JPH06347623A - Retroreflective sheet - Google Patents

Abstract

PURPOSE:To improve mechanical strength, resilience, impact resistance, holdability of retroreflective performance and weatherability by forming at least the part of a base film where glass beads are embedded and held and sonstituting connecting walls into an island-and-sea structure. CONSTITUTION:The base film 2 is composed of a bead supporting layer 7 and a reinforcing layer 8 formed out of a crosslinked resin. The bead supporting layer 7 is formed out of a resin mixture having the island-and-sea structure consisting of the crosslinked particles dispersed in the thermoplastic resin. The glass beads 5 coated with vapor deposited metallic films 4 on the nearly lower hemispherical surfaces are so embedded in a substantially single layer on the bead supporting layer 7 that at least nearly the upper hemispherical surfaces of the glass beads 5 are exposed. A transparent protective film 1 is connected onto the surfaces of the exposed glass beads 5 by the connecting walls 3 in the continuous line forms produced by thermal fusing and molding of the base frame 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention is useful for signs such as road signs and construction signs, license plates for vehicles such as automobiles and motorcycles, safety materials such as clothes and life preservers, and markings for signs and the like. Retroreflective sheet.

[0002]

2. Description of the Related Art Conventionally, a retroreflective sheet for retroreflecting light toward a light source is well known, and by utilizing its retroreflectivity, the sheet is widely used in the above application fields. There is. Among them, the retroreflecting sheet generally called a capsule lens type retroreflective sheet, which uses the low refractive index of air to improve the retroreflective performance of light, has been expanding its application year by year due to its excellent light retroreflecting performance. It's starting.

Generally, a capsule lens type retroreflective sheet is formed by partially thermally deforming a support film and a support film which face each other with a small air layer in between, and a support film to partially bond them. Is formed of a continuous linear connecting wall, and the sealed small compartment between the protective film and the support film, which is partitioned by the connecting wall, is substantially embedded in the support film. The lower hemisphere contains glass beads coated with a metal vapor deposition film.

For such a capsule lens type retroreflective sheet, high retroreflective performance is demanded as the most important function. In addition, the machine when it is used under severe conditions such as outdoor use. In addition to the dynamic strength, flexibility, impact resistance, etc., retention of the retroreflective performance, that is, good weatherability capable of maintaining the retroreflective performance for a long period of time is also required as an important function.

When the capsule lens type retroreflective sheet is used outdoors for a long period of time, the deterioration of the retroreflective performance is almost always caused by the destruction of the sealed small compartment empty space and the intrusion of rainwater or the like into it. . That is, peeling or destruction of the connection wall itself at the interface between the protective film and the connection wall due to expansion, contraction, etc. of the sealed small compartment vacancy accompanying changes in the outside air temperature, or an adherend to which the reflection sheet is attached The crack of the sheet due to repeated expansion and contraction due to the change of the outside air temperature, further, the vacant chamber is destroyed by deformation of the sealed small compartment vacant chamber due to the contraction of the protective film, etc., and rainwater and the like invade into it, Since the refractive index condition in the vacant chamber, which is an important factor of retroreflective performance, is changed, or the metal evaporated film that is a light reflective film is deteriorated and loses the light reflective performance, the retroreflective performance is deteriorated. is there.

Therefore, in the retroreflective sheeting, the support film which constitutes more than half of the wall surface of the sealed small compartment vacancy as the connecting wall and the glass bead support layer is used for maintaining the retroreflective performance. Plays an important role in obtaining the weather resistance of the support film. It is necessary to have various properties such as meltability, toughness or flexibility as a connecting wall, absorbability of strain to withstand repeated expansion and contraction, and strength to withstand shrinkage deformation.

Conventionally, various attempts have been made to improve the support film in order to improve these various characteristics. For example, in JP-A-52-110592, the support film is crosslinked by radiation to improve the strength. A method for achieving this has been proposed. However, since the support film in this proposal consists of a uniform resin layer showing thermoplasticity before hot melt molding, it becomes in a state in which it easily flows during hot melt molding, and the protective film and the support film part The width and thickness of the connecting wall portion are liable to change due to a slight change in the thickness and a slight change in the hot-melt molding conditions, and the shape of the connecting wall portion is stable and the adhesive strength between the protective film and the support film is stable. Is difficult to obtain.

In addition, in the radiation cross-linking reaction after the hot melt molding, the heat applied to the support sheet during the hot melt molding and the preservation of the support sheet immediately before the heat melting are caused by a slight change in the irradiation conditions. There is a problem that it is difficult to obtain the same cross-linking physical properties due to the difference in heat history in the state, and further the cross-linking reaction after hot melt molding causes distortion such as volume contraction in the connecting wall part, etc., and the protective film and the support film There is also a problem that the adhesive strength with is adversely affected.

Furthermore, the crosslinking component having an unsaturated bond, which is used in the radiation crosslinking reaction, is rarely completely reacted during the crosslinking reaction, and in many cases, the unreacted component is directly used as a product. Since it remains on the support film and the connecting wall portion of the retroreflective sheet, undesired crosslinking proceeds due to external factors such as heat and sunlight during the use of the retroreflective sheet, and the protective film and the connecting wall. It was also found that there are problems that the adhesive strength of the above-mentioned is reduced, the support film and the connecting wall portion are fragile, and the sealed small compartment vacancy is easily broken.

Other than the above, for example, JP-A-62-121043
The publication discloses a method of obtaining high toughness and flexibility by using a high molecular weight thermoplastic film as a support film. However, even in this method, the support film is a uniform system and the molecular weight is remarkably increased. It has been found that if the toughness and the like are improved by using the increased resin, the heat melting property and the flexibility tend to be impaired, and it is extremely difficult to solve the above problems only by this. Further, JP-A-59-71848 proposes a method of achieving a large tensile strength and excellent elongation by using a urethane resin or the like as a support film, but the urethane resin leaves a problem in weather resistance. ing.

The object of the present invention is to provide stable hot melt moldability,
That is, the heat-melting property at the time of hot-melt molding that provides a strong adhesive force with the protective film as the connecting wall, and without undergoing a step of causing distortion in the connecting wall portion due to a crosslinking reaction after the hot-melt molding, By using a support film that has excellent properties such as toughness and flexibility as a wall, absorbency of strain to withstand repeated expansion and contraction, and strength to withstand shrinkage deformation, these conventional films are used. The object is to provide an excellent retroreflective sheeting that overcomes the drawbacks of the technology.

[0012]

DISCLOSURE OF THE INVENTION The inventors of the present invention have conducted various studies on a support film of a retroreflective sheet, particularly a capsule lens type retroreflective sheet, and as a result, at least glass beads are embedded in the support film. A flexible thermoplastic resin, for example, particles of a resin having a higher degree of cross-linking than the thermoplastic resin (hereinafter sometimes referred to simply as cross-linked particles) and / or the thermoplastic resin in a portion which supports and constitutes the connecting wall. By using a resin layer formed by mixing so-called mixed resin having a sea-island structure in which resin particles having a higher polarity than the resin (hereinafter, simply referred to as polar particles) are dispersed and used, it is possible to obtain all of the above characteristics. It has been found that a retroreflective sheet can be obtained.

[0013]

Thus, according to the present invention, glass beads having a substantially lower hemispherical surface coated with a metal vapor deposition film on one surface are substantially single layers and at least approximately the upper hemispherical surface of the glass beads. A support film embedded so as to expose, a transparent protective film provided on the surface of the exposed glass beads, and the support film formed by partially heat-melting and deforming the support film to protect the support film. A retroreflective sheet comprising a connecting wall for connecting a film, preferably a continuous linear connecting wall for connecting the support film and the protective film so as to form a large number of sealed small compartments, Of the support film, at least a portion of the support film which embeds and supports the glass beads and which constitutes a connecting wall has a sea-island structure, preferably a retroreflective sheet, preferably a cap. Rurenzu retroreflective sheet is provided.

The present invention will be described in more detail below.

The support film in the retroreflective sheeting of the present invention has a sea-island structure at least in a portion which embeds and supports the glass beads and forms a connecting wall, preferably in a thermoplastic resin in which crosslinked particles and The sea-island structure is formed by dispersing at least one kind of resin particles (preferably cross-linked particles) selected from polar particles, and preferably the part forming the sea-island structure retains heat melting property. It is characterized by that.

In the present invention, the whole support film may have the above-mentioned sea-island structure, but it also has other properties such as solvent resistance and is particularly excellent in strength, impact resistance and flexibility. In order to achieve the above, in the support film, glass beads are embedded and supported, and the portion constituting the connecting wall is formed of a mixed resin of sea-island structure as a bead supporting layer, and the surface opposite to the surface supporting the glass beads is formed. It is preferable that the portion located on the side is formed of a crosslinked resin as a reinforcing layer, and at least these two layers are laminated to form a support film.

FIG. 1 shows a capsule lens type retroreflective sheet which is a preferred embodiment of the retroreflective sheet of the present invention. In FIG. 1, a support film (2)
Is a bead supporting layer (7) that embeds and supports glass beads and constitutes a connecting wall, and a reinforcing layer formed by a crosslinked resin located on the opposite side of the surface supporting the glass beads of the bead supporting layer ( 8) and the bead supporting layer is formed of a sea-island mixed resin in which crosslinked particles are dispersed in a thermoplastic resin.

In the bead supporting layer (7), the glass beads (5) whose lower hemisphere surface is covered with the metal vapor deposition film (4) are substantially a single layer and at least almost the upper hemisphere of the glass beads (5). It is buried so that the surface is exposed. Further, a transparent protective film (1) on the exposed glass bead surface is a continuous linear connecting wall (3) made by hot-melt molding the support film.
The glass bead layer embedded and supported in the bead support layer (7) of the protective film (1 and the connecting wall (3) and the support film (2) provides a large number of sealed small compartments (6). Has been formed.

If necessary, an adhesive layer (9) such as a pressure-sensitive adhesive is laminated on the back surface of the reinforcing layer (8), and a protective substrate (10) such as release paper is further provided on the back surface thereof. Are stacked.

The feature of the retroreflective sheeting of the present invention is that, in the support film, at least a portion which embeds and supports glass beads and constitutes a connecting wall [preferably bead support layer (7)] has a sea-island structure. What is done, preferably that a mixed resin having a sea-island structure is used in which at least one kind of resin particles selected from crosslinked particles and polar particles (particularly preferably crosslinked particles) is dispersed in a thermoplastic resin. is there.

The thermoplastic resin forming the sea part is not particularly limited, and is selected from, for example, an acrylic resin, a polyurethane resin, a polyester resin, a vinyl chloride resin, a vinyl acetate resin, a polyolefin resin, a polyamide resin, or the like. Examples thereof include plastic resins, and these can be used alone or as a blend of two or more kinds. Among them, the glass transition temperature is − because of its strength, impact resistance, weather resistance, flexibility and ease of processing or handling.
10 ° C or higher, weight average molecular weight of 20 × 10 ⁴ or higher, 1
Acrylic resin of less than 00 × 10 ⁴ is suitable.

As the crosslinked particles and the polar particles which are suitable components for forming islands, a crosslinked particulate resin having a size of 20 μm or less, preferably 10 μm or less, more preferably 5 μm or less is suitable. Used for. When the size of the crosslinked particles is 20 μm or less, poor dispersibility, and strength and flexibility are not impaired, which is preferable.

The resin that can be used for the crosslinked particles is not particularly limited, and examples thereof include crosslinked acrylic, alkyd, polyurethane, polyester, epoxy, vinyl chloride, vinyl acetate, Examples of the resin include polyolefin resins and polyamide resins. Among them, acrylic resins are particularly preferable because of their strength, impact resistance, weather resistance, and ease of processing or handling.

The crosslinked particles are used as a support film (2).
When forming the bead support layer (7), the crosslinked particles, insoluble in the resin composition consisting of the thermoplastic resin and the organic solvent, and the connection wall due to heat melting deformation of the support film (2) Any resin may be used as long as it has a degree of cross-linking that is at least sufficient to maintain infusibility during molding, but it is preferable to use composite particles that have a plurality of resin components each having a different glass transition temperature and / or degree of cross-linking. Good.

More specifically, the term "composite particles" as used in the present invention means that the same particles have two or more kinds of glass transition temperatures and / or
Alternatively, it is composed of acrylic (co) polymers having different degrees of cross-linking, and can be synthesized by utilizing a multistage polymerization method, a power feed polymerization method or the like. In this case, these (co) polymers may be mixed with each other, or may be in a state where a graft bond is appropriately introduced to the extent that the block bond or the rubber elasticity is not lost. The shape of the composite particles is not necessarily limited, but may be spherical particles in which at least two or more (co) polymers are mixed, for example, a core part and a plurality of outer layers covering the core part. "Core-shell type particle" that has both
"Gourd-type particles" such as spherical particles made of (co) polymer bonded to each other, or at least 1 in core-shell type particles
It may be a “compet-type particle” in which a plurality of hump-shaped particles composed of one or more (co) polymers are attached.

The resin that can be used for the polar particles is not particularly limited, and examples thereof include acrylic acid (co) polymers, acrylic ester-acrylic acid copolymers, ethylene-acrylic acid copolymers. Polymers, polycarboxylic acid resins such as maleic anhydride-vinyl ether copolymers; for example, cellulose resins such as cellulose acetate butyrate and nitrocellulose; polyhydroxyl resins such as starch and polyvinyl alcohol; Resin can be illustrated.

The resin composition of the bead supporting layer (7) is not particularly limited, but is usually a thermoplastic resin forming a sea part in order to obtain a property having a good balance of strength, impact resistance and flexibility. 50 parts by weight or less, preferably 10 to 30 parts by weight, of particles forming islands, for example, crosslinked particles and / or 100 parts by weight, is added to form 100 parts by weight.

The bead supporting layer (7) may further include an extender pigment or a coloring pigment (for example, titanium oxide, magnesium oxide, calcium carbonate, barium sulfate, cyanine blue, cyanine green, etc.); an ultraviolet absorber. (For example, benzotriazole-based absorbent, benzophenone-based absorbent, cyanoacrylate-based absorbent, etc.), light stabilizer (for example, hindered amine-based light stabilizer, hindered phenol-based light stabilizer, etc.), antioxidant (for example,
Phenolic antioxidant, phosphite antioxidant,
Stabilization aids such as thioether antioxidants) and other additives can be added in usual amounts.

The bead support layer (79 has a thickness not less than a thickness at which the lower hemisphere of the glass beads can be embedded) and may be appropriately determined depending on the type of resin, the size of the glass beads, etc. ~ 200 μm, preferably 30-150 μm,
More preferably, it is convenient to set it in the range of 50 to 100 μm.

In the preferred capsule lens type retroreflective sheeting of the present invention, the reinforcing layer (8) is formed of a crosslinked resin (hereinafter sometimes referred to simply as a crosslinked resin). The resin used for the reinforcing layer (8) is preferably a crosslinked resin so as to impart strength to the capsule lens type retroreflective sheet due to its toughness and to function as a processability auxiliary layer during hot melt molding.

The term "crosslinked resin" as used herein means a resin containing at least 50% by weight or more of the crosslinked resin in the total resin, and a resin having a gel content of 50% by weight or more. The preferred gel content of the reinforcing layer is 70% by weight or more, and the more preferred gel content is 80% by weight or more.

The gel content here is a measure of the degree of cross-linking, and a resin layer serving as a sample such as a reinforcing layer is immersed in tetrahydrofuran at 25 ° C. for 12 hours, stirred and filtered with a 400-mesh wire net, and then the wire net is placed on the wire net. The remaining resin was dried and weighed, and the weight ratio to the original resin layer weight was measured. When the resin layer contains a component other than the resin, this component is removed and corrected to obtain a gel component.

The resin forming the reinforcing layer (8) is not particularly limited as long as it is a crosslinked resin. For example, it is self-crosslinked by irradiation with actinic rays such as ultraviolet rays and electron beams, heating, catalysts and the like. An internal cross-linking type resin; an external cross-linking type resin cross-linked with a cross-linking agent such as a polyisocyanate compound, melamine or a derivative thereof, an epoxy compound or a derivative thereof, a chelate compound of a metal such as aluminum or titanium; They can be used alone or in combination of two or more. Further, a thermoplastic resin may be used together within the range that does not impair the above-mentioned conditions.

In the reinforcing layer (8), if necessary, a stabilizing aid such as an extender pigment, a coloring pigment, an ultraviolet absorber, a light stabilizer, an antioxidant, etc., and other additives are usually added, as in the above bead supporting layer. Can be blended in the amount of.

The thickness of the reinforcing layer (8) is not strictly limited and can be varied over a wide range depending on the material of the reinforcing layer, the end product application, etc.
~ 100 μm, preferably 10-70 μm, more preferably 20
It is suitable to be in the range of up to 50 μm.

In the present invention, the support film (2) is preferably composed of at least two layers, a bead support layer (7) and a reinforcing layer (8). Further, each layer does not necessarily have to be a layer having a single composition, for example, two or more layers having different compositions, as long as the characteristics of each layer are not impaired,
Alternatively, for example, it may be formed as two or more layers having different degrees of cross-linking, or may be formed using, for example, a layer whose degree of cross-linking continuously changes.

The protective film, glass beads, metal vapor deposition film and the like used in the retroreflective sheet of the present invention are not particularly limited, and known ones described in the above-mentioned patent publications may be used.

The method for producing the retroreflective sheet of the present invention is also not particularly limited, and a known production method similar to the above may be used.

For the production of the support film (2), for example, a solution obtained by adding a cross-linking agent such as a polyisocyanate compound to an organic solvent solution such as an acrylic resin is applied as a film and dried and cured to reinforce it. A layer (8), and then, on the reinforcing layer (8), a resin composition comprising a thermoplastic resin, crosslinked particles and an organic solvent as described above is applied and dried to form a bead support layer (7). Alternatively, the bead supporting layer (7) and the reinforcing layer (8), which are separately formed in advance, may be formed by bonding and adhering.

[0040]

EXAMPLES The present invention will be described in more detail with reference to Examples and Comparative Examples. The manufacturing method and the measuring method of the retroreflective sheet shown in Examples and Comparative Examples are as follows.

Production of capsule lens type retroreflective sheeting
Method A capsule lens type retroreflective sheet was prepared through the following steps.

Step 1: A step in which polyethylene resin is laminated on paper The paper is heated to about 105 ° C., glass beads having an average particle size of about 65 μm and a refractive index of about 1.91 are uniformly and densely dispersed on the paper, and the nip roll is used. After pressure was applied to embed the glass beads in the polyethylene resin layer to about 33% of the diameter, the glass beads were subjected to aluminum vapor deposition with a thickness of about 0.1 μm.

Step 2: A reinforcing resin layer having a thickness of about 40 μm is formed on the polyethylene terephthalate film which has been subjected to the release treatment.
And then dried to obtain a bead-supporting resin layer having a thickness of about 80 μm and dried to obtain a two-layer laminate.

Step 3: Glass bead embedding step Laminated on the aluminum vapor deposition side of the paper so that the bead supporting resin layer side of the laminate faces, and pressurized to embed about 33% of the glass beads in the bead supporting resin layer. I chose

Step 4: After maturing for 14 days at 35 ° C., the polyethylene resin laminating step paper was removed from this laminate, and the unstretched glass beads on the exposed glass beads had a thickness of about 75 μm and a total light transmittance of about 93%. Place the acrylic film on top of each other, and between the metal roll with a surface temperature of about 190 ℃ and the rubber roll with a surface temperature of about 60 ℃, which has a line width of 0.3 mm and is convexly engraved on the mesh, so that the acrylic film side is in contact with the rubber roll. It was made to pass under pressure and hot-melt molding was performed.

Step 5: The release-treated polyethylene terephthalate film was removed from the hot-melt molded product, and an acrylic pressure-sensitive adhesive having a thickness of about 40 μm was laminated on the reinforcing resin layer.

Measurement item and measurement method

1) Meltability test Measurement atmosphere: 23 ° C. × 65% RH Test piece: 50 mm × 50 mm (capsule lens type retroreflective sheet cut out to remove adhesive layer in advance) Measurement method: Upper mold temperature approx. 190 ℃, lower rubber plate temperature approx. 6
Using a heat-sealing machine at 0 ° C. and a set pressure of 1.5 kg / cm ² , a heat-sealing test was performed with a pressing time of 1.5 seconds, and the degree of contact was evaluated visually and by a simple peeling test with a cutter knife.

Evaluation criteria: 1: No adhesion by visual inspection and peeling 2: Adhesion by visual inspection, but easy peeling by a peeling test 3: Adhesion by visual inspection and peeling

2) Strong elongation at 25 ° C. Measuring atmosphere: 23 ° C. × 65% RH Equipment used: “Tensilon” [trade name; Orientech
Co., Ltd.] Specimen: 25mm width x 150mm (cut out from capsule lens type retroreflective sheet) Test condition: Grasping interval 100mm, pulling speed 200mm / min

3) Strong elongation at 70 ° C Measurement atmosphere: 70 ± 2 ° C Equipment used: "Tensilon" with high temperature chamber [trade name; manufactured by Orientec Co., Ltd.] Specimen: 25mm width x 100mm (capsule lens type recursive property) (Cut out from the reflection sheet) Test condition: Grip interval 50mm, Pulling speed 200mm / min

4) Impact resistance Measurement atmosphere: 23 ° C. × 65% RH Equipment used: DuPont type impact tester (manufactured by DuPont) Measurement conditions: A pin with a diameter of 1 inch is set and a load of 300 g
Was dropped from a height of 50 mm and the surface of the retroreflective sheet was visually observed.

Evaluation Criteria: 1: Completely removed state 2: Cracks occurred 3: Cracks not occurred

5) Weather resistance Equipment used: Xenon lamp type sunshine weather o-meter (manufactured by Atlas Co., Ltd.) Measuring conditions: 63 ° C. × 2,000 hours Evaluation standard: Test pieces after weathering deterioration were visually observed. 1: Remarkably poor appearance 2: Hair cracks occurred 3: No change in appearance

Example 1 A retroreflective sheet having a sea-island structure as a bead support layer was produced according to the method for producing a capsule lens type retroreflective sheet. The materials used for manufacturing are as follows.

Protective film: "Acryprene HBS" 80μ
[Product name: Mitsubishi Rayon Co., Ltd.]

Reinforcing layer: "Nissetsu SX-5305" [trade name;
Acrylic resin (solid content 50% by weight), manufactured by Nippon Carbide Industry Co., Ltd.] 100 parts by weight, and cross-linking agent "Nissetsu CK-10"
2 "[brand name, HMDI-based cross-linking agent (solid content 75% by weight), manufactured by Nippon Carbide Industry Co., Ltd.] 14 parts by weight are used.

Bead support layer: "Nisetsu KP-1684A" as a thermoplastic resin [trade name, acrylic resin (solid content 30
%), Manufactured by Nippon Carbide Industry Co., Ltd.] 133 parts by weight and "Nissetsu KP-1703A" [trade name, acrylic resin (solid content 40% by weight), manufactured by Nippon Carbide Industry Co., Ltd.] 100 parts by weight, crosslinked 80 parts by weight of "Nissetsu SX-5150" (trade name, acrylic resin composite particles (solid content 20% by weight), manufactured by Nippon Carbide Industry Co., Ltd.) is used as particles, and 4 parts by weight of cellulose acetate butyrate is used as polar particles. And 40 parts by weight of rutile type titanium oxide is used as other additive.

Adhesive layer: "Nissetsu KP-1384" [trade name, acrylic adhesive (solid content 40% by weight), manufactured by Nippon Carbide Industry Co., Ltd.] 100 parts by weight, and crosslinking agent "Nissetsu"
CK-103A "[trade name, HMDI-based cross-linking agent (solid content 10% by weight), manufactured by Nippon Carbide Industry Co., Ltd.] 1.2 parts by weight.

As shown in Table 1, the obtained retroreflective sheet was excellent in strength, impact resistance and flexibility and was able to sufficiently attain the object of the present invention.

Comparative Example 1 A capsule lens type retroreflective sheet was prepared in the same manner as in Example 1 except that the protective film and the bead support layer were changed to the following composition and each layer was a crosslinked resin layer. Formed.

Protective film: "Nissetsu KP-964" [trade name, acrylic resin (solid content 40% by weight), manufactured by Nippon Carbide Industry Co., Ltd.] 100 parts by weight, and crosslinking agent "CK-102"
Uses 3 parts by weight.

Bead support layer: "Nissetsu KP-1684A" 133
Parts by weight, "Nissetsu KP-1703A" 100 parts by weight, crosslinking agent "Nissetsu CK-102" 2 parts by weight, and 40 parts by weight of rutile titanium oxide as an additive. The obtained retroreflective sheet was inferior in flexibility.

Comparative Example 2 Capsule lens type retroreflective coating was carried out in the same manner as in Example 1 except that the protective film and the bead supporting layer were changed to the following composition and the respective layers were changed to thermoplastic resin layers. A sheet was formed.

Protective film: "Nissetsu KP-964" 100 parts by weight Bead support layer: "Nissetsu KP-1684A" 133 parts by weight, "Nissetsu KP-1703A" 100 parts by weight, and rutile-type titanium oxide as an additive 40 Uses parts by weight. The obtained retroreflective sheet was inferior in strength and impact resistance.

[0066]

[Table 1]

According to the present invention, in the support film of the capsule lens type retroreflective sheet, at least the portion (bead support layer) which embeds and supports the glass beads and constitutes the connecting wall has the sea-island structure. Thereby, the retroreflective sheet can be provided with further excellent strength, impact resistance, and flexibility.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of a preferred capsule lens type retroreflective sheeting of the present invention.

[Explanation of symbols] 1 ... Protective film 2 ... Support film 3 ... Continuous linear connecting wall 4 ... Metal evaporated film 5 ... ··· Glass beads 6 ··· Sealed small compartments 7 ··· Bead support layer 8 ··· Reinforcing layer 9 ··· Adhesive layer 10 ··· .... Protecting base

Claims (4)

[Claims] 1. A support film in which glass beads having a substantially lower hemisphere coated with a metal vapor deposition film on one surface are embedded in a substantially single layer so that at least substantially the upper hemisphere of the glass beads is exposed. , A recursive property consisting of a transparent protective film provided on the surface of the exposed glass beads, and a connecting wall connecting the supporting film and the protective film formed by partially heat-deforming the supporting film. A retroreflective sheet, which is a reflective sheet, characterized in that, of the support film, at least a portion of the support film in which the glass beads are embedded and supported and which constitutes a connecting wall has a sea-island structure. 2. The retroreflective sheet according to claim 1, wherein the connecting wall is formed in a continuous line shape and divides the support film and the protective film into a large number of sealed small compartments. 3. A thermoplastic resin having the sea-island structure, wherein at least one resin particle selected from particles of a resin having a higher degree of crosslinking than the thermoplastic resin and particles of a resin having a higher polarity than the thermoplastic resin. The retroreflective sheet according to claim 1 or 2, wherein the retroreflective sheet is dispersed. 4. The retroreflective sheet according to claim 1, wherein the portion forming the sea-island structure retains heat melting property.