Polyester resin composition pellets

Abstract

To provide a polyester resin composition which has a relatively high degree of crystallization and the inside also is crystallized to the same degree as the surface.SOLUTION: There is provided a polyester resin composition which comprises a dicarboxylic acid component containing furandicarboxylic acid as a main component and a glycol component containing ethylene glycol as a main component, wherein the degree of crystallization is 5% or more and the heights of absorbance peaks I1 to I4 in the infrared absorption spectrum satisfy the following expression, |I1 / I2-I3 / I4|≤0.20 (where, I1 represents the height of an absorbance peak in the vicinity of 1340 cm-1 on the surface of the polyester resin composition, I2 represents the height of an absorbance peak in the vicinity of 1580 cm-1 on the surface of the polyester resin composition, I3 represents the height of an absorbance peak in the vicinity of 1340 cm-1 at a depth of 1 mm from the surface of the polyester resin composition, I4 represents the height of an absorbance peak in the vicinity of 1580 cm-1 at a depth of 1 mm from the surface of the polyester resin composition.)SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a polyester resin composition. [Background technology]

[0002] Polyester resins such as polyethylene terephthalate (PET) and polybutylene terephthalate (PBT) are thermoplastic resins with excellent heat resistance and mechanical properties, and are therefore used in a very wide range of fields, including plastic films, electronics, energy, packaging materials, and automobiles.

[0003] However, PET and PBT are resins made from petroleum-derived substances, and in recent years, with the aim of moving away from petroleum, biodegradable resins and resins made from biomass-derived raw materials have been attracting attention as environmentally friendly or sustainable alternatives to PET and PBT.

[0004] Furandicarboxylic acid (FDCA), a biomass-derived raw material, has a planar structure, and it has been proposed that it has a similar structure to terephthalic acid, which is a component of PET.

[0005] For example, Patent Document 1 discloses a production method in which a polyester resin containing a polyethylene furan dicarboxylate resin is dried under reduced pressure and then a polyester film is produced. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] International Publication No. 2018 / 159648 Summary of the Invention [Problem to be solved by the invention]

[0007] When polyester resin is used in various fields in a desired shape, the polyester resin is generally formed into a pellet shape. The pellets are generally processed into a molded body of a shape according to the application, and the pellets are stored in a storage device such as a hopper or a tank, and are transported to a processing device such as an extruder or a molding machine through a conveying device such as a transport line, and are processed into a molded body. However, when polyester resin pellets consisting of a dicarboxylic acid component mainly composed of furandicarboxylic acid and a glycol component mainly composed of ethylene glycol are prepared and dried under reduced pressure as described in Patent Document 1, it was found that the shape of the pellets cannot be maintained due to fusion during drying. As a result, it was also found that clogging and unevenness in the supply amount occur at the raw material inlet of the conveying device or processing device.

[0008] An object of the present invention is to provide a polyester resin composition in which fusion between pellets is unlikely to occur and in which the pellets are unlikely to crack or chip during transportation and processing. [Means for solving the problem]

[0009] As a result of intensive research to solve the above-mentioned problems, the inventors have discovered that a polyester resin composition is composed of a dicarboxylic acid component mainly composed of furandicarboxylic acid and a glycol component mainly composed of ethylene glycol, and therefore, despite being a resin with a relatively slow crystallization rate, has a relatively high degree of crystallization and is crystallized internally to the same extent as on the surface. This makes it possible, when the resin composition is in the form of pellets, to prevent fusion between the pellets and also to prevent the pellets from cracking or chipping during transportation and processing, and thus completed the present invention.

[0010] That is, the present invention comprises the following configuration. [1] A polyester resin composition comprising a dicarboxylic acid component mainly composed of furandicarboxylic acid and a glycol component mainly composed of ethylene glycol, the polyester resin composition having a crystallinity of 5% or more and an absorbance peak height I in an infrared absorption spectrum. 1 ~I4 A polyester resin composition which satisfies the following formula: |I 1 / I 2 -I 3 / I 4 |≦0.20 (In the formula, I 1 is 1340 cm on the surface of the polyester resin composition -1 The height of the absorbance peak near I 2 is 1580 cm on the surface of the polyester resin composition -1 The height of the absorbance peak near I 3 is 1340 cm at a depth of 1 mm from the surface of the polyester resin composition -1 The height of the absorbance peak near I 4 is 1580 cm at a depth of 1 mm from the surface of the polyester resin composition -1 (Indicates the height of the absorbance peak near the [2] The polyester resin composition according to [1] above, having a crystallinity of 10% or more. [3] I above 3 / I 4 The polyester resin composition according to [1] or [2] above, wherein [4] The polyester resin composition according to any one of [1] to [3] above, which has a heat of fusion ΔHm of 5 J / g or more. Effect of the Invention

[0011] In the present invention, a resin composition can be obtained in which the crystallization rate is relatively slow, but the degree of crystallization is increased and the interior is crystallized to the same extent as the surface. When such a resin composition is in the form of pellets, the pellets are less likely to fuse together and are less likely to crack or chip during transportation and processing, making it suitable for many industrial applications. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] [Constitution of polyester resin composition] The polyester resin composition of the present invention is composed of a dicarboxylic acid component mainly composed of furandicarboxylic acid and a glycol component mainly composed of ethylene glycol, from the viewpoint of being an environmentally friendly or environmentally sustainable material. "Mainly" means that furandicarboxylic acid is 80 mol% or more in 100 mol% of all dicarboxylic acid components, and ethylene glycol is 80 mol% or more in 100 mol% of all glycol components. In 100 mol% of all dicarboxylic acid components, furandicarboxylic acid is preferably 90 mol% or more, more preferably 95 mol% or more, even more preferably 98 mol% or more, and particularly preferably 99 mol% or more. In 100 mol% of all glycol components, ethylene glycol is preferably 90 mol% or more, more preferably 95 mol% or more, even more preferably 98 mol% or more, and particularly preferably 99 mol% or more. Note that the polyester resin is a resin obtained by polycondensing a dicarboxylic acid component and a glycol component, and "100 mol% of dicarboxylic acid component" means that the total amount of all dicarboxylic acid-derived units in the polyester resin composition is 100 mol%. Similarly, for a glycol component, a polyvalent carboxylic acid component, a polyhydric alcohol component and the like described below, the total amount of units derived from all of the components in the polyester resin composition is 100 mol %.

[0013] The polyester resin composition of the present invention may contain units derived from a dicarboxylic acid component other than furandicarboxylic acid and units derived from a glycol component other than ethylene glycol, so long as the object of the present invention is not impaired.

[0014] Dicarboxylic acids other than furandicarboxylic acid include terephthalic acid, isophthalic acid, and phthalic acid. Examples of the dicarboxylic acid include aromatic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, 2,5-norbornenedicarboxylic acid, and tetrahydrophthalic acid; alicyclic dicarboxylic acids such as oxalic acid, malonic acid, succinic acid, adipic acid, azelaic acid, sebacic acid, undecanediacid, dodecanediacid, octadecanedioic acid, fumaric acid, maleic acid, itaconic acid, mesaconic acid, citraconic acid, and dimer acid. In the total dicarboxylic acid components (100 mol%), the dicarboxylic acid components other than furandicarboxylic acid are 20 mol% or less, preferably 10 mol% or less, more preferably 5 mol% or less, even more preferably 2 mol% or less, and particularly preferably 1 mol% or less. When two or more dicarboxylic acids other than furandicarboxylic acid are used, the total amount of the dicarboxylic acids is preferably within the above range.

[0015] In addition, as a polyvalent carboxylic acid other than dicarboxylic acid, a trivalent or higher polyvalent carboxylic acid or a hydroxycarboxylic acid may be used in combination in a small amount. Examples of the polyvalent carboxylic acid include ethanetricarboxylic acid, propanetricarboxylic acid, butanetetracarboxylic acid, pyromellitic acid, trimellitic acid, trimesic acid, and 3,4,3',4'-biphenyltetracarboxylic acid. In the polyester resin composition of the present invention, the trivalent or higher polyvalent carboxylic acid is preferably 10 mol% or less, more preferably 5 mol% or less, even more preferably 2 mol% or less, and particularly preferably 0 mol% (not including trivalent or higher polyvalent carboxylic acid) relative to 100 mol% of the total polyvalent carboxylic acid components. When two or more kinds of trivalent or higher polyvalent carboxylic acids are used, the total amount is preferably within the above range.

[0016] Examples of hydroxycarboxylic acids include lactic acid, citric acid, malic acid, tartaric acid, hydroxyacetic acid, 3-hydroxybutyric acid, p-hydroxybenzoic acid, p-(2-hydroxyethoxy)benzoic acid, and 4-hydroxycyclohexanecarboxylic acid. In the polyester resin composition of the present invention, the hydroxycarboxylic acid is preferably 10 mol% or less, more preferably 5 mol% or less, even more preferably 2 mol% or less, and particularly preferably 0 mol% (no hydroxycarboxylic acid) relative to the total polyvalent carboxylic acid components. When two or more hydroxycarboxylic acids are used, the total is preferably within the above range.

[0017] In this specification, the term "units derived from an acid" includes not only units derived from the acid but also units derived from an ester-forming derivative of the acid. Examples of the ester-forming derivatives of polycarboxylic acids or hydroxycarboxylic acids include their alkyl esters, acid chlorides, acid anhydrides, etc.

[0018] Examples of glycols other than ethylene glycol include aliphatic glycols such as 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2-methyl-1,3-propanediol, 2-amino-2-ethyl-1,3-propanediol, 2-amino-2-methyl-1,3-propanediol, 1,10-decanediol, dimethyloltricyclodecane, diethylene glycol, and triethylene glycol; ethylene oxide adducts or propylene oxide adducts of bisphenol A, bisphenol S, bisphenol C, bisphenol Z, bisphenol AP, and 4,4'-biphenol; alicyclic glycols such as 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, and 1,4-cyclohexanedimethanol; polyethylene glycol; and polypropylene glycol. In the total glycol components (100 mol%), the glycol components other than ethylene glycol are 20 mol% or less, preferably 10 mol% or less, more preferably 5 mol% or less, even more preferably 2 mol% or less, and particularly preferably 1 mol% or less. When two or more glycols other than ethylene glycol are used, the total amount of the glycols is within the above range. It is preferable.

[0019] In addition, a small amount of a polyhydric alcohol having a valence of three or more may be used in combination as a polyhydric alcohol other than glycol. Examples of the polyhydric alcohol having a valence of three or more include trimethylolmethane, trimethylolethane, trimethylolpropane, pentaerythritol, glycerol, and hexanetriol. In the polyester resin composition of the present invention, the amount of the polyhydric alcohol having a valence of three or more is preferably 10 mol% or less, more preferably 5 mol% or less, even more preferably 2 mol% or less, and particularly preferably 0 mol% (not including a polyhydric alcohol having a valence of three or more) relative to 100 mol% of the total polyhydric alcohol components. When two or more kinds of polyhydric alcohols having a valence of three or more are used, the total amount of the trihydric alcohols is preferably within the above range.

[0020] As described above, it is preferable that the amount of trivalent or higher polyvalent carboxylic acid or hydroxycarboxylic acid is small, so that in 100 mol% of all polyvalent carboxylic acid components, furandicarboxylic acid is preferably 80 mol% or more, more preferably 90 mol% or more, even more preferably 95 mol% or more, particularly preferably 98 mol% or more, and most preferably 99 mol% or more. Also, as described above, it is preferable that the amount of trivalent or higher polyhydric alcohol, etc. is small, so that in 100 mol% of all polyhydric alcohol components, ethylene glycol is preferably 80 mol% or more, more preferably 90 mol% or more, even more preferably 95 mol% or more, particularly preferably 98 mol% or more, and most preferably 99 mol% or more.

[0021] The polyester resin composition of the present invention may contain other resins such as polyamide, polystyrene, polyolefin, etc., as resin components, but from the viewpoint of mechanical properties and heat resistance, the content of resins other than polyester is preferably 20 mol% or less, more preferably 10 mol% or less, even more preferably 5 mol% or less, even more preferably 2 mol% or less, and most preferably 1 mol% or less, based on the polyester resin composition. In this specification, the term "polyester resin composition" is used even when resins other than polyester are contained.

[0022] Of all the structural units (100 mol%) of the polyester resin composition of the present invention, the content of ethylene furan dicarboxylate units is preferably 80 mol% or more, more preferably 90 mol% or more, even more preferably 95 mol% or more, particularly preferably 98 mol% or more, and most preferably 99 mol% or more.

[0023] The polyester resin composition of the present invention may contain additives as long as the purpose of the present invention is not hindered. Additives that may be used in the present invention include inert particles such as fine particles, heat-resistant polymer particles, and crosslinked polymer particles, fluorescent whitening agents, ultraviolet inhibitors, infrared absorbing dyes, heat stabilizers, surfactants, and antioxidants, depending on the purpose of use. One type of additive may be contained, or two or more types may be contained. The content of the additive is preferably 10% by mass or less, more preferably 5% by mass or less, even more preferably 2% by mass or less, and particularly preferably 1% by mass or less, based on the polyester resin composition. When two or more types of additives are used, the total amount of the additives is preferably within the above range.

[0024] Any fine particles can be selected as the fine particles, and examples of the fine particles include inorganic particles such as silica, calcium carbonate, barium sulfate, calcium sulfate, alumina, kaolinite, talc, and other organic particles. From the viewpoint of transparency in particular, silica particles having a refractive index relatively close to that of the polyester resin are preferred, and amorphous silica particles are more preferred.

[0025] The average particle size of the fine particles is preferably in the range of 1 to 10 μm, and more preferably in the range of 1.5 to 7 μm. It is preferably within the range of 1 μm or more, and more preferably within the range of 2 to 5 μm. If the average particle size of the fine particles is 1 μm or more, it is possible to impart an uneven structure suitable for imparting easy slipperiness to the surface of the resin composition, which is preferable. On the other hand, if the average particle size of the fine particles is 10 μm or less, it is preferable because high transparency can be maintained.

[0026] The ultraviolet absorbing agent can be selected from any of the above, and examples thereof include organic ultraviolet absorbing agents such as benzotriazole compounds and benzophenone compounds, and inorganic ultraviolet absorbing agents such as zinc oxide, titanium oxide, and cerium oxide in the form of fine particles having a particle size of 0.2 μm or less. The agent may be selected from known agents depending on the purpose of use.

[0027] The antioxidant may be any one selected from the above list, and examples thereof include aromatic amines, phenols, etc. Examples of stabilizers include phosphorus-based stabilizers such as phosphoric acid and phosphoric acid esters, sulfur-based stabilizers, and amine-based stabilizers.

[0028] [Physical properties of polyester resin composition] The polyester resin composition of the present invention has an absorbance peak height I 1 ~I 4 satisfies the following formula. Note that I 1 / I 2 and I 3 / I 4 shall be rounded off to the second decimal place. |I 1 / I 2 -I 3 / I 4 |≦0.20 (Equation 1) (In formula 1, I 1 is 1340 cm on the surface of the polyester resin composition of the present invention. -1 The height of the absorbance peak near I 2 is 1580 cm on the surface of the polyester resin composition of the present invention. -1 The height of the absorbance peak near I 3 is 1340 cm at a depth of 1 mm from the surface of the polyester resin composition of the present invention. -1 The height of the absorbance peak near I 4 is 1580 cm at a depth of 1 mm from the surface of the polyester resin composition of the present invention. -1 (Indicates the height of the absorbance peak near the

[0029] In the following description, the surface of the polyester resin composition is simply referred to as the "surface", the location 1 mm deep from the surface of the polyester resin composition is referred to as the "interior", and the value on the left side of the above formula 1 is referred to as the "crystal uniformity". The polyester resin composition of the present invention has a crystal uniformity of 0.20 or less, preferably 0.10 or less, more preferably 0.05 or less, and even more preferably 0.03 or less. When the crystal uniformity exceeds 0.20, there is a large difference between the crystallinity of the surface and the crystallinity of the interior, and the resin composition is prone to breakage such as cracks and chips during transportation and processing. 1 ~I 4 The method for measuring the crystal uniformity will be described later. The lower limit of the crystal uniformity is not particularly limited, and is 0.00(I 1 / I 2 and I 3 / I 4 and the same value).

[0030] I 1 / I 2 is preferably 0.65 or more, more preferably 0.70 or more, even more preferably 0.75 or more, and even more preferably 0.80 or more. 1 / I 2 The upper limit of is not particularly limited, but is, for example, 0.90 or less.

[0031] I 3 / I 4 is preferably 0.50 or more, more preferably 0.60 or more, even more preferably 0.65 or more, even more preferably 0.70 or more, particularly preferably 0.75 or more, and most preferably 0.80 or more. 3 / I 4 The upper limit of is not particularly limited, but is, for example, 0.90 or less.

[0032] From the viewpoint of making the crystallinity of the surface and the crystallinity of the inside the composition equal, the polyester resin composition is preferably in the form of pellets. The distance from the deepest part of the pellet to the surface is preferably 2.5 mm or less, more preferably 2 mm or less, even more preferably 1.5 mm or less, and particularly preferably 1.2 mm or less. The deepest part refers to the part furthest from the surface of the pellet. For example, in the case of a cylindrical pellet having a length of 3 mm and a diameter of 2 mm, the distance from the deepest part to the surface is 1 mm, and the distance from the deepest part to the surface is 1 mm. In the case of a cylindrical pellet having a diameter of 2 mm, the distance from the deepest part to the surface is 0.5 mm. The shape of the pellet may be, for example, a cylindrical shape, a disk shape, an elliptical cylinder shape, an elliptical disk shape, a go stone shape, a sphere shape, an irregular shape, etc., but a cylindrical shape is preferable from the viewpoint of productivity and handling during molding. In the case of a cylindrical pellet, the diameter is preferably 1 to 5 mm, more preferably 1.5 to 3 mm, and the length is preferably 1 to 10 mm, more preferably 2 to 5 mm.

[0033] The polyester resin composition of the present invention has a crystallinity of 5% or more, preferably 10% or more, more preferably 10-50%, even more preferably 15-40%, particularly preferably 20-35%, and most preferably 22-30%. If the crystallinity is less than 5%, there is a risk of frequent breakage such as cracking and chipping during transportation and processing, and when pelletized, there is a risk of the pellets fusing together. In addition, a higher crystallinity is preferable because the heat resistance of the polyester resin composition is higher, but the upper limit is about 50% from the viewpoint of molecular structure.

[0034] The degree of crystallinity is calculated by measuring the heat of fusion ΔHm (J / g) and the heat of cold crystallization ΔHc (J / g) and calculating the degree of crystallinity Χc (%) using the following formula 2. 0 The value of (J / g) is described in Physical Chemistry Chemical Physics, Vol. 16, (Eng), 2014, p.7946-7958. The method for measuring the heat of fusion ΔHm and the heat of cold crystallization ΔHc will be described later. Χc=100×(ΔHm-ΔHc) / ΔHm 0 (Formula 2)

[0035] From the viewpoint of increasing the crystallinity, the heat of fusion ΔHm is preferably 5 J / g or more, more preferably 10 J / g or more, 12 J / g or more, 15 J / g or more, 18 J / g or more, 20 J / g or more, 22 J / g or more, 25 J / g or more, 27 J / g or more, and most preferably 30 J / g or more. The upper limit of the heat of fusion ΔHm is not particularly limited, but is, for example, 60 J / g or less. If the heat of fusion ΔHm is less than 5 J / g, there is a risk that the pellets will fuse together when the resin composition is formed into pellets.

[0036] The cold crystallization heat ΔHc is preferably 3 J / g or less, more preferably 2 J / g or less, further preferably 1 J / g or less, and particularly preferably 0 J / g.

[0037] The polyester resin composition of the present invention has an apparent density of 0.8 g / cm 3 It is preferable that the concentration is 1.0 g / cm or more. 3 More preferably, it is 1.2 g / cm or more. 3 More preferably, it is 1.4 g / cm or more. 3 It is particularly preferable that the apparent density is 0.8 g / cm or more. 3 If the apparent density is less than 1.0 g / cm, many voids will be present in the polyester resin composition, and the resin composition may be subject to frequent damage such as cracks and chips during transportation and processing. 3 The following is the result.

[0038] Of 10 cylindrical pellets having a length of about 3 mm and a diameter of about 2 mm formed from the polyester resin composition of the present invention, the number of pellets having a shape retention rate of 80% or more after the impact resistance test is preferably 5 or more, more preferably 7 or more. Details of the impact resistance test will be described later.

[0039] The polyester resin composition of the present invention preferably has an intrinsic viscosity of 0.3 to 1.2 dl / g, more preferably 0.4 to 1.0 dl / g or less, and even more preferably 0.5 to 0.8 dl / g or less. If the intrinsic viscosity is lower than 0.3 dl / g, the resin composition is brittle and may be subject to frequent breakage such as cracks and chips during transportation or processing. On the other hand, if the intrinsic viscosity is higher than 1.2 dl / g, the increase in filtration pressure during melt processing becomes large, and It may become difficult to perform high-precision filtration, and it may become difficult to extrude the resin through the filter. Also, if the intrinsic viscosity is higher than 1.2 dl / g, the effect of improving the mechanical properties of the resin composition may become saturated.

[0040] The moisture content of the polyester resin composition of the present invention is preferably 200 ppm or less, more preferably 100 ppm or less. If the moisture content exceeds 200 ppm, when the resin composition is made into a pellet shape, the polymer may decompose in the process of processing the pellet into a molded product, or the polymer discharge rate may fluctuate greatly due to pressure fluctuation. There is no particular limitation on the method for making the moisture content of the polyester resin composition of the present invention within the above range, and for example, it may be dried at room temperature or using hot air. The lower the moisture content, the more suppressed the decomposition of the resin is, and therefore, it is preferable, but the actual lower limit is 1 ppm. In the examples and comparative examples described below, the moisture content is 100 ppm or less.

[0041] The polyester resin composition of the present invention has a crystallization temperature of preferably 150 to 180° C., more preferably 160 to 175° C. When the crystallization temperature is 150° C. or higher, the degree of crystallization of the resin composition is easily increased and the heat resistance is excellent. On the other hand, when the crystallization temperature is 180° C. or lower, the degree of crystallization of the surface and the inside of the resin composition is easily uniform.

[0042] The intrinsic viscosity and the crystallization temperature are values ​​inherent to the resin composition, and are physical properties that do not change much before and after the crystallization treatment described below.

[0043] [Method of producing polyester resin composition] A method for producing the polyester resin composition of the present invention will be described below, but the method is not limited to the following method.

[0044] The method for producing the polyester resin composition is not particularly limited, and any method can be used, such as a direct esterification method in which furandicarboxylic acid is directly reacted with ethylene glycol, and if necessary, other dicarboxylic acid components or glycol components, or an ester exchange method in which dimethyl ester of furandicarboxylic acid (including methyl ester of other dicarboxylic acid, if necessary) is reacted with ethylene glycol (including other glycol components, if necessary). When the moisture content of the obtained polyester resin composition is high, it is preferable to dry it at room temperature or with hot air in order to reduce the moisture content. In addition, a commercially available product may be used as the polyester resin composition.

[0045] Next, the polyester resin composition is subjected to a crystallization treatment. Specifically, the polyester resin composition is subjected to a heat treatment in the presence of an inert gas in a supercritical state, and then the pressure is reduced from the pressure in the supercritical state to atmospheric pressure, thereby obtaining the polyester resin composition of the present invention. Hereinafter, the polyester resin composition before the crystallization treatment (before the heat treatment) is referred to as a "polyester resin material" to distinguish it from the polyester resin composition after the crystallization treatment (the polyester resin composition of the present invention).

[0046] Since the inert gas dissolves in the polyester resin material and plasticizes it, the crystallization behavior during the treatment with the inert gas under high pressure is different from that under normal atmospheric pressure. Therefore, the heat treatment temperature is preferably from crystallization temperature -70°C to crystallization temperature +10°C, more preferably from crystallization temperature -60°C to crystallization temperature, even more preferably from crystallization temperature -35°C to crystallization temperature -5°C, particularly preferably from crystallization temperature -30°C to crystallization temperature -10°C, and most preferably from crystallization temperature -25°C to crystallization temperature -15°C. The method for measuring the crystallization temperature will be described later.

[0047] The inert gas is not particularly limited as long as it does not activate the polyester resin material. Examples of the inert gas include oxygen, methane, propane, nitrogen dioxide, nitrogen, argon, helium, and carbon dioxide, and among these, it is preferable to use carbon dioxide. Note that carbon dioxide may react with some compounds and may not be usable as an inert gas, but in this specification, "inert gas" refers to a gas that does not activate the polyester resin composition.

[0048] If the pressure during heat treatment is high, the inert gas dissolves in the polyester resin material and plasticizes it, which results in crystallization in a short time, so the pressure during heat treatment is preferably 5 MPa or more, more preferably 8 Ma or more, even more preferably 10 Ma or more, particularly preferably 15 Ma or more, and most preferably 18 Ma or more. The upper limit of the pressure during heat treatment is not particularly limited, but is, for example, 50 MPa. A reaction vessel that can withstand a pressure exceeding 50 MPa needs to have a very thick metal thickness, which is not practical.

[0049] In order to make the pressure during heat treatment higher than atmospheric pressure, for example, the polyester resin material is placed in a high-pressure reaction vessel and connected to a gas cylinder, a pump, a back pressure valve, a pressure gauge, a safety valve, etc. After the high-pressure reaction vessel is heated to a predetermined temperature, an inert gas is pumped through the pump and the pressure is adjusted to a predetermined level by the back pressure valve.

[0050] The heat treatment temperature of the polyester resin composition of the present invention is preferably 105 to 180° C., more preferably 135 to 165° C. When the heat treatment temperature is 105° C. or higher, the crystallinity of the resin composition is easily increased and the heat resistance is excellent. On the other hand, when the heat treatment temperature is 180° C. or lower, the crystallinity of the surface and the inside of the resin composition is easily uniform.

[0051] The heat treatment time is preferably 10 minutes or more, more preferably 15 minutes or more, even more preferably 20 minutes or more, and preferably 25 minutes or more. If the heat treatment time is 10 minutes or more, the inert gas can be sufficiently dissolved in the polyester resin material. The upper limit of the heat treatment time is not particularly limited, but is, for example, 200 minutes or less, preferably 180 minutes or less, and more preferably 150 minutes or less. If it exceeds 200 minutes, the effect of increasing the crystallinity is saturated.

[0052] The time required for reducing the pressure from the pressure in the supercritical state to atmospheric pressure is preferably 0.5 to 20 minutes, more preferably 1.5 to 10 minutes, and even more preferably 3 to 5 minutes.

[0053] The pressure reduction rate from the pressure in the supercritical state to atmospheric pressure is preferably 1 to 30 MPa / min, more preferably 2 to 25 MPa / min, even more preferably 3 to 15 MPa / min, particularly preferably 4 to 10 MPa / min, and most preferably 5 to 7 MPa / min. EXAMPLES

[0054] The present invention will be described below with reference to examples, but the present invention is not limited to these examples. The evaluation methods used in each example and comparative example are as follows.

[0055] (1) Intrinsic viscosity The polyester resin material was pulverized and dried. Then, the polyester resin was dissolved in a mixed solvent of parachlorophenol / tetrachloroethane = 75 / 25 (mass ratio) to a concentration of 0.4 g / dl to obtain a solution. The flow time of the solution and the flow time of the mixed solvent were measured using an Ubbelohde viscometer, and the intrinsic viscosity of the polyester resin was calculated from the time ratio using the Huggins formula. Note that the Huggins constant was set to 0.38 The intrinsic viscosity of the polyester resin was calculated assuming that

[0056] (2) Melting point, glass transition temperature, crystallization temperature The melting point, glass transition temperature, and crystallization temperature of the polyester resin material were measured using a DSC6200 manufactured by Seiko Instruments Inc.

[0057] (3) Heat of fusion ΔHm, heat of cold crystallization ΔHc, degree of crystallinity Xc Using a Seiko Instruments DSC6200, the pellets were heated in a nitrogen atmosphere from 25°C to 300°C at a heating rate of 10°C / min in accordance with JIS K7122, and the heat of fusion ΔHm (J / g) and the heat of cold crystallization ΔHc (J / g) during the heating process were determined. 0 The value of (J / g) was set to 137 J / g as described above, and the degree of crystallization Xc (%) was calculated from the following formula. The average of the heat of fusion ΔHm of the three pellets was calculated to be the heat of fusion ΔHm of the resin composition, and the average values ​​were calculated similarly for the heat of cold crystallization ΔHc and the degree of crystallization Xc. Note that, except for Comparative Example 3, pellets after crystallization treatment (polyester resin composition) were used as the pellets, and the same applies to the measurements from (4) onwards. Xc = 100 × (ΔHm-ΔHc) / ΔHm 0

[0058] (4) Crystal uniformity Fourier transform infrared absorption spectrum (FT-IR) ATR (attenuated total reflection) was used to measure the peak at 1340cm -1 CH of ethylene glycol appears nearby 2 (trans structure) bending vibration absorption and 1580cm -1 The absorption of the furan rings that appear near the surface and have little change due to crystallinity is measured, and the crystallinity at the surface or at a depth of 1 mm from the surface is quantified to indicate the crystal uniformity. Specifically, the height of the absorbance peak of the polyester resin composition I 1 ~I 4 Measure I 1 / I 2 and I 3 / I 4 Difference from (|I 1 / I 2 -I 3 / I 4 |) was calculated. I 1 : 1340 cm at the surface of the pellet -1 Height of absorbance peak near I 2 : 1580 cm at the surface of the pellet -1 Height of absorbance peak near I 3 : 1340 cm at a depth of 1 mm from the pellet surface -1 Height of absorbance peak near I 4 : 1580 cm at a depth of 1 mm from the pellet surface -1 Height of absorbance peak near

[0059] The FT-IR ATR measurement was carried out under the following conditions. FT-IR instrument: Agilent Technologies Cary 660 FTIR Single reflection ATR (attenuated total reflection) attachment: Specac MKII Golden Gate Internal reflective elements: Diamond Incident angle: 45° Resolution: 4cm -1 Number of times: 32

[0060] (5) Impact resistance test A crushing rod and a sample were placed in a polycarbonate tube 70 mm long and 20 mm in diameter, the tube was closed with a stainless steel lid, and then the tube was shaken 150 times. A stainless steel cylinder about 50 mm long and 10 mm in diameter was placed as the crushing rod, and 10 cylindrical pellets about 3 mm long and 2 mm in diameter obtained in the examples and comparative examples were placed as samples. After shaking, the pellets were removed and the shape retention rate of each pellet was calculated using the following formula, and the impact resistance was evaluated using the following index. ○: 7 or more pellets with a shape retention rate of 80% or more △: 5 to 6 pellets with a shape retention rate of 80% or more ×: 4 or less pellets with a shape retention rate of 80% or more Resin pellet shape retention rate (%) = pellet volume after shaking ÷ pellet volume before shaking × 100

[0061] (6) Apparent density The mass and volume of the pellets were measured, and the apparent density was calculated using the following formula: The apparent density was calculated using 10 pellets, and the average of the apparent densities of the 8 pellets excluding the upper and lower limits was taken as the apparent density of the resin composition. Apparent density (g / cm 3 ) = mass (g) / volume (cm 3 )

[0062] (7) Fusion 5 g of pellets were placed in a 10 mL glass vial and heat-treated at 120° C. for 1 hour in a nitrogen atmosphere. After cooling to room temperature, the pellets were removed and the fusion property was evaluated according to the following index. ○: The pellets do not fuse together, and they can be taken out one by one. △: Although there is slight adhesion between the pellets, the pellets can be easily separated and removed one by one. ×: Pellets were fused together and could not be taken out one by one.

[0063] Example 1 A polyester resin material in the form of cylindrical pellets with a length of about 3 mm and a diameter of about 2 mm was prepared by the following manufacturing method. A starting mixture of 2,5-furandicarboxylic acid (FDCA) and ethylene glycol (EG) (EG / FDCA molar ratio 1.5) was treated with 149 ppm of tetraethylammonium hydroxide (based on the molar amount of FDCA, N(Et) 4(calculated as mole ppm of OH) was added. Next, esterification was performed for 3.2 hours while gradually increasing the temperature of the mixture from 80°C to 220°C, and volatile compounds such as water were distilled off, after which a polycondensation catalyst and a phosphorus compound were added. Note that an ethylene glycol solution of basic aluminum acetate was added as a polycondensation catalyst, and an ethylene glycol solution of 3,5-di-tert-butyl-4-hydroxybenzylphosphonic acid diethyl was added as a phosphorus compound. An ethylene glycol solution of basic aluminum acetate and an ethylene glycol solution of 3,5-di-tert-butyl-4-hydroxybenzylphosphonic acid diethyl were added so that the amount of aluminum was 202 ppm and the amount of 3,5-di-tert-butyl-4-hydroxybenzylphosphonic acid diethyl was 435 ppm relative to the molar amount of FDCA in the starting mixture. The temperature of the mixture to which the ethylene glycol solution was added was raised from 220°C to 270°C, and the pressure was reduced to 1 mmHg (about 133 Pa), and initial polycondensation was performed for 60 minutes. Further, a final polycondensation was carried out for 119 minutes at about 13 Pa and 270° C. After the completion of the polycondensation, the pressure was returned to normal pressure, and the polycondensate was passed through a Hesstrahlung in water, cooled, and then cut to obtain a polyester resin material in the form of cylindrical pellets with a length of about 3 mm and a diameter of about 2 mm. The polyester resin material was a polymer composed of units derived from a furandicarboxylic acid component, units derived from an ethylene glycol component, and units derived from a diethylene glycol component (4.0 mol% relative to all units derived from the glycol components), and had a content of aluminum atoms derived from the catalyst component of 30 ppm, a content of phosphorus atoms derived from the catalyst auxiliary component of 74 ppm, an intrinsic viscosity of 0.62 dL / g, a crystallization temperature of 170°C, a melting point of 215°C, a glass transition temperature of 86°C, and a degree of crystallinity of 3%.

[0064] The obtained polyester resin material was dried under reduced pressure (1 Torr) at 80°C for 12 hours, after which 4 g was weighed out and placed in a 10 mL reaction vessel. At the time of the above-mentioned addition, the reaction vessel had been preheated to a temperature close to 150°C. Carbon dioxide was pumped into the reaction vessel at a flow rate of 5 mL / min from a pump connected to a carbon dioxide cylinder, and the pressure inside the reaction vessel was adjusted with a pressure relief valve to 20 MPa after 3 minutes, after which a crystallization treatment was carried out at 150°C for 30 minutes. After the crystallization treatment, the pressure was reduced and the reaction vessel was cooled to 100°C. The pressure in the reaction vessel was reduced to atmospheric pressure at a rate of 5 MPa / min to obtain a polyester resin composition. The vessel was not cooled, and the polyester resin composition was removed from the reaction vessel and cooled to room temperature, after which the physical properties were evaluated. The evaluation results are shown in Table 1.

[0065] (Examples 2 to 9) A polyester resin composition was obtained in the same manner as in Example 1 except that the treatment conditions were changed as shown in Table 1. The evaluation results are shown in Table 1.

[0066] Comparative Example 1 The polyester resin material obtained by the manufacturing method described in Example 1 was dried under reduced pressure (1 Torr) at 80°C for 12 hours, and then 4 g was weighed out and placed in a 10 mL reaction vessel. The reaction vessel was filled with air and the pressure was atmospheric pressure. The reaction vessel was then heated to 150°C and subjected to a crystallization treatment for 180 minutes to obtain a polyester resin composition. The polyester resin composition was removed from the reaction vessel and the physical properties were evaluated. The evaluation results are shown in Table 1.

[0067] Comparative Example 2 A resin composition was obtained in the same manner as in Comparative Example 1, except that the crystallization treatment time was changed to 240 minutes. The evaluation results are shown in Table 1.

[0068] Comparative Example 3 The polyester resin material obtained by the manufacturing method described in Example 1 was dried under reduced pressure (1 Torr) at 100° C. for 24 hours, and then its physical properties were evaluated. The evaluation results are shown in Table 1.

[0069] [Table 1]

[0070] In Comparative Examples 1 and 2, the crystallization treatment was carried out with air without using an inert gas, so the crystallinity of the interior was significantly inferior to that of the surface, and the pellets were prone to cracking and chipping due to impact. Note that in Comparative Examples 1 and 2, although an inert gas was not used, the crystallization treatment itself was carried out, so there was no fusion, unlike in Comparative Example 3.

[0071] In Comparative Example 3, the crystallinity was the same as before the drying under reduced pressure even after drying under reduced pressure for a long time at high temperature, so the pellets were prone to cracking and chipping due to impact. Also, in Comparative Example 3, the pellets were fused together. [Industrial Applicability]

[0072] The polyester resin composition of the present invention has a relatively high degree of crystallinity and is crystallized internally to the same extent as on the surface, and therefore can be suitably used in many industrial applications.

Claims

1. A polyester resin composition pellet comprising a dicarboxylic acid component mainly composed of frangic acid and a glycol component mainly composed of ethylene glycol, The degree of crystallinity is 5% or higher. Height of absorbance peak in infrared absorption spectrum I １ ~I ４ However, the following two formulas satisfy the following polyester resin composition pellets. |I １ / I ２ -I ３ / I ４ |≦0.20 I 1 / I 2 ≧0.65 (where I １ represents the height of the absorbance peak near 1340 cm －１ on the surface of the polyester resin composition pellet, I ２ represents the height of the absorbance peak near 1580 cm －１ on the surface of the polyester resin composition pellet, I ３ represents the height of the absorbance peak near 1340 cm at a depth of 1 mm from the surface of the polyester resin composition pellet, I －１ represents the height of the absorbance peak near 1580 cm at a depth of 1 mm from the surface of the polyester resin composition pellet, I ４ represents the height of the absorbance peak near 1580 cm at a depth of 1 mm from the surface of the polyester resin composition pellet)​​

2. A polyester resin composition pellet according to claim 1, wherein the degree of crystallinity is 10% or more.

3. The above I ３ / I ４ A polyester resin composition pellet according to claim 1 or 2, wherein the ratio is 0.50 or higher.

4. A polyester resin composition pellet according to claim 1 or 2, wherein the heat of fusion ΔHm is 5 J / g or more.