JPH10316739A - Refuse sack - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a novel refuse sack which is soft, easily handleable and excellent in degradability in the natural environment or in a compost and contributing to environmental protection. SOLUTION: This sack contains at least 50 wt.% fiber or film produced from a polymer composition being at least one composition selected from the group consisting of a mixture of a crystalline polylactic acid having a melting point of 150 deg.C or above with an aliphatic polyester based on a linear diol and an aliphatic dicarboxylic acid and having a melting point of 140 deg.C or below, a block copolymer of a polylactic acid with an aliphatic polyester and a mixture of a polylactic acid and/or an aliphatic polyester with a block copolymer and having a content of a lactic-acid-derived component of 50-99 wt.% and a content of an aliphatic polyester-derived component of 1-50 wt.%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel garbage bag which is naturally decomposable and is decomposed in a natural environment so that it can be easily disposed of and contributes to protection of the natural environment.

[0002]

2. Description of the Related Art Garbage bags and drain bags made of synthetic resins and synthetic fibers (hereinafter referred to as garbage bags) are used in large quantities to collect and discard household garbage, garbage, industrial garbage and the like. However, synthetic resins are difficult to decompose in a natural environment, so that they are difficult to dispose after use and generate a large amount of heat during combustion, which causes environmental pollution. For this reason, garbage bags and drainage bags using a resin composed of an aliphatic polyester that decomposes in a natural environment are disclosed in, for example, JP-A-4-362080, JP-A-6-32357, and JP-A-8-188.
No. 706, for example.

[0003] In these publications, polycaprolactone and polybutylene succinate are disclosed as the most preferable examples (examples and the like) of naturally degradable resins. However, polycaprolactone and polybutylene succinate have low melting points and thus have problems in melt spinning and melt film formation.In addition, they are inferior in performance and heat resistance. There are many problems.

According to the findings of the present inventors, polylactic acid is mentioned as a degradable polymer which is expected to be particularly preferable as a material for a garbage bag because of its excellent fiber and film properties and heat resistance. Furthermore, polylactic acid is made from agricultural products (starch, etc.)
Therefore, it is preferable from the viewpoint of protecting the global environment. (Although the above publication also discloses polylactic acid as one of many aliphatic polyesters listed, it is described as being particularly suitable. Not). However, the homopolymer of polylactic acid has the following disadvantages: (1) the melting point (175-185 ° C.) is too high, close to the decomposition temperature, and melt polymerization, melt spinning and melt film formation are difficult; There are many problems such as difficulty in stretching, difficulty in handling such as the film being hard and brittle and breaking during use, and poor practicality; and (3) difficulty in disposal due to slow decomposition rate in a natural environment.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a naturally degradable garbage bag made of a novel polymer composition which makes use of the above-mentioned advantages of polylactic acid and has improved the problems.

[0006]

The object of the present invention is to provide
"(1) crystalline polylactic acid (A) having a melting point of 150 ° C. or more,
Mainly composed of chain diol and aliphatic dicarboxylic acid, melting point 1
A mixture with an aliphatic polyester (B) having a temperature of 40 ° C. or lower,
(2) a block copolymer (C) of the polylactic acid (A) and the aliphatic polyester (B), and (3) the polylactic acid (A) and / or the aliphatic polyester (B)
And a mixture of the above-mentioned block copolymer (C) ", wherein the proportion of the component derived from lactic acid is 50 to 99% by weight, and This is achieved by a naturally degradable garbage bag containing 50% by weight or more of a fiber and / or a film produced from a polymer composition having a ratio of 1 to 50% by weight.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of crystalline polylactic acid (A) having a melting point of 150 ° C. or higher include poly-L-lactic acid and poly-D-lactic acid.
Lactic acid and a small amount thereof (not more than 50% by weight, especially not more than 30% by weight, often not more than 20% by weight) obtained by copolymerizing lactic acid and a different kind of raw material for the polyester, while keeping the melting point at 150 ° C. or more Is mentioned. The melting point of the crystalline polylactic acid (A) is preferably high from the viewpoint of heat resistance, particularly preferably 160 ° C. or higher, and most preferably 170 ° C. or higher. Even when such a high melting point polylactic acid is used, there is no problem because the melt flowability and flexibility are improved because the combination with the above-mentioned low melting point aliphatic polyester is used. Is often obtained.

The chain diol is a diol having no aromatic cyclic structure, and includes aliphatic diols having straight and side chains, diols having an ether bond, diols having a carbonate bond, and the like. Examples of aliphatic diols include:
Ethylene glycol, propylene glycol, butanediol, hexanediol, neopentyl glycol,
In addition to octanediol and the like, those having an unsaturated bond may be mentioned. Examples of the diol having an ether bond include diethylene glycol, triethylene glycol, ethylene / propylene glycol, dipropylene glycol, dihydroxyethoxybutane, polyethylene glycol, and the like.
Oligomers and polymers of polyalkylene ethers, such as polypropylene glycol, polyethylene / propylene glycol, and the like, are mentioned. As the diol having a carbonate bond, polypropylene carbonate,
Examples include oligomers and polymers of aliphatic polycarbonates such as polybutylene carbonate and polyhexane carbonate.

Examples of the aliphatic dicarboxylic acid include succinic acid, adipic acid, suberic acid, azelaic acid, sebacic acid and decanedicarboxylic acid, as well as those having a side chain and those having an unsaturated bond.

The above chain diol and aliphatic dicarboxylic acid are also used as a raw material for copolymerizing crystalline polylactic acid.
Other aliphatic polyester raw materials, for example, glycolic acid, glycolide, optical isomers of lactic acid, optical isomers of lactide, butyrolactone, caprolactone, hydroxyalkylcarboxylic acids such as hydroxybutylcarboxylic acid, and cyclic esters thereof are also used as raw materials for copolymerization. It is possible. If the amount is small (about 10% by weight or less), aromatic raw materials such as terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, and sulfoisophthalic acid can be applied.

The melting point of the polymer was determined by using a dried sample that had been sufficiently heat-treated or stretched, using a differential calorimeter (hereinafter referred to as DSC), 10 mg of the sample, in a nitrogen atmosphere, and at a heating rate of 1%.
The peak temperature of the endothermic peak due to the melting of the polymer crystal when measured at 0 ° C./min. The melting point of pure polylactic acid (poly-L-lactic acid, poly-D-lactic acid) is about 185 ° C., but usually some optical isomers are formed due to the racemization phenomenon during the reaction and are formed into a copolymer. Therefore, the melting point is 175
~ 180 ° C is often indicated.

Many polyesters obtained by combining an aliphatic diol and an aliphatic dicarboxylic acid have a melting point of 140 ° C. or less and a glass transition point of ordinary temperature or less, and are used in the present invention as the above (low melting point) aliphatic polyester (B). I can do it. Specific examples thereof include polyethylene succinate (melting point: about 102 ° C.) and polyethylene adipate (49
° C), polyethylene suberate (65 ° C), polyethylene suberate (65 ° C), polyethylene azelate (52 ° C), polyethylene sebacate (72 ° C),
Polybutylene succinate (116 ° C), polybutylene adipate (72 ° C), polybutylene sebacate (66 ° C), polybutylene azelate (52 ° C),
Polyhexane sebacate (74 ° C.). These are examples of homopolymers, but of course copolymers are also used. In the case of a non-crystalline copolymer or the like, the glass transition point is regarded as the melting point.

The composition for forming the specific fibers and films used in the garbage bag of the present invention comprises the above-mentioned polylactic acid (A) having a relatively high melting point and the aliphatic polyester (B) having a low melting point. It is roughly divided into the following five types.

1. A mixture of (A) and (B). As a mixing ratio, (A) is preferably 70% by weight or more, more preferably 85% by weight or more. If it is less than 85% by weight,
The compatibility between (A) and (B) is poor, and the molded product tends to be brittle or opaque. 2. Block copolymer (C) of (A) and (B).
As for the reaction ratio of (A) and (B), there is no major problem if (A) is in the range of 50 to 99% by weight and (B) is in the range of 1 to 50% by weight, but the ratio of (B) is large By the way, the ratio of (B) is preferably at most 40% by weight, more preferably 30% by weight, because heat resistance and crystallinity are reduced and there are restrictions depending on applications and purposes. 3. A mixture of (A) and (C). Used here (C)
Can be used, a block copolymer containing at most 50% by weight of (B) can be used, and the proportion of the aliphatic polyester-derived component in the mixture of (A) and (C) is at most 50% by weight. , Preferably at most 40% by weight, more preferably at most 30% by weight. 4. A mixture of (B) and (C). Used here (C)
May be the same as the composition of the above item 3, and the amount of the component derived from the aliphatic polyester in the mixture is also the same. 5. A ternary mixture of (A), (B) and (C). The amount of (C) used here may be the same as the composition of the above 3. Further, the proportion of the component derived from the aliphatic polyester in the triple mixture system is at most 50% by weight, preferably at most 40% by weight. More preferably, (B) / (A) + (B) = 0.1
(C) consisting of about 0.5 to about 0.2 of the amount of (B) in the three-component mixed system is preferably used.

Of course, the fiber or film used in the garbage bag of the present invention is not limited to one kind, and a plurality of fibers or films having different compositions may be mixed and used. Similarly, composite fibers or composite films in which a plurality of polymer compositions are composited are also applicable and are included in the present invention.

The method of mixing the polylactic acid (A) and the aliphatic polyester (B) is not particularly limited, but the two may be mechanically stirred in a solution state, and the flow splitting and merging are repeated in multiple stages. A static mixing device may be applied, or both may be used in combination. Melt mixing is efficient and preferable, but a device capable of mixing in a short time (for example, within 20 minutes, particularly 10 minutes), for example, a twin-screw extruder, in order to prevent the polymers from reacting to form a random copolymer. It is preferable to use such as. Similarly, one in which the end of one polymer (for example, (B)) is blocked to suppress the reactivity can be added and mixed during the polymerization of the other polymer (for example, (A)).

The method for block copolymerization of the polylactic acid (A) and the aliphatic polyester (B) is not particularly limited. For example, when an L or D lactide is melt-polymerized to produce polylactic acid, if an aliphatic polyester (B) having a hydroxyl group at one or both molecular terminals is added to and mixed with the polymerization system, lactide is converted from the terminal hydroxyl group. The polymerization is started, and a block copolymer is easily obtained. If both are unreacted, a mixture of both is obtained, and if a part is reacted and a part is unreacted, a mixture of "a block copolymer of both" and "a mixture of both" is obtained . However, care must be taken so that the reaction does not proceed excessively to reach a complete random copolymer.

Similarly, polylactic acid (A) having a hydroxyl group at both ends and an aliphatic polyester are mixed, and a polyfunctional reactant (chain extender) such as diisocyanate or dicarboxylic acid chloride is added thereto and reacted. The two components can be linked to form a block copolymer. The block copolymerization by transesterification at the time of melt mixing of both components is as described above. Whether or not both components have reacted can be considerably determined by GPC analysis or the like. If the random copolymerization proceeds excessively, a sharp decrease in the melting point and a remarkable decrease in the melting endotherm (crystallinity) are observed by DSC analysis. The decrease in melting point due to block copolymerization is relatively slow.

As described above, the composition used in the present invention is roughly classified into five types. In particular, the block copolymer (C) of polylactic acid (A) and aliphatic polyester (B) has a melt flowability and It is excellent in miscibility, easy to obtain a uniform product, and easy to manufacture. Further, since the block copolymer (C) is excellent in miscibility with the component (A) and the component (B), a mixture of (A) and (C), a mixture of (B) and (C), A ternary mixture of (A), (B) and (C) is particularly preferred for the purpose of the present invention.

The fibers and films, which are the main materials forming the garbage bag of the present invention, are mainly composed of polylactic acid (A) and a low-melting aliphatic polyester (B). By introducing the low melting point aliphatic polyester (B),
The problems of the above-mentioned polylactic acid, that is, the product is hard and brittle, the melt fluidity is low and the melt polymerization or melt molding is difficult, the spontaneous decomposition rate is low, and the fluidity, flexibility,
The impact resistance, spontaneous decomposition property, etc. are also improved, and the advantages of polylactic acid, such as good spinnability and film forming properties, and excellent heat resistance and strength, are fully exhibited.

In the waste treatment, it is most preferable that the compostable organic waste is reused as compost, and it is desired that the garbage bag be sufficiently decomposed (at least fragmented) in the composting step. However, in polylactic acid homopolymer, in a compost at a temperature of 60 ° C., the generation of carbon dioxide due to decomposition becomes remarkable after 10 days (equivalent to cellulose), and it takes about 30 days to completely decompose. Degradation is slower in cooler compost. Practically 40
It is most desirable to compost in a compost at ５０50 ° C. in about 10 to 30 days, but the present invention has made it possible.

These improvements or modifications become more remarkable as the introduction amount (weight ratio) of the low melting point aliphatic polyester (B) increases. For example, to make the composting speed much faster,
The introduction amount of the aliphatic polyester (B) is 10% by weight or more,
In particular, it is effective if the content is 20% by weight or more. However, when the amount of the low melting point aliphatic polyester (B) becomes excessive,
In order to lose desirable physical properties of polylactic acid (good heat resistance, spinnability, film forming property, etc.) and to suppress petroleum-derived components, the content of lactic acid-derived components in the composition is 50 to 99% by weight. It must be in the range, particularly preferably in the range of 60 to 95% by weight, and the range of 65 to 92% by weight is most widely used. Similarly, the component derived from the low melting point aliphatic polyester in the composition should be in the range of 1 to 50% by weight, preferably 5 to 40% by weight, and most preferably 8 to 35% by weight. Can be

The composition used in the garbage bag of the present invention contains, in addition to the above-mentioned main components (A) and (B), for example, a fluidity improver, a plasticizer, a release agent, a water repellent, an oxidizer, and the like. Introducing and mixing inhibitors, stabilizers, compatibilizers, colorants, dispersants (surfactants, etc.), decomposition accelerators, other additives and components for improvement, fillers, extenders, and other components You can do it. Examples of the filler include particles of an inorganic compound, and examples of the filler include starch, modified starch, cellulose powder, and modified cellulose powder. The amount to be added may be selected according to the purpose, but in the case of an extender, a relatively large amount is added, for example, 10 to 49% by weight, particularly 15 to 45%.
% By weight, and in the case of additives and fillers, usually about 20% by weight or less, particularly 0.1 to 10% by weight.
In many cases, it is about weight%.

The molecular weight of the polylactic acid component (A) forming the composition used in the present invention is not particularly limited, but is usually preferably 30,000 or more, particularly preferably in the range of 50,000 to 300,000, and more preferably in the range of 70 to 200,000. Most widely used. Although the molecular weight of the aliphatic polyester component (B) having a low melting point is not particularly limited, it is usually preferably 20,000 or more, particularly preferably in the range of 30,000 to 300,000, and most preferably in the range of 50,000 to 200,000. The molecular weight is 0.1
% GPC analysis of chloroform solution
The weight average molecular weight of the dispersion of the polymer component excluding the components of 00 or less is defined.

The garbage bag of the present invention comprises the above polylactic acid (A)
And 50% by weight or more of a fiber or film composed of a composition mainly composed of a low melting point aliphatic polyester (B).
That is, it may contain 50% by weight or less of other components. However, in order to strongly exert the features of the present invention, it is preferable to suppress the usage of other components, for example, preferably 30% by weight or less, particularly preferably 20% by weight or less, and most preferably 10% by weight or less.

Examples of the mixture of other components include cotton, wool,
Examples include natural fibers such as cellulose and regenerated cellulose, cellulose-based fibers, and cellulose-based films. In addition, a small amount of superabsorbent synthetic fibers or films having a large amount of metal acrylate base or the like (for example, about 10% by weight or less)
By mixing, the natural decomposition rate at the time of disposal can be increased. The mixing method can be performed by ordinary blending or blending. For example, the simplest method is to staple the fibers of the present application and staples such as cotton, wool, rayon, etc. on a card at a predetermined ratio and blend them. By mixing and using natural fibers and rayon, it becomes easy to control hygroscopicity and degradability. In addition, it is possible to adjust the hardness and the hand feel.

When a highly water-absorbing material is used, for example, when a weak alkaline aqueous solution such as sodium carbonate is applied by spraying at the time of disposal, the water-absorbing material adsorbs the alkali and rapidly decomposes the surrounding aliphatic polyester, The bags are shredded to facilitate processing. An adhesive may be used for bonding and bonding the fibers and the film to each other, but the adhesive is preferably naturally decomposable. The number average molecular weight of the polyester composition used in the present invention is not particularly limited, but is preferably 50,000 or more, more preferably 70,000 to 300,000, and particularly preferably 80,000 to 200,000.

The garbage bag of the present invention contains the above-mentioned specific polymer composition as a main component, and its structure is not particularly limited. However, a nonwoven fabric, a woven fabric, a knitted fabric, a sheet-like structure composed of other fibers, a film, and a fiber And a composite of a film and the like are widely used.

As the fibers, continuous filaments and short fibers (staples) can be used, and both can be used in combination. Fibers are melt-spun, dry-spun, wet-spun,
Known methods such as dry and wet spinning are often used,
For non-woven fabrics, flash spinning, spunbonding, dry staple web (card method), wet web, and other well-known manufacturing methods can be applied. A method using a high-speed jet stream of fluid, application of an adhesive, a method of heating a web in which fibers having a relatively low melting point or a heat-bonded fiber (a self-adhesive fiber) in which a low-melting polymer and a high-melting polymer are combined, Any method such as embossing can be applied.

Similarly, for the film used for the garbage bag of the present invention, known methods such as a melt film forming method, a wet film forming method and a dry film forming method can be applied. Method, coating method, dipping method and the like can be applied. Since the specific composition used in the present invention has a different heat fusing temperature depending on the composition, a single component fiber or a bicomponent composite fiber is manufactured by using one or two or more types of the heat bonding fibers. Is also possible. For example, if the heat bonding temperature is 2
Two kinds of compositions differing by 0 ° C. or more, preferably 30 ° C. or more can be combined in a core / sheath or side-by-side relationship to produce a heat-bonded fiber.

Further, a film suitable for heat bonding can be produced from a low-melting polymer, and a multilayer film and other composite films can be produced from a plurality of polymers. Although the structure and size of the bag are not particularly limited, it is common to bond or sew the joint.

The garbage bag of the present invention having a porous structure or provided with holes as appropriate is suitable as a draining bag, as a garbage bag having moisture such as kitchen garbage and kitchen garbage. For example, a tubular structure (a kind of knitting) in which fibers are bonded in a net shape, obtained by mutually rotating two inner and outer base plates provided with a number of extrusion nozzles on the circumference, is easy to manufacture. It is efficient and is particularly preferred as a drain bag. In addition, bags and draining bags having various structures may be used according to the purpose.

The thickness and thickness of the fibers and films constituting the garbage bag of the present invention are not particularly limited. Usually, the single fiber fineness of the fiber is about 0.5 to 500 denier, especially 1 to 20 denier.
A fiber having a denier of about 0 is widely used, and a film having a thickness of about 5 to 500 μm, particularly about 10 to 200 μm is often used.

[0034]

EXAMPLES In the following examples,% and parts are by weight unless otherwise specified.

Examples 1 and 2 and Comparative Example 1 L-lactide was mixed with 200 ppm of tin octylate and polymerized in a twin-screw kneading extruder at 188 ° C. for 8 minutes in a nitrogen atmosphere. The mixture was treated in a nitrogen atmosphere at ℃ (solid state polymerization) to obtain a poly-L-lactic acid homopolymer P1. P1 had a melting point of 176 ° C. and a molecular weight of 181,000.

Using a twin screw extruder, 10% of polybutylene succinate having a molecular weight of 128,000 (hereinafter referred to as PBS, melting point: 116 ° C.) was added to P1, and mixed at 190 ° C. for 3 minutes. Lactic acid / PBS = 9/1 mixed polymer P
2 was obtained. Polymer P2 has a melting point of 176 ° C. and a molecular weight of 1
It was 47,000. Similarly, a mixed polymer P3 was obtained with a mixing ratio of polylactic acid / PBS = 75/25. The melting point of the mixed polymer P3 is 173 ° C. and the molecular weight is 1
It was 29,000.

The polymer P1 is melted by a screw extruder at 230 ° C., and semicircular orifices having a diameter of 0.2 mm are arranged at intervals of 2 mm on a circumference of 10 cm in diameter. 230 caps
The mixture was extruded into the air at a temperature of 0 ° C., immediately introduced into normal-temperature water, and cooled to obtain a cylindrical net having a rhombic mesh having a side length of about 2 mm and a fiber thickness of about 0.2 mm.

The tubular net was cut to a length of 45 cm, and one end of the net was converged by using a blade-shaped metal at 190 ° C. and bonded by a heat sealing method to obtain a drainage bag B1 (Comparative Example 1).
Similarly, draining bags B2 (Example 1) and B3 (Example 2) were obtained using polymers P2 and P3, respectively. The drainer bag B1 is hard and easy to tear, but slightly difficult to use, while B2 and B3 are soft and hard to break and easy to use.

Into the draining bags B1, B2, and B3, put 1 kg of a mixture of vegetable waste, sweet potato waste (strips) and 1/1/1 of paper waste, tie the entrance with a hemp rope, and further place polypropylene on the entrance. After putting it in a similar tubular net bag and sealing it, put it in a small compost tester (stainless steel rotating tank) together with 50 kg of a mixture of vegetable waste, sweet potato waste (strips) and 1/1/10 sawdust. did.

From above, EM fermentation bacteria (EM fermentation blur:
(Miyazaki Clean Farm) 1 kg was used. Initially, the internal temperature was maintained at 40 ° C., and from the third day, the temperature increased to 50 to 55 ° C. due to the heat generated by fermentation, but the operation was continued. From about the 20th day, although the temperature dropped to around 40 ° C. again, the operation was continued as it was. After 30 days, the operation was stopped, and the inside was observed.

As a result, it was found that the draining bag B1 (comparative example) was almost intact and the decomposition rate was insufficient under these conditions. On the other hand, the drainer bag B2 (Example 1) was slightly cut off from the original form but was fragmented, and it was found that composting under these conditions did not pose any problem. The draining bag B3 (Example 2) was completely decomposed, and no small pieces were found. In addition, the polypropylene net kept its original shape completely, vegetable waste and paper waste were almost decomposed, and sawdust was composted. Similar results could be obtained using activated sludge.

Examples 3 and 4 and Comparative Example 2 91 parts of L-lactide, PBS 10 having a molecular weight of 128,000
Parts, 200 ppm of tin octylate mixed in a nitrogen atmosphere
Polymerization was performed at 88 ° C for 9 minutes in a twin screw extruder, and after cooling chips were formed, the mixture was treated in a nitrogen atmosphere at 140 ° C (solid state polymerization).
A polylactic acid / PBS (about 10%) block copolymer P4 was obtained. P4 has a melting point of 173 ° C. and a molecular weight of 164,000.

A polylactic acid / PBS (20%) block copolymer P5 having a melting point of 170 ° C. and a molecular weight of 1390,000 was obtained in substantially the same manner as in P4 except that the amount of PBS added was 20%. P4 and P5 are 220 at 230 ° C. with a screw extruder.
Extruded from a T-shaped die at 80 ° C and cooled with a cooling roll.
Stretched 3.3 times in the vertical direction and 2.7 times in the horizontal direction at 0 ° C,
The film was heat-set at 10 ° C. to obtain films F1 and F2 having a thickness of 0.12 mm.

Using a heat sealing machine at 120 ° C., first, the film F1 was formed into a cylinder having a diameter of 55 cm, cut into a length of 60 cm, and heat-sealed at one end, thereby forming a garbage bag B4 (Example 3).
I got Similarly, a garbage bag of film F2 was obtained as B5 (Example 4). Similarly, the polymer P used in Comparative Example 1 was used.
The garbage bag of the film obtained using No. 1 was designated as B6 (Comparative Example 2). Although the garbage bags B4 and B5 are flexible and easy to handle, the garbage bag B6 is hard and difficult to handle, and there is a problem in that the garbage bag B6 is rough and noisy when handling.

Using the garbage bags B4, B5 and B6, a compost test was carried out in the same manner as in Examples 1, 2 and Comparative Example 1. As a result, B4 (Example 3) was fragmented and B5 (Example 4) disappeared, and there was no problem in composting. On the other hand, B6 (Comparative Example 2) was partially damaged, but remained in its original form and was inadequately decomposed. Under these conditions, B6 was found to be unsuitable for composting.

Example 5 and Comparative Example 3 P1 and L-lactide of Example 1 70 parts, molecular weight 12.8
30 parts of PBS and 200 ppm of tin octylate are mixed, melt-stirred and polymerized in a twin-screw extruder at 190 ° C. for 12 minutes in a nitrogen atmosphere, extruded into a gut, cooled into chips,
Polylactic acid / PBS = 70/30 block copolymer P6
I got

P6 and P1 and PBS having a molecular weight of 128,000
Were preliminarily mixed at a ratio of 20/60/20, then melted and mixed with a screw extruder set at 225 ° C., extruded into water from a net molding machine used in Example 1, and the same cylinder as in Example 1. The shape net was formed. 22 at 230 ° C
Extruded from a T-die at 0 ° C., cooled by a cooling roll, stretched 3.3 times in a vertical direction and 2.7 times in a lateral direction at 80 ° C., and heat-set at 110 ° C. to obtain a film F3 having a thickness of 0.12 mm. I got

A heat-sealing machine set at 145 ° C. was used to form a heat-sealed portion having a length of 15 cm and then cut with a cutter to obtain a kitchen drainer net (B7). The net was relatively soft and durable and did not hinder the kitchen garbage.

The garbage bag was set in a drain in a home kitchen, and garbage normally generated was collected. Tea leaves, coffee powder, etc., as well as relatively large garbage could be collected. Therefore, the amount of organic substances flowing to the sewage as wastewater could be greatly reduced. When the garbage was full, it was taken out and subjected to a compost test in the same manner as in Examples 1, 2 and Comparative Example 1 above. As a result, the net was shattered and largely lost. Most of the garbage was composted. On the other hand, it was confirmed that the commercially available polyolefin draining net (B8) still remained in its original form even when the garbage was composted, did not decompose at all, and did not compost.

P1, P6, P7 (P of molecular weight 13,000)
And BS) were mixed as shown in Table 1 and net-molded in the same manner as in Example 5 to form garbage bags (B9 to B17).

[0051]

[Table 1]

Example 6 and Comparative Example 4 P2 of Example 2 was melted by a screw extruder set at 230 ° C., extruded into the air from a spinning nozzle having 1000 holes of 0.3 mm, and then taken up at a speed of 3500 mm. After spraying on a moving net, it was pressure-bonded with an embossing roller at 130 ° C. to obtain an extremely thin spun bond having a basis weight of 15 g / m ² . Spunbond is longitudinal,
It had uniform quality without unevenness in the width direction.

The obtained spunbond was bent to a width of 15 cm and sewn in a length direction by a high-frequency sewing machine, and simultaneously melt-cut to a length of 15 cm by a heat sealing machine to form a bag. This bag (garbage bag (B18)) was very soft and strong.

A garbage collection test and a compost test were performed on this garbage bag in the same manner as in Example 5. Although the water permeability was worse than that of the net of Example 5, the waste collection efficiency was very high and most of the food residue could be collected. Therefore, almost no BOD load was applied to the wastewater, and the effect of reducing the load of the sewage treatment was large. Moreover, when the dust was taken out when it became full, composting did not cause any problem as in the case of the fifth embodiment. On the other hand, a composting test was also performed on a commercially available polyester spunbond draining bag (B19), and it was confirmed that the original shape was not decomposed at all and no composting was performed.

Example 7 and Comparative Examples 5 and 6 The polymer of P2 was melted by a melt extruder heated to 230 ° C., and a hole having a hole diameter of 0.25 mm was formed in 1025.
The polymer was extruded from the spinning nozzle into the air, cooled, stretched 1.8 times in warm water set at 60 ° C, and then stretched to 90 ° C.
After stretching 2.5 times in warm water set at
A crimp of 5 pieces / inch was applied, then dried and cut to obtain a staple of 1.5d × 51 mm.

The staple and 1.5d × 38 mm rayon were hung on a card at a ratio of 75/25, mixed uniformly, and entangled under high-pressure water flow. Then, it was dried on a heating roller to obtain a hydroentangled nonwoven fabric having a basis weight of 20 g / m ² . Garbage bag (B20) using this nonwoven fabric as in Example 6
The garbage was collected and tested for its compostability. The garbage bag was very soft and comfortable to use, and was able to collect fine garbage when collecting garbage, and was very effective in improving the quality of wastewater (particularly BOD). Also, composting was satisfactory without any particular problem.

A polyester staple using 100% of 1.5d × 51 mm polyester staples and a polyester staple /
A garbage bag (B21, B22) similarly prepared by mixing rayon staples at a ratio of 75/25 was tested at the same time, but in B21 the garbage bag remained without any change,
B22 was slightly thinner but remained almost unchanged.

[0058]

According to the present invention, it is possible to provide a garbage bag which is flexible and easy to handle, has an improved decomposition rate in a natural environment, and is easy to dispose or compost, and is expected to greatly contribute to environmental protection. The product of the present invention also has the advantage that the productivity of raw material resin, fiber and film is improved, so that industrial production is easy and the cost is low. In addition, the main raw material of the product of the present invention is starch, which can fix carbon dioxide in the air, and is a crude raw material. Unlike the extinction, it is expected that carbon dioxide in the air will not increase much and will contribute to the prevention of global warming.

Claims (2)

[Claims] 1. (1) A crystalline polylactic acid (A) having a melting point of 150 ° C. or higher, and an aliphatic polyester (B) having a chain diol and an aliphatic dicarboxylic acid as main components and a melting point of 140 ° C. or lower.
(2) a block copolymer (C) of the polylactic acid (A) and the aliphatic polyester (B), and (3) a polylactic acid (A) and / or the aliphatic polyester (B). ) And the above-mentioned block copolymer (C), "wherein at least one composition is selected from the group consisting of lactic acid-derived components and 50 to 99% by weight;
The ratio of the component derived from the aliphatic polyester is 1 to 50% by weight.
A naturally degradable garbage bag containing 50% by weight or more of a fiber and / or a film produced from the polymer composition as described above. 2. A fiber and / or film comprising a polyester composition containing from 60 to 95% by weight of a component derived from lactic acid, containing at least 50% by weight of a polyester composition, and selected from the group consisting of natural fibers, cellulose fibers and cellulose films. A garbage bag according to claim 1, comprising at least one material.