JP6298605B2 - Hard-coated polyolefin resin sheet - Google Patents

Description

  The present invention relates to a hard coat-coated polyolefin resin sheet.

  Polyolefin is a resin that is widely used as a general-purpose resin. Polyolefin is lightweight and excellent in economic efficiency and moldability, and thus is easily molded and widely used by melt molding such as extrusion molding, blow molding, and injection molding.

  Polyolefin is excellent in chemical resistance, water resistance, electrical insulation, impact resistance, rigidity, ESCR resistance, etc., and is lightweight and tough. Therefore, it is widely used as a material for electrical insulators, home appliances, daily miscellaneous goods and the like.

  On the other hand, since polyolefin is a semi-crystalline resin, characteristics such as transparency, dimensional stability, and heat resistance are not sufficient. Conventional polyolefin products, except for products such as thin films, are generally opaque, so they can be used industrially in applications where transparency is required. It wasn't. However, in recent years, transparent molded products have been obtained even in thick molded products that have never existed by combining raw materials and processing techniques (see, for example, Patent Documents 1 to 4). With such a technique, it is possible to use polyolefin for various applications that require transparency.

  In order to obtain a transparent polyolefin molded product, the thickness is thin using a copolymer having a very low crystallinity (crystallinity), such as so-called low density polyethylene, linear low density polyethylene, block polypropylene, and random polypropylene. Films are used. However, it cannot be applied to a structure or the like that requires strength, rigidity, etc. because of its thin thickness.

  In order to obtain a strong, thick and transparent product, it is known to roll a thick sheet obtained from a specific raw material under processing conditions below the melting point to refine the crystal structure. (For example, refer to Patent Documents 1 to 4.) As a result, an unprecedented transparent thick molded product (sheet) is obtained. A material having transparency in such a sheet shape has not been obtained by the conventional concept of polyolefin-based materials.

  Furthermore, Patent Document 4 describes a transparent polyolefin-based resin sheet that is excellent in transparency in the visible light region and excellent in transparency in the infrared region. Such a polyolefin-based resin sheet can be developed for use as a protective cover for an apparatus capable of infrared diagnosis using thermography or the like. Further, the transparent polyolefin-based sheet having such novel characteristics can be used for electronic members using infrared as a communication means in addition to a protective cover and a window material.

  Examples of applications expected as electronic members include touch panels, protective films and sheets thereof. Conventionally, in such applications, a chemically tempered glass plate has been used because the surface of the molded product is required to be hard and transparent.

  However, the chemically strengthened glass plate strongly absorbs infrared rays, and therefore cannot be used for an electronic member using an infrared sensor or the like. On the other hand, a polyolefin resin sheet having transparency at wavelengths in the visible light and infrared regions has low surface hardness, and therefore has low scratch resistance and scratch resistance, making it difficult to replace glass products and the like.

  Accordingly, there is a demand for a member having transparency with respect to wavelengths in the visible light and infrared regions and having high surface hardness.

  Usually, as a means for increasing the surface hardness of the resin, conjugation with other materials such as hard coat agent coating can be considered. If the effect of improving the surface hardness by the hard coating agent coating is obtained on the polyolefin resin sheet, it can be developed for various uses. In particular, if the hardness of the transparent polyolefin resin sheet can be increased by coating with a hard coating agent, etc., it can be used as a substitute for glass, and it can be used in new applications for components that use infrared transparency. Thus, it becomes possible to provide a wide range of lightweight and inexpensive materials.

  However, with regard to imparting hard coat properties to the polyolefin resin sheet, there is usually a problem that the affinity between the polyolefin resin sheet and the hard coat agent is low and it is difficult to directly coat the hard coat. Therefore, it is necessary to interpose an adhesive layer between them. Further, it is generally known that there is no adhesive for bonding a polyolefin resin. This is because, with respect to an adhesive having a polar group, there are almost no surface functional groups that can participate in adhesion in the polyolefin resin sheet, and the free surface energy required for adhesion is low. Therefore, unless some surface treatment is performed, an adhesive layer having a sufficient adhesive force cannot be applied and the polyolefin resin sheet cannot be coated with a hard coat agent.

  In order to increase the surface free energy of the polyolefin resin sheet, it is common to increase the adhesion by adding polar groups to the surface of the polyolefin resin sheet by performing corona treatment, low temperature plasma treatment, flare treatment, etc. as pretreatment Has been done.

  Patent Documents 5 and 6 disclose adhesives suitable for polyolefin resin sheets. Patent Document 7 describes a hard coating forming sheet. Further, Patent Documents 8 and 9 have a description regarding a hard coat on a polyolefin resin.

WO2008 / 001772 JP 2009-154394 A JP 2012-126769 A WO2012 / 081586 JP 2002-201426 A Japanese Patent Laid-Open No. 11-50031 Special table 2013-512305 gazette JP 2002-241525 A Japanese Patent Laid-Open No. 2004-17410

  However, Patent Documents 5 and 6 relate to transparency in the visible light region and transparency in the infrared region of the polyolefin resin sheet after the adhesive or hard coat agent is applied or the hard coat layer is adhered. There is no detailed description. Usually, when a hard coat agent is applied to a polyolefin resin sheet, it is generally difficult to perform a sufficient hard coat due to poor adhesion and adhesion to the coating liquid. Therefore, it is common to apply a hard coat layer after previously applying an adhesive to a polyolefin substrate sheet. At this time, not only the strength but also the transparency and the transmittance of infrared rays are greatly affected by the type of adhesive and hard coating agent to be applied and the coating thickness.

  Further, Patent Document 7 only discloses a hardness improvement related to a hard coat using polyethylene terephthalate. The hardness when applied to a polyolefin resin sheet, transparency in the visible light region, and infrared transmittance. Is not described.

  Furthermore, Patent Documents 8 and 9 do not describe anything for transmitting infrared rays.

  Under such circumstances, a polyolefin resin sheet coated with a hard coat has been desired.

  The present invention has been made in view of the above problems, and is a hard coat-coated polyolefin resin sheet that is excellent in transparency and transparency in the visible light region and infrared region, and has a high surface hardness and excellent scratch resistance. The purpose is to provide.

  As a result of advancing earnest research to achieve the above object, the inventors of the present invention applied at least an adhesive layer and a hard coat layer to a base material sheet made of a polyolefin resin sheet in a wavelength region of 8 μm to 14 μm. The inventors have found that the above object can be achieved by using an adhesive layer and a hard coat layer having an average infrared transmittance and a total light transmittance in a visible light range within a predetermined range, and have completed the present invention.

That is, the present invention is as follows.
[1]
A polyolefin resin sheet (A), a hard coat layer (C), and an adhesive layer (B) for bonding the polyolefin resin sheet (A) and the hard coat layer (C);
The average infrared transmittance in the infrared wavelength region of 8 μm to 14 μm is 5% or more,
The surface hardness obtained as Vickers hardness is 70 N / mm ² or more,
The polyolefin resin sheet (A) contains a polyethylene resin,
Hard coat coated polyolefin resin sheet.
[2]
The hard coat-coated polyolefin resin sheet according to item [1], wherein the polyolefin resin sheet (A) is transparent.
[3]
The hard coat-coated polyolefin resin sheet according to [1] or [2], wherein the total light transmittance in the visible light region is 80% or more.
[4]
The hard coat-coated polyolefin resin sheet according to any one of [1] to [3] above, wherein the thickness of the hard coat-coated polyolefin resin sheet itself is 0.10 mm to 3.0 mm.
[5]
The adhesive layer (B) has a thickness of 0.10 μm to 100 μm,
The hard coat-coated polyolefin resin sheet according to any one of [1] to [3], wherein the hard coat layer (C) has a thickness of 0.10 μm to 100 μm.
[6]
The hard coat layer (C) according to any one of [1] to [5], wherein the hard coat layer (C) contains one or more selected from the group consisting of acrylic materials, silica materials, and carbon materials. Hard coat coated polyolefin resin sheet.
[7]
Any of [1] to [6] above, wherein the polyolefin resin sheet (A) is obtained by rolling at a temperature not higher than the melting point of the polyolefin resin contained in the polyolefin resin sheet (A). 2. The hard coat-coated polyolefin resin sheet according to claim 1.
[8]
The hard coat-coated polyolefin resin according to any one of [1] to [7], further including a primer layer (D) at an interface between the polyolefin resin sheet (A) and the adhesive layer (B). Sheet.
[9]
The hard coat-coated polyolefin resin sheet as described in [8] above, wherein the primer layer (D) contains an amine compound.
[10]
The hard coat-coated polyolefin resin sheet according to any one of [1] to [9] above, which is used as a member using infrared rays.
[11]
The hard coat-coated polyolefin resin sheet according to [10] above, wherein the member is a member for the automobile industry, a member for the electrical equipment industry, or a medical member.
[12]
The hard coat-coated polyolefin resin sheet according to [10], wherein the member is a touch panel display member.

  According to the present invention, it is possible to provide a hard coat-coated polyolefin resin sheet that is excellent in transparency and transparency in the visible light region and infrared region, and has a high surface hardness and excellent scratch resistance. Furthermore, the display member for touch panels using infrared rays, etc. can be provided using the polyolefin resin sheet coated with the hard coat.

  Hereinafter, a mode for carrying out the present invention (hereinafter, simply referred to as “the present embodiment”) will be described in detail. However, the following embodiment is an example for explaining the present invention, and the present invention will be described. It is not intended to limit the following contents. The present invention can be implemented with appropriate modifications within the scope of the gist thereof. The hard coat-coated polyolefin resin sheet will be described below.

[Hard coat coated polyolefin resin sheet]
The hard coat-coated polyolefin resin sheet according to the present embodiment (hereinafter also referred to as “hard coat-coated sheet”) is
A polyolefin resin sheet (A), a hard coat layer (C), and an adhesive layer (B) for bonding the polyolefin resin sheet (A) and the hard coat layer (C);
The average infrared transmittance in the infrared wavelength region of 8 μm to 14 μm is 5% or more,
The surface hardness is 70 N / mm ² or more.

[Infrared transmittance]
The average infrared transmittance of the hard coat coated sheet in the infrared wavelength range of 8 μm to 14 μm is 5% or more, preferably 10% or more, more preferably 20% or more, and further preferably 30% or more. It is. When the average infrared transmittance is 5% or more, it can be suitably used for an apparatus that emits infrared rays. Further, when the average infrared transmittance is less than 5%, it is difficult to identify by infrared thermography or infrared sensor using infrared rays, and it becomes difficult to detect infrared rays as communication and response means. The upper limit of the average infrared transmittance is not particularly limited, but is preferably 100%.

  Here, “average infrared transmittance” refers to an average value of infrared transmittance in a wavelength region of 8 μm to 14 μm. The average infrared transmittance can be measured by the method described in Examples. In addition, the average infrared transmittance is the thickness of the hard coat coating sheet, the thickness of each layer, the selection of an adhesive and a hard coat agent described later, and the surface smoothness is improved to control the transmittance by reflection, etc. Can be controlled.

[Visible light transmittance]
The total light transmittance of the hard coat-coated sheet in the visible light region is preferably 80% or more, more preferably 85% or more, and further preferably 90% or more. When the total light transmittance is 80% or more, transparency to visible light is high, and visibility when an object is viewed through a sheet tends to be further improved. The upper limit of the total light transmittance is not particularly limited, but is preferably 100%.

  The total light transmittance can be measured by the method described in Examples. In addition, the total light transmittance is the thickness of the hard coat covering sheet, the thickness of each layer, the selection of the adhesive and hard coat agent described later, the surface smoothness is improved to control the transmittance by reflection, etc. Can be controlled. Here, the “visible light region” refers to a wavelength range of 400 nm to 800 nm. In addition, as a method of calculating | requiring the transmittance | permeability (transparency) of such a visible light area | region, the method as described in JISK7361-1: 1997 is mentioned.

〔surface hardness〕
The surface hardness of the hard coat coating sheet according to the present embodiment is 70N / mm ² or more, preferably 100 N / mm ² or more, more preferably 150 N / mm ² or more. When the surface hardness is 70 N / mm ² or more, the surface hardness is higher and the scratch resistance is more excellent while maintaining the transparency and transparency of the visible light region and the infrared region. Further, the upper limit of the surface hardness is not particularly limited, but it is preferably as high as possible within a range in which a predetermined infrared transmittance and visible light transmittance can be secured. The surface hardness can be measured by the method described in the examples. The surface hardness can be controlled by selecting the thickness of the hard coat covering sheet, the thickness of each layer, and the adhesive and hard coat agent described later.

〔thickness〕
The thickness of the hard coat covering sheet is preferably 0.10 mm to 3.0 mm, more preferably 0.30 mm to 2.0 mm, and further preferably 0.50 mm to 1.5 mm. On the other hand, when the thickness of the hard coat covering sheet is 0.1 mm or more, the rigidity of the base sheet tends to be high and the surface hardness tends to be further improved. Moreover, it exists in the tendency which can suppress the fall of the transmittance | permeability of visible light and infrared rays because the thickness of a hard coat coating sheet is 3 mm or less. As described above, it is preferable to select a combination of an adhesive layer and a hard coat layer having a predetermined thickness that provides a surface hardness of 70 N / mm ² or more. Increasing the thickness to improve adhesion and hard coat properties tends to decrease the transparency of the infrared region, and decreasing the thickness tends to decrease mechanical properties, so the thickness is controlled within a predetermined range. Thus, it is preferable to achieve both adhesiveness, hard coat property and infrared transparency.

[Polyolefin resin sheet (A)]
The polyolefin resin sheet (A) contains a polyolefin resin. The polyolefin resin sheet (A) is preferably transparent. Here, “transparent” means that the total light transmittance is 80% or more and the haze value measured by the method specified in JIS K 7136: 2000 is 15% or less. In addition, regarding transparency, the higher the total light transmittance in the visible light region, the better. On the other hand, from the viewpoint of transparency, the lower the haze value used as an indicator of haze, the better. That is, the higher the total light transmittance in the visible light region and the lower the haze value, the more the transparency tends to improve.

  The polyolefin resin is not particularly limited, and examples thereof include polyethylene resins, polypropylene resins, polybutadiene resins, cycloolefin resins, polybutene resins, ethylene-propylene copolymer rubbers, and hydrogenated products thereof. Can be mentioned. Among these, a polyethylene resin and a polypropylene resin are preferable, and a polyethylene resin is more preferable. The polyethylene-based resin has a simple structure and has few functional groups that absorb infrared rays. Therefore, by using a polyethylene-based resin, it tends to be more excellent in infrared transparency. These polyolefin resin may be used individually by 1 type, and may use 2 or more types together.

  Although it does not specifically limit as a polyethylene-type resin, For example, the copolymer of the homopolymer of ethylene and the other comonomer copolymerizable with ethylene and ethylene is mentioned. Although it does not specifically limit as another comonomer, For example, alpha-olefins, such as propylene, 1-butene, 1-hexene, 1-octene, vinyl acetate, vinyl alcohol, etc. are mentioned.

  The polyethylene resin is not particularly limited. For example, for example, high density polyethylene (HDPE), medium density polyethylene (MDPE) low density polyethylene (LDPE), linear low density polyethylene (LLDPE), and ultra low density polyethylene. (VLDPE), ultra high molecular weight polyethylene (UHMWPE), cross-linked polyethylene (PEX) and the like.

The density of the polyethylene resin is preferably 880 kg / m ³ or more, more preferably 910 kg / m ³ or more, more preferably 915 kg / m ³ or more. When the density of the polyethylene resin is 880 kg / m ³ or more, the rigidity in the thickness direction of the polyolefin resin sheet (A) becomes higher and the rigidity of the entire hard coat coated sheet tends to be further improved.

Further, the density of the polyethylene resin, preferably at 960 kg / m ³ or less, more preferably 950 kg / m ³ or less, more preferably not more 945 kg / m ³ or less, still more preferably 943kg / m ³ or less It is. When the density of the polyethylene resin is 960 kg / m ³ or less, the proportion of the amorphous part increases, and the transmittance in the visible light region tends to be further improved.

  The density of the polyethylene resin can be controlled by blending the polyethylene resin.

  The molecular weight of the polyolefin resin can be appropriately selected according to the workability when producing the raw material of the polyolefin resin sheet (A) and the mechanical properties of the finally obtained polyolefin resin sheet (A). it can.

  For example, if emphasis is placed on the processability of the raw fabric, high density polyethylene (HDPE), medium density polyethylene (MDPE), low density polyethylene (LDPE), linear low density polyethylene (LLDPE), ultra low density polyethylene ( VLDPE) or the like is preferably used. A melt flow rate (hereinafter also referred to as “MFR”) can be used as an index of the molecular weight of these polyethylene resins. The MFR of the polyethylene resin is preferably 20 g / 10 min or less, more preferably 10 g / 10 min or less, and further preferably 5 g / 10 min or less. When the MFR is 20 g / 10 min or less, the melt viscosity is improved, the sheet-shaped extrusion molding becomes easier, and the mechanical properties such as impact strength of the finally obtained polyolefin resin sheet (A) are also improved. It tends to improve.

  The MFR of the polyethylene resin is preferably 0.01 g / 10 min or more, more preferably 0.1 g / 10 min or more, further preferably 0.5 g / 10 min or more, and further Preferably it is 1.0 g / 10 minutes. When the MFR is 0.01 g / 10 min or more, the sheet-shaped extrusion tends to be easier.

  The MFR of the polyethylene resin can be measured by the method described in the examples. The MFR of the polyethylene resin can be controlled by blending the polyethylene resin.

  On the other hand, if a base sheet having more excellent mechanical properties such as wear resistance and impact resistance is used, ultra high molecular weight polyethylene (UHMWPE) is preferably used. The intrinsic viscosity in a 135 ° C. decalin solution can be used as an index of the molecular weight of ultra high molecular weight polyethylene (UHMWPE). The intrinsic viscosity of the ultra high molecular weight polyethylene is preferably 7 dL / g or less, more preferably 10 dL / g or more, still more preferably 13 dL / g or more, and even more preferably 15 dL / g or more. When the intrinsic viscosity of the ultrahigh molecular weight polyethylene is 7 dL / g or more, the mechanical properties of the polyolefin resin sheet (A) such as wear resistance and impact resistance tend to be further improved.

  Further, the intrinsic viscosity of the ultrahigh molecular weight polyethylene is preferably 30 dL / g or less, more preferably 25 dL / g or less, and further preferably 20 dL / g or less. When the intrinsic viscosity of the ultrahigh molecular weight polyethylene is 30 dL / g or less, the fusion property between the resin powders during processing is improved, and the workability tends to be excellent. Moreover, since intrinsic viscosity is 30 dL / g or less, since the melt | fusion property of the resin powder at the time of a process improves, it exists in the tendency for a mechanical physical property to improve more.

  The intrinsic viscosity of ultra high molecular weight polyethylene can be measured by the method described in the examples. The intrinsic viscosity of ultra high molecular weight polyethylene can be controlled by blending a polyethylene resin.

  In the case of ultra high molecular weight polyethylene, since it has a high viscosity, extrusion molding, which is a general molding process, may be difficult. Therefore, when using ultra high molecular weight polyethylene, a cylindrical molded product is obtained by a general molding method of ultra high molecular weight polyethylene, such as ram extrusion molding or compression molding, and the molded product is made into a skive shape. A polyolefin-based resin sheet (A) can be obtained by producing a cut skive sheet or the like.

  The polyolefin resin sheet (A) is preferably obtained by rolling at a temperature not higher than the melting point of the polyolefin resin contained in the polyolefin resin sheet (A). By carrying out such a rolling process, the transparency tends to be further improved. The rolling ratio is preferably 1.3 times or more, more preferably 3 times or more, and further preferably 4 times or more. When the rolling ratio is within the above range, the transparency tends to be further improved.

  The rolling temperature is preferably not higher than the melting point of the polyolefin resin, more preferably not higher than the melting point of the polyolefin resin and not lower than 3 ° C., more preferably not lower than the melting point of the polyolefin resin and not lower than 5 ° C. Here, the “rolling temperature” includes a preheating temperature and a roll temperature.

  Regarding the thickness of each of the polyolefin-based resin sheet (A), the adhesive layer (B), and the hard coat layer (C), the total light transmittance in the visible light region is 80% or more, respectively, and the wavelength ranges from 8 μm to 14 μm. It is preferable to adjust the thickness so that the average infrared transmittance at is 5% or more.

(Manufacturing method of polyolefin resin sheet (A))
Although it does not specifically limit as a manufacturing method of polyolefin resin sheet (A), For example, the method described in patent documents 1-3 is mentioned.

[Adhesive layer (B)]
The adhesive layer (B) is a layer that adheres the polyolefin resin sheet (A) and the hard coat layer (C). Conventionally, it has been difficult to bond other members to polyolefin resin sheets, and there has been no suitable adhesive. However, in recent years, adhesives that can adhere to polyethylene resins and polypropylene resins, which are base materials for difficult adhesives Are becoming commercially available, and these usually marketed adhesives can be used for the polyolefin resin sheet (A). By providing the adhesive layer (B), the adhesion between the polyolefin-based resin sheet (A) and the hard coat layer (C) can be further enhanced.

  Although it does not specifically limit as an adhesive agent which can be contained in a contact bonding layer (B), For example, a solvent type adhesive agent and a chemical reaction type adhesive agent are mentioned. Moreover, it is although it does not specifically limit as a type of adhesive agent, For example, 1 liquid type and 2 liquid type are mentioned. The adhesive that can be included in the adhesive layer (B) may be used alone or in combination of two or more.

  Although it does not specifically limit as a 1 liquid type solvent form adhesive agent, For example, the styrene block copolymer rubber-type adhesive agent etc. which are described in patent document 6 are mentioned.

  Although it does not specifically limit as a 2 liquid type adhesive agent, For example, the 2-cyanoacrylate type adhesive agent etc. which are described in patent document 5 are mentioned.

  In the case of adopting the two-component type, it is preferable to further have a primer layer (D) at the interface between the polyolefin resin sheet (A) and the adhesive layer (B). Before applying the adhesive to the polyolefin resin sheet (A), the primer layer (D) is subjected to a surface treatment to further strengthen the adhesive strength between the polyolefin resin sheet (A) and the adhesive layer (B). It tends to be possible.

  The primer layer (D) preferably contains an amine compound. Although it does not specifically limit as an amine compound, For example, the compound with which the 2 or more tertiary amino group was couple | bonded with the alkylene chain which has an ether bond is preferable. By using an amine compound, the adhesive strength between the polyolefin resin sheet (A) and the adhesive layer (B) tends to be further strengthened.

  The thickness of the adhesive layer (B) is preferably 0.10 μm to 100 μm, more preferably 0.50 μm to 50 μm, still more preferably 1.0 μm to 30 μm, and still more preferably 3.0 μm to 15 μm. It is. When the thickness of the adhesive layer (B) is 0.10 μm or more, the adhesiveness to the polyolefin resin sheet (A) tends to be further improved. Moreover, when the thickness of the adhesive layer (B) is 100 μm or less, the infrared transmittance due to the infrared absorbing characteristic group in the adhesive component tends to be further suppressed.

  The visible light transmittance of the adhesive layer (B) is preferably 80% or more, more preferably 85% or more, and further preferably 90% or more. The upper limit of the visible light transmittance is not particularly limited, but is preferably 100%. When the visible light transmittance of the adhesive layer (B) is within the above range, it can be suitably used for an apparatus that emits infrared rays. The visible light transmittance of the adhesive layer (B) can be controlled by selecting the thickness of the adhesive layer (B), the type of adhesive, and the like.

  The average infrared transmittance of the adhesive layer (B) is preferably 5% or more, more preferably 20% or more, and further preferably 20% or more. The upper limit of the average infrared transmittance is not particularly limited, but is preferably 100%. When the average infrared transmittance of the adhesive layer (B) is within the above range, the visibility when the object is viewed through the sheet tends to be improved. The average infrared transmittance of the adhesive layer (B) can be controlled by selecting the thickness of the adhesive layer (B), the type of adhesive, and the like.

[Hard coat layer (C)]
The hard coat layer (C) is bonded to the polyolefin resin sheet (A) via the adhesive layer (B). Although it does not specifically limit as a hard-coat agent which can be contained in a hard-coat layer (C), For example, an acrylic material, a silica-type material, and a carbon-type material are mentioned. By including such a resin, the surface hardness tends to be higher and the scratch resistance tends to be better while maintaining transparency and transparency in the visible light region and infrared region. The resin that can be included in the hard coat layer (C) may be used alone or in combination of two or more.

  The acrylic material is not particularly limited, and examples thereof include monomeric radical polymerization type monofunctional acrylate, bifunctional acrylate, trifunctional acrylate, and 4-6 functional acrylate; oligomeric radical polymerization type epoxy acrylate, urethane acrylate, Examples thereof include polyester acrylate, copolymer acrylate, polybutadiene acrylate, silicon acrylate, and amino resin acrylate.

  The silica-based material is not particularly limited. For example, tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetraisopropoxysilane, ethoxytrimethoxysilane, propoxytrimethoxysilane, isopropoxytrimethoxysilane, trimethoxysilane, Examples include methoxytriethoxysilane, propoxytriethoxysilane, isopropoxytriethoxysilane, methoxytripropoxysilane, ethoxytripropoxysilane, diethoxydimethoxysilane, dimethoxydipropoxysilane, and the like.

  Although it does not specifically limit as a carbon-type material, For example, a diamond-like carbon (DLC) film | membrane etc. are mentioned. By using an inorganic film such as a DLC film, the surface hardness tends to be further improved.

  Although it does not specifically limit as a hardening type of a hard-coat agent, For example, thermosetting types, such as ionizing radiation hardening type; normal temperature hardening type and a two-component reaction hardening type, etc. are mentioned. That is, the hard coat agent is not particularly limited, and examples thereof include generally known UV curable resins, urethane resins, amino resins, and condensation resins.

  Although it does not specifically limit as a preparation method of a hard-coat layer (C), For example, after apply | coating a hard-coat agent to a polyolefin-type resin sheet (A) via an adhesive layer (B), heat, an ultraviolet-ray, Examples include a wet method in which a film is formed (cured) using an electron beam, a vacuum deposition method, ion plating, sputtering, plasma polymerization, and other dry methods. Among these, the wet method is preferable when the hard coat layer (C) is formed on the polyolefin resin sheet (A) having a large size and an arbitrary shape.

  Although it does not specifically limit as a coating method of a hard-coat agent, For example, a reverse coat method, a gravure coat method, a bar coat method, a spray coat method, a kiss coat method, a wire barcode method, a curtain coat method is mentioned. Moreover, in order to improve coating property, it is also possible to process the polyolefin-type resin sheet (A) surface with a leveling agent.

  The method for forming the hard coat layer is not particularly limited, and a known molding technique can be used. Known film forming techniques include, for example, a film forming method (for example, refer to Patent Document 8) relating to a silica-based hard coat layer using an organosilicon compound, a hard coat liquid containing polyfunctional acrylate, aminosilane, and colloidal silica. The method of apply | coating and irradiating an active energy ray and forming a hard-coat layer is mentioned (for example, refer patent document 8).

  In addition, as a method of forming a DLC film, a method of coating the DLC film after modifying the polyolefin resin sheet (A) by plasma irradiation, and a method of coating a reactive gas using an active gas when performing plasma irradiation Is mentioned. The step of modifying the surface of the polyolefin resin sheet (A) by plasma irradiation is not particularly limited. For example, atoms or molecular radical species generated by plasma are attached to the surface of the polyolefin resin sheet (A), or There are various plasma processing methods for activating the surface after the incorporation.

  There is a method of performing plasma irradiation using a reactive gas on the surface of the polyolefin resin sheet (A) by a plasma CVD method (Chemical Vapor Deposition). Before performing the plasma treatment, it is possible to further activate methane and acetylene to be added thereafter by cleaning with argon gas for several minutes in advance.

Diamond has an SP ³ structure consisting only of carbon atoms, and is very high. Meanwhile, DLC has a composite structure of carbon atoms and hydrogen SP ³ structure, an amorphous structure of the carbon atoms including hydrogen atoms and SP ³ structure, the color at the time of the coated and brownish Tend to be. The balance between transparency and hardness can be controlled by adjusting the amount of hydrogen at the time of irradiation and the thickness of the hard coat layer (C). The temperature of the reaction at the time of activation is preferably 50 ° C to 200 ° C, more preferably 60 ° C to 150 ° C, and further preferably 70 ° C to 100 ° C. Further, the hydrogen concentration is preferably 5% to 35%, more preferably 10% to 25%, and further preferably 15% to 20%. By setting it as such conditions, it exists in the tendency for adhesiveness with a polyolefin-type resin sheet (A) to improve more.

  The thickness of the hard coat layer (C) is preferably 0.10 μm to 100 μm, more preferably 0.50 μm to 50 μm, still more preferably 1.0 μm to 30 μm, still more preferably 3.0 μm to 15 μm. When the thickness of the hard coat layer (C) is 0.10 μm or more, the scratch resistance tends to be further improved. Moreover, it exists in the tendency which can suppress generation | occurrence | production of the fall of an infrared transmittance and the crack of a hard-coat layer (C) because the thickness of a hard-coat layer (C) is 100 micrometers or less.

  The visible light transmittance of the hard coat layer (C) is preferably 80% or more, more preferably 85% or more, and further preferably 90% or more. The upper limit of the visible light transmittance is not particularly limited, but is preferably 100%. When the visible light transmittance of the hard coat layer (C) is within the above range, the visibility when the object is viewed through the sheet tends to be further improved. The visible light transmittance of the hard coat layer (C) can be controlled by selecting the thickness of the hard coat layer (C) and the type of the hard coat agent.

  The average infrared transmittance of the hard coat layer (C) is preferably 5% or more, more preferably 10% or more, and further preferably 20% or more. The upper limit of the average infrared transmittance is not particularly limited, but is preferably 100%. When the average infrared transmittance of the hard coat layer (C) is within the above range, the hard coat layer (C) can be suitably used for an apparatus that emits infrared rays. The average infrared transmittance of the hard coat layer (C) can be controlled by selecting the thickness of the hard coat layer (C) and the type of the hard coat agent.

The surface hardness of the hard coat layer (C) is preferably 70N / mm ² or more, more preferably 100 N / mm ² or more, further preferably 150 N / mm ² or more. When the surface hardness is 70 N / mm ² or more, the surface hardness tends to be higher and the scratch resistance tends to be better while maintaining transparency and transparency in the visible light region and the infrared region. Further, the upper limit of the surface hardness is not particularly limited, but it is preferably as high as possible within a range in which a predetermined infrared transmittance and visible light transmittance can be secured. The surface hardness can be measured by the method described in the examples. The surface hardness can be controlled by selecting the thickness of the hard coat covering sheet, the thickness of each layer, and the adhesive and hard coat agent described later.

[Use]
By having the hard coat layer (C) on the surface of the hard coat coated sheet, the hard coat layer (C) can be used for applications that are used in an environment where scratches easily occur. Such a hard coat-coated polyethylene resin sheet is preferably used as a member utilizing infrared rays. The member using infrared rays is not particularly limited, and examples thereof include a member of a communication unit of a mobile terminal device (such as a mobile phone and a mobile computer) in which an infrared sensor is incorporated, a display member for a touch panel, and the like. Other members using infrared rays are not particularly limited. For example, a member for an automotive industry such as a protective cover for an infrared array sensor of a vehicle, a CCD camera cover for visually checking the front, rear, or side of a vehicle, a human body detector. Examples include members for the electrical equipment industry such as a protective sheet for an infrared sensor, and medical members such as a device capable of infrared diagnosis using a thermography.

  If a hard coat coating layer having a function of preventing scratches is formed on a transparent polyolefin sheet that transmits infrared rays and visible light, the availability of the hard coat coating sheet can be further increased.

  EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention further in detail, this invention is not limited at all by the following Examples.

Measurement method and conditions (1) Density (ρ: kg / m ³ )
The density was measured by a density gradient tube method (23 ° C.) according to JIS K 7112: 1999.

(2) Melt flow rate (MFR)
The MFR of polyethylene (PE) was measured according to JIS K 7210: 1999.

(3) Intrinsic viscosity (IV)
The viscosity of ultra high molecular weight polyethylene was measured by the following solution viscosity method. 20 mg of polymer was added to 20 mL of decalin (decahydronaphthalene) and stirred at 150 ° C. for 2 hours to dissolve the polymer. The dropping time (t _s ) between the marked lines was measured using a Ubbelohde type viscometer for the solution in a thermostatic bath at 135 ° C. As a blank, it does not put the polymer was measured drop time decalin only (t _b). The specific viscosity (η _sp / C) of the polymer was plotted according to the following formula, and the intrinsic viscosity (η; IV) extrapolated to a concentration of 0 was determined.
η _sp / C = (t _s / t _b −1) /0.1

(4) Total light transmittance For the measurement of the total light transmittance, a test piece obtained by punching out a hard coat coated sheet to 35 mm × 50 mm was used. The total light transmittance was measured according to JIS K 7361-1: 1997. The measuring instrument was measured by using a haze meter NDH2000 manufactured by Nippon Denshoku Industries Co., Ltd.

(5) Measurement of average infrared transmittance For measurement of average infrared transmittance, a test piece obtained by punching a hard coat coated sheet into 35 mm × 50 mm was used. The average infrared transmittance is FT-IR Fourier transform infrared spectrophotometer “FT / IR4100” manufactured by Nippon Spectrometer Co., Ltd., with a transmission method having a resolution of 4 cm ⁻¹ , a total number of 64 times, and a wavelength region of 8 μm to 14 μm (wave number infrared transmittance was measured for transmittance at 1250cm ^-1 ~714cm ^-1) for each 1 cm ^-1, by adding all the obtained value was obtained by dividing the total number of data.

(6) Hard coat coated polyolefin resin sheet thickness The thickness of the hard coat coated polyolefin resin sheet was measured to the second decimal place using a micrometer (395-541: BMD-25DM) manufactured by Mitutoyo Corporation. Rounded to the second decimal place. The stretch ratio was calculated from the actually measured sheet thickness (2nd decimal place) and rounded off to the second decimal place.

  Regarding the thickness of the adhesive layer (B) and the thickness of the hard coat layer (C), the hard coat-coated polyolefin resin sheet is embedded with an epoxy resin and cured, and then the microtome (Reichert UCN) is formed in the thickness direction. Then, the glass knife surface cutting was performed, and the cut surface was observed with a reflection microscope (OLYMPUS GX51F) to obtain each. More specifically, the thickness of the adhesive layer and the hard coat layer on the surface of the polyolefin resin sheet was measured in the order of microns and submicrons with the dimension measurement software attached to the microscope apparatus.

(7) Molding method (7-1) Compression molding [Preparation of skive sheet]
Ultra high molecular weight polyethylene powder is introduced into a donut-shaped mold having a hole with an outer diameter of 600 mmφ and an inner diameter of 90 mmφ so that the thickness finally becomes about 130 mm, and the internal air is released at about 10 MPa for 30 minutes, and then The mixture was heated and compressed for 13 hours under conditions of about 9 MPa and about 140 to 145 ° C. Furthermore, it cooled with the cooling water of 20 degreeC-30 degree | times for about 7 hours, keeping a pressure at about 9 MPa. The doughnut-shaped molded body taken out from the mold was allowed to stand at room temperature for 2 days or more and cooled by further gradually heating the internal heat. Thereafter, the doughnut-shaped formed body was fixed to a skive machine and skived to obtain a skive sheet having a thickness of 1 mm to 4 mm.

(7-2) Extrusion [Production of Extruded Sheet]
In a single screw extruder (manufactured by Toshiba Corporation, screw diameter: φ65 mm, L / D = 28), the cylinder temperature, the die temperature and the adapter die temperature were set to 190 ° C., respectively, and the screw rotation speed was 50 rpm. The molten parison was extruded using a T die having a width of 400 mm and a lip width of 5.5 mm. Next, a molten parison was introduced into a chill roll whose temperature was adjusted at 95 ° C., and an extruded sheet having a thickness of 5 mm and a thickness of 5 mm was produced.

(7-3) Roll forming [Production of rolled sheet]
The above-mentioned skive sheet or extruded sheet is pre-heated at 120 ° C. with a rolling roll having a roll diameter of 300 mmφ and a roll width of 500 mm, and the roll is rotated by 1 m / min by adjusting the skive sheet or extruded sheet to an arbitrary gap. The skive sheet was rolled at high speed. The GAP value is desirably a clearance of 1/2 to 1/10 of the original fabric thickness.

  Rolling was performed at a roll temperature of 120 ° C., similar to the preheating temperature. The preheating temperature and the roll temperature at this time are not temperature conditions limited to 120 ° C. The rolled sheet that came out of the rolling roll was taken up at a different take-up speed, and was taken up while applying a tension of 200 N or more while monitoring the tension controller. The wound sheet was allowed to cool at room temperature for several hours.

  In addition, about the manufacturing conditions of said (7-1)-(7-3), when there is special description in each Example, it gives priority.

(8) Surface hardness The surface hardness was determined as Vickers hardness. The Vickers hardness having a predetermined Vickers indenter was measured under the following conditions using a testing machine (product name: HM221, manufactured by Mitutoyo Corporation).
Indentation depth: 1 μm
Maximum load: 5 N / mm ²
(Evaluation criteria)
○: 70N / mm ² or more △: 50N / mm ² more than 70N / mm ² less than ×: 50N / mm less than ²

(9) Scratch resistance Scratch resistance was reciprocated 20 times with a 1 kgf load using steel wool (# 0000) in accordance with JIS-K5600, and scratches on the surface were visually confirmed.
○: There is no scratch at all.
Δ: Slightly scratched, but no effect on visual transparency.
×: Scratched and has an influence on visual visibility.

Polyolefin resin raw material

Adhesive (B-1): Solvent type adhesive (1 liquid type, styrene butadiene rubber (43%) / cyclohexane, acetone (57%); manufactured by Konishi Co., Ltd., product name Bond GP Clear)
Adhesive (B-2): Chemically reactive adhesive (cyanoacrylate (95% or more); product name Cemedine PPX, manufactured by Cemedine Co., Ltd.)

Hard coat agent (C-1): Acrylate resin Hard coat agent (C-2): Thermosetting silicone hard coat paint Hard coat agent (C-3): DLC

  Primer (D): Contains 99% normal heptane and 1% bis (2-dimethylaminoethyl) ether.

Example 1
By producing an extruded sheet of 2.5 mm using HDPE (density 941 kg / m ³ , MFR 2.5 g / 10 min, manufactured by Asahi Kasei Chemicals, product name Creolex TM K4125), and rolling the extruded sheet A polyolefin resin sheet was prepared. The rolling conditions were a roll temperature of 120 ° C., a rotation speed of 0.6 m / min, and a GAP of 0.4 mm. The thickness of the polyolefin resin sheet obtained by rolling was 0.5 mm. The polyolefin resin sheet produced as described above (hereinafter also referred to as “HDPE transparent sheet (0.5 mm)”) was cut into 100 mm × 100 mm.

  The surface of the obtained polyolefin resin sheet was washed with chloroform. Since the viscosity of the adhesive (B-1) was high, the adhesive (B-1) was previously diluted to about 15% with chloroform. Next, 0.3 g of diluted adhesive (B-1) was applied to the washed polyolefin resin sheet, and uniformly coated using a bar coater. After coating, the polyolefin resin sheet was cured for 24 hours or more on a draft test bench at room temperature, and the diluent chloroform was sufficiently volatilized.

  70 parts of a hard coating agent (C-1), 3 parts of a polymerization initiator (Irgacure 184; manufactured by Ciba Specialty Chemicals) and 27 parts of methyl ethyl ketone were mixed and stirred with a stirrer to prepare a hard coating agent. 0.3 g of the prepared coating agent for hard coat was dropped onto a polyolefin resin sheet, applied with a bar coater, and then dried at 80 ° C. for 30 minutes. The surface hardness, average infrared transmittance, and total light transmittance of the obtained hard coat-coated polyolefin resin sheet were measured.

(Example 2)
The surface of the HDPE transparent sheet (0.5 mm) produced in Example 1 was washed with chloroform, and then the primer (D) was applied to the surface of the HDPE transparent sheet (0.5 mm) with a cotton swab. After the primer (D) was applied, g of the adhesive (B-2) was applied and applied uniformly using a bar coater. After coating, the polyolefin resin sheet was cured for 3 hours on a draft test bench at room temperature to adjust the state. Thereafter, a hard coat layer was produced in the same manner as in Example 1. The surface hardness, average infrared transmittance, and total light transmittance of the obtained hard coat-coated polyolefin resin sheet were measured.

(Example 3)
A hard coat-coated polyolefin resin sheet was prepared in the same manner as in Example 1 except that the hard coat agent (C-2) was used. Specifically, a hard coating agent (C-2), methyltrimethoxysilane, zinc methoxyethoxide, hydrochloric acid, and alcohol were mixed to prepare a hard coating agent. The prepared hard coat coating agent was dropped onto a polyolefin resin sheet, coated with a bar coater, and then dried at 140 ° C. for 15 minutes using a heater. After drying, the state was adjusted for about 1 hour at room temperature. The surface hardness, average infrared transmittance, and total light transmittance of the obtained hard coat-coated polyolefin resin sheet were measured.

Example 4
A hard coat-coated polyolefin resin sheet was produced in the same manner as in Example 1 except that the hard coat agent (C-3) was used. Specifically, a polyolefin resin sheet is placed in a chamber of a plasma CVD apparatus, the pressure in the chamber is set to a vacuum (1 × 10 ⁻⁴ Pa), and then 50% by volume of argon gas and methane gas are mixed. Then, the surface of the polyolefin resin sheet was modified. After the surface modification, the reaction gas was stopped, and then a methane gas containing a hard coat agent (C-3) as a raw material for the DLC film was introduced into the chamber to form a DLC film. The production conditions of the DLC film were as follows: pressure 15 Pa, temperature 70 ° C., and formation time 15 minutes. When the difference in thickness before and after the production of the DLC film was measured, the difference in thickness was 0.5 μm. The surface hardness, average infrared transmittance, and total light transmittance of the obtained hard coat-coated polyolefin resin sheet were measured.

(Example 5)
A hard coat-coated polyolefin resin sheet was obtained in the same manner as in Example 4 except that the thickness of the polyolefin resin sheet was 1.0 mm. Specifically, a 5 mm extruded sheet was produced using HDPE (density 941 kg / m ³ , MFR 2.5 g / 10 min, manufactured by Asahi Kasei Chemicals, product name Creolex TM K4125), and the extruded sheet was rolled. As a result, a polyolefin resin sheet having a thickness of 1.0 mm was produced. The rolling conditions were a heating layer of 120 ° C., the temperature of the sheet was adjusted to 100 ° C. to 120 ° C., a roll temperature of 120 ° C., a rotation speed of 0.6 m / min, and a GAP of 0.85 mm. The polyolefin resin sheet obtained by rolling had a thickness of 1.0 mm. The surface hardness, average infrared transmittance, and total light transmittance of the obtained hard coat-coated polyolefin resin sheet were measured.

(Example 6)
A hard coat coated polyolefin resin sheet was obtained in the same manner as in Example 4 except that the following UHMWPE transparent sheet (rolled) was used as the polyolefin resin sheet. Specifically, compression molding is performed using UHMWPE (density is 920 kg / m ³ , IV is 17.0 dl / g, manufactured by Asahi Kasei Chemicals Corporation, product name Sun Fine TM UL901), and a 2 mm thick skive sheet is formed. A polyolefin resin sheet was produced by rolling the skive sheet. As the rolling conditions, heating was performed in a heating layer so that the temperature of the sheet was 100 ° C., and the roll temperature was 120 ° C., the rotation speed was 0.6 m / min, and the GAP was 0.4 mm. The thickness of the polyolefin resin sheet obtained by rolling was 0.5 mm. The polyolefin resin sheet produced as described above (hereinafter also referred to as “UHMWPE transparent sheet (rolled)”) was cut into 100 mm × 100 mm and used. The surface hardness, average infrared transmittance, and total light transmittance of the obtained hard coat-coated polyolefin resin sheet were measured.

(Comparative Example 1)
The surface hardness, average infrared transmittance, and total light transmittance of soda glass (product name: soda-lime glass, manufactured by Central Glass Co., Ltd.) having a thickness of 0.5 mm were measured.

(Comparative Example 2)
A polymethyl methacrylate having a thickness of 0.6 mm (manufactured by Asahi Kasei Chemicals, trade name “Delagrass A”), a surface hardness of a density of 1190 kg / m ³ , an average infrared transmittance, and a total light transmittance were measured.

(Comparative Example 3)
The surface hardness, average infrared transmittance, and total light transmittance of the polyolefin resin sheet described in Example 1 were measured.

(Example 7)
A hard coat coated polyolefin resin sheet was obtained in the same manner as in Example 1 except that the following UHMWPE sheet was used as the polyolefin resin sheet. Specifically, compression molding was performed using UHMWPE (density is 920 kg / m ³ and IV is 17.0 dl / g) to obtain a skive sheet having a thickness of 0.5 mm. Without performing rolling, the skive sheet was used as a polyolefin resin sheet (hereinafter also referred to as “UHMWPE sheet”). In addition, the sheet | seat made from UHMWPE which has not performed the rolling process was opaque. The surface hardness, average infrared transmittance, and total light transmittance of the obtained hard coat-coated polyolefin resin sheet were measured.

(Comparative Example 4)
Compression molding was performed using UHMWPE (density is 920 kg / m ³ , IV is 17.0 dl / g, manufactured by Asahi Kasei Chemicals Corporation, product name Sun Fine TM UL901), and a skive sheet having a thickness of 0.5 mm was produced. The obtained sheet was measured for surface hardness, average infrared transmittance, and total light transmittance without applying an adhesive or a hard coat agent.

  The results of the above examples and comparative examples are summarized in Table 2.

  From the results shown in Table 2, in the examples, a hard coat coated sheet having a high total light transmittance and infrared transmittance, excellent visibility with visible light and infrared light, and high surface hardness is obtained. In general, glass and acrylic resin plates having excellent hardness and high transparency do not transmit infrared rays at all, and therefore cannot be developed for applications using infrared rays. On the other hand, in Comparative Example 3, when the hard coat is not performed, the surface hardness is low, so that it is not suitable for applications such as a touch panel using infrared rays. Comparative Example 4 is a commonly used polyethylene sheet, which transmits infrared rays, but has insufficient transparency and surface hardness such as total light transmittance, and a touch panel using infrared rays. It is unsuitable for use.

  The hard coat-coated polyolefin resin sheet of the present invention has high sheet surface hardness and excellent transparency in the visible light and infrared wavelength regions, so that it has high visibility and uses infrared rays such as an infrared sensor. Application to peripheral members is possible.

Claims (12)

A polyolefin resin sheet (A), a hard coat layer (C), and an adhesive layer (B) for bonding the polyolefin resin sheet (A) and the hard coat layer (C);
The average infrared transmittance in the infrared wavelength region of 8 μm to 14 μm is 5% or more,
Ri Der surface hardness 70N / mm ² or more was determined as Vickers hardness,
The polyolefin resin sheet (A) contains a polyethylene resin ,
Hard coat coated polyolefin resin sheet.   The hard coat coated polyolefin resin sheet according to claim 1, wherein the polyolefin resin sheet (A) is transparent.   The hard coat-coated polyolefin resin sheet according to claim 1 or 2, wherein the total light transmittance in a visible light region is 80% or more.   The hard coat coated polyolefin resin sheet according to any one of claims 1 to 3, wherein the thickness of the hard coat coated polyolefin resin sheet itself is 0.10 mm to 3.0 mm. The adhesive layer (B) has a thickness of 0.10 μm to 100 μm,
The hard coat-coated polyolefin resin sheet according to any one of claims 1 to 3, wherein the hard coat layer (C) has a thickness of 0.10 to 100 µm.   The hard coat coating according to any one of claims 1 to 5, wherein the hard coat layer (C) contains one or more selected from the group consisting of acrylic materials, silica materials, and carbon materials. Polyolefin resin sheet. The polyolefin-based resin sheet (A) is one obtained by rolling at the polyolefin-based resin sheet (A) to contain the polyolefin resin having a melting point below the temperature, any one of claims 1 to 6 Hard coat coated polyolefin resin sheet as described in 1. The hard coat coated polyolefin resin sheet according to any one of claims 1 to 7 , further comprising a primer layer (D) at an interface between the polyolefin resin sheet (A) and the adhesive layer (B). The hard coat-coated polyolefin resin sheet according to claim 8 , wherein the primer layer (D) contains an amine compound. The hard coat coated polyolefin resin sheet according to any one of claims 1 to 9, which is used as a member utilizing infrared rays. The hard coat-coated polyolefin resin sheet according to claim 10 , wherein the member is a member for the automobile industry, a member for the electrical equipment industry, or a member for medical use. The hard coat coated polyolefin resin sheet according to claim 10 , wherein the member is a display member for a touch panel.