JPH047350A - Antistatic polyester composition - Google Patents

Abstract

PURPOSE:To obtain a polyester composition which can be molded into a film, a fiber or the like improved in antistatic properties by dispersing inert inorganic particles subjected to a specified surface treatment in a polyester. CONSTITUTION:Inert inorganic particles having a negative xsi-potential value and a mean particle diameter of 10-3000mum and being surface-treated with 0.01-40 pts.wt. (per 100 pts.wt. inert inorganic particles) compound having at least one amino group and at least one sulfonic group and/or metal sulfonate group are dispersed in a polyester mainly consisting of an aromatic acid dicarboxylic acid and a glycol and mainly consisting of repeating units of an aromatic carboxylate to obtain an antistatic polyester composition containing 0.01-5.0 pts.wt. above compound. This polyester composition can exhibit its antistatic effect when molded into a fiber, a film or other molding, and is desirable especially as a magnetic tape film which is repeatedly used in a state of contact friction.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an antistatic polyester composition containing inert inorganic particles whose surface has been treated with a specific compound as an antistatic agent.

[Prior art] Polyester films, represented by polyethylene terephthalate and polyethylene naphthalate, have excellent mechanical properties, weather resistance, electrical insulation properties, and chemical resistance, so they are used for magnetic tape films, capacitor films, photographic films, etc. It is widely used in

However, these polyester films are generally prone to being charged by contact running, etc., and the accumulation of static electricity can cause various problems such as product defects due to dirt absorption when the films are attached to each other during film forming and processing processes. is causing it.

Various studies have been made to prevent static electricity on such polyester films.

In general, antistatic agents are applied to the film surface or incorporated into the film, but the former method (e.g.
JP-A No. 61-205137, etc.), although the complexity of the coating process increases, there is a problem in that repeated contact running causes the coating agent to fall off, making it impossible to maintain the antistatic effect. On the other hand, many studies have been made on the latter method, and among them, it is well known that the addition of sulfonic acid derivatives to polyester is effective (Japanese Patent Application Laid-Open No. 52-118).
47071, JP-A-52-47072, JP-A-60-38123, etc.). However, as mentioned in the text, these methods have the problem that the dispersibility of the sulfonic acid derivative is insufficient, the sulfonic acid derivative bleeds out on the surface, and the effectiveness decreases over time.

[Problems to be Solved by the Invention] As a result of intensive studies, the present inventors have found that by surface-treating the inert inorganic particles blended with polyester under specific conditions and imparting an antistatic function to the treatment agent, , we have found a solution to these problems.

An object of the present invention is to provide a polyester composition that has improved antistatic properties when formed into a film, fiber, etc. by blending and dispersing inert inorganic particles that have undergone a specific surface treatment into polyester. be.

[Means for Solving the Problems] The object of the present invention described above is to provide a polyester mainly composed of an aromatic dicarboxylic acid and a glycol whose main repeating unit is an aromatic carboxylate, such that the ζ-potential in pure water is -charged. 0.01 to 40 parts by weight of a compound having at least one amino group and at least one sulfonic acid group and/or sulfonic acid metal base (inert inorganic particles with an average particle diameter of 10 to 3000 mμ) 100 parts by weight), and 0.
This can be achieved by using an antistatic polyester composition containing 01 to 5.0 parts by weight.

Generally, protrusions are formed on the film surface by inert inorganic particles added to the film, and since these protrusions selectively run in contact with each other, it is important that the protrusions have excellent antistatic properties. However, when the antistatic polyester composition of the present invention is formed into a film, the antistatic agent concentration around the particles is high and the antistatic agent is bonded to the particles, so surface bleed-out of the antistatic agent is suppressed. , the deterioration of antistatic ability over time is suppressed.

The polyester in the present invention is terephthalic acid.

2. Aromatic dicarboxylic acids such as 6-naphthalene dicarboxylic acid, diphenyldicarboxylic acid, and isophthalic acid; aliphatic dicarboxylic acids such as adipic acid and sebacic acid; and alicyclic dicarboxylic acids such as hexahydroterephthalic acid and hexahydroisophthalic acid. A dicarboxylic acid component represented by
It is a polyester obtained from glycol components such as ethylene glycol, butanediol, and cyclohexane dimetatool, and specific examples include polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate. Further, these polyesters may be homopolymers or copolymer polymers, and as the copolymer component, one or more of the dicarboxylic acid components and diol components described above can also be used. Furthermore, polyalkylene glycols such as polyethylene glycol and polybutylene glycol, and dicarboxylic acids such as 5-sodium sulfoisophthalic acid and hydroxyethoxybenzoic acid can also be used.

It is essential that the inert inorganic particles in the present invention have a ζ-potential of one charge in pure water.

As long as they fall within this range, they may be selected from natural particles or synthesized artificially.

For example, such particle groups whose ζ-potential is -charge include silicon oxide, titanium oxide, cerium oxide, chromium oxide, kaolinite, and talc.

Examples include zeolite carbon black and titanium nitride.

In some cases, particles such as magnesium oxide, calcium oxide, aluminum oxide, zirconium oxide, and calcium carbonate, which have a positive ζ potential in pure water, are surface-treated with an excess acid compound to bring the ζ-potential to one level. It is also possible to select from those modified to be charge.

In addition, depending on the need to control surface protrusions of molded products such as films and fibers, the particle size may be adjusted to 10 to 3000 mμ.
You can choose within the range. More preferably 15 to 20
00 mμ. If the particle size is less than 10 mμ, the surface irregularities are too fine and the running properties of the film are poor;
If it exceeds 000 mμ, the surface irregularities are too rough and it is difficult to maintain the abrasion resistance of the particles even with the structure of the present invention. Note that at least one type from among these particle groups may be used, but in some cases, two or more types may be used in combination.

In the present invention, the amount of inert inorganic particles added to polyester is 0.0 parts by weight per 100 parts by weight of polyester.
It is necessary to set it as 1-5.0 parts by weight. Preferably 0.
05 to 2.0 parts by weight.

If the amount exceeds 5.0 parts by weight, the surface flatness when formed into a film will be impaired, and as a result, the abrasion resistance will also be reduced, which is not preferable. On the other hand, if the amount added is less than 0.01 part by weight, when formed into a film, the surface roughness will be small and the running properties of the film will be poor, which is not preferable.

The surface treating agent for inert inorganic particles in the present invention is a compound having at least one amino group and at least one sulfonic acid group and/or sulfonic acid metal base. It is essential that the surface treatment agent has at least one amino group. Since the surface of particles whose ζ-potential is -charged acts as an acid, this amino group is necessary to connect the inert inorganic particles and the surface treatment agent through an acid-base bond. Furthermore, in order to impart an antistatic function, it is essential that the surface treatment agent contains at least one sulfonic acid group and/or sulfonic acid metal base. Although it is unclear why such sulfonic acid groups and/or sulfonic acid metal bases have antistatic ability, it is believed that the reason is improved conductivity due to water absorption ability.

Specific examples of such compounds include aminomethanesulfonic acid, aminoethanesulfonic acid, aminotoluenesulfonic acid, aminobenzenesulfonic acid, aminomethylbenzenesulfonic acid, aminonaphthalenesulfonic acid, aminonaphthalene disulfonic acid, and lithium of these compounds. ,
Examples include metal salts such as potassium and sodium, but other than these, any polymer compound may be used as long as it has at least one sulfonic acid group and/or sulfonic acid metal base. Note that two or more of these compounds may be used in combination.

In the present invention, the surface treatment amount of the surface treatment agent for inert inorganic particles is 0 parts by weight per 100 parts by weight of inert inorganic particles.
．． It is necessary to set it as 01-40 parts by weight. Preferably 0.
05 to 20 parts by weight, more preferably 0.1 to 1
It is 0 parts by weight. If the amount exceeds 40 parts by weight, the polymerization time may be delayed or the intrinsic viscosity of the polymer may become low, which is not preferable. On the other hand, if it is less than 0.01 part by weight, the desired antistatic performance will be insufficient, which is not preferable.

Methods for treating inert inorganic particles with such surface treatment agents include, for example, spraying an aqueous solution of these surface treatment agents on dry inert inorganic particles and then drying them, or spraying the inert inorganic particles with water. Alternatively, the surface treatment agent may be suspended in a slurry or other solvent, and the surface treatment agent may be added to the slurry for wet treatment. Further, at this time, physical treatments such as dispersion and pulverization may be performed at the same time. Various methods are known for dispersing and pulverizing, and for example, methods using ultrasonic waves, methods using high-speed stirring, methods using a media type mill, etc. may be selected depending on the desired particle size. In addition, when carrying out such surface treatment, it is more preferable to collect the surface treatment agent evenly and efficiently around the particles. Therefore, it is generally preferable to use a wet method such as the latter.

Next, a specific example of the method for producing polyester of the present invention will be described in detail using polyethylene terephthalate (PET) as an example. When incorporating particles into PET under the conditions of the present invention,
A method in which a reaction product obtained by an esterification reaction of terephthalic acid and ethylene glycol is subjected to a polycondensation reaction (direct polymerization method), and a reaction product obtained by an ester exchange reaction between dimethyl terephthalate and ethylene glycol is subjected to a polycondensation reaction. It can be obtained by any method (transesterification method).

More specifically, first of all, in the case of the direct weight method, terephthalic acid and ethylene glycol are subjected to an esterification reaction at a temperature of 240 to 280°C in the presence of a catalyst or in the absence of a catalyst, and the reaction rate is 95% or more. Get the product. Thereafter, an ethylene glycol-soluble metal, a phosphorus compound, and the above-mentioned inert inorganic particles are added, and then a polycondensation reaction is carried out at 230 to 300° C. under reduced pressure to obtain the desired PET composition. Note that these compounds may be added at the same time or whichever comes first, but it is preferable to add the inert inorganic particles after adding the metal compound and the phosphorus compound, and the addition interval is 5 ~60 minutes, preferably 10-3
It is 0 minutes. If the time is less than 5 minutes, the inert inorganic particles tend to aggregate, and if it exceeds 60 minutes, not only will the dispersibility not improve any further, but the softening point of the polyester will decrease, and the time cycle will be delayed, resulting in reduced productivity. This is undesirable because it causes deterioration. Moreover, it is preferable to add the above-mentioned inert inorganic particles before the intrinsic viscosity reaches 0.3. If the inert inorganic particles are added after the intrinsic viscosity reaches 0.3, the inert inorganic particles will not be uniformly mixed due to the high melt viscosity of the reaction system, which is not preferable.

Second, in the case of the transesterification method, dimethyl terephthalate and ethylene glycol are transesterified at 140 to 240°C to obtain a reaction product. As the transesterification reaction catalyst, common metal compounds can be used. Furthermore, the metal compound can be added again after the transesterification reaction is substantially completed. The phosphorus compound is added after the transesterification reaction, but if a metal compound other than the transesterification catalyst is added after the transesterification reaction, it is preferably added after the addition of the metal compound. Although there is no particular restriction on the timing of addition of inert inorganic particles, it is preferable to add them before the intrinsic viscosity reaches 0.3, as in the above-mentioned direct loading method. The above reaction product is 230
Polycondensation reaction is carried out at ~300℃ under reduced pressure to produce the desired PET.
Obtain a composition.

Moreover, when manufacturing a film using the polyester composition synthesized by both methods, conventionally known film manufacturing methods can be applied. For example, a polyester composition containing inert inorganic particles within the range described in this application is melt-cast to form an amorphous unstretched film, and then the unstretched film is stretched in the direction of the two wheels, heat-set, and as necessary. If available, it is manufactured by subjecting it to relaxation heat treatment. Here, the film surface properties change depending on the particle size and content of inert inorganic particles in the polyester, or the stretching conditions.
Stretching conditions are selected appropriately. In addition, the voids, density, and heat shrinkage rate of the film are also determined by the stretching ratio.

Since the properties vary depending on the drawing speed, heat treatment temperature, etc., conditions are selected that simultaneously satisfy these properties. For example, the stretching temperature may vary from (Tg-10)°C to (Tg+45) at the −th stage (for example, longitudinal stretching temperature: T1)
'C range (where Tg is the glass transition temperature of polyester) to the second-stage stretching temperature (for example, the transverse stretching temperature
2) from (T1 + 15) °C to (T1 + 40)'C
It is recommended to select from the range of . Further, the stretching ratio is preferably selected from a range in which the stretching ratio in the -axial direction is 2 times or more, more preferably 2.5 times or more, and the area ratio is 6 times or more, more preferably 8 times or more. In addition, the heat fixation temperature is 1
80°C to 250°C, more preferably 200°C to 2
It is best to choose from a range of 30°C.

This makes it possible to obtain a biaxially stretched polyester film with improved abrasion resistance even when running at high speed. This two-wheel stretched polyester film is preferably used as a base film for magnetic recording media, especially for magnetic tapes, but is not limited to this, and can be used in other fields such as electrical applications, packaging applications, and vapor deposition applications. can also be widely applied. Furthermore, the thermoplastic polyester resin of the present invention exhibits excellent effects not only on films but also on fibers and other engineering plastics.

[Example] The present invention will be explained in detail in the following example. Note that each characteristic value was measured according to the following method.

(A) Average particle diameter The primary diameter of the particles was measured using a scanning electron microscope.

(B) ζ-Potential of Particles Particles were added to pure water to form a dilute slurry, and measured by a conventional electrophoresis method.

(C) Intrinsic viscosity of polymer Measurement was carried out at 25°C using 0-chlorophenol as a solvent.

(D) Average surface roughness of film (Ra) J I 5-B
-0601, using a stylus surface roughness meter with a cutoff of 0°08mm and a measurement length of 4mm.
It was measured as

(E) Friction coefficient of film Measured using a slip tester according to ASTM-D-1894B method. The coefficient of dynamic friction (μd) was used as a measure of the slipperiness of the film.

(F) Charge potential half-life time Shishido Shokai Static Honest Meter S-410
Using Type 4, apply a voltage of -5 kV to the sample [2 cm to 3 cm].
This is the time (seconds) it takes for the potential generated on the sample to decay to 1/2 of the value when applied for 0 seconds (20°C, 65%RH)
.

The time is preferably 10 seconds or less.

Example 1 0.1 part by weight of calcium acetate was added as a catalyst to 100 parts by weight of dimethyl terephthalate and 64 parts by weight of ethylene glycol, a transesterification reaction was carried out by a conventional method, and 0.04 part by weight of antimony trioxide was added. 0.04 parts by weight of trimethylphosphene was added to form the reaction product (X).
I got it.

On the other hand, (A) 10 parts by weight of silicon oxide having a particle size of 220 mμ (ζ-potential of pure water system - 56 mV), 89.8 parts by weight of ethylene glycol, and (B) 1 cum of p-aminobenzenesulfonic acid. A slurry (Y-1) was obtained by dispersing 2 parts by weight using a common sand grinder. Next, the above reaction product (X) was melted at 220°C, and 3.0 parts by weight of the above slurry (Y-1) was added thereto.
After stirring and holding at 5° C. for 20 minutes, the mixture was transferred to a polycondensation reaction tank, and a polyester composition (C) having an intrinsic viscosity of 0.617 and a carboxyl terminal group concentration of 48 eq/l was obtained by a conventional method.

Next, the obtained polyester composition was melt-extruded using an extruder at 290°C and rapidly cooled using a casting drum to obtain an unstretched sheet.

Subsequently, this was stretched 3 times in the longitudinal and transverse directions at 90° C. and heat-set at 220° C. for 10 seconds to obtain a biaxially stretched film with a thickness of 20 μm. Table 1 shows polymer properties and film properties.
As shown in , the biaxially stretched film had good Ra, coefficient of dynamic friction, and antistatic properties.

Comparative Example 1 Example 1 except that the surface treatment of the inert inorganic particles was not performed.
A polyester composition and a biaxially stretched film were obtained in the same manner as above. Table 2 shows the properties of the obtained film. As is clear from this table, the obtained two-wheel stretched film did not have sufficient performance in both dynamic friction coefficient and antistatic properties.

Examples 2 to 4 As shown in Table 1, inert inorganic particle species 1 particle average diameter,
A polyester composition and two-wheel stretched film were obtained in the same manner as in Example 1, except that the amount of ζ-potential 1 particles added and the type and amount of surface treatment agent added were changed. The properties of the obtained polymer and film are shown in Table 1, including Ra, coefficient of dynamic friction,
The biaxially stretched film had good antistatic properties.

Comparative Examples 2 to 5 Example 1 was carried out by changing the average diameter of two inert inorganic particles, the amount of ζ-potential added per particle, and the type and amount of surface treatment agent added.
A polyester composition and a biaxially stretched film were obtained in the same manner as above. The resulting polymer.

The properties of the film are shown in Table 2. As is clear from this table, a biaxially stretched film with sufficient performance could not be obtained because the coefficient of dynamic friction was high and the antistatic property was poor. Furthermore, if the ζ-potential was +charged or the amount of surface treatment agent added was large, the polymerization time would be delayed or breakage would occur during film formation, making it impossible to obtain a satisfactory stable product.

[Effects of the Invention] The polyester composition of the present invention is blended into polyester after inert inorganic particles are surface-treated with a special compound. , the antistatic properties are improved.

Therefore, the polyester composition of the present invention exhibits an effective antistatic effect when molded into fibers, films, or other molded products. In particular, it is suitable as a film for magnetic tape that is used repeatedly due to contact friction.

Claims (1)

[Claims] At least one inert inorganic particle with an average particle diameter of 10 to 3000 mμ and a ζ-potential of -charge in pure water is added to a polyester mainly composed of aromatic dicarboxylic acid and glycol and whose main repeating unit is an aromatic carboxylate. The surface is treated with 0.01 to 40 parts by weight (based on 100 parts by weight of inert inorganic particles) of a compound having an amino group and at least one sulfonic acid group and/or sulfonic acid metal base. An antistatic polyester composition containing .0 parts by weight.