JP2576210B2 - Copolyester - Google Patents

Description

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

[Prior Art] Polyesters typified by polyethylene terephthalate are widely used as fibers, films, and other molded products because of their excellent mechanical performance, light resistance, heat resistance, chemical resistance, and the like. Particularly in the film field, it is used for magnetic tapes, drafting, discharging, condensers, packaging, photography, and the like, and its use is expanding. However, in expanding the uses of polyester, 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 the polyester film. However, these methods not only complicate the process but also have the disadvantage of lowering the transparency and the like.

A method of coating an adhesive substance on the surface of polyester is also known (Japanese Patent Application Laid-Open No. 58-141208). However, in this case, an extra step of coating is required, and an increase in cost is inevitable. Therefore, it has been desired to improve the adhesiveness from the base film itself without requiring these steps.

[Problems to be Solved by the Invention] An object of the present invention is to eliminate the above-mentioned disadvantages of the prior art, and does not require special high-order processing, has excellent adhesiveness, transparency, and mechanical properties. An object of the present invention is to provide a copolymerized polyester having satisfactory characteristics.

[Means for Solving the Problems] An object of the present invention is to provide an aromatic dicarboxylic acid component having 70% by mole or more of a terephthalic acid component and 2 to 10% by mole of a metal sulfonate group in a dicarboxylic acid component,
80% by mole or more of the glycol component is composed of the ethylene glycol component, and is 1 to the total copolymerized polyester.
-20% by weight is achieved by a copolymerized polyester characterized by being a glycol component represented by the following general formula [I].

(However, l and n are an integer of 3 to 50 and m is an integer of 2 to 20 and may be the same or different.) The aromatic dicarboxylic acid having a metal sulfonate group of the present invention is specifically, , 5-sodium sulfoisophthalic acid, 2-sodium sulfoterephthalic acid, 4-sodium sulfophthalic acid, 4-sodium sulfo-2,6-naphthalenedicarboxylic acid and their sodium substituted with other metals (potassium, lithium, etc.) The following compounds can be mentioned.

In the present invention, 70 mol% or more of the dicarboxylic acid component is a terephthalic acid component. If it is less than 70 mol%, it is not preferable because film formation is difficult. Further, the content of the aromatic dicarboxylic acid component having a metal sulfonate group is 2 to 10 mol%, preferably 3 to 7 mol%, based on all dicarboxylic acid components. When the amount is less than 2 mol%, a film having a sufficient adhesive property cannot be obtained. On the other hand, when the amount exceeds 10 mol%, the adhesiveness reaches saturation, and conversely, the mechanical strength decreases and the pressure during film formation decreases. There is a problem that the yield decreases due to an increase or the like.

The glycol component present together with the ethylene glycol component in the present invention has a general formula (However, l and n are integers of 3 to 50 and m is an integer of 2 to 20 and may be the same or different.)

If any one of l, m, and n in the above formula [I] is not satisfied, the object of the present invention cannot be achieved. That is, when l and n are less than 3, sufficient adhesiveness cannot be obtained, and when it is more than 50, the compatibility with the copolymerized polyester is deteriorated and the transparency is lowered, which is not preferable. On the other hand, when m is less than 2, the surface of the polymer or molded product becomes white with the passage of time and the transparency is lowered, and when it is larger than 20, the compatibility with the copolymerized polyester is deteriorated.

The amount of the glycol represented by the formula [I] is 1 to 20% by weight, preferably 2 to 15% by weight based on the weight of the copolymerized polyester.
It is. If this is less than 1% by weight, a film having a sufficient adhesive property cannot be obtained when the film is formed,
Conversely, if it exceeds 20% by weight, not only the adhesiveness is saturated, but also the mechanical strength is lowered and the yield is lowered due to an increase in pressure during film formation.

In the copolymerized polyester of the present invention, as long as the adhesiveness, transparency and mechanical properties are not impaired, other acid components, for example, isophthalic acid, aromatic dicarboxylic acid components such as naphthalenedicarboxylic acid, Aliphatic dicarboxylic acid components such as glutaric acid, adipic acid, azelaic acid and sebacic acid, and other glycol components such as tetramethylene glycol, 1,4-cyclohexanedimethanol and bisphenol A are copolymerized. You may.

The copolymerized polyester of the present invention is a normal polyester production method such as a polycondensation reaction after transesterification of a lower alkyl ester of dicarboxylic acid and glycol and a polycondensation reaction after esterification of dicarboxylic acid and glycol. It can be manufactured according to Here, the aromatic dicarboxylic acid component having a metal sulfonate group may be reacted in the same manner as other dicarboxylic acid components.

The glycol component represented by the formula [I] has the general formula (However, l and n are integers of 3 to 50 and m is an integer of 2 to 20 and may be the same or different.) As a glycol represented by Alternatively, it is particularly preferable to add during the start of the polycondensation reaction after the completion of the esterification reaction from the viewpoint of suppressing the decomposition of the ether bond.

Furthermore, depending on the purpose, silica, kaolin, talc, Ti
A small amount of a lubricant such as O ₂ or BaSO ₄ or a small amount of an additive such as a pigment, a dye or a weathering agent can be optionally used.

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples. In addition, the measured value of each characteristic is based on the following method.

(Intrinsic viscosity of polymer) It measured at 25 degreeC using o-chlorophenol as a solvent.

(Adhesiveness of film) Aluminum was vapor-deposited on the surface of the film, a cellophane tape was pressure-bonded to the vapor-deposited surface, and the state when peeled off was shown in the next stage.

Grade 1: No peeling on the cellophane tape side.

Second grade: 10% or less of the portion peeled off to the cellophane tape side.

Grade 3: A portion of 10 to 50% is peeled to the cellophane tape side.

Grade 4: 50% or more of the part is peeled to the cellophane tape side.

Grade 5: The Al film is completely peeled to the cellophane tape side without resistance.

 Class 3 or higher is a practically preferable level.

(Transparency) The haze of the film was measured according to ASTM-D1003-52. 2% or less is practically preferable.

(Rupture strength) Tensile speed 30 per film sample of 10mm width x 50mm length
It was measured at 0 mm / min and classified into the following ranks.

:: Exceeds 15 kg / mm ² .

△: 10 to 15 kg / mm ² ×: less than 10 kg / mm ² (elastic modulus) A 10 mm wide x 50 mm long film sample was pulled at a tensile speed of 10 mm /
Per minute and determined from the tangent to the rising portion of the obtained load-elongation curve. From the measured values, it was classified into the following ranks.

○: exceeding ^{300kg / mm 2 △: 200~300kg /} mm 2 ×: 200kg / mm 2 than Examples 1 to 6 and Comparative Examples 1 to 4 100 parts by weight of dimethyl terephthalate, ethylene glycol 70 parts by weight Table 1 0.1 part by weight of calcium acetate and 0.03 part by weight of antimony trioxide were added to the amount of dimethyl 5-sodium sulfoisophthalate shown in (1), and a transesterification reaction was carried out by a conventional method. After the transesterification, the following general formula [II] In Example 1, l, m, n and the copolymerized amount of glycol shown in Table 1 were added. To the obtained product, 0.05 parts by weight of trimethyl phosphate was added, and the temperature was gradually increased and the pressure was reduced. Finally, polymerization was performed at 280 ° C. and 1 mmHg or less to obtain a copolymerized polyester.

After drying these copolymerized polyesters, they were melt-extruded at 280 ° C. to prepare unstretched sheets. The film is then stretched 3.3 times in one direction at a temperature of 80 ° C, and further perpendicularly at a temperature of 90 ° C.
After stretching 3.3 times, heat set at 200 ° C for 5 seconds and thickness 30μm
Was obtained. Table 1 also shows the characteristic values of the film.

As is clear from Table 1, it is understood that the copolyester within the range specified in the present invention has excellent adhesiveness, good transparency and good mechanical strength.

On the other hand, if it is out of the range of the present invention, the adhesiveness and the mechanical strength are inferior, and when a large amount of dimethyl 5-sodium sulfoisophthalate is copolymerized as in Comparative Example 4, the viscosity of the raw material is remarkably thickened. It was impossible.

Example 7 A biaxially stretched film was obtained by polymerization and film formation in the same manner as in Example 1 except that dimethyl 2-sodium sulfoterephthalate was used instead of dimethyl 5-sodium sulfoisophthalate. As shown in Table 1, the film was found to be excellent in adhesiveness, transparency, and mechanical properties.

Comparative Examples 5 to 8 Polymerization and film formation were carried out in the same manner as in Example 1 except that l, m and n in the general formula [II] were changed to obtain a biaxially stretched film.
As shown in Table 1 as being outside the scope of the present invention,
It turns out that transparency or mechanical properties are inferior.

[Effect of the Invention] The copolymerized polyester of the present invention not only has good adhesiveness, but also has excellent transparency and mechanical properties.

Therefore, the copolymerized polyester of the present invention is effectively used for all applications of a film in which adhesiveness, transparency and mechanical properties are required, and has adhesiveness similar to cellophane, so that it can be used for medicine packaging, food packaging, etc. When used for general light packaging films, tapes such as pressure-sensitive adhesive tapes and belt-like cords, the effects are more remarkably exhibited.

Claims (1)

(57) [Claims] (1) At least 70 mol% of a dicarboxylic acid component is a terephthalic acid component and 2 to 10 mol% is an aromatic dicarboxylic acid having a metal sulfonate group, and at least 80 mol% of a glycol component is composed of an ethylene glycol component. 1 to 20% by weight based on the total copolymerized polyester
Is a glycol component represented by the following general formula [I]. (However, l and n are integers of 3 to 50 and m is an integer of 2 to 20 and may be the same or different.)