JPH1016165A - Biodegradable composite material and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a composite material, which has functions excellent in water resistance, strength or the like and develops a small heating value of combustion at burningly incineration and has a property being degraded by the microbes in the earth, by a method wherein a thin flat plate made of aliphatic polyester resin is thermally fused onto at least one side of a corrugated panel made of aliphatic polyester resin. SOLUTION: This biodegradable composite material 17 is produced by fusing a thin flat plate 5 made of aliphatic polyester resin onto at least one side of a corrugated panel made of aliphatic polyester resin. The corrugated panel is produced by melting aliphatic polyester resin in an extruder and extruding it into a sheet through a die and immediately pinching it between corrugated rolls 3 and 4. Since the temperature of the resin sheet lowers below its melting temperature at its pinching, the apex parts of the corrugated panel under the state being held on the corrugated roll 4 are heated and melted with a heating device 7. The thin plate 5 of aliphatic polyester resin sheet or film just after being extruded from an extruder is piled up onto and pressed against the apex parts of this melted corrugated panel with a pressure roll 6 so as to be thermally fused together.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a biodegradable composite material and a method for producing the same. Specifically, a biodegradable composite material and a method for producing the same, in which a flat thin plate made of the same aliphatic polyester resin is directly heat-sealed to an corrugated sheet made of an aliphatic polyester resin sheet without using an adhesive or the like. To provide. The biodegradable composite material according to the present invention can be applied to various uses such as drainage material for civil engineering work, packaging material for fresh food, hygiene / medical material, agricultural use, and other various cushioning materials for packaging. In addition, since it has biodegradability, disposal problems can be reduced.

[0002]

2. Description of the Related Art Conventionally, cardboard made of synthetic resin has been widely used, for example, for packaging of processed marine products, because of its excellent water resistance and strength. However, these synthetic resin corrugated boards have the following problems: (1) When they are incinerated after use, they generate a large amount of heat and damage the incinerator; (2) When they are landfilled after use, they are permanently soiled. There was a problem on disposal such as remaining in

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a conventional synthetic resin cardboard which has excellent functions such as water resistance and strength, and has a small amount of heat generated by combustion when incinerated. An object of the present invention is to provide a biodegradable composite material which has the property of being degraded by microorganisms in the soil (biodegradability) when treated, and is almost degraded over a long period of time.

[0004]

In order to solve the above-mentioned problems, according to the first aspect of the present invention, at least one surface of a corrugated sheet made of an aliphatic polyester resin is made of an aliphatic polyester resin. Provided is a biodegradable composite material characterized in that a flat thin plate is heat-sealed.

[0005] The invention according to claim 4 (second invention).
Then, the aliphatic polyester resin sheet in the molten state is corrugated by a corrugated roll, and while holding the corrugated sheet with the corrugated roll, the top of the corrugated sheet is heated from the outside to partially melt the corrugated sheet. 2. The method for producing a biodegradable composite material according to claim 1, wherein the flat thin plates are stacked, and the two are thermally fused and cooled.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
In the present invention, the aliphatic polyester resin has an aliphatic diol and a dicarboxylic acid or a derivative thereof as a main component, and a bifunctional aliphatic oxycarboxylic acid is used in an amount of 0.04 to 6 with respect to 100 moles of the aliphatic dicarboxylic acid (or a derivative thereof).
It is copolymerized in the presence of 0 mol. Furthermore, when a polycondensation reaction is performed mainly on an aliphatic or alicyclic diol and an aliphatic dicarboxylic acid or a derivative thereof, a bifunctional aliphatic oxycarboxylic acid of an α-hydroxycarboxylic acid type represented by lactic acid is added to the fatty acid. Aliphatic polyester resin having a number average molecular weight of 10,000 to 200,000 obtained by using a catalyst comprising a germanium compound in an amount of 0.04 to 60 mol per 100 mol of an aromatic dicarboxylic acid or a derivative thereof. is there. At the time of the polycondensation reaction, a polymerization rate is increased by using a bifunctional aliphatic oxycarboxylic acid such as lactic acid in an appropriate amount in the presence of a catalyst made of a germanium compound, thereby obtaining a high molecular weight aliphatic polyester.

As the aliphatic diol, the following formula: HO-
Aliphatic diols corresponding to (CH ₂ ) _m —OH, where m is an integer of 2 to 10, are preferred. Specifically, ethylene glycol, 1,4-butanediol, 1,6-hexanediol, decamethylene glycol, neopentyl glycol, 1,4-cyclohexanedimethanol and the like can be mentioned. These aliphatic diols may be used alone or as a mixture of two or more. From the viewpoint of the properties of the obtained resin, preferred is 1,4-butanediol or ethylene glycol, and particularly preferred is 1,4-butanediol.

As the aliphatic dicarboxylic acid, the following formula: HO
OC— (CH ₂ ) _n —COOH (where n is 0 or 1 to 1)
It is an integer of 12. The dicarboxylic acids corresponding to) are preferred. Specific examples include succinic acid, adipic acid, suberic acid, sebacic acid, dodecanoic acid, or lower alkyl esters as derivatives thereof, and acid anhydrides such as succinic anhydride and adipic anhydride. These dicarboxylic acids (or derivatives thereof) may be used alone or as a mixture of two or more. From the viewpoint of the properties of the obtained resin, succinic acid, succinic anhydride, or a mixture of succinic acid and adipic acid is particularly preferred.

The bifunctional aliphatic oxycarboxylic acid includes
Aliphatic α-hydroxycarboxylic acids corresponding to the following formula (IV) are preferred.

[0010]

Embedded image

Specific examples of the bifunctional aliphatic oxycarboxylic acid include lactic acid, glycolic acid, 2-hydroxy-n
-Butyric acid, 2-hydroxycaproic acid, 2-hydroxy-3,3-dimethylbutyric acid, 2-hydroxymethylbutyric acid, 2
-Hydroxyisocaproic acid, or mixtures thereof. When these compounds have optical isomers, they may be in D-form, L-form, or racemic form, and may be in the form of solid, liquid, or aqueous solution.
Of these, particularly preferred is lactic acid or an aqueous lactic acid solution that is easily available. The bifunctional aliphatic oxycarboxylic acid may be represented by the above formula (IV) and used in combination with another bifunctional aliphatic oxycarboxylic acid not represented by the formula (IV).

The aliphatic polyester resin as a raw material of the biodegradable composite according to the present invention can be produced by a conventionally known method. That is, the polycondensation reaction when producing this aliphatic polyester resin can be set by combining conventionally known appropriate conditions, and is not particularly limited. The amount of the aliphatic diol to be used is substantially equimolar to 100 mol of the aliphatic dicarboxylic acid or a derivative thereof, but is generally used in an excess of 1 to 30 mol% due to distillation during esterification. Can be

When the amount of the aliphatic oxycarboxylic acid to be added is too small, the molecular weight of the polycondensation reaction product cannot be increased, and when the amount is too large, heat resistance, mechanical properties and the like are poor. It is sufficient, and neither is preferable. The amount of the aliphatic oxycarboxylic acid is preferably 0.04 to 60 mol, more preferably 1 to 40 mol, particularly preferably 2 to 20 mol, per 100 mol of the aliphatic dicarboxylic acid or a derivative thereof. The time and method of adding the aliphatic oxycarboxylic acid are not particularly limited as long as it is before the polycondensation reaction.For example, (1) a method in which a catalyst is added in a state of being dissolved in an aliphatic oxycarboxylic acid solution in advance,
(2) A method of adding the catalyst at the same time as adding the catalyst at the time of raw material charging,
And the like.

The aliphatic polyester resin is obtained by polycondensing the above raw materials in the presence of a polymerization catalyst comprising a germanium compound. Examples of the germanium compound include organic germanium compounds such as tetraalkoxygermanium, and inorganic germanium compounds such as germanium oxide and germanium chloride. Germanium oxide, tetraethoxygermanium, tetrabutoxygermanium, or the like is particularly preferable in terms of price, availability, and the like. The germanium compound may be a single compound or a mixture of two or more compounds. As the germanium compound of the catalyst, other catalysts that can be used in producing polyester can be used in combination. Catalysts that can be used in combination are metal catalysts that are soluble in the reaction system, and include, for example, compounds such as titanium, antimony, tin, magnesium, calcium, and zinc.

The amount of these catalysts used is 0.001 to 3% by weight, more preferably 0.005 to 1.5% by weight, based on the amount of monomers used in the polycondensation reaction. The time for adding the catalyst is not particularly limited as long as it is before the start of the polycondensation, but it is preferable to add the catalyst at the same time as the raw materials are charged, or to add the catalyst by dissolving it in an aqueous solution of aliphatic oxycarboxylic acid. Among them, from the viewpoint of the storage stability of the catalyst, a method in which the catalyst is dissolved in an aliphatic oxycarboxylic acid and added is preferred.

The conditions such as temperature, time and pressure for producing the aliphatic polyester resin depend on the combination of the starting monomers,
The composition ratio, the type of the catalyst, the temperature and the like vary depending on the combination, but the temperature is preferably 150 to 260 ° C, preferably 180 to 230 ° C, and the polymerization time is 2 hours or more, preferably 4 to 15 hours. It is better to choose by range. Reaction pressure is 10
The pressure should be reduced to not more than mmHg, preferably not more than 2 mmHg.

The composition ratio of the aliphatic polyester is as described in the above (I)
It is necessary that the molar ratio of the aliphatic diol unit represented by the formula (I) to the aliphatic dicarboxylic acid unit represented by the formula (III) is substantially equal. The aliphatic diol unit represented by the formula (II) and the aliphatic dicarboxylic acid unit represented by the formula (III) are each in the range of 35 to 49.99 mol%, preferably 40 to 49.75 mol%, more preferably 45
It is good to choose in the range of ４９49.5 mol%. The aliphatic oxycarboxylic acid unit represented by the formula (I) is 0.02
It is good to choose in the range of ３０30 mol%. When the amount of the aliphatic oxycarboxylic acid exceeds 30 mol%, heat resistance and mechanical properties are insufficient, and when the amount is less than 0.02 mol%, the effect of addition does not appear. The above range is preferably 0.5 to 20 mol%, and particularly preferably the range is 1.0 to 10 mol%.

Other copolymerizable components can be introduced into the aliphatic polyester resin as long as the objects and effects of the present invention are not impaired. Examples of other copolymerization components include trifunctional or higher functional polyoxycarboxylic acids, polycarboxylic acids, and polyhydric alcohols. When these other copolymer components are introduced, the melt viscosity of the aliphatic polyester resin can be increased, which is preferable. Specific examples of other copolymer components include malic acid, tartaric acid, citric acid, trimethylolpropane, glycerin, pentaerythritol, trimellitic acid, pyromellitic acid, and the like. From the viewpoint of the physical properties of the aliphatic polyester resin obtained, malic acid, trimethylolpropane, glycerin and the like are particularly preferred.

The aliphatic polyester resin which is the raw material resin of the biodegradable composite according to the present invention has a number average molecular weight divided by gel permeation chromatography (GPC).
The value measured by the method. ｝ Is in the range of 10,000 to 200,000, preferably in the range of 30,000 to 200,000. Also,
Its melting point is preferably in the range of 70 to 180 ° C. Melting point 7
If the temperature is lower than 0 ° C., the heat resistance is insufficient, and if the temperature exceeds 180 ° C., it is difficult to manufacture. The preferred melting point range is 70-1.
It is 50 degreeC, More preferably, it is 80-135 degreeC. Furthermore, the MFR at a temperature of 190 ° C. (JIS K
It refers to a value measured in accordance with 7210. ) Is 0.01 to
A range of 50 g / 10 minutes is preferred. MFR 0.01g
If it is less than / 10 minutes, the moldability is inferior, and if it exceeds 50 g / 10 minutes, heat resistance, mechanical properties, etc. become insufficient,
Neither is preferred.

The aliphatic polyester resin as the raw material resin may be blended with various kinds and amounts of resin additives which do not impair the object and effect of the present invention. Examples of the resin additive include an inorganic filler, an organic filler, a heat stabilizer, an ultraviolet absorber, a dye, a pigment, an antistatic agent, a fluorescent agent, a plasticizer, a lubricant, and a flame retardant.

In the biodegradable composite material according to the present invention, the aliphatic polyester resin is melted to form a corrugated corrugated sheet, and a flat plate made of the same aliphatic polyester resin is fused to at least one surface thereof. Things. The thickness of the corrugated sheet, the shape of the waves, the interval between the waves, the height of the waves, and the like can be appropriately selected according to the use of the composite material.

The flat thin plate to be fused to at least one surface of the corrugated plate is selected from the group consisting of a normal film, a normal sheet, a porous film, a porous sheet, a nonwoven fabric and a woven fabric. Among these flat thin plates, ordinary unstretched films and sheets are prepared using the above aliphatic polyester resin as a raw material, in the same manner as a usual thermoplastic resin molding method,
It can be manufactured by an extrusion molding method, a calendar molding method, or the like.

The porous film and the porous sheet among the flat thin plates can be easily produced by a conventionally known method. For example, the raw material resin 1
At least 50 parts by weight of a filler (inorganic filler or organic filler, or a mixture thereof) and, if necessary, a plasticizer are added to 00 parts by weight to form a composition, and a melt kneader such as an extruder is used. And extruded into a film or sheet, and stretched at least 1.2 times or more in a uniaxial direction. The stretching method may be any of an inflation method and a pin tenter method. Among them, stretched ones are preferable,
Particularly, a porous film or sheet stretched at least 1.2 times or more in a uniaxial direction is preferable.

The nonwoven fabric among the flat thin plates can be easily produced by a conventionally known method.
For example, the above-mentioned aliphatic polyester resin fibers are uniformly dispersed in water, and this is a wet method in which the fibers are scattered in the air, and the fibers are scattered in the air. Examples include an aeration method, a spun bond method for forming a web directly from a spinning machine, and a melt blow method. The nonwoven fabric produced by these methods is not particularly limited in terms of fiber diameter, thickness, basis weight, density, and the like, but usually has a basis weight of 10 to 70 g / m ² . Examples of the woven fabric include plain weave, twill weave, and vermilion weave.

In order to fuse the flat thin plate to at least one surface of the corrugated corrugated sheet, an aliphatic polyester resin is melted by a melting device such as an extruder to form a sheet. A corrugated sheet is sandwiched between rolls. When forming a corrugated sheet, good molding is not performed unless cooled to a temperature lower than the melting point of the raw resin,
In order to perform good molding, it is necessary to set the corrugated roll temperature to a temperature lower than the melting point of the raw material resin. The corrugated sheet is sent to the next step in a state where the corrugated sheet is in close contact with and held on the surface of one corrugated roll.

In the next step, the top of the corrugated sheet still in a softened state is heated from the outside to partially melt the corrugated sheet, and the top of the melted corrugated sheet is melted by another extruder and immediately after extruded. It is preferable to adopt a method in which a flat thin plate still in a melt-softened state or a separately prepared flat thin plate is stacked, and both are pressed and fused by a pressure roller. When the flat thin plate is a porous film or nonwoven fabric, in order to stabilize the thermal fusion between the corrugated sheet and the film or nonwoven fabric,
It is preferable to cool with a blower, and it is preferable to heat with a heating roll at the end of the manufacturing process in order to make the appearance of the composite material beautiful.

Hereinafter, an example of a method for producing a biodegradable composite material according to the present invention will be described in detail with reference to the drawings. FIG.
It is a schematic explanatory view showing an example of an apparatus used when performing the method of the present invention. In the figure, 1 is an extruder, 2 is a sheet, 3 and 4 are corrugated rolls, 5 is a flat thin plate, 6 is a press roll, 7 is a heating device, 8 is a blower, 9, 10,
11 and 12 are guide rolls, 13 pressing rolls, 14 is a heating roll, and 15 and 16 are take-up rolls, respectively.

The aliphatic polyester resin as a raw material is melted by an extruder 1, extruded into a sheet 2 from a die mounted on the tip of a cylinder, and immediately sandwiched between corrugated rolls 3 and 4 to form a corrugated sheet. The temperature of the corrugated rolls 3, 4 is set to a temperature equal to or lower than the melting point of the raw resin. The corrugated sheet 2 is brought into close contact with the surface of the corrugated roll 4.
It is preferable that the temperature of the corrugated roll 4 be set higher than the temperature of the corrugated roll 3 in order to transfer to the next step in the state where the corrugated roll 3 is held.

The temperature of the corrugated rolls 3 and 4 varies depending on the type of the raw aliphatic polyester resin, the extrusion temperature, the extrusion speed, the thickness of the resin sheet 2 and the like. Should be lower by about 1 to 90 ° C. than the melting point of the raw resin. The temperature difference between the corrugated rolls 3 and 4 is 10
About 100 ° C, particularly preferably about 10-50 ° C.

The resin sheet 2 is corrugated by corrugated rolls 3 and 4. At this time, since the resin sheet is cooled to a temperature lower than the melting temperature, the corrugated sheet is
In this state, the top of the corrugated sheet is heated and melted by the heating device 7 to ensure the heat-sealing property with the thin plate 5. The heating device 7 is preferably an infrared heater. The flat thin plate 5 is superimposed on the top of the melted corrugated plate, pressed by a pressing roll 6, and thermally fused. The plate-like thin plate 5 may be any of a film or sheet immediately after being extruded by an extruder, a separately prepared porous film or a nonwoven fabric, and the like.

FIG. 1 shows an example in which the flat thin plate 5 is heat-sealed on one side of the corrugated plate. However, the flat thin plate 5 can be heat-sealed on both sides of the corrugated plate. In order to heat-bond the flat sheet 5 to both sides of the corrugated sheet, the flat sheet 5 is heat-sealed to one side of the corrugated sheet, and then the top of the remaining corrugated sheet is heated and melted. Then, the flat thin plate 5 may be thermally fused. The composite material thus obtained is taken up by the take-up rolls 15, 1
According to 6, it is taken up, wound into a roll, or cut into a flat plate and cut to a certain length, and used for various purposes.

The biodegradable composite material according to the present invention has water resistance,
It has excellent functions, such as strength, and has a small calorific value when incinerated, and exhibits the property of being decomposed by microorganisms in the soil when buried in the soil. Biodegradable composite material. Taking advantage of these special features, drainage materials for civil engineering work, packaging materials for fresh food (cardboard), sanitation
It can be applied to various uses such as medical materials, agriculture, and various other cushioning materials for packaging.

[0033]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist. In the examples described below, the weight retention of the biodegradable composite was measured by placing a sample of the biodegradable composite (2 × 2 cm pieces) in a cup placed in cultivated soil conditioned to 65% of the maximum water capacity. ) Is buried and incubated in a dark place at 30 ° C., and after 3 months, the sample is taken out, washed with water, dried for a whole day and night, the weight of the sample is measured, and the weight retention is calculated by the following formula. OK. The weight retention is a measure of the biodegradation rate, and a smaller value means a higher biodegradation rate. Weight retention (%) = (W2 / W1) × 100 Here, W1 means initial weight before embedding, and W2 means weight after embedding.

[Production Example] <Production Example of Aliphatic Polyester Resin I> Succinic acid was added to a reaction vessel having a capacity of 600 liters equipped with a stirrer, a nitrogen gas inlet tube, a heating device, a thermometer, and an auxiliary agent addition port.
g, 123 liters of 1,4-butanediol and 90% DL in which 1% by weight of germanium oxide was previously dissolved
-7.43 kg of an aqueous lactic acid solution and 0.2 kg of super talc as a crystal nucleating agent were respectively charged, and in a nitrogen gas atmosphere,
The condensation polymerization reaction was performed at 120 to 220 ° C. for 2 hours. Subsequently, the internal temperature of the container was raised to stop the introduction of nitrogen gas.
The deglycol-reaction was performed under a reduced pressure of 5 mmHg for 5 hours.
This condensation polymerization reaction product was extruded into water and cut with a cutter. The obtained aliphatic polyester resin I was white, and the yield was 180 kg.

This aliphatic polyester resin I has a melting point of 110 ° C. (according to the DSC method, a heating rate of 16 ° C./min,
Nitrogen atmosphere), number average molecular weight (Mn) of 65,
000 and the weight average molecular weight was 150,000. The average molecular weight is measured by a GPC method (manufactured by Tosoh Corporation, HLC-8).
Uses 020 type GPC device. Column is PLgel-5μ
-MIX. Polystyrene equivalent. Chloroform solvent. ). The polymer composition measured by 1 H-NMR was as follows: lactic acid unit: 3.1 mol%, succinic acid unit: 48.0 mol%, 1,4-butanediol unit: 4 mol%
It was 8.9 mol%. Further, the MFR measured according to JIS K7210 was 9.6 g / 10 minutes.

<Production Example of Aliphatic Polyester Resin II> In the same reaction vessel used in Example 1, succinic acid was added at 137k.
g, 116 liters of 1,4-butanediol and 90% DL in which 1% by weight of germanium oxide was previously dissolved
-An aqueous lactic acid solution (7.43 kg) and malic acid (0.23 kg) were charged, respectively, and subjected to a condensation polymerization reaction at 120 to 220 ° C for 2 hours in a nitrogen gas atmosphere. Subsequently, the internal temperature of the vessel was raised, the introduction of nitrogen gas was stopped, and a glycol removal reaction was performed for 4 hours under a reduced pressure of 0.5 mmHg. This condensation polymerization reaction product was extruded into water and cut with a cutter. The obtained aliphatic polyester resin II is white, and the yield is 180 k.
g.

This aliphatic polyester resin II had a melting point of 111 ° C., a number average molecular weight (Mn) of 75,000, and a weight average molecular weight of 190,000. Also, 1H-N
The polymer composition by MR was 3.1 mol% of lactic acid units, 48.1 mol% of succinic acid units, and 48.8 mol% of 1,4-butanediol units. Further, the MFR is 5.0 g.
/ 10 minutes.

<Production Example of Aliphatic Polyester Resin III>
In the same reaction vessel used in Example 1, succinic acid was added to 123
kg, 17 kg of adipic acid, 121 liters of 1,4-butanediol, 7.43 kg of a 90% DL-lactic acid aqueous solution in which 1% by weight of germanium oxide was previously dissolved,
0.23 kg of trimethylolpropane was charged in an amount of 0.2 kg, and reacted at 120 to 220 ° C. for 2 hours in a nitrogen gas atmosphere. Subsequently, the internal temperature of the vessel was increased, the introduction of nitrogen gas was stopped, and a glycol removal reaction was performed for 5 hours under a reduced pressure of 0.5 mmHg. The reaction product was extruded into water and cut with a cutter. The obtained aliphatic polyester resin III was white, and the yield was 180 kg.

The aliphatic polyester resin III had a melting point of 90 ° C., a number average molecular weight (Mn) of 68,000, and a weight average molecular weight of 173,000. Also, 11H-
The polymer composition by NMR was 3.3 mol% of lactic acid units,
It was 43.3 mol% of succinic acid units, 4.8 mol% of adipic acid, and 48.6 mol% of 1,4-butanediol units. Further, the MFR was 8.2 g / 10 minutes.

[Example 1] Aliphatic polyester resin I
Is melted by an extruder 1 shown in FIG. 1 and extruded as a sheet 2 and formed into a corrugated sheet by corrugating rolls 3 (set temperature: 80 ° C.) and 4 (set temperature: 95 ° C.). While the sheet 5 is in a molten state, the sheet 5 is pressed against the top of the corrugated sheet by the overlapping press roll 6 to thermally fuse the two, and the guide rolls 9, 10, 1
1 and passed between the pressing rolls 13 and 14 and pulled by the pulling rolls 15 and 16 to obtain a composite material in which the sheet was heat-sealed to one surface of the corrugated sheet. The production conditions of the sheets 2 and 5 are as follows: cylinder temperature: 120-140.
-150-160 ° C, head and die temperature: 160 ° C,
Die width (W): 1000mm, sheet take-off speed: 10m /
min, sheet thickness: 150 μm. The weight retention of the obtained biodegradable composite material was 93%.

Example 2 A biodegradable composite material was obtained in the same manner as in Example 1 except that the raw material resin was changed to aliphatic polyester resin II. The weight retention of the resulting biodegradable composite is
79%.

Example 3 In the example described in Example 1, the raw material resin was changed to the aliphatic polyester resin II, and the corrugated sheet processing conditions of the sheet 2 were set such that the corrugated roll 3 was set at a temperature of 60 ° C. The biodegradable composite material was obtained in the same procedure as in the same example except that the set temperature was changed to 75 ° C. The weight retention of the obtained biodegradable composite material was 61%.

Example 4 In the example described in Example 1, after the sheet 2 was a corrugated sheet and the sheet 5 was heat-sealed to the top of the corrugated sheet, the sheet was guided while the corrugated sheet was in a molten state. Before being transferred to the roll 9, the sheet is obtained by another extruder (not shown), and while the sheet is in a molten state, pressed on another corrugated sheet (not shown) by overlapping the top of the corrugated sheet; The two are heat-sealed to form guide rolls 9, 10, 11
Then, the composite material was passed between the pressing rolls 13 and 14 and taken up by the take-off rolls 15 and 16 to obtain a composite material in which sheets were heat-sealed on both sides of the corrugated sheet. The extruder cylinder temperature, head and die temperature, die width (W), take-up speed, sheet thickness and the set temperature of the corrugated rolls 3 and 4 when producing this composite material were the same as those in Example 1. The weight retention of the resulting biodegradable composite is
95%.

Example 5 A biodegradable composite material was obtained in the same manner as in Example 4 except that the raw material resin was changed to aliphatic polyester resin II. The weight retention of the resulting biodegradable composite is
84%.

Example 6 A biodegradable composite material was obtained in the same manner as in Example 4 except that the raw material resin was changed to aliphatic polyester resin III. The weight retention of the resulting biodegradable composite is
75%.

[0046]

The present invention has the following particularly advantageous effects, and its industrial value is extremely large. 1. The biodegradable composite material according to the present invention is similar to conventional resin-made corrugated cardboard, and is used as a drainage material for civil engineering work, a packaging material for fresh food products, a sanitary / medical material, agriculture, and other various cushioning materials for packaging. It can be applied to various uses. 2. Since the biodegradable composite material according to the present invention has a property of being degraded by microorganisms, problems in disposal can be reduced.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view showing an example of an apparatus used when carrying out the method of the present invention.

[Explanation of symbols]

 1: Extruder 2: Sheet 3, 4: Corrugated roll 5: Flat thin plate 6: Press roll 7: Heating device 8: Blower 9, 10, 11, 12: Guide roll 13: Press Roll 14: Heating roll 15, 16: Take-up roll 17: Composite material

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Hiroaki Yamaoka 1000 Kamoshita-cho, Aoba-ku, Yokohama-shi, Kanagawa Prefecture Inside the Yokohama Research Laboratory, Mitsubishi Chemical Corporation (72) Inventor Kenichi Tanaka 1789 Minato, Shiratori-cho, Okawa-gun, Kagawa Prefecture Shikoku Kako Inside the corporation

Claims (8)

[Claims] 1. A biodegradable composite material, wherein a flat thin plate made of an aliphatic polyester resin is heat-sealed to at least one surface of a corrugated sheet made of an aliphatic polyester resin. 2. The biodegradable composite according to claim 1, wherein the flat sheet is selected from the group consisting of a film, a sheet, a nonwoven fabric and a woven fabric. 3. The biodegradable composite material according to claim 1, wherein the flat thin plate is a porous film or a porous sheet stretched at least 1.2 times in a uniaxial direction. 4. An aliphatic polyester resin sheet in a molten state is formed into a corrugated sheet by a corrugated roll, and while the corrugated sheet is held by the corrugated roll, the top of the corrugated sheet is heated from the outside to partially melt the corrugated sheet. 2. The method for producing a biodegradable composite material according to claim 1, wherein a flat thin plate is stacked on the thin plate, and the two are thermally fused and cooled. 5. The method for producing a biodegradable composite material according to claim 4, wherein the flat thin plate is formed by melt molding with an extruder. 6. An aliphatic polyester resin having a temperature of 190.
MFR in ° C. is 0.01 to 50 g / 10 minutes,
The method for producing a biodegradable composite material according to claim 4, wherein the melting point is 70 to 180 ° C. 7. 7. An aliphatic polyester resin comprising the following (I)
An aliphatic oxycarboxylic acid unit represented by the formula:
30 mol%, 35 to 49.99 mol% of an aliphatic diol unit represented by the following formula (II), and 35 to 49.99 mol% of an aliphatic dicarboxylic acid unit represented by the following formula (III); The method for producing a biodegradable composite according to any one of claims 4 to 6, wherein the number average molecular weight is 10,000 to 200,000. Embedded image Embedded image Embedded image 8. The aliphatic oxycarboxylic acid is lactic acid,
The method for producing a biodegradable composite according to any one of claims 4 to 7, wherein the aliphatic diol is -1,4-butanediol, and the aliphatic dicarboxylic acid is succinic acid.