Laminate and manufacturing method thereof

Abstract

To provide a laminate with consideration for environmental load and easy to obtain desired characteristics.SOLUTION: A sheet-like or tabular laminate includes: at least one layer of A layer containing a polyethylene-based resin A as a base resin having a biomass degree measured in accordance with ASTM D 6866 of 40% or over and at least one layer of B layer containing a polyethylene-based resin B as a base resin having a biomass degree measured in accordance with ASTM D 6866 of 20% or under, wherein at least one layer among A layer or B layer is a foamed layer, a thickness of the laminate is 2 mm or over, a density of the laminate is 10 kg / m3 or over and 300 kg / m3 or under, and a biomass degree of the laminate measured in accordance with ASTM D 6866 of 5% or over.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a laminate and a method for manufacturing the same.

Background Art

[0002] Since the polyethylene-based resin foam is a material having excellent cushioning properties, it is used in various fields as a cushioning material for logistics such as interleaving paper for flat plates and packaging materials.

[0003] The polyethylene-based resin foam is manufactured, for example, by the following extrusion foaming method. A polyethylene-based resin is supplied to an extruder together with a foam regulator or the like, heated and kneaded to form a resin melt, a physical foaming agent is injected into the resin melt, kneaded to form a foaming resin melt, and the foaming resin melt is extruded from the inside of the extruder under atmospheric pressure to be foamed.

[0004] The polyethylene-based resin foam is usually manufactured using petroleum-derived polyethylene produced from fossil fuel resources. In recent years, however, concerns have been raised about global warming due to an increase in the amount of carbon dioxide in the atmosphere and the depletion of fossil fuel resources. Therefore, the development of a polyethylene-based resin foam that does not overly depend on petroleum-derived polyethylene is desired.

[0005] For example, Patent Document 1 discloses a foam containing 50% by mass or more and 100% by mass or less of a polyolefin-based resin in 100% by mass of all components of the foam, 25% by mass to 80% by mass of a polyethylene in which the polyolefin-based resin contains a component derived from natural-derived ethylene, and 75% by mass to 20% by mass of a low-density polyethylene produced from fossil raw materials, and the density of the foam is in the range of 20 kg / m 3 ~50 kg / m 3 and the biomass degree measured by ASTM D6866 (established in 2004) is 25% or more.

Prior Art Documents

Patent Documents

[0006] [Patent Document 1] Japanese Patent No. 5919841 [Summary of the Invention] [Problems to be Solved by the Invention]

[0007] However, in the invention described in Patent Document 1, since it is necessary to adjust the resin component constituting the single-layer foam to obtain a desired foam product, it is difficult to efficiently obtain a foam product that satisfies various properties as a product, such as density and thickness, while increasing the biomass content in consideration of the environmental impact. The present invention has been made in view of the above circumstances, and an object thereof is to provide a laminate and a method for producing the same that can efficiently obtain a foam product having desired properties while considering the environmental impact. [Means for Solving the Problems]

[0008] The present inventor has found that by laminating a plurality of layers including a layer having a polyethylene-based resin with a biomass content of 40% or more as a base resin and a layer having a polyethylene-based resin with a biomass content of 20% or less as a base resin, and making at least one of these layers a foam layer, it is possible to efficiently obtain a foam product having desired properties while increasing the biomass content, and thus the present invention has been achieved.

[0009] That is, the present invention is a sheet-like or plate-like laminate, having at least one A layer having a polyethylene-based resin A with a biomass content of 40% or more measured by ASTM D 6866 as a base resin, and at least one B layer having a polyethylene-based resin B with a biomass content of 20% or less measured by ASTM D 6866 as a base resin, wherein at least one of the A layer or the B layer is a foam layer, the thickness of the laminate is 2 mm or more, the density of the laminate is 10 kg / m 3 or more and 300 kg / m 3 or less, and the biomass content of the laminate measured by ASTM D 6866 is 5% or more.

[0010] The proportion of the foamed layer in the laminate is preferably 50% by mass or more.

[0011] It is preferable that at least one layer of the A layer is a foamed A layer that is a foamed layer, and at least one layer of the B layer is a foamed B layer that is a foamed layer.

[0012] The density of the foamed A layer is 10 kg / m 3 or more and 300 kg / m 3 or less, and the ratio of the density of the foamed B layer to the density of the foamed A layer is preferably 0.8 or more and 1.2 or less.

[0013] The biomass degree D of the foamed A layer A and the biomass degree D of the foamed B layer B and the difference D A -D B is preferably 40% or more.

[0014] The manufacturing method of the laminate of the present invention is a manufacturing method of a sheet-like or plate-like laminate, which includes an A layer using a polyethylene-based resin A having a biomass degree of 40% or more measured by ASTM D 6866 as a base resin, and a B layer using a polyethylene-based resin B having a biomass degree of 20% or less measured by ASTM D 6866 as a base resin. At least one layer of each is laminated, at least one layer of the A layer and the B layer is a foamed layer, the thickness of the laminate is 2 mm or more, and the density of the laminate is 10 kg / m 3 or more and 300 kg / m 3 or less, and it is a manufacturing method of a laminate having a biomass degree of 5% or more measured by ASTM D 6866 of the laminate.

Advantages of the Invention

[0015] According to the present invention, it is possible to obtain a laminate that takes environmental load into consideration and is easy to obtain desired properties.

Brief Description of the Drawings

[0016]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Mode for Carrying Out the Invention

[0017] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0018] [Laminate] The laminate of the present invention is a sheet-like or plate-like laminate, and has at least one A layer having a polyethylene-based resin A with a biomass content of 40% or more measured by ASTM D 6866 as a base resin, and at least one B layer having a polyethylene-based resin B with a biomass content of 20% or less measured by ASTM D 6866 as a base resin. At least one of the A layer or the B layer is a foamed layer, the thickness of the laminate is 2 mm or more, the density of the laminate is 10 kg / m 3 or more and 300 kg / m 3 or less, and the biomass content of the laminate measured by ASTM D 6866 is 5% or more.

[0019] (A layer) The A layer is made of a polyethylene-based resin A with a biomass content of 40% or more measured by ASTM D 6866 as a base resin. Examples of the polyethylene-based resin A in the present invention include low-density polyethylene, linear low-density polyethylene, high-density polyethylene, ethylene-vinyl acetate copolymer, ethylene-methyl methacrylate copolymer, ethylene-ethyl acrylate copolymer, ethylene-butyl acrylate copolymer, and the like, and mixtures thereof. Further, the polyethylene-based resin A only needs to satisfy the above biomass degree. As the polyethylene-based resin A, for example, only a plant-derived polyethylene-based resin can be used, or a plant-derived polyethylene-based resin and a petroleum-derived polyethylene-based resin can be used in combination. When the A layer using the polyethylene-based resin A as the base resin is a foamed layer, from the viewpoint of easily obtaining a foam with good cushioning properties, the polyethylene-based resin A preferably contains low-density polyethylene as a main component. Specifically, the proportion of low-density polyethylene in the polyethylene-based resin A is preferably 50% by mass or more, more preferably 60% by mass or more, and still more preferably 80% by mass or more. Further, from the viewpoint of easily increasing the biomass degree in the laminate, the polyethylene-based resin A preferably contains plant-derived low-density polyethylene as a main component. Specifically, the proportion of plant-derived low-density polyethylene in the polyethylene-based resin A is preferably 50% by mass or more, more preferably 60% by mass or more, and even more preferably 80% by mass or more. The above low-density polyethylene has a long-chain branched structure and a density of 0.910 g / cm 3 or more and less than 0.930 g / cm 3 means polyethylene. Examples of the plant-derived polyethylene-based resin include polyethylene-based resins produced by polymerizing monomers containing bioethylene produced from plants such as sugarcane, corn, and beet. Examples of commercially available plant-derived polyethylene-based resins include plant-derived low-density polyethylenes such as SEB853, SPB681, and STN7006 manufactured by Braskem.

[0020] - Biomass degree - The biomass content measured by ASTM D 6866 means the proportion of plant-derived components (naturally derived components) contained in the resin, and is determined by measuring the concentration of radioactive carbon C14. From the viewpoint of easily increasing the biomass content in the laminate, the polyethylene-based resin A preferably has a biomass content of 50% or more, more preferably 60% or more, still more preferably 70% or more, even more preferably 80% or more, and particularly preferably 90% as measured by ASTM D 6866. When a plurality of polyethylene-based resins are used in combination as the polyethylene-based resin A, the biomass content of the polyethylene-based resin A may be calculated from the biomass content of each polyethylene-based resin contained in the polyethylene-based resin A and the content ratio of each polyethylene-based resin contained in the polyethylene-based resin A. As a method for increasing the biomass content of the polyethylene-based resin A, for example, it can be adjusted by increasing the proportion of the plant-derived polyethylene-based resin contained in the polyethylene-based resin A, increasing the amount of bioethylene used in the production of the plant-derived polyethylene-based resin, and the like.

[0021] -Melting point- The melting point of the polyethylene-based resin A is preferably 100°C or higher and 115°C or lower. By setting it within the above range, when the A layer using the polyethylene-based resin A as the base resin is a foamed layer, a foamed sheet having a good cell structure and excellent cushioning properties can be stably obtained. From this viewpoint, the melting point of the polyethylene-based resin A is preferably 105°C or higher, more preferably 107°C or higher. Also, the melting point of the polyethylene-based resin A is preferably 113°C or lower, more preferably 112°C or lower.

[0022] -Measurement of melting point- The melting point of the polyethylene-based resin A and the melting point of the polyethylene-based resin B described below can be measured based on JIS K 7121-1987. In the measurement, a test piece conditioned according to the conditions of JIS K 7121-1987 3. Conditioning of test pieces (2) (however, the cooling rate is 10 °C / min.) is used, and the temperature is raised at 10 °C / min to obtain a melting peak, and the temperature at the peak of the obtained melting peak is taken as the melting point. When two or more melting peaks appear, the temperature at the peak of the melting peak with the largest area is taken as the melting point. In addition, in the measurement of the above melting point, samples taken from each layer and polyethylene-based resins used to form each layer can be used as test pieces.

[0023] -Melt flow rate- The melt flow rate of the polyethylene-based resin A is preferably 0.1 g / 10 min or more and 5 g / 10 min or less, and more preferably 0.2 g / 10 min or more and 4 g / 10 min or less. When the A layer using the polyethylene-based resin A as the base resin is a foamed layer, it becomes easier to stably manufacture a foamed sheet having a wide thickness and apparent density within this range. The melt flow rate of the above low-density polyethylene-based resin A and the melt flow rate of the low-density polyethylene-based resin B described below are values measured at a temperature of 190 °C and a load of 2.16 kg in accordance with JIS K7210-1:2014.

[0024] When a plurality of types of polyethylene-based resins are used as the polyethylene-based resin A, a kneaded mixture for measurement in which each polyethylene-based resin is melt-kneaded by an extruder or the like at the blending ratio of each polyethylene-based resin during the production of the A layer is prepared, and various measurements are performed on the kneaded mixture for measurement, so that the melting point and melt flow rate of the polyethylene-based resin can be determined.

[0025] (B layer) The B layer is made of a polyethylene-based resin B having a biomass content of 20% or less measured by ASTM D 6866 as the base resin. Examples of the polyethylene-based resin B in the present invention include low-density polyethylene, linear low-density polyethylene, high-density polyethylene, ethylene-vinyl acetate copolymer, ethylene-methyl methacrylate copolymer, ethylene-ethyl acrylate copolymer, ethylene-butyl acrylate copolymer, and the like, and mixtures thereof. Further, the polyethylene-based resin B only needs to satisfy the above biomass degree, and as the polyethylene-based resin B, for example, only a petroleum-derived polyethylene-based resin can be used, or a petroleum-derived polyethylene-based resin and a plant-derived polyethylene-based resin can be used in combination.

[0026] When the B layer using the polyethylene-based resin B as the base resin is a foamed layer, from the viewpoint of easily obtaining a foam with good cushioning properties, the polyethylene-based resin B preferably contains low-density polyethylene as a main component. Specifically, the proportion of low-density polyethylene in the polyethylene-based resin B is preferably 50% by mass or more, more preferably 60% by mass or more, and still more preferably 80% by mass or more. Further, when the B layer using the polyethylene-based resin B as the base resin is a foamed layer, from the viewpoint of easily obtaining a foam having desired physical properties, the polyethylene-based resin B preferably contains petroleum-derived low-density polyethylene as a main component. Specifically, the proportion of petroleum-derived low-density polyethylene in the polyethylene-based resin B is preferably 50% by mass or more, more preferably 60% by mass or more, and still more preferably 80% by mass or more. The above low-density polyethylene means polyethylene having a long-chain branched structure and a density of 0.910 g / cm 3 or more and less than 0.930 g / cm 3 Hereinafter. Further, as the petroleum-derived polyethylene-based resin, a polyethylene-based resin derived from a fossil fuel resource produced using a fossil fuel such as naphtha as a raw material can be used.

[0027] When the B layer having a polyethylene-based resin B as a base resin is a foamed layer, from the viewpoint of easily obtaining a foam having desired physical properties, the polyethylene-based resin B preferably has a biomass content of 15% or less, more preferably 10% or less, still more preferably 5% or less, and particularly preferably 0% as measured by ASTM D 6866. In addition, when a plurality of polyethylene-based resins are used in combination as the polyethylene-based resin B, the biomass content of the polyethylene-based resin B may be calculated from the biomass content of each polyethylene-based resin contained in the polyethylene-based resin B and the content ratio of each polyethylene-based resin contained in the polyethylene-based resin B. As a method for making the biomass content of the polyethylene-based resin B below a predetermined value, for example, by increasing the proportion of the petroleum-derived polyethylene-based resin contained in the polyethylene-based resin B it can be adjusted.

[0028] -Melting point- The melting point of the polyethylene-based resin B is preferably 100°C or higher and 115°C or lower. By setting it within this range, when the B layer having a polyethylene-based resin B as a base resin is a foamed layer, a foam having a good cell structure and excellent cushioning properties can be stably obtained easily. From such a viewpoint, the melting point is preferably 113°C or lower, more preferably 112°C or lower. Also, the melting point is preferably 105°C or higher, more preferably 107°C or higher.

[0029] -Melt flow rate- The melt flow rate of the polyethylene-based resin B is preferably 0.1 g / 10 min or more and 5 g / 10 min or less. When it is within this range, when the B layer having a polyethylene-based resin B as a base resin is a foamed layer, it becomes easy to stably manufacture a foamed sheet having a wide thickness and apparent density.

[0030] In addition, when using a plurality of types of polyethylene-based resins as the polyethylene-based resin B, a kneaded product for measurement in which each polyethylene-based resin is melt-kneaded by an extruder or the like is prepared at the blending ratio of each polyethylene-based resin during the production of the B layer, and various measurements are performed on the kneaded product for measurement, whereby the melting point and melt flow rate of the polyethylene-based resin B can be determined.

[0031] (Foamed layer, foamed layer ratio) In the laminate of the present invention, at least one of the A layer and the B layer is a foamed layer. For example, the laminate includes a form in which at least one of the A layers is a foamed layer (a form having one or more foamed A layers), and a form in which at least one of the B layers is a foamed layer (a form having one or more foamed B layers). Further, when the laminate has one or more foamed A layers and one or more foamed B layers, for example, the laminate can have 2 to 15 foamed layers. Note that the laminate of the present invention may have a non-foamed layer (unfoamed layer). The non-foamed layer includes a resin film and a resin layer formed by extrusion lamination or the like for laminating and adhering between layers. From the viewpoint of stably obtaining a foamed product having desired physical properties, the ratio of the foamed layer in the laminate of the present invention is preferably 50% by mass or more, more preferably 60% by mass or more, and even more preferably 80% or more. When the laminate has a plurality of foamed layers, the total ratio of the foamed layers in the laminate is defined as the ratio of the foamed layer in the laminate. Further, from the viewpoint of easily and efficiently manufacturing a foamed product having a desired biomass degree, density, and thickness, the laminate is preferably a foamed A layer in which at least one of the A layers is a foamed layer, and a foamed B layer in which at least one of the B layers is a foamed layer. Note that, within the range where the intended purpose can be achieved, the laminate may have a layer other than the A layer and the B layer.

[0032] (Density) The density of the foamed A layer is preferably 10 kg / m 3 or more and 300 kg / m 3 or less, more preferably 12 kg / m 3200 kg / m or more 3 is more preferably 15 kg / m or less 3 100 kg / m or more 3 is more preferably 10 kg / m or less. When the density of the foam A layer is 10 kg / m 3 or more, it becomes easier to manufacture a foam product having appropriate compressive strength. Further, when the density of the foam A layer is 300 kg / m 3 or less, it becomes easier to manufacture a lightweight foam product and a foam product having good cushioning properties. From the same viewpoint, the density of the foam B layer is preferably 10 kg / m 3 300 kg / m or less 3 is preferably 12 kg / m or more 3 200 kg / m or less 3 is more preferably 15 kg / m or more 3 100 kg / m or less 3 is even more preferably the case.

[0033] (Density ratio) The ratio of the density of the foam B layer to the density of the foam A layer is preferably 0.8 or more and 1.2 or less, and more preferably 0.9 or more and 1.1 or less. By setting the density ratio within the above range, a foam product having desired physical properties can be stably obtained. Note that the density can be obtained by dividing the basis weight (g / m 2 ) of the foam A layer and the foam B layer by the thickness of each layer and further converting the unit to (kg / m 3 ). Further, the basis weight is the weight per unit area of the foam layer.

[0034] (Difference in biomass degree) The difference D TA between the total biomass degree D TB of the A layers constituting the laminate and the total biomass degree D TA -D TBis preferably 40% or more, more preferably 50% or more, still more preferably 60% or more, even more preferably 70% or more, and particularly preferably 80% or more. When the difference in biomass degree is 40% or more, it becomes easier to manufacture a laminate having a desired thickness and density while increasing the biomass degree in the laminate. The total biomass degree D TA is the total value of the biomass degrees of the A layers in the laminate considering the weight ratios of the respective A layers constituting the laminate. For example, it can be obtained by multiplying the biomass degree (ratio) of each A layer constituting the laminate by the basis weight of each A layer, adding these values, and dividing the sum by the total value of the basis weights of the A layers constituting the laminate, and expressing the result as a percentage. Similarly, the total biomass degree D TB is the total value of the biomass degrees of the B layers in the laminate considering the weight ratios of the respective B layers constituting the laminate. For example, it can be obtained by multiplying the biomass degree (ratio) of each B layer constituting the laminate by the basis weight of each B layer, adding these values, and dividing the sum by the total value of the basis weights of the B layers constituting the laminate, and expressing the result as a percentage.

[0035] Also, the difference D A between the biomass degree D B of the foamed A layer and the biomass degree D A of the foamed B layer B is preferably 40% or more, more preferably 50% or more, still more preferably 60% or more, even more preferably 70% or more, and particularly preferably 80% or more. When the difference in biomass degree is 40% or more, it becomes easier to manufacture a laminate having a desired thickness and density while increasing the biomass degree in the laminate. When the laminate has a plurality of foamed A layers, the arithmetic mean value of these biomass degrees is taken as the biomass degree D A of the foamed A layer. Similarly, when the laminate has a plurality of foamed B layers, the arithmetic mean value of these biomass degrees is taken as the biomass degree D B of the foamed B layer.

[0036] In addition, compared with polyethylene-based resins having a relatively low biomass content, the types of resins that can be selected for polyethylene-based resins with a relatively high biomass content are currently limited. Therefore, when producing a foam using a polyethylene-based resin with a relatively high biomass content, a resin that is difficult to extrude and foam may be used in the production of the foam. When attempting to obtain a foam with a lower density, it may be difficult to obtain a foam with the desired specifications. On the other hand, a foam B layer obtained using a polyethylene-based resin with a relatively low biomass content and easy to extrude and foam, and a foam A layer obtained using a polyethylene-based resin with a relatively high biomass content are combined, and the difference D in biomass content between the foam A layer and the foam B layer A -D B By laminating these so that they have a predetermined relationship, it is possible to stably produce a foam product having a desired density while ensuring the biomass content.

[0037] Within the range where the effects of the present invention can be achieved, other components such as resins and elastomers other than the polyethylene-based resins specified in the present invention may be blended into each layer. In that case, the blending amount of other components is preferably 40 parts by mass or less, more preferably 30 parts by mass or less, and even more preferably 20 parts by mass or less with respect to 100 parts by mass of the polyethylene-based resin.

[0038] (Physical foaming agent) As the physical foaming agent used for forming the foam layer, the physical foaming agents conventionally used in the production of polyethylene-based resin foams can be preferably used. Examples of the physical foaming agent include organic physical foaming agents and inorganic physical foaming agents.

[0039] Examples of organic physical foaming agents include aliphatic hydrocarbons such as propane, normal butane, isobutane, normal pentane, isopentane, normal hexane, and isohexane; alicyclic hydrocarbons such as cyclopentane and cyclohexane; chlorinated hydrocarbons such as methyl chloride and ethyl chloride; fluorinated hydrocarbons such as 1,1,1,2 - tetrafluoroethane and 1,1 - difluoroethane; ethers such as dimethyl ether and methyl ethyl ether; and alcohols such as methanol and ethanol. Examples of inorganic physical foaming agents include oxygen, nitrogen, carbon dioxide, air, water, etc. These physical foaming agents can be used by mixing two or more of them. Among these, it is preferable to use an organic physical foaming agent from the viewpoint of excellent extrusion foamability and take - up stability of the foam, and it is more preferable to use butane. As butane, normal butane, isobutane, or a mixture thereof can be used.

[0040] The addition amount of the physical foaming agent can be adjusted according to its type, the apparent density and basis weight of the target foamed sheet. For example, when obtaining the foamed sheet of the present invention using a butane mixture of 30% by mass of isobutane and 70% by mass of normal butane as the physical foaming agent, it is preferable to add 3 - 35 parts by mass of the physical foaming agent, more preferably 5 - 30 parts by mass, and even more preferably 6 - 25 parts by mass with respect to 100 parts by mass of the base resin.

[0041] (Bubble regulator) In the present invention, a cell regulator can be used together with the above-mentioned low-density polyethylene. As the cell regulator, inorganic powder or a chemical foaming agent can be used. Examples of the inorganic powder include talc, zeolite, silica, calcium carbonate, etc. Examples of the chemical foaming agent include azodicarbonamide, hydrazodicarbonamide, azobisisobutyronitrile, sodium hydrogen carbonate (baking soda), and a baking soda-citric acid-based chemical foaming agent which is a mixture of sodium hydrogen carbonate and a monoalkali metal salt of citric acid such as citric acid or sodium citrate. The addition amount of the cell regulator is preferably 0.1 part by mass or more and 3 parts by mass or less, more preferably 0.2 part by mass or more and 2 parts by mass or less, based on 100 parts by mass of the base resin. When the addition amount is within the above range, it becomes easier to stably adjust the cell diameter of the foamed layer to a desired range.

[0042] (Other Additives) In the present invention, in addition to the above components, various additives can be added within a range that does not impair the effects of the present invention. Examples of the additives include an anti-shrinkage agent, an antistatic agent, an antioxidant, a heat stabilizer, a weathering agent, an ultraviolet absorber, a flame retardant, an inorganic filler, an antibacterial agent, a colorant, etc.

[0043] (Thickness of the Foamed Layer A and the Foamed Layer B) The thickness of each foamed layer A and each foamed layer B constituting the laminate is preferably 0.05 mm or more and 30 mm or less. Also, when manufacturing a relatively low-thickness laminate (for example, a laminate with a thickness of 20 mm or less), it is preferable that the thickness of each foamed layer A and each foamed layer B is a sheet-like foamed layer of 0.05 mm or more and less than 10 mm. On the other hand, when manufacturing a relatively high-thickness laminate (for example, a laminate with a thickness exceeding 20 mm and 150 mm or less), it is preferable that the thickness of each foamed layer A and each foamed layer B is a plate-like foamed layer of 10 mm or more and 20 mm or less. By setting the thickness of the foamed layer A and the foamed layer B within the above range, a desired laminate can be efficiently manufactured.

[0044] Incidentally, the thicknesses of the foamed layer A and the foamed layer B for forming the laminate can be determined by measuring the thickness at predetermined intervals (for example, at 1 cm intervals) for the entire width of the foamed layer in the width direction orthogonal to the extrusion direction of the foamed layer, and calculating the arithmetic mean of the measured thicknesses. The thickness can be measured using an offline thickness measuring machine "TOF-4R" manufactured by Yamamoto Electric Co., Ltd.

[0045] [Physical properties of the laminate] The thickness of the laminate is preferably 2 mm or more and 150 mm or less in order to obtain a foamed product according to various desired applications and cushioning performance. Further, for example, when a foamed product with a relatively high thickness is required, a plate-shaped laminate with a thickness of 10 mm or more can be used. The density of the laminate is 10 kg / m 3 or more and 300 kg / m 3 or less, preferably 12 kg / m 3 or more and 200 kg / m 3 or less, more preferably 15 kg / m 3 or more and 100 kg / m 3 or less. Incidentally, the density can be determined by dividing the basis weight (g / m 2 ) of the laminate by the thickness of the laminate and further converting the unit to (kg / m 3 ). From the viewpoint of reducing the environmental load, the biomass content of the laminate measured according to ASTM D 6866 is preferably 10% or more, more preferably 15% or more, and even more preferably 20% or more. Also, the upper limit of the biomass content is, for example, 80%, and it may be 70%, 60%, or 50%. Incidentally, the biomass content in the laminate may be calculated from the weight ratio of the A layer and the B layer constituting the laminate and the biomass content of each layer.

[0046] [Manufacturing method of the laminate] The method for manufacturing the laminate of the present invention includes an A layer using a polyethylene-based resin A having a biomass content of 50% or more as measured by ASTM D 6866 as a base resin, and a B layer using a polyethylene-based resin B having a biomass content of 30% or less as measured by ASTM D 6866 as a base resin. At least one layer of each of the A layer and the B layer is laminated, at least one layer of the A layer and the B layer is a foamed layer, the thickness of the laminate is 2 mm or more, and the density of the laminate is 10 kg / m 3 or more and 300 kg / m 3 or less, and the biomass content of the laminate as measured by ASTM D 6866 is 5% or more. In the method for manufacturing the laminate of the present invention, it is preferable to laminate at least one layer of a sheet-like or plate-like A layer and at least one layer of a sheet-like or plate-like B layer. Further, in the method for manufacturing the laminate of the present invention, it is preferable that at least one layer of the A layer is a foamed A layer that is a foamed layer, and at least one layer of the B layer is a foamed B layer that is a foamed layer. Regarding the polyethylene-based resin, biomass content, thickness, density, etc. of the A layer and the B layer used in the manufacture of the laminate, the above-described content of the laminate can be appropriately referred to.

[0047] The A layer and the B layer used to form the laminate can be prepared, for example, as films, sheets, or foams using a polyethylene-based resin A or a polyethylene-based resin B as a base resin. Further, the A layer and the B layer may be formed as a resin layer for laminating and adhering the layers.

[0048] As the foamed A layer and the foamed B layer used to form the laminate, a sheet-like foam or a plate-like foam can be preferably used. The sheet-like foam can be manufactured, for example, as follows. First, a polyethylene-based resin, which is a material for forming the foam, and additives such as a cell regulator added as necessary are supplied to an extruder and heat-kneaded to obtain a resin melt. In the case of producing a sheet-like foam with a thickness of 3 mm or more in extrusion foaming, it is preferable to appropriately blend an anti-shrinkage agent for suppressing excessive shrinkage of the foam. As the anti-shrinkage agent, a fatty acid ester, an aliphatic amine, a fatty acid amide, or the like can be used. Next, a physical foaming agent is press-fitted into this resin melt and further kneaded to obtain a foamable resin melt in the extruder. The foamable resin melt is introduced into an annular die provided on the downstream side of the extruder, extruded into the atmosphere from the lip portion at the tip of the annular die, and the foamable resin melt is foamed. Next, the tubular extrusion foam formed by extrusion foaming is expanded (blown up) with a tubular expanding device (mandrel), and while being drawn along the mandrel, it is cut open along the extrusion direction to obtain a sheet-like foam.

[0049] The plate-like foam can be manufactured, for example, as follows. First, a polyethylene-based resin, a cell regulator, etc. for forming the foam layer are supplied to the supply port of the extruder, melted and kneaded, then a physical foaming agent is added from the middle of the extruder, and further melted and kneaded to adjust a foamable resin melt for forming the foam layer. Next, the foamable resin melt is extruded from the die under a pressure lower than that inside the die (usually under atmospheric pressure) to foam the foamable resin melt, thereby manufacturing a plate-like foam.

[0050] Also, for example, a multilayer foam having a plurality of foam layers produced by co-extrusion can be used to constitute part or all of the laminate. As an example, a multilayer foam having a foam core layer and foam surface layers laminated and adhered to both sides of the foam core layer, manufactured as follows, may be used. By using an extrusion device capable of co-extrusion, taking up a tubular foam having a multilayer structure formed by co-extruding a foaming resin melt for a foamed core layer obtained by kneading a polyethylene-based resin and a physical foaming agent, and a foaming resin melt for a foamed surface layer obtained by kneading a polyethylene-based resin and a physical foaming agent, a multilayer foam can be produced. In addition, to each foaming resin melt, additives such as an antistatic agent and a shrinkage inhibitor can be added as necessary in addition to the resin. In the above case, as the extrusion device, for example, prepare an extrusion device in which a co-extrusion annular die is attached to the downstream side of the extruder for forming the foamed core layer and a co-extrusion annular die is connected to the downstream side of the extruder for forming the foamed surface layer. By performing co-extrusion using the extrusion device, a tubular multilayer foam is obtained, and the multilayer foam can be produced by cutting open the tubular multilayer foam as described above.

[0051] Further, in order to form a laminate, a multilayer foam including a foamed layer and a resin layer may be used. As an example, a multilayer foam including a foamed B layer and B layers (resin layers) laminated and adhered to both surfaces of the foamed B layer produced as follows may be used. By using an extrusion device capable of co-extrusion, taking up a tubular foam formed by co-extruding a foaming resin melt for a foamed B layer obtained by kneading a polyethylene-based resin B and a physical foaming agent, and a resin melt for a resin layer obtained by kneading a polyethylene-based resin B, a multilayer foam can be produced. In addition, to each resin melt, additives such as an antistatic agent can be added as necessary in addition to the resin.

[0052] In this case, as the extrusion device, for example, prepare an extrusion device in which a co-extrusion annular die is attached to the downstream side of the extruder for forming the foamed layer and a co-extrusion annular die is connected to the downstream side of the extruder for forming the resin layer. By performing co-extrusion using the extrusion device, a tubular multilayer foam is obtained, and the multilayer foam can be produced by cutting open the tubular multilayer foam as described above. Note that the resin layer is preferably in a non-foamed state.

[0053] The method for laminating the A layer and the B layer is not particularly limited. For example, after heating the lamination surface of each layer with hot air or the like and then pressing, the layers are adhered by heat; a method of laminating a resin melted by an extruder or the like on the lamination surface and adhering the layers through this resin layer (ruder lamination); a method of adhering the layers through an adhesive film or an adhesive; a method of forming the A layer and the B layer by coextrusion and laminating and adhering the A layer and the B layer, and the like can be mentioned. In the case of ruder lamination, since polyethylene-based resin A can be used to form the resin layer and the resin layer can be formed with a relatively large basis weight, there is an advantage that it is easy to form a laminate with a high biomass degree while achieving a desired density and thickness.

[0054] When manufacturing an extruded foam by the extrusion foaming method, when the foam is relatively thick and a low-density foam is desired, the production of the foam tends to be difficult. On the other hand, plant-derived polyethylene-based resins have fewer types of resins (physical properties) to choose from compared to petroleum-derived polyethylene-based resins, so the degree of freedom in manufacturing the foam tends to decrease. For these reasons, in order to obtain a foam having a desired thickness and density and a desired biomass degree, for example, when manufacturing a foamed product by blending a plant-derived polyethylene-based resin and a petroleum-derived polyethylene-based resin as a single-layer foam, it may be necessary to adjust manufacturing conditions such as selecting a combination of raw materials suitable for the foamed product with the desired specifications, and the production of the foam may become difficult. Also, in this case, there was a risk that product loss would easily occur due to the switching of raw materials according to the desired specifications of the foamed product. On the other hand, in the present invention, since a foamed product is obtained by using a specific laminate, it becomes easier to stably manufacture a foam for forming the laminate, for example, a foamed A layer or a foamed B layer. Further, by combining the pre-prepared A layer and B layer to form a laminate, various specifications of foamed products can be obtained with a relatively small number of types of foams, so that a foamed product having a desired thickness, density, and biomass degree can be efficiently manufactured.

[0055] As a specific example, when obtaining foamed products with a biomass content of 45% and a density of 30 kg / m 3 and having various thicknesses, the case will be described. In this case, first, a polyethylene-based resin with a biomass content of 90% is used as the base resin, with a density of 30 kg / m 3 and a foamed A layer (foamed A layer example 1) with a thickness of 1 mm, a polyethylene-based resin with a biomass content of 0% is used as the base resin, with a density of 30 kg / m 3 and a foamed B layer (foamed B layer example 1) with a thickness of 1 mm, and a polyethylene-based resin with a biomass content of 0% is used as the base resin, with a density of 15 kg / m 3 and a foamed B layer (foamed B layer example 2) with a thickness of 1 mm are prepared. By laminating and adhering the prepared foams, the following foamed products can be obtained. By laminating one layer each of the foamed A layer example 1 and the foamed B layer example 1 to form a laminate, a foamed product with a biomass content of 45%, a density of 30 kg / m 3 and a thickness of 2 mm can be obtained. Also, by laminating two layers each of the foamed A layer example 1 and the foamed B layer example 1 to form a laminate, a foamed product with a biomass content of 45%, a density of 30 kg / m 3 and a thickness of 4 mm can be obtained. Also, by laminating one layer of the foamed A layer example 1 and two layers of the foamed B layer example 2 to form a laminate, a foamed product with a biomass content of 45%, a density of 30 kg / m 3 and a thickness of 3 mm can be obtained.

[0056] Also, as another specific example, using the above foamed A layer example 1 and the above foamed B layer example 1, a density of 30 kg / m 3 and a thickness of 5 mm, foamed products with various biomass contents can be obtained as follows. By laminating one layer of the foamed A layer example 1 and four layers of the foamed B layer example 1 to form a laminate, a foamed product with a density of 30 kg / m 3 and a thickness of 5 mm and a biomass content of 18% can be obtained. Also, by laminating two layers of the foamed A layer example 1 and three layers of the foamed B layer example 1 to form a laminate, a density of 30 kg / m 3and a foamed product with a thickness of 5 mm and a biomass content of 36% can be obtained. Further, by laminating the three-layer foamed A layer Example 1 and the two-layer foamed B layer Example 1 to form a laminate, the density is 30 kg / m 3 and a foamed product with a thickness of 5 mm and a biomass content of 54% can be obtained. Further, by laminating the four-layer foamed A layer Example 1 and the one-layer foamed B layer Example 1 to form a laminate, the density is 30 kg / m 3 and a foamed product with a thickness of 5 mm and a biomass content of 72% can be obtained.

[0057] (Examples of layer structures in the laminate) Regarding the layer structure of the laminate of the present invention, within the range that can achieve the intended purpose of the present invention, the A layer (foamed A layer) and the B layer (foamed B layer) can be combined and configured. An example of the layer structure in the laminate including the foamed A layer and the foamed B layer is shown in FIGS. 1 to 5. As shown in FIG. 1, the laminate of the present invention may be a laminate 10 having two foamed layers, which is laminated in the order of the foamed A layer (12) and the foamed B layer (11). Further, as shown in FIG. 2, it may be a laminate 20 having three foamed layers, which is laminated in the order of the first foamed B layer (11a), the foamed A layer (12), and the second foamed B layer (11b). Further, as shown in FIG. 3, it may be a laminate 30 having four foamed layers, which is laminated in the order of the first foamed B layer (11a), the first foamed A layer (12a), the second foamed A layer (12b), and the second foamed B layer (11b). Further, as shown in FIG. 4, it may be a laminate 40 having five foamed layers, which is laminated in the order of the first foamed B layer (11a), the first foamed A layer (12a), the second foamed B layer (11b), the second foamed A layer (12b), and the third foamed B layer (11c). Further, as shown in FIG. 5, it may be a laminate 50 having three foamed layers, which is laminated in the order of the first foamed A layer (12a), the foamed B layer (11), and the second foamed A layer (12b). In FIGS. 1 to 5, each foam layer constituting the laminate is illustrated, but laminates having non-foamed A layers and B layers on the surface side of the foam layer or between the foam layers are also included in the laminate of the present invention.

[0058] Further, for example, a laminate can be formed using a foamed A layer and a foamed B layer having a density lower than that of the foamed A layer. At this time, for example, by disposing the foamed B layer as the foam layer located on the outermost surface side of the laminate, a laminate having a relatively soft surface layer portion can be formed. Further, by disposing the foamed A layer as the foam layer located on the outermost surface side of the laminate, a laminate having a relatively smooth surface layer portion can be formed. Further, by disposing the foamed B layer as the foam layer located on one outermost surface side of the laminate and disposing the foamed A layer as the foam layer located on the other outermost surface side of the laminate, a laminate having different textures on each surface can be formed.

Example

[0059] In order to form a laminate having an A layer and a B layer, various foams were prepared using the following resins and the like. · Plant-derived low-density polyethylene 1: "SEB853" manufactured by Braskem S.A., biomass degree 95% measured by ASTM D 6866, melting point 112 ° C, melt flow rate 2.7 g / 10 min · Petroleum-derived low-density polyethylene 1: "NUC-8321" manufactured by ENEOS NUC Co., Ltd., biomass degree 0% measured by ASTM D 6866, melting point 112 ° C, melt flow rate 2.4 g / 10 min · Antishrinkage agent (glyceryl monostearate): "S-100" manufactured by Riken Vitamin Co., Ltd. · Bubble regulator (talc): Manufactured by Matsumura Sangyo Co., Ltd., "High Filler #12" · Baking soda-citric acid-based bubble regulator: "Fine Cell Master PO217K" manufactured by Dainichi Seika Kogyo Co., Ltd. · Multilayer Foam 1: A plate-shaped multilayer foam with a thickness of 20 mm and a basis weight of 470 g / m², having three foamed layers (Foamed A Layers) with plant-derived low-density polyethylene 1 (Polyethylene-based Resin A) as the base resin 2 , with an apparent density of 23.5 kg / m³ 3 · Multilayer Foam 2: A plate-shaped multilayer foam with a thickness of 15 mm and a basis weight of 350 g / m², having three foamed layers (Foamed A Layers) with plant-derived low-density polyethylene 1 (Polyethylene-based Resin A) as the base resin 2 , with an apparent density of 23.3 kg / m³ 3 · Multilayer Foam 3: A sheet-shaped multilayer foam with a thickness of 5 mm and a basis weight of 150 g / m², having three foamed layers (Foamed A Layers) with plant-derived low-density polyethylene 1 (Polyethylene-based Resin A) as the base resin 2 , with an apparent density of 30 kg / m³ 3 · Multilayer Foam 4: A plate-shaped multilayer foam with a thickness of 20 mm and a basis weight of 470 g / m², having three foamed layers (Foamed B Layers) with petroleum-derived low-density polyethylene 1 (Polyethylene-based Resin B) as the base resin 2 , with an apparent density of 23.5 kg / m³ 3 · Multilayer Foam 5: A sheet-shaped multilayer foam with a thickness of 5 mm and a basis weight of 150 g / m², having three foamed layers (Foamed B Layers) with petroleum-derived low-density polyethylene 1 (Polyethylene-based Resin B) as the base resin 2 , with an apparent density of 30 kg / m³ 3 · Foam 1: A sheet-shaped foam with a thickness of 2 mm and a basis weight of 60 g / m², having plant-derived low-density polyethylene 1 (Polyethylene-based Resin A) as the base resin 2 , with an apparent density of 30 kg / m³ 3 · Foam 2: A sheet-shaped foam with a thickness of 2 mm and a basis weight of 60 g / m², having petroleum-derived low-density polyethylene 1 (Polyethylene-based Resin B) as the base resin 2 , with an apparent density of 30 kg / m³ 3

[0060] Among the above, Multilayer Foams 1 to 5 were manufactured as follows. Multilayer Foam 1: ​​​​​​​An extrusion apparatus equipped with an extruder for forming a foamed core layer and an extruder for forming a foamed surface layer was used. Specifically, as the extruder for forming the foamed core layer, a tandem extruder comprising a first extruder with a barrel inner diameter of 115 mm and a second extruder with a barrel inner diameter of 180 mm connected downstream thereof was prepared. Also, as the extruder for forming the foamed surface layer, a single-screw third extruder with an inner diameter of 115 mm was prepared. A co-extrusion annular die was attached to the downstream side of the second extruder, and the third extruder was connected to the annular die. Further, a cooling member for cooling the outer surface of the tubular foam extruded from the lip portion was attached to the downstream side of the annular die. Also, a mandrel (cooling pipe) with a diameter of 368 mm was arranged on the downstream side of the cooling member.

[0061] To form the foamed core layer, 199 parts by mass of plant-derived low-density polyethylene, 1 part by mass of glycerin monostearate as an anti-shrinkage agent, and 2 parts by weight of talc as a cell regulator were supplied to the extruder and melt-kneaded. Butane as a physical foaming agent was added at 15% by weight based on 100% by mass of the foaming resin melt and further kneaded to form a foaming resin melt for forming the foamed core layer. Also, to form the foamed surface layer, 199 parts by mass of plant-derived low-density polyethylene, 1 part by mass of glycerin monostearate as an anti-shrinkage agent, and 2 parts by weight of talc as a cell regulator were supplied to the extruder and melt-kneaded. Butane as a physical foaming agent was added at 13% by weight based on 100% by mass of the foaming resin melt and further kneaded to form a foaming resin melt for forming the foamed surface layer. After adjusting these foaming resin melts to about 112 °C, extrusion foaming was carried out by extruding at a total discharge rate of 320 kg / hr at a ratio of foamed surface layer / foamed core layer / foamed surface layer = 1 / 6 / 1. The extruded foam was pressed by the cooling member and then taken up along the mandrel. The take-up speed at this time was 10 m / min, and the foam was cut while being taken up to obtain a plate-shaped foam. In this way, the length in the width direction is 1 m, and the cross-sectional area in the direction perpendicular to the extrusion direction is 0.02 m 2A plate-like multilayer foam was manufactured. The foam core layer and the two foam surface layers that make up the multilayer foam are foam layer A. Also, the foam core layer has a thickness of 15 mm and an apparent density of 23.5 kg / m 3 . Also, each foam surface layer has a thickness of 2.5 mm and an apparent density of 23.5 kg / m 3 .

[0062] Multilayer foam 2: A plate-like multilayer foam was manufactured in the same manner as multilayer foam 1, except that the take-up speed when taking up the extruded foam was changed to 15 m / min.

[0063] Multilayer foam 3: A sheet-like multilayer foam was manufactured in the same manner as multilayer foam 1, except that the amount of butane added to the foaming resin melt for forming the foam core layer was changed to 16% by mass based on 100% by mass of the foaming resin melt, the amount of butane added to the foaming resin melt for forming the foam surface layer was changed to 11% by mass based on 100% by mass of the foaming resin melt, the total discharge amount was changed to 200 kg / hr, and the take-up speed when taking up the extruded foam was changed to 27 m / min to perform extrusion foaming. The foam core layer has a thickness of 3.8 mm and an apparent density of 30 kg / m 3 . Also, each foam surface layer has a thickness of 0.6 mm and an apparent density of 30 kg / m 3 .

[0064] Multilayer foam 4: A plate-like multilayer foam was manufactured in the same manner as multilayer foam 1, except that plant-derived low-density polyethylene 1 was changed to petroleum-derived low-density polyethylene 1. The foam core layer and the two foam surface layers that make up the multilayer foam are foam layer B.

[0065] Multilayer foam 5: A sheet-like multilayer foam was manufactured in the same manner as multilayer foam 3, except that plant-derived low-density polyethylene 1 was changed to petroleum-derived low-density polyethylene 1. The foam core layer and the two foam surface layers that make up the multilayer foam are foam layer B.

[0066] Also, among the above, the foams 1 and 2 were manufactured as follows.

[0067] Foam 1: A tandem extruder equipped with a first extruder having a barrel inner diameter of 90 mm and a second extruder having a barrel inner diameter of 120 mm connected to the downstream side thereof was prepared. An annular die was attached to the outlet of the second extruder, and a mandrel (cooling pipe) with a diameter of 350 mm was arranged on the downstream side of the annular die. Using such a manufacturing apparatus, 100 parts by mass of plant-derived low-density polyethylene 1 and 1 part by weight of a sodium bicarbonate-citric acid-based bubble regulator were supplied to the extruder and melt-kneaded. Butane as a physical foaming agent was added at 20% by weight with the foaming resin melt being 100% by mass and further kneaded to form a foaming resin melt. After adjusting the foaming resin melt to about 112°C, extrusion foaming was performed by extruding from the extruder at a discharge rate of 100 kg / hr. The extruded cylindrical foam was cut open while being pulled at a take-up speed of 50 m / min along the mandrel to produce a sheet-like foam with a width of about 1 m.

[0068] Foam 2: A sheet-like foam was manufactured in the same manner as Foam 1 except that plant-derived low-density polyethylene 1 was changed to petroleum-derived low-density polyethylene 1.

[0069] [Example 1] Using Multilayer Foam 1 and Multilayer Foam 4, a laminate having 3 layers of Foam A and 3 layers of Foam B was manufactured. Specifically, using a hot air laminating apparatus, one surface of Multilayer Foam 1 and one surface of Multilayer Foam 4 were each heated by hot air, and then the heated surfaces were overlapped and pressure was applied to thermally fuse them to obtain a laminate having 6 foam layers. The thickness of this laminate was 40 mm, the density was 23.5 kg / m 3 and the biomass content measured by ASTM D 6866 was 46%.

[0070] [Example 2] Using three multilayer foams 1 and two multilayer foams 4, a laminate having 9 foam A layers and 6 foam B layers was manufactured. Specifically, first, using a hot air laminating apparatus, one surface of one multilayer foam 1, both surfaces of the multilayer foam 4, and one surface of one multilayer foam 1 were heated by hot air in the lamination order of multilayer foam 1 / multilayer foam 4 / multilayer foam 1. Then, the heated surfaces were overlapped and pressure was applied to thermally fuse them, thereby obtaining a laminate having 9 foam layers. Next, using a hot air laminating apparatus, one surface of the laminate having 9 foam layers and the surface on the multilayer foam 4 side of the laminate having 6 foam layers obtained in Example 1 were heated by hot air respectively. Then, the heated surfaces were overlapped and pressure was applied to thermally fuse them, thereby obtaining a laminate having 15 foam layers. The thickness of this laminate is 100 mm, and the density is 23.5 kg / m 3 and the biomass content measured by ASTM D 6866 was 55%.

[0071] [Example 3] Using two multilayer foams 2 and a multilayer foam 4, a laminate having 6 foam A layers and 3 foam B layers was manufactured. Specifically, using a hot air laminating apparatus, one surface of one multilayer foam 2, both surfaces of the multilayer foam 4, and one surface of one multilayer foam 2 were heated by hot air in the lamination order of multilayer foam 2 / multilayer foam 4 / multilayer foam 2. Then, the heated surfaces were overlapped and pressure was applied to thermally fuse them, thereby obtaining a laminate having 9 foam layers. The thickness of this laminate is 50 mm, and the density is 23.4 kg / m 3 and the biomass content measured by ASTM D 6866 was 55%.

[0072] [Example 4] Using foam 1 and foam 2, a laminate having 1 foam A layer and 1 foam B layer was manufactured. Specifically, petroleum-derived low-density polyethylene 2 (NUC-8009 manufactured by ENEOS NUC Co., Ltd., biomass content 0% measured by ASTM D 6866) was prepared as the resin for forming the adhesive layer. Using an extrusion laminating apparatus, the resin was melted, and the molten resin was extruded between one surface of the foam 1 and one surface of the foam 2, and the foam 1 and the foam 2 were crimped. Thereby, a laminate having a two-layer foam layer in which the foam 1 and the foam 2 were laminated and adhered via the adhesive layer was obtained. The basis weight of the adhesive layer was laminated so as to be 20 g / m 2 was obtained. The thickness of this laminate was 4 mm, the density was 35 kg / m 3 and the biomass content measured by ASTM D 6866 was 40%.

[0073] [Example 5] Using the multilayer foam 3 and two multilayer foams 5, a laminate having three foam A layers and six foam B layers was manufactured. Specifically, first, petroleum-derived low-density polyethylene 2 was prepared as the resin for forming the adhesive layer. Using an extrusion laminating apparatus, the resin was melted, and the molten resin was extruded between one surface of the multilayer foam 3 and one surface of the multilayer foam 5, and the multilayer foam 3 and the multilayer foam 5 were crimped. The multilayer foam 3 and the multilayer foam 5 were laminated and adhered. Next, plant-derived low-density polyethylene 2 (SBC818 manufactured by Braskem S.A., biomass content 95% measured by ASTM D 6866) was prepared as the resin for forming the adhesive layer. Using an extrusion laminating apparatus, the resin was melted, and the molten resin was extruded between the surface of the multilayer foam 3 on the side where the multilayer foam 5 was not laminated and the other multilayer foam 5, and these were crimped. Thereby, a laminate having nine foam layers was obtained. The basis weight of each adhesive layer was laminated so as to be 20 g / m 2 was obtained. The thickness of this laminate was 15 mm, the density was 33 kg / m 3 and the biomass content measured by ASTM D 6866 was 32%.

[0074] [Example 6] An extrusion apparatus equipped with an extruder for forming the foamed A layer and an extruder for forming the foamed B layer was used. In the extrusion apparatus, a co-extrusion annular die was attached to the downstream side of the extruder for forming the foamed A layer, and the downstream side of the extruder for forming the foamed B layer was connected to the annular die. Also, a mandrel (cooling pipe) was disposed on the downstream side of the annular die. To form the foamed A layer, 199 parts by mass of plant-derived low-density polyethylene, 1 part by mass of glycerin monostearate as an anti-shrinkage agent, and 2 parts by weight of talc as a cell regulator were supplied to an extruder and melt-kneaded. Butane as a physical foaming agent was added in an amount of 11% by weight based on 100% by mass of the foamed resin melt, and further kneaded to form a foamed resin melt for forming the foamed A layer. Also, to form the foamed B layer, 199 parts by mass of petroleum-derived low-density polyethylene, 1 part by mass of glycerin monostearate as an anti-shrinkage agent, and 2 parts by weight of talc as a cell regulator were supplied to an extruder and melt-kneaded. Butane as a physical foaming agent was added in an amount of 11% by weight based on 100% by mass of the foamed resin melt, and further kneaded to form a foamed resin melt for forming the foamed B layer. After adjusting these foamed resin melts to about 112°C, extrusion foaming was carried out by extruding at a total discharge rate of 200 kg / hr at a ratio of foamed A layer / foamed B layer = 1 / 1. The extruded foam was taken along the mandrel. The take-up speed at this time was 34 m / min, and the foam was cut while being taken up to obtain a sheet-like laminate. The thickness of this laminate was 4 mm, and the density was 30 kg / m 3 and the biomass content measured by ASTM D 6866 was 46%. The foamed A layer had a thickness of 2 mm and an apparent density of 30 kg / m 3 The foamed B layer had a thickness of 2 mm and an apparent density of 30 kg / m 3

[0075] ​The laminate of the present invention has at least one A layer with a polyethylene-based resin A having a biomass content of 50% or more measured by ASTM D 6866 as a base resin, and at least one B layer with a polyethylene-based resin B having a biomass content of 30% or less measured by ASTM D 6866 as a base resin. At least one of the A layer or the B layer is a foamed layer. The thickness of the laminate is 2 mm or more, and the density of the laminate is 10 kg / m 3 or more and 300 kg / m 3 or less. Since it is a laminate having a biomass content of 5% or more measured by ASTM D 6866 of the laminate, compared with the case of obtaining a single-layer foam by adjusting the resin component, it is easy to obtain a foamed product having a desired property, for example, a desired density, thickness, etc. while increasing the biomass content.

Claims

1. A sheet-like or plate-like laminate comprising: At least one A layer made of a polyethylene-based resin A having a biomass content of 40% or more as measured by ASTM D 6866 as a base resin, and at least one B layer made of a polyethylene-based resin B having a biomass content of 20% or less as measured by ASTM D 6866 as a base resin, At least one of the A layer or the B layer is a foamed layer, The thickness of the laminate is 2 mm or more, The density of the laminate is 10 kg / m ３ or more and 300 kg / m ３ or less, A laminate having a biomass content of 5% or more as measured by ASTM D 6866.

2. The laminate according to claim 1, wherein the proportion of the foamed layer in the laminate is 50% by mass or more.

3. The laminate according to claim 1 or 2, wherein at least one of the A layers is a foamed A layer that is a foamed layer, and at least one of the B layers is a foamed B layer that is a foamed layer.

4. The density of the foamed A layer is 10 kg / m ３ or more and 300 kg / m ３ or less, The laminate according to claim 3, wherein the ratio of the density of the foamed B layer to the density of the foamed A layer is 0.8 or more and 1.2 or less.

5. The difference D Ａ between the biomass content D Ｂ of the foamed A layer and the biomass content D Ａ of the foamed B layer Ｂ is 40% or more. The laminate according to claim 3.

6. A method for manufacturing a sheet-like or plate-like laminate, comprising: An A layer using a polyethylene-based resin A with a biomass content of 40% or more measured by ASTM D 6866 as a base resin and a B layer using a polyethylene-based resin B with a biomass content of 20% or less measured by ASTM D 6866 as a base resin are each laminated at least one layer, at least one of the A layer and the B layer is a foamed layer, the thickness of the laminate is 2 mm or more, and the density of the laminate is 10 kg / m ３ or more and 300 kg / m ３ or less, and a method for producing a laminate having a biomass content of 5% or more measured by ASTM D 6866 of the laminate.

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