JP2003183483A - Biodegradable fertilizer bag - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a biodegradable fertilizer bag which is soft and excellent in bleed-out resistance and heat seal strength. <P>SOLUTION: This biodegradable fertilizer bag is prepared by heat sealing at least one side of a biodegradable film and has a heat seal strength of 15 N/15 mm or higher. The film contains (A) polylactic acid, (B) a biodegradable aliphatic-aromatic copolyester having a glass transition point of 0°C or lower, (C) a plasticizer, and (D) an inorganic filler. The method for producing a biodegradable fertilizer bag comprises heat sealing at least one side of a biodegradable film at 260-280°C in a sealing time of 0.1-1 sec. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fertilizer bag biodegradable by composting, which is formed into a bag by heat-sealing a biodegradable film. More specifically, polylactic acid comprises a biodegradable film obtained by blending a specific biodegradable aliphatic-aromatic copolyester component and a plasticizer component, and further an inorganic filler component, at least one of which is heat. The present invention relates to a biodegradable fertilizer bag that is sealed and has a heat sealing strength of 15 N / 15 mm or more.

[0002]

2. Description of the Related Art Conventionally, as a fertilizer bag used for home gardening and agricultural production, a polyethylene fertilizer bag is mainly used because it is easy for a user to handle, easy to produce, and inexpensive. Came. These fertilizer bags are treated as waste after the fertilizer is sprayed, but in many cases, they are either landfilled as non-burnable garbage or treated by field burning, which is gradually prohibited by the regulations. At present, it has never been environmentally friendly. However, in recent years, with the increasing social demand for environmental protection, there has been a movement to change the fertilizer bag to a material having a low environmental load. Biodegradable resins that are decomposed by microorganisms have been attracting attention as one of the candidates. Biodegradable resin can be processed into films using the same method as polyethylene and existing machines, and the obtained films have the same level of physical properties as existing products. It is a new type of plastic that can be completely decomposed into water and carbon dioxide by microorganisms etc. by composting once the purpose of use is over. Specific examples of the biodegradable resin include aliphatic polyesters such as polybutylene succinate, polycaprolactone and polylactic acid, and terephthalic acid / 1,4
-A melt-moldable polyester such as an aliphatic-aromatic copolyester which is a butanediol / adipic acid copolymer.

Of the above biodegradable resins, a fertilizer bag formed from a film of an aliphatic polyester other than polylactic acid or an aliphatic-aromatic copolyester has practical physical properties such as film strength and heat sealing strength. There is no problem in use. However, since the fertilizer bags made of these biodegradable resin films are decomposed by microorganisms, decomposition by microorganisms progresses during long-term storage of the product, resulting in holes in the film or embrittlement of the film for long-term storage. There was a problem with sex. In addition, in the sense of using biodegradable resin, that is, in the sense that composting is used to decompose not only conventional incineration but also garbage and agricultural residues to reduce the environmental load, it is completely insufficient. is there. That is, when the composting process is performed, the film may not be decomposed at all within the required time, or the film may be entangled with the agitator in the composting device due to insufficient decomposition, and in the worst case, the machine may be broken. It was In addition, the fertilizer bag made of these biodegradable resin films was 4-8 times as expensive as the polyethylene fertilizer bag, which was very expensive.

On the other hand, polylactic acid, among aliphatic polyesters, is widely distributed in nature, is harmless to animals and plants and humans and animals, and has a melting point of 140 to 175 ° C., so that it has sufficient heat resistance and is practical. Excellent and polyethylene 2
Since the resin price is three times higher, it is expected as a relatively inexpensive biodegradable thermoplastic resin. Therefore, studies have been conducted to apply a polylactic acid film to a fertilizer bag, but the polylactic acid film is hard and fragile to impact, and if it is dropped, it can be easily broken, and a bag with practical suitability is obtained. However, improvement of flexibility and impact strength has been demanded.

Therefore, in order to improve the flexibility and impact resistance of the polylactic acid-based film, a method in which a plasticizer is added to polylactic acid or lactic acid and another hydroxycarboxylic acid to promote plasticization of the resin composition (Patent No. 3105020) has been proposed. In this method, in order to give the resin composition flexibility suitable for practical use, a considerable amount of a plasticizer must be blended with the polylactic acid, but originally, it has a good compatibility with the polylactic acid. Most of the plasticizers bleed out because they are very small in amount, which causes blocking between the films after film formation and deterioration of the mouth opening property when tailored into a bag, and the ink used for printing plasticizes. There was a problem in practicability as a bag such that the agent flows out due to bleed-out and the appearance as a product. Furthermore, the decrease in glass transition temperature due to the plasticizer can easily improve the molecular motion at room temperature, but on the other hand, it accelerates hydrolysis and significantly shortens the shelf life of the film, resulting in storage stability as a fertilizer bag. There was a serious problem of being inferior.

Further, it has been shown that a cup formed by vacuum molding using a sheet made of a polylactic acid polymer and a biodegradable aliphatic polyester having a glass transition temperature of 0 ° C. or less has excellent impact resistance ( In Japanese Patent Laid-Open No. 9-111107), the impact strength of a thin film is insufficient in practical use, and there is a problem that the bag is broken especially in applications such as a fertilizer bag.

To solve the above problems, a film or sheet is formed from a resin composition of polylactic acid, a biodegradable aliphatic polyester having a melting point of 80 to 250 ° C. and a plasticizer. (JP-A-11-11
6788), and by forming an inflation film from polylactic acid, a biodegradable aliphatic polyester having a glass transition temperature of 0 ° C. or less, and a plasticizer (JP-A-2000-273207), flexibility and resistance can be improved. Methods have been proposed to improve impact resistance. In this method, the above problem can be solved by plasticizing polylactic acid, which is originally high in rigidity, with a plasticizer and blending an aliphatic polyester that is softer than polylactic acid. However, since the aliphatic polyester used here is easily crystallized in the film forming process and has high crystallinity, the plasticizer distributed in the aliphatic polyester cannot be retained. Therefore, in the film obtained by the above method, the plasticizer bleeds out, resulting in deterioration of the opening of the bag, blocking between the films, outflow of the printing ink, and decrease in heat seal strength over time. However, problems such as poor practicability have arisen, and these cannot be fully solved.

[0008]

DISCLOSURE OF THE INVENTION The present invention is an unstretched film, which has been difficult with conventional polylactic acid-based films as described above, and even if a considerable amount of a plasticizer is blended, the bleed-out of the plasticizer does not occur. Not seen, blocking between films after film formation and during bag making, opening of bag is good, ink does not flow out, storage stability is also excellent, heat seal strength is improved and raw deterioration is improved. It is intended to provide a fertilizer bag made of a degradable film.

[0009]

Means for Solving the Problems As a result of intensive studies conducted by the present inventors, polylactic acid was blended with a specific biodegradable aliphatic-aromatic copolyester, a plasticizer and an inorganic filler at a specific ratio. It has been found that the above-mentioned film can solve the above-mentioned problems and that the sealing strength is improved by heat-sealing under a certain specific condition, and the present invention has been accomplished. That is, the gist of the present invention is as follows.

A fertilizer bag in which at least one of the biodegradable films is heat-sealed, wherein the biodegradable film is polylactic acid (A) and the glass transition temperature is 0 ° C. or less. A biodegradable fertilizer bag containing a copolyester (B), a plasticizer (C), and an inorganic filler (D) and having a heat-sealing strength of 15 N / 15 mm or more.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below. Examples of the polylactic acid (A) used in the present invention include poly L-lactic acid whose lactic acid structural unit is L-lactic acid, poly D-lactic acid whose structural unit is D-lactic acid, and further L-lactic acid and D-lactic acid. Poly DL-lactic acid, which is a copolymer of, or a mixture thereof. The number average molecular weight of polylactic acid is preferably 80,000 to 150,000. Further, in order to suppress the bleed-out of the plasticizer and to secure the film-forming stability by crystallization of polylactic acid, it is preferable to use a combination of crystalline polylactic acid and amorphous polylactic acid, and the ratio thereof is crystalline polylactic acid / Amorphous polylactic acid is preferably 50/50 to 90/10 (mass%). The crystalline polylactic acid referred to here is 140 to 175 ° C.
It means a polylactic acid resin having a melting point in the range of, and the amorphous polylactic acid means a polylactic acid resin having substantially no melting point. When the proportion of crystalline polylactic acid is less than 50% by mass, the polylactic acid is inferior in crystallization and stable film formation cannot be performed. On the other hand, if the proportion of crystalline polylactic acid exceeds 90% by mass, the plasticizer cannot be retained and bleed out of the plasticizer occurs during or after film formation.

In the present invention, the biodegradable film contains a biodegradable aliphatic-aromatic copolyester (B) having a glass transition temperature of 0 ° C. or lower as an essential component. In the conventional biodegradable aliphatic polyester, the dicarboxylic acid component constituting the polyester is an aliphatic dicarboxylic acid, so the melting point of the obtained resin is low (about 115 ° C.),
Moreover, when a component such as adipic acid is generally copolymerized for the purpose of imparting flexibility, the melting point is further lowered to cause deterioration of the processability of the resin, and therefore the component for imparting flexibility cannot be copolymerized so much. It was Therefore, the crystallinity of the resulting aliphatic polyester resin does not significantly decrease, so that the resin becomes highly crystalline, and when a plasticizer is added,
Bleedout was observed because the plasticizer could not be retained sufficiently.
However, the aliphatic-aromatic copolyester (B) having a glass transition temperature of 0 ° C. or lower used in the present invention.
Since the aromatic dicarboxylic acid is used as a constituent component of the polyester, it can be designed at a relatively high melting point.
Therefore, it becomes possible to copolymerize an aliphatic dicarboxylic acid that induces a melting point decrease in a larger amount than in the case of an aliphatic polyester. This makes it possible to design a resin in which the crystallinity is lowered by copolymerizing the aliphatic dicarboxylic acid component to such an extent that the workability of the resin is not adversely affected (melting point: about 100 ° C.). This makes it more flexible than the aliphatic polyester and significantly improves the retention of the plasticizer,
The bleed-out resistance could be improved.

When the crystallinity of the aliphatic-aromatic copolyester is high, that is, the heat of fusion of melting (ΔHm) is large, the excluded volume effect and the lack of the amorphous region associated with the crystallization cause bleeding out of the plasticizer. It becomes difficult to hold the plasticizer in the resin. Therefore, although the crystal fusion heat amount (ΔHm) of the obtained resin is different depending on the copolymerization composition ratio of the aromatic dicarboxylic acid component and the aliphatic dicarboxylic acid component, in the present invention, the aliphatic resin having a glass transition temperature of 0 ° C. or lower is used. -The heat of crystal fusion (ΔHm) of the aromatic polyester copolymer (B) is preferably 25 J / g or less. When the amount of heat of fusion of crystal (ΔHm) of the aliphatic-aromatic copolyester (B) exceeds 25 J / g, the plasticizer cannot be retained and the bleed of the plasticizer cannot be maintained due to the decrease of the amorphous region due to the improvement of the crystallinity of the resin. Out becomes remarkable.

The biodegradable aliphatic-aromatic copolyester (B) having a glass transition temperature of 0 ° C. or lower used in the present invention is obtained by condensing an aliphatic diol with an aromatic dicarboxylic acid or an aliphatic dicarboxylic acid. Obtainable. Examples of the aliphatic diol constituting the aliphatic-aromatic copolyester (B) include ethylene glycol, propylene glycol, 1,4-butanediol and 1,4-
Examples of aromatic dicarboxylic acids include terephthalic acid, isophthalic acid, and naphthalenedicarboxylic acid, and examples of aliphatic dicarboxylic acids include succinic acid, adipic acid, suberic acid, sebacic acid, and dodecanoic acid. is there. And each of these 1
It can be obtained by selecting more than one kind and polycondensing. If necessary, it can be crosslinked with a polyfunctional isocyanate compound.

In the present invention, the content ratio of polylactic acid (A) constituting the biodegradable film and the biodegradable aliphatic-aromatic copolyester (B) having a glass transition temperature of 0 ° C. or less is 95/5 to 30. It is preferably / 70 (mass%), further preferably 80/20 to 50/50 (mass%), and more preferably 80/20 to 60/40 (mass%). When the content ratio of polylactic acid exceeds 95% by mass, the fertilizer bag obtained is inferior in flexibility, and the physical properties of the film are rapidly deteriorated due to the decrease in molecular weight due to hydrolysis, which is a practical problem. Polylactic acid content ratio is 3
If it is less than 0% by mass, the aliphatic-aromatic copolymerized polyester component is the main component and the decomposition is remarkably delayed. Therefore, the film is entangled with the stirring blades in the decomposition process using a composting device or the like, which may damage the composting device, which is not preferable.

In the present invention, the biodegradable film contains a plasticizer (C) as an essential component. The plasticizer (C) used is compatible with the components (A) and (B), is non-volatile, is non-toxic from the viewpoint of environmental issues, and has passed the FDA. Those are preferable.
Examples of plasticizers that satisfy such conditions include ether ester plasticizers and oxyacid ester plasticizers. Specific examples of the ether ester plasticizer include bismethyldiethylene glycol adipate, bisbutyldiethylene glycol adipate, and the like.
Specific examples of the oxyacid ester plasticizer include tributyl acetyl citrate and the like. Two or more kinds of these plasticizers can be mixed and used.

The content of the plasticizer (C) is 4 to 30 parts by mass, preferably 5 to 20 parts by mass based on 100 parts by mass of the total of the components (A) and (B). When the content of the plasticizer (C) is less than 4 parts by mass, almost no decrease in the glass transition temperature of polylactic acid is observed, so that the obtained fertilizer bag becomes cellophane-like and has poor flexibility. When the content of the plasticizer (C) exceeds 30 parts by mass, the glass transition temperature of polylactic acid is excessively lowered and the hydrolysis rate of the fertilizer bag obtained is rapidly accelerated, resulting in too short product life and practical use. In addition to the above problem, bleeding out of the plasticizer occurs, resulting in problems such as film blocking during film formation and poor ink gluing so that printing cannot be performed.

In the present invention, the biodegradable film contains the inorganic filler (D) as an essential component. The purpose of this is to prevent the melt tension of the film from significantly lowering during film formation, as the resin is plasticized by the plasticizer.
It is to act as a crystal nucleating agent, and to suppress blocking during film formation and to impart slipperiness.

Examples of the inorganic filler (D) used in the present invention include talc, silica, calcium carbonate, magnesium carbonate, kaolin, mica, titanium oxide, aluminum oxide, zeolite, clay, glass beads, and other general inorganic fillers. In particular, talc is preferable because it exhibits the most effect as a crystal nucleating agent for polylactic acid. Moreover, you may use these inorganic fillers in mixture of 2 or more types.

The content of the inorganic filler (D) is preferably 5 to 40 parts by mass, more preferably 10 to 30 parts by mass, based on 100 parts by mass of the total of the components (A) and (B).
It is more preferably 10 to 20 parts by mass. When the content of the inorganic filler (D) is less than 5 parts by mass, the effect of the crystal nucleating agent of the inorganic filler does not appear, and the film only has difficulty in forming due to insufficient melt tension of the film during film formation. In addition, the film itself is inferior in slipperiness and blocking resistance, which may cause problems in processing such as post-processing. on the other hand,
When the content of the inorganic filler (D) exceeds 40 parts by mass,
The physical properties of the obtained film (fertilizer bag), particularly tear strength, heat seal strength, etc. are remarkably reduced, which poses a practical problem.

Further, in the present invention, an organic lubricant may be used in combination with the inorganic filler. Specific examples of the organic lubricant include, for example, liquid hydrocarbons, microcrystalline wax, natural paraffins, synthetic paraffins and other aliphatic hydrocarbon lubricants, stearic acid, lauric acid, hydroxystearic acid, fatty acid lubricants such as hydrogenated castor oil, and eruca. Fatty acid amide lubricants such as acid amide, stearic acid amide, oleic acid amide, ethylenebisstearic acid amide, ethylenebisoleic acid amide, ethylenebislauric acid amide, aluminum stearate, lead stearate, calcium stearate, magnesium stearate, etc. Soluble lubricants of fatty acid metal salts having 12 to 30 carbon atoms, fatty acid (partial) ester lubricants of polyhydric alcohols such as glycerin fatty acid ester and sorbitan fatty acid ester, butyl stearate ester And long chain esters fatty ester lubricant, such as wax or a composite lubricant These were combined, such as montan wax.

In the present invention, for the purpose of suppressing a decrease in melt tension during film formation, a crosslinking agent such as an organic peroxide and a crosslinking aid are used in combination, if necessary, to lightly crosslink the resin composition. Is also possible. Specific examples of the cross-linking agent include n-
Butyl-4,4-bis-t-butylperoxyvalerate, dicumyl peroxide, di-t-butyl peroxide, di-t-hexyl peroxide, 2,5-dimethyl-2,5-di (t -Butylperoxy) hexane, 2,5-dimethyl-2,5-t-butylperoxyhexyne-3 and other organic peroxides, phthalic anhydride, maleic anhydride, trimethyladipic acid, trimellitic anhydride, Polyvalent carboxylic acids such as 1,2,3,4-butanetetracarboxylic acid, lithium formate, sodium methoxide,
Metal complexes such as potassium propionate and magnesium ethoxide, bisphenol A type diglycidyl ether,
Epoxy compounds such as 1,6-hexanediol diglycidyl ether, trimethylolpropane triglycidyl ether, terephthalic acid diglycidyl ester, hexamethylene diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, xylylene diisocyanate And isocyanate compounds such as diphenylmethane diisocyanate.
Specific examples of the crosslinking aid include glycidyl methacrylate, normal-butyl methacrylate, hydroxypropyl monomethacrylate, polyethylene glycol monomethacrylate and the like.

The fertilizer bag of the present invention comprises an anti-ultraviolet agent, a light stabilizer, an anti-fog agent, an anti-fog agent, an antistatic agent, a flame retardant, an anti-coloring agent, an antioxidant, a filler, and white depending on the use. Additives other than the above, such as pigments of black, black and other colors, can be added.

Next, a method for producing the biodegradable film constituting the fertilizer bag of the present invention will be described, but the method is not limited to this. First, polylactic acid (A), a biodegradable aliphatic-aromatic copolyester (B) having a glass transition temperature of 0 ° C. or less, a plasticizer (C) and an inorganic filler (D) are mixed in predetermined amounts, and 2 Melt kneading with a shaft kneading extruder to produce compound pellets. After drying the compound pellets, a film is formed by an inflation film forming method. That is, the compound pellets after drying are charged into a single-screw kneading extruder, the molten polymer is pulled up from a round die into a cylindrical shape, and simultaneously air-cooled to be inflated into a balloon shape to form a film, or the molten polymer is melted from a round die. It can be formed into a film or a film by extruding it into a cylindrical shape together with cooling water, folding it once, pulling it up, and then expanding it into a balloon shape while heating. The polymer melting temperature of the twin-screw kneading extruder is the melting temperature of polylactic acid 2
The melting temperature of the polymer of the compound pellets in the single-screw kneading extruder is appropriately selected in the temperature range of 10 to 240 ° C., and the composition ratio of L-lactic acid and D-lactic acid of polylactic acid is (B).
The melting point and blending amount of the components and the blending amount of the component (C) are selected at appropriate times, but a temperature range of 160 ° C. to 200 ° C. is usually preferable. Further, when producing compound pellets, which is the pre-stage of film production, a crosslinking agent, a crosslinking aid, an organic lubricant, etc. can be added as necessary.
In addition, during film production, additives may be added, if necessary, to the extent that they do not affect the physical properties of the film.

The film thus formed is once wound on a roll, and then a bag is produced by a bag making machine in another step or a continuous step.

The biodegradable film thus obtained preferably has a glass transition temperature of 25 to 40 ° C. When the glass transition temperature is lower than 25 ° C., hydrolysis of polylactic acid is promoted even at room temperature, and mechanical properties and seal strength of the film are significantly deteriorated with time, which is a practical problem. When the glass transition temperature exceeds 40 ° C., the flexibility of the film decreases, which causes wrinkles in the film during film formation, or the elongation of the film decreases, and the film is easily broken, which is not preferable.

Next, a method for producing the fertilizer bag of the present invention from the biodegradable film will be described, but the method is not limited to this. When making a biodegradable film into a fertilizer bag,
The film is cut after being heat-sealed or at the same time as the heat-sealing, and the conditions of this heat-sealing have a significant influence on the practicality when the bag is made into a fertilizer bag and the seal strength change with time during storage. First, although it depends on the thickness of the film, the sealing temperature when heat-sealing a thick film having a thickness of 50 to 150 μm such as a fertilizer bag is 2
60-285 degreeC is preferable, More preferably, it is 270-
280 ° C. If the sealing temperature is less than 260 ° C,
Due to insufficient heat, the seal may become insufficient and the seal may come off. On the other hand, if the temperature exceeds 285 ° C., the temperature is too high and the boundary line is often broken at the boundary between the seal portion and the film, which causes a phenomenon of bottoming out of the fertilizer bag, which is a problem. On the other hand, when heat-sealing, keeping the amount of heat applied to the film for a certain period of time prevents breakage of the boundary line and improves the seal strength, thus preventing the film from being damaged and suppressing the decrease in seal strength over time. effective. The sealing time is preferably 0.1 to 1 second, more preferably 0.
2 to 0.8 seconds. If the time is shorter than 0.1 seconds, the sealing strength will be insufficient and the practical performance as a fertilizer bag will be a problem. If the sealing time exceeds 1 second, the time that heat is applied to the film becomes long and damages the film itself, causing breaks in the boundary line. It is not preferable because it causes a decrease.

The heat-sealing strength of the film produced as a fertilizer bag must be 15 N / 15 mm or more. Although it depends on the size of the bag, when the fertilizer is filled in the bag and the seal strength is less than 15 N / 15 mm, the seal part may come off and the bottom may come off, which is not preferable.

The fertilizer bag of the present invention manufactured by the above method is filled with bark compost, and when dropped together with the bag from a height of 1.2 M, it is dropped 5 times or more continuously in both horizontal drop and side drop. It is preferable not to break the bag. If the bag is broken with less than 5 drops, it is likely to break during transportation, which is not preferable.

[0030]

EXAMPLES Next, the present invention will be specifically described based on examples, but the present invention is not limited to these examples. In addition, the measurement of various physical properties in the following Examples and Comparative Examples was performed by the following methods. (1) Tensile strength (MPa), tensile elongation (%), tensile modulus (GPa): Measured according to JIS K-7127. (2) Heat-sealing strength: When a film piece prepared with a sample length of 50 mm and a sample width of 15 mm so as to be centered on the heat-sealed portion was pulled by a Toyo Bold AGS-100B at a pulling speed of 300 mm / min. The strength at which the seal part peeled off was defined as heat seal strength. (3) Dropping bag test A 45 L fertilizer bag manufactured by the method described in the example was filled with 15 kg of bark compost, and the bag mouth was sealed at a sealing temperature of 280 ° C., a sealing time of 0.4 seconds, and a sealing width of 15 mm. did. This bag was dropped from a height of 1.2 m.
At this time, the bag was dropped by two methods, horizontal and side. This operation was repeated, and the number of dropped bags when the bag broke was evaluated. (4) Bleedability of plasticizer, blocking property and opening property: When a bag obtained by bag-making a film produced by an inflation method is held at 80 ° C. under a load of 500 g in accordance with JIS Z0219. The bleeding property, blocking property, and opening property of the plasticizer were evaluated. The case where no bleedout was observed was evaluated as ◯, the case where a slight bleedout was observed was evaluated as Δ, and the case where bleedout was significantly observed was evaluated as x. In addition, the case where no blocking was observed and the opening property was good was evaluated as ◯, the case where the opening property was slightly difficult was evaluated as Δ, and the case where the blocking property was completely and not opened was evaluated as x. (5) After printing on the printable film with a flexographic printing machine, it was dried with hot air at 40 ° C. After that, attach a cellophane tape with a length of 50 mm and a width of 15 mm to the printed surface, and then peel off the cellophane tape to indicate that the ink has not peeled off at all on the cellophane tape, and that the ink has peeled off even a little on the cellophane tape. It was set to x.

Example 1 Crystalline polylactic acid (D-lactic acid = 1.2 mol%, weight average molecular weight 200,000, manufactured by Cargill Dow: Nature Works) and amorphous polylactic acid (D-lactic acid = 10 mol%) Of polylactic acid (A) having a weight average molecular weight of 200,000 and a mixing ratio of 70/30 (mass%) manufactured by Cargill Dow Co., Ltd. (Nature Works), aliphatic-aromatic copolyester (B) ( Glass transition temperature −30 ° C., heat of crystal fusion (Δ
Hm) 15 J / g, manufactured by BASF: Ecoflex F)
40 parts by mass, 8 parts by mass of bismethyldiethylene glycol adipate (manufactured by Daihachi Chemical Co., Ltd .: MXA) as a plasticizer (C), talc as an inorganic filler (D) (Up by Hayashi Kasei)
u HST-0.5, average particle size 2.75 μm) 15 parts by mass was weighed, and a twin-screw extrusion kneader (manufactured by Japan Steel Works: TE) was used.
X44α) was melt-kneaded to prepare a polylactic acid-based compound raw material at an extrusion temperature of 230 ° C. Next, this polylactic acid-based compound raw material was equipped with a circular die having a diameter of 200 mm, and the screw diameter was 90 mm.
Melt extrusion was performed at a set temperature of 190 ° C. The molten resin composition discharged from the die was expanded by air pressure and simultaneously formed into a tube while being air-cooled by an air ring. A film formed to have a film thickness of 90 μm and a film folding width of 500 mm is formed by a set of pinch rolls installed on the die.
It was collected at a speed of 4 m / min. After a cooling time of about 7 seconds, the tubular film was nipped by a pinch roll and wound by a winding machine for 1000 m. The composition was formed into a film in an environment where the temperature was controlled at 20 to 25 ° C. Next, the wound biodegradable film was printed by a flexographic printing machine at a pitch of 800 mm for each of the front and back sides. Ink drying temperature is set to 40 ℃, printing speed is 70m
/ Min. Next, using a bag-making machine (Nozaki company: Nozaki type high-speed turbo automatic bag-making machine KBS703L-30103), at a sealing temperature of 275 ° C., a sealing time of 0.25 seconds, a sealing width of 15 mm, and a bag-making speed of 55 m / min. Only one side was heat-sealed and then cut automatically to prepare a fertilizer bag for 45 L. Table 1 shows various physical property values of the fertilizer bag thus obtained.

Example 2 Tributyl acetyl citrate (made by Taoka Chemical Co., Ltd .:
ATBC), and a biodegradable film was produced in the same manner as in Example 1 except that the blending amount was changed to 10 parts by mass. Then, using the same printing machine and bag making machine as in Example 1, one side was heat-sealed under the same conditions as in Example 1, and then automatically cut to produce a 45 L fertilizer bag. Table 1 shows various physical properties of the obtained fertilizer bag.

Comparative Example 1 Instead of the aliphatic-aromatic copolyester of Example 1, an aliphatic polyester polybutylene succinate adipate (manufactured by Showa Polymer Co., Ltd .: Bionole # 300) was used.
A film having a thickness of 90 μm and a film width of 500 mm was obtained in the same manner as in Example 1, except that the compounding amount, the compounding conditions, the film forming conditions, etc. were used except that 1) was used. Thereafter, printing and bag making were carried out under the same conditions as in Example 1 to produce a 45 L fertilizer bag. Table 1 shows various physical properties of the obtained fertilizer bag.

COMPARATIVE EXAMPLE 2 The procedure of Example 1 was repeated except that the aliphatic-aromatic copolyester was not used, but the plasticizer content was changed to 20 parts by mass and the inorganic filler content was changed to 25 parts by mass. A compound raw material was prepared in the same manner as in Example 1. Then, this compound raw material was melt-extruded using the same single-screw extruder as in Example 1 at a set temperature of 180 ° C. The molten resin composition discharged from the die was formed into a film in the same manner as in Example 1. Next, the wound film was printed in the same manner as in Example 1, and then the same bag-making machine as in Example 1 was used to heat-seal only one side at a sealing temperature of 280 ° C. and a sealing time of 0.5 seconds, and thereafter. It cut automatically and the 45 L fertilizer bag was produced. Table 1 shows various physical property values of the fertilizer bag thus obtained.

Comparative Example 3 A film having a thickness of 90 μm and a film width of 500 was prepared in the same manner as in Example 1 except that no plasticizer was used.
A film of mm was obtained. Next, the wound film was printed in the same manner as in Example 1, and then the same bag-making machine as in Example 1 was used to heat-seal only one side at a sealing temperature of 275 ° C. and a sealing time of 0.25 seconds, and thereafter. It cut automatically and the 45 L fertilizer bag was produced. Table 1 shows various physical property values of the fertilizer bag thus obtained.

Comparative Example 4 A compound was prepared by using the same composition and mixing ratio as in Example 1 except that no inorganic filler was used. When pelletizing, blocking was vigorous, and when a film was formed using this pellet in the same manner as in Example 1, the tube was not stable due to insufficient melt tension of the tube, resulting in width unevenness. After the film-like film was nipped by a pinch roll, the film was blocked and could not be opened at all.

Comparative Example 5 A film was formed in the same manner as in Example 1, and subsequently, after printing on the film, the bag was formed at a sealing temperature of 200 ° C. and a sealing time of 1 second, and the same procedure as in Example 1 was performed. A fertilizer bag for 45 L was prepared. Table 1 shows various physical properties of the obtained fertilizer bag.

Comparative Example 6 A fertilizer bag for 45 L was prepared in the same manner as in Example 1 except that the film was formed in the same manner as in Example 1 and then the bag was made at a sealing temperature of 290 ° C. and a sealing time of 0.1 seconds. Was produced. Table 1 shows various physical properties of the obtained fertilizer bag.

[0039]

[Table 1]

The fertilizer bags obtained in Examples 1 and 2 were flexible, no bleed out of the plasticizer was observed, there was no blocking between films, and the mouth opening was good. Also, the strength of the seal is practically no problem, and there is no bag breakage.
No printing ink leaked. In Comparative Example 1, an aliphatic polyester was used in place of the aliphatic-aromatic copolyester, but the aliphatic polyester has a high crystallinity and therefore cannot sufficiently retain the plasticizer, so that the plasticizer bleeds out and the film It was blocked between and the openness was poor. Also, the outflow of printing ink was observed. Comparative example 2
Since no aliphatic-aromatic copolyester was used, it was necessary to increase the compounding amount of the plasticizer in order to impart flexibility to the film. Increasing the plasticizer content lowers the glass transition temperature of the film that makes up the fertilizer bag, but when it falls below room temperature, it accelerates the hydrolysis of polylactic acid, and the mechanical properties and seal strength of the film significantly decrease over time. However, it was a problem in practical use because it also caused the bag to break. Further, since the added amount of the plasticizer was increased, the outflow of the printing ink due to the bleed-out of the plasticizer was also remarkable. In Comparative Example 3, since the plasticizer was not used at all, the obtained film was inferior in flexibility, and even in the drop bag test, the bag was broken in one drop bag. In Comparative Example 5, since the sealing temperature was too low, heat sealing could not be sufficiently performed, and the bag was broken at one time in the drop bag test due to insufficient sealing strength. Comparative Example 6 had a fatal defect that the film was melted because the sealing temperature was too high, holes were often formed at the boundary between the sealing part and the film, and boundary lines were frequently broken, and the bottom of the fertilizer bag came off. It was

[0041]

According to the present invention, a film containing polylactic acid containing a biodegradable aliphatic-aromatic copolyester having a glass transition temperature of 0 ° C. or less, a plasticizer, and an inorganic filler as essential components is manufactured. The fertilizer bag obtained by heat-sealing at least one of the above films under the conditions of a sealing temperature of 260 to 280 ° C. and a sealing time of 0.1 to 1 second is hard and brittle at room temperature, which is a drawback of polylactic acid. In addition to improving properties, it is also excellent in plasticizer bleed-out and seal strength. In addition, this fertilizer bag is biodegradable and, in addition to degrading in the natural environment, it does not generate toxic gas when incinerated because it is obtained from polylactic acid, and it does not have a problem of waste treatment. It is extremely useful as a gentle and practical fertilizer bag.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) C08K 5/10 C08K 5/10 F term (reference) 3E064 BA54 BA60 BB01 BC18 BC20 EA04 EA30 HN05 3E086 AA23 AB02 AC07 AD01 BA02 BA15 BA33 BA35 BB51 BB58 BB62 BB66 BB85 BB90 CA40 4F071 AA43 AA43X AA76X AA86 AB01 AC10 AE04 AE17 AF13 AF59Y AH05 BA01 BB09 BC01 4J002 CF03X57FD0E0 DJ057F0700

Claims (8)

[Claims] 1. A fertilizer bag in which at least one of biodegradable films is heat-sealed, wherein the biodegradable film is polylactic acid (A), and the biodegradable aliphatic glass having a glass transition temperature of 0 ° C. or lower. A biodegradable fertilizer bag containing an aromatic copolyester (B), a plasticizer (C), and an inorganic filler (D) and having a heat-sealing strength of 15 N / 15 mm or more. 2. Polylactic acid (A) and a biodegradable aliphatic-aromatic copolyester (B) having a glass transition temperature of 0 ° C. or less.
Content ratio of 95/5 to 30/70 (mass%), 4 to 30 parts by mass of the plasticizer (C), and inorganic filling to 100 parts by mass of the components (A) and (B) in total. The biodegradable fertilizer bag according to claim 1, wherein the material (D) is contained in an amount of 5 to 40 parts by mass. 3. The heat of crystal fusion (ΔHm) of the biodegradable aliphatic-aromatic copolyester (B) having a glass transition temperature of 0 ° C. or lower is 25 J / g or less. Biodegradable fertilizer bag as described. 4. The biodegradation according to any one of claims 1 to 3, wherein the plasticizer (C) is at least one selected from ether ester plasticizers and oxyester plasticizers. Sex fertilizer bag. 5. The biodegradable fertilizer bag according to claim 4, wherein the plasticizer (C) is at least one selected from bismethyldiethylene glycol adipate, bisbutyldiethylene glycol adipate, and tributyl acetylcitrate. 6. The glass transition temperature of the biodegradable film is 2
It is 5-40 degreeC, The biodegradable fertilizer bag in any one of Claims 1-5 characterized by the above-mentioned. 7. When the bag is filled with 15 kg of bark compost and dropped horizontally and laterally from a height of 1.2 m, the bag will not be broken even if dropped five times or more. The biodegradable fertilizer bag according to any one of to 6. 8. The biodegradability according to claim 1, wherein at least one of the biodegradable films is heat-sealed under the conditions of a sealing temperature of 260 to 285 ° C. and a sealing time of 0.1 to 1 second. Fertilizer bag manufacturing method.