JP3518954B2 - Polyethylene oxalate, molded product thereof, and production method thereof - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to polyethylene oxalate [poly (eth) which is a biodegradable polymer material.
More specifically, a polyethylene oxalate having a high molecular weight and being excellent in melt processability, heat resistance, crystal characteristics, mechanical characteristics, and the like, various molded products formed from the polyethylene oxalate, and The present invention relates to a method for producing polyethylene oxalate. Since the polyethylene oxalate of the present invention has a disintegrating property in soil, the load on the environment is small. Further, the polyethylene oxalate of the present invention uses oxalic acid as one of its raw materials. Oxalic acid can be produced by electrolysis of carbon dioxide, etc., and thus is a kind of polymer using carbon dioxide in the atmosphere. be able to. The polyethylene oxalate in the present invention is a cyclic ester of ethylene oxalate.
e oxalate) is a polymer mainly composed of a repeating unit having a ring-opened structure, and includes homopolymers and copolymers.

[0002]

2. Description of the Related Art Polymer materials typified by plastics have been developed and produced for high performance and long-term stability. Therefore, most of the polymer materials are not decomposed in the natural environment, and waste treatment of plastic products and environmental pollution have become major problems on a global scale.
Therefore, in recent years, development of a biodegradable polymer material having a low environmental load has been strongly desired. Generally, in the process of microbial degradation of biodegradable polymer materials, first, a degrading enzyme secreted outside the microbial cells of the microorganism is adsorbed on the surface of the material to form chemical bonds such as ester bonds, glycoside bonds and peptide bonds of the polymer chains. Cleave by hydrolysis reaction. When the molecular weight is reduced by breaking the chemical bond, the polymer material collapses. The low molecular weight compound is further enzymatically decomposed into a low molecular weight decomposed product such as a monomer or a dimer in monomer units. Whether or not the polymer material is biodegradable can be determined, for example, by burying a molded article made of the polymer material in soil and observing whether or not it collapses after a certain period of time. .

Examples of the biodegradable polymer materials developed so far include (A) polymer materials mainly composed of natural products such as starch and protein, (B) non-aromatic polyester containing asymmetric carbon, (C) A non-aromatic polyester containing no asymmetric carbon may be mentioned. However, polymer materials mainly composed of natural products are inferior in melt processability, water resistance, mechanical properties and the like and are unsatisfactory in practical use. Non-aromatic polyesters containing asymmetric carbon have low productivity and result in high costs because a culture process using microorganisms is indispensable at the production stage of raw material monomers or the production stage of polymers. It was extremely unsatisfactory from the viewpoint. Examples of non-aromatic polyesters containing no asymmetric carbon include aliphatic polyesters containing no asymmetric carbon such as polysuccinate and polycaprolactone. However, many of these aliphatic polyesters are low heat resistant polymers having a melting point of about 110 ° C. or lower,
In particular, it has been difficult to apply to fields such as food packaging materials that require heat resistance for sterilization and cooking.

On the other hand, polyethylene oxalate is a non-aromatic polyester containing no asymmetric carbon and is known as a high melting point polymer material, as disclosed in the following documents (i) to (iv). It is a polymer. However, the conventional ones have a molecular weight that is too small to be melt-processed or have poor mechanical properties, and have little practical value. (I) W. H. Carothers et al. Reported that ethylene glycol and diethyl oxalate were heated to prepare an ester, which was then fractionally crystallized to obtain polyethylene oxalate having a melting point of 153 ° C. as a high molecular weight fraction thereof. J. Am. Chem. Soc. 52,
p. 3292 (1930)]. When this polymer is heated in vacuum, depolymerization occurs, producing the monomer ethylene oxalate (1,4-dioxane-2,3-dione). Polymerization occurs when the monomer is left to stand at room temperature. This polymerization reaction is accelerated by heating and has a melting point of 1
A 72 ° C. polymer is reportedly obtained. However, the polyethylene oxalate obtained by these methods has a low molecular weight closer to that of an oligomer than a polymer, and general melt processing cannot be applied to the polyethylene oxalate. No report has been made on the fact that it is a melt-molded product or the physical properties of the molded product.

(Ii) W. K. Cline et al., Cyclic ethylene oxalate.
oxalate) in a nitrogen atmosphere with a catalyst such as antimony trifluoride and tin chloride for about 165 to about 210.
A method for producing polyethylene oxalate having film- and fiber-forming properties by heating to ℃ has been proposed (US Pat. No. 3,197,445). Monomeric cyclic ethylene oxalate is obtained by condensing diethyl oxalate and ethylene glycol using a sodium catalyst,
A waxy prepolymer was synthesized and
It is prepared by heating at 91 to 216 ° C., preferably 175 to 190 ° C. for depolymerization. Purification of the monomer is performed by sublimation at 190 to 210 ° C. under reduced pressure. Next, the purified monomer is subjected to ring-opening polymerization using a catalyst such as antimony trifluoride. However, since the molecular weight of polyethylene oxalate obtained by this method is still too low, the polymer melt (pol
It has only been reported that a thread-like product was barely obtained by pulling up the glass rod by pulling it into the ymeric melt. Therefore, no report has been made on the physical properties of films and fibers.

(Iii) A. Alksnis et al. Heated oxalic anhydride and ethylene glycol to the reflux temperature of benzene in benzene in the presence of p-toluenesulfonic acid to give oligoethylene oxalate [ol].
igo (ethylene oxalate)] and then heating the oligomer in vacuum in the presence of SnCl ₂ .2H ₂ O to transesterify
By setting the
It is reported that a fiber-forming polyethylene oxalate was obtained [J. Polymer Sci. : Po
LymerChemistry Ed. Vol. 15,
p. 1855 (1977)]. However, the polyethylene oxalate obtained by this method has a low molecular weight,
The density of the crystallized product is as low as 1.45 g / cm ³ or less, and the melt viscosity is measured by melting the polymer once and then, in the supercooled state, the melting point of the polymer (178 ° C.).
It is barely measuring at a lower temperature (175 ° C). Therefore, this polymer is, of course, unsuitable for melt-molding processing, a satisfactory melt-molded product cannot be obtained, and the physical properties of the molded product have not been reported.

(Iv) G. E. Zaikov et al. Obtained polyethylene oxalate by polymerizing ethylene oxalate [Polymer Degradation].
and Stability 9 (1984) p. Four
1 to 50], the density is 1.475 g / cm ^{3 which} is extremely low even in a filamentous material obtained by crystallizing the polymer (crystallinity 73%). Since the density of normal crystallized polyethylene oxalate is usually 1.50 g / cm ³ or more, Zaik
The polyethylene oxalate of ov et al. has an extremely low density and is presumed to be a polymer having an extremely low degree of polymerization. Therefore, the polymer is unlikely to be a melt moldable polymer. On the other hand, there have been almost no reports on ethylene oxalate copolymers having a sufficiently high molecular weight that can be melt-molded. Of course, there is no report on the copolymerization for improving the melt processability of polyethylene oxalate.

Zaikov et al. Simultaneously reported a copolymer of ethylene oxalate, but the density of tablets of the obtained copolymer was 1.46 g / cm ^3.
It is a copolymer having a very low degree of polymerization and a very low number average degree of polymerization of 160. Therefore, the copolymer is
It is unlikely to be a melt-moldable polymer. that's all,
As described in detail, the conventional polyethylene oxalate is
It is a polymer having a relatively low molecular weight, and it has been difficult to form a film, fiber, or other molded product having satisfactory physical properties by a general melt processing method. Further, no proposal has been made about using polyethylene oxalate as a biodegradable polymer material by molding it into various molded products.

[0009]

DISCLOSURE OF THE INVENTION An object of the present invention is to provide a polyethylene oxalate which has a high molecular weight and is excellent in melt processability, heat resistance, crystal characteristics, mechanical characteristics and the like, and formed from the polyethylene oxalate. It is intended to provide various molded products and a method for producing the polyethylene oxalate. Another object of the present invention is to provide polyethylene oxalate with improved melt processability. More specifically, it is an object of the present invention to provide a melt processable copolymer polyethylene oxalate having improved thermal stability during melt processing by a copolymerization method. Another object of the present invention is to provide polyethylene oxalate, which is a biodegradable polymer material showing disintegration in soil, and a molded product thereof.

The present inventors have paid attention to the fact that polyethylene oxalate has a high melting point and has an ester bond in the molecular chain, so that it can be a heat-resistant biodegradable polymer material. As a result of various studies on the reason why high molecular weight polyethylene oxalate was not conventionally obtained, it was found that the molecular weight can be increased by effectively removing the impurities present in the monomer. Also,
It is desirable to carry out the ring-opening polymerization reaction at a relatively low temperature. The polyethylene oxalate of the present invention has a higher molecular weight than that obtained by the conventional method, and can be formed into a film, a fiber, an injection-molded product, etc. by a melt processing method, and further, it disintegrates in soil. The environmental load is small because it shows the nature. The present invention has been completed based on these findings.

[0011]

According to the present invention, the following formula (1)

[0012]

[Chemical 9] A polyethylene oxalate containing 60 repeating mol% or more of the repeating unit represented by
-0.40 g / d in a mixed solvent of chlorophenol and 1,2,4-trichlorobenzene in a weight ratio of 4: 1
1, the solution viscosity (η _inh ) measured at a temperature of 30 ° C. is 0.25 dl / g or more, and (b) the melt viscosity (η ^* ) measured at a temperature of 190 ° C. and a shear rate of 1000 / sec is 30.
Pa · s or more, and (c) the density of the amorphous substance is 1.48 g /
Provided is a polyethylene oxalate characterized by having a size of ³ cm ³ or more. Further, according to the present invention, various molded products such as sheets, films, fibers and injection molded products formed from the above-mentioned high molecular weight polyethylene oxalate are provided.

Further, according to the present invention, the following methods 1 and 2 for producing polyethylene oxalate are provided. 1. In the method for producing polyethylene oxalate in which a cyclic ethylene oxalate monomer obtained by depolymerizing an ethylene oxalate oligomer is heated in an inert gas atmosphere to perform ring-opening polymerization, (i) ethylene is used as the cyclic ethylene oxalate monomer. After washing the oxalate oligomer with an organic solvent for purification, (ii) heating the oligomer under reduced pressure to depolymerize it to sublimate the produced monomer, and then (iii) to obtain the monomer obtained by sublimation. A method for producing polyethylene oxalate, which comprises using a monomer purified by recrystallization in an organic solvent.

2. In the method for producing polyethylene oxalate in which a cyclic ethylene oxalate monomer obtained by depolymerizing an ethylene oxalate oligomer is heated in an inert gas atmosphere to perform ring-opening polymerization, (I) ethylene is used as the cyclic ethylene oxalate monomer. A mixture containing an oxalate oligomer and a high boiling point polar organic solvent,
Under normal pressure or under reduced pressure, it is heated to a temperature at which depolymerization of the oligomer occurs, the oligomer is dissolved in the polar organic solvent, and (II) further heating is continued to depolymerize the oligomer in the solution phase. Thereby, the produced monomer is distilled out together with the polar organic solvent, and then the monomer recovered from the distillate (III) is used.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below. Polymer Structure The chemical structure of the polyethylene oxalate of the present invention has 60 basic mol% or more of the repeating unit represented by the formula (1),
It is preferably a non-aromatic polyester containing 80 basic mol% or more, more preferably 90 basic mol% or more. Polyethylene oxalate containing more than 99 basic mol% of the repeating unit represented by the formula (1) is substantially a homopolymer. If this repeating unit is less than 60 basic%,
The disintegration property in soil (disintegration property in soil) may be impaired, and the heat resistance, crystallinity, mechanical properties, etc. may deteriorate. As the repeating unit other than the repeating unit of the formula (1), for example, the following formula (2)

[0016]

[Chemical 10] A repeating unit represented by the formula (3)

[0017]

[Chemical 11] A repeating unit represented by (n = 1 to 6) and a formula (4)

[0018]

[Chemical 12] (However, m is an integer of 0 to 6).

The polyethylene oxalate of the present invention is classified into a homopolymer or a polymer of a group (I) close to a homopolymer depending on the content of a copolymerization component and a polymer (II) of which the physical properties of the homopolymer are modified by copolymerization. It can be roughly divided into polymers. The polymers of group (I) have 9 repeating units of formula (1)
It is a polymer containing more than 9 basic mol% and is substantially a homopolymer. The polymers belonging to this group (I) are characterized by high performance such as high crystallization rate, high melting point, high strength and high elastic modulus. The polymers of group (II) are
60 to 99 basic mol% of the repeating unit represented by the formula (1) and 1 of the repeating unit represented by the formulas (2) to (4).
-40 basic mol%. Polymers belonging to this group (II) are characterized by easy melt processability such as low crystallization rate, low melting point and high thermal stability during melting.

The repeating units of the formulas (2) to (4) include, as comonomers, for example, lactide, glycolide, lactone (having 7 or less carbon atoms), and alkylene oxalate (having 3 to 9 carbon atoms in the alkylene group). It can be introduced into the molecular chain of polyethylene oxalate by ring-opening copolymerization with a cyclic ethylene oxalate monomer using at least one cyclic monomer selected from the group consisting of 0.1 basic mol% of these repeating units
By copolymerizing so as to contain the above, the crystallization rate of polyethylene oxalate can be controlled and the melt processing characteristics can be improved. However, if the copolymerization ratio of these comonomers is too large, the copolymer becomes amorphous and heat resistance is likely to be impaired. Therefore, the upper limit of the proportion of repeating units derived from a comonomer is 40 basic mol%, preferably 30
Basic mol%. In addition, in the present invention, each repeating unit is referred to as one basic mole.

Since lactide and glycolide are cyclic diesters, usually 2 basic moles of each repeating unit are produced from 1 mole of these monomers. The repeating unit derived from lactide is represented by formula (2). The repeating unit derived from glycolide is the case where n = 1 in the formula (3). Examples of the lactone include β-propiolactone, β-butyrolactone, pivalolactone, γ-
Butyrolactone, δ-valerolactone, β-methyl-δ
-Valerolactone, ε-caprolactone and the like can be mentioned. The repeating unit derived from lactone is the case where n = 2 to 6 in the formula (3). Examples of the alkylene oxalate include those having an alkylene group having 3 to 9 carbon atoms such as propylene oxalate (propylene oxalate). The repeating unit derived from alkylene oxalate is represented by formula (4).

Polymer Physical Properties The polyethylene oxalate of the present invention is a polymer having a high molecular weight and excellent heat resistance, crystal characteristics, mechanical strength, melt processability, and the like, and is disintegratable in soil (disintegration in soil). ) Is a biodegradable polymer material.

<Molecular Weight> The polyethylene oxalate of the present invention is a high molecular weight polymer. The molecular weight of polyethylene oxalate can be evaluated by solution viscosity (η _inh ) and melt viscosity (η ^* ). The solution viscosity (η _inh ) of the polyethylene oxalate of the present invention is 0.25 dl.
/ G or more, preferably 0.30 dl / g or more, more preferably 0.50 dl / g or more. However, the solution viscosity is 0. 1 in a mixed solvent of m-chlorophenol and 1,2,4-trichlorobenzene in a weight ratio of 4: 1.
It is a value measured under the conditions of 40 g / dl and a temperature of 30 ° C.
The solution viscosity of polyethylene oxalate is 0.25 dl /
If it is less than g, the molecular weight is low, and the melt-molded product obtained from this may have insufficient practical mechanical properties. Further, if the solution viscosity is less than 0.25 dl / g, the melt viscosity (η ^* ) of polyethylene oxalate also becomes small, which may make melt processing difficult.

The melt viscosity (η ^* ) of the polyethylene oxalate of the present invention is 30 Pa · s or more, preferably 50 Pa · s or more, more preferably 100 Pa · s or more. However, the melt viscosity (η ^* ) is 190 ° C,
It is a value measured under the condition of a shear rate of 1000 / sec. Polyethylene oxalate has a melt viscosity (η ^* ) of 30 Pa
If it is less than s, drawdown or fusing is likely to occur during extrusion molding, and melt molding may be difficult.
For example, in the case of melt spinning polyethylene oxalate, if drawdown is severe during melt extrusion, it may be difficult or impossible to perform spinning. Further, if the melt viscosity is too low, the practical mechanical properties of the melt-molded product may be insufficient.

<Thermophysical Properties> The polyethylene oxalate of the present invention has a high melting point, crystallinity, and a high crystallization rate, but the thermal properties can be widely changed by changing the copolymerization composition. Can be made. That is, by changing the type of the copolymerization component, the copolymerization ratio, etc., (A) crystalline and high crystallization rate, (B) crystalline and low crystallization rate, and (C) substantially It is possible to obtain an amorphous material.

(A) Polyethylene oxalate having a high crystallinity and a high crystallization rate A polymer belonging to this category is a homopolymer of ethylene oxalate or a copolymer having a very small content of other copolymerization components. That is, such a polymer of group (I) corresponds to such polyethylene oxalate. However, among the polymers of group (II), those having a very small amount of copolymerization component may correspond thereto. Such polyethylene oxalate typically has the following thermal physical properties. Melting point (Tm) is 130 ° C. or higher, melting enthalpy (ΔHm) is 20 J / g or higher, and melting crystallization enthalpy (ΔHmc) is 20 J / g or higher. However, melting point (Tm) and melting enthalpy (ΔHm)
Is the melting point and melting enthalpy detected when a 0.2 mm thick amorphous sheet sample was heated at a rate of 10 ° C./min in an inert gas atmosphere using a differential scanning calorimeter (DSC). And the melt crystallization enthalpy (ΔHmc) is
After the amorphous sheet sample reaches 220 ° C. by heating,
It is the melt crystallization enthalpy detected immediately when the temperature is lowered at a rate of 10 ° C./min.

Polyethylene oxalate, which is crystalline and has a high crystallization rate, usually has a melting point (Tm) of 130 ° C. or higher, preferably 150 ° C. or higher, more preferably 170 ° C. or higher. When the melting point (Tm) is less than 130 ° C, the heat resistance is insufficient, and for example, when polyethylene oxalate is used as a food packaging material, sterilization treatment such as retort treatment becomes difficult. Therefore, it is difficult to use in the fields of food packaging materials, microwave oven wrap materials, medical materials, and the like.

Polyethylene oxalate, which is crystalline and has a high crystallization rate, has a melting enthalpy (ΔHm) of 20 J / g or more, preferably 30 J / g or more, more preferably 40 J or more, which is one of the indicators of crystallinity. / G or more. Melt enthalpy (ΔHm) is 20 J /
If it is less than g, it becomes difficult to achieve heat resistance with a melting point (Tm) of 130 ° C. or higher, and the mechanical properties of the resulting molded article may be insufficient. Regarding the crystallization rate, the melting crystallization enthalpy (ΔHmc), which is one of the indicators, is 20 J / g or more, preferably 25 J / g.
As described above, more preferably 30 J / g or more. Polyethylene oxalate having the above-mentioned thermal properties is particularly suitable for injection molding, multifilament spinning, melt blow, and other molding processes that require high-speed crystallization.

(B) Polyethylene oxalate which is crystalline and has a low crystallization rate A polymer belonging to this category is a copolymer mainly containing the repeating unit of the formula (1) and containing a small amount of a copolymerization component. That is, such polyethylene oxalate mainly corresponds to polyethylene oxalate which is the above-mentioned group (II) polymer and has a small amount of copolymerization components. Such polyethylene oxalate typically has the following thermal physical properties. Melting point (Tm) is 130 ° C. or more, melting enthalpy (ΔHm) is 20 J / g or more, and melting crystallization enthalpy (ΔHmc) is less than 20 J / g.

The melting point (Tm), which is an index of heat resistance, and the melting enthalpy (ΔHm), which is an index of crystallinity, are almost the same as those in the group (A). What is different from the group (A) is the crystallization rate.
Polyethylene oxalate which is crystalline and has a low crystallization rate has a melt crystallization enthalpy (ΔHmc) which is one of the indicators of the crystallization rate of less than 20 J / g, preferably 15 J.
/ G, and the crystallization rate is low.
Polyethylene oxalate having a high crystallization rate of (A) is likely to form coarse crystals in extrusion molding and the like, and may give a poor molded product. However, by reducing the crystallization rate as in (B) by copolymerization (group II) or the like, generation of coarse crystals during melt processing can be suppressed. Therefore, polyethylene oxalate having a low crystallization rate as described above has been improved in molding processing such as monofilament spinning, inflation molding, blow molding, and extrusion molding such as the T-die method.

(C) Substantially Amorphous Polyethylene Oxalate A polymer belonging to this group is a copolymer mainly composed of the repeating unit of the formula (1) and containing a relatively large amount of a copolymerization component. That is, such polyethylene oxalate corresponds to polyethylene oxalate which is a polymer of the above-mentioned group (II) and has a large amount of copolymerization components.

<Thermal stability during melt processing-easy melt processability>
Conventional polyethylene oxalate is thermally unstable,
Since the thermal decomposition temperature Td of the polymer is close to the melting point Tm of the polymer, when the polymer is melted by heating it to a temperature of Tm or higher during melting processing, there is a possibility that thermal decomposition occurs, which makes melting processing difficult. On the other hand, the polyethylene oxalate of the present invention is a homopolymer,
Since it was produced by ring-opening polymerization of a high-purity monomer, its thermal stability was considerably improved, and melt processing became easy. However, in the above-mentioned polymer of group (II), when the copolymerization component is added in an appropriate amount, Tm is lowered, but Td is hardly lowered. If the temperature range between Tm and Td is widened, the melt processing temperature ( Usually, thermal stability at (Tm + about 10 ° C.) is greatly improved, and melt processing becomes easier.

The thermal stability of a polymer during melt processing is determined, for example, by the TGA method at the melt processing temperature (ie, Tm +
It can be quantitatively evaluated by the average weight loss rate (average weight loss rate in the initial 30 minutes) due to thermal decomposition under an inert atmosphere at 10 ° C. According to this evaluation, the average weight loss rate of the polyethylene oxalate of the present invention at (Tm + 10 ° C.) is usually 0.5% by weight / min or less, preferably 0.
It is 3% by weight / min or less, more preferably 0.2% by weight / min or less. On the other hand, conventional polyethylene oxalate has a large average weight loss rate and is inferior in thermal stability.

As a method of improving the thermal stability of the polyethylene oxalate of the present invention, there is a method of appropriately copolymerizing 1 basic mol% or more of a comonomer.
A polymer having improved thermal stability can be obtained until the average weight loss rate is 0.1% by weight / min or less, and depending on the conditions, it is 0.05% by weight / min or less. Such polyethylene oxalate typically has a melting enthalpy (ΔHm) of 20 J, which is one of the indicators of crystallinity.
/ G, preferably less than 15 J / g. Since amorphous polyethylene oxalate has poor heat resistance and crystallinity, it can be used in fields such as polymer blends and optical materials.

[0035] <Density> polyethylene oxalate of the present invention, the density of HiAkirabutsu is 1.48 g / cm ³ or more, preferably 1.51 g / cm ³ or more dense polymer. A polymer having an amorphous substance density of less than 1.48 g / cm ³ has insufficient molecular weight, has low thermal stability, and foams during melt processing, resulting in melt processability and the obtained melt-molded product. Has very unsatisfactory mechanical properties.

<Biodegradability> Since the polyethylene oxalate of the present invention exhibits disintegratability in soil, it can be evaluated as a biodegradable polymer material. The soil disintegration property is that when an amorphous sheet-like sample with a thickness of 0.2 mm is prepared from polyethylene oxalate and embedded in soil such as upland at a depth of 10 cm, it will disintegrate within 1 year and It can be evaluated by whether or not the shape is lost. The polyethylene oxalate of the present invention disintegrates in soil within 1 year, and more specifically, the onset of disintegration is observed in 0.5 months to 1 month. The reason why the polyethylene oxalate of the present invention exhibits disintegration in soil is that, in addition to being a non-aromatic polyester, it does not substantially contain L-form asymmetric carbon in its molecular chain, so it is digested by microorganisms in soil. It is presumed that this is because it is easily done.

Molded Product The polyethylene oxalate of the present invention can be molded into various molded products such as extrusion molded products such as fibers, sheets and films, or injection molded products by melt molding. The molded product of the present invention has characteristics such as soil disintegration, high heat resistance, and high mechanical properties.

<Non-Oriented Sheet> The polyethylene oxalate of the present invention has a melting enthalpy (ΔHm) of 2
Those crystalline at 0 J / g or more can be formed into non-oriented amorphous sheets or crystallized sheets (including films). Industrially, using an extruder equipped with a T-die,
Polyethylene oxalate at a temperature above the melting point (Tm),
For example, in a temperature range of Tm to (Tm + 50 ° C.), a sheet (or a film) can be formed by extruding a sheet from a T die. The extruded sheet is usually taken up on a roll. The thickness of the sheet is usually about 1 μm to 3 mm. The non-oriented amorphous sheet formed from the polyethylene oxalate of the present invention is colorless and has extremely high transparency. When this amorphous sheet is fixed and heat-treated (fixed-length heat treatment) for 1 second to 10 hours within the temperature range of crystallization temperature (Tc) to melting point (Tm), a non-oriented crystallized sheet can be obtained. it can. The non-oriented crystallized sheet of the present invention is a translucent, tough sheet that is hard to break even when folded.

The non-oriented heat-setting sheet (non-oriented crystallized sheet) formed from the crystalline polyethylene oxalate of the present invention has the following physical properties. Melting point (Tm) 130 ° C or higher, density 1.50 g / cm ³ or higher, tensile strength 0.05 GPa or higher, tensile elastic modulus 1.0 GPa or higher, elongation 3% or higher, and heat shrinkage (110 ° C / 10 minutes) 30% or less.

In particular, the non-oriented heat setting formed from polyethylene oxalate belonging to the group (I) or a part of the group (II) in which the content of the repeating unit represented by the formula (1) is 90 basic mol% or more. The sheet has the following physical properties. Melting point (Tm) 170 ° C. or higher, preferably 175 ° C. or higher, density 1.53 g / cm ³ or higher, tensile strength 0.06 GPa or higher, preferably 0.08 G
Pa or more, tensile elastic modulus 1.2 GPa or more, preferably 1.5 GP
a or more, elongation of 3% or more, and heat shrinkage rate (110 ° C./10 minutes) of 20% or less. The glass transition temperature (Tg) of the non-oriented sheet is usually 20.
Although it is -50 ° C, it can be easily lowered to below that by changing the copolymerization composition or adding a plasticizer.

<Uniaxially oriented film> By stretching an amorphous sheet of polyethylene oxalate in a uniaxial direction,
Uniaxially oriented films (including sheets) can be obtained. Specifically, the amorphous sheet is uniaxially rolled with a roll and / or a tenter at an area magnification of 2 to 20 times within a temperature range of glass transition temperature (Tg) to crystallization temperature (Tc). Orient by stretching. The film obtained by uniaxial stretching is usually toughened by heat treatment (fixed length heat treatment) in a fixed state within a temperature range of crystallization temperature (Tc) to melting point (Tm) for 1 second to 10 hours. It can be a heat setting film. The thickness of the uniaxially oriented film is usually 1 μm to 3 mm. The low crystallization rate polymer of group (II) is unlikely to form coarse spherulites when forming an amorphous sheet, and thus is particularly easy to give a uniaxially oriented film having excellent physical properties.

The uniaxially oriented film formed from the crystalline polyethylene oxalate of the present invention has the following physical properties. Melting point (Tm) 130 ° C. or higher, density 1.50 g / cm ³ or higher, tensile strength (alignment direction) 0.07 GPa or higher, tensile elastic modulus (alignment direction) 1.0 GPa or higher, elongation (alignment direction) 3% or higher, Moreover, the heat shrinkage (110 ° C./10 minutes) (orientation direction) is 30% or less.

In particular, a uniaxially oriented film formed from polyethylene oxalate belonging to the group (I) or a part of the group (II) in which the content of the repeating unit represented by the formula (1) is 90 basic mol% or more is , Has the following physical properties. Melting point (Tm) 170 ° C. or higher, preferably 175 ° C. or higher, density 1.53 g / cm ³ or higher, tensile strength (alignment direction) 0.10 GPa or higher, preferably 0.15 GPa or higher, tensile elastic modulus (alignment direction) 1. 2 GPa or more, preferably 1.5 GPa or more, elongation (orientation direction) 3% or more, and thermal shrinkage (110 ° C./10 minutes) (orientation direction) 20% or less. The Tg of the uniaxially oriented film is usually 20 to 50 ° C., but it can be easily lowered to below that by changing the copolymerization composition or adding a plasticizer.

<Biaxially oriented film> By stretching an amorphous sheet of polyethylene oxalate biaxially,
Biaxially oriented films (including sheets) can be obtained. Specifically, the amorphous sheet is biaxially rolled with a roll and / or a tenter at an area magnification of 2 to 20 times in a temperature range of glass transition temperature (Tg) to crystallization temperature (Tc). To stretch and orient. The film obtained by biaxial stretching is generally strong by being heat-treated (fixed-length heat treatment) for 1 second to 10 hours within a temperature range of crystallization temperature (Tc) to melting point (Tm) in a fixed state. It can be a heat setting film. The thickness of the biaxially oriented film is usually 1 μm to 3 mm.

The crystalline polyethylene oxalate of the present invention is extruded by an inflation method using an extruder equipped with a ring die or the like in a temperature range of Tm to (Tm + 50 ° C.) and a temperature range of Tg to Tc. A biaxially oriented film can be formed by inflating the film with an area magnification of 2 to 20 times. This film is also Tc
By heat-treating in the temperature range of to Tm, a strong heat setting film can be obtained. The low crystallization rate polymer in the group (II) is unlikely to form coarse spherulites during the production of an amorphous sheet or during inflation, and thus is particularly easy to provide a biaxially oriented film having excellent physical properties. .

The biaxially oriented film formed of the crystalline polyethylene oxalate of the present invention has the following physical properties (physical properties in the maximum stretching direction). Melting point (Tm) 130 ° C or higher, density 1.50 g / cm ³ or higher, tensile strength 0.07 GPa or higher, tensile elastic modulus 1.0 GPa or higher, elongation 3% or higher, and heat shrinkage (110 ° C / 10 minutes) 30% or less.

In particular, the biaxially oriented film formed from a part of the group (I) or the group (II) of polyethylene oxalate having a content of the repeating unit represented by the formula (1) of 90 basic mol% or more is , Has the following physical properties. Melting point (Tm) 170 ° C. or higher, preferably 175 ° C. or higher, density 1.53 g / cm ³ or higher, tensile strength 0.10 GPa or higher, preferably 0.15 G
Pa or more, tensile elastic modulus 1.2 GPa or more, preferably 1.5 GP
a or more, elongation of 3% or more, and heat shrinkage (110 ° C./10 minutes) of 20% or less, preferably 10% or less. The Tg of the biaxially oriented film is usually 20 to 50 ° C., but it can be easily lowered to below that by changing the copolymer composition or adding a plasticizer.

<Fiber> A fiber can be obtained by melt spinning using the crystalline polyethylene oxalate of the present invention. Specifically, according to an ordinary melt spinning method, an extruder equipped with a single-hole or double-hole nozzle for spinning is used to extrude in a temperature range of Tm to (Tm + 50 ° C.), and a take-up ratio R ₁ (take-off speed / Discharge speed) is 2-100
A tough heat-fixing fiber can be obtained by taking it out in the range of 0, drawing 1 to 20 times further if necessary, and heat-treating it in the temperature range of Tc to Tm. The polyethylene oxalate of the present invention can also be directly formed into a nonwoven fabric by a melt blow method or the like. Fiber diameter is usually 1 μm
It is about 1 mm. The low crystallization rate polymer of the group (II) does not easily generate coarse spherulites when melt-spinning a large-diameter yarn such as a monofilament, and thus particularly easily gives an excellent large-diameter yarn.

The fiber formed of the crystalline polyethylene oxalate of the present invention has the following physical properties. Melting point (Tm) 130 ° C or higher, density 1.50 g / cm ³ or higher, tensile strength 0.07 GPa or higher, tensile elastic modulus 3.0 GPa or higher, tensile elongation 3% or higher, and heat shrinkage (110 ° C / 10 minutes ) 40% or less.

In particular, the fiber formed from a part of the polyethylene oxalate of the group (I) or the group (II) in which the content ratio of the repeating unit represented by the formula (1) is 90 basic mol% or more is as follows. It has the following physical properties. Melting point (Tm) 170 ° C. or higher, preferably 175 ° C. or higher, density 1.53 g / cm ³ or higher, tensile strength 0.15 GP or higher, preferably 0.25 GP
Above, tensile elastic modulus is 4.0 GPa or more, preferably 6.0 GPa
a or more, tensile elongation of 3% or more and heat shrinkage (110 ° C./10 minutes) of 30% or less.

<Injection Molded Product> The polyethylene oxalate of the present invention can be molded into various shapes by an injection molding method. Polyethylene oxalate can be subjected to injection molding by itself as neetresin or as a composition by blending with a filler (inorganic filler and / or fibrous filler) or other resin. For the crystalline polyethylene oxalate of the present invention, an injection molding machine equipped with an injection molding die is used to measure the cylinder temperature Tm to
Extrusion in the temperature range of (Tm + 50 ° C), mold temperature 0 to 1
50 ° C temperature range, injection pressure 0.01-1000 GPa
A strong injection-molded product can be obtained by injecting under the pressure range condition.

For injection molding, some high crystallization rate polymers of group (I) or group (II) allow for injection molding processing in high speed cycles. The injection-molded product formed from the crystalline polyethylene oxalate (knee resin) of the present invention has the following physical properties. Melting point (Tm) 130 ° C or higher, preferably 170 ° C or higher, bending strength 0.01 GPa or higher, preferably 0.02G
Pa or more and flexural modulus of 1.0 GPa or more, preferably 2.0 GP
a or more. When the composition containing polyethylene oxalate of the present invention is used, injection molded products having various physical properties can be obtained depending on the types and blending amounts of the filler and the blended resin.

Resin Composition The polyethylene oxalate of the present invention can be used alone, but if desired, a natural or synthetic polymer material, a filler, and other additives may be blended and used as a composition. can do. As various materials to be mixed, for example, polycaprolactone, polylactic acid, polyglycolic acid, polysuccinic acid ester, poly (3-hydroxybutanoic acid), (3-hydroxybutanoic acid / 4-hydroxybutanoic acid) copolymer, starch, acetic acid Plastic materials such as cellulose, chitosan, alginic acid, polyvinyl alcohol, polyethylene, polyvinyl acetate, polyvinyl chloride, polystyrene, polyglutamic acid ester; natural rubber, polyester rubber, polyamide rubber, styrene-butadiene-styrene block copolymer (SB
S), rubber or elastomer such as hydrogenated SBS; reinforcing fiber such as carbon fiber, silica fiber, glass fiber; inorganic filler such as carbon black, silica powder, alumina powder, titanium oxide powder, talc, clay and calcium sulfate; And so on. These may be used alone or in combination of two or more.

The polyethylene oxalate of the present invention includes
Plasticizers such as aliphatic monobasic acid ester (butyl oleate etc.), aliphatic dibasic acid ester (hexyl adipate etc.), oxy acid ester (triethyl acetyl citrate etc.), phthalate ester (dibutyl phthalate etc.) Can be blended. A composition obtained by blending these plasticizers can give a flexible molded product having a glass transition temperature of room temperature or lower, and can be used, for example, as a food packaging material or a wrap material. Low-boiling alcohols, low-boiling ethers, etc. can be sorbed on the polyethylene oxalate of the present invention, and foamed by heating to give a foamed molded product. Further, the foamed molded product can be easily provided by the partial thermal decomposition method of the polymer itself. The polyethylene oxalate of the present invention includes a light stabilizer, a heat stabilizer,
Various stabilizers such as antioxidants, waterproofing agents (wax, silicone oil, higher alcohols, lanolin, etc.), pigments, dyes,
Lubricants, flame retardants and the like can be added.

Method for Producing Polyethylene Oxalate The high molecular weight polyethylene oxalate of the present invention cannot be obtained by the method disclosed in the documents (i) to (iv). The high molecular weight polyethylene oxalate cannot be obtained by the methods described in the literatures (ii) and (iii), which are reported to obtain a polymer having a film or fiber-forming property. That is, a method of Cline et al. (Abbreviated as “conventional method 1”) in which an ethylene oxalate monomer obtained by decomposing / sublimating oligoethylene oxalate is directly subjected to ring-opening polymerization, or by condensing oxalic anhydride and ethylene glycol Method of Alksnis et al. For transesterification of the obtained oligoethylene oxalate (abbreviated as "conventional method 2")
Also, the high molecular weight polyethylene oxalate of the present invention cannot be obtained.

The high molecular weight polyethylene oxalate of the present invention is obtained by heating a cyclic ethylene oxalate monomer obtained by heating and depolymerizing oligoethylene oxalate (ie, ethylene oxalate oligomer) in an inert gas atmosphere. It can be produced by heating at room temperature and ring-opening polymerization. In order to obtain a copolymer by copolymerizing the cyclic ethylene oxalate monomer with lactide, glycolide, lactone, alkylene oxalate, etc., these comonomers may be coexisted in a predetermined ratio and copolymerized.

The ethylene oxalate oligomer can be synthesized by a conventional method. For example, the oligomer can be prepared by condensing (dealcoholizing) an alkyl oxalate ester (eg, diethyl oxalate) and ethylene glycol to form an ester. The condensation reaction is, for example, 150 to 200 ° C., preferably 170 to 1
It can be performed by heating at 90 ° C. for 1 to 10 hours, preferably 2 to 5 hours. In the condensation reaction,
A catalyst such as sodium may be present. In the present invention, as the polyethylene oxalate monomer, a cyclic ethylene oxalate monomer highly purified by a special method is used.

As the first method for producing the cyclic ethylene oxalate monomer used in the present invention, (i) the ethylene oxalate oligomer is washed with an organic solvent for purification, and (ii) the oligomer is heated under reduced pressure. And depolymerize the resulting monomer to sublimate, and then
(Iii) A method in which a monomer obtained by sublimation is recrystallized in an organic solvent for purification is exemplified. The crude ethylene oxalate oligomer obtained by the method described above may be volatilized during sublimation by washing with an organic solvent (eg, aromatic hydrocarbon such as toluene) in advance before the depolymerization / sublimation step. , Remove impurities that may cause bumping. To that end, the oligomer is, for example, heated (eg 100-2).
It is preferable to wash with an organic solvent (00 ° C).

In order to sublimate the product while depolymerizing the purified oligomer, the purified oligomer and a catalyst (eg, tin tetrachloride), if necessary, are placed in a reaction vessel and decompressed (eg, about 5 to 7 Torr). 2) is heated to 190 to 220 ° C. to depolymerize the oligomer, sublimate the produced cyclic monomer, and collect it in the cooling part of the reaction vessel. The ethylene oxalate monomer obtained by sublimation is purified by recrystallization in a solvent (eg, acetonitrile, acetic acid, acetone, etc.) to remove impurities mixed in the monomer in the sublimation step. The melting point (Tm) of the purified monomer obtained by recrystallization in this manner is about 144.5 ° C.

As the second method for producing the cyclic ethylene oxalate monomer used in the present invention, a mixture containing (I) an ethylene oxalate oligomer and a high-boiling polar organic solvent is added under normal pressure or reduced pressure to the oligomer. Is heated to a temperature at which the depolymerization occurs to dissolve the oligomer in the polar organic solvent, and (II) further heating is performed to depolymerize the oligomer in the solution phase, whereby the product monomer is added to the polar organic solvent. Distill with solvent, then (II
I) The method of recovering a monomer from a distillate is mentioned.
In this second production method, the boiling point is 225 to 450 ° C, preferably 255 to 430 ° C, more preferably 285 to 4 ° C.
A polar organic solvent having a high boiling point of 20 ° C. is used. Examples of such a polar organic solvent include dibutyl phthalate (D
BP), benzyl butyl phthalate (BBP), tricresyl phosphate (TCP), and other solvents capable of dissolving ethylene oxalate oligomers.

In this second production method, the oligomer and the high boiling point polar organic solvent (0.3 to 50 times by weight of the oligomer) are added under normal pressure or reduced pressure (preferably 0.1 to 9).
(0 kPa) is heated to a temperature (about 170 to 300 ° C.) at which depolymerization of the oligomer occurs to form a uniform solution, and further heating is continued to cause depolymerization of the oligomer in the solution phase to form a ring. Ethylene oxalate monomer is distilled together with the solvent, the azeotropic distillate is cooled, if necessary, a non-solvent of the monomer (for example,
Cyclohexane, toluene, benzene, etc.) to solidify / precipitate the monomer to separate / recover from the co-distillate, and then wash or extract with a non-solvent, and purify by recrystallization, etc. if necessary. To do.

In the polymerization method of the present invention, the ring-opening polymerization of the monomer is carried out at 150 ° C. or higher but lower than 200 ° C., preferably 155 to 550 ° C.
It is desirable to perform in a relatively low temperature range of 190 ° C. The ring-opening polymerization of a cyclic ethylene oxalate monomer is carried out under an atmosphere of an inert gas such as nitrogen gas under a catalyst (eg, tin tetrachloride, tin dichloride, tin octoate, aluminum chloride,
It is preferably carried out by heating to a temperature of less than 200 ° C. in the presence of zinc chloride, antimony trifluoride, titanium tetrachloride, zinc acetate, lead oxide, etc.).

[0063] Applications of polyethylene oxalate of the present invention, as a film or sheet, retortable food packaging materials, is suitable as microwavable plastic wrap. The foamed molded product is suitable as an instant food container, a fresh seafood container, a fruit container, an egg container, a cushioning material, a heat insulating material, etc., which has a low environmental load. BACKGROUND ART Bag-shaped molded products, bottles and the like are used in the fields of garbage bags, foods, cosmetics, kitchen utensils and other daily necessities as packaging materials or containers with a low environmental load. Fibers (monofilament, multifilament, non-woven fabric, etc.) are environmentally friendly packaging tapes, fishing lines, fishnets, surgical sutures,
Used as sterilizable gauze and bandages. The polyethylene oxalate of the present invention is a heat-sealing material, as a barrier material, a resin for multilayer extrusion, a resin for laminating,
It is used as a resin for cards and a resin for blending. It is also used as an X-ray resist, a UV resist and the like.

[0064]

EXAMPLES The present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited to these examples. The methods for measuring physical properties are as follows. (1) Solution viscosity (η _inh ) An amorphous sheet of each polymer was used as a sample, and this was measured by m-
Chlorophenol / 1,2,4-trichlorobenzene =
Immerse in a mixed solvent of 8/2 (weight ratio) and about 10 at 150 ° C.
It was heated and dissolved for a minute to give a solution having a concentration of about 0.4 g / dl, and then the melt viscosity was measured at 30 ° C. using an Ubbelohde viscometer. (Unit: dl / g) (2) Melt viscosity (η ^* ) As a sample, an amorphous sheet of polymer was heated and crystallized at about 130 ° C. for 10 minutes, and used as D = 0.5 m.
m, L = 5 mm, equipped with a capillograph (manufactured by Toyo Seiki Co., Ltd.), temperature 190 ° C., shear rate 1
The melt viscosity was measured at 000 / sec. (Unit: Pa · s) (3) Tg, Tm, ΔHm, ΔHmc Using a polymer amorphous sheet as a sample, using a differential scanning calorimeter (manufactured by METTTLER, DSC30 type) under a nitrogen stream at 10 ° C / The temperature was raised at a rate of minutes, the glass transition temperature (Tg), the melting point (Tm), and the enthalpy of fusion (ΔHm) were measured at that time, and after reaching 220 ° C, immediately at a rate of 10 ° C / min. When the temperature is lowered, the melting crystallization temperature (Tmc) and the melting crystallization enthalpy (ΔHm)
c) was measured. (4) Density The polymer density relates to the amorphous sheet, and the density of the molded product is
The crystallized product was measured according to JIS R-7222 (Pycnometer method using n-butanol). (5) About 3 cm of amorphous sheet (0.2 mm thick) of each polymer
It was cut into strips of width, embedded in soil at a depth of about 10 cm, and dug out every half month to observe the shape.
The time when the amorphous sheet collapsed and the shape began to collapse was observed. When the shape collapsed within one year after being buried in the soil, it was evaluated as having soil disintegration (○). (6) Heat shrinkage rate The heat shrinkage rate (110 ° C./10 minutes) is 10 mm wide strip-shaped samples for films and sheets, and monofilaments are used for yarns as they are, and the sample length is 50 mm. Clip one end like
It was suspended and heated in an air circulation type gear oven at 110 ° C. After heating for 10 minutes, the sample was taken out of the gear oven, the size of the sample was measured, and the shrinkage ratio was determined. (7) Tensile property Tensileon (manufactured by Toyo Baldwin) was used for the tensile property of the sheet, film and fiber at a temperature of 23.
℃, test length 30mm (width of sheet and film is 10mm)
The tensile speed was measured at 100 mm / min when measuring tensile strength and elongation, and at 10 mm / min when measuring tensile modulus. (8) Thermal stability during melt processing The thermal stability during melt processing is 10 from the Tm of the sample polymer.
A temperature higher by 0 ° C. was set as the melt processing temperature, and the average weight loss rate in the initial 30 minutes at that temperature was measured under a nitrogen stream using a TG30 type TGA manufactured by METLER.

Example 1 Preparation Example 1 of Monomer In a 1 liter autoclave, diethyl oxalate 58 was added.
5 g (4.0 mol) and 160 g ethylene glycol
(2.6 mol) was charged, and the mixture was stirred at 170 ° C. for 2
After heating for 1 hour at 190 ° C. for 1 hour, condensation was carried out while distilling ethanol to produce a crude ethylene oxalate oligomer. After the reaction was completed, the pressure was reduced to collect unreacted materials. To the crude oligomer remaining in the autoclave, 400 g of toluene was added, and while stirring, 130-
After heating at 140 ° C. for 2 hours and then at 160 to 170 ° C. for 10 minutes, cooling and filtering were performed to collect solids.
This solid content was dried under reduced pressure at 150 ° C. to obtain a purified oligomer (powder). 10 g of the purified oligomer thus obtained and SnCl ₄ .nH ₂ O (n = 6.5) 10-2
0 mg was put into a glass tube for sublimation Oven [manufactured by Shibata Kagaku Co., Ltd.], and 2 under reduced pressure of about 5 to 7 Torr.
The produced ethylene oxalate monomer was sublimated while being heated at 00 to 220 ° C. for about 1 hour to depolymerize the oligomer, and collected on the cold finger of the oven. After further washing the sublimation monomer with toluene, 40 to 5
It is dissolved in 500 g of acetonitrile at 0 ° C., left standing at room temperature for 3 days, then filtered, benzene is added to the mother liquor to precipitate a monomer crystal, and the liquid phase is decanted to obtain about 5 monomer crystals.
It was washed twice with 0 ° C. benzene. The obtained crystals are dried under reduced pressure at room temperature to obtain a sublimation recrystallized monomer (MOX-
1) (Tm = 144.5 ° C.) was obtained. Several batches of (MOX-1) were prepared in a similar manner.

Synthesis of Polymer 50 g of the monomer (MOX-1) was mixed with SnCl ₄ .nH ₂ O.
0.008 g of (n = 6.5) was added by sprinkling the 4.5 wt% ether solution. This is PTFE
(Polytetrafluoroethylene) tube made of PFA (tetrafluoroethylene / perfluorovinyl ether copolymer) equipped with a gas introduction tube, blown with nitrogen gas for 20 minutes to remove ether and water, and then nitrogen. Polymerization was carried out by heating at 170 ° C. for 2 hours while blowing gas. The monomer (MOX-1) was melted in about 5 minutes after the start of heating, and nitrogen gas was bubbled in the melted monomer. The monomer viscosity then rose sharply and the melt almost immobile and solidified to a spongy solid after about 5-10 minutes. After completion of heating, the mixture was allowed to cool at room temperature to crystallize the sponge-like solid. After crystallization, the sponge-like solid was taken out from the PFA tube to obtain a polymer (POX-1). The polymer was quickly stored in a polyethylene bag. Table 1 shows the physical properties of the obtained polymer.

[Examples 2 to 5] Monomer (MOX-1)
In addition, as shown in Table 1, the copolymer was synthesized by the same method as in Example 1 except that (R)-(−)-lactide and, if necessary, a small amount of ε-caprolactone were added. Copolymer POX-2 (Example 2), PO
X-3 (Example 3), POX-4 (Example 4), and P
OX-5 (Example 5) was obtained. Table 1 collectively shows these comonomer compositions and the physical properties of the obtained copolymers.

Example 6 Preparation Example 2 of Monomer 40 g of crude ethylene oxalate oligomer prepared by the same method as in Example 1 was cooled with ice water, and a receiver was connected 3
A 00 ml three-necked flask was charged, and 200 g of dibutyl phthalate (DBP) as a high boiling polar organic solvent was added thereto. While stirring, the mixture was heated at 235 to 245 ° C. under a reduced pressure of 10 kPa in a nitrogen atmosphere to dissolve the oligomer and form a uniform solution. Continue heating at the same temperature to cause depolymerization of the oligomer in the homogeneous solution phase, and co-distill the produced ethylene oxalate monomer and the solvent until almost stopped, and co-distill. The whole amount was collected in a receiver cooled with ice water. To the collected co-distillate, twice the amount of toluene as a non-solvent was added, and the mixture was allowed to cool to precipitate crystals of ethylene oxalate monomer. After allowing to cool, the precipitated crystals were separated by filtration. The crystals separated by filtration were saturated dissolved in acetonitrile at 40 to 50 ° C., and allowed to cool overnight in a refrigerator to recrystallize. After repeating recrystallization, it was separated by filtration and vacuum dried at about 40 ° C. to obtain a cyclic ethylene oxalate monomer (MOX-1A) by the homogeneous solution phase depolymerization method. The same method was repeated to obtain several batches of MOX-1A. Polymer synthesis As a monomer, ethylene oxalate monomer (MO
A polymer (POX-6) was obtained in the same manner as in Example 1 except that X-1A) was used. Table 1 shows the physical properties of the obtained polymer.

[Examples 7 to 8] Polymer (POX-7) was prepared in the same manner as in Examples 2 to 5 except that ethylene oxalate monomer (MOX-1A) and a small amount of glycolide were used as the monomers. ) And (POX-
8) was obtained. Table 1 collectively shows these comonomer compositions and the physical properties of the obtained copolymers.

Comparative Example 1 Preparation of Monomer In the step of preparing the monomer in Example 1, the purification of the crude ethylene oxalate oligomer with toluene was omitted and the oligomer was immediately dried at 150 ° C. under reduced pressure. Further, the addition of SnCl ₄ .nH ₂ O was also omitted, and the oligomer was decomposed and sublimated immediately using a glass tube oven to obtain a sublimation monomer (MOX-2). Purification by recrystallization of the sublimation monomer was omitted and the product was subjected to polymerization as it was (according to conventional method 1). Polymer Synthesis Example 1 except that the monomer (MOX-2) was used.
Polymerization was carried out in the same manner as in the polymer synthesis method in 1.
Table 1 shows the physical properties of the obtained polymer (CPOX-1).

Comparative Example 2 40.26 g of oxalic anhydride,
25 ml of ethylene glycol, 500 ml of benzene, and 1.52 g of p-toluenesulfonic acid were charged into a 1000-ml three-necked flask, and heated at a reflux temperature of benzene for 2.5 hours with stirring to obtain a condensate. This was washed with acetone and then dried at 80 ° C. to obtain an oligomer. 0.002 g of SnCl ₄ .2H ₂ O was added to 10 g of this oligomer, and the pressure was reduced to 0.5 to 1.0 Torr.
While flowing argon slowly, the mixture was heated at 180 ° C for 6 hours to carry out the transesterification reaction, and the polymer (CPO
X-2) was obtained (according to conventional method 2). Polymer (CPO
The physical properties of X-2) are shown in Table 1.

[0072]

[Table 1]

(Footnote) (* 1) A polymer was synthesized from an oligomer by a transesterification method. (* 2) The average weight loss rate is TGA, under nitrogen flow,
Melt processing temperature = [Tm + 10 ° C.] is the average weight loss rate in the initial 30 minutes when heated. (* 3) Density was based on the amorphous sheet density measuring method. (* 4) Classification; Group (I) is a polymer having less than 1 basic mol% of the copolymerization component, and Group (II) is a polymer having 1 basic mol% or more of the copolymerization component. Type (A) is a high crystallization rate crystalline type, type (B) is a low crystallization rate crystalline type, and type (C) is an amorphous type. (1) The amorphous sheet used for measuring each physical property was prepared by the method described in Example 9 below. (2) Regarding the disintegration property in soil, it was confirmed that the amorphous sheets of each polymer started to disintegrate in about 0.5 to 1 month. More specifically, in the winter, the amorphous sheet of each polymer was buried in soil for one month and then taken out. In each case, the decomposition mainly from the end into many small pieces was observed.
Even if there was a remaining sheet portion, it was white and brittle, and it was impossible to measure the mechanical strength.

Example 9 Amorphous Sheet The polymer (POX-1) obtained in Example 1 was preheated at a temperature of [polymer melting point + 20 ° C.] for about 15 minutes and then hot-pressed at 10 MPa for 15 seconds. Pressurized, immediately transferred to a cooling press and rapidly cooled to prepare a substantially non-oriented amorphous sheet (S-1) having a thickness of 0.2 mm, which was quickly put in a polyethylene bag and stored. The obtained sheet was colorless and had extremely high transparency. The physical properties of this amorphous sheet (S-1) are as follows. Thickness: 0.2 mm, density 1.52 g / cm ³ Tensile strength: 0.09 GPa Tensile modulus: 2.2 GPa Elongation: 11% It was obtained in Examples 2-8 and Comparative Examples 1-2. Polymers (POX-2) to (POX-8), and (CPOX
-1) to (CPOX-2) in the same manner as described above, and the respective non-oriented amorphous sheets (S-2) to (S-).
8) and (CS-1) to (CS-2) were prepared. However, the preheating temperature of POX-5 was 200 ° C. Each of the obtained amorphous sheets was colorless and had extremely high transparency.

[Example 10] Non-Oriented Crystallized Sheet The amorphous sheet (S-1) prepared in Example 9 was replaced with two PTs.
It is sandwiched between FE sheets, and a weight of about 1 KPa is placed on it.
Crystallization was performed by heat treatment at 15 ° C. for 15 minutes. As a result, a semi-transparent tough non-oriented crystallized sheet which was hard to break even when bent was obtained. The physical properties of this non-oriented crystallized sheet are as follows. Thickness: 0.2 mm Density: 1.56 g / cm ³ or more Tensile strength: 0.11 GPa Tensile elastic modulus: 2.6 GPa Elongation: 8% Heat shrinkage (110 ° C./10 minutes): <2% Example 9 Amorphous sheets (S-2) to (S-
8) and (CS-1) to (CS-2) were also heat-treated and crystallized by the same method as above. Amorphous sheets (S-2) to (S-4) and (S-6) to (S-8)
From the above, a semi-transparent and tough non-oriented crystallized sheet which was not easily broken even when bent was obtained. From the amorphous sheet (S-5),
A transparent non-oriented crystallized sheet that was not easily broken even when bent was obtained. However, the amorphous sheets (CS-1) and (CS-
From 2), a brittle non-oriented crystallized sheet that easily breaks when bent was obtained.

[Example 11] Uniaxially oriented film The amorphous sheets (S-1) and (S- prepared in Example 9 were used.
2), (S-5), (S-6), (S-8), (CS-
1) and (CS-2) are cut into strips each having a width of 10.0 mm, and each of them is stretched at a temperature of 45 to 50 ° C. in a uniaxial direction by 4.0 times. Fix with a frame, heat-fix for 2 minutes at 150 ° C,
A uniaxially stretched film was prepared. Amorphous sheet (S-1),
(S-2), (S-5), (S-6), and (S-8)
Although a uniaxially oriented film could be obtained from the above, the amorphous sheets (CS-1) and (CS-2) made of a polymer having a low molecular weight were broken during stretching. The physical properties of the obtained uniaxially oriented films are as shown in Table 2.

[0077]

[Table 2] (* 1) It was hard to shrink and it was difficult to measure. (* 2) The amorphous sheet broke during uniaxial stretching.

[Example 12] Biaxially oriented film The amorphous sheets (S-1) and (S- prepared in Example 9 were used.
2), (S-5), (S-6), (S-8), (CS-
1) and (CS-2) were each cut into 10 cm square pieces, and this was cut using a biaxial stretching machine [manufactured by Toyo Seiki Co., Ltd.].
Biaxially stretched at a draw ratio of 3.0 times in the longitudinal direction and 3.0 times in the lateral direction at 40 to 45 ° C., and the obtained stretched film is fixed with a metal frame and fixed at 150 ° C. for 2 minutes. Long heat treatment was performed to prepare a biaxially oriented film. Amorphous sheet (S-
1), (S-2), (S-5), (S-6), and (S
From (8), a biaxially oriented film could be obtained, but an amorphous sheet (CS-) made of a polymer having a low molecular weight was used.
1) and (CS-2) broke during stretching. The physical properties of the obtained biaxially oriented films are as shown in Table 3.

[0079]

[Table 3] (* 1) It was hard to shrink and it was difficult to measure. (* 2) The amorphous sheet broke during biaxial stretching. The biaxially stretched films made from the amorphous sheets (S-1) and (S-2) are easily heat-sealed by stacking two sheets and pressing and heating with an iron having a surface temperature of about 200 ° C. I was able to.

Example 13 Stretched Monofilament The amorphous sheets (S-1) and (S-) prepared in Example 9 were used.
2), (S-5), (S-6), (S-8), (CS-
Each of 1) and (CS-2) was cut into strips of about 0.5 cm and heated at 130 ° C./10 min for crystallization, and this was fitted with nozzles of D = 0.5 mm and L = 5 mm. Fill a capillograph [manufactured by Toyo Seiki Co., Ltd.],
Melt extrusion at 190 ° C., R ₁ (take-off speed / discharge speed) =
Each raw yarn was obtained by taking off with No. 5. However, amorphous sheets (CS-1) and (CS-2) made of a polymer having a low molecular weight
In the case of using, the drawdown during melt extrusion was so severe that the spinning could not be performed. 5 for each obtained yarn
It was stretched 4.0 times at 0 to 55 ° C. 5 at 150 ℃
Heat treatment was carried out by heat treatment for a fixed length of time. Physical properties of the stretched monofilament thus obtained are as shown in Table 4.

[0081]

[Table 4] (* 1) It was hard to shrink and it was difficult to measure. (* 2) Drawdown was severe during melt extrusion, and spinning was not possible.

Example 14 Injection Molded Polymers Polymers (POX-1), (POX-2), (POX-)
5), (POX-6) and (POX-8) are each heated at 130 ° C. to be crystallized, pulverized, and
It was dried under reduced pressure at 0 ° C. to obtain a crystallized powder. Each of the obtained crystallized powders was extruded into a strand at about 190 ° C. by an extruder, quenched, and cut into pellets.
The pellet was air-dried at 120 ° C. for 2 hours for crystallization. An injection molding machine equipped with a mold (cylinder temperature 200 ° C., injection holding pressure 0.1 GP)
a, mold temperature 30 ° C.) to produce a dumbbell-shaped injection molded product. This was annealed at 120 ° C. for 5 hours. The physical properties of the obtained injection molded products are as shown in Table 5. Bending strength and flexural modulus are both ASTM
It was measured at 23 ° C. according to D790.

[0083]

[Table 5]

[Example 15] Laminated paper The polymer (POX-2) obtained in Example 2 was used at 200 ° C.
After preheating for about 15 minutes at 10MP using a hot press
Pressing with a for 15 seconds, immediately transferring to a cooling press and quenching, a substantially non-oriented amorphous sheet of 0.1 mm thickness (S
2-1) was prepared. The obtained amorphous sheet was colorless and had extremely high transparency. Two sheets of this amorphous sheet (S-2-1) are used to sandwich both sides of the same type of base paper used in a milk carton, and both sides are P
It is sandwiched between TFE sheets and hot pressed at 200 ℃
Pressurize and heat with a polymer (POX-2) on both sides of the base paper.
Sheets were laminated. This was pressed at about 90 ° C. using a cooling press, held and crystallized. In this way, a glossy, water-resistant base paper laminated on both sides with polyethylene oxalate was obtained.

[0085]

According to the present invention, polyethylene oxalate having a high molecular weight and excellent in melt processability, heat resistance, crystal characteristics, mechanical characteristics and the like is provided. Further, according to the present invention, various molded products formed from high molecular weight polyethylene oxalate are provided. Further, according to the present invention, a novel method for producing high molecular weight polyethylene oxalate is provided. Since the high molecular weight polyethylene oxalate of the present invention has biodegradability, it is used in a wide range of fields including the food packaging field as a sheet, a film, a fiber, an injection molded product, a foam, etc., which has a low environmental load. can do.

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Claims (16)

(57) [Claims] 1. The following formula (1): A polyethylene oxalate containing 60 repeating mol% or more of the repeating unit represented by
-0.40 g / d in a mixed solvent of chlorophenol and 1,2,4-trichlorobenzene in a weight ratio of 4: 1
1, the solution viscosity (η _inh ) measured at a temperature of 30 ° C. is 0.25 dl / g or more, and (b) the melt viscosity (η ^* ) measured at a temperature of 190 ° C. and a shear rate of 1000 / sec is 30.
Pa · s or more, and (c) the density of the amorphous substance is 1.48 g /
Polyethylene oxalate characterized by having a size of not less than ³ cm ³ . 2. The polyethylene oxalate according to claim 1, which is a substantially homopolymer in which the proportion of the repeating unit represented by the formula (1) exceeds 99 basic mol%. 3. The repeating unit represented by the formula (1) is contained in a proportion of 60 to 99 basic mol%, and the repeating unit represented by the following formula (2): A repeating unit represented by the following formula (3): (Wherein n is an integer of 1 to 6), and a repeating unit represented by the following formula (4): The polyethylene according to claim 1, which is a copolymer containing at least one repeating unit selected from the group consisting of repeating units represented by (wherein m is an integer of 0 to 6) in a proportion of 1 to 40 basic mol%. Oxalate. 4. Further, (d) the melting point (Tm) is 130 ° C.
Above, (e) melting enthalpy (ΔHm) is 20 J / g
Above, and (f) melt crystallization enthalpy (ΔHmc)
The polyethylene oxalate according to any one of claims 1 to 3, having a physical property of 20 J / g or more. [However, the melting point (Tm) and the enthalpy of fusion (ΔHm) are
The melting point and melting enthalpy detected when a 0.2 mm thick amorphous sheet sample was heated at a rate of 10 ° C./min in an inert gas atmosphere using a differential scanning calorimeter. The enthalpy (ΔHmc) was 10 ° C immediately after the amorphous sheet sample reached 220 ° C due to temperature rise.
It is the melt crystallization enthalpy detected when the temperature is lowered at a rate of / min. ] 5. Further, (d) the melting point (Tm) is 130 ° C.
Above, (e) melting enthalpy (ΔHm) is 20 J / g
Above, and (g) Melt crystallization enthalpy (ΔHmc)
The polyethylene oxalate according to any one of claims 1 to 3, having a physical property of less than 20 J / g. 6. Further, (h) enthalpy of fusion (ΔH)
m) has a physical property of less than 20 J / g.
The polyethylene oxalate according to any one of 1. 7. The polyethylene oxalate according to any one of claims 1 to 3, which further has (i) a property of having a thermal decomposition rate of 0.5% by weight / minute or less. 8. A non-oriented sheet formed from the polyethylene oxalate according to claim 1, having a melting point (Tm) of 130 ° C. or higher, a density of 1.50 g / cm ³ or higher, and a tensile strength. A non-oriented sheet having a strength of 0.05 GPa or more, a tensile elastic modulus of 1.0 GPa or more, an elongation of 3% or more, and a heat shrinkage rate (110 ° C./10 minutes) of 30% or less. 9. A uniaxially oriented film formed from the polyethylene oxalate according to claim 1, which has a melting point (Tm) of 130 ° C. or higher, a density of 1.50 g / cm ³ or higher, and a tensile strength. Strength (orientation direction) 0.07 GPa or more, tensile modulus (orientation direction) 1.0 GPa or more, elongation (orientation direction) 3% or more, and heat shrinkage (110 ° C / 10 minutes) (orientation direction) 30% or less Is a uniaxially oriented film. 10. A biaxially oriented film formed from the polyethylene oxalate according to claim 1, having a melting point (Tm) of 130 ° C. or higher, a density of 1.50 g / cm ³ or higher, A biaxially oriented film having a tensile strength of 0.07 GPa or more, a tensile elastic modulus of 1.0 GPa or more, an elongation of 3% or more, and a heat shrinkage rate (110 ° C./10 minutes) of 30% or less. 11. A fiber formed from the polyethylene oxalate according to claim 1, which has a melting point (Tm) of 130 ° C. or higher, a density of 1.50 g / cm ³ or higher, and a tensile strength of 0. A fiber having a tensile elastic modulus of 3.0 GPa or more, a tensile elongation of 3% or more, and a heat shrinkage rate (110 ° C./10 minutes) of 40% or less. 12. An injection-molded article formed from the polyethylene oxalate according to claim 1, which has a melting point (Tm) of 130 ° C. or more, a bending strength of 0.01 GPa or more, and a bending elasticity. An injection-molded article having a rate of 1.0 GPa or more. 13. A method for producing polyethylene oxalate in which a cyclic ethylene oxalate monomer obtained by depolymerizing an ethylene oxalate oligomer is heated in an inert gas atmosphere to perform ring-opening polymerization. , (I) the ethylene oxalate oligomer is washed with an organic solvent for purification, and then (i)
i) sublimate the produced monomer by heating the oligomer under reduced pressure to depolymerize, and then (iii)
A method for producing polyethylene oxalate, which comprises using a monomer purified by recrystallization of a monomer obtained by sublimation in an organic solvent. 14. A method for producing polyethylene oxalate in which a cyclic ethylene oxalate monomer obtained by depolymerizing an ethylene oxalate oligomer is heated in an inert gas atmosphere to perform ring-opening polymerization, , (I) a mixture containing an ethylene oxalate oligomer and a high boiling point polar organic solvent,
Under normal pressure or under reduced pressure, it is heated to a temperature at which depolymerization of the oligomer occurs, the oligomer is dissolved in the polar organic solvent, and (II) further heating is continued to depolymerize the oligomer in the solution phase. Thereby, the produced monomer is distilled out together with the polar organic solvent, and then the monomer recovered from the distillate (III) is used. 15. The cyclic ethylene oxalate monomer, and at least one selected from the group consisting of lactide, glycolide, lactone (having 7 or less carbon atoms), and alkylene oxalate (having 3 to 9 carbon atoms in the alkylene group). The ring-opening copolymerization of the cyclic monomer of 1.
3. The manufacturing method according to 3 or 14. 16. A compound of formula (1): A repeating unit represented by the following formula (2) A repeating unit represented by the following formula (3): (However, n is an integer of 1 to 6) and a repeating unit represented by the following formula (4): (However, m is an integer of 0 to 6) A copolymer containing at least one repeating unit selected from the group consisting of repeating units represented by 1 to 40 basic mol% is produced. Production method.