JP2014144553A - Biodegradable resin sheet and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a biodegradable resin sheet which contains a poly(3-hydroxyalkanoate), can satisfactorily form a film even without using a crystal nucleating agent and has an excellent barrier property.SOLUTION: There is provided a biodegradable resin sheet 10 which comprises a first biodegradable resin layer 11 and a second biodegradable resin layer 12, wherein the first biodegradable resin layer 11 contains 10 to 90 mass% of a poly(3-hydroxyalkanoate), the content ratio of the poly(3-hydroxyalkanoate) in the second biodegradable resin layer 12 is less than 10 mass%, the content ratio of the poly(3-hydroxyalkanoate) based on the total mass is 10 to 60 mass%, and the biodegradable resin sheet 10 is formed by simultaneous multilayer formation.

Description

  The present invention relates to a biodegradable resin sheet and a method for producing the same.

Conventionally, wastes of plastic molded products are often landfilled and have a large environmental load, and in recent years, the use of biodegradable resins has been spreading. Until now, biodegradable resins made from fossil fuels have been widely used, but biodegradable resins made from fossil fuels can reduce carbon dioxide emissions, which are responsible for global warming. It is not a reduction. Therefore, the use of biodegradable resins derived from biomass using biomass such as plants as a raw material has been studied.
As biodegradable resins derived from biomass, poly (3-hydroxyalkanoate) and polylactic acid are known. Poly (3-hydroxyalkanoate) is a soft resin, and polylactic acid is a hard resin. Therefore, in order to obtain a biodegradable soft sheet derived from biomass, it was necessary to use poly (3-hydroxyalkanoate) (Patent Document 1).
In addition, poly (3-hydroxyalkanoate) has a property of higher barrier properties than other biodegradable resins. Therefore, by using poly (3-hydroxyalkanoate), a sheet having both biodegradability and high barrier properties may be obtained (Patent Document 2). Here, the barrier property is one of the performances of a plastic sheet or film, and refers to the permeation-preventing property of gases such as oxygen and carbon dioxide and water vapor. It is indicated by the rate (moisture permeability).
However, since poly (3-hydroxyalkanoate) has a low crystallization rate, the cooling and solidification of the molten resin is difficult to proceed in the T-die extrusion molding, inflation molding, and calendar molding, which are general sheet molding methods. Is bad. For this reason, it has been difficult to use poly (3-hydroxyalkanoate) alone. Further, even when other biodegradable resin was mixed with poly (3-hydroxyalkanoate), crystallization did not proceed, the formability was unstable, and a sheet was not obtained.
Therefore, in order to improve the crystallization speed of poly (3-hydroxyalkanoate), inorganic particles, organic particles, inorganic fibers, organic fibers, glycine, alanine, or the like may be added as a crystal nucleating agent (patent) References 3, 4).

International Publication No. 2001/014883 Japanese Patent Laid-Open No. 2005-162884 JP 2006-45366 A International Publication No. 2009/113288

  However, when a sheet is formed using the crystal nucleating agent described in Patent Documents 3 and 4, the crystal nucleating agent remains as an unmelted material in the sheet, and depending on the amount of the crystal nucleating agent added, the sheet appearance may be impaired, There were times when holes were opened.

  The present invention provides a biodegradable resin sheet containing poly (3-hydroxyalkanoate) and capable of forming a film well without using a crystal nucleating agent and having excellent barrier properties, and a method for producing the same. The purpose is to do.

The biodegradable resin sheet of the present invention has a first biodegradable resin layer and a second biodegradable resin layer, and the first biodegradable resin layer comprises poly (3-hydroxyalkanoate), poly And at least one selected from the group consisting of butylene succinate, polybutylene succinate adipate, and polybutylene adipate terephthalate, and the content ratio of poly (3-hydroxyalkanoate) in the first biodegradable resin layer is 10 to 10. 90% by mass, the second biodegradable resin layer contains a biodegradable resin, and the content ratio of poly (3-hydroxyalkanoate) in the second biodegradable resin layer is less than 10% by mass, The mass ratio of poly (3-hydroxyalkanoate) is 10 to 60 mass% with respect to the total mass, and is molded by simultaneous multilayer molding.
The method for producing a biodegradable resin sheet according to the present invention includes a step of co-extrusion molding of a first biodegradable resin layer and a second biodegradable resin layer and simultaneous multilayer molding, and the first biodegradable resin layer The layer contains poly (3-hydroxyalkanoate) and at least one selected from the group consisting of polybutylene succinate, polybutylene succinate adipate, polybutylene adipate terephthalate, and a first biodegradable resin layer In the second biodegradable resin layer, the poly (3-hydroxyalkanoate) content is 10 to 90% by mass, and the second biodegradable resin layer contains a biodegradable resin. The content ratio of (hydroxyalkanoate) is less than 10 mass%, and the mass ratio of poly (3-hydroxyalkanoate) is 10 to 60 mass% with respect to the total mass.

The biodegradable resin sheet of the present invention contains poly (3-hydroxyalkanoate) and can form a film satisfactorily despite not using a crystal nucleating agent, and has excellent barrier properties. Moreover, since this biodegradable resin sheet has much content of poly (3-hydroxy alkanoate), the usage-amount of biomass raw material is high.
According to the method for producing a biodegradable resin sheet of the present invention, it is possible to form a film satisfactorily despite containing poly (3-hydroxyalkanoate) and not using a crystal nucleating agent. Can be improved.

It is sectional drawing which shows one Embodiment of the biodegradable resin sheet of this invention.

One embodiment of the biodegradable resin sheet of the present invention will be described.
In FIG. 1, the biodegradable resin sheet of this embodiment is shown. The biodegradable resin sheet 10 of this embodiment includes a first biodegradable resin layer 11 that is an inner layer and a second biodegradable resin layer 12 that is an outer layer formed on both surfaces of the first biodegradable resin layer 11. , 12 and two types and three layers.

  The first biodegradable resin layer 11 includes poly (3-hydroxyalkanoate) (hereinafter referred to as “component A”), polybutylene succinate (hereinafter referred to as “PBS”), polybutylene succinate adipate ( Hereinafter referred to as “PBSA”) and at least one selected from the group consisting of polybutylene adipate terephthalate (hereinafter referred to as “PBAT”) (hereinafter referred to as “component B”).

Component A is an aliphatic polyester copolymer having a unit represented by the following formula (1). Component A can be produced using biomass as a raw material and microorganisms.
Formula (1): [—CHR—CH ₂ —CO—O—]
However, R is an alkyl group represented by C _n H _{2n + 1} (n is an integer of 1 to 15. Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, a butyl group, and a hexyl group. Group, octyl group, decyl group and the like.

Specific examples of component A include 3-hydroxybutyrate, 3-hydroxypropionate, 3-hydroxyvalerate, 3-hydroxyhexanoate, 3-hydroxyheptanoate, 3-hydroxyoctanoate, 3 At least one selected from -hydroxynonanoate, 3-hydroxydecanoate, 3-hydroxydodecenoate, 3-hydroxytetradecanoate, 3-hydroxyhexadecanoate, 3-hydroxyoctadecanoate Mention may be made of copolymers with monomers.
Among these, in the above formula (1), poly (3-hydroxybutyrate-co-3-hydroxyhexanoate) having a unit of n = 1 and a unit of n = 3 (hereinafter referred to as “PHBH”) .) Is preferred. PHBH has a molding temperature close to that of Component B and is excellent in mechanical properties.

The molar ratio (3HB / 3HH) of poly (3-hydroxybutyrate) units (hereinafter referred to as “3HB”) and poly (3-hydroxyhexanoate) units (hereinafter referred to as “3HH”) in PHBH is 99/1 to 80/20 are preferable, and 95/5 to 85/15 are more preferable. When the molar ratio of 3HH exceeds 20, it may become hard and sufficient softness may not be ensured. On the other hand, when the molar ratio of 3HB increases, the softness increases, but when it exceeds 99, the crystallization rate decreases and the moldability decreases and the barrier property tends to decrease.
The PHBH melt flow rate (JIS K7210-1999, temperature 160 ° C., load 2.16 kgf) is preferably in the range of 0.5 to 10.0 g / 10 minutes, and the sheet formability is improved. A range of 5.0 g / 10 min is more preferred. In the present specification, “melt flow rate” is expressed as “MFR”.

Component B, PBS, is an aliphatic polyester obtained by condensation polymerization of 1,4-butanediol and succinic acid. The PBS includes those having a long chain branching structure. PBS having a long-chain branched structure is excellent in melt tension, has a large non-linearity in extensional viscosity, and has high stability in melt molding of a sheet (see, for example, Japanese Patent No. 3434517).
The MFR of PBS (JIS K7210-1999, temperature 190 ° C., load 2.16 kgf) is usually in the range of 0.5 to 10.0 g / 10 min, and the MFR of PBS having no long chain branching structure is 0.00. It is preferably 5 to 5.0 g / 10 min, and the MFR of PBS having a long chain branched structure is preferably 4.0 to 8.0 g / 10 min.
PBSA is an aliphatic polyester obtained by copolymerizing succinic acid with PBS. The MFR (JIS K7210-1999, temperature 190 ° C., load 2.16 kgf) of PBSA is preferably 0.5 to 10.0 g / 10 min.
PBAT is a copolymer of 1,4 butanediol, adipic acid and terephthalic acid. The MFR (JIS K7210-1999, temperature 190 ° C., load 2.16 kgf) of PBAT is preferably 1.0 to 5.0 g / 10 minutes.
Component B, PBS, PBSA, PBAT, has a relatively high crystallization rate, and has the above-described T-die extrusion moldability, inflation moldability, and calendar moldability.

  The content rate of the component A in the 1st biodegradable resin layer 11 is 10-90 mass% when the sum total of the component A and the component B is 100 mass%, and it is preferable that it is 15-50 mass%. When the proportion of component A in the first biodegradable resin layer 11 is less than the lower limit value, the barrier property is lowered, and when it exceeds the upper limit value, the film forming property is deteriorated.

  The first biodegradable resin layer 11 includes an antioxidant, an ultraviolet ray inhibitor, an antiblocking agent (for example, higher fatty acid salt), a lubricant (higher fatty acid metal salt, waxes, etc.), starches, corn starches, and coloring. Additives such as agents may be included.

The second biodegradable resin layer 12 is at least one biodegradable selected from the group consisting of component A, component B, component A, and biodegradable resin other than component B (hereinafter referred to as “component C”). Contains resin.
Examples of component C include polylactic acid, polycaprolactone, polyglycolic acid, polyvinyl alcohol and the like.

  The content ratio of Component A in the second biodegradable resin layer 12 is less than 10% by mass, preferably 5% by mass or less, more preferably 2% by mass or less, and particularly preferably 0% by mass, that is, not contained at all. When the content ratio of the component A in the second biodegradable resin layer 12 is equal to or higher than the upper limit value, the crystallization rate when the biodegradable resin sheet 10 is molded becomes slow, and the film forming property tends to deteriorate.

  The second biodegradable resin layer 12 includes an antioxidant, an ultraviolet ray inhibitor, an anti-blocking agent (for example, higher fatty acid salts), a lubricant (higher fatty acid metal salts, waxes, etc.), starches, corn starches, and coloring. Additives such as agents may be included. When an additive is included, it may be included in only one of the two second biodegradable resin layers 12, or may be included in both.

  The mass ratio of all components A to the total mass of the biodegradable resin sheet 10 is 10 to 60 mass%, and more preferably 20 to 60 mass%. When the mass ratio of all components A is less than the lower limit value, the barrier property is lowered and the use ratio of the biomass raw material is lowered. When the upper limit value is exceeded, the film forming property is lowered.

The total thickness of the biodegradable resin sheet 10 is preferably 0.05 to 1.0 mm. That is, the biodegradable resin sheet 10 includes a so-called “film” having a thickness.
If the total thickness of the biodegradable resin sheet 10 is within the above range, it can be molded by a general cooling method in the above molding method, and the sheet moldability is good. In addition, if the thickness of the biodegradable resin sheet 10 is equal to or greater than the lower limit value, barrier properties can be obtained and sufficient strength can be ensured. If the thickness is equal to or less than the upper limit value, the moldability can be obtained and sufficient. Flexibility can be secured.

  As a method for producing the biodegradable resin sheet 10, the first biodegradable resin layer and the second biodegradable resin layer are co-extruded and simultaneously formed using a multilayer T-die molding apparatus, a multilayer inflation molding apparatus, or the like. A multi-layer forming method is applied.

The second biodegradable resin layer 12 in the biodegradable resin sheet 10 has a low component A content or does not contain the component A, and thus has high melt moldability and can be stably formed into a film. Therefore, the moldability of the first biodegradable resin layer 11 is compensated by simultaneously forming the first biodegradable resin layer 11 containing a large amount of the component A having a slow crystal acceleration together with the second biodegradable resin layer 12. Can do. Therefore, the film can be satisfactorily formed although the component A is contained and no crystal nucleating agent is used. In addition, since the biodegradable resin sheet 10 does not contain a crystal nucleating agent, the appearance of the sheet is good and the occurrence of defects such as opening of holes is prevented.
Moreover, since the said biodegradable resin sheet 10 contains many components A, its barrier property is high and the usage-amount of a biomass raw material is high.

In addition, the arrangement | positioning of the 1st biodegradable resin layer and the 2nd biodegradable resin layer in the biodegradable resin sheet of this invention will be said 2 if the mass ratio of the component A with respect to the whole sheet mass is the said range. It is not limited to the seed 3 layer. For example, a two-type three-layer sheet in which the inner layer is the second biodegradable resin layer and the outer layer is the first biodegradable resin layer may be used.
Moreover, the 2 type 2 layer sheet | seat which consists of a 1st biodegradable resin layer and a 2nd biodegradable resin layer may be sufficient.
Further, the biodegradable resin sheet of the present invention may be a three-kind three-layer sheet. Examples of the three-kind three-layer sheet include a sheet having two first biodegradable resin layers and one second biodegradable resin layer having different compositions, and one layer of first biodegradable resin. And a sheet having two layers of second biodegradable resin layers having different compositions from each other. The two second biodegradable resin layers having different compositions are, for example, a layer composed of B component / a layer composed of C component, a layer composed of A component and B component (however, A component is less than 10% by mass) / A component and C component layer, A component and B component layer (A component is less than 10% by mass) / C component layer, A component and B component layer (however, A component is less than 10% by mass) / B component layer, B component and C component layer / C component layer, B component and C component layer / B component layer, and the like.
Furthermore, the biodegradable resin sheet of the present invention may be a sheet having four or more layers (for example, a two-kind five-layer sheet, a three-kind five-layer sheet).
As the two types and five layers, the first biodegradable resin layer / second biodegradable resin layer / first biodegradable resin layer / second biodegradable resin layer / first biodegradable resin layer are laminated. Sheet comprising composition, sheet comprising laminate structure of second biodegradable resin layer / first biodegradable resin layer / second biodegradable resin layer / first biodegradable resin layer / second biodegradable resin layer .
As the three types and five layers, the first biodegradable resin layer / second biodegradable resin layer / first biodegradable resin layer / second biodegradable resin layer / first biodegradable resin layer are laminated. A sheet having a different composition from the first first biodegradable resin layer and the outer first biodegradable resin layer, second biodegradable resin layer / first biodegradable resin layer / second biodegradable A sheet having a laminated structure of a resin layer / first biodegradable resin layer / second biodegradable resin layer, the composition of the intermediate second biodegradable resin layer and the outer second biodegradable resin layer being different from each other, Can be mentioned.

Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples. However, the present invention is not limited to the following examples.
In the following examples, a biodegradable resin was used.
<Component A>
A1: PHBH, Aonilex X131A (3HH molar ratio: 5.5%, MFR: 1 g / 10 min, manufactured by Kaneka Corporation)
A2: PHBH, Aonilex X151A (3HH molar ratio: 11.5%, MFR: 2 g / 10 min, manufactured by Kaneka Corporation)
The MFR of component A is a value measured under the conditions of JIS K7210-1999, temperature 160 ° C., load 2.16 kgf.
<Component B>
B1: PBS, Bionore 1001MD (MFR: 1.9 g / 10 min, manufactured by Showa Denko KK)
B2: PBS, Bionore 1903MD (MFR: 5.8 g / 10 min, manufactured by Showa Denko KK)
B3: PBSA, Bionore 3001MD (MFR: 1.0 g / 10 min, manufactured by Showa Denko KK)
B4: PBAT, Ecoflex F BLEND (MFR: 4.5 g / 10 min, manufactured by BASF)
The MFR of component B is a value measured under the conditions of JIS K7210-1999, temperature 190 ° C., load 2.16 kgf.

(Examples 1-15, Comparative Examples 1-4)
Using the following three-layer inflation film forming apparatus, simultaneous multi-layer sheet molding was performed with the formulations shown in Tables 1 to 7 to obtain biodegradable resin sheets. Two types of biodegradable resin sheets having a thickness of 40 μm and 100 μm were formed.
In Tables 1 to 7, “%” means “mass%”.
[Three-layer inflation film formation system]
Molding device: EXU65 EXU95 EXU65 L / D
Die: Three-layer die Cooling device: Placo 2-stage external cooling device Cooling gas: Use air at room temperature 25 ° C Molding temperature: 145 ° C-165 ° C Extruder Die

<Evaluation>
The obtained biodegradable resin sheet was evaluated for barrier properties. Specifically, oxygen permeability and carbon dioxide permeability were measured based on JIS K7126, and moisture permeability was measured based on JIS Z0208. The measurement results are shown in Tables 8-13.
In Comparative Examples 1 and 4, the film forming property was low and the sheet could not be formed, so the barrier property was not evaluated.

In Examples 1 to 15 in which the layer containing 10 to 90% by mass of component A and the layer containing less than 10% by mass of component A are formed simultaneously, and the content ratio of component A to the whole is 10 to 60% by mass, good Film formation was possible and the barrier property was high.
In Comparative Example 1 in which Component A does not have a layer of less than 10% by mass, film formation was impossible.
The biodegradable resin sheet of Comparative Example 2 that did not contain Component A and the biodegradable resin sheet of Comparative Example 3 in which the content ratio of Component A relative to the whole was less than 10% by mass had low barrier properties.
In Comparative Example 4 where the component A has a layer exceeding 90% by mass, film formation was impossible.

  The biodegradable resin sheet of the present invention can be suitably used for, for example, agricultural members, forestry members, building members, packaging members, sundries and the like. Specifically, it can be used for agricultural multi-films, fumigation sheets, cushioning materials, garbage bags, plastic bags, barrier packaging materials, and the like.

10 biodegradable resin sheet 11 first biodegradable resin layer 12 second biodegradable resin layer

Claims (2)

Having a first biodegradable resin layer and a second biodegradable resin layer;
The first biodegradable resin layer contains poly (3-hydroxyalkanoate) and at least one selected from the group consisting of polybutylene succinate, polybutylene succinate adipate, and polybutylene adipate terephthalate. The content ratio of poly (3-hydroxyalkanoate) in the biodegradable resin layer is 10 to 90% by mass,
The second biodegradable resin layer contains a biodegradable resin, and the content ratio of poly (3-hydroxyalkanoate) in the second biodegradable resin layer is less than 10% by mass;
The mass proportion of poly (3-hydroxyalkanoate) is 10 to 60 mass% with respect to the total mass,
A biodegradable resin sheet formed by simultaneous multilayer molding. A step of co-extrusion molding of the first biodegradable resin layer and the second biodegradable resin layer and simultaneous multilayer molding;
The first biodegradable resin layer contains poly (3-hydroxyalkanoate) and at least one selected from the group consisting of polybutylene succinate, polybutylene succinate adipate, polybutylene adipate terephthalate, The content ratio of poly (3-hydroxyalkanoate) in one biodegradable resin layer is 10 to 90% by mass,
The second biodegradable resin layer contains a biodegradable resin, and the content ratio of poly (3-hydroxyalkanoate) in the second biodegradable resin layer is less than 10% by mass,
A method for producing a biodegradable resin sheet, wherein the mass ratio of poly (3-hydroxyalkanoate) is 10 to 60 mass% with respect to the total mass.

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