JPH11147917A - Preparation of diallyl phthalate prepolymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a process for preparing a post-curable diallyl phthalate prepolymer having excellent properties such as electrical properties, heat resistance, chemical resistance and dimensional stability as a thermosetting resin. SOLUTION: There is provided a process for producing a diallyl phthalate prepolymer from a diallyl phthalate monomer by solution polymerization, which process comprises using hydrogen peroxide as the polymerization initiator, using 200-500 pts.wt., per 100 pts.wt. diallyl phthalate monomer and a, solvent selected among 2-propanol, 2-butanol and 2-methyl-1-propanol, performing the polymerization at 120-180 deg.C under elevated pressure, stopping the reaction when a part of the reaction solution is withdrawn from the reactor and then becomes turbid when cooled to 80-140 deg.C and separating the prepolymer precipitated after cooling. This process can provide a diallyl phthalate prepolymer from a diallyl phthalate monomer in high yields, and unlike a conventional process, can dispense with the extraction of the prepolymer with a large amount of a solvent because the prepolymer can be precipitated by simply cooling the reaction solution.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a post-curable diallyl phthalate prepolymer having excellent electrical properties, heat resistance, chemical resistance and dimensional stability as a thermosetting resin.

[0002]

2. Description of the Related Art As a conventional method for producing a diallyl phthalate prepolymer, polymerization of the monomer is stopped before a gel point by bulk polymerization or solution polymerization, and a large amount of a lower alcohol such as methanol is poured into a polymerization solution. A method is known in which an unreacted monomer is dissolved in the lower alcohol to separate the prepolymer, or a prepolymer is obtained by removing the unreacted monomer by distillation.

[0003] JP-B-35-943, JP-B-36-943
No. 21039 discloses diallyl phthalate using hydrogen peroxide as a polymerization initiator and a solvent such as a lower aliphatic alcohol having 5 or less carbon atoms or an aromatic hydrocarbon such as benzene, toluene, xylene, ethylbenzene and isopropylbenzene. A method is described in which polymerization is carried out at a monomer concentration of 75% or more, preferably 85 to 95% by weight, at a reaction temperature of 105 to 120 ° C., and then the resultant is poured into a large amount of the lower aliphatic alcohol to precipitate and separate a prepolymer.

Japanese Patent Publication No. 48-1832 discloses that an organic radical source is used as a catalyst in a very small amount at first, and additives such as cumene and diisopropylbenzene are present in an amount of more than 50% of the monomer. Polymerization is performed by adding the organic radical source in small portions at a time or by blowing air to generate the peroxide of the additive, and the additive is sequentially distilled to prevent precipitation of the formed prepolymer. Have gained.

In Japanese Patent Publication No. 24850/1990, polymerization is carried out using diallyl terephthalate and aromatic hydrocarbons such as toluene, xylene, ethylbenzene and isopropyl as solvents and di-tert-butyl peroxide as a catalyst.
The polymerization reaction solution was distilled off the solvent, and treated with 5 times by weight of methanol to obtain a copolymer.

[0006]

In the case of polymerization of an unsaturated compound having two unsaturated groups, such as diallyl phthalate, a polymer having a relatively low molecular weight, for example, a molecular weight of 4,000 to 4,000 is preferred.
Production of 10,000 prepolymers without gelation can be achieved by reducing the conversion of monomers to prepolymers or diluting the reaction system.
In the case of the above-mentioned conventional method, the reaction system is diluted with a lower aliphatic alcohol to 25% or less to raise the polymerization rate to 40%, and the reaction is carried out. A method is employed in which a large amount of a dissolving lower aliphatic alcohol is added to precipitate and separate a prepolymer.

However, the above conventional method has the following disadvantages. That is, a large amount of lower aliphatic alcohol is used in an amount of 10 times or more to extract a prepolymer from a polymerization solution. Therefore, a large amount of energy is consumed to recover the unreacted monomer from a mixture of the unreacted monomer and the lower aliphatic alcohol. There is a need. Separately, JP-B-45-13831, JP-B-45-14546, and JP-B-45-14
No. 547 discloses a prepolymer liquid phase separation method.
In these cases, the polymerization solution uses 5 times the amount of methanol or lower aliphatic alcohol, so that a large amount of energy has to be consumed to recover the unreacted monomer. An object of the present invention is to improve such a conventional method and to provide a new polymerization method which eliminates the labor of extracting a prepolymer from the reaction solution after the completion of the polymerization reaction.

[0008]

SUMMARY OF THE INVENTION The present invention provides a method for producing a prepolymer by polymerizing a diallyl phthalate premonomer, which increases the degree of polymerization as much as possible and makes it easier to separate and recover the prepolymer from a polymerization solution. We studied diligently how to do it. As a result, the lower aliphatic alcohol selected as a reaction solvent is used in a large amount with respect to the monomer, and the polymerization is carried out at a high reaction temperature. Thereafter, when the reaction solution was cooled to a predetermined temperature, it was found that a desired prepolymer was separated by precipitation.

The present invention relates to a method for producing a diallyl phthalate prepolymer from a diallyl phthalate monomer by solution polymerization, wherein hydrogen peroxide is used as a polymerization initiator.
Using a solvent selected from propanol, 2-butanol and 2-methyl-1-propanol in an amount of 200 to 500 parts by weight based on 100 parts by weight of diallyl phthalate monomer, a polymerization reaction is performed under pressure at 120 to 180 ° C. A process for producing a diallyl phthalate prepolymer, which comprises taking out a part, cooling the reaction solution to 80 to 140 ° C., stopping the reaction when the reaction solution becomes cloudy, and separating the prepolymer precipitated after cooling.

The diallyl phthalate monomer used in the present invention includes ortho, iso and tere monomers and mixtures thereof. The amount of hydrogen peroxide added may be 0.14 to 5.0 parts by weight as an anhydride based on 100 parts by weight of diallyl phthalate monomer.

The end point of the polymerization reaction in the method of the present invention is when the reaction solution becomes turbid when a part of the reaction solution is taken out of the system and cooled to 80 to 140 ° C., and the taken out reaction solution can be returned to the original reaction solution. Dissolves and becomes transparent. That is, the reaction solution is transparent at the reaction temperature. Normally, the time until clouding at 80 to 140 ° C. is 3 to 8 hours. Therefore, a part of the reaction solution is taken out after 3 hours from the start of the reaction, and 80 to 140 ° C.
It is sufficient to cool down. The cooling temperature is 30 to 4 times lower than the reaction temperature.
The temperature may be 0 ° C. lower, and when the reaction temperature is 120 ° C., it may be cloudy at 80 ° C. or higher, and when the reaction temperature is 180 ° C., it may be cloudy at 140 ° C. or less. The yield of the prepolymer according to the method of the present invention is 30 to 60%.

Various lower aliphatic alcohols are known in addition to those specified in the present invention, but none of them have obtained satisfactory results. That is, methanol,
When polymerization is performed in ethanol, a prepolymer can be obtained only at a low polymerization rate, and when polymerization is continued, gelation occurs. When n-propanol, n-butanol or tertiary butanol is used, the polymerization rate is low and the yield of prepolymer is low, which is not practical.

The solvent amount is 20 per 100 parts by weight of the monomer.
If the amount is less than 0 parts by weight, the content of the unreacted monomer becomes high because the amount of the solvent is small in the reaction solution after the polymerization reaction, and even if the yield of the prepolymer increases to nearly 60%,
The prepolymer does not precipitate out as a solid simply by cooling. On the other hand, if it is more than 500 parts by weight, the monomer is excessively diluted, the yield of the prepolymer is lowered, and the size of the reaction vessel becomes large, which is not practical.

The reason for reacting under pressure is to raise the reaction temperature. If the reaction temperature is lower than 120 ° C., the polymerization rate becomes slow, it takes a long time, and the productivity is poor. Even if the reaction temperature is 180 ° C. or more, the yield does not increase particularly. On the other hand, if the temperature is 180 ° C. or higher, a high-pressure vessel is required, and equipment cost is increased, which is not practical.

In the method of the present invention, to separate the prepolymer from the polymerization solution, the prepolymer precipitated by cooling the polymerization solution may be subjected to a decanting method (gradient method) or filtration. In particular, if the polymerization solution is left to cool, the prepolymer will aggregate and settle, so the supernatant containing the unreacted monomer may be decanted and removed. The prepolymer thus obtained can be obtained as a powder by evaporating the solvent. In this case, it contains a small amount of unreacted monomer remaining together with the solvent, but since the amount is small, it can be easily obtained as a powder. On the other hand, if the prepolymer is separated by filtration, the amount of the residual monomer will naturally decrease because the amount of the residual solvent is small. The amount of monomers contained in the prepolymer separated by the decanting method is 20% or less,
The amount of monomer contained in the prepolymer separated by filtration is 5% or less.

The prepolymer containing a small amount of this monomer is used as it is for the production of decorative boards, laminates, molded articles and other general uses. To further reduce the amount of monomer, a decanting method or filtration is used. The obtained prepolymer may be washed with a lower aliphatic alcohol according to a conventional method. Next, the present invention will be described in detail with reference to Examples and Comparative Examples.

[0017]

[Examples and Comparative Examples]

Example 1 200 g of diallyl terephthalate monomer, 3.0 g of 30% hydrogen peroxide and 400 g of 2-propanol were charged in a 1 liter autoclave, and the polymerization temperature was 150 ° C. and the pressure was 6
Polymerized at 〜7 kg / cm ² . A part of the polymerization solution was taken out, cooled, and the cloudiness point was measured. At this point, the reaction was stopped. The reaction time was 4 hours.

At the end of the polymerization, the reaction system was uniform and transparent, and when cooled to room temperature, the prepolymer precipitated in the lower layer. The solvent containing the unreacted monomer in the upper layer was decanted and the obtained prepolymer was dried. The polymerization yield was 52.0%.

The prepolymer had an iodine value of 89, an acid value of 1.2, and a number average molecular weight of 8,000 as determined by gel permeation chromatography. The monomer content was 20%.

Example 2 100 g of diallyl terephthalate monomer, 2 g of 30% hydrogen peroxide and 400 g of 2-propanol were charged into a 1 liter autoclave, and the polymerization temperature was 150 ° C. and the pressure was 6 to 7.
The polymerization was carried out at kg / cm ² . A part of the polymerization solution was taken out, cooled, and the cloudiness point was measured. At this point, the reaction was stopped. The reaction time was 6 hours.

At the end of the polymerization, the reaction system was uniform and transparent, and after cooling, the prepolymer settled down in the lower layer. The waxy prepolymer was separated by decantation, 5-fold 2-propanol was added, hot extraction was performed at 60 ° C. by the method of JP-B No. 45-14546, and the separated prepolymer was filtered and dried. Was. The polymerization yield was 36.0%.

The prepolymer had an iodine value of 67, an acid value of 0.6, and a number average molecular weight of 12,000 as determined by gel permeation chromatography. The monomer content was 1% or less.

Comparative Example 1 In Example 2, when 2-propanol was replaced with n-propanol for polymerization, the cloudiness point was 70 ° C., and the polymerization yield was 22.0.
0% and no high polymerization yield was obtained. In addition, when 2-propanol was replaced with tertiary butanol for polymerization, the cloudiness point was 77 ° C., the polymerization yield was 10.6%, and a high polymerization yield was not obtained.

Example 3 200 g of diallyl orthophthalate monomer, 1 g of 60% hydrogen peroxide and 400 g of 2-propanol were charged into a 1 liter autoclave, and the polymerization temperature was 170 ° C. and the pressure was 11
The polymerization was carried out at kg / cm ² . When the cloudiness point was determined in the same manner as in Example 1, the temperature was 104 ° C., and the reaction time was 3 hours.

At the end of the polymerization, the reaction system was uniform and transparent, and after cooling, the prepolymer was precipitated in the lower layer. The solvent containing the unreacted monomer in the upper layer was separated and the prepolymer was dried. The polymerization yield was 41.0%.

The prepolymer had an iodine value of 30.3, an acid value of 1.3, and a number average molecular weight determined by gel permeation chromatography of 10,200.

Example 4 140 g of diallyl terephthalate monomer, 2.8 g of 30% hydrogen peroxide, 420 of 2-methyl-1-propanol
g in a 1 liter autoclave, and the polymerization temperature was 16
Polymerization was performed at 0 ° C. and a pressure of 9 kg / cm ² . The cloudiness point was determined in the same manner as in Example 1 to be 105 ° C, and the reaction time was 5
It was time.

At the end of the polymerization, the reaction system was homogeneous and transparent, and after cooling, the prepolymer was precipitated in the lower layer. The solvent containing the unreacted monomer in the upper layer was separated and the prepolymer was dried. The polymerization yield was 39.5%.

The prepolymer had an iodine value of 80, an acid value of 0.8, and a number average molecular weight of 8,500 as determined by gel permeation chromatography.

Example 5 A 1 liter autoclave was charged with 200 g of diallyl isophthalate monomer, 2 g of 30% hydrogen peroxide and 400 g of 2-propanol, and the polymerization temperature was 150 ° C., and the pressure was 6 to 7.
The polymerization was carried out at kg / cm ² . The cloudiness point was determined in the same manner as in Example 1 to be 105 ° C., and the reaction time was 6 hours.

At the end of the polymerization, the reaction system was uniform and transparent, and after cooling, the prepolymer sedimented in the lower layer in a sticky manner. After separating the upper layer solution, a warm extraction at 60 ° C. was performed with a 5-fold amount of 2-propanol, followed by filtration and drying to obtain a prepolymer. Polymerization yield is 37.4
%Met.

The prepolymer had an iodine value of 58, an acid value of 1.0, and a number average molecular weight determined by gel permeation chromatography of 10,000. The monomer content was 1%.

Example 6 100 g of diallyl terephthalate monomer, 2 g of 30% hydrogen peroxide and 400 g of 2-butanol were charged into a 1 liter autoclave, and the polymerization temperature was 150 ° C. and the pressure was 2.5.
Polymerized at 3 kg / cm ² . When the cloudiness point was determined in the same manner as in Example 1, the temperature was 90 ° C., and the reaction time was 6 hours.

At the end of the polymerization, the reaction system was homogeneous and transparent, and after cooling, the prepolymer precipitated in the lower layer. The prepolymer was obtained by drying. The polymerization yield was 31.0%.

The prepolymer had an iodine value of 81, an acid value of 1.3, and a number average molecular weight determined by gel permeation chromatography of 9,000.

Example 7 150 g of diallyl terephthalate monomer, 450 g of 2-propanol, and 3 g of 30% hydrogen peroxide were charged into a 1 liter autoclave, and the polymerization temperature was 160 ° C. and the pressure was 9 to 1.
Polymerization was performed at 0 kg / cm ² . The cloudiness point was determined in the same manner as in Example 1 to be 127 ° C., and the reaction time was 8 hours.

At the end of the polymerization, the reaction system was homogeneous and transparent, and after cooling, the prepolymer precipitated in the lower layer. The prepolymer was obtained by drying. The polymerization yield was 58.2%.

The prepolymer had an iodine value of 80, an acid value of 0.9, and a number average molecular weight of 12,000 as determined by gel permeation chromatography.

Example 8 100 g of diallyl orthophthalate monomer, 100 g of diallyl terephthalate monomer, 2-propanol 4
00 g and 1.5 g of 60% hydrogen peroxide were charged into a 1 liter autoclave, and the polymerization temperature was 130 ° C. and the pressure was 2 to 3 kg.
/ Cm ² . The cloud point was determined in the same manner as in Example 1. The cloud point was 85 ° C., and the reaction time was 8 hours.

At the end of the polymerization, the reaction system was uniform and transparent, and after cooling, the prepolymer precipitated in the lower layer. The prepolymer was obtained by drying. The polymerization yield was 35%.

The prepolymer had an iodine value of 60, an acid value of 1.4, and a number average molecular weight of 6,000 as determined by gel permeation chromatography.

[0042]

According to the method of the present invention, a diallyl phthalate prepolymer can be obtained in high yield from a diallyl phthalate monomer, and unlike the conventional method, the prepolymer precipitates only by cooling the reaction solution. There is an excellent effect that it is not necessary to extract the prepolymer using a large amount of solvent, and the prepolymer can be separated by a decanting method or filtration.

Claims (3)

[Claims] When producing a diallyl phthalate prepolymer by solution polymerization from a diallyl phthalate monomer, a solvent selected from 2-propanol, 2-butanol and 2-methyl-1-propanol using hydrogen peroxide as a polymerization initiator. Diallyl phthalate monomer 10
Using 200 to 500 parts by weight with respect to 0 parts by weight, a polymerization reaction is carried out at 120 to 180 ° C. under pressure, a part of the reaction solution is taken out and cooled to 80 to 140 ° C. When the reaction solution becomes cloudy, the reaction is started. A method for producing a diallyl phthalate prepolymer, which comprises stopping, cooling and separating a precipitated prepolymer. 2. The diallyl phthalate monomer is a monomer selected from diallyl orthophthalate, diallyl isophthalate and diallyl terephthalate.
A method for producing the diallyl phthalate prepolymer described. 3. The method for producing a diallyl phthalate prepolymer according to claim 1, wherein the amount of hydrogen peroxide added is 0.14 to 5 parts by weight based on 100 parts by weight of the diallyl phthalate monomer.