JPH10300937A - Light transmission body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a light transmission body having excellent transparency, weatherability and heat resistance by forming the body of a polymer contg. specific repeating units. SOLUTION: The light transmission body formed of the polymer contg. the repeating units expressed by the formula is used. In the formula, R<1> denotes a hydrogen atom or alicyclic hydrocarbon group, substd. hydrocarbon group, (n) denotes a positive integer. R<1> is preferably a methyl group or of >=6C in terms of a sp.gr. and heat resistance as the repeating unit component expressed by formular of the polymer, for which methyl, cyclohexyl, tricyclodecanyl and adamantyl group are more particularly preferable. Further, the examples of the components exclusive of these repeating units include (meth)acrylate, such as methyl methacrylate and methyl acrylate, styrene, α-methyl styrene and acrylonitrile, among which the methyl methacrylate is mots preferable in terms of the transparency.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light guide which can be used for illumination of various instruments, various displays, signboard illumination, and the like.

[Prior art]

[0002] As a method of illuminating an instrument panel mounted on a vehicle, an aircraft, or the like, a light guide made of inorganic glass or a transparent resin material is used. This light guide has a side surface as a lighting surface, guides light incident from a light source placed near the lighting surface into the light guide, and a reflective layer such as an aluminum vapor-deposited layer provided on the back surface of the light guide. The light is reflected to illuminate a display located on the light emitting surface of the light guide.

In general, a light source is placed in the vicinity of a light-receiving surface of a light guide in order to allow a sufficient amount of light for illuminating a light-emitting surface on the front side to enter from a light-receiving surface having a small area. It is necessary that the daylighting surface is not deformed or deteriorated by the generated heat.

[0004] Light guides made of inorganic glass have excellent heat resistance and transparency, but have the drawback of poor workability. Recently, light guides made of thermoplastic polymers have been widely used.

As the thermoplastic polymer having excellent transparency and weather resistance, there is an acrylic polymer represented by polymethyl methacrylate. However, since the heat resistance is low, a thermoplastic resin molded from these polymers is used. Light bodies have the disadvantage that they are easily deformed by the heat generated when the lamp is lit. Polycarbonate is a thermoplastic polymer having relatively good transparency and high heat resistance temperature.

[0006]

However, the heat resistance of polycarbonate cannot be said to be sufficient, and in practical use, the shape of the light guide is not so high, or special measures are taken for heat shielding. The point is that consideration is needed. Polycarbonate also has a problem in weather resistance.
An object of the present invention is to provide a light guide having excellent transparency, weather resistance and heat resistance.

[0007]

The gist of the present invention resides in a light guide formed of a polymer containing a repeating unit represented by the following general formula (1).

[0008]

Embedded image

In the formula, R ¹ represents a hydrogen atom, a hydrocarbon group having 1 to 25 carbon atoms, an alicyclic hydrocarbon group, or a substituted hydrocarbon group, and n represents a positive integer.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION In the polymer used in the light guide of the present invention, the content of the repeating unit represented by the general formula (1) is not particularly limited. The content of the repeating unit is preferably 30% by weight or more, more preferably 50% by weight or more. If the content is too small, the heat resistance tends to be insufficient. Further, as the repeating unit component of the general formula (1) of the polymer, R ¹ is preferably a methyl group or a compound having 6 or more carbon atoms from the viewpoint of specific gravity and heat resistance, and methyl, cyclohexyl, tricyclodeca, and the like are preferable. Particularly preferably, they are a nyl or adamantyl group. Examples of components other than the repeating unit of the general formula (1) of the polymer include (meth) acrylates such as methyl methacrylate and methyl acrylate, styrene, α-methylstyrene, and acrylonitrile. In view of this, methyl methacrylate is most preferred. The molecular weight of the polymer is not particularly limited, but is preferably in the range of 10,000 to 1,000,000 in number average molecular weight Mn. More preferably, it is in the range of 30,000 to 500,000.

Although the light guide of the present invention has at least a light-emitting surface and a light-receiving surface, its shape is not particularly limited and can be any shape according to the purpose of use and design. The most common shape is a plate-like body, and one or two side surfaces of the plate-like body serve as a light-receiving surface, and one surface serves as a light-emitting surface.
A light source is usually arranged on the daylighting surface. On the surface opposite to the light emitting surface, a reflector or the like can be arranged as necessary.

The light guide of the present invention can be molded by a known melt molding method, solution molding method or the like. Among these molding methods, the injection molding method is most preferable from the viewpoint of efficiency. On this occasion,
Molding can be carried out by mixing an appropriate amount of a plasticizer, a crosslinking agent, a heat stabilizer, a coloring agent, an ultraviolet absorber, and a release agent.

Further, the light guide may be required to have abrasion resistance on the surface, so that a crosslinked cured resin film can be formed on the light emitting surface as needed. Examples of the compound that forms such a crosslinked cured resin include an acrylic polyfunctional compound and a silicon compound.

[0014]

The present invention will be described below in detail with reference to examples. In the examples, “parts” and “%” are all parts by weight and% by weight. In the following examples, the light guide and the cured film were evaluated by the following methods.

The molecular weight of the polymer was determined by the GPC method (solvent: chloroform) using PMMA as a standard.

The polymer composition was quantified by 1H NMR (solvent: chloroform-d, measurement temperature: 60 ° C.).

Saturated water absorption The pellet was dried at 80 ° C for 24 hours, and the cylinder temperature was 250
Injection molding was performed at 60 ° C. and a mold temperature of 60 ° C. to obtain a flat test plate of 50 × 100 × 2 mm. After drying at 80 ° C., the weight was measured and then immersed in warm water at 25 ° C. until the weight reached equilibrium. The weight after equilibrium was measured and determined by the following equation.

Saturated water absorption (%) = [(water absorption−dry weight) / dry weight] × 100 Total light transmittance Measured by an integrating sphere haze meter according to ASTM D1003.

VICAT softening temperature Measured according to ASTM D1525.

Yellowness index (YI value) The yellowness index (YI value) was measured in accordance with JIS standard K-7103 using a color difference analyzer (type 307, manufactured by Hitachi, Ltd.). The YI value was calculated from the X, Y, and Z stimulus values according to the following equation. YI value = 100 (1.28X-1.06Z) / Y

Abrasion resistance (Steel wool abrasion resistance) 000 steel wool ("Bonstar" manufactured by Nippon Steel Wool Co., Ltd.) was mounted on a circular pad having a diameter of 25 mm, and held on a reciprocating abrasion test stand. This pad was placed on the surface of the sample and subjected to 50 reciprocal scratches under a load of 1000 g. This sample was washed with a neutral detergent, and the haze value was measured with a haze meter.
The steel wool abrasion resistance was represented by "Haze value after abrasion-Haze value before abrasion".

Adhesion of the cured film The surface of the sample was cut with a razor to make 11 vertical and horizontal scratches at 1.5mm intervals to make 100 squares, and cellophane tape 25mm width
(Nichiban Co., Ltd.) is pressed against the squares and rapidly removed upward. The evaluation result was represented by the number of remaining squares / the total number of squares (100).

Weather resistance Sunshine weatherometer (WE-produced by Suga Test Instruments Co., Ltd.)
(SUN-DC), black panel temperature 63 ° C, water 12 min / dry
Exposure was performed for 1000 hours and 1500 hours in a 60-minute cycle. This sample was observed for the following appearance items. The appearance of the coating such as cracks, crazing, delamination, haze, yellowish color and the like was observed.

Example 1 In a flask having a capacity of 2 liters, 824 g (4 mol) of tricyclodecanyl acrylate, 160 g (4 mol) of paraformaldehyde having a purity of 75%, and 60 g of 1,4-diazabicyclo [2,2,2] octane (0.53 g) mol), p-methoxyphenol 616 mg, t-butyl alcohol 120 g while bubbling air with 80
The reaction was carried out at 5 ° C. for 5 days. After the completion of the reaction, the reaction solution was poured into 3 L of methanol and stirred for 30 minutes. Then, the mixed solution was allowed to stand at −20 ° C. overnight, and bis (α-hydroxymethyl acrylate tricyclodecanyl) ether as white crystals was obtained.
712 g (79.2% yield) was obtained.

In a 5 L flask containing 2500 ml of toluene as a solvent, 250 g of bis (α-hydroxymethyl acrylate) and 250 g of methyl methacrylate (MMA) were dissolved. To this solution was added 3 g of pertetra A (manufactured by NOF Corporation, purity: 20 wt.%) As an initiator, and the mixture was stirred for 40 minutes while purging with nitrogen. Thereafter, the mixture was heated to 95 ° C. to start the polymerization, and the polymerization was performed for 7 hours.

This reaction solution was put into a large amount of methanol to precipitate a polymer, which was filtered and washed with methanol. This is vacuum dried to obtain 455 g of a powdery polymer (yield:
91%). This polymer was shaped into a strand using an extruder (barrel temperature: about 250 ° C.) with a 30φ double vent, and pelletized. Using the obtained pellets, a light guide having a length of 15 cm, a width of 15 cm and a thickness of 2 mm was manufactured by injection molding. The injection molding machine uses IS-100 manufactured by Toshiba Machine Co., Ltd., cylinder temperature 250 ° C, mold temperature 100 ° C, injection pressure 1350k
The molding was performed under the conditions of g / cm ² . A part of the obtained light guide was cut, and its physical properties were measured. The following results were obtained. Polymer molecular weight: Mn = 95,000 Polymer composition: tricyclodecanyl ester / methyl methacrylate = 50/50 Saturated water absorption: 0.9% Total light transmittance: 91% VICAT softening temperature: 155 ° C. Yellowness index (YI value) : 1.5

Example 2 The following two types of curing liquids were prepared. 1) Composition of curing liquid 1 Dipentaerythritol hexaacrylate 39 parts Dipentaerythritol pentaacrylate 28 parts Tetrahydrofurfuryl acrylate 35 parts 2-hydroxy-4-n-octoxybenzophenone 10 parts Benzoin / isopropyl ether 4 parts Then, 75 parts of isopropyl alcohol and 75 parts of toluene were added as organic solvents to obtain a curing liquid 1.

2) Composition of Curing Liquid 2 Dipentaerythritol hexaacrylate 33 parts Dipentaerythritol pentaacrylate 22 parts Trimethylolethane / succinic acid / acrylic acid = esterified compound synthesized from 2/1 / 4.4 (molar ratio) 10 parts Tetrahydrofurfuryl acrylate 35 parts 2,4-dihydroxybenzophenone 10 parts Benzoin ethyl ether 4 parts Based on the above composition, 75 parts of isopropyl alcohol and 75 parts of n-butyl acetate were added as an organic solvent to obtain a curing liquid 2. .

After each of these two types of curing liquids was coated on one surface of the light guide, it was left at room temperature for 5 minutes to evaporate and remove the organic solvent. Then, it was cured by irradiation with a high-pressure mercury lamp (“I-Graphic” H08L21). The obtained light guide was evaluated for abrasion resistance of the cured film, adhesion of the cured film, and weather resistance of the light guide, and the results shown in Table 1 were obtained.

[0030]

[Table 1]

[0031]

The light guide of the present invention is excellent in transparency, weather resistance and heat resistance, and can be used as a light guide for lighting equipment or the like which requires such performance.

[Brief description of the drawings]

FIG. 1 is a perspective view of a light guide according to the present invention.

FIG. 2 is a cross-sectional view of the light guide of the present invention.

FIG. 3 is a sectional view of the light guide of the present invention.

[Brief description of reference numerals]

 DESCRIPTION OF SYMBOLS 1 Light guide 2 Coating of crosslinked resin 3 Reflective film 4 Lighting surface 5 Light emitting surface

Claims (2)

[Claims] 1. A light guide formed of a polymer containing a repeating unit represented by the following general formula (1). Embedded image (Wherein, R ¹ represents a hydrogen atom or a hydrocarbon group having 1 to 25 carbon atoms or an alicyclic hydrocarbon group, a substituted hydrocarbon group,
n represents a positive integer. ) 2. The light guide according to claim 1, wherein a coating of a crosslinked cured resin is formed on at least its light emitting surface.