JP5144921B2 - Biodegradable multilayer sheet - Google Patents

Description

The present invention relates to a multilayer sheet comprising a biodegradable resin layer made of a biodegradable resin.

Since most of the commonly used synthetic resins are not decomposed in the natural environment, disposal of plastic product waste that is discarded after use is a major problem. Therefore, biodegradable resins that can be easily decomposed in a natural environment have attracted attention.
Among the biodegradable resins, polylactic acid (PLA) is the most widely used, but it has a biodegradable function and excellent transparency, while this resin is hard and inferior in heat resistance, impact resistance, and chemical resistance. For example, there are parts that are problematic when handled as plastic products. Therefore, various attempts have been made to maintain the characteristics as a plastic product by combining with a polyolefin resin excellent in heat resistance, impact resistance and chemical resistance.
For example, Patent Document 1 describes a technique in which an inner layer of a container is formed of a polyolefin resin, an outer layer is formed of a biodegradable resin, and an intermediate layer as an adhesive is provided between the inner layer and the outer layer as necessary. ing.
Patent Document 2 describes a multilayer sheet in which an inner layer and an outer layer contain 50% or more of a polyolefin resin, and an intermediate layer contains 50% or more of a biodegradable resin.

JP 2001-225430 A JP 2006-88541 A

  However, in Patent Document 1 and Patent Document 2, an intermediate layer as an adhesive is provided between the polyolefin layer and the biodegradable resin layer as necessary, but the adhesive strength is weak. When such a multilayer sheet is subjected to thermoforming or ruled lines, there has been a problem of delamination.

An object of the present invention is excellent in adhesion between layers, to provide biodegradable functionality and transparency, more flexibility, impact resistance, a biodegradable multilayer sheet having both heat resistance and chemical resistance It is.

The biodegradable multilayer sheet of the present invention is a biodegradable multilayer sheet including at least a thermoplastic resin layer, an adhesive layer, and a biodegradable resin layer, and the adhesive layer includes a thermoplastic resin layer, a biodegradable resin layer, and the like. A plurality of layers including a first adhesive layer adjacent to the thermoplastic resin layer, and a second adhesive layer adjacent to the first adhesive layer and the biodegradable resin layer. is formed, said first adhesive layer is a layer having adhesiveness with the thermoplastic resin layer comprises an acid-modified polyolefin down, the second adhesive layer, adhesiveness with the biodegradable resin layer a layer having a alloy layer containing a thermoplastic resin and a biodegradable resin and a dispersant, wherein the dispersant is seen containing an acid-modified polyolefin down, the mixing ratio of the dispersant in the alloy layer , this is in the range of 30% to 90% relative to the total alloy layer The features.

That is, this invention is a multilayer sheet which consists of at least 4 layers laminated | stacked in order of the thermoplastic resin layer, the 1st contact bonding layer, the 2nd contact bonding layer, and the biodegradable resin layer.
According to this invention, the adhesive layer is formed of two layers of the first adhesive layer and the second adhesive layer, and the first adhesive layer is formed of a material having good adhesiveness with the thermoplastic resin layer, The second adhesive layer was formed of a material having good adhesiveness with the biodegradable resin layer.
Accordingly, the adhesion between the layers is improved, so that the layers are not peeled when thermoformed or ruled lines are inserted.

Since the second adhesive layer in contact with the biodegradable resin layer is an alloy layer containing a thermoplastic resin, a biodegradable resin, and a dispersant , the adhesion between the biodegradable resin layer and the second adhesive layer Property is improved.

Furthermore , it can be set as an alloy layer with favorable adhesiveness by mix | blending a dispersing agent in the ratio of 30 to 90%. If the proportion of the dispersant is less than 30%, the thermoplastic resin and the biodegradable resin cannot be sufficiently dispersed due to a shortage of the dispersant, resulting in uneven adhesion. On the other hand, when the proportion of the dispersant exceeds 90%, the thermoplastic resin and the biodegradable resin are insufficient, resulting in poor adhesion.

In the biodegradable multilayer sheet of the present invention, the adhesive strength between the thermoplastic resin layer and the biodegradable resin layer is preferably 3 N / 25 mm width or more.
According to this invention, since the adhesive strength between the thermoplastic resin layer and the biodegradable resin layer is 3N / 25 mm or more according to the measurement method of “JIS 7113”, the adhesive strength is sufficient. Yes. Therefore, even if thermoforming or ruled lines are inserted, delamination does not occur between the thermoplastic resin layer and the biodegradable resin layer.

The biodegradable multilayer sheet of the present invention preferably contains 25% by mass or more of the biodegradable resin.
The standard of 25% by mass of biodegradable resin is the minimum ratio for obtaining certification based on the “Biomass Plastic Identification and Labeling System” of the Biodegradable Plastics Study Group (BPS). Therefore, if the ratio of the biodegradable resin is less than 25% by mass of the entire biodegradable multilayer sheet, this certification cannot be obtained.

In the biodegradable multilayer sheet of the present invention, the biodegradable resin used in the biodegradable resin layer is preferably a plant-derived resin.
According to this invention, since the biodegradable resin is derived from a plant, it is possible to continuously supply raw materials by regenerating the plant.

In the biodegradable multilayer sheet of the present invention, the biodegradable resin is preferably polylactic acid.
According to this invention, since polylactic acid is made from starch such as corn and potato, the calorific value at the time of combustion is low and no harmful substances are produced. Moreover, since it is biodegraded in the natural environment, an environmentally friendly product can be provided. Moreover, since polylactic acid is excellent in transparency, a product having transparency can be provided.

The method for producing a biodegradable multilayer sheet according to the present invention comprises the steps of co-extrusion of the thermoplastic resin layer, the biodegradable resin layer, the first adhesive layer, and the second adhesive layer. It is characterized by manufacturing.
According to this invention, since the biodegradable multilayer sheet can be produced in one step by coextrusion, it does not take time and effort and is economical.

The molded article of the present invention is characterized by being molded from the aforementioned biodegradable multilayer sheet.
According to this invention, since the biodegradable multilayer sheet having the above-described effects is used, a molded product can be produced without peeling between the layers even when thermoformed or ruled lines are inserted. Can do.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view of a biodegradable multilayer sheet according to an embodiment of the present invention.
In FIG. 1, it consists of a thermoplastic resin layer 1, an adhesive layer 2 comprising a first adhesive layer 21 and a second adhesive layer 22, a biodegradable resin layer 3, a second adhesive layer 42 and a first adhesive layer 41. The adhesive layer 4 and the thermoplastic resin layer 5 are laminated in this order.

  Examples of the material used for the thermoplastic resin layer 1 include polyolefin and polyethylene terephthalate (PET). Examples of polyolefins include polypropylene resins (PP) such as homopolypropylene (HPP), block polypropylene (BPP), and random polypropylene (RPP), low density polyethylene (LDPE), high density polyethylene (HDPE), and linear low density polyethylene. There are polyethylene resins (PE) such as (L-LDPE). In addition, thermoplastic resins such as polystyrene resins such as general-purpose polystyrene (GPPS) and impact-resistant polystyrene (HIPS) can be used. These resins can be used alone or in combination, and elastomers can also be used in combination as necessary.

  The first adhesive layers 21 and 41 that are in contact with the thermoplastic resin layer 1 or 5 may be formed of the same resin, may be formed of different resins, and have good adhesion to the thermoplastic resin. There is no particular limitation. For example, acid-modified polyolefin, functional polyolefin, functional elastomer and the like can be mentioned. Specifically, Admer (Mitsui Chemicals, registered trademark) can be used as the functional polyolefin.

  As the second adhesive layers 22 and 42 in contact with the biodegradable resin layer 3, an alloy layer having good adhesiveness with the biodegradable resin is used. The alloy layer includes a thermoplastic resin, a biodegradable resin, and a dispersant. The same thermoplastic resin as that used in the thermoplastic resin layer can be used, and the biodegradable resin is a biodegradable resin layer. The same one used can be used. Moreover, as a dispersing agent, you may use an adhesive agent and can use the adhesive agent used for the 1st contact bonding layer. The blending ratio of the dispersant is preferably in the range of 30 to 90% with respect to the entire alloy layer.

  The biodegradable resin layer 3 is preferably a plant-derived biodegradable resin, and examples thereof include polylactic acid, polybutylene succinate, polybutylene succinate adipate, and the like. Of these, it is particularly preferable to use polylactic acid (PLA).

A biodegradable multilayer sheet made of such a material is formed by a coextrusion molding method using a T die. That is, four hoppers corresponding to each resin and four extruders corresponding to each layer are used, and the resin extruded from each extruder is introduced into a feed block type or multi-manifold type T-die to perform coextrusion molding. May be.
The biodegradable multilayer sheet molded in this manner has a form in which both surfaces of the biodegradable resin layer 3 are sandwiched between the thermoplastic resin layers 1 and 5 via the adhesive layers 2 and 4.
Then, a molded product such as a clear holder or a packaging bag can be produced by subjecting this biodegradable multilayer sheet to processing such as thermoforming or ruled lines.

According to the embodiment described above, the following operational effects can be obtained.
(1) Between the thermoplastic resin layers 1 and 5 and the biodegradable resin layer 3, each of the layers in contact with each other and the first adhesive layer and the second adhesive layer formed of a material having good adhesiveness Adhesive layer consisting of two layers improves adhesion between each layer, clearing without peeling between each layer even when thermoforming or ruled lines are inserted when forming a biodegradable multilayer sheet A molded product such as a holder can be manufactured.
Therefore, the frequency of occurrence of defective products or the like in the manufacturing process can be greatly reduced, efficiency is increased, and waste of materials and the like can be suppressed, thereby reducing costs.

(2) Since the thermoplastic resin layer of the biodegradable multilayer sheet is formed from a material such as polyolefin, it has impact resistance and heat resistance.
Moreover, in this embodiment, since the surface which touches the exterior is made into the thermoplastic resin layers 1 and 5, the product excellent in chemical resistance can be provided. Furthermore, since the conventional printing technology for thermoplastic resins can be used as it is, it is economical.

(3) Since the biodegradable resin layer 3 of the biodegradable multilayer sheet is made of polylactic acid, it can provide excellent transparency and biodegradability.
In addition, polylactic acid derived from plants is environmentally friendly because it generates a low amount of heat during combustion and does not produce harmful substances. Furthermore, since corn, which is a raw material for polylactic acid, is a recyclable resource, it is possible to supply the raw material continuously.

(4) Therefore, according to (2) and (3), a biodegradable multilayer sheet having an environmentally friendly biodegradation function while having impact resistance, heat resistance and chemical resistance, which are functions as a plastic, is provided. can do.

(5) Since the biodegradable multilayer sheet can be produced in one step by co-extrusion, it does not take time and can reduce the cost.

It should be noted that the present invention is not limited to the above-described embodiment, and it goes without saying that modifications and improvements within the scope of achieving the objects and effects of the present invention are included in the contents of the present invention. Nor.
For example, in the present invention, an adhesive layer composed of two layers of a first adhesive layer and a second adhesive layer is provided, but a third adhesive layer is provided between the first adhesive layer and the second adhesive layer. You can also.

EXAMPLES The present invention will be described more specifically with reference to examples and comparative examples, but the present invention is not limited to the contents of examples and the like.
The following multilayer sheets of Example 1 and Comparative Examples 1 and 2 were produced by coextrusion, and a clear box was created with ruled lines. “AD” in the text is an adhesive layer.

[Example 1]
The layer structure of the multilayer sheet is shown below.
PP (polypropylene) / AD1 / AD2 / PLA (polylactic acid) / AD2 / AD1 / PP
The raw materials used for each layer are as follows.
PP: Prime Polymer Pro Primer 233GV
AD1: Made by Mitsui Chemicals Admer SF730
AD2: Mixture of (233GV: SF730: 3032DK = 35%: 30%: 35%) PLA: Terramac 4032DK manufactured by Unitika

[Example 2]
The layer structure of the multilayer sheet is shown below.
PP / AD1 / AD2 / PLA / AD2 / AD1 / PP
The raw materials used for each layer are as follows.
PP: Prime Polymer Pro Primer 233GV
AD1: Made by Mitsui Chemicals Admer SF730
AD2: Mixture of (233GV: SF730: 3032DK = 20%: 50%: 30%) PLA: Terramac 4032DK manufactured by Unitika

[Example 3]
The layer structure of the multilayer sheet is shown below.
PET / AD1 / AD2 / PLA / AD2 / AD1 / PET
The raw materials used for each layer are as follows.
PET: Easter CopolyEster PET-G 6763
AD1: Modic F534A manufactured by Mitsubishi Chemical
AD2: (PETG 6763: F534A: 4032DK = 35%: 30%: 35%) PLA PLA: Unitika Terramac 4032DK

[Comparative Example 1]
The layer structure of the multilayer sheet is shown below.
PP / AD / PLA / AD / PP
The raw materials used for each layer are as follows.
PP: Prime Polymer Pro Primer 233GV
AD: Made by Mitsui Chemicals Admer SF730
PLA: Terramac 4032DK manufactured by Unitika

[Comparative Example 2]
The layer structure of the multilayer sheet is shown below.
PP / AD / PLA / AD / PP
The raw materials used for each layer are as follows.
PP: Prime Polymer Pro Primer 233GV
AD: (233GV: SF730: 4032DK = 35%: 30%: 35%) PLA: PLATIMAC 4032DK manufactured by Unitika

<Evaluation>
The adhesive strength of the multilayer sheets produced in Examples 1 to 3, Comparative Example 1 and Comparative Example 2 and the adhesion state when ruled lines were entered were evaluated and are shown in Table 1.
(Measurement method of adhesive strength)
Table 1 shows the strength measured in accordance with “JIS 7113” and peeled off at the weakest part of the multilayer sheet.
(Evaluation method with ruled lines)
Using PW-865, Sakamoto Machine Co., Ltd., a ruled line was put at a depth of 0.15 mm in the sheet, and the cross section was observed with a microscope (KEYENCE VH-Z100) to confirm whether it was peeled off.

In Examples 1 to 3, a good adhesive strength of 3 N / 25 mm width or greater was obtained, and no delamination occurred between the layers even when ruled lines were inserted.
In Comparative Example 1, since an adhesive polyolefin (Admer SF730) is used for the AD layer, the adhesiveness to the PP layer is good, but the adhesiveness to the PLA layer is poor, and when the ruled line is put, the AD layer And the PLA layer were delaminated.
In Comparative Example 2, since the AD layer is an alloy layer, the adhesion to the PLA layer is good, but the adhesion to the PP layer is poor, and the delamination between the AD layer and the PP layer when ruled lines are made did.

  The present invention can be used for containers for cosmetics, medicines, foods and the like.

Sectional drawing of the multilayer sheet in embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 5 ... Thermoplastic resin layer 2, 4 ... Adhesion layer 3 ... Biodegradable resin layer

Claims (5)

In a biodegradable multilayer sheet including at least a thermoplastic resin layer, an adhesive layer, and a biodegradable resin layer,
The adhesive layer is provided between the thermoplastic resin layer and the biodegradable resin layer,
A first adhesive layer adjacent to the thermoplastic resin layer;
Formed of a plurality of layers including a first adhesive layer and a second adhesive layer adjacent to the biodegradable resin layer;
It said first adhesive layer is a layer having adhesiveness with the thermoplastic resin layer comprises an acid-modified polyolefin down,
The second adhesive layer is a layer having adhesiveness with the biodegradable resin layer, and is an alloy layer containing a thermoplastic resin, a biodegradable resin and a dispersant,
The dispersing agent comprises an acid-modified polyolefin down,
The biodegradable multilayer sheet, wherein the blending ratio of the dispersant in the alloy layer is in the range of 30 to 90% with respect to the entire alloy layer . The biodegradable multilayer sheet according to claim 1 ,
A biodegradable multilayer sheet, wherein an adhesive strength between the thermoplastic resin layer and the biodegradable resin layer is 3 N / 25 mm or more. In the biodegradable multilayer sheet according to claim 1 or 2 ,
A biodegradable multilayer sheet comprising 25% by mass or more of the biodegradable resin. In the biodegradable multilayer sheet according to any one of claims 1 to 3 ,
A biodegradable multilayer sheet, wherein the biodegradable resin used in the biodegradable resin layer is a plant-derived resin. In the biodegradable multilayer sheet according to any one of claims 1 to 4 ,
The biodegradable multilayer sheet, wherein the biodegradable resin is polylactic acid.

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