KR960007610B1 - Method for manufacturing high molecule polyester - Google Patents

Abstract

The high molecular weight polyester is prepared by making prepolymer of polyester containing more than 70% ethylene terephthalate; adding a foaming agent by 0.01-30wt.% with respect to the amount of prepolymer, and making pellets of prepolymer with a density of 0.3-1.332g/cm2 and an intrinsic viscosity of 0.3-0.9dl/g by extrusion molding; and polymerizing pellets in a solid state. The method gives high molecular weight polyester, abundant high Mw polyester can be obtained for short time.

Description

Process for producing high molecular weight polyester resin

The present invention relates to a method for producing a high molecular weight polyester resin, and more particularly, by adding a blowing agent to the prepolymer during the production of a high molecular weight polyester resin and then extruding it to solid-phase polymerization of a large amount of high molecular weight in a short time. It relates to a method for producing a polyester resin.

Currently, high molecular weight polyester resins are used as polyethylene terephthalate (PET) bottle resins, tire cords, resins for various containers and microwave ovens, and resins for sheets.

It is well known that high molecular weight resins having an intrinsic viscosity of more than 0.7 dl / g are usually produced by solid phase polymerization. However, when preparing a high molecular weight polyester by solid phase polymerization, a long reaction time is required because the solid phase polymerization by-product must be diffused and discharged through the polymer solid. Moreover, as the solid phase polymerization of the polyester polymer proceeds, the diffusion rate of water and glycol, which are polymerization by-products, is further disturbed and the reaction rate is further reduced.

Therefore, in order to achieve high molecular weight within a short time, the prepolymer should be made to facilitate the diffusion of polymerization by-products, and in general, as the specific surface area of the prepolymer is increased, the reaction rate of the solid phase polymerization is increased. In this regard, British Patent No. 1,167,004 In order to increase the specific surface area, a method of solidifying a polyester prepolymer into a powder form is disclosed. However, this method requires a lot of time and energy to make the prepolymer into a powder form, such as extrusion, injection, etc. It is not preferable because it is difficult to handle even in the subsequent step.

On the other hand, US Patent No. 4.891.195 discloses a process for dissolving a polyester prepolymer in an organic solvent and then making a porous fiber mass from the solution, and then compressing it to form a porous fill and solid-phase polymerization. However, this method also has a disadvantage in that the process of dissolving or recompressing in an organic solvent is not suitable for commercial scale.

In addition, Japanese Patent Publication No. 49-25437 discloses a method of increasing the specific surface area by making a cross section of a chip other than * when melt-polymerizing the shape of a polyester prepolymer and then extruding it. Since the effect of increasing the surface area is large, there is a problem that the rate of the solid-state polymerization reaction is not greatly increased.

Therefore. The inventors of the present invention, in the production of high molecular weight polyester by the solid phase polymerization method, by foaming the polyester prepolymer obtained by melt polycondensation in a known method to facilitate volcanic by-products during the solid phase polymerization reaction, it is remarkable compared to the conventional It is possible to produce a high molecular weight polyester resin at a high speed

Knowing the facts completed the present invention.

Accordingly, an object of the present invention is to provide an improved method for producing a high molecular weight polyester resin by adding a foaming agent to a prepolymer and then extruding it to solid phase polymerization.

Hereinafter, the present invention will be described in detail.

The present invention is to prepare a polyester prepolymer by a polycondensation reaction, and then to prepare a high molecular weight polyester resin by solid phase polymerization, wherein the polyester prepolymer is prepared in units of 70 mol% or more ethylene terephthalate, and the preliminary The foaming agent is added in an amount of 0.01-30% by weight based on the total amount of the polymer, followed by extrusion molding to form expanded polyester prepolymer pellets, followed by solid phase polymerization to prepare a high molecular weight polyester resin.

Referring to the present invention in more detail as follows.

The present invention relates to a method for producing a high molecular weight polyester resin at a remarkably high speed. The polyester prepolymer used in the present invention can be produced by various methods, but is prepared by conventional melt polymerization. Therefore, conventional reaction temperatures, catalyst contents, stabilizers and the like are prepared using methods well known in the literature and polyester prepolymer preparation.

These polyester prepolymers are mainly polymers composed of known polyethylene terephthalate (PET) or PET structural units, and the polyester prepolymers are composed of ethylene terephthalate units in addition to 70 mol% or more of which crystallization may occur for solid phase polymerization. It should be manufactured as.

At this time. If the ethylene terephthalate unit is less than 70 mol%, the crystallization rate is greatly lowered and the solid phase polymerization reaction cannot be performed.

In addition, components that may be contained in the polyester prepolymer include, for example, dicarboxylic acids or esters thereof such as isophthalic acid, dimethylisophthalate, orthophthalic acid, dimethylorthophthalate, naphthalenedicarboxylic acid, dimethylnaphthalenedicarboxylate and the like. Compounds and glycols such as 1,4-butanediol, neopentylglycol, 1,4-cyclohexanedimethanol, propyleneglycol, and the like, and other glycol components.

However, in the present invention, the present invention can be applied to any polymer capable of solid-phase polymerization, such as PET, polyethylene isophthalate, polybutylene terephthalate, polycyclohexanedimatic terephthalate, polyethylene naphthalate and the like.

The polyester prepolymer used in the present invention is to make a polyester foam through the extrusion process together with the blowing agent after the melt polycondensation reaction. The blowing agent used here is a liquid that can be easily vaporized or a compound that generates gas by pyrolysis, and any of those used in the production of thermoplastic polyester resins can be used, for example inert gas, saturated hydrocarbon, aromatic hydrocarbon, halogenated Hydrocarbons, ethers or ketones. Specifically, carbon dioxide, nitrogen, methane, ethane, propane, butane. Pentane, hexane, methylpentane, dimethylbutane, cyclopentane, cyclohexane, methylcyclopentane. Dichlorotrifluoroethane, monochlorodifluoroethane, tetrafluoroethane, dimethylether, 2-ethoxybetane. Acetone, methyl ethyl ketone, acetyl acetone, dichlorotetrafluoroethane, monochlorotetrafluoroethane, dichloromonofluoro ethane, difluoroethane and the like can be used.

In the present invention, the blowing agent is preferably added to 0.01 to 30% by weight based on the total amount of the polyester resin prepolymer. If the foaming agent is less than 0.01% by weight, the foaming effect is not sufficiently exhibited. If the foaming agent is more than 30% by weight, the density of the foam is so low that the productivity of the solid phase polymerization is lowered.

The blowing agent is to increase the specific surface area through the extrusion process to facilitate the discharge of by-products during the solid phase polymerization reaction, thereby increasing the solid phase polymerization rate due to such blowing agents.

In making foams of polyester prepolymers using such blowing agents, stabilizers, pigments, fillers, foaming nucleating agents, antistatic agents and the like may be added as necessary to improve the physical or chemical properties of the polyester resins. Compounds with one or more anhydride functionalities can be added to homogenize the cells of the ester foam and prevent color change.

In addition, the extruder that can be used in the present invention may be a single screw extruder, multi-screw extruder and the like. The extruded foamed polyester resin is pelleted in a pelletizing apparatus through a cooling bath immediately after exiting the extrusion die. The polyester foamed prepolymer thus obtained has a density of 0.3 to 1.332 g / cm 3 and an intrinsic viscosity of 0.3 to 0.9 dl / g, wherein when the density is less than 0.3, the solid-phase polymerization productivity (which can be produced per hour in a reactor of the same size) If the amount can be too small and exceeds 1.332 g / cm 3, it is not possible to expect a solid phase polymerization rate increase due to foaming.

In addition, when the intrinsic viscosity exceeds 0.9, the melt polymerization degree is late, and there is no economy, and if it is less than 0.3, the solid phase polymerization time is long and there is no economy.

If foam polyester prepolymer pellets are made by the above method, they can be optionally converted to higher crystallinity before solid phase polymerization to raise the adhesion temperature of the prepolymer chip. This is done to reduce the likelihood that the prepolymer chip will stick to form a solid mass.

In addition, it is preferable that the surface crystallinity of the polyester prepolymer to be solid-phase polymerized is at least 20% or more to prevent fusion of the prepolymer chip. Typically, the polyester prepolymer chip is used at 110 ° C to 200 ° C for 5 minutes to 300 minutes. By heating, the crystallinity can be made 20% or more.

On the other hand, the polyester prepolymer according to the present invention can be subjected to solid phase polymerization by a batch or continuous method, the solid phase polymerization temperature is generally about 1 ℃ to 60 ℃ lower than the adhesion temperature of the polyester prepolymer used. For example, polyethylene terephthalate is solid phase polymerized at a temperature of about 190 ° C. to 255 ° C., in most cases polyethylene terephthalate is solid phase polymerized at a temperature of 200 ° C. to 245 ° C. The optimum solid state polymerization temperature varies slightly depending on the composition and molecular weight of the prepolymer and may be increased as the reaction proceeds.

This solid phase polymerization is carried out under vacuum or under a stream of inert gas. Inert gas may be nitrogen, carbon dioxide, helium, argon, neon, etc., and the amount of inert gas is usually 0.05 to 10 l per kg of polyester prepolymer. Is suitable.

In addition, in order to raise the molecular weight of the polyester prepolymer to the desired molecular weight can be obtained by a solid phase polymerization reaction at a suitable temperature for a suitable time, in order to obtain an ultra high molecular weight polyester must be subjected to a solid phase polymerization reaction for a long polymerization time. . Here, the solid-state polymerization reaction time performed by the present invention is mostly in the range of about 30 minutes to 30 hours.

As described above, in the case of solid-phase polymerization of the polyester prepolymer according to the present invention, a polyester resin having a high molecular weight of any desired molecular weight can be prepared within a faster time than a conventional solid phase polymerization method, and has an intrinsic viscosity of 1.2d1 / g or more. A polyester resin having an ultra high molecular weight can be produced. Therefore, the present invention is a useful method that can easily prepare the ultra-high molecular weight vonriester resin as described above, without the difficult process of wall painting, such as polyester resins having an intrinsic viscosity of more than 2.0 dl / g can also be produced.

The high molecular weight polyester resin produced by the present invention can be used for the production of reinforcing agents (for example, tire cords) for rubber products, and can be used for the manufacture of dishes used in battery ranges and general electric or gas ovens.

It can also be used to make polyester bottles by extrusion blow, and can be effectively used for the fabrication of monofilaments for kvass used in papermaking.

In addition, all of the following polyester solid-state polymerizations requiring high intrinsic viscosity can be used in the process according to the present invention, i.e. bottle-free polyester resins, resins for fibers requiring high intrinsic viscosity, and for making sheets or films. The method according to the invention can be usefully used in the preparation of the resin.

Below. The present invention will be described in detail based on Examples as follows. The present invention is not limited by the examples.

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

Example 1

100 parts by weight of terephthaline, 43 parts by weight of ethylene glycol slurry of terephthalic acid, ethylene glycol and antimony oxide, trimethyl phosphate and cobalt acetate were dried in an intrinsic viscosity 0.60 dl / g PET prepolymer for 4 hours in a hot air dryer at 160 ° C. Next, 500 g of dry PET prepolymer was placed in a plastic coder type 25 mm single screw extruder. In addition, by injecting 0.1 parts by weight of isopantanol as a blowing agent into the molten polymer was extruded to make a foamed PET prepolymer. The process conditions of the extruder were as follows.

Barrel 1: 270 ~ 28O ℃

Barrel 2: 275 ~ 285 ℃

Baron 3: 275 ~ 285 ℃

Extruder Head: 270 ~ 28O ℃

RPM: 50rpm

The foamed PET prepolymer was crystallized and dried at 140 ° C. for 4 hours, and then sublimed to 220 ° C. for a solid phase polymerization reaction for 4 hours while maintaining a vacuum of 0.2 Torr. The intrinsic viscosity of the PET resin after the solid state polymerization was 0.91 d1 / g.

Example 2

The same procedure as in Example 1 was carried out except that 1.0 parts by weight of isopentanol was used. The intrinsic viscosity of the solid state polymerized PET was 1.01 dl / g.

Example 3

It carried out similarly to Example 1 except having made isopentane 2.0 weight part. The intrinsic viscosity of the solid state polymerized PET was 1.93 dl / g.

Example 4

The same procedure as in Example 1 was carried out except that the solid phase polymerization time was 8 hours. The inherent viscosity of the solid state polymerized PET was 1.18 d1 / g.

Example 5

The same procedure as in Example 1 was carried out except that the solid phase polymerization time was 8 hours. The inherent viscosity of the solid state polymerized PET was 1.356 dl / g.

Example 6

The same procedure as in Example 1 was carried out except that the solid phase polymerization time was 8 hours. The intrinsic viscosity of the solid state polymerized PET was 1.38 dl / g.

Comparative Example 1

The same procedure as in Example 1 was carried out except that the dried PET prepolymer was extruded without the blowing agent.

The intrinsic viscosity of the solid state polymerized PET was 0.72 dl / g.

Comparative Example 2

The same procedure as in Comparative Example 1 was carried out except that the solid phase polymerization time was 8 hours. The intrinsic viscosity of the solid state polymerized PET was 0.83 d1 / g.

Summarizing the contents of Examples 1 to 6 and Comparative Examples 1 to 2 are shown in Table 1 below.

As can be seen in Table 1, in Examples 1 to 6 manufactured according to the method of the present invention, the solid phase polymerization time was shortened by about one-half as compared to the conventional Comparative Examples 1 and 2, and the solid polymer The intrinsic viscosity of is also improved by about 20% ~ 50%. Therefore, when produced by the method of the present invention, it is possible to produce a high molecular weight polyester resin at a remarkably high speed, and as a result, a large amount of resin can be produced in a short time.

Claims (3)

In preparing the polyester prepolymer by the polycondensation reaction and then preparing the high molecular weight polyester resin by the solid phase polymerization method, the polyester prepolymer is prepared in units of 70 mol% or more of ethylene terephthalate, and the entire prepolymer The foaming agent was added in an amount of 0.01 to 30% by weight, followed by extrusion molding to prepare expanded polyester prepolymer pellets having a density of 0.3 to 1.332 g / cm 3 and an intrinsic viscosity of 0.3 to 0.9 dl / g, followed by solid phase polymerization. A method for producing a high molecular weight polyester resin, characterized in that the production. The method of claim 1, wherein the polyester prepolymer is selected from polyethylene naphthalate, polybutylene terephthalate and polycyclohexanedimethyl terephthalate. The method of claim 1, wherein the blowing agent is carbon dioxide, nitrogen, methane, ethane, propane, butane, pentane, hexane, methylpentane, dimethylbutane, cyclopentane, cyclohexane, ethylcyclopentane, dichlorotrifluoroethane, mono Chlorodifluoroethane, tetrafluoroethane, dimethyl ether, 2-ethoxyethane, acetone, methyl ethyl ketone, acetylacetone, dichlorotetrafluoroethane, monochlorotetrafluoroethane, dichloromonofluoroethane and difluoro Method for producing a high molecular weight polyester resin, characterized in that selected from roethane.