JPH03152137A - Polyester porous material, production thereof and solid phase polymerization of polyester - Google Patents

Abstract

PURPOSE:To obtain the subject porous material having a narrow polymerization degree distribution and a large specific surface area at a high solid phase polymerization rate by thermally dissolving a polyalkylene terephthalate prepolymer in a solvent, cooling the solution to solidify the prepolymer, and subsequently removing the solvent. CONSTITUTION:1 pt. of a polyalkylene terephthalate prepolymer is mixed with and thermally dissolved in 0.1-100 pts., preferably 0.3-30 pts., of a solvent (preferably benzophenone, dibenzofuran or diphenyl ether), cooled to solidify the prepolymer, and subsequently subjected to a solvent-removing process to provide the objective porous material having a specific surface area of >=0.1m<2>/g and an intrinsic viscosity of >=0.2.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a polyester porous material having a specific surface area of 0.1 nf/g or more, a method for producing the same, and a solid phase polymerization method for polyester using the polyester porous material.

More specifically, the present invention relates to a method for rapidly producing high-quality polyester useful for fibers, films, and other molded products by surface phase polymerization by utilizing a porous polyester material with a significantly expanded specific surface area. .

(Prior Art) As a method for increasing the degree of polymerization of polyester, a so-called solid phase polymerization method in which polyester particles are reacted under reduced pressure or under an inert gas flow at a temperature below their melting point is well known.

However, in the case of commonly used cylindrical or prismatic bodies (equivalent to particle size 3 to 5) called chips, the solid phase polymerization rate is very slow due to slow diffusion of reaction by-products, etc. economical efficiency cannot be achieved.

In addition, because reaction byproducts diffuse faster on the chip surface than inside the chip, in other words, the polymerization rate is faster, variations in the degree of polymerization occur inside and outside the chip after solid-phase polymerization, and this can lead to quality problems in molded products. has the disadvantage of being inferior.

As a drastic method to solve these low solid phase polymerization rates and wide polymerization degree distribution within chips, attempts have been made to make chips smaller, but due to the toughness of polyester polymers, the crushing cost is high. It takes a lot of time, and there are many process problems such as fusion easily occurring in the solid phase polymerization equipment and troublesome handling during transportation.Furthermore, when pulverized, particle size distribution inevitably occurs. When this is subjected to solid phase polymerization, the solid phase polymerization rate varies depending on the particle size, so the molecular weight distribution of the pulverized product after solid phase polymerization becomes extremely wide.

For these reasons, it is difficult to put the method of particle size reduction into practical use.

(Intelligence to be solved by the invention!l) The present invention provides a polyester porous material necessary for obtaining a high surface phase polymerization rate and a narrow polymerization degree distribution within the particles, which have been difficult to produce up to now, and a method for producing the same. The present invention also provides a method for solid phase polymerization of polyester using the same.

(Means for Solving the Problems) The present inventors focused on the relationship between various factors related to the solid phase polymerization of polyester and the polymerization rate, etc., and conducted various studies focusing on a method for increasing the specific surface area by making the polymer porous. As a result, it was discovered that when a solvent is added to a polymer, heated and dissolved, and then cooled, a solvent that solidifies the solution is selected, and by removing the solvent from the solidified state, it is possible to create porosity.

Furthermore, this porous state is maintained even at the face-phase polymerization temperature, indicating that if this porous polyester material is subjected to face-phase polymerization as a prepolymer, a high polymerization rate and a product with a narrow degree of polymerization distribution can be obtained. I found it. Based on these findings, we have completed the present invention.

That is, the present invention has; (1) a specific surface area of 0.1 m2/g or more and an intrinsic viscosity of 0.1 m2/g or more;
2 or more polyalkylene terephthalate prepolymer porous body;
The solvent is removed after cooling and solidifying, and the specific surface area is 0. In
A method for producing a polyalkylene terephthalate prepolymer having a polyalkylene terephthalate of f/g or more and an intrinsic viscosity of 0.2 or more; It's legal.

Furthermore, the present invention will be specifically explained.

In the present invention, parts refer to parts by weight unless otherwise specified.

The (porous) polyester prepolymer porous body of the present invention needs to have a specific surface area of 0.1 rrf/g or more.

In solid phase polymerization of polyester, it is necessary to expand the specific surface area of the polymer in order to promote the diffusion of reaction byproducts, and by using the porous polyester prepolymer with an expanded specific surface area of the present invention, The surface phase polymerization rate can be increased. If the specific surface area is less than O.1rrf/g, the solid phase polymerization rate will not be improved.The specific surface area is preferably 0.5m/g or more, more preferably lnf/g.
That's all.

The polyester prepolymers of the present invention are porous, and compared to non-porous prepolymers, there is no significant difference in the diffusion rate of by-products inside the polymer and in the outer layer; therefore, the polymerization of the polymer after face-phase polymerization The width of the degree distribution can be narrowed compared to when a non-porous prepolymer is used.

The porosity referred to in the present invention is, for example, as shown in the scanning electron S micrograph of FIG. 1, and is completely different from the surface of a simply pulverized prepolymer as shown in FIG. 2D. .

The intrinsic viscosity of the prepolymer of the present invention needs to be 0.2 or more. When the intrinsic viscosity is less than 0.2, the porous prepolymer is brittle and easily crumbles, making it very difficult to handle it during solid phase polymerization and in the processes before and after the solid phase polymerization.

The intrinsic viscosity referred to here is the value measured at 35°C after dissolving in orthochlorophenol.

The polyester used in the present invention is one that has alkylene terephthalate as the main repeating unit, and has terephthalic acid as the main acid component, and alkylene glycols having 2 to 6 carbon atoms, such as ethylene glycol, trimethylene glycol, tetramethylene glycol, The object is a polyester obtained as a main glycol component of at least one glycol selected from pentamethylene glycol and hexamethylene glycol, particularly preferably ethylene glycol and tetramethylene glycol.

It may also be a polyester in which part of the terephthalic acid component is replaced with another difunctional carboxylic acid component, or a polyester in which part of the glycol component is replaced with the above glycol other than the main component or another diol component. There may be.

Examples of difunctional carboxylic acids other than terephthalic acid used here include isophthalic acid, naphthalene dicarboxylic acid, diphenylcarboxylic acid, diphenoxyethane dicarboxylic acid, β-hydroxyethoxybenzoic acid, P-oxybenzoic acid, 5- Mention may be made of aromatic, aliphatic, and alicyclic difunctional carboxylic acids such as sodium sulfoisophthalic acid, adipic acid, sebacic acid, and 1,4-cyclohexanedicarboxylic acid.

In addition, as diol compounds other than the above glycols,
For example, aliphatic, alicyclic and aromatic diol compounds such as cyclohexane-1,4-dimetatool, neopentyl glycol, bisphenol A1 bisphenol S, polyoxyalkylene glycol and Uniol DA can be mentioned.

In addition, the polyester of the present invention may contain polyfunctional crosslinking agents such as trimethylolpropane, pentaerythritol, glycerin, and trimesic acid, monofunctional terminal terminators such as monomethoxypolyethylene glycol and naphthoic acid, antioxidants, and ultraviolet rays. It may contain additives such as titanium oxide as an absorbent and a matting agent.

The porous polyester prepolymer of the present invention can be produced by the following method. That is, it can be produced by adding 0.1 to 100 parts of a solvent to 1 part of the polyester polymer, heating and melting it, cooling it to solidify it, and then removing the solvent.

The solvent used here may be any solvent as long as it can dissolve the polyester, including hydrocarbons, halogenated hydrocarbons, ethers, ketones, alcohols, phenols, halogenated phenols, amines, nitro Examples include compounds, nitriles, amides, thiols, thioethers, sulfones, sulfoxides, and the like. Particularly preferred are benzophenone, dibenzofuran, diphenyl ether and the like. Further, the solvent may be used alone (or two or more types may be used in combination).

The mixing ratio of the solvent needs to be 0.1 to 100 parts to 1 part of the polyester polymer. If it is less than 0.1 part, a porous body with the desired specific surface area cannot be obtained.
On the other hand, if the amount is more than 100 parts, the porous body becomes very brittle and easily powdered (and handling in the process becomes troublesome).The preferable amount to be melted is 0.3 to 30 parts per part of the polymer.

Methods for dissolving the raw polyester in a solvent include, for example: 1) manufacturing the raw polyester and once turning it into chips and then dissolving it in a separate melting tank; 2) injecting the solvent into the chip that has been remelted with a screw. , method of dissolving in a screw, ■ method of dissolving the polymer by injecting it at the time when the polymer after polymerization is passed through a screw, gear pump, etc. when taking it out from the melt polymerization can, ■ method of dissolving the polymer by injecting it into the polymerization part after melt polymerization. There are several methods, including a method of injecting and dissolving, and a method of polymerizing a prepolymer while a solvent is placed in a polymerization can, and any method may be used.

The melting temperature and melting pressure during melting are appropriately determined within the range in which the polyester can be melted.

Cooling of the solution obtained by melting the polyester is performed as appropriate depending on the amount of the solvent.

The shape of the polymer when solidified can be any desired shape, such as a lobe, a sheet, or a chip formed by cutting them. By using a thin nozzle, it can be solidified into a fibrous form to produce a porous filament.

Next, there are several methods for removing the solvent from the solidified polymer containing the solvent, such as extraction with a solvent, evaporation of the solvent under normal pressure or reduced pressure, and any method may be used.

In addition, by treating the porous prepolymer with a liquid or gas containing additives such as catalysts, stabilizers, antioxidants, and antistatic agents, these additives can be blended into the prepolymer. Alternatively, by adding these additives to the extraction solvent used for porosity formation in advance, porosity can be obtained and the additives can be blended into the prepolymer at the same time.

For example, before molding, various additives and chips are mixed together in a process known as chip blending, but it is difficult to mix them evenly into the polymer, both in terms of uniformity and in terms of time. There's a problem. In particular, the difficulty increases as the size of the polymer particles (chips) increases.

However, when this porous polymer is used, it is possible to uniformly and quickly blend it into the polymer, regardless of the size of the polymer particles (chips), and by utilizing this, higher quality pores can be created. It is possible to economically obtain a flexible molded product.

Furthermore, before solid phase polymerization, this porous polyester prepolymer can be subjected to a treatment such as annealing to increase its melting point and crystallinity.

The porous polyester prepolymer thus obtained is solid-phase polymerized by a conventional method.

That is, solid phase polymerization is performed under reduced pressure or under inert gas flow. Furthermore, a method of flowing a small amount of inert gas under reduced pressure can also be used.

When performing solid phase polymerization under reduced pressure, the higher the degree of reduced pressure, the higher the polymerization rate.
The pressure is set to 0 Torr or less, preferably 2 Torr or less, and more preferably ITorr or less.

Further, when an inert gas is used, nitrogen, carbon dioxide, argon, etc. can be used as the inert gas.

The solid phase polymerization temperature must be below the melting point of the porous polyester prepolymer so that the porous polyester prepolymers do not fuse together. During solid phase polymerization, the melting point of polyester is gradually increased by annealing, so gradually increasing the surface phase polymerization temperature is also an effective method for obtaining a high polymerization rate. Preferably, a polymerization temperature of 200 to 270°C, more preferably 220 to 260°C is employed.

The present invention will be explained by the following Examples, but the present invention is not limited to these Examples.
It was measured by the method described below, and unless otherwise specified, parts represent parts by weight.

(2) Reduced viscosity: The polymer was dissolved in O-chlorophenol at a concentration of 1 g/a, and the viscosity was measured at 35°C using an Ubbelohde viscosity needle.

■Specific surface area: Using fracture accusorb manufactured by Shimadzu, N,
was physically adsorbed and measured.

Example 1 100 parts of dimethyl terephthalate, 6 parts of ethylene glycol
8 parts and 0.05 part of manganese acetate under nitrogen atmosphere at 140~
The mixture was heated to 220°C, and by-produced methanol was distilled off over 2.5 hours. Add 0.0% trimethyl phosphate to this.
After adding 0.03 parts and 0.05 parts of antimony oxide, 295
The temperature was raised to 0.degree. C., and the mixture was reacted for 2 hours while ethylene glycol was distilled off under a reduced pressure of 0.5 degrees Hg. The obtained polymer had a reduced viscosity of 0.69.

The polymer thus obtained was dried by flowing dry air at 150° C. for 4 hours.

2 parts of diphenyl ether was added to 1 part of this dried polymer, the temperature was raised to 250°C, and a homogeneous solution was obtained after 10 minutes. After cooling and solidifying this, the solid was taken out and cut into chips with a particle size of 3 to 5 grains.

Next, 5 parts of acetone was added to 1 part of this solvent-containing solid, and the mixture was stirred for 30 minutes to extract the solvent, and then the solvent-containing acetone was discharged. This operation was repeated five times to almost completely remove the solvent from the polymer.

The specific surface area of this porous polymer is 114rrf/
It was g. Further, the reduced viscosity was 0.69, and the shape of the porous polyester was the same as before extraction.

This porous polyester was reacted as a prepolymer in a solid phase polymerization machine at 0.3 Torr and 250° C. for 1 hour.

The reduced viscosity after the reaction was 1.60.

The reduced viscosity of the outer surface and inside of the chip is 1.
There was almost no difference between 61 and 1.58.

No fusion phenomenon was observed between the chips or between the chips and the wall inside the solid phase polymerization machine.

Comparative Example 1 A polyester polymer with a reduced viscosity of 0°69 made in the same manner as in Example 1 was cut into chips with a particle size of 3 to 5 mm without making it porous, and subjected to the same face phase polymerization conditions as in Example 1. Solid phase polymerization was performed.

The average viscosity of the chip after solid phase polymerization is 0.76,
Compared to the porous prepolymer used in Example 1, the solid state polymerization rate is significantly lower.

In addition, the reduced viscosity on the outer surface and inside of the chip is each 0.7.
There was a big difference between 0 and 0.85.

Examples 2-3 The same operation as in Example 1 was performed except that the ratio of polymer to solvent was changed as shown in Table 1. In either case, the shape of the chip did not collapse during the process including solid phase polymerization, and no fusion occurred.

The reduced viscosity on the outer surface and inside of the chip after solid-state polymerization was almost the same.

The specific surface area in Table 1 was 105rrf/g. The average reduced viscosity after solid phase polymerization was 1.55, and there was almost no difference in reduced viscosity between the outer surface and the inside of the chip.

Comparative Example 2 Reduced viscosity 0.6 melt polymerized in the same manner as Example 1
The polymer No. 9 was crushed and classified to obtain a polyester powder having a particle size of 1.0 and a specific surface area of 0.007 m/g. This was subjected to solid phase polymerization under the same conditions as in Example 1.

The viscosity after solid phase polymerization was 1.15, which is inferior to the porous polyester chip of the present invention.Moreover, powder fusion occurs in the surface phase polymerization machine, which increases the effort of cleaning the inside of the surface phase polymerization machine, and makes handling difficult. was difficult.

Example 4 The polymer obtained by performing the same operation as in Example 1 except that the type of solvent was changed from diphenyl ether to benzophenone retained the chip shape. (Effects of the invention) Polyester porous bodies were manufactured according to the present invention. However, when it is used for solid phase polymerization, it is possible to increase the degree of polymerization at a faster surface phase polymerization rate that could not be obtained conventionally, and the degree of polymerization distribution of the polymer obtained by solid phase polymerization can be made narrower than before. , it is possible to economically obtain high quality polyester with a high degree of polymerization in a short time.

[Brief explanation of the drawing]

The drawings used in the present invention are all photographs taken with a scanning electron microscope at a magnification of 1,000 times. FIG. 1 is a scanning electron micrograph (1°000x magnification) of the surface of the polymer porous body produced in Example 1 of the present invention. Figure 2 shows the reduced viscosity 0. Scanning electron micrograph (1,0
00 times). (1 other person)

Claims (4)

[Claims] (1) A polyalkylene terephthalate prepolymer porous body having a specific surface area of 0.1 m^2/g or more and an intrinsic viscosity of 0.2 or more. (2) Adding 0.1 to 100 parts of a solvent to 1 part of polyalkylene terephthalate prepolymer, heating and dissolving, cooling and solidifying, and then removing the solvent,
Specific surface area is 0.1m^2/g or more, and intrinsic viscosity is 0.2
The method for producing the polyalkylene terephthalate prepolymer porous body described above. (3) A method for solid-state polymerization of polyester, characterized in that the porous prepolymer according to claim (1) is used in the solid-state polymerization of polyalkylene terephthalate. (4) A polyalkylene terephthalate polymer porous body having an increased degree of polymerization and having a specific surface area of 0.1 m^2/g or more, produced by the solid phase polymerization method according to claim (3).