JPH0753795B2 - Method for producing ethylene glycol slurry for polyester addition - Google Patents

Description

TECHNICAL FIELD The present invention relates to an aluminum glycol particle-containing ethylene glycol slurry having excellent dispersibility after addition of polyester.

[Problems to be Solved by Conventional Techniques and Inventions]

Polyester films, especially biaxially oriented polyester films, have excellent physical and chemical properties and are used in various applications such as base films for magnetic recording media and capacitor dielectrics. In particular, since the film containing aluminum oxide particles has excellent wear resistance, its application range is expanding.

However, it has been difficult to stably obtain a film containing aluminum oxide particles having such excellent wear resistance.

That is, the particle-containing polyester is obtained by adding a slurry containing aluminum oxide to the production process, but the dispersibility of the particles in the slurry is not always sufficient, and coarse agglomerated particles are often produced. Such a problem becomes more remarkable as the particle size of the particles in the slurry becomes smaller and the concentration thereof becomes higher.

[Means for Solving the Problems]

The present inventors, as a result of intensive studies on the above problems,
Crushing of ethylene glycol slurry containing aluminum oxide particles Crushing and suppressing increase of pH as much as possible to prevent generation of agglomerated particles and increase of slurry viscosity after crushing and to obtain extremely excellent dispersibility The inventors have found that this is possible and have completed the present invention.

That is, the gist of the present invention is a method for producing an ethylene glycol slurry added in the polyester production process,
In the disintegration treatment step of an ethylene glycol slurry containing 5 to 40% by weight of aluminum oxide particles, an increase in slurry pH (hydrogen ion concentration) defined by the following formula (1) is set to 1.0 or less. There is a method for producing a slurry.

Increase of slurry pH = slurry pH after crushing treatment−slurry pH before crushing treatment (1) Hereinafter, the present invention will be described in more detail.

The polyester referred to in the present invention means terephthalic acid, 2,6-
An aromatic dicarboxylic acid such as naphthalenedicarboxylic acid or an ester thereof and a polyester obtained by using ethylene glycol as a main starting material are mentioned, but other third component may be contained. In this case, examples of the dicarboxylic acid component include isophthalic acid, terephthalic acid,
One of 2,6-naphthalenedicarboxylic acid, adipic acid and sebacic acid can be used. As the glycol component, one or more of diethylene glycol, propylene glycol, butanediol, 1,4-cyclohexanedimethanol, neopentyl glycol and the like can be used. In any case, the polyester of the present invention refers to a polyester in which 80% or more of repeating structural units have ethylene terephthalate units or ethylene-2,6-naphthalate units.

Such polyester is processed into, for example, a biaxially stretched film and used, but in order to improve its abrasion resistance, it usually contains fine aluminum oxide particles. As the aluminum oxide particles used in the present invention, in consideration of abrasion resistance of the finally obtained film and damage to the substrate in contact with the film, a delta type or a gamma type, in particular, a delta type is contained in an amount of 70% by weight or more. Those are preferably used. Part of the aluminum oxide, for example less than 10% by weight Si,
It may be substituted with Ti, Fe, Na or the like.

The primary particle size of aluminum oxide particles measured by electron microscopy is usually 0.10 μm or less, preferably 0.05 μm.
It is the following.

Since such fine aluminum oxide aggregates to some extent in the production stage and becomes aggregated particles having an average particle size of 0.5 to 2 μm, it is crushed and classified by a dry method, if necessary, and then an ethylene glycol slurry is obtained. As a wet process, crushing, classification and filtration are performed.

For the crushing treatment, for example, a rod mill, a ball mill, a vibration mill, a vibration ball mill, a roller mill, an impact mill,
A stirring crushing mill, a fluid energy mill, etc. can be adopted.

For the classification treatment, for example, an anti-auto vortex system, a forced vortex system, a hydrocyclone system, a centrifugal separation method, etc. can be adopted.

In the present invention, the average particle diameter of secondary agglomerated particles of such aluminum oxide particles is usually 0.3 in ethylene glycol.
It is crushed so that the particle size is not more than μm, preferably not more than 0.15 μm. If the average particle size of the secondary agglomerated particles exceeds 0.3 μm, the abrasion resistance of the film is poor and the base material in contact with the film is damaged, which is not preferable.

In the present invention, it is possible to increase the pH of the ethylene glycol slurry containing aluminum oxide particles in the crushing process step.
It is necessary to be 1.0 or less, preferably by crushing with a relatively weak impact force so that it is 0.5 or less,
It is possible to obtain a slurry having extremely excellent dispersibility without reaggregation of particles after crushing treatment. If the slurry pH increase in the crushing treatment step exceeds 1.0, the particle stability in the slurry is inferior and agglomerates during polyester polymerization to impair the film properties, which is not preferable.

In the slurry disintegration process step, adjust the pH before disintegration process to 3.
By adjusting the amount in the range of 0 to 6.0 or 9.0 to 12.0, preferably 9.0 to 12.0, the dispersibility of particles in the slurry can be enhanced and the concentration of the slurry can be easily increased. If the pH of the slurry before crushing is below 3.0 or above 6.0 9.
When it is less than 0 or more than 12.0, the viscosity of the slurry is significantly increased and the dispersibility of the particles is deteriorated. Therefore, it is better to avoid such a pH range.

In order to adjust the pH of the slurry to the range of 9.0 to 12.0, general basic compounds such as sodium hydroxide, potassium hydroxide and ammonia can be used.

In the present invention, the reason why the stability of the aluminum oxide particles in the ethylene glycol slurry treated under conditions such that the increase in pH in the disintegration treatment step is 1.0 or less and the polyester polymerization is significantly improved is not clear, but comparison is made. It is presumed that there are few newly formed active sites on the surface of the aluminum oxide particles treated with relatively weak impact force, and strong aggregation of the particles does not occur.

In the present invention, the content of aluminum oxide particles in the slurry is in the range of 5 to 40% by weight, preferably 10 to 30% by weight. If the content of particles in the slurry is less than 5% by weight, the amount of ethylene glycol used is increased and the basic unit of ethylene glycol becomes too large, which is not preferable. Further, in the case of a slurry having a particle concentration of more than 40% by weight, the viscosity of the slurry becomes too high and the workability becomes poor.

In the ethylene glycol slurry referred to in the present invention,
20% by weight or less of water, within the range that does not impair the spirit of the present invention,
Methanol, diethylene glycol, etc., or a small amount of fine particles of silica, kaolin, calcium carbonate, etc. may be contained.

The slurry is added to the polyester synthesis reaction step, but it is particularly preferable from the viewpoint of operation and dispersibility that the slurry is added after the transesterification reaction, the esterification reaction, and before the polycondensation reaction.

〔Example〕

Hereinafter, the present invention will be described in more detail with reference to Examples.
The present invention is not limited by the following examples unless it exceeds the gist. The measuring methods and definitions of various physical properties and characteristics in the examples are as follows.
In Examples and Comparative Examples, “part” means “part by weight”.

(1) Measurement of Primary Particle Size by Electron Microscopy The particle size was measured by an electron microscope, and the particle size with an integral volume ratio of 50% in the equivalent spherical distribution was defined as the primary particle size.

(2) Measurement of secondary particle size Centrifugal sedimentation type particle size distribution analyzer (SA-CP3 manufactured by Shimadzu Corporation
Type) 50% of cumulative volume fraction in the equivalent spherical distribution
Was used as the secondary particle diameter.

(3) Measurement of pH pH (hydrogen ion concentration) meter (HM-10 manufactured by Toa Denpa Kogyo)
P-type) was used to measure the aluminum oxide particle-containing ethylene glycol slurry directly at room temperature.

(4) Viscosity measurement The viscosity was measured using an E-type viscometer (VISCONIC-EMD type manufactured by Tokyo Keiki Co., Ltd.) under the conditions of 30 ° C and 20 rpm.

(5) Filterability The ethylene glycol slurry containing aluminum oxide particles was suction-filtered using a wire mesh type filter (mesh # 3600) under the following constant conditions, and the filterability was evaluated from the filtration rate or the degree of filter clogging.

Amount of filtration slurry: 500 ml Filter area: 10 cm ₂ Vacuum degree during suction filtration: 100 mmHg (6) Dispersibility in polymer Evaluated by film-forming polyester containing aluminum oxide particles and measuring the maximum height of protrusions on the surface. .

・ Measurement of maximum height of protrusions A portion of the reference curve (2.5 mm) extracted from the cross-section curve obtained by the surface roughness measuring instrument (SE-3F) manufactured by Kosaka Laboratory Ltd. (hereinafter, extracted portion). Is sandwiched between two straight lines parallel to the average line, the distance between these two straight lines is measured, and the value expressed in units of micrometers (μm) is defined as the maximum height of the extracted portion. The maximum height of the protrusion was obtained by calculating 10 cross-section curves from the surface of the sample film, and expressing the average value of the maximum heights of the extracted portions obtained from these cross-section curves.
The radius of the stylus used for measurement is 2.0 μm, and the load is 30 m.
The g and cutoff value were 0.08 mm.

Example 1 [Preparation of slurry] 13 parts of aluminum oxide particles which are aggregates of primary particles having a primary particle diameter of 0.02 μm and 90 parts of ethylene glycol were used with a homomixer (TK homomixer manufactured by Tokushu Kika Kogyo Co., Ltd.) to rotate at 10,000 rpm. The stirring time was 30 minutes, and the mixture was dispersed. Slurry pH is 7.3, viscosity is 60cp, apparent average particle size is 0.85μ
It was m. Then add 0.1 part of sodium hydroxide to adjust the pH.
Was adjusted to 9.5, and then crushed using a sand grinder (SGL-1 / 2G manufactured by Igarashi Kikai). The conditions at this time are as follows. Media: Glass beads with a diameter of 2 mm, media volume: 1, slurry volume: 1, wind speed: 9 m /
Seconds, shredding time: 140 minutes.

The pH of the slurry obtained after crushing was 9.8, and
The viscosity was 0.3, the viscosity was 23 cp, the average particle size was 0.06 μm, and the filterability of the slurry was good.

[Production of polyester]

Dimethyl terephthalate 100 parts, ethylene glycol 60
Parts and 0.09 parts of magnesium acetate tetrahydrate are heated in a reactor and heated, and methanol is distilled off to carry out an ester conversion reaction. It takes 4 hours from the start of the reaction to raise the temperature to 230 ° C. and substantially transesterify. The reaction was completed.

Next, after adding 2.3 parts of the above slurry, 0.04 part of ethyl acid phosphate was added, and 0.04 part of antimony trioxide was further added to carry out a polycondensation reaction for 5 hours to obtain an intrinsic viscosity of 0.
65 polyethylene terephthalates were obtained.

After drying the obtained polyester, melt extrusion at 290 ° C,
After making it into an amorphous sheet, it is stretched 3.5 times at 90 ° C in the longitudinal direction and 3.7 times at 110 ° C in the transverse direction, and heat treated at 210 ° C for 3 seconds,
A film having a thickness of 15 μm was obtained. The maximum protrusion height of the film surface protrusion generated by the aluminum oxide particles in the obtained film was 0.040 μm, and the film had a uniform fine surface.

Example 2 The concentration of aluminum oxide particles was 20%, and the pH before crushing treatment was
10.0 and the amount of slurry added during polyester polymerization is 1.5
The characteristics were evaluated in the same manner as in Example 1 except for the parts. The increase in the pH of the slurry in the crushing process was 0.4, and the particles in the slurry showed excellent dispersibility, and the dispersed state in the polymer was also good.

Example 3 The concentration of aluminum oxide particles was 20%, 0.2 parts of ethyl acid phosphate was added instead of sodium hydroxide, and p was added.
H was 3.5 and the amount of slurry added during polyester polymerization was 1.
The characteristics were evaluated in the same manner as in Example 1 except that the amount was 5 parts. The increase in the pH of the slurry in the crushing process was 0.9, and the particles in the slurry showed excellent dispersibility, and the dispersed state in the polymer was also good.

Comparative Example 1 The characteristics of Example 1 were evaluated in the same manner as in Example 1 except that the peripheral speed during the slurry disintegration treatment was 13 m / sec.

The increase in the pH of the slurry in the crushing process was 1.5, and the particle dispersibility in the slurry and the dispersion state in the polymer were insufficient.

Comparative Example 2 In Comparative Example 1, except that the particle concentration of the slurry was 20%, 0.25 parts of ethyl acid phosphate was added in place of sodium hydroxide to adjust the pH to 4.0, and the addition amount of the slurry during polyester polymerization was 1.5 parts. The characteristics were evaluated in the same manner as in Comparative Example 1.

The pH increase of the slurry was 2.5, and the dispersibility of particles in the slurry and the dispersion state in the polymer were insufficient.

Comparative Example 3 The characteristics of Comparative Example 2 were evaluated in the same manner as Comparative Example 2 except that the pH was not adjusted with ethyl acid phosphate during the preparation of the slurry.

The resulting slurry was too agglomerated and could not be filtered at all.

The results obtained above are summarized in Table 1 below.

[Effects of the Invention] The aluminum oxide particle-containing ethylene glycol slurry obtained by the production method of the present invention exhibits excellent dispersibility, is suitable for use in polyester addition and has a high industrial value.

Claims (1)

[Claims] 1. A method for producing an ethylene glycol slurry which is added in a polyester producing step, wherein the ethylene glycol slurry containing aluminum oxide particles in an amount of 5 to 40% by weight is defined by the following formula (1) in the crushing step. The method for producing an ethylene glycol slurry is characterized by increasing the pH (hydrogen ion concentration) of the slurry to 1.0 or less. Increase of slurry pH = slurry pH after disintegration treatment-slurry pH before disintegration treatment (1)