JPH0848880A - Curable fluorosilicone composition - Google Patents

Abstract

(57) Abstract: A composition having excellent water and oil repellency, stain resistance, moisture resistance, and compatibility with an organosilicon compound having a hydrolyzable group is provided. An excess equivalent of CH ₃ Si (OCO) is added to a silanol-terminated organopolysiloxane (1) having an R _f group.
A composition containing a fluorosilicone obtained by reacting an organosilicon compound such as CH ₃ ) ₃ or a condensate of the organosilicon compound, and a curing catalyst, and containing substantially no water. Embedded image

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to curable fluorosilicone compositions.

[0002]

Conventionally, a curable silicone composition containing a silanol-terminated diorganopolysiloxane and an organosilicon compound having a hydrolyzable group has been used in automobiles, ships, aircraft, heavy electrical machinery, weak electrical machinery, electronics industry, and construction. In such fields, it is widely used as an adhesive sealant and the like. In recent years, along with the expansion of curable silicone compositions, improvements have been demanded in terms of functions such as stain resistance, oil resistance, moisture resistance and water / oil repellency. As a method for improving it, a method of adding a surface modifier having a polyfluoroalkyl group to the composition or applying it on the surface is known, but the effect is not sufficient, and durability in long-term use It has been pointed out that there are problems such as lack of.

It is also known to substitute some or all of the side chains of the silanol-terminated organopolysiloxane, which is the main component of the curable silicone composition, with trifluoropropyl groups (US Pat. No. 3,170,894, US Pat. No. 3,170,894). 3334067
No. 3398112, British Patent No. 1100680, etc.). However, the effect is extremely excellent water and oil repellency, antifouling property,
It was unsatisfactory in the field requiring moisture resistance.

[0004]

More than the conventional curable organopolysiloxane composition containing a trifluoropropyl group-containing organopolysiloxane as a main component,
In order to improve water repellency, oil repellency, stain resistance, and moisture resistance, it is desirable to introduce a longer-chain polyfluoroalkyl group. On the other hand, when a polyfluoroalkyl group is introduced into the organopolysiloxane, the compatibility between the organopolysiloxane and the organosilicon compound having a hydrolyzable group tends to deteriorate. In particular, when a long-chain polyfluoroalkyl group is introduced, even if the organopolysiloxane and the organosilicon compound are mixed, phase separation occurs between them and a sufficient cross-linking effect cannot be obtained. There is a problem that the elastic body having the rubber-like elastic body is not cured.

[0005]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and a silanol-terminated organopolysiloxane having a polyfluoroalkyl group represented by the general formula (1) is added to the silanol. A fluorosilicone obtained by reacting an organosilicon compound represented by the general formula (2) or a condensate of the organosilicon compound in an excess equivalent amount with respect to a terminal organopolysiloxane, and a curing catalyst, and substantially A curable fluorosilicone composition that is curable in the presence of moisture, characterized by being free of water.

[0006]

[Chemical 3]

[However, in the general formula (1), R ² ,
R ³ and R ⁴ may be the same or different and each is an alkyl group having 1 to 10 carbon atoms, an alkenyl group, or a phenyl group, and R ¹ is — (CH ₂ ) _p —R ⁵ (p is 1 ~
5 is an integer of ⁵ and R ⁵ is a perfluoroalkyl group having 3 to 20 carbon atoms. m + n is a number at which the viscosity of the organopolysiloxane at 25 ° C. becomes 100 to 200,000 centipoise (hereinafter, simply referred to as cP), and m / n =
It is 1/99 to 100/0. ]

[0008]

Embedded image (R ¹⁶ ) _a Si (R ¹⁷ ) _4-a (2)

[However, in the general formula (2), R
¹⁶ is an alkyl group having 1 to 10 carbon atoms or an alkenyl group, and R ¹⁷ is —OR ⁶ , —ONR ⁷ , or —ONR ⁸
R ^9, -NR ¹⁰ R ^11, or halogen atom. However, R ⁶ , R ¹⁰ and R ¹¹ are alkyl groups having 10 or less carbon atoms, —COR ¹² (R ¹² is an alkyl group having 5 or less carbon atoms),
Alternatively, —C (R ¹³ ) ═CH ₂ (R ¹³ is an alkyl group having 5 or less carbon atoms), and R ⁷ is ═CR ¹⁴ R ¹⁵ (R ¹⁴ , R ¹⁵
Are each an alkyl group having 5 or less carbon atoms), R ⁸ ,
Each R ⁹ is an alkyl group having 4 or less carbon atoms.
a is 0 or 1. ]

The structure of the organopolysiloxane represented by the general formula (1) (hereinafter referred to simply as "organopolysiloxane") is not particularly limited, and the fluorine-containing siloxane unit and the fluorine-free siloxane unit are randomly, alternately or block-shaped. It may be arranged in any type. Of these organopolysiloxanes, those in which R ² , R ³ , and R ⁴ are each a methyl group are preferable because they have excellent fluidity before curing and rubber elasticity after curing.

R ⁵ may be linear or branched, but is preferably linear. Especially p is 2-3,
R ⁵ is preferably a linear perfluoroalkyl group having 4 to 12 carbon atoms.

If the value of m / n is too small, sufficient effect of improving water / oil repellency, antifouling property, etc. cannot be obtained. m /
The larger the value of n is, the more excellent the effect of improving the water / oil repellency and the antifouling property is obtained, but the fluidity before curing tends to decrease.

However, the fluidity before curing can be appropriately improved by adjusting the molecular weight of the organopolysiloxane or adding a solvent. Therefore, the larger the value of m / n, the better, preferably 5/95 or more, and especially 20/8.
It is preferably 0 or more. The upper limit may be 100/0, but about 90/10 is preferable for the above reasons. The value of m + n is a number at which the viscosity of the organopolysiloxane is 100 to 200,000 cP. If the viscosity of the organopolysiloxane is too low, the rubber elasticity after curing becomes poor, which is not preferable. On the other hand, if it is too large, the fluidity before curing deteriorates, which is not preferable. The organopolysiloxane preferably has a viscosity of 1000 to 15
It is a number that becomes 0000 cP. Examples of such organopolysiloxanes include compounds of the following formulae, but the present invention is not limited thereto.

[0014]

Embedded image

As the organosilicon compound having a hydrolyzable group (hereinafter, simply referred to as an organosilicon compound), an organosilicon compound represented by the general formula (2) is adopted.

[0016]

Embedded image (R ¹⁶ ) _a Si (R ¹⁷ ) _4-a (2)

[However, in the general formula (2), R
¹⁶ is an alkyl group having 1 to 10 carbon atoms or an alkenyl group, and R ¹⁷ is —OR ⁶ , —ONR ⁷ , or —ONR ⁸
R ^9, -NR ¹⁰ R ^11, or halogen atom. However, R ⁶ , R ¹⁰ and R ¹¹ are alkyl groups having 10 or less carbon atoms, —COR ¹² (R ¹² is an alkyl group having 5 or less carbon atoms),
Alternatively, —C (R ¹³ ) ═CH ₂ (R ¹³ is an alkyl group having 5 or less carbon atoms), and R ⁷ is ═CR ¹⁴ R ¹⁵ (R ¹⁴ , R ¹⁵
Are each an alkyl group having 5 or less carbon atoms), R ⁸ ,
Each R ⁹ is an alkyl group having 4 or less carbon atoms.
a is 0 or 1. ]

Specifically, -OR ⁶ is -OCO.
_{CH 3, -OCOC 2 H 5,} -OC 2 H 5, -OCH
_{3, -OC (CH 3) =} CH 2, OC (C 2 H 5) = C
H _2, etc., as the -ONR ^7, -ON = C (CH
_{3) 2, -ON = C (} C 2 H 5) -CH 3, -ON = C
(C ₂ H ₅ ) _{2 and the} like are -O as -ONR ⁸ R ^9.
_{N (CH 3) 2, -ON} (C 2 H 5) -CH 3, -ON
(C ₂ H ₅ ) ₂ or the like is -N ¹⁰ R ¹¹ is -N
_{(CH 3) 2, -N (} C 2 H 5) 2, -N (C 2 H 5)
_{-CH 3, -N (CH 3)} -COCH 3, -N (C 2 H
₅₎ -COCH _3, and _{-N (CH 3) -COC 2 H} 5, as the halogen atom, Br, Cl, etc. are exemplified.

The organosilicon compound is a trifunctional compound having three hydrolyzable groups in the molecule, a tetrafunctional compound having four hydrolyzable groups, or a mixture thereof. A trifunctional compound alone or a mixture of a trifunctional compound and a tetrafunctional compound is preferable because the curing rate is high and gelation hardly occurs during the reaction. It may also be a mixture of organosilicon compounds having different R ¹⁷ .

Specific examples of the organosilicon compound include compounds represented by the following formulae, but the present invention is not limited thereto.

[0021]

Embedded image CH ₃ Si (OCOCH ₃ ) ₃ , CH ₃ Si
(OC ₂ H ₅ ) ₃ , CH ₃ Si [ON (C ₂ H ₅ ) ₂ ]
₃ , CH ₃ Si [N (CH ₃ ) (COCH ₃ )] ₃ , C
H ₃ Si [ON = C (CH ₃ ) (C ₂ H ₅ )] ₃ , CH
_{3 Si [N (CH 3)} 2] 3, CH 2 = CHSi (OC
H ₃ ) ₃ , Si (OCOCH ₃ ) ₄ , Si (OC ₂ H
₅ ) ₄ .

The organosilicon compound may be condensed as shown in the following formula (q is an integer of 2 or more) or may be a mixture thereof.

[0023]

Embedded image

In the present invention, it is important to react the organopolysiloxane with the organosilicon compound. Merely mixing the organopolysiloxane and the organosilicon compound causes phase separation gradually and does not cure into an elastic body having good rubber elasticity. It is also important to react the organopolysiloxane with an excess equivalent amount of the organosilicon compound. In order for the reaction product to be curable, the hydrolyzable groups must remain. Therefore, the number of hydrolyzable groups of the organosilicon compound in the reaction system needs to be larger than the number of silanol groups of the organopolysiloxane.

Unreacted silanol groups may remain in the reaction product, and if a large amount of unreacted silanol groups remain in the reaction product, the viscosity of the reaction product may easily change or the curability may be increased. However, it is not preferable because it becomes defective. On the other hand, an unreacted organosilicon compound may be present in the reaction product. When the reaction product is cured, the unreacted organosilicon compound condenses itself in the presence of water and reacts with the reaction product. When the curable fluorosilicone that is the reaction product is cured, an organosilicon compound having a hydrolyzable group can be additionally added.

The amount of the organosilicon compound is not limited as long as it is an excess equivalent, but when the amount is small, the frequency of reaction of two or more molecules of organopolysiloxane with respect to one molecule of the organosilicon compound becomes high and the reaction It is not preferable because the viscosity of the subsequent silicone increases and the subsequent handling becomes complicated. Preferably, per mol of organopolysiloxane,
It is preferable to mix and react at least 2 mol of the organosilicon compound.

Further, such a reaction is carried out in the substantial absence of water. In the presence of water, the hydrolyzable group of the organosilicon compound undergoes hydrolysis, the above reaction proceeds, the viscosity of the silicone after the reaction increases, or a gel is formed, and subsequent handling becomes complicated. Not preferable.

The reaction is preferably carried out within the temperature range of 60 to 200 ° C. Below the above temperature, the compatibility between the organopolysiloxane and the organosilicon compound is poor, and the reaction rate is very slow, which is not preferable. Furthermore, such a reaction has a viscosity of silicone of 200 to 200 after the reaction.
It is preferable to keep it to about 300,000 cP because it facilitates the subsequent handling.

Further, such a reaction may be carried out in the presence of a suitable solvent in order to reduce the viscosity and facilitate uniform mixing and stirring. As such a solvent, chlorofluorocarbons such as trichlorotrifluoroethane are preferably adopted. Further, a reaction catalyst may be added to accelerate the reaction. Examples of the reaction catalyst include tin compounds such as dibutyltin diacetate and dibutyltin dibenzoate, titanium compounds such as diisopropoxytitanium bisacetylacetonate, and zinc compounds such as zinc naphthenate.

The composition containing a curable fluorosilicone as a main component, which is produced by the above method, contains substantially no water. When such a composition contains water, it is not preferable because the composition itself cures during storage and the viscosity increases or gelation occurs.
In addition, if a large amount of water is contained, the hydrolysis may proceed completely by itself and the curability may be lost.

The composition of the present invention alone can be cured in the presence of water, but a curing catalyst is added to accelerate the curing. As the curing catalyst, the same compound as the above-mentioned reaction catalyst is adopted. A solvent may be added to reduce the viscosity. As such a solvent, chlorofluorocarbons such as trichlorotrifluoroethane are adopted.

Further, various fillers may be added if necessary. Examples of such fillers include silica, calcium carbonate, talc, carbon black, kaolin, clay, calcium titanate, alumina powder, magnesium oxide, glass powder and the like. The composition of the present invention can also be used in combination with other curable compounds or compositions.

[0033]

EXAMPLES The present invention will be specifically described below with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

Example 1 In a 100 ml glass reaction vessel, 20 g of a compound represented by the following formula (where x is a number having a viscosity of 39600 cP) and CH ₃ Si (OCOC) were used.
1.0 g of H ₃ ) ₃ and 0.008 g of dibutyltin dilaurate as a catalyst were added, and the components were reacted by stirring at 100 ° C. for 1 hour.

[0035]

[Chemical 9]

The product was a milky white but uniform liquid rubber, and about 1 g of this liquid rubber was dropped on a glass plate.
It spread out. After being left for 12 hours, it became a rubber-like elastic body having a smooth surface and well adhered to the glass plate.

Comparative Example 1 Example 1 except that heating is performed
A similar operation was performed to obtain a mixture. When this mixture was left to stand, droplets were phase-separated and remained sticky even after the mixture was left in the air at room temperature for 1 week.

(Examples 2 to 6) Rubber-like elastic bodies were obtained in the same manner as in Example 1 except that the types, amounts and curing times of the organopolysiloxane and the organosilicon compound were set as shown in Table 1.

[0039]

[Table 1]

(Comparative Example 2) 5 g of polydimethylsiloxane having silanol at both ends (viscosity 8000 cP), CH ₃ Si
0.25 g of (OCOCH ₃ ) ₃ and 0.002 g of dibutyltin dilaurate were placed in a glass container and mixed in a dry box. When 1 g of this was dropped onto a glass plate, it spreads out, and after 3 hours, it became a rubber-like elastic body having a smooth surface adhered to the glass plate.

N-Hexadecane 1 was used as an oil repellency test for the rubber-like elastic materials obtained in Examples 1, 3, 5, 6 and Comparative Example 2.
Drops were dropped and the contact angle was measured. The results are shown in Table 2.

[0042]

[Table 2]

[0043]

The composition of the present invention contains an organopolysiloxane containing a polyfluoroalkyl group as a main component, but can be cured into an elastic body having good rubber-like elasticity by moisture, and It has an effect that the alkyl group becomes a long chain and is cured well.

Since the elastic polyfluoroalkyl group after curing is chemically bonded to the composition of the present invention, excellent properties such as stain resistance, moisture resistance, water / oil repellency, and oil resistance are maintained for a long period of time. To be demonstrated. Further, by making the polyfluoroalkyl group have a long chain, the above-mentioned characteristics become extremely excellent.

Claims (1)

[Claims] 1. A silanol-terminated organopolysiloxane having a polyfluoroalkyl group represented by the general formula (1), and an excess of the organosilicon represented by the general formula (2) with respect to the silanol-terminated organopolysiloxane. A fluorosilicone obtained by reacting a compound or a condensate of the organosilicon compound, and a curable fluoro, which is characterized by containing a curing catalyst and containing substantially no water, capable of curing in the presence of moisture. Silicone composition. Embedded image [However, in the general formula (1), R ² , R ³ , R ⁴
May be the same or different and each has 1 to 1 carbon atoms.
0 is an alkyl group, an alkenyl group, or a phenyl group, R ¹ is — (CH ₂ ) _p —R ⁵ (p is an integer of 1 to 5,
R ⁵ is a C 3-20 perfluoroalkyl group). m + n is the number at which the viscosity of the organopolysiloxane at 25 ° C. is 100 to 200,000 centipoise, and m / n = 1/99 to 100/0. ## STR00002 ## (R ¹⁶ ) _a Si (R ¹⁷ ) _4-a (2) [In the general formula (2), R ¹⁶ has 1 to 10 carbon atoms.]
10 alkyl or alkenyl groups, R
^{17, -OR 6, -ONR 7, -ONR} 8 R 9, -NR
¹⁰ R ¹¹ or a halogen atom. However, R ⁶ , R
¹⁰ , R ¹¹ is an alkyl group having 10 or less carbon atoms, —COR ¹²
(R ¹² is an alkyl group having 5 or less carbon atoms), or -C (R
¹³ ) = CH ₂ (R ¹³ is an alkyl group having 5 or less carbon atoms), R ⁷ is = CR ¹⁴ R ¹⁵ (R ¹⁴ and R ¹⁵ are each an alkyl group having 5 or less carbon atoms), and R ⁸ , R ⁹ are each an alkyl group having 4 or less carbon atoms. a is 0 or 1
Is. ]