JP2847476B2 - Cellular retroreflective sheet - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a retroreflective sheet having an adjacent small void space which is sealed in a cell shape on the surface thereof.

[0002]

2. Description of the Related Art Reflective sheets for retroreflecting light in the direction of incidence on a sheet surface are widely used for road signs, automobile license plates, and the like. Reflective sheets are desired to have good retroreflective performance, and one of them is angular characteristics. That is, as the angle of incidence of light on the sheet surface increases, the amount of retroreflected light with respect to the incident light tends to decrease. However, a small attenuation factor, in other words, good angular characteristics is required. Because

[0003] As a reflection sheet having such excellent angle characteristics, a reflection sheet has conventionally been disclosed, for example, in Japanese Patent Application Laid-Open No. Sho 40-7870 (US Pat.
No. 90178) and Japanese Patent Publication No. 61-13561 (U.S. Pat. No. 4,025,159), a reflection sheet called a capsule type is used.

[0004] The structure of the capsule type reflection sheet is such that a metal deposition film is provided directly on the lower hemisphere of a glass bead which is arranged from a transparent protective film with each of the independent sealed small compartments separated therefrom. A binder layer in which the lower hemisphere portion of the glass beads is embedded on the upper surface and a protective film on the upper portion of the glass beads are vertically connected by a connecting wall that is continuous in a plane mesh shape, and the surface of the reflection sheet is an independent sealed small space having a small area. It is divided into rooms.

However, in such a conventional capsule-type reflective sheet, the strength of the connecting wall portion connecting the binder layer and the protective film is not always sufficient, and when a peeling force is applied to the reflective sheet, the sheet becomes the binder layer. However, there is a disadvantage that the cohesive failure occurs at the connecting wall portion and the fracture occurs rather than peeling off at the interface between the protective film and the protective film.

Therefore, the applicant of the present application has previously filed Japanese Patent Application No. 59-48.
No. 201 (Japanese Unexamined Patent Publication No. 60-194405, U.S. Pat. No. 4,653,854) discloses a reflection sheet (hereinafter referred to as "improved capsule reflection sheet") for the purpose of eliminating the drawbacks of the conventional capsule reflection sheet. ) Proposed. This reflective sheet embeds and supports an almost lower hemispherical surface covered with a metal vapor-deposited film of glass beads lined up on a support film made of synthetic resin, and a transparent synthetic resin provided on the exposed glass bead surface side In a retroreflective sheet comprising a number of sealed small compartment vacancies separated by a continuous linear connecting wall formed by partial heating molding of the support film between the protective film and the support film consisting of, The support film includes at least an upper layer side in contact with the glass beads and a lower layer side opposite to the lower layer side, the lower layer side has a composition having a larger cohesive force and rubbery elasticity than the upper layer side, and the protective film is a stretched film. It is a feature.

In the improved capsule type reflective sheet, the support film has a two-layer structure composed of an upper layer and a lower layer having different compositions and physical properties from each other, and the lower layer has a composition having larger cohesive force and rubbery elasticity than the upper layer. By using unstretched protective film, the protective film is superior in that it can increase the resistance to cohesive failure of the continuous wall portion caused by artificial force or deterioration due to aging, and can prevent shrinkage deformation due to heating. It has the effect of
The manufacturing process has the following problems.

That is, the reason why the support film has a two-layer structure of an upper layer and a lower layer in the improved capsule-type reflection sheet is that in the conventional capsule-type reflection sheet in which the support film has a single layer, the adhesiveness with the protective film is reduced. If the melt viscosity of the support film is sufficiently reduced during the melt molding of the support film in order to improve the shape, when forming the connecting wall by embossing, CC-C 'in FIG. 2 of Japanese Patent Application No. 59-48201 is attached. While the legs of the connecting wall indicated by the lines are too stretched and become thinner, which tends to cause cohesive failure in this portion during use as a product, the melt viscosity of the supporting film is set to prevent such excessively extending legs of the connecting wall. Higher, there is a contradiction that the adhesiveness with the protective film is deteriorated and a sufficient adhesive strength cannot be obtained, so in order to overcome this contradiction,
At the time of melt molding, the upper layer has a composition with a low melt viscosity so as to ensure sufficient adhesiveness, and the lower layer has a composition with a relatively high melt viscosity so that the connecting wall legs do not grow too thin. is there.

In a preferred embodiment of the improved capsule type reflection sheet, in order to achieve the above object, both the upper layer and the lower layer are formed of a room temperature curable resin crosslinked by polyisocyanate, and the upper layer and the lower layer are cured. I try to vary the speed. That is, the progress of curing in the upper layer is made slower than in the lower layer by selecting the composition of each layer such that the number of active groups that react with isocyanate is reduced in the upper layer and increased in the lower layer. When the curing step of such a curable resin is divided into three stages of “uncrosslinked”, “semicrosslinked”, and “crosslinked”, the upper layer is in an uncrosslinked state, and the lower layer is in a semicrosslinked state. Melt molding and bonding with a protective film. Therefore, in order to achieve the object of the improved capsule-type reflective sheet, the support film must be embossed at a timing when the upper layer is in an uncrosslinked state and the lower layer is already in a semi-crosslinked state. The period in which the two states coexist is only an extremely short period of time from the start of curing to completion of each layer, so it is necessary to pay close attention to the control of the progress of curing and the settings during embossing, Producing a product that achieves the purpose without failure requires a high degree of skill in process control.

In order to prevent the legs of the connecting wall from being excessively elongated and becoming thin during the melt molding of the supporting film,
At the time of melt molding, it is most preferable that the lower layer be in a semi-crosslinked state in the latter half of the above semi-crosslinked state, that is, close to the crosslinked state. If embossing is performed in this state, the lower layer has the necessary deformability for forming the connecting wall but does not elongate too much, and furthermore, the inside of the connecting wall is broken due to internal stress caused by the restoring force after molding. Because there is nothing. However, in the improved capsule-type reflection sheet, when the lower layer enters the latter half of the semi-crosslinked state, the uncrosslinked state of the upper layer has already been completed, and there is often no period in which the two states coexist. Therefore, embossing cannot be performed in the latter half of the semi-crosslinked state, which is the optimum embossing timing for the lower layer.

[0011]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the problems of the above-mentioned improved capsule-type reflective sheet. Provided is a capsule-type reflective sheet that has a sufficient resistance to breakage, has a simpler manufacturing method, does not require a high level of skill in process control, and can form a connecting wall under optimal embossing conditions. What you're trying to do.

To achieve the above object, the present inventors have conducted intensive studies and experiments, and as a result, have found that a binder layer in which the lower hemisphere of glass beads is embedded (corresponding to the upper layer of the support film of the improved capsule-type reflective sheet). The glass transition point
A support layer formed of a thermoplastic resin containing a resin having a large adhesive strength to a protective film at 35 ° C. or lower and a multi-layer polymer acrylic resin, and a support layer in contact with the binder layer (the lower layer of the support film of the improved capsule-type reflective sheet) Is formed of a curable resin, thereby solving the above-mentioned problems at a glance, and providing a capsule-type reflective sheet that is not inferior to the conventional capsule-type reflective sheets in various performances as a product. We succeeded in realizing it.

In addition, the inventor succeeded in further improving the heat resistance of the binder layer by adding a fibrous resin to the thermoplastic resin forming the binder layer.

[0014]

That is, the retroreflective sheet for achieving the object of the present invention has a support film made of a synthetic resin having a substantially lower hemispherical surface covered with a metal vapor-deposited film of glass beads arranged in a line. A buried binder layer,
A support layer provided on the opposite side of the glass beads in contact with the binder layer, and a support film formed of a transparent synthetic resin provided on the exposed glass bead surface side and a support layer provided between the binder layer and the protective film. In a cellular retroreflective sheet comprising a number of sealed small compartment cavities separated by continuous linear connecting walls formed by partial heat molding of a film, the binder layer has a glass transition point of 35 ° C.
In the following, a thermoplastic resin containing a resin having a large adhesive strength with a protective film and a multilayer polymer acrylic resin is formed as a main component, the support layer is formed mainly of a curable resin, and the support layer is It is characterized by being formed with a curable resin as a main component.

[0015] Further, the cellular retroreflective sheet for achieving the object of the present invention is characterized in that the thermoplastic resin further contains a fibrous resin.

When compared with the above-mentioned improved capsule type reflection sheet, the reflection sheet of the present invention is common to the former in that it has a two-layer structure of a binder layer and a support layer. The latter is different from the latter in that a thermoplastic resin is used for the binder layer and a curable resin is used for the support layer.

In the present invention, a two-layer structure of a unique combination of a binder layer made of a thermoplastic resin and a support layer made of a curable resin has a sufficient resistance to cohesive failure of the connecting wall portion derived from the two-layer structure. While maintaining such an effect, it is possible to eliminate the necessity that the crosslinked state between the upper layer and the lower layer, which was a problem of the improved capsule-type reflective sheet, has to be embossed within a short period of time satisfying a predetermined condition. .

That is, by using a non-crosslinked thermoplastic resin as the binder layer, it is not necessary to consider the crosslinked state of the binder layer, and the timing of embossing can be determined by merely looking at the crosslinked state of the support layer. become. In other words, embossing may be performed anytime while the curable resin forming the support layer is in a semi-crosslinked state. Further, as a result, as described above, the embossing timing of the support layer
It is possible to freely select the latter half of the semi-crosslinked state which is the optimal timing.

However, by simply selecting a thermoplastic resin as the binder layer, it is not possible to realize a reflective sheet having various practically usable properties even if the above-mentioned problems relating to the timing of embossing can be solved. .

In order to prevent the binder layer from being broken or cracked even when the reflective sheet is used in extremely hot or cold regions, when the binder layer is formed of a thermoplastic resin, the thermoplastic resin has heat resistance, that is, sufficient heat resistance. It is necessary to have a high glass transition point (hereinafter sometimes abbreviated as Tg), and also have sufficient cold resistance, that is, sufficient strength not to cause cracking even at the lowest temperature at which the reflective sheet is used. However, in conventional thermoplastic resins, those having a high Tg tend to be brittle and crack at low temperatures, while those having sufficient strength at low temperatures tend to have a low Tg and tend to soften in extremely hot places and cause cohesive failure of the connecting wall. A thermoplastic resin having contradictory properties and satisfying both conditions simultaneously cannot be found in a conventionally known thermoplastic resin.

As a result of the research, the present inventors have found that a thermoplastic resin composed mainly of a resin such as an acrylic resin having a high Tg of 35 ° C. or less and an adhesive force to a protective film and a multi-layer polymer acrylic resin as main components. By doing so, it has been found that a new thermoplastic resin having both a sufficiently high Tg and a sufficient strength at a low temperature, which was not obtained in the conventional thermoplastic resin, can be obtained, and by using this novel thermoplastic resin, It succeeded in achieving a binder layer having sufficient heat resistance even in extremely hot regions and sufficient cold resistance even in extremely cold regions. That is, one important feature of the present invention resides in that a thermoplastic resin having a novel composition excellent in both heat resistance and cold resistance is employed as the binder layer in the two-layer structure.

In the present invention, a resin having a relatively low melting temperature of Tg of 35 ° C. or less and having a large adhesive strength to a protective film and a multilayer structure having relatively low temperature-dependent physical properties. Blend with the unified acrylic resin as the main component of the thermoplastic resin. By blending the above two types of substances having completely different physical properties, sufficient melting property and protective film can be obtained for molding. Thus, a thermoplastic resin having adhesiveness to heat and sufficient heat resistance and cold resistance for the purpose of use as a reflection sheet can be obtained.

Acrylic resin or polyester resin is preferable as a resin having a Tg of 35 ° C. or less and a high adhesive strength to a protective film. For example, acrylic resins such as methyl methacrylate, ethyl acrylate and 2-hydroxyethyl methacrylate are preferable. Copolymers and the like can be used.

These resins must have a Tg of 35 ° C. or less. If the Tg exceeds 35 ° C., the thermoplastic resin requires a high temperature in order to obtain sufficient meltability in molding processing, which is not preferable, and the cold resistance is extremely reduced.

Examples of the multilayer polymer acrylic resin used for the thermoplastic resin forming the binder layer include, for example,
The multilayer structure polymer acrylic resin described in JP-B-59-36645 (corresponding to U.S. Pat. No. 4052525) is preferred.

In the case where a resin having a relatively low compatibility with an acrylic resin or a polyester resin having a Tg of 35 ° C. or less, which is a main component forming the binder layer, is used among these multi-layer polymer acrylic resins. In order to enhance the compatibility between the two, a macromonomer, which is a high-molecular-weight monomer having a polymerizable functional group at the terminal, may be introduced into an acrylic resin or a polyester resin and used as a copolymer.

It has been found that when a suitable amount of a fibrous resin is further added to the thermoplastic resin having the above structure, the heat resistance of the thermoplastic resin can be further improved, but the cold resistance does not deteriorate. However, the addition amount of the fibrous resin is suitably not more than 20% of the thermoplastic resin, and if it exceeds this, the meltability of the resin deteriorates, which is not preferable. As such a fibrous resin, CAB (cellulose acetate butyrate) or CAP (cellulose acetate propionate) is preferable, and nitrocellulose, acetylcellulose and the like can also be used.

FIG. 1 shows the structure of an example of a completed reflection sheet of the present invention before a release paper is attached for shipping. That is, the protective film 1 and the support film 3 are partially connected by the connection wall 8 formed by melt-molding the support film 3, and the inside surrounded by the connection wall 8 is a sealed independent small compartment empty. A chamber 7 is formed, and an upper hemisphere of the glass beads 2 buried in the binder layer 5 is exposed on the inner surface of the chamber 7, and a lower hemisphere of the beads 2 is covered with a metal deposition film. Surface.

The binder layer 5 must have good adhesion to the protective film 1. This adhesive force is not unilaterally determined only by the composition of the main component of the binder layer 5 but is determined by the correspondence with the composition of the protective film 1. One of the best combinations is a combination of a protective film containing an acrylic copolymer as a main component and a binder layer whose main component is an acrylic thermoplastic resin containing a multilayer polymer acrylic resin. However, the present invention is not limited to the above-mentioned combination, but may be any combination of a protective film made of an appropriate polymer and a binder layer made of a thermoplastic resin described in the claims.

The support layer 6 is formed of a curable resin. As the curable resin, in addition to a thermosetting resin, a room temperature curable resin, for example, a solid that is thermoplastic at room temperature and becomes a fluid state in which the connection wall can be formed by heating, but is crosslinked and cured at room temperature after molding. Materials can be used. In particular, in the present invention, a thermoplastic copolymer having an active group such as an OH group capable of crosslinking by combining with a polyisocyanate that undergoes a crosslinking reaction at room temperature is contained as a main component of the support layer 6. It is preferred to do so.

If it is possible to omit any means such as a long-time heating means for curing and an electron beam irradiating means by using a cold-setting type hot melt adhesive material, it is extremely advantageous in producing the reflection sheet of the present invention. is there.

The support layer 6 is desirably made of a composition having higher cohesive force and rubbery elasticity than the binder layer 5. In the present invention, the binder layer 5 and the support layer 6 are combined with the binder layer 5 in order to make the internal strength of the thin connecting wall connecting the protective film 1 and the support film 3 composed of the binder layer 5 and the protective layer 1 sufficient and to prevent the internal layer from being broken by cohesive failure. The support layer 6 has a combination structure of two layers having different physical properties.

The composition of the binder layer 5 is as follows.
It must have good adhesiveness with the support layer 6 and good affinity with the support layer 6 so that both can be integrated. Further, the binder layer 5 needs to sufficiently wet the protective film 1 and the glass beads at the time of melt molding in order to improve the adhesion to the protective film 1 and maintain the strength of FIG. 1B-B ′.

On the other hand, the support layer 6 is excessively extended,
It must have a moderate melt viscosity that is not too low so that the part becomes thin and does not break from this part. By including a polyisocyanate that cures at room temperature as the support layer 6, such an appropriate melt viscosity can be obtained. In addition, resistance to cohesive failure and rubber-like elasticity can be increased to reduce external force. The stress becomes large and the elasticity can be easily restored quickly. The rubber-like elasticity serves to suppress the expansion and contraction of the binder layer 5 to a minimum, thereby preventing the connection wall from being broken. Obtainable.

The protective film 1 is mainly composed of a film containing an unstretched acrylic copolymer as a main component, for example, an acrylic copolymer mixed with, for example, synthetic rubber, cellulose acetate butyrate, styrene copolymer and the like. A film as a component can be used. Further, a film containing a polycarbonate film, a vinyl chloride film or the like as a main component can also be used.

As a method for forming the binder layer 5 and the support layer 6 as described above, first, the binder layer 5
The support layer 6 may be laminated after the material film to be formed is pressed against the surface of the lower hemisphere of the metal-deposited glass beads 2 to completely bury the lower hemisphere of the beads 2.
In addition, it is allowed that the binder layer 5 and the support layer 6 are laminated in advance and pressed against the glass beads 2.

In any of the above cases, the binder layer 5 needs to have a thickness sufficient to completely bury the substantially lower hemisphere of the glass beads 2. In both cases, it is convenient to use both layers 5 and 6 which are formed by applying them onto a base polymer film that does not strongly adhere to them with or without a release agent layer as appropriate.

In a reflection sheet in which the surface of the binder layer 5 exposed in the gap between the lower hemisphere surface of the glass beads and the beads is covered with a metal vapor-deposited film without any gap, the supporting film 3 and the protective film are formed by melting the binder layer 5. In the case where a thin connecting wall is provided to connect between the first connecting member 1 and the first connecting member, a considerable number of glass beads on which metal is deposited and a metal film released from the surface of the binder layer 5 are mixed in the thin connecting wall. . When such foreign matter is present in the connection wall, the temperature change applied to the reflection sheet and the internal distortion due to moisture absorption easily cause the inside of the thin linear wall to weaken. Therefore, it is desirable that no metal film remains on the surface of the binder layer 5 between the adjacent glass bead gaps.

In order to prevent the metal deposition film from being left on the surface of the binder layer 5 between the glass bead gaps, the beads are first supported on a temporary support by a known method, and after the metal deposition step, the temporary support is removed. A thin layer of a polymer having a relatively good adhesion to the deposited film and a relatively low adhesion to the supporting film, and then depositing the binder layer 5, and then a temporary support and the polymer deposited thereon A method such as peeling off the layers integrally can be used. In short, a method may be used in which the temporary support and the metal deposit thereon are not in direct contact with the binder layer 5.

[0040]

【Example】

Example 1 Glass beads having a refractive index of 1.92 and a diameter of 50 to 60 μ are buried in the polyethylene of a carrier paper on which a film of polyethylene having a thickness of approximately 30 μ is laminated. afterwards,
The upper hemisphere of glass beads is vacuum deposited with aluminum.

A predetermined binder layer forming composition is applied on a silicone-treated release paper, and most of the solvent is dried in an oven to form a binder layer of about 80 μm. Laminated on the glass beads.

Next, a composition for forming a support layer is applied on a film of polyethylene terephthalate of 20 μm, and the solvent is dried in an oven to form a support layer of about 40 μm, which is laminated on the binder layer.

The carrier paper was peeled from the laminate after an appropriate curing period, and the support film comprising a binder layer and a support layer was applied to the protective film at a temperature of 170 ° C. by a known method. From the side to form a connecting wall. As the protective film, a film having a thickness of about 80 μ and containing an unstretched acrylic copolymer as a main component is used.

Further, after the polyethylene terephthalate film is peeled off, an adhesive is applied to the support layer by a usual method, and the support layer is protected with a peeling film to obtain a desired reflection sheet.

As a composition for forming a binder layer in the examples, as described below, 40 parts of titanium oxide was dispersed in 100 parts of an acrylic composition having a solid content of 40%, and further, a solid content of 20%
Was added and mixed with 50 parts of a methyl ethyl ketone solution of the acrylic polymer having a multilayer structure.

Composition of Binder Layer Forming Composition Acrylic monomers of 40% methyl methacrylate, 55% ethyl acrylate, and 5% 2-hydroxyethyl methacrylate were polymerized in a mixed solvent of toluene and methyl isobutyl ketone. 100 parts of an acrylic composition adjusted to be a% solids solution 100 parts of a 20% solids solution of methyl ethyl ketone in a multilayer polymer acrylic resin 50 parts of titanium oxide

Composition of Support Layer Forming Composition Acrylic monomer of 21% of methyl methacrylate, 65% of ethyl acrylate and 14% of 2-hydroxyethyl methacrylate was polymerized in a mixed solvent of toluene and methyl isobutyl ketone, and 40% Acrylic composition adjusted to be a solid solution 100 parts Hexamethylene diisocyanate cross-linking agent 14 parts (Sumijur N-75 manufactured by Sumitomo Bayer)

The binder layer prepared by using the above-mentioned composition for forming a binder layer can still be embossed even after being left at room temperature for 2 weeks after the application of the binder agent. It was enough.

On the other hand, the laminate made with the binder layer forming composition of Example 1 of Japanese Patent Application No. 59-48201 is
After applying the composition for forming a binder layer, when left at room temperature after 2 days, the fluidity during embossing of the binder layer became poor, and the adhesiveness of the binder layer to the protective film was reduced. Then, poor adhesion to the protective film occurred.

Example 2 A reflection sheet was prepared in the same manner as in Example 1 except that the following components were used as the binder layer forming composition.

Composition of composition for forming binder layer 100 parts of acrylic composition same as in Example 1 100 parts of acrylic polymer having a multilayer structure same as in Example 1 40 parts of titanium oxide 40 parts of cellulose acetate butyrate solution * 8 parts * (to methyl ethyl ketone Solution dissolved to a solid content of 20%)

As the support layer, a composition having the same composition as in Example 1 was used. According to the emboss test,
The embossing of the binder layer was possible even after standing at room temperature for 1 day or 14 days, and the adhesive strength to the protective film was sufficient.

[0053]

As described above, according to the present invention, in a cellular retroreflective sheeting in which a support film for supporting glass beads has a two-layer structure of a binder layer and a support layer, the binder layer has a Tg of 35 ° C. In the following, it is made of a thermoplastic resin containing a resin with high adhesion to the protective film and a multi-layer polymer acrylic resin, and the support layer is made of a curable resin. The production method is simple while maintaining sufficient resistance to destruction, and does not require a high level of skill in process control.
In addition, a connecting sheet can be formed under optimum embossing conditions, and a reflection sheet having sufficient heat resistance and cold resistance can be obtained.

In order to show that the binder layer of the present invention is excellent in both heat resistance and cold resistance, physical properties at various temperatures were examined. The composition for forming a binder layer was applied on a silicone-treated release paper with a doctor blade, and the solvent was completely evaporated in an oven to form a coating film of about 60 to 65 µ. At this time, the coating film of the composition for forming a binder layer was adjusted so that the residual solvent was 1% or less. The coating is 2.
The test piece was cut into a size of 5 cm × 20 cm in length, and tensile strength and elongation were measured by a tensile tester. The temperature at the time of measurement was 0 ° C,
The temperatures were 25 ° C and 70 ° C. Table 1 shows the measurement results.

The following five coating films were measured for the binder layer-forming composition. A. Coating film of the formulation for forming the upper layer of the support film of Example 1 of Japanese Patent Application No. 59-48201. Coating film for forming a binder layer of Example 1 of the present invention C. Coating film for forming a binder layer of Example 2 of the present invention D. 40% of methyl methacrylate, 55 of ethyl acrylate
A. Acrylic composition with a Tg of 19.4 ° C. consisting of 5% of 2-hydroxyethyl methacrylate and 5% of 2-hydroxyethyl methacrylate E. Methyl methacrylate 50%, ethyl acrylate 45
Acrylic composition having a Tg of 31.6 DEG C. and a binder composition disclosed in Japanese Patent Application Laid-Open No. 40-7787.

[0056]

[Table 1]

The mere acrylic compositions D and F have almost the same cold resistance as A, which is a thermosetting type binder, but have a low tensile strength at 70 ° C. That is, heat resistance is poor. The acrylic composition E also has a tensile strength at 70 ° C. that is almost the same as that of A, but has poor cold resistance. On the other hand, the binder agent of the present invention has almost the same performance at high and low temperatures as A, and is excellent in both heat resistance and cold resistance.

Table 2 below shows the results of comparing the adhesive strength between the binder layer and the protective film by measuring the peel strength of each of the above-mentioned binder compound coating films.

The peel force was measured by laminating each of the binder compound coating films in the two protective films used in Example 1 at a lamination temperature of 130 ° C. (the thickness of the coating film was 80 to 85 μ). The measurement was performed by measuring the force when the laminate thus formed was peeled at a temperature of 25 ° C. at a speed of 100 mm / min. The peel force was measured after all the laminates were cured at 30 ° C. for 10 days after lamination.

[0060]

[Table 2]

From these results, it is clear that the adhesive strength of the binder layer to the protective film of the cellular retroreflective sheet according to the present invention is remarkably greater than that of the conventional retroreflective sheet using a thermoplastic resin. It turns out that it is not inferior to or superior to the improved capsule type reflection sheet of the structure.

[Brief description of the drawings]

FIG. 1 is a partially enlarged sectional view of one example of a reflection sheet of the present invention.

FIG. 2 is a view showing an example of a surface pattern formed by a connecting wall of the reflection sheet of the present invention.

[Explanation of symbols]

 1. Protective film 2. Glass beads 3. Support film 4. Metal deposited film 5. Binder layer 6. Support layer 7. Small lot vacancy 8. Connecting wall 9. Adhesive layer

Continued on the front page (51) Int.Cl. ⁶ Identification code FI B32B 15/08 B32B 15/08 E

Claims (2)

(57) [Claims] A supporting film made of a synthetic resin is provided with a binder layer in which a substantially lower hemispherical surface is buried and covered with a metal vapor-deposited film of glass beads arranged in a single layer, and on a side opposite to the glass beads in contact with the binder layer. A continuous line formed by partially heating and molding the support film between the protective film made of a transparent synthetic resin provided on the exposed glass bead surface side and the binder layer. In a cellular retroreflective sheet comprising a number of sealed small compartment cavities separated by a connecting wall, the binder layer has a glass transition point of 35 ° C. or less and a resin having a large adhesive force with a protective film and a multilayer structure. A cell formed by using a thermoplastic resin containing a polymer acrylic resin as a main component, and the support layer being formed mainly by a curable resin. Retroreflective sheet. 2. The cellular retroreflective sheet according to claim 1, wherein the binder layer further contains a fibrous resin.