JPH0525293A - Polyethylene 2,6-naphthalate film - Google Patents

Abstract

PURPOSE:To provide a biaxially oriented polyethylene 2,6-naphthalate film excellent in modulus of elasticity and tear strength which is useful for magnetic recording and electrical insulation. CONSTITUTION:The objective polyethylene 2,6-naphthalate film contains main recurring units of ethylene 2,6-naphthalate blended with compd. having at least 3 ester-forming functional groups per molecule.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to polyethylene-2,6-
Regarding naphthalate film. More specifically, biaxially oriented polyethylene-2,6 having excellent elastic modulus and tear strength
-Regarding naphthalate film.

[0002]

2. Description of the Related Art Polyester typified by polyethylene terephthalate is widely used today in applications such as fibers, films and molded products because of its excellent physical and chemical properties. Particularly in the magnetic recording field such as audio tapes, video tapes, computer tapes and floppy disks, which have made remarkable progress in recent years, a biaxially stretched film of polyethylene terephthalate is preferably used as the base film.

However, the characteristics required for the base film have become more and more severe with the recent progress in miniaturization, weight reduction and high performance of electric and electronic devices. For example, in the field of magnetic recording, it is necessary to reduce the thickness of the base film in order to realize long-time recording, downsizing, and weight reduction, but at the same time, it is possible to increase the elastic modulus and maintain the film stiffness. is important. For this reason, when the thickness of the base film is very thin, there are cases in which the elastic modulus of the conventional base film made of polyethylene terephthalate is insufficient.

Polyethylene-2,6-naphthalate film is a polyester film which has been attracting attention under such circumstances. It has been clarified that polyethylene-2,6-naphthalate film is superior to polyethylene terephthalate film in many points such as heat resistance, mechanical properties, and chemical properties, and its study has been actively conducted recently. Has been. For example, JP-A-62-11
3529, JP-A-2-120329, and JP-A-2-208.
323, JP-A-2-202924, JP-A-2-2029
Many proposals have been made for polyethylene-2,6-naphthalate films such as Japanese Patent No.

[0005]

As described above, the polyethylene-2,6-naphthalate film basically has many excellent properties, but the polyethylene-2,6-naphthalate film is a normal polyethylene. It has the drawback of lower tear strength than terephthalate film. In particular, when a biaxially stretched film is accompanied by a stretching treatment, the tear strength of the intermediate product or the final product in the molding process tends to be low. So for example polyethylene-2,
In the film forming process of a 6-naphthalate sequential biaxially stretched film, film tear frequently occurs and a product cannot be obtained, or even if a product is obtained, the film becomes extremely weak against tearing in a specific direction. Had a point. In addition, the demand for higher elastic modulus for biaxially stretched films tends to be more and more stringent, and depending on the application, there are some areas where the elastic modulus of conventional polyethylene-2,6-naphthalate is insufficient. ing.

The object of the present invention is to solve the above problems of the conventional polyethylene-2,6-naphthalate film, and to improve the elastic modulus and tear strength of the polyethylene-.
It is to provide a 2,6-naphthalate film.

[0007]

The above object of the present invention is to provide a compound whose main repeating unit is ethylene-2,6-naphthalate and which has three or more ester-forming functional groups in one molecule. This can be achieved by a polyethylene-2,6-naphthalate film, which is characterized by comprising a polyester copolymerized in an amount of 005% by weight or more and 10% by weight or less.

The polyester whose main repeating unit is ethylene-2,6-naphthalate in the present invention is substantially the repeating unit.

[0009]

[Chemical 1]

It is composed of ethylene-2,6-naphthalenedicarboxylate units represented by: Further, in the polyethylene-2,6-naphthalate of the present invention, a copolymer in which 10% or less, preferably 5% or less of the number of repeating units is substituted with another component, or 1% of the total weight is used.
Included are mixtures in which 0% or less, preferably 5% or less, is another polymer. Here, as the other component, a compound having a divalent ester-forming functional group, for example, 2,7, 1,4,
1,5 isomers of naphthalenedicarboxylic acid, terephthalic acid, isophthalic acid, diphenoxyethanedicarboxylic acid, dichlorophenoxyethanedicarboxylic acid, diphenyldicarboxylic acid, diphenyletherdicarboxylic acid,
Diphenyl sulfone dicarboxylic acid, diphenyl ketone dicarboxylic acid, anthracene dicarboxylic acid, or alkylene glycol such as trimethylene glycol, tetramethylene glycol, pentamethylene glycol, hexamethylene glycol, decamethylene glycol, alicyclic diol such as cyclohexanedimethanol, can give.

The ester-forming functional group in the present invention may be any functional group which forms an ester bond under the reaction conditions in the conventionally known polyester production method. Examples of such functional groups include -OH group, -COOH group,-
Examples thereof include OCOR ₁ group, —COOR ₂ group, and —COX group (wherein R represents a monovalent organic group having 1 to 6 carbon atoms and X represents a halogen group). The compound having three or more such ester-forming functional groups in one molecule may be a high molecular compound such as an aromatic compound, an aliphatic compound, an alicyclic compound or polyalkylene glycol. Examples of such a compound include hemimellitic acid, trimesic acid, trimellitic acid, prenitic acid, melophanoic acid, pyromellitic acid, biphenyl-3,3 ', 4,4'-tetracarboxylic acid, and benzophenone-3,3'. , 4, 4'-
Polyfunctional carboxylic acid such as tetracarboxylic acid, glycerin, trimethylolethane, trimethylolpropane,
Trimethylolbutane, 1,3,5-trimethylolbenzene, 1,3,5-triethylbenzene, 1,
3,5-tributyrolbenzene, 1,2,6-hexanetriol, pentaerythritol, sorbitol,
Polyhydric alcohol such as 2,2,6,6-tetramethylolcyclohexanol, or 5-hydroxyisophthalic acid, 4-hydroxyisophthalic acid, 2,5-dihydroxyterephthalic acid, 2,5-dihydroxyisophthalic acid, etc. in one molecule And a compound having a plurality of types of ester-forming functional groups. Hemi-mellitic acid, trimesic acid, trimellitic acid, prenitic acid, melophanoic acid, pyromellitic acid, biphenyl-3,3 ', 4,4'-tetracarboxylic acid, benzophenone-3,3' having a particularly rigid molecular skeleton. , 4,4'-tetracarboxylic acid and the like are preferable.

It is preferable that these compounds having three or more ester-forming functional groups in one molecule are mixed in polyethylene naphthalate in an amount of 0.005% by weight or more and 10% by weight or less, particularly preferably 0.01% by weight. 5% by weight or more
It is less than or equal to weight%. In this case, a film having a uniform thickness and surface condition can be obtained, which is preferable.

The polyethylene-2,6-naphthalate of the present invention can be produced by an esterification reaction or a transesterification reaction and a subsequent polycondensation reaction. If it is necessary to further increase the degree of polymerization, solid phase polymerization may be subsequently performed. The intrinsic viscosity of the polyester used in the present invention is 0.4 or more, preferably 0.5 or more.
The upper limit of the intrinsic viscosity is not particularly limited, but if the viscosity becomes high, uniformity of thickness cannot be obtained at the time of extrusion.

The polyethylene-2,6-naphthalate film of the present invention can be manufactured by the following method. The polyester pellets obtained by the polymerization reaction are sufficiently dried and then immediately fed to the extruder. The pellets are melted at 270 to 350 ° C., extruded in a sheet form from a die, cooled on a casting roll and solidified to obtain an unstretched film. Next, this unstretched film is biaxially stretched. As a stretching method, a sequential biaxial stretching method, a simultaneous biaxial stretching method, or a method of stretching the biaxially stretched film again in this manner may be used. Although depending on the composition of the polyester, the final stretched area ratio (longitudinal ratio × horizontal ratio) is preferably 6 times or more in order to obtain the elastic modulus targeted by the present invention. Further, in order to keep the heat shrinkage rate of the film small, it is preferable to perform heat treatment in the temperature range of 150 to 260 ° C. for about 0.1 to 60 seconds.

Various inert particles are added to the polyethylene-2,6-naphthalate film of the present invention for the purpose of improving the processability in the film forming process, the handleability of the obtained film, the workability and the commercial value. It may have been done.
Here, the inert particles are fine particles that do not cause deterioration by reacting with the polyester component during the production of the polyester, during molding, or after molding. Specifically, natural products are crushed / classified or synthesized. Manufactured by the method, silica, alumina, titania, zirconia, ceria, molybdenum oxide, tungsten oxide, calcium carbonate, calcium phosphate, barium sulfate, iron oxide, kaolin, inorganic compound particles such as carbon, silicone resin particles, silicone rubber particles, cross-linking Examples thereof include polystyrene, polyimide particles, and organic compound particles such as epoxy resin particles.

Further, the polyethylene-2,6-naphthalate film of the present invention may contain various ultraviolet absorbers, antistatic agents and the like within a range not impairing the object of the present invention.

[0017]

EXAMPLES The present invention will now be described in more detail with reference to examples. The characteristic values in the examples were measured according to the following methods.

A. Intrinsic viscosity Measured at 25 ° C using orthochlorophenol as a solvent.

B. Modulus of elasticity Biaxially stretched film longitudinal direction (MD direction) and transverse direction (TD
Direction) was measured using a Tensilon manufactured by Toyo Baldwin Co., Ltd. according to the method specified in ASTM-D-882.

B. Tear propagation resistance Longitudinal direction (MD direction) and transverse direction (TD) of biaxially stretched film
Direction) was measured by using an Elemendorf tear tester manufactured by Toyo Seiki Seisakusho according to the method specified in JIS-P-8116, and the judgment was made as follows. Both the MD and TD tear propagation resistances are 2.7 or more Class 1 The MD and TD tear propagation resistances are both 2.4 or more Class 2 MD and TD tear propagation resistances are both 2.1 or more 3 Grade Less than 2.1 in either the MD or TD direction Grade 4 Grade 3 or higher was accepted.

Example 1 In a transesterification reactor equipped with a stirrer, a rectification column and a condenser, 66.1 parts of dimethyl 2,6-naphthalene dicarboxylate, 33.6 parts of ethylene glycol and 0.3 of trimethyl trimellitate were added. And 0.06 part of manganese acetate / tetrahydrate were gradually heated to 180 ° C. to 240 ° C., and simultaneously produced methanol was subjected to transesterification while continuously distilling out of the reaction system. .. To the thus obtained reaction product, 0.025 part of trimethyl phosphate was added and reacted for 15 minutes, then 0.02 part of antimony trioxide was added, and further reacted for 5 minutes.

Subsequently, while continuously distilling ethylene glycol, the temperature was raised to 290 ° C. and, at the same time, 0.2 mmH
The polycondensation reaction is performed by reducing the pressure to g and the intrinsic viscosity is 0.6.
2 polymers were obtained. This polymer was a copolymer containing 0.5% by weight of trimethyl trimellitate units.

Then, the pellets of the copolymerized polymer were dried, melted at 300 ° C. in an extruder and extruded into a sheet to obtain an unstretched sheet. Then 3.5 times in the vertical direction and 3. in the horizontal direction.
It was stretched 0 times. The film did not break during film formation and showed good stretchability. Then, heat treatment was performed at 230 ° C. for 5 seconds to obtain a biaxially stretched film having a thickness of 10 μm.

The elastic modulus of this film is 760 k in the MD direction.
It was g / mm ² and 740 kg / mm ² in the TD direction. Tear propagation resistance is 2.5g in MD direction and 2.7g in TD direction.
And showed a good value.

Example 2 In the same manner as in Example 1, 0.05% by weight of trimethyl trimellitate unit having an intrinsic viscosity of 0.62 was contained from dimethyl 2,6-naphthalenedicarboxylate, ethylene glycol and trimethyl trimellitate. A copolymerized polymer was obtained. Using this copolymer, a biaxially stretched film having a thickness of 10 μm was obtained in the same manner as in Example 1. The film did not break during film formation and showed good stretchability.

The elastic modulus of this film is 740 k in the MD direction.
g / mm ^2, was a TD direction 720kg / mm ^2. The tear propagation resistance is 2.2g in MD and 2.4g in TD.
And showed a good value.

Example 3 In the same manner as in Example 1, dimethyl 2,6-naphthalenedicarboxylate, ethylene glycol and 1,3,5-trimethylolbenzene were used to give 1,3 having an intrinsic viscosity of 0.66.
A copolymerized polymer containing 4.5% by weight of 5-trimethylolbenzene unit was obtained. Using this copolymer, a biaxially stretched film having a thickness of 10 μm was obtained in the same manner as in Example 1. The film did not break during film formation and showed good stretchability.

The elastic modulus of this film is 780 k in the MD direction.
It was g / mm ² and 760 kg / mm ² in the TD direction. The tear propagation resistance is 2.7g in MD and 3.0g in TD.
And showed a good value.

Comparative Example 1 In the same manner as in Example 1, 0.003% by weight of tetramethyl pyromellitic acid unit having an intrinsic viscosity of 0.62 from dimethyl 2,6-naphthalenedicarboxylate, ethylene glycol and tetramethyl pyromellitic acid. The contained copolymer polymer was obtained. Using this copolymer, a biaxially stretched film having a thickness of 10 μm was obtained in the same manner as in Example 1. This copolymer polymer frequently suffered film breakage during film formation.

The elastic modulus of this film is 660 k in the MD direction.
It was g / mm ² and 650 kg / mm ² in the TD direction. The tear propagation resistance is 1.5g in the MD direction and 1.7g in the TD direction.
And showed a very low value.

Comparative Example 2 In the same manner as in Example 1, a copolymerized polymer containing dimethyl 2,6-naphthalenedicarboxylate, ethylene glycol, and pentaerythritol in an amount of 12.0% by weight of a pentaerythritol unit having an intrinsic viscosity of 0.69. Obtained. Using this copolymer, a biaxially stretched film was formed in the same manner as in Example 1, but many breakages occurred, and uniform stretching could not be performed to obtain a satisfactory film.

Comparative Example 3 In the same manner as in Example 1, dimethyl 2,6-naphthalenedicarboxylate and ethylene glycol were used to obtain an intrinsic viscosity of 0.
62 polyethylene-2,6-naphthalate homopolymer was polymerized. Using this polymer, a biaxially stretched film was formed into a film in the same manner as in Example 1, but the film was frequently torn. The elastic modulus of this film is 650 kg / MD direction
mm ² and 630 kg / mm ² in the TD direction. The tear propagation resistance was 1.5 g in the MD direction and 1.7 g in the TD direction, which were very low values.

[0033]

The polyethylene-2,6-naphthalate film of the present invention exhibits excellent elastic modulus and tear strength.
The present invention can provide a biaxially stretched polyethylene-2,6-naphthalate film having excellent properties for magnetic recording and electrical insulation.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location B29L 7:00 4F C08L 67:02

Claims (1)

Claims: 1. The main repeating unit is ethylene-2,6-naphthalate, and 0.005% by weight or more and 10% by weight of a compound having 3 or more ester-forming functional groups in one molecule. %, A polyethylene-2,6-naphthalate film comprising a polyester copolymerized in an amount of not more than%.