JP3380451B2 - Slurry for adding polyester, method for producing the same, and polyester composition using the same - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a slurry for adding polyester, a method for producing the same, and a polyester composition produced using the slurry. More specifically, there are very few spherical coarse particles and agglomerates of spherical organic polymer particles dispersed in the slurry, and an excellent slurry for polyester addition and a method for producing the same, and a polyester composition produced using the slurry. The present invention relates to a polyester composition capable of producing a film having excellent surface characteristics with extremely few coarse projections when formed into a film.

[0002]

2. Description of the Related Art Generally, polyester, especially polyethylene terephthalate, is widely used for films, fibers and the like because of its excellent mechanical properties and chemical properties.

However, in the case of producing a film or fiber which makes full use of its transparency and brilliance,
In the molding process and processing process, process defects were often caused. The cause is often due to the high coefficient of friction.

Conventionally, as a method for reducing the friction coefficient of a polyester film, many methods in which fine particles are present in polyester have been proposed. As these fine particles, various organic polymer particles have been proposed because of their superior affinity to polymers as compared with inorganic particles. Above all, from the viewpoint of achieving both runnability and protrusion uniformity (flatness) on the surface. Therefore, many proposals regarding spherical particles have been made (for example, JP-A-63-191838 (spherical silicone resin fine particles) and JP-A-1-129038 (spherical cross-linked polystyrene particles)).

[0005]

By the way, according to the study by the present inventors, a small amount of spherical coarse particles, agglomerates, amorphous particles, and the like are by-produced in the conventional spherical organic polymer particles in the manufacturing process. Generally, as a method for reducing these, filtration treatment after slurrying is effective, but it is possible to significantly reduce spherical coarse particles and the like in the unit of μm and to simultaneously suppress filter clogging during slurry filtration. Difficult,
It wasn't optimized.

When such particles are prepared in a slurry for adding polyester, there remains a problem that spherical coarse particles and aggregates remain. Incidentally, when these are mixed in polyester, for example, when formed into a film, coarse protrusions are formed on the film surface, and when used as a magnetic recording medium, they cause dropout. In particular, this is a particularly serious defect in recent high-density magnetic recording medium applications. Above all, since spherical coarse particles are mixed in with a high protrusion, even a very small amount has a great influence on the film. Moreover, quantification of spherical coarse particles in the slurry is extremely difficult to quantify by general particle size measurement, etc., because the amount of contamination is extremely small, so the number of coarse particles in the slurry and the like in the film are not always required. The relationship between the number of coarse projections was not clear.

As a result of further studies on the above problems, the present inventor has found out that the above problems are caused by extremely small amounts of spherical coarse particles and aggregates in the slurry, and these spherical coarse particles, aggregates and the like are significantly reduced. It was found that the above problem can be solved by reducing

Therefore, an object of the present invention is to provide a slurry for polyester addition in which the number of spherical coarse particles and agglomerates and the like are not more than a specified amount, and a method for producing the same, and further, the above-mentioned problem of the slurry produced using the slurry. To provide a polyester composition.

[0009]

The first object of the present invention is to:
Which is a slurry in which spherical organic polymer particles having an average particle diameter of 1.5 μm or less are dispersed, and when the particles are filtered with a straight pore membrane filter having an opening of 3 μm, the residual rate of the particles is 0. It is achieved by a slurry for adding polyester, which is characterized in that it is not more than 01% by weight, and the existence probability of the number of spherical coarse particles on the filter is not more than 5 / 1,000,000.

Thirdly, the object of the present invention is achieved by a method for producing a slurry for polyester addition, which comprises filtering the slurry with a filter having an absolute filtration accuracy of 3 μm or less when producing the above slurry.

A third object of the present invention is to prepare a polyester composition which is produced by using the above-mentioned slurry for adding polyester and contains 0.001 to 5% by weight (based on the polyester) of spherical organic polymer particles. Achieved by things.

The polyester in the present invention is a polyester having an aromatic dicarboxylic acid as a main acid component and an aliphatic glycol as a main glycol component. Such polyesters are substantially linear and have film forming properties, especially film forming properties by melt molding.
Examples of the aromatic dicarboxylic acid include terephthalic acid, naphthalenedicarboxylic acid, isophthalic acid, diphenylketone dicarboxylic acid and anthracene dicarboxylic acid. Examples of the aliphatic glycols include alkylene glycols having 2 to 10 carbon atoms such as ethylene glycol, trimethylene glycol, tetramethylene glycol, pentamethylene glycol, hexamethylene glycol, decamethylene glycol, and aliphatic diols such as cyclohexanedimethanol. Can be mentioned.

In the present invention, as the polyester, a polymer containing alkylene terephthalate and / or alkylene naphthalate as a main constituent is preferably used. Among such polyesters, especially polyethylene terephthalate, polyethylene-2,6-naphthalate, etc.
A copolymer in which at least mol% is terephthalic acid and / or 2,6-naphthalenedicarboxylic acid and at least 80 mol% of all glycol components is ethylene glycol is preferred. At that time, 20 mol% or less of all the acid components is the above-mentioned aromatic dicarboxylic acid other than terephthalic acid and / or 2,6-naphthalenedicarboxylic acid as long as the surface flatness and dry heat deterioration are not impaired. Further, it may be an aliphatic dicarboxylic acid such as adipic acid or sebacic acid, or an aliphatic dicarboxylic acid such as cyclohexane-1,4-dicarboxylic acid. Further, 20 mol% or less of the total glycol component is the above other than ethylene glycol,
It can be a glycol, for example hydroquinone,
Resorcin, 2,2-bis (4-hydroxyphenyl)
And aliphatic diols such as propane, aromatic diols having an aromatic ring such as 1,4-dihydroxydimethylbenzene, and polyalkylene glycols (polyoxyalkylene glycols) such as polyethylene glycol, polypropylene glycol, polytetramethylene glycol, etc. You can also Further, the polyester in the present invention, unless the effect of the present invention is impaired, an aromatic oxy acid such as hydroxybenzoic acid, a component derived from an oxycarboxylic acid such as an aliphatic oxy acid such as ω-hydroxycaproic acid, Those which are copolymerized or bonded at 20 mol% or less based on the total amount of the dicarboxylic acid component and the oxycarboxylic acid component are also included.

Further, the polyester in the present invention is trifunctional in an amount within a range of being substantially linear and within a range of not more than 2 mol% with respect to the total acid component unless the effects of the present invention are impaired. Also included are those obtained by copolymerizing the above polycarboxylic acids or polyhydroxy compounds such as trimellitic acid and pentaerythritol.

Further, in the polyester of the present invention,
As long as the effect of the present invention is not impaired, for example, a lubricant,
Pigments, dyes, optical brighteners, antistatic agents, flame retardants, antioxidants, light stabilizers, light shielding agents (for example, carbon black,
If necessary, additives such as titanium oxide) can be included.

The above polyesters are known per se,
And it can be manufactured by a method known per se. As the above polyester, those having an intrinsic viscosity of about 0.4 to about 0.9 obtained by measuring at 35 ° C. as a solution in o-chlorophenol are preferable.

The spherical organic polymer particles dispersed in the slurry for addition of polyester in the present invention are not particularly limited as long as they can be added to polyester, but crosslinked polystyrene, silicone resin, silicone rubber, melamine / formaldehyde co-polymer. Examples thereof include spherical organic polymer particles having one or more components such as coalescence, benzoguanamine, thermosetting epoxy, and crosslinked polyester. Further, the production method of the spherical organic polymer particles, the structure, the surface treatment, etc., is not limited as long as spherical particles within the scope of the present invention can be obtained, for example, emulsion polymerization, soap-free emulsion polymerization, seed emulsion polymerization, Examples thereof include suspension polymerization, dispersion polymerization, two-step expansion polymerization and the like. Furthermore, in the structure of particles, organic heterogeneous polymer composite particles (core / shell type) and inorganic / organic composite particles (organic particle surface coated with an inorganic compound,
Metals or metal bonds are partially supported on the particle structure), hollow particles and the like are also included, and the surface treatment may be silane coupling treatment or the like.

In the present invention, one kind or two or more kinds of these particles can be used. Among these, crosslinked polystyrene particles are preferable as the spherical particles having excellent heat resistance.

Further, the spherical cross-linked polystyrene particles are not limited to the production method and the like. For example, in the production method, styrene such as styrene monomer, methyl styrene monomer, α-methyl styrene monomer and dichlorostyrene monomer is used. In addition to derivative monomers, conjugated diene monomers of butadiene, unsaturated nitrile monomers such as acrylonitrile, monomers such as methacrylic acid esters such as methyl methacrylate, functional monomers such as unsaturated carboxylic acids, hydroxy A monomer having a hydroxyl group such as ethyl methacrylate, a monomer having an epoxide group such as glycidyl methacrylate, and one or more kinds of monomers selected from unsaturated sulfonic acid and the like, and for making the polymer particles have a three-dimensional structure As a cross-linking agent, Emulsion polymerization of functional vinyl compounds, such as divinylbenzene, ethylene glycol dimethacrylate, trimethylolpropane triacrylate, diallyl phthalate, etc., in an aqueous medium in which a water-soluble polymer is dissolved as a protective colloid to form an emulsion of polymer particles. It can be obtained by preparing and recovering polymer particles from this emulsion.

The average particle diameter of the spherical organic polymer particles in the present invention is 1.5 μm or less. It is preferably 1.0 μm or less, more preferably 0.8 μm or less. If the particle size exceeds 1.5 μm, clogging tends to occur during filtration with a straight pore membrane filter having an opening of 3 μm, which is not preferable.

Further, the relative standard deviation of the particle size of the above-mentioned particles is preferably 0.5 or less, more preferably 0.3 or less, and particularly preferably 0.12 or less. When the relative standard deviation is larger than 0.5, the uniformity of protrusions when formed into a film becomes insufficient, which is not preferable.

[0022]

[Equation 1]

The particles may have a spherical shape, more preferably a true spherical shape, which is effective for imparting slipperiness to the film.

The slurry added to the polyester of the present invention needs to have a particle residue rate of 0.01% by weight or less at the time of filtration with a filter having a pore size of 3 μm and a straight pore. It is preferably 0.005% by weight or less. If the residue rate is more than 0.01% by weight, high protrusions due to spherical coarse particles, agglomerates, etc. are large on the film surface, and dropout of the magnetic recording medium using the film is likely to occur. The residual rate (% by weight) of the particles is represented by the following formula.

[0025]

## EQU00002 ## Residual rate of particles (% by weight) = ((AB) / C)
× 100 ≦ 0.01 Here, A is the weight of the filter after filtering the particles, B is the weight of the filter before filtering, and C is the weight of the particles used for filtration.

Further, it is necessary that the existence probability of the number of spherical coarse particles on the filter after filtration is 5 / million or less. It is preferably 5 / 10,000,000 or less. When the existence probability of the spherical coarse particles is more than 5 / 1,000,000, many high protrusions due to the spherical coarse particles are generated on the surface of the film, which easily causes dropout of the magnetic recording medium based on the film. Become.

The existence probability described here is an opening of 3 μm.
In the slurry filtration using the non-porous membrane filter, the value obtained by converting the weight of the particles used for filtration into the number of particles based on the average particle size and density of the particles is used. (The average particle size is calculated from the area equivalent circle diameter and converted to the number as perfect spherical particles)

As the spherical coarse particles in the present invention, for example, the particle size ratio defined by the ratio of the maximum diameter to the minimum diameter is 1.0 to.
Examples thereof include those in the range of 1.2, and examples of the morphology include single spheres and fine particle granulated / aggregated spheres.

The filter used for the evaluation filtration of the present invention is a direct-pore membrane filter. Other porous,
Fibrous filters are not preferable because they cause problems such as cake generation on the filter surface and / or spherical coarse particles being buried inside the filter.

As the slurry for adding polyester, the slurry immediately after the synthesis of the spherical organic polymer particles and / or the solvent of the slurry may be replaced with an organic solvent, and then the slurry preparation described below may be carried out and used, or filtration and centrifugation. The particles may be treated by separation or the like to extract the fine particles, and then washed, dried, crushed, etc., and then re-slurried.

The dispersion medium of the polyester addition slurry is not particularly limited, and known media can be used. Examples thereof include water, an organic solvent, and a mixture thereof. Particularly, it is presumed to be added during the production of polyester, and a glycol component as a raw material of polyester, particularly ethylene glycol is preferable from the viewpoint of cost. The concentration of the slurry is 40
It is not more than 20% by weight, preferably not more than 30% by weight, more preferably not more than 20% by weight. If this amount is higher than 40% by weight, the viscosity of the slurry becomes high, and filtration is substantially difficult, which is not preferable. Further, the lower limit of the slurry concentration is preferably 5% by weight from the viewpoint of handleability. It should be noted that the slurry may contain a dispersant, an antifoaming agent, etc. within a range that does not impair the effects of the present invention.

There are no particular restrictions on the method for making the residue rate and the probability of the presence of the number of spherical coarse particles in the slurry less than the specific values of the present invention, but the particles are dispersed, classified, crushed and pre-filtered (pre-filtration). A known method for preparing a slurry such as) is preferable. These preparations may be carried out individually or a plurality of times, and / or may be repeatedly carried out by combining the respective preparations, and may be carried out as a pre-preparation (treatment) leading to a slurry preparation with a filter having an absolute filtration accuracy of 3 μm or less as described later. Preferably.

Further, the slurry after pre-preparation has an opening of 3 μm.
It is preferable that the above-mentioned residual rate at the time of filtering with the non-porous membrane filter of No. 5 is 0.05% by weight or less, since the filter clogging at the time of absolute filtration preparation is alleviated. More preferably, it is 0.03% by weight or less. When the residual amount is more than 0.05% by weight, clogging is likely to occur during filter filtration with an absolute filtration accuracy of 3 μm or less, and coarse particles and the like are likely to slip through when the pressure of the filter is increased, which is preferable. Absent.

In this pre-preparation, it is preferable to suppress the deformation (cracking, crushing, crushing, etc.) of the particles themselves, and the ratio of the deformed particles to the total number of the particles is 20% or less, more preferably 10%. The number is less than or equal to%. When the number of the deformed particles is more than 20% by number, the projection forming property when formed into a film is deteriorated, which is not preferable.

The slurry filtration preparation with a filter having an absolute filtration accuracy of 3 μm or less in the present invention is effective for removing spherical coarse particles and aggregates, and is preferably carried out. It is particularly preferable to perform the filtration treatment a plurality of times in order to reduce coarse particles. (Absolute filtration accuracy is based on glass bead passage test and / or test method based on ANSI B93, 31-1973)

The mechanism of suppressing the generation of coarse protrusions when the polyester composition produced by using the slurry for polyester addition in the present invention is formed into a film has a specific value in the slurry stage such as spherical coarse particles which become high protrusions in the film. It seems that you have done the following.

When preparing the above-mentioned slurry, it is preferable to reduce the residue rate in the slurry in the pre-preparation step, and then carry out filter filtration with an absolute filtration accuracy of 3 μm or less, thereby reducing spherical coarse particles. We think that we were able to achieve both suppression of filter clogging.

In the present invention, the spherical organic polymer particles may be dispersed and contained in the polyester composition at any time, but in the polyester production process, for example, terephthalic acid or 2,6-naphthalenedicarboxylic acid is used as a raw material. A method in which the slurry is added at the esterification reaction stage of the direct polymerization method or at the transesterification reaction time of the transesterification method using dimethylene terephthalate or dimethylene-2,6-naphthalene dicarboxylate as a raw material. Further, for example, using a vent type extruder, a method of mixing molten polyester and particle slurry dispersed in a dispersion medium such as water or an organic solvent in an extruder and removing the vaporized dispersion medium through a vent can be mentioned. .

The amount of the particles added to the polyester in the present invention is not particularly limited, but it is
It is 0.001 to 5% by weight, preferably 0.005 to 2% by weight. If the amount added is too small, the slipperiness in forming a film becomes poor, while if the amount added is too large, problems such as insufficient dispersibility in the polymer occur.

In the present invention, particles other than the spherical organic polymer particles may be added to the polyester composition and used in combination with the spherical organic polymer particles. Examples of these particles include silicon oxide, alumina, titanium oxide, calcium carbonate, kaolin, zirconium oxide, and carbun black.

When the polyester composition of the present invention is applied to a film, a conventionally known method can be applied. For example, polyester is melt extruded and rapidly cooled to obtain an unstretched film, and then the unstretched film is stretched biaxially,
It can be produced by heat setting and, if necessary, relaxation heat treatment. Physical properties such as surface characteristics, density, and heat shrinkage of the film at that time vary depending on stretching conditions and other manufacturing conditions, and are appropriately selected as necessary. This film may be used as a monolayer film, but may be used as a biaxially stretched laminated film in which a layer containing the polyester composition of the present invention is laminated on at least one surface. These films are
It can be most preferably used as a base film of a magnetic recording medium by taking advantage of the feature that the spherical coarse particles of the present invention are extremely small.

As a method for producing a film, for example, the above-mentioned unstretched film is uniaxially (longitudinal or transverse) at a temperature of (Tg-10) to (Tg + 60) ° C. (however, T
g: glass transition temperature of polyester), and stretched at a draw ratio of 2.5 times or more, preferably 3 times or more, and then 2.5 times or more at a temperature of Tg to (Tg + 70) ° C. in the direction perpendicular to the stretching direction. It is preferable to stretch at a draw ratio of 3 times or more. Further, if necessary, it may be stretched again in the machine direction and / or the transverse direction. Thus, the total draw ratio is preferably 9 times or more as an area draw ratio, and
Double is more preferable, and 15 to 30 times is particularly preferable. Furthermore, the biaxially stretched film has (Tg + 70) to (Tm-1)
It can be heat-set at a temperature of 0) ° C. (however, Tm: melting point of polyester), and for example, heat-setting at a temperature of 180 to 250 ° C. is preferable. The heat setting time is preferably 1 to 60 seconds.

[0043]

The present invention will be described in detail in the following examples. Various physical properties and characteristics in the present invention are measured and defined as follows.

(1) Average particle size of particles Using an aqueous solution containing a trace amount of a surfactant as a dispersion medium, a CP-50 type St. Fugle particle size analyzer (Centrifugal Particle Size Analyst) manufactured by Shimadzu Corporation
The particle size corresponding to 50 mass% is read from the integrated curve of the particle size calculated based on the centrifugal sedimentation curve obtained by using (yzer) and the abundance of particles having that particle size, and this value is calculated as the above average. The particle size. (Book “Granularity Measurement Technology”
(Published by Nikkan Kogyo Shimbun, 1975, pp. 242-247)

(2) Relative standard deviation of particle size The difference particle size distribution is obtained from the integrated curve in item (1), and the relative standard deviation is calculated based on the following definition formula of relative standard deviation.

[0046]

[Equation 3]

(3) Residual rate from the slurry About 0.1 to 1.0 g of the slurry, which corresponds to the amount of powder, is sampled, and the weight is accurately weighed with a high precision electronic balance. Then, the mixture is diluted and dispersed in about 300 ml of a dispersion medium (ethanol), and natural filtration is performed using a pre-measured Nomura Science direct membrane filter having a pore size of 3 μm. When the filtration is completed, the filter surface is washed and filtered with 1000 to 3000 ml of the dispersion medium. After filtration, the filter is dried and weighed, and the residue rate is calculated from the following equation 1. The amount of slurry collected is appropriately changed according to the residue rate so as to facilitate filtration.

[0048]

## EQU00004 ## Particle residue rate (wt%) = ((A−B) / C) × 100 In the formula, A is the filter weight after filtering the particles, B is the filter weight before filtering, and C is the filter weight. It is the weight of the particles.

(4) Existence probability of the number of spherical coarse particles from the slurry About 0.002 to 0.2 g of the slurry corresponding to the amount of powder is sampled, and the weight is accurately weighed with a high precision electronic balance. Next, dilute and disperse in about 300 ml of dispersion medium (ethanol), Nomura Science Co., Ltd., direct pore membrane filter mesh opening 3 μm
Is used for natural filtration. When the filtration is completed, the filter surface is washed and filtered with 1000 to 3000 ml of the dispersion medium. After filtration, the filter is dried, gold sputter is applied to the filter, and it is 500 to 10 with a scanning electron microscope.
Observe at 00 times and count only spherical particles on the filter. The number of spherical coarse particles is calculated by converting to a powder amount of 1 g. Next, the amount of powder used for filtration is converted into a number unit mainly by the average particle size and density of the particles, and the existence establishment is determined from the following formula. In this specification, the number of converted particles is 10
It is expressed by the number of spherical coarse particles on the filter for 0,000 particles.

[0050]

Established existence = D / E In the formula, D is the count number of spherical coarse particles on the straight-pore membrane filter, and E is the number of the powder amount used for filtration converted into a number unit.

(5) Particle Size Ratio of Spherical Coarse Particles The spherical coarse particles in the item (4) are observed with an electron microscope and expressed by the ratio of the maximum diameter to the minimum diameter of the spherical coarse particles.

(6) Evaluation of Slurry Filterability By using a slurry having a particle concentration adjusted to 10% by weight, filtration is performed with a filter having an absolute filtration accuracy of 3 μm. It should be noted that the filtration condition was 2.0 to 3.5 by sending 100 L of the slurry at room temperature.
Filtering is carried out at kg / cm ² , and clogging is judged by the fluctuation of the filter pressure. The condition of clogging is displayed by judgment as follows. The measurement is performed with n = 3 times. ⊚: Filter pressure is not raised at all, and filtration is good. △: Filter pressure is slightly raised, and filtration is not satisfactory. ×: Filter pressure, pressure is raised rapidly and filtration is not possible.

(7) Deformation particle ratio adjusting slurry in slurry particles A small amount of a slurry is sampled, diluted with a dispersion medium (ethanol), and then dropped on a sample table and dried. Next, with a scanning electron microscope, at a magnification of 10,000 to 30,000, at least 1
00 or more particles are observed, and the number of deformed (cracked, crushed, crushed, etc.) particles is calculated by the following equation (5). The measurement is performed with n = 5 times.

[0054]

[Formula 6] Number of deformed particles% = (count of deformed particles / total count of the particles) × 100

(8) Number of Coarse Protrusions in Film and Evaluation Film Inside Coarse Protrusions The film was observed under a polarizing microscope, and the place where polarization was applied had a maximum diameter of 5 to 8 μm or more.
The number per cm 2 was measured and displayed as follows.
The measurement is performed with n = 5 times. [Four-level judgment] ◎ 0 to 5 pieces Very good number of coarse projections ○ 6 to 10 pieces Number of coarse projections Normal △ 11 to 20 pieces Large number of coarse projections × 20 or more Very large number of coarse projections Marking is applied to
The polymer in the surface layer is removed with a plasma reactor, and the nuclei inside the coarse projections are observed with a scanning electron microscope.

Example 1 (1) Preparation of Slurry Crosslinked polystyrene particles (average particle size = 1.0 μm, relative standard deviation = 0.35) were synthesized by seed emulsion polymerization in an aqueous medium, and then an evaporator was used. The ethylene glycol used was replaced with ethylene glycol to obtain 1000 kg of an ethylene glycol dispersion (content of crosslinked polystyrene particles = 10% by weight). Next, after stirring and dispersing with a suction dispersion stirrer (Jetstream Inductor Mixer) for 4 hours, a media stirring type crusher (Ult
The slurry was subjected to high-flow self-circulation for 1 hour at ra-Visco Mill). Then, filtration was performed once with a pleat type filter having openings of 10 μm and 5 μm (pre-filtration) to prepare a slurry. This pre-prepared slurry was subjected to continuous pass treatment 5 times with a filter having an absolute filtration accuracy of 3 μm.

(2) Production of polyester containing spherical crosslinked polystyrene particles Using dimethyl terephthalate and ethylene glycol as raw materials, manganese acetate as an ester exchange catalyst, antimony trioxide as a polymerization catalyst, and phosphorous acid as a stabilizer are prepared by a conventional method. In addition, in the final stage of the transesterification reaction, the spherical silicone resin particle slurry in (2) was added to dimethyl terephthalate in an amount equivalent to 0.2% by weight as the particles, and then the polymerization reaction was performed. Polyethylene terephthalate (polyester composition) having an intrinsic viscosity of 0.62 (orthochlorophenol, 35 ° C.) was obtained.

(3) Film formation of polyester composition The polyester pellets obtained in (2) were dried at 170 ° C. for 3 hours and then fed to an extruder hopper at a melting temperature of 28.
It was melted at 0 to 300 ° C., and this molten polymer was extruded through a 1 mm slit die onto a rotary cooling drum having a surface temperature of 20 ° C. and rapidly cooled to obtain an unstretched film. This unstretched film was preheated to 75 ° C., further heated by a single IR heater having a surface temperature of 900 ° C. from above 15 mm between low-speed and high-speed rolls, stretched to 3.6 times, and rapidly cooled. Was supplied to a stenter and stretched 3.7 times in the transverse direction at 105 ° C. The obtained biaxially oriented film was heat set at a temperature of 205 ° C. for 5 seconds to obtain a heat set biaxially oriented polyester film having a thickness of 15 μm. The obtained slurry characteristics and film characteristics are shown in Table 1.

[Example 2] Discontinuation of treatment with a medium agitation type pulverizer in slurry preparation, and the number of prefilter filtrations was 10
Slurry and film were obtained in the same manner as in Example 1, except that the number of filtration treatments with an absolute filtration accuracy of 3 μm was changed to 1 pass. The obtained slurry characteristics and film characteristics are shown in Table 1.

[Example 3] (1) Preparation of slurry In the slurry preparation of the particles of Example 1, an aqueous dispersion of 1000 kg (crosslinked polystyrene particle content = 10% by weight) was prepared without substitution with ethylene glycol. After changing and stirring and dispersing with a suction dispersion stirrer (Jetstream Inductor Mixer) for 4 hours, a medium stirring type crusher (Ult
Ra-Visco Mill) circulates the slurry for 2 hours at high flow rate, and then filters it once with pleat type filters with openings of 10 μm and 5 μm (pre-filtration).
The slurry was prepared in advance. This pre-prepared slurry was subjected to continuous pass treatment 5 times with a filter having an absolute filtration accuracy of 3 μm.

(2) Production of Polyester Containing Spherical Crosslinked Polystyrene Particles Undried polyethylene terephthalate pellets containing no additive were used in an amount of 5 to 15 kg / H from a vibration type quantitative feeder.
In a ratio in the range of r, the mixture was fed to a vent type co-rotating mesh type twin-screw kneading extruder having a kneading disc paddle as a screw constituent, and at the same time, using a Milton type metering pump, the content of the particles in the polyester was 0.2
The slurry of the above (1) was added so that the weight% was obtained.
At this time, set the degree of vacuum at the vent port to about 1 mmHg,
The mixture was melt-kneaded at a cylinder temperature of 285 ° C. and extruded to obtain polyethylene terephthalate (polyester composition) having an intrinsic viscosity of 0.57 (orthochlorophenol, 35 ° C.). The polyester composition was formed into a film in the same manner as in Example 1 to obtain a film. The obtained slurry characteristics and film characteristics are shown in Table 1.

Example 4 In the preparation of the slurry of Example 1, the spherical crosslinked polystyrene particles were once taken out from the aqueous dispersion as a powder by using an airflow type dispersion classifier, and then 1000 kg of ethylene glycol slurry (containing the crosslinked polystyrene particles was included. (Amount = 10% by weight), and a slurry and a film were obtained in the same manner as in Example 1 except that the medium stirring type pulverizer was changed to 4 hours. The obtained slurry characteristics and film characteristics are shown in Table 1.

Example 5 Crosslinked polystyrene particles (average particle size = 0.5 μm, relative standard deviation = 0.10) were changed, and the amount of the particles added in the production of polyester was changed to 0.5% by weight. A slurry and a film were obtained in the same manner as in Example 1 except for the above. The obtained slurry characteristics and film characteristics are shown in Table 1.

Example 6 Spherical silicone rubber particles (average particle size) obtained by underwater curing of crosslinked polystyrene particles from a reaction solution obtained by addition polymerization of vinyl group-containing methylpolysiloxane and methylhydrogenpolysiloxane =
1.2 μm, relative standard deviation = 0.20), and a slurry and a film were obtained in the same manner as in Example 1 except that the addition amount of the particles in the polyester production was changed to 0.25% by weight. . The obtained slurry characteristics and film characteristics are shown in Table 1.

[Example 7] The crosslinked polystyrene particles were changed to spherical silicone resin particles (average particle size = 0.5 µm, relative standard deviation = 0.12), and the addition amount of the particles in the production of polyester was 0.50. A slurry and a film were obtained in the same manner as in Example 1 except that the weight% was changed. The obtained slurry characteristics and film characteristics are shown in Table 1.

Comparative Example 1 Pre-filtration in slurry preparation,
A slurry and a film were obtained in the same manner as in Example 1 except that the filtration treatment with an absolute filtration accuracy of 3 μm was stopped. The obtained slurry characteristics and film characteristics are shown in Table 1.

[Comparative Example 2] A slurry and a film were obtained in the same manner as in Example 1 except that the wet pulverization treatment in the slurry preparation was changed to 14 hr and the filtration treatment with an absolute filtration accuracy of 3 µm was stopped. The obtained slurry characteristics and film characteristics are shown in Table 1.

Comparative Example 3 Absolute Filtration Accuracy in Slurry Preparation Except that the filtration process with a 3 μm filter was stopped.
A slurry and a film were obtained in the same manner as in Example 5. The obtained slurry characteristics and film characteristics are shown in Table 1. Compared to Comparative Examples 1 to 3, in Examples 1 to 5, coarse projections were reduced in the film, and a large improvement effect was observed.

[0069]

[Table 1]

[0070]

EFFECTS OF THE INVENTION According to the present invention, it is possible to provide a slurry for adding polyester, which contains spherical organic polymer particles in a dispersed state and contains few spherical coarse particles and aggregates. Further, it is possible to provide a polyester composition capable of obtaining a film having extremely few coarse protrusions when formed into a film.

Continuation of front page (58) Fields investigated (Int.Cl. ⁷ , DB name) C08L 67/00-67/02

Claims (6)

(57) [Claims] 1. A slurry in which spherical organic polymer particles having an average particle diameter of 1.5 μm or less are dispersed, having an opening of 3 μm.
When the particles are filtered by the non-porous membrane filter of No. 1, the residual rate of the particles is 0.01% by weight or less, and the existence probability of the number of spherical coarse particles on the filter is 5 / 1,000,000 or less. Characteristic polyester addition slurry. 2. The polyester addition slurry according to claim 1, wherein the spherical organic polymer particles are spherical crosslinked polystyrene particles. 3. The polyester addition slurry according to claim 1, wherein the dispersion medium of the slurry is ethylene glycol. 4. A method for producing a polyester-adding slurry, which comprises filtering the slurry with a filter having an absolute filtration accuracy of 3 μm or less when the slurry according to claim 1 is produced. 5. A polyester composition containing 0.001 to 5% by weight (based on polyester) of spherical organic polymer particles produced by using the slurry for adding polyester according to any one of claims 1 to 3. 6. The polyester composition according to claim 5, wherein the polyester is polyalkylene terephthalate and / or polyalkylene naphthalate.