylene group, hexamethylene group, or part or all of the hydrogen atoms bonded to carbon atoms of these groups are halogen atoms,
An unsubstituted or substituted divalent hydrocarbon group selected from a tetrafluoroethylene group substituted with a cyano group or the like, a
Is 2, 3 or 4, and examples thereof include the following. Si [ON = C (CH ₃ ) (C ₂ H ₅ )] ₄ , CH ₃ Si [ON = C (CH ₃ ) (C ₂ H ₅ )] ₃ , CH ₂ = CHSi [ON = C (C ₂ H _{5) 2] 3, (C} 6 H 5) 2 Si [ON = C (CH 2 CH 2 CF 3)] 2, ClCH 2 Si [ON = C (CH 3) 2] 3,

Embedded image

If the amount of the component (B) is too small, the composition will not be sufficiently cured, and if it is too large, the physical properties of a cured product made from the composition will be adversely affected.
The molar ratio may be in the range of 3 to 20 equivalents with respect to the hydroxyl groups in the organopolysiloxane as the component (A), and the composition according to the present invention has the effect of preventing slumping and resistance to movement cracking. It needs to be added in two parts to give.

The above component (B) should be added at least in an amount sufficient to block the hydroxy groups of the organopolysiloxane as component (A) (k> 0). The amount of iminoxylan of component (B) remaining without being consumed by the blocking of the hydroxy group in component (A) becomes less than the total amount of OH groups in the silica of component (C) when the silica of component (C) is added. It is necessary to make it 10 times or less (k < 1.5), but this (B)
If the preceding addition amount of the component is too small, the thixotropy of the composition becomes low and slump occurs, and if it is too large, the thixotropy becomes too strong and causes movement cracking, so this is calculated from the following formula (1). Is required. (A _oH + kC _oH ) × B _Mw (g) ・ ・ ・ ・ (1) where A _OH : hydroxyl group amount (mol) of organopolysiloxane of component (A) B _MW : iminoxysilane of component (B) The molecular weight of C _OH : The total amount of OH groups (mol) of the silica of the component (C) k: 0 <k <1.5 The remainder of the component (B) is added as necessary after the addition of the following component (C). It may be added to this together with the component (D) to be blended.

Next, the silica fine particles as the component (C) constituting the composition of the present invention are used as a reinforcing material for imparting mechanical strength to a rubber elastic body obtained by curing the composition. This has a specific surface area of 70 m ² / g or more. However, since the preservation of the composition is impaired if the amount of adsorbed water is large, it is necessary to suppress the adsorbed water to 0.5% or less. Examples thereof include silica, wet silica, calcined silica, and those obtained by subjecting their surfaces to hydrophobic treatment with organochlorosilanes, polyorganosiloxanes, and organosilazane.

If the amount of the component (C) is too small, the mechanical strength of the cured product of the composition becomes weak, and if it is too large, the fluidity of the composition in a compound state becomes extremely poor, and as a sealing agent. Since it becomes difficult to use, the amount may be 1 to 50 parts by weight, preferably 5 to 40 parts by weight, based on 100 parts by weight of the component (A), but the amount of use is not limited to one type. It may be used as a mixture of two or more.

The condensation catalyst as an optional component (D) constituting the composition of the present invention is for accelerating the curing of the composition. Known ones used in the composition can be used, including dibutyl tin dimethoxide, dibutyl tin diacetate, dibutyl tin dioctoate, dibutyl tin dilaurate, dibutyl tin dimethoxide, dibutyl tin diacetate, and the like. Organic tin compounds,
Tetrapropyl titanate, tetrabutyl titanate,
Organic titanium compounds such as tetra-2-ethylhexyl titanate and dimethoxytitanium diacetylacetonate;
Examples include amine compounds such as hexylamine, 3-aminopropyltrimethoxysilane, and tetramethylguanidylpropyltrimethoxysilane, and salts thereof.

It is not always necessary to use the component (D), but if too much is added, poor curing will occur, and sufficient performance as a seal material will not be obtained.
This may be 0 to 10 parts by weight based on 100 parts by weight of the component (A), but the use is not limited to one kind.
It may be used as a mixture of two or more.

The composition of the present invention has the above-mentioned (A),
It can be obtained by uniformly mixing predetermined amounts of (B), (C), and (D). This mixing is first calculated for the component (A) by the above formula (1) as described above. After adding the amount of the component (B), the component (C) is added,
Then, it is necessary to add and mix the component (D) and the remaining component (B), which are blended as required. However, this composition, if necessary, various fillers and dyes,
It is optional to add a pigment, an adhesion imparting agent, a rust inhibitor, a fungicide, a heat resistance improver, a flame retardant, a water repellent, and the like.

[0017]

EXAMPLES Examples of the present invention and comparative examples will now be described.
Parts in Examples are parts by weight, and viscosities are values measured at 25 ° C.

Example 1, Comparative Example 1 1,000 g of α, β-dihydroxydimethylpolysiloxane (hereinafter abbreviated as oil A) having a viscosity of 20,000 cS and 0.004 mol of hydroxyl groups per 100 g, and methyltris (methylethylketokim) Silane (hereinafter abbreviated as MMKS) 15g and 10mmHg with a universal mixer with moisture shut off
After mixing for 15 minutes while reducing the pressure, the specific surface area
150 g of dry silica fine particles (hereinafter abbreviated as silica A) whose surface was treated with dimethyldichlorosilane at 150 m ² / g and the total amount of OH groups was 0.0003 mol / g were added and mixed under reduced pressure.

Then, 48 g of MMKS, 1.0 g of dibutyltin dioctoate (hereinafter abbreviated as tin A) and 10 g of aminopropyltrimethoxysilane (hereinafter abbreviated as APMS) were added thereto and mixed under reduced pressure to obtain composition 1. Make and add 6g of MMKS at the beginning for comparison
The composition was prepared in the same manner as above except that the second addition amount was 54 g.

Next, the compositions 1 and 2 were subjected to JIS-
After performing a slump test and a movement crack test according to A-5758, these were formed into a sheet having a thickness of 2 mm, and cured at 20 ° C. and 55% RH for 7 days. The cured product was subjected to JIS-K-6301. The physical properties of the rubber were measured according to the standard, and a part of the composition was acceleratedly degraded in a dryer at 70 ° C. for 7 days in a sealed state. However, the results as shown in Table 1 below were obtained. The transparency of the cured product having a thickness of 2 mm was measured with a self-spectrophotometer at 400 nm.
The results were as shown in Table 1.

Example 2 and Comparative Example 2 1,000 g of oil A and 24 g of vinyltris (methylethylketokim) silane (hereinafter abbreviated as VMKS) were mixed for 15 minutes while reducing the pressure to 10 mmHg with a universal mixer in which moisture was shut off. After that, the surface was treated with hexamethyldidioxane, the specific surface area was 150 m ² / g, and the total OH group content was 0.
[0005] 100 g of dry silica fine particles (hereinafter abbreviated as "silica B") of 100 mol / g are added and mixed under reduced pressure, and then 48 g of VMKS and 1.0 g of tin A are added thereto, and similarly mixed under reduced pressure. Composition 3 was made.

For comparison, composition 4 was treated in the same manner as above except that VMKS was initially added in the total amount (72 g).
These compositions 3 and 4 were examined for slump properties, movement crack resistance, rubber properties, storage properties and transparency in the same manner as in Example 1, and the results were as shown in Table 1 below. The result was obtained.

Example 3 and Comparative Example 3 1,000 g of oil A and 36 g of MMKS were mixed for 15 minutes while reducing the pressure to 10 mmHg with a universal mixer in which moisture was cut off, and the specific surface area of the untreated surface was 200 m ^2. 120 g of dry silica particles (hereinafter abbreviated as silica C) having a total OH group content of 0.0014 mol / g in 1 g / g are added and mixed under reduced pressure,
Then, 60 g of VMKS and 1,5 g of tin A were added thereto and mixed in the same manner under reduced pressure to prepare composition 5.

For comparison, a composition 6 was prepared in the same manner as above except that MMKS and VMKS were not added first but MMKS and VMKS were added later.
The slump properties, movement crack resistance, rubber properties, storage properties and transparency of the sample No. 6 were examined in the same manner as in Example 1, and the results shown in Table 1 were obtained.

[0025]

[Table 1]

[0026]

The present invention relates to a method for producing a room-temperature-curable organopolysiloxane composition, which comprises (A) a hydroxy-terminated organopolysiloxane;
In the method for producing a room temperature-curable organopolysiloxane comprising (B) iminoxysilane as a crosslinking agent, (C) silica fine particles, and (D) a condensation catalyst, the amount of iminoxysilane as the component (B) is calculated in advance by (A) After mixing with the organopolysiloxane as the component, silica fine particles as the component (C) are added, and then the condensation catalyst as the component (D) and the remaining amount of the component (B) are added as required. According to this, according to this composition, the workability is improved due to the long tack free time, which significantly improves the movement crack resistance, and further improves the anti-slump agent. The advantage is given that slump-free operation can be achieved without using.

Continuation of front page (56) References JP-A-2-41361 (JP, A)

Claims (1)

(57) [Claims] 1. A (A) the general formula ^{_{HO- (SiR 1 2 O) n}} -H (1 monovalent hydrocarbon radical unsubstituted or substituted where in R ¹ may be the same or different, n represents a natural number) organo represented by 100 parts by weight of polysiloxane (B) General formula R ² _4-a Si (ON = CR ³ ₂ ) _a or (Where R ² and R ³ are the same or different unsubstituted or substituted monovalent hydrocarbon groups, R ⁴ is an unsubstituted or substituted divalent hydrocarbon group, and a is 2, 3 or 4) 3-20 equivalents of the organosilicon compound in a molar ratio to the hydroxyl group of the organopolysiloxane of the component (A), and (C) silica having a specific surface area of 70 m ² / g or more and an adsorbed moisture of 0.5% or less. In preparing a room-temperature-curable organopolysiloxane composition comprising 1 to 50 parts by weight of fine particles (D) and 0 to 10 parts by weight of a condensation catalyst, the following formula (A) is used based on the hydroxyl group of the organopolysiloxane of the component (A). _oH + kC _oH ) × B _Mw (g) ... (1) where A _oH : hydroxyl group amount (mol) of organopolysiloxane of component (A), B _Mw : iminoxysilane of component (B) molecular weight, C _oH: (C) component of the silica bets - Tal OH group content (mol), k: 0 is calculated from <k <1.5 Iminokishishiran as component (B) in an amount
And the component (A) are mixed in advance, and then the mixture is mixed with a predetermined amount of the silica of the component (C), and then the remaining iminoxysilane of the component (B) and, if necessary, the component (D). A method for producing a room-temperature-curable organopolysiloxane composition, comprising mixing a predetermined amount of the condensation catalyst described above.