JPH0967513A - Biodegradable polyester resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyester resin composition having improved biodegradability in spite of containing an aliphatic polyester resin which is lowly biodegradable because of its high crystallinity, the existence of urethane bonds, etc. SOLUTION: This biodegradable polyester resin composition comprises 100 pts.wt. aliphatic polyester resin (e.g. a polyester resin made from succinic acid and 1,4-butanediol or a product prepared by heightening the molecular weight of the resin by using hexamethylene diisocyanate) and 1-200 pts.wt. polycaprolactone.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a polyester resin composition having biodegradability. More specifically, the present invention relates to a polyester resin composition which contains an aliphatic polyester resin having a relatively low biodegradability and an aliphatic polyester resin having a urethane bond, but is also excellent in biodegradability than these.

[0002]

2. Description of the Related Art Conventionally, plastics such as polyolefin are characterized by stability and durability.
It is used in building materials, automobiles, and various other fields, and is consumed in large quantities. Examples of the disposal method after use of them include incineration and landfill disposal, but incombustible resins such as polyolefin and vinyl chloride damage the incinerator due to high calorific value during incineration, The generation of hazardous waste gas poses a problem, while on the other hand, in the case of landfill disposal, environmental pollution is a problem because it remains in the environment forever.

Therefore, applications such as biodegradable plastics such as natural material-based biocellulose or plastics mainly composed of starch, low-substituted cellulose ester, polyester synthesized by microorganisms, aliphatic polyester resin and the like have been studied. ing. Of these, workability, cost,
Aliphatic polyester resins obtained by chemical synthesis are mentioned as resins that are relatively well balanced in terms of mechanical properties and water resistance and are easy to use in various applications.

The aliphatic polyester resin is represented by a polyester resin obtained by polycondensation of an α, ω-2 functional aliphatic alcohol and an α, ω-2 functional aliphatic carboxylic acid, but generally has a low melting point. , Cannot be used as a substitute for conventional polyolefins. However, it is known that some polyester resins have a melting point of 100 ° C. or higher and have thermoplasticity, and synthetic studies have been conducted.
That is, a polyester resin obtained from succinic acid and 1,4-butanediol, a polyester resin obtained from succinic acid and ethylene glycol, a polyester resin obtained from oxalic acid and neopentyl glycol, and 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, the polyester resin obtained from oxalic acid has particularly poor thermal stability,
Although it does not reach a high molecular weight, the polyester resin obtained from succinic acid has comparatively good thermal stability, and synthetic methods have been devised. However, even with these succinic acid-based aliphatic polyester resins, when polycondensation is performed 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.

Therefore, the molecular terminal hydroxyl groups of the polyester resin are made to have a high molecular weight by urethane bonding using polyisocyanate or the like. Of the polyisocyanates used here, hexamethylene diisocyanate and the like are often used, because aliphatic type shows better biodegradability than aromatic type. In this way,
Under the current circumstances, low molecular weight aliphatic polyester resins are made to have a high molecular weight to secure mechanical properties and are compatible with processes such as injection molding, blow molding, fiberization, and film formation.

However, even with these aliphatic polyester resins, the crystallinity is high, and when a urethane bond is introduced into the resin molecule as described above, biodegradability by microorganisms usually decreases. This is because it is known that biodegradation proceeds from the amorphous portion of the resin, the crystal portion is difficult to decompose and remains easily, and even when polycaprolactone polyol having excellent biodegradability is used as the polyol, polyisocyanate The biodegradability of caprolactone-based polyurethane using hexamethylene diisocyanate for
It is also clear from the result that when evaluated by a decomposition test in activated sludge specified by IS K6950, almost no decomposition is observed. Since such a tendency is also observed in a resin having a relatively low density of urethane bond, a polyester resin which is originally biodegradable is also included for the purpose of increasing the molecular weight, so that a small amount of urethane such as a few% by weight is used. The presence of the bond is often responsible for the reduced biodegradability. In fact, the number average molecular weight is 10,0
A polyester resin obtained by connecting 4 to 5 molecular terminal hydroxyl groups of a succinic acid-based polyester resin with polyisocyanate to a high molecular weight to a number average molecular weight of 40,000 to 50,000 is defined in JIS K6950. When evaluated in a decomposition test in activated sludge, the evaluation result is persistent.

[0007]

SUMMARY OF THE INVENTION Therefore, according to the present invention, an aliphatic polyester resin which is not relatively biodegradable by itself or an aliphatic polyester resin containing a small amount of urethane bond (hereinafter, unless otherwise distinguished, Simply referred to as “aliphatic polyester resin”).

[0008]

[Means for Solving the Problems] A single resin exhibits biodegradability in an environment in which bacteria that decompose it efficiently exist, but by blending and kneading a resin with better degradability, Due to the fact that the probability that bacteria that decompose the kneaded resin will be present in the environment will increase, and that once the decomposition begins, the surface area will expand, the surface will become hydrophilic, and there will be an environment in which the bacteria will grow easily. In some cases, the decomposability is improved as compared with the case of using a single resin.

The present inventors prefer polycaprolactone having a higher biodegradability to aliphatic polyester resins having a relatively low biodegradability by themselves and polyester resins having a low biodegradability containing a urethane bond. It was found that the biodegradability was remarkably improved by blending and kneading. That is, the degradation rate and content rate of the low biodegradable polyester resin constituting the kneaded resin composition alone, and the degradation rate expected from the degradation rate and content rate of the highly biodegradable polycaprolactone alone are higher. It has been found that a decomposition rate can be obtained. Polycaprolactone has a melting point of 60 ° C.
It is usually considered that the melting point of the entire resin composition will be lowered by kneading this, but by blending / adding a relatively small amount of polycaprolactone that falls within the range of melting point reduction, which is practically no problem, by itself Found that the biodegradability of an aliphatic polyester resin having a relatively low biodegradability or an aliphatic polyester resin containing a urethane bond can be remarkably improved.

That is, in the present invention, 1 to 20 parts of polycaprolactone is added to 100 parts by weight of the aliphatic polyester resin.
The present invention relates to a biodegradable polyester resin composition containing 0 part by weight. Hereinafter, the present invention will be described in detail.

The aliphatic polyester resin used in the present invention is not particularly limited, but has a melting point of 100.
A resin having a thermoplasticity or a resin having a relatively low biodegradability at a temperature of ℃ or more is preferable. A polyester resin obtained from the succinic acid and 1,4-butanediol, a polyester resin obtained from succinic acid and ethylene glycol, and Shu A polyester resin obtained from an acid and neopentyl glycol, a polyester resin obtained from oxalic acid and 1,4-butanediol, a polyester resin obtained from oxalic acid and ethylene glycol, and the like can be exemplified. Particularly preferably, succinic acid and 1, It is a polyester resin obtained from 4-butanediol.

The aliphatic polyester resin containing a urethane bond used in the present invention is obtained by polymerizing the above aliphatic polyester resin preferably with an aliphatic diisocyanate compound. Examples of the aliphatic diisocyanate compound include hexamethylene diisocyanate, lysine diisocyanate methyl ester {OCN- (CH _{2) 4} -
_{CH (-NCO) (- COOCH 3} )}, but trimethylhexamethylene diisocyanate and the like, among others hexamethylene diisocyanate are preferred. The preferred number average molecular weight of the aliphatic polyester resin containing urethane bond is in the range of 20,000 or more, more preferably 40,000 or more.

The polycaprolactone used in the present invention is
For example, it is obtained by carrying out a ring-opening polymerization of ε-caprolactone by a conventional method using active hydrogen such as alcohol as an initiator. The functional number of the initiator is not particularly limited, and 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 low molecular weight polycaprolactone is used, the addition amount is limited because the heat resistance and mechanical strength of the kneading resin decrease significantly, but The melt viscosity of the composition is lowered, and advantages such as improvement in moldability are exhibited. However, it is more preferable to use high molecular weight polycaprolactone because the blending ratio can be increased and heat resistance, mechanical properties, and biodegradability can be well balanced. Specifically, the number average molecular weight is 1,000 to 20.
10,000, more preferably 5,000 to 100,000 polycaprolactone can be preferably used. In addition, 200,
Although those having a number average molecular weight higher than 000 can be used without any problem, it is difficult and unrealistic to obtain polycaprolactone having such a very high molecular weight. In addition to the homopolymer of ε-caprolactone, the polycaprolactone to be used may include valerolactone, comonomer structural units such as glycolide and lactide, for example, 20
A copolymer containing less than or equal to mol% can also be used.

The blending ratio of the aliphatic polyester resin and the polycaprolactone depends on the molecular weight of both and the required biodegradability, but the former is 100 parts by weight and the latter is 1 to 200 parts by weight.
Parts by weight, more preferably 5 to 50 parts by weight, especially 20 to 40 parts by weight.

When the aliphatic polyester resin and the polycaprolactone are kneaded, it is preferable that both are compatible from the viewpoint of mechanical properties of the resin composition obtained by kneading, but if they are not compatible, For example, a compatibilizer such as a copolymer of a resin component to be kneaded and a polycaprolactone component,
For example, addition of a resin having a polarity intermediate between the two can be preferably used.

The biodegradable polyester resin composition of the present invention contains various additives such as calcium carbonate, mica, calcium silicate, white carbon, asbestos, porcelain clay (calcined as long as the biodegradability of the resin component is not impaired. ), An inorganic filler such as glass fiber can be added.

As a kneading method of polycaprolactone and an aliphatic polyester resin, a general method can be preferably used. Specifically, pellets, powders, solid fine particles and the like are dry-mixed with a Henschel mixer or a ribbon mixer, Uniaxial or 2
It can be melt-kneaded by supplying it to a known melt mixer such as a shaft extruder, Banbury mixer, kneader or mixing roll. Further, even when liquid polycaprolactone is added, the kneading can be performed by the same method.

The biodegradable polyester resin composition provided by the present invention has a decomposition rate of 20%, preferably more than 30% after 4 weeks of culturing in municipal sewage sludge specified in JIS K6950 below. Further, the biodegradable polyester resin composition provided by the present invention can be used for a wide range of applications as a substitute for conventional polyolefins. It is particularly preferable to use it for the purpose of articles that are easily left in the environment.

The biodegradability evaluation method of the sample is JIS
There are various methods such as the method of using activated sludge according to K6950, burial in soil, immersion in seawater or river, evaluation in compost, etc., but in the following examples, the degradability in general fields and correlation JIS K6950 that is said to have
It was carried out according to.

[0020]

EXAMPLES The present invention will be described in detail below with reference to examples, but the present invention is not limited thereto.

(Example 1) Succinic acid (Mw = 118) 3
5.4 g and 1,4-butanediol (Mw = 90) 2
9.1 g of tetraisopropyl titanate and 0.02 g of tetraisopropyl titanate were placed in a flask equipped with a stirrer, a diversion tube, a gas introduction tube, and a decompression tube, and under a nitrogen atmosphere normal pressure at 200 ° C. for 2 hours, followed by gradually reducing the pressure, After reaching 0.5 mmHg or less, the mixture was stirred at 200 ° C. for 5 hours, and water and excess 1,
4-Butanediol was distilled off from the system to synthesize a polyester resin. Next, under atmospheric pressure of nitrogen atmosphere, 200 ° C
Then, 0.8 g of hexamethylene diisocyanate (Mw = 168) was added to synthesize a polyester resin (A) having an increased molecular weight. The number average molecular weight of the polyester resin (A) is about 44,000 in terms of standard styrene by GPC.
0, the weight average molecular weight was about 185,000. Kneading of the polyester resin (A) and polycaprolactone and molding of the sheet sample were performed by the following methods. 100 parts by weight of polyester resin (A) and 11.1 parts by weight of polycaprolactone "PCLH7" (manufactured by Daicel Chemical Industries, Ltd., number average molecular weight 70,000) were supplied to a Labo Plastomill and kneaded at 150 ° C and 30 rpm, After the torque was stabilized, the mixture was heated and kneaded for 10 minutes. The obtained resin composition was hot press molded to prepare a 150 × 150 × 1 mm sheet. In hot press molding, a required amount of resin is put in a mold, preheated (150 ° C, 10 minutes), and pressure molded (15
After 0 ° C. and 100 kg / cm ² for 10 minutes), the sheet was naturally cooled and the sheet was taken out from the mold.

Example 2 Dimethyl succinate (Mw = 1)
46) 43.8 g, 1,4-butanediol 29.1
g, tetraisopropyl titanate (0.02 g) was placed in a flask equipped with a stirrer, a diversion tube, a gas introduction tube, and a depressurizing tube, and under a nitrogen atmosphere normal pressure at 190 ° C. for 2 hours, and then gradually depressurized, 1 to 0. 200 at 0.5 mmHg
The temperature is raised to ℃ and the mixture is stirred for 8 hours, and further 0.5 to 0.1 mmH.
The temperature was raised to 210 to 220 ° C in g and the mixture was stirred for 5 hours, methanol and excess 1,4-butanediol were distilled off from the system to synthesize a polyester resin (B). The polyester resin (B) had a number average molecular weight of about 38,000 and a weight average molecular weight of about 75,000. The kneading of the polyester resin (B) and polycaprolactone and the molding of the sheet sample were performed by the following methods. Polycaprolactone "PCL" with 100 parts by weight of polyester resin (B)
H1P "(manufactured by Daicel Chemical Industries, number average molecular weight 10,0
00) 11.1 parts by weight are supplied to Labo Plastomill to
After the torque was stabilized at 50 ° C. and 30 rpm, the mixture was heated and kneaded for 10 minutes. The obtained resin composition was subjected to heat press molding to prepare a 150 × 150 × 1 mm sheet. In hot press molding, put the required amount of resin in the mold and preheat (150
℃, 10 minutes), pressure molding (150 ℃, 100kg /
(cm ² for 10 minutes), allowed to cool naturally, and take out the sheet from the mold.

(Comparative Example 1) The polyester resin (A) was heated and kneaded for 10 minutes in a Labo Plastomill after the torque was stabilized at 150 ° C. and 30 rpm, and the resin was heated and press-molded to form a 150 × 150 × 1 mm sheet. It was made. In hot press molding, put the required amount of resin in the mold and preheat (15
0 ℃, 10 minutes), pressure molding (150 ℃, 100kg /
(cm ² for 10 minutes), allowed to cool naturally, and take out the sheet from the mold.

(Comparative Example 2) The polyester resin (B) was heat kneaded for 10 minutes after the torque was stabilized at 150 ° C. and 30 rpm in a Labo Plastomill to form a 150 × 150 × 1 mm sheet by heat press molding. Was produced. In hot press molding, put the required amount of resin in the mold and preheat (1
50 ℃, 10 minutes), pressure molding (150 ℃, 100k)
(g / cm ² , 10 minutes), and allowed to cool naturally, and the sheet was taken out from the mold.

Comparative Example 3 Polycaprolactone PCLH
7 (manufactured by Daicel Chemical Industries) in a Labo Plastomill 15
After the torque was stabilized at 0 ° C and 30 rpm, the resin was heated and kneaded for 10 minutes, and then heat-press molded to obtain 150 x 150 x.
A 1 mm sheet was prepared. The hot press molding is performed by putting a required amount of resin in a mold, preheating (150 ° C., 10 minutes), pressure molding (150 ° C., 100 kg / cm ² , 10 minutes), and then allowing it to cool naturally. It was done by the method of taking out the sheet from.

The evaluation of mechanical properties, heat resistance, biodegradability, etc. was carried out by obtaining a sample having the following shape from each molded sheet. Mechanical properties were evaluated with dumbbell-shaped sheets and heat resistance was 30
A mm-square sheet was used as a sample for sheet viscosity for melt viscosity, and a sheet resin powder for biodegradability as a sample. The evaluation methods and results are shown in Table 1 below.

[0027]

[Table 1]

According to Table-1, the actual biodegradability results of Examples 1 and 2 are the biodegradation rate expected from the mixing ratio of the polyester resins (A), (B) and polycaprolactone (in Example 1, 10%, 22% in Example 2),
It can be seen that they are improved by about 260% and 100%, respectively. It can be considered that the polyester resins (A) and (B) were induced to decompose by polycaprolactone. From the above, by kneading the polycaprolactone, the effect of improving the biodegradability by the kneading is clear with almost no deterioration of the physical properties such as the melting point of the kneaded aliphatic polyester resin.

[0029]

Industrial Applicability According to the present invention, the biodegradability of a high molecular weight aliphatic polyester resin having a low biodegradability due to the fact that it contains an aliphatic polyester resin which is not relatively biodegradable by itself or a urethane bond. Can be easily improved and can be used in various fields as an alternative to conventional polyolefins. Therefore, the present invention has great industrial advantages from the viewpoint of environmental protection.

Claims (5)

[Claims] 1. A biodegradable polyester resin composition comprising 100 parts by weight of an aliphatic polyester resin and 1 to 200 parts by weight of polycaprolactone. 2. The aliphatic polyester resin is a polyester resin containing succinic acid as a dicarboxylic acid component.
The biodegradable polyester resin composition described. 3. The biodegradable polyester resin composition according to claim 1, wherein the aliphatic polyester resin is a polyester resin composed of succinic acid and 1,4-butanediol. 4. The aliphatic polyester resin is a polyester resin containing succinic acid as a dicarboxylic acid component and having a high molecular weight with an aliphatic diisocyanate compound.
The biodegradable polyester resin composition described. 5. The biodegradable polyester resin composition according to claim 1, wherein the aliphatic polyester resin is a polyester resin composed of succinic acid and 1,4-butanediol and has a high molecular weight with hexamethylene diisocyanate.