Laminated material and method for producing same

Abstract

The invention provides a laminated material which takes environmental load into consideration and can easily obtain required characteristics. The laminated material is in the form of a sheet or a plate and has at least one layer of a polyethylene resin A in which the base resin is 40% or more in biomass content as measured by ASTM D 6866, and at least one layer of a polyethylene resin B in which the base resin is 20% or less in biomass content as measured by ASTM D 6866, at least one of the layer A and the layer B is a foamed layer, and the thickness of the laminated material is 2 mm or more. The density is 10 kg / m or more and 300 kg / m or less, and the biomass content measured by ASTM D 6866 is 5% or more.

Description

Technical Field

[0001] The present disclosure relates to a laminated material and a method for manufacturing the same. Background Art

[0002] Polyethylene resin foams are widely used in various fields due to their excellent cushioning properties, such as interleaving paper between plates, packaging materials, and other logistics cushioning materials.

[0003] Polyethylene resin foams are manufactured, for example, by the following extrusion foaming method. A polyethylene resin and a bubble regulator are fed into an extruder together, heated and kneaded into a resin melt, then a physical foaming agent is pressed into the resin melt, kneaded to form a foamable resin melt, and finally the foamable resin melt is extruded from the extruder at atmospheric pressure to foam, obtaining a foam.

[0004] Polyethylene resin foams are usually made of petroleum-based polyethylene produced from fossil fuel resources. However, in recent years, due to concerns about global warming caused by the increase in the amount of carbon dioxide in the atmosphere and the depletion of fossil fuel resources, there has been an increasing desire to develop polyethylene resin foams that do not overly rely on petroleum-based polyethylene.

[0005] For example, Patent Document 1 discloses a foam that contains 50% by mass or more and 100% by mass or less of a polyolefin resin in 100% by mass of all components, wherein 25% to 80% of the polyethylene is a natural source ethylene component, 20% to 75% of the low-density polyethylene is a component produced from fossil raw materials, and the density of the foam is in the range of 20 kg / m³ to 50 kg / m³, and the biomass content measured according to ASTM D6866 (established in 2004) is 25% or more.

[0006] Prior Art Documents

[0007] Patent Documents

[0008] Patent Document 1: Japanese Patent No. 5919841 Summary of the Invention

[0009] Problems to be Solved by the Invention

[0010] However, in the invention described in Patent Document 1, since it is necessary to adjust the resin components constituting the single-layer foam in order to obtain an ideal foamed product, there are the following problems, that is, it is difficult to efficiently obtain a foamed product that satisfies various properties such as density or thickness required as a product while increasing the biomass content to reduce the environmental load.

[0011] The present invention is made based on the above situation, and its object is to provide a laminated material and a manufacturing method thereof that can reduce the environmental load and can efficiently obtain a foamed product having desired properties.

[0012] Solution to the problem

[0013] The inventors of the present invention found that by laminating multiple layers of a layer having a polyethylene resin with a biomass content (biomass degree) higher than a specific value as a base resin and a layer having a polyethylene resin with a biomass content lower than a specific value as a base resin, and forming a laminated material (for example, a laminate) in which at least one layer is a foam layer, it is possible to effectively obtain a foamed product having desired properties while increasing the biomass content, thus resulting in the present invention.

[0014] That is, the present invention provides a sheet-like or plate-like laminated material, characterized in that it has at least one A layer with a polyethylene-based resin A having a biomass content of 40% or more measured by ASTM D6866 as a base resin, and at least one B layer with a polyethylene-based resin B having a biomass content of 20% or less measured by ASTM D6866 as a base resin. At least one of the A layer or the B layer is a foam layer. The thickness of the laminated material is 2 mm or more, the density of the laminated material is 10 kg / m³ or more and 300 kg / m³ or less, and the biomass content of the laminated material measured by ASTM D6866 is 5% or more.

[0015] Preferably, the proportion of the foam layer in the laminated material is 50% by mass or more.

[0016] Preferably, at least one of the A layers is a foamed A layer as the foam layer, and at least one of the B layers is a foamed B layer as the foam layer.

[0017] Preferably, the density of the foamed A layer is 10 kg / m³ or more and 300 kg / m³ or less, and the density ratio of the foamed B layer to the density of the foamed A layer is 0.8 or more and 1.2 or less.

[0018] Preferably, the difference DA - DB between the biomass content DA of the foamed A layer and the biomass content DB of the foamed B layer is 40% or more.

[0019] In addition, the present invention provides a method for manufacturing a sheet-like or plate-like laminated material, characterized in that at least one layer of 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 at least one layer of 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 laminated respectively. At least one of the A layer and the B layer is a foamed layer. The thickness of the laminated material is 2 mm or more, the density of the laminated material is 10 kg / m³ or more and 300 kg / m³ or less, and the biomass content of the laminated material measured by ASTM D 6866 is 5% or more.

[0020] Advantages of the Invention

[0021] According to the present invention, a laminated material with reduced environmental load and easily obtainable desired properties can be obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 A schematic cross-sectional view showing one embodiment of the present invention is shown.

[0023] Figure 2 A schematic cross-sectional view showing one embodiment of the present invention is shown.

[0024] Figure 3 A schematic cross-sectional view showing one embodiment of the present invention is shown.

[0025] Figure 4 A schematic cross-sectional view showing one embodiment of the present invention is shown.

[0026] Figure 5 A schematic cross-sectional view showing one embodiment of the present invention is shown. DETAILED DESCRIPTION OF THE INVENTION

[0027] Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

[0028] [Laminated Material]

[0029] The laminated material of the present invention is a sheet-like or plate-like laminated material having at least one A layer and at least one B layer. The at least one A layer uses a polyethylene resin A with a biomass content of 40% or more measured by ASTM D 6866 as a base resin, and the at least one B layer uses a polyethylene 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 and the B layer is a foamed layer. The thickness of the laminated material is 2 mm or more, the density of the laminated material is 10 kg / m³ or more and 300 kg / m³ or less, and the biomass content of the laminated material measured by ASTM D 6866 is 5% or more.

[0030] (Layer A)

[0031] Layer A is a layer with a polyethylene resin A having a biomass content of 40% or more as measured by ASTM D 6866 as the base resin.

[0032] In the present invention, the polyethylene resin A can be, for example, 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, etc., or a mixture thereof. In addition, as long as the above biomass content requirements are met, the polyethylene resin A can use only plant-derived polyethylene resin, or can also be used in combination with plant-derived polyethylene resin and petroleum-derived polyethylene resin.

[0033] When the layer A with polyethylene resin A as the base resin is a foamed layer, from the viewpoint of more easily obtaining a foam with good cushioning properties, the polyethylene resin A is preferably mainly composed of low-density polyethylene. Specifically, the proportion of low-density polyethylene in the polyethylene resin A is preferably 50% by mass or more, more preferably 60% by mass or more, and further preferably 80% by mass or more.

[0034] In addition, from the perspective of easily increasing the biomass content of the laminate, the polyethylene resin A is preferably mainly composed of plant-derived low-density polyethylene. Specifically, the proportion of plant-derived low-density polyethylene in the polyethylene resin A is preferably 50% by mass or more, more preferably 60% by mass or more, and further preferably 80% by mass or more.

[0035] In addition, the above-mentioned low-density polyethylene refers to polyethylene having a long-chain branched structure and a density of 0.910 g / cm³ or more and less than 0.930 g / cm³.

[0036] In addition, as the plant-derived polyethylene resin, for example, it is a polyethylene resin obtained by polymerizing bio-ethylene monomers produced from plant raw materials such as sugarcane, corn, and beet. Commercially available plant-derived polyethylene resins include, for example, SEB853, SPB681, STN7006, etc., which are plant-derived low-density polyethylenes produced by Braskem.

[0037] -Biomass content-

[0038] The biomass content measured by ASTM D 6866 refers to the proportion of plant-derived components (natural components) contained in the resin, and can be determined by measuring the concentration of radioactive carbon C14.

[0039] From the perspective of easily increasing the biomass content of the laminated material, the biomass content of polyethylene resin A measured by ASTM D 6866 is preferably 50% or more, more preferably 60% or more, further preferably 70% or more, still further preferably 80% or more, and particularly preferably 90% or more.

[0040] In addition, when polyethylene resin A is composed of a mixture of multiple polyethylene resins, the biomass content of polyethylene resin A can be calculated based on the biomass content and the content ratio of each polyethylene resin contained in polyethylene resin A.

[0041] As a method for increasing the biomass content of polyethylene resin A, the following adjustments can be made: for example, by increasing the proportion of plant-derived polyethylene resin in polyethylene resin A, or by increasing the amount of bioethylene used in the production of plant-derived polyethylene resin.

[0042] -Melting point-

[0043] The melting point of polyethylene 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 polyethylene resin A as the base resin is a foaming layer, it is beneficial to obtain a foam with a good cell structure and excellent cushioning performance. From this perspective, the melting point of polyethylene resin A is preferably 105 °C or higher, more preferably 107 °C or higher. In addition, the melting point of polyethylene resin A is preferably 113 °C or lower, more preferably 112 °C or lower.

[0044] -Measurement of melting point-

[0045] The melting point of polyethylene resin A and the melting point of polyethylene resin B described below can be measured according to JIS K7121-1987. In the measurement, a specimen adjusted according to the conditions of specimen state conditioning (2) in Section 3 of JIS K 7121-1987 (cooling rate: 10 °C / minute) is used, and the melting peak is obtained at a heating rate of 10 °C / minute. The peak temperature of the obtained melting peak is regarded as the melting point. In addition, if there are two or more melting peaks, the peak temperature of the melting peak with the largest area is taken as the melting point. In addition, in this melting point measurement, samples extracted from each layer or the polyethylene resin used to form each layer can be used as specimens.

[0046] -Melt flow rate-

[0047] The melt flow rate (MFR) of polyethylene resin A is preferably 0.1 g / 10 min or more and 5 g / 10 min or less, more preferably 0.2 g / 10 min or more and 4 g / 10 min or less. Within this range, when polyethylene resin A is used as the base resin and for the foamed layer of layer A, it is easier to stably produce foamed sheets with different thicknesses and apparent densities.

[0048] The melt flow rate of the above-mentioned low-density polyethylene resin A and the melt flow rate of the low-density polyethylene resin B described below are values measured according to JIS K7210-1:2014 at a temperature of 190 °C and a load of 2.16 kg.

[0049] In addition, when polyethylene resin A is composed of a mixture of multiple polyethylene resins, during the manufacture of layer A, a mixture for measurement can be melt-kneaded in equipment such as an extruder according to the ratio of each polyethylene resin, and various measurements can be performed on this mixture to determine the melting point and melt flow rate of the polyethylene resin.

[0050] (Layer B)

[0051] Layer B is a layer with polyethylene resin B having a biomass content (measured according to ASTM D 6866) of not more than 20% as the base resin.

[0052] In the present invention, polyethylene resin B can be, for example, 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, etc. and mixtures thereof. In addition, polyethylene resin B only needs to meet the above biomass content requirements. Polyethylene resin B can be used, for example, a petroleum-based polyethylene resin or a combination of a petroleum-based polyethylene resin and a plant-based polyethylene resin.

[0053] When layer B with polyethylene resin B as the base resin is a foamed layer, to obtain a foam with good cushioning properties, polyethylene resin B is preferably mainly composed of low-density polyethylene. Specifically, the proportion of low-density polyethylene in polyethylene resin B is preferably 50% by mass or more, more preferably 60% by mass or more, and further preferably 80% by mass or more.

[0054] In addition, when layer B with polyethylene resin B as the base resin is a foamed layer, to easily obtain a foam with the required physical properties, polyethylene resin B is preferably mainly composed of petroleum-based low-density polyethylene. Specifically, the proportion of petroleum-based low-density polyethylene in polyethylene resin B is preferably 50% by mass or more, more preferably 60% by mass or more, and further preferably 80% by mass or more.

[0055] In addition, the above-mentioned low-density polyethylene refers to polyethylene having a long-chain branched structure and a density of more than 0.910 g / cm³ and less than 0.930 g / cm³.

[0056] In addition, as the polyethylene resin derived from petroleum (petroleum-based polyethylene resin), a polyethylene resin derived from fossil fuel resources manufactured using fossil fuels such as naphtha can be used.

[0057] When the B layer with polyethylene resin B as the base resin is a foamed layer, in order to easily obtain a foam with desired physical properties, the biomass content of polyethylene resin B measured according to ASTM D 6866 is preferably 15% or less, more preferably 10% or less, further preferably 5% or less, and most preferably 0%.

[0058] In addition, when polyethylene resin B is a mixture of multiple polyethylene resins, the biomass content of polyethylene resin B can be calculated based on the biomass content of each polyethylene resin contained in polyethylene resin B and the content ratio of each polyethylene resin contained in polyethylene resin B.

[0059] As a method for controlling the biomass content of polyethylene resin B below a specified value, for example, it can be adjusted by increasing the proportion of petroleum-based polyethylene resin in polyethylene resin B.

[0060] - Melting point -

[0061] The melting point of polyethylene resin B is preferably 100°C or higher and 115°C or lower. By setting it within this range, when the B layer using polyethylene resin B as the base resin is a foamed layer, it is easier to obtain a foam with a good cell structure and excellent cushioning performance. From this perspective, the melting point is preferably 113°C or lower, more preferably 112°C or lower. In addition, the melting point is preferably 105°C or higher, more preferably 107°C or higher.

[0062] - Melt flow rate -

[0063] The melt flow rate of polyethylene resin B is preferably 0.1 g / 10 minutes or higher and 5 g / 10 minutes or lower. Within this range, when the B layer using polyethylene resin B as the base resin is a foamed layer, it is easier to stably produce foamed sheets with different thicknesses and apparent densities.

[0064] In addition, when polyethylene resin B is a mixture of multiple polyethylene resins, during the manufacturing process of the B layer, a mixture for measurement can be melt-kneaded in equipment such as an extruder according to the ratio of each polyethylene resin, and various measurements can be performed on this mixture to determine the melting point and melt flow rate of polyethylene resin B.

[0065] (Foamed layer, foamed layer ratio)

[0066] In the laminated material of the present invention, at least one of layer A or layer B is a foamed layer. For example, the laminated material may be in a form where at least one of layer A is a foamed layer (a form having more than one foamed layer A), or a form where at least one of layer B is a foamed layer (a form having more than one foamed layer B). In addition, when the laminated material includes more than one foamed layer A and foamed layer B, etc., for example, it can be designed as a laminated material having 2 to 15 foamed layers. Additionally, the laminated material of the present invention may also not have a foamed layer (non-foamed layer). The non-foamed layer includes a resin film or a resin layer formed by extrusion lamination or the like for laminating and bonding layers.

[0067] From the perspective of stably producing a foamed product with desired physical properties, the proportion of the foamed layer in the laminated material of the present invention is preferably 50% by mass or more, more preferably 60% by mass or more, and further preferably 80% by mass or more. In addition, when the laminated material includes a plurality of foamed layers, the total proportion of the foamed layers in the laminated material can be regarded as the proportion of the foamed layer in the laminated material.

[0068] Furthermore, from the perspective of efficiently producing a foamed product with a desired biomass content, density, and thickness, it is preferred that at least one of layer A in the laminated material is a foamed layer A, and at least one of layer B is a foamed layer B.

[0069] In addition, within the range that can achieve the expected goal, the laminated material may also include other layers in addition to layer A or layer B.

[0070] (Density)

[0071] The density of the foamed layer A is preferably 10 kg / m³ or more and 300 kg / m³ or less, more preferably 12 kg / m³ or more and 200 kg / m³ or less, and further preferably 15 kg / m³ or more and 100 kg / m³ or less. When the density of the foamed layer A is 10 kg / m³ or more, it is easier to produce a foamed product with appropriate compressive strength. In addition, when the density of the foamed layer A is 300 kg / m³ or less, it is easier to produce a lightweight foamed product, and the foamed product has excellent cushioning performance.

[0072] Similarly, from this perspective, the density of the foamed layer B is preferably 10 kg / m³ or more and 300 kg / m³ or less, more preferably 12 kg / m³ or more and 200 kg / m³ or less, and further preferably 15 kg / m³ or more and 100 kg / m³ or less.

[0073] (Density ratio)

[0074] The density ratio of the foamed A layer to the foamed B layer is preferably 0.8 or more and 1.2 or less, more preferably 0.9 or more and 1.1 or less. By setting the density ratio within the above range, a foamed product with desired physical properties can be stably obtained.

[0075] In addition, the density of the foamed A layer can be calculated by dividing the total weight per unit area (g / m²) of the foamed A layer by the total thickness of the foamed A layer and converting it to the unit kg / m³. Similarly, the density of the foamed B layer can be calculated by dividing the total weight per unit area (g / m²) of the foamed B layer by the total thickness of the foamed B layer and converting it to the unit kg / m³. Furthermore, the weight per unit area of the foamed layer refers to the mass of the foamed layer per unit area.

[0076] (Difference in biomass content)

[0077] The difference DTA - DTB between the total biomass content DTA of layer A and the total biomass content DTB of layer B in the laminated material is preferably 40% or more, more preferably 50% or more, further preferably 60% or more, most desirably 70% or more, and particularly desirably 80% or more. When the difference in biomass content reaches 40% or more, a laminated material with a desired thickness and density can be stably produced while increasing the biomass content of the laminated material. In addition, the total biomass content DTA is the sum value of the biomass content of layer A in the laminated material calculated based on the mass ratio of each layer A constituting the laminated material. For example, after multiplying the biomass content (ratio) of each layer A constituting the laminated material by the weight per unit area of each layer A, adding these values, and then dividing by the total weight per unit area of layer A constituting the laminated material, it is obtained and expressed as a percentage. Similarly, the total biomass content DTB is the sum value of the biomass content of layer B in the laminated material calculated based on the mass ratio of each layer B constituting the laminated material. For example, after multiplying the biomass content (ratio) of each layer B constituting the laminated material by the weight per unit area of each layer B, adding these values, and then dividing by the total weight per unit area of layer B constituting the laminated material, it is obtained and expressed as a percentage.

[0078] The difference DA - DB between the biomass content DA of the foamed A layer and the biomass content DB of the foamed B layer is preferably 40% or more, more preferably 50% or more, further preferably 60% or more, most desirably 70% or more, and particularly desirably 80% or more. When the biomass content difference reaches 40% or more, a laminated material with the required thickness and density can be stably and easily produced while increasing the biomass content of the laminated material. When the laminated material includes a plurality of foamed A layers, the arithmetic average of the biomass content of the A layers in the laminated material considering the mass ratio of each A layer constituting the laminated material is taken as the biomass content DA of the foamed A layer. Similarly, when the laminated material includes a plurality of foamed B layers, the arithmetic average of the biomass content of the B layers in the laminated material considering the mass ratio of each B layer constituting the laminated material is taken as the biomass content DB of the foamed B layer.

[0079] In addition, compared with polyethylene resins with a lower biomass content, there are few resin types available for polyethylene resins with a higher biomass content. Therefore, when using a polyethylene resin with a higher biomass content to manufacture a foam, problems may be encountered in that it is difficult to extrude the resin to form a foam. Especially when attempting to manufacture a low-density foam, it is difficult to obtain a foam that meets the expected specifications.

[0080] On the other hand, by combining a polyethylene resin with a lower biomass content that is easy to extrude and foam for the foamed B layer and a foamed A layer obtained from a polyethylene resin with a higher biomass content, and when the biomass content difference DA - DB between the foamed A layer and the foamed B layer is in a predetermined relationship through stacking (laminating combination), it is possible to stably manufacture a foamed product with physical properties such as the required density while ensuring the biomass content.

[0081] On the premise of not affecting the effects of the present invention, each layer of the laminated material may further contain other components such as resins and elastomers other than polyethylene resin. At this time, the addition amount of other components is preferably not more than 40 parts by mass per 100 parts by mass of polyethylene resin, more preferably not more than 30 parts by mass, and further preferably not more than 20 parts by mass.

[0082] (Physical foaming agent)

[0083] As the physical foaming agent for forming the foamed layer, the physical foaming agents used in the manufacture of conventional polyethylene-based resin foams can be appropriately used. Examples of physical foaming agents include organic physical foaming agents and inorganic physical foaming agents.

[0084] As the organic physical foaming agent, aliphatic hydrocarbons such as propane, n-butane, isobutane, n-pentane, isopentane, n-hexane, ishexane, etc., cyclic hydrocarbons such as cyclopentane, cyclohexane, etc., chlorinated hydrocarbons such as chloromethane, chloroethane, etc., fluorinated hydrocarbons such as 1,1,1,2-tetrafluoroethane, 1,1-difluoroethane, etc., ethers such as dimethyl ether, methyl ethyl ether, etc., and alcohols such as methanol, ethanol, etc. can be used.

[0085] As the inorganic physical foaming agent, oxygen, nitrogen, carbon dioxide, air, water, etc. can be used.

[0086] These physical foaming agents can be used in combination (used in combination of two or more). Among them, from the viewpoints of extrusion foaming property and foam stability, it is preferable to use an organic physical foaming agent, and it is more preferable to use butane. Butane can be n-butane, isobutane or a mixture thereof.

[0087] The addition amount of the physical foaming agent can be adjusted according to its type, the apparent density of the target foam, the weight per unit area, etc. For example, when using a mixture of 30% by mass of isobutane and 70% by mass of n-butane as the physical foaming agent, the addition amount of the physical foaming agent is preferably 3 parts by mass or more and 35 parts by mass or less, more preferably 5 parts by mass or more and 30 parts by mass or less, and further preferably 6 parts by mass or more and 25 parts by mass or less with respect to 100 parts by mass.

[0088] (Bubble regulator)

[0089] In the present invention, a bubble regulator can be used together with low-density polyethylene. As the bubble regulator, an 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 bicarbonate (baking soda) or a baking soda-citric acid chemical foaming agent which is a mixture of sodium bicarbonate and a monovalent metal salt of citric acid such as citric acid or sodium citrate. The addition amount of the bubble regulator is preferably 0.1 part by mass to 3 parts by mass, more preferably 0.2 part by mass to 2 parts by mass per 100 parts by mass of the base resin. The addition amount within the above range helps to stably adjust the bubble size of the foaming layer to the required range.

[0090] (Other additives)

[0091] In the present invention, various additives can be added within the range that does not impair the effects of the present invention. The additives can include, for example, a shrinkage inhibitor, 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.

[0092] (Thickness of the foamed layer A and the foamed layer B)

[0093] The thickness of each foamed A layer and each foamed B layer constituting the laminated material is preferably 0.05 mm or more and 30 mm or less.

[0094] In addition, when manufacturing a relatively thin laminated material (for example, a laminated material with a thickness of 20 mm or less), the thickness of each foamed A layer and foamed B layer is preferably a sheet-like foamed layer of 0.05 mm or more and 10 mm or less.

[0095] On the other hand, when manufacturing a relatively thick laminated material (for example, a laminated material with a thickness exceeding 20 mm and not exceeding 150 mm), the thickness of each foamed A layer and foamed B layer is preferably a plate-like foamed layer of 10 mm or more and 20 mm or less.

[0096] By setting the thickness of the foamed A layer and the foamed B layer within the above range, a laminated material that meets the requirements can be efficiently manufactured.

[0097] In addition, the thickness of the foamed A layer and the foamed B layer used to form the laminated material can be determined by measuring the thickness at specified intervals (for example, every 1 cm) across the entire width of the foamed layer in the width direction orthogonal to the extrusion direction of the foamed layer and taking the arithmetic mean of the measured values. Thickness measurement can be performed using equipment such as the offline thickness gauge "TOF-4R" manufactured by Yamamoto Electric Co., Ltd.

[0098] [Physical properties of the laminated material]

[0099] The thickness of the laminated material is preferably 2 mm or more and 150 mm or less to suit various uses and required cushioning performance, etc.

[0100] In addition, for example, when a relatively thick foamed product is required, the thickness of the laminated material can be a plate-like laminated material of 10 mm or more.

[0101] The density of the laminated material is preferably 10 kg / m³ or more and 300 kg / m³ or less, more preferably 12 kg / m³ or more and 200 kg / m³ or less, and further preferably 15 kg / m³ or more and 100 kg / m³ or less. In addition, the density can be calculated by dividing the unit area weight (g / m²) of the laminated material by the thickness of the laminated material and then converting it to the unit kg / m³.

[0102] From the perspective of reducing environmental load, the biomass content of the laminated material measured by ASTM D 6866 is preferably 10% or more, more preferably 15% or more, and further preferably 20% or more. In addition, the upper limit of the biomass content can be 80%, 70%, 60%, or 50%. In addition, the biomass content of the laminated material can be determined by calculating the mass ratio of layer A and layer B and the biomass content of each layer.

[0103] [Method for manufacturing laminated material]

[0104] The method for manufacturing the laminated material of the present invention includes laminating at least one layer of layer A with a polyethylene resin A having a biomass content of 50% or more (measured by ASTM D 6866) as a base resin and at least one layer of layer B with a polyethylene resin B having a biomass content of 30% or less as a base resin, and at least one of layer A or layer B is a foamed layer. The thickness of the laminated material is 2 mm or more, the density is 10 kg / m³ or more and 300 kg / m³ or less, and the biomass content (measured by ASTM D 6866) is 5% or more.

[0105] In the method for manufacturing the laminated material of the present invention, it is preferable to laminate at least one layer of sheet-like or plate-like layer A and layer B. In addition, it is preferable that at least one layer A is a foamed layer A and at least one layer B is a foamed layer B.

[0106] For the polyethylene resin, biomass content, thickness and density of the foamed layer, etc. of layer A and layer B used for manufacturing the laminated material, reference can be made to the description of the aforementioned laminated material.

[0107] Layer A and layer B for constituting the laminated material may be films, sheets, or foams using polyethylene resin A or polyethylene resin B as a base resin. In addition, layer A and layer B may also be resin layers for interlayer adhesion.

[0108] As the foamed layer A and foamed layer B for constituting the laminated material, sheet-like foams or plate-like foams can be appropriately used.

[0109] The manufacturing of the sheet-like foam can be carried out according to the following method.

[0110] First, the materials for forming the foam, that is, polyethylene resin and other additives such as bubble regulators added as necessary, are supplied to an extruder for heating and kneading to obtain a resin melt. In addition, during the extrusion foaming process, when manufacturing a sheet-like foam with a thickness of 3 mm or more, it is preferable to add an anti-shrinkage agent to inhibit excessive shrinkage of the foam. Fatty acid esters, aliphatic amines, or fatty acid amides can be used as the anti-shrinkage agent.

[0111] Next, a physical foaming agent is pressed into the resin melt, further kneaded, and a foaming resin melt is formed in the extruder. Then, the foaming resin melt is introduced into the downstream part of the extruder provided with an annular die, and is extruded into the atmosphere through the nozzle of the annular die to foam the resin melt.

[0112] Subsequently, the tubular foam formed by extrusion foaming is expanded (blown) using a tubular expansion device (mandrel), and is pulled along the mandrel, and at the same time is cut along the extrusion direction, and a sheet-like foam can be obtained.

[0113] The plate-like foam can be produced, for example, by the following production method.

[0114] First, the polyethylene resin and bubble regulator for forming the foam layer are supplied to the extruder, and after melt kneading, a physical foaming agent is added from the middle of the extruder, and further melt kneading is performed to adjust the foamable resin melt for the foam layer.

[0115] Next, the foamable resin melt is extruded from the mold under an environment lower than the pressure in the mold (usually atmospheric pressure) to foam the foamable resin melt, thereby producing a sheet-shaped foam.

[0116] In addition, for example, the multilayer foam with multiple foam layers manufactured by coextrusion method can be used to constitute a part or all of the laminate. As an example, the multilayer foam with a foam core layer and a foam surface layer bonded to the foam core layer both sides can be manufactured using the following method.

[0117] By using an extrusion device capable of co-extrusion, a foamable resin melt for a foamed core layer obtained by kneading a polyethylene resin with a physical foaming agent, and a foamable resin melt for a foamed surface layer obtained by kneading a polyethylene resin with a physical foaming agent are co-extruded to form a tubular foam having a multilayer structure, thereby being able to manufacture a multilayer foam. In addition, additives such as an antistatic agent and an anti-shrinkage agent can be added to each foamable resin melt as needed in addition to the resin.

[0118] In the above case, as the extrusion device, for example, an annular die for coextrusion (annular die for coextrusion) is installed at the downstream part of the extruder for forming the foamed core layer, and an annular die for coextrusion is connected to the downstream part of the extruder for forming the foamed surface layer. By coextruding using the extrusion device, a cylindrical multilayer foam body is obtained, and the cylindrical multilayer foam body is cut according to the above method to produce a multilayer foam body.

[0119] In addition, a multilayer foam having a foam layer and a resin layer can also be used to form a laminate. For example, a multilayer foam having a foam layer and a resin layer bonded to both sides of the foam layer can be produced by the following method.

[0120] Using an extrusion device capable of co-extrusion, the polyethylene resin and the physical foaming agent are kneaded to obtain a foamable resin melt for the foaming layer, and the kneaded resin melt for the resin layer is co-extruded to obtain a cylindrical foam. Additives such as an antistatic agent can be added to the resin melt as needed.

[0121] In this case, as the extrusion device, an extrusion device can be used which, for example, connects an annular die for co-extrusion to the downstream part of an extruder for forming a foamed layer, while connecting another annular die for co-extrusion to the downstream part of an extruder for forming a resin layer. By co-extruding using the extrusion device, a tubular multi-layer foamed body can be obtained, and the tubular foamed body is cut according to the aforementioned method to manufacture a multi-layer foamed body. The resin layer is preferably in a non-foamed state.

[0122] There is no particular limitation on the lamination method of layer A and layer B. For example, after heating the lamination surfaces of each layer with hot air or the like, the layers are bonded by hot pressing, or a method of laminating a molten resin on the lamination surface using an extruder or the like and bonding each layer through this resin layer (referred to as extrusion coating adhesion); it is also possible to bond each layer by using an adhesive film or an adhesive, or a method of simultaneously forming and laminating and bonding layer A and layer B by co-extrusion. In addition, in the case of extrusion coating adhesion, polyethylene resin A can be used as the material of the resin layer, and the resin layer can be formed with a relatively large unit area weight, which helps to form a laminated material with a high biomass content while maintaining the required density and thickness.

[0123] When manufacturing an extruded foam by the extrusion foaming method, if an attempt is made to manufacture a foam with a large thickness and a low density, the manufacturing process often becomes more difficult. On the other hand, since the types of resins (physical properties) available for plant-derived polyethylene resins are fewer compared to petroleum-derived polyethylene resins, the degree of freedom in manufacturing the foam is reduced. Therefore, in order to obtain a foam with the required thickness, density, and biomass content, for example, when manufacturing a foam product by mixing a plant-derived polyethylene resin and a petroleum-derived polyethylene resin as a single-layer foam, it may be necessary to adjust the manufacturing conditions, such as selecting a combination of raw materials that meet the specification requirements, etc., which further increases the difficulty of manufacturing the foam. In addition, in this case, due to replacing the raw materials that meet the required specifications, the product loss may increase.

[0124] On the other hand, in the present invention, since a foam product is manufactured by forming a specific laminated material, a foam for forming the laminated material, such as a foamed layer A and a foamed layer B, can be manufactured more stably. In addition, by combining the pre-prepared layer A and layer B to form a laminated material, various specifications of foam products can be manufactured with fewer types of foams, so that a foam product with the required thickness, density, and biomass content can be manufactured efficiently.

[0125] The following is a specific example of how to obtain a foamed product with a biomass content of 45%, a density of 30 kg / m³, and different thicknesses. In this case, first prepare a foamed A layer (foamed A layer example 1) with a biomass content of 90%, a density of 30 kg / m³, and a thickness of 1 mm, a foamed B layer (foamed B layer example 1) with a biomass content of 0%, a density of 30 kg / m³, and a thickness of 1 mm, and a foamed B layer (foamed B layer example 2) with a biomass content of 0%, a density of 15 kg / m³, and a thickness of 1 mm. By laminating and bonding these prepared foamed bodies, the following foamed products can be obtained.

[0126] By laminating one layer of foamed A layer example 1 and one layer of foamed B layer example 1 to form a laminated material, a foamed product with a biomass content of 45%, a density of 30 kg / m³, and a thickness of 2 mm can be obtained. In addition, by laminating two layers of foamed A layer example 1 and two layers of foamed B layer example 1 to form a laminated material, a foamed product with a biomass content of 45%, a density of 30 kg / m³, and a thickness of 4 mm can be obtained. In addition, by laminating one layer of foamed A layer example 1 and two layers of foamed B layer example 2 to form a laminated material, a foamed product with a biomass content of 45%, a density of 30 kg / m³, and a thickness of 3 mm can be obtained.

[0127] In addition, another specific example is that by using foamed A layer example 1 and foamed B layer example 1, foamed products with a density of 30 kg / m³, a thickness of 5 mm, and different biomass contents can be obtained in the following forms.

[0128] By laminating one layer of foamed A layer example 1 and four layers of foamed B layer example 1 to form a laminated material, a foamed product with a density of 30 kg / m³, a thickness of 5 mm, and a biomass content of 18% can be obtained. In addition, by laminating two layers of foamed A layer example 1 and three layers of foamed B layer example 1 to form a laminated material, a foamed product with a density of 30 kg / m³, a thickness of 5 mm, and a biomass content of 36% can be obtained. In addition, by laminating three layers of foamed A layer example 1 and two layers of foamed B layer example 1 to form a laminated material, a foamed product with a density of 30 kg / m³, a thickness of 5 mm, and a biomass content of 54% can be obtained. In addition, by laminating four layers of foamed A layer example 1 and one layer of foamed B layer example 1 to form a laminated material, a foamed product with a density of 30 kg / m³, a thickness of 5 mm, and a biomass content of 72% can be obtained.

[0129] (Example of layer structure in laminated material)

[0130] The layer structure of the laminated material of the present invention can form a combination of layer A (foamed A layer) and layer B (foamed B layer) within the range of achieving the expected purpose of the present invention.

[0131] Figures 1 to 5 An example of the layer structure of a laminate including a foamed layer A and a foamed layer B is shown.

[0132] As Figure 1 shown, the laminate of the present invention may be a laminate 10 of two foamed layers laminated in the order of the foamed layer A (12) and the foamed layer B (11).

[0133] In addition, as Figure 2 shown, the laminate of the present invention may be a laminate 20 of three foamed layers laminated in the order of the first foamed layer B (11a), the foamed layer A (12), and the second foamed layer B (11b).

[0134] In addition, as Figure 3 shown, the laminate of the present invention may be a laminate 30 of four foamed layers laminated in the order of the first foamed layer B (11a), the first foamed layer A (12a), the second foamed layer A (12b), and the second foamed layer B (11b).

[0135] In addition, as Figure 4 shown, the laminate of the present invention may be a laminate 40 of five foamed layers laminated in the order of the first foamed layer B (11a), the first foamed layer A (12a), the second foamed layer B (11b), the second foamed layer A (12b), and the third foamed layer B (11c).

[0136] In addition, as Figure 5 shown, the laminate of the present invention may be a laminate 50 of three foamed layers laminated in the order of the first foamed layer A (12a), the foamed layer B (11), and the second foamed layer A (12b).

[0137] In addition, in Figures 1 to 5 , although each foamed layer constituting the laminate is shown, laminates including a non-foamed layer A or B layer on the surface of the foamed layer or between the foamed layers are also included in the laminates of the present invention.

[0138] When bonding a plurality of pre-prepared foamed layer A by heat fusion or the like, since the adhesiveness of these bonding surfaces is often poor, there is a risk of easy peeling, and the density of the foamed layer A during bonding may decrease, etc., the density of the entire laminate is likely to change before and after laminate bonding. From this point of view, the laminate is preferably formed by laminating and bonding the prepared foamed layer A and non-foamed layer A and / or B layer.

[0139] In addition, for example, a laminated material can be formed using a foamed A layer and a foamed B layer having a density lower than that of the foamed A layer. In this case, for example, by disposing the foamed B layer as the foamed layer on the outermost surface of the laminated material, a laminated material having a relatively soft surface layer can be formed. Or, by disposing the foamed A layer as the foamed layer on the outermost surface of the laminated material, a laminated material having a relatively smooth surface layer can be formed. In addition, by disposing the foamed B layer on one outermost surface of the laminated material and the foamed A layer on the other outermost surface, a laminated material having different surface textures on each surface can be formed.

[0140]

Examples

[0141] To form a laminated material having an A layer and a B layer, various foams were prepared using the following resins and other materials.

[0142] Plant-derived (plant-based) low-density polyethylene 1: "SEB853" produced by Braskem S.A., biomass content 95% measured by ASTM D6866, melting point 112°C, melt flow rate 2.7 g / 10 min.

[0143] Petroleum-derived (petroleum-based) low-density polyethylene 1: "NUC-8321" produced by ENEOS NUC Corporation, Japan, biomass content 0% measured by ASTM D 6866, melting point 112°C, melt flow rate 2.4 g / 10 min.

[0144] Shrinkage inhibitor (glyceryl monostearate): "S-100" produced by Riken Vitamin Co., Ltd.

[0145] Bubble regulator (talc): "High Filler #12" produced by Matsumura Sangyo Co., Ltd.

[0146] Baking soda-citric acid bubble regulator: "Fine Cell MasterPO217K" produced by Dainichi Seika Kogyo Co., Ltd.

[0147] Multi-layer foam 1: A plate-shaped multi-layer foam having three foamed layers (foamed A layer), a thickness of 20 mm, a unit area weight of 470 g / m², and an apparent density of 23.5 kg / m³, using plant-derived low-density polyethylene 1 (polyethylene resin A) as the base resin.

[0148] Multi-layer foam 2: A plate-shaped multi-layer foam having three foamed layers (foamed A layer), a thickness of 15 mm, a unit area weight of 350 g / m², and an apparent density of 23.3 kg / m³, using plant-derived low-density polyethylene 1 (polyethylene resin A) as the base resin.

[0149] Multi-layer foam 3: A sheet-like multi-layer foam with a thickness of 5 mm, a weight per unit area of 150 g / m², and an apparent density of 30 kg / m³, using plant-derived low-density polyethylene 1 (polyethylene resin A) as the base resin and having three foam layers (foam A layer).

[0150] Multi-layer foam 4: A plate-like multi-layer foam with a thickness of 20 mm, a weight per unit area of 470 g / m², and an apparent density of 23.5 kg / m³, using petroleum-derived low-density polyethylene 1 (polyethylene resin B) as the base resin and having three foam layers (foam B layer).

[0151] Multi-layer foam 5: A sheet-like multi-layer foam with a thickness of 5 mm, a weight per unit area of 150 g / m², and an apparent density of 30 kg / m³, using petroleum-derived low-density polyethylene 1 (polyethylene resin B) as the base resin and having three foam layers (foam B layer).

[0152] Foam 1: A sheet-like foam with a thickness of 2 mm, a weight per unit area of 60 g / m², and an apparent density of 30 kg / m³, using plant-derived low-density polyethylene 1 (polyethylene resin A) as the base resin.

[0153] Foam 2: A sheet-like foam with a thickness of 2 mm, a weight per unit area of 60 g / m², and an apparent density of 30 kg / m³, using petroleum-derived low-density polyethylene 1 (polyethylene resin B) as the base resin.

[0154] The above multi-layer foams 1 to 5 are manufactured by the following method.

[0155] Multi-layer foam 1:

[0156] An extrusion device equipped with a foam core layer extruder and a foam surface layer extruder is used. Specifically, the foam core layer extruder includes a first extruder with a diameter of 115 mm and a second extruder with a diameter of 180 mm connected downstream thereof, forming a series-connected extruder. In addition, a single-screw third extruder with a diameter of 115 mm is prepared as the foam surface layer extruder. A co-extrusion annular die is installed downstream of the second extruder, and the third extruder is connected to this annular die. In addition, a cooling device for cooling the outer surface of the tubular foam extruded from the die nozzle is installed downstream of the annular die. Furthermore, a mandrel (cooling tube) with a diameter of 368 mm is arranged downstream of the cooling device.

[0157] To form the foamed core layer, 99 parts by mass of plant-derived low-density polyethylene 1, 1 part by mass of glycerol monostearate as an anti-shrinkage agent, and 2 parts by mass of talc as a cell regulator are supplied together to an extruder and melt-kneaded. Then, 15% by mass of butane is added relative to 100% by mass of the foaming resin melt as a physical foaming agent, and further kneading is carried out to form a foaming resin melt for the foamed surface layer.

[0158] In addition, to form the foamed surface layer, 99 parts by mass of plant-derived low-density polyethylene 1, 1 part by mass of glycerol monostearate as an anti-shrinkage agent, and 2 parts by mass of talc as a cell regulator are supplied together to an extruder and melt-kneaded. Then, butane as a physical foaming agent is added, and its addition amount is 13% by mass of the foaming resin melt, and further kneading is carried out to form a foaming resin melt for the foamed surface layer.

[0159] These foaming resin melts are adjusted to about 112 °C, and extrusion foaming is carried out at a total discharge rate of 320 kg / hr in the ratio of foamed surface layer / foamed core layer / foamed surface layer = 1 / 6 / 1. After the extruded foam is compacted by a cooling device, it is drawn along the mandrel at a drawing speed of 10 m / min, and at the same time, the foam is cut to obtain a plate-shaped foam.

[0160] By this method, a plate-shaped multi-layer foam with a width of 1 m and a cross-sectional area of 0.02 m² in the direction orthogonal to the extrusion direction is manufactured. In addition, the foamed core layer and the two foamed surface layers constituting the multi-layer foam are both foamed A layers. Moreover, the thickness of the foamed core layer is 15 mm, and the apparent density is 23.5 kg / m³. The thickness of each foamed surface layer is 2.5 mm, and the apparent density is 23.5 kg / m³.

[0161] Multi-layer foam 2:

[0162] A plate-shaped multi-layer foam is manufactured in the same manner as multi-layer foam 1, except that the drawing speed when taking out the extruded foam is changed to 15 m / min.

[0163] Multi-layer foam 3:

[0164] A sheet-shaped multi-layer foam is manufactured in the same manner as multi-layer foam 1, except that the addition amount of butane added to the foaming resin melt for forming the foamed core layer is changed to 16% by mass, the addition amount of butane in the foaming resin melt for forming the foamed surface layer is changed to 11% by mass relative to 100% by mass of the foaming resin melt, the total discharge rate is changed to 200 kg / hr, and the drawing speed is changed to 27 m / min.

[0165] In addition, the thickness of the foamed core layer is 3.8 mm, and the apparent density is 30 kg / m³. Moreover, the thickness of each foamed surface layer is 0.6 mm, and the apparent density is 30 kg / m³.

[0166] Multi-layer foamed body 4:

[0167] Except for changing the plant-derived low-density polyethylene 1 to petroleum-derived low-density polyethylene 1, the other steps are the same as those of the multi-layer foamed body 1, and a plate-shaped multi-layer foamed body was manufactured. In addition, the foamed core layer and the two foamed surface layers constituting the multi-layer foamed body are foamed layer B.

[0168] Multi-layer foamed body 5:

[0169] Except for changing the plant-derived low-density polyethylene 1 to petroleum-derived low-density polyethylene 1, the other steps are the same as those of the multi-layer foamed body 3, and a sheet-shaped multi-layer foamed body was manufactured. In addition, the foamed core layer and the two foamed surface layers constituting the multi-layer foamed body are foamed layer B.

[0170] In addition, the above-mentioned foamed bodies 1 and 2 were manufactured by the following method.

[0171] Foamed body 1:

[0172] A tandem extruder equipped with a first extruder with an inner diameter of 90 mm and a second extruder with an inner diameter of 120 mm was prepared. An annular die was installed at the outlet of the second extruder, and a mandrel (cooling tube) with a diameter of 350 mm was arranged downstream thereof. Using this equipment, 100 parts by mass of plant-derived low-density polyethylene 1 and 1 part by mass of sodium bicarbonate-citric acid bubble regulator were supplied to the extruder, melt-kneaded, and 20% by mass of butane was added as a physical foaming agent relative to 100% by mass of the foaming resin melt and continued to be kneaded to form a foaming resin melt. Then, the foaming resin melt was adjusted to about 112 °C and extruded from the extruder at a discharge rate of 100 kg / hr. The tubular foamed body was pulled along the mandrel at a pulling speed of 50 m / min and cut to manufacture a sheet-shaped foamed body with a width of about 1 meter.

[0173] Foamed body 2:

[0174] Except for changing the plant-derived low-density polyethylene 1 to petroleum-derived low-density polyethylene 1, the other steps are the same as those of the foamed body 1, and a sheet-shaped foamed body was manufactured.

[0175] [Example 1]

[0176] Using the multi-layer foamed body 1 and the multi-layer foamed body 4, a laminated material containing 3 layers of foamed layer A and 3 layers of foamed layer B was manufactured.

[0177] Specifically, using a hot air lamination device, one side surface of the multi-layer foam 1 and the multi-layer foam 4 were heated separately, and then the heated surfaces were overlapped and pressure was applied for hot melting connection to obtain a laminated material with 6 foam layers.

[0178] The thickness of this laminated material is 40 mm, the density is 23.5 kg / m³, and the biomass content measured by ASTM D 6866 is 46%.

[0179] [Example 2]

[0180] Using 3 multi-layer foams 1 and 2 multi-layer foams 4, a laminated material containing 9 foam A layers and 6 foam B layers was manufactured.

[0181] Specifically, first using a hot air lamination device, in the order of multi-layer foam 1 / multi-layer foam 4 / multi-layer foam 1, one side surface of one multi-layer foam 1, both side surfaces of the multi-layer foam 4, and one side surface of another multi-layer foam 1 were heated separately. Then, the heated surfaces were overlapped and pressure was applied for hot melting connection to obtain a laminated material with 9 foam layers. Next, using a hot air lamination device, one side of the laminated material with 9 foam layers and the side surface of the multi-layer foam 4 of the laminated material with 6 foam layers obtained in Example 1 were heated separately, and the heated surfaces were overlapped and pressure was applied for hot melting connection to obtain a laminated material with 15 foam layers.

[0182] The thickness of this laminated material is 100 mm, the density is 23.5 kg / m³, and the biomass content measured by ASTM D 6866 is 55%.

[0183] [Example 3]

[0184] Using 2 multi-layer foams 2 and one multi-layer foam 4, a laminated material with 6 foam A layers and 3 foam B layers was manufactured.

[0185] Specifically, using a hot air lamination device, in the order of multi-layer foam 2 / multi-layer foam 4 / multi-layer foam 2, one side surface of one multi-layer foam 2, both side surfaces of the multi-layer foam 4, and one side surface of another multi-layer foam 2 were heated separately, and the heated surfaces were overlapped and pressure was applied for hot melting connection to obtain a laminated material with 9 foam layers.

[0186] The thickness of this laminated material is 50 mm, the density is 23.4 kg / m³, and the biomass content measured by ASTM D 6866 is 55%.

[0187] [Example 4]

[0188] Using foam 1 and foam 2, a laminated material with 1 foam A layer and 1 foam B layer was manufactured.

[0189] Specifically, as the resin for forming the adhesive layer, low-density polyethylene 2 derived from petroleum (produced by ENEOS NUC, NUC-8009, with a biomass content of 0% as measured by ASTM D 6866) was prepared. The resin was melted using an extrusion coating device, 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 pressed together. In this way, the foam 1 and the foam 2 were bonded together through the adhesive layer, and a laminated material with two foam layers was obtained. In addition, the laminated was carried out in such a way that the weight per unit area of the adhesive layer reached 20 g / m².

[0190] The thickness of this laminated material is 4 mm, the density is 35 kg / m³, and the biomass content as measured by ASTM D 6866 is 40%.

[0191] [Example 5]

[0192] Using the multi-layer foam 3 and two multi-layer foams 5, a laminated material with 3 foam A layers and 6 foam B layers was manufactured.

[0193] Specifically, first, low-density polyethylene 2 derived from petroleum was prepared as the resin for forming the adhesive layer. Using an extrusion coating device, as the resin melted, the molten resin was extruded between one surface of the multi-layer foam 3 and one surface of the multi-layer foam 5, and the multi-layer foam 3 and the multi-layer foam 5 were pressed together. Then, low-density polyethylene 2 derived from plants (SBC818 produced by Braskem S.A., with a biomass content of 95% as measured by ASTM D 6866) was prepared as the resin for forming the adhesive layer. Using an extrusion coating device, as the resin melted, the molten resin was extruded between the surface of the multi-layer foam 3 that had not been laminated with the multi-layer foam 5 and another multi-layer foam 5, and these were laminated together. In this way, a laminated material with 9 foam layers was finally obtained. In addition, the lamination was carried out in such a way that the weight per unit area of each adhesive layer reached 20 g / m².

[0194] The thickness of this laminated material is 15 mm, the density is 33 kg / m³, and the biomass content as measured by ASTM D 6866 is 32%.

[0195] [Example 6]

[0196] An extrusion device with a foam A layer extruder and a foam B layer extruder was used. A co-extrusion annular die was installed downstream of the foam A layer extruder, and at the same time, the downstream of the extruder for the foam B layer was connected to the annular die. In addition, a cooling pipe (mandrel) was arranged downstream of the annular die.

[0197] To form the foamed A layer, 99 parts by mass of plant-derived low-density polyethylene 1, 1 part by mass of glycerol monostearate as an anti-shrinkage agent, and 2 parts by mass of talc as a cell regulator are supplied to an extruder for melt-kneading. Then, 15% by mass of butane is added as a physical foaming agent relative to 100% by mass of the foaming resin melt, and kneading is continued to form a foaming resin melt for forming the foamed A layer.

[0198] In addition, to form the foamed B layer, 99 parts by mass of petroleum-derived low-density polyethylene 1, 1 part by mass of glycerol monostearate, and 2 parts by mass of talc are supplied to an extruder for melt-kneading. Then, 15% by mass of butane is added as a physical foaming agent relative to 100% by mass of the foaming resin melt, and kneading is continued to form a foaming resin melt for the foamed B layer.

[0199] These foaming resin melts are adjusted to about 112°C, and then extrusion foaming is performed at a total discharge rate of 200 kg / hr and a ratio of foamed A layer / foamed B layer = 1 / 1. The extruded foam is pulled along the mandrel at a pulling speed of 34 m / min, and the foam is cut to manufacture a sheet-like laminated material.

[0200] The thickness of this laminated material is 4 mm, the density is 30 kg / m³, and the biomass content measured by ASTM D 6866 is 46%. In addition, the thickness of the foamed A layer is 2 mm, the apparent density is 30 kg / m³, the thickness of the foamed B layer is 2 mm, and the apparent density is 30 kg / m³.

[0201] The laminated material of the present invention has an A layer in which at least one base resin is a polyethylene-based resin A with a biomass content of 50% or more as measured by ASTM D 6866, and a B layer in which at least one base resin is a polyethylene-based resin B with a biomass content of 30% or less as measured by ASTM D 6866. At least one of the A layer or the B layer is a foamed layer. The thickness of the laminated material is 2 mm or more, the density is 10 kg / m³ or more and 300 kg / m³ or less, and the biomass content of the laminated material measured by ASTM D 6866 is 5% or more. Therefore, compared with the method of adjusting the resin composition to obtain a single-layer foam, the present invention can more easily obtain the required properties such as the required density and thickness while increasing the biomass content.

Claims

1. A sheet-like or plate-like laminated material, characterized in that: A layer having at least one polyethylene resin A having a biomass content of 40% or more as measured by ASTM D 6866 as a base resin, and at least one polyethylene 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 laminated material is greater than 2 mm, The density of the laminated material is greater than or equal to 10 kg / m³ and less than or equal to 300 kg / m³, The biomass content of the laminated material measured by ASTM D 6866 is greater than 5%.

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

3. The laminated material according to claim 1 or 2, wherein: At least one of the A layers is a foamed A layer as the foamed layer, and at least one of the B layers is a foamed B layer as the foamed layer.

4. The laminate material according to claim 3, wherein: The density of the foamed A layer is greater than 10 kg / m³ and less than 300 kg / m³. Furthermore, the density ratio 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 laminate material according to claim 3, wherein: A difference DA-DB between the biomass content DA of the foamed A layer and the biomass content DB of the foamed B layer is greater than 40%.

6. A method for producing a sheet-like or plate-like laminated material, characterized in that: A polyethylene resin A having a biomass content of 40% or more as measured by ASTM D 6866 as a base resin layer A and a polyethylene resin B having a biomass content of 20% or less as measured by ASTM D 6866 as a base resin layer B are laminated at least one layer each, At least one of the A layer and the B layer is a foamed layer, The thickness of the laminated material is greater than 2 mm, the density of the laminated material is greater than 10 kg / m³ and less than 300 kg / m³, and the biomass content of the laminated material measured by ASTM D 6866 is greater than 5%.

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