JP5114993B2 - Polyester resin - Google Patents

Description

  The present invention relates to a polyester resin using erythritan, which is a plant-derived raw material, and more particularly to a polyester resin having excellent heat resistance and transparency.

In recent years, polyester resins represented by polyethylene terephthalate (hereinafter referred to as PET) are widely used as containers such as bottles, injection molded articles, films, sheets, and fibers because they have excellent mechanical properties, heat resistance, and chemical resistance. Used in large quantities.
Along with the growing demand for a recycling-oriented (sustainable) society, in the materials field, it is desired to move away from fossil fuels as well as energy. When developing high-molecular materials that do not use petroleum as a raw material, biomass using plants as raw materials is a promising raw material candidate, and the practical application of biomass plastics is rapidly progressing.

  A polyester composed of isosorbide, which is one of biomass raw materials, terephthalic acid and ethylene glycol has been proposed (Patent Document 1). However, since secondary alcohols such as isosorbide have low reactivity with terephthalic acid, even if a high molecular weight polyester is to be manufactured, the ratio of isosorbide to the whole polyester is only 2.6% or less. I can't.

Further, bishydroxymethylfuran (hereinafter referred to as BHF) obtained by decomposing cellulose has attracted attention as a biomass raw material, and a polyester using the raw material has been studied (Non-patent Document 1).
However, since polyester resins composed of BHF and various dicarboxylic acids can only have low transparency and heat resistance compared to conventional polyesters, they can be obtained from biomass raw materials having heat resistance and transparency equivalent to or higher than conventional PET. There has been a need for high molecular weight polyesters obtained.
Special table 2002-512304 gazette Journal of Polymer Science, Vol.62, No.7, pp.321-325 (Jul., 2005)

  In view of the above problems, an object of the present invention is to provide a high molecular weight polyester resin containing a large amount of biomass raw materials and having high heat resistance and transparency.

As a result of intensive studies to solve the above problems, the present inventors have worked on the development of a polyester resin containing a dihydroxy compound represented by the following general formula (1) and terephthalic acid, and the polyester resin has a polymerization reactivity. The present inventors have found that a good and high molecular weight polyester resin can be easily obtained, and are excellent in heat resistance and transparency, and have reached the present invention.
That is, the gist of the present invention resides in a polyester resin containing a structural unit derived from a dihydroxy compound represented by the following general formula (1) and a structural unit derived from a dicarboxylic acid.

  The polyester resin of the present invention can be polymerized more easily than conventional biomass raw material polyester resins using isosorbide as a copolymerization component, and can be widely used as various molding materials having transparency and heat resistance by molding.

The description of the constituent requirements described below is an example (representative example) of an embodiment of the present invention, and the present invention is not limited to these contents. The details will be described below.
The polyester resin of the present invention is a polyester resin comprising a dicarboxylic acid and a diol, and includes a dihydroxy compound represented by the following general formula (1) as a diol component, and another diol component. is there.

  In the present invention, examples of the dihydroxy compound represented by the general formula (1) include erythritan. Erythritan is a compound synthesized by an intramolecular dehydration reaction of erythritol, a natural polysaccharide. It is a diol component having a 5-membered ring structure, and the two hydroxyl groups have a cis structure and do not contain a trans structure. Because of this structure, it is considered that a polyester resin containing erythritan as a diol component has low crystallinity, excellent transparency, and improved heat resistance.

  The content of erythritan in the polyester resin of the present invention is preferably 20 to 100 mol%, more preferably 30 to 100 mol%, based on all diol components. When the erythritan content is within this range, a resin excellent in moldability, mechanical strength, transparency, and heat resistance can be obtained. The greater the erythritan content, the higher the glass transition temperature and the better the heat resistance, and the smaller the content, the lower the heat resistance.

  In the present invention, erythritan is used as the main component as the diol component, but ethylene glycol, diethylene glycol, 1,4-butanediol, 1,4-cyclohexanedimethanol, and the like can be used as other diol components. These diol components may be used alone or in combination of two or more, but 1,4-cyclohexanedimethanol is preferably used from the viewpoint that heat resistance can be maintained. The main component here is usually 50 mol% or more, preferably 60 mol% or more, more preferably 70 mol% or more, and particularly preferably 90 mol% or more with respect to the total diol component.

On the other hand, examples of the dicarboxylic acid that can be used in the present invention include an aromatic dicarboxylic acid or a mixture thereof, or a mixture of an aromatic dicarboxylic acid and an aliphatic dicarboxylic acid.
Examples of the aromatic dicarboxylic acid include terephthalic acid and isophthalic acid, and examples of the aromatic dicarboxylic acid derivative include lower alkyl esters of aromatic dicarboxylic acid, specifically methyl ester, ethyl ester, propyl ester, and butyl. Examples include esters. Among these, as the aromatic dicarboxylic acid, those having terephthalic acid as a main component are preferable from the viewpoint of maintaining the glass transition temperature (heat resistance) of the polyester resin. As the aromatic dicarboxylic acid derivative, dimethyl terephthalate is preferable. The main component is preferred. The main component here is usually 50 mol% or more, preferably 60 mol% or more, more preferably 70 mol% or more, and particularly preferably 90 mol% or more with respect to the total dicarboxylic acid component.

As the aliphatic dicarboxylic acid component, an aliphatic dicarboxylic acid or a derivative thereof is used. Specific examples of the aliphatic dicarboxylic acid 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. Examples include chain or alicyclic dicarboxylic acids. Examples of the aliphatic dicarboxylic acid derivative include lower alkyl esters such as methyl ester, ethyl ester, propyl ester, and butyl ester of the aliphatic dicarboxylic acid, and cyclic acid anhydrides of the aliphatic dicarboxylic acid such as succinic anhydride. Can be used. Of these, the main component of the aliphatic dicarboxylic acid is preferably an alicyclic dicarboxylic acid from the viewpoint of the physical properties of the resulting polymer. Among them, cyclohexanedicarboxylic acid is more preferable, and 1,4-cyclohexanedicarboxylic acid is most preferable. preferable.
These dicarboxylic acids can be used alone or in combination of two or more.

  The intrinsic viscosity at a concentration of 1.00 g / dl at 30 ° C. in a 1: 1 weight ratio solution of phenol and 1,1,2,2-tetrachloroethane of the polyester resin of the present invention is 0.40 to 1.20 dl / It is preferably in the range of g, and more preferably in the range of 0.50 to 0.80 dl / g. When the intrinsic viscosity of the copolymerized polyester resin is within this range, a molded product having excellent moldability, heat resistance, and transparency can be obtained. That is, when the intrinsic viscosity of the polyester resin is less than 0.40 dl / g, impact resistance, transparency and heat resistance are lowered, and when it exceeds 1.20 dl / g, moldability is lowered.

The preferred polyester resin of the present invention is basically produced by a conventional production method of a polyester resin comprising a dicarboxylic acid component containing terephthalic acid as a main component and a diol component containing erythritan as a main component.
That is, a dicarboxylic acid component containing terephthalic acid as a main component and a diol component containing erythritan as a main component are esterified in an esterification reaction tank, and the resulting esterification reaction product is transferred to a polycondensation reaction tank for polycondensation. In the direct polymerization method, a dicarboxylic acid component mainly composed of an ester-forming derivative of terephthalic acid and a diol component mainly composed of erythritan are transesterified in a transesterification reaction tank, and the resulting transesterification reaction product is overlapped. An ester exchange method in which a polycarboxylic acid is transferred to a condensation reaction tank, or a slurry prepared by dispersing a dicarboxylic acid component containing terephthalic acid as a main component in a diol component containing erythritan as a main component in a slurry preparation tank. Continuously added to the esterification reaction product or transesterification reaction product obtained above in the esterification reaction tank. And esterified, it may also take any of such continuous direct polymerization method polycondensation by transferring the reaction product obtained continuously or / and stepwise polycondensation reaction tank. A diol component other than erythritan can be added at any time until the esterification reaction or the transesterification reaction is completed.

  Usually, the resin obtained by the polycondensation reaction is extracted in the form of a strand from an extraction port provided at the bottom of the polycondensation reaction tank, and is cooled with water or after water cooling and cut into a pellet by cutting with a cutter. However, the polycondensation pellets are subjected to a heat treatment and subjected to solid phase polymerization, whereby the degree of polymerization can be further increased, and reaction by-products such as acetaldehyde and low molecular oligomers can be reduced.

In the above production method, the esterification reaction is carried out using, for example, an antimony trioxide, an organic acid salt such as antimony, titanium, magnesium, calcium, or an esterification catalyst such as alcoholate. It is carried out at a temperature of about 270 ° C. and a pressure of about 1 × 10 ⁵ to 4 × 10 ⁵ Pa, and the transesterification reaction is performed, for example, lithium, sodium, potassium, magnesium, calcium, manganese, titanium as necessary. The reaction is performed at a temperature of about 200 to 270 ° C. and a pressure of about 1 × 10 ⁵ to 4 × 10 ⁵ Pa using a transesterification catalyst such as an organic acid salt such as zinc.

The polycondensation reaction uses, for example, phosphorus compounds such as orthophosphoric acid, phosphorous acid, and esters thereof as stabilizers, and metal oxides such as diantimony trioxide, germanium dioxide, germanium tetroxide, etc. Alternatively, using a polycondensation catalyst such as an organic acid salt such as antimony, germanium, zinc, titanium, cobalt, or alcoholate, a temperature of about 240 to 290 ° C., a reduced pressure of about 1 × 10 ² to 2 × 10 ³ Pa Made below. In order to suppress the thermal decomposition of erythritan, it is preferably carried out at a limit temperature at which the polymerization reaction proceeds, and the temperature is 240 to 270 ° C. In addition, following the polycondensation reaction, solid phase polymerization can be performed. After precrystallization is performed by heating at a temperature of about 120 to 200 ° C. for 1 minute or longer, 180 to about a melting point of about −5 ° C. In an atmosphere of an inert gas such as nitrogen gas or / and a reduced pressure of about 1 × 10 ² to 2 × 10 ³ Pa.

  The polyester resin of the present invention can produce various molded products by known molding methods. For example, it is obtained by drying a polyester resin to a moisture content of 200 ppm or less, supplying the polyester resin to an injection molding machine, injection molding into a mold having a predetermined shape at the melting temperature of the resin, and cooling and solidifying in the mold. In addition, the polyester resin of the present invention is preferably used for automotive parts that require heat resistance.

Hereinafter, the present invention will be described in detail by way of examples. The measurement method and evaluation of each physical property followed the following method.
(1) Intrinsic viscosity (IV)
After dissolving about 0.25 g of a polyester resin sample in about 25 mL of a mixture of phenol / 1,1,2,2-tetrachloroethane (weight ratio 1/1) so that the concentration is 1.00 g / dL The solution was cooled to 30 ° C. and held, and the number of seconds of dropping of the sample solution and the solvent alone was measured with a fully automatic solution viscometer (“2CH DT504” manufactured by Chuo Rika Co., Ltd.), and calculated according to the following formula.
IV = ((1 + 4KHηsp) 0.5-1) / (2KHC)
Here, ηsp = η / η0−1, η is the drop time of the sample solution, η0 is the drop time of the solvent alone, C is the sample solution concentration (g / dL), and KH is the Huggins constant. KH adopted 0.33. The sample is dissolved at 110 ° C. for 30 minutes.

(2) Determination of polyester constituents (NMR measurement)
Polyester resin was dissolved in deuterated chloroform / HFIP mixed solution = 70/30 (weight ratio), ¹ H-NMR was measured using AV400M spectrometer manufactured by BRUKER, and each copolymer component of the obtained chart was measured. The copolymer composition (mol%) for all diol components was calculated from the peak integrated intensity of protons.

(3) Extrapolated glass transition start temperature (Tg)
An extrapolated glass transition start temperature (Tg) was measured in accordance with JIS K 7121 “Method for measuring transition temperature of plastic” using a differential scanning calorimeter (DSC822 model manufactured by Mettler). Specifically, about 7 mg of a polyester resin sample is packed in a test container and heated at a heating rate of 20 ° C./min from a nitrogen flow rate of 40 ml / min to a temperature 50 ° C. lower than the transition temperature to 30 ° C. higher than the transition temperature. From the DSC curve, the extrapolated glass transition onset temperature (Tg) was determined.

(4) Heat resistance evaluation (deflection temperature under load)
The polyester resin is dried in a hot air dryer at 130 ° C. for 5 hours (in the case of an amorphous resin, at 60 ° C. for 5 hours or more), the resin moisture content is adjusted to 100 ppm or less, and then an injection pressure is set to 60 MPa using an injection molding machine. A test piece having a length of 110 mm, a thickness of 4.2 mm, and a width of 12.8 mm was molded at a molding temperature of 260 ° C. and a mold temperature of 40 ° C. Using the obtained test piece, the deflection temperature under load at a load of 0.45 MPa (4.6 kgf / cm ² ) was measured according to JIS K 7191 “Test method for deflection temperature under plastic load”. When the deflection temperature under load is 70 ° C. or higher, it can be practically used as a molded product.

(5) Transparency (haze)
The polyester resin is dried in a hot air dryer at 130 ° C. for 5 hours (in the case of an amorphous resin, at 60 ° C. for 5 hours or more), the resin moisture content is adjusted to 100 ppm or less, and then an injection pressure is set to 60 MPa using an injection molding machine. A flat plate having a size of 80 mm × 120 mm and a thickness of 2 mm was molded at a molding temperature of 260 ° C. and a mold temperature of 40 ° C. Using the obtained test piece, the haze (haze value) was measured with a haze meter (Nippon Denshoku Co., Ltd. haze meter 300A) according to JIS K 7105 “Testing methods for optical properties of plastics”. If the haze is 1.0% or less, the molded article has good transparency.

Example 1
<Manufacture of polyester resin>
8.55 kg of terephthalic acid (hereinafter referred to as TPA) and 0.27 kg of erythritan and 3.83 kg of ethylene glycol (hereinafter referred to as EG) so that the molar ratio of the glycol component to the acid component is 1.2 The mixture was charged into a stainless steel autoclave equipped with a distillation tube and subjected to esterification under conditions of 250 ° C. and 200 kPa for 5 hours. After completion of the esterification reaction, 120 ppm of germanium dioxide catalyst, 8 ppm of titanium tetrabutoxide catalyst, and 32 ppm of triethyl phosphate were added to the obtained polymer, and a polycondensation reaction was performed at 270 ° C. and a reduced pressure of 100 Pa. The germanium dioxide catalyst, titanium tetrabutoxide catalyst and triethyl phosphate were all added as an EG solution. Regarding the obtained copolymer polyester resin, the results of measuring the copolymer composition (mol%), intrinsic viscosity IV (dL / g), glass transition temperature Tg (° C.), deflection temperature under load (° C.), and haze (%) are shown. It is shown in Table 1.

(Example 2 to Example 10)
In Example 1, evaluation was performed in the same manner as in Example 1 except that the amounts of TPA, EG and erythritan charged and the melt polycondensation time were changed as shown in Tables 1 to 3 and Table 5. In Example 10, the molar ratio of the glycol component to the acid component was set to 1.0. The results are shown in Tables 1 to 3 and Table 5.

(Example 10)
The pelletized copolyester resin obtained in Example 1 was crystallized at 100 ° C. for 8 hours in a nitrogen atmosphere, and then solid phase polycondensation time shown in Table 4 at 195 ° C. in a nitrogen atmosphere. Polycondensation was performed. Table 4 shows the intrinsic viscosity and molded product evaluation results of the obtained resin.

Example 11
Table 4 shows the results of evaluation conducted in the same manner as in Example 5 except that the melt polycondensation time was changed to the time shown in Table 4 in Example 5.

(Example 12)
In Example 7, solid phase polycondensation was carried out at the solid phase polycondensation time described in Table 4 using the pelletized copolymer polyester resin obtained in Example 2 instead of the resin obtained in Example 1. went. Table 4 shows the intrinsic viscosity and molded product evaluation results of the obtained resin.

(Comparative Example 1)
In Example 1, tests and evaluations were conducted in the same manner as in Example 1 except that 8.64 kg of TPA and 3.88 kg of EG were charged and erythritan was changed so as not to be used. The results are shown in Table 5.

(Comparative Example 2)
In Example 1, the test was conducted in the same manner as in Example 1 except that TPA 7.60 Kg, isophthalic acid 1.04 kg, EG 3.88 kg were charged, and erythritan was changed not to be used. (Isophthalic acid copolymerization amount: 12 mol%)
The results are shown in Table 5.

  From the above Examples and Comparative Examples, it can be seen that the copolymerized polyester resin of the present invention has excellent heat resistance and good transparency.

Claims (5)

30 containing a constitutional unit derived from a dihydroxy compound represented by the following general formula (1) and a constitutional unit derived from a dicarboxylic acid, and a weight ratio of phenol and 1,1,2,2-tetrachloroethane of 30 in a 1: 1 solution. The intrinsic viscosity at a concentration of 1.00 g / dl at 0 ° C. is in the range of 0.36 to 0.85 dl / g, and the content ratio of the structural unit derived from the dihydroxy compound represented by the following general formula (1) is: The polyester resin which is 30-100 mol% with respect to the structural unit derived from all the diol components.

The polyester resin according to claim 1, further comprising a structural unit derived from at least one compound selected from the group consisting of ethylene glycol, diethylene glycol, 1,4-butanediol, and 1,4-cyclohexanedimethanol. The polyester resin according to claim 1, wherein the dicarboxylic acid is terephthalic acid. The polyester resin according to claim 1 or 2, wherein the dicarboxylic acid is 1,4-cyclohexanedicarboxylic acid. The intrinsic viscosity at a concentration of 1.00 g / dl at 30 ° C in a 1: 1 weight ratio solution of phenol and 1,1,2,2-tetrachloroethane is in the range of 0.50 to 0.80 dl / g. The polyester resin according to any one of 1 to 4 .