JPH07103247B2 - Polyester composition and film comprising the composition - Google Patents

Description

TECHNICAL FIELD The present invention relates to a polyester composition and a film comprising the composition, and more specifically, it has excellent abrasion resistance, slipperiness and surface property when formed into a film, It also relates to a polyester composition that gives a film having excellent transparency.

[Problems to be Solved by Prior Art and Invention]

The biaxially stretched polyester film typified by polyester film, especially polyethylene terephthalate, has excellent characteristics, and thus can be used for magnetic tapes, capacitors, packaging materials,
It is used as a base film in a wide range of fields such as photoengraving.

The properties required of such a polyester film differ depending on the application, but generally it is necessary that it has good wear resistance, excellent slipperiness, and that it has few rough surface protrusions.

In order to improve these abrasion resistance and slipperiness, a technique of giving fine irregularities to the film surface has been conventionally used. As a method for providing such fine irregularities, a method of adding fine particles inactive to polyester during the polyester manufacturing step or extrusion step to form protrusions on the film surface (hereinafter referred to as "added particle method").
Is well known.

When performing the additive particle method, what is important is the selection of particles, and if the type of particles is different, the slipperiness of the film, abrasion resistance, the degree of rough surface projections, and the transparency will be different. Although it has been found that calcium particles, silica particles, titanium dioxide particles, kaolin particles, and the like are preferable as particles to be used in view of these characteristics, calcium carbonate is particularly excellent in that it is easy to slip and has very few rough surface protrusions.

However, a film formed by biaxially stretching a composition using calcium carbonate has a problem that the particles themselves fall off. Originally, the interaction and affinity between calcium carbonate and polyester are small, and especially when a polyester with calcium carbonate added is biaxially stretched to form a film, the stretching stress acts on the particle surface and the polyester in the vicinity of the particle surface. A space (hereinafter referred to as “internal void”) is generated by the peeling, and the particles are easily dropped off by a slight external force. The presence or absence of internal voids, the size of the film can be easily determined by observing the inside of the film with a polarizing microscope.Since this internal void part has a large difference in refractive index from the polyester itself, when the volume and number of internal voids increase, It also reduces the transparency of the entire film (increased haze inside the film).

On the other hand, in the case of a composition containing calcium carbonate particles, the productivity at the time of forming a film, that is, the increase in the film formation rate has not always been sufficiently achieved, and higher productivity has been desired.

[Means for solving problems]

The inventors of the present invention have made extensive studies in view of the above problems, and contain calcium carbonate which has been subjected to a specific surface treatment, and the specific resistance during melting is a polyester composition in a specific range, The inventors have found that the particles have excellent affinity for polyester when they are formed into a film, and also improve productivity, and have completed the present invention.

That is, the gist of the present invention is a particle mainly composed of calcium carbonate having an average particle size of 0.05 to 5 μm, wherein the alkylene has a carbon number of 1 to 4 and a polyalkylene glycol unit and / or a polyacrylic acid unit and / or polyacrylic acid. The particles obtained by surface treatment with a copolymer containing an alkali metal salt, an alkaline earth metal salt or an ammonium salt unit of an acid are contained in an amount of 0.001 to 10% by weight, and a specific resistance when melted is 1
The polyester composition and the film made of the composition are characterized by being in the range of x10 ⁶ to 1x10 ⁸ Ω · cm.

Hereinafter, the present invention will be described in detail.

The polyester referred to in the present invention refers to a polyester obtained from an aromatic dicarboxylic acid such as terephthalic acid or naphthalene-2,6-dicarboxylic acid or an ester thereof and ethylene glycol as main starting materials. You may contain the component. The third component is appropriately selected from isophthalic acid as the aromatic dicarboxylic acid component, and propylene glycol, tetramethylene glycol, neopentyl glycol or the like as the glycol component.

In the present invention, the particles containing calcium carbonate as a main component for improving the surface properties and the slipperiness of the film by being contained in the polyester include a synthetic method by the reaction of calcium hydroxide suspension and carbon dioxide gas, so-called Those having a calcite structure synthesized by the carbon dioxide gas synthesis method are preferable. More preferably, by incorporating an Sr (strontium) compound and / or a Ba (barium) compound into the particles, the dispersibility of the obtained particles is further improved and the particle size distribution is sharper. These strontium compound and barium compound are added before or during the particle synthesis reaction.

Examples of the strontium compound coexisting in calcium carbonate include strontium carbonate, sulfate,
Examples thereof include chlorides, hydroxides and oxides. Examples of the barium compound include barium carbonate, sulfate, chloride, hydroxide, and oxide. The content of these strontium compounds and / or barium compounds is 0.001 to 5% by weight, preferably 0.005 to 5% by weight, more preferably 0.01 to 4% by weight, based on the total amount of calcium carbonate containing them. Strontium compound and / or barium compound content is 0.00
If it is less than 1% by weight, the dispersibility of the particles in a medium such as ethylene glycol and polyester is not sufficient, which is not preferable. Further, if the content exceeds 5% by weight, no further effect of improving the dispersibility is recognized, and the cost is rather increased, which is not preferable.

The average particle size of calcium carbonate in the present invention is 0.05 to 5
It is in the range of μm. If it is less than 0.05 μm, the slipperiness and abrasion resistance of the obtained film are insufficient, and if it exceeds 5 μm, the surface roughness of the obtained film becomes excessive, which is not preferable.

In order to obtain particles having a desired particle size, after synthesizing particles having a particle size slightly larger than the desired particle size by appropriately adjusting the reaction conditions in the step of synthesizing calcium carbonate by the carbonation reaction. This is crushed to a desired particle size by using a crushing device such as an agitation grinding mill (sand grinder), a ball mill, a rod mill, etc., and coarse particles and contaminants are removed by dry classification, wet classification, etc.

Next, the surface treatment method of particles in the present invention will be described.

In the present invention, the surface treatment is carried out by adding a surface treatment agent before or during the step of pulverizing the calcium carbonate particles which have been synthesized by the carbonation reaction to a desired particle size. By such treatment, surface treatment is sufficiently performed on the new surface with high surface energy generated by pulverization,
The surface treatment of the particles as a whole is sufficiently achieved.

As the surface treatment agent, it is necessary to use a polymer containing a polyalkylene glycol unit having an alkylene carbon number of 1 to 4 and a polyacrylic acid unit and / or a polyacrylic acid derivative unit. As such a copolymer, for example, a copolymer of polyacrylic acid and polyethylene glycol monomethacrylate, a copolymer of polyacrylic acid and methoxypolyethylene glycol and polypropylene glycol monomethacrylate, or a partial copolymer of these polyacrylic acids with ammonia. Examples thereof include, but are not limited to, those neutralized with and those replaced with sodium polyacrylate.

These surface treatment agents are added to a slurry in which calcium carbonate particles are dispersed in water, ethylene glycol or the like, and the surface treatment is performed by pulverizing. The amount of the surface treatment agent added is not particularly limited, but is preferably 0.1 to 5% by weight with respect to the total amount of particles. If it is less than 0.1% by weight, the surface treatment effect is often insufficient, and if it exceeds 5% by weight, agglomeration between particles or the treatment agent itself occurs, which is not preferable.

In the present invention, the content of added particles in the polyester composition is 0.001 to 10% by weight. If it is less than 0.001% by weight, the slipperiness and abrasion resistance of the obtained film are insufficient, and if it exceeds 10% by weight, the surface roughness of the film becomes excessive, which is not preferable.

In the production of the polyester composition of the present invention, the additive particles are preferably added during the polyester synthesis reaction. In particular, it is preferable to add before the transesterification reaction or the esterification reaction, during the transesterification reaction or the esterification reaction, or after the completion of the transesterification reaction or the esterification reaction and before the start of the polycondensation reaction.

In addition to surface-treated calcium carbonate particles, fine particles of titanium dioxide, silica, kaolin, zeolite or the like may be used in combination in the polyester composition of the present invention. In addition to such fine particles, internal particles precipitated by the reaction of the catalyst residue and the phosphorus compound in the polyester polycondensation reaction system may be used in combination.

Further, the polyester composition of the present invention is required to have a specific resistance when melted of 1 × 10 ⁶ to 1 × 10 ⁸ Ω · cm.
A range of × 10 ^{6 to} 5 × 10 ⁷ Ω · cm is desirable. If the specific resistance during melting is less than 1 × 10 ⁶ Ω · cm, the thermal stability of the polymer deteriorates and it becomes difficult to form a film. On the other hand, the specific resistance during melting is 1
If it exceeds × 10 ⁸ Ω · cm, the cooling method using electrostatic charge (Japanese Patent Publication No. 37-6
An excellent method for producing an unstretched sheet described in Japanese Patent Publication No. 142, etc. However, it is difficult to increase the film-forming speed and the productivity of the film is extremely deteriorated. The specific resistance at the time of melting is adjusted by solubilizing a metal compound in polyester, usually after the transesterification reaction, the transesterification reaction catalyst, for example, a magnesium compound, a lithium compound, etc., 0.3 to 1.0 times equivalent, Preferably 0.4-
It is carried out by adding 0.8 times the equivalent of a phosphorus compound.

The polyester composition of the present invention is melt extruded into a non-stretched sheet on a rotary cooling drum (preferably using the above-mentioned electrostatically applied cooling method), and is 80 to 130 ° C. in the longitudinal direction 2 to 10 times, 8 times.
The film can be stretched at a temperature of 0 to 140 ° C in the transverse direction by 2 to 10 times at a time or at the same time, and if necessary, again stretched, and then heat treated at 160 to 240 ° C to form a film, but it is not limited to this method. However, the conditions are appropriately selected depending on the intended use of the film.

In addition, a coating layer may be provided on the film surface or corona treatment may be performed to impart adhesiveness and slipperiness to the film.

〔Example〕

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples.

The methods for evaluating physical properties and characteristics in the present invention are shown below.

(1) Average particle diameter of added particles mainly composed of calcium carbonate The particle diameter was measured by a centrifugal sedimentation method using SA-CP3 manufactured by Shimadzu Corporation.

(2) Sliding property of film Sliding property was evaluated by measuring the friction coefficient according to the method of ASTM D1894-63.

(3) Abrasion resistance of the film The abrasion resistance was evaluated by using the running system shown in FIG.
6mmφ pin (SU
The amount of the S420J2 surface finish 0.2S) adhering to the surface due to wear was visually evaluated and expressed by the following ranks. The running speed of the film was 10 m / min, the tension was about 500 g, and the winding angle (θ) with the pin was 135 °.

○: Almost no adhesion.

△ …… Slightly adheres.

×: There is a large amount of adhesion.

(4) Affinity between added particles and polyester As an evaluation of the surface treatment effect, that is, the affinity between added particles and polyester, the size of voids around the particles inside the film was observed with a polarizing microscope, and the following ranks were used. Represented.

○ …… Voids are not seen in the majority of particles.

△: The number of particles with voids is slightly large.

×: Extremely large voids are seen around the majority of particles.

(5) Haze inside the film According to the method of ASTMD1003-61, turbidimeter N manufactured by Nippon Denshoku Co., Ltd.
Using DH-2A type, liquid paraffin was applied to both sides of the film and measured.

(6) Number of Coarse Protrusions Aluminum was vapor-deposited on the film surface, and the number was measured using a two-beam interference microscope. The number showing the n-th order interference fringes at the measurement wavelength of 0.54 μ is converted and shown per 25 cm ² . The number of protrusions of 4th order or higher is shown as F ₄ , and the number of protrusions of 3rd order or higher is shown as F ₃ .

(7) Surface roughness (Ra) It was measured by the method described in JIS B0601-1976.

For the measurement, a surface roughness measuring instrument model SE-3F manufactured by Kosaka Laboratory was used, and the stylus diameter was 2μ, stylus load was 30mg, and cutoff value was 0.08mm.
And

(8) Specific resistance of polyester when melted British Journal of Applied Physics (Brit.J.Appl.Phys.) Volume 17, 1149-1154
The method described on page (1966) was followed. However, in this case, the temperature at the time of melting the polymer composition is 290 ° C.
The value immediately after applying 000 V was taken as the specific resistance during melting.

In the examples, "part" or "%" means "part by weight" or "% by weight" unless otherwise specified.

Example 1 [Synthesis of calcium carbonate particles] Lime milk containing calcium hydroxide at a concentration of 200 g / 20
Was heated to 60 ° C., 16.2 g of SrCO ₃ (amount of 0.3% based on the produced calcium carbonate particles) was added, and the mixture was stirred and mixed, and carbon dioxide gas having a carbon dioxide concentration of 25% by volume was added to 400 /
It was introduced at a rate of h and the reaction was carried out with stirring. After reacting for 24 hours, the blowing rate of carbon dioxide gas was set to 4 / h and the reaction was continued for 14 days to obtain the average particle size of the calcite structure.
A 1.0 μm SrCO ₃ -containing calcium carbonate water slurry was obtained.

[Surface treatment process]

As a surface treatment agent, a copolymer of sodium polyacrylate, methoxy polyethylene glycol (methoxy PEG) and polypropylene glycol monomethacrylate (PPG monomethacrylate) in the above calcium carbonate water slurry becomes 1.0% based on the particles. , Then pulverized with a sand grinder to give an average particle size of 0.55μ.
A m particle slurry was obtained. The obtained slurry was dehydrated by a filter press and dried, and then dispersed in ethylene glycol using a TK homomixer manufactured by Tokushu Kika Kogyo. This ethylene glycol slurry is pulverized using a sand grinder to obtain a particle slurry having an average particle size of 0.52 μm, which is subjected to wet classification and filtration to obtain an average particle size of 0.50 μm.
A 20% strength ethylene glycol slurry of m was obtained.

[Production of polyester composition]

100 parts dimethylene terephthalate and 6 ethylene glycol
0 parts and 0.09 parts of magnesium acetate / tetrahydrate are placed in a reactor, heated and heated, and methanol is distilled off to carry out a transesterification reaction, which requires 4 hours from the start of the reaction.
The temperature was raised to 230 ° C. to substantially complete the transesterification reaction. Then, after adding 0.04 part of ethyl acid phosphate (at this time, 0.7 times equivalent of phosphorus compound is added to magnesium compound), the above average particle size is obtained.
Polyethylene terephthalate polymer was prepared by adding 1.5 parts of 0.50 μm additive particle slurry (the content of the particles is 0.3% based on the obtained polyester resin), and further adding 0.04 part of antimony trioxide and carrying out polycondensation for 4 hours. Got

The specific resistance of the obtained polymer when melted was 5 × 10 ⁶ Ω · cm.

[Production of film]

The obtained polymer was dried by heating at 180 ° C. under a nitrogen atmosphere for 6 hours, melt-extruded by an extruder, and a 220 μm sheet-like material was prepared by an electrostatically applied cooling method.
After stretching 3.7 times at ℃ and 4 times at 90 ℃ in the transverse direction,
Heat treatment was performed at 20 ° C. for 5 seconds to obtain a biaxially stretched polyethylene terephthalate film having a thickness of 15 μm.

At this time, the speed at which the film can be formed without binding air bubbles by the electrostatic cooling method, that is, the maximum rotation speed of the cooling drum is 60
It was possible to achieve high speeds of m / min, and the productivity of film formation was good.

Example 2 As a surface treatment agent, the same as Example 1 except that 0.3% of a copolymer of polyacrylic acid in which a part of the carboxyl groups was neutralized with ammonia, methoxy PEG and PPG monomethacrylate was used with respect to the particles. A polyester composition was obtained in the same manner and a film was formed in the same manner as in Example 1 to obtain a film having a thickness of 15 μm.

Example 3 A polyester composition was obtained under the same conditions as in Example 2 except that the amount of the surface treatment agent was 1.0% with respect to the particles, and a film having a thickness of 15 μm was formed in the same manner as in Example 1. Obtained.

Example 4 A polyester composition was obtained in the same manner as in Example 1 except that 0.3% of a copolymer of sodium polyacrylate, polymaleic acid, methoxy PEG and PPG monomethacrylate was used as a surface treatment agent. The film was formed in the same manner as in Example 1 to obtain a film having a thickness of 15 μm.

Example 5 A polyester composition was obtained in the same manner as in Example 4 except that the amount of the surface treatment agent was 1.0% with respect to the particles. The polyester composition was formed in the same manner as in Example 1 to obtain a film having a thickness of 15 μm. .

Example 6 A polyester composition was obtained in the same manner as in Example 1 except that a copolymer of polyacrylic acid, methoxy polyethylene glycol, and polypropylene glycol monomethacrylate was used as the surface treatment agent in an amount of 1.0% based on the particles. A film having a thickness of 15 μm was obtained by forming a film in the same manner as in.

Comparative Example 1 A polyester composition was obtained in the same manner as in Example 1 except that a titanate-based coupling agent was used as the surface treatment agent in an amount of 1.0% based on the particles. I got a film.

Comparative Example 2 A polyester composition was obtained in the same manner as in Example 1 except that the surface treating agent was not used, and the film was formed in the same manner as in Example 1.
A 15 μm film was obtained.

Comparative Example 3 A polyester composition was obtained in the same manner as in Example 1 except that the amount of ethyl acid phosphate added after the completion of the transesterification reaction was 0.18 part.

The specific resistance of the obtained composition at the time of melting was as high as 1 × 10 ⁹ Ω · cm. Then, a biaxially stretched film was produced in the same manner as in Example 1, but at that time, there were no bound bubbles and the film was formed. The speed that can be achieved, that is, the maximum rotation speed of the cooling drum is as slow as 25 m / min, and the productivity of the film was poor.

The results are summarized in Table 1 above.

[Effects of the Invention] The polyester composition containing particles having calcium carbonate as a main component, which has been subjected to the special surface treatment of the present invention, has a sharp particle size distribution and good dispersibility of the particles. Further, since the affinity between the polyester and the particles is improved, the particles do not drop off very much when formed into a film, have excellent abrasion resistance, and have few coarse protrusions. Therefore, the film comprising the polyester composition of the present invention can be applied to a wide range of applications such as magnetic tapes, capacitors, packaging materials, and photolithography, and its industrial value is high.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a running system for evaluating the abrasion resistance of a film. In the figure, (I) is a 6 mmφ SUS420-J2 0.2S surface-finished fixing pin, and (II) is a tension pickup. The winding angle θ of the fixed pin film is 135 °.

Claims (2)

[Claims] 1. Particles mainly composed of calcium carbonate having an average particle diameter of 0.05 to 5 μm, wherein the alkylene has 1 to 4 carbon atoms.
0.001 of the particles obtained by surface treatment with a copolymer containing a polyalkylene glycol unit and a polyacrylic acid unit and / or an alkali metal salt of polyacrylic acid, an alkaline earth metal salt or an ammonium salt unit. ~ 1
Contains 0% by weight and has a specific resistance of 1 × 10 ⁶ to 1 × when melted.
A polyester composition characterized by being in the range of 10 ⁸ Ω · cm. 2. A film comprising the polyester composition according to claim 1.