JPH11345504A - Cover for lamp - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lamp cover made of a resin having excellent in transparency, weather resistance, heat resistance, and moldability, having high scratch resistance. SOLUTION: This cover is manufactured by polymerizing and curing a resin composition which consists of (A) 30 to 60 pts.wt. of an unsaturated monomer mixture composed chiefly of an unsaturated monomer having a least two radically polymerizable double bonds in one molecule, (B) 40 to 70 pts.wt. of resin particles made of a polymer of an unsaturated monomer composed chiefly of methyl methacrylate and consisting of 20 to 100 wt.% partly crosslinked resin particles and 0 to 80 wt.% uncrosslinked resin particles, and (C) 0.1 to 5 pts.wt. of a radical polymerization initiator for a total of 100 pts.wt. of (A) and (B) components.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to transparency, weather resistance,
The present invention relates to a methacrylic resin lamp cover excellent in heat resistance and moldability and having high scratch resistance, and a lamp cover.

[0002]

2. Description of the Related Art Heretofore, glass headlamp covers for automobiles and motorcycles have been mainly used. This is because the headlamp has an integral structure in which an inert gas is sealed therein, and the front cover needs to suppress the permeation of the gas. In recent years, this inert gas-filled lamp structure has been replaced by a bulb replacement type, and glass lamp covers have been replaced with polycarbonate resins in order to reduce the weight of automobiles and respond to diversification of designs. Was.

As a characteristic required for a headlamp cover of a car or a motorcycle, it is necessary that the cover is hardly damaged by insects and dust flying during running, or by friction with a brush at the time of car washing. In addition, in outdoor use, it is required that deterioration is small over a long period of time.

[0004]

In the case of the above-mentioned polycarbonate resin, the surface hardness of the polycarbonate resin itself is not so high, and the deterioration such as yellowing due to ultraviolet rays is remarkable. Forming a cured film,
It is necessary to perform a so-called hard coat treatment. If the surface hardness of the resin base material itself is high, such a hard coat treatment is not required, and the manufacturing process of the lamp lens can be reduced by one. Further, a general composition for a hard coat contains a considerable amount of an organic solvent, and in the hard coat step, equipment for recovering a volatile solvent is required for the purpose of preserving a working environment.

In view of such circumstances, the present inventors have conducted intensive studies with the aim of providing a cover for a lamp which has a practically sufficient surface hardness without a hard coat, and is excellent in transparency and weather resistance. As a result, it has been found that a resin obtained by polymerizing and curing a specific resin composition can be suitably used as a lamp cover, and the present invention has been completed.

[0006]

That is, according to the present invention, a resin composition comprising the following components (A) to (C) is polymerized and cured to form a radical polymerization in one molecule of a lamp cover (A). 30 to 60 parts by weight of an unsaturated monomer mixture mainly composed of an unsaturated monomer having at least two possible double bonds, and (B) a polymer of an unsaturated monomer mainly composed of methyl methacrylate The resin is composed of 20 to 100% by weight of partially crosslinked resin particles and 0 to 80% by weight of non-crosslinked resin particles. ) And (B) in a total amount of 0.1 to 5 parts by weight.

The present invention further provides a resin composition containing the following components (A) to (C), which is heated into a soft molding material, and the molding material is prepared by injection molding, compression molding or transfer molding. A lamp cover (A) obtained by molding, polymerizing and curing according to the above method, is an unsaturated monomer mixture mainly composed of an unsaturated monomer having at least two double bonds capable of radical polymerization in one molecule. 30 to 60 parts by weight, (B) a polymer of an unsaturated monomer mainly composed of methyl methacrylate, wherein 20 to 100% by weight of partially crosslinked resin particles and 0 to 80% by weight of non-crosslinked The purpose is to provide 40 to 70 parts by weight of resin particles composed of resin particles, and 0.1 to 5 parts by weight of (C) the radical polymerization initiator based on 100 parts by weight of the total of components (A) and (B). .

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
The lamp cover according to the present invention is a cover for a lamp used for a vehicle, for a ship, for an aircraft, for an outdoor use, for a signal, and the like, and as an example, a head lamp, a tail lamp, a fog lamp, a halogen lamp, a metal halide lamp, Covers such as xenon lamps, fluorescent mercury lamps, sodium lamps, and the like.

[0009] In the present invention, an unsaturated monomer having at least two radically polymerizable double bonds in one molecule, which is a component (A) of the resin composition constituting the lamp cover, is mainly used. The unsaturated monomer mixture is a mixture containing at least about 50% by weight of an unsaturated monomer having at least two radically polymerizable double bonds in one molecule, and an unsaturated monomer copolymerizable therewith. And a mixture with

Examples of the unsaturated monomer having at least two radical polymerizable double bonds in one molecule (polyfunctional unsaturated monomer) include, for example, allyl methacrylate, ethylene glycol di (meth) acrylate, diethylene glycol Di (meth) acrylate, triethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, 1,3-butylene glycol di (meth) acrylate, 1,6-hexanediol di (Meth) acrylate, neopentyl glycol di (meth) acrylate, divinylbenzene, diallyl phthalate, trimethylolpropane tri (meth) acrylate, tetramethylol methane tri (meth) acrylate, tetramethylol methyl Ntetora (meth) acrylate. It is used alone or in combination of two or more.

The unsaturated monomer copolymerizable with the polyfunctional unsaturated monomer includes, for example, methyl (meth)
Acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate,
Methacrylic acid or acrylic acid such as 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, isobornyl (meth) acrylate, benzyl (meth) acrylate, cyclohexyl (meth) acrylate, and aliphatic; Esters with aromatic or alicyclic alcohols;
(Meth) acrylic monomers such as hydroxyalkyl esters such as hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate and hydroxybutyl (meth) acrylate; unsaturated acids such as acrylic acid and methacrylic acid; styrene; Styrene-based monomers such as α-methylstyrene; monofunctional unsaturated monomers such as acrylonitrile, methacrylonitrile, maleic anhydride, phenylmaleimide, cyclohexylmaleimide, and vinyl acetate, but are not limited thereto. is not.

In the unsaturated monomer mixture of the component (A), a homopolymer or copolymer of the above polyfunctional unsaturated monomer or monofunctional unsaturated monomer can be dissolved and contained. .

The unsaturated monomer mixture of the component (A) is used in an amount of about 30 to 30 parts by weight of the total of 100 parts by weight of the components (A) and (B).
Used in the range of 60 parts by weight. If the amount is less than about 30 parts by weight, sufficient fluidity cannot be obtained when molding the resin composition.
Conversely, if the amount is more than about 60 parts by weight, the handling becomes poor such that the stickiness of the surface after kneading the resin composition becomes large and the shape is difficult to maintain, which is not preferable. Also,
Shrinkage due to polymerization during molding becomes large, and it becomes difficult to obtain a molded body having a smooth surface.

In the present invention, the resin particles composed of a polymer of an unsaturated monomer mainly composed of methyl methacrylate as the component (B) are defined as methyl methacrylate and another copolymerizable unsaturated monomer. And a resin component of which methyl methacrylate accounts for 50% by weight or more.

As the unsaturated monomer copolymerizable with methyl methacrylate, the above-mentioned polyfunctional unsaturated monomer and monofunctional unsaturated monomer are mentioned.

Examples of the polyfunctional unsaturated monomer include the same ones as described above, for example, allyl methacrylate, ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate. Acrylate, polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, 1,3-butylene glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate , Divinylbenzene, diallyl phthalate, trimethylolpropane tri (meth) acrylate, tetramethylolmethane tri (meth) acrylate, tetramethylolmethanetetra (meth) acrylate and the like. That is, it may be any monomer capable of copolymerizing with methyl methacrylate, but is not limited thereto.

Examples of the monofunctional unsaturated monomer include the same ones as described above. For example, methyl acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl ( Methacrylic acid or acrylic acid such as meth) acrylate, lauryl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, isobornyl (meth) acrylate, benzyl (meth) acrylate, cyclohexyl (meth) acrylate, and aliphatic, aromatic, and fatty acids Esters with cyclic alcohols; (meth) acrylic monomers such as hydroxyalkyl esters such as hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate and hydroxybutyl (meth) acrylate; acrylic Styrene monomers such as styrene and α-methylstyrene; acrylonitrile, methacrylonitrile, maleic anhydride, phenylmaleimide, cyclohexylmaleimide, and vinyl acetate. It is not something to be done.

The unsaturated monomer may contain a polyfunctional unsaturated monomer or a monofunctional unsaturated monomer homopolymer or copolymer dissolved therein as described above.

As the resin particles, for example, resin particles obtained by polymerization such as emulsion polymerization, suspension polymerization and dispersion polymerization are used. Resin particles obtained by pulverizing a polymer obtained by another polymerization method can also be used.

The size of the resin particles is usually about 1 to
Those having a size of 100 μm are preferably used. When resin particles smaller than about 1 μm are used, mixing and kneading with the unsaturated monomer mixture of the component (A) tend to be difficult, and conversely, when resin particles having a size exceeding about 100 μm are used. Is not preferred because the particle shape may be noticeable after molding.

Incidentally, about 20 to 10 of the resin particles are used.
0% by weight uses partially crosslinked resin particles, and about 0 to 80% by weight uses non-crosslinked resin particles. When the proportion of the partially crosslinked resin particles in the resin particles is less than about 20% by weight, the handleability of a soft molding material obtained after mixing and kneading the resin composition deteriorates.

The partially crosslinked resin particles referred to here generally swell, but do not completely dissolve, in a solvent capable of dissolving a methyl methacrylate polymer such as acetone. Resin particles. Such resin particles contain about 50% by weight of methyl methacrylate.
It can be obtained by adding a polyfunctional unsaturated monomer when producing a resin particle or a polymer by polymerizing a mixture of the above-mentioned and an unsaturated monomer copolymerizable therewith.

The resin particles of the component (B) are used in an amount of about 40 to 70 parts by weight based on a total of 100 parts by weight of the components (A) and (B). If the amount is less than about 40 parts by weight, the mixture of the soft molding material obtained after mixing and kneading the resin composition becomes sticky and the handleability becomes poor, and
If it is more than 0% by weight, uniform mixing and kneading become difficult.

If necessary, known additives such as an antioxidant, an ultraviolet absorber, a chain transfer agent, a release agent, a dye, and a pigment may be added to the resin particles.

In the present invention, a radical polymerization initiator is added as the component (C) to polymerize and cure the unsaturated monomer mixture of the component (A). Examples of the radical polymerization initiator include 1,1′-azobis (cyclohexane-1-carbonitrile), 2,2′-azobis (2,4,4-trimethylpentene), and 2,2′-azobis (2-methylpropane). ), 2-cyano-2-propyrazoformamide,
2,2′-azobis (2-hydroxy-methylpropionate), 2,2′-azobis (2-methyl-butyronitrile), 2,2′-azobisisobutyronitrile,
Azo compounds such as 2,2'-azobis [2- (2-imidazolin-2-yl) propane] and dimethyl 2,2'-azobis (2-methylpropionate); dicumyl peroxide, t-butylcumi Luper oxide, di-t
-Butyl peroxide, benzoyl peroxide,
Diacyl such as lauroyl peroxide, dialkyl peroxide-based initiator; t-butylperoxy-3,
3,5-trimethylhexanoate, t-butylperoxylaurate, t-butylperoxyisobutyrate, t-butylperoxyacetate, di-t-butylperoxyhexahydroterephthalate, di-t-butylperate Oxyazelate, t-butylperoxy-2-
Peroxyester-based initiators such as ethylhexanoate, 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate, t-amylperoxy-2-ethylhexanoate; t-butyl Percarbonate-based initiators such as peroxyallyl carbonate and t-butyl peroxyisopropyl carbonate; 1,1
-Di-t-butylperoxycyclohexane, 1,1-
Di-tert-butylperoxy-3,3,5-trimethylcyclohexane, 1,1-di-tert-hexylperoxy-
Peroxyketal-based initiators such as 3,3,5-trimethylcyclohexane are exemplified. These radical polymerization initiators are used alone or in combination of two or more.

These polymerization initiators are used in an amount of about 0.1 to 5 parts by weight based on 100 parts by weight of the total of the components (A) and (B). If the amount is less than about 0.1 part by weight, it takes a long time to carry out the radical polymerization. If the amount exceeds about 5 parts by weight, the unsaturated monomer mixture of the component (A) cannot be polymerized stably.

The resin composition containing the components (A) to (C) of the present invention contains a releasing agent, an ultraviolet absorber, a dye, a pigment, a polymerization inhibitor, a chain transfer agent, an antioxidant, Flame retardant,
A reinforcing agent or the like can be added.

Next, a method for producing a lamp cover as a molded article from the resin composition will be described. The production of the molded article in the present invention is a step of kneading and aging, and a polymerization and
It consists of two steps of curing.

First, in the kneading and aging step, the components (A) to (C) are mixed, and it is sufficient that a homogeneous mixture is finally obtained. As a specific method, for example, the component (A)
To (C) to obtain a resin composition in the form of a slurry, which is then aged in an appropriate container. The shape of the container is not particularly limited. Further, as the container, a cell or the like including at least two flat plates and a sealing material for sealing the periphery can be used. The material of the container is not particularly limited as long as it is not dissolved or eroded in the unsaturated monomer mixture.

After mixing the components (A) to (C), the mixture is poured into a container and ripened at about 20 ° C. to 80 ° C. During the aging step, the unsaturated monomer mixture (A) is impregnated into the resin particles (B),
When non-crosslinked particles are used for the resin particles (B), the noncrosslinked particles are dissolved by (A). The appearance of the mixture changes from a slurry to a clay during the aging step, and a soft molding material is obtained.

Heating at about 80 ° C. during aging is not preferred because the polymerization and curing reaction by the added radical polymerization initiator are started. On the other hand, if the temperature is lower than about 20 ° C., aging takes a long time, which is not preferable. Therefore, the aging temperature is preferably in the range of about 20C to 80C. The aging conditions are appropriately selected depending on the resin particles used, the composition of the unsaturated monomer mixture, the type of polymerization initiator used, and the like.

As another method, for example, the component (A)
When mixing and kneading (C) to (C), an appropriate temperature is selected, and aging can be performed at the same time. In that case, as a device for kneading, a known kneading device such as a twin-screw extruder, a universal mixer, a kneader, and a Banbury mixer can be used.

The clay-like molding material thus obtained is soft and can be easily processed into a desired shape which is advantageous during handling. For example, sheet, block,
It can be handled in the form of cake, rod, pellet, ribbon, strand, etc.

Next, in the step of polymerization and curing, the above-mentioned clay-like molding material is charged into molding dies having various desired shapes, pressurized and heated to perform a molding and curing reaction, and a lamp is formed. Get a cover for

In order to carry out a curing reaction by radical polymerization,
The heating is performed at a temperature of about 80 to 160 ° C. If the temperature is lower than about 80 ° C., the curing reaction takes a long time,
Industrially disadvantageous. Conversely, when heated at a temperature exceeding about 160 ° C., decomposition or coloring may occur.

As a molding method applicable to the present invention, compression molding, injection molding, transfer molding and the like can be applied. Also,
The applicable molding method is not limited to these as long as it is a molding method in which pressing and heating are performed to perform a shaping reaction and a curing reaction.

In the case of compression molding, a compression molding machine composed of a general pressure unit and a mold can be applied. The mold temperature is adjusted in the range of 80 to 160 ° C. The temperature of the front mold and the rear mold may be adjusted to be the same, or a difference may be provided within a range not exceeding 20 ° C. A mold clamping pressure of about 20 to 100 kg / cm ² can be applied. If the pressure is lower than 20 kg / cm ² , defects such as internal cracks are likely to occur in the molded product, and surface defects due to boiling of the contained methyl methacrylate may occur. On the other hand, when the mold clamping pressure is 100
If it exceeds kg / cm ² , the material may flow out of the mold during pressurization. The above mold temperature, mold clamping pressure,
The mold-clamping speed, the injection position of the molding material into the mold, and the like can be appropriately selected and determined depending on the shape of the lamp cover to be molded and the desired production time.

In the case of injection molding and transfer molding, an injection molding machine composed of an injection unit and a mold clamping unit and a transfer molding machine can be applied. Screws having a compression ratio not exceeding 1.5 can be suitably used for metering and injection. In addition, a structure in which a check valve of various structures is attached to the tip portion can be applied.

It is preferable to control the temperature of the cylinder section covering the screw or the transfer pipe section in the transfer molding so as not to exceed 60 ° C. If the temperature is higher than 60 ° C., the curing reaction may be started when the temperature becomes locally high due to the heat generated by shearing with the screw or cylinder or the heat generated by shearing with the pipe during transfer, which is not preferable.

The mold temperature is adjusted in the range of 80 to 160 ° C. The temperature of the front mold and the rear mold may be adjusted to be the same, or a difference may be provided within a range not exceeding 20 ° C. The mold may be clamped at a constant pressure,
The pressure and the mold clearance may be controlled continuously or stepwise according to the progress of the curing reaction.

The molding conditions at the time of injection molding and transfer molding can be appropriately selected and determined according to the shape of the lamp cover to be molded and the desired production time.

The components (A) thus obtained
A molded article made of the resin composition containing (C) has an excellent hardness of 3H or more, usually 4H or more in terms of pencil hardness.

[0043]

According to the present invention described in detail above, a lamp cover having a high surface hardness and excellent scratch resistance can be stably and easily manufactured and provided.

[0044]

The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the present invention is limited thereto. The evaluation was performed by the following method. (1) Surface hardness of molded article A pencil hardness corresponding to the surface hardness was measured and evaluated by a pencil scratch test of JIS-K5400. (2) Transparency Total light transmittance was measured and evaluated according to JIS-K7105. (3) Weather resistance Using a sunshine weatherometer (manufactured by Suga Test Instruments), the change in transparency after 1000 hours was measured and evaluated.

Example 1 In a 1-liter round bottom flask, 28 parts by weight of neopentyl glycol dimethacrylate [NK ester NPG (manufactured by Shin-Nakamura Chemical Co., Ltd.)], 22 parts by weight of methyl methacrylate, partially crosslinked resin particles [Sumipex XC-1
A (manufactured by Sumitomo Chemical Co., Ltd.)] 36 parts by weight, non-crosslinked resin particles [SUMIPEX MHF (manufactured by Sumitomo Chemical Co., Ltd.)] 14 parts by weight, polymerization initiator (t-butyl peroxyisopropyl carbonate) 0.23 part by weight Then, the mixture was stirred and mixed to obtain a slurry resin composition.

After degassing the resin composition under reduced pressure, a glass plate (thickness: 5 mm) having a polyethylene film adhered to the inner surface and a gasket made of a vinyl chloride resin are used so that the gap between the glass plates is 5 mm. Into the cell
Aged in a hot air drying oven at 60 ° C. for 7 hours. After cooling to room temperature, the glass plate and the polyethylene film were removed to obtain a clay-like molding material.

Next, 80 g of the molding material was put into a 120 × 120 × 20 mm dish-shaped lamp cover mold.
1 at a temperature of 120 ° C and a mold clamping pressure of 70 kg / cm2.
Heating and pressurization was performed for 0 minutes to produce a lamp cover. The surface hardness of the obtained lamp cover was 4H, and the total light transmittance was 93.0%. Further, when the weather resistance was evaluated, the total light transmittance after 1000 hours had been 92.6%, and no change in coloring or other appearance was observed.

Example 2 25 parts by weight of neopentyl glycol dimethacrylate [NK ester NPG (manufactured by Shin-Nakamura Chemical Co., Ltd.)], 20 parts by weight of methyl methacrylate, partially crosslinked resin particles [SUMIPEX XC-1A (Sumitomo Chemical Industries, Ltd.) 40% by weight, non-crosslinked resin particles [Sumipex M
HF (manufactured by Sumitomo Chemical Co., Ltd.) 15 parts by weight, polymerization initiator (t-butyl peroxyisopropyl carbonate)
0.23 parts by weight was charged into a kneader and kneaded for 2 hours while maintaining the material temperature at 70 ° C. by circulation of warm water. The kneaded material was cooled to room temperature to obtain a clay-like molding material.

Next, the molding material was put into a thermosetting resin injection molding machine equipped with a 120 × 120 × 20 mm dish-shaped lamp cover molding die, and injection molding was performed at a mold temperature of 135 ° C. A lamp cover was prepared. The surface hardness of the obtained lamp cover was 4H, and the total light transmittance was 92.5%.
Met. When the weather resistance was evaluated, 100
After 0 hour, the total light transmittance was 91.8%, and no coloring or other change in appearance was observed.

Claims (2)

[Claims] 1. A lamp cover (A) 1 obtained by polymerizing and curing a resin composition containing the following components (A) to (C):
At least two radically polymerizable double bonds in the molecule
30 to 60 parts by weight of an unsaturated monomer mixture mainly composed of unsaturated monomers, and (B) a polymer of an unsaturated monomer mainly composed of methyl methacrylate,
40 to 70 parts by weight of a resin particle composed of a partially crosslinked resin particle of 0% to 80% by weight of a non-crosslinked resin particle and (C) a radical polymerization initiator in total of components (A) and (B). 0.1 to 5 parts by weight based on 100 parts by weight. 2. A resin composition containing the following components (A) to (C) is heated to obtain a soft molding material, and the molding material is subjected to any one of injection molding, compression molding and transfer molding. Cover (A) 1 formed by molding, polymerization and curing
At least two radically polymerizable double bonds in the molecule
30 to 60 parts by weight of an unsaturated monomer mixture mainly composed of unsaturated monomers, and (B) a polymer of an unsaturated monomer mainly composed of methyl methacrylate,
40 to 70 parts by weight of a resin particle composed of a partially crosslinked resin particle of 0% to 80% by weight and a non-crosslinked resin particle of 0 to 80% by weight, and (C) a radical polymerization initiator as components (A) and (B) 0.1 to 5 parts by weight with respect to 100 parts by weight in total.