JP2009275133A - Light-modifying sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light-modifying sheet which exhibits light-shielding properties because of its ability to show a large haze (%) variation in a relatively low temperature region (40-50°C) and exhibits its effect in a practical temperature region (25-50°C). <P>SOLUTION: The light-modifying sheet is produced by molding a resin composition comprising 50 to 200 pts.wt. particles of an average particle diameter of 3-50 μm based on 100 pts.wt. thermoplastic resin, wherein the haze variation (b-a) is 35% or larger (wherein a is the haze at 25°C and b is the haze at 50°C as measured according to JIS K7136). <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a light-controllable sheet whose transparency changes with environmental temperature changes. More specifically, the thermoplastic resin is blended with particles having a specific average particle diameter, exhibits a sufficient light shielding property in a relatively low temperature range (40 to 50 ° C.), and has a practical temperature range (25 to 25 ° C.). 50 ° C), the present invention relates to a light-controllable sheet having a good reversible change in transparency.

  Conventionally, resin compositions whose light transmittance changes reversibly with changes in environmental temperature are known. For example, Patent Document 1 is composed of a linear α-olefin polymer having 14 or more carbon atoms and another α-olefin polymer or a methacrylic acid ester polymer, and the light transmittance as the environmental temperature changes. Disclosed is a resin composition in which reversibly changes.

Furthermore, Patent Document 2 discloses a resin composition in which the light diffusivity changes reversibly with a change in environmental temperature by blending a resin and particles.
Japanese Patent No. 2706701 JP 2001-226604 A

  In the invention described in Patent Document 1, there is a problem that the decrease in light transmittance is not efficient from the viewpoint of effective use of light.

  Further, in the invention described in Patent Document 2, the light diffusivity is not sufficiently large in a relatively low temperature region (40 to 50 ° C.), and the dimming property is not sufficient in a practical temperature region (25 to 50 ° C.). There was a problem.

  Therefore, the present invention is a light-controllable sheet in which the transparency changes reversibly by increasing the amount of change in haze value (%) due to environmental temperature changes, and is particularly a relatively low temperature region (40 to 50). It is an object of the present invention to provide a light-controllable sheet that exhibits light shielding properties at a temperature of 25 ° C. and has a good reversible transparency change in a practical temperature range (25 to 50 ° C.).

  As a result of intensive studies to solve these problems, the present inventor has blended particles having an average particle diameter of 3 μm or more and 50 μm or less with respect to 100 parts by weight of the thermoplastic resin, exceeding 50 parts by weight and 200 parts by weight or less. The amount of change ba of the haze value when the haze value at 25 ° C. measured according to JIS K7136 is a and the haze value at 50 ° C. is b is 35. It has been found that the above-mentioned problems can be solved by a light-controllable sheet of at least%, and the present invention has been completed.

  The first aspect of the present invention comprises molding a resin composition in which particles having an average particle size of 3 μm or more and 50 μm or less are blended in an amount of more than 50 parts by weight and 200 parts by weight or less with respect to 100 parts by weight of a thermoplastic resin. Dimming, characterized in that the haze value change b−a is 35% or more when the haze value at 25 ° C. measured in accordance with JIS K7136 is a and the haze value at 50 ° C. is b. It is a sex sheet.

  The light control sheet according to the first aspect of the present invention has a large range of change in transparency (transparent to cloudiness) due to temperature change in a practical temperature range (25 to 50 ° C.), and a favorable reversible change in transparency. can do.

  Conventionally, for example, a light control sheet as described in Patent Document 2 has been studied for light control properties with a value of a light diffusivity that does not consider the measurement angle. However, in order to significantly increase the haze value in a relatively low temperature region (40 to 50 ° C.), the present inventors simply add particles to the resin to increase the refractive index difference and increase the light diffusivity. Rather, it is important to increase the light diffusivity by increasing the diffusion intensity at various measurement angles, more specifically the diffusion angle distribution at various incident angles, measured using a goniophotometer. I found out. In order to increase the diffusion angle distribution at various incident angles and increase the light diffusion rate, the average particle diameter of the particles added to the thermoplastic resin and the content thereof are set within a predetermined range. It came to the conclusion that the amount of change in haze value in the temperature range (25-50 ° C.) can be significantly increased.

  In the first aspect of the present invention, the light control sheet comprises a resin composition in which particles having an average particle diameter of 3 μm or more and 50 μm or less are mixed with more than 50 parts by weight and 200 parts by weight or less with respect to 100 parts by weight of the thermoplastic resin. It is molded and needs to have a predetermined haze value. When the content of the particles is 50 parts by weight or less with respect to 100 parts by weight of the thermoplastic resin, the shielding property at the time of cloudiness is insufficient, When the amount is 200 parts by weight or more with respect to 100 parts by weight of the plastic resin, it becomes difficult to mold the resin composition.

  Further, if the average particle size of the particles is smaller than 3 μm, sufficient shielding properties cannot be obtained when clouded, and if the average particle size is larger than 50 μm, it becomes difficult to mold the resin composition.

  In the first aspect of the present invention, the dimming sheet has a haze value change amount b−a when the haze value at 25 ° C. measured according to JIS K7136 is a and the haze value at 50 ° C. is b. 35% or more. When the haze is adjusted in such a range, the transparency before the temperature rise and the white turbidity after the temperature rise are excellent, and the transparency change can be improved.

  1st invention WHEREIN: It is preferable that the thermoplastic resin which comprises a light control sheet | seat is an ethylene-vinyl acetate copolymer, Especially, the vinyl acetate component in the said ethylene-vinyl acetate copolymer is 10-50 weight. % Is more preferable.

  In the first invention, the particles contained in the thermoplastic resin constituting the light control sheet are preferably crosslinked acrylic particles.

  In the first invention, the thickness of the light control sheet is preferably 10 to 200 μm. By setting it to such a thickness, there are advantageous effects such as quick change of the temperature of the sheet and improvement of responsiveness of transparent-white turbidity, and it can be said that it is practical from an economical viewpoint. In the present invention, the content of the particles contained in the thermoplastic resin constituting the light control sheet needs to be 50 to 200 parts by weight with respect to 100 parts by weight of the thermoplastic resin. Such a content can have a very advantageous effect in the thickness of the practical range as described above. So far, a relatively thick light control sheet having a thickness of 200 μm or more has been proposed, and in such a thickness, the content of particles added to the thermoplastic resin was 50 parts by weight or less. When the content of the added particles is 50 parts by weight or less at a practical thickness, the reversible transparency change cannot be made satisfactory.

  2nd this invention is a laminated body formed by laminating | stacking at least 1 layer of the light control sheet | seat of 1st this invention.

  The laminated body according to the second aspect of the present invention can exhibit effects such as improvement in mechanical strength because at least one layer of the light control sheet according to the first aspect of the present invention is laminated.

  In the second aspect of the present invention, the laminate preferably further comprises at least one sheet mainly composed of polycarbonate. By adopting such a configuration, the mechanical strength can be improved, and a stable shape can be maintained.

  According to the present invention, dimming properties that reversibly change transparency in a practical temperature range (25 to 50 ° C.) by exhibiting sufficient light shielding properties in a relatively low temperature range (40 to 50 ° C.). A sheet can be provided, and the dimmable sheet can be suitably used as various window materials such as a carport and a multi-layer window.

  Embodiments of the present invention will be described below. Note that the boundary between the sheet and the film is not clear, and it is not necessary to distinguish the two in terms of the present invention. Therefore, in the present invention, the term “sheet” includes “film”. In addition, the expression “main component” includes the meaning of allowing other components to be contained within a range that does not hinder the function of the main component unless otherwise specified. In particular, the content ratio of the main component is not specified, but usually the component (when two or more components are the main components, the total amount thereof) is 50% by mass or more, particularly 70% by mass in the composition. % Or more, especially 90% by mass or more (including 100%).

<Light control sheet>
The light control sheet of the present invention is formed by molding a resin composition in which particles having an average particle size of 3 μm or more and 50 μm or less are mixed with more than 50 parts by weight and 200 parts by weight or less with respect to 100 parts by weight of a thermoplastic resin. It will be.

(Haze of light control sheet)
The light control sheet of the present invention has a haze value change amount b-a of 35% or more when the haze value at 25 ° C. measured in accordance with JIS K7136 is a and the haze value at 50 ° C. is b. However, it is more preferably 40% or more. The haze value b at 50 ° C. is preferably 55% or more, more preferably 60% or more, and the haze value change ba is 35% or more, and the haze value at 50 ° C. Most preferably, the value b is 55% or more. By setting it as such a range, in the practical temperature range, the transparency change width (transparent to cloudiness) by a temperature change is large, and a reversible transparency change can be made favorable.

  1st invention WHEREIN: As above-mentioned, it is preferable that the thickness of a light control sheet | seat is 10-200 micrometers, It is more preferable that it is 30-200 micrometers, It is further more preferable that it is 50-150 micrometers. If the thickness is adjusted to the above range, reversible transparency change can be improved.

(Resin composition)
1st invention WHEREIN: As a resin composition which comprises a light control sheet, a thermoplastic resin and particle | grains are mix | blended, The compounding quantity of the said thermoplastic resin and the said particle | grains, and the average particle diameter of particle | grains If it is a predetermined range, it will not restrict | limit, What is necessary is just to combine the thermoplastic resin illustrated below and particle | grains suitably.

(Thermoplastic resin)
The thermoplastic resin is not particularly limited. For example, a linear α-olefin polymer having 14 or more carbon atoms described in Patent Document 1 and another α-olefin polymer or a methacrylic acid ester polymer And α-olefin polymers and methacrylic acid polymers described in JP-A No. 64-9267. In addition, polyolefin resins such as polyethylene and polypropylene, polyvinyl chloride resins, polyvinyl acetate resins, polyethylene terephthalate, polyethylene naphthalate, polylactic acid, polyester resins such as polycaprolactone, and norbornene polymers. Cyclic polyolefin resins, polycarbonate resins, polysulfone resins, polyether sulfone resins, polyarylate resins, polyvinyl alcohol resins, polyurethane resins, polyacrylate resins, polymethacrylate resins, epoxy resins, Examples include synthetic polymers such as polyalkylene oxides such as polyethylene oxide and polypropylene oxide. The synthetic polymer may be a copolymer obtained from two or more kinds of monomers, and specifically includes an ethylene-vinyl acetate copolymer. In addition, natural polymers such as cellulose resins such as cellulose diacetate and cellulose triacetate can be exemplified, and these can be used alone or in combination of two or more thereof. Among them, ethylene-vinyl acetate copolymer is used. Is preferable from the viewpoint of transparency and the like, and the vinyl acetate component is more preferably 10 to 50% by weight from the viewpoint of temperature dependency of the refractive index.

  Among the above thermoplastic resins, a thermoplastic resin having an absolute value of refractive index difference of at least 0.01 or more is preferable in a range of 20 to 70 ° C., and a thermoplastic resin having an absolute value of refractive index difference of 0.03 or more. A resin is more preferable. If the thermoplastic resin in such a range is used, the range of change in transparency (transparent to cloudiness) due to temperature change is large, and the reversible change in transparency can be made favorable.

(Particles contained in the resin composition)
The particles need to be particles having an average particle diameter of 3 μm or more and 50 μm or less, but among them, the average particle diameter is preferably 3 to 30 μm for the reason of balance between shielding properties and sheet formability during cloudiness. 5 to 20 μm is more preferable. The particles are observed with a microscope, and the average of the diameter of the circle circumscribing the particle and the shortest length from the center of the circle to the end of the particle is observed, and 100 particles are observed at different locations. The average value was taken as the average particle size. Further, as described above, the light control sheet of the present invention increases the diffusion angle distribution at various incident angles and increases the light diffusivity by adding a specific amount of particles having the above average particle diameter to the thermoplastic resin. However, the increase in the distribution of reflected light in various incident light is also caused by the particle size distribution of the particles. That is, instead of using particles having a uniform particle size, it is preferable to use particles having a distribution in particle size. Examples of particles having a particle size distribution include MR-7G (average particle size) manufactured by Soken Chemical Co., Ltd. Diameter 5 μm), MR-10G (average particle size 10 μm), MR-20G (average particle size 20 μm), MR-30G (average particle size 30 μm).

  The content of the particles needs to be more than 50 parts by weight and 200 parts by weight or less with respect to 100 parts by weight of the thermoplastic resin. For balance reasons, it is preferably 51 to 150 parts by weight, more preferably 60 to 130 parts by weight.

  Furthermore, as the material of the particles, for example, as organic particles, polymer particles such as polystyrene, polyethylene, polypropylene, polymethyl methacrylate resin and cross-linked polymers, ethylene, propylene, styrene, methyl methacrylate, benzoguanamine, formaldehyde Examples of inorganic particles include glass beads, silica, silicone, titanium oxide, zeolite, mica, talc, and the like. Can be mentioned. Among these, it is preferable to use a crosslinked acrylic particle for the reason of dispersibility.

<Manufacturing method of light control sheet>
The production method of the light control sheet in the present invention is not particularly limited. For example, the above-described thermoplastic resin and particles are melt kneaded using a single screw extruder, twin screw extruder, roll, Banbury mixer, kneader, or the like. Then, a method of forming into a sheet shape using a T-die is mentioned. Moreover, after melt | dissolving and disperse | distributing a thermoplastic resin and particle | grains in a solvent, the method of shape | molding in a sheet | seat shape except a solvent is mentioned.

<Application of light control sheet>
Since the light-controllable sheet of the present invention has a property of changing from transparent to cloudy depending on the temperature, the use thereof is a field having an anti-glare effect and an indoor temperature rise suppressing effect when the indoor temperature rises, for example, Various window materials such as carports and multi-layer windows, partitions for privacy protection, door materials, etc. can be mentioned, and applications to temperature display materials and screens for image projection are also possible.

<Laminated body>
The laminate of the present invention requires at least one layer to be the light control sheet of the first invention, and preferably includes at least one sheet mainly composed of polycarbonate. The sheet containing polycarbonate as a main component is not particularly limited, and a known sheet can be used, and examples thereof include “STELLA” manufactured by Mitsubishi Plastics.

  The thickness of the sheet containing polycarbonate as a main component is preferably 0.1 to 20 mm, more preferably 1 to 10 mm, for reasons such as mechanical strength.

<Method for producing laminate>
As a method for producing the laminate of the present invention, a known method can be employed. For example, a method of thermocompression bonding the light control sheet of the present invention using a sheet mainly composed of polycarbonate as a base material, Examples include a method in which a plastic resin and particles are dissolved and dispersed in a solvent, and then applied to a base sheet and dried to remove the solvent to obtain a laminate.

(Refractive index of thermoplastic resin)
About ethylene vinyl acetate copolymer (Mitsui / DuPont Polychemical, “Evaflex V421”), Abbe refractometer NAR-2T (manufactured by Atago Co., Ltd.), 20 ° C., 30 ° C., 50 ° C., and 70 ° C. The refractive index of the resin at each temperature was measured, and the results are shown in Table 1.

Example 1
100 parts by weight of cross-linked acrylic particles having an average particle diameter of 5 μm (“MX-500”, manufactured by Soken Chemical Co., Ltd.) per 100 parts by weight of ethylene vinyl acetate copolymer (Mitsui / DuPont Polychemical, “Evaflex V421”) Was kneaded for 5 minutes under the conditions of a temperature of 150 ° C. and a rotation speed of 60 rpm using a lab plast mill. This kneaded product is formed into a sheet having a thickness of 100 μm by hot pressing, and this sheet is further made into an acrylic film (manufactured by Kaneka Corporation, “Sanduren NR-38”) and a polycarbonate plate (manufactured by Mitsubishi Plastics, “Stella”, thickness 2 mm) to obtain a laminate. The vinyl acetate component in the ethylene vinyl acetate copolymer was 28% by weight.

(Example 2)
A sheet and a laminate were obtained in the same manner as in Example 1 except that 100 parts by weight of crosslinked acrylic particles having an average particle size of 20 μm (“MX-2000” manufactured by Soken Chemical Co., Ltd.) was used.

(Example 3)
A sheet and a laminate were obtained in the same manner as in Example 1 except that 100 parts by weight of crosslinked acrylic particles having an average particle diameter of 10 μm (manufactured by Soken Chemical Co., Ltd., “MR-10HG”) was used.

(Comparative Example 1)
A polycarbonate plate “Stella” (thickness 2 mm) manufactured by Mitsubishi Plastics was used as a laminate.

(Comparative Example 2)
A sheet and a laminate were obtained in the same manner as in Example 1 except that 100 parts by weight of a crosslinked acrylic particle having an average particle size of 1.5 μm (“MX-150” manufactured by Soken Chemical Co., Ltd.) was used.

(Comparative Example 3)
A sheet and a laminate were obtained in the same manner as in Example 1 except that 100 parts by weight of a crosslinked acrylic having an average particle size of 2 μm (manufactured by Soken Chemical Co., Ltd., “MR-2HG”) was used.

  The following tests were performed using the sheets and laminates obtained in Examples 1 to 3 and Comparative Examples 1 to 3.

(Haze)
About the laminated body of Examples 1-3 and Comparative Examples 1-3, based on JISK7136, temperature 25 degreeC (room temperature) and 50 using a haze meter (Murakami Color Research Laboratory Co., Ltd. HM-150). The haze value (%) at ° C. was measured. The results are shown in Table 2.

(Total light transmittance)
About the laminated body of Examples 1-3 and Comparative Examples 1-3, based on JISK7361-1, all using the haze meter (Murakami Color Research Laboratory Co., Ltd. HM-150) at the temperature of 50 degreeC. The light transmittance (%) was measured. The results are shown in Table 2.

(Transmission shielding at 50 ° C)
About the laminated body of Examples 1-3 and Comparative Examples 1-3, when a test piece was heated at 50 degreeC and the other side was visually recognized through the test piece immediately after that, what was easily visible on the other side x was somewhat visible. Those that were difficult to do were marked with Δ, and those that were hardly visible were marked with ○. The results are shown in Table 2.

  From Table 1, the light control sheet (Examples 1 to 3) of the present invention had a large amount of change in haze and good transparency change in the practical temperature range (25 to 50 ° C.). On the other hand, in the sheets of Comparative Examples 1 to 3, the amount of change in haze was small and the transparency change was insufficient in the practical temperature range (25 to 50 ° C.). Although it is difficult to understand this difference numerically, as shown in the drawings, it has been confirmed that the difference between the above numerical values becomes very large in actual transparency change.

  While the present invention has been described in connection with embodiments that are presently the most practical and preferred, the present invention is not limited to the embodiments disclosed herein. However, it should be understood that the present invention can be appropriately changed without departing from the spirit or idea of the invention that can be read from the claims and the entire specification, and is included in the technical scope of the present invention.

It is the figure which showed the result of the transparency change accompanying a temperature change about the laminated body in Example 1. FIG. It is the figure which showed the result of the transparency change accompanying a temperature change about the laminated body in Example 2. FIG. It is the figure which showed the result of the transparency change accompanying a temperature change about the laminated body in Example 3. FIG. It is the figure which showed the result of the transparency change accompanying a temperature change about the laminated body in the comparative example 2. FIG. It is the figure which showed the result of the transparency change accompanying a temperature change about the laminated body in the comparative example 3. FIG.

Claims (7)

A resin composition in which particles having an average particle size of 3 μm or more and 50 μm or less are blended in excess of 50 parts by weight to 200 parts by weight or less with respect to 100 parts by weight of a thermoplastic resin is measured in accordance with JIS K7136. A light-controllable sheet, wherein the haze value change amount b−a is 35% or more when the haze value at 25 ° C. is a and the haze value at 50 ° C. is b. The light control sheet according to claim 1, wherein the particles are crosslinked acrylic particles. The light control sheet according to claim 1, wherein the thermoplastic resin is an ethylene-vinyl acetate copolymer. The light control sheet according to claim 3, wherein the vinyl acetate component in the ethylene-vinyl acetate copolymer is 10 to 50% by weight. The light control sheet according to any one of claims 1 to 4, which has a thickness of 10 to 200 µm. The laminated body in which at least 1 layer consists of a light control sheet in any one of Claims 1-5. Furthermore, the laminated body of Claim 6 provided with the sheet | seat which has a polycarbonate as a main component at least 1 layer.