CN1140888C - retroreflective sheeting - Google Patents

Abstract

The present invention provides a retroreflective sheet formed by laminating a fluororesin film having a total light transmittance of 80% or more on the surface layer of a smooth surface layer on the light incident side via an adhesive layer. sheet. The retro-reflective sheet material seldom forms ice or snow on the surface even when used in a cold region, and has excellent decontamination even against stains caused by tricks such as paint or ink.

Description

retroreflective sheeting

technical field

The present invention relates to a retro-reflective thin plate, which can be used for signs such as road signs and engineering signs, number plates of vehicles such as automobiles and mopeds, safety equipment such as clothes and lifesaving tools, sports goods such as ski poles, and scoring equipment such as kanbans etc.; especially, there is little ice or snow accumulation on the surface of the retro-reflective sheet even when it is used in a cold region, and even when the surface of the retro-reflective sheet is contaminated with paint, ink, etc., there is no need to use organic solvents, only by Stains can be easily removed by wiping or washing with water, and thus are excellent in desmearability.

Background technique

Retroreflective sheet materials capable of retroreflecting light toward a light source have long been known, and utilizing their retroreflectivity, the sheet materials have been widely used in various fields as described above.

However, these prior retroreflective sheet materials have various problems especially when they are used in cold regions. For example, when the temperature drops below freezing in winter, the water droplets attached to the surface of the retroreflective sheet will freeze and make the Retro-reflective performance is reduced. In addition, when it snows, snow will adhere to the surface of the retro-reflective sheet. If the amount of adhesion is significant, the display function as a mark will be completely lost. Therefore, in cold regions, snow and ice often occur and cause visibility problems. Trouble with drop or drop in retroreflective performance etc.

Regarding the attempt to prevent freezing and snow accumulation in such cold regions, several schemes have been proposed. For example, U.S. Patent No. 5,087,508 specification discloses that a heat storage material is equipped in the label, and the heat is used to prevent freezing and snow accumulation. Methods. However, in this method, there are problems such as cumbersome operation of disposing the heat storage material in the marking, and such dispensing also raises the cost, and the disadvantage is that it is very difficult to put it into wide use.

In addition, recently, especially the surface of signs such as road signs and engineering signs is often contaminated by paint, ink, etc. due to mischief, and troubles such as degradation of display functions as signs occur, which has become a problem. Attempts to restore the lost function by decontaminating such polluted signs have been made, for example, by coating a solution of acrylic cross-linked resin or the like on the surface of a retroreflective sheet, drying, Form a surface layer with strong solvent resistance, and implement methods such as wiping with an organic solvent to remove contamination in the case of contamination. However, in this method, a solvent for dissolving pollutants is required for decontamination anyway, and thus there is a disadvantage of causing adverse health effects on workers and adverse effects on the environment.

Furthermore, there is also known a so-called enclosed lens type retroreflective sheet material in which at least a part of the retroreflective sheet is made of a fluororesin film. For example, JP-A-4-86701 discloses a super-weather-resistant retro-reflective thin plate, which is sequentially laminated with high refractive index glass beads and focus layer film in a surface layer composed of a fluororesin film. , and then formed by covering a metal layer on the focus layer film.

According to this patent publication, it is also disclosed that the above-mentioned super weather-resistant retroreflective thin plate can be manufactured as follows: coating a coating with a fluororesin solution as the main component on a suitable support film, drying it to form a fluororesin surface layer, Coating a kind of coating material for adhesive layer film on this surface layer, after making it dry, embed glass beads in this adhesive layer film, and then coat a kind of coating material for focus layer film on it, make After drying, a metal reflective layer is formed on the focus layer film. In addition, an intermediate layer can also be set between the surface layer and the adhesive layer by the same method.

However, in the case of resins with low surface tension such as fluorine-based resins, most of them have poor solubility in organic solvents. When preparing an organic solvent solution of such resins, the selection range of resins may be narrowed or the selection of organic solvents may be limited. It is difficult and other problems, and the current situation is that it is not always possible to obtain a sufficiently satisfactory retroreflective sheet material.

The object of the present invention is, in view of the shortcomings of the prior art, to provide an improved retro-reflective sheet material, so that the retro-reflective sheet can be endowed with icing resistance and snow resistance through simple operations, and then marking class Even when the surface of a product using a retroreflective sheet is contaminated by paint, ink, etc., there is no need to use a wiping solvent that will adversely affect the human body or the environment, and the contamination can be easily removed by wiping or washing.

invention disclosure

The inventors of the present invention have conducted various researches on methods for improving the icing or snow accumulation on the surface of the retroreflective sheet, which are problematic in cold regions, and at the same time improving the ease of decontamination of the retroreflective sheet. As a result, it was found that , now through the extremely simple operation of adhering a transparent fluororesin film on the light-incident side surface of the retroreflective sheet via an adhesive layer, the icing resistance of the retroreflective sheet can be significantly improved. Snow accumulation and ease of pollution removal.

Therefore, according to the present invention, there is provided a retroreflective sheet material characterized in that it has a smooth surface layer on the light incident side, and a fluorine film having a total light transmittance of 80% or more is laminated on the surface via an adhesive layer. Resin-like film.

The retroreflective sheet material of the present invention will be described in more detail below.

According to the present invention, the type of retroreflective sheet pasted with a fluororesin film is not particularly limited as long as it has a smooth surface (that is, has a flat front face) on its light incident side. For example, an enclosed lens type retroreflective sheet can be used. Sheet, capsule lens type retroreflective sheet, capsule square corner retroreflective sheet, metallized square corner retroreflective sheet and other retroreflective sheet materials. These retroreflective sheets and their manufacturing methods are described in patent documents respectively. For example, the encapsulating lens type retroreflective sheet is described in Japanese Patent Publication No. 56-2921 (US Patent No. 4,025,674 specification), and the capsule lens type retroreflective sheet The sheet is described in JP-A-60-194405 (US Patent No. 4,653,854 specification), the capsule square-angle retroreflective sheet is described in US Patent No. 3,417,959 specification, and the metallized square-angle retroreflective sheet is described in JP-A Publication No. 49-106839 (US Patent No. 3,712,706 Specification) and the like, and the references to these documents are here used instead of their detailed descriptions.

The present invention is characterized in that a fluororesin film is pasted on the smooth light-incident side surface layer of the above-mentioned retroreflective sheet material.

As the fluororesin film to be pasted, a highly transparent film having a total light transmittance of 80% or more, preferably 85% or more, more preferably 90% or more can be used. In this specification, the total light transmittance of the fluororesin film is a value measured with "Hyez Meter TC-H III" (manufactured by Tokyo Denshoku Co., Ltd.).

In addition, the thickness of the above-mentioned fluororesin film is not particularly limited, and it can be changed in a wide range depending on the application of the retroreflective sheet, etc., but it can be generally 1 to 100 μm, preferably 5 to 80 μm, More preferably, it is in the range of 10 to 70 μm, more preferably in the range of 20 to 60 μm.

As the fluororesin that can be used for the preparation of such films, fluoroalkene monomers such as tetrafluoroethylene, chlorotrifluoroethylene, trifluoroethylene, vinylidene fluoride, vinyl fluoride, and hexafluoropropylene can be used, Homopolymers of fluorine-containing monomers other than fluoroalkene monomers such as perfluoroalkyl vinyl ether and perfluoroalkyl (meth)acrylate, etc., between these fluorine-containing monomers or between these fluorine-containing monomers and Polymers of other copolymerizable monomers, and mixtures of these homo(co)polymers with other resins.

Examples of the above-mentioned copolymerizable monomers include olefinic monomers such as ethylene and propylene, methyl vinyl ether, ethyl vinyl ether, n-butyl vinyl ether, cyclohexyl vinyl ether, cyclopentyl vinyl ether, etc. ) Alkyl vinyl ether monomer, vinyl acetate, vinyl propionate, vinyl pivalate, vinyl Versatic acid (trade name, manufactured by Shell), vinyl benzoate, vinyl p-tert-butylbenzoate Vinyl carboxylate monomers such as vinyl cyclohexanecarboxylate and isopropenyl acetate, vinyl halide monomers other than fluorine-containing monomers such as vinyl chloride and vinylidene chloride, methyl (meth)acrylate , ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, (meth)acrylic acid 2-Ethylhexyl, n-octyl (meth)acrylate, isooctyl (meth)acrylate, n-nonyl (meth)acrylate, isononyl (meth)acrylate, lauryl (meth)acrylate (meth)acrylate monomers, 2-hydroxyethyl vinyl ether, 3-hydroxypropyl vinyl ether, 4-hydroxybutyl vinyl ether, 2-hydroxyethyl allyl ether, (meth)acrylic acid 2 -Hydroxyl-containing monomers such as hydroxyethyl ester, hydroxyl-containing monomers such as acrylic acid and methacrylic acid, N,N-dimethylaminoethyl (meth)acrylate, N,N-diethyl (meth)acrylate Amino ethyl ester, N,N-diethylaminoethyl vinyl ether and other amino-containing monomers, glycidyl vinyl ether, glycidyl (meth)acrylate and other epoxy-containing monomers, trimethoxyvinyl methyl Silane, triethoxyvinylsilane, 2-(trimethoxysilyl)ethyl vinyl ether, γ-(methacryloyloxy)propyltrimethoxysilane, etc. containing hydrolyzable silyl mono Monomers, 2-(trimethylsiloxy) ethyl vinyl ether, 4-(trimethylsiloxy) butyl vinyl ether and other siloxy-containing monomers, trimethyl (meth)acrylate Silyl esters, vinyl 5-(trimethylsiloxycarbonyl)valerate, and other siloxycarbonyl-containing monomers.

These copolymerizable monomers can be used in a certain proportion, so that the surface tension of the film made from the formed fluorine-based copolymer reaches below 40 dyne/cm, preferably below 35 dyne/cm, and more preferably below 31 dyne/cm. In/cm below. Here, the surface tension of the film is a value measured as follows.

In the case of a film with a surface tension of 31 dynes/cm or more, various wetness index standard solutions [manufactured by Wako Pure Chemical Industries, Ltd. ) atmosphere on the surface of the film in a linear shape, after about 3 seconds, visually judge whether it is wet or not, and determine the surface tension of the film surface according to the number of the standard solution that is wet. In the case of films with surface tensions below 31 dyne/cm, the surface tension was determined by measuring the contact angle by the drop method using a methanol/water mixture.

Fluorine-based resins that can be preferably used in the present invention include polytetrafluoroethylene, tetrafluoroethylene/perfluoroalkyl vinyl ether copolymer, tetrafluoroethylene/hexafluoropropylene copolymer, tetrafluoroethylene / Hexafluoropropylene/perfluoroalkyl vinyl ether copolymer, tetrafluoroethylene/ethylene copolymer, polychlorotrifluoroethylene, chlorotrifluoroethylene/ethylene copolymer, polyvinylidene fluoride, polyvinyl fluoride, etc.

In addition, mixtures of these fluorine-based homo(co)polymers and other resins can also be used. Other resins that can be mixed include polyacetal-based resins, polycarbonate-based resins, polyamide-based resins, polystyrene-based resins, acrylic resins, vinyl acetate-based resins, polyurethane-based resins, phenol resins, polyimide resins.

The mixing ratio of these other resins may be a ratio enabling the surface tension of a film produced from the formed resin mixture to fall within the above range.

However, as a fluororesin that can be used particularly well in the present invention, it can be cited that the tetrafluoroethylene unit content is 15-85% by weight, preferably 25-75% by weight, more preferably 35-85% by weight. Tetrafluoroethylene/ethylene copolymers and polyvinylidene fluoride in the range of 65% by weight. These homo(co)polymers generally have a weight-average molecular weight of preferably 5,000 to 400,000, particularly 7,000 to 300,000, from the viewpoints of processability and film durability.

In addition, mixtures of the above-mentioned homo(co)polymers with the above-mentioned other resins can also be used. In this case, the fluorine-based homo(co)polymer preferably accounts for at least 70% by weight, especially more than 80% by weight, more especially 90% by weight, based on the weight of the mixture.

Moreover, as a commercially available homo(co)polymer containing fluorinated olefin units that can be used in the present invention, examples such as "Fluon (Fluon)", "Aflon (Aflon) TEE", "Aflon ( "Aflon) COP" (manufactured by Asahi Glass Co., Ltd. above), "Polyflon (polyfluoron) TFE", "Neoflon (New Fluoron) FEP", "Neoflon (New Fluoron) PFA", "Neoflon (New Fluoron) ) ETFE" (the above are manufactured by Daikin Industries, Ltd.), "Raflon (Teflon) TFE", "Raflon (Teflon) FEP", "Raflon (Teflon) PFA", "Raflon (Teflon) Fluoron) EPE", "Rafuzel (Teflon)" (the above are manufactured by Mitsui DuPont Fluorochemical Co., Ltd.) and the like.

In the fluorine-based resin used in the present invention, within the range that does not substantially affect the physical properties such as total light transmittance and surface tension of the film, if necessary, heat stabilizers, light stabilizers, Linking agent, coloring agent, etc.

The above-mentioned fluororesins are preferably processed into films by hot-melt molding methods such as melt extrusion and calendaring.

According to the present invention, the fluororesin film thus obtained is laminated on the smooth surface layer on the light incident side of the retroreflective sheet via an adhesive layer, preferably a pressure-sensitive adhesive layer. When carrying out this kind of lamination, the adhesive can be coated on the bonding surface of the fluororesin film in advance, or can be coated on the surface layer of the retroreflective sheet, or can be coated with the adhesive on a suitable surface. The release material is then transferred to the adhesive side of the fluororesin film or the surface layer of the retroreflective sheet.

The thickness of the adhesive layer formed in this way can be changed according to the type of adhesive or the thickness of the resin film to be pasted, but generally it can be 5-80 μm, preferably 10-70 μm, more preferably 20-70 μm. within the range of 60 μm.

As the above-mentioned adhesive, it is generally preferred to contain an adhesive resin with a glass transition temperature (Tg) in the range of -100°C to +50°C, especially in the range of -80°C to -20°C as the main composition. adhesive.

As the adhesive resin, resins commonly used in pressure-sensitive adhesives can also be used, and the type is not particularly limited. For example, acrylic, polyurethane, ethylene-vinyl acetate copolymer, silicone, etc. can be used. Alkanes and other synthetic resins, but acrylic resins are better among them.

Examples of such acrylic resins include ethyl acrylate, n-propyl acrylate, n-butyl acrylate, isobutyl acrylate, n-pentyl acrylate, 2-methylbutyl acrylate, n-hexyl acrylate, 2-ethyl acrylate, At least one of C ₂ -C ₁₂ alkyl acrylates such as hexyl acrylate, n-octyl acrylate, isooctyl acrylate, n-nonyl acrylate, and isononyl acrylate (monomer A), and acrylic acid, methacrylic acid, propylene Amide, N-(hydroxymethyl)acrylamide, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate and other functional group-containing acrylic monomers (monomer B), so that Tg can fall into A resin obtained by copolymerization at a ratio within the above range. The copolymerization ratio of monomer A and monomer B is preferably in the range of monomer A/monomer B weight ratio of 99.5/0.5 to 70/30, especially 99/1 to 75/25.

As an acrylic resin that is particularly good even among adhesive resins, butyl acrylate (BA) and acrylic acid (AA) can be cited at a weight ratio of 99.1/0.9 to 70/30, especially 99.5/0.5 to 99.5/0.5. A copolymer obtained by copolymerization within the range of 80/20.

In addition, in the above-mentioned adhesive resin, for the purpose of improving the weather resistance of itself and the weather resistance of the retroreflective sheet used as the backing, it is desirable to also contain an ultraviolet absorber, and if necessary, a photooxidation agent may be added. Inhibitors.

As the ultraviolet absorber that can be used in the above-mentioned adhesive resin, it is generally preferred that the maximum absorption wavelength is within the range of 340-353nm, especially within the range of 343-346nm, for example, cyanoacrylates, benzene Triazoles, benzophenones, salicylic acids, hydroquinones and other UV absorbers. The reactive compounds of these absorbents can either react with the polymer formed or can be incorporated into the polymer by prior reaction with the monomers as previously described.

Specific examples of usable ultraviolet absorbers include 2-(3,5-di-tert-butyl-2-hydroxyphenyl)benzotriazole, 2-[2 -Hydroxy-3,5-di(α,α-dimethylbenzyl)phenyl]-2H-benzotriazole, 2-(3,5-di-tert-amyl-2-hydroxyphenyl)benzo Triazole etc.; As benzophenone ultraviolet absorber, can enumerate such as 2-hydroxyl-4-octyloxybenzophenone, 2,4-dihydroxybenzophenone, 2-hydroxyl-4-methoxyl-2 '-Hydroxybenzophenone etc.; As the salicylic acid ultraviolet absorber, such as phenyl salicylate, p-octylphenyl salicylate, resorcinol monobenzoate, salicylic acid 4- tert-butylphenyl ester, etc.; then, as cyanoacrylate ultraviolet absorbers, such as 2-cyano-3,3-diphenyl ethyl acrylate, 2-cyano-3,3-diphenyl 2-ethylhexyl acrylate, etc.

Among these, benzotriazole-based ultraviolet absorbers are particularly preferable.

The above-mentioned ultraviolet absorber is usually in the range of 0.5 to 10 parts by weight, preferably 0.6 to 9 parts by weight, and more preferably 0.7 to 8 parts by weight per 100 parts by weight of the adhesive resin (calculated as solid matter). use.

In addition, in the adhesive layer, it is desirable to contain a photooxidation inhibitor in addition to the above-mentioned ultraviolet absorber, and photooxidation inhibitors such as hindered amines and hindered phenols, etc. Inhibitors, preferably hindered amine photooxidation inhibitors.

The hindered amine-based photooxidation inhibitor is not particularly limited, but in general, those having a high molecular weight and an N-substituted piperidinol nucleus can be cited as preferable examples. The hindered amine photooxidation inhibitor usually preferably has a weight average molecular weight in the range of 400-10,000, especially in the range of 500-5,000. As a specific example of such hindered amine photooxidation inhibitors, high molecular weight esters such as esters of butane tetracarboxylic acid and N-substituted piperidinol can be enumerated, wherein a better example can enumerate commercially available MARK LA-63 ( Trade name, manufactured by Adeka Aigas Co., Ltd.), MARKLA-62 (trade name, manufactured by Adeka Aigas Co., Ltd.), TINUVIN-622LD (trade name, manufactured by Nippon Chiba Gaigi Co., Ltd.), etc. By using such a high-molecular-weight hindered amine-based photooxidation inhibitor, decomposition and cracking can be prevented, and as a result, performance can be maintained over a long period of time.

The compounding amount of the photooxidation inhibitor is not strictly limited, and can be changed according to its type, but generally speaking, for every 100 parts by weight of the adhesive resin (calculated as solid matter), this inhibitor can be 0.5 to 5 parts by weight. parts, preferably in the range of 0.6 to 4 parts by weight, more preferably in the range of 0.7 to 3 parts by weight.

In the adhesive composition for forming an adhesive layer mainly composed of the above-mentioned adhesive resin, in addition to the above-mentioned ultraviolet absorber and photooxidation inhibitor, general-purpose components such as ethyl acetate Solvents such as esters and ethyl acetoacetate, colorants such as various pigments and dyes, crosslinking agents, crosslinking accelerators, etc. Examples of crosslinking agents include isocyanates, epoxies, melamines, and aluminum chelates, and examples of crosslinking accelerators include dibutyltin laurate.

The above-mentioned adhesive composition may be applied to the bonding surface of the fluororesin film or the light-incident side surface of the retroreflective sheet, but practically, it is preferably applied to the fluororesin film in advance. Cover the adhesive layer with a release paper or the like on the pasting surface of the retro-reflective sheet, peel off the release paper or the like when necessary, and press-laminate it on the incident side surface of the retroreflective sheet.

The above-mentioned retroreflective sheet of the present invention protects its surface with a fluorine-based resin film with low surface tension and excellent weather resistance, solvent resistance, mechanical strength, etc., so it is rarely used even in cold regions. Ice or snow accumulates on the surface of the retro-reflective sheet, and even if the surface of the retro-reflective sheet is contaminated with paint, ink, etc., there is no need to use organic solvents, etc., and the contamination can be easily removed by wiping or washing with water, so , can be advantageously used for signs such as road signs and engineering signs, number plates of vehicles such as cars, motorbikes, etc., safety equipment such as clothes and life-saving appliances, sporting goods such as ski poles, and scoring equipment such as kanbans.

Example

Hereinafter, the present invention will be described more specifically using examples and comparative examples. The methods of the icing resistance test, snow resistance test, retroreflective performance test, softness test, and decontamination test of the retroreflective sheet in Examples and Comparative Examples and their evaluation methods are as follows.

(1) Icing resistance test

The retroreflective sheet was pasted on the entire surface of an aluminum plate of 7.5 x 15 cm to prepare a test piece. The test piece is vertically erected in the atmosphere of -30°C, spray water droplets on the entire surface of the retro-reflective sheet by spraying method, observe the freezing state of the surface after 24 hours, and evaluate according to the following criteria:

5 The frozen part accounts for less than 5% of the total area;

4 The frozen part accounts for more than 5% to less than 10% of the total area;

3 The frozen part accounts for more than 10% to less than 20% of the total area;

2 The frozen part accounts for more than 20% to less than 30% of the total area;

1 The frozen part accounts for more than 30% of the total area.

(2) Snow resistance test

The retroreflective thin plate was pasted on the entire surface of a 1×1.5 m aluminum plate to prepare a test piece. When it is snowing, stand the test piece vertically outside the house, observe the surface snow condition after 24 hours, and evaluate according to the following criteria:

5 The snow accumulation part accounts for less than 5% of the total area;

4 The snow accumulation part accounts for more than 5% to less than 10% of the total area;

3 The snow accumulation part accounts for more than 10% to less than 20% of the total area;

2 The snow accumulation part accounts for more than 20% to less than 30% of the total area;

1 The snow cover part accounts for more than 30% of the total area.

(3) Retro-reflective performance

Measured in accordance with the retroreflection performance measurement method specified in JIS Z-9117. In addition, the angle conditions at the time of measurement were observation angle 0.2 degree, and incident angle 5 degrees.

(4) Softness test

The retro-reflective sheet is cut into 10×10 cm, and at 5°C, stick it on a polyvinyl chloride resin pipe with a diameter of about 5 cm by means of a pressure-sensitive adhesive provided on the back of the retro-reflective sheet, and fix it for 10 seconds bell. Then remove the fixation, observe the pasting state, and evaluate according to the following criteria:

3 No sticking abnormalities such as floating and peeling;

2 Paste abnormalities such as floating and peeling are within 10mm from the end;

1 Paste irregularities such as floating and peeling exceed 10mm from the end.

(5) Decontamination test

The surface of the retro-reflective sheet was stained black with an oil-based felt pen, and after drying for 5 minutes, the decontamination was evaluated according to the following criteria:

5 It can be removed by simply wiping with a cloth, leaving no trace at all;

4 It can be removed when vigorously wiped with a cloth, leaving no trace at all;

3 It cannot be completely removed even if you wipe it vigorously with a cloth, but wipe it with water or ethanol on the cloth

can be removed without leaving any trace at all;

2 It can be removed but leaves traces when it is dipped in water or ethanol on a cloth and then wiped;

1 Dip water or ethanol on the cloth and then wipe it can not be removed.

Example 1

A tetrafluoroethylene/ethylene copolymer fluororesin film with a thickness of about 40 μm, a total light transmittance of 92%, and a surface tension of 23 dyne/cm ["Aflon COP", manufactured by Asahi Glass Co., Ltd.] was coated on a release paper. A mixed solution, a pressure-sensitive adhesive layer with a thickness of about 50 μm after drying is bonded to make a fluororesin film with a pressure-sensitive adhesive, and the mixed solution contains butyl acrylate (BA)/acrylic acid (AA) copolymer (weight ratio: BA/AA=90/10) 294 parts by weight of ethyl acetate/toluene (4/6) solution (solids=34%), benzotriazole ultraviolet absorber ["TINUVIN328", チバ· Gaigi 1 Co., Ltd.] 1.4 parts by weight, hindered amine photooxidation inhibitor ["TINUVIN622LD", Chiba Gaigi 1 Co., Ltd.] 0.7 parts by weight, and 1,6-hexamethylene diisocyanate crosslinking agent as a crosslinking agent 0.3 parts by weight of 1-methoxypropyl acetate-2/xylene (1/1) solution (solid content=75%).

Then, the release paper on the fluorine-based film with the pressure-sensitive adhesive was peeled off, and pasted and laminated on the light incident side surface of a commercially available capsule lens type retroreflective sheet ["Nitsuka Laitto ULS 512", manufactured by Nitsuka Polyma Co., Ltd.] , A retroreflective sheet having a surface layer coated with a fluororesin film was obtained.

The obtained retroreflective sheet was subjected to various tests according to the aforementioned test methods. The test results are listed in Table 1 below.

Example 2

Except for the tetrafluoroethylene-ethylene copolymer film in Example 1, a vinylidene fluoride-based resin film (PVdF) ["DX film 14S0050" with a thickness of about 50 μm, a total light transmittance of 92%, and a surface tension of 25 dynes/cm was used. , manufactured by Denki Kagaku Kogyo Co., Ltd.], except that the procedure was carried out in the same manner as in Example 1 to obtain a retroreflective sheet. The obtained retroreflective sheet was subjected to various tests according to the aforementioned test methods. The test results are listed in Table 1 below.

Comparative example 1

With regard to the commercially available capsule lens type retroreflective sheet used in Example 1, various tests were performed according to the aforementioned test methods. The test results are listed in Table 1 below.

Comparative example 2

In addition to the polyethylene terephthalate resin film (PET) of about 38 μm of thickness, total light transmittance 93%, surface tension 41 dyne/centimeter of tetrafluoroethylene-ethylene copolymer film in embodiment 1 [ "Lighting Latron S-38", manufactured by Teijin Co., Ltd.] was replaced by the same procedure as in Example 1 to obtain a retroreflective sheet. The obtained retroreflective sheet was subjected to various tests according to the aforementioned test methods. The test results are listed in Table 1 below.

Example 3

The procedure was carried out in the same manner as in Example 1, except that the capsule lens type retroreflective sheet used as the retroreflective sheet in Example 1 was replaced with a commercially available enclosed lens type retroreflective sheet ["Nitsuka Laitto SEG 15012", manufactured by Nitsuka Polyma Co., Ltd.]. , to obtain a retroreflective sheet. The obtained retroreflective sheet was subjected to various tests according to the aforementioned test methods. The test results are listed in Table 1 below.

Comparative example 3

With respect to the commercially available enclosed lens type retroreflective sheet used in Example 3, various tests were carried out according to the aforementioned test methods. The test results are listed in Table 1 below. Table 1

Claims (15)

1. the retroreflecting thin plate is characterized in that, at light incident side flat top layer is arranged; Via the fluorine-type resin film of the full light transmittance of adhesive phase lamination more than 80%, described fluorine-type resin film is tetrafluoroethylene/ethylene multipolymer or polyvinylidene fluoride on this superficial layer.

2. the described retroreflecting thin plate of claim 1, wherein the fluorine-type resin film has the full light transmittance more than 85%.

3. the described retroreflecting thin plate of claim 1, wherein to contain percentage by weight be 15～85% tetrafluoroethylene units to the tetrafluoroethylene/ethylene multipolymer.

4. the described retroreflecting thin plate of claim 1, wherein the fluorine-type resin film is by the melt-shaping manufactured.

5. the described retroreflecting thin plate of claim 1, wherein the thickness of fluorine-type resin film is 1～100 μ m.

6. the described retroreflecting thin plate of claim 5, wherein the thickness of fluorine-type resin film is 5～80 μ m.

7. the described retroreflecting thin plate of claim 1, wherein adhesive phase is made up of pressure-sensitive adhesive.

8. the described retroreflecting thin plate of claim 7, wherein pressure-sensitive adhesive mainly is made up of acrylic resin.

9. the described retroreflecting thin plate of claim 1, wherein adhesive phase contains ultraviolet light absorber.

10. the described retroreflecting thin plate of claim 9, wherein ultraviolet light absorber is the benzotriazole ultraviolet light absorber.

11. the described retroreflecting thin plate of claim 9, wherein adhesive phase further contains the photooxidation inhibitor.

12. the described retroreflecting thin plate of claim 11, wherein the photooxidation inhibitor is that weight-average molecular weight is the hindered amines photooxidation inhibitor of 400-10000.

13. the described retroreflecting thin plate of claim 1, wherein the thickness of adhesive phase is 5～80 μ m.

14. the described retroreflecting thin plate of claim 13, wherein the thickness of adhesive phase is 10～70 μ m.

15. the described retroreflecting thin plate of claim 1, wherein fluoroplastic film has the following surface tension of 40 dynes per centimeter.