JPH11349795A - Biodegradable polyester resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a biodegradable polyester resin composition capable of improving the biodegradability of an aliphatic polyester resin, and hardly causing draw down at the time of vacuum molding, blow molding or inflation molding. SOLUTION: This biodegradable polyester resin composition comprises an aliphatic polyester resin, a polycaprolactone and an inorganic additive. The ratio of the amount of the aliphatic polyester resin to the amount of the polycaprolactone is regulated so as to be 100 pts.wt. to 1-200 pts.wt., and the ratio of the total amount of the aliphatic polyester resin and the polycaprolactone to the amount of the inorganic filler is regulated so as to be (95-50) wt.% to (5-50) wt.%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a biodegradable polyester resin composition for vacuum molding, blow molding, inflation molding and the like. More specifically, while containing an aliphatic polyester resin having a relatively low biodegradability or an aliphatic polyester resin containing a urethane bond, it is also more excellent in biodegradability than itself, and is vacuum-formed, blow-molded or inflationed. The present invention relates to a biodegradable polyester resin composition that does not easily draw down during molding.

[0002]

2. Description of the Related Art Conventionally, plastics such as polyolefins are characterized by stability and durability, and are characterized by packaging materials,
It is used in building materials, automobiles and various other fields, and is consumed in large quantities. Disposal methods after their use include incineration and landfill disposal.However, hardly decomposable resins such as polyolefins and polyvinyl chloride can damage incinerators due to high calorific value during incineration. In addition, the generation of harmful waste gas becomes a problem, while the landfill disposal poses a problem of environmental pollution caused by remaining in the environment forever.

[0003] Therefore, natural materials such as biocellulose and starch-based plastics, low-substituted cellulose esters, natural polyesters produced by microorganisms, and aliphatic polyester resins produced by chemical synthesis are used as biodegradable plastics. Etc. are being studied. Among these, aliphatic polyester resins obtained by chemical synthesis are relatively well-balanced in terms of processability, cost, mechanical properties, water resistance, etc., and are attracting attention as easy-to-use resins for various applications. Is mentioned.

The aliphatic polyester resin is represented by a polyester resin obtained by polycondensation of an α, ω-functional aliphatic alcohol and an α, ω-functional aliphatic dicarboxylic acid, but generally has a low melting point. However, it cannot be used as a substitute for conventional polyolefins. However, it is known that certain polyester resins have a melting point of 100 ° C. or higher and have thermoplasticity, and synthesis studies have been conducted.
That is, polyester resin obtained from succinic acid and 1,4-butanediol, polyester resin obtained from succinic acid and ethylene glycol, polyester resin obtained from oxalic acid and neopentyl glycol, oxalic acid and 1,4-butanediol The obtained polyester resin and the polyester resin obtained from oxalic acid and ethylene glycol correspond to them. Of these, polyester resins obtained from oxalic acid have particularly poor heat stability,
Although it does not reach a high molecular weight, the polyester resin obtained from succinic acid has relatively good thermal stability, and synthesis has been devised. However, even with these succinic aliphatic polyester resins, when polycondensation is carried out using a general apparatus, it is difficult to obtain a high molecular weight, and it is difficult to obtain a resin having practical mechanical strength.

[0005] Therefore, it has been practiced to increase the molecular weight of the hydroxyl group of the polyester resin by a urethane bond using a polyisocyanate or the like. As the polyisocyanate used here, hexamethylene diisocyanate and the like are often used because aliphatic ones have better biodegradability than aromatic ones. In this way,
At present, low-molecular-weight aliphatic polyester resins are made to have a high molecular weight, and mechanical properties are ensured so as to be compatible with processing such as injection molding, blow molding, fiberization, and film formation.

However, even with these aliphatic polyester resins, when the crystallinity is high, or when a urethane bond is introduced into the resin molecule as described above, the biodegradability by microorganisms usually decreases. This means that biodegradation proceeds from the amorphous portion of the resin, and the crystalline portion is known to be difficult to decompose and remain easily.Also, even if polycaprolactone polyol having excellent biodegradability is used as the polyol, polyisocyanate The biodegradability of caprolactone polyurethane using hexamethylene diisocyanate as
It is clear from the result that when evaluated in a decomposition test in activated sludge specified in IS K6950, almost no decomposition is observed. Such a tendency is also observed in a urethane bond-containing resin having a relatively low density. Therefore, a small amount of urethane of a few weight%, which originally contains a biodegradable polyester resin for increasing the molecular weight. The presence of the bond often causes a decrease in biodegradability. In fact, the number average molecular weight is 10,000
JIS K6950 defines a polyester resin obtained by connecting 4 to 5 molecular terminal hydroxyl groups of a succinic polyester resin having a molecular weight of about 00 to a number average molecular weight of 40,000 to 50,000 by using a polyisocyanate. When evaluated by a decomposition test in activated sludge, an evaluation result of poor decomposition is obtained.

Therefore, Japanese Patent Application Laid-Open No. 9-67513 discloses that
Polycaprolactone is added to 100 parts by weight of an aliphatic polyester resin having a high molecular weight by aliphatic isocyanate.
A polyester resin composition having improved biodegradability, comprising -200 parts by weight, is disclosed. A single aliphatic polyester resin shows biodegradability in an environment where bacteria that efficiently decompose it exist, but decomposes the kneaded resin by blending and kneading polycaprolactone with better degradability. In the case of a single resin, the probability that bacteria exist in the environment increases, and once decomposition begins, the surface area increases, the surface becomes hydrophilic, and an environment in which bacteria can grow easily is created. Thus, the decomposability is improved. However, when vacuum molding, blow molding, inflation molding, or the like is performed using such a resin, there has been a problem that the resin melted during the molding is drawn down.

[0008]

Accordingly, the present invention relates to an aliphatic polyester resin which is not relatively biodegradable by itself or an aliphatic polyester resin containing a small amount of urethane bonds (hereinafter, unless otherwise specified, both are used). It is an object of the present invention to provide a biodegradable polyester resin composition which improves the biodegradability of the polyester resin (hereinafter simply referred to as "aliphatic polyester resin") and is hardly drawn down during vacuum molding, blow molding or inflation molding.

[0009]

The inventor of the present invention has proposed that polycaprolactone is added in an amount of 1 to 200 parts by weight per 100 parts by weight of an aliphatic polyester resin having a high molecular weight by an aliphatic isocyanate.
By adding a specific amount of an inorganic filler such as talc to the biodegradable polyester resin comprising parts by weight, vacuum molding, blow molding, or a biodegradable polyester resin composition that is difficult to draw down during inflation molding is obtained. The inventors have found that the present invention has been completed and completed the present invention.

That is, a first aspect of the present invention comprises an aliphatic polyester resin, polycaprolactone and an inorganic additive, wherein the ratio of the aliphatic polyester resin to polycaprolactone is 100 parts by weight to 1 to 200 parts by weight, Provided is a biodegradable polyester resin composition wherein the ratio of the total of the polyester resin and the polycaprolactone to the inorganic additive is 95 to 50% by weight to 5 to 50% by weight. A second aspect of the present invention provides the biodegradable polyester resin composition according to the first aspect, wherein the aliphatic polyester resin is a polyester resin containing succinic acid and / or adipic acid as a dicarboxylic acid component. A third aspect of the present invention provides the biodegradable polyester resin composition according to the first or second aspect of the present invention, wherein the aliphatic polyester resin is a polyester resin containing 1,4-butanediol as a diol component. A fourth aspect of the present invention provides the biodegradable polyester resin composition according to any one of the first to third aspects of the present invention, wherein the aliphatic polyester resin is obtained by increasing the molecular weight of a polyester resin with an aliphatic diisocyanate compound. . A fifth aspect of the present invention provides the biodegradable polyester resin composition according to any one of the first to fourth aspects, wherein the inorganic additive is talc.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Aliphatic Polyester Resin The aliphatic polyester resin used in the present invention is not particularly limited, but has a melting point of 100 ° C. or higher, has thermoplasticity, has relatively low biodegradability. Preferably not high, polyester resin obtained from the succinic acid and 1,4-butanediol, polyester resin obtained from succinic acid and ethylene glycol, polyester resin obtained from oxalic acid and neopentyl glycol, oxalic acid and 1, Examples thereof include a polyester resin obtained from 4-butanediol and a polyester resin obtained from oxalic acid and ethylene glycol. Particularly preferred is a polyester resin obtained from succinic acid and 1,4-butanediol. The number average molecular weight of the aliphatic polyester resin is preferably 20,000 or more, more preferably 40,000 or more. There is no particular upper limit, but practically about 500,000 can be used.

As the aliphatic polyester resin used in the present invention, those containing a urethane bond can be used. The aliphatic polyester resin containing a urethane bond is obtained by increasing the molecular weight of the aliphatic polyester resin, preferably with an aliphatic diisocyanate compound. Examples of the aliphatic diisocyanate compound include hexamethylene diisocyanate and lysine diisocyanate methyl ester {OCN- (CH ₂ ) ₄ -CH (-NCO) (-COOC
H ₃ )}, trimethylhexamethylene diisocyanate, etc., among which hexamethylene diisocyanate is preferred. The preferred number average molecular weight of the aliphatic polyester resin containing a urethane bond is 20,0.
The range is at least 00, more preferably at least 40,000. Examples of the aliphatic polyester resin containing a urethane bond include Bionole # 1000 and # 3 manufactured by Showa Polymer Co., Ltd.
000, # 6000 series.

Polycaprolactone The polycaprolactone used in the present invention is obtained by subjecting ε-caprolactone to ring-opening polymerization of ε-caprolactone by a conventional method using an active hydrogen-containing compound such as an alcohol as an initiator. The functional number of the initiator is not particularly limited,
Bifunctional or trifunctional ones can be preferably used. The molecular weight of polycaprolactone can be used from low molecular weight to high molecular weight, but when using low molecular weight polycaprolactone, the amount of addition is limited because the heat resistance and mechanical strength of the kneaded resin decrease greatly. Merits such as a decrease in the melt viscosity of the composition and an improvement in moldability appear. However, it is more preferable to use polycaprolactone having a high molecular weight, since the compounding ratio can be increased, and all of heat resistance, mechanical properties, and biodegradability can be highly balanced. Specifically, the number average molecular weight is 1,000 to 200,
000, more preferably 5,000 to 100,000 polycaprolactone can be preferably used. In addition, 200,00
Although those having a number average molecular weight higher than 0 can be used without problems, it is difficult to obtain such a polycaprolactone having a very high molecular weight, which is not practical. Also,
The polycaprolactone to be used contains, in addition to ε-caprolactone homopolymer, comonomer constituent units such as valerolactone, glycolide and lactide, for example, 20 mol%.
The copolymers contained below can also be used. Examples of polycaprolactone include PCLH manufactured by Daicel Chemical Industries, Ltd.
7, PCLH4, PCLH1 and the like.

The mixing ratio of the aliphatic polyester resin and the polycaprolactone depends on the molecular weight of both, and the required biodegradability.
Parts by weight, more preferably 5 to 50 parts by weight, particularly preferably 20 to 50 parts by weight.
The range is 40 parts by weight.

When the aliphatic polyester resin and the polycaprolactone are kneaded, it is preferable that they are compatible with each other from the viewpoint of the mechanical properties of the resin composition obtained by kneading. For example, a compatibilizer such as a copolymer of a kneaded resin component and a polycaprolactone component,
For example, addition of a resin having a polarity intermediate between the two can also be preferably used.

The biodegradable polyester resin composition of the present invention may contain various additives such as calcium carbonate, mica, calcium silicate, white carbon, asbestos, and porcelain clay as long as the biodegradability of the resin component is not impaired. ), Inorganic fillers such as glass fibers can be added. By adding an inorganic filler, the biodegradability is further improved and the melt strength (viscosity) is increased, so that drawdown during melt molding is prevented, and moldability such as vacuum molding, blow molding, and inflation molding is improved. improves. The weight ratio of the inorganic filler / (total of the aliphatic polyester resin and polycaprolactone) to the total amount of the aliphatic polyester resin and polycaprolactone is 5 to 50/95.
-50, preferably 10-45 / 90-55, more preferably 20-40 / 80-60, particularly preferably 25-90.
35/75 to 65. If the amount of inorganic filler is too large,
If the resin blows powder, if it is too small, drawdown, necking, thickness unevenness, and unevenness will be noticeable in molding.

As a method for kneading the polycaprolactone, the aliphatic polyester resin and the inorganic filler, a general method can be preferably used. Specifically, a raw resin pellet, a powder, a solid strip and the like are mixed with a Henschel mixer or a ribbon mixer. Dry mixing with a single-screw or twin-screw extruder, Banbury mixer,
It can be supplied to a known melt mixer such as a kneader or a mixing roll and melt-kneaded. Further, even when liquid polycaprolactone is added, kneading can be performed in the same manner.

The biodegradable polyester resin composition provided by the present invention has a degradation rate of 20%, preferably more than 30% after cultivation in municipal sewage sludge for 4 weeks specified in JIS K6950. Further, the biodegradable polyester resin composition provided by the present invention can be used for a wide range of applications such as films and vacuum / pressure molded products as alternatives to conventional polyolefins. In particular, it is preferable to use it for articles that are easily left in the environment.

The method for evaluating the biodegradability of a sample is described in JIS.
There are various methods such as using activated sludge according to K6950, burial in soil, immersion in seawater or rivers, evaluation in compost, and the like. JIS K6950 that there is
Perform according to.

[0020]

The present invention will be described in more detail with reference to the following examples, which should not be construed as limiting the present invention.

[Examples 1 to 3 and Comparative Example 1] (Extrusion molding) Vionole # 1001 (succinic acid / 1,4-butanediol copolymer, manufactured by Showa Polymer Co., Ltd.) as a polyester resin and polycaprolactone "PCLH7" (manufactured by Daicel Chemical Industries, Ltd., number average molecular weight 70,000)
And talc were blended in a weight ratio shown in Table 1, and then supplied to a Labo Plastomill and kneaded at 150 ° C. and 30 rpm. After the torque stabilizes, heat and knead for another 10 minutes,
The obtained resin composition was extruded into a sheet. Extrusion molding conditions Cylinder temperature: 160 ° C Screw rotation speed: 60 rpm Resin pressure: 210-260 kg / cm ² Roll temperature: 60 ° C Roll speed: 0.5 m / min Sheet: width 250 mm, thickness 0.5 mm The results are shown in Table 1. Show. As a result, when talc was not filled, necking and thickness unevenness were remarkable, and it was difficult to extrude a sheet at a die lip opening of 1.2 mm even if the extrusion temperature was lowered to 140 ° C or 120 ° C.

[0022]

[Table 1]

[Examples 4 to 6 and Comparative Example 2] (Vacuum molded sheet) Vionore # 3001 (succinic acid / adipic acid / 1,4-butanediol copolymer, manufactured by Showa Polymer Co., Ltd.) as a polyester resin And polycaprolactone "PCLH
7 "(manufactured by Daicel Chemical Industries, Ltd., number average molecular weight 70,
000) and talc in a weight ratio shown in Table 2 and supplied to Labo Plastomill at 150 ° C. and 30 rpm.
And kneaded. After the torque was stabilized, the mixture was heated and kneaded for another 10 minutes, and the obtained resin composition was vacuum formed by a single-shot sheet forming machine. Vacuum forming conditions Molding temperature: 110 ° C. Cooling time: 5 seconds Sheet: 250 × 250 mm, thickness 0.5 mm The results are shown in Table 2. As a result, when talc was not filled, drawdown was large at a molding temperature of 110 ° C., and vacuum forming was difficult, and molding was possible at 95 ° C., but mold release properties were poor, and cooling was lower than that with talc. Time had to be more than doubled.

[0024]

[Table 2]

The heat shrinkage stress was determined from the peak top at 120 ° C. using a melten rheometer (extension viscometer) manufactured by Toyo Seiki Co., Ltd. As a result, those containing talc have a large heat shrinkage stress, and it is difficult for the molten resin to draw down during vacuum molding or the like.

[Example 7 and Comparative Example 3] (Biodegradability of extruded product) Sheet obtained in Example 2 (Bionole # 1001 / polycaprolactone "PCLH7" / talc = 49/21)
/ 30) was measured for biodegradability. The biodegradability result after 28 days was 81%. On the other hand, the biodegradability of the sheet (Bionole # 1001 / polycaprolactone “PCLH7” / talc = 49/21/0) obtained in Comparative Example 1 was measured. The biodegradability results after 28 days are 75%
Met. The results are shown in FIG. As a result, the effect of improving the biodegradability by talc kneading is observed.

Example 8 and Comparative Example 4 43.8 g of dimethyl succinate (Mw = 146), 29.1 g of 1,4-butanediol, 0.02 g of tetraisopropyl titanate
Into a flask equipped with a stirrer, a diversion tube, a gas introduction tube, and a decompression tube, and heated to 200 ° C. at 1 to 0.5 mmHg while gradually reducing the pressure at 190 ° C. for 2 hours under a normal pressure of nitrogen atmosphere. And stirred for 8 hours.
The temperature was raised to 210 to 220 ° C. with mmHg and stirred for 5 hours,
Methanol and excess 1,4-butanediol were distilled off from the system to synthesize a polyester resin. The number average molecular weight of the polyester resin was about 38,000, and the weight average molecular weight was about 75,000. 100 parts by weight of a high molecular weight polyester resin containing no urethane bond, 11.1 parts by weight of polycaprolactone “PCLH7”, talc 4
A sheet was prepared in the same manner as in Example 7 using 7.6 parts by weight, and its biodegradability was measured. The biodegradability result after 28 days was 46%. On the other hand, as Comparative Example 4, a sheet was prepared in the same manner as Comparative Example 3 using 100 parts by weight of a high molecular weight polyester resin and 11.1 parts by weight of polycaprolactone "PCLH7", and the biodegradability was measured. 2
The biodegradability result after 8 days was 40%. As a result,
It can be seen that when a high molecular weight polyester containing no urethane bond is used, the biodegradability is improved by mixing talc even if the mixing ratio of polycaprolactone is reduced.

[0028]

According to the present invention, the biodegradability of an aliphatic polyester resin having a relatively low biodegradability by itself or a high molecular weight aliphatic polyester resin having a low biodegradability due to a urethane bond or the like is included. Can be easily improved, and vacuum molding, blow molding, and inflation molding can be performed, and can be used in various fields in place of conventional polyolefins. Therefore, the present invention has a great industrial advantage from the viewpoint of environmental protection.

[Brief description of the drawings]

FIG. 1 is a graph showing the change over time of the biodegradability of an extruded sheet of a kneaded product of a high-molecular-weight polyester / polycaprolactone PH7 / talc according to the present invention. (1) Polyester resin / polycaprolactone PH7 /
Kneaded material of talc (2) Kneaded material of polyester resin / polycaprolactone PH7

Claims (5)

[Claims] 1. An aliphatic polyester resin, polycaprolactone and an inorganic additive, wherein the ratio of aliphatic polyester resin to polycaprolactone is 100 parts by weight to 1-2 parts.
A biodegradable polyester resin composition wherein the ratio of the total amount of the aliphatic polyester resin and the polycaprolactone to the inorganic additive is 95 to 50% by weight to 5 to 50% by weight. 2. The biodegradable polyester resin composition according to claim 1, wherein the aliphatic polyester resin is a polyester resin containing succinic acid and / or adipic acid as a dicarboxylic acid component. 3. The biodegradable polyester resin composition according to claim 1, wherein the aliphatic polyester resin is a polyester resin containing 1,4-butanediol as a diol component. 4. The biodegradable polyester resin composition according to claim 1, wherein the aliphatic polyester resin is obtained by increasing the molecular weight of the polyester resin with an aliphatic diisocyanate compound. 5. The method according to claim 1, wherein the inorganic additive is talc.
The biodegradable polyester resin composition according to any one of the above.