JPH0449851B2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field] The present invention relates to a method for polymerizing polyester, and in particular, to a method for polymerizing polyester, in which (β-hydroxyethyl) terephthalate (hereinafter referred to as BHT) or its initial condensate is made into fine particles and inert. This invention relates to a method for producing polyester by polymerizing it by dispersing it in a non-aqueous emulsion state in a medium.

[Prior art]

Bulk melt polymerization has been most commonly used to polymerize polyesters such as polyethylene terephthalate. However, in this method, the melt viscosity increases as the molecular weight of the polyester increases, and a large stirring power is required. Furthermore, since the melt viscosity becomes high, heat transfer from the walls of the condensation vessel becomes poor, and local deterioration due to heating tends to occur. In addition, it has several disadvantages, such as it takes time to extract the polymer and the degree of polymerization differs between the early and late stages of polymer extraction.

Therefore, the present inventors investigated a method for solving the above-mentioned drawbacks in polycondensation using BHT or its initial condensate, and found that silicone oil, which is an inert solvent, The present invention was completed based on the discovery that dispersing and subjecting ethylene glycol removal to reaction and using polysiloxane grafted with an acrylic or methacrylic polymer as a dispersion medium are extremely effective methods.

[Structure of the invention]

The gist of the present invention is that bis(β-hydroxyethyl) terephthalate or its initial condensate is mixed in silicone oil with a grafted polysiloxane having a polysiloxane as a backbone and a (meth)acrylic polymer as a branch as a dispersion stabilizer. According to a method for polymerizing polyester, the method comprises dispersing the polyester into fine particles and polymerizing the polyester by heating.

Any silicone oil can be used as long as it has good physical and chemical stability at temperatures of 150° C. or higher.

The grafted polysiloxane used in carrying out the present invention is necessary for dispersing BHT or its initial condensate in silicone oil in the form of fine particles and maintaining a good dispersion state. With polysiloxane as the core,
It has (meth)acrylic polymer as its branches. This grafted polysiloxane is produced by condensing an organosilane and a functional group-containing silane, such as an alkylene alkoxylan having a vinyl group, to produce a polysiloxane containing a functional group such as a vinyl group in the side chain, and then producing an acrylic ester. By graft copolymerizing methacrylic acid esters, it is possible to obtain a polysiloxane in which a (meth)acrylic polymer is graft-polymerized on the side chain. When synthesizing polysiloxane, cyclic polysiloxane, especially 3 to 3 repeating units, is used.
The main raw material is 8-cyclic dimethylpolysiloxane, and as a molecular weight regulator, a silane compound having one alkoxy group in one molecule, such as trimethylmethoxysilane or trimethylethoxysilane, is used.As the functional group-containing silane, dimethoxysilane is used. −
Dialkoxysilanes having a mercapto group such as 3-mercaptopropylmethylsilane, dialkoxysilanes having a vinyl group such as diethoxymethylvinylsilane, or dialkoxysilanes having a glycidyl group such as γ-glycidoxypropylmethyldiethoxysilane. However, it is preferable to polymerize at 100 to 150° C. using a silane compound having two alkoxy groups in one molecule and using a strong acid or a strong base as a catalyst.

To this, methacrylic acid or acrylic acid is added together with hydroquinone, heated to esterify it, then hydroquinone is removed, and (meth)acrylic acid esters are added together with peroxide and reacted at a temperature of about 50 to 90°C. Then, branches of acrylic polymer are grafted onto the polyorganosiloxane trunk. As the (meth)acrylic ester, methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, and benzine (meth)acrylate are preferred.

The molecular weight etc. of the grafted polysiloxane obtained in this way is determined appropriately taking into consideration its own stability, dispersion stability, and compatibility with polyester or silicone oil, but the molecular weight of the acrylic polymer that becomes the branch The molecular weight of the grafted polysiloxane is preferably about 1,000 to 300,000, which is about the same or lower than the molecular weight of the main polysiloxane. That is, if these molecular weights are too small, the compatibility with polyester or silicone oil will be insufficient, and if the molecular weights are too large, the probability of thermal deterioration will increase and the dispersion stability during polyester polymerization will decrease. Therefore, it is not desirable.
Furthermore, the weight ratio of polysiloxane to acrylic polymer in the grafted polysiloxane is appropriately selected in consideration of dispersion stability, etc., and is particularly preferably about 1:1.

In practicing the present invention, BHT is added to the silicone oil containing the grafted polysiloxane.
BHT or its initial condensate is added in a molten state and dispersed by shearing, or BHT or its initial condensate is melt-mixed with grafted polysiloxane and dispersed in silicone oil by shearing. A finely divided dispersion of the initial condensate is made.

The particle size of the fine particles of BHT or its initial condensate is determined from the viewpoints of improving the ethylene glycol separation reactivity from the fine particles and improving the dispersion stability of BHT and its initial condensate in silicone oil. , the particle size is about 100μ or less, especially 0.05~80μ
It is best to keep it within this range.

According to the method of the present invention, acrylic polymers, which are branches of grafted polysiloxane, are arranged with good affinity on the surface of BHT or its initial condensate fine particles, and polysiloxane, which is the trunk of grafted polysiloxane, is arranged on the silicone oil side. arranged and extremely stable
An organic emulsion of BHT or its precondensate is formed.

Therefore, this organic emulsion should be heated at over 150℃.
In particular, when polymerized by heating to 180°C to 300°C, the stirring torque does not increase even if the molecular weight increases, and the heat transfer from the pot wall does not change.

Polyesterification of BHT or its precondensate can be carried out without a catalyst or in the presence of a suitable catalyst.

After the obtained polyester is separated from the reaction medium and thoroughly washed with an organic solvent, it can be further subjected to a polymerization reaction. The silicone oil separated from the reaction system is filtered, and after ethylene glycol is distilled off, it is recycled back to the reaction system for use.

Since a specific grafted polysiloxane is used as a dispersion medium for BHT or its initial condensate in silicone oil, the fine particles of BHT or its initial condensate are stably and uniformly dispersed in silicone oil. This also greatly contributes to promoting the polyesterification reaction.

The grafted polysiloxane has a structure in which the acrylic polymer branches are placed on the particulate side and the trunk polysiloxane is placed on the silicone oil side at the interface between the particulates and the silicone oil, thereby achieving a dispersion effect. is estimated to be increasing.

The method of the present invention is not limited to the production of polyethylene terephthalate, but also polybutylene terephthalate,
Alternatively, it can be fully utilized in the production of copolymerized polyester.

The present invention will be explained in more detail with reference to Examples below.

All parts and percentages are by weight.

Example 1 (a) Production of grafted polysiloxane 50 parts of cyclic dimethylpolysiloxane (3 to 6 repeating units) and 3 parts of dimethoxy-3-mercaptopropylmethylsilane were used to obtain a polysiloxane with a molecular weight of about 8000. and 1 part of methoxytrimethylsilane were stirred together with 0.0075 part of potassium hydroxide at 140° C. for 3 hours under a nitrogen atmosphere.

The reaction system was cooled to 90°C, 1.3 parts of a 1% aqueous sulfuric acid solution was added, stirred for 1 hour, and then washed with water three times.

The water-washed reaction product was distilled to remove unreacted materials to obtain 45 parts of silicone polymer A.

Next, 45 parts of this silicone polymer A, 70 parts of methyl methacrylate, and 1900 parts of toluene were heated to 80°C for 5 minutes with 2.5 parts of benzoyl peroxide in a nitrogen atmosphere.
The mixture was heated and stirred for hours.

The product was added to excess acetone to precipitate graft polymer B, yielding 80 parts.

(b) Dispersion of fine particles of polyethylene terephthalate oligomer melt in silicone oil Part B1 of graft polymer obtained in (a) and polyethylene terephthalate oligomer obtained by direct polycondensation of terephthalic acid and ethylene glycol ([η]= 0.1) 100 parts antimony trioxide
A molten mixture of 0.045 parts was heated to 265°C for 30 minutes under stirring in a nitrogen atmosphere, and while maintaining the temperature at 265°C, it was poured into 400 parts of silicone oil heated to 265°C, and heated to 265°C under stirring. The reaction was carried out for 6 hours.

Microparticles formed as soon as the mixture was added to the silicone oil, and the microparticles remained stable during stirring.

The system was allowed to cool, and the silicone oil was collected by filtration. The intrinsic viscosity [η] of the polymer was 0.35.

Example 2 (a) Preparation of grafted polysiloxane 50 parts of cyclic dimethylpolysiloxane (3 to 6 repeating units), 3 parts of diethoxymethylvinylsilane, and methoxytrimethylsilane were used to obtain a polysiloxane with a molecular weight of about 8000. 1 part with 0.0075 part of potassium hydroxide under nitrogen atmosphere,
The mixture was stirred at 140°C for 3 hours.

The reaction system was cooled to 90°C, 1.3 parts of a 1% aqueous sulfuric acid solution was added, stirred for 1 hour, and then washed with water three times.

The water-washed reaction product was distilled to remove unreacted materials to obtain 45 parts of silicone polymer C.

Next, 45 parts of this silicone polymer C, 70 parts of methyl methacrylate, and 1900 parts of toluene were heated and stirred together with 2.5 parts of benzoyl peroxide at 80° C. for 5 hours under a nitrogen atmosphere.

The product was added to excess acetone to precipitate graft polymer D, yielding 78 parts.

(b) Dispersion of fine particles of polyethylene terephthalate oligomer melt in silicone oil Part D1 of the graft polymer obtained in (a) and the polyethylene terephthalate oligomer obtained by direct polycondensation of terephthalic acid and ethylene glycol ([η]= 0.1) 100 parts antimony trioxide
A molten mixture of 0.045 parts was heated to 265°C for 30 minutes under stirring in a nitrogen atmosphere, and while maintaining the temperature at 265°C, it was poured into 400 parts of silicone oil heated to 265°C, and the mixture was heated at 265°C under stirring. The reaction was carried out for 6 hours.

Microparticles formed as soon as the mixture was added to the silicone oil, and the microparticles remained stable during stirring.

The system was allowed to cool, and the silicone oil was collected by filtration. The intrinsic viscosity [η] of the polymer was 0.34.

Claims (1)

[Claims] 1 Bis(β-hydroxyethyl) terephthalate or its initial condensate is formed into fine particles in silicone oil using a grafted polysiloxane having a polysiloxane as a trunk and an acrylic polymer as a dispersion stabilizer as a dispersion stabilizer. A polyester polymerization method characterized by dispersion and heating polymerization. 2. The method for polymerizing polyester according to claim 1, wherein the fine particle size of bis(β-hydroxyethyl) terephthalate or its initial condensate is 100 μm or less.