JP2718186B2 - Method for producing particle-containing polyester - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to an improved method for producing polyester for producing films or fibers.
More specifically, the present invention relates to a method for producing a linear polyester in which alumina particles are uniformly dispersed in a polyester, a coarse agglomerated particle or the like is not contained, and a film or fiber excellent in abrasion resistance can be produced.

[Prior art] Polyester, especially polyethylene terephthalate,
Due to its excellent mechanical properties, heat resistance, light resistance and electrical insulation, it is widely used as films, fibers and other molded products.

However, the polyester itself is reduced in productivity due to poor process passability at the time of obtaining a molded product. For example, when a biaxially stretched film is formed, its value is impaired due to poor slipperiness of the film. Have a problem.

Conventionally, in order to solve such a problem, the polyester contains inactive inorganic particles such as calcium carbonate, titanium oxide, and silicon oxide to form irregularities on the surface of the molded article, thereby improving processability during molding. And methods for imparting surface lubricity to molded articles are known. For example, Japanese Unexamined Patent Publication No.
No. 1 discloses a method in which when alumina obtained by a pyrolysis method is used, a method of mixing and adding the same with silica obtained by a pyrolysis method is also disclosed. As described above, in such a method, secondary agglomerated particles are formed, and there is no effect of eliminating the coarse projections, which is the object of the present invention, and as a result, the obtained film is inferior in abrasion resistance.

[Problems to be Solved by the Invention] The inventors of the present invention have a problem of the prior art that the dispersion of the added alumina particles is not sufficient, so that a large number of coarse particles are contained, and such coarse particles are contained. Is effective for surface smoothness, but when the polyester is formed into a film, film breakage and increase in filtration pressure due to the coarse particles occur frequently, and in a formed film,
As a result of intensive studies on the problem of fish eye and drop out, the present invention has been achieved.

That is, an object of the present invention relates to a method for producing a polyester having excellent surface properties and excellent abrasion resistance without coarse projections caused by secondary aggregated particles when formed into a molded product, particularly a film. is there. More specifically, the present invention relates to a method for producing a polyester having very small surface irregularities when formed into a film and free from defects such as film tearing, drop-out, and fish eyes.

[Means for Solving the Problems] The object of the present invention described above is to prepare a polyester before the polymerization is completed.
(A) a phosphorus compound and an alkali metal compound, or (B)
0.01 to 40 parts by weight (based on 100 parts by weight of alumina) of at least one of the alkali metal salts of the phosphorus compound;
(C) 0.01 to 3.0 particles of at least one alumina particle selected from δ-type, η-type and γ-type having an average particle size of 5 μm to 5000 μm.
Parts by weight (based on 100 parts by weight of the polyester) are added in the form of a slurry by high-speed stirring, and then the polymerization is completed.

In the present invention, the phosphorus compound (A) is pyrophosphoric acid,
Examples thereof include metaphosphoric acid, phosphoric acid, phosphorous acid, and hypophosphorous acid. Of these, pyrophosphoric acid, metaphosphoric acid, and phosphoric acid are preferable. These compounds may be added alone,
Two or more types may be used in combination. Alkali metal compounds include hydroxides of sodium, potassium and lithium, acetates and the like, among which sodium hydroxide, sodium acetate, potassium hydroxide and potassium acetate are preferable, and sodium acetate and potassium acetate are more preferable. Is preferred.

The alkali metal compound of the phosphorus compound (B) is sodium pyrophosphate, potassium pyrophosphate, sodium phosphate, potassium phosphate, sodium hexametaphosphate, etc., among which sodium pyrophosphate, potassium pyrophosphate, sodium hexametaphosphate, etc. Is preferred. These compounds may be used alone, or two or more of these compounds may be used in combination.

And (A) a phosphorus compound and an alkali metal compound,
(B) An alkali metal compound of a phosphorus compound may be used in combination.

These (A) the phosphorus compound and the alkali metal compound, or (B) the alkali metal compound of the phosphorus compound,
To be used as a dispersant for alumina particles, it must be added to the same slurry as the alumina particles. Water, methanol, ethylene glycol, 1,
Examples thereof include 4-butanediol, neopentyl glycol, propylene glycol, and diethylene glycol, and it is preferable to use glycol used as a raw material and a copolymer component of polyester. Further, the slurry may contain a polyester catalyst, a heat stabilizer, an antioxidant, an ultraviolet absorber and waxes.

It is more preferable that the slurry containing alumina particles is added to the reaction system after pretreatment such as mechanical dispersion by ultrasonic waves or high-speed stirring. Also, even if the slurry is filtered by an ordinary method to obtain a target particle size distribution,
Classification with a decanter is also acceptable. The timing of addition may be any time between the charging of the starting materials and the completion of the polymerization of the linear polyester, but is preferably after esterification or after transesterification to the initial stage of polycondensation.

In the present invention, (A) the phosphorus compound and the alkali metal compound or (B) the alkali metal compound of the phosphorus compound is added in an amount of (A) or (B) per 100 parts by weight of alumina.
Must be 0.01 to 40 parts by weight. Preferably 0.05 to
The amount is 20 parts by weight, more preferably 0.1 to 10 parts by weight. If the amount is more than 40 parts by weight, the polymerization time is delayed and the intrinsic viscosity of the polymer is undesirably reduced. Conversely, if the amount is less than 0.01 part by weight, the dispersing effect of the intended alumina becomes insufficient, coarse particles are present in the polymer, and the film is broken when formed into a film.
Dropping out, fish eye, etc., and breakage of the fiber when it is formed are undesirable.

Further, in order to prevent polymer deterioration due to the presence of a large amount of free metal ions, delay of polymerization time due to excessive residual phosphorus amount or reduction of intrinsic viscosity, the ratio of the phosphorus compound and the alkali metal compound in (A) is determined by The molar ratio of (compound) / (alkali metal compound) is preferably 0.5 or more and 4.0 or less.

Alumina particles in the present invention are crystalline alumina hydrates such as gibbsite, bayerite, Nordstrandite, boehmite, diaspore, todite, and amorphous alumina hydrates such as amorphous gel, boehmite gel, and bayerite gel Means intermediate activated alumina such as ρ, η, γ, χ, κ, δ, θ, and α-type alumina, and among them, δ-type, η-type, and γ-type are preferable.

The primary particle average diameter of the alumina particles in the present invention is 5 m
It is necessary to be set to μ to 5000 mμ. Preferably 5mμ ~ 3000m
μ, and more preferably 5 μm to 2000 μm. Five
If it exceeds 000 mμ, the surface flatness when formed into a film or fiber is impaired, and the abrasion resistance is reduced. In the case of a film, dropout is caused. Conversely, if the particle size is less than 5 μm, agglomeration occurs partially in the polyester, which is equivalent to the presence of coarse particles.In the case of a film, dropout occurs. It is not preferable.

By particle size according to the invention is meant the "equivalent spherical diameter" of the particles at a point of 50% by weight of the total particles. Here, the “equivalent spherical diameter” means the diameter of a virtual sphere having the same volume as the target particle, and can be measured by a known method such as a normal sedimentation method or direct observation with an electron microscope.

The particle size distribution is preferably sharp, not containing particles of 10μ or more, in order to prevent film breakage and dropout, and the volume content of particles of 2.0μ or more is 30%.
It is more preferable that the following is satisfied.

The amount of the alumina particles added to the polyester in the invention is 0.01 to 100 parts by weight of the polyester.
Must be 3.0 parts by weight. Preferably, it is 0.05 to 2.0 parts by weight. If the amount exceeds 3.0 parts by weight, the surface flatness when formed into a film or a fiber is impaired, and as a result, abrasion resistance is undesirably reduced. If the addition amount is less than 0.01 part by weight, the surface irregularities of the film and fiber are small, and sufficient abrasion resistance cannot be obtained, which is not preferable.

The slurry containing alumina particles in the present invention can be added to a known polyester. As the polyester, any polyester can be used as long as it can form a film or a fiber.For example, polyethylene terephthalate, polytetramethylene terephthalate, polycyclohexylene dimethylene terephthalate, polyethylene-2,6-naphthalenedicarboxylate, polyethylene -1,2-bis (2-chlorophenoxy) ethane-4,4 '
-Dicarboxylate and the like are preferred, and polyethylene terephthalate and polyethylene-2,6-naphthalenedicarboxylate are particularly preferred.

In these polyesters, adipic acid, isophthalic acid, sebacic acid, phthalic acid, 4,4 ′
Dicarboxylic acids such as diphenyldicarboxylic acid and ester-forming derivatives thereof, dioxy compounds such as polyethylene glycol, diethylene glycol, hexamethylene glycol, neopentyl glycol and polypropylene glycol, and oxycarboxylic acids such as p- (β-oxyethoxy) benzoic acid Acids and their ester-forming derivatives may be copolymerized.

The polyester in the present invention can be synthesized by a known method. For example, in the case of polyethylene terephthalate, the polyester can be obtained by reacting terephthalic acid or dimethyl terephthalate with ethylene glycol to form a low polymer, followed by polycondensation. In this case, a metal compound known as a transesterification catalyst, for example, acetates, oxalates, halides, hydroxides such as calcium, magnesium, lithium, manganese, zinc, and cobalt, and an antimony compound as a polymerization catalyst , A titanium compound, a germanium compound, or the like may be used. In addition to the above (A), known phosphorus compounds such as phosphoric acid, phosphorous acid, phosphonic acid, and lower alkyl esters and phenyl esters thereof may be added during the reaction as a coloring inhibitor.

In addition, when the polyester thus produced is used to form a film, for example, it can be produced in accordance with a conventionally accumulated method for producing a biaxially stretched film.
For example, it is produced by melt-forming a polyester containing alumina particles into an amorphous unstretched film, and then stretching the unstretched film biaxially, heat-setting, and, if necessary, relaxation heat treatment. Is done. At this time, since the film surface characteristics vary depending on the shape, particle size, amount, etc. of the alumina particles and the stretching conditions, they are appropriately selected from conventional stretching conditions. In addition, voids, densities, heat shrinkage ratios, and the like also change depending on the temperature, magnification, speed, and the like during stretching and heat treatment. Therefore, conditions that simultaneously satisfy these characteristics are determined. For example, the stretching temperature is such that the first-stage stretching temperature (for example, longitudinal stretching temperature: T ₁ ) is in the range of (Tg−10) to (Tg + 45) ° C. (however, Tg:
From the glass transition temperature of the polyester), the second-stage stretching temperature (for example, the transverse stretching temperature: T ₂ ) is from (T ₁ −15) to (T ₁ +4).
0) It is good to select from the range of ° C. The stretching ratio is preferably selected from a range where the stretching ratio in the uniaxial direction is 2.5 or more, particularly 3 or more, and the area magnification is 8 or more, especially 10 or more. Furthermore, the heat setting temperature is 180-250 ° C,
It is good to select from the range of 200 to 230 ° C. This makes it possible to obtain a biaxially oriented polyester film having excellent sliding properties and excellent abrasion resistance.

The biaxially oriented polyester film is preferably used for a base film of a magnetic recording medium, especially for a magnetic tape, but is not limited to this. Can also be widely applied.

Further, not only such a film but also a yarn having excellent surface characteristics can be obtained even if it is formed into a fiber.

[Examples] Hereinafter, the present invention will be described in more detail with reference to Examples.
In addition, the physical property in an Example was measured as follows.

A. Average particle diameter of primary particles The inorganic particle-containing slurry was measured by a usual liquid phase sedimentation method.

B. Fish eye of the film Observation of the film under a polarizing microscope, the presence of agglomerates of primary particles of 10μ or more in places where polarized light is present is referred to as fish eye, and the number per 1 cm ² is represented by 1 / cm ² or less was regarded as good.

C. Abrasion resistance of the film
The amount of white powder generated during high-speed running by rubbing against a metal guide rail installed in the middle was measured, and was indicated by the following ranking.

 Rank A: White powder hardly occurs.

 B: A small amount of white powder is generated.

 C: White powder adheres to the film contact surface side of the metal guide rail as a whole.

Example 1 90 parts of ethylene glycol and 0.2 parts of sodium pyrophosphate were added to 10 parts of γ-type alumina particles having an average primary particle diameter of 30 mμ, and the mixture was stirred at high speed and filtered with a 5μ filter to form a slurry.

Next, 100 parts of dimethyl terephthalate, 70 parts of ethylene glycol, and 0.06 part of magnesium acetate were charged, and a transesterification reaction was performed in a usual manner.After that, 0.03 part of trimethyl phosphate was added, and 30 parts of the above slurry was added. Perform a normal polycondensation reaction, intrinsic viscosity 0.615,
A polymer having a softening point of 260.8 ° C. was obtained.

Using the obtained polyester composition, a draw ratio of 3.3
The film was molded into a biaxially stretched film having a thickness of 10 μm under the conditions of a heat treatment temperature of 215 ° C. and a heat treatment time of 5 seconds. The resulting film had 0 fish eyes / cm ² , little adhesion of white powder, and was found to have uniform and fine surface irregularities and excellent abrasion resistance sufficient for magnetic tape applications. .

Examples 2 to 6 As shown in Table 1, alumina particle species, particle addition amount,
A polyester composition and a biaxially stretched film were obtained in the same manner as in Example 1, except that the average particle diameter and the type and amount of the dispersant were changed. The obtained film had the film properties as shown in Table 1, and had sufficiently fine uniform and fine surface irregularities and abrasion resistance for magnetic tape use.

Example 7 90 parts of ethylene glycol, 0.3 parts of pyrophosphoric acid, and 0.33 parts of potassium acetate were added to 10 parts of γ-type alumina particles having an average diameter of primary particles of 20 mμ, and the mixture was stirred at high speed and filtered with a 5 μ filter to form a slurry. Was.

Using this slurry, a polyester composition and a biaxially stretched film were obtained in the same manner as in Example 1. As shown in Table 1, the obtained film had sufficiently satisfactory uniform fine surface irregularities and abrasion resistance as a magnetic tape.

Comparative Examples 1 to 5 A polyester composition and a biaxially stretched film were obtained in the same manner as in Example 1 except that the average particle diameter and the amount added, and the type and amount of the dispersant were changed.

Table 2 shows the fish eye and abrasion resistance of the obtained film. As is clear from this table, the obtained biaxially stretched film does not have uniform and fine surface irregularities, has many fish eyes and poor abrasion resistance, and has poor performance for magnetic tape applications. It was not enough.

In addition, when the amount of the added phosphorus compound was large, the polymerization time was delayed, or the film was broken during film formation, so that a stable product could not be obtained.

[Effects of the Invention] As described above, the present invention uniformly disperses fine alumina particles in polyester, so that when formed into a molded product, the molded product has uniform fine surface irregularities and has a high abrasion resistance. Excellent molded products can be made.

Therefore, the composition of the present invention is effective in the field of films, fibers and other engineering plastics, but can be preferably used particularly in the field of films.

Claims (1)

(57) [Claims] When producing a polyester, 0.01 to 40 parts by weight of at least one of (A) a phosphorus compound and an alkali metal compound or (B) an alkali metal salt of a phosphorus compound before polymerization is completed. (C with respect to 100 parts by weight of alumina) and (C) at least one alumina particle selected from δ-type, η-type and γ-type having an average particle size of 5 μm to 5000 μm.
A method for producing a particle-containing polyester, comprising adding and slurrying 01 to 3.0 parts by weight (based on 100 parts by weight of polyester) by high-speed stirring and then completing the polymerization.