JP2021191636A - Laminate - Google Patents

Abstract

To provide a light display member that has high light transmission and soft touch feeling.SOLUTION: Provided is a laminate, which is a laminate including a skin layer and a foam layer, and in which the total light transmittance of the foam layer is 10% or more, the Asker C hardness is 70 or less, and the total light transmittance is more than 0.01% and 4.23% or less.SELECTED DRAWING: None

Description

The present invention relates to a laminate comprising a foam layer.

In recent years, an optical display member that displays information such as temperature, time, and vehicle speed in a vehicle such as an automobile by light has been actively developed from the viewpoint of improving its performance. The optical display member needs to have excellent light transmission in order to properly display information, and since it constitutes a part of the interior of the vehicle, it maintains a flexible tactile sensation and has excellent design. A sense of luxury is required.

Effervescent foam is known as a flexible material. Effervescent foam is used in various industrial fields because it has excellent cushioning properties, heat insulating properties, etc. in addition to flexibility. In addition, a foam having improved light transmission has been developed. For example, Patent Document 1 has a closed cell structure, a total light transmittance of 15% or more, a shrinkage rate in the length direction (MD) and a width direction (TD), and an average in the length direction (MD). Polyolefin-based resin foams in which the bubble diameter, thickness, apparent density, and 25% compression hardness are adjusted to a specific range have been proposed. Further, Patent Document 2 proposes an acrylic resin foam having an average bubble diameter of 1.2 mm or more. In Cited Documents 1 and 2, the light transmittance of the foam is improved mainly by adjusting the average bubble diameter.
Further, Patent Document 3 proposes an adiabatic foam made of a thermoplastic resin having a total light transmittance of 80% or more, having a foaming magnification of 5 to 100 times, and an average cell diameter of 1 to 15 mm. Has been done. In Patent Document 3, the light transmittance of the foam is improved by using a resin having a high total light transmittance such as methyl methacrylate.

JP-A-2017-190375 Japanese Unexamined Patent Publication No. 2013-203984 Japanese Unexamined Patent Publication No. 08-067757

However, although the foams described in Patent Documents 1 to 3 have a certain degree of light transmission, from the viewpoint of achieving both high light transmission and a flexible tactile sensation when used as the above-mentioned light display member. There was room for improvement. Therefore, it is an object of the present invention to provide a laminated body having high light transmittance and a flexible tactile sensation, which is suitably used as an optical display member.

The gist of the present invention is the following [1] to [12].
[1] A laminate comprising a skin layer and a foam layer, having an Asker C hardness of 70 or less and a total light transmittance of more than 0.01%.
[2] The laminate according to the above [1], wherein the skin layer has a thickness of 0.2 to 1.0 mm.
[3] The laminate according to the above [1] or [2], wherein the total light transmittance of the epidermis layer is 0.02 to 30%.
[4] The laminate according to any one of the above [1] to [3], wherein the foam layer has a thickness of 0.5 to 5 mm.
[5] The laminate according to any one of the above [1] to [4], wherein the total light transmittance of the foam layer is 10% or more.
[6] The laminate according to any one of the above [1] to [5], wherein the foam layer has a foaming ratio of 7 to 40 times.
[7] The laminate according to any one of the above [1] to [6], wherein the foam layer is a polyolefin-based foam layer or a polyurethane-based foam layer.
[8] The laminate according to any one of the above [1] to [7], wherein the laminate further includes at least one of a print layer and a print film layer.
[9] The laminate according to the above [8], wherein the printing layer is formed by printing at least one surface of a foam layer and a skin layer.
[10] An optical display member including the laminate according to any one of the above [1] to [9].
[11] The light display member according to the above [10], which has a sensor element.
[12] The optical display member according to the above [10] or [11], comprising a display having a sensor element.

According to the present invention, it is possible to provide a laminate having high light transmission and a flexible tactile sensation.

It is sectional drawing of one Embodiment of the laminated body of this invention. It is sectional drawing of another embodiment of the laminated body of this invention. It is sectional drawing of another embodiment of the laminated body of this invention. It is a top view which shows an example of the printing layer in this invention.

[Laminate]
The present invention is a laminated body including a skin layer and a foam layer, wherein the asker C hardness of the laminated body is 70 or less and the total light transmittance is more than 0.01%. ..
FIG. 1 shows a cross-sectional view of an embodiment of the laminated body of the present invention. The laminated body of the present invention is a laminated body 10 including a skin layer 11 and a foam layer 12, and the skin layer 11 is laminated on one surface of the foam layer 12. When the laminated body 10 is used, for example, as an interior material of an automobile, the skin layer 11 is, for example, a resin sheet, and by laminating this on the foam layer 12, the user (driver or the like) can use it. It can give a sense of luxury.
Further, an LED 13 is provided on the other surface side of the foam layer 12, and the LED 13 can display necessary information such as temperature, time, and vehicle speed in a vehicle such as an automobile by emitting light. The light emitted by the LED 13 passes through the foam layer 12 and the skin layer 11, whereby the information required by a person can be sensed from the skin layer 11 side. Although the LED 13 is shown in layers in the drawings, it does not necessarily have to be layered. Further, although the LED 13 is shown so as to be provided in contact with the foam layer or the like, the LED 13 may be arranged at a certain distance from the foam layer or the like.
Since the laminated body 10 of the present invention has a total light transmittance of a certain level or more, it is easy for a person to perceive necessary information. Further, the laminated body has a soft tactile sensation because the Asker C hardness is not more than a certain value. Although FIG. 1 shows an embodiment in which the skin layer 11 and the foam layer 12 are directly laminated, even if an adhesive layer (not shown) is provided between the skin layer 11 and the foam layer 12. good.

Another embodiment of the laminate of the present invention is shown in FIG. The laminate 10 shown in FIG. 2 further includes a print layer 14. More specifically, in the laminated body 10, the skin layer 11, the foam layer 12, and the printed layer 14 are laminated in this order, and the printed layer 14 is on the surface side opposite to the surface on which the foam layer 12 is present. The LED 13 is provided. The print layer 14 has a light-shielding portion that blocks light emitted from the LED 13, and a light-transmitting portion that transmits light. By forming the light-transmitting portion into a constant character shape or the like, the light of the LED 13 is formed. The necessary information is confirmed from the epidermal layer side. An example of the top view of the print layer 14 is shown in FIG. 4, in which the black portion is the light-shielding portion and the white portion is the light-transmitting portion. In this case, the white portion (S-shaped) is the skin layer. It is sensed from the side.
In FIG. 2, the print layer 14 is a layer formed on the surface of the foam layer 12 by a known method, but the mode in which the print layer 14 is provided is not limited to this mode, and the print layer 14 is not limited to this mode. , May be formed by printing on at least one surface of the foam layer 12 and the skin layer 11.
Further, instead of the print layer 14, a print film layer on which at least one surface of the film is printed may be used. Similarly, the print film layer also has a light-shielding portion that blocks light and a light-transmitting portion that transmits light. In other words, the laminate 10 may include at least one of a print layer and a print film layer, and such a laminate 10 depends on the shape of the light transmitting portion of the print layer or the print film layer. Information can be displayed.
Further, as shown in FIG. 3, such a print layer 14 may be provided between the skin layer 11 and the foam layer 12. Further, in the laminated body 10 of FIG. 2 or FIG. 3, an adhesive layer (not shown) may be provided between the layers.

(Total light transmittance of the laminated body)
In the present invention, the total light transmittance of the laminate including the skin layer and the foam layer is more than 0.01%. When the total light transmittance of the laminated body is 0.01% or less, the light transmittance is poor and it becomes difficult to visually recognize necessary information from the skin layer side. The total light transmittance of the laminated body is preferably 0.02% or more, more preferably 0.5% or more, and further preferably 1% or more. Further, it is preferable that the laminated body senses necessary information from the epidermis layer side when it is irradiated with light from an LED or the like as described above, but when it is not irradiated with light, it foams from the epidermis layer side. It is preferable that the inside of the layer, the printing layer, the printing film layer, etc. cannot be seen through. From such a viewpoint, the total light transmittance of the laminated body is preferably 5% or less, more preferably 4% or less, and further preferably 3% or less.
The total light transmittance of the laminated body means the maximum total light transmittance of the laminated body when the laminated body includes at least one of a print layer and a print film layer. That is, the print layer and the print film layer include a light-shielding portion that does not transmit light and a light-transmitting portion that transmits light as described above, and the maximum total light transmittance of the laminated body is the light-transmitting portion. It is the total light transmittance when it is used as a measurement target.
The total light transmittance of the laminated body can be adjusted by the thickness and composition of the epidermis layer and the foam layer, which will be described later.

(Asker C hardness of laminated body)
The Asker C hardness of the laminated body in the present invention is 70 or less. If the Asker C hardness of the laminated body is more than 70, it becomes difficult to maintain a flexible tactile sensation. The Asker C hardness of the laminate is preferably 60 or less, more preferably 50 or less, and further preferably 40 or less. The lower limit of the Asker C hardness is not particularly limited, but the Asker C hardness of the laminated body is preferably 5 or more, more preferably 10 or more, from the viewpoint of maintaining a certain mechanical strength. The Asker C hardness of the laminated body can be adjusted by adjusting the thickness of the foam layer, the foaming ratio, and the like.

(Epidermis layer)
The thickness of the epidermis layer is not particularly limited as long as the total light transmittance and the Asker C hardness of the laminated body are within the above ranges, but is preferably 0.2 to 1.0 mm. By setting the thickness of the skin layer to 1.0 mm or less, it becomes easy to adjust the total light transmittance and the Asker C hardness of the laminated body within the above ranges. Further, by setting the thickness of the skin layer to 0.2 mm or more, it becomes easy to prevent the inside of the foam layer, the print layer provided as necessary, the print film layer, and the like from being seen through from the skin layer side. .. The thickness of the epidermis layer is more preferably 0.2 to 0.8 mm, still more preferably 0.2 to 0.7 mm.

The total light transmittance of the epidermis layer is preferably 0.02 to 30%. When the total light transmittance of the epidermis layer is 0.02% or more, it becomes easy to adjust the total light transmittance of the laminated body to a certain level or more as described above. When the total light transmittance of the epidermis layer is 30% or less, it becomes easy to prevent the inside of the foam layer, the print layer provided as necessary, the print film layer, and the like from being seen through from the epidermis layer side. The total light transmittance of the epidermis layer is preferably 0.05 to 25%, more preferably 0.1 to 22%.

The skin layer may contain pigments such as carbon black, titanium dioxide, pearl particles, metal powder such as aluminum powder, and the like from the viewpoint of adjusting the total light transmittance to a desired value. The epidermis layer preferably contains a resin sheet and a pigment described later, and the content of the pigment in the epidermis layer is preferably 0.01 to 3% by mass, more preferably 0.02 to 0% based on the total amount of the epidermis layer. It is 1% by mass.

The material constituting the skin layer is not particularly limited, and examples thereof include polypropylene sheets, polyethylene sheets, olefin-based thermoplastic elastomer (TPO) sheets, polyvinyl chloride sheets, and mixed resin sheets of polyvinyl chloride and ABS resin. Examples thereof include resin sheets, textiles using natural fibers and artificial fibers, knitted fabrics, non-woven fabrics, and leathers such as artificial leather and synthetic leather.
Among these, a resin sheet is preferable, a polypropylene sheet and an olefin-based thermoplastic elastomer sheet are preferable, and an olefin-based thermoplastic elastomer sheet is more preferable, from the viewpoint of easily adjusting the total light transmittance to a desired range.
From the viewpoint of enhancing the design, a grain pattern may be formed on the surface of the epidermis layer. Further, the surface of the epidermis layer may be coated with a lenticel or a wood grain pattern by using a silicone stamper or the like having irregularities transferred from genuine leather, stone, wood or the like.
Further, from the viewpoint of preventing scratches, various coatings may be applied to the surface of the epidermis layer.

(Effervescent layer)
The foam layer constituting the laminated body in the present invention will be described below.

<Thickness>
The thickness of the foam layer is not particularly limited as long as the total light transmittance and the Asker C hardness of the laminate are within the above ranges, but is preferably 0.5 to 5 mm. By setting the thickness of the foam layer to 0.5 mm or more, the tactile sensation of the laminated body tends to be flexible. Further, by setting the thickness of the foam layer to 5 mm or less, it becomes easy to adjust the total light transmittance of the laminated body within the above range. The thickness of the foam layer is preferably 0.5 to 4 mm, more preferably 0.6 to 3.5 mm.

<Total light transmittance>
The total light transmittance of the foam layer is preferably 10% or more. When the total light transmittance of the foam layer is 10% or more, it becomes easy to adjust the total light transmittance of the laminated body within the above range. The total light transmittance of the foam layer is more preferably 20% or more, still more preferably 30% or more. The higher the total light transmittance of the foam layer, the better, but it is usually 95% or less.

<Effervescence magnification>
The foaming ratio of the foam layer is not particularly limited, but is preferably 7 to 40 times. When the foaming ratio is 7 times or more, the Asker C hardness of the laminated body becomes low, the tactile sensation tends to be flexible, and the total light transmittance of the laminated body also becomes easy to adjust within the above range. By setting the foaming ratio of the foam layer to 40 times or less, the mechanical strength of the laminated body can be set to a certain level or higher. The foaming ratio of the foam layer is more preferably 10 to 35 times, still more preferably 12 to 33 times.

<Crosslinking degree (gel fraction)>
The degree of cross-linking (gel fraction) of the polyolefin-based foam layer is preferably 5 to 60% by mass. When the gel fraction is at least the above lower limit value, sufficient cross-linking is formed in the foam layer, so that the mechanical strength tends to be high. Further, when the degree of cross-linking is not more than these upper limit values, it becomes easy to secure a flexible tactile sensation. From such a viewpoint, the degree of cross-linking is more preferably 10 to 50% by mass, further preferably 10 to 40% by mass. The degree of cross-linking can be measured by a measuring method described later.

<Material>
The foam layer is preferably formed of a resin, specifically, a polyolefin-based foam layer or a polyurethane-based foam layer is preferable, and a polyolefin-based foam layer is more preferable. The polyolefin-based foam layer is formed by foaming a foamable resin composition containing a polyolefin resin, and examples of the polyolefin resin include polypropylene resin, polyethylene resin, ethylene-vinyl acetate copolymer, and the like. May be used alone or in combination of two or more.
It is preferable that only one type of resin is used to form the foam layer. By using only one type, fogging due to blending is less likely to occur, and the light transmission of the foam layer can be enhanced.
The foam layer may be a single-layer foam layer or a multi-layer foam layer in which two or more foams are laminated. The individual foams constituting the multi-layered foam layer may have different physical characteristics such as composition, thickness, total light transmittance, foaming magnification, and degree of cross-linking, and the multi-layered foam layer as a whole may have different physical characteristics. It is preferable to satisfy the physical properties.

≪Polyethylene resin≫
The polyethylene resins, low density polyethylene resin (0.93 g / cm ³ or less, LDPE), medium density polyethylene resin (greater than 0.930g / cm ³ 0.942g / cm less than ^3, MDPE), high density polyethylene resin ( 0.942 g / cm ³ or more, HDPE). Further, as a preferable specific example of the low density polyethylene resin, a linear low density polyethylene resin (LLDPE) can be mentioned.

The polyethylene resin may be a homopolymer of ethylene, but a copolymer of ethylene and a small amount of α-olefin containing ethylene as a main component (preferably 75% by mass or more, more preferably 90% by mass or more of all the monomers) or the like. But it may be. Examples of the α-olefin include those having 3 to 12 carbon atoms, more preferably 4 to 10 carbon atoms, and specifically, 1-butene, 1-pentene, 1-hexene and 4-methyl-1. -Pentene, 1-hexene, 1-octene and the like can be mentioned. In the copolymer, these α-olefins can be used alone or in combination of two or more.
Further, the polyethylene resin may be used alone or in combination of two or more.

≪Polypropylene resin≫
The polypropylene resin may be homopolypropylene, which is a homopolymer of propylene, or propylene and a small amount of ethylene containing propylene as a main component (preferably 75% by mass or more, more preferably 90% by mass or more of all the monomers). Examples thereof include a copolymer with α-olefin other than propylene.
Examples of the copolymer of propylene and α-olefin other than ethylene and propylene include block copolymers (block polypropylene), random copolymers (random polypropylene), and random block copolymers.
Examples of α-olefins other than propylene include α-olefins having 4 to 10 carbon atoms such as 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-heptene, and 1-octene. Among these, ethylene is preferable from the viewpoint of moldability and heat resistance. In the copolymer, these α-olefins can be used alone or in combination of two or more.
Further, the polypropylene resin may be used alone or in combination of two or more.

In the present invention, any of a polyethylene resin, a polypropylene resin, or a mixture thereof polymerized with a polymerization catalyst such as a Cheegler-Natta compound, a metallocene compound, and a chromium oxide compound may be used.

≪Ethylene-vinyl acetate copolymer≫
Examples of the ethylene-vinyl acetate copolymer used as the polyolefin resin include an ethylene-vinyl acetate copolymer containing 50% by mass or more of a structural unit derived from ethylene. Since the ethylene-vinyl acetate copolymer has high compatibility with the polyethylene resin and the polypropylene resin, the ethylene-vinyl acetate copolymer can be used in combination with one or more selected from the polyethylene resin and the polypropylene resin.
The density of the ethylene-vinyl acetate copolymer is preferably 0.92 g / cm ³ or more, more preferably 0.93 g / cm ³ or more, still more preferably 0.94 g / cm ³ or more, and preferably 0. .97g / cm ³ or less, more preferably 0.96 g / cm ³ or less.

The polyolefin-based foam layer may be composed of only the above-mentioned polyolefin resin, or may be a mixture of the polyolefin-based resin and the elastomer. Examples of the elastomer include ethylene-propylene-diene rubber (EPDM), ethylene-propylene rubber (EPM), and styrene rubber. Further, examples of the elastomer include thermoplastic elastomers. Examples of the thermoplastic elastomer include olefin-based thermoplastic elastomers and styrene-based thermoplastic elastomers.
The content of the polyolefin resin in the polyolefin-based foam layer is preferably 50% by mass or more, more preferably 70% by mass or more, still more preferably 90% by mass or more, based on the total amount of the foam layer.

The polyurethane-based foam layer is formed of a polyurethane resin, and is formed by foaming an effervescent resin composition containing a polyol compound and a polyisocyanate compound, as will be described later.
The content of the polyurethane resin in the polyolefin-based foam layer is preferably 50% by mass or more, more preferably 70% by mass or more, still more preferably 90% by mass or more, based on the total amount of the foam layer.

[Manufacturing of foam layer]
The foam layer in the present invention is formed by foaming a foamable resin composition. Examples of the foaming method include a method of foaming using a pyrolytic foaming agent, a foaming agent such as water, and a method of foaming using an inert gas such as carbon dioxide and butane gas, as described later.

(Manufacturing of polyolefin-based foam layer)
The polyolefin-based foam layer is produced, for example, by foaming a foamable resin composition containing the above-mentioned polyolefin resin and a foaming agent. Examples of the foaming agent include a chemical foaming agent and a physical foaming agent.

<Effervescent agent>
As the chemical foaming agent, a pyrolytic foaming agent is preferable. As the pyrolytic foaming agent, an organic foaming agent and an inorganic foaming agent can be used. Examples of the organic foaming agent include azodicarboxylic amides, azodicarboxylic acid metal salts (azodicarboxylic acid barium, etc.), azo compounds such as azobisisobutyronitrile, nitroso compounds such as N, N'-dinitrosopentamethylenetetramine, and hydrazine. Examples thereof include zodicarboxylic amides, hydrazine derivatives such as 4,4'-oxybis (benzenesulfonyl hydrazide) and toluenesulfonyl hydrazide, and semicarbazide compounds such as toluenesulfonyl semicarbazide.
Examples of the inorganic foaming agent include ammonium carbonate, sodium carbonate, ammonium hydrogencarbonate, sodium hydrogencarbonate, ammonium nitrite, sodium boron hydride, anhydrous monosoda citrate and the like.
Among these, azo compounds are preferable, and azodicarbonamides are more preferable, from the viewpoint of obtaining fine bubbles, economy, and safety.
One type of pyrolysis foaming agent may be used alone, or two or more types may be used in combination.
Examples of the physical foaming agent include an inert gas described later.

The content of the foaming agent in the effervescent resin composition is preferably 1 to 30 parts by mass, more preferably 2 to 25 parts by mass, still more preferably 2 to 20 parts by mass with respect to 100 parts by mass of the polyolefin resin. By setting the blending amount of the foaming agent to 1 part by mass or more, the foam layer is appropriately foamed, and it becomes possible to impart a certain degree of flexibility. Further, by setting the blending amount of the foaming agent to 30 parts by mass or less, the foam layer can be prevented from foaming more than necessary, and the mechanical strength of the foam layer can be improved.

<Nucleating agent>
The effervescent fat composition may contain a nucleating agent. The nucleating agent is not particularly limited as long as it has the effect of improving the progress rate of the crystal nucleation process. By adding a nucleating agent to a polyolefin resin such as a polyethylene resin or a polypropylene resin, the size of the resulting crystals can be reduced, so that the transparency of the foam layer is improved.
Examples of the nucleating agent include substances having an effect of improving the progress rate of the crystal nucleation process and having an effect of promoting the molecular chain orientation through the process of adsorbing the molecular chain of the polymer.
More specifically, a refractory polymer, an organic carboxylic acid or a metal salt thereof, an aliphatic alcohol group, dibenzylidene sorbitol or a derivative thereof, a partial metal salt of loginic acid, an amide compound, inorganic fine particles, an organic phosphoric acid compound or a metal salt thereof. , Imidos, quinacridones, quinones, aromatic sulfonates or metal salts thereof, saccharides, and mixtures thereof. These may be used alone or in combination of two or more.

<Additives>
The effervescent resin composition may contain components such as a cross-linking aid, a decomposition temperature adjusting agent, and an antioxidant.
As the cross-linking aid, a polyfunctional monomer can be used. By adding the cross-linking aid to the polyolefin resin, the amount of ionizing radiation irradiated in the step (2) described later is reduced, and the resin molecules are prevented from being cut or deteriorated by the irradiation of the ionizing radiation.
Specific examples of the cross-linking aid include one molecule such as trimethylolpropanetrimethacrylate, trimethylolpropanetriacrylate, trimellitic acid triallyl ester, 1,2,4-benzenetricarboxylic acid triallyl ester, and triallyl isocyanurate. A compound having three functional groups in it, or two in one molecule such as 1,6-hexanediol dimethacrylate, 1,9-nonanediol dimethacrylate, 1,10-decanediol dimethacrylate, and divinylbenzene. Examples thereof include compounds having a functional group, diallyl phthalate, diallyl terephthalate, diallyl isophthalate, ethyl vinylbenzene, neopentyl glycol dimethacrylate, lauryl methacrylate, stearyl methacrylate and the like.
These cross-linking aids may be used alone or in combination of two or more.

The amount of the cross-linking aid added is preferably 0.5 to 10 parts by mass, more preferably 1.0 to 8 parts by mass, and even more preferably 1.5 to 5 parts by mass with respect to 100 parts by mass of the polyolefin resin. When the addition amount is 0.5 parts by mass or more, the desired degree of cross-linking of the foam layer can be stably obtained, and when the addition amount is 10 parts by mass or less, the degree of cross-linking of the foam layer can be easily controlled. Will be.

The effervescent resin composition may contain a decomposition temperature adjusting agent. The decomposition temperature adjusting agent is compounded as a compound for lowering the decomposition temperature of the thermally decomposing foaming agent and increasing or adjusting the decomposition rate, and specific compounds include zinc oxide, zinc stearate, and urea. And so on. The decomposition temperature adjusting agent is blended in an amount of 0.01 to 5 parts by mass with respect to 100 parts by mass of the polyolefin resin, for example, in order to adjust the surface condition of the foam layer.

The effervescent resin composition may contain an antioxidant. Examples of the antioxidant include phenolic antioxidants such as 2,6-di-t-butyl-p-cresol and pentaerythritol tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate]. Examples thereof include sulfur-based antioxidants such as dilaurylthiodipropionate, phosphorus-based antioxidants, and amine-based antioxidants. For example, the antioxidant is blended in an amount of 0.01 to 5 parts by mass with respect to 100 parts by mass of the polyolefin resin.
In addition to these, the effervescent resin composition may contain additives generally used for foams such as heat stabilizers, colorants, flame retardants, antistatic agents, and fillers.

(Manufacturing process of polyolefin-based foam layer)
The method for producing the polyolefin-based foam layer is not particularly limited, but at least a foamable sheet made of a foamable resin composition containing a polyolefin resin and a pyrolysis-type foaming agent is heated to foam the pyrolysis-type foaming agent. Can be manufactured. More specifically, the production method preferably includes the following steps (1) to (3).
Step (1): Step of forming an effervescent sheet made of an effervescent resin composition containing at least a polyolefin resin and a pyrolytic foaming agent Step (2): Irradiating the effervescent sheet with ionizing radiation to form an effervescent sheet. Crosslinking Step Step (3): A step of heating the crosslinked foamable sheet to foam a pyrolysis foaming agent to obtain a foam layer.

In the step (1), the method for forming the foamable sheet is not particularly limited, and for example, a polyolefin resin, a pyrolytic foaming agent, a nucleating agent to be blended as necessary, and an additive are supplied to the extruder. Then, it may be melt-kneaded and molded by extruding the foamable resin composition into a sheet from an extruder. Further, the foam layer may be formed by pressing an effervescent resin composition or the like.
The molding temperature of the foamable resin composition (that is, the temperature at the time of extrusion or the temperature at the time of pressing) is preferably 50 ° C. or higher and 250 ° C. or lower, and more preferably 80 ° C. or higher and 180 ° C. or lower.

As a method for cross-linking the foamable sheet in the step (2), a method of irradiating the foamable sheet with ionizing radiation such as electron beam, α ray, β ray, and γ ray is used. The irradiation amount of the ionizing radiation may be adjusted so that the degree of cross-linking of the obtained foam layer is within the above-mentioned desired range, but is preferably 1 to 9 Mrad, and preferably 1.9 to 5 Mrad. More preferred.

In the step (3), the heating temperature when the foamable sheet is heated to foam the pyrolyzable foaming agent may be equal to or higher than the foaming temperature of the pyrolyzable foaming agent, but is preferably 200 to 300 ° C., more preferably. Is 220 to 280 ° C.

Further, in the present production method, the foamable sheet may be stretched to either one or both of MD and TD. The effervescent sheet may be stretched after the effervescent sheet is foamed to obtain a foam layer, or the effervescent sheet may be stretched while being foamed. When the foam layer is stretched after the foamable sheet is foamed to obtain the foam layer, the foam layer is continuously formed without cooling the foam layer while maintaining the molten state at the time of foaming. It may be stretched, or after cooling the foam layer, the foam layer may be heated again to be in a melted or softened state, and then the foam may be stretched. By stretching the foam layer, it becomes easy to make it thin. Further, the foam layer may be heated to, for example, 100 to 280 ° C, preferably 150 to 260 ° C during stretching. In the present invention, by stretching, the bubble diameter of the foam becomes large along one or both of MD and TD, and the light transmission tends to be high.

However, in the above steps (1) to (3), instead of irradiating with ionizing radiation, an organic peroxide is mixed in advance with the polyolefin-based resin composition, and the foamable sheet is heated to heat the organic peroxide. Cross-linking may be performed by a method of decomposing.

The method for producing the polyolefin-based foam layer is not limited to the method of performing the above steps (1) to (3), and may be foamed by performing physical foaming.
When foaming by physical foaming, it is preferable to impregnate the resin composition containing the polyolefin resin, the nucleating agent to be blended if necessary, and the additive with the physical foaming agent. The impregnation with the physical foaming agent is preferably performed after the resin composition is molded into a sheet. The resin composition may be formed into a sheet, irradiated with an electron beam, and then impregnated with a physical foaming agent. The same method as in the above step (2) can be used for electron beam irradiation.
As the physical foaming agent, it is preferable to use a high-pressure inert gas. The inert gas is not particularly limited as long as it is inert to the resin composition and can be impregnated, and examples thereof include carbon dioxide, butane gas, nitrogen gas, and air. These gases may be mixed and used. Of these, carbon dioxide and butane gas are preferable from the viewpoint of easily increasing the foaming ratio of the foam layer. The inert gas to be impregnated is preferably in a supercritical state or a subcritical state.

(Manufacturing of polyurethane foam layer)
The polyurethane-based foam layer is obtained by foaming and curing a foamable resin composition containing a polyol compound, an isocyanate compound, and a foaming agent.

<Polyol compound>
Examples of the polyol compound include polylactone polyols, polycarbonate polyols, aromatic polyols, alicyclic polyols, aliphatic polyols, polyester polyols, and polyether polyols. The above-mentioned polyol compound may be a polymer polyol. Only one kind of the above-mentioned polyol compound may be used, or two or more kinds thereof may be used in combination.

Examples of the polylactone polyol include polypropiolactone glycol, polycaprolactone glycol, polyvalerolactone glycol and the like.

Examples of the polycarbonate polyol include a dealcohol reaction product of a hydroxyl group-containing compound and a carbonate compound. Examples of the hydroxyl group-containing compound include ethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol, octanediol, and nonanediol. Examples of the carbonate compound include diethylene carbonate and dipropylene carbonate.

Examples of the aromatic polyol include bisphenol A, bisphenol F, phenol novolak, and cresol novolak.

Examples of the alicyclic polyol include cyclohexanediol, methylcyclohexanediol, isophoronediol, dicyclohexylmethanediol, and dimethyldicyclohexylmethanediol.

Examples of the aliphatic polyol include ethylene glycol, propylene glycol, butanediol, pentanediol, and hexanediol.

Examples of the polyester polyol include a dehydration condensate of a polybasic acid and a polyhydric alcohol, a ring-opening polymer of a lactone, and a condensate of a hydroxycarboxylic acid and a polyhydric alcohol. Examples of the polybasic acid include adipic acid, azelaic acid, sebacic acid, terephthalic acid, isophthalic acid, and succinic acid. Examples of the polyhydric alcohol include bisphenol A, ethylene glycol, propylene glycol, butanediol, diethylene glycol, hexaneglycol, neopentyl glycol and the like. Examples of the lactone include ε-caprolactone and α-methyl-ε-caprolactone. Examples of the hydroxycarboxylic acid include castor oil and reaction products of castor oil and ethylene glycol.

Examples of the above-mentioned polyether polyol include a ring-opening polymer of an active hydrogen compound having two or more active hydrogen atoms and an alkylene oxide. Examples of the alkylene oxide include ethylene oxide, propylene oxide and tetrahydrofuran. The molecular weight of the active hydrogen compound is preferably low. Examples of the active hydrogen compound include diol compounds such as bisphenol A, ethylene glycol, propylene glycol, butylene glycol, and 1,6-hexanediol, triol compounds such as glycerin and trimethylolpropane, and amines such as ethylenediamine and butylene diamine. Examples include compounds.

Examples of the polymer polyol include a graft polymer obtained by graft-polymerizing an unsaturated organic compound on a polyol compound, a polybutadiene polyol, a modified polyol of a polyhydric alcohol, and hydrogenated additives thereof.

In the graft polymer, examples of the polyol compound include aromatic polyols, alicyclic polyols, aliphatic polyols, polyester polyols, and polyether polyols. Examples of the unsaturated organic compound include acrylonitrile, styrene, and methyl (meth) acrylate.

Examples of the modified polyol of the polyhydric alcohol include a reaction-modified product of the polyhydric alcohol and an alkylene oxide. Examples of the polyhydric alcohol include trihydric alcohols such as glycerin and trimethylolpropane, pentaerythritol, sorbitol, mannitol, sorbitan, diglycerin, dipentaerythritol, sucrose, glucose, mannose, fructose, methyl glucoside and derivatives thereof. Alcohols with 4 or more and 9 or less valences, phenol, fluoroglycercin, cresol, pyrogallol, catechol, hydroquinone, bisphenol A, bisphenol F, bisphenol S, 1-hydroxynaphthalene, 1,3,6,8-tetrahydroxynaphthalene, anthrol , 1,4,5,8-Tetrahydroxyanthracene, and phenolic compounds such as 1-hydroxypyrene, polybutadiene polyols, castor oil polyols, (co) polymers of hydroxyalkyl (meth) acrylates, polyfunctionals such as polyvinyl alcohols (eg). (The number of functional groups is 2 or more and 100 or less), polyols, condensates of phenol and formaldehyde (Novolak), and the like can be mentioned. Examples of the alkylene oxide include alkylene oxides having 2 or more carbon atoms and 6 or less carbon atoms. Specific examples of the alkylene oxide include ethylene oxide, 1,2-propylene oxide, 1,3-propylene oxide, 1,2-butylene oxide, and 1,4-butylene oxide. From the viewpoint of improving the properties and reactivity, the alkylene oxide is preferably 1,2-propylene oxide, ethylene oxide or 1,2-butylene oxide, and is 1,2-propylene oxide or ethylene oxide. Is more preferable. Only one kind of the above alkylene oxide may be used, or two or more kinds thereof may be used in combination.

<Polyisocyanate compound>
Examples of the polyisocyanate compound include aromatic polyisocyanates, alicyclic polyisocyanates, and aliphatic polyisocyanates.

Examples of the aromatic polyisocyanate include phenylenediocyanate, tolylene diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate, dimethyldiphenylmethane diisocyanate, triphenylmethane triisocyanate, naphthalene diisocyanate, and polymethylene polyphenyl polyisocyanate.

Examples of the alicyclic polyisocyanate include cyclohexylene diisocyanate, methylcyclohexylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, and dimethyldicyclohexylmethane diisocyanate.

Examples of the aliphatic polyisocyanate include methylene diisocyanate, ethylene diisocyanate, propylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate and the like.

The content of the isocyanate compound is preferably 10 parts by mass or more, more preferably 15 parts by mass or more, preferably 35 parts by mass or less, and more preferably 30 parts by mass or less with respect to 100 parts by mass of the polyol compound.

<Effervescent agent>
Examples of the foaming agent for producing the polyurethane-based foam layer include water and organic halogen compounds.

Examples of the organic halogen compound include an organic chlorine compound and an organic fluorine compound.
Examples of the organochlorine compound include dichloroethane, propyl chloride, isopropyl chloride, butyl chloride, isobutyl chloride, pentyl chloride, isopentyl chloride and the like.
Examples of the organic fluorine compound include difluoromethane (HFC32), 1,1,1,2,2-pentafluoroethane (HFC125), 1,1,1-trifluoroethane (HFC143a), 1,1,2, 2-Tetrafluoroethane (HFC134), 1,1,1,2-tetrafluoroethane (HFC134a), 1,1-difluoroethane (HFC152a), 1,1,1,2,3,3,3-heptafluoropropane (HFC227ea), 1,1,1,3,3-pentafluopropane (HFC245fa), 1,1,1,3,3-pentafluobtan (HFC365mfc) and 1,1,1,2,2,3 , 4, 5, 5, 5-decafluoropentane (HFC4310mee) and the like.

The content of the foaming agent may be appropriately adjusted according to the type of the foaming agent. When water is used as the foaming agent, the foaming agent may be preferably 1 to 10 parts by mass, more preferably 1 to 5 parts by mass, based on 100 parts by mass of the total of the polyol compound and the polyisocyanate compound. When an organic halogen compound is used as the foaming agent, the foaming agent may be preferably 1 to 10 parts by mass, more preferably 1 to 5 parts by mass, based on 100 parts by mass of the total of the polyol compound and the polyisocyanate compound. good. When water and an organic halogen compound are used as the foaming agent, it is preferable to adjust the blending amount so that each of them is in the above range.

<Catalyst>
The effervescent resin composition may contain a catalyst. Examples of the catalyst include a urethanization catalyst, a quantification catalyst and the like. Examples of the urethanization catalyst include an amine catalyst and the like. Examples of the trimerization catalyst include aromatic compounds, alkali metal salts of carboxylic acids, quaternary ammonium salts of carboxylic acids, and quaternary ammonium salt / ethylene glycol mixtures.
The content (total amount) of the catalyst is preferably 0.05 to 1 part by mass with respect to 100 parts by mass of the total of the polyol compound and the polyisocyanate compound.

In addition to the above, the effervescent resin composition for producing the polyurethane foam layer includes decomposition temperature control agents, antioxidants, heat stabilizers, colorants, flame retardants, antistatic agents, fillers and the like. May be contained.

The polyurethane-based foam layer can be obtained by foaming and curing the above-mentioned foamable resin composition. For example, the effervescent resin composition can be injected into a mold and heated to effervescent and cure. After foaming and curing the effervescent resin composition, the thickness of the foam layer may be adjusted by slicing the obtained cured product to a desired thickness.

(Print layer, print film layer)
As described above, the laminate of the present invention may include at least one of a print layer and a print film layer. As a result, the shape corresponding to the printing pattern can be sensed from the skin layer side by the light. The print layer can be formed, for example, by printing on one side of the foam layer. The print film layer is formed by forming a print layer on a base film such as a polyester film such as a polyolefin film and a PET film. As a method for forming the print layer, a known method such as an inkjet method can be appropriately used. The thickness of the print layer is preferably 1 to 25 μm, more preferably 2 to 10 μm. The thickness of the print film layer is preferably 4 to 50 μm, more preferably 12 to 25 μm.

Even if the laminated body is not provided with the print layer and the print film layer, the character information can be visually recognized from the skin layer side by irradiating the light emitted from the foam layer side so as to display a certain character information. Is possible.

(Manufacturing of laminated body)
The laminate of the present invention can be produced, for example, by laminating a foam layer, a skin layer, and a printing film layer provided as needed. The specific layer structure is as described above. As the foam layer, one in which a printed layer is formed may be used. For laminating, a thermal laminating method may be used, or the layers may be adhered to each other with an adhesive.

(Light display member)
The laminated body of the present invention can be suitably used as an optical display member. That is, it is preferable to use an optical display member including a laminated body. The configuration of the optical display member is not particularly limited, but it is preferable to include a laminated body and an information display component, and for example, the optical display member in which the skin layer, the foam layer, and the information display component are laminated in this order. Can be done. Examples of the information display component include a display, an arranged LED, and the like. The arranged LEDs are those in which a plurality of LEDs are arranged in a specific shape in order to display specific information.
The optical display member may have a sensor element, and for example, the information display component may be a display having a sensor element such as a touch panel.
The optical display member is suitably used for vehicles such as automobiles, displays necessary information such as temperature, time, vehicle speed, danger, safety, and notice, and is used as a member for design and lighting. Is preferable.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited thereto.

The evaluation method is as follows.
<Asker C hardness>
Using an Asker rubber hardness tester C type (manufactured by Polymer Meter Co., Ltd.), the needle of the hardness tester was brought into contact with the epidermis layer of the laminate for measurement. The measurement was performed at 25 ° C.

<Effervescence magnification>
The foaming ratio was calculated by obtaining the density (apparent density) of the foam layer and calculating the reciprocal of the density. The apparent density was measured according to JIS K7222: 2005.

<Gel fraction (crosslinking degree)>
About 100 mg of the test piece was collected from the foam layer, and the weight A (mg) of the test piece was precisely weighed. ^{Next, this test piece was immersed in 30 cm 3} of xylene at 120 ° C. and left for 24 hours, then filtered through a 200 mesh wire mesh to collect the insoluble matter on the wire mesh, vacuum dried, and the weight of the insoluble matter. B (mg) was precisely weighed. From the obtained values, the degree of cross-linking (mass%) was calculated by the following formula.
Degree of cross-linking (% by mass) = (B / A) x 100

<Total light transmittance>
Total light transmittance was measured using a haze meter in accordance with ASTM D1003.

<Evaluation of sheer feeling>
The inside was visually inspected from the epidermis layer side, and the evaluation was made based on the degree of visibility of the foam layer.
〇 ・ ・ The foam layer cannot be seen at all △ ・ ・ Part of the foam layer can be seen × ・ ・ The entire foam layer can be seen

<Raw materials used for the foam layer>
The materials used in the examples and comparative examples are as follows.
[Polyolefin resin]
Polypropylene resin (PP): "Nobren AD571" manufactured by Sumitomo Chemical Co., Ltd. (density: 0.900 g / cm ³ )
Polyethylene resin (LLDPE, linear low density polyethylene): Tosoh Corporation "Niporon-Z ZF231B" (density: 0.917 g / cm ³ )
Polyethylene resin (LDPE (1), low density polyethylene): Ube Maruzen Polyethylene Co., Ltd. "UBE Polyethylene F522N" (Density: 0.922 g / cm ³ )
Polyethylene resin (LDPE (2), low density polyethylene): sdavi "1905UO" density: 0.920 g / cm ³ )
EVA: Tosoh Corporation "Ultrasen 636" (Density: 0.941 g / cm ³ )

[Polyurethane resin]
Polyol compound (1): Sanyo Kasei GP3000
Polyester compound (2): Ethylene glycol polyisocyanate compound: Nippon Polyurethane Coronate T-80

[Effervescent agent]
Azodicarbonamide (1): Eiwa Kasei Co., Ltd. "AC # R" (azodicarbonamide)
Azodicarbonamide (2): Otsuka Chemical Co., Ltd. "SO-L" (azodicarbonamide)
water

Crosslinking aid: Kyoeisha Chemical "Light Ester 1.9-ND" (1,9-nonanediol dimethacrylate)
Antioxidant: BASF Japan "Irganox 1010"
Decomposition temperature adjuster: Sakai Chemical "Zinc oxide type II"
Catalyst: Nitto Kasei "U-28"
Defoamer: Momentive "L-626"

<Epidermis layer>
The skin layer used in Examples and Comparative Examples contains a pigment masterbatch (PEX99901 manufactured by Tokyo Ink Co., Ltd.) containing 40 wt% of a pigment (carbon black) and an olefin-based thermoplastic elastomer (TPO). The blending amount of the pigment masterbatch and the pigment content were adjusted as shown in Table 1. The content of the pigment shown in Table 1 is a value based on the total amount of the epidermis layer.

(Example 1)
85 parts by mass of polypropylene resin (PP), 15 parts by mass of polyethylene resin (LLDPE), 6 parts by mass of foaming agent, 3 parts by mass of cross-linking aid, and 0.5 parts by mass of antioxidant are melt-kneaded and then pressed. A foamable sheet was obtained. Both sides of the obtained foamable sheet were irradiated with an electron beam for 2Mrad at an acceleration voltage of 800 keV to crosslink the foamable sheet. Next, the crosslinked foamable sheet was heated to 250 ° C. to foam it to obtain a foam layer having a foaming ratio of 13 times and a thickness of 0.6 mm.
The obtained foam layer and the skin layer were laminated with an adhesive sheet (manufactured by Sekisui Chemical Co., Ltd., "3803H") having a thickness of 0.03 mm to obtain a laminated body.
Each evaluation was performed on the obtained laminated body, and the results are shown in Table 1.

(Examples 2 to 7, 11, 12, Comparative Examples 2 to 4)
The same as in Example 1 except that the composition of the foamable resin composition and the type of the epidermis layer were changed as shown in Table 1 and the irradiation conditions of the electron beam were appropriately changed so that the degree of cross-linking was as shown in Table 1. Obtained a laminate.
Each evaluation was performed on the obtained laminated body, and the results are shown in Table 1.

(Example 8)
100 parts by mass of polyethylene resin (LDPE (2)) and 0.5 parts by mass of antioxidant were put into a single-screw extruder, and supercritical carbon dioxide was injected and mixed at 7 MPa. After that, the temperature decreased toward the tip of the single-screw extruder, the temperature was set so that the temperature at the die outlet was 110 ° C., and extrusion molding was performed to obtain a sheet-shaped foam.
Both sides of the obtained sheet-shaped foam were crosslinked by irradiating both sides with an electron beam at an acceleration voltage of 500 keV for 1.9 Mrad to obtain a foam layer.
The obtained foam layer and the skin layer were laminated with an adhesive sheet (manufactured by Sekisui Chemical Co., Ltd., "3803H") having a thickness of 0.03 mm to obtain a laminated body.

(Comparative Examples 1 and 5)
A laminated body was obtained in the same manner as in Example 8 except that the irradiation conditions of the electron beam were changed so that the degree of cross-linking of the foam layer was as shown in Table 1 and the type of the skin layer was changed as shown in Table 1. rice field.
Each evaluation was performed on the obtained laminated body, and the results are shown in Table 1.

(Example 9)
A polyol compound consisting of 100 parts by mass of the polyol compound (1) and 5 parts by mass of the polyol compound (2), 20 parts by mass of the polyisocyanate compound, 0.1 part by mass of U-28 as a catalyst, and 2 parts of L626 as a foam stabilizer. A foamable resin composition was prepared by mixing a mass portion and 2 parts by mass of water as a foaming agent. The effervescent composition was injected into a mold (150 mm × 150 mm × 50 mm) and then heated in an oven at 80 ° C. for 60 minutes to effervescent and cure to obtain a cured product. The cured product was sliced to obtain a foam layer having a thickness of 3 mm.
The obtained foam layer and the skin layer were laminated with a 0.03 mm adhesive sheet (manufactured by Sekisui Chemical Co., Ltd., "3803H") to obtain a laminated body.
Each evaluation was performed on the obtained laminated body, and the results are shown in Table 1.

(Example 10)
A laminate was obtained in the same manner as in Example 9 except that the composition of the effervescent resin composition and the type of the epidermis layer were changed as shown in Table 1.
Each evaluation was performed on the obtained laminated body, and the results are shown in Table 1.

Since the laminate of the present invention has an Asker C hardness of a certain value or less, it has a flexible tactile sensation, a high total light transmittance, an excellent light transmittance, and necessary information is easily visible from the epidermis layer side. It turned out.

10 Laminated body 11 Epidermis layer 12 Foam layer 13 LED
14 Print layer

Claims (12)

A laminate having an epidermis layer and a foam layer, having an Asker C hardness of 70 or less and a total light transmittance of more than 0.01%. The laminate according to claim 1, wherein the skin layer has a thickness of 0.2 to 1.0 mm. The laminate according to claim 1 or 2, wherein the total light transmittance of the skin layer is 0.02 to 30%. The laminate according to any one of claims 1 to 3, wherein the foam layer has a thickness of 0.5 to 5 mm. The laminate according to any one of claims 1 to 4, wherein the total light transmittance of the foam layer is 10% or more. The laminate according to any one of claims 1 to 5, wherein the foam layer has a foaming ratio of 7 to 40 times. The laminate according to any one of claims 1 to 6, wherein the foam layer is a polyolefin-based foam layer or a polyurethane-based foam layer. The laminate according to any one of claims 1 to 7, wherein the laminate further includes at least one of a print layer and a print film layer. The laminate according to claim 8, wherein the printing layer is formed by printing at least one surface of a foam layer and a skin layer. An optical display member comprising the laminate according to any one of claims 1 to 9. The light display member according to claim 10, further comprising a sensor element. The optical display member according to claim 10 or 11, comprising a display having a sensor element.

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