Laminate and method for manufacturing a laminate

Abstract

To provide a laminate which has biodegradability and sufficiently suppresses thermal deformation.SOLUTION: A laminate 100 includes a resin film 10 containing a first biodegradable resin, and resin layers 20 and 30 which are provided on both surfaces 11 and 13 of the resin film 10 and contain a second biodegradable resin, wherein the first biodegradable resin is a biodegradable resin other than cellulose acetate, and the second biodegradable resin is the cellulose acetate.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a laminate. Background Art

[0002] In recent years, biodegradable resins have been researched to reduce the environmental impact associated with the treatment of plastic waste. Biodegradable resins have the property of being ultimately decomposed into carbon dioxide and water by the action of microorganisms and circulated into the natural environment.

[0003] For example, Patent Document 1 describes a biodegradable laminated film in which a biodegradable resin layer (1) is laminated with a biodegradable resin layer (2) of a type different from the biodegradable resin layer (1), and the total number of layers is 2 or more. Further, Patent Document 2 describes a biodegradable laminate obtained by laminating a resin layer on one or both surfaces of a paper base material. The resin layer is represented by formula (A): [-CHR-CH2-CO-O-] (wherein R is C n H 2n+1 which is an alkyl group represented by, and n is an integer of 1 or more and 15 or less. ), contains 100 parts by weight of a polyhydroxyalkanoate containing a repeating unit represented by, and 1 to 20 parts by weight of (B) a glycerin ester compound. Prior Art Documents Patent Documents

[0004] Patent Document 1 Japanese Unexamined Patent Publication No. 2000-238194 Patent Document 2 International Publication No. WO 2019 / 239913 Summary of the Invention Problem to be Solved by the Invention

[0005] However, the biodegradable laminated film described in Patent Document 1 has a problem in that thermal deformation cannot be sufficiently suppressed. Also, the biodegradable laminate described in Patent Document 2 has a problem in that thermal deformation cannot be sufficiently suppressed.

[0006] The object of the present invention is to provide a laminate that is biodegradable and has sufficiently suppressed thermal deformation. [Means for solving the problem]

[0007] [1] A resin film containing a first biodegradable resin, A resin layer containing a second biodegradable resin is provided on both sides of the aforementioned resin film, Equipped with, The first biodegradable resin is a biodegradable resin other than cellulose acetate, The second biodegradable resin is cellulose acetate. Laminated structure.

[0008] [2] In the laminate described in [1], The thickness of the aforementioned resin layer is 2 μm or more and 20 μm or less. Laminated structure.

[0009] [3] In the laminate described in [1] or [2], The degree of acetic acidization of the cellulose acetate is 50% or more and 62% or less. Laminated structure.

[0010] [4] In the laminate described in any of [1] to [3], The total degree of acetyl group substitution of the cellulose acetate is 2.3 or more and 2.6 or less. Laminated structure.

[0011] [5] In the laminate described in any of [1] to [4], The resin layer is a resin layer obtained by coating with a coating solution in which the cellulose acetate is dissolved in an organic solvent. Laminated structure.

[0012] In the laminate described in any of [1] to [5], Said first biodegradable resin is at least one biodegradable resin selected from the group consisting of polylactic acid, polybutylene succinate, polybutylene succinate adipate, polybutylene adipate terephthalate, polyethylene terephthalate succinate, polyglycolic acid, and poly(3-hydroxybutyrate-co-3-hydroxyhexanoate), A laminate. Effects of the Invention

[0013] According to one aspect of the present invention, a laminate having biodegradability and sufficiently suppressed thermal deformation can be provided. Brief Description of the Drawings

[0014] [Figure 1] 1 is a schematic cross-sectional view schematically illustrating an example of the laminate according to the present embodiment. Mode for Carrying Out the Invention

[0015] Hereinafter, preferred embodiments of the laminate that is an example of the present invention will be described.

[0016] The laminate according to the present embodiment comprises: a resin film containing a first biodegradable resin; and resin layers containing a second biodegradable resin provided on both surfaces of the resin film. The first biodegradable resin is a biodegradable resin other than cellulose acetate, and the second biodegradable resin is said cellulose acetate.

[0017] The laminate according to the present embodiment, having the above configuration, achieves the properties of being biodegradable and having sufficiently suppressed thermal deformation. Although the reason for this is not clear, the present inventors infer that since cellulose acetate has higher heat resistance than biodegradable resins other than cellulose acetate, the above-described laminate with sufficiently suppressed thermal deformation can be obtained. In addition, it is preferable that the laminate according to this embodiment exhibits suppressed thermal deformation at temperatures of 130°C or higher, more preferably at temperatures of 150°C or higher, and particularly preferably at temperatures of 170°C or higher. Thermal deformation can be evaluated, for example, by preparing a 15 mm wide strip-shaped sample, placing it in a constant temperature bath heated to a predetermined temperature (130°C, 150°C, and 170°C) for 3 minutes, and then checking for any deformation of the sample.

[0018] The laminate according to this embodiment will be described with reference to the drawings. The laminate 100 shown in Figure 1 comprises a resin film 10 and resin layers 20 and 30 provided on both surfaces of the resin film 10 (the first main surface 11 of the resin film 10 and the second main surface 13 of the resin film 10). The resin layer 30, the resin film 10, and the resin layer 20 are sequentially laminated in this order, from the resin layer 30 toward the resin layer 20. The resin layers 20 and 30 contain cellulose acetate. In the laminate 100, heat resistance is provided to the first main surface 11 and the second main surface 13 of the resin film 10 on which the resin layers 20 and 30 are provided. Here, the main surface refers to the largest surface of the resin film or resin layer, and represents the surface facing the thickness direction (i.e., the lamination direction of each layer).

[0019] An example of a laminate according to this embodiment has been described above with reference to Figure 1, but the laminate according to this embodiment is not limited thereto. The laminate according to this embodiment can take various forms as long as it has the above configuration.

[0020] (Resin film) The resin film is a film containing a first biodegradable resin. Furthermore, it is preferable that the resin film is capable of supporting the resin layer described later. The type of biodegradable resin is not particularly limited as long as it includes a biodegradable resin other than cellulose acetate. The biodegradable resin other than cellulose acetate is preferably at least one biodegradable resin selected from the group consisting of polylactic acid, polybutylene succinate, polybutylene succinate adipate, polybutylene adipate terephthalate, polyethylene terephthalate succinate, polyglycolic acid, and poly(3-hydroxybutyrate-co-3-hydroxyhexanoate). Among these, the biodegradable resin other than cellulose acetate is preferably one or more of polylactic acid, polybutylene succinate, polybutylene succinate adipate, and polybutylene adipate terephthalate, and more preferably one or more of polybutylene succinate adipate and polybutylene adipate terephthalate.

[0021] The thickness of the resin film is not particularly limited, but is preferably 5 μm or more, and more preferably 10 μm or more. The thickness of the resin film is preferably 300 μm or less, and more preferably 200 μm or less.

[0022] (Resin layer) The resin layer contains cellulose acetate. Preferably, the resin layer contains only cellulose acetate.

[0023] From the viewpoint of heat resistance of the laminate, the thickness of the resin layer is preferably 2 μm or more, more preferably 3 μm or more, even more preferably 4 μm or more, and particularly preferably 5 μm or more. On the other hand, from the viewpoint of preventing the laminate from becoming too hard and resulting in insufficient bending strength, the thickness of the resin layer is preferably 20 μm or less, more preferably 16 μm or less, even more preferably 12 μm or less, and particularly preferably 10 μm or less.

[0024] From the viewpoint of easily obtaining biodegradability, cellulose acetate is preferably of a degree of acetic acid of 50% or more, and more preferably of 52% or more. Cellulose acetate may also have a degree of acetic acid of 53% or more, or 54% or more. From the viewpoint of easily obtaining biodegradability, cellulose acetate is preferably of a degree of acetic acid of 62% or less.

[0025] The degree of acetic acidity of cellulose acetate can be measured in accordance with the measurement method for the degree of acetic acidity of ASTM D-817-91 (Test method for cellulose acetate, etc.).

[0026] The total degree of acetyl group substitution in cellulose acetate is preferably 2.3 or higher, and more preferably 2.4 or higher, from the viewpoint of easily obtaining biodegradability. The total degree of acetyl group substitution in cellulose acetate is preferably 2.6 or lower, and more preferably 2.5 or lower, from the viewpoint of easily obtaining biodegradability.

[0027] The total degree of acetyl group substitution in cellulose acetate can be determined by converting the degree of acetic acidization of cellulose acetate using the following formula (F1). DS=162.14×AV / (6005.2-AV×42.037)...(F1) In formula (F1), DS represents the total degree of acetyl group substitution, and AV represents the degree of acetic acid (%).

[0028] Furthermore, it is preferable that the cellulose acetate has a 6% viscosity (viscosity when diluted to 6%) at 25±1℃ of 50 mPa·s or more and 200 mPa·s or less. For example, the 6% viscosity can be determined by using a 6 wt / vol% solution obtained by dissolving 3 g of the dried sample in 39.9 g of a 95% acetone aqueous solution. Cellulose acetate preferably has a melting point of 230°C or higher and 300°C or lower. The viscosity of a solution containing cellulose acetate can be measured according to the method specified in, for example, JIS K7117-1:1999. The melting point of cellulose acetate can also be measured according to the method specified in, for example, JIS K7121-1987.

[0029] The resin layer may be (i) a resin layer formed by melt extrusion of cellulose acetate, or (ii) a resin layer coated with a coating solution in which cellulose acetate is dissolved in an organic solvent. From the viewpoint of ease of formation and adhesion of the resin layer, it is preferable that the resin layer is a resin layer coated with a coating solution in which cellulose acetate is dissolved in an organic solvent.

[0030] In addition to cellulose acetate, the resin layer may also contain other components as needed, such as additives (e.g., plasticizers), as long as they do not impair the effects of this embodiment.

[0031] (Method of manufacturing a laminate) Next, a method for manufacturing the laminate according to this embodiment will be described. The laminate according to this embodiment can be suitably manufactured, for example, by the following method. In other words, the laminate according to this embodiment can be manufactured by a method comprising the step of coating a resin film with a coating solution in which cellulose acetate is dissolved in an organic solvent to form a resin layer. Here, the resin layer is provided on both sides of the resin film, but (i) a resin layer may be formed on one side of the resin film and then on the other side, or (ii) a resin layer may be formed on both sides of the resin film simultaneously.

[0032] As the resin film, the aforementioned resin film may be used. In the process of forming this resin layer, various surface treatments such as heating or corona discharge treatment may be applied to improve adhesion with the resin film. In the process of forming this resin layer, the resin layer is formed by coating the resin layer-forming composition onto the resin film with a coating solution and then drying it.

[0033] The viscosity of the coating solution for the resin layer-forming composition at 25°C is preferably between 20 mPa·s and 2000 mPa·s. If the viscosity is within this range, it becomes easier to form a suitable resin layer using the coating solution. This viscosity can be measured, for example, in accordance with the method specified in JIS K7117-1:1999.

[0034] The organic solvent used to dissolve cellulose acetate is not particularly limited and includes, for example, ketones (acetone, cyclohexanone, and methyl ethyl ketone (MEK), etc.), ethers (diethyl ether, ethylene glycol monomethyl ether, and propylene glycol monomethyl ether, etc.), amides (dimethylformamide, etc.), and esters (ethyl acetate, butyl acetate, etc.). These organic solvents may be used individually or in combination of two or more. Among these organic solvents, at least one selected from the group consisting of ethyl methyl ketone, dimethylformamide, and cyclohexanone is preferred from the viewpoint of ease of dissolving cellulose acetate.

[0035] Methods for coating a resin film with a coating solution of a resin layer-forming composition include, for example, bar coating, knife coating, roll knife coating, roll coating, blade coating, die coating, curtain coating, and gravure coating. The amount of coating solution of the resin layer-forming composition is preferably such that the thickness of the resin layer after drying is in the range of 2 μm or more and 20 μm or less. When the resin layer is made only of cellulose acetate, the amount of coating solution of the resin layer-forming composition is not particularly limited, for example, 3 g / m². 2 More than 30g / m 2 The following are some examples:

[0036] By following the above steps, the laminate according to this embodiment can be obtained.

[0037] (Applications of laminates) The laminate according to this embodiment is biodegradable and exhibits sufficiently suppressed thermal deformation. Therefore, the laminate according to this embodiment can be suitably used in applications such as heat-resistant containers, packaging materials, carriers for casting films, and protective films, all of which have a low environmental impact.

[0038] The present invention is not limited to the embodiments described above. The present invention may include modifications and improvements to the extent that they can achieve the objectives of the present invention. [Examples]

[0039] Examples are described below, but the present invention is not limited in any way to these examples.

[0040] The following raw materials were prepared to produce the laminates of each example and each comparative example.

[0041] (Resin film) PBS-1: Polybutylene succinate film (Mitsubishi Chemical Corporation, DM9B01, 100 μm thick) PBS-2: Polybutylene succinate film (Mitsubishi Chemical Corporation ZM9B02, 100 μm thick) PLA-1: Polylactic acid film (Terramac TE-2000 manufactured by Unitika, 100 μm thick) PBAT-1: Polybutylene adipate terephthalate film (BASF Ecoflex C1200, 100 μm thick) PP-1: Polypropylene film (Sun Allomer Co., Ltd. PHA03A, 100 μm thick)

[0042] (Cellulose acetate) CA-1: Cellulose acetate with a degree of acetate 55% (total degree of acetyl group substitution 2.4) (manufactured by Daicel Corporation, L-20)

[0043] <Example 1> On one side (front) of PBS-1, a coating solution of a resin layer-forming composition prepared by dissolving cellulose acetate in methyl ethyl ketone (viscosity 1200 mPa·s at 25°C) was coated using an applicator, and then dried at 120°C for 1 minute to form a resin layer with a thickness of 5 μm. Subsequently, on the other side (back) of the PBS-1 with the resin layer formed, the coating solution (viscosity 1200 mPa·s at 25°C) was coated using an applicator, and then dried at 120°C for 1 minute to form a resin layer with a thickness of 5 μm, thereby obtaining the laminate of Example 1.

[0044] <Examples 2-6> A laminate was obtained in the same manner as in Example 1, except that the type of resin film, the thickness of the resin layer, and the presence or absence of a resin layer were changed as shown in Table 1. <Comparative Examples 1-4> A resin film or laminate was obtained in the same manner as in Example 1, except that the type of resin film, the thickness of the resin layer, and the presence or absence of a resin layer were changed as shown in Table 1.

[0045] [Evaluation of thermal deformation] From the laminates or resin films obtained in each of the above examples, strip-shaped samples with a width of 15 mm were cut out. These samples were then left to stand for 3 minutes in a constant temperature bath heated to a predetermined temperature (130°C, 150°C, and 170°C), and the presence or absence of thermal deformation (thermal shrinkage) of these samples was evaluated based on the evaluation criteria described below.

[0046] (Evaluation Criteria) A: No thermal deformation F: Heat deformation present

[0047] [Table 1]

[0048] Based on the above results, it can be seen that the laminate of the example in which a resin layer containing cellulose acetate is provided on both sides can suppress thermal deformation more effectively than the resin film or laminate of the comparative example in which such a resin layer is not provided. [Explanation of symbols]

[0049] 10... Resin film, 11... First main surface (first main surface of the resin film), 13... Second main surface (second main surface of the resin film), 20... Resin layer, 30... Resin layer, 100... Laminate.

Claims

1. A resin film containing a first biodegradable resin, A resin layer containing a second biodegradable resin is provided on both sides of the aforementioned resin film, Equipped with, The first biodegradable resin is a biodegradable resin other than cellulose acetate, The second biodegradable resin is cellulose acetate, The first biodegradable resin is at least one biodegradable resin selected from the group consisting of polylactic acid, polybutylene succinate, polybutylene succinate adipate, polybutylene adipate terephthalate, polyethylene terephthalate succinate, polyglycolic acid, and poly(3-hydroxybutyrate-co-3-hydroxyhexanoate). The total degree of acetyl group substitution of the cellulose acetate is 2.4 or more and 2.6 or less. Laminated structure.

2. In the laminate according to claim 1, The thickness of the aforementioned resin layer is 2 μm or more and 20 μm or less. Laminated structure.

3. In the laminate according to claim 1 or claim 2, The degree of acetic acidization of the cellulose acetate is 50% or more and 62% or less. Laminated structure.

4. A method for manufacturing a laminate according to claim 1 or claim 2, The process includes a step of coating the resin layer with a coating solution in which the cellulose acetate is dissolved in an organic solvent. A method for manufacturing laminates.

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