JPS60139717A - Production of polyester - Google Patents

Abstract

PURPOSE:To improve the rates of diffusion and removal of ethylene glcyol and a homogeneous reaction, by finely pulverizing bis-omega-hydroxyalkyl terephthalate, forming an emulsion of the obtained powder in the presence of a high-molecular substance and polymerizing it by heating. CONSTITUTION:Bis-omega-hydroxyalkyl terephthalate or its precondensate is finely pulverized into a particle having such a size that the characteristic particle diameter is equal to or smaller than 500mu. The finely pulverized particle is dispersed in a heat-transfer fluid in the presence of a high-molecular substance soluble in said fluid to form an emulsion. This emulsion is polymerized by heating to a temperature >= the m.p. of the particle. The bis-omega-hydroxyalkyl terephthalate or its precondensate can be prepared by condensing or transesterfying an aromatic dicarboxylic acid or its dialkyl ester with an alpha,omega-diol acid.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a method for producing polyester. This invention relates to a method for producing polyester by heating and polymerizing it in a state in which it is dispersed in the form of fine particles in a medium.

[Prior art]

As shown in Fiber Handbook (Maruzen Co., Ltd., November 30th edition, 1961), there are known polyester polymerization methods that have been developed so far, such as batch polymerization method and continuous polymerization method. It has been pointed out that the polymerization efficiency of the existing method still needs to be improved, or that the complexity of the equipment needs to be improved.

A method for improving the polymerization rate of bone ester is disclosed in Japanese Patent Publication No. 39-684.8 or Japanese Patent Publication No. 48-'5'.
As shown in No. 1'19, BHT or its initial condensate is formed as a thin film with a thickness of 0.1 to 4 + u, or a thin film of 0.026 to 0.3 IK is formed on an endless metal belt. Methods have been shown to produce polyester by feeding the BHT into a heating zone and removing ethylene glycol, but these methods do not provide a sufficient surface area to remove ethylene glycol from BHT or its initial condensate. Not there,
From the viewpoint of improving the polymerization rate of polyester, it is desired that a further improved method be developed.

Another method, as shown in Japanese Patent Publication No. 35-4993, is B) a method in which IT or its initial condensate is melted and injected together with gas into a vacuum and polymerized at a temperature of 150 to 300°C. However, this method is also difficult to control the particle size of the powder because the medium for the powder of BT (T) or its initial condensate is in a vacuum or an inert gas atmosphere. Sedimentation cannot be avoided, and further improvements are said to be necessary from the viewpoint of improving polymerization efficiency.

Therefore, the present inventors conducted studies with the aim of improving the rate of diffusion and separation of ethylene glycol from BHT or its initial condensate and homogenizing the reaction.
Treating BHT or its initial condensate as a fine powder is the most effective way to increase its surface area, and is highly effective in promoting the polymerization reaction by removing ethylene glycol. The present invention was completed by discovering that a method of using a polymer soluble in the liquid organic substance as a dispersion medium for the initial condensate is an extremely effective method.

[Structure of the invention]

The gist of the present invention is to atomize bis-W-hydroxyalkyl terephthalate or an initial condensate thereof so that its representative diameter becomes a particle size of 500μ or less, and add a polymer compound soluble in the heat medium to a liquid heat medium. BHT or its initial condensate is uniformly dispersed as a medium and heated to a temperature above the melting point, preferably 270°C to 320°C, to cause a condensation reaction, and the resulting ethylene glycol and low boiling point components are absorbed into the heating medium. The characteristic lies in the manufacturing method of polyester.

Bis-w-hydroxyalkyl terephthalate or its initial condensate used in carrying out the present invention is terephthalic acid, inphthalic acid, orthophthalic acid, 2,6-su7
Aromatic dicarboxylic acids such as thalene dicarboxylic acid or their dialkyl esters and ethylene glycol, 1,
3-7' donkey/diol, 1,4-butanediol, 1
, 6-hegysandiol and other α,ω-diols by condensation or transesterification.

When carrying out the present invention, BHT or its initial condensate is treated as fine particles of 500 μm or less and 300 μm or less, and the effect of increasing the surface area is used to promote the ethylene glycol removal reaction. It is best to melt the BHT or its initial condensate using an atomizer or the like to obtain a desired particle size.If the representative diameter of these fine particles exceeds 500μ, desorption from the fine particles may be difficult. This is not preferable because the ethylene glycol reaction rate will rapidly decrease (゜O).
) It is a substance that is non-reactive with IT or its initial condensate, and is preferably an organic solvent with high affinity for ethylene glycol, such as halogen, toluene, xylene, tetrazine, decal, etc. , hexamenalbenzene,
Specific examples include a/trace/, methyl ethyl ketone, naphthalene, halaffinic hydrocarbons, biphenyl, diphenylmethane, triphenylmethane, bi/zil, fena/trelli/, and silicone oil.

Examples of the polymer compounds soluble in the heating medium used in carrying out the present invention include BI(T) or Since the initial condensate fine particles can be efficiently dispersed in the heating medium, the fine particles do not precipitate or aggregate (the ethylene glycol and low-volatile components from the fine particles do not precipitate or aggregate). Absorption into the liquid heat medium can be carried out extremely smoothly.

It is preferable to use a reaction temperature above the melting point of BHT or its initial condensate, especially between 270 and 320°C; too low a temperature will slow down the condensation reaction; This is not preferred because undesirable reactions such as decomposition reactions of the initial condensate occur.

The present invention can be carried out by dispersing fine particles of BHT or its initial condensate in an inert liquid heating medium, but uniform dispersion of the fine particles in the heating medium can be achieved by mechanical stirring. Alternatively, this can be achieved by using an organic or inorganic dispersion stabilizer.

According to the present invention, since BHT or its initial condensate is treated as a finely divided product, its surface area can be significantly increased compared to conventional methods, so that the ethylene glycol removal reaction can be carried out efficiently. Since the dispersion medium of the initial condensate is a liquid heating medium, the temperature of the reaction system can be uniformly controlled, and these media have an affinity for ethylene glycol. Ethylene glycol removal reaction from the condensate can be carried out smoothly. Furthermore, B.U.
These reactions can be carried out more smoothly without causing any inconvenience such as precipitation of T or its initial condensate fine particles (because they can be uniformly dispersed in the heating medium).

When carrying out the present invention, a method is used in which the heat transfer medium absorbs ethylene glycol and low boiling point components released from BHT or its initial condensate, and this liquid heat transfer medium is taken out of the reaction system and these components are removed. After that, it is returned to the reaction system and reused.

After the reaction, the polyester is taken out from the reaction vessel, and if the heating medium is a low boiling point solvent, it is simply dried, or if the heating medium is a high boiling point solvent, it is washed and dried with another low boiling point solvent. Bye.

When carrying out the present invention, it is preferable to use a reaction vessel as shown in FIG. 1 or 2.

In the figure, l is a rectification column, 2 is a reaction vessel, 3 is a filter,
4 is a pump, 5 is an extraction tank, 6 is a water recovery port, 7 is a water supply port, and 8 is a water discharge port.

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

Example 1 100 parts of the obtained esterified product (I, V = 0.12) of terephthalic acid and ethylene glycol, 400 parts of toluene, 0.05 part of a/thymontriacetate, and 0.1 part of polystyrene were added as shown in FIG. Reaction capacity as shown! (51
) and while purifying toluene, the mixture was heated to 265° C. and reacted for 30 minutes under pressure and strong stirring. The resulting slurry was cooled to 120°C, taken out, washed with acetone and water, and dried to obtain polyethylene terephthalate powder. The average particle size of this powder is 253 μm, which is 1.5 μm of polyester. V was 0.47.

Furthermore, the state of the slurry was very stable during the reaction period, and almost no current was generated.

Example 2 Transesterified product (I, V=
0.14) 100 parts, tetralin 500 parts, antimony triacetate) 0.03 parts, polymethylef 0.15
The mixture was placed in a reaction vessel (5f) as shown in FIG. 2, and reacted for 40 minutes at 270° C. under pressure and strong stirring while rectifying the tetralin. The resulting slurry was cooled to 120°C, taken out, washed with acetone and water, and dried to obtain polyester powder. The average particle size of this powder is 1'
85 Jim, and -1, V was 0.53. Furthermore, the state of the slurry was very stable during the reaction period, and almost no current was generated.

Example 3 Powder of esterified product of terephthalic acid and 1,4-buta/diol (average particle size 75 μff, 100 parts, toluene 400 parts, polymethyl methacrylate 0.1 part, a/thimontriacetate) 0.03 1 part was placed in the same container as in Example 1, and while purifying toluene, the mixture was pressurized at 270°C.
The reaction was allowed to proceed for 30 minutes with strong stirring. The resulting slurry was cooled to 120°C, taken out, and dried in a vacuum dryer at 100°C to obtain polyester powder.

The average particle size of this powder was 80 μm, and I and V increased by 6.7 VC from 3.1 before the reaction. Moreover, the state of the slurry was very stable during the reaction period, and there was almost no generation of cullet.

Comparative Example 1 The same experiment as Example 2 was conducted except that polystyrene was not used. As a result, it seems that dispersed particles were produced in the early stage of polymerization, and the stirring torque was small, but the stirring torque suddenly increased about 10 minutes after the start of the reaction. After 40 minutes of reaction, the contents were cooled to 120°C and the lid of the reactor was opened to find that the polymer had become sticky. I and V of the obtained polyester were 0.22.

[Brief explanation of the drawing]

FIGS. 1 and 2 show a reaction apparatus used in carrying out the present invention. Page 1 of the drawings (no change in content) Figure 4 2nd country procedure amendment (method) April 2, 1980 Yuhi Patent Application No. 58-245789 2 Title of invention Process for manufacturing polyester 3, Amendment Patent applicant: 2-3-19 Kyobashi, Chuo-ku, Tokyo (603) Akio Kawasaki, President and CEO of Mitsubishi Rayon Co., Ltd. 4; Agent: Mitsubishi, 2-3-19 Kyobashi, Chuo-ku, Tokyo Rayon Co., Ltd. (6949) Buried Earth Reported by Sawa 1 Masao 5, Amendment Order dated March 7, 1980 (Delivery date March 27, 1980) Procedural Amendment Document March 1985 lθ Manabu Shiga, Commissioner of the Japan Patent Office2, Name of the invention: Process for producing polyester3, Relationship with the person making the amendment Patent applicant: 2-3-19 Kyobashi, Chuo-ku, Tokyo (603) Director, Mitsubishi Rayon Co., Ltd.tI Akio Naga Kawasaki 4, Agent 6, 2-3-19 Kyobashi, Chuo-ku, Tokyo Subject of amendment (1) “3.1 to 6.” on page 11, line 8 of the amended specification.
7" is corrected from "0.31 to 0.67J.

Claims (2)

[Claims] (1) Atomized luterephthalate or an initial condensate thereof in bis-W- and crystalline oxygen to a particle size with a typical diameter of 500μ or less is added to a liquid heating medium in the presence of a polymeric substance soluble in the heating medium. - Disperse under pressure to form an emulsion, and heat to a temperature higher than the melting point of the atomized material to polymerize.
A method for producing polyester, which is characterized by: (2) As a liquid heat medium, bis-W-hydroxyalkyl terephthalate is characterized by using an organic solvent that is non-reactive with its initial condensate. ! lij, own method for producing polyester. , .