WO2001079334A1 - Stretched polyester-amide film and process for producing the same - Google Patents

Abstract

A stretched polyester-amide film made of a polyester-amide copolymer comprising polyamide units and polyester units in the molecular chain. In dynamic viscoelastometry, the stretched film has a main dispersion peak at a temperature higher by at least 10°C than the main dispersion peak temperature for a nonoriented object made of the polyester-amide copolymer. The stretched film has biodegradability and is excellent in mechanical strength and heat resistance. It can be produced by the inflation stretching method.

Description

 Description Stretched polyester amide film and method for producing the same

 The present invention relates to a stretched polyesteramide film, and more particularly, to a stretched polyesteramide film having excellent mechanical strength and heat resistance and having biodegradability (disintegration in soil). The present invention also relates to a method for producing a polyesteramide stretched film having excellent mechanical strength and heat resistance and having biodegradability by using a polyesteramide copolymer by an inflation stretching method. The stretched polyesteramide film of the present invention is suitable as a packaging material for various articles such as food, a wrap film, and the like. Landscape technology

 In recent years, as environmental problems have become more serious, there has been an increasing demand for biodegradable, environmentally friendly packaging materials. Since the reliability of protecting the contents is required for packaging materials for various products such as food, synthetic resin films having excellent mechanical strength and heat resistance are generally used.

 However, general-purpose synthetic resin films, such as polyolefin-based films, polyamide-based films, and polyvinylidene chloride-based films, have been developed with the goal of high performance and long-term stability, and have excellent physical properties such as mechanical strength. On the other hand, once released into the natural world, they remain in their original form without being decomposed. Used packaging materials are collected as garbage and incinerated or landfilled. However, in fact, a large amount of scattered garbage has been shown to have a negative impact on natural ecosystems. There are also problems such as environmental pollution due to incineration, narrowing of landfills and location.

On the other hand, biodegradable polymers are polymers that eventually break down into water and carbon dioxide by the action of microorganisms and do not remain in the environment. This biodegradable polymer also includes polymers that lose their shape under the action of microorganisms in the soil or sea. Using such a biodegradable polymer as a raw material, it has properties that can be substituted for general-purpose synthetic resin films. If environmentally friendly packaging materials can be manufactured, these environmental problems can be reduced.

 However, films used for packaging materials, etc., are required to have mechanical properties, thermal properties, melt processability, economy, etc., but many biodegradable polymers are used as packaging materials. It is difficult to form a film having sufficient physical properties. For example, a film formed using starch has insufficient mechanical strength and heat resistance, and is difficult to melt-process. Cellulose films are unsatisfactory in mechanical strength and are difficult to melt process.

 Films formed using microbial polyesters are unsatisfactory in mechanical strength, and have the problem of high cost. Polyketone prolactone has a low melting point of 60 ° C, so that a film having excellent heat resistance cannot be formed. Films made of aliphatic polyesters such as polybutylene succinate / adipate copolymer are not satisfactory in mechanical strength and heat resistance. Films made of polylactic acid have insufficient mechanical properties, and the optically active L-lactic acid used as a raw material must be produced by a bioprocess called fermentation, which limits the cost reduction. .

 In order to obtain a film with excellent mechanical strength and heat resistance applicable to applications such as packaging materials, it is generally indispensable to arrange a stretching step at the time of film production, but many biodegradable polymers are melted. Due to unsatisfactory workability and stretch orientation, it is difficult to form stretched films with excellent physical properties using simple equipment or existing equipment.

 Conventionally, polyesteramide copolymers have been developed to improve the physical properties of aliphatic polyesters that have biodegradability and at the same time impart biodegradability to polyamides.Applications to biodegradable films have also been proposed. Have been. Specifically, a biodegradable film formed by using a copolymer in which a number of low molecular weight aliphatic polyester ester blocks and low molecular weight aliphatic polyamide amide blocks are alternately bonded as a material (Japanese Unexamined Patent Application Publication No. Japanese Patent Application Laid-open No. Sho 54-119954 /) and agricultural multi-film (Japanese Patent Application Laid-Open No. Sho 56-223234) have been proposed.

However, these prior art documents merely include powder or thin film Only the results of a biodegradability test performed by adding a degrading enzyme to the coalesced are shown, and there is no disclosure of an example in which a film was actually formed using a polyesteramide copolymer. There is no disclosure. Disclosure of the invention

 An object of the present invention is to provide a stretched film which has biodegradability and is excellent in mechanical strength and heat resistance by using a polyesteramide copolymer. Another object of the present invention is to provide a method for economically producing a stretched film having biodegradability and excellent mechanical strength and heat resistance by inflation stretching using a polyesteramide copolymer. Is to provide.

 The present inventors have conducted intensive studies to achieve the above object, and as a result, when a stretched film having a high plane orientation was formed from a polyesteramide copolymer, mechanical properties such as tensile strength, tensile elongation, and tensile modulus were measured. It has been found that a drawn film having remarkably improved mechanical strength and excellent heat resistance can be obtained. It was confirmed that this stretched film exhibited disintegration in soil. The degree of orientation of the stretched film can be quantitatively evaluated based on the main dispersion peak temperature in the dynamic viscoelasticity measurement of the stretched film.

 The present inventors have found that when a stretched film is formed by applying an inflation stretching method to a polyesteramide copolymer, a stretched film with a high degree of plane orientation can be obtained at a stretching temperature near room temperature. Polyamide can be stretched under heating by the inflation stretching method. However, the stability of the bubble is poor, and industrially, the equipment is large and precise control of the stretching conditions is required. On the other hand, for polyester amide copolymers, conventional blown film manufacturing equipment can be used, and by using a stretching temperature near room temperature, bubbles can be stabilized, and thickness fluctuations and stretching magnifications can be reduced. The fluctuation is suppressed, and as a result, a stretched film having excellent physical properties can be formed. In addition, since the polyesteramide copolymer can be stretched at a stretching temperature near room temperature, less energy is required for production.

Before stretching, heat treatment at a relatively low temperature is performed for a short time to form a molten parison. As the crystallization progresses, the bubble becomes more stable, and the variation in thickness and the variation in stretching ratio can be suppressed to a higher degree, whereby the appearance and mechanical strength of the stretched polyester amide film are further improved. Can be obtained. The present invention has been completed based on these findings.

 According to the present invention, a stretched polyesteramide film comprising a polyesteramide copolymer containing a polyamide unit and a polyester unit in a molecular chain, and a main dispersion peak temperature in dynamic viscoelasticity measurement of the stretched film is The present invention provides a stretched polyesteramide film which is higher by 10 ° C. or more than the main dispersion peak temperature of the non-oriented material comprising the polyesteramide copolymer.

 According to the present invention,

 (1) a step of supplying a polyester amide copolymer containing a polyamide unit and a polyester unit in a molecular chain to an extruder equipped with a ring die for inflation and melt-extruding the ring die into a tube,

 (2) immediately cooling the melt-extruded tube in an inert liquid medium at a temperature of 25 ° C or lower to prepare a parison; and

 (3) The parison is stretched in an atmosphere at a temperature of 15 to 40 ° C. in a stretching direction in the machine direction (MD) of 1.1 to 10 times and in a width direction (TD) of 1.1 to 10 times. The process of doubling inflation

And a method for producing a stretched polyesteramide film comprising a series of steps comprising:

 Further, according to the present invention,

 (i) a step of supplying a polyester amide copolymer containing a polyamide unit and a polyester unit in a molecular chain to an extruder equipped with an inflation ring die, and melt-extruding a tube from the ring die.

 (ii) a step of immediately cooling the melt-extruded tube in an inert liquid medium at a temperature of 25 ° C or lower to prepare a parison;

 (ii) heat treating the parison in an inert liquid medium at a temperature of 30 to 60 ° C or in a dry heat atmosphere for 0.5 to 10 seconds; and

(iv) The parison is stretched in the longitudinal direction (MD) in an atmosphere at a temperature of 15 to 40 ° C. Step of inflation at a draw ratio of 1.5 to 10 times and a draw ratio of 1.5 to 10 times in the width direction (TD)

And a method for producing a stretched polyesteramide film comprising a series of steps comprising: BEST MODE FOR CARRYING OUT THE INVENTION

1. Polyester amide copolymer

 The polyesteramide copolymer used in the present invention is a polymer having a polyamide unit and a polyester unit in a molecular chain. The proportion of each unit is preferably from 5 to 8.0 mol%, more preferably from 20 to 70 mol%, particularly preferably from 30 to 60 mol%, of polyamide units. The content of the polyester unit is preferably 20 to 95 mol%, more preferably 30 to 80 mol%, and particularly preferably 40 to 70 mol%. In many cases, good results can be obtained by using a polyesteramide copolymer having 45 to 55 mol% of polyamide units and 45 to 55 mol% of polyester units.

 If the proportion of the polyamide unit in the polyesteramide copolymer is too small, orientation crystallization hardly occurs at the time of inflation stretching, and the inflation stretching itself becomes difficult due to bursting of bubbles and the like. Further, if the proportion of the polyamide unit is too small, only a stretched film having poor mechanical strength can be obtained even if stretching is performed. On the other hand, if the proportion of the polyamide unit is too large, the biodegradability of the polyester amide copolymer is impaired.

 As the polyamide unit, various known polyamides are used. If a polyamide having an excessively high melting point is used, the polyester segment may be thermally decomposed during melt processing. Therefore, polyamide 6 (nylon 6), polyamide 66 (nylon 66), or a copolymer thereof having an appropriate melting point is preferred. Among these, polyamide 6 is most preferable from the viewpoint that when a copolymer with polyester is formed, heat resistance and thermal stability during melt molding are balanced.

As the polyester unit, an aliphatic polyester is preferably used from the viewpoint of biodegradability. However, as long as it shows biodegradability, An alicyclic polyester such as adipate, an aromatic polyester, or the like may be used alone or in combination with an aliphatic polyester. As the aliphatic polyester, polybutylene adipate, polyethylene adipate, polylactone and the like are preferable, and polybutylene adipate is particularly preferable.

 The method for synthesizing the polyesteramide copolymer is not particularly limited. For example, (1) a polyamide-amide copolymer is obtained by alternately introducing a large number of polyamides into an aliphatic polyester by an amide-ester exchange reaction. (2) Polyamide-forming compounds (for example, ε-force prolactam), dicarboxylic acids and polyester diols (for example, polylactone diol) (Japanese Patent Application Laid-Open No. 7-173716), (3) a polyamide-forming compound (for example, ε-force prolactam, etc.) and a polyester-forming compound (a dibasic acid and a diol; lactone). And the like).

 In the above method (1), examples of the polyester include polycaprolactone, polyethylene adipate, and polybutylene adipate. Examples of the polyamide include nylon 6, nylon, 66, nylon 69, and nylon 61. , Nylon 61, nylon 11, nylon 12, and the like.

 Examples of the polyamide-forming compound include ω-aminobutyric acid, ω-aminovaleric acid, ω-aminocaproic acid, ω-aminoenanthic acid, ω-aminoforce prillic acid, ω-aminoberalgonic acid, ω-aminoundecanoic acid , Ω-aminododecanoic acid, etc., having 4 to 12 carbon atoms; amino acids having 4 to 12 carbon atoms; And the like.

Further, as the polyamide-forming compound, a nylon salt composed of dicarboxylic acid and diamine can be exemplified. Examples of the dicarboxylic acids include aliphatic dicarboxylic acids having 4 to 12 carbon atoms, such as succinic acid, daltaric acid, adipic acid, pimelic acid, suberic acid, sebacic acid, azelaic acid, and dodecandionic acid; hydrogenated terephthalic acid, hydrogenated Alicyclic dicarboxylic acids such as isophthalic acid; aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid and phthalic acid; Examples of diamines include tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, and heptamethine. Aliphatic diamines having 4 to 12 carbon atoms, such as diamine, octamethylene diamine, nonamethylene diamine, decamethylendiamine, pendecamethylene diamine, dodecamethylene diamine; cyclohexanediamine, methylcyclohexane Alicyclic diamines such as xanthamine; aromatic diamines such as xylene diamine; and the like.

 In the method of the above (2), the dicarboxylic acid includes aliphatic dicarboxylic acids such as succinic acid, daltaric acid, adipic acid, pimelic acid, suberic acid, sebacic acid, azelaic acid, and dodecanedic acid; hydrogenated terephthalic acid, Alicyclic dicarboxylic acids such as hydrogenated isophthalic acid; aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid and phthalic acid;

 In the above method (2), examples of the polyester diol include a polylactone diol having an average molecular weight of 500 to 400. Polylactonediol is synthesized from a lactone having 3 to 12 carbon atoms using a glycol compound as a reaction initiator. Examples of the lactone include / 3-propiolactone,] 3-butyl lactone, d-valerolactone, ε-force prolactone, enanthractone, capryloractone, laurolactone and the like.

 In the above method (3), examples of the dibasic acid include adipic acid, pimelic acid, suberic acid, sebacic acid, azelaic acid, dodecanedioic acid and the like. Diols include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 2,3-butanediol, 2,5 —Hexanediol, 2-methyl-1,4-butanediol, 3-methyl-2,4-pentanediol, 2-methyl-1,2,4-pentanediol, 2-ethyl-2-methyl-1,3-propanediol , 2,3-dimethyl-2,3-butanediol and the like.

In the above method (3), examples of the lactone include J3-propiolactone; 6-butyrolactone, δ-valerolactone, ε-force prolactone, enantholactone, caprylolactone, laurolactone and the like. In addition, glycolic acid, glycolide, lactic acid, / 3-hydroxybutyric acid, jS-hydroxyvaleric acid and the like can also be mentioned as polyester-forming compounds. Polyester amide copolymers include nylon 6 / polybutylene adipate copolymer, nylon 66 / polybutylene adipate copolymer, and nylon 6 / polyethylene adipate from the viewpoint of the balance between mechanical strength and biodegradability. Polymers, nylon 66 / polyethylene adipate copolymer, nylon 6 / polyprolactone copolymer, nylon 66Z polyprolactone copolymer and the like are preferred. Among these, nylon 6Z polybutylene adipate copolymer is particularly preferred from the viewpoints of if heat property and melt processability.

 The lower limit of the melting point (Tm) of the polyesteramide copolymer is preferably 90 ° (:, more preferably 100 ° C, and the upper limit is preferably 210 ° C, more preferably 200 ° C. The melting point (Tm) of the polyesteramide copolymer is detected when measured with a differential scanning calorimeter at a heating rate of 10 ° C / min. Crystal melting peak temperature When multiple melting peaks appear, the peak temperature with the largest calorific value is taken as the melting point If this melting point is too low, the heat resistance of the polyesteramide stretched film is not enough and it is too high When the melting temperature increases, the polyester segment is easily decomposed.

 The relative viscosity of the polyesteramide copolymer is preferably at least 1.0, more preferably at least 1.3, and often from 1.0 to 3.0. The relative viscosity of the polyesteramide copolymer was determined using hexafluoroisopropanol (HF IP) as the solvent at a concentration of 0.4 g / dl (dissolved at a rate of 0.4 g of polymer per 100 ml of solvent). This is the value measured using a Ubbelohde viscometer in a 10 ° C atmosphere of the polymer solution. If the relative viscosity is too low, the degree of polymerization (or the molecular weight) is too low, and it is difficult to obtain a stretched film having excellent mechanical strength. If the relative viscosity is too high, the thickness and the draw ratio tend to fluctuate. It becomes difficult to obtain a stretched film with uniform physical properties.

 The polyesteramide copolymer preferably has a half-crystallization time of 1 to 3 minutes at 20 ° C. in order to obtain a highly oriented stretched film by an inflation stretching method.

 2. Manufacturing method of polyesteramide stretched film

The stretched polyesteramide film of the present invention has a high degree of plane orientation. If the main dispersion peak temperature in the dynamic viscoelasticity measurement of the stretched film is higher than the main dispersion peak temperature of the non-oriented material composed of the polyester amide copolymer by 10 ° C or more, the production method is as follows. There is no particular limitation.

 As a method for producing a stretched film, there are a flat die method, a sakyura die method, and the like. The flat die method includes a uniaxial stretching method, a sequential biaxial stretching method, and a simultaneous biaxial stretching method. As a biaxial stretching method using the sakura die method, there is an inflation stretching method. In order to produce a polyesteramide stretched film having a high degree of plane orientation and excellent mechanical strength and heat resistance with good productivity and economical efficiency, it is preferable to employ the inflation stretching method.

 In general, in the inflation method, a resin melted by an extruder is formed into a cylindrical shape by a ring die, and a continuous tubular parison is discharged, and an inert gas (such as air or nitrogen gas) is discharged into the parison. This method involves press-fitting, expanding using the plasticity of the resin, and forming the film into a thinner film.

 In the direct inflation method, air is blown directly from the die side into the molten parison extruded from the ring die to expand it, forming a bubble, followed by blowing cooling air or water in a ring shape and hardening at an arbitrary expansion ratio . In the direct inflation method, since the molten parison is expanded, stretching orientation is not easily generated, and it is not possible to obtain a polyesteramide stretched film having excellent mechanical strength and heat resistance.

In contrast, in the inflation stretching method, generally, a tubular parison extruded from a ring die is quenched with water or the like, and then usually re-heated to a temperature equal to or higher than the glass transition temperature of the resin and lower than the melting point. A bubble is formed between the pinch rollers by sealing an inert gas so as to expand the parison. In this method, since the parison is expanded at a temperature lower than the melting point, orientation is generated and a stretched film is obtained. The parison is quenched to suppress crystallization and to orient the molecular chains during stretching. When reheating, select temperature conditions so that crystallization of the quenched parison does not progress. In other words, in the ordinary inflation stretching method, the parison is stretched while suppressing crystallization as much as possible, an inert gas is blown into the parison to form a bubble, and the parison is stretched by the pressure in the bubble, and the forcing at that time is performed. Orientation of molecular chains due to deformation Crystallization is occurring. During stretching, it is usual to blow bubbles into the parison while blowing the inert gas into the parison while maintaining the stretching temperature in the range of the glass transition temperature of the resin to the glass transition temperature + 50 ° C.

 The first production method of the present invention comprises: (1) a step of supplying a polyesteramide copolymer to an extruder equipped with a ring die for inflation and melt-extruding a tube from the ring die; ) A step of immediately cooling the melt-extruded tube in an inert liquid medium at a temperature of 25 ° C or less to prepare a parison; and (3) cooling the parison in an atmosphere at a temperature of 15 to 40: This is a method for producing a stretched polyesteramide film, comprising a series of steps comprising inflation at a draw ratio of 1.5 to 10 times in the machine direction (MD) and 1.5 to 10 times in the width direction (TD). .

 In the step (2), in order to suppress crystallization, the cooling temperature is preferably set to 20 ° C or lower. When water is used as a cooling medium, the temperature is preferably 0 to 15 ° C, and particularly preferably. Preferably, the temperature is adjusted to about 2 to 10 ° C. In the step (3), it is preferable to adjust the stretching temperature within a temperature range of about 20 to 30 ° C. since stretching at room temperature can be performed without special heating.

 In the case of inflation stretching of polyamide, the quenched parison is reheated to a temperature above the glass transition temperature of the resin and below the melting point, and the parison is in the range from the glass transition temperature of the resin to the glass transition temperature + 5 Ot: While maintaining the stretching temperature of, inert gas is blown into the parison to generate bubbles. The stretching temperature is about 40 to 140 ° C. in the case of nylon. By stretching the polyamide while heating, a stretched polyamide film having excellent mechanical strength and surface smoothness can be obtained. However, inflation stretching of polyamide has a poor bubble stability, requires a large-scale industrial equipment, and requires precise control of the stretching conditions. Moreover, the stretched polyamide film has no biodegradability.

 On the other hand, in the inflation stretching using the polyesteramide copolymer, although the polyesteramide copolymer is a polymer having a relatively high melting point, the stretching temperature at around room temperature (typically, 2). It was found that inflation stretching at 5 ° C) was possible.

The polyesteramide copolymer is used to prevent the biodegradability from being impaired. It is designed to shorten the chain length of polyamide units (polyamide segments). For this reason, the polyesteramide copolymer has characteristics such that crystallinity is low, oriented crystallization is difficult to occur, and the crystallization speed is low. Therefore, if the molten parison is quenched with water or the like and then stretched at a temperature around room temperature, it is expected that it is difficult to make the orientation of not only the crystal part but also the amorphous part sufficiently high. Was. Contrary to this expectation, it is surprising that, even at low stretching temperatures, a fully plane oriented polyester amide stretched film can be obtained. In addition, the polyesteramide copolymer has relatively good bubble stability, and has a large allowable range of stretching conditions. Therefore, according to the inflation stretching method of the present invention, it is possible to obtain a stretched film which is simple in equipment, requires little energy for production, and has excellent mechanical strength and heat resistance.

 The stretching ratio is preferably 2 to 8 times, more preferably 3 to 7 times in the machine direction (MD), and preferably 2 to 8 times, more preferably 3 to 7 times in the width direction (TD). If the stretching ratio is too small, the degree of orientation is reduced, and the mechanical strength and heat resistance are reduced. If it is too large, bubbles may be broken.

 After the stretching step, if necessary, at a temperature of usually 40 to 200 ° C., preferably 50 to 180 ° C., for 1 second to 3 hours, preferably 3 seconds to 30 minutes, constant length It can be heat set under tension or under tension. If the polyesteramide stretched film requires a certain degree of heat shrinkage or is used for applications where heat shrinkage is not inconvenient, the heat treatment step is preferably omitted.

The second production method of the present invention comprises: (i) a step of supplying a polyesteramide copolymer to an extruder equipped with a ring die for inflation, and melt-extruding the polyester into a tube from the ring die; (ii) A step of immediately cooling the melt-extruded tube in an inert liquid medium at a temperature of 25 ° C or lower to prepare a parison; (iii) cooling the parison in an inert liquid medium at a temperature of 30 to 60 ° C. Or (iv) heat-treating the parison in a dry heat atmosphere for 0.5 to 10 seconds, and (iv) stretching the parison in a longitudinal direction (MD) of 1.5 to 40 ° C. in an atmosphere at a temperature of 15 to 40 ° C. This is a method for producing a stretched polyesteramide film including a series of steps of inflation at a stretch ratio of 10 times and a draw ratio of 1.5 to 10 times in the width direction (TD). The second manufacturing method of the present invention is the same as the first manufacturing method, except that a heat treatment step is arranged as the (iii) step. That is, the cooling temperature in step (ii) is preferably 20 ° C. or lower, and when water is used as the cooling medium, preferably 0 to 15 ° C., and particularly preferably 2 to 10 ° C. It is about. In the step (iv), it is preferable to adjust the stretching temperature within a temperature range of about 20 to 30 ° C. since stretching at room temperature is possible. The stretching ratio is preferably 2 to 8 times, more preferably 3 to 7 times in the machine direction (MD), and preferably 2 to 8 times, more preferably 3 to 7 times in the width direction (TD). After stretching, it can be heat-set if necessary.

 In the conventional inflation stretching method, it has been customary to extend the parison while minimizing crystallization. However, when the parison is crystallized by performing a heat treatment at a relatively low temperature for a short time before stretching, the stability of the bubble increases, and the thickness fluctuation and the fluctuation of the stretching ratio can be suppressed more effectively. There was found. Further, by adjusting the heat treatment conditions, it is possible to obtain a stretched polyesteramide film having better mechanical strength such as tensile modulus and heat resistance. As described above, the polyester amide copolymer is characterized by low crystallinity due to the short chain length of the polyamide unit, difficult to cause oriented crystallization, and low crystallization speed. It is presumed that by stretching the parison, which has been crystallized to some extent, by performing heat treatment before stretching, the stretching orientation during inflation can be more effectively increased. The heat treatment of the parison is performed in an inert liquid medium such as water or in a dry heat atmosphere using a heater, but in order to obtain a heat treatment effect in a short time, it is preferable to perform the heat treatment in an inert liquid medium. The heat treatment temperature is preferably about 35 to 55 ° C. from the viewpoint of promoting crystallization of the parison. The heat treatment time depends on the heat treatment temperature, but is preferably as short as about 1 to 5 seconds for continuous inflation stretching.

 Similarly, in the flat die method, a method is employed in which a polyesteramide copolymer is melt-extruded into a sheet, cooled to a temperature of 25 ° C or less, and stretched in an atmosphere of 15 to 40 ° C. Is done. Preferably, a method of performing heat treatment at 30 to 60 at 0.5 to 10 seconds before stretching is employed.

3. Polyesteramide stretched film In the stretched polyesteramide film of the present invention, it is essential that the main dispersion peak temperature measured by the dynamic viscosity measurement described later is higher than that of the oriented product composed of the polyesteramide copolymer by 10 ° C. or more. Preferably, it is higher than 20 ° C.

 The fact that the main dispersion peak temperature of the polyesteramide stretched film is higher than the main dispersion peak temperature of the non-oriented material by 10 ° C or more means that in the polyesteramide stretched film, the amorphous molecular chains are highly tightly restrained. It indicates that. In other words, as a result of the effective stretching, the stretched polyesteramide stretched film of the present invention has a high degree of not only the molecular chains in the crystalline part but also the molecular chains in the amorphous part. It shows that it is oriented.

 The upper limit of the temperature difference between the main dispersion peak temperatures is about 40 ° C, and often about 35 ° C. The main dispersion peak temperature of the polyesteramide stretched film may be slightly different between MD and TD, but in such a case, the main dispersion peak temperature in at least one direction is 10 ° higher than that of the non-oriented material. It is necessary that the temperature of the main dispersion peak in both directions be higher than that of the non-oriented material by 10 ° C or more.

 The stretched polyesteramide film of the present invention has the following formula (I):

 5≤ (AXB) / 100≤30 (I)

Is preferably satisfied.

 The crystallinity A and the long period B measured by small-angle X-ray scattering are given by the formula (I I)

 10≤ (AXB) / 100≤25 (II)

Is more preferably satisfied.

The product of the crystallinity A and the long period B measured by small-angle X-ray scattering corresponds to the thickness of the crystals formed by crystallization of the polyamide segment. The stretched polyesteramide film having an (AXB) / 100 value of less than 5 has a low crystallinity due to the short chain length of the polyamide segment, and the polyamide unit introduced into the molecular chain improves mechanical strength and heat resistance. It may not sufficiently contribute to sex. On the other hand, a stretched film having an (AXB) / 100 value exceeding 30 has a polyamide segment chain length. Too long, biodegradability may be impaired. According to the production method of the present invention,

A stretched film having an (AXB) / 100 value in the range of 10 to 25 can be easily obtained. In particular, according to the second production method of the present invention, a stretched film having (AXB) ./ 00 value of 20 or more can be easily obtained.

 The stretched polyesteramide film of the present invention preferably has a degree of orientation of 75% or more as measured when X-rays are incident parallel to the film surface by wide-angle X-ray diffraction. The degree of orientation is more preferably 80% or more. The degree of orientation when X-rays are incident parallel to the film surface is a measure of the degree of plane orientation of the film.If the degree of orientation is too small, mechanical strength such as tensile breaking strength is impaired. There is fear. Most preferably, the degree of orientation when X-rays are incident from the end of the stretched film (the direction parallel to the film surface and also parallel to the MD) and the edge (the direction parallel to the film surface and also parallel to the TD). However, both are more than 80%. Such a stretched film has excellent uniformity of plane orientation and low anisotropy of mechanical strength.

 The stretched polyesteramide film of the present invention has good heat resistance, and retains its shape after being heated in a hot-air oven at 100 ° C. for 30 minutes. Further, the stretched polyesteramide film of the present invention has good biodegradability, and when it is taken out after being buried in soil for a certain period of time, it loses its shape or its tensile breaking strength is lower than the value before it is buried. It has dropped to less than 50%.

 The stretched polyesteramide film of the present invention preferably has a stretch ratio in the machine direction (MD) of 1.5 to 10 times, more preferably 2 to 8 times, and a stretch ratio in the width direction (TD) of preferably 1. It is 5 to 10 times, more preferably 2 to 8 times.

 The tensile rupture strength of the stretched polyesteramide film of the present invention, together with MD and TD, is preferably 5 OMPa or more, more preferably 6 OMPa or more, and still more preferably 7 OMPa or more. The tensile breaking strength of the stretched film in both MD and TD is in the range of 50 to 180 MPa in most cases, and more often in the range of 60 to 70 MPa.

The tensile elongation at break of the stretched polyesteramide film of the present invention is preferably 80% or more, more preferably 90% or more, and still more preferably 100% or more, for both MD and TD. The tensile elongation at break of the stretched film is large for both MD and TD. In most cases it is in the range of 80-200%, more often 90-190%. The tensile modulus of the stretched polyesteramide film of the present invention is preferably 12 OMPa or more, more preferably 13 OMPa or more, and even more preferably 15 OMPa or more, for both MD and TD. The tensile modulus of this stretched film, in both MD and TD, is often in the range of 120 to 30 OMPa, more often 130 to 28 OMPa.

 The stretched polyesteramide film of the present invention has a thickness of usually 1 to 500 111, preferably 3 to 300 zm, more preferably 5 to 200 m. The stretched polyesteramide film of the present invention can be made into a slippery film or imparted with printability by adding an organic filler or an inorganic filler to the polyesteramide copolymer. Moreover, the polyesteramide stretched film of the present invention can contain various additives such as an antioxidant, an ultraviolet absorber, a lubricant, a plasticizer, and a coloring agent, if necessary. The stretched polyesteramide film of the present invention may contain other thermoplastic resins and thermosetting resins as long as the biodegradability, mechanical strength, heat resistance and the like are not impaired. The stretched polyesteramide film of the present invention may be laminated with various film sheets to form a multilayer film in order to improve or impart heat sealing properties, gas barrier properties, heat resistance, mechanical strength, and the like, if desired. be able to. Example

 Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples. Methods for measuring physical properties are as follows.

 (1) Main dispersion peak temperature

 After leaving the sample in an atmosphere of 23 ° C and 50% RH (relative humidity) for 24 hours, the distance between the chucks was 20 mm and the sample width was 3 mm using a dynamic viscoelasticity measuring device RSA manufactured by Leometrics. mm, at a measurement frequency of 10 Hz, the temperature was increased from −100 ° C. to 120 ° C. at a rate of 2 ° C./min, and the temperature dispersion curve of the loss tangent t an δ was measured. The temperature at which this temperature dispersion curve shows a maximum was defined as the main dispersion peak temperature (° C).

(2) Crystallinity Using a differential scanning calorimeter DSC 7 manufactured by PerkinElmer Co., Ltd., set about 1 Omg of the sample in the measuring cell, and in a nitrogen gas atmosphere, at a temperature rise rate of 30 ° C to 10 ° C / min and 200 ° C And the DSC curve was measured. From the DSC curve, the melting rupture ΔΗ (J / g) of the crystal was determined, and the crystallinity was calculated from the following equation.

 Crystallinity (% by weight) = (ΔΗΖΔΗ.) X 100

 Where ΔΗ. = 190.88 (J / g)

 (3) Long period measured by small-angle X-ray scattering

 The direction in which the scattering image of the sample film appeared most clearly was selected and X-rays were incident, and imaging plates were photographed. A rotorflex 200 RB manufactured by Rigaku Corporation was used as an X-ray generator, and CuKa rays passed through a Ni filter at 40 kV-200 mA were used as the X-ray source. BAS-SR12 manufactured by Fuji Photo Film Co., Ltd. was used as an imaging plate. The sample was exposed at a distance of 50 Omm between the imaging plate and an exposure time of 24 hours, and a scattered image was read using R-AXIS SDS3 manufactured by Rigaku Corporation to create a scattering angle intensity distribution curve. The long period (unit: angstrom; A) was determined from the peak angle of the scattering angle intensity distribution curve.

 (4) Orientation measured by wide-angle X-fountain scattering

The films were stretched in the same stretching direction so as to have a width of lmm, a length of 20 mm, and a thickness of 3 mm, and were fixed with a cyanoacrylate adhesive to prepare a sample. X-rays were incident (Edge direction and End direction) parallel to the film surface of this sample, and an imaging plate was photographed. The X-ray source was a rotor flex; R U-200B manufactured by Rigaku Denki Co., Ltd., and the X-ray source was a Cu uα ray passed through a Ni filter at 30 kV—10 OmA. Using BAS-SR127 manufactured by Fuji Photo Film Co., Ltd. as an imaging plate, the sample was exposed at a distance of 6 Omm between the imaging plate and an exposure time of 20 minutes. Rigaku Denki Co .; — Using AX IS DS 3, diffraction images were read to create an azimuthal (triangle) intensity distribution curve of diffraction from the (200) plane of polyamide 6 α-type crystal. From the zero-angle intensity distribution curve, two points on the equatorial line were obtained according to the method of measuring the degree of orientation described on page 81 of the revised X-ray diffraction guide published by Rigaku Denki Co., Ltd. (published on June 30, 1985). From the sum of the half-widths Wi (degrees) for (] triangles of 90 ° and 270 °) ∑Wi (degrees), the degree of orientation (%) I asked.

 Orientation = ((360-∑W i) no 360) x 100

 (5) Tensile properties

 The sample was left in a temperature and humidity controlled room at a temperature of 23 ° C and a humidity of 50% RH for 24 hours. Then, the sample length (distance between chucks) was 50 mm in the same room using Tensilon UTM-3 manufactured by Toyo Pallwin. A tensile test was performed under the conditions of a sample width of 10 mm and a tensile speed of 500 mm / min, and the tensile strength at break (MPa), tensile elongation at break (%), and tensile modulus (MPa) were measured.

 (6) Heat resistance

 Fix the film in a metal frame with inner dimensions of 10 Omm X 10 Omm, heat it in a hot air oven controlled at a temperature of 100 ° C for 30 minutes, take it out, and keep the film shape as good heat resistance .

 (7) Biodegradability (microbial degradability)

 The sample is buried in the soil for 6 months and then removed.If the sample loses its shape or its tensile strength at break is reduced to 50% or less of the value before filling, the microbial degradability is defined as good. . If the sample is not decomposed, it is evaluated as defective.

 (8) Half crystallization time

 The half-crystallization time was measured by a depolarization intensity method using an MK-801 type crystallization rate measuring device manufactured by Kotaki Seisakusho. Melting conditions were heating at 140 ° C for 5 minutes, and crystallization conditions were as follows: the temperature was set to 20 ° C, and the time-permeation curve was measured.The time when the transmitted light reached 1/2 of the equilibrium value was determined as the half-crystallization time. Defined.

 [Example 1]

Polyester amide copolymer [: Bayer BAK 1095, copolymer composition = nylon 6Z polybutylene adipate = 50/50 (mol%), melting point (Tm) = 125, relative viscosity = 1.47, half-crystallization time = 2.2 minutes) to a 45 mm Φ single-screw extruder, melt at the extruder tip temperature of 145 ° C, cut a circular slit with an inner diameter of 30.5 mm and an outer diameter of 32 mm adjusted to a temperature of 140 ° C. The mixture was extruded into a tube from a ring die and immediately cooled in a water bath adjusted to a temperature of 5 ° C. to obtain a parison having a diameter of 16 mm. The obtained parison is immediately placed in an atmosphere at a temperature of 25 ° C, A stretched film was prepared by inflation so that the stretching ratio in the direction (MD) was 3.5 times and the stretching ratio in the width direction (TD) was 5.2 times. Table 1 shows the inflation stretching conditions, Table 2 shows the structural parameters of the stretched film, and Table 3 shows the physical properties of the stretched film.

 On the other hand, the obtained stretched films were stacked and heated and pressed at 140 at 5 minutes to form a press sheet having a thickness of 250 m. This press sheet is a non-oriented sample of the polyester amide copolymer. The main dispersion peak temperature of this unoriented sample was measured and found to be 11 it.

 [Example 2]

 The same polyesteramide copolymer as used in Example 1 was supplied to a 45 ηιππφ single-screw extruder, melted at an extruder tip temperature of 144 ° C, and adjusted to a temperature of 140 ° C. It is extruded into a tube from a ring die having a circular slit with an inner diameter of 30.5 mm and an outer diameter of 32 mm, and is immediately cooled in a water bath adjusted to a temperature of 5 ° C to form a parison with a diameter of 16 mm. Obtained. The parison was then heat treated by passing it through a water bath adjusted to a temperature of 40 for 2 seconds. After the heat treatment, the parison is infused in an atmosphere at a temperature of 25 ° C so that the stretching ratio in the machine direction (MD) is 3.5 times and the stretching ratio in the width direction (TD) is 5.2 times, and a stretched film is prepared. did. Table 1 shows the inflation stretching conditions, Table 2 shows the structural parameters of the stretched film, and Table 3 shows the physical properties of the stretched film.

 On the other hand, the obtained stretched films were stacked and heated and pressed at 140 ° C. for 5 minutes to prepare a pressed sheet having a thickness of 250 m. This press sheet is a non-oriented sample of the polyester amide copolymer. The main dispersion peak temperature of this non-oriented sample was measured to be 11 ° C.

 [Example 3]

 A stretched film was prepared in the same manner as in Example 2, except that the temperature of the water bath for performing the parison heat treatment was changed from 40 to 50 ° C. Table 1 shows the inflation stretching conditions, Table 2 shows the structural parameters of the stretched film, and Table 3 shows the physical properties of the stretched film.

On the other hand, the obtained stretched films were stacked and heated and pressed at 140 ° C for 5 minutes to obtain a thickness. A 250 m press sheet was created. This press sheet is a non-oriented sample of the polyester amide copolymer. The main dispersion peak temperature of this non-oriented sample was measured to be 11 ° C.

 [Comparative Example 1]

 A nylon 6/66 copolymer (Amilan C M604 IX, manufactured by Toray Industries, Inc.) is supplied as a polyamide homopolymer to a 5 5πιπιφ single screw extruder, melted at an extruder tip temperature of 240 ° C, and adjusted to 240 ° C It was extruded into a tube from a ring die having a circular slit having an inner diameter of 24 mm and an outer diameter of 27 mm, and immediately cooled in a water bath adjusted to a temperature of 15 ° C. to obtain a parison having a diameter of 18 mm. The parison was then heat treated by passing it through a water bath adjusted to a temperature of 75 ° C. for 3 seconds. After the heat treatment, the parison is inflated to a stretch ratio of 2.5 times in the machine direction (MD) and 3.1 times in the cross direction (TD) while supplementarily heating the parison with hot air at a temperature of 70 ° C. Created. Table 1 shows the inflation stretching conditions, Table 2 shows the structural parameters of the stretched film, and Table 3 shows the physical properties of the stretched film.

 [Comparative Example 2] '

 A polybutylene succinate-adipate copolymer (Pionole # 3001 manufactured by Showa Polymer Co., Ltd.) as an aliphatic polyester homopolymer was heated and pressed at a temperature of 140 ° C. to form a sheet. The obtained sheet was simultaneously biaxially stretched at a temperature of 80 ° C. and a stretch ratio of 3 × 3 to prepare a stretched film having a thickness of 20 m. When the heat resistance of this film was evaluated, it was broken. Table 3 shows the results.

 [Comparative Example 3]

Comparative Example 3 was a polyvinylidene chloride stretched film (manufactured by Kureha Chemical Co., Ltd., trade name: Nuclelap, thickness: 10 m) obtained by the inflation stretching method. Table 3 shows the results. table 1

 Structural parameters of stretched film

 Main dispersion peak temperature

 Orientation degree Crystallinity Long period

 (%) Peak temperature Unoriented and (A) (B) AXB

 (° C) difference (° C) 100

Edge / End MD / TD MD / TD wt. ¾ A Example 1 84. 9/82. 1 14.6 / 14. 8 25. 6/25. 8 24. 8 76. 4 18.9 Example 2 85 0 / 86.6 14.9 / 14.8 25.9 / 25.8 27.4 73.9 20.2.Example 3 85.2 / 86.7 15.9 / 16.1 26.9 / 17.1 27.1 74.0 20.1 Comparative example 1 83.0 / 87.1 Not measured Not measured 20.7 68.7 14.2 Table 3

産業上の利用可能性

Industrial applicability

 According to the present invention, a stretched polyesteramide film having biodegradability and excellent mechanical strength and heat resistance is provided. Further, according to the present invention, there is provided a method for economically producing a stretched polyesteramide film having biodegradability and excellent mechanical strength and heat resistance by infusion stretching. The stretched polyesteramide film of the present invention is suitable as a packaging material for various articles such as food, a wrap film, and the like.

Claims

The scope of the claims 1. A stretched polyester amide film comprising a polyester amide copolymer containing a polyamide unit and a polyester unit in a molecular chain, and wherein the main dispersion peak temperature in the dynamic viscoelasticity measurement of the stretched film is the polyester A stretched polyesteramide film that is at least 10 ° C higher than the main dispersion peak temperature of the non-oriented material made of amide copolymer. 2. The crystallinity A (unit:% by weight) of the stretched film and the long period B (unit: A) measured by small-angle X-ray scattering are represented by the formula (I).  5≤ (AXB) / 100≤30 (I) 2. The stretched polyesteramide film according to claim 1, wherein the following relationship is satisfied. 3. The stretched polyester amide film according to claim 1, wherein the degree of orientation measured when X-rays are incident parallel to the film surface by wide-angle X-ray diffraction is 75% or more. 4. The stretched polyesteramide film according to claim 1, wherein the polyesteramide copolymer is a polyesteramide copolymer containing 5 to 80 mol% of a polyamide unit and 20 to 95 mol% of a polyester unit in a molecular chain. 5. The stretched polyesteramide film according to claim 1, wherein the polyesteramide copolymer has a melting point of 90 to 210 ° C. 6. The stretched polyesteramide film according to claim 1, wherein the polyesteramide copolymer has a relative viscosity of 1.0 to 3.0. 7. The stretched polyesteramide film according to claim 1, wherein the polyesteramide copolymer has a half-crystallization time at 20 ° C. of 1 to 3 minutes. 8. Polyester amide copolymer is nylon 6 / polybutylene adipate copolymer, nylon 66 / polybutylene adipate copolymer, nylon 6 / polyethylene adipate copolymer, nylon 66 / polyethylene adipate copolymer, nylon 6 2. The stretched polyesteramide film according to claim 1, wherein the stretched polyesteramide film is a copolymer selected from the group consisting of a nopoly force prolactone copolymer and a nylon 66Z polyforce prolactone copolymer. 9. The stretched polyester amide film according to claim 1, which is produced by an inflation stretching method. 10. The stretched polyesteramide film according to claim 1, wherein the stretch ratio in the machine direction (MD) is 1.5 to 10 times, and the stretch ratio in the width direction (TD) is 1.5 to 10 times. 1 1. The stretched polyesteramide film according to claim 1, wherein the tensile strength at break is at least 50 MPa for both MD and TD. 12. The stretched polyesteramide film according to claim 1, having a tensile elongation at break of 80% or more for both MD and TD. 13. The stretched polyesteramide film according to claim 1, which has a tensile modulus of 12 OMPa or more for both MD and TD. 14. The stretched polyesteramide film according to claim 1, which is biodegradable. 15. The stretched polyesteramide film according to claim 1, which retains its shape after heating in a hot-air oven at 100 ° C for 30 minutes. 16. (1) A step of supplying a polyesteramide copolymer containing a polyamide unit and a polyester unit in a molecular chain to an extruder equipped with an inflation ring die, and melt-extruding a tube from the ring die.  (2) immediately cooling the melt-extruded tube in an inert liquid medium at a temperature of 25 ° C or lower to prepare a parison; and  (3) The parison is stretched in an atmosphere at a temperature of 15 to 40 ° C. in a stretching direction in the machine direction (MD) of 1.1 to 10 times and in a width direction (TD) of 1.1 to 10 times. The process of doubling inflation A method for producing a stretched polyesteramide film comprising a series of steps comprising: 17. The process according to claim 16, wherein the polyesteramide copolymer is a polyesteramide copolymer containing 5 to 80 mol% of a polyamide unit and 20 to 95 mol% of a polyester unit in a molecular chain. Method. 18. (i) A polyesteramide copolymer containing a polyamide unit and a polyester unit in a molecular chain is supplied to an extruder equipped with an inflation ring die, and is melt-extruded into a tube from the ring die. Process,  (ii) a step of immediately cooling the melt-extruded tube in an inert liquid medium at a temperature of 25 ° C or lower to prepare a parison;  (ii) heat treating the parison in an inert liquid medium at a temperature of 30 to 60 ° C or in a dry heat atmosphere for 0.5 to 10 seconds; and  (iv) The parison is stretched in an atmosphere at a temperature of 15 to 40 ° C. in a stretching direction in the machine direction (MD) of 1.5 to 10 times and in a width direction (TD) of 1.5 to 10 times. The process of doubling inflation A method for producing a stretched polyesteramide film comprising a series of steps comprising: 19. The process according to claim 18, wherein the polyesteramide copolymer is a polyesteramide copolymer containing 5 to 80 mol% of a polyamide unit and 20 to 95 mol% of a polyester unit in a molecular chain. Method.