JP3009409B2 - Polyester film - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a polyester film, and more particularly, to a polyester film having excellent adhesiveness and satisfying transparency, antistatic properties and mechanical properties.

[Prior Art] Polyester mainly composed of polyethylene terephthalate generally shows high crystallinity and a high melting point, and is known to have excellent properties in heat resistance, chemical resistance, strength, elastic modulus, etc., and is used for clothing. It has many uses, such as in the field of textiles for industrial use, etc., and in the field of films for magnetic tapes, drafting, electricity, packaging, and photography.

However, there is a problem that the polyester itself is generally inactive and thus difficult to adhere. Conventionally, corona discharge treatment, embossing treatment, and fire treatment have been performed to improve the adhesiveness of polyester films and the like.However, these methods not only complicate the process but also decrease the transparency of the film. There is.

In addition, a method of coating the surface of a polyester film with an adhesive substance is also known, but in this case, an extra step of coating is required, and an increase in cost is inevitable.

On the other hand, as a method for improving the adhesiveness from the base film itself, a method of copolymerizing a oxyalkylene glycol comonomer with a comonomer containing a metal sulfonate group (JP-A-59-11320) is also known. In addition, there was a problem that transparency was reduced.

Therefore, it has been desired to improve the adhesiveness without reducing the transparency of the base film itself without requiring an extra step.

[Problems to be Solved by the Invention] An object of the present invention is to solve the above-mentioned drawbacks of the prior art, and in particular, has excellent adhesiveness without requiring extra high-order processing, and has excellent transparency and mechanical properties. And a polyester film having excellent antistatic properties.

[Means for Solving the Problems] The object of the present invention described above is that the acid component constituting the polyester is terephthalic acid, an aromatic dicarboxylic acid having a metal sulfonate group and an aliphatic dicarboxylic acid having 4 to 20 carbon atoms. The ratio of each acid component satisfies the following formulas (I) and (II), the diol component is alkylene glycol, and the organic sulfonic acid salt is contained in an amount of 0.01 to 6 parts by weight based on 100 parts by weight of the polyester. Achieved by polyester film.

0.02 ≦ X ≦ 0.15 (I) 0.03 ≦ Y ≦ 0.25 (II) X: mole ratio of aromatic dicarboxylic acid having metal sulfonate group to terephthalic acid Y: mole of aliphatic dicarboxylic acid having 4 to 20 carbon atoms to terephthalic acid Ratio As the aromatic dicarboxylic acid containing a metal sulfonate group in the present invention, specifically, 5-sodium sulfoisophthalic acid, 2-sodium sulfoterephthalic acid, 4-sodium sulfophthalic acid, 4-sodium sulfo-2, Examples include 6-naphthalenedicarboxylic acid and compounds obtained by substituting sodium thereof with another metal (such as potassium or lithium). Particularly preferred compounds are 5-
Sodium sulfoisophthalic acid. 4-20 carbon atoms
Examples of the aliphatic dicarboxylic acid include succinic acid, adipic acid, sebacic acid, dodecane diacid, eicosane diacid (having 20 carbon atoms), among which succinic acid and adipic acid are preferable, and adipic acid is particularly preferable. .

As the glycol component in the present invention, ethylene glycol and 1,4-butanediol can be selected, but ethylene glycol is preferred.

The ratio of each acid component in the polyester satisfies the following formulas (I) and (II).

0.02 ≦ X ≦ 0.15 (I) 0.03 ≦ Y ≦ 0.25 (II) X: mole ratio of aromatic dicarboxylic acid having metal sulfonate group to terephthalic acid Y: mole of aliphatic dicarboxylic acid having 4 to 20 carbon atoms to terephthalic acid Ratio Particularly preferred ratios of the respective acid components are the following (III) and (I
V) is the range represented by the equation.

0.05 ≦ X ≦ 0.1 (III) 0.05 ≦ Y ≦ 0.2 (IV) In the polyester film of the present invention, if the proportion is small as long as the adhesiveness, transparency, mechanical properties and slipperiness are not impaired, further It is also possible to copolymerize the acid component and the glycol component.

For the production of the polyester of the present invention, a usual polyester production method can be applied as it is. For example, an acid component is directly esterified with an excess glycol component or a dialkyl ester of an acid is transesterified with an excess glycol component to obtain a low polymer, which is heated under reduced pressure to obtain excess glycol. By removing the components, a polyester can be obtained. At this time, a reaction promoting catalyst and a heat stabilizer are added as necessary.

The organic sulfonate in the present invention is a compound represented by the following general formula (I).

_{R-SO 3 M n (I} ) wherein, R is an alkyl group having 6 to 30 carbon atoms, an aryl group or an alkylaryl group, M is Li, Na, alkali metals K, Mg, Ca alkaline earth metal or phosphonium ,
n is 1 when M is an alkali metal or phosphonium, and is 1/2 when M is an alkaline earth metal.

Specifically, sodium dodecylsulfonate, sodium stearylsulfonate, sodium octylbenzenesulfonate, sodium dodecylbenzenesulfonate, sodium stearylbenzenesulfonate,
Dodecylnaphthalenesulfonic acid sodium salt and compounds obtained by substituting these sodium with other metals (Li, K, Mg, Ca) and phosphonium are mentioned. Among them, sodium dodecylbenzenesulfonate, sodium stearylsulfonate, sodium dodecylsulfonate and compounds obtained by substituting sodium with lithium are preferred.

The content of the organic sulfonate is 0.
The amount is from 01 to 6 parts by weight, preferably from 0.05 to 2 parts by weight, particularly preferably from 0.1 to 1 part by weight. When the content is less than 0.01 part by weight, the antistatic property is not improved, and when the content is more than 6 parts by weight, the antistatic property not only reaches almost saturation but also impairs transparency, which is not preferable.

The polyester film of the present invention is produced by adding an organic sulfonate at any time during the polyester production. That is, any time from before the direct esterification or transesterification to the end of the polycondensation reaction. Preferably, it is an arbitrary time from the end of the direct esterification or transesterification reaction to the start of reduced pressure.

Depending on the purpose, additives such as a lubricant, a dye, and a weathering agent can be optionally used in combination.

(Examples) Hereinafter, the present invention will be described in more detail with reference to Examples.

 In addition, the measurement of each characteristic is based on the following method.

A. Intrinsic viscosity of polymer Measured at 25 ° C using o-chlorophenol as a solvent.

B. Adhesiveness In the film state, aluminum was vapor-deposited on the surface, a cellophane tape was pressure-bonded to the vapor-deposited surface, and the state when peeled off was shown in the following four stages.

 A: No peeling was observed on the cellophane tape side.

：: The portion peeled off to the cellophane tape side is less than 30%.

Δ: A portion of 30 to 50% is peeled to the cellophane tape side.

×: The portion exceeding 50% was peeled to the cellophane tape side.

◎ and ○ indicated by the above ranks are practically preferable levels.

C. Transparency The haze of the film was measured according to the ASTM-D1003-52 method.

 2% or less is practically preferable.

D. Antistatic properties Shishido Shokai Static Honest Meter S-4104
Using a mold, the time (sec) until the potential generated in the sample was attenuated to a half value when a voltage of 5 kV was applied from 2 cm above the sample for 30 seconds was expressed. (Atmosphere is 20 ° C., 60% RH) It is preferably 10 seconds or less.

E. Breaking strength 10mm width x 50mm length
It was measured at 0 mm / min and classified into the following ranks.

○: greater than ^{15kg / mm 2 △: 10~15kg /} mm 2 ×: 10kg / mm 2 tensile at less than F. modulus 10mm width × 50 mm length of the film sample with tensile speed of 10mm / min, resulting load -Determined from the tangent at the rising part of the elongation curve. Based on the measured values, it was classified into the following ranks.

:: larger than 300 kg / mm ² △: 200 to 300 kg / mm ² ×: smaller than 200 kg / mm ² Example 1 100 parts by weight of dimethyl terephthalate, 70 parts by weight of ethylene glycol, 10 parts by weight of dimethyl 5-sodium sulfoisophthalate 0.03 parts by weight of antimony trioxide and magnesium acetate tetrahydrate were added to 10 parts by weight of dimethyl adipate and a transesterification reaction was carried out by a conventional method.
0.025 parts by weight of trimethyl phosphate was added to the obtained product, and 2 parts by weight of an ethylene glycol solution of sodium dodecylbenzenesulfonate (concentration: 30% by weight) was further added. Next, the temperature was gradually raised and the pressure was reduced, and finally polymerization was performed at 280 ° C. and 0.5 mmHg to obtain a polyester composition.

The polyester composition was melt-extruded at 280 ° C. to prepare an unstretched sheet. Next, the film is stretched 3.3 times in one direction at a temperature of 80 ° C., and then 3.3 ° in a perpendicular direction at a temperature of 80 ° C.
After stretching twice, it was heat-set at 200 ° C. to obtain a biaxially stretched film having a thickness of 30 μm. Table 1 shows the characteristic values of the film.

As is clear from Table 1, it is understood that the polyester film of the present invention has excellent adhesiveness, and satisfies transparency, antistatic properties and mechanical strength. Further, the haze of the polyester film of the present invention was not changed even after a lapse of six months, and excellent transparency was maintained.

Comparative Examples 1 to 3 As shown in Table 1, polymerization and film formation were performed in the same manner as in Example 1 except that dimethyl 5-sodium sulfoisophthalate, dimethyl adipate, and sodium dodecylbenzenesulfonate were not added. Was carried out to obtain a biaxially stretched film.

As shown in Table 1, the properties of the film were insufficient when dimethyl 5-sodium sulfoisophthalate or dimethyl adipate was not added, and the film was charged when sodium dodecylbenzenesulfonate was not added. The prevention was insufficient.

Example 2, Comparative Example 4 A biaxially stretched film was obtained by polymerization and filming in the same manner as in Example 1 except that the amount of sodium dodecylbenzenesulfonate added was changed as shown in Table 1. As is clear from Table 1, if the content of the organic sulfonate is within the range of the present invention, the transparency and the antistatic property are good as well as the adhesiveness. When it exceeds the range, it is understood that transparency, adhesiveness and mechanical properties become insufficient.

Examples 3, 45 Polymerization and film formation were carried out in the same manner as in Example 1 except that the amounts of addition of dimethyl 5-sodium sulfoisophthalate and dimethyl adipate were changed to obtain a biaxially stretched film. As shown in Table 1, the film was found to be excellent in adhesiveness, transparency, and antistatic properties.

Example 5 A biaxially stretched film was obtained by polymerization and film formation in the same manner as in Example 1 except that the organic sulfonate shown in Table 1 was used instead of sodium dodecylbenzenesulfonate. The film had good transparency and antistatic properties as well as adhesiveness.

Example 6 Polymerization and film formation were carried out in the same manner as in Example 1 except that dimethyl succinate was used instead of dimethyl adipate to obtain a biaxially stretched film. As shown in Table 1, the film was found to be excellent in adhesiveness, transparency, slipperiness and mechanical properties.

[Effects of the Invention] The polyester film of the present invention has 2
Since a specific dicarboxylic acid component is copolymerized in a specific ratio and further comprises a polyester composition containing a specific organic sulfonate, not only the adhesion is improved, but also the transparency, antistatic properties and The mechanical properties can also be satisfied.

And, since the polyester film of the present invention has adhesive properties similar to cellophane, the effect is more remarkably exhibited when used for general light packaging films such as medicine packaging and food packaging and adhesive tapes and tapes such as band-shaped strings. Is done. It can also be used effectively as a surface laminate material.

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-61-197236 (JP, A) JP-B-48-4096 (JP, B1)

Claims (1)

(57) [Claims] An acid component constituting the polyester is terephthalic acid, an aromatic dicarboxylic acid having a metal sulfonate group and an aliphatic dicarboxylic acid having 4 to 20 carbon atoms, and the ratio of each acid component is as follows: consists thereby satisfying the II) wherein with the diol component consisting of an alkylene glycol, represented by the following general formula _{(1) R-SO 3 M} n (1) ( wherein, R is an alkyl group having 6 to 30 carbon atoms, an aryl group Or an alkylaryl group, M is an alkali metal of Li, Na, K, an alkaline earth metal or phosphonium of Mg, Ca,
n is 1 when M is an alkali metal or phosphonium, and is 1/2 when M is an alkaline earth metal. A polyester film containing the organic sulfonate represented by the formula (1) in an amount of 0.01 to 6 parts by weight based on 100 parts by weight of the polyester. 0.02 ≦ X ≦ 0.15 0.03 ≦ Y ≦ 0.25 X: mole number of an aromatic dicarboxylic acid having a metal sulfonate group with respect to terephthalic acid Y: mole number of an aliphatic dicarboxylic acid having 4 to 20 carbon atoms with respect to terephthalic acid