JP2681683B2 - Polyester film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention has particularly improved antistatic effect and adhesiveness, and has mechanical properties, heat resistance, slipperiness, transparency and surface gloss. , A polyester film having excellent chemical resistance and gas barrier properties.

[Problems to be solved by conventional technology and invention]

Biaxially oriented polyester film containing polyethylene terephthalate as the main component has excellent properties such as mechanical properties, chemical resistance, gas barrier properties, transparency and safety, so it is used for magnetic recording media, plate making and photo-etching. It is used in many applications such as electrical, packaging and packaging.

Recently, with the diversification of food culture, variously processed polyester films have been used for food packaging. Such processing is often performed not only for the purpose of increasing the consumer's willingness to purchase, but also for imparting functionality. For example, vacuum deposition of aluminum on a polyester film to improve gas barrier properties, lamination of an olefin resin or the like to impart heat sealing properties, and the like can be mentioned.

Further, recently, in printing, which is indispensable for packaging materials, in addition to high speed and multicolor printing, high precision printing such as bar code printing is required.

However, since polyethylene terephthalate has high crystallinity and is poor in reactivity with other substances because it does not have a functional group, the polyester film obtained from polyethylene terephthalate has adhesiveness with printing ink or laminating adhesive. If it is inferior to
Further, since the polyester film has a high friction coefficient and a high specific electric resistance, it is easily charged by static electricity. The electrostatic charge of the polyester film causes inconveniences such as film wrapping and winding around the rolls in the film forming process and fritting process, and this charging also causes a discharge sparse to the device and the worker for safety. Not preferred. Further, since the charged polyester imparts dust, the dust adheres to the film surface during the printing process, and the adhesion causes a beard, which makes it difficult to form a film having excellent printing accuracy.

As an attempt to improve the adhesiveness of the polyester film, many techniques have been developed, such as a method of applying a component having some good adhesiveness to the film surface and a method of simultaneously extruding a resin with good adhesiveness and a polyester resin, By these methods, it is possible to obtain a polyester film having a somewhat satisfactory adhesive performance. However, these methods have low film production efficiency, cannot avoid an increase in cost, and cannot be said to be industrially and economically effective methods. On the other hand, a method of modifying the polyester resin itself to improve the adhesiveness has been proposed. This method is a method of copolymerizing a straight-chain aliphatic diol or a straight-chain aliphatic dicarboxylic acid with a raw material for polyester production or a polyester. A method of adding polyalkylene glycol or the like has been proposed. However, the polyester film obtained by the former method has insufficient adhesive performance, and the polyester film obtained by the latter method has a certain degree of adhesive performance, but the polyester film obtained by the oxidative decomposition or thermal decomposition of the polyalkylene glycol It is not preferable because mechanical strength is lowered and coloring occurs.

As for antistatic, many techniques have been developed such as a method of applying a material having an antistatic effect or a method of simultaneously extruding a resin having an antistatic effect and a polyester resin, and these methods are satisfactory to some extent. A polyester film having an antistatic effect can be obtained. However, in this case as well, the same problem as in the case of attempting to improve the adhesiveness occurs, and therefore there is a demand for a method of obtaining a film having an antistatic effect by modifying the polyester resin itself. As this method, there is known a method in which a metal sulfonate or a mixture of the metal salt and polyalkylene glycol is added to polyester to form a film from the polyester composition. However, the polyester film obtained from the composition obtained by adding the sulfonic acid metal salt alone to the polyester is insufficient in terms of the antistatic effect, and the polyester obtained from the composition obtained by adding the sulfonic acid metal salt and the polyalkylene glycol to the polyester. Although the film has an antistatic ability, the mechanical strength may be reduced and the coloring may be caused by the oxidative decomposition or thermal decomposition of the polyalkylene glycol as in the case of attempting to improve the adhesiveness.

[Means for solving the problem]

The present inventors have conducted intensive studies in view of the present situation, and as a result, have made a polyester consisting of polyester, a specific polyethylene glycol and a specific antistatic agent, and obtained by adding the polyethylene glycol at a specific time. We have found that the polyester film produced using the composition has excellent adhesion and antistatic properties, and completed the present invention.

That is, the present invention relates to 100 parts by weight of polyester (A) containing ethylene terephthalate as a main repeating unit and polyethylene glycol (B) having a weight average molecular weight of 10,000 to 30,000.
0.1-2.0 parts by weight and alkyl sulfonic acid metal salt and / or alkylbenzene sulfonic acid metal salt (C) 0.1-1.0
A polyester resin composition obtained by adding polyethylene glycol (B) at a stage where the intrinsic viscosity of the polyester exceeds 0.3 in the polymerization process of the polyester (A) and the polymerization is completed. It is a polyester film with excellent antistatic effect and adhesiveness.

The polyester (A) having ethylene terephthalate as a main repeating unit used in the present invention is obtained by subjecting terephthalic acid or a derivative thereof and ethylene glycol to an esterification reaction or a transesterification reaction, and further subjecting an intermediate product thereof to a polycondensation reaction. Although it is a polymer obtained by the above, a conventionally known carboxylic acid component and a glycol component can be copolymerized within a range that does not impair the effects of the present invention. Specifically, for example, phthalic acid, isophthalic acid, adipic acid, Sebacic acid, naphthalene-1,4- or -2,6-dicarboxylic acid, carboxylic acid components such as diphenyl ether-4,4'-dicarboxylic acid; propylene glycol, butylene glycol, neopentyl glycol, cyclohexanedimethanol, Glycol component such as 2,2-bis (4-hydroxyphenyl) propane; p- Carboxymethyl benzoic acid, p- methoxybenzoic acid, oxyacids of p- hydroxyethoxy benzoic acid.

As a catalyst for the esterification reaction or transesterification reaction, conventionally known catalysts such as alkali and alkaline earth metals,
Acetates such as zinc, titanium and tin, alcoholates and the like are used.

The intrinsic viscosity [η] of polyester is 0.5
The range of -0.9 is preferable, and the range of 0.6-0.7 is more preferable. The intrinsic viscosity [η] referred to in the present invention
Is a value measured at 25 ° C. using an equivalent weight mixture of phenol and tetrachloroethane as a solvent.

The polyethylene glycol (B) used in the present invention must be added during the above-mentioned polyester polymerization process, when the intrinsic viscosity [η] of the polyester exceeds 0.3. If added before the intrinsic viscosity of the polyester exceeds 0.3, thermal decomposition of polyethylene glycol, inhibition of the polycondensation reaction of the polyester, etc. occur, and the resulting polyester film tends to be colored, odor is generated, and mechanical strength is lowered. In addition, the method of producing polyester, pelletizing it and then melt-mixing polyethylene glycol with an extruder is a method in which polyester easily hydrolyzes, while polyethylene glycol has high hygroscopicity, but its melting point and glass transition temperature are low. In order to eliminate the water content of polyethylene glycol, it is necessary to dry for a long time, which is not preferable industrially and economically.

The weight average molecular weight of polyethylene glycol is 10
The range of 000 to 30,000 is preferred. Weight average molecular weight is 10
From the polyester composition containing less than 000, a polyester film having reduced mechanical strength can be obtained. Further, from a polyester composition obtained from one having a weight average molecular weight of more than 30,000, a polyester film having poor adhesiveness and bad haze can be obtained.

The content of polyethylene glycol is preferably in the range of 0.1 to 2 parts by weight with respect to 100 parts by weight of polyester (A). From the polyester composition containing less than 0.1 part by weight of polyethylene glycol, a film exhibiting sufficient antistatic property and adhesiveness cannot be obtained, and a polyester film prepared from the polyester composition exceeding 2 parts by weight. Causes deterioration of haze and deterioration of mechanical properties, and also becomes colored and odorous, and film breakage frequently occurs in the film forming process.

The alkali metal salt of alkylsulfonic acid and the alkali metal salt of alkylbenzenesulfonic acid (C) used in the present invention are respectively alkali metal salt of alkylsulfonic acid: R—SO ₃ M (I) Alkali metal salt of alkylbenzenesulfonic acid: (R and R 'are alkyl groups having 10 to 16 carbon atoms, M
And M ′ are represented by Li, Na, K).

These metal salts have an excellent antistatic effect due to a synergistic effect with polyethylene glycol.

The amount of the alkali metal salt of alkyl sulfonic acid and the alkali metal salt of alkylbenzene sulfonic acid blended is preferably 0.1 to 1 part by weight with respect to 100 parts by weight of the polyester (A). A film made from a polyester composition having a blending amount of less than 0.1 does not have sufficient antistatic effect, and a film made from a polyester composition having a blending amount of the metal salt of more than 1 part by weight has a metal salt of the metal salt. Bleeds out, the adhesiveness is deteriorated, and it is not preferable in terms of hygiene.

The addition timing of the alkali metal salt of alkyl sulfonic acid and the alkali metal salt of alkylbenzene sulfonic acid is different from the addition timing of polyethylene glycol and is not particularly limited. Therefore, it may be added during the polymerization reaction of polyester, or may be added in the polyester pellet and the extruder. In terms of handling, it is preferable to add it by mixing with polyethylene glycol.

Further, it is acceptable to add a conventionally known additive to the polyester composition to the extent that the characteristics of the present invention are not impaired.
Examples of additives include polyamide, resins such as polyolefin, silica, talc, kaolin, inorganic particles such as calcium carbonate, titanium oxide, pigments such as carbon black,
Examples thereof include ultraviolet absorbers, release agents, flame retardants, antioxidants, and the like.

The polyester film of the present invention can be easily produced by a conventionally known method.

As a film forming method, any conventionally known method can be selected. That is, a method in which a polyester resin is melted by an extruder and extruded from a die having an appropriate slit, immediately after that, uniaxially or biaxially stretched, heat-fixed, and wound to obtain a film product, etc. To be

For the stretching method, uniaxial and biaxial directions can be arbitrarily selected, and in the case of biaxial stretching, the order of stretching can be arbitrarily set. The stretching ratio and the stretching speed can be appropriately selected depending on the amount of the additive, or may be in conformity with a normal polyester film.

In the present invention, it is preferable that after the film is formed on the film, the surface of the film is subjected to discharge corona treatment. Since the ether bond of polyethylene glycol is particularly susceptible to oxidation, it is easily converted into a carboxy group or a carbonyl group by the corona discharge treatment, and these functional groups develop remarkable film adhesiveness. Furthermore, since the corona discharge treatment activates the alkali metal salt of the sulfonic acid derivative, promotes the interaction with polyethylene glycol, and promotes the migration to the vicinity of the film surface, the antistatic effect of the polyester film is also improved.

The polyester film of the present invention has excellent mechanical properties of a conventional polyethylene terephthalate film,
Although it exhibits excellent adhesiveness and antistatic properties comparable to those of the coating type without impairing transparency, heat resistance, etc., it can be processed by a conventionally known process in order to impart more specific performance. Examples of processing include irradiation with ultraviolet rays, α-rays, γ-rays, electron rays, etc., application of resins such as vinylidene chloride, polyvinyl alcohol, polyamide, and polyolefin, lamination, and vapor deposition of metals.

Since the polyester film of the present invention suppresses the decomposition of polyethylene glycol to a minimum, the generation of odor and the transfer of the decomposed product to food are extremely small, and it is most suitable as a film for food packaging. The polyester film of the present invention is not limited to this application, but can be widely used for magnetic recording medium application, photographic application, general industrial application, and the like.

〔Example〕

Hereinafter, the present invention will be specifically described with reference to examples. In addition,
Each physical property value in the examples is measured by the following method.

(1) Haze Measured according to JIS K6714.

[Judgment]

○: Almost no haze increase compared to polyethylene terephthalate film △: Less than 50% increase ×: More than 50% increase (2) Mechanical strength In accordance with JIB C-2318, Orientetech A tensile test was conducted on a film having a width of 1 cm and a length of 10 cm (the machine axis direction was the longitudinal direction) using a Tensilon manufactured by the company. At this time, the mechanical strength was measured based on the breaking strength and elongation and Young's modulus.

[Judgment]

◯: Neither the breaking strength / elongation nor the Young's modulus is much lower than that of the polyethylene terephthalate film.

(Triangle | delta): A big fall is recognized in either breaking strength elongation or Young's modulus.

X: A significant decrease is observed in both the breaking elongation at break and the Young's modulus.

(3) Adhesion Toyo Ink Mfg. Co., Ltd.'s CCST 62 (white) is diluted 50% with a special solvent (NC102), applied to the film with a bar coater (# 0), and dried at 80 ° C for 30 seconds. Then, the following test was conducted. The coating film thickness at this time was about 1 μm. Nichiban Co., Ltd. cellophane tape (15 mm width) was attached to this ink-coated surface, and after pressure bonding with a rubber roller, T-type peeling was performed at a speed of 100 mm / sec, and the peeled surface was visually evaluated.

(4) Antistatic property Surface resistance value Measured with Toa Denpa Kogyo's SM-10E Insulator.

Charge voltage half-life Measured using a static Honest meter S-5109 type manufactured by Shishido Shokai. The voltage application was 12 KV from the position 2 mm above the sample. All of these measurements are at 25 ℃, 65% R
I went in the atmosphere of H.

(5) The sample was weighed and put into an equal weight mixed solution of phenol and tetrachloroethane heated to an intrinsic viscosity of 140 ° C, and dissolved by stirring for 15 minutes. After cooling this solution, the solution viscosity was measured by an Ostwald-type capillary viscometer installed in a constant temperature bath at 25 ° C. In this way, the viscosity of the solution having several concentrations was measured, and the concentration was extrapolated to 0 to obtain the intrinsic viscosity [η].

Examples 1 to 5 Using terephthalic acid as the dicarboxylic acid component and ethylene glycol as the diol component, these were charged in a reaction vessel, and the esterification reaction was allowed to proceed at 240 ° C. under pressure.
The point at which almost no water distilling was observed was regarded as the substantial end point of the esterification reaction.

Then, 500 ppm of antimony trioxide (II) was added to terephthalic acid as a polycondensation catalyst, and the particle size was further reduced to 1.5 μm.
Was added as a lubricant to 500 ppm of terephthalic acid. Thereafter, the pressure in the kettle was reduced, and the polycondensation reaction was allowed to proceed under a vacuum of 0.5 torr.

The reaction product in the kettle was sampled over time, and when the intrinsic viscosity [η] reached 0.5, 100 parts by weight of polyethylene terephthalate in the kettle were added to polyethylene glycol and sodium alkyl sulfonate (average carbon number of alkyl: 13). Was added at the ratio shown in Table 1. After the addition is complete
The polycondensation reaction was allowed to proceed again, and when the intrinsic viscosity reached 0.80, it was taken out of the kettle.

Using the polyester resin composition produced by the above method as a raw material, a biaxially stretched film was produced and evaluated. The biaxially stretched film was manufactured by the sequential biaxial stretching method shown below. That is, the polyester resin composition is
After melt-extruding at a die temperature of 282 ℃ to make an unstretched film with a thickness of about 130μ at a casting roller temperature of 40 ℃, a longitudinal stretching temperature of 80 in a longitudinal stretching section composed of a low drive roll and a high drive roll. Longitudinal stretching was performed in the range of up to 90 ° C so that the longitudinal stretching ratio was 2.8, and then transverse stretching was performed using a tenter so that the lateral stretching temperature (tenter open temperature) was 95 ° C and the lateral stretching ratio was 3.8. After that, heat-set at 210 ℃, corona discharge treatment of the film surface (3m on the film surface
A high frequency wave of 500 kHz and 9 KV was applied to the blade electrode placed at m, and the electrode was moved in air. ) Was applied to obtain a biaxially stretched film having a thickness of 12 μm. The results of evaluation of this film by the above method are shown in Table 1.

Comparative Examples 1 to 7 Films were produced in exactly the same manner as in Examples 1 to 5 except that the composition of the polyester resin was outside the scope of the present invention shown in Table 1, and the results of evaluation of the obtained films were The results are shown in Table 1.

In Examples 1 to 5 of the present invention, it can be seen that all films exhibit excellent adhesiveness and antistatic effect without impairing the excellent properties (Comparative Example 1) originally possessed by the polyethylene terephthalate film. .

On the other hand, in Comparative Example 2 in which sodium alkylsulfonate was not added, the adhesiveness and antistatic property were insufficient, and in Comparative Example 3 in which polyethylene glycol was not added, no improvement in adhesiveness was observed. The antistatic property is also insufficient.

On the other hand, in Comparative Examples 4 and 5 in which the weight average molecular weight of polyethylene glycol is outside the range of the present invention, the adhesiveness and antistatic property are inferior to those of Example 2 in which the addition amount is equal, and the mechanical properties Decrease and increase in haze are remarkable. Furthermore,
In Comparative Example 6 in which the amount of polyethylene glycol added exceeds the range of the present invention, the adhesiveness and antistatic property are good, but the haze increases and the mechanical properties decrease remarkably. Further, in Comparative Example 7 in which the added amount of sodium alkylsulfonate exceeds the range of the present invention, the antistatic property is sufficient, but the adhesive property is insufficient. In Comparative Example 7, oozing of sodium alkylsulfonate occurred on the surface of the film, which was a sanitary problem.

Comparative Examples 8 and 9 A film was produced in exactly the same manner as in Example 2 except that the polyethylene glycol and sodium alkylsulfonate were added immediately before the start of polycondensation or when the film was formed into an extruder. The results of evaluating the film performance at this time are shown in Table 2. It can be understood that even if the composition is the same, if the addition timing is out of the range of the present invention, mechanical properties are deteriorated, haze is deteriorated, and antistatic property is not sufficiently exhibited.

Example 10 Example 2 is repeated except that sodium dodecylbenzenesulfonate is used in place of sodium alkylsulfonate.
The film was manufactured and evaluated in exactly the same manner as in. as a result,
The film was excellent in haze, mechanical strength, adhesiveness and antistatic property.

Comparative Examples 10 to 12 Polyester resin compositions (master polymers) were produced in the same manner as in Example 1 in the proportions of polyester resin shown in Table 2. Intrinsic viscosity [η] = 0.7
Diluted with the polyester resin of No. 2 to have the content of polyethylene glycol and sodium alkylsulfonate shown in Table 2, and in the same manner as in Example 1, a polyester film was obtained and evaluated. The results are shown in Table 2.
The haze is shown numerically. In addition, Example 1,
The haze value of Example 2 and Example 5 was about 2.8.

[Effects of the Invention] The polyester film obtained according to the present invention has excellent antistatic properties without impairing its original excellent properties, namely mechanical properties, heat resistance, gas barrier properties, chemical resistance, transparency and the like. , Which expresses adhesiveness. Therefore, even though it has the same performance as the conventional coated product, it can be used in fields where it has not been applicable up to now because of its price advantage, so it has a high industrial contribution.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location C08L 71:02)

Claims (1)

(57) [Claims] 1. A polyester (A) containing 100 parts by weight of ethylene terephthalate as a main repeating unit, and a polyethylene glycol (B) of 0.1 to 3 having a weight average molecular weight of 10,000 to 30,000.
2.0 parts by weight and 0.1 to 1.0 parts by weight of an alkyl sulfonic acid metal salt and / or an alkylbenzene sulfonic acid metal salt (C), and at the stage where the intrinsic viscosity of the polyester exceeds 0.3 in the polymerization process of the polyester (A). A polyester film having excellent antistatic effect and adhesiveness, obtained by forming a polyester resin composition obtained by adding polyethylene glycol (B) and completing polymerization.