JP2002059499A - Biodegradable bubble sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a biodegradable bubble sheet having excellent buffering performance, decomposability, mildewproofness and water resistance, remarkably improved in molding processability and yield in the case of manufacturing and remarkably improved in its flexibility and softness without bleeding of a plasticizer at a high temperature. SOLUTION: The biodegradable bubble sheet comprises a lactate resin composition containing at least one type of a compound of 5 to 30 pts.wt. selected from the group consisting of a compound (A) represented by formula (1), (wherein at least one of R1, R2 and R3 is a 6-18C acyl group. A residue is a hydrogen atom or an acetyl group) and a compound (B) of a reaction product of a condensate of 1 to 10 molecules of a glycerin with a 6-18C carboxylic acid, to a lactate resin of 100 pts.wt.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a foam which is decomposable in a natural environment and produced from a lactic acid-based resin composition containing polylactic acid or a lactic acid-based resin containing at least 50% by weight of a lactic acid component as a main component. The present invention relates to a composite sheet obtained by laminating a sheet and kraft paper.

[0002]

2. Description of the Related Art A foam sheet in which a large number of air bubbles are formed by laminating an embossed sheet having a large number of embosses and a base sheet, and a composite sheet formed by laminating kraft paper or the like on one or both sides of the bubble sheet, Conventionally,
It is widely used as a buffer and a packaging material for transporting goods such as electric parts, glass, pottery, food, and arts. General-purpose resins such as polyethylene resin are generally used for the foam sheet and the composite sheet. However, some foam sheets made from such general-purpose resins are excellent in impact resistance, light weight, heat absorption resistance, and flexibility. Since it is hardly decomposed below, it remains semi-permanently even if it is buried. In addition, abandoned plastics cause problems such as degrading the landscape and destroying the living environment of marine life.

To solve such a problem, for example, Japanese Patent Laid-Open No.
JP-A-320654 and JP-A-7-16966 disclose that an extruder melt-mixes a plurality of resins composed of an ethylene / carbon monoxide copolymer resin, a high-density polyethylene resin, a polyamide resin, and an aliphatic polyester resin. A bubble sheet comprising a mixed resin composition is disclosed.

This sheet has the following features 1) to 3). 1) It has an effective function as a packaging material, a heat insulating material, a sound absorbing material, a civil engineering building material, and an agricultural material. 2) Excellent gas barrier properties. 3) It is easily decomposable. In other words, it has the function of biodegrading when buried in the soil after disposal, and photodecomposes when exposed to sunlight to reduce the volume. However, this bubble sheet contains a general-purpose polymer having substantially no decomposability (high-density polyethylene resin, polyamide resin, etc.), and the decomposability is not always sufficient.

On the other hand, as a biodegradable polymer of a thermoplastic resin, polylactic acid, a copolymer of lactic acid and another aliphatic hydroxycarboxylic acid, an aliphatic polyhydric alcohol and an aliphatic polycarboxylic acid are used. Polyester and the like have been developed. Some of these polymers are 100% biodegradable within months to one year in animals or, when placed in soil or seawater, begin to degrade within weeks in a humid environment, with about 1 Some disappear in a few years. These decomposition products have the property of becoming lactic acid, carbon dioxide, and water that are harmless to the human body. In particular, polylactic acid has recently been produced in large quantities and inexpensively by fermentation of L-lactic acid as a raw material,
Due to its high decomposition rate in compost and excellent characteristics such as mold resistance, odor resistance to food, and coloration resistance, it is expected to expand its field of use.

Against this background, the present inventors have disclosed in Japanese Patent Application Laid-Open No. 7-76628 a cell sheet made of a thermoplastic resin composition containing polylactic acid as a main component. This bubble sheet is excellent in scratch resistance, waterproofness, mold resistance, etc., and can be decomposed under natural environment,
It is suitable as a buffer material that also eliminates the problem of environmental pollution. Also,
A composite sheet made of a foam sheet and kraft paper is suitable as a material for transportation such as cardboard, envelopes and the like. However, polylactic acid has high rigidity, and it is hard to say that it is an appropriate resin for applications requiring flexibility such as films and packaging materials.Depending on the composition ratio and molding processing conditions of the resin composition used,
Requires advanced technology for forming. Further, the flexibility and flexibility of the obtained product is not always sufficient, and cracks may occur at the time of winding after the production of the bubble sheet, and bubbles may be removed or burst, which is not very practical. Therefore, in order to obtain a practical foam sheet containing polylactic acid as a main component, it is necessary to impart flexibility by some method.

On the other hand, generally, as a technique for imparting flexibility to polylactic acid, a method of adding a plasticizer, a method of forming a copolymer, a method of adding a soft polymer, and the like are known. For example, JP-A-11-302424 discloses a polylactic acid comprising a polylactic acid, a polymer component containing a biodegradable aliphatic polyester having a melting point of 80 to 250 ° C., and a biodegradable plasticizer. A foam sheet composed of a resin composition is disclosed. However, in the method described therein in which a plasticizer such as tributyl acetylcitrate or glycerin triacetate is added, in order to impart sufficient flexibility, the melting point is 80 to 25.
Aliphatic polyester having a biodegradability of 0 ° C. is required as an essential component, and even if flexibility is obtained, the plasticizer bleeds at high temperatures and loses heat resistance,
In addition, since there is a problem that bleeding of a plasticizer causes blocking of a sheet in a manufacturing process, there are practically several problems for practical use. In addition, glycerin triacetate has a high solubility in water, and glycerin triacetate elutes from the molded product in water, and loses flexibility. As described above, it is a fact that imparting flexibility and heat resistance without impairing the characteristics of polylactic acid cannot be achieved by conventional techniques.

[0008]

The problems to be solved by the present invention are excellent in buffering performance, biodegradability, fungicide resistance and water resistance, and in the production thereof, the moldability and the yield are remarkable. It is an object of the present invention to provide a foam sheet that is improved and has significantly improved flexibility and flexibility. More specifically, by simply adding a specific plasticizer, excellent flexibility can be obtained, and further, since the plasticizer has excellent bleed-out resistance at high temperatures, it has excellent blocking resistance and water resistance. An object of the present invention is to provide a foam sheet made of a lactic acid-based resin composition having properties and having both heat resistance and flexibility. Furthermore, it has flexibility (elastic modulus of 100 to 1000 MPa) and heat resistance (blocking temperature of 60 ° C. or more), such as polypropylene, polyethylene and polyvinyl chloride used for garbage bags and packaging materials. An object of the present invention is to develop a foam sheet made of a biodegradable lactic acid-based resin composition.

[0009]

Means for Solving the Problems The present inventors disclosed in Japanese Patent Laid-Open No.
When a thermoplastic polymer composition containing polylactic acid used in the inventions disclosed in JP-766628A and JP-A-11-302424 is molded into a foam sheet, flexibility and flexibility are improved. In order to improve water resistance, screening of a plasticizer that does not easily pollute the environment has been studied. As a result, it has been found that by adding a lactic acid-based resin and a specific plasticizer having good compatibility with the lactic acid-based resin, a foam sheet made of a lactic acid-based resin composition that can solve the above problems can be obtained. Was completed.

That is, the present invention relates to a compound of the general formula (1)

[0011]

Embedded image (Wherein at least one of R ₁ , R ₂ and R ₃ has 6 carbon atoms)
(A) which is an acyl group having from 18 to 18 carbon atoms, and the remainder is a hydrogen atom or an acetyl group); and a reaction product of a condensate of 1 to 10 glycerin molecules and a carboxylic acid having 6 to 18 carbon atoms. A cell sheet comprising a lactic acid-based resin composition containing 5 to 30 parts by weight of at least one compound selected from the compound (B).

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
The foam sheet of the present invention is flexible, water-resistant, and excellent in bleed-out resistance of a plasticizer at a high temperature, and a lactic acid-based resin composition obtained by mixing a lactic acid-based resin with a specific glycerin ester as a plasticizer. Consists of

In the present invention, a lactic acid-based resin means that the lactic acid component in all the monomer components constituting the resin is at least 5%.
0% by weight or more of a homopolymer and a copolymer, for example, polylactic acid, a copolymer of lactic acid and an aliphatic hydroxycarboxylic acid (for example, a copolymer of lactic acid and glycolic acid, a copolymer of lactic acid and caproic acid, and a copolymer of polylactic acid and polycaproic acid) A copolymer of lactic acid and an aliphatic polyhydric alcohol and an aliphatic polycarboxylic acid (for example, a copolymer of lactic acid and butanediol with succinic acid and adipic acid, a copolymer of lactic acid with ethylene glycol and a copolymer of butanediol and succinic acid), Block copolymers of polylactic acid and polybutylene succinate), and mixtures thereof. Further, a mixture of polylactic acid and an aliphatic polyester (for example, polycaproic acid, polybutylene succinate, polyethylene succinate, a copolymer of β-hydroxybutyric acid and β-hydroxyvaleric acid, etc.) is included. In the case of a mixture, a compatibilizer may be contained. When the lactic acid-based resin is a copolymer, the mode of arrangement of the copolymer may be random copolymer, alternating copolymer,
Any type such as a block copolymer and a graft copolymer may be used. Furthermore, these may be at least partially cross-linked with a cross-linking agent such as xylylene diisocyanate, polyvalent isocyanate such as 2,4-tolylene diisocyanate or polysaccharide such as cellulose, acetyl cellulose or ethyl cellulose. At least a part thereof may have any structure such as a linear shape, a ring shape, a branched shape, a star shape, and a three-dimensional network structure, and there is no limitation.

In the lactic acid resin of the present invention, polylactic acid,
In particular, poly-L-lactic acid, a block copolymer of polylactic acid and poly-6-hydroxycaproic acid, particularly a block copolymer of poly-L-lactic acid and poly-6-hydroxycaproic acid, and a block of polylactic acid and polybutylene succinate Copolymers, especially block copolymers of poly-L-lactic acid and polybutylene succinate, block copolymers of polylactic acid, β-hydroxybutyric acid and β-hydroxyvaleric acid,
Particularly, a block copolymer of poly-L-lactic acid, β-hydroxybutyric acid and β-hydroxyvaleric acid is preferred. Of these, polylactic acid is most preferred.

In the present invention, specific examples of the aliphatic hydroxycarboxylic acid constituting the lactic acid-based resin include, for example, glycolic acid, lactic acid, 3-hydroxy drank acid, 4-hydroxy drank acid, 3-hydroxyvaleric acid, 4-hydroxyvaleric acid, Hydroxyvaleric acid, 5-hydroxyvaleric lactic acid, 6-hydroxycaproic acid and the like can be mentioned. These may be one kind or a mixture of two or more kinds. When the aliphatic hydroxycarboxylic acid has an asymmetric carbon, L-form, D-form, and a mixture thereof,
That is, it may be racemic.

Specific examples of the aliphatic polycarboxylic acid constituting the lactic acid resin in the present invention include, for example, oxalic acid, succinic acid, malonic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, Examples thereof include aliphatic dicarboxylic acids such as sebacic acid, undecanoic acid and dodecane diacid, and anhydrides thereof. These may be one kind or a mixture of two or more kinds.

Specific examples of the aliphatic polyhydric alcohol constituting the lactic acid resin in the present invention include, for example, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, 1,3-butanediol, 4-butanediol, 3-methyl-1,5-pentanediol, 1,6-
Hexanediol, 1,9-nonanediol, neopentyl glycol, tetramethylene glycol, 1,4-
Cyclohexanedimethanol and the like. These may be one kind or a mixture of two or more kinds.

Specific examples of the polysaccharide constituting the lactic acid resin in the present invention include, for example, cellulose, cellulose nitrate, cellulose acetate, methyl cellulose, ethyl cellulose, celluloid, viscose rayon, regenerated cellulose, cellophane, cupra, copper ammonia rayon , Cuprophan, bemberg, hemicellulose, starch, amylopectin, dextrin, dextran, glycogen, pectin, chitin, chitosan, gum arabic, guar gum, locust bean gum, acacia gum, and the like, and derivatives thereof. Ethyl cellulose is preferably used. These may be one kind or a mixture of two or more kinds.

The molecular weight of the lactic acid-based resin used in the present invention is not particularly limited as long as it exhibits substantially sufficient mechanical properties, but is generally 1 to 300 as a weight average molecular weight. 10,000 is preferable, 3 to 2,000,000 is more preferable, 5 to 1,000,000 is more preferable, and 7 to 5
More preferably, it is 100,000, most preferably 90,000 to 300,000. In general, when the weight average molecular weight is less than 10,000, mechanical properties are not sufficient. On the contrary, when the molecular weight is more than 3,000,000, handling becomes difficult due to molding processing, and uneconomical in production cost. It may be.

The weight average molecular weight and the molecular weight distribution of the lactic acid resin used in the present invention are determined by the following method.
Solvent type, catalyst type and amount, reaction temperature, reaction time,
The desired conditions can be controlled by appropriately selecting the reaction conditions such as the method of embedding the solvent distilled off by azeotropic distillation and the degree of solvent drying in the reaction system.

The method for producing the lactic acid-based resin of the present invention is not particularly limited. For example, as an example of a method for producing a polylactic acid and a lactic acid-based resin having lactic acid as a structural unit, see JP-A-6-6-6.
A method as described in Production Example 1 described below with reference to the method disclosed in Japanese Patent No. 5360 is cited. That is,
This is a direct dehydration condensation method in which lactic acid and / or lactic acid and an aliphatic hydroxycarboxylic acid other than lactic acid, or an aliphatic diol and an aliphatic dicarboxylic acid are directly dehydrated and condensed in the presence of an organic solvent and a catalyst.

Another example of a method for producing a lactic acid-based resin having lactic acid as a structural unit is described in, for example, JP-A-7-17326.
No. 6, reference is made to the method disclosed therein. That is, this is a method in which a homopolymer of at least two kinds of lactic acid-based resins is copolymerized and transesterified in the presence of a polymerization catalyst.

As another example of the method for producing polylactic acid, for example, a method referring to the method disclosed in US Pat. No. 2,703,316 can be mentioned. That is, once lactic acid and / or hydroxycarboxylic acid other than lactic acid,
This is an indirect polymerization method in which ring-opening polymerization is performed after dehydration to form a cyclic dimer.

In the present invention, for the purpose of imparting flexibility to the biodegradable foam sheet, a plasticizer represented by the following general formula (1):

[0025]

Embedded image (Wherein at least one of R ₁ , R ₂ and R ₃ has 6 carbon atoms)
(A) and glycerol 1 represented by the formula:
At least one compound selected from the compounds (B), which are reaction products of a condensate of 10 to 10 molecules and a carboxylic acid having 6 to 18 carbon atoms, is used.

The added amount of these plasticizers affects the crystallinity, flexibility, heat resistance and the like of the obtained sheet, film and the like. If the addition amount is too large, the crystallinity and heat resistance decrease. If the amount is too small, sufficient flexibility cannot be obtained. From such a viewpoint, the amount of the plasticizer to be added may be
The amount is preferably 5 to 30 parts by weight with respect to 0 parts by weight.
More preferably, it is 10 to 25 parts by weight.

The compound (A) used in the present invention is a glycerin ester represented by the general formula (1). Normal,
The acetyl group of the compound is 2 mol or less on average per 1 mol of glycerin. An acyl group having 6 to 18 carbon atoms (hereinafter, referred to as an acyl group)
C6-18 acyl group) is 0.9 mol or more on average to 1 mol of glycerin. Acetyl group and C6-1
The total amount of 8-acyl groups is an average of 2. to 1 mol of glycerin.
It is in the range of 7 to 3.0 mol. Preferably, the total amount of the acetyl group and the C6-18 acyl group is in the range of 2.9 to 3.0 mol on average per 1 mol of glycerin. In addition, from the viewpoint of the plasticizing effect of the resin and the non-bleeding property, the glycerin ester preferably has 8 to 18 carbon atoms of the acyl group among the C6 to 18 acyl groups. In the general formula (1), an ester in which at least one of R ₁ , R ₂ , and R ₃ is an acyl group having 8 to 18 carbon atoms and the remainder is an acetyl group is more preferable. Particularly preferred compounds (A) include glycerin diacet monocaprylate, glycerin diacet monolaurate and glycerin diacet monooleate. Compound (A) may be used alone or as a mixture.

In the present invention, the compound (B) used as a plasticizer is usually a carboxylic acid having 6 to 18 carbon atoms per 1 mol of a condensate of 1 to 10 molecules of glycerin.
~ 1.2 mol. From the viewpoint of the plasticizing effect of the resin and the non-bleeding property, a condensate of 2 to 10 molecules of glycerin and an ester compound with a carboxylic acid having 8 to 18 carbon atoms are preferable. More preferably, it is an ester with a condensate of 4 to 10 molecules of glycerin. Particularly preferred specific compounds include tetraglycerin caprylate, decaglycerin laurate, and decaglycerin oleate. Compound (B) may be used alone or as a mixture.

Considering the suppression of bleeding of the plasticizer, it is preferable to use the compound (A) and the compound (B) together.
In that case, the mixing weight ratio of (A) to (B) is from 1: 1 to 4:
A range of 1 is preferred. A more preferred mixing weight ratio of (A) to (B) is in the range of 2: 1 to 3: 1.

The lactic acid-based resin composition according to the present invention may contain various additives (antioxidants, ultraviolet absorbers, heat stabilizers, etc.) depending on the purpose (for example, improvement in tensile strength, heat resistance, weather resistance, etc.).
Flame retardants, internal release agents, inorganic additives, antistatic agents, surface wetting improvers, incineration aids, lubricants such as pigments) and the like can be added. For example, in inflation molding and T-die extrusion molding, it is recommended to add an inorganic additive and a lubricant (aliphatic carboxylic acid amide) in order to improve the anti-blocking property and the sliding property of the film, sheet and bubble sheet.

The aliphatic carboxylic acid amide used in the present invention includes "10889 chemical products (1989,
389 of Chemical Daily, Nihonbashi-hama-cho, Chuo-ku, Tokyo)
"Fatty acid amide" described in the right column of the page to the left column of the page 391 are included. All the descriptions are incorporated as a part of the disclosure of the specification of the present application by explicitly citing the cited documents and the cited range, and by referring to the explicitly cited ranges, the matters or disclosures described in the specification of the present application are all Items that can be directly and unambiguously derived by the trader are disclosed.

Specific examples of the aliphatic carboxylic acid amide include, for example, oleic acid amide, stearic acid amide,
Erucamide, behenic amide, N-oleyl palmitamide, N-stearyl erucamide, N, N '
-Ethylene bis (stearamide), N, N'-methylene bis (stearamide), methylol stearamide, ethylene bisoleic acid amide, ethylene bisbehenic acid amide, ethylene bis stearic acid amide,
Ethylene bislaurate amide, hexamethylene bisoleate amide, hexamethylene bisstearate amide, butylene bisstearate amide, N,
N'-dioleyl sebacic amide, N, N'-dioleyl adipamide, N, N'-distearyl adipamide, N, N'-distearyl sebacamide, m-xylylene bis stearamide , N, N '
-Distearyl isophthalamide, N, N'-distearyl terephthalamide, N-oleyl oleamide, N-stearyl oleamide, N-stearyl erucamide, N-oleyl stearamide,
N-stearyl stearamide, N-butyl-N '
Stearyl urea, N-propyl-N ′ stearyl urea,
N-allyl-N 'stearyl urea, N-phenyl-N'
Examples include stearyl urea, N-stearyl-N 'stearyl urea, dimethitol oil amide, dimethyl laurate amide, dimethyl stearate amide and the like.
In particular, oleic acid amide, stearic acid amide, erucic acid amide, behenic acid amide, N-oleyl palmitamide, and N-stearyl erucic acid amide are preferably used. These may be one kind or a mixture of two or more kinds.

The amount of the aliphatic carboxylic acid amide to be added is 0.05 to 10.0 parts by weight, preferably 0.1 to 7.0 parts by weight, more preferably 0 to 100 parts by weight based on 100 parts by weight of the lactic acid resin. 0.3-5.0 parts by weight, most preferably 0.5-5.0 parts by weight
3.0 parts by weight is preferred. The amount of addition, as in the case of the inorganic additive, the desired film, moldability of the sheet and the like,
The optimum amount of the obtained film, sheet, and bubble sheet at which the blocking resistance and the slipperiness are good is appropriately selected.

In the present invention, an inorganic filler having a controlled particle size can be added for the purpose of improving the blocking properties of the film, sheet and bubble sheet. Specific examples of the inorganic filler include, for example, talc, magnesium silicate, calcium carbonate, aluminum powder, silica, kaolinite and the like. The particle size of the agent is 50 μm
Or less, preferably 30 μm or less, more preferably 20 μm
m, more preferably 15 μm or less, and most preferably 10 μm or less. If the particle size is larger than 50 μm, defects may occur at the interface between the film and the additive, and bubbles in the resin sheet may be easily released. The amount of the inorganic filler to be added is 0.1 to 100 parts by weight of the polylactic acid-based resin composition.
The amount is from 1 to 10.0 parts by weight, preferably from 0.5 to 7.0 parts by weight, more preferably from 1.0 to 5.0 parts by weight, and an optimum amount for obtaining the desired effect is appropriately selected.

The lactic acid-based resin composition according to the present invention is obtained by adding and mixing the lactic acid-based resin with the above-mentioned plasticizer and, if necessary, additives and the like according to the desired molded product.
As a method, after uniformly mixing the lactic acid-based resin and the plasticizer, and optionally other additives using a high-speed stirrer or a low-speed stirrer, a single-screw or multi-screw extruder having a sufficient kneading ability is used. And a method of melt-kneading. The shape of the resin composition according to the present invention is preferably a pellet, a rod, a powder, or the like.

The bubble sheet of the present invention is a flexible sheet composed of the above-described resin composition and having a large number of protrusions or protrusions on one surface. The shape, size, number of projections per unit area, and the like are not particularly limited, and are appropriately selected according to the purpose. Usually, the height of the protrusions or protrusions is 1 to 18 mm, generally 3.3 to 1
About 3 mm, width or diameter is 2 to 45 mm, generally 3 to 37 mm, and the area occupied by the projections or protrusions is 20 to 90%, generally 60 to 85% per sheet surface Kong. The shape of the convex protrusions of the bubble sheet is not particularly limited, but is usually a semicircular shape, a columnar shape, an elliptical shape, or the like. Within the above-mentioned range, functions as a packaging material, a heat insulating material, a sound absorbing material, a material for civil engineering and construction, and a material for agricultural use can be sufficiently exhibited.

The base film thickness of the bubble sheet is not particularly limited, and is appropriately selected according to the purpose. The thickness of the projections or protrusions is not particularly limited, and is appropriately selected depending on the purpose. Usually, the thickness of the base sheet of the bubble sheet is 50 to 300 μm.
m, and the thickness of the projections or protrusions is 25 to 150 μm.

A typical embodiment of the bubble sheet of the present invention is a composite sheet having hollow projections or protrusions formed by laminating a base sheet and an embossed sheet provided with a large number of uneven portions by embossing.

As a method for producing the bubble sheet of the present invention,
The lactic acid-based resin composition described above, in some cases, an inorganic filler, a resin composition obtained by mixing a lubricant, etc., are mixed using a general mixer or extruder, pelletized, and then formed into a normal molding machine. In addition, the desired resin sheet can be obtained by the molding method and the molding machine and the molding method are not limited at all. For example, as a specific method of forming a resin sheet, a resin composition is formed using a normal inflation molding machine or a T-die extruder, and then a flat sheet is formed and then a bubble sheet is formed. A method of forming a foam sheet (Japanese Patent Publication No. 54-36617) can be mentioned.

In producing the foam sheet of the present invention, the base sheet used as a raw material is the same as the conventional polyethylene resin sheet at a temperature of about 100 to 120 ° C.
Embossing is possible in the temperature range of ~ 100 ° C, and the welding temperature of the molded embossed sheet and base sheet is 60-170 ° C, compared to 120-150 ° C for polyethylene resin. Excellent workability.

Also, when a composite sheet is manufactured by laminating kraft paper or the like on one or both sides of the bubble sheet,
In the case of polyethylene resin, extrude polyethylene from the T-die of the extruder at a temperature of 300 ° C or more and bond it to kraft paper, or lower the temperature of the embossing roll to 280 ° C or less and preheat the kraft paper at a temperature of about 60 ° C in advance. In general, the base sheet and the kraft paper of the raw materials are directly heated at a temperature of 180 to 250 ° C.
Welding is possible at a pressure of 0.1 to 0.5 kg / cm2. As for the laminating conditions, the composite sheet can be easily bonded at a relatively low temperature and in a wide temperature range, so that a composite sheet having good workability and stable can be produced.

An embodiment of the method for producing a bubble sheet according to the present invention will be described below. 1) Production of base sheet The lactic acid-based resin composition is formed into a base sheet having a thickness of 15 to 300 µm. 2) Production of embossed sheet Just like the production of the base sheet, the thickness is 15 to 300 μm.
m sheets are manufactured. The sheet is held in a thermostat or heated and softened to a temperature of 50 to 100 ° C. by a hot roll. Next, the heat-softened sheet is wrapped around a temperature-controlled embossing roll, and a pressure reduction degree of 1
0 to 400 mmHg, preferably 20 to 100 mmHg
Then, an embossed sheet having a concave portion on the entire peripheral surface is formed by vacuum forming. Here, as the embossing roll, for example, a roll having a depth of 5 mm, a diameter of 9.5 mm, a number of holes of 9,720 / m ² , and each of which has a vacuum hole capable of being vacuum formed is used. used. 3) Manufacture of bubble sheet The embossed sheet is separately heated to 60 to 170 by a hot roll.
A base sheet having a thickness of 15 to 300 μm heated and softened to a temperature of ° C. is welded and cooled to produce a foam sheet.
In this case, it is general that the base sheet is continuously heat-welded to the flat portion of the embossed sheet in the process of “2) Production of embossed sheet”.

[0043]

The present invention will be described more specifically with reference to the following examples. The weight average molecular weight (Mw) in the examples was determined by gel permeation chromatography (GPC) (column temperature; 40 ° C., chloroform solvent) in comparison with a polystyrene standard sample. In Examples and Comparative Examples, the foam sheets were subjected to the following tests 1) to 5) and evaluated. 1) Degradability test A test piece was buried in soil at a temperature of 35 ° C and a water content of 30%.
The appearance and weight loss rate after a month were determined. 2) Mold resistance test A test piece was placed on an inorganic agar medium according to JIS Z-2911, and a spore suspension of five test bacteria was spray-inoculated.
After culturing at 30 ° C., the growth of mold with time was observed.

3) Compressive strength A foam sheet of 120 × 120 mm is compressed to half of the initial thickness and held in this state for 1 minute in accordance with the Defense Agency standard (draft) test method for foamed plastic film cushioning material for packaging. Then, the burst of the bubbles was observed. 4) Flexibility (Flexibility) The elastic modulus of the blown films obtained in Examples and Comparative Examples was determined according to JIS K6732.

5) Heat resistance The blown films obtained in Examples and Comparative Examples were subjected to 80 ° C./500 g load according to JIS Z0219.
The state of the film when it was kept under the conditions described above was observed. * Bleed of plasticizer ○ ・ ・ ・ No bleed × ・ ・ ・ Bleed * Film blocking ○ ・ ・ ・ No blocking △ ・ ・ ・ Slightly blocking × ・ ・ ・ Blocking 6) Water resistant foam sheet 23 Immersed in water for 5 days, then 2
It was left overnight at 3 ° C. and 50% RH. The hardness of the obtained molded article was observed. ：: No change △: Slightly hard ×: Clearly hard

Production Example 1 104.3 g of 90% monolactic acid and diphenyl ether 2 were placed in a 500 ml four-neck flask equipped with a stirrer and a thermometer.
25.0 g and 2.0 g of metallic tin were added, and 130 ° C./140
The mixture was heated and stirred at 7 mmHg for 7 hours while distilling the generated water out of the system. A Dean Stark Trap was attached thereto, and azeotropic dehydration was performed at 140 ° C./130 mmHg for 8 hours. Then, a drying tube filled with 40 g of molecular sieves 3A was attached, and the distilled solvent was returned to the reactor through the drying tube. At 130 ° C / 17 mmHg
Heated to reflux for an hour. After cooling, the reaction mass was dissolved in 600 ml of chloroform, added to 4 liters of acetone, reprecipitated, and the precipitated solid was filtered off. Next, 500 ml of an isopropyl alcohol (hereinafter, referred to as IPA) solution in which 5 g of hydrochloric acid is dissolved is added to the filter cake, and the mixture is stirred for 30 minutes. Further, 500 ml of IPA is added.
The wet cake obtained at 60 ° C / 100mmH
g for 15 hours. The obtained solid was polylactic acid in the form of a white powder, the yield was 69.1 g, the yield was 92.2%, and the weight average molecular weight (Mw) was 29.5 million.

Example 1 100 parts by weight of the polylactic acid obtained in Production Example 1, 13 parts by weight of glycerin diacetomonocaprylate as a plasticizer,
3.0 parts by weight of silica as an inorganic filler and 1.0 parts by weight of erucamide as a lubricant are mixed well with a Henschel mixer, and the resin temperature is 170 to 220 ° C. using a twin screw extruder.
And extruded into pellets. This pellet is heated at 70 ° C / 1
After drying for 5 hours, the extruder of 40mmΦ
And inflation molding was performed under the conditions of an extrusion temperature of 180 to 200 ° C. and an expansion ratio of 2, to obtain a sheet having a thickness of 40 μm. The sheet was heated and softened by a roll controlled at a temperature of 80 ° C., and further embossed roll (hole depth 5 mm, hole diameter 9.5 m) controlled at a reduced pressure of 50 mmHg.
m, number of holes 9720 / m ² ). At this time, 1
A base sheet having a thickness of 40 μm passed through a smooth roll heated to 20 ° C. is wound around the embossed sheet and welded to a flat portion of the embossed sheet, and a 5 mm-thick bubble sheet 1 of FIG. (About 70% per area).

1) Degradability test The shape collapsed and became loose. 2) Mold resistance test No mold growth was observed even after 3 months. 3) Compressive strength There was no burst of bubbles in the bubble sheet. 4) Flexibility It was superior to the foam sheet manufactured in Comparative Example 1 in flexibility and flexibility (the elastic modulus of the sheet was 150 MPa). The winding of the bubble sheet was good without bursting the bubbles. 5) Heat resistance * Bleeding of plasticizer ... * * Blocking of film ... * 6) Water resistance ... *

Example 2 Instead of 100 parts by weight of polylactic acid, 70 parts by weight of polylactic acid, polybutylene succinate (Bionole # 3001)
A lactic acid-based resin pellet was obtained in the same manner as in Example 1 except that 30 parts by weight (manufactured by Showa Polymer Co., Ltd.) was used. After the pellets were dried at 70 ° C./15 hr, a die having a diameter of 75 mm was connected to an extruder having a diameter of 40 mm.
Inflation molding was performed at 200 ° C. and a swelling ratio of 2 to obtain a sheet having a thickness of 40 μm. The temperature of this sheet is 8
Heat and soften with a roll controlled to 0 ° C, and further reduce the pressure to 5 ° C.
Embossing roll controlled to 0 mmHg (hole depth 5 m
m, hole diameter 9.5 mm, number of holes 9720 / m ² ). At this time, a base sheet having a thickness of 40 μm passed through a smooth roll heated to 120 ° C. was wound around the embossed sheet, and was welded to a flat portion of the embossed sheet. (The number is about 70% per unit area).

1) Degradability test The shape collapsed and became loose. 2) Mold resistance test No mold growth was observed even after 3 months. 3) Compressive strength There was no burst of bubbles in the bubble sheet. 4) Flexibility It was superior to the foam sheet manufactured in Comparative Example 1 in flexibility and flexibility (the elastic modulus of the sheet was 150 MPa). The winding of the bubble sheet was good without bursting the bubbles. 5) Heat resistance * Bleeding of plasticizer ... * * Blocking of film ... * 6) Water resistance ... *

Comparative Example 1 100 parts by weight of the polylactic acid obtained in Production Example 1, 20 parts by weight of tributyl acetylcitrate as a plasticizer, 3 parts by weight of silica as an inorganic filler, and 1 part by weight of erucamide as a lubricant were used. A bubble sheet was prepared in the same manner as in Example 1. 1) Degradability test The shape was disintegrated and it was broken apart. 2) Mold resistance test No mold growth was observed even after 3 months. 3) Compressive strength There was no burst of bubbles in the bubble sheet. 4) Flexibility It was inferior in flexibility and flexibility (the elastic modulus of the sheet was 250 MPa) to the bubble sheet manufactured in Example 1. Winding of the bubble sheet was a bit bad. 5) Heat resistance * Bleeding of plasticizer ... x * Blocking of film x 6) Water resistance x

Comparative Example 2 100 parts by weight of the polylactic acid obtained in Production Example 1, 20 parts by weight of glycerin triacetate (triacetin) as a plasticizer, 5.0 parts by weight of silica as an inorganic filler, 1.0 part by weight of erucamide To produce a bubble sheet in the same manner as in Example 1. 1) Degradability test The shape was disintegrated and it was broken apart. 2) Mold resistance test No mold growth was observed even after 3 months. 3) Compressive strength There was no burst of bubbles in the bubble sheet. 4) Flexibility Although the flexibility and flexibility (the elastic modulus of the sheet was 150 MPa) were equal to those of the foam sheet manufactured in Example 1, the plasticizer slightly bleed on the foam sheet. And winding was a bit bad. 5) Heat resistance * Bleeding of plasticizer ... x * Blocking of film x 6) Water resistance x

Comparative Example 3 100 parts by weight of the polylactic acid obtained in Production Example 1, 20 parts by weight of glycerin diacetomonopropionate as a plasticizer,
Using 5.0 parts by weight of silica and 1.0 part by weight of erucamide as an inorganic filler, a foam sheet was prepared in the same manner as in Example 1. 1) Degradability test The shape was disintegrated and it was broken apart. 2) Mold resistance test No mold growth was observed even after 3 months. 3) Compressive strength There was no burst of bubbles in the bubble sheet. 4) Flexibility Same as the foam sheet manufactured in Example 1 in flexibility and flexibility (the elastic modulus of the sheet is 200 MPa), but the plasticizer slightly bleeds on the foam sheet. The winding was a bit bad. 5) Heat resistance * Bleeding of plasticizer ... x * Blocking of film ... x 6) Water resistance ...

Comparative Example 4 The procedure of Example 1 was repeated except that dioctyl phthalate was used as the plasticizer. However, the bleeding of the plasticizer was so severe that a bubble sheet could not be obtained.

Comparative Example 5 The procedure of Example 1 was repeated except that ethyl stearate was used as the plasticizer. However, the bleeding of the plasticizer was so severe that a foam sheet could not be obtained.

Comparative Example 6 The procedure of Example 1 was repeated except that epoxidized soybean oil was used as the plasticizer. However, the bleeding of the plasticizer was so severe that a foam sheet could not be obtained.

Comparative Example 7 The procedure of Example 1 was repeated except that tributyl phosphate was used as the plasticizer. However, the bleeding of the plasticizer was so severe that a foam sheet could not be obtained.

[0058]

According to the present invention, excellent cushioning performance, decomposability, fungicide resistance and water resistance, and in the production thereof, the moldability and the yield are remarkably improved. A bubble sheet having no bleed and significantly improved flexibility and flexibility can be provided. In addition, the foam sheet according to the present invention is a composite sheet composed of the foam sheet and kraft paper, which is suitable as a material for transportation such as a cardboard, an envelope and the like.

[Brief description of the drawings]

FIG. 1 is a perspective view of a bubble sheet as an example of the present invention.

[Explanation of symbols]

 1 ... bubble sheet 1a ... protrusion or protrusion (bubble)

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08L 67/04 ZBP C08L 67/04 ZBP (72) Inventor Yasuhiro Kitahara 1190 Kasama-cho, Sakae-ku, Yokohama, Kanagawa Mitsui Inside Chemical Company (72) Inventor Akinori Takehara 1190 Kasama-cho, Sakae-ku, Yokohama-shi, Kanagawa Prefecture Inside Mitsui Chemical Co., Ltd. (72) Inventor Takayuki Kuroki 2-1-1 Tango-dori, Minami-ku, Nagoya-shi, Aichi Mitsui Chemicals F-term (Reference) 2B024 DB01 2B029 EB04 EB09 EB21 EC06 EC20 4F100 AA20H AH02A AH02C AH02H AH03H AK01A AK01C AK41A AK41C AL05A AL05C AT00B BA02 BA03 BA06 BA07 BA10A BA10C DD01A01E01 E01C01 DJ01D01C01

Claims (10)

[Claims] [Claim 1] A lactic acid-based resin is used in an amount of 100 parts by weight to the general formula (1). (Wherein at least one of R ₁ , R ₂ and R ₃ has 6 carbon atoms)
(A) and glycerol 1 represented by the formula:
A lactic acid-based resin composition containing 5 to 30 parts by weight of at least one compound selected from compound (B) which is a reaction product of a condensate of 10 to 10 molecules and a carboxylic acid having 6 to 18 carbon atoms. Biodegradable foam sheet. 2. In the general formula (1), R ₁ , R ₂ and R ₃
At least one is an acyl group having 8 to 18 carbon atoms,
The foam sheet according to claim 1, wherein the remainder is an acetyl group. 3. The foam sheet according to claim 2, wherein the compound (A) is at least one compound selected from glycerin diacet monocaprylate, glycerin diacet monolaurate and glycerin diacet monooleate. 4. The bubble sheet according to claim 1, wherein the compound (B) is an ester obtained by reacting 0.8 to 1.2 mol of a carboxylic acid with 1 mol of a glycerin condensate. 5. The foam sheet according to claim 1, wherein the carboxylic acid forming the compound (B) has 8 to 18 carbon atoms. 6. The foam sheet according to claim 1, wherein the glycerin condensate forming the compound (B) has 2 to 10 glycerin molecules. 7. The foam sheet according to claim 6, wherein the glycerin condensate forming the compound (B) has 4 to 10 glycerin molecules. 8. The foam sheet according to claim 7, wherein the compound (B) is at least one compound selected from tetraglycerin caprylate, decaglycerin laurate and decaglycerin oleate. 9. The foam sheet according to claim 1, comprising both compound (A) and compound (B), wherein the weight ratio of (A) to (B) is from 1: 1 to 4: 1. 10. The composite sheet according to claim 1, wherein the bubble sheet is a composite sheet formed by laminating an embossed sheet provided with a large number of uneven portions by embossing on at least one surface of a flat base sheet. The air bubble sheet according to 1.