JPH07330904A - Production of hydroxyl-terminated organohydrogenpolyisloxane - Google Patents

Abstract

PURPOSE:To provide a method whereby a hydroxyl-terminated organohydrogenpolysiloxane can be produced stably by the ring-opening copolymn. of a cyclic hydrogensiloxane and a cyclic siloxane. CONSTITUTION:A hydroxyl-terminated organohydrogenpolysiloxane of formula III (wherein s>=1; and t>=3) is obtd. by subjecting a cyclic hydrogensiloxane of formula I (wherein R<1> is an optionally substd. hydrocarbon group; p>=1; and q>=0 provided p+q>=3) and a cyclic siloxane of formula II (wherein r>3) to ring-opening copolymn. in the presence of dimethyldichlorosilane and an acid catalyst (e.g. trifluoromethanesulfonic acid) and hydrolyzing the resulting product pref. by dropping it into water. The ring-opening copolymn. is done in the absence or presence of a solvent, generally at a temp. from room temp. to 80 deg.C for 1-24hr.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to an organopolysiloxane having a hydroxy group at the terminal of a molecular chain and a hydrogen atom bonded to a silicon atom not in the terminal but in the molecular chain (hereinafter referred to as an organohydrogenpolysiloxane terminated with a hydroxy group). Referred to as siloxane).

[0002]

2. Description of the Related Art Conventionally, a terminal trimethylsilyl-terminated organohydrogenpolysiloxane has been known to open a cyclic hydrogenpolysiloxane and a cyclic polysiloxane in the presence of an acid catalyst using hexamethyldisiloxane or terminal trimethylsilylsilyldiorganopolysiloxane as a stopper. It is produced by ring polymerization and neutralization. Therefore, as a method for producing a terminal hydroxy group-terminated organohydrogenpolysiloxane, it is conceivable to use a siloxane having a hydroxy group at the terminal as a stopper in the above method.

[0003]

However, when siloxane or the like having a hydroxy group at the terminal is used as the stopper, the acid catalyst reacts with the silanol group of the stopper and polymerization does not occur or the stoppers are not separated from each other. There was a problem that the dehydration condensation reaction proceeded and the viscosity of the stopper was extremely increased to cause gelation, so that it was not possible to produce the target terminal hydroxy group-terminated organohydrogenpolysiloxane.

Therefore, an object of the present invention is to provide a method capable of stably producing an organohydrogenpolysiloxane having a terminal hydroxy group.

[0005]

According to the present invention, the following general formula (1):

[Chemical 4] In the formula, R ¹ may be the same or different and is an unsubstituted or substituted monovalent hydrocarbon group, p is an integer of 1 or more, q
Is an integer of 0 or more, provided that p + q ≧ 3, and a cyclic hydrogen siloxane represented by the following general formula (2):

[Chemical 5] In the formula, R ¹ is as described above, r is an integer of 3 or more, and ring-opening polymerization is performed in the presence of dimethyldichlorosilane and a catalyst, and then a reaction product is formed. General formula (3) consisting of hydrolyzing a product:

[Chemical 6] In the formula, R ¹ is as described above, s is an integer of 1 or more, and t is an integer of 3 or more, and a method for producing a terminal hydroxy group-terminated organohydrogenpolysiloxane sun is provided. It

That is, in the present invention, the cyclic hydrogen siloxane of the general formula (1) and the general formula (2) are used.
In the ring-opening polymerization of the cyclic siloxane, dimethylchlorosilane acts as a stopper. Therefore, by this ring-opening polymerization, a hydrogen siloxane having a dimethylchlorosilyl group at the terminal and a hydrogen atom bonded to silicon in the molecular chain can be obtained. A hydroxy terminated organohydrogenpolysiloxane is obtained. In particular, the stopper dimethylchlorosilane is inactive with respect to the catalyst, and therefore does not cause any problem of condensation between stoppers or gelation of the stopper during ring-opening polymerization.

(Starting Material) In the present invention, the starting material used for the ring-opening polymerization is the cyclic hydrogen siloxane represented by the general formula (1) and the cyclic siloxane represented by the general formula (2).

In the above-mentioned general formula (1), R ¹ is an unsubstituted or substituted monovalent hydrocarbon group, specifically, an alkyl group such as a methyl group, an ethyl group and a propyl group, a cyclohexyl group and the like. Cycloalkyl group, alkenyl group such as vinyl group and allyl group, aryl group such as phenyl group and tolyl group, aralkyl group such as benzyl group and phenylethyl group,
And groups in which at least a part of hydrogen atoms of these groups are substituted with halogen atoms, such as a 3,3,3-trifluoropropyl group. Further, in the general formula (1), p is an integer of 1 or more, preferably an integer of 1 to 4, and q is an integer of 0 or more, preferably 0 to 4. However, p and q satisfy p + q ≧ 3. In the general formula (2), R ¹ is a group as described above, and r is 3 or more, preferably an integer of 3 to 8.

The cyclic hydrogen siloxane of the general formula (1) is a source of hydrogen atoms bonded to silicon in the molecular chain, and the amount ratio of the cyclic hydrogen siloxane to the cyclic siloxane of the general formula (2) is It may be set according to the content of silicon atom-bonded hydrogen atoms in the target polymer.

(Ring-Opening Polymerization) The above-mentioned ring-opening polymerization of cyclic hydrogen siloxane and cyclic siloxane is carried out in the presence of a catalyst using dimethylchlorosilane as a stopper. As the catalyst, those conventionally used as this kind of ring-opening polymerization catalyst, for example, acid catalysts such as sulfuric acid, trifluoroacetic acid, trifluoromethanesulfonic acid, etc. are used. The amount used may be a so-called catalytic amount, and is usually in the range of 100 to 50,000 ppm based on the total amount of the cyclic hydrogen siloxane and the cyclic siloxane. The dimethylchlorosilane used as a stopper is generally used in an amount of 0.2 to 30 parts by weight, particularly 0.3 to 20 parts by weight, per 100 parts by weight of the total amount of the cyclic hydrogen siloxane and the cyclic siloxane.

Although ring-opening polymerization can be carried out without solvent,
If necessary, a solvent having no active hydrogen, such as toluene, xylene, hexane, or tetrahydrofuran, which does not inhibit polymerization can be used. The polymerization temperature and the polymerization time are set according to the degree of polymerization of the target polymer and the like, but generally, they may be in the range of room temperature (18 ° C) to 80 ° C for about 1 to 24 hours.

The thus obtained hydrogen siloxane having a dimethylchlorosilyl group at the terminal and a silicon-bonded hydrogen atom in the molecular chain is represented by, for example, the following formula (4):
It is represented by.

[Chemical 7] In the above formula, R ¹ , s and t are as described above.

(Hydrolysis) The above-obtained hydrogen siloxane having a dimethylchlorosilyl group at the terminal and a silicon-bonded hydrogen atom in the molecular chain is subjected to hydrolysis. This hydrolysis is carried out by mixing with water, and the amount of water used is at least a stoichiometric amount sufficient to replace the chlorine atom at the terminal of the molecular chain with an OH group, preferably a stoichiometric amount. 1. It is recommended to use more than 1 time. In addition, the hydrolysis is usually preferably carried out by dropping the hydrogen siloxane into water in order to prevent condensation during the hydrolysis of the hydrogen siloxane.
Of course, if there is no problem of condensation, it is not necessary to use such a method.

In the hydrolysis, if necessary,
Neutralizing agents such as sodium hydrogen carbonate, calcium carbonate and propylene oxide can be used. This neutralizing agent is used to deactivate the acid catalyst used in the ring-opening polymerization to stabilize the polymer. further,
In the above hydrolysis, if necessary, the above-mentioned organic solvent having no active hydrogen may be used.

The thus-obtained hydrolysis product is subjected to a conventional purification treatment such as filtration or stripping to obtain the desired terminal hydroxy group-terminated organohydrogenposiloxane represented by the general formula (3). be able to.

Since this polymer has a SiH group in the molecular chain, it serves as a curing agent for the addition-curing organopolysiloxane composition, and has a hydroxyl group at the end of the molecular chain, so that it is a condensation-curing organopolysiloxane composition. It is useful as a base polymer of

[0017]

EXAMPLE 1 In a four-necked flask equipped with a stirrer, a thermometer, a dry nitrogen inlet and a calcium chloride tube, 2368 g of octamethyltetracyclosiloxane, 480 g of tetramethyltetrahydrogentetracyclosiloxane and dimethyldichlorosilane were placed. 128 g and 5 g of trifluoromethanesulfone sun were added, and the mixture was reacted at room temperature for 24 hours to perform ring-opening polymerization.

Then, in a four-necked flask equipped with a stirrer, a thermometer, and a dropping device capable of flowing dry nitrogen, THF was added.
1000 g, sodium hydrogen carbonate 250 g, water 1
80 g was added and the polymerization product obtained above was added dropwise with stirring to carry out hydrolysis. After the dropping, the mixture was left stirring for 24 hours. The resulting hydrolyzed solution was filtered to remove salts, and then stripped to obtain 2,617 g of an oily polymer (yield 89%).

The following physical properties of the obtained oily polymer were measured. Viscosity: Measured using a BL-type rotational viscometer in a thermostatic chamber at 25 ° C. Measured value 285 cP Si-H group content: The obtained oily polymer was treated with a butanol / potassium hydroxide solution, and the amount of hydrogen generated was measured. Measurement value 65 ml / g (theoretical value 61 ml / g) Si-OH content: A platinum catalyst was added to the obtained oily polymer and stirred, and the amount of hydrogen generated was measured to calculate the silanol content. Measured value 17 ml / g (Theoretical value 15 ml / g)

From the above results, it was confirmed that the obtained oily polymer was a terminal hydroxy group-terminated organohydrogenpolysiloxane represented by the following formula.

[Chemical 8] In the formula, s has an average of 7.64 and t has an average of 29.16.

[0021]

EFFECTS OF THE INVENTION According to the present invention, there is no problem of condensation between stoppers or gelation of stoppers during ring-opening polymerization, so that the terminal hydroxy group-terminated organohydrogenpolysiloxane can be stably produced.

Claims (1)

[Claims] 1. The following general formula (1): In the formula, R ¹ may be the same or different and is an unsubstituted or substituted monovalent hydrocarbon group, p is an integer of 1 or more, q is an integer of 0 or more, provided that p is p.
And a cyclic hydrogen siloxane represented by the following general formula (2): embedded image In the formula, R ¹ is as described above, r is an integer of 3 or more, and the cyclic siloxane represented by is subjected to ring-opening polymerization in the presence of dimethyldichlorosilane and a catalyst, followed by reaction formation General formula (3) consisting of hydrolyzing a product: In the formula, R ¹ is as described above, s is an integer of 1 or more, and t is an integer of 3 or more, The method for producing a terminal hydroxy group-terminated organohydrogenpolysiloxane sun.