JP5510892B2 - Biodegradable laminate and biodegradable container using the same - Google Patents

Description

  The present invention relates to a biodegradable resin laminate having both hygiene and biodegradability and a biodegradable container formed from the laminate.

A packaging container containing a biodegradable resin composition has been proposed as a packaging material, and the use of a resin composition containing a decomposition accelerator in the biodegradable resin has been proposed in order to improve the degradation rate. (Patent Document 1). When such a resin composition (also referred to as an easily decomposable composition) is placed in a decomposition solution containing a biodegradable enzyme, excellent biodegradability can be obtained by the action of a decomposition accelerator in the resin.
However, when a food or liquid containing moisture is put into a container or the like manufactured from a resin composition containing the above-described decomposition accelerator, the decomposition accelerator inside the container is eluted, and thus hygiene concerns arise. There was a problem.

International Application Publication No. 2008/038648

  An object of this invention is to provide the biodegradable resin laminated body which suppressed the elution of the decomposition accelerator to the liquid.

According to the present invention, a biodegradable resin containing a substance having an affinity for a degradation product of the degradation accelerator is disposed between the biodegradable resin containing the degradation accelerator and the liquid, so that the liquid is contained in the liquid. This is based on the knowledge that elution of the decomposition accelerator can be efficiently suppressed.
That is, the present invention is a biodegradable resin having a biodegradable resin layer A containing a decomposition accelerator and a biodegradable resin layer B containing a substance having an affinity for a decomposition product of the decomposition accelerator. A laminate is provided.
The present invention is also a biodegradable container molded from the biodegradable resin laminate, wherein the biodegradable resin layer B is disposed on the inner side of the container with respect to the biodegradable resin layer A. A biodegradable container is provided.

  By this invention, it becomes possible to manufacture the biodegradable container which suppressed elution of the decomposition accelerator from biodegradable resin and was compatible with hygiene and biodegradability.

For Examples 1 and 2 and Comparative Examples 1 and 2, the amount of oxalic acid eluted into the decomposition solution is shown. For Examples 1 and 2 and Comparative Examples 1 and 2, the decomposition rates after 4 days of decomposition are shown. For Example 3 and Comparative Examples 3 and 4, the amount of glycolic acid eluted into the decomposition solution is shown. The gradient pattern in a HPLC measurement is shown.

The biodegradable resin laminate of the present invention has a biodegradable resin layer A containing a decomposition accelerator and a biodegradable resin layer B containing a substance having an affinity for a decomposition product of the decomposition accelerator. .
The biodegradable resin constituting the biodegradable resin layer A and the biodegradable resin layer B may be any resin that has biodegradability, such as a chemically synthesized resin, a microbial resin, a natural product-based resin, and the like. Can be mentioned. Specifically, aliphatic polyester, polyvinyl alcohol (PVA), celluloses, starches and the like can be mentioned. Examples of the aliphatic polyester include polylactic acid (PLA) resin and derivatives thereof, polybutylene succinate (PBS) resin and derivatives thereof, polycaprolactone (PCL), polyhydroxybutyrate (PHB) and derivatives thereof, polyethylene adipate (PEA) ), Polyglycolic acid (PGA), polytetramethylene adipate, condensates of diol and dicarboxylic acid, and the like. Examples of celluloses include methyl cellulose, ethyl cellulose, and acetyl cellulose. These may be used alone, in a copolymer, or in combination of two or more. Examples of the component forming the copolymer include polyhydric alcohols such as ethylene glycol, propylene glycol, butanediol, octanediol, dodecanediol, neopentyl glycol, glycerin, pentaerythritol, sorbitan, bisphenol A, and polyethylene glycol; succinic acid Dicarboxylic acids such as adipic acid, sebacic acid, glutaric acid, decanedicarboxylic acid, cyclohexanedicarboxylic acid, terephthalic acid, isophthalic acid, anthracene dicarboxylic acid; glycolic acid, L-lactic acid, D-lactic acid, hydroxypropionic acid, hydroxybutyric acid, Hydroxycarboxylic acids such as hydroxyvaleric acid, hydroxycaproic acid, mandelic acid, hydroxybenzoic acid; glycolide, caprolactone, butyrolactone, valerolactone, poropiola Tons, such as lactones, such as undecalactone and the like.
Further, it may be a mixture of the biodegradable resin, a general-purpose chemical resin such as polyethylene, polypropylene, polystyrene, polyethylene terephthalate, nylon, and polycarbonate, and an additive. Here, plasticizers, heat stabilizers, light stabilizers, antioxidants, ultraviolet absorbers, flame retardants, colorants, pigments, fillers, inorganic fillers, mold release agents, antistatic agents, fragrances, lubricants are used as additives. , Foaming agents, antibacterial / antifungal agents, nucleating agents and the like.

  The biodegradable resin contained in the biodegradable resin layer A contains a decomposition accelerator, preferably 0.1 to 20 parts by weight, for example 1.0 to 0.1 parts by weight of the decomposition accelerator with respect to 100 parts by weight of the biodegradable resin. Contains 10 parts by weight. If the amount of the decomposition accelerator used is too small, it may be difficult to promote the decomposition of the biodegradable resin, and if it is used in an excessive amount, it may be used as an adjustment stage or molded product of this resin composition. This is because the biodegradable resin may start to be decomposed at the stage where it is used. The decomposition accelerator preferably releases an acid by hydrolysis, and the acid to be released preferably has a pH (25 ° C.) in an aqueous solution or dispersion having a concentration of 0.005 g / ml of 4 or less, particularly 3 or less. As shown, polymers that readily hydrolyze to release acid when mixed with water are preferably used. Specific examples of the acid to be released include oxalic acid, maleic acid, maleic anhydride, glycolic acid and the like, and oxalic acid and glycolic acid are preferred among the above. Examples of such a decomposition accelerator include polyoxalate, polyethylene maleate, polyglycolic acid and the like. Preferred decomposition accelerators are polyethylene oxalate and polyglycolic acid. These may be copolymers, used alone or in combination of two or more. Examples of the component forming the copolymer include polyhydric alcohols such as ethylene glycol, propylene glycol, butanediol, octanediol, dodecanediol, neopentyl glycol, glycerin, pentaerythritol, sorbitan, bisphenol A, and polyethylene glycol; succinic acid, adipine Acids, sebacic acid, glutaric acid, decanedicarboxylic acid, cyclohexanedicarboxylic acid, terephthalic acid, isophthalic acid, anthracene dicarboxylic acid and other dicarboxylic acids; glycolic acid, L-lactic acid, D-lactic acid, hydroxypropionic acid, hydroxybutyric acid, hydroxy Hydroxycarboxylic acids such as herbic acid, hydroxycaproic acid, mandelic acid, hydroxybenzoic acid; glycolide, caprolactone, butyrolactone, valerolactone, poropio Becton, such as lactones, such as undecalactone and the like.

  In the present specification, a polymer obtained by polymerizing oxalic acid as at least one monomer in a homopolymer, copolymer, or blend is referred to as polyoxalate.

  In particular, the above-mentioned polyoxalate and polyglycolic acid are easily hydrolyzable biodegradable resins, and are also preferably used in that they have biodegradability by themselves.

  In addition, the above-described decomposition accelerator is preferably one whose glass transition point (Tg) is lower than the deactivation temperature of the enzyme used for the decomposition of the biodegradable resin. By using the one having such a low glass transition point, it becomes possible to accelerate the degradation of the biodegradable resin by an enzyme more rapidly. The glass transition temperature can be measured using, for example, DSC 6220 (differential scanning calorimetry) manufactured by Seiko Instruments Inc.

  The biodegradable resin contained in the biodegradable resin layer B contains a substance having an affinity for the decomposition product of the decomposition accelerator. When the biodegradable resin layer B contains the above-described substances, the biodegradable resin layer B binds to the decomposition product of the decomposition accelerator eluted from the inside of the adjacent biodegradable resin layer A and is trapped in the biodegradable resin layer B. And it can suppress that the said decomposition product further elutes the exterior of the biodegradable resin layer B. FIG. In this specification, “having affinity” means that it can bind to a degradation product to be affinityd, but the binding mode (chemical bond, physical bond, etc.), strength, etc. Is not particularly limited as long as at least a part of the decomposition product can be captured to such an extent that the above-described effects can be obtained.

The substance having affinity with the decomposition product of the decomposition accelerator is preferably an inorganic compound and / or a metal compound. Examples of such compounds include inorganic compounds such as calcium compounds, sodium compounds, potassium compounds, lithium compounds, for example, salts of calcium, sodium, potassium, lithium, and acids such as carbonic acid and acetic acid. Of these, calcium carbonate is most preferred. Examples of the metal compound include iron compounds, copper compounds, silver compounds, aluminum compounds, nickel compounds, tin compounds, magnesium compounds, titanium compounds, zinc compounds, and the like, for example, iron oxide. For example, when calcium carbonate is used as the compound and polyoxalate is used as a decomposition accelerator, oxalic acid, which is a decomposition product of polyoxalate, reacts with calcium carbonate to form calcium oxalate, which is an insoluble salt. By forming, it can suppress that oxalic acid elutes into the liquid outside the biodegradable resin layer B.
The amount of the substance having affinity with the degradation product of the degradation accelerator contained in the biodegradable resin layer B can be appropriately set by those skilled in the art in consideration of the type and amount of the degradation accelerator. For example, 0.1 to 50% by weight, preferably 1.0 to 10% by weight. Further, the substance having affinity with the decomposed product may be subjected to surface treatment.

In the biodegradable resin laminate of the present invention, the biodegradable resin layer A and the biodegradable resin layer B are preferably disposed adjacent to each other, but as long as the effect of the present invention is obtained, the layer is between the layers A and B. Another layer (for example, an adhesive layer, a moisture barrier layer, an oxygen barrier layer, a carbon dioxide gas barrier layer, etc.) may be disposed. Further, the biodegradable resin layer B may be disposed on one side with respect to the biodegradable resin layer A, and, for example, as the biodegradable resin layer B1 and the biodegradable resin layer B2 on both sides, respectively. The same or different types of layers may be arranged.
For example, in the biodegradable container molded from the biodegradable resin laminate of the present invention as described later, the biodegradable resin layer B is disposed on the inner side of the container with respect to the biodegradable resin layer A. A preferable effect can be obtained.

  The thickness of the biodegradable resin layer A and the biodegradable resin layer B includes the arrangement of both layers, the types of biodegradable resins constituting the layers, the types of substances having affinity with the decomposition accelerator and its decomposition products, It can set suitably according to quantity etc., and there is no limitation in particular. For example, the thickness of the biodegradable resin layer A can be 50 to 500 μm, preferably 100 to 400 μm, more preferably 200 to 300 μm, for example 250 μm, and the thickness of the biodegradable resin layer B is 5 -50 μm, preferably 10-40 μm, more preferably 15-30 μm, for example 20 μm. Further, the ratio of the thicknesses of the layer A and the layer B is from 1: 1 to 100: 1, preferably from 5: 1 to 50: 1, more preferably from 10: 1 to 20: 1, for example, 12.5: 1. It can be.

The biodegradable resin laminate of the present invention can be formed into a molded body such as a biodegradable container by a known molding method.
For example, a multilayer film, a multilayer sheet, a multilayer parison, a multilayer pipe, or the like can be formed by performing extrusion molding using a multilayer multiple die using the number of extruders corresponding to the type of resin. In addition, a multilayer preform for bottle molding can be manufactured by co-injection molding such as a simultaneous injection method or a sequential injection method using the number of injection molding machines corresponding to the type of resin. By further processing such a multilayer film, parison, and preform, the biodegradable container of the present invention can be obtained. A similar container can be obtained by using compression molding.
Packaging materials such as films can be used as pouches in various forms and as lid materials for tray cups. Examples of the pouch include three- or four-side sealed flat pouches, gusseted pouches, standing pouches, pillow packaging bags, and the like. Bag making can be performed by a known bag making method. Further, by applying the film or sheet to means such as vacuum forming, pressure forming, bulging forming, plug assist forming, compression forming or cast forming, a packaging container such as a cup shape or a tray shape can be obtained.
Note that the biodegradable resin layer A and the biodegradable resin layer B may be formed into a molded body such as a container by molding a layered body in advance in consideration of the type, shape, molding method, and the like. You may obtain a molded object by making biodegradable resin layer A and biodegradable resin layer B into a laminated body in the process of a body.

For the production of a multilayer film or a multilayer sheet, an extrusion coating method or sandwich lamination can be used. Moreover, the single layer and multilayer film which were formed previously can also be laminated | stacked by dry lamination. For example, two layers of polylactic acid / polyglycolic acid laminated by dry lamination, laminating a transparent vapor deposition biodegradable film by dry lamination to a two-layer coextruded film comprising an easily decomposable resin composition / polylactic acid (sealant) layer Examples of the method include, but are not limited to, a method in which two layers of an easily decomposable resin composition / polylactic acid (sealant) are extrusion-coated on a film via an anchor agent.
Moreover, a parison, a pipe, or a preform is pinched off by a pair of split molds, and a bottle or a tube can be easily formed by blowing a fluid into the inside. Moreover, after cooling a pipe and a preform, it is heated to a stretching temperature, stretched in the axial direction, and blow stretched in the circumferential direction by fluid pressure to obtain a stretch blow bottle or the like.

In the biodegradable container of the present invention, the biodegradable resin layer B is preferably disposed on the side that is the inside of the container with respect to the biodegradable resin layer A. The side that is the inner side of the container generally means the side of the surface that comes into contact with the object such as food or liquid that is put in or placed in the container, but is a concept that changes according to the shape of the container, etc. It should be determined as appropriate based on common general knowledge. By setting it as such arrangement | positioning, it becomes possible to suppress the elution of the decomposition promotion agent from the inner side of a container.
Examples of the present invention will be described below, but the present invention is not limited thereto.

(Materials used)
As PLA, 4032D (d-lactic acid 2%) manufactured by natureworks was used.
A PGA manufactured by kureha (Mw = 100000) was used.
PEOx used the following synthetic product.

(Synthesis of polyethylene oxalate (hereinafter abbreviated as “PEOx”))
A 1 L separable flask equipped with a mantle heater, a stirrer, a nitrogen inlet tube, and a condenser tube was charged with 354 g (3.0 mol) of dimethyl oxalate, 223.5 g (3.6 mol) of ethylene glycol, and 0.30 g of tetrabutyl titanate under a nitrogen stream. While the methanol was distilled off from 110 º C, the internal temperature was heated to 170 ° C and reacted for 9 hours. Finally, 210 ml of methanol was distilled off. Thereafter, the mixture was stirred at an internal temperature of 150 ° C. under a reduced pressure of 0.1-0.5 mmHg for 1 hour, and reacted at an internal temperature of 170 ° C. to 190 ° C. for 7 hours. The solution viscosity (ηinh) of the composite was 0.12. The obtained PEOx had a melting point (mp) and a glass transition temperature (Tg) of mp 172 ° C. and Tg 25 ° C.
The solution viscosity (ηinh) was measured using a synthesized PEOx that was vacuum-dried overnight at 120 ° C., and this was mixed with m-chlorophenol / 1,2,4-trichlorobenzene = 4/1 (weight ratio) mixed solvent. It was immersed and dissolved at 150 ° C. for about 10 minutes to prepare a solution having a concentration of 0.4 g / dl, and then the solution viscosity was measured at 30 ° C. using an Ubbelohde viscometer. (Unit dl / g)

(Preparation of decomposition accelerator-containing PLA pellets)
Various materials were dry blended and melt-mixed using a twin screw extruder (ULT Nano05-20AG manufactured by Technobel) to produce master pellets of PLA / PEOx or PGA = 95/5 wt%. When PEOx was used as a decomposition accelerator, pellets were produced at a molding temperature of 200 ° C., and when PGA was used, 240 ° C.

(Preparation of biodegradable resin layer A)
The master pellet was melted and mixed using a twin screw extruder (ULT Nano05-20AG manufactured by Technobel), and a 190 to 270 μm thick sheet was formed using a lab plast mill (manufactured by Toyo Seiki Co., Ltd.). At that time, PEOx-containing PLA was formed at a molding temperature of 200 ° C., and PGA 5% -containing PLA was formed at a molding temperature of 240 ° C.

(Production of biodegradable resin layer B)
PLA was dissolved in 45 ml of chloroform, a substance having an affinity described later was added, and the mixed solution was poured into a Teflon (registered trademark) vat and allowed to stand for 1 day to prepare a cast film of 10 μm to 20 μm.

(Production of biodegradable resin laminate)
Cut the biodegradable resin layer A into 1 × 2 cm, sand with the biodegradable resin layer B, weld and laminate at 120 ° C., and cut the edges so that the biodegradable resin layer A is not exposed to obtain a test piece. It was. The thicknesses of the obtained test pieces were 190 to 270 μm for the biodegradable resin layer A and 10 μm to 20 μm for the biodegradable resin layer B.
(Acid dissolution test)
The obtained test piece was charged with 10 ml of pure water in a 25 ml vial, allowed to stand at 40 ° C., and the amount of acid eluted in the solution was measured by HPLC (high performance liquid chromatography).
The HPLC system was JASCO's GULLIVER series and analyzed under the following conditions. Using a column (Waters Atlantis dC ₁₈ 5 μm, 4.6 × 250 mm) in a column oven maintained at 40 ° C., apply a gradient with 0.5% phosphoric acid and methanol to a flow rate of 1 mL / min as shown in FIG. 50 μl of sample was injected as the mobile phase. For detection, UV absorption at 210 nm was used, and oxalic acid, glycolic acid or L-lactic acid (manufactured by Wako Pure Chemical Industries, Ltd.) was used as a standard sample.

(Degradability test)
48ml of CLE enzyme solution (Cryptococcus sp. S-2 lipase showing lipase activity of 653U / ml (Independent Administrative Institution Liquor Research Institute: JP 2004-73123)) added to 10ml of pH7 60mmol / l phosphate buffer Thus, a decomposition solution was prepared. The lipase activity was measured using paranitrophenyl laurate as a substrate. Here, 1 U of lipase activity is defined as the amount of enzyme when 1 μmol / min of paranitrophenol is released from paranitrophenyl laurate. The laminate prepared by the above method was placed in a 25 ml vial with 10 ml of the decomposition solution and shaken at a predetermined temperature (45 ° C., 100 rpm) for 4 days. In order to avoid an extreme decrease in pH, the decomposition solution was exchanged on the second day for 4 days. After 4 days, the test piece was taken out and dried overnight in a 45 ° C. oven, and the weight was measured. The decomposition rate of the test piece was determined by {(initial film weight) − (film weight after 4 days) / initial film weight)} × 100.

Example 1
A biodegradable resin layer A containing 5 wt% PEOx in PLA and a biodegradable resin layer B containing 10 wt% calcium carbonate (Wako Pure Chemical Industries, Ltd.) in PLA were prepared. Produced. The obtained laminate was subjected to the acid elution test and the decomposability test. In addition, the acid elution test was conducted every day and continued until the sixth day. The results are shown in FIGS.

(Example 2)
The same procedure as in Example 1 was performed except that the calcium carbonate content of the biodegradable resin layer B was 50 wt%. The results are shown in Table 1 and FIGS. The degradation rate in the degradability test was lower than that in Example 1, but this was because the biodegradable enzyme was converted into a biodegradable resin layer because the calcium carbonate content of the biodegradable resin layer B was increased. This is considered to be because the decomposition rate became slow due to difficulty in entering A.

(Comparative Example 1)
The same procedure as in Example 1 was performed except that the biodegradable resin layer B did not contain calcium carbonate. The results are shown in Table 1 and FIGS.

(Comparative Example 2)
The same operation as in Example 1 was performed except that the biodegradable resin layer B was not provided. The results are shown in Table 1 and FIGS.

(Example 3)
A biodegradable resin layer A containing 5 wt% PGA in PLA and a biodegradable resin layer B containing 10 wt% iron oxide (Wako Pure Chemical Industries, Ltd.) were produced to produce a biodegradable resin molded body. . The obtained laminate was subjected to the acid elution test. The acid elution test was conducted on the 2nd, 7th and 14th, respectively. The results are shown in Table 2 and FIG.

(Comparative Example 3)
The same operation as in Example 3 was conducted except that calcium carbonate was not contained. The results are shown in Table 2 and FIG.

（ｐｐｍ）

（ｐｐｍ） (Comparative Example 4)
The same procedure as in Example 3 was performed except that the biodegradable resin layer B was not provided. The results are shown in Table 2 and FIG.

(Ppm)

(Ppm)

Claims (9)

Biodegradable molded from a biodegradable resin laminate having a biodegradable resin layer A containing a decomposition accelerator and a biodegradable resin layer B containing a substance having an affinity for the decomposition product of the decomposition accelerator A biodegradable container, wherein the biodegradable resin layer B is disposed on the inner side of the container with respect to the biodegradable resin layer A. Decomposition accelerating agent releases an acid by hydrolysis, the biodegradable container of claim 1, wherein. The biodegradable container according to claim 1 or 2 , wherein the degradation accelerator is polyoxalate and / or polyglycolic acid. A biodegradable multilayer film comprising a biodegradable resin layer A containing a degradation accelerator and a biodegradable resin layer B containing a substance having an affinity for a degradation product of the degradation accelerator , A biodegradable multilayer film, characterized in that a biodegradable resin layer B is disposed on the side of the surface in contact with the object . The biodegradable multilayer film according to claim 4, wherein the degradation accelerator releases an acid by hydrolysis . The biodegradable multilayer film according to claim 4 or 5, wherein the degradation accelerator is polyoxalate and / or polyglycolic acid . A biodegradable resin layer A comprising a biodegradable resin layer A containing a decomposition accelerator and biodegradable resin layers B1 and B2 containing a substance having an affinity for a decomposition product of the decomposition accelerator, A biodegradable resin laminate comprising a biodegradable resin layer B1 on one side and a biodegradable resin layer B2 on the other side of the biodegradable resin layer A. The biodegradable resin laminate according to claim 7, wherein the decomposition accelerator releases an acid by hydrolysis. The biodegradable resin laminate according to claim 7 or 8, wherein the degradation accelerator is polyoxalate and / or polyglycolic acid.

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