JPH04145156A - Production of polyester composition - Google Patents

Abstract

PURPOSE:To readily produce a polyester composition having crosslinked polymer particles uniformly dispersed in a polyester by blending crosslinked polymer particles containing a specific amount of a surfactant with a polyester. CONSTITUTION:(A) A polyester comprising >=80wt.% repeating structural units composed of ethylene terephthalate, ethylene-2,6-naphthalate or 1,4- cyclohexanedimethylene terephthalate is blended with (B) 0.1-30wt.%, preferably 0.3-20wt.% crosslinked polymer particles containing 0.001-1 wt.%, preferably 0.01-0.8wt.% surfactant, having 0.1-1.2mum average particle diameter and a ratio (Dw/Dn) of weight-average particle diameter and number-average particle diameter (Dn) of <=1.1 and kneaded by a screw type twin extruder at 270-310 deg.C for 1-20 minutes.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for producing a polyester composition in which crosslinked polymer particles are uniformly dispersed in polyester.

[Prior art and problems to be solved by the invention] Polyester has excellent physical and chemical properties and is widely used as an industrial material. In particular, biaxially stretched polyester film has superior flatness, mechanical strength, and dimensional stability compared to other films, so it is essential for many applications such as the base material of magnetic recording media and the dielectric material of capacitors. It has become a thing.

These films are required to have excellent running properties and abrasion resistance, and it is known that this can be achieved by adding certain inorganic or organic particles to the film. . Among these particles, it is known that crosslinked polymer particles have particularly excellent affinity with polyester and generally have monodispersity.

However, it is not easy to uniformly disperse organic particles in polyester (particularly when the blending concentration is increased, significant agglomeration often occurs).

In addition, the particles to be added are conventionally added in the form of ethylene glycol slurry during the polyester polymerization process, but in the case of crosslinked polymer particles, foaming often occurs during the polymerization process, making the particle type difficult to use for adding polyester. Met.

[Means for Solving the Problems] As a result of intensive studies in view of the above problems, the present inventors have discovered that by kneading crosslinked polymer particles containing a certain specific component into polyester, the dispersibility of the particles can be improved. This discovery led to the completion of the present invention.

That is, the gist of the present invention is that the surfactant is
The present invention relates to a method for producing a polyester composition, which comprises kneading crosslinked polymer particles containing % by weight of polyester and polyester.

The present invention will be explained in more detail below.

Polyester as used in the present invention refers to a polyester whose main component is an aromatic dicarboxylic acid such as terephthalic acid or 2,6-naphthalene dicarboxylic acid or an ester thereof as an acid component, and ethylene glycol or 1,4-cyclohexane dimetatool as a gelol component. This refers to a polyester whose main component is, but it may contain other copolymer components. In any case, the polyester of the present invention refers to a polyester in which 80% or more of the repeating structural units are ethylene terephthalate units, ethylene-2,6-naphthalate units, or 1°4-cyclohexane dimethylene terephthalate units.

In the present invention, crosslinked polymer particles are blended into such polyester by kneading. As a means for this, a melt molding machine is usually used. The melt molding machine referred to here refers to a molding machine that melts polyester chips and forcibly applies strong shearing force, but it may be either a continuous type or a batch type, and it may be a molding machine with or without vent holes. do not have. in particular,
For example, extrusion molding machines, injection molding machines, Banbury mixers
Among them, good results can be obtained by using a screw type twin screw extruder (or kneader). In this case, the screws may be of co-rotating type or counter-rotating type. The temperature during kneading is usually 270 to 310"
C, and the residence time is usually 1 to 20 minutes, preferably 2 to 10 minutes.

In the present invention, polyester and crosslinked polymer particles are kneaded using a melt molding machine as described above. They are organic particles. Such particles are
Usually, one or more monovinyl compounds (A) having only one aliphatic unsaturated bond in the molecule, and a compound (B) having two or more aliphatic unsaturated bonds in the molecule as a crosslinking agent.
) is produced using one or more of the following as starting materials. Compound (A
) include acrylic acid, methacrylic acid and their alkyl or glycidyl esters, maleic anhydride and its alkyl derivatives, vinyl glycidyl ether,
Examples include vinyl acetate, styrene, and alkyl-substituted styrene.

Further, examples of the compound (B) include divinylbenzene, divinyl sulfone, ethylene glycol dimethacrylate, and the like. One or more types of each of compounds (A) and (B) are used, but a compound having a nitrogen atom or ethylene may be copolymerized.

Emulsion polymerization, which is one of the methods for producing particles used in the present invention, involves polymerization using a very small amount of emulsifier, in addition to typical emulsion polymerization, which uses an amount of emulsifier sufficient to form a critical micelle concentration. These include soap-free polymerization, seed polymerization in which core particles are added to the reaction system prior to emulsion polymerization, and core-shell polymerization in which multi-stage emulsion polymerization is performed by changing the monomer composition. It is preferable to use an emulsifier in order to maintain the dispersion stability of the micelles and the produced particles.

Such compounds called emulsifiers are a type of so-called surfactants, and specifically include fatty acid salts, alkenyl succinates, higher alcohol sulfate ester salts, sodium alkylbenzenesulfonates, alkyldiphenyl ether disulfonates, and naphthalene sulfones. Examples include anionic surfactants such as acid formalin condensates, polyoxyethylene alkyl ether sulfates, and reactive surfactants, and nonionic surfactants such as polyethylene glycol ether and polyoxyethylene sorbitan ester.

In the present invention, the amount of surfactant in the crosslinked polymer particles to be kneaded is 0.001 to 1% by weight, preferably 0.001 to 1% by weight, preferably 0.
．． 01 to 0.8% by weight, more preferably 0.02 to 0
．． It is 5% by weight. If this amount is less than 0.001% by weight, the dispersion of particles in the polyester composition after kneading will not be sufficiently improved, and if this amount exceeds 1% by weight, the thermal stability of the polyester will deteriorate, e.g. When processed into a film, bubbles and discoloration occur.

The amount of surfactant within this range can be achieved, for example, by adjusting the amount of emulsifier during emulsion polymerization and the presence or absence and number of times of washing with water after emulsion polymerization. Of course, it is possible to add a surfactant if necessary, for example, after emulsion polymerization is completed and before drying the water slurry, but it is easier to obtain dry particles while leaving most of the emulsifier used in emulsion polymerization. It is. Note that such a surfactant is preferably present on the surface of the crosslinked polymer particles.

The average particle diameter of the crosslinked polymer particles kneaded with the polyester in the present invention is usually in the range of 0.05 to 1.5 μm, preferably in the range of 0.1 to 1.2 μm. If this value is less than 0.05 μm, for example, when processed into a film, the running properties and abrasion resistance of the film will not be improved, and if this value exceeds 1.2 μm, the surface roughness after film processing will become too large. Undesirable. Further, during kneading, the effects of the present invention are preferably exhibited when the concentration of the crosslinked polymer particles relative to the polyester is 0.1 to 30% by weight, especially <0.3 to 20% by weight. If this value is less than 0.1% by weight, the resulting polyester composition can hardly be expected to be used as a so-called masterbatch, and the effect of improving properties after film processing is also poor. If this value exceeds 30% by weight, the dispersibility in the polyester will be insufficient despite the presence of the surfactant.

In addition, it is preferable that the crosslinked polymer particles used in the present invention have monodispersity. Specifically, the weight average particle diameter (D
8) and the number average particle diameter (D7) (D, /D,)
It is preferably 10 or less, more preferably 1
．． 05 or less, particularly preferably 1.03 or less. When this value exceeds 1.10, the surface of the film after processing becomes non-uniform, and coarse projections are often observed on the film surface.

The polyester composition obtained by the method of the present invention is usually a polyester appropriately containing additive particles or so-called precipitated particles such as kaolin, calcium carbonate, silicon oxide, titanium oxide, aluminum oxide, etc., or a polyester containing substantially no particles. It is diluted appropriately and processed into, for example, a film, and the processed product has a uniform surface and the inherent particles have excellent affinity with polyester, so it can be applied to a variety of uses. can. For example, as a base film for magnetic recording media such as magnetic tapes and floppy disks, for capacitors, for photolithography, for thermal transfer, for thermal stencils, for packaging, etc.
It can be effectively used as a base film in various fields such as transfer marks, gold and silver threads, etc.

[Examples] Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the following Examples unless the gist thereof is exceeded. In addition, the measurement methods and definitions of various physical properties and characteristics in Examples are as follows. In Examples and Comparative Examples, "parts" indicate "parts by weight."

(]) Average particle size and particle size distribution of particles The particle size was measured using an electron microscope. The average particle size was calculated as the particle size (diameter) at a point where the weight fraction of the equivalent sphere was 50%. Note that this value is the weight average particle diameter (D+-), but the number average particle diameter (D, ,) is also determined at the same time, and the ratio of the two (D, 1/
D, , ) was used as an index of the sharpness of the particle size distribution.

(2) Uniformity of film surface Ten point average roughness R2 and center line average roughness R according to the method described in Japanese Industrial Standard JIS BO601.

and the ratio between the two was determined. The smaller this value is, the more preferable it is.

(3) Number of coarse protrusions on the film surface Aluminum is vapor-deposited on the film surface and three-beam interference microscope @
Measured using a mirror. The measurement wavelength was 0.54 μm, and the number of interference fringes of third order or higher order was calculated per 10 cJ.

Example 1 [Production of crosslinked polymer particles] 5.0 parts of potassium persulfate as a water-soluble polymerization initiator and 0 parts of sodium lauryl sulfate as an emulsifier were added to 1000 parts of demineralized water.
．． After adding 0.4 parts and uniformly dissolving it, a mixed solution of 80 parts of styrene and 20 parts of divinylbenzene was added. Next, a polymerization reaction was carried out at 70°C for 8 hours while stirring under a nitrogen gas atmosphere. The reaction rate was 98%, the average particle diameter of the obtained particles was 0.60 μm, and D, 1/D, was 1.02. Moreover, the concentration of the obtained water slurry was 9% by weight.

The resulting water slurry was then dried with hot air without washing with water to obtain crosslinked polymer particles with a water content of 0.1% by weight. The amount of surfactant in the obtained particles was confirmed to be 0.038% by weight from the results of chemical analysis.

[Manufacture of polyester composition]

97 parts of polyethylene terephthalate chips having an intrinsic viscosity of 0.66 and 3 parts of the above dry particles were kneaded in a co-rotating twin-screw kneading extruder (Ikegai Iron Works ■PCM-30).

The kneading temperature was 293° C. and the residence time was 3 minutes, and the mixture was discharged into strands and cooled with water to form chips.

When the dispersion state of the particles in the obtained chip was observed under a microscope, it was found to be extremely good.

[Manufacture of polyester film] The above polyester chip 10 containing 3% by weight of crosslinked polymer
and 90 parts of polyethylene terephthalate chips with an intrinsic viscosity of 0.66, which do not contain particles, were melt-extruded at 290°C using a T-shaped die to form an amorphous sheet, and then heated at 105°C in the longitudinal direction. 3.5x, 120 horizontally
It was stretched 3.5 times at °C and heat treated at 210 °C to obtain a film with a thickness of 15 μm.

The evaluation results of the obtained film are shown in Table 1 along with other examples, and the crosslinked polymer particles were extremely uniformly dispersed, and the surface properties of the film were also satisfactory.

Example 2 Example 1 except that the emulsifier in Example 1 was 0.05 parts of sodium alkyl diphenyl ether disulfonate.
The particles were synthesized in the same manner as in the production of crosslinked polymer particles.

The amount of surfactant in the resulting particles was 0.045% by weight.

Next, a polyester composition was obtained in the same manner as in Example 1,
It was made into a film.

Comparative Example 1 After emulsion polymerization in the production of crosslinked polymer particles of Example 1,
The crosslinked polymer particles in the resulting water slurry were washed three times with water to adjust the amount of surfactant in the particles to 3 ppm.

The obtained particles were kneaded in the same manner as in Example 1, and then formed into a film.

Comparative Example 2 Particles obtained by polymerizing the surfactant obtained in the production of crosslinked polymer particles in Example 1 by 0.038% were dispersed in ethylene glycol (particle concentration 3% by weight), and subjected to ultrasonic dispersion treatment. Thereafter, the obtained slurry was added to the transesterification product so that the concentration of crosslinked polymer particles in the polyester was 0.3% by weight, and a polycondensation reaction was carried out in a conventional manner.

〔Effect of the invention〕

According to the method of the present invention, a polyester composition in which crosslinked polymer particles are uniformly dispersed can be easily obtained, and its industrial value is high.

Claims (1)

[Claims] (1) A method for producing a polyester composition, which comprises kneading crosslinked polymer particles containing 0.001 to 1% by weight of a surfactant and polyester.