JPH07165923A - Production of silicone resin - Google Patents

Abstract

PURPOSE:To produce a high-molecular silicone resin having a strong affinity to polypropylene resin and useful as a resin modifier by heating a polydialkylsiloxane having terminal condensable groups under a reduced pressure. CONSTITUTION:A polydialkylsiloxane having terminal condensable groups, capable of forming an intermediate phase, preferably having a repeating unit of formula I (R1 is a >=1C alkyl; R2 is a >=2C alkyl same as or different from R1) and blocked with a silyl group of formula II (R3 is a >=1C alkyl; X is a condensable group) at each terminal is heated at a temperature of >= the melting point and <= the transition point of intermediate phase-isotropic liquid under a reduced pressure (preferably 0.01 to 100mm Hg), thus the objective high- molecular polydialkylsiloxane having the weight-average molecular weight of 500000 to 1500000 is efficiently produced.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing a high molecular weight polydialkylsiloxane which is effective as a resin modifier.

[0002]

2. Description of the Related Art Silicone resins are known to be effective for improving impact resistance, fluidity, and releasability of polypropylene resins (hereinafter sometimes abbreviated as PP). It is also used industrially. However, since the silicone resin has a poor affinity for PP, addition of the silicone resin to the PP causes problems such as a decrease in workability during melt-kneading and a bleed-out of the silicone resin after molding.

As a means for solving these problems, Japanese Patent Publication No. 52-43863 discloses a method of adding a block or graft copolymer of a vinyl polymer and a polyorganosiloxane as a compatibilizer. , A method using a high molecular weight silicone resin and having 2 carbon atoms in the side chain in order to enhance the affinity between the silicone resin and PP.
The method using the above-mentioned silicone resin having an alkyl group introduced therein is widely known and adopted.

However, the method using the block copolymer in the first method is not practical because it needs to be separately synthesized using an expensive compound such as an organolithium compound, and the method using the graft copolymer is not suitable. There is a problem that the PP molecule is cleaved during the reaction, and the deterioration of physical properties cannot be avoided. In the second method, a polydimethylsiloxane-based silicone resin having a molecular weight of more than 1,000,000 was obtained, and the workability during melt-kneading was considerably improved, but bleed-out was suppressed. Not in. Further, regarding a silicone resin having an alkyl group having 2 or more carbon atoms other than the polydimethylsiloxane type, a method for efficiently obtaining a high molecular weight one is not known. Therefore, in the third method, even if an alkyl group having 2 or more carbon atoms is introduced into the molecule in order to increase the affinity with PP, the molecular weight is low and a sufficient improvement effect is not obtained.

[0005]

Thus, there is no known method for efficiently obtaining a high molecular weight silicone resin having an alkyl group having 2 or more carbon atoms in its side chain, and the appearance of such a method is strongly desired. Was there.

[0006]

Means for Solving the Problems As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that a polydialkylsiloxane having a terminal condensable group and capable of forming an intermediate phase is reduced in pressure. Therefore, it was found that a high molecular weight polydialkylsiloxane can be efficiently obtained by heating to a temperature not lower than the melting point and not higher than the transition point of the intermediate phase-isotropic liquid, and completed the present invention.

That is, according to the present invention, a polydialkylsiloxane having a terminal condensable group and capable of forming an intermediate phase is kept under reduced pressure at a temperature not lower than the melting point and not higher than the transition point of the intermediate phase-isotropic liquid. A method for producing a high molecular weight polydialkylsiloxane, which comprises heating.

The polydialkylsiloxane used in the present invention is not particularly limited as long as it has a condensable group at the terminal and can form an intermediate phase, and a known polydialkylsiloxane can be used. Examples of the condensable group include a hydroxyl group; an alkoxy group such as a methoxy group, an ethoxy group and a propoxy group; an inorganic and organic acid group such as a trifluoromethanesulfonic acid group, a sulfuric acid group, a nitric acid group and an acetic acid group; chlorine,
Examples thereof include halogen atoms such as bromine, fluorine and iodine; alkali metal atoms such as sodium and potassium and hydrogen atoms.

The polydialkylsiloxane having a terminally condensable group used in the present invention is required to exhibit a mesophase. The intermediate phase referred to here is a phase which is found in a thermotropic liquid crystalline compound and exhibits an intermediate state between a solid crystalline state and an isotropic liquid state. For example, polydinormal propyl siloxane has 55 to 7
At 0 ° C. the solid crystalline state transitions to the mesophase,
The transition from the mesophase to the isotropic liquid occurs at ˜230 ° C.

In the present invention, a polydialkylsiloxane having a repeating unit represented by the following general formula (1) and having a terminal blocked with a silyl group represented by the following general formula (2) is relatively synthesized. It is preferable because it is easy.

[0011]

[Chemical 1]

[0012]

[Chemical 2]

(However, in the above general formula (1), R ₁ is an alkyl group having 1 or more carbon atoms, and R ₂ is an alkyl group having 2 or more carbon atoms which is the same or different from R ₁ . In the general formula (2), R ₃ is an alkyl group having 1 or more carbon atoms, and X is a condensable group.) These alkyl groups represented by R _{1 to} R ₃ may be those having carbon atoms in the above range. Although not particularly limited, when the alkyl group has more than 25 carbon atoms, the number of carbon atoms is 25 or less because the polymerization activity of the monomer as the raw material of the polydialkylsiloxane tends to decrease and synthesis tends to be difficult. It is preferable. The structure of the alkyl group is not particularly limited and may be linear, branched or cyclic. Further, X in the general formula (2) is not particularly limited as long as it is a condensable group described above.

The molecular weight of the polydialkylsiloxane having a terminal condensable group used in the present invention is not particularly limited, but in consideration of the efficiency of increasing the molecular weight of the polydialkylsiloxane and the ease of synthesis, the weight average molecular weight (hereinafter , Mw) is 10,000 to 500,
000 is preferable. The weight average molecular weight referred to herein is a polystyrene equivalent molecular weight measured by gel permeation chromatography (GPC).

The method for producing the polydialkylsiloxane used in the present invention is not limited at all, but in general, a cyclic dialkylsiloxane obtained by hydrolyzing a dialkyldichlorosilane represented by the following general formula (3) is represented by the general formula: It is preferable that the disiloxane represented by (4) is optionally added and polymerized in the presence of an acid or alkali catalyst as it is, or is obtained by washing with water.

[0016]

[Chemical 3]

[0017] (wherein, R ₁ and R ₂ in the general formula (3) is identical to R ₁ and R ₂ in the general formula (1), X ₁ and X in the general formula (4) ₂ is the same kind or different kind of condensable groups as X in the above-mentioned general formula (2).) The polydialkylsiloxane having a condensable group at the terminal thus obtained under reduced pressure A high molecular weight dialkylsiloxane can be produced by heating to a temperature not lower than the melting point and not higher than the transition point of the intermediate phase-isotropic liquid (hereinafter sometimes abbreviated as MI transition point). At this time, the polydialkylsiloxane having a condensable group at the terminal may be used not only as a single type but also as a mixture of a plurality of types having different side chains and terminal groups.

The pressure for heating the polydialkylsiloxane having a condensable group at the end is not particularly limited as long as it is less than atmospheric pressure, but it is preferably 0.01 to 100 mmHg in consideration of the efficiency of high molecular weight. . Further, the temperature for heating needs to be equal to or higher than the melting point of the polydialkylsiloxane having a terminal condensable group and lower than or equal to the transition point of the intermediate phase-isotropic liquid. At temperatures outside this range, there is almost no increase in the molecular weight.

In the production method of the present invention, the polydialkylsiloxane having a terminally condensable group to be used, the reaction pressure and the reaction temperature are not particularly limited, but the high molecular weight of the polydialkylsiloxane can be achieved by using an intermolecular structure. Since it occurs by a condensation reaction, it is preferable to carry out stirring during heating for the purpose of increasing the probability of contact between molecular ends. The stirring method is not particularly limited either, but since the viscosity of polydialkylsiloxane in the mesophase state is generally high, it is suitable for stirring a high-viscosity fluid. Preference is given to performing a type of agitation. In addition, a catalyst may be added if necessary for the purpose of promoting the condensation reaction. The catalyst that can be used at this time is not particularly limited as long as it accelerates the condensation reaction between the end groups of the polydialkylsiloxane. Specific examples of catalysts that can be preferably used include organic acid salts such as zinc octylate, iron octylate, tin octylate, cobalt octylate, and lead octylate; trifluoromethanesulfonic acid, hydrochloric acid, sulfuric acid, phosphoric acid, chloride Acids such as iron and boric acid; alkaline compounds such as sodium hydroxide and potassium hydroxide;
Examples include amines such as methylamine, diethylamine, trimethylamine, allylamine, and aniline.

By carrying out the reaction as described above, a high molecular weight polydialkylsiloxane having a weight average molecular weight of 500,000 to 1,500,000 can be efficiently obtained. The high molecular weight polydialkylsiloxane thus obtained can be used as a PP modifier as it is, or after being subjected to post-treatments such as washing, drying and pulverizing.

[0021]

[Function] Generally, a method of using an alkali catalyst and a method of using an acid catalyst are known as a method for producing a polydialkylsiloxane. When an alkali catalyst is used, the active sites generated by the coordination of the catalyst are generated between molecules one after another. It is said that the polymerization proceeds by the moving chain growth mechanism, or in the case of using an acid catalyst, by condensation of the terminal silanol and the terminal silyl ester generated by the chain growth mechanism and the coordination of the catalyst. However, polydialkylsiloxane having an alkyl group having 2 or more carbon atoms in the side chain cannot obtain a high molecular weight one because these mechanisms do not proceed smoothly due to steric hindrance. On the other hand, in the method of the present invention, the side chain has 2 carbon atoms.
The high molecular weight polydialkylsiloxane having the above alkyl groups can be efficiently obtained. Although the cause of such effects is not clear, molecular orientation is likely to occur,
In other words, it is presumed that the cause is that the intermolecular condensation reaction, which normally would not occur easily, proceeds by setting the conditions that promote the condensation reaction in a neutral state in the state where the contact between the molecular ends is likely to occur. ing.

[0022]

[Effect] According to the present invention, it is possible to efficiently obtain a high molecular weight polydialkylsiloxane having a high affinity for PP. This is epoch-making for the polydialkylsiloxane resin whose use as a modifier for PP was limited due to its low affinity for PP.

[0023]

EXAMPLES In order to more specifically describe the present invention, examples and comparative examples will be described below, but the present invention is not limited to these examples.

The polydialkylsiloxanes used in this example and comparative examples are shown below.

S1: Polydinormal propyl siloxane having hydroxyl groups at both ends (Mw = 350,000, melting point 66 ° C.,
M-I transition point 225 ° C) S2: polydinormal siloxane having a hydroxyl group at one end and a trifluoromethanesulfonic acid group at the other end (Mw = 250,000, melting point 65 ° C, M-I transition point 2)
20 ° C., but containing about 15 wt% of dinormal propyl siloxane cyclic trimer and a trace amount of trifluoromethane sulfonic acid) S3: Polydinormal propyl siloxane having dimethylethoxysilyl groups at both ends (Mw = 80,000, melting point 61)
° C, M-I transition point 210 ° C) S4: Polydinormal propyl siloxane having trimethylsilyl groups at both ends (Mw = 150,000, melting point 63 ° C, M
-I transition point 213 ° C.) S5: Polydimethylsiloxane having hydroxyl groups at both ends (Mw = 150,000, does not form PS348.7 intermediate phase manufactured by Chisso Corporation.) Incidentally, S1 to S4 were synthesized by the following method. did. First, dichlorosilane and propylene gas were blown into a hexane solvent in the presence of a chloroplatinic acid catalyst at the same time to cause a reaction to synthesize dinormalpropyldichlorosilane.
The isolated di-normal propyl dichlorosilane was further hydrolyzed to synthesize a di-normal propyl siloxane cyclic trimer. In the case of S1 and S2, the purified cyclic trimer was used as it was, and in the case of S3, 0.5 mol% of 1,3-diethoxytetramethyldisiloxane was added to S4.
In the case of, 0.25 mol% of hexamethyldisiloxane was added and polymerization was carried out in the presence of 1 mol% of a trifluoromethanesulfonic acid catalyst. In the case of S2, this is left as it is, and in the case of S1, S3 and S4, the polymerization product is dissolved in hexane and washed sufficiently with water to remove the catalyst, and further solvent washing is performed to remove residual monomers and then drying. Then, the dinormal propyl siloxane polymer of S1 to S4 was obtained.

Also, the melting point and M-I of these polymers
The transition point was determined by calorimetric analysis.

Examples 1 to 5 and Comparative Examples 1 to 4 Various polydialkylsiloxane polymers in the amounts shown in Tables 1 and 2 were used and made of a jacket-heated stainless steel having an internal volume of 2 liters equipped with a stirrer and a nozzle for connecting a pressure controller. The reactor was charged and stirred under the pressure and temperature conditions shown in Table 1 and Table 2 for 2 hours. After the completion of stirring, after confirming that the temperature in the reactor became 100 ° C or lower, the reactor was opened to the atmosphere, a part of the polymer in the reactor was sampled, and GPC measurement was performed to determine M
I asked for w. The results are shown in Tables 1 and 2.

The high-molecular weight dialkyl siloxanes obtained in Examples 1 to 5 were added to PP in an amount of 5 wt% and injection-molded to produce a plate-shaped molded product. The workability during melt-kneading was good, and the bleeding was good. I couldn't see any out.

[0029]

[Table 1]

[0030]

[Table 2]

Claims (1)

[Claims] 1. A polydialkylsiloxane having a terminal condensable group and capable of forming an intermediate phase is heated under reduced pressure to a temperature not lower than the melting point and not higher than the transition point of the intermediate phase-isotropic liquid. A method for producing a high molecular weight polydialkylsiloxane characterized by the above.