JP7460007B2 - polyester resin composition - Google Patents

Description

The present invention relates to a biomass polyester resin composition obtained from plant-derived raw materials, and more particularly to a resin composition containing a polyester using biomass-derived ethylene glycol as a diol component.

Polyester has excellent mechanical properties, chemical stability, heat resistance, transparency, etc., and is inexpensive, so it is widely used in various industrial applications. Polyester is obtained by polycondensing diol units and dicarboxylic acid units. For example, polyethylene terephthalate (hereinafter sometimes abbreviated as PET) is obtained by esterifying ethylene glycol and terephthalic acid as raw materials. After that, it is produced by polycondensation reaction. These raw materials are produced from petroleum, which is a fossil resource; for example, ethylene glycol is industrially produced from ethylene, and terephthalic acid is industrially produced from xylene.

In recent years, as calls for the creation of a recycling-oriented society grow, there is a desire to move away from fossil fuels in the materials field, just as there is in the energy field, and the use of biomass has attracted attention. Biomass is an organic compound produced by photosynthesis from carbon dioxide and water, and by using it, it becomes carbon dioxide and water again, making it a so-called carbon-neutral renewable energy. Recently, the practical application of biomass plastics made from these biomass raw materials has progressed rapidly, and there are also attempts to produce polyester, a general-purpose polymer material, from these biomass raw materials.

For example, as a polyester using a biomass raw material, a polyester consisting of isosorbide, which is one of the biomass raw materials, terephthalic acid, and ethylene glycol has been proposed (Patent Document 1).

In addition, biomass ethanol obtained by fermenting starch and sugars obtained from plants such as corn and sugarcane with microorganisms has been put into practical use, and it is possible to industrially produce ethylene glycol from this biomass ethanol via ethylene. It has also been successful.

Special Publication No. 2002-512304

The present inventors focused on ethylene glycol, a raw material for polyester, and discovered that polyester made from plant-derived ethylene glycol instead of conventional ethylene glycol obtained from fossil fuels has physical properties, such as mechanical properties, comparable to polyester made from conventional ethylene glycol obtained from fossil fuels. The present invention is based on this discovery.

Therefore, the object of the present invention is to provide a method for producing a film made of a resin composition containing a carbon-neutral polyester made from biomass ethylene glycol, and to provide a method for producing a biaxially stretched resin film that can produce a film that is comparable in physical properties, such as mechanical properties, to films produced from raw materials obtained from conventional fossil fuels.

The method for producing a biaxially stretched film according to the present invention is a method for producing a biaxially stretched resin film made of a resin composition containing, as a main component, a polyester composed of a diol unit and a dicarboxylic acid unit, comprising the steps of:
The resin composition contains 50 to 90% by mass of a biomass-derived polyester in which a diol unit is ethylene glycol derived from biomass and a dicarboxylic acid unit is terephthalic acid derived from a fossil fuel;
The manufacturing method includes a step of biaxially stretching the resin composition containing the biomass-derived polyester,
In the method for producing a biaxially stretched resin film, the biaxially stretching step is a step of stretching in the longitudinal direction and then stretching in the transverse direction.
In a preferred embodiment of the present invention, the resin composition contains 5 to 45% by mass of recycled polyester based on the total mass of the resin composition.
In one embodiment of the present invention, the biaxially stretched resin film preferably has a breaking strength of 5 to 40 kgf/mm ² in the MD direction and 5 to 35 kgf/mm ² in the TD direction.
In one embodiment of the present invention, the biaxially stretched resin film preferably has a breaking elongation of 50 to 350% in the MD direction and 50 to 300% in the TD direction.
In an embodiment of the present invention, the biaxially stretched resin film is preferably stretched longitudinally at a ratio of 2.5 to 4.2 times, and transversely at a ratio of 2.5 to 5.0 times.
In an aspect of the present invention, the content of biomass-derived carbon in the resin composition as determined by radiocarbon (C14) measurement is preferably 10 to 19% relative to the total carbon in the resin composition.
In an embodiment of the present invention, the biaxially stretched resin film preferably has a thickness of 5 to 12.13 μm.

According to the present invention, the resin composition contains a polyester whose diol component unit is biomass-derived ethylene glycol and whose dicarboxylic acid component unit is petroleum-derived dicarboxylic acid, making it possible to produce a carbon-neutral film. Furthermore, the film that can be produced by the present invention is comparable in physical properties, such as mechanical properties, to polyester films produced from conventional raw materials derived from fossil fuels, and can replace conventional polyester films.

The resin composition according to the present invention contains 50 to 90 parts by mass of biomass polyester having ethylene glycol derived from biomass as a diol unit, and 5 to 45% by mass of so-called recycled polyester as the main component. By making the resin composition contain 50 to 90% by mass of such polyester containing biomass-derived diol units, a carbon-neutral polyester resin can be realized. In addition, since the resin composition contains 5 to 45% by mass of recycled polyester as a component other than the biomass-derived polyester, the film formation stability during film formation is improved and a resin composition with low environmental impact can be realized. In addition, since biomass-derived ethylene glycol has the same chemical structure as conventional fossil fuel-derived ethylene glycol, polyester using biomass-derived ethylene glycol is no different from polyester polymerized from conventional fossil fuel-derived raw materials, and therefore, a film made from the resin composition of the present invention is comparable to conventional polyester films in terms of physical properties such as mechanical properties. The polyester contained in the resin composition will be described below.

<Polyester>
The polyester contained in the resin composition according to the present invention in an amount of 50 to 90 mass % (hereinafter also referred to as biomass-derived polyester) is composed of diol units and dicarboxylic acid units, and is obtained by a polycondensation reaction using ethylene glycol derived from biomass as the diol units and dicarboxylic acid derived from fossil fuels as the dicarboxylic acid units.

The biomass-derived ethylene glycol used in the biomass-derived polyester is made from ethanol (biomass ethanol) produced from biomass as a raw material. For example, biomass-derived ethylene glycol can be obtained by a method of producing ethylene glycol from biomass ethanol via ethylene oxide using a conventionally known method. Commercially available biomass ethylene glycol may also be used, and for example, biomass ethylene glycol available from India Glycoal Limited can be suitably used.

As the dicarboxylic acid used in the biomass polyester, a dicarboxylic acid derived from a fossil fuel is used. As the dicarboxylic acid, aromatic dicarboxylic acids, aliphatic dicarboxylic acids, and derivatives thereof can be used without restrictions. Examples of aromatic dicarboxylic acids include terephthalic acid and isophthalic acid, and examples of derivatives of aromatic dicarboxylic acids include lower alkyl esters of aromatic dicarboxylic acids, specifically methyl esters, ethyl esters, propyl esters, and butyl esters. Among these, terephthalic acid is preferred, and as a derivative of aromatic dicarboxylic acid, dimethyl terephthalate is preferred.

Examples of aliphatic dicarboxylic acids include oxalic acid, succinic acid, glutaric acid, adipic acid, sebacic acid, dodecanedioic acid, dimer acid, and cyclohexanedicarboxylic acid, which usually have 2 to 40 carbon atoms. chain or alicyclic dicarboxylic acids. Further, as derivatives of aliphatic dicarboxylic acids, lower alkyl esters such as methyl ester, ethyl ester, propyl ester, and butyl ester of the above aliphatic dicarboxylic acids, and cyclic acid anhydrides of the above aliphatic dicarboxylic acids such as succinic anhydride may be used. Can be mentioned. Among these, adipic acid, succinic acid, dimer acid, or mixtures thereof are preferred, and those containing succinic acid as a main component are particularly preferred. As the aliphatic dicarboxylic acid derivative, methyl esters of adipic acid and succinic acid, or mixtures thereof are more preferred.

These dicarboxylic acids can be used alone or in combination of two or more.

The polyester contained in the resin composition according to the present invention may be a copolymerized polyester in which a copolymer component is added as a third component in addition to the diol component and dicarboxylic acid component described above. Specific examples of copolymerization components include bifunctional oxycarboxylic acids, trifunctional or more polyhydric alcohols, trifunctional or more polycarboxylic acids and/or their anhydrides, and trifunctional or more functional polyhydric alcohols to form a crosslinked structure. At least one type of polyfunctional compound selected from the group consisting of oxycarboxylic acids having higher than functional functions is mentioned. Among these copolymerization components, bifunctional and/or trifunctional or higher functional oxycarboxylic acids are particularly preferably used because copolymerized polyesters with a high degree of polymerization tend to be easily produced. Among these, the use of trifunctional or higher functional oxycarboxylic acids is most preferable because polyester with a high degree of polymerization can be easily produced in a very small amount without using a chain extender described later.

Moreover, the above-mentioned polyester may be a high molecular weight polyester obtained by chain extension (coupling) of these copolymerized polyesters. As a chain extender, a chain extender such as a carbonate compound or a diisocyanate compound can also be used, but the amount is usually such that carbonate bonds and urethane bonds are It is usually 10 mol% or less, preferably 5 mol% or less, more preferably 3 mol% or less.

Specific examples of carbonate compounds include diphenyl carbonate, ditolyl carbonate, bis(chlorophenyl) carbonate, m-cresyl carbonate, dinaphthyl carbonate, dimethyl carbonate, diethyl carbonate, dibutyl carbonate, ethylene carbonate, diamyl carbonate, dicyclohexyl carbonate, etc. In addition, carbonate compounds consisting of the same or different hydroxy compounds derived from hydroxy compounds such as phenols and alcohols can be used.

Specific examples of diisocyanate compounds include known diisocyanates such as 2,4-tolylene diisocyanate, a mixture of 2,4-tolylene diisocyanate and 2,6-tolylene diisocyanate, diphenylmethane diisocyanate, 1,5-naphthylene diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, hexamethylene diisocyanate, and isophorone diisocyanate.

The polyester used in the present invention can be obtained by a conventionally known method of polycondensing the above-mentioned diol unit and dicarboxylic acid unit. Specifically, it can be produced by a general melt polymerization method in which an esterification reaction and/or an ester exchange reaction between the above-mentioned dicarboxylic acid component and diol component is carried out, followed by a polycondensation reaction under reduced pressure, or by a known solution heating dehydration condensation method using an organic solvent.

The amount of diol used when producing polyester is substantially equimolar to 100 moles of dicarboxylic acid or its derivative, but generally, it is used during esterification and/or transesterification reaction and/or polycondensation reaction. Since there is distillation of

Further, the polycondensation reaction is preferably carried out in the presence of a polymerization catalyst. The timing of adding the polymerization catalyst is not particularly limited as long as it is before the polycondensation reaction, and it may be added at the time of charging the raw materials or at the start of pressure reduction.

Examples of the polymerization catalyst generally include compounds containing metal elements from Groups 1 to 14 of the periodic table, excluding hydrogen and carbon. Specifically, at least one metal selected from the group consisting of titanium, zirconium, tin, antimony, cerium, germanium, zinc, cobalt, manganese, iron, aluminum, magnesium, calcium, strontium, sodium, and potassium. Compounds containing organic groups, such as carboxylates, alkoxy salts, organic sulfonates, or β-diketonate salts, as well as inorganic compounds such as the metal oxides and halides mentioned above, and mixtures thereof. Among these, metal compounds containing titanium, zirconium, germanium, zinc, aluminum, magnesium, and calcium, and mixtures thereof are preferred, and titanium compounds, zirconium compounds, and germanium compounds are particularly preferred. Furthermore, since the polymerization rate increases when the catalyst is in a molten or dissolved state during polymerization, it is preferably a compound that is liquid during polymerization or dissolves in the ester low polymer or polyester.

As the titanium compound, tetraalkyl titanates are preferred, specifically tetra-n-propyl titanate, tetraisopropyl titanate, tetra-n-butyl titanate, tetra-t-butyl titanate, tetraphenyl titanate, tetracyclohexyl titanate, tetrabenzyl titanate, and mixed titanates thereof. In addition, titanium (oxy) acetylacetonate, titanium tetraacetylacetonate, titanium (diisopropoxide) acetylacetonate, titanium bis(ammonium lactate) dihydroxide, titanium bis(ethylacetoacetate) diisopropoxide, titanium (triethanolamine) isopropoxide, polyhydroxytitanium stearate, titanium lactate, titanium triethanolamine, butyl titanate dimer, etc. are also preferably used. Furthermore, titanium oxide and composite oxides containing titanium and silicon are also preferably used. Among these, tetra-n-propyl titanate, tetraisopropyl titanate, tetra-n-butyl titanate, titanium (oxy) acetylacetonate, titanium tetraacetylacetonate, titanium bis(ammonium lactate) dihydroxide, polyhydroxytitanium stearate, titanium lactate, butyl titanate dimer, titanium oxide, titania/silica composite oxide (e.g., product name: C-94 manufactured by Acordis Industrial Fibers) are preferred, and tetra-n-butyl titanate, polyhydroxytitanium stearate, titanium (oxy) acetylacetonate, titanium tetraacetylacetonate, titania/silica composite oxide (e.g., product name: C-94 manufactured by Acordis Industrial Fibers) are particularly preferred.

Specific examples of zirconium compounds include zirconium tetraacetate, zirconium acetate hydroxide, zirconium tris(butoxy)stearate, zirconyl diacetate, zirconium oxalate, zirconyl oxalate, zirconium potassium oxalate, and polyhydroxyzirconium. Mention may be made of stearate, zirconium ethoxide, zirconium tetra-n-propoxide, zirconium tetraisopropoxide, zirconium tetra-n-butoxide, zirconium tetra-t-butoxide, zirconium tributoxyacetylacetonate and mixtures thereof. Furthermore, zirconium oxide or a composite oxide containing zirconium and silicon, for example, may be used. Among these, zirconyl diacetate, zirconium tris(butoxy) stearate, zirconium tetraacetate, zirconium acetate hydroxide, zirconium ammonium oxalate, zirconium potassium oxalate, polyhydroxyzirconium stearate, zirconium tetra-n-propoxy Preferred are zirconium tetraisopropoxide, zirconium tetra-n-butoxide, and zirconium tetra-t-butoxide.

Specific examples of germanium compounds include inorganic germanium compounds such as germanium oxide and germanium chloride, and organic germanium compounds such as tetraalkoxygermanium. In terms of price and availability, germanium oxide, tetraethoxygermanium, tetrabutoxygermanium, and the like are preferred, and germanium oxide is particularly preferred.

When using metal compounds as polymerization catalysts, the amount of catalyst used is usually 5 ppm or more, preferably 10 ppm or more, and the upper limit is usually 30,000 ppm or less, preferably 1,000 ppm or less, more preferably 250 ppm or less, and particularly preferably 130 ppm or less, in terms of the amount of metal relative to the polyester produced. If too much catalyst is used, not only is it economically disadvantageous but the thermal stability of the polymer is also reduced, whereas if too little is used, the polymerization activity is reduced, and as a result, decomposition of the polymer is more likely to be induced during the polymer production. As for the amount of catalyst used here, the method of reducing the amount of catalyst used is a preferred embodiment, since the amount of terminal carboxyl groups in the polyester produced is reduced as the amount of catalyst used is reduced.

The reaction temperature of the esterification reaction and/or transesterification reaction between the dicarboxylic acid component and the diol component is usually in the range of 150 to 260°C, and the reaction atmosphere is usually an inert gas atmosphere such as nitrogen or argon. . Further, the reaction pressure is usually normal pressure to 10 kPa. Further, the reaction time is usually about 1 hour to 10 hours.

In the above-mentioned manufacturing process, a chain extender (coupling agent) may be added to the reaction system. After the polycondensation is completed, the chain extender is added to the reaction system in a homogeneous molten state without a solvent, and reacted with the polyester obtained by polycondensation.

High molecular weight polyesters using these chain extenders (coupling agents) can be produced using known techniques. After the completion of polycondensation, the chain extender is added to the reaction system in a uniform molten state without a solvent, and reacted with the polyester obtained by polycondensation. Specifically, a polyester obtained by catalytically reacting a diol and a dicarboxylic acid, whose terminal group substantially has a hydroxyl group, and whose mass average molecular weight (Mw) is 20,000 or more, preferably 40,000 or more. By reacting the prepolymer with the chain extender, a polyester resin having a higher molecular weight can be obtained. If the prepolymer has a mass average molecular weight of 20,000 or more, it can be used even under severe conditions such as in a molten state by using a small amount of coupling agent, and will not be affected by residual catalyst, so it will not form a gel during the reaction. , high molecular weight polyesters can be produced.

After the obtained polyester is solidified, it may be subjected to solid phase polymerization, if necessary, in order to further increase the degree of polymerization or to remove oligomers such as cyclic trimers. Specifically, after polyester is chipped and dried, the polyester is pre-crystallized by heating at a temperature of 100 to 180°C for about 1 to 8 hours, and then inert at a temperature of 190 to 230°C. This is carried out by heating for 1 to several tens of hours under gas flow or reduced pressure.

The intrinsic viscosity of the polyester obtained as described above (measured in orthochlorophenol solution at 35°C) is preferably 0.5 dl/g to 1.5 dl/g, more preferably 0.6 dl/g to 1.2 dl/g. If the intrinsic viscosity is less than 0.5 dl/g, the mechanical properties required of the polyester film as a semi-transparent reflective film substrate, including tear strength, may be insufficient. On the other hand, if the intrinsic viscosity exceeds 1.5 dl/g, productivity is impaired in the raw material production process and the film production process.

Various additives may be added in the polyester manufacturing process or to the manufactured polyester as long as its properties are not impaired, such as plasticizers, ultraviolet stabilizers, color inhibitors, matting agents, etc. , a deodorant, a flame retardant, a weathering agent, an antistatic agent, a yarn friction reducing agent, a mold release agent, an antioxidant, an ion exchange agent, a coloring pigment, etc. can be added. These additives are added in an amount of 5 to 20% by mass based on the entire polyester resin composition.

The polyester (hereinafter also referred to as recycled polyester) contained in the resin composition according to the present invention in a proportion of 5 to 45% by mass is composed of diol units and dicarboxylic acid units, and the diol units are fossil fuel-derived diols. Alternatively, it is a polyester obtained by recycling a product made of a polyester resin obtained by a polycondensation reaction using biomass-derived ethylene glycol and a fossil fuel-derived dicarboxylic acid as a dicarboxylic acid unit.

Even if the diol unit and dicarboxylic acid unit are both made from fossil fuel-derived raw materials, the resin that is the source of recycled polyester (that is, the polyester resin before recycling) is not biomass polyester as described above. Good too.

Fossil fuel-derived diols used in the resin that is the basis of recycled polyester include aliphatic diols, aromatic diols, and derivatives thereof, and those used as diol units of conventional polyesters are preferably used. be able to. The aliphatic diol is not particularly limited as long as it is an aliphatic or alicyclic compound having two OH groups, but the lower limit of the number of carbon atoms is 2 or more, and the upper limit is usually 10 or less, preferably 6. The following aliphatic diols may be mentioned. Specific examples include ethylene glycol, 1,3-propylene glycol, neopentyl glycol, 1,6-hexamethylene glycol, decamethylene glycol, 1,4-butanediol, and 1,4-cyclohexanedimethanol. It will be done. These may be used alone or as a mixture of two or more. Among these, ethylene glycol, 1,4-butanediol, 1,3-propylene glycol and 1,4-cyclohexanedimethanol are preferred, and ethylene glycol is particularly preferred.

The resin composition containing the polyester obtained as described above preferably contains 10 to 18% of biomass-derived carbon based on the total carbon in the polyester as determined by radiocarbon (C14) measurement. Since carbon dioxide in the atmosphere contains C14 at a certain rate (105.5 pMC), the C14 content in plants that grow by taking in atmospheric carbon dioxide, such as corn, is also around 105.5 pMC. It is known. It is also known that fossil fuels contain almost no C14. Therefore, by measuring the proportion of C14 contained in all carbon atoms in polyester, the proportion of carbon derived from biomass can be calculated. In the present invention, the biomass-derived carbon content P _bio is defined as follows, where the C14 content in the polyester is P _C14 .
P _bio (%) = P _C14 /105.5×100

Taking polyethylene terephthalate as an example, polyethylene terephthalate is a polymerization of ethylene glycol containing 2 carbon atoms and terephthalic acid containing 8 carbon atoms in a molar ratio of 1:1, so only biomass-derived ethylene glycol can be used. When P bio is used, the biomass-derived carbon content P _bio in the polyester is 20%. In the present invention, the content of biomass-derived carbon as determined by radiocarbon (C14) measurement is preferably 10 to 19% based on the total carbon in the resin composition. If the biomass-derived carbon content in the resin composition is less than 10%, the effect as a carbon offset material will be poor. On the other hand, as mentioned above, the biomass-derived carbon content in the resin composition is preferably close to 20%, but due to problems in the film manufacturing process and physical properties, the resin may contain recycled polyester or Since it is preferable to include additives, the actual upper limit is 18%.

<Resin film>
The resin film according to the present invention is made of the above-mentioned resin composition. To process the resin composition into a film, a method for forming a film from a conventional polyester resin can be adopted. Specifically, after drying the above-mentioned resin composition, the resin composition is supplied to a melt extruder heated to a temperature (Tm) to Tm+70° C. above the melting point of the polyester, melted, extruded into a sheet from a die such as a T-die, and the extruded sheet is quenched and solidified by a rotating cooling drum or the like to form a film. As the melt extruder, a single screw extruder, a twin screw extruder, a vent extruder, a tandem extruder, or the like can be used according to the purpose.

The resin film according to the present invention is preferably biaxially stretched. Biaxial stretching can be performed by a conventionally known method. For example, the film extruded onto a cooling drum as described above is then heated by roll heating, infrared heating, etc., and stretched in the longitudinal direction to form a longitudinally stretched film. This stretching is preferably carried out using the difference in circumferential speed between two or more rolls. Longitudinal stretching is usually carried out at a temperature range of 50 to 100°C. Further, the longitudinal stretching ratio is preferably 2.5 times or more and 4.2 times or less, although it depends on the required characteristics of the film application. When the stretching ratio is less than 2.5 times, the thickness unevenness of the polyester film becomes large and it is difficult to obtain a good film.

The longitudinally stretched film is then subjected to the sequential processing steps of transverse stretching, heat setting, and heat relaxation to become a biaxially stretched film. Transverse stretching is usually performed at a temperature range of 50 to 100°C. The transverse stretching ratio is preferably 2.5 to 5.0 times, depending on the required characteristics of the application. If it is less than 2.5 times, the film thickness will become uneven and it will be difficult to obtain a good film, and if it exceeds 5.0 times, breakage will occur easily during film production.

After the transverse stretching, a heat setting process is carried out. The preferred temperature range for heat setting is Tg+70 to Tm-10°C of the polyester. The heat setting time is preferably 1 to 60 seconds. For applications requiring a reduction in the thermal shrinkage rate, a heat relaxation process may be carried out as necessary.

The thickness of the stretched resin film obtained as described above is optional depending on the application, but is usually about 5 to 500 μm. The breaking strength of such a resin film is 5 to 40 kgf/mm ² in the MD direction and 5 to 35 kgf/mm ² in the TD direction, and the breaking elongation is 50 to 350% in the MD direction and 50 to 300% in the TD direction. In addition, the shrinkage rate when left in a temperature environment of 150° C. for 30 minutes is 0.1 to 5%. Thus, the film made of the resin composition according to the present invention has physical properties equivalent to those of a polyester film produced only from conventional materials derived from fossil fuels.

The formed biaxially stretched film has surface functions such as chemical functions, electrical functions, magnetic functions, mechanical functions, friction/wear/lubrication functions, optical functions, thermal functions, and biocompatibility. It is also possible to perform secondary processing for the purpose of imparting. Examples of secondary processing include embossing, painting, adhesion, printing, metallization (plating, etc.), machining, surface treatment (antistatic treatment, corona discharge treatment, plasma treatment, photochromism treatment, physical vapor deposition, chemical vapor deposition, coating, etc.).

The resin film according to the present invention can be suitably used for packaging products, various label materials, lid materials, sheet molded products, laminated tubes, and the like.

Other aspects The present invention provides a resin composition containing a carbon-neutral polyester using biomass ethylene glycol, which has physical properties such as mechanical properties and polyester produced from raw materials obtained from conventional fossil fuels. Another object of the present invention is to provide a biomass-derived resin composition from which a polyester comparable in terms of quality can be obtained.
A resin composition according to yet another aspect of the present invention is a resin composition comprising a polyester comprising a diol unit and a dicarboxylic acid unit,
A polyester in which the diol unit is ethylene glycol derived from biomass and the dicarboxylic acid unit is a dicarboxylic acid derived from fossil fuel is used in an amount of 50 to 90% by mass based on the entire resin composition, and the diol unit is a diol derived from fossil fuel or biomass. 5 to 45% by mass of the polyester obtained by recycling a polyester whose dicarboxylic acid unit is a fossil fuel-derived dicarboxylic acid, based on the total resin composition.
It is characterized by comprising.
In yet another aspect of the present invention, the fossil fuel-derived dicarboxylic acid is preferably terephthalic acid.
In yet another aspect of the present invention, the fossil fuel-derived diol is preferably ethylene glycol.
In yet another embodiment of the present invention, it is preferable that the composition further contains an additive.
In yet another embodiment of the present invention, it is preferable that the additive is contained in an amount of 5 to 20% by mass based on the entire resin composition.
In still another aspect of the present invention, the additives include a plasticizer, an ultraviolet stabilizer, an anti-coloring agent, a matting agent, a deodorant, a flame retardant, a weathering agent, an antistatic agent, and a yarn friction reducing agent. , a mold release agent, an antioxidant, an ion exchange agent, and a colored pigment.
In yet another aspect of the present invention, the content of biomass-derived carbon as measured by radiocarbon (C14) is preferably 10 to 18% based on the total carbon in the polyester.
According to yet another aspect of the present invention, a resin film made of the above resin composition is also provided.
According to still another aspect of the present invention, a polyester in which the diol component unit is biomass-derived ethylene glycol and the dicarboxylic acid component unit is a petroleum-derived dicarboxylic acid is added throughout the resin composition. It contains 50 to 90% by mass of carbon, making it possible to realize a carbon-neutral polyester resin. Furthermore, the film made of the resin composition of the present invention is comparable in physical properties such as mechanical properties to polyester films manufactured from conventional raw materials obtained from fossil fuels, and can replace conventional polyester films. .

A method for producing a biaxially stretched resin film according to another aspect of the present invention is a method for producing a biaxially stretched resin film made of a resin composition containing, as a main component, a polyester composed of a diol unit and a dicarboxylic acid unit, comprising the steps of:
The resin composition comprises:
a biomass-derived polyester, the diol unit of which is ethylene glycol derived from biomass and the dicarboxylic acid unit of which is terephthalic acid derived from fossil fuels;
and recycled polyester obtained by recycling a product made of a polyester resin obtained by a polycondensation reaction using a diol unit in which the diol unit is a diol derived from a fossil fuel or ethylene glycol derived from biomass, and a dicarboxylic acid unit in which terephthalic acid derived from a fossil fuel is used,
The manufacturing method comprises:
a step of polymerizing the biomass-derived ethylene glycol and the fossil fuel-derived terephthalic acid to obtain a polymer, and solid-state polymerizing the polymer to prepare the biomass-derived polyester having an intrinsic viscosity of 0.5 dl/g to 0.8 dl/g;
The method is characterized by including a step of biaxially stretching the resin composition containing the biomass-derived polyester and the recycled polyester.
In another aspect of the present invention, the resin composition preferably contains the biomass-derived polyester in an amount of 50 mass % or more based on the entire resin composition.
In another aspect of the present invention, the resin composition preferably contains the biomass-derived polyester in an amount of 50 to 90 mass % based on the total mass of the resin composition.
In another aspect of the present invention, the resin composition preferably contains the recycled polyester in an amount of 5 to 45% by mass based on the total mass of the resin composition.
In another aspect of the present invention, the biaxially stretched resin film preferably has a breaking strength of 5 to 40 kgf/mm ² in the MD direction and 5 to 35 kgf/mm ² in the TD direction.
In another aspect of the present invention, the breaking elongation of the biaxially stretched resin film is preferably 50 to 350% in the MD direction and 50 to 300% in the TD direction.
In another embodiment of the present invention, the biaxially stretched resin film is preferably stretched longitudinally at a stretching ratio of 2.5 to 4.2 times, and transversely at a stretching ratio of 2.5 to 5.0 times.
In another aspect of the present invention, the content of biomass-derived carbon in the resin composition as determined by radiocarbon (C14) measurement is preferably 10 to 19% relative to the total carbon in the resin composition.
In another aspect of the present invention, the biaxially stretched resin film preferably has a thickness of 5 to 12.13 μm.

The present invention will be described below based on Examples, but the present invention is not limited thereto.

Example 1
<Synthesis of polyester derived from biomass>
83 parts by mass of terephthalic acid and 62 parts by mass of biomass ethylene glycol (manufactured by India Glycol) were fed as a slurry to a reaction vessel, and an esterification reaction was carried out at 240°C for 5 hours by a conventional direct polymerization method. Then, 0.013 parts by mass of trimethyl phosphate (manufactured by Aldrich) was added (15 mmol% relative to the acid component), and then the polymerization reaction was transferred to a high-temperature vacuum condition. First, the vacuum degree was raised to 4000 Pa and the polymerization temperature to 280°C in 40 minutes, and then the vacuum degree was lowered to 200 Pa while maintaining the polymerization temperature at 280°C to carry out a melt polymerization reaction. The reaction time was 3 hours. The synthesized polymer was discharged in the form of a strand into running water and pelletized by a pelletizer. The pellets were dried at 160°C for 5 hours, and then solid-phase polymerized at 205°C under a nitrogen atmosphere and a vacuum of 50 Pa to obtain a polymer with an intrinsic viscosity of 0.8 dl/g. The intrinsic viscosity was calculated from the melt viscosity measured at 35°C using a phenol/tetrachloroethane (component ratio: 3/2) solvent. Differential thermal analysis of the obtained polymer (apparatus: Shimadzu DSC-60, measurement conditions: in helium gas, heating at 6°C/min) showed a glass transition temperature of 69°C, which was equivalent to that of known polyethylene terephthalate obtained from raw materials derived from fossil fuels. Radiocarbon measurement of the obtained biomass-derived polyethylene terephthalate was also performed, and the content of biomass-derived carbon was found to be 16% by radiocarbon (C14) measurement.

<Film Preparation>
90 parts by mass of the polyethylene terephthalate pellets obtained as above and 10 parts by mass of a fossil fuel-derived polyethylene terephthalate master batch containing 200 ppm of porous silica with an average particle size of 0.9 μm as a lubricant were dried and then fed into an extruder, melted at 285 ° C., extruded into a sheet shape from a T-die, and cooled and solidified by a cooling roll to obtain an unstretched sheet. Next, this unstretched sheet was stretched at a ratio of 3.5 times in the longitudinal direction with a low-speed driving roll speed of 6.5 m / min and a high-speed driving roll speed of 22 m / min, and further stretched at a ratio of 3.5 times in the transverse direction by a tenter to obtain a biaxially stretched polyester film 1 having a thickness of 12.02 μm.

Example 2
60 parts by mass of the polyethylene terephthalate obtained in Example 1, 30 parts by mass of recycled PET (re-pelletized from lost parts in the manufacturing process such as edge loss during film formation), and the polyethylene terephthalate masterbatch used above. After drying 10 parts by mass, it was supplied to an extruder, melted at 285°C, extruded into a sheet from a T-die, and cooled and solidified using a cooling roll to obtain an unstretched sheet. Next, this unstretched sheet was stretched in the longitudinal direction at a magnification of 3.5 times with the speed of the low speed drive roll being 6.5 m/min and the speed of the high speed drive roll being 22 m/min, and further, using a tenter. A biaxially stretched polyester film 2 having a thickness of 12.13 μm was obtained by stretching in the transverse direction at a magnification of 3.5 times.

Comparative Example 1
60 parts by mass of polyethylene terephthalate (intrinsic viscosity 0.83 dl/g) produced from conventional raw materials derived from fossil fuels, 30 parts by mass of recycled PET (repelletized parts of loss during the production process such as edge loss during film formation), and 10 parts by mass of the polyethylene terephthalate master batch used above were dried and then fed into an extruder, melted at 285°C, extruded into a sheet shape from a T-die, and cooled and solidified by a cooling roll to obtain an unstretched sheet. Next, this unstretched sheet was stretched at a ratio of 3.5 times in the longitudinal direction with a low-speed driving roll speed of 6.5 m/min and a high-speed driving roll speed of 22 m/min, and further stretched at a ratio of 3.5 times in the transverse direction by a tenter to obtain a biaxially stretched polyester film 3 having a thickness of 12.06 μm.

<Radiation carbon measurement>
When the obtained film 1 was subjected to radiation carbon measurement, the content of biomass-derived carbon was 14% as determined by radiocarbon (C14) measurement. Furthermore, when films 2 and 3 were similarly subjected to radiation carbon measurement, the biomass-derived carbon content was 10% and 0%, respectively.

<Film evaluation>
Each of the obtained films was cut into a test piece with a width of 15 mm and a length of 200 mm from each of the MD direction (winding direction) and TD direction (direction made at a 90 degree angle with the MD direction). The strength and elongation of the test piece was measured using RTC-125A (manufactured by Orientech Co., Ltd.) in an environment of a temperature of 23° C. and a humidity of 50 RH%. Further, the F5 value (tensile strength when the film is stretched by 5%) in the MD direction and the TD direction was measured. The tensile strength (kgf/mm ² ) and elongation at break (%) in the MD direction and TD direction, and the F5 value (kgf/mm ² ) were as shown in Table 1.

In addition, test pieces cut out from each of the MD and TD directions were placed in a heating oven at 150°C and heat treated at 150°C for 30 minutes in accordance with JIS/C-2318, and the heat shrinkage rate was measured. The results were as shown in Table 1.

Each film obtained above was cut into a test piece with a width of 50 mm and a length of 50 mm, and the haze of the film was measured at 23°C and 50% RH using a haze meter (NDH4000, manufactured by Nippon Denshoku Industries Co., Ltd.). The measurement was performed in accordance with JIS K7136:2000. The measurement results are shown in Table 1 below.

In addition, for each film with and without corona treatment on the surface, test pieces 50 mm wide and 50 mm long were cut and the wet tension was measured at 23°C and 50% RH using a wet tension test mixture (manufactured by Wako Pure Chemical Industries, Ltd.). The measurement was performed in accordance with JIS K6768:1999. The measurement results are shown in Table 1 below.

In addition, the friction coefficient between the test pieces whose surfaces obtained above were subjected to corona treatment and the friction coefficient between test pieces whose surfaces were not subjected to corona treatment were measured using a friction coefficient measuring device (AFT-200, Daiei Kagaku Seiki Seisakusho Co., Ltd.). The measurement was carried out using a 23° C. and 50 RH% humidity environment. The measurements were conducted in accordance with JIS K7125:1999. The measurement results were as shown in Table 1 below.

As is clear from Table 1, the polyethylene terephthalate films synthesized using biomass-derived ethylene glycol (Examples 1 and 2) have physical properties that are comparable to those of existing polyester films (Comparative Example 1).

Claims (7)

A method for producing a biaxially stretched resin film made of a resin composition containing, as a main component, a polyester composed of a diol unit and a dicarboxylic acid unit, comprising:
The resin composition contains 50 to 90% by mass of a biomass-derived polyester in which a diol unit is ethylene glycol derived from biomass and a dicarboxylic acid unit is terephthalic acid derived from a fossil fuel;
The manufacturing method includes a step of biaxially stretching the resin composition containing the biomass-derived polyester,
The method for producing a biaxially stretched resin film, wherein the biaxially stretching step is a step of stretching in the longitudinal direction and then stretching in the transverse direction. The method for producing a biaxially stretched resin film according to claim 1, wherein the resin composition contains 5 to 45% by mass of recycled polyester relative to the entire resin composition. 3. The method for producing a biaxially stretched resin film according to claim 1, wherein the biaxially stretched resin film has a breaking strength of 5 to 40 kgf/mm ² in the MD direction and 5 to 35 kgf/mm ² in the TD direction. Production of a biaxially stretched resin film according to any one of claims 1 to 3, wherein the elongation at break of the biaxially stretched resin film is 50 to 350% in the MD direction and 50 to 300% in the TD direction. Method. Any one of claims 1 to 4, wherein the longitudinal stretching ratio of the biaxially stretched resin film is 2.5 times or more and 4.2 times or less, and the transverse stretching ratio is 2.5 times or more and 5.0 times or less. The method for producing a biaxially stretched resin film according to item (1). Any one of claims 1 to 5, wherein the content of biomass-derived carbon as measured by radiocarbon (C14) in the resin composition is 10 to 19% with respect to the total carbon in the resin composition. The method for producing a biaxially stretched resin film as described in 2. The method for producing a biaxially stretched resin film according to any one of claims 1 to 6, wherein the biaxially stretched resin film has a thickness of 5 to 12.13 μm.