JPS61231046A - Polyester film - Google Patents

Abstract

PURPOSE:To reduce the formation of coarse particles and to improve lubrivity, wear resistance, etc., by incorporating fine particles of an CONSTITUTION:An arom, dicarboxylic acid component and an ethylene grlycol componenta are polycondensed to obtaina polyester.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a biaxially stretched polyester film that has excellent slipperiness and abrasion resistance and has few coarse protrusions.

Biaxially oriented polyester films, especially polyester/terephthalate, have excellent mechanical properties, electrical properties, chemical resistance, dimensional stability, etc., and are therefore used for magnetic recording, capacitors, packaging, plate making, etc. It is used as a base material in many fields such as electrical disconnection and photographic film.

The properties required for such a polyester film differ depending on its use, but the universally desired property is workability when handling the film, and in order to improve this, it is necessary to reduce the film's slipperiness, that is, the coefficient of friction. There is a need to.

In addition, base films for magnetic recording media for audio, video, and computer applications, which have been growing rapidly in recent years, have not only a low coefficient of friction but also good wear resistance. It is desirable that the formation of small amounts of substances such as

Many methods have been proposed to improve these properties required for polyester films, including the use of antistatic agents and lubricants, but the amount currently available is limited due to various factors such as effectiveness, reliability, and cost. A commonly used method is to include fine particles that are inert to polyester in the film.

This method can be broadly divided into two. One of these is the precipitation method, in which one or more metal compounds soluble in ethylene glycol, such as calcium compounds and lithium compounds, are added before and after the transesterification reaction or esterification reaction, and the polyester manufacturing process, especially the polymerization process, is carried out. This is a method in which these are precipitated as fine particles insoluble in polyester during the process. In this case, there is also a method of obtaining precipitated particles under conditions in which one or more phosphorus compounds coexist.

However, when attempting to improve the lubricity using these precipitated particles, the amount and particle diameter of the precipitated particles tend to change, making it difficult to control the lubricity. Furthermore, since the amount of precipitated particles is limited, it is difficult to increase the concentration, and furthermore, when a polyester film containing the particles is recycled, it no longer retains its original slipperiness.

Although precipitated particles have the advantage of having excellent affinity with polyester because they contain many organic components, it is also well known that a sufficient improvement in wear resistance cannot be achieved with precipitated particles alone.

In this method, calcium carbonate, calcium sulfate, kaolin, silica, titanium dioxide, etc. are added as they are or after being made into fine particles during polyester synthesis or molding. Although the method of adding these inorganic compounds allows the particle size and amount of fine particles to be controlled and the reproducibility of the results is good, it is extremely difficult to uniformly disperse them in polyester, which is an organic substance.

Furthermore, according to the knowledge of the present inventors, some of these inorganic compounds, such as calcium carbonate and calcium sulfate, have been thoroughly classified in advance to remove coarse particles. It has poor properties and often forms rough protrusions on the film.

The present inventors conducted intensive studies based on this knowledge, and found that the cause of coarse particles is not only the remaining coarse particles due to insufficient classification operations, which have been pointed out in the past, but also the aggregation of particles during the polyester manufacturing process. It was discovered that there is another cause, namely coarsening due to part of the particles dissolving and re-precipitating.

As a result of paying attention to the reduction of coarse particles due to redecipitation, the above problems can be solved at once by using organic metal salt fine particles that have extremely low solubility in ethylene glycol. The inventors have discovered that a polyester film containing fine particles has excellent slipperiness and abrasion resistance, and produces significantly less coarse particles, leading to the present invention.

That is, the present invention uses particles having an average particle size of 0.01-8% by weight or less and having a solubility in ethylene glycol at 20°C.
The present invention relates to a biaxially stretched polyester film containing 0.001 to 3 g of a 10 μm organic metal salt.

The present invention will be explained in detail below.

The polyester referred to in the present invention refers to a polyester containing aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, naphthalene-λ, and t-dicarboxylic acid, or esters thereof, and glycols such as ethylene glycol, tetramethylene glycol, neopentyl glycol, etc. In addition to being obtained by direct polycondensation of products that can be obtained by condensation, polycondensation is performed after a glycol triester exchange reaction with an aromatic dicarboxylic acid dialkyl ester, or by polycondensation of a diglycol ester of an aromatic dicarboxylic acid. It can also be obtained by methods such as

Typical examples of such polymers include polyethylene terephthalate, polyethylene co, and 6-s7talate. This polymer may be a homopolymer or may be a copolymer of a third component. In any case, in the present invention, polyesters having 10 moles or more of ethylene terephthalate units and/or ethylene-2,t-naphthalate units are preferred.

Next, regarding the organic metal salt used in the present invention, the organic metal salt has a solubility in ethylene glycol at 0°C of 0.1% by weight or less, preferably 0.0%.
j % or less, more preferably 0.07% by weight or less. Further, in order to prevent melting during polyester polymerization, its melting point must be 300°C or higher.

Such organic metal salts are preferably polyvalent carbo/acid metal salts, and examples of metals include alkaline earth metals, cadmium, nickel, and the like. Specifically, calcium oxalate,
Barium oxalate, strontium oxalate, cadmium oxalate, nickel oxalate, calcium citrate,
Quell barium, calcium tartrate, etc. can be mentioned. Among these, alkaline earth metal salts of polyhydric carboxylic acids are preferred. Among these, oxalates, particularly calcium oxalate, are preferably used because of their extremely low solubility in ethylene glycol.

Usually, when particles are added to a polyester manufacturing process, they are added as an ethylene glycol slurry for various reasons such as automation, ease of metering, improved dispersibility, and simplification of the recovery system.

The slurry is added preferably after the transesterification reaction or the esterification reaction and before the polycondensation reaction.

In this case, if the solubility of the particles in ethylene glycol is high, the dissolved portion will precipitate as the reaction progresses, often forming coarse particles.

Furthermore, coarse particles are formed due to this reason not only in ethylene glycol near room temperature, but also when the solubility in heated ethylene glycol and polyester oligomers is high; can often be substituted with.

From this point of view, in the present invention, it is necessary to use an organic metal salt whose solubility in ethylene glycol at 20°C is 0.1% by weight or less, and for example, if this value is about 12% by weight,
Calcium terephthalate is unsuitable as an organometallic salt for use in the present invention.

In addition, the average particle size of the organic metal salt is 0.0/~10μ
, preferably 0. / must be −jμ. If the average particle size is less than 0.07μ, the lubricity and abrasion resistance of the film will not be improved; on the other hand, if this value exceeds 10μ, the filter permeability during film formation will deteriorate and the resulting film will be As so-called marbling becomes more common, product prices are significantly reduced. Also, as a matter of course, many coarse protrusions are present on the film surface, making it impossible to use it for high-grade film applications.

The amount of the organic metal salt added to the polyester film is 0.00/~3% by weight, preferably o, o o
r~1% by weight, more preferably 0,0/~o3wt-
selected from the range. If this amount is less than 0.007% by weight, no improvement effect on lubricity or abrasion resistance will be observed, while if this amount exceeds 3% by weight, filter permeability will deteriorate and particles will overlap frequently. As a result, coarse protuberances occur frequently.

As described above, the present invention is characterized in that a polyester film contains a specific amount of an organic metal salt having a specific particle size that is sparingly soluble or insoluble in ethylene glycol, but within the scope of the spirit of the invention. Other particles, such as the above-mentioned precipitated particles or inorganic salt fine particles, may be used in combination.

Note that the organic metal salt used in the present invention is normal! It is added as an ethylene glycol slurry of ~30% by weight to the polyester manufacturing process, preferably after the transesterification reaction or esterification reaction and before the start of the polycondensation reaction, but if necessary, it is pulverized and classified in advance to make the particle size uniform. You can also do that. Any method can be used to crush and classify the particles. For example, for crushing, a rod mill,
Ball mill, vibrating rod mill, vibrating ball mill, pan mill, roller mill.

Impact mills, disk mills, stirring mills, fluid energy mills, etc. can be used, and for classification, semi-free whirlpool type, forced whirlpool type, hydrocyclone type, centrifugal separation method, R-compliant method, etc. can be used. You can use the above.

Known methods can be used to polymerize polyester containing such organic metal salts. For example, using one or more of antimony compounds, germanium compounds, titanium compounds, etc. as catalysts for polycondensation reactions, heating to 230°C to 300°C and distilling ethylene glycol under reduced pressure.
Make the reaction proceed further.

In addition, when forming a film, a known film forming method such as 2
After melting and extruding polyester chips into a film at 70~JOO℃, cooling and solidifying at 70℃~70℃ to form an amorphous sheet, biaxially stretching or simultaneous biaxially stretching in length and width.
A method such as heat treatment at 40 to 2170° C. (for example, the method described in Japanese Patent Publication No. 3 O-j632) can be employed.

EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to the following Examples as long as the gist thereof is not exceeded.

The various physical properties were measured using the following methods.

Solubility of particles in ethylene glycol; Experimental Chemistry Course (published by Maruzen, Showa ≠ 2nd year) No.! The solubility measurement method (analytical method) described in Vol. ≠ page 00 was used.

Average particle size; determined by microscopy. That is, the particles or polyester containing particles were photographed using an optical microscope or an electron microscope, and then the maximum particle size was measured. The average particle diameter is determined by calculating the weight distribution of the particle group having the maximum diameter, and then calculating the weight fraction by 0.
It is expressed by the diameter of the point 9, and refers to the diameter of the 9 grains.

Smoothness: Represented by friction coefficient, friction coefficient is AEITMD
-/According to 1917, the tape-shaped sump is 120■/
It is min. Measurements were made at a temperature of 21°C and a humidity of t! ±! −
It was conducted in an atmosphere of

Abrasion resistance: The film was run over the length of the room using the running system shown in Figure 1, and the amount of wear attached to the hard chrome fixing pins of tφ shown in (I) was visually evaluated and divided into the dents and scratches shown below. .

The film speed was set to /Om/min, and the tension was set to approximately JOofbθ=/J00.

Rantum: Does not adhere at all.

Rank B: Slight adhesion.

Rank C: Large amount of adhesion.

Filter f permeability: When extruding molten polymer at r, j kg/hr using a 21,000 mesh filter with a filtration area of 30 aA, the pressure of the filter population is /
! The extrusion amount (converted to ton/rp?) until reaching Okl/- was measured. The larger this value is, the better the filter resistance is.

Example 1 (Preparation of ethylene glycol slurry of calcium oxalate) Average particle size approx. Calcium oxalate having an average diameter of 0 μ was pulverized using a jet mill and then subjected to air classification to obtain fine calcium oxalate powder having an average particle size of 0 μ.

Next, a 70 weight ethylene glycol slurry of the calcium oxalate fine powder was prepared and subjected to ultrasonic dispersion treatment.

The solubility of calcium oxalate at 0°C was investigated and found to be approximately 0.002% by weight.

(Manufacture of polyester) dimethyl terephthalate ioo
parts, 70 parts of ethylene glycol and 0 parts of calcium acetate.
．． 10 parts were placed in a reactor and the temperature was raised by 9 degrees, methanol was distilled off, and transesterification was carried out. After the start of the reaction, about μ
It took some time to reach 230°C, and the transesterification reaction was substantially completed.

Next, this transesterification product was added with triethylphosyl
x-) 0. Ot part s Altimony dioxide O, Oa
and 3 parts of an ethylene glycol slurry of 10 parts by weight of calcium chelate having an average particle diameter of 0 μm prepared in advance were added thereto, and polymerization was carried out in accordance with a conventional method. That is, 100 minutes after adding antimony trioxide, the temperature was increased to 210°C and the pressure was increased to I! rrm
After reaching Hg, the pressure was gradually reduced.

After μ time, the pressure inside the system was returned to normal pressure and the polymer was discharged to obtain polyethylene terephthalate (A) having an intrinsic viscosity of o and tz.

(Manufacture of polyester film) Polyester (A) was extruded into a sheet using an extruder at 0°C, rapidly cooled to form an amorphous sheet, and then 3. Stretched to j times and heat treated at 2JO℃ to a thickness l! A biaxially stretched polyethylene terephthalate film of μ was obtained.

The properties of the obtained polyester film are shown in Table 1. Like the other examples, the filter life during film formation was long, and the lubricity, abrasion resistance, and coarse protrusions were all at satisfactory levels. there were.

Example λ A polyester (B) was obtained in the same manner as in Example 1 except that calcium oxalate and aluminum were not added. A polyester film was obtained in substantially the same manner as the particles in the polyester. The results are shown in Table 1.

Example J A polymer was obtained in the same manner as in Example 1 except that the average particle size and amount of calcium oxalate added in Example/4C were changed.
Next, a polyester film was obtained in the same manner as in Example 1. The conditions and results are shown in Table 1.

Example μ In place of calcium oxalate in Example 1, barium oxalate (average particle size Heko μ) having a solubility in ethylene glycol at 20° C. of about 0.007 wt.
A polyester was obtained in the same manner as in Example 1, except that the same amount of polyester was used, and then a biaxially stretched polyester film was obtained. The evaluation results of the film are shown in Table 1.

Example! In producing the polyester of Example 1, a transesterification reaction was carried out in the same manner as in Example 1, except that 0.13 parts of lithium acetate and o and or parts of calcium acetate were used in place of 0.10 parts of calcium acetate.

Next, after adding 0.127 parts of triethyl phosphate and 4 parts of antimony trioxide, a polycondensation reaction was carried out according to a conventional method to obtain a polyester having an intrinsic viscosity of 0.12.
0) was obtained.

A large number of fine precipitated particles with average particle diameters of about o and rμ were observed in the polyester (0).

Next, polyester (A) and polyester ((:ritot
/: Hiroshi (weight ratio) After blending, film formation was performed in the same manner as in Example 1. The properties of the obtained film were
Shown in the table.

Comparative Example 1 In place of calcium oxalate in Example 1, the average particle size was
of calcium carbonate 0. A polyester was obtained in the same manner as in Example 1 except that 0 part of J was used, and then a biaxially stretched film was obtained.

The properties of the obtained film are shown in Table 1, and it shows that it has many coarse protrusions and the life of the filter during film formation is short.

Comparative Example 2 Table 1 shows the results when using calcium terephthalate, which is an organic salt but is relatively well soluble in ethylene glycol. More coarse protrusions were observed than in Examples.

Comparative Example 3 A biaxially stretched film was obtained in the same manner as in Example 1 using the polyester (0) obtained in Example≠.

Although this film had few large protrusions and was excellent in filter life, it was unsatisfactory in terms of cleanability and abrasion resistance.

Results of the Invention As detailed above, the film of the present invention has excellent affinity with polyester and polyester, and has fewer aggregated particles, as well as significantly fewer coarse particles due to dissolution and reprecipitation, which is an unprecedented feature. has. In addition, it has excellent durability and abrasion resistance, so it can be used in a wide range of applications such as magnetic tapes, vapor deposition, capacitors, and packaging.

[Brief explanation of drawings]

Figure 1 shows the running system for evaluating wear resistance, and (I) is t
Hard chrome fixing pin of 111IIφ, (■) indicates a tensor meter, and θ is / j O'. Applicant: Diafoil Co., Ltd. Agent: Patent attorney: Yo Hase - 1 other person

Claims (1)

[Claims] (1) Average particle size of 0.01 to 10μ with solubility in ethylene glycol at 20°C of 0.1% by weight or less
A biaxially oriented polyester film containing 0.001 to 3% by weight of an organic metal salt.