KR950006722B1 - Method for producing polyester-resin - Google Patents

Abstract

The solid state polymerized high molecular weight polyester resin for reinforcing agent in rubber products such as a tire cord etc., after preparation of prepolymer, is manufactured by mixing 0.1-10 wt% crystalline powder of particle size of 20-200 mesh of polyester prepolymer during the solid state polymerization with polyester prepolymer including the structure unit of polyethylene terephthalate or more than 80 mol% ethylene terephthalate, and crystallizing the mixture with temperature elevation. The crystalline powder is produced by pulverizing the crystalline body after crystallization of prepolymer chips at 120-180 deg.C for 10-300 min.. The intrinsic viscosity of prepolymer has the range of 0.4-0.7 dl/g.

Description

Manufacturing method of high molecular weight polyester resin

The present invention relates to a method for producing a high molecular weight polyester, and more particularly, by adding a crystalline powder to the prepolymer to suppress the fusion phenomenon to significantly shorten the solid-state polymerization time to effectively produce a high molecular weight polyester It is about a method.

In general, high molecular weight polyester resins are rapidly used in the manufacture of bottles, tire cords, various containers and microwave containers.

In general, high molecular weight polyester resins having an intrinsic viscosity of 0.7 dl / g or more are uneconomical when manufactured by melt polymerization, and various side reactions occur to impart poor physical properties to the resin. The dl / g prepolymer is dried and crystallized and then heated to give a vacuum or inert to increase molecular weight.

If the step of crystallization is omitted and the temperature is raised to the solid phase polymerization temperature rapidly, the prepolymer chip is fused to form a solid mass. Therefore, during the solid state polymerization reaction, a crystallization process is necessary, but the crystallization and the temperature increase step require a long time.

In order to solve this drawback, Japanese Patent Publication No. 73-43193 proposes a method of preventing fusion between prepolymers by adding metal salts of Groups 1, 2, and 3 of the periodic table, but this is a disadvantage that the additive remains as an impurity even after the reaction. There is this.

In addition, Korean Patent Publication No. 91-3567 discloses a method of preventing fusion between prepolymers by solid phase polymerization after addition and mixing of an inert liquid having a boiling point of 160 ° C. or higher, but again, a small amount of inert liquid may remain in the polymer. Because of this size, it is difficult to be used for food packaging.

The present inventors have studied to solve the above problems, and the present invention has been achieved by shortening the temperature raising and crystallization time required for decoration in the solid phase polymerization of polyester.

Accordingly, an object of the present invention is to provide a method for preventing fusion phenomenon and shortening solid phase polymerization time by adding crystalline powder of polyester prepolymer to polyester prepolymer.

Hereinafter, the present invention will be described in detail.

The present invention is to prepare a prepolymer by the polycondensation reaction, and then to prepare a high molecular weight polyester by the solid phase polymerization method, the temperature of the solid polymer by mixing 0.1 to 10% by weight of the crystalline powder of the prepolymer with the polyester prepolymer And crystallization.

Referring to the present invention in more detail as follows.

The present invention is a fusion phenomenon by mixing 0.1 to 10% by weight of a polyester powder having a size of 20 to 200 mesh pre-crystallized on a polyester prepolymer chip having an intrinsic viscosity of 0.4 to 0.7 dl / g made by melt polymerization Crystallization at high speed while preventing the is characterized in that the overall solid-state polymerization time is shortened.

In the present invention, the prepolymer for solid phase polymerization is usually made in the form of pellets and prepared by conventional melt polymerization. Conventional temperatures, catalysts, catalyst contents, stabilizers and the like are therefore prepared using methods well known in the literature and in polyester production.

Such polyester prepolymers are mainly polymers composed of known polyethylene terephthalate or polyethylene naphthalate (hereinafter PET) or PET structural units, and are preferably at least 70 mol%, preferably 80, in order to undergo solid phase polymerization. Polyesters consisting of at least mol% ethylene terephthalate units are used.

And components which may be contained in the polyester prepolymer, for example, glycols such as isophthalic acid, dimethylisophthalate, orthophthalic acid, dimethylorthophthalate, naphthalenedicarboxylic acid or dimethylnaphthalene dicarboxylate, or other glycol components. It may contain.

However, the present invention is practically applicable to all polyesters capable of solid-phase polymerization, such as PET, polyethylene isophthalate, poly 1,4-cyclohexanedimethyl terephthalate, poly 2,6-ethylene naphthalate, and the like.

The prepolymer powder used in the present invention is obtained by crystallizing the same prepolymer chip at 120 to 180 ° C. for 10 to 300 minutes and then grinding it with a common freeze mill. At this time, the particle size of the powder is preferably 20 to 200 mesh bar, when larger than 20 mesh is less effective in preventing fusion phenomenon and less than 200 mesh problem occurs difficult to handle in the post-process.

In addition, since the intrinsic viscosity of such a prepolymer is generally used at 0.4 to 0.7 dl / g, the present invention also uses a prepolymer having the same intrinsic viscosity.

The amount of prepolymer crystal powder added to the prepolymer is suitably 0.1 to 10% by weight, preferably 0.2 to 5% by weight. If an amount of less than 0.1 weight is added, the fusion cannot be eliminated, and if an amount of more than 10 weight% is added, it is economically undesirable.

The prepolymer and its crystalline powder are mixed for about 5 minutes in a mixer such as a tumbler, which is usually used in the ratios set forth above, and the fusion phenomenon does not appear even when the temperature is raised to the temperature at which the solid phase polymerization proceeds, thereby greatly shortening the solid phase polymerization time.

In addition, since there is no addition of foreign matter other than polyester by this method, polyester after solid phase polymerization also has no residual foreign matter.

The high molecular weight polyester resin produced by the present invention can be used for the manufacture of rubber product reinforcements such as tire cords, polyester resins for making dishes, bottles or sheets, etc. used in microwave ovens and general electric or gas ovens. It can be used for the preparation of.

Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited by the Examples.

The intrinsic viscosity of the high molecular weight polyester resin produced in this example is a value measured at 30 ° C. using a phenol / tetrachloroethane mixed solvent (6: 4 weight ratio) solution.

Example 1

100 parts by weight of dimethyl terephthalate, 70 parts by weight of ethylene glycol, and 0.04 parts by weight of manganese acetate were placed in a reactor equipped with a condenser, heated to a temperature of 220 ° C. in a nitrogen stream, and the theoretical amount of methanol was distilled off. After the addition of parts by weight, the ethylene glycol was removed by heating and heating to 285 ℃. After reacting for 60 minutes, the polymer was discharged into water to make a 4 × 3 × 2 nm prepolymer chip.

The intrinsic viscosity of this prepolymer was 0.61. 5 parts by weight of the prepared chip was crystallized in a convection oven at 120 ℃ and then pulverized by using a liquid nitrogen freeze crusher to obtain a powder having a size between 50 and 100 mesh body.

100 parts by weight of the prepolymer pellet and 1 part by weight of the powder were placed in a rotary vacuum distillation machine, rotated at 20 rpm for 5 minutes, mixed, and heated to 215 ° C. for 30 minutes, and solidified under vacuum at this temperature for 6 hours. At this time, no fusion occurred at elevated temperatures.

Example 2

The same procedure as in Example 1 was carried out except that 0.1 parts by weight of the crystallized prepolymer powder was added. At this time, the fusion phenomenon was that some of the chips were fused to the reactor wall during the elevated temperature, but they were not severe.

Comparative Example 1

The remaining conditions were performed in the same manner as in Example 1 without adding the crystallized prepolymer powder to the polyester prepolymer of Example 1. At this time, the prepolymer chip in the elevated temperature was severely fused between the reactor wall and the chip.

Comparative Example 2

After the prepolymer chip of Example 1 was crystallized at 120 ° C for 3 hours, the remaining conditions were performed in the same manner as in Example 1. The fusion phenomenon did not occur at this time.

The experimental results of the Examples and Comparative Examples are shown in Table 1 below.

TABLE 1

Claims (3)

In preparing the high molecular weight polyester by the solid phase polymerization method after preparing the prepolymer by the polycondensation reaction, 0.1 to 10% by weight of the crystalline powder of the polyester prepolymer is mixed with the polyester prepolymer during solid phase polymerization A method for producing a high molecular weight polyester resin, characterized in that the crystallization. The method of claim 1, wherein the polyester prepolymer is a polymer containing polyethylene terephthalate or at least 80 mol% of ethylene terephthalate structural unit. The method of claim 1, wherein the crystalline powder of the polyester prepolymer has a particle size of 20 to 200 mesh.