JPH07330949A - Luminescent molding and its production - Google Patents

Abstract

PURPOSE:To obtain a molding having a high luminescence efficiency even when the content of an expensive luminescent agent therein is low by effectively using the luminescent agent. CONSTITUTION:A resin composition containing a luminescent agent, preferably a luminous pigment or the like, preferably in an amount of 0.1-50 pts.wt. per 100 pts.wt. the resin is injected into a rotary drum and subjected to rotational molding to obtain a molding in which the surface layer has a higher concentration of the luminescent agent on one side (a) than on the other side (b) due to centrifugal force. The concentration of the luminescent agent in the surface layer on the side (a) is preferably 1.2-50 times the concentration on the side (b).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a luminescent molded article which emits light upon irradiation with excitation light and a method for producing the same.

[0002]

2. Description of the Related Art In order to improve visibility and discrimination in a dark place,
Luminescent paints and luminescent paints are used for road signs, clock faces and hands. A phosphorescent pigment that emits phosphorescence by stimulating light is usually used for such a paint. In addition, in order to expand the color rendering range, it has been proposed to use a phosphorescent pigment and a fluorescent colorant in combination. For example, Japanese Patent Laid-Open No. 3-16
Japanese Patent No. 6269 proposes a color phosphorescent pigment in which a small amount of an organic coloring pigment is added to the phosphorescent pigment in order to improve weather resistance.

In Japanese Unexamined Patent Publication No. 4-51405, a phosphorescent pigment is applied or contained in a wall covering material to form a sheet, and the phosphorescence luminance 10 minutes after extinguishing the stimulating light is 0.3 mcd / m ^2.
The above wall covering materials are disclosed. Such wall coverings are
A method of applying a paint containing a phosphorescent pigment to a material such as paper,
Obtained by a method of molding a synthetic resin containing a phosphorescent pigment,
This is useful for lighting the evacuation passage to guide evacuation.

However, in the wall covering material, the luminous pigment is uniformly dispersed in the coating film or the molded article, so that the luminous pigment cannot be effectively used for light emission, and the luminous efficiency is lowered. Further, in order to increase the phosphorescence brightness after turning off the stimulating light, it is necessary to use a relatively large amount of expensive phosphorescent pigment, which makes the molded product expensive.

[0005]

SUMMARY OF THE INVENTION It is, therefore, an object of the present invention to provide a luminescent molded article which can effectively utilize an expensive luminescent agent and has a high luminous efficiency, and a method for producing the same.

Another object of the present invention is to provide a luminescent molded article capable of emitting light with high efficiency even when the content of the luminescent agent is small, and a method for producing the same.

Still another object of the present invention is to provide a method capable of efficiently producing the above-mentioned molded product by a simple operation.

[0008]

Means for Solving the Problems As a result of intensive studies for achieving the above-mentioned object, the present inventors have found that a small amount is obtained when a resin composition containing a luminescent agent such as a phosphorescent pigment is molded while exerting a centrifugal force. However, the inventors have found that the luminescent agent is segregated or concentrated in the direction of action of centrifugal force, and the concentrated luminescent agent can enhance the luminous efficiency, and completed the present invention.

That is, the luminescent molded product of the present invention is composed of a resin composition containing a luminescent agent such as a phosphorescent pigment, and the concentration of the luminescent agent in one surface layer portion of the molded product is higher than that in the other surface layer portion. . The content of the luminescent agent may be, for example, about 0.1 to 50 parts by weight with respect to 100 parts by weight of the resin.
The concentration of the luminescent agent on one surface layer side of the molded product is
It is often 1.2 to 50 times higher than the concentration of the other surface layer. The molded article may have various shapes, for example, a sheet shape.

The luminescent molded article can be produced, for example, by rotational molding (or centrifugal molding) of a resin composition containing a luminescent agent. In the following, centrifugal molding and rotation molding
Collectively referred to as rotational molding. At the time of molding, the resin composition may be rotationally molded while being heated, and the rotational speed depends on the segregation degree or concentration of the luminescent agent such as the phosphorescent pigment and the specific gravity difference or viscosity difference between the luminescent agent and other components. It can be selected accordingly.

The present invention will be described in more detail below.

The resin constituting the molded article includes various thermoplastic resins and thermosetting resins which have fluidity at room temperature or under heating. The fluidity is
It means at least fluidity at the time of molding, and may be fluidity such as a liquid or paste state, or may be melt fluidity.

Examples of the thermoplastic resin include olefin polymers such as polyethylene, polypropylene and ethylene-propylene copolymer, acrylic polymers such as polymethylmethacrylate, chlorine-containing polymers such as polyvinyl chloride, polyethylene terephthalate and poly. Polyester such as butylene terephthalate, polyamide 6, polyamide 66, polyamide 610, polyamide 1
1, polyamide such as polyamide 12, polycarbonate, polystyrene, acrylonitrile-styrene copolymer, styrene polymer such as ABS resin, synthetic rubber,
Examples include fibrin-based polymers such as cellulose derivatives. These thermoplastic resins may be used alone or in combination of two or more.

In the rotational molding method, a granular thermoplastic resin (for example, an olefin polymer, a polycarbonate,
Styrene resins, fibrin polymers, etc.) can also be used, so that various thermoplastic resins can be rotationally formed. Among these thermoplastic resins, in order to efficiently segregate the luminescent agent, for example, a polymer having a high rotational moldability and a low melt viscosity (for example, an olefin polymer, an acrylic polymer, a styrene polymer, etc.), a paste Polymerizable polymers such as polyvinyl chloride are preferred.

As the thermosetting resin, for example, phenol resin, diallyl phthalate resin, epoxy resin, vinyl ester resin, unsaturated polyester, polyurethane,
Examples include polyimide and silicon resin. Two or more kinds of these thermosetting resins can also be used if necessary.

Since the thermosetting resin is usually used in the form of a prepolymer, it has a low viscosity during molding and is convenient for segregating or concentrating the luminescent agent by rotational molding. Preferred thermosetting resins include thermoplastic resins whose viscosity at the time of molding can be reduced by a reactive diluent or a polymerizable vinyl monomer and which can be easily adjusted. For example, a diallyl phthalate resin can reduce the viscosity of a diallyl phthalate prepolymer with a diallyl phthalate monomer, and an epoxy resin can reduce the viscosity of an epoxy resin such as bisphenol A type with a reactive diluent, a vinyl ester resin and a vinyl ester resin. Saturated polyesters can be made low in viscosity with polymerizable vinyl monomers such as styrene and (meth) acrylic acid ester, and silicone resins and silicone rubbers are liquid or pasty curable silicone rubbers (for example, RTV (Room Temperature
Valcanizable) Silicone rubber and LTV (Low Temper)
ature Valcanizable) Silicone rubber etc.). Further, the thermosetting polyurethane can be composed of a urethane prepolymer having an isocyanate group at the terminal and a curing agent having an amino group or a hydroxyl group.

Among the above-mentioned thermosetting resins, the resins useful for obtaining a molded article having high toughness, heat resistance and abrasion resistance and durability include thermosetting polyurethane. Hereinafter, the thermosetting polyurethane will be described.

The urethane prepolymer has an excess amount of isocyanate groups with respect to hydroxyl groups,
It is obtained by reacting a polyol component with a polyisocyanate compound. Examples of the polyisocyanate compound include phenylene diisocyanate and 2,4
-Aromatic polyisocyanates such as tolylene diisocyanate, 2,6-tolylene diisocyanate, diphenylmethane-4,4'-diisocyanate; hexamethylene-1,6-diisocyanate, 2,2,4-trimethylhexamethylene-1,4 Aliphatic polyisocyanates such as diisocyanates, lysine diisocyanates;
Examples thereof include alicyclic polyisocyanates such as 1,4-cyclohexane diisocyanate, isophorone diisocyanate and hydrogenated xylylene diisocyanate; and dimers and trimers of these isocyanate compounds. These polyisocyanate compounds may be used alone or in combination of two or more. Of these polyisocyanate compounds, aromatic polyisocyanates are often used.

Examples of the polyol component include ethylene glycol, propylene glycol, 1,3-butanediol, tetramethylene glycol, 1,6-hexanediol, neopentyl glycol, glycerol,
Trimethylolpropane, pentaerythritol, bisphenol A, hydrogenated bisphenol A and polyhydric alcohols in which alkylene oxide is added to these; diethylene glycol, polyethylene glycol, dipropylene glycol, polypropylene glycol, polytetramethylene glycol, alkylene oxide copolymerized polyol, etc. Polyether polyols; Polyester polyols such as condensation-type polyester polyols obtained by the reaction of the polyhydric alcohol and polycarboxylic acid, lactone-based polyester polyols obtained by ring-opening polymerization of lactones such as ε-caprolactone; Polybutadiene polyols, etc. Other polyols are listed. These polyol components may be used alone or in combination of two or more. Of these polyol components, polyether polyols and polyester polyols are often used.

Examples of the curing agent having an amino group include monocyclic aromatic compounds such as 2,4-diaminotoluene, 2,6-diaminotoluene, m-phenylenediamine, p-phenylenediamine and p-xylylenediamine. Polyamine; 4,4'-diaminodiphenylmethane, 4,4 '
-Diamino-3,3'-dichlorodiphenylmethane,
Examples are polyamines such as diphenylmethane-based polyamines such as 2,2'-dimethyl-4,4'-diaminodiphenylmethane. Examples of the curing agent having a hydroxyl group include polyhydric alcohols such as 1,4-butanediol; hydroquinone diethylol ether,
1,4-bis (2-hydroxyethoxy) benzene,
2,2-bis (2-hydroxyethoxyphenyl) propane and the like can be mentioned. These curing agents can be used alone or as a mixture of two or more. Further, a curing agent having an amino group and a curing agent having a hydroxyl group may be used in combination.

Among the above curing agents, a curing agent having an amino group, particularly an aromatic polyamine, and among them, a diphenylmethane aromatic diamine such as 3,3′-dichloro-4,4′-diaminodiphenylmethane is preferable.

The ratio of the urethane prepolymer to the curing agent is such that amino groups or hydroxyl groups / isocyanate groups =
It can be used at a ratio of about 0.8 to 1.2 / 1 (equivalent ratio).

As the luminescent agent contained in the resin composition, various organic or inorganic substances that emit fluorescence or phosphorescence when excited by light irradiation can be used, and have a specific gravity higher than that of the resin composition excluding the luminescent agent. The type is not particularly limited as long as it is large. Preferred luminescent agents include substances that emit phosphorescence. The substance that emits phosphorescence may be a condensed polycyclic aromatic compound or the like, but it has a high phosphorescence brightness and an inorganic light emitting agent having a large difference in specific gravity (density difference) from the resin composition excluding the light emitting agent, particularly It is preferably composed of a phosphorescent pigment.

As the phosphorescent pigment, a conventional substance, for example,
Calcium sulfide (CaS: B with bismuth as activator)
i), calcium strontium sulfide ((Ca, Sr) S: Bi) with bismuth activator, zinc sulfide (ZnS: Cu) with copper activator, zinc cadmium sulfide with copper activator Examples thereof include metal sulfides activated with an activator such as ((Zn, Cd) S: Cu), ceramics-based phosphorescent pigments (for example, ceramics-based oxides composed of alumina containing rare earth elements), and the like. . These phosphorescent pigments can be used alone or in combination of two or more. As a phosphorescent pigment,
In many cases, zinc sulfide, which uses copper as an activator, and a ceramics-based phosphorescent pigment are used.

Difference in specific gravity (density difference) of the luminescent agent with respect to the resin
Is, for example, about 1.5 to 10, preferably about 2 to 7 (for example, 2.5 to 5) in many cases.

A luminescent pigment may be prepared by adding a radioactive substance such as promesium to a luminescent agent, particularly a luminous pigment. Further, in order to enhance color rendering properties, organic or inorganic color pigments, for example, azo pigments, quinacridone pigments, phthalocyanine pigments, organic pigments such as perylene pigments, chrome yellow, iron oxide, zinc yellow, navy blue, ultramarine blue. You may use together inorganic pigments such as.

The amount of the luminescent agent used can be selected within a range that does not impair the luminous efficiency, and is, for example, 0.1 to 50 parts by weight, preferably 1 to 40 parts by weight with respect to 100 parts by weight of the thermoplastic resin or the thermosetting resin. It is about 1 to 30 parts by weight, and more preferably about 5 to 25 parts by weight. In addition,
In the present invention, the luminous efficiency can be improved even if the amount of the luminescent agent used is small. For example, even if the amount of the conventional phosphorescent pigment used is about 20 to 70% by weight, an afterglow brightness equal to or higher than that is obtained.

When the thermoplastic resin is in powder form, the luminescent agent can be contained in the granular thermoplastic resin. The resin composition is a conventional additive, for example, an antioxidant, a stabilizer such as an ultraviolet absorber, a plasticizer, a flame retardant, a release agent, an antiblocking agent, a filler, as long as the light emitting property is not impaired. It may contain a reinforcing agent and the like. In addition, in order to adjust the viscosity of the resin composition and to promote the segregation (concentration) of the luminescent agent, the resin composition may be mixed with water, an organic solvent, if necessary, within a range that does not impair workability such as moldability. Solvents (for example, hydrocarbons, halogenated hydrocarbons, esters, ketones,
Ethers, etc.) may be included.

The form of the molded product formed from such a resin composition is not particularly limited, and can be selected according to the shape of the member required to emit light, the application and the application method. The preferable shape of the molded product includes a shape that can be efficiently obtained by rotational molding, such as a hollow cylindrical shape and a sheet shape.

The characteristic feature of the present invention is that the concentration of the luminescent agent (such as a phosphorescent pigment) in one surface layer portion of the molded article is made higher than the concentration in the other surface layer portion facing the surface layer portion to improve the luminous efficiency. There is a point to improve. That is, when molded by rotational molding, the centrifugal force acts on the luminescent agent, and the luminescent agent is segregated or concentrated on the outer surface layer portion of the molded article in which the centrifugal force acts, and the concentration of the luminescent agent on one surface layer portion. The inside or the other surface layer portion (that is, the surface layer portion on the rotating shaft side facing the surface layer portion).
Can be higher than the concentration of. Further, when the molded product is in the form of a sheet, the concentration of the luminescent agent in the surface layer portion on one side of the sheet-shaped molded product can be made higher than that in the surface layer portion on the other side. Therefore, even if the amount of the luminescent agent used is small, the luminous efficiency of the surface layer portion having a high concentration can be increased.

The proportion of the luminescent agent in one surface layer portion of the molded product and the other surface layer portion facing the molded article can be easily adjusted by the rotational speed in rotational molding, the viscosity of the resin composition, the specific gravity of the luminescent agent, and the like. The concentration of the luminescent agent in one surface layer portion is 1.2 to 50 times, preferably 1.3 to 25 times, more preferably 1.5 to 10 times higher than the concentration in the other surface layer portion. The concentration of the luminescent agent in the surface layer is usually about 1.5 to 5 times the concentration in the other surface layer. The concentration of the luminescent agent in the surface layer of the molded product is determined by a conventional method, for example, ESCA (Electron spectroscopy for ordinary chemical analysis means for analyzing the composition ratio).
It can be measured by surface analysis means such as chemical analysis) or optical analysis means utilizing the fact that the concentration of the luminescent agent and the emission brightness (intensity) are in a proportional relationship.

Such a luminescent molded article can be manufactured by a rotational molding method in which a moldable resin composition containing a luminescent agent is molded while applying a centrifugal force. At the time of rotational molding, the resin composition can be supplied into a rotatable closed metal mold such as a rotating drum in various forms such as powder, paste, and melt. The resin composition adheres to the inner wall of the closed mold with the rotation molding, and the luminescent agent is concentrated on the outer side, that is, the inner wall side of the closed mold by the action of centrifugal force.

In order to efficiently segregate (concentrate) the luminescent agent during rotational molding, the viscosity (melt viscosity, etc.) of the molding resin composition is lowered while heating by various heating methods such as an air heating method and an open flame method. Preferably. The heating may be performed by a heating furnace in which a closed container is rotatably arranged. The heating temperature can be selected according to the type of resin, the melt viscosity of the thermoplastic resin and the curing temperature of the thermosetting resin, and is, for example, 50 to 350 ° C., preferably 70 to 3
It is about 00 ° C, and 70 to 20 in the case of a thermosetting resin.
It is often about 0 ° C.

Centrifugal force is the number of rotations of the closed mold (drum),
It can be adjusted according to the inner diameter of the drum, the viscosity of the resin composition, the density difference with the luminescent agent, and the like. For example, the rotation speed of the closed mold (drum) is 50 to 3000 rpm, preferably 100 to 2 rpm.
000 rpm, more preferably 150 to 1000 rp
m, and often 100 to 700 rpm. By the action of such centrifugal force, the luminescent agent can be efficiently moved to the surface layer portion on the inner wall side of the drum to be concentrated.

According to such a method, the luminescent agent is concentrated on the surface layer portion which is in contact with the inner wall of the rotary mold, so that the surface smoothness of the surface of the molded article on the side where the concentration of the luminescent agent is high can be enhanced. .

A molded product can be obtained by cooling the closed mold and taking out the molded product. This molded product is
It may be a solid molded product (for example, a rod shape) formed by filling the resin composition in a closed container, but it is usually a hollow molding formed along the inner wall of the closed container (drum). It is often an article (for example, a hollow cylindrical shape). The sheet-like luminescent molded product can be obtained by appropriately cutting a hollow molded product. The thickness of the sheet-shaped molded product is not particularly limited, but is, for example, 0.1 to 10
mm, preferably about 0.5 to 5 mm.

Such a molded article can be used as a light emitting member as it is, and may be processed into an appropriate shape by secondary processing or the like. The luminescent molded product, particularly the sheet-shaped molded product, can be used as a laminate. The sheet-like laminated body includes (1) a laminated sheet of a luminescent sheet and a substrate such as a film or a sheet, (2) a laminated sheet of a luminescent sheet and an adhesive layer, and (3) a sheet of the above (1). Among them, a laminated sheet in which a pressure-sensitive adhesive layer is laminated on the base material side, a laminated sheet in which a peelable release sheet is laminated on the pressure-sensitive adhesive layer of (2) and (3) above, and the like are included.

Further, one surface of the molded product having a high concentration of the luminescent agent is a coating layer (for example, a clear coating layer which may be colored) within a range not impairing absorption and emission of light by the luminescent agent. It may be coated with, for example, to improve weather resistance, chemical resistance and the like.

When one surface of the luminescent molded product is irradiated with excitation light such as sunlight, fluorescent light, or ultraviolet light, the luminescent agent is excited and emits light. Also, when using a phosphorescent pigment,
It absorbs and stores excitation light and emits light in the dark. Therefore, the luminescent molded product can be used as it is, and can be attached to a predetermined member to be attached by using attachment means such as an adhesive or the above-mentioned adhesive. Such a luminescent member,
It can be used as a sign member or notification member for evacuation, firefighting, disaster prevention, ships, fire extinguishers, etc., a display member for guiding or displaying guidance, fishing tackle, an identification member attached to fishing tackle, etc.

[0040]

EFFECTS OF THE INVENTION Since the luminescent molded article of the present invention can increase the concentration of the luminescent agent in one surface layer portion, an expensive luminescent agent can be effectively used and the luminous efficiency can be enhanced.
Further, even if the content of the luminescent agent is small, the concentration of the luminescent agent can be increased in one of the surface layer portions, so that light can be emitted with high efficiency.

In the method of the present invention, a molded article as described above is
It can be manufactured efficiently by a simple operation called rotational molding.

[0042]

The present invention will be described in more detail based on the following examples, but the invention is not intended to be limited by these examples.

Examples 1 to 4 A urethane prepolymer using polypropylene glycol as a diol component (Sanprene P894X1 manufactured by Sanyo Kasei Co., Ltd.) was stored in a tank A at a temperature of 80 ° C., and a curing agent (4,4′-diamino) was stored. -3,3′-dichlorodiphenylmethane) is stored in tank B at a temperature of 120 ° C., and a dispersion containing a phosphorescent pigment (manufactured by Nemoto Special Chemical Co., Ltd., GSS) and a plasticizer (dioctyl phthalate) is stored in tank C at room temperature. The mixture was stored in and was mixed with the casting machine equipped with a flow rate control device by adjusting the ratio of each component in each tank, and the mixture was discharged and injected into the rotating drum (closed mold) of the centrifugal molding machine.

The ratio of the phosphorescent pigment to 100 parts by weight of the urethane prepolymer was 2 parts by weight (Example 1), 6 parts by weight.
Parts by weight (Example 2), 10 parts by weight (Example 3) and 2
0 parts by weight (Example 4). Further, the ratio of the curing agent to 100 parts by weight of the urethane prepolymer is 12 parts by weight (NH ₂ group / NCO group =
1.0 (equivalent ratio)).

A drum (inner diameter of 650 mmφ) was rotationally molded at a rotation speed of 400 rpm and a temperature of 110 ° C., and the resulting hollow molded article was cut to obtain a thickness of 2 m.
m polyurethane rubber sheet was prepared.

Comparative Example 12 parts by weight of the curing agent of Example 1 was added to 100 parts by weight of the urethane prepolymer of Example 1, and
20 parts by weight of the dispersion in terms of phosphorescent pigment is mixed, the obtained resin composition is injected into a predetermined molding die, primary cured at 100 ° C. for 2 hours, and then secondary cured at 100 ° C. for 16 hours,
A sheet having a thickness of 2 mm was produced.

Examples 5 to 8 Sheets having a thickness of 3 mm were produced in the same manner as in Examples 1 to 4 except that the amount of the mixture injected into the rotary drum was increased.
The ratio of the phosphorescent pigment to 100 parts by weight of the urethane prepolymer was 2 parts by weight (Example 5), 6 parts by weight (Example 6), and 10 parts by weight (Example 7), as in the above examples.
And 20 parts by weight (Example 8).

Then, the sheets obtained in the above-mentioned Examples and Comparative Examples were left in a dark place for 4 hours or more to completely eliminate afterglow, and then D65 in accordance with JIS Z-9100.
Using a standard light source, one surface side of the sheet was stimulated at 200 lux for 4 minutes, and the afterglow brightness after a predetermined time elapsed was measured. The sheets obtained in the examples were stimulated by irradiating the surface side, which was in contact with the rotary drum, with excitation light. The obtained results are shown in the table and FIGS.

[0049]

[Table 1] As is clear from the table and the figures, and in particular, comparison between Examples 3 and 4 and Comparative Example, the sheet of Example has a larger afterglow brightness than the sheet of Comparative Example, and the amount of the luminescent agent used is Comparative Example. The same afterglow brightness is exhibited even if it is about ½ of the above.

[Brief description of drawings]

FIG. 1 is a graph showing the results in Examples 1 to 4 and Comparative Example.

FIG. 2 is a graph showing the results in Examples 5-8.

Claims (10)

[Claims] 1. A luminescent molded article comprising a resin composition containing a luminescent agent, wherein the luminescent agent concentration in one surface layer portion of the molded article is higher than that in the other surface layer portion. 2. The luminescent molded article according to claim 1, wherein the luminescent agent is composed of at least a phosphorescent pigment. 3. The luminescent molded article according to claim 2, which contains 0.1 to 50 parts by weight of the phosphorescent pigment with respect to 100 parts by weight of the resin. 4. The luminescent molded product according to claim 2, wherein the concentration of the phosphorescent pigment on one surface layer side of the molded product is 1.2 to 50 times higher than the concentration of the other surface layer portion. 5. The luminescent molded product according to claim 1, wherein the molded product is in the form of a sheet. 6. The concentration of the phosphorescent pigment on the one surface layer side of the molded article is 1 to 30 parts by weight with respect to 100 parts by weight of the thermosetting resin, and the concentration of the phosphorescent pigment on one surface layer side of the molded product is 1 than the concentration on the other surface layer part. A sheet-like luminescent molded product that is 0.5 to 10 times higher. 7. A method for producing a luminescent molded article, which comprises rotationally molding a resin composition containing a luminescent agent. 8. The method for producing a luminescent molded product according to claim 7, wherein the resin composition containing a phosphorescent pigment is rotationally molded while being heated to obtain a sheet-shaped molded product. 9. A method for producing a sheet-like luminescent molded article, which comprises rotationally molding a thermosetting resin composition containing a luminescent agent at a drum rotation speed of 50 to 3000 rpm. 10. With respect to 100 parts by weight of the thermosetting resin,
A thermosetting resin composition containing 5 to 25 parts by weight of a phosphorescent pigment,
The drum was rotationally molded at a rotational speed of 100 to 2000 rpm while heating, and the concentration of the luminescent agent in one surface layer of the molded product was
A method for producing a luminescent molded article having a higher level than the other surface layer portion.