JP4590925B2 - Copolyester and method for producing the same, polyester resin composition and polyester film - Google Patents

Description

  The present invention relates to a copolyester or a polyester resin composition capable of forming a flexible molded product, and a flexible polyester film, and more specifically, an industrial material that requires transparency, easy moldability, and heat resistance. The present invention relates to a polyester film suitable for use as a packaging material and a copolymer polyester (resin composition) as a raw material thereof.

A typical flexible film is a polyvinyl chloride film. This polyvinyl chloride film has been preferably used in that it has excellent weather resistance and is suitable not only for various processes such as embossing but also at low cost.
However, polyvinyl chloride film has problems such as the generation of toxic gas when the film burns due to a fire or the like, and the problem of bleeding out of plasticizers. Therefore, a new flexible film is required due to recent environmental needs. It has been.

  In order to obtain a resin for a film with the above drawbacks improved, a method of copolymerizing a soft segment with polyester has been considered. For example, a resin obtained by copolymerizing polybutylene terephthalate with a long-chain polyether such as polytetramethylene glycol (for example, see Patent Document 1), and polyethylene terephthalate with a long-chain aliphatic dicarboxylic acid that is a dimer of unsaturated fatty acids. Polymerized resin (for example, see Patent Document 2), resin obtained by copolymerizing polybutylene terephthalate with a long-chain aliphatic dicarboxylic acid that is a dimer of unsaturated fatty acid (for example, see Patent Document 3), and further polybutylene terephthalate In addition, a resin obtained by copolymerizing polyethylene terephthalate with a long-chain aliphatic dicarboxylic acid that is a dimer of unsaturated fatty acids (see, for example, Patent Documents 4 to 5) has been proposed.

  Moreover, as a method for obtaining a polyester (resin composition) containing a long chain aliphatic dicarboxylic acid as a copolymerization component in a predetermined ratio, in addition to a method of directly copolymerizing a long chain aliphatic dicarboxylic acid in a predetermined ratio, a long chain A method is known in which an aliphatic dicarboxylic acid copolymerized polyester and an aromatic polyester are mixed at a certain ratio (see, for example, Patent Documents 6 to 7).

  However, a resin obtained by copolymerizing polybutylene terephthalate with a long-chain polyether is inferior in weather resistance, heat resistance and transparency, and a resin obtained by copolymerizing polyethylene terephthalate with a long-chain aliphatic dicarboxylic acid has a crystallization rate. However, it is difficult to form fibers, films, sheets, and other molded products. A resin obtained by copolymerizing polybutylene terephthalate with a long-chain aliphatic dicarboxylic acid is easy to form into a fiber, film, sheet or other molded product due to its high crystallinity. Or high-purity (purity of 95% by weight or more) long-chain aliphatic dicarboxylic acid (see Patent Document 4) obtained through multiple distillations / purifications, etc. Could not find a suitable use. Further, when a film is obtained by mixing a long-chain aliphatic dicarboxylic acid copolymer polyester and an aromatic polyester at a certain ratio, a high-purity long-chain aliphatic dicarboxylic acid having a purity of 99% by weight or more is preferably used. (See Patent Document 6), and a cost problem is inevitable.

  In order to overcome the cost problem, it is conceivable to use a long-chain fatty acid dicarboxylic acid derivative having a purity of less than 95% by weight that can be produced without going through multiple distillation / purification steps. However, in the case of long-chain fatty acid dicarboxylic acid derivatives such as dimer acid, the degree of polymerization does not increase sufficiently due to the monomer acid contained as an impurity, or the degree of crosslinking increases due to trimer acid, resulting in a decrease in mechanical properties. It has been considered that it is difficult to industrially manufacture a product with good quality.

Japanese Patent Publication No.57-48577 Japanese Patent Publication No.42-8709 Japanese Patent Publication No.54-15913 Japanese Patent No. 3151875 Japanese Patent No. 3200848 JP-A-6-73277 JP 2002-12749 A

  Accordingly, an object of the present invention is to eliminate the drawbacks of the prior art, and is produced using a long-chain aliphatic dicarboxylic acid derivative containing impurities such as monomeric acid and trimer acid as a polymerization raw material. Provided is a copolyester or a polyester resin composition capable of producing a polyester film excellent in transparency, flexibility, heat resistance, bleed-out resistance, and whitening resistance over time even when a copolyester is used. There is.

  In order to significantly reduce the production cost by using a relatively low-purity product rather than a high-purity product of fatty acid (derivative), the present invention contains dimers and trimers in the fatty acid (derivative). Obtaining the knowledge that it is effective to make the composition such as the amount within a specific range and the polymerization composition and melt viscosity of the copolymerized polyester obtained by copolymerization within the specific range, the present invention has been achieved. It is.

That is, the copolymer polyester of the present invention contains, as an acid component, a fatty acid monomer, a fatty acid dimer, and an aliphatic trimer, and the fatty acid dimer and the fatty acid trimer are 70 to 90 % by weight, A copolymerized polyester synthesized from a composition containing a fatty acid or a derivative thereof in a ratio of 10 to 30 % by weight and containing 1,4-butanediol as a glycol component, and constituting the copolymerized polyester In the unit, the content of the fatty acid (derivative) residue in the acid component is 5 to 50 mol%, the content of the 1,4-butanediol residue in the glycol component is 42 to 90 mol%, and This can be achieved by the fact that the melt viscosity of the polymerized polyester is 1000 to 3000 poise at 250 ° C. Hereinafter, this copolyester is referred to as copolyester A.

  Furthermore, even when the degree of polymerization is considerably reduced by using a low-purity fatty acid derivative, a polyester resin composition having practical characteristics can be obtained by using a resin composition having the following formulation.

It is a copolymerized polyester synthesized from a composition containing a fatty acid or a derivative thereof containing, as an acid component, a fatty acid dimer and a trimer in a proportion of 15% by weight or more and less than 95% by weight and 5 to 85% by weight, respectively. A polyester resin comprising an aromatic polyester and a copolymer polyester containing 20 to 80 mol% of a fatty acid (derivative) residue as an acid component in its constituent components and having a melt viscosity of 50 to 450 poise at 250 ° C. Composition. Thus, the said copolyester in the case of mixing with other aromatic polyesters and setting it as a resin composition is called copolyester B below.

  According to the present invention, it is possible to obtain a copolymer polyester, a polyester resin composition, and a polyester film that are excellent in flexibility, transparency, whitening resistance, and cost. The film obtained by this invention can be preferably used for uses, such as an industrial material and a packaging material which require a softness | flexibility and easy moldability.

  The copolymer polyester A in the present invention includes, as an acid component, a hard segment containing an aromatic dicarboxylic acid residue as a main constituent, a soft segment containing a residue consisting of a fatty acid (derivative) as a main constituent, and a glycol. It is composed of a 1,4-butanediol residue and other glycol residues having 10 or less carbon atoms that are included as necessary. In addition, the copolymer polyester B also contains a soft segment whose main constituent is a residue composed of the fatty acid (derivative) described above, but the glycol component is not particularly limited.

  In these copolyesters A and B, the aromatic dicarboxylic acid residue constituting the hard segment is formed from an aromatic dicarboxylic acid and an ester-forming derivative thereof. Specifically, for example, isophthalic acid, terephthalic acid, diphenyl-4,4′-dicarboxylic acid, 2,6-naphthalenedicarboxylic acid, naphthalene 2,7-dicarboxylic acid, naphthalene 1,5-dicarboxylic acid, diphenoxyethane Examples include 4-4′-dicarboxylic acid, diphenylsulfone-4, 4′-dicarboxylic acid, diphenyl ether-4, 4′-dicarboxylic acid, and ester-forming derivatives thereof. Of these, terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, and ester-forming derivatives thereof are preferable. These aromatic dicarboxylic acid components may be used alone or in combination of two or more.

  In the case of the copolyester A, the amount of the aromatic acid residue is preferably 50 to 95 mol% of the acid component. More preferably, it is 55-93 mol%, More preferably, it is 60-90 mol%. When the amount of the aromatic dicarboxylic acid residue is less than 50 mol%, the heat resistance of the copolyester is lowered, and the mechanical properties of the molded product obtained therefrom may be lowered. On the other hand, when it exceeds 95 mol%, the flexibility of the molded product may be lowered.

  Further, the fatty acid derivative constituting the soft segment in the copolyesters A and B is preferably derived from an unsaturated fatty acid having 10 to 30 carbon atoms represented by the following formula, and is mainly a dimerized fatty acid obtained by dimerization thereof. Alternatively, it is formed from an ester-forming derivative thereof.

CH ₃ (CH ₂ ) _m (CH═CH—CH ₂ ) _k (CH ₂ ) _n COOR
(In the formula, R is a hydrogen atom or an alkyl group, m is an integer of 1 to 25, k is an integer of 1 to 5, n is an integer of 0 to 25, and m, k, and n are 8 ≦ m + 3k + n ≦ 28. Satisfies the relational expression.)

  In this dimerization reaction of unsaturated fatty acid, a trimer is produced together with the dimer, and therefore the dimer, trimer and monomer are contained in the fatty acid derivative obtained by the dimerization reaction. . Even when this fatty acid derivative is used as a raw material for polymerization without any particular purification, the ratio of dimer and trimer must be 15% by weight or more and less than 95% by weight and 5% by weight or more and 85% by weight or less, respectively. Preferably, the dimer is 70% by weight to 90% by weight and the trimer is 10% by weight to 30% by weight. When the dimer is less than 15% by weight and / or the trimer is less than 5% by weight, the reactivity during the production of the copolyester is lowered, and the degree of polymerization is hardly increased. Alternatively, when the trimer exceeds 85% by weight, the degree of crosslinking of the polyester increases, so that the degree of polymerization and mechanical properties tend to decrease.

  The fatty acid derivative used in the production of the copolyesters A and B of the present invention has an unsaturated bond produced by a dimerization reaction. You may use after reducing. However, particularly when heat resistance, weather resistance, and transparency are required, it is preferable to use a dimerized fatty acid in which unsaturated bonds are eliminated by hydrogenation.

  As the dimerized unsaturated fatty acid that can be used in the production of the copolyesters A and B of the present invention, dimer acid that is a dimerized fatty acid having 36 carbon atoms and an ester-forming derivative thereof are preferable. The dimer acid is obtained by dimerizing an unsaturated fatty acid having 18 carbon atoms such as linoleic acid and linolenic acid. For example, “Pripol” from Unikema International, or various esters thereof. Forming derivatives are commercially available. One or more of the above compounds may be used in combination.

  In the case of the copolymer polyester A, the amount of the fatty acid derivative residue in the copolymer polyester of the present invention is required to be 5 to 50 mol% of the acid component, more preferably 7 to 45%, and still more preferably 9 -40 mol%. When the amount of the fatty acid derivative residue exceeds 50 mol%, the heat resistance of the polyester may be lowered, and the mechanical properties of the molded product obtained therefrom may be lowered. On the other hand, if the amount of the fatty acid derivative residue is less than 5 mol%, the flexibility of the molded product obtained from the polyester may be lowered.

  In the copolyester B, the amount of the fatty acid derivative residue needs to be 20 to 80 mol% of the acid component, and more preferably 22 to 50%.

  The glycol component of the copolymerized polyester A of the present invention must contain at least a 1,4-butanediol residue. If necessary, other than 1,4-butanediol represented by the following formula: The above-mentioned glycol residues (referred to as other glycol residues) may be contained.

-O-X-O-
(X in the formula is an alkylene group other than a tetramethylene group, an alkylene group having a side chain composed of an alkyl group or a cycloalkyl group, or a cycloalkylene group and an alkylene group.)

  Specific examples of glycol components for other glycol residues (referred to as other glycol components) include, for example, ethylene glycol, 1,3-propanediol, 1,2-propanediol, 2-methyl-1, 3-propanediol, 1,3-butanediol, 1,2-butanediol, 1,5-pentylglycol, 2,2-dimethyl-1,3-propanediol, 2-ethyl-1,3-propanediol, 1,6-hexanediol, 2-methyl-2-ethyl-1,3-propanediol, 1,8-octanediol, 1,10-decanediol, 1,3-cyclobutanediol, 1,3-cyclobutanedimethanol 1,3-cyclopentanedimethanol, 1,4-cyclohexanedimethanol and the like.

  In the case of the copolymerized polyester A of the present invention, the amount of 1,4-butanediol residue needs to be 42 to 100 mol%, more preferably 42 to 90 mol%, still more preferably 45 to 85 mol%. It is. On the other hand, the amount of other glycol residues is 58 mol% or less, preferably 10 to 58 mol%, more preferably 15 to 55 mol%. If the amount of 1,4-butanediol residue is less than 42 mol%, the crystallization rate of the polyester decreases, and it becomes difficult to form by sticking at the time of molding, or the transparency of the resulting molded product is lowered. Sometimes.

  In the case of the copolyester B, the type and composition of the glycol component are not particularly limited, and any of the above glycol components may be used, but it is preferable that a 1,4-butanediol residue is included. .

  In the copolymerized polyester of the present invention, in addition to the above components, other components may be copolymerized within a range not impairing the object of the present invention, or a resin composed of other components can be mixed. For example, as copolymerizable acid components, 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, 5-sodium sulfoisophthalic acid trimellitic acid, trimesic acid, trimellitic acid Trimesic acid and the like, or ester derivatives thereof, p-oxybenzoic acid, p-hydroxymethylbenzoic acid, or ester derivatives thereof as the hydroxycarboxylic acid component, and 1,12-dodecanediol, diethylene glycol as the alcohol component, Polyoxyalkylene glycol, 1,2-cyclohexanediol, 1,3-cyclohexanediol, 1,4-cyclohexanediol, spiroglycol, or bisphenol A, bisphenol S and their ethyleneoxy Adduct, trimethylolpropane and the like.

  In the case of the copolyester A of the present invention, the melt viscosity is required to be 1000 to 3000 poise at 250 ° C., more preferably 1300 to 2300 poise. When the melt viscosity of the polyester exceeds 3000 poise, when the polyester is extruded into a film or the like, the extruded state may not be stable and may give a non-uniform film thickness. Furthermore, the partially thickened portion may be whitened and spotted. Also, if the melt viscosity is less than 1000 poise, film formation may be difficult due to insufficient viscosity.

  In the case of the copolyester B, the melt viscosity at 250 ° C. needs to be 50 to 1500 poise, more preferably 70 to 1000 poise.

  The method for producing the above-described copolymer polyesters A and B of the present invention is not particularly limited, and can be produced by a normal polyester polymerization method. For example, a method obtained by directly copolymerizing a composition containing 1,4-butanediol and another glycol component, aromatic dicarboxylic acid, and fatty acid derivative within the specific range described above may be used, or two or more types may be used. Alternatively, the polymer and / or copolymer may be melt-kneaded in an extruder so as to have the above-described specific polymerization composition.

  As the latter method, an aromatic polyester composed of an aromatic dicarboxylic acid and a glycol component and an aliphatic-aromatic polyester copolymer composed of an aromatic dicarboxylic acid, a fatty acid derivative and a glycol component are placed in an extruder. Examples thereof include a method of melting and kneading to achieve the above-described specific polymerization composition. Cost advantage that general-purpose aromatic polyesters such as polyethylene terephthalate (PET) and polybutylene terephthalate (PBT) can be used, and inclusion in copolymer polyester A only by changing the mixing amount of aromatic polyester and copolymer From the viewpoint of handleability in which the components can be freely controlled, a method in which an aromatic polyester and an aliphatic-aromatic polyester copolymer are melt-kneaded in an extruder to obtain the above-described specific polymerization composition is preferable. Aromatic polyester, that is, terephthalic acid and ethylene glycol, that is, PET, and an aliphatic-aromatic polyester copolymer whose constituent components are terephthalic acid and a fatty acid derivative and 1,4-butanediol are melt-kneaded in an extruder. The specific polymerization composition Preferred.

  Moreover, in the case of the copolyester B which contains a fatty acid derivative in high concentration, after making it the resin composition mixed with the other aromatic polyester, it uses for shaping | molding etc. That is, using this copolyester B as a master pellet, this is appropriately diluted with another aromatic polyester so as to have a desired polymerization composition, and using an extruder, the polyester resin composition or the polyester film of the present invention is prepared. To get.

  In this case, the content of the fatty acid derivative in the acid component is 20 to 80 mol%, preferably 22 to 50 mol%, from the viewpoint of handling properties when the copolymerized polyester B is used after being diluted. . In order to improve the transparency of the polyester resin molded product obtained using this copolyester B, the melt viscosity of the copolyester B is 50 to 1500 poise at 250 ° C., preferably 70 to 1000 poise.

  In addition, the aromatic polyester used for the dilution contains an aromatic dicarboxylic acid residue and a 1,4-butanediol residue from the viewpoint of improving the transparency of the resulting polyester resin molded product. It is preferable that at least one kind of polyester which is a group and / or another diol residue is used, and 30% by weight or more of the total glycol component in the entire aromatic polyester is preferably 1,4 butanediol residue, more preferably Is an aromatic polyester resin composition containing 30% by weight or more of polybutylene terephthalate, and a resin composition of polyethylene terephthalate (70% by weight or less) and polybutylene terephthalate (30% by weight or more) is particularly preferable.

  The method of making a resin composition using a copolymerized polyester B containing a fatty acid derivative at a high concentration is advantageous for cost reduction because a general-purpose polyester such as polyethylene terephthalate (PET) or polybutylene terephthalate (PBT) is used. Further, even when the degree of polymerization of the copolyester B is very low and it is difficult to handle by itself, there is an advantage that it can be molded by mixing with an aromatic polyester, and the handling property is also good.

  Even in the case of the resin composition comprising the copolymer polyester B and the aromatic polyester, the content of the fatty acid (derivative) residue in the acid component is 5 to 50 mol% in all repeating units constituting the glycol component, The content of 1,4-butanediol residue is preferably 42 to 100 mol%, and the melt viscosity of the resin composition is preferably 1000 to 3000 poise at 250 ° C.

  In order to improve the melt viscosity of the copolymerized polyester A obtained by copolymerization or to improve the transparency of the polyester resin molded product when the copolymerized polyester B is used, the following It is preferable to add a compatibilizing agent at the time of copolymerization or resin mixing. Examples of the compatibilizer include diglycidyl hexahydrophthalate, diglycidyl terephthalate, diglycidyl phthalate, bisphenol S diglycidyl ether, and polyethylene glycol diglycidyl ether, 1,4-phenylenebisoxazoline, 1,3 -Various oxazolines such as phenylenebisoxazoline, various ester compounds of various fatty acids such as stearic acid, oleic acid, lauric acid and polyether, and organic acids such as hydrochloric acid, sulfuric acid, nitric acid, p-toluenesulfonic acid, Of these, bisoxazoline or organic acid is preferably used. The mechanism of improving the melt viscosity or transparency by adding the above compound is not necessarily clear. Further, the present invention is not limited to a specific mechanism or hypothesis, but for example, it can be explained by the following model.

[Bisoxazoline addition effect]
Addition of bisoxazoline, which is a bifunctional compound, causes the carboxylic acid ends in the copolyester A chain to react with each other, contributing to an increase in molecular weight, which is one of the main factors for improving melt viscosity. In addition, when the aromatic polyester and an aliphatic-aromatic polyester copolymer composed of an aromatic dicarboxylic acid, a fatty acid derivative and a glycol component are melt-kneaded to obtain a copolymerized polyester A or a film thereof, a fatty acid derivative In the case where a polyester molded article is produced from a resin composition comprising a copolymer polyester B and an aromatic polyester containing a high concentration of bisoxazoline, in addition to the above effects, two functional groups of bisoxazoline are different polymers (for example, In the case of an aromatic polyester and an aliphatic-aromatic polyester copolymer, a block copolymer is formed by adding to the carboxylic acid terminal of each of the aromatic polyester and the copolymer polyester B). Improves compatibility between different polymers and improves transparency.

[Organic acid addition effect]
When melt-kneading an aromatic polyester and an aliphatic-aromatic polyester copolymer to obtain a copolymer polyester A or a film thereof, a polyester molded product from a resin composition comprising the copolymer polyester B and an aromatic polyester In the production, the transesterification reaction between different polymers is promoted by the acid catalyst effect of the organic acid, the formation of the copolyester is promoted, and the transparency is improved by homogenizing the polymer chain.

  The addition amount when the compatibilizer shown above is added to the copolyester A may be any amount that has the desired viscosity level and exhibits the desired transparency, and is generally 0.1%. ~ 5 wt% is preferred. Moreover, generally the addition amount in the case of adding a compatibilizer to the said polyester resin composition has preferable 0.1 to 5 weight%.

  In order to obtain good flexibility, the glass transition point (Tg) of the copolyesters A and B in the present invention is preferably 25 ° C. or lower, more preferably 20 ° C. or lower, and further preferably 15 ° C. or lower. It is.

  The polyester film of the present invention is a film obtained by forming a film by a usual method after adding various particles and additives to the above-described copolymerized polyester A or the above-described polyester resin composition as necessary. For example, it is produced by melt-extrusion cooling and solidification, and if necessary, stretching or heat treatment.

  The particles to be added to the polyester film are appropriately selected according to the purpose and application, and are not particularly limited as long as the effects of the present invention are not impaired. Inorganic particles, organic particles, crosslinked polymer particles, and produced in a polymerization system Internal particles can be mentioned. Two or more kinds of these particles may be added. From the viewpoint of the mechanical properties of the polyester resin composition, the amount of such particles added is preferably 0.01 to 10% by weight, more preferably 0.02 to 1% by weight.

  Moreover, the average particle diameter of the particle to add becomes like this. Preferably it is 0.001-10 micrometers, More preferably, it is 0.01-2 micrometers. When the average particle diameter is within such a preferable range, defects in the resin composition and the film are hardly generated, and it is difficult to cause deterioration of transparency and moldability.

  The inorganic particles are not particularly limited, but various carbonates such as calcium carbonate, magnesium carbonate and barium carbonate, various sulfates such as calcium sulfate and barium sulfate, various composite oxides such as kaolin and talc, lithium phosphate, calcium phosphate Fine particles comprising various phosphates such as magnesium phosphate, various oxides such as aluminum oxide, silicon oxide, titanium oxide and zirconium oxide, various salts such as lithium fluoride, and the like can be used.

  As the organic particles, fine particles made of calcium oxalate, terephthalate such as calcium, barium, zinc, manganese, magnesium, or the like are used. Examples of the crosslinked polymer particles include fine particles made of a vinyl monomer such as divinylbenzene, styrene, acrylic acid or methacrylic acid, or a copolymer. In addition, organic fine particles such as polytetrafluoroethylene, benzoguanamine resin, thermosetting epoxy resin, unsaturated polyester resin, thermosetting urea resin, and thermosetting phenol resin are also preferably used.

  As the internal particles generated in the polymerization system, particles generated by a known method in which an alkali metal compound, an alkaline earth metal compound, or the like is added to the reaction system and a phosphorus compound is further added may be used.

  In the polyester film of the present invention, as long as the effects of the present invention are not impaired, known additives such as flame retardants, heat stabilizers, antioxidants, ultraviolet absorbers, antistatic agents, An appropriate amount of a plasticizer, a tackifier, an organic lubricant such as a fatty acid ester or wax, an antifoaming agent such as polysiloxane, or a coloring agent such as a pigment or a dye can be blended.

  The film structure may be a single layer, or may be a laminated structure in which layers for imparting new functions such as slipperiness, adhesiveness, tackiness, heat resistance, and weather resistance are formed on the surface. . For example, when laminating B and C layers having different resin or additive compositions on layer A containing a fatty acid derivative, two layers A / B, B / A / B, B / A / C, or Examples include A / B / C three layers. Furthermore, if necessary, it may have a laminated structure of more than three layers, and the lamination thickness ratio of each layer can be arbitrarily set.

  The polyester film of the present invention preferably has an elastic modulus in the range of 1 to 1000 MPa at 25 ° C. When the elastic modulus is in such a preferable range, when used in the form of a film, the deformation is small, there is no problem in handling, and the low temperature formability is excellent. In order to make the elastic modulus in the range of 1 to 1000 MPa at 25 ° C., for example, a method of changing the fatty acid content as necessary or using a fatty acid having a high softening effect can be mentioned.

  The polyester film of the present invention may be an unstretched film or a stretched film. The stretched film may be either a uniaxially stretched film stretched in either the longitudinal direction or the width direction of the film, or a biaxially stretched film stretched in both the longitudinal direction or the width direction of the film.

  Moreover, it is preferable to set it as a stretched film from a viewpoint of whitening-proof whitening, and it is still more preferable to set it as a biaxially stretched film. The plane orientation coefficient in the case of a biaxially stretched film is preferably 0.0030 to 0.150, more preferably 0.050 to 0.140, from the viewpoint of preventing whitening during processing and maintaining workability. Particularly preferred is 0.080 to 1.130.

Here, the plane orientation coefficient (fn) is a value calculated by the following equation from refractive indexes (Nx, Ny, Nz, respectively) in the film longitudinal direction, width direction, and thickness direction measured using an Abbe refractometer or the like. is there.
Plane orientation coefficient: fn = (Nx + Ny) / 2−Nz

  In addition, the polyester film of the present invention has a thermal shrinkage rate in the range of −10 to 10% at least at the molding temperature from the viewpoint of suppressing adhesion and workability, particularly film wrinkling during processing. Is preferred. More preferably, the heat shrinkage rate is in the range of −5 to + 5%. When the thermal shrinkage is within this range, good workability can be imparted without causing problems such as the film surface swelling to impair the appearance, peeling from the base material, or distorting printing.

  Next, the case where a film is produced using a resin composition obtained by adding copolymer polyester B (master pellet) containing a fatty acid derivative at a high concentration to an aromatic polyester will be specifically described.

  Aromatic polyester and copolymerized polyester B are weighed using a metering device according to their properties and fed to a twin screw extruder at a predetermined ratio. As the twin screw extruder, a vent type twin screw extruder can be preferably used because the aromatic polyester can be supplied in an undried state. Polyester B is preferably supplied after drying / dehydration treatment in advance. The supplied aromatic polyester and copolymer polyester B are melt-mixed and molded at an extrusion temperature of 200 to 300 ° C. according to the melt viscosity of the aromatic polyester. In the case of forming into a film, the molten mixed resin is guided to a slit-shaped base, extruded onto a cooling casting drum in a sheet shape, and cooled to form an unstretched film. When the T-die method is used, an electrostatic application adhesion method or a touch roll casting method can be used at the time of rapid cooling, and an unstretched film having a uniform thickness can be obtained particularly by the electrostatic application adhesion method.

  In the case of obtaining a stretched film, the unstretched film obtained above is then sent to a stretching apparatus and stretched by a uniaxial stretching method, a simultaneous biaxial stretching method, a sequential biaxial stretching method, or the like. In the case of sequential biaxial stretching, the stretching order may be the order of the film in the longitudinal direction and then the width direction, or vice versa. Furthermore, in the sequential biaxial stretching, the stretching in the longitudinal direction or the width direction can be performed twice or more.

  The stretching method is not particularly limited, and methods such as roll stretching and tenter stretching can be employed. The film shape during stretching may be any shape such as a flat shape or a tube shape. The stretching ratio in the longitudinal direction and the width direction of the film can be arbitrarily set according to desired properties such as intended flexibility, processability, deposition suitability, etc., but preferably 1 for improving thickness unevenness. .5 to 6.0 times. The stretching temperature can be any temperature as long as it is in the range from the glass transition temperature of the polyester to [melting point−20 ° C.], but is preferably 30 to 150 ° C.

  The thickness of the film can be freely determined according to the application to be used. The thickness is usually in the range of 0.5 to 1000 μm, preferably 1 to 500 μm, more preferably 5 to 200 μm from the viewpoint of film formation stability.

  Furthermore, the film can be heat treated after stretching. The heat treatment temperature can be any temperature below the melting point of the polyester, but is preferably 100 to 240 ° C. Such heat treatment may be performed while relaxing the film in the longitudinal direction and / or the width direction.

  The polyester film of the present invention can be improved in adhesion and printability as necessary by performing surface treatment such as corona discharge treatment. Various coatings may be applied, and the type, coating method, and thickness of the coating compound are not particularly limited as long as the effects of the present invention are not impaired. Furthermore, it can be used after being subjected to molding processing such as embossing, printing, or the like, if necessary.

  The polyester film of the present invention can be used as various industrial materials and packaging materials that require easy moldability with a single sheet or a composite sheet. In the composite sheet, it can be used by being bonded to a base material such as metal, wood, paper, resin sheet or resin plate.

  Specific applications include applications in which conventional flexible films and easily molded films have been used, such as packaging films, wrap films, stretch films, partition films, wallpaper films, and plywood decorative sheets. However, the present invention is not limited to this.

Hereinafter, the present invention will be described in detail by way of examples. Various characteristics were measured and evaluated by the following methods.
(1) Composition ratio of monomer, dimer and trimer in fatty acid (derivative) The composition ratio was determined from the peak area of each component by analysis by high performance liquid chromatography.
(2) Intrinsic viscosity of polyester Polyester was dissolved in orthochlorophenol and measured at 25 ° C.

(3) Melt viscosity of polyester or polyester resin composition The polyester was vacuum-dried at 150 ° C for 5 hours or more, and then measured at 250 ° C using a melt index.

(4) Film formation stability The stability at the time of polyester film formation was determined according to the following criteria.
○: The film can be stably formed with a constant discharge amount.
(Triangle | delta): Although discharge becomes unstable temporarily, there is almost no problem in film forming property.
X: The discharge amount is clearly unstable, and stable film formation is difficult.

(5) Transparency of film The transparency of the polyester film was determined based on the following criteria from the haze value measured using a fully automatic direct reading haze computer HGM-2DP manufactured by Suga Test Instruments Co., Ltd.
A: Haze value less than 10%,
○: Haze value 10% or more and less than 30%,
Δ: Haze value 30% or more and less than 70%,
X: Haze value 70% or more,

(6) Whitening resistance of film over time About a film after being put into a 40 ° C. gear oven for one week, a haze value was measured using a fully automatic direct reading haze computer HGM-2DP manufactured by Suga Test Instruments Co., Ltd. Judged by criteria.
A: Haze value less than 15%,
○: Haze value 15% or more and less than 40%,
Δ: Haze value 40% or more and less than 70%,
X: Haze value 70% or more,

(7) Elastic modulus of film It measured at 25 degreeC using Orientec Co., Ltd. product tensilon. The film was kept at the measurement temperature for 30 seconds, and the elastic modulus (MPa) in the film longitudinal direction and the width direction was measured at 10 points each at a tensile rate of 300 mm / min. Asked.

[Polymerization of aromatic polyester]
(PET)
To a mixture of 100 parts by weight of dimethyl terephthalate and 60 parts by weight of ethylene glycol, 0.09 parts by weight of magnesium acetate and 0.03 parts by weight of diantimony trioxide are added, and the temperature is raised by a conventional method to perform a transesterification reaction. It was. Next, 0.026 part by weight of trimethyl phosphate is added to the transesterification reaction product, and then transferred to the polycondensation reaction layer. Next, the reaction system was gradually depressurized while being heated and heated, and polymerization was performed at 290 ° C. under a reduced pressure of 1 mmHg by a conventional method to prepare a polyester having an intrinsic viscosity of 0.65.

(PBT)
To a mixture of 100 parts by weight of dimethyl terephthalate and 60 parts by weight of 1,4-butanediol, 0.05 part by weight of tetrabutyl titanate was added to perform a transesterification reaction, and then 0.03 part by weight of trimethyl phosphate was added to the PET. The same polycondensation reaction was carried out to produce a polyester having an intrinsic viscosity of 0.85.

(PET / I)
To a mixture of 83 parts by weight of dimethyl terephthalate, 17 parts by weight of dimethyl isophthalate and 60 parts by weight of ethylene glycol, 0.09 parts by weight of magnesium acetate and 0.03 parts by weight of antimony trioxide are added, and the temperature is raised by a conventional method. Then, 0.026 parts by weight of trimethyl phosphate was added and a polycondensation reaction similar to PET was performed to produce a polyester having an intrinsic viscosity of 0.65.

  Tables 1 and 2 show the compositions of the copolyesters used in the examples and comparative examples.

In Table 1 and Table 2 above,
DMT: terephthalic acid residue C36: dimer acid residue (main chain carbon number 36)
C44: Dimerized fatty acid residue (44 main chain carbon atoms)
EG: ethylene glycol residue BG: butanediol residue CHDM: 1,4-cyclohexanedimethanol residue NPG: 2,2-dimethyl-1,3-propanediol

[Synthesis of Copolyester]
(Synthesis of copolymer polyester 1 in Table 1)
3 parts by weight of sulfuric acid was added to a mixture of 50 parts by weight of “PRIPOL 1025” (“PRIPOL 1025”) (manufactured by Unikema International) and 50 parts by weight of methanol, and after refluxing for 10 hours, drying was carried out. %, Dimer 78.6% and trimer 19.2% were prepared.

  Add 95 parts by weight of dimethyl terephthalate, 22 parts by weight of dimethyl dimer having 36 carbon atoms obtained above, 15 parts by weight of ethylene glycol, 50 parts by weight of 1,4-butanediol and 0.1 part by weight of tetrabutyl titanate, After performing the exchange reaction, a polycondensation reaction was performed under high temperature and reduced pressure to prepare a copolyester having a melt viscosity of 1800 poise and an intrinsic viscosity of 0.82. The composition of the obtained copolymer polyester was 94 mol% terephthalic acid residue, 6 mol% dimer acid residue, 15 mol% ethylene glycol residue, and 85 mol% 1,4-butanediol residue.

(Synthesis of copolymer polyester 2 in Table 1)
61 parts by weight of dimethyl terephthalate, 33 parts by weight of dimethyl dimer acid having 36 carbon atoms, consisting of 2.2% monomer, 78.6% dimer and 19.2% trimer, 20 parts by weight ethylene glycol, After adding 40 parts by weight of 4-butanediol and 0.1 part by weight of tetrabutyl titanate and carrying out a transesterification reaction, 2 parts by weight of 1,4-phenylenebisoxazoline was further added to 100 parts by weight of the resulting resin. Then, a polycondensation reaction was performed under high temperature and reduced pressure to prepare a copolyester having a melt viscosity of 1900 poise and an intrinsic viscosity of 0.85. The composition of the obtained copolymer polyester was 85 mol% terephthalic acid residue, 15 mol% dimer acid residue, 20 mol% ethylene glycol residue, and 80 mol% 1,4-butanediol residue.

(Synthesis of copolymer polyester 3-16)
The composition described in Table 1 or Table 2 was polymerized by the same method as for the copolyester 1 or 2, to synthesize copolyesters having respective compositions and viscosities.
(Synthesis of copolymer polyester 17)
Polymerization was attempted with the composition shown in Table 2 in the same manner as for copolyester 1, but no polymer could be obtained.

(Synthesis of copolymer polyester 18 (aliphatic-aromatic copolymer polyester))
The composition shown in Table 2 was polymerized by the same method as that for copolymer polyester 1, to synthesize copolymer polyester 18 (aliphatic-aromatic copolymer polyester) having the viscosity shown in Table 2.

Example 1
The copolymerized polyester 1 was supplied to a vent type different-direction twin screw extruder (3 vent portions, L / D = 42), and passed through 2 vacuum vent portions and a short tube while being heated at 260 ° C. Next, the sheet was extruded from a slit-shaped die into a sheet shape, adhered to a casting drum by an electrostatic application method, and solidified by cooling to obtain an unstretched film. The unstretched film was able to be produced stably, and the physical properties of the obtained film showed good transparency as shown in Table 3.

(Example 2)
An unstretched film was produced in the same manner as in Example 1 except that the copolymer polyester 2 was used. The physical properties of the obtained unstretched film are as shown in Table 3. Compared with Example 1, the bisoxazoline was added to the copolyester 2, so that it was particularly excellent in flexibility and aging resistance. It was.

( Reference Example 3)
An unstretched film was produced in the same manner as in Example 1 except that the copolymer polyester 3 was used. The physical properties of the obtained unstretched film are as shown in Table 3. Although it is slightly inferior to the film forming stability as compared with Example 1, it is at a practical level and has good flexibility properties.

( Reference Example 4)
An unstretched film was produced in the same manner as in Example 1 except that the copolymer polyester 4 was used. The physical properties of the obtained unstretched film are as shown in Table 3. Compared with Example 1, the film-forming stability and transparency are slightly inferior, but at a practical level and have relatively good flexibility characteristics. Was.

( Reference Example 5)
An unstretched film was produced in the same manner as in Example 1 except that the copolymer polyester 5 was used. The physical properties of the obtained unstretched film are as shown in Table 3. Compared with Example 1, the film-forming stability and transparency are slightly inferior, but at a practical level and have relatively good flexibility characteristics. Was.

(Example 6)
The copolymer polyester 9 is used as the copolymer polyester B, PET and PBT are used as the aromatic polyester, and the copolymer polyester 8 // PET // PBT is melt-blended at a ratio of 60 wt% // 10 wt% // 30 wt%. Thus, a resin composition was prepared. An unstretched film was produced in the same manner as in Example 1 except that this resin composition was used. The physical properties of the obtained unstretched film are as shown in Table 4, and showed good film-forming stability, transparency, flexibility and resistance to whitening with time.

( Reference Example 7)
As the copolyester B, the copolyester 7 is used, PET and PBT are used as the aromatic polyester, and the copolyester 7 // PET // PBT is melted at a ratio of 60 wt% // 10 wt% // 30 wt%. A resin composition was prepared by blending. An unstretched film was produced in the same manner as in Example 1 except that this resin composition was used. The characteristics of the obtained film are as shown in Table 4, which is a practical level although the transparency is slightly lowered as compared with Example 6, and shows good film-forming stability, flexibility, and resistance to whitening over time. .

( Reference Example 8)
Copolymer polyester B is used as copolymer polyester B, PET / I and PBT are used as aromatic polyester, copolymer polyester 7 // PET / I // PBT is 60 wt% // 10 wt% // 30 wt%. A resin composition was prepared by melt blending at a ratio. An unstretched film was produced in the same manner as in Example 1 except that this resin composition was used. The characteristics of the obtained film are as shown in Table 4, which is a practical level although the transparency is slightly lowered as compared with Example 6, and shows good film-forming stability, flexibility and resistance to whitening with time. It was a thing.

( Reference Example 9)
Copolymer polyester 7 is used as copolymer polyester B, PET and PBT are used as aromatic polyester, and copolymer polyester 7 // PET // PBT is blended at a ratio of 60 wt% // 10 wt% // 30 wt%. Further, 2 parts by weight of 1,4-phenylenebisoxazoline was added to 100 parts by weight of this resin composition and melt blended to prepare a resin composition. An unstretched film was produced in the same manner as in Example 1 except that this resin composition was used. The characteristics of the obtained film were as shown in Table 4, and showed good film forming stability, transparency and flexibility.

(Example 10)
The copolymerized polyester 6 and the copolymerized polyester 8 are blended at a ratio of 20 wt% // 80 wt% (wt // wt), and 1,4-phenylenebisoxazoline is added in an amount of 2 parts per 100 parts by weight of the resin composition. Part by weight was added and melt blended to prepare a resin composition. An unstretched film was produced in the same manner as in Example 1 except that this resin composition was used. The properties of the obtained film were as shown in Table 3, and showed good film forming stability, transparency and flexibility.

(Example 11)
An unstretched film was produced in the same manner as in Example 1 except that the copolyester 11 was used. The physical properties of the obtained unstretched film are as shown in Table 3, and showed good film forming stability and transparency.

(Example 12)
An unstretched film was produced in the same manner as in Example 1 except that the copolyester 12 was used. The physical properties of the obtained unstretched film are as shown in Table 3, and showed good film forming stability, flexibility, and excellent transparency.

(Example 13)
An unstretched film was produced in the same manner as in Example 1 except that the copolyester 13 was used. The physical properties of the obtained unstretched film are as shown in Table 3, and showed good film-forming stability, flexibility and transparency.

(Example 14)
The copolymer polyester 9 is used as the copolymer polyester B, PET and PBT are used as the aromatic polyester, and the copolymer polyester 9 // PET // PBT is melted at a rate of 60 wt% / 10/10 wt% / 30 wt%. A resin composition was prepared by blending. This resin composition was supplied to a vent type different-direction twin screw extruder (3 vent portions, L / D = 42), passed through 2 vacuum vent portions, heated at 260 ° C., and 2 vacuum vent portions and A short tube was passed. Next, it is extruded into a sheet form from a slit-shaped die, and is cooled and solidified by being in close contact with a casting drum by an electrostatic application method. A biaxially stretched film adjusted to a thickness of 100 μm was prepared by stretching at 3.5 times. The physical properties of the obtained biaxially stretched film are as shown in Table 3. Compared with Example 6, particularly, the whitening resistance with time was improved due to orientation crystallization.

(Example 15)
(Synthesis of copolymer polyester 19)
The PET is used as the aromatic polyester, the copolymer polyester 18 is used as the aliphatic-aromatic polyester, and the PET // copolymer polyester 18 is mixed at a ratio of 18 wt% // 88 wt%. Supply to twin screw extruder (3 vents, L / D = 42), pass through 2 vacuum vents and short pipe while heating at 260 ° C, and immediately discharge the gut after discharging from the die in ice water The copolymer polyester 19 having physical properties described in Table 2 was prepared by quenching.

(Film)
The PET // copolymerized polyester 18 was mixed at a ratio of 18 wt% // 88 wt% and supplied to a vent type different direction twin screw extruder (3 vent portions, L / D = 42) at 260 ° C. While heating, two vacuum vents and a short tube were passed. Next, the sheet was extruded from a slit-shaped die into a sheet shape, adhered to a casting drum by an electrostatic application method, and solidified by cooling to obtain an unstretched film. The unstretched film could be prepared stably, and the physical properties of the obtained film as shown in Table 5 showed good film forming stability, flexibility and resistance to whitening with time.

(Example 16)
(Synthesis of copolymer polyester 20)
The PET is used as the aromatic polyester, the copolymer polyester 18 is used as the aliphatic-aromatic polyester, and the PET // copolymer polyester 18 is mixed at a ratio of 18 wt% // 88 wt%. After adding 2 parts by weight of p-toluenesulfonic acid to 100 parts by weight of the mixture, it is supplied to a vent type different direction twin screw extruder (3 vents, L / D = 42) and heated at 260 ° C. while being vacuumed. Two vent parts and a short pipe were passed, and the gut discharged from the die was immediately cooled in ice water to produce a copolymerized polyester 20 having the physical properties shown in Table 2.

(Film)
The PET // copolymerized polyester 18 was mixed at a ratio of 18 wt% // 88 wt%, and 2 parts by weight of p-toluenesulfonic acid was added to 100 parts by weight of the resin mixture. It supplied to the twin-screw extruder (3 vent parts, L / D = 42), and let it pass through 2 vacuum vent parts and a short tube, heating at 260 degreeC. Next, the sheet was extruded from a slit-shaped die into a sheet shape, adhered to a casting drum by an electrostatic application method, and solidified by cooling to obtain an unstretched film. The unstretched film was able to be produced stably, and the physical properties of the obtained film are as shown in Table 5. Compared with Example 16, the improvement in transparency was particularly observed due to the addition of p-toluenesulfonic acid.

(Comparative Example 1)
A film was formed in the same manner as in Example 1 except that the copolyester 10 was used. However, the film formation was unstable and a film could not be obtained.
(Comparative Example 2)
A film was formed in the same manner as in Example 1 except that the copolyester 6 was used. The physical properties of the obtained unstretched film are as shown in Table 5. The film exhibited good transparency. Although it had good softness properties immediately after film formation, whitening progressed with time.

(Comparative Example 3)
A film was formed in the same manner as in Example 1 except that the copolyester 14 was used, but gelation occurred and a film could not be obtained.
(Comparative Example 4)
A film was formed in the same manner as in Example 1 except that the copolymer polyester 15 was used. However, the film formation was unstable and a film could not be obtained.

(Comparative Example 5)
A film was formed in the same manner as in Example 1 except that the copolymer polyester 16 was used. The physical properties of the obtained unstretched film are as shown in Table 5. Although the film had good film forming stability and transparency, the flexibility was insufficient.

  The film obtained by this invention can be preferably used for uses, such as an industrial material and a packaging material which require a softness | flexibility and easy moldability.

Claims (16)

As an acid component, a fatty acid monomer, a fatty acid dimer and an aliphatic trimer are included, and the fatty acid dimer and the fatty acid trimer are contained in a ratio of 70 to 90 % by weight and 10 to 30 % by weight, respectively. A copolyester comprising a fatty acid or a derivative thereof and synthesized from a composition containing 1,4-butanediol as a glycol component, wherein the fatty acid (derivative) in the acid component is a repeating unit constituting the copolyester. ) The content of the residue is 5 to 50 mol%, the content of the 1,4-butanediol residue in the glycol component is 42 to 90 mol%, and the melt viscosity of the copolymer polyester is 1000 at 250 ° C. Copolyester characterized by being -3000 poise. The copolyester according to claim 1, wherein a compatibilizing agent is added. The copolyester according to claim 2 , wherein the compatibilizing agent is bisoxazoline. The copolyester according to claim 2 , wherein the compatibilizing agent is an organic acid. The copolymer polyester according to any one of claims 1 to 4 , wherein the fatty acid dimer in the acid component of the fatty acid or a derivative thereof is a dimer acid or a dimer acid derivative. A method for producing a copolyester, characterized in that the copolyester according to any one of claims 1 to 5 is produced by melt-kneading an aromatic polyester and an aliphatic-aromatic copolyester. The constituent components of the aromatic polyester are mainly terephthalic acid residues and ethylene glycol residues, and the constituent components of the aliphatic-aromatic copolymer polyester are mainly terephthalic acid and fatty acid or its derivative residues and 1,4-butanediol residue. The method for producing a copolyester according to claim 6 , which is a group. It is a copolymerized polyester synthesized from a composition containing a fatty acid or a derivative thereof containing, as an acid component, a fatty acid dimer and a trimer in a proportion of 15% by weight or more and less than 95% by weight and 5 to 85% by weight, respectively. A polyester resin comprising an aromatic polyester and a copolymer polyester containing 20 to 80 mol% of a fatty acid (derivative) residue as an acid component in its constituent components and having a melt viscosity of 50 to 450 poise at 250 ° C. Composition. The aromatic polyester is one or more polyesters in which the acid component is an aromatic dicarboxylic acid residue and the glycol component is 1,4 butanediol residue and / or other diol residue, The polyester resin composition according to claim 8 , wherein 30% by weight or more of all glycol components are 1,4 butanediol residues. In all repeating units constituting the copolymer polyester and the aromatic polyester, the content of the fatty acid (derivative) residue in the acid component is 5 to 50 mol%, and the content of the 1,4-butanediol residue in the glycol component There is a 42 to 90 mol%, and the polyester resin composition according to claim 8 or 9 melt viscosity of the resin composition is characterized in that it is a 1000~3000poise at 250 ° C.. Fatty acids or the content of the fatty acid dimer in the acid component of the derivatives thereof, each of the content of trimer, 70 to 90 wt%, of claims 8 to 10, characterized in that 10 to 30 wt% The polyester resin composition in any one. The polyester resin compound according to any one of claims 8 to 11, wherein a compatibilizing agent is added. The polyester resin composition according to claim 12 , wherein the compatibilizer is bisoxazoline. The copolyester according to claim 12 , wherein the compatibilizer is an organic acid. The polyester resin composition according to any one of claims 8 to 14 , wherein the fatty acid dimer in the acid component of the fatty acid or a derivative thereof is a dimer acid or a dimer acid derivative. A polyester film comprising the copolymerized polyester according to any one of claims 1 to 5 , or a polyester film produced from the polyester resin composition according to any one of claims 8 to 15 , wherein the elastic modulus is 25. A polyester film characterized by being 1 to 1000 MPa at a temperature.