JP7151263B2 - Resin sheet laminate and protective film set - Google Patents

Description

The present invention relates to a resin sheet laminate and a protective film set.

2. Description of the Related Art In recent years, there has been known a head-up display device that is mounted on an automobile and used (see, for example, Patent Document 1).

The head-up display device described in Patent Document 1 emits red (R), green (G), and blue (B) laser beams from a laser light source, respectively, and uses the windshield as a screen to display an image on the screen. can be formed. Also, in this head-up display device, a laser light source is housed in a housing. The housing is provided with a translucent emission window through which the laser light is emitted (transmitted) toward the screen.

The exit window comprises a polarizing layer made of a polarizer and a resin layer covering the polarizing layer. The resin layer is mainly made of a polycarbonate resin, and the slow axis of the polarizing layer is It has been proposed to use a cover member (translucent resin sheet) that is arranged in substantially the same direction as the absorption axis of the polarizing layer (see, for example, Patent Document 2).

Further, the cover member having such a configuration is attached to the housing as an emission window in a curved state in which a concave portion is formed in the central portion.

Therefore, in order to maintain the display quality of the image displayed by the laser beam transmitted through this cover member (exit window), it is possible to prevent erroneous insertion into the housing in both vertical and horizontal directions and up and down (front and back) directions. required to be worn against Therefore, before being cut into the shape of the exit window of the housing, the cover member is generally formed as a long sheet so that the vertical and horizontal directions can be distinguished, and furthermore, the cover member is formed as a long sheet so that the vertical direction can be distinguished. In addition, peelable protective films having different color tones are laminated on the upper surface (front surface) and the lower surface (back surface) of the cover member (long sheet).

However, in the case of determining the vertical direction, since the cover member has translucency, when the protective films are laminated on the upper surface and the lower surface, different colors are mixed with each other. As a result, there is a problem that it is difficult to distinguish between the top and bottom until at least a part of the protective film is peeled off from the cover member.

Such problems are not limited to the protective film laminated (attached) to the exit window (cover member) provided in the above-described head-up display device, but also smartphones, PC displays, car navigation systems, clusters and center information displays. The same phenomenon occurs in the protective film laminated on the display portion (translucent resin sheet) provided by the like.

Japanese Unexamined Patent Application Publication No. 2015-225244 Japanese Patent Application Laid-Open No. 2017-116882

An object of the present invention is to provide a resin sheet laminate capable of distinguishing the vertical direction of a translucent resin sheet in a state in which a protective film is laminated on each of the upper surface and the lower surface of the translucent resin sheet. An object of the present invention is to provide a protective film set with which a resin sheet laminate can be produced.

Such objects are achieved by the present invention described in (1) to ( 4 ) below.
(1) having a light-transmitting resin sheet having light-transmitting properties and protective films peelably laminated on both sides of the light-transmitting resin sheet,
The translucent resin sheet, with the protective film removed, is used as a translucent cover member provided in a projection display,
A resin sheet laminate, wherein the protective films on both sides have different reflectances.

(2) The above (1), wherein the reflectance of light with a wavelength of 550 nm is set lower on the surface of one of the protective films on both sides than on the surface of the other protective film. The resin sheet laminate according to .

(3) The reflectance of light with a wavelength of 550 nm is 5.0% or less on the surface of one of the protective films, and the reflectance on the surface of one protective film and the surface of the other protective film The resin sheet laminate according to (2) above, which has a difference from the reflectance of 0.4% or more.

( 4 ) A protective film set comprising a pair of protective films detachably laminated on both sides of a translucent resin sheet having translucency,
The translucent resin sheet, with the protective film removed, is used as a translucent cover member provided in a projection display,
A protective film set, wherein the protective film laminated on one surface and the protective film laminated on the other surface have different reflectances.

In the present invention, the protective films laminated on both the upper surface and the lower surface of the translucent resin sheet have different reflectances. Therefore, based on this difference in reflectance, the protective film is laminated on the upper surface and the lower surface of the translucent resin sheet, respectively, and the protective film is laminated on the surface and the protective film is laminated on the back surface. As a result, it is possible to determine the vertical direction of the translucent resin sheet.

1 is a side view showing an embodiment of a head-up display for an automobile, which has, as a cover member, a translucent resin sheet included in the resin sheet laminate of the present invention; FIG. FIG. 2 is an enlarged cross-sectional view of a region [A] surrounded by a dashed line in FIG. 1; FIG. 3 is an enlarged sectional view of a cover member in FIG. 2; 4 is an enlarged cross-sectional view showing a resin sheet laminate in which a protective film is laminated on the cover member shown in FIG. 3; FIG.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the resin sheet laminate and the protective film set of the present invention will be described in detail based on preferred embodiments shown in the accompanying drawings.

First, before describing the resin sheet laminate and the protective film set of the present invention, an automobile having a translucent resin sheet included in the resin sheet laminate of the present invention as a cover member (translucent cover member) head-up display (projection display) will be described.

<Head-up display>
FIG. 1 is a side view showing an embodiment of a head-up display for an automobile, which has a translucent resin sheet included in the resin sheet laminate of the present invention as a cover member. FIG. 2 is an enlarged cross-sectional view of a region [A] surrounded by a dashed line in FIG. 3 is an enlarged cross-sectional view of the cover member in FIG. 2, and FIG. 4 is an enlarged cross-sectional view showing a resin sheet laminate in which a protective film is laminated on the cover member shown in FIG. For convenience of explanation, the upper side in FIGS. 1 to 4 is hereinafter referred to as "upper" or "upper", and the lower side is referred to as "lower" or "lower". In addition, the left side in FIGS. 1 and 2 is called "front" or "front", and the right side is called "rear" or "rear". Also, in FIGS. 3 and 4, for ease of understanding, the cover member is shown in a flat state, and the thickness direction is exaggerated and schematically shown.

As shown in FIG. 1, a head-up display 10 is mounted on an automobile 100 and used. This head-up display 10 is built in the upper part of the dashboard 101 of the automobile 100 .

As shown in FIG. 2 , head-up display 10 includes light source 11 , reflecting member 12 , and housing 13 .

The light source 11 can independently irradiate laser beams LS of red (R), green (G), and blue (B) colors. An image can be formed by controlling the irradiation timing of the laser light LS of each color while scanning the light source 11 .

The reflecting member 12 is composed of, for example, a prism, and can reflect the laser beam LS from the light source 11 . The laser light LS reflected by the reflecting member 12 is projected onto the rear surface 102a (inner surface) of the windshield 102 using the windshield 102 as a screen. This projected light is recognized by the driver H as the image (see FIGS. 1 and 2).

As shown in FIG. 2, the storage body 13 (housing) has a box-like shape, and can house the light source 11, the reflecting member 12, and other parts constituting the head-up display 10 inside. Further, the storage body 13 has a window portion 131 configured by an opening that opens toward the windshield 102 side. Through this window portion 131 , the laser beam LS is emitted toward the outside of the container 13 , that is, toward the windshield 102 .

Moreover, the cover member 1 having translucency is installed on the window portion 131 of the container 13 so as to cover the window portion 131 . As a result, the laser beam LS can be emitted toward the windshield 102 , and foreign matter such as dust can be prevented from entering the storage body 13 through the window portion 131 . Therefore, it is possible to prevent the lens of the light source 11 and the reflecting member 12 from becoming cloudy or dirty due to the foreign matter.

As shown in FIG. 3, the cover member 1 has optical transparency. and bonding layer 4B, and hard coat layer 5A and hard coat layer 5B. Each layer will be described below.

The first resin layer 2 is an intermediate layer located in the center of the cover member 1 in the thickness direction, and is a portion with a constant thickness t2 in the surface direction of the cover member ₁ .

The first resin layer 2 is mainly composed of polyvinyl alcohol (PVA) resin.

In this embodiment, the first resin layer 2 is a polyvinyl alcohol resin dyed with a dichroic dye such as iodine or a dichroic dye and crosslinked with a boron compound or the like. In this case, the content of the polyvinyl alcohol resin in the first resin layer 2 is preferably 1% or more and 8% or less, more preferably 2% or more and 5% or less.

Also, the first resin layer 2 is formed by processing a sheet material (film) made of the above constituent material. That is, the sheet material is a sheet material thicker than the thickness t2 of the _first resin layer ₂ in the cover member 1, and the sheet material is stretched in one direction until the thickness becomes t2. The 1st resin layer 2 is obtained by setting it as a state. As a result, the first resin layer 2 becomes a polarizing layer functioning as a polarizer because the polyvinyl alcohol resin (polymer) is aligned along one direction in which the first resin layer 2 is stretched.

_The thickness t2 is not particularly limited, and is preferably 0.01 mm or more and 0.03 mm or less, for example. If the thickness t2 is less _than 0.01 mm, the first resin layer ₂ may not sufficiently exhibit its function as a polarizer. The improvement of the function as a polarizer cannot be expected.

The refractive index of the first resin layer 2 is not particularly limited, and is preferably 1.52 or more and 1.67 or less, more preferably 1.54 or more and 1.60 or less.

As shown in FIG. 3, the second resin layer 3A is arranged on the upper surface 21 side of the first resin layer 2, and the second resin layer 3B is arranged on the lower surface 22 side. Since the second resin layer 3A and the second resin layer 3B have the same configuration except that the second resin layer 3A and the second resin layer 3B are arranged at different locations and that the second resin layer 3A contains particles 31 composed of a metal oxide, The second resin layer 3A will be representatively described below.

The second resin layer 3A is mainly made of polycarbonate resin. The polycarbonate resin preferably has a weight average molecular weight of 19,000 to 40,000, more preferably 19,500 to 35,000. Thereby, the second resin layer 3A has, for example, sufficient impact resistance.

The second resin layer 3A is obtained by processing a polycarbonate resin sheet material containing metal oxide particles 31 . That is, the sheet material is a sheet material thicker than the thickness t3A of the second resin layer _3A in the cover member 1, and the sheet material is stretched in one direction until the thickness becomes _t3A . 3 A of 2nd resin layers are obtained by setting it as a state. Thereby, the second resin layer 3A is arranged along one direction in which the polycarbonate resin (polymer) is stretched in the layer. As a result, the second resin layer 3A has a retardation (birefringence×thickness) and a retardation in the thickness direction (Rth). For example, the retardation is preferably 2400 nm or more and 6000 nm or less, more preferably 3000 nm or more and 5600 nm or less.

The thickness t3A of the second resin layer _3A (the same applies to the thickness t3B of the second resin layer _3B ) is preferably 0.2 mm or more and 0.35 mm or less, and more preferably 0.23 mm or more and 0.35 mm or less. .30 mm or less. If the thickness _t3A is less than the lower limit, it may not be possible to expect the second resin layer _3A to have the retardation. There is a possibility that further improvement in function cannot be expected. Also, the thickness _t3A and the thickness _t3B may be different, but are preferably the same. When the thickness _t3A and the thickness _t3B are the same, there is an advantage that warping is less likely to occur when exposed to high temperatures.

The second resin layer 3A having such a configuration and the second resin layer 3B having a configuration in which the particles 31 are omitted from the second resin layer 3A each have a slow axis of the first resin layer 2. They are arranged in the same direction as the absorption axis. That is, in the second resin layer 3A (second resin layer 3B), the direction in which the polycarbonate resin (polymer) is arranged along one direction and in the first resin layer 2, the polyvinyl alcohol resin is aligned. 2nd resin layer 3A (2nd resin layer 3B) is arrange|positioned with respect to the 1st resin layer 2 so that the direction which arranges along a direction may become the same.

The "slow axis" is the direction in which the speed of light traveling through the second resin layer 3A or the second resin layer 3B is slow (the phase is delayed). The azimuth in which the traveling speed is fast (the phase advances) is called the "fast axis" of the retarder. The deviation between the slow axis and the absorption axis is allowed within ±5 degrees.

When the cover member 1 is used for the head-up display 10, as shown in FIG. , the light in a predetermined polarization direction is absorbed by the cover member 1 , and the remaining light OL′ reaches the container 13 . As a result, the penetration of the sunlight OL into the storage body 13 is suppressed, thereby preventing the light source 11, the reflecting member 12, and the like in the storage body 13 from deteriorating over time due to the sunlight OL (especially ultraviolet rays and heat). can be prevented as much as possible. On the other hand, the laser light LS that is emitted from the light source 11 and forms an image on the windshield 102 uses polarized light. Therefore, even if the light passes through the cover member 1, it is emitted to the outside as it is without being absorbed by the cover member 1. FIG. Note that the polarization direction of the laser light LS and the polarization direction of the light OL' are the same. Thus, the cover member 1 also functions as a polarizing plate.

Further, as described above, the second resin layer 3A and the second resin layer 3B are provided on both surface sides of the first resin layer 2, respectively. This configuration contributes to increasing the effect of absorbing the sunlight OL compared to the case where the second resin layer 3A or the second resin layer 3B is provided on one side of the first resin layer 2. do.

As shown in FIG. 2, the cover member 1 is attached to the window portion 131 in such a curved manner that the container 13 side is convex and the windshield 102 side is concave in the used state. As a result, the cover member 1 can easily reflect the sunlight OL, and can further suppress the penetration of the sunlight OL into the storage body 13 . In addition, for example, the cover member 1 can be prevented from protruding from the dashboard 101, so that the cover member 1 blocking the driver H's field of vision can be suppressed or prevented accurately.

The refractive index of the second resin layer 3A and the second resin layer 3B is not particularly limited, and is, for example, preferably 1.58 or more and 1.60 or less, and 1.585 or more and 1.595 or less. is more preferred.

As shown in FIG. 3, the second resin layer 3A contains dispersed particles 31 made of metal oxide. Particles 31 having such a configuration function as an IR (Infrared Rays) cutting material capable of absorbing infrared rays contained in sunlight OL. As a result, for example, it is possible to suppress the temperature rise in the storage body 13 under the scorching sun, and to appropriately suppress or prevent deterioration of the light source 11 and the like due to heat.

In the used cover member 1, that is, the cover member 1 attached to the window portion 131, the second resin layer 3A side containing the metal oxide faces the windshield 102, and the second resin layer 3B side faces the windshield 102. It faces the storage body 13 . As a result, the infrared rays can be absorbed as far away as possible from inside the container 13 , thereby contributing to suppressing the temperature rise inside the container 13 .

If the particles 31 (second resin layer 3A) do not need to absorb the infrared rays, the particles 31 may be omitted from the second resin layer 3B.

In addition, in the present embodiment, the first resin layer 2 and the second resin layer 3A are bonded via the bonding layer 4A, and the first resin layer 2 and the second resin layer 3B are bonded via the bonding layer 4A. 4B.

The bonding layer 4A and the bonding layer 4B are various adhesives or adhesives such as urethane adhesives, epoxy adhesives, acrylic adhesives, and acrylic adhesives. As a result, the layers can be reliably joined together, and the cover member 1 can be used for a long period of time.

The thickness t _4A of the bonding layer 4A and the thickness t _4B of the bonding layer 4B are not particularly limited. It is more preferable to have If the thickness t _4A and the thickness t _4B are less than the lower limit values, the adhesive strength may be _{lowered .} It is not expected to improve the adhesive strength of Also, the thickness _t4A and the thickness _t4B may be different, but are preferably the same.

The refractive index of the bonding layer 4A and the bonding layer 4B is not particularly limited, and is preferably 1.46 or more and 1.55 or less, more preferably 1.461 or more and 1.545 or less.

Further, a hard coat layer 5A is provided on the second resin layer 3A. Thereby, the second resin layer 3A, which is relatively easily damaged, can be protected. The hard coat layer 5A is made of an ultraviolet curable resin. A varnish-like material to be the hard coat layer 5A is applied on the second resin layer 3A, and the applied layer is irradiated with ultraviolet rays. It is hardened by

Similarly, a hard coat layer 5B is also provided on the second resin layer 3B. Thereby, the second resin layer 3B, which is relatively easily damaged, can be protected. The hard coat layer 5B is also made of an ultraviolet-curing resin. A varnish-like material that forms the hard coat layer 5B is applied on the second resin layer 3B, and the applied layer is irradiated with ultraviolet rays. It is hardened. Incidentally, in the cover member 1, the hard coat layer 5B may be omitted.

Examples of the ultraviolet curable resin constituting the hard coat layer 5A and the hard coat layer 5B include an ultraviolet curable resin mainly composed of an acrylic compound, an ultraviolet curable resin mainly composed of a urethane acrylate oligomer or a polyester urethane acrylate oligomer. UV curable resins containing at least one selected from the group consisting of resins, epoxy resins, and vinylphenol resins as a main component, and the like. Among these, an ultraviolet curable resin containing an acrylic compound as a main component is preferable. Thereby, the adhesiveness with each resin layer can be improved.

The thickness t _5A of the hard coat layer 5A and the thickness t _5B of the hard coat layer 5B are not particularly limited. More preferably: Also, the thickness _t5A and the thickness _t5B may be different, but are preferably the same.

The refractive index of the hard coat layer 5A and the hard coat layer 5B is not particularly limited. .

The cover member ₁ configured as described above preferably has a total thickness t1 of, for example, 0.4 mm or more and 1.0 mm or less, and more preferably 0.4 mm or more and 0.8 mm or less. As a result, the cover member 1 can be made as thin as possible and have sufficient rigidity to withstand normal use within the automobile 100 .

In addition, the cover member 1 has a rectangular shape in plan view, and preferably has a length of 50 mm or more and 200 mm or less, more preferably 60 mm or more and 190 mm or less, and a width of 100 mm or more and 400 mm or less. is preferred, and 130 mm or more and 380 mm or less is more preferred.

Now, in the cover member 1 having such a configuration, as described above, the first resin layer 2 and the second resin layers 3A and 3B are each formed in a stretched state in which they are stretched in one direction. is. Therefore, the polyvinyl alcohol resin and the polycarbonate resin (polymer) are aligned along one stretched direction (stretching direction) in these layers. Then, in each layer, the absorption axis of the first resin layer 2 and the slow phase of the second resin layers 3A and 3B formed due to the arrangement of the polymers along the stretching direction in this way are arranged in the same direction. Therefore, the cover member 1 is required to be attached to the window portion 131 of the storage body 13 without being erroneously inserted in the vertical and horizontal directions.

Further, for example, in the second resin layers 3A and 3B, the polycarbonate resin in the layers is arranged along the stretching direction while being oriented in the thickness direction. A thickness direction retardation (Rth) is set according to the degree of orientation with respect to. Further, in this embodiment, the second resin layer 3A contains the particles 31 and the second resin layer 3B does not contain the particles 31. As shown in FIG. For these reasons, in order to keep the display quality of the head-up display 10 constant, the cover member 1 is required to be attached to the window portion 131 without erroneous insertion even in the vertical (front and back) directions. be done. In addition, even when the second resin layer 3A is configured not to contain the particles 31, from the viewpoint of keeping the display quality of the head-up display 10 constant due to the thickness direction retardation (Rth), the vertical direction It is required to prevent erroneous insertion in

Therefore, before the cover member 1 is cut according to the shape of the window portion 131 (exit window) provided in the container 13 (housing), that is, when the cover member 1 is stored and transported, the vertical and horizontal directions can be determined. In addition, the top surface 51 (front surface) and the bottom surface 52 (back surface) of the cover member 1 (long sheet) are provided so that the vertical (front and back) directions can be distinguished. , a protective film 150A and a protective film 150B that can be peeled off are laminated (see FIG. 4). That is, before being cut, the cover member 1 (translucent resin sheet) is stored and/or transported as a resin sheet laminate 200 on which the protective films 150A and 150B are formed (laminated), and then cut. At this time, the protective films 150A and 150B are peeled off from the resin sheet laminate 200, and the cover member 1 is cut.

Here, as a method for determining the vertical direction of the cover member 1 by laminating the protective film 150A and the protective film 150B on the upper surface 51 (front surface) and the lower surface 52 (back surface) of the cover member 1, respectively, for example, A method of making the color tone of protective film 150A and protective film 150B different from each other is conceivable. However, in such a method, since the cover member 1 has translucency, when the protective film 150A and the protective film 150B are laminated on the upper surface 51 and the lower surface 52, respectively, different colors are mixed with each other. The top and bottom of the sheet laminate 200 have the same color tone, and until at least part of the protective films 150A and 150B are peeled off from the cover member 1, it is difficult to distinguish between the top and bottom.

Furthermore, as a method for determining the vertical direction, a method of marking the protective film 150A and the protective film 150B differently from each other such as upper (rear) and lower (front) is conceivable. However, in such a method, it is necessary to change the marking position according to the cut size of the cover member 1 (resin sheet laminate 200), which requires time and effort. Further, when marking is applied to the protective films 150A and 150B after laminating the protective film 150A and the protective film 150B on the upper surface 51 and the lower surface 52, respectively, it is said that the marking marks are transferred to the upper surface 51 and the lower surface 52. Problems can arise.

On the other hand, in the present invention, as another method for determining the vertical direction, a method of laminating protective films 150A and 150B having different reflectances is used. That is, the resin sheet laminate 200 is provided with protective films 150A and 150B that are detachably laminated on both surfaces (upper surface 51 and lower surface 52) of the cover member 1, respectively. have different reflectances (protective film set of the present invention). By using such a technique, the protective film 150A and the protective film 150B can be distinguished from each other based on the difference in reflectance on the surfaces of the protective films 150A and 150B. A judgment is made. Therefore, even if the cover member 1 has translucency, the reflectance of the protective films 150A and 150B located on the opposite side does not affect the reflectance of the protective films 150A and 150B. Since the protective film 150A and the protective film 150B can be reliably distinguished, it is possible to easily distinguish the upper and lower sides of the resin sheet laminate 200 (cover member 1). Since it is not necessary to mark the protective films 150A and 150B, it does not take much time and effort to form the markings, and marking marks are not transferred to the upper surface 51 and the lower surface 52.例文帳に追加

Such protective films 150A and 150B are set to have different light reflectances, preferably within a wavelength range of 380 nm or more and 780 nm or less, more preferably about 550 nm. This makes it possible to more reliably distinguish between the top and bottom of the resin sheet laminate 200 based on the difference in reflectance between the protective films 150A and 150B.

The distinction between the protective films 150A and 150B based on the difference in reflectance is specifically based on the reflectance of light with a wavelength of 550 nm. The surface has a lower reflectance for light with a wavelength of 550 nm compared to the surface of the other protective film. This makes it relatively easy to distinguish between the protective film 150A and the protective film 150B.

Furthermore, in this case, the reflectance of light with a wavelength of 550 nm is 5.0% or less on the surface of one protective film, and the reflectance on the surface of one protective film and the reflection on the surface of the other protective film It is preferable that the difference from the rate is 0.4% or more. As a result, one protective film with a low reflectance does not provide good image clarity, while the other protective film with a high reflectance provides good image clarity. It is possible to more easily distinguish (identify) the film 150A and the protective film 150B.

Moreover, it is preferable that the protective film 150A and the protective film 150B have different surface roughnesses. In addition to the reflectance, the difference in surface roughness makes it easier to distinguish between protective film 150A and protective film 150B.

When the surface roughness is different, the surface roughness measured in accordance with JIS B 0601 is 0.04 μm or more for one protective film, and the surface roughness for one protective film and the other The difference from the surface roughness of the protective film is preferably 0.1 μm or more. This makes it possible to more easily distinguish (identify) the protective film 150A and the protective film 150B with the human eye.

Each of the protective film 150A and the protective film 150B as described above is composed of a single-layer body or a laminate containing at least one of (meth)acrylic resin and olefin-based resin as a main material, By appropriately changing the combination of constituent materials contained in each layer, a difference is generated between the reflectance of one protective film and the reflectance of the other protective film, so that the reflectance of one protective film is low. , the reflectance of the other protective film is set high.

In this specification, the (meth)acrylic resin means a polymer of (meth)acrylic acid and its derivatives, or a copolymer of (meth)acrylic acid and its derivatives and other monomers. do. Here, (meth)acrylic acid or the like means acrylic acid or methacrylic acid.

Examples of (meth)acrylic resins include polyacrylic acid esters such as polyacrylic acid, polymethacrylic acid, polymethyl acrylate, polyethyl acrylate, polybutyl acrylate, and poly-2-ethylhexyl acrylate, and polymethacryl. polymethacrylic acid esters such as methyl acid, polyethyl methacrylate, polybutyl methacrylate, polyacrylonitrile, polymethacrylonitrile, polyacrylamide, butyl acrylate-ethyl acrylate-acrylonitrile copolymer, acrylonitrile-styrene copolymer, Methyl methacrylate-styrene copolymer, Methyl methacrylate-acrylonitrile copolymer, Methyl methacrylate-α-methylstyrene copolymer, Butyl acrylate-ethyl acrylate-acrylonitrile-2-hydroxyethyl methacrylate-methacrylic acid copolymer coalescence, butyl acrylate-ethyl acrylate-acrylonitrile-2-hydroxyethyl methacrylate-acrylic acid copolymer, butyl acrylate-acrylonitrile-2-hydroxyethyl methacrylate copolymer, butyl acrylate-acrylonitrile-acrylic acid copolymer , ethyl acrylate-acrylonitrile-N,N dimethylacrylamide copolymer and the like.

Examples of olefin resins include homopolymers of α-olefins and copolymers of α-olefins with other copolymerizable monomers. Examples include polyethylene (PE) and polypropylene (PP). , polybutene, 1,2-polybutadiene, ethylene-propylene copolymer, ethylene-butene copolymer, ethylene-4-methyl-1-pentene copolymer, ethylene-vinyl acetate copolymer (EVA), ethylene-anhydride Examples include maleic acid copolymers.

The copolymer may be either a block copolymer or a random copolymer.

As a specific combination of constituent materials of the protective films 150A and 150B, for example, a laminate having a first layer mainly made of PE and a second layer mainly made of EVA is used. As one protective film, a laminate comprising a first layer mainly made of PP and a second layer mainly made of (meth) acrylic resin is used as the other protective film with high reflectance, or PE A laminate comprising a first layer mainly composed of and a second layer mainly composed of (meth) acrylic resin is used as one protective film having a low reflectance, and a first layer mainly composed of PP and EVA and a second layer containing as a main material the other protective film having a high reflectance. When the protective films 150A and 150B are laminated bodies of the first layer and the second layer as described above, the protective films 150A and 150B are attached to the cover member 1 with the second layer facing the cover member 1. (Lamination).

In addition, the protective films 150A and 150B preferably have an average thickness of 20 μm or more and 100 μm or less, more preferably 30 μm or more and 80 μm or less. As a result, the functions of the protective films 150A and 150B described above can be reliably exhibited.

Although the resin sheet laminate and the protective film set of the present invention have been described above, the present invention is not limited to this, and the case where the protective film is composed of either a single layer body or a multilayer body (laminate) However, each constituent layer can be replaced with an arbitrary configuration that can exhibit the same function.

Furthermore, in the above-described embodiment, the translucent resin sheet in the resin sheet laminate (the resin sheet laminate of the present invention) in which the protective film set of the present invention is laminated on the translucent resin sheet is used for a head-up display of an automobile. Although the case where it is applied to a cover member (translucent cover member) provided in a (projection type display) has been described, the translucent resin sheet is not limited to such a cover member, and may be a sheet having optical transparency. There are no restrictions on the material if any, and for example, it may be a display unit provided in a smartphone, a PC display, a car navigation system, a cluster, a center information display, or the like.

EXAMPLES The present invention will now be described more specifically based on examples. In addition, the present invention is not limited at all by these examples.

1. Preparation of Protective Film First, the following protective films were prepared as protective films used to form the resin sheet laminates of each example and each comparative example.

<LDPE film 1>
LDPE film (adhesive surface: acrylic adhesive) (color: transparent, thickness: 65.0 μm) with a reflectance of light at a wavelength of 550 nm of 5.30% and a surface roughness Rz of 0.05 μm
<LDPE film 2>
LDPE film (adhesive surface: acrylic adhesive) (color: blue, thickness: 65.0 μm) with a reflectance of light at a wavelength of 550 nm of 5.30% and a surface roughness Rz of 0.04 μm
<Polypropylene film 1>
A polypropylene film with a reflectance of 4.90% for light at a wavelength of 550 nm and a surface roughness Rz of 0.15 μm (adhesive surface: acrylic adhesive) (color: transparent, thickness: 45.0 μm)
<LDPE film 3>
LDPE film (adhesive surface: acrylic adhesive) (color: blue, thickness: 65.0 μm) with a reflectance of light at a wavelength of 550 nm of 4.90% and a surface roughness Rz of 0.05 μm
<HDPE film 1>
HDPE film with a reflectance of 4.90% for light at a wavelength of 550 nm and a surface roughness Rz of 0.28 μm (adhesive surface: EVA-based adhesive) (color: green, thickness: 60.0 μm)
<HDPE film 2>
HDPE with a reflectance of 4.90% at a wavelength of 550 nm and a surface roughness Rz of 0.16 μm (adhesive surface: olefin adhesive) (color: white, thickness: 40.0 μm)
<Polypropylene film 2>
A polypropylene film (adhesive surface: LLDPE-based adhesive) with a reflectance of light at a wavelength of 550 nm of 4.30% and a surface roughness Rz of 1.08 μm (color: white, thickness: 50.0 μm)
<LDPE film 4>
LDPE film (adhesive surface: olefin-based adhesive) with a reflectance of 4.90% for light at a wavelength of 550 nm and a surface roughness Rz of 0.13 μm (color: transparent, thickness: 50.0 μm)

The reflectance of each protective film was measured in the range of 380 nm to 780 nm at 5 degrees of incidence using a spectrophotometer (manufactured by JASCO Corporation, "V-670"). In addition, the surface roughness Rz of each protective film is measured using a spectrophotometer (manufactured by Tokyo Seimitsu Co., Ltd., "HADY SURF E-35A") in accordance with JIS B 0601, cutoff: 0.80 mm, evaluation length Thickness: Measured under the condition of 4.0 mm.

2. Production of resin sheet laminate (Example 1)
As a translucent resin sheet, a polycarbonate resin substrate (“Finelight ECLR100V2” manufactured by Sumitomo Bakelite Co., Ltd., thickness 500 μm) with a length of 50 mm and a width of 50 mm was prepared, and the surface (upper surface) and back surface of this translucent resin sheet were prepared. The resin sheet laminate of Example 1 was obtained by attaching (laminating) an LDPE film 1 and a polypropylene film 1 to (lower surface), respectively.

(Examples 2 to 4, Comparative Examples 1 to 3)
Examples 2 to 4, 4 and 5 were prepared in the same manner as in Example 1 except that the combination of protective films attached to the front and back surfaces of the translucent resin sheet was changed as shown in Table 1. Resin sheet laminates of Comparative Examples 1 to 3 were obtained.

3. Evaluation The resin sheet laminate of each example and each comparative example was evaluated by the following methods.

<1> Difference in reflectance of protective film was used to measure the reflectance at 5 degrees incidence within the range of 380 nm to 780 nm.

Then, the reflectance of each protective film was evaluated at a wavelength of 550 nm, and based on the results, the absolute value of the difference in reflectance between the two protective films was determined.

<2> Distinguishability of protective film For the resin sheet laminates of each example and each comparative example, the front and back surfaces of the resin sheet laminate were examined under an environment of illuminance of 600 Lx without peeling off the protective film from the resin sheet laminate. made a judgment. Then, the evaluation was performed by marking ◯ when the front and back could be determined, and × when the determination was difficult.

Table 1 below shows the evaluation results of the resin sheet laminates of Examples and Comparative Examples obtained as described above.

As shown in Table 1, in the resin sheet laminate in each example, the two protective films attached to the front surface and the back surface have different reflectances, respectively. , it was possible to determine the front and back of the resin sheet laminate.

On the other hand, in the resin sheet laminates in each of the comparative examples, no difference in reflectance was observed between the two protective films attached to the front surface and the back surface, respectively. couldn't.

Reference Signs List 1 cover member 2 first resin layer 21 upper surface 22 lower surface 3A, 3B second resin layer 31 particles 4A, 4B joining layer 5A, 5B hard coat layer 51 upper surface 52 lower surface 10 head-up display (Head-Up Display)
REFERENCE SIGNS LIST 11 light source 12 reflective member 13 container 131 window 100 automobile 101 dashboard 102 windshield 102a rear surface (inner surface)
150A, 150B Protective film 200 Resin sheet laminate H Driver LS Laser beam OL Sunlight (natural light)
OL' light t1 _total thickness _t2 , _t3A , _t3B , _t4A , _t4B , _t5A , _t5B thickness

Claims (4)

A light-transmitting resin sheet having light-transmitting properties and protective films peelably laminated on both sides of the light-transmitting resin sheet,
The translucent resin sheet, with the protective film removed, is used as a translucent cover member provided in a projection display,
A resin sheet laminate, wherein the protective films on both sides have different reflectances. 2. The resin according to claim 1, wherein the reflectance of light having a wavelength of 550 nm is set lower on the surface of one of the protective films on both sides than on the surface of the other protective film. sheet laminate. The reflectance of light with a wavelength of 550 nm is 5.0% or less on the surface of one of the protective films, and the reflectance on the surface of one protective film and the reflectance on the surface of the other protective film 3. The resin sheet laminate according to claim 2, wherein the difference between is 0.4% or more. A protective film set comprising a pair of protective films detachably laminated on both sides of a translucent resin sheet having translucency,
The translucent resin sheet, with the protective film removed, is used as a translucent cover member provided in a projection display,
A protective film set, wherein the protective film laminated on one surface and the protective film laminated on the other surface have different reflectances.

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