JPH10251492A - Naturally degradable resin composition and molded product thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a composition having the action of promoting plant growth and the action of inhibiting the multiplication of harmful bacteria and is degradable in the natural environment by mixing an aliphatic polyester with inorganic glass particles having the capability of releasing ions of at least two kinds of elements selected from the group consisting of P, K, Mg, etc., and/or a water soluble compound into water. SOLUTION: The aliphatic polyester (A) is a polymer obtained by polymerizing an aliphatic hydroxy acid, an aliphatic lactone, an aliphatic diol and an aliphatic dicarboxylic acid, etc., and is exemplified by a polyethylene succinate, a poly-L-lactic acid, a polyglycol or the like being a crystalline and having a melting point of 110 deg.C or above and is desirably a polylactic acid or a modified polylactic acid containing at least 60wt.% lactic acid component. The molecular weight is 50,000 or above. The inorganic glass (B) is an amorphous or lowly crystalline and is a mixture comprising oxides of at least two metals selected among P, K, Mg, Ca, B, Mn, Mo, Fe, Cu and Zn. Component B is used in an amount of 0.1-50wt.% based on the resin composition, and component A is used in an amount of 99.9-50wt.% based on the resin composition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel resin composition which is naturally degradable and contains components useful for plant growth, and is suitable for plant cultivation, and a molded product thereof.

[0002]

2. Description of the Related Art Petroleum-based synthetic resins are widely used because of their excellent performance and low cost. However, they have low degradability in the natural environment and generate large amounts of heat during incineration. It needs to be reviewed from a protection standpoint. A large amount of synthetic resin products are used in agriculture, forestry, horticulture, and other plant cultivation, but they do not decompose in the natural environment, causing environmental pollution, and causing problems because of their troublesome disposal. I have. For this reason, spontaneously degradable resins made of aliphatic polyesters are being developed, but at present, products that are not only degradable but also more suitable for plant cultivation are being demanded.

[0003]

It is preferable that the plant cultivation article has an action of promoting plant growth. Further, the action of suppressing the growth of harmful bacteria is also preferable. It is an object of the present invention to provide a resin composition having these functions and decomposing in a natural environment, and a molded product thereof.

[0004]

The object of the present invention is to provide an aliphatic polyester (A) comprising P, K, Mg, Ca, B,
Inorganic glass particles (B) that release ions of at least two elements selected from the group consisting of Mn, Mo, Fe, Cu and Zn and / or a water-soluble compound into water, and (A) contains 99 0.9 to 50% by weight, (B) 0.1 to 50%
Achieved by a naturally degradable resin composition that occupies weight percent.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The aliphatic polyester (A) is a polymer obtained by polymerizing an aliphatic hydroxy acid, an aliphatic lactone, an aliphatic diol, an aliphatic dicarboxylic acid and the like, and a small amount thereof (for example, 30% by weight). (Preferably 10% by weight or less)) in which other components are copolymerized and / or mixed.

Examples of the raw materials for the polymerization of aliphatic polyesters include (a) aliphatic hydroxy acids such as glycolic acid and hydroxybutyl carboxylic acid, (b) aliphatic lactones such as glycolide, butyrolactone and caprolactone;
(C) aliphatic diols such as ethylene glycol, propylene glycol, butanediol and hexanediol; (d) diethylene glycol, triethylene glycol, ethylene / propylene glycol, dipropylene glycol, dihydroxyethoxybutane, polyethylene glycol, polypropylene glycol, polyethylene / Oligomers and polymers of polyalkylene ethers such as propylene glycol, (e) oligomers and polymers of aliphatic polycarbonates such as polypropylene carbonate, polybutylene carbonate, polyhexane carbonate, (f) succinic acid, adipic acid, suberic acid, azelaic acid, Examples include aliphatic polyester raw materials such as aliphatic dicarboxylic acids such as sebacic acid and decane dicarboxylic acid.

Also, aromatic components such as terephthalic acid, isophthalic acid, hydroxybenzoic acid, and naphthalenedicarboxylic acid can be applied in a small amount (for example, 10% by weight or less). Even if it contains such a small amount of aromatic components,
Considered substantially as an aliphatic polymer.

The aliphatic polyester used in the present invention is crystalline and has a melting point of 8 from the practicality such as moldability, heat resistance and strength.
The temperature is preferably at least 0 ° C, more preferably at least 110 ° C, particularly preferably at least 130 ° C.

Examples of polyester having a melting point of 110 ° C. or higher include polyethylene succinate (melting point: about 116 ° C.)
Poly L-lactic acid (melting point about 175 ° C), poly D-lactic acid (melting point about 175 ° C), polyhydroxybutyrate (melting point about 18 ° C)
0 ° C.), polyglycolic acid (melting point: about 230 ° C.), and those obtained by copolymerizing or mixing a small amount (for example, 30% or less) of these components with other components.

Among them, polylactic acid and lactic acid component are used in 60
Modified polylactic acid (by copolymerization and / or mixing of other components) containing not less than% by weight is excellent in performance (heat resistance, strength), wide decomposition rate and cost, and is most preferable.

In general, aliphatic polyesters having a high melting point, such as polylactic acid, are hard and brittle, but those having relatively low melting points, such as polybutylene succinate, polybutylene adipate (melting point of about 69 ° C.), and polyethylene sebacate (melting point of about 69 ° C.) 72 ° C.), polycaprolactone (melting point about 6
(0 ° C.) or the like, which is mixed with about 3 to 30% by weight or block copolymerized to improve flexibility, impact resistance, decomposition rate, etc. without significantly lowering the melting point. Can be done.

A copolymer of L-lactic acid and D-lactic acid, which are optically active monomers, is more preferable because the melting point and the crystallinity can be arbitrarily controlled.

Similarly, those obtained by improving the decomposition rate, moldability, mold release, stability, etc. by mixing or copolymerizing other components are preferably used in the present invention. Polylactic acid homopolymer has the slowest decomposition rate among aliphatic polyesters (can be used for a long period of time), but the decomposition rate can be increased by mixing or copolymerizing other components, and a wide range of decomposition rates can be obtained. .

The molecular weight of the aliphatic polyester used in the present invention is not particularly limited, but is preferably 50,000 or more,
The range of 300,000 is more preferable, and the range of 80,000 to 200,000 is particularly preferable in many cases.

The inorganic glass particles (B) used in the present invention are:
P, K, Mg, Ca, B, Mn, Mo, Fe, Cu, Z
It has the ability to release ions and / or water-soluble compounds of at least two elements selected from the group n into water.

The inorganic glass is a mixture of a plurality of metal oxides and is non-crystalline or low-crystalline (usually, the degree of crystallinity is 50% or less, preferably 30% or less). Are preferred.

The inorganic glass particles (B) used in the present invention are:
P, K, Mg, Ca, B, Mn, Mo, Fe, Cu, Z
Those containing, as a component, oxides of at least two elements selected from the group of n are preferable.

For the growth of plants, the required elements differ depending on the time of growth, and it is preferable to have a plurality of them. For example, the preferable content of the oxide is, based on the total amount of the inorganic glass particles (B), P ₂ O ₅ : at most 65% by weight, particularly 55 to 10% by weight, K ₂ O: at most 35% by weight,
Especially 30 to 5% by weight, MgO: at most 45% by weight, especially 4
0-5% by weight, CaO: at most 45% by weight, especially 40-5%
Wt%, B ₂ O _3: at most 65% by weight, especially 50 to 5 wt%, MnO: at most 45% by weight, in particular 40 to 1 wt%, M
o ₂ O ₃ : at most 25% by weight, especially 20 to 2% by weight, Fe
₂ O ₃ : at most 25% by weight, especially 20 to 2% by weight, Cu
O: At most 25% by weight, particularly 20 to 2% by weight.

From the glass mixed with them, for example, phosphoric acid, phosphate ion, potassium ion, magnesium ion, calcium ion, borate ion, manganese ion, molybdenum ion, iron ion, copper ion, zinc ion, or any of them Metal hydroxides are gradually released into water and are effective as plant nutrients.

[0020] Zinc ions and copper ions have the effect of suppressing bacteria and have the effect of preventing plant diseases and decay. The inorganic glass particles (B) used in the present invention may contain a small amount (usually 50% or less, preferably 30% or less) of components other than the above-mentioned effective components, such as silicon oxide and aluminum oxide.

The inorganic glass particles (B) used in the present invention are:
The components gradually elute when immersed in water. The hydrogen ion concentration index PH of water changes depending on the components eluted and the amount thereof. However, if the pH is 7.5 or more alkaline, the decomposition of the aliphatic polyester is promoted.
Suitable for use within a year (part of agriculture and horticulture).

The amount of the inorganic glass particles (B) is from 0.1 to 50% by weight, preferably from 5 to 45% by weight, particularly preferably from 10 to 40% by weight, based on the total amount of the resin composition. When the amount of the inorganic glass particles (B) is less than 0.1% by weight, the dissolution rate and the dissolution amount are small, and the effect on plant growth is small.
On the other hand, when the content exceeds 50% by weight, not only does the operation efficiency and productivity significantly decrease in producing the resin composition,
The physical properties and handleability of the product also deteriorate.

In the case where the pH is 7 or neutral or the acidity is 7 or less, the decomposition is not promoted so much that it is suitable for long-term use. Therefore, it is possible to adjust the components of the inorganic glass used in the present invention, adjust the amounts of the acidic components and the alkaline components in the components eluted in water, and adjust the PH of the eluted components to the intended use. Generally, when planting a plant or using a seeded sheet for civil engineering,
It is desirable that the strength be maintained, and the PH
Is preferably neutral or weakly acidic (pH of about 7 to 5).

The size of the inorganic glass particles (B) used in the present invention is not particularly limited, but the average particle size is 0.01 μm to 1 μm.
Those having a size of about 00 μm are preferably used. For example, for fibers and films, the average particle size is preferably 0.01 μm to 2 μm, particularly preferably about 0.1 μm to 1.5 μm, and for extrusion molding or injection molding, 0.01 μm to 100 μm,
Particularly, those having a thickness of about 0.1 μm to 20 μm are preferable,
Most preferably, the range is from 0.1 μm to 10 μm.

The shape of the particles is arbitrary, and may be spherical, strip-like, needle-like, amorphous, or the like. Similarly, the particles may be porous, which increases the release rate of ions and water-soluble components. Similarly, when the porosity and particle size are small, the adsorbability of other substances is enhanced, and the above-mentioned effective element components (ions and compounds) can be adsorbed and contained.

As effective (fertilizer) components other than the above elements,
It is also useful to use a compound containing a nitrogen compound, such as nitric acid, nitrate, ammonia, or ammonium salt, which is a nutrient for plants.
Similarly, for the purpose of improving dispersibility in a resin and improving (e.g., suppressing) the release rate of an active ingredient, those obtained by subjecting particles to surface treatment with a fat or oil, a surfactant, a polymer, or the like are also preferably used.

The above-mentioned special glass particles used in the present invention are dispersed in pure water 10 times (by weight), and when left at 20 ° C. for 24 hours, the total amount of the active ingredient elements extracted in the water is 1 ppm or more. , Preferably 5 ppm or more.

The method for producing the composition of the present invention, in particular, the mixing method is not limited, but the special glass particles can be mixed in a molten state of the aliphatic polyester or in a solvent solution. At the time of mixing, there is no or extremely low moisture,
It is preferable to prevent decomposition of the aliphatic polyester. For example, the moisture content of the mixed system is preferably 20 ppm or less,
pm or less is particularly preferable, and 5 ppm or less is most preferable.

Similarly, at the time of melt polymerization or solution polymerization of an aliphatic polyester, glass particles may be mixed with a raw material for polymerization,
It can also be mixed during the polymerization process. For example, an aliphatic polyester may be melted by a screw extruder, glass particles may be added to the molten polymer, and the mixture may be continuously mixed by a single or twin screw extruder. Similarly, a static mixer that performs flow division and merging in multiple stages may be used, or a static mixer and a mechanical stirring device may be used in combination.

When mixing in a solution state, the mixing may be performed continuously or intermittently in a container having a stirring device. In order to improve the mixed state or the dispersed state of the particles, or to enhance the hydrophobicity of the particles, a dispersant, a surfactant, a fat or oil, a silicone oil or a silicone resin, a fluorine compound, or the like can be applied.

In the composition of the present invention, in addition to the aliphatic polyester as the main component and the above-mentioned special glass particles, an antioxidant, an ultraviolet absorber, a coloring agent, a pigment, a dye, a release agent, an antibacterial agent, As needed, a property improving agent, a dispersant, a surfactant, other various additives, various polymers, inorganic compounds, particles of metal and the like, fibers, various fillers, and the like can be appropriately mixed.

The composition of the present invention is used at least in part.
Fibers, yarns, strings, ropes, knits, woven fabrics, nonwoven fabrics, and other fibrous structures, films, sheets, composite materials, extruded products, injection molded products, capsule-shaped structures, and other molded products are especially cultivated products for plants. Extremely useful and effective.

When a large amount of glass particles, for example, fibers, are mixed with each other, friction tends to cause abrasion or damage of a partner (gaite, knitting needle, etc.). The problem of abrasion can be solved by forming a core / sheath composite fiber by using a polymer containing only (for example, 2% or less) a sheath.

In the case of a film or sheet, a composite structure in which a polymer containing glass particles is disposed in the inner layer and a polymer is disposed in the outer layer can improve abrasion and other problems. In this case, the composite ratio (volume ratio) of the core and the sheath is optional, but is, for example, in the range of 1/9 to 9/1, particularly 3/7 to 7 /.
A range of 3 is preferably used. Further, a fiber and a film or a resin can be combined.

Examples of uses and products in which the composition of the present invention is particularly preferably used include vegetation cloths and nonwoven fabrics, sheet-like, cloth-like or tape-like materials to which seeds and seedlings are attached, nursery pots, flowerpots, Examples include piles, seedling protection sheets, bags, ropes, root protection sheets and packaging materials. When growing within a year and firmly rooting, aliphatic polyester with a relatively short decomposition time is suitable.For plants that take a long time to firmly root, seeded sheets for reinforcing slopes, etc. Preferably, the time is two years or more. In the former,
A composition using glass particles having a pH of 8 or more can be preferably applied, and the latter is preferably a composition using glass particles having a pH of 7 or less.

[0036]

EXAMPLES In the following examples,% and parts are by weight unless otherwise specified. Example 1 L-lactide was mixed with 100 ppm of tin octylate, polymerized in a twin-screw kneading extruder at 188 ° C. for 8 minutes in a nitrogen atmosphere, cooled, formed into chips, and then treated in a nitrogen atmosphere at 140 ° C. Phase polymerization) to obtain a poly-L-lactic acid homopolymer P1. P1 had a melting point of 177 ° C. and a molecular weight of 15,000.

P ₂ O ₅ 45%, B ₂ O ₃ 10%, K ₂ O
25%, CaO 8%, ZnO 3%, MgO 4%, CuO
Glass particles having a composition of 4% and an average particle diameter of 0.8 μm are defined as G1. 2 at 200 ° C in 1 Torr of nitrogen gas
The particles G1 dried for 4 hours were added at 120 ° C.
A mixture of 5% of magnesium stearate dried at 0 Torr for 10 hours was mixed at 195 ° C. using a twin screw extruder.
A mixture obtained by mixing 10% with respect to the polymer P1 is referred to as a polymer P2.

The melted polymer P2 was used as a core, and the separately melted polymer P1 was used as a sheath. The two were combined in a core-in-sheath shape at a volume ratio of 2/1, and were spun through a circular die hole of 220 ° C. and 0.30 mm in diameter. Out, cool in air and apply oil agent 15
It is wound at a speed of 00 m / min, plied into a 500,000 denier tow, stretched 2.9 times at 90 ° C., crimped by a press-type crimping device, cut, and cut to a single yarn fineness of 4.5 denier. And a staple S1 having a length of 55 mm. For comparison, a single-component staple similarly obtained from the polymer P1 alone is designated as S2.

A nonwoven fabric having a basis weight of 75 g / m ² was produced by the card method using the staple S1, and the starch paste was mixed with the seeds of western turf and air-dried to obtain F1. For comparison, the staple S2 is used, and the nonwoven fabric with seeds obtained in the same manner is referred to as F2. Similarly, for comparison, a nonwoven fabric made of ordinary polyethylene terephthalate (PET) staples and attached with grass seeds is referred to as F3.

The above-mentioned nonwoven fabric with seeds is arranged on a field soil adjusted to pH 7 using slaked lime.
The plants were cultivated for 90 days in a greenhouse at 20 ° C. with water once a week and a 0.05% ammonium chloride solution twice a week in a greenhouse at 0 ° C. The weight per turf at that time was 0.12 g using the nonwoven fabric F1 (the present invention), and 0.08 g using the nonwoven fabric F2 (comparative example).
And the nonwoven fabric F3 (comparative example) was 0.06
g.

Thus, the nonwoven fabric F1 according to the present invention
It can be seen that the effect of raising the seedlings is clear. The non-woven fabric F2 having no nutrients (Comparative Example) is a normal PET.
It is considered that the effect of the polylactic acid is slightly higher than that using the nonwoven fabric F3 (Comparative Example).

Example 2 88 parts of L-lactide, molecular weight 14 having hydroxyl groups at both ends
10 parts of polybutylene succinate, 5 parts of ethylene glycol (EG), 3 parts of polyethylene glycol (PEG) having a molecular weight of 10,000 having hydroxyl groups at both ends, 0.1 part of Irganox 1010, an antioxidant from Ciba-Geigy, A mixture of 0.01 part of tin octylate and poly L-lactic acid / polybutylene succinate (PBS) / PE having a molecular weight of 140,000 and a melting point of 172 ° C. was prepared in the same manner as in the case of the polymer P1 of Example 1.
A G block copolymer BP1 was obtained.

Using BP1, a staple S4 was obtained in the same manner as the staple S1 of Example 1, and a non-woven fabric F4 with seeds (the present invention) was similarly obtained using the staple S4. Non-woven fabric F
4 was cultivated for 90 days in the same manner as in Example 1, and the weight per seedling was 0.13 g. The reason why the non-woven fabric F4 has a slightly higher growth effect than the non-woven fabric F1 of Example 1 is that the copolymerization of PBS and PEG having low glass transition temperatures accelerates the diffusion rate of water and active ingredients in polylactic acid. Seem.

[0044]

Industrial Applicability According to the present invention, there is provided a composition which is naturally degradable, less polluting the environment, and has an effect of promoting the growth of plants, comprising fibers, yarns, ropes, strings, knits,
Textile structures such as woven fabrics and nonwoven fabrics, films, sheets, composite materials containing fibers, injection molded products, extrusion molded products, various vegetation sheets, seedling raising materials, horticultural materials and supplies, agricultural materials and supplies, forestry materials and supplies, planting It can be suitably and effectively used for purposes such as cultivation, cultivation and protection of plants, such as planting and civil engineering materials and supplies. In particular, when polylactic acid is used as a main component, since the raw material lactic acid is obtained from agricultural products such as starch and cellulose, there is a characteristic that it has less adverse effects on the environment than synthetic resin products using petroleum as a raw material.

Claims (4)

[Claims] 1. An aliphatic polyester (A), comprising P, K,
Inorganic glass particles (B) capable of releasing ions of at least two elements selected from the group consisting of Mg, Ca, B, Mn, Mo, Fe, Cu and Zn and / or a water-soluble compound into water. A naturally decomposable resin composition containing 99.9 to 50% by weight of (A) and 0.1 to 50% by weight of (B). 2. The inorganic glass particles (B) having an average particle size of 0.
The resin composition according to claim 1, which has a content of 1 to 10 µm and a content of 5 to 45% by weight. 3. An inorganic glass particle (B) comprising P, K, M
The resin composition according to claim 1, comprising an oxide of at least two elements selected from the group consisting of g, Ca, B, Mn, Mo, Fe, Cu, and Zn. 4. A molded product for plant cultivation, comprising at least a part of the composition according to claim 1.