JP2007112822A - Aromatic polyester composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a composition capable of being suitably used as a material of a solid molded article equipped with biodegradability and mechanical strength simultaneously at high levels. <P>SOLUTION: This aromatic polyester composition is obtained by melting and kneading a polyester copolymer consisting of a combination of a specific aromatic dicarboxylic acid residue, an aliphatic dicarboxylic acid residue and a diol residue with a mixed composition of cellulose with a polyalkylene glycol. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  TECHNICAL FIELD The present invention relates to a biodegradable material using a renewable resource, and more particularly to a biodegradable molding material having a low environmental load, comprising a composition of an aromatic polyester and a renewable resource.

  In recent years, from the viewpoint of low environmental impact, materials that use renewable and sustainable biomass resources have been demanded in the field of general-purpose plastics and engineering plastics, and technological development is being promoted to achieve this.

  In particular, bio-derived polymers such as starch and cellulose are useful as resources in terms of production volume and cost, but it is pointed out that they generally have lower heat resistance, workability, and mechanical strength than general-purpose plastics. The

  For this reason, for example, a technology of thermoplasticizing by chemical modification is applied to improve the processability of cellulose. However, derivatization reagents and waste liquids used in the production process are harmful, biodegradable, etc. In particular, problems with environmental aspects such as the loss of the inherent biocompatibility of cellulose and the difficulty of production when the raw material is of low purity such as wood are pointed out.

  In terms of improving thermophysical properties and mechanical properties, there is a method of blending cellulose with current general-purpose plastics, and it has been conventionally known that compositions having some degree of physical property improvement and thermoplasticity have been achieved. However, such a method requires that the plastic to be blended has an affinity for cellulose, and is limited to polar resins such as polyvinyl alcohol and polyacrylic resins, and resins having relatively low heat resistance such as aliphatic polyesters. In many cases (for example, see Patent Documents 1, 2, 3, etc.), the use of the blend is limited to a narrow range such as clothing fibers and medical films.

  In order to obtain higher heat resistance and strength, the use of chemically modified cellulose such as cellulose acetate for blending with an aromatic polymer has also been proposed (for example, Patent Document 4). Problems arise from.

  In addition, as a means for thermoplasticizing cellulose without chemically modifying cellulose and without generating waste, a method of mixing with a thermoplastic polymer and dry-mechanical grinding is disclosed (for example, patents). Literature 5 etc.). Since the cellulose composition obtained here is thermoplastic compared to cellulose alone, it can form melt blends with various resins in a wide temperature range. However, when the biodegradability is increased, there is a problem that the mechanical strength of the molded product may be lowered.

Japanese Patent Laid-Open No. 11-117120 Japanese Patent Laid-Open No. 10-316767 JP 2001-335710 A Japanese Patent No. 2732554 Japanese Patent No. 3099064

  An object of the present invention is to provide a composition that can be used suitably as a material for a three-dimensional molded article, which solves the problems of the conventional techniques and has both high biodegradability and mechanical strength. There is.

  As a result of intensive studies in view of the prior art, the present inventors have found that a copolymer of an aliphatic ester component, a polyalkylene glycol derivative having a specific structure, and an aromatic ester component is thermoplasticized by mechanical grinding. It has been found that an environmentally low load resin can be obtained by using a renewable resource that has heat resistance and mechanical strength that can be easily melted and kneaded with liquefied cellulose, and can be adapted to general-purpose plastics applications. It came.

That is, the object of the present invention is to
A main repeating unit is an aromatic dicarboxylic acid residue represented by the following general formula (1), an aliphatic dicarboxylic acid residue represented by the following general formula (2), and a diol represented by the following general formula (3) A mixed composition of a polyester copolymer (A), cellulose, and polyalkylene glycol, which is a combination of a residue and a diol residue represented by the following general formula (4) and / or the following general formula (5) ( B) and an aromatic polyester composition obtained by melt-kneading.

  The aromatic polyester composition of the present invention is extremely effective as a material for molded products that require a good balance between heat resistance and biodegradability.

Hereinafter, the present invention will be described in detail.
The aromatic polyester composition of the present invention is a composition comprising the following polyester copolymer (A) and mixed composition (B).

  Here, the polyester copolymer (A) has an aromatic dicarboxylic acid residue whose main repeating unit is represented by the following general formula (1) and an aliphatic dicarboxylic acid residue represented by the following general formula (2): And a diol residue represented by the following general formula (3) and a diol residue represented by the following general formula (4) and / or the following general formula (5).

In the general formula (1), Ar ¹ is an arylene group having 6 to 20 carbon atoms which may have a substituent, specifically, a phenylene group, a methylphenylene group, an ethylphenylene group, a methoxyphenylene group, an ethoxy group. Examples include a phenylene group, a dimethylphenylene group, a diethylphenylene group, a dimethoxyphenylene group, a diethoxyphenylene group, a naphthylene group, and the like. A phenylene group is a preferred example because of its availability.

In the general formula (2), R ² is a divalent aliphatic hydrocarbon group having 1 to 10 carbon atoms which may have a branched structure. Specifically, methane-1,1-diyl group, ethane- 1,1-diyl group, ethane-1,2-diyl group, propane-1,1-diyl group, propane-1,2-diyl group, propane-1,3-diyl group, butane-1,3-diyl Group, butane-1,4-diyl group, pentane-1,5-diyl group, pentane-1,4-diyl group, hexane-1,6-diyl group, hexane-1,5-diyl group and the like. However, ethane-1,2-diyl group or butane-1,2-diyl group is preferable because the obtained aromatic polyester composition has good heat resistance and the raw material can be obtained at low cost. It is done.

  The ratio of the aromatic dicarboxylic acid and the aliphatic dicarboxylic acid component represented by the general formulas (1) and (2) greatly affects the melting point of the polyester copolymer (A), and the aromatic polyester composition of the present invention The ratio is determined so that the mixture composition (B) has a sufficient melting point so that the mixture composition (B) does not undergo significant thermal deterioration during melt-kneading with the mixture composition (B) while having sufficient heat resistance. Preferably, the mixing ratio of the polyester copolymer (A) to the mixed composition (B) is in the range of (3: 7) to (7: 3) by weight.

That is, the aromatic dicarboxylic acid residue is preferably in the range of 65 to 85 equivalents, more preferably in the range of 70 to 80 equivalents with respect to 100 equivalents of the total amount of dicarboxylic acid residues forming the copolyester. . On the other hand, the aliphatic dicarboxylic acid residue is preferably in the range of 15 to 35 equivalents, particularly preferably in the range of 20 to 30 equivalents.
When it is in the above range, both heat resistance and biodegradability can be achieved at a higher level.

In the general formula (3), R ³ is a divalent aliphatic hydrocarbon group having 1 to 10 carbon atoms, specifically methane-1,1-diyl group, ethane-1,1-diyl group, ethane- 1,2-diyl group, propane-1,2-diyl group, propane-1,3-diyl group, butane-1,3-diyl group, butane-1,4-diyl group, pentane-1,5-diyl Group, pentane-1,4-diyl group, hexane-1,6-diyl group, hexane-1,5-diyl group and the like, and the point that the aromatic polyester composition has good heat resistance, and further the raw material is An ethane-1,2-diyl group is a preferred example because it can be obtained inexpensively.

In the general formula (4), R ³ is a trivalent aliphatic hydrocarbon group having 1 to 10 carbon atoms, specifically, methane-triyl group, ethane-1,1,2-triyl group, propane-1, 1,3-triyl group, propane-1,2,3-triyl group, butane-1,1,4-triyl group, butane-1,2,4-triyl group and the like, and polyester copolymer (A ) Has good heat resistance, a preferred example is a propane-1,2,3-triyl group.

R ⁴ is a C 1-10 divalent aliphatic hydrocarbon group, specifically, methane-1,1-diyl group, ethane-1,1-diyl group, ethane-1,2-diyl. Group, propane-1,3-diyl group, propane-1,2-diyl group, butane-1,3-diyl group, butane-1,4-diyl group, pentane-1,5-diyl group, pentane-1 , 4-diyl group, hexane-1,6-diyl group, hexane-1,5-diyl group and the like, and the aromatic polyester composition has good biodegradability, and further, raw materials can be obtained at low cost. From the standpoint, a preferred example is an ethane-1,2-diyl group.

  In addition, n in the said General formula (4) is 1-100 as an average value, Preferably it is 5-70 in order for a polyester copolymer to have favorable heat resistance, More preferably, it is 5-50. More preferably, it is 9-45. When n exceeds 100, the compatibility with the polymer main chain is lowered and the desired heat stability cannot be obtained. However, in the present invention, the average value of n may be in the range of 1 to 100. Even if it contains more than 100 components, the average value may be in the range of 1 to 100. In addition, n defined as said average value can be calculated | required from the number average molecular weight of the oligomer measured by gel permeation chromatography, The value can be normally represented by the real number including a decimal point.

  In addition, the diol component of the general formula (4) exhibits the effect that the copolyester is mixed with the cellulose composition quickly and uniformly because the side chain structure has a strong affinity with cellulose. From that viewpoint, the copolymerization ratio of the diol component is defined by the weight fraction with respect to the polyester, and is in the range of 1 to 20 parts by weight with respect to 100 parts by weight of the copolymerized polyester. When less than the said range, an effect with respect to mixing with a cellulose composition is low, and desired biodegradability is not acquired. On the other hand, when the above range is exceeded, the copolyester is not preferred because it does not have the desired heat resistance.

In the general formula (5), R ⁵ is a divalent aliphatic hydrocarbon group having 1 to 5 carbon atoms which may have a branched structure, specifically a methane-1,1-diyl group, ethane- 1,1-diyl group, ethane-1,2-diyl group, propane-1,3-diyl group, propane-1,2-diyl group, butane-1,3-diyl group, butane-1,4-diyl Group, pentane-1,5-diyl group, pentane-1,4-diyl group and the like, and since the polyester composition has good biodegradability, methane-1 A 1-diyl group is a preferred example.

  In the present invention, the diol component represented by the general formula (4) and the general formula (5) has an effect of quickly mixing the polyester copolymer (A) and the mixed composition (B), and the copolymer polyester. It has the effect of improving the heat resistance stability, and further the effect of remarkably improving the biodegradability of the polyester composition.

  From the viewpoint of the combination of the entire composition, the polyester copolymer (A) of the present invention is specifically derived from polyoxyethylenepropanediol having a polyoxyalkylenepropanediol residue having a weight average molecular weight of 300 to 2500. The alkylene diol residue is an ethylene glycol residue, the carbohydrate-derived ether diol residue is an isosorbide residue, the aliphatic dicarboxylic acid residue is a succinic acid residue, and the entire diol residue is When it is 100 mol%, the polyoxyalkylenepropanediol residue is in the range of 0.25 to 5 mol%, the alkylenediol residue is in the range of 75 to 98 mol%, and the saccharide-derived ether diol residue is 5 to 5 mol%. What is in the range of 25 mol% and in which the dicarboxylic acid residue is in the range of 10 to 40 mol% is practically cost-effective. Such dynamics have thermal properties, and preferred to provide good biodegradability.

  The reduced viscosity of the polyester copolymer (A) in the present invention is in the range of 0.5 to 2.0 dl / g. If the reduced viscosity is less than 0.5 dl / g, the desired heat resistance cannot be obtained, and if it exceeds 2.0 dl / g, the desired biodegradability cannot be obtained. The reduced viscosity in the present invention is measured at 35 ° C. with respect to a solution obtained by dissolving 120 mg of a sample in 10 ml of a mixed solvent of 1,1,2,2-tetrachloroethane and phenol at a weight ratio of 1: 1.

  The aromatic polyester copolymer of the present invention may be produced by any method, for example, an aromatic dicarboxylic acid corresponding to the general formula (1) and an aliphatic dicarboxylic acid corresponding to the general formula (2) or Manufactured by melt polycondensation of an ester-forming derivative and a diol corresponding to the general formulas (3), (4) and (5) or an ester-forming derivative thereof, preferably in the presence of a transesterification catalyst. Is done.

  At that time, dicarboxylic acids and diols used as raw materials are arbitrarily selected from compounds having a corresponding structure, but they may be recycled from the manufacturing process or waste after use, and the recovered resin. A product regenerated from the product by a method such as depolymerization may be used. If the polyester copolymer to be produced (A) is within the range satisfying the physical properties required for the intended use, use such recycled or recycled raw materials from the viewpoint of achieving low environmental impact. Is preferred.

  Further, the mixed composition (B) of the present invention is a mixture of cellulose and polyalkylene glycol. As a mixing method, a method of mechanically pulverizing with a pulverizer such as various mills is used. It is preferable as a method capable of achieving the above mixing. By performing such a treatment, it is possible to obtain a very high affinity with the polyester copolymer, it can be quickly mixed under relatively mild conditions, and the physical properties of the aromatic polyester composition are impaired. There is no.

  The type of cellulose used for the pulverization treatment is not particularly limited, but the finer the cellulose powder, the more gentle the kneading is possible, so the average particle size is preferably 50 μm or less, more preferably 30 μm or less. .

  Examples of the polyalkylene glycol to be subjected to the pulverization treatment include polyethylene glycol, polypropylene glycol and the like, and polyethylene glycol is preferable from the viewpoint of rapidly producing a thermoplastic composition with cellulose. As the polyalkylene glycol, those having a number average molecular weight in the range of 10,000 to 5,000,000 are used, and preferably 10,000 to 3,000,000 in order to be easily mixed with cellulose and quickly blended with the polyester copolymer (A). It is preferable that

  The pulverization treatment is performed by treating a mixture of cellulose and polyalkylene glycol with a fine powder production apparatus, and any type of apparatus may be used. For example, a ball mill, a planetary ball mill, a stirring ball mill , Vibration mill, rod mill and the like.

  In the present invention, the above-mentioned polyester copolymer (A) and the mixed composition (B) are melt-kneaded to obtain an aromatic polyester composition. Any device can be used for this melt-kneading. For example, a polycondensation reaction apparatus or a uniaxial or biaxial melt kneading extruder may be mentioned as a preferable example.

The present invention will be further described below with reference to examples, but the present invention is not limited to these examples. In addition, the following measurements were performed about the aromatic polyester copolymer manufactured in the Example.
(1) Measurement of melting point (Tm):
The melting point was measured using a 910 differential scanning calorimeter manufactured by Dupont at a rate of 20 ° C./min in a nitrogen gas stream. When the melting point was 190 ° C. or higher, it was determined that the heat resistance was good.
(2) Measurement of reduced viscosity:
The reduced viscosity of the resin was determined by measuring the viscosity at 35 ° C. of a solution obtained by dissolving 120 mg of a sample in 10 ml of a mixed solvent of phenol / tetrachloroethane (volume ratio 50/50). The unit is dl / g.
(3) Biodegradability test:
The biodegradability of the resin was evaluated using a laboratory scale composting apparatus. The disintegration property in the curing compost was visually observed to determine the presence or absence of biodegradability. Hereinafter, a specific procedure will be described.
5 g of each resin was dissolved in 50 ml of phenol: 1,1,2,2-tetrachloroethane = 1: 1 (wt / wt), cast using a 100 μm doctor knife, and dried with a hot air dryer at 80 ° C. A film was obtained.
As a seeding source in a compost container (volume: 11 liters), 1.72 kg of porous wood pieces (Biochip manufactured by Matsushita Electric Works), 0.075 kg of cellulose particles having fine pores (Bioball made by Matsushita Electric Works Co., Ltd.) every day About 1 to 1.5 kg of vegetable scraps are replenished, stirred once every 3 hours for 2 minutes, and manually squeezed once a week, moisture 50-60%, pH 7.5-8.5, The film cut into 50 mm squares was put into compost kept at a temperature of 45 to 55 ° C., and the film was sampled after a predetermined time.
After the film deposits were removed by water washing and air-dried, the film surface appearance was visually observed and the film weight was weighed. The biodegradability was determined to be high when the weight residual ratio of the film after 10 days of composting was 10% or less (（in the table). Biodegradability was observed when the weight residual ratio was 50% or less (◯ in the table), and when 95% or less, biodegradability was evaluated as low (× in the table).
(4) Mechanical strength:
The mechanical strength of the molded product was evaluated by an Izod impact strength test (notched) according to JIS K6911.

[Example 1]
498.3 parts by weight of dimethyl terephthalate, 41.7 parts by weight of dimethyl succinate, 324.6 parts by weight of ethylene glycol, 71.3 parts by weight of a diol compound represented by the following formula (C), and 64.2 parts by weight of isosorbide The mixture was charged into a three-necked flask equipped with a Vigreux tube, 22 × 10 ⁻² parts by weight of manganese acetate was added as a transesterification reaction catalyst, and transesterification was performed at 180 ° C. to 200 ° C.

Thereafter, 26 × 10 ⁻² parts by weight of antimony oxide as a polycondensation catalyst was added to initiate polymerization, and the temperature was increased from 220 ° C. and 4 MPa to 240 ° C. and 5 Pa over 2 hours. The excess ethylene glycol was reacted and distilled off under reduced pressure to polymerize the polyester copolymer (A). The evaluation results of this polyester copolymer (A) are shown as reference examples in the table.

  Subsequently, 90 parts by weight of cellulose dried at 0.5 Torr and 105 ° C. for 3 hours and 10 parts by weight of polyethylene glycol (Mw = 200000) were pulverized at room temperature and 100 rpm using a rotary ball mill. Performing for a while, a thermoplastic cellulose composition (mixed composition (B)) was obtained.

  After 70 parts by weight of the copolyester (A) was melted at a reduced pressure of 133.3 Pa and 230 ° C., 30 parts by weight of the mixed composition (B) was added and stirred for 15 minutes to obtain an aromatic polyester composition. . The results are shown in Table 1.

[Example 2]
In Example 1, the same operation was performed except that 50 parts by weight of the copolyester (A) and 50 parts by weight of the mixed composition (B) were obtained. The results are shown in Table 1.

[Example 3]
In Example 1, the copolymerized polyester (A) and the mixed composition (B) were dry blended, then charged into a hopper, melt kneaded in a biaxial melt kneading extruder, barrel temperature 230 ° C., screw rotation speed 100 rpm. The discharge strand was air-cooled and then pelletized with a chip cutter to obtain a polyester composition pellet. The results are shown in Table 1.

[Example 4]
In Example 1, 445.5 parts by weight of dimethyl terephthalate, 106.1 parts by weight of dimethyl succinate, 372.8 parts by weight of ethylene glycol, 75.5 parts by weight of diol compound, and the point that no isosorbide was used. The same operation was performed except for this. The results are shown in Table 1.

[Example 5]
In Example 1, 533.5 parts by weight of dimethyl terephthalate, 44.6 parts by weight of dimethyl succinate, 347.5 parts by weight of ethylene glycol, 74.3 parts by weight of isosorbide, and a point in which no diol compound was used. The same operation was performed except for this. The results are shown in Table 1.

[Comparative Example 1]
After melting 100 parts by weight of polyethylene terephthalate (ηsp / c = 0.84) at 280 ° C. in a nitrogen atmosphere, 11 parts by weight of the diol compound (C) is added, and mixed and stirred at 280 ° C. for 30 minutes in a nitrogen atmosphere. It was. Subsequently, the pressure in the system was gradually reduced, and stirring was performed for 1 hour at an internal pressure of 66.7 Pa to obtain a resin. The results are shown in Table 1.

[Comparative Example 2]
In Comparative Example 1, the same operation was performed except that the diol compound (C) was not added. The results are shown in Table 1.

  The aromatic polyester composition of the present invention may be used for any application, but especially for food packaging containers and tableware material applications, moderate strength and heat resistance are required. It can be preferably used as a raw material, and disposable tableware can be cited as a preferred example of the use of the aromatic polyester composition of the present invention from the background that volume reduction by composting and disposal are recently desired from the viewpoint of low environmental load. .

Claims (8)

A main repeating unit is an aromatic dicarboxylic acid residue represented by the following general formula (1), an aliphatic dicarboxylic acid residue represented by the following general formula (2), and a diol represented by the following general formula (3) A mixed composition of a polyester copolymer (A), cellulose, and polyalkylene glycol, which is a combination of a residue and a diol residue represented by the following general formula (4) and / or the following general formula (5) ( An aromatic polyester composition obtained by melt-kneading B).

  The composition according to claim 1, wherein the mixing ratio of the polyester copolymer (A) and the mixed composition (B) is in the range of (3: 7) to (7: 3) by weight.   The composition according to claim 1, wherein the mixed composition (B) is a composition obtained by pulverizing a powder mixture of cellulose and polyalkylene glycol.   The composition according to claim 1, wherein a mixing ratio of the cellulose and the polyalkylene glycol in the mixed composition (B) is (9: 1) to (1: 9) by weight.   The composition according to claim 1, wherein the polyalkylene glycol is polyethylene glycol having a number average molecular weight of 10,000 to 5,000,000.   The ratio of the aromatic dicarboxylic acid residue represented by the general formula (1) and the aliphatic dicarboxylic acid residue represented by the general formula (2) is (9: 1)-(6 The composition of Claim 1 which is: 4). The composition according to claim 1, wherein the aromatic dicarboxylic acid component is represented by the following formula (6), the aliphatic dicarboxylic acid component is represented by the formula (7), and the dihydroxy compound is represented by the formulas (8) and (9).

  A molded article comprising the aromatic polyester composition according to claim 1.