JP3355088B2 - Biodegradable polyester resin composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a biodegradable polyester resin composition. More specifically, dicarboxylic acids or esters thereof, which are not relatively highly biodegradable,
The present invention relates to a polyester resin composition which contains an aliphatic polyester resin obtained by polycondensation from a polyol and an aliphatic polyester resin containing a urethane bond, and is more excellent in biodegradability than itself.

[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 vinyl chloride can damage incinerators due to high calorific value during incineration, The generation of harmful waste gas is a problem, while the landfill disposal has a problem of environmental pollution due to remaining in the environment forever.

[0003] In view of the above, the use of bio-cellulose or starch-based plastics of natural materials, low-substituted cellulose esters, polyesters synthesized by microorganisms, aliphatic polyester resins, etc. as biodegradable plastics has been studied. ing. Of these, workability, cost,
An aliphatic polyester resin obtained by chemical synthesis is one that has attracted attention as a resin that is relatively balanced in terms of mechanical properties, water resistance, and the like and is easy to use in various applications.

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 carboxylic 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.

Therefore, the above-mentioned dicarboxylic acid or
Obtained by polycondensation from its ester and polyol
Have been made to be high molecular weight by a urethane bond a molecule terminal hydroxyl groups of the polyester resin using a polyisocyanate. As the polyisocyanate used here, hexamethylene diisocyanate and the like are often used because aliphatic ones have better biodegradability than aromatic ones. As described above, at present, low-molecular-weight aliphatic polyester resins are made to have a high molecular weight, mechanical properties are secured, and processing such as injection molding, blow molding, fiberization, and film formation is performed.

However, these dicarboxylic acids or their dicarboxylic acids
Even if it is an aliphatic polyester resin obtained by polycondensation from an ester and a polyol, the crystallinity is high, and when a urethane bond is introduced into the resin molecule as described above, biodegradability by a microorganism is usually high. descend. 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-based polyurethane using hexamethylene diisocyanate was clearly evaluated from the results of almost no decomposition observed when evaluated in a decomposition test in activated sludge specified in JIS K6950. is there. 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 of the succinic polyester resin having a number-average molecular weight of about 10,000 is connected by connecting 4 to 5 hydroxyl groups with polyisocyanate at a molecular weight of 40,000 to 4
Polyester resin with high molecular weight of 50,000
When evaluated by a decomposition test in activated sludge specified by SK6950, an evaluation result of poor decomposition is obtained.

[0007]

Accordingly, the present invention relates to dicarboxylic acids or
Obtained by polycondensation from its ester and polyol
Aliphatic polyester resin and a small amount of an aliphatic polyester resin containing urethane bonds (hereinafter, unless specifically distinguished, this where both simply referred to as "aliphatic polyester resin"
There is also . ) To improve the biodegradability.

[0008]

Means for Solving the Problems A single resin exhibits biodegradability in an environment in which bacteria capable of efficiently decomposing the same are present, but is kneaded by mixing and kneading a resin having better degradability. For example, the probability that bacteria that decompose the degraded resin will be present 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. In some cases, the decomposability is higher than in the case of one resin.

[0009] The present inventors consider that dicarboxylic acids or their esters and polyethers which are not relatively highly biodegradable by themselves.
The biodegradability is remarkably improved by blending and kneading a higher biodegradable polycaprolactone with an aliphatic polyester resin obtained by polycondensation from riol and a polyester resin containing urethane bonds and having low biodegradability. Found to improve. That is, the decomposition rate and the content ratio of the low biodegradable polyester resin constituting the kneaded resin composition alone, higher than the decomposition rate expected from the decomposition rate and the content ratio of the high biodegradable polycaprolactone alone. It has been found that a decomposition rate can be obtained. Further, since polycaprolactone has a low melting point of 60 ° C., it is generally considered that the kneading of the polycaprolactone lowers the melting point of the whole resin composition. It has been found that the biodegradability of an aliphatic polyester resin having a relatively high biodegradability by itself or an aliphatic polyester resin containing a urethane bond can be remarkably improved by the blending / addition of.

That is, the present invention relates to a dicarboxylic acid or a dicarboxylic acid.
Obtained by polycondensation from esters and polyols of
That relates to polycarbonate <br/> Purorakuto emissions 1-200 by blending parts by weight biodegradable polyester resin composition per 100 parts by weight of the aliphatic polyester resin. Hereinafter, the present invention will be described in detail.

The dicarboxylic acid used in the present invention or its dicarboxylic acid
The aliphatic polyester resin obtained by polycondensation from an ester and a polyol is not particularly limited, but has a melting point of 100 ° C. or higher, has thermoplasticity, and is not relatively high in biodegradability. The polyester resin obtained from the succinic acid and 1,4-butanediol, the polyester resin obtained from succinic acid and ethylene glycol, the polyester resin obtained from oxalic acid and neopentyl glycol, the oxalic acid and 1,4- Examples thereof include a polyester resin obtained from 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 aliphatic polyester resin containing a urethane bond used in the present invention is obtained by increasing the molecular weight of the aliphatic polyester resin, preferably by using 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 )}, trimethylhexamethylene diisocyanate and the like are exemplified, and among them, hexamethylene diisocyanate is preferable. The number average molecular weight of the aliphatic polyester resin containing a urethane bond is preferably 20,000 or more, more preferably 40,000 or more.

The polycaprolactone used in the present invention is:
For example, it can be obtained by subjecting ε-caprolactone to ring-opening polymerization in a conventional manner 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 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 20.
0000, and 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 problems, it is difficult and impractical to obtain polycaprolactone having such a very high molecular weight. Further, the polycaprolactone to be used includes, in addition to ε-caprolactone homopolymer, comonomer constituent units such as valerolactone, glycolide, and lactide, for example, 20
Copolymers containing less than mol% can also be used.

Dicarboxylic acid or its ester and polycarboxylic acid
The mixing ratio of the aliphatic polyester resin and polycaprolactone obtained by polycondensation from riol depends on the molecular weight of both, and the required biodegradability, but the latter is 1 to 200 parts by weight, and the latter is 1 to 200 parts by weight. Preferably 5-5
0 parts by weight, in particular from 20 to 40 parts by weight.

Dicarboxylic acid or its ester and polycarboxylic acid
When kneading an aliphatic polyester resin and polycaprolactone obtained by polycondensation from riol, it is preferable to have compatibility with both, from the viewpoint of mechanical properties of the resin composition obtained by kneading. If there is no
For example, addition of a compatibilizer such as a copolymer of a resin component to be kneaded and a polycaprolactone component, for example, 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.

Polycaprolactone and dicarboxylic acid or
Obtained by polycondensation from its ester and polyol
As a method of kneading with the aliphatic polyester resin to be used, a general method can be preferably used, and specifically, a pellet or powder,
The solid flakes and the like can be dry-mixed with a Henschel mixer or a ribbon mixer, and supplied to a known melt mixer such as a single-screw or twin-screw extruder, a Banbury mixer, a kneader, or a mixing roll to be 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 as a substitute for 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
It went 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.

Example 1 35.4 g of succinic acid (Mw = 118), 29.1 g of 1,4-butanediol (Mw = 90) and 0.02 g of tetraisopropyl titanate were stirred with a stirrer, a distribution pipe, and a gas introduction pipe. Into a flask equipped with a decompression tube, under nitrogen atmosphere at normal pressure, at 200 ° C. for 2 hours, while gradually reducing the pressure to reach 0.5 mmHg or less, stirring at 200 ° C. for 5 hours, water and excess water. 1,4-butanediol was distilled off from the system to synthesize a polyester resin. next,
0.8 g of hexamethylene diisocyanate (Mw = 168) was added at 200 ° C. under a normal pressure of nitrogen atmosphere 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, and the weight average molecular weight is about 18
It was 5,000. Kneading of polyester resin (A) and polycaprolactone and molding of a sheet sample
The following method was used. 100% polyester resin (A)
Parts by weight 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 at 150 ° C. and 30 rpm.
After kneading at m, and the torque was stabilized, the mixture was further heated and kneaded for 10 minutes. The obtained resin composition was subjected to hot press molding, and 15
A 0 × 150 × 1 mm sheet was prepared. In hot press molding, a required amount of resin is put into a mold and preheated (150 ° C, 10 ° C).
Min.) And press molding (150 ° C, 100 kg / cm ² ,
After 10 minutes), the sheet was allowed to cool naturally and the sheet was taken out of the mold.

Example 2 43.8 g of dimethyl succinate (Mw = 146), 1,4
-29.1 g of butanediol 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 depressurization tube.
2 hours at 0 ° C., while gradually reducing the pressure,
The temperature was raised to 200 ° C. at 0.5 mmHg, and the mixture was stirred for 8 hours. The temperature was further raised to 210 to 220 ° C. at 0.5 to 0.1 mmHg, and the mixture was stirred for 5 hours to remove methanol and excess 1,4-butanediol. The polyester resin (B) was synthesized by distilling off the system. The number average molecular weight of the polyester resin (B) was about 38,000, and the weight average molecular weight was about 75,000. The kneading of the polyester resin (B) and the polycaprolactone and the molding of the sheet sample were performed by the following method. 100 parts by weight of a polyester resin (B) and polycaprolactone “PCLH1P” (manufactured by Daicel Chemical Industries,
11.1 parts by weight (number average molecular weight 10,000) was supplied to a Labo Plastomill, and the mixture was heated and kneaded at 150 ° C. and 30 rpm for 10 minutes after the torque was stabilized. The obtained resin composition was subjected to heat press molding to prepare a 150 × 150 × 1 mm sheet. In hot press molding, a required amount of resin is put into a mold, preheated (150 ° C., 10 minutes), and pressure molded (1
(50 ° C., 100 kg / cm ² , 10 minutes), allowed to cool naturally, and the sheet was taken out of the mold.

(Comparative Example 1) A polyester resin (A) was placed in a Labo Plastomill for 150 hours.
After the torque was stabilized at 30 ° C. and 30 rpm, the resin heated and kneaded for 10 minutes was subjected to hot press molding to form 150 × 150 × 1
mm sheet was produced. In hot press molding, a required amount of resin is put into a mold, preheated (150 ° C., 10 minutes), pressed (150 ° C., 100 kg / cm ² , 10 minutes), allowed to cool naturally, and then Was carried out by a method of taking out a sheet from the apparatus.

(Comparative Example 2) The polyester resin (B) was placed in a Labo Plastomill for 15 minutes.
After the torque is stabilized at 0 ° C. and 30 rpm, the resin which has been heated and kneaded for 10 minutes is subjected to hot press molding to obtain 150 × 150 ×
A 1 mm sheet was produced. In hot press molding, a required amount of resin is put into a mold, preheated (150 ° C., 10 minutes), pressed (150 ° C., 100 kg / cm ² , 10 minutes), allowed to cool naturally, and then cooled. Was carried out by a method of taking out a sheet from the apparatus.

Comparative Example 3 Polycaprolactone PCLH7 (manufactured by Daicel Chemical Industries)
After the torque was stabilized at 150 ° C. and 30 rpm in a lab plast mill, a resin heated and kneaded for 10 minutes was subjected to heat press molding to prepare a 150 × 150 × 1 mm sheet.
In hot press molding, a required amount of resin is put into a mold, preheated (150 ° C., 10 minutes), and pressure molded (150 ° C., 10 ° C.).
(0 kg / cm ² , 10 minutes), allowed to cool naturally, and taken out of the mold.

Evaluation of mechanical properties, heat resistance, biodegradability, etc. was performed by obtaining samples of the following shapes from each molded sheet. The mechanical properties were evaluated using a dumbbell-shaped sheet and the heat resistance was 30.
Samples of mm square sheets, thin pieces of sheet resin for melt viscosity, and powders of sheet resin for biodegradability were used. 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 indicate that dicarboxylic acid or its ester and
The biodegradation rate expected from the mixing ratio of the polyester resins (A) and (B) obtained by polycondensation with the polyol and polycaprolactone (10% in Example 1 and 22% in Example 2) is about 260% and 100%
It can be seen that it has been improved. This can be considered that the polyester resins (A) and (B) were induced to decompose by polycaprolactone. From the above, it is apparent that the kneading of polycaprolactone has the effect of improving the biodegradability by kneading with almost no reduction in physical properties such as a decrease in the melting point of the aliphatic polyester resin to be kneaded.

[0029]

According to the present invention, dicarboxylic acids or esters thereof which are not relatively highly biodegradable by themselves and
It is possible to easily improve the biodegradability of an aliphatic polyester resin obtained by polycondensation from a polyol or a high-molecular-weight aliphatic polyester resin whose biodegradability has been reduced due to the fact that it contains a urethane bond. Can be used in various fields. Therefore, the present invention has a great industrial advantage from the viewpoint of environmental protection.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-5-105771 (JP, A) JP-A-6-192550 (JP, A) JP-A-6-107934 (JP, A) JP-A-6-107934 145283 (JP, A) JP-A-5-287704 (JP, A) JP-A-5-271375 (JP, A) JP-A-7-3138 (JP, A) JP-A-6-293826 (JP, A) (58) Field surveyed (Int.Cl. ⁷ , DB name) C08L 75/04-75/12 C08L 67 / 02,67 / 04

Claims (5)

(57) [Claims] 1. A dicarboxylic acid or an ester thereof and
Polycaprolactone Lactobacillus down 1 to 100 parts by weight of the aliphatic polyester resin obtained by polycondensation of a polyol
A biodegradable polyester resin composition containing 200 parts by weight. 2. An aliphatic polyester resin comprising succinic acid as a dicarboxylic acid component.
The biodegradable polyester resin composition as described in the above. 3. The biodegradable polyester resin composition according to claim 1, wherein the aliphatic polyester resin is a polyester resin comprising succinic acid and 1,4-butanediol. 4. The aliphatic polyester resin obtained by increasing the molecular weight of a polyester resin containing succinic acid as a dicarboxylic acid component with an aliphatic diisocyanate compound.
The biodegradable polyester resin composition as described in the above. 5. The biodegradable polyester resin composition according to claim 1, wherein the aliphatic polyester resin is obtained by increasing the molecular weight of a polyester resin comprising succinic acid and 1,4-butanediol with hexamethylene diisocyanate.