JPH02306501A - Lamp cover for lighting fixture - Google Patents

Abstract

PURPOSE:To enhance the transparency, heat resistance, anti-weatherability, and lightweight construction by using thermoplastic polymer containing glutaric imide unit having a certain weight. CONSTITUTION:A film 2 of bridged hardening resin is provided over the external surface of a base member 1 for lamp cover made of thermoplastic polymer. The physical properties of the cover and hardened film are such that the content of glutaric imide structure unit is over 60wt.%, amide segment amount in the polymer is below 2wt.%, ferric content of the polymer is below 20ppm, the YI value measured by a color difference meter is below 3, and the total photo beam penetration coefficient is over 87%.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a plastic lamp cover used for lamps such as bathroom white lamps and mercury lamps.

[Prior Art] White bathroom lamps and mercury lamps used outdoors are usually fitted with lamp covers made of inorganic glass in order to maintain light transmission. However, although inorganic glass has excellent heat resistance, transparency, and weather resistance, it has drawbacks such as being easily broken and being heavy. Recently, some plastic lamp covers have been developed and are not put into practical use. There is.

By the way, acrylic polymers such as methyl methacrylate polymers are examples of thermoplastic polymers with excellent transparency and weather resistance, but lamp covers made of these polymers have low heat resistance. has the disadvantage that it is easily deformed by the heat generated when the lamp is lit. In addition, polycarbonate is a thermoplastic polymer that has relatively good transparency and weather resistance, and has a high heat resistance.Considerations such as making it into a shape that does not get hot or taking special measures for heat insulation are necessary. It was said that

[Problem to be solved by the invention] Due to the above situation, recently, materials with excellent transparency and weather resistance have been developed.
Thermoplastic polymers with high temperature resistance have been developed.
Moreover, lamp covers using such polymers have been proposed. (Refer to JP-A No. 60-136791 and JP-A No. 63-234002) The present invention is based on the premise of using such an improved thermoplastic polymer to create a product that is even more excellent as a lamp cover for lighting equipment. It was created to provide the following.

[Means for Solving the Problems] That is, the gist of the present invention is a lamp cover molded from a thermoplastic polymer containing glutarimide units, which satisfies the following requirements a' to e. Lamp cover a for a lamp, characterized in that the content of glutarimide structural unit is 60% by weight or more, the amount of amide segment in the b0 polymer is 2% by weight or less, the content of iron in the C1 polymer is 20ppm or less, 61 The YI value measured with a color difference meter is 3 or less, e, and the total light transmittance measured with an integrating sphere haze meter is 87% or more.

The present invention will be explained in more detail below.

The lamp cover of the present invention is molded from a thermoplastic polymer containing glutarimide units, and this polymer includes a) a glutarimide structural unit content of 60% or more;
As an upper limit, the content usually needs to be less than 95%. The content of this glutarimide structural unit is calculated from the nitrogen content determined by elemental analysis, and if this content is less than 60%, the heat resistance is insufficient.

Specific examples of the glutarimide unit include N-methylmethacrylimide or methacrylimide having a cyclohexyl, phenyl, hydrogen atom, etc. as a substituent on the nitrogen atom forming the imide ring; specific examples include N-cy, kilohexyl; Examples include methacrylimide, N-phenylmethacrylimide, and methacrylimide.

Specific examples of components other than glutarimide units include:
Mention may be made of styrene, α-methylstyrene, acrylonitrile, methyl methacrylate and methacrylic acid esters or acrylic acid alkyl esters.

Even if the polymer obtained from the above composition is used as a lamp cover, in order to further improve the color banding property, b
The amount of amide segment in one polymer needs to be 2% by weight or less. The amount of this amide segment is determined by FT-NMR
It is determined by a spectrometer, and this quantity is 2
If it exceeds % by weight, it becomes yellowish, which is not preferable.

In addition, in order to further improve the colorability, it is necessary to suppress the iron content in the C91 polymer to 20 ppm or less, but if this content exceeds 20 ppm, it is disadvantageous that it will become colored in a high temperature atmosphere. occurs.

The lamp cover must efficiently transmit the light from the internal light source, and for this purpose the Y
It is desirable that the I value is 3 or less, and the e and total light transmittance measured with an integrating sphere haze meter are 87 or more. Note that the latter total light transmittance is a value measured in accordance with ASTM-D-1003.

The lamp cover of the present invention can be obtained by injection molding a thermoplastic polymer molding material having the above-mentioned performance, but the shape may be any shape depending on the purpose of use and design. I can do it.

Further, since the lamp cover may be required to have surface scratch resistance, it is preferable to form a crosslinked curable resin film on at least one surface, if necessary. Examples of this coating include those made of an acrylic polyfunctional compound and a silicone compound.

Hereinafter, the present invention will be described with reference to the drawings. FIG. 1 shows the entire lamp cover, and FIGS. 2 and 3 are enlarged views of the main parts thereof. In the figure, (1) is the base material of the lamp cover formed from a thermoplastic polymer, and (2) in Figure 3 is the coating of cross-linked curable resin provided on the outer surface of the base material. .

[Example] Hereinafter, specific examples of the present invention will be described. Note that "1 part" and "r%" used in the examples are all parts by weight and weight %.

In the following examples, the physical properties of the lamp cover were measured and the cured film was evaluated by the following method.

(1) The infrared absorption spectrum was measured by the KBr disk method using an infrared spectrophotometer (Model 285 manufactured by Hitachi, Ltd.).

(2) Heat distortion temperature was measured based on ASTM D-648.

(3) The total light transmittance of the molded product was measured using an integrating sphere haze meter.

(4) The imidization rate was determined as follows.

The nitrogen content of the polymer was determined by elemental analysis (measuring device CHN coder, MT-3, manufactured by Yanagimoto Seisakusho Co., Ltd.), and the imidization rate (% by weight) was calculated.

(5) The yellowness index (YI value) was determined using a color difference meter color analyzer (model 307 manufactured by Hitachi, Ltd.) according to JIS standard K.
-7103.

,Y Calculated from X, Y% Z stimulation value.

(6) Molecular weight measurement by GPC was carried out as described in "Gel Chromatography (Basic Edition)" published by Kodansha, pages 97 to 122.

Column) A calibration curve was prepared using IGs-20,50 (manufactured by Shimabara Seisakusho Co., Ltd.) and standard polystyrene (manufactured by Frerasya Chemical Co., Ltd.), and eluted with a tetrahydrofuran solution.

The elution curve obtained using the sample solution was divided into equal parts, the height at the division points was measured, and the MW was determined by the following formula.

MW −Qm I [old xMi(p) )/QpΣold However, Hi is the height of the elution curve at the dividing point, Mi(p
) is the molecular weight of standard polystyrene at division point i, Qm
s Qp is the Q factor of the polymer and polystyrene, which were taken as 40 and 41, respectively.

(7) The iron content in the polymer was determined by weighing 5 g of the polymer and measuring it with a light emission spectrometer (manufactured by Nippon Jarrell Ash Co., Ltd.).

(8) Measurement of the amount of amide segment in the polymer is carried out using FT-
NMR' (Ctrometer (JNM-GSX-400)
(manufactured by JEOL Ltd.), using TMS internal standards, d6-
Dimethyl sulfoxide 5% by weight, constant at 120°C, the amount of amide segment based on the polymer was expressed in weight%.

(9) Abrasion resistance (steel wool scratch resistance) evaluation #0
00 Steel Cool ("Bonstar" manufactured by Nippon Steel Wool Co., Ltd.) was attached to a circular pad with a diameter of 25 mm, and the pad was placed on the surface of the sample held on a reciprocating abrasion tester stand and subjected to 50 reciprocations under a load of 1000 g. I got scratched. This sample was washed using a neutral detergent, and the haze value was measured using a haze meter. Steel wool scratch resistance is (haze value after scratching -
Haze value before abrasion).

(10) Evaluation of adhesion Make 11 vertical and horizontal razor wires of 1.5 mm on the sample surface.
Make 100 squares by making scratches at intervals, press a 25 mm wide piece of cellophane tape (manufactured by Chiban Co., Ltd.) onto the squares, and peel it upward sharply. The evaluation of this result is expressed as the number of remaining squares/the total number of squares (100).

(11) Evaluation of weather resistance Sun Shine Quezaometer (Suga test time, 1
Exposure was made for 500 hours. This sample was observed for the following appearance items.

Appearance abnormalities such as cracks, crazing, delamination, haze, and yellowish yellow in the film were observed, and the rating was rated O when these abnormalities could not be observed.

Example 1 65 parts of methyl methacrylate, 30 parts of toluene, 5 parts of methanol, 0.08 part of 11°-azobiscyclohexanecarbonitrile, 0.0325 part of 2.2-azobisisobutyronitrile, 0.0 parts of n-octylmercaptan. A polymerization feed liquid consisting of 15 parts was continuously fed to a nitrogen-feed countercurrent contact tower (nitrogen: feed liquid≠1:100 weight ratio), and the amount of dissolved oxygen in the raw material feed liquid was adjusted to 0.6 ppm. , using a 0.1 μm Fluorobor (manufactured by Sumitomo Electric Industries, Ltd.), fine particles of 0.5 to 25 μm in the feed liquid were
0 particles/ml, high purity feed liquid, internal volume 2
A 0 L first stirred tank reactor was continuously fed at a rate of 4 L/Hr. The polymerization conversion rate immediately after leaving the reactor was measured and was 55%. This polymerization liquid was transferred to a second multi-tubular heat exchange type reactor (inner diameter 12.7 m).
1,000 mm in length and composed of 100 O wood), and polymerization was carried out at a temperature of 140° C. to a polymerization conversion rate of 95%. Furthermore, this polymerization liquid was mixed with the following imidized substance and supplied to the stirred tank type reactor in the third reaction zone.

On the other hand, a mixed solvent (toluene:methanol = -i: weight ratio) for dissolving and diluting the imidized substance (methylamine) was used in the same manner as in the raw material feed solution treatment to reduce the amount of dissolved oxygen to 0.6.
ppm, then added methylamine to make 40% by weight, filtered through 0.1 μm Fluorobore, and made 1.2 L/l (r
The polymer solution was mixed with the polymerization solution and supplied to the third reaction zone. The imidized substance and the polymerization solution were mixed at 100° C. for 5 minutes, and after thorough mixing using an in-line mixer, the mixture was supplied to the third reaction zone. The mixed liquid of the polymerization liquid and the imidization substance is transferred to the third reaction zone (inner volume: 15 L, temperature: 23
After the imidization reaction is carried out by supplying the reaction liquid from the lower part of the stirring type reactor (0°C), the reaction liquid leaving this reaction zone has an internal volume of 3
L was supplied to a stirred tank type reactor serving as a ripening reaction zone at a temperature of 230°C. The reaction liquid exiting these reaction zones is flushed from the nozzle opening into a tank regulated under a reduced pressure of 100 torr, and the flushed polymer is washed with a screw (the shaft is Hardness steel material) and hold the barrel by stainless steel 3
The mixture was shaped into a strand using a 0φ double vent twin-screw extruder and made into pellets.

Extruder with double vent has vent part vacuum degree SmmHg,
The temperature was 260°C, the metal ring part temperature i was 270°C, and the die part temperature was 255°C. When the infrared spectrum of the obtained pellet-like polymer was measured, the wave number was 1720 CI-',
Absorption characteristic of methacrylimide was observed at 1663 cm-' and 750 cm-', confirming that the polymer was a methacrylimide-containing polymer.

Using the polymer pellet obtained as above,
The lamp cover was manufactured by injection molding.

The injection molding machine used was 1575E manufactured by Toshiba Machine Co., Ltd., and the mold temperature was 130° C. and the injection pressure was 1350 Kg/cm.

A part of the obtained lamp lens was cut and its physical properties were measured as follows.

Total light transmittance (%) 93 Heat distortion temperature ('C) 145
Imidization rate (%) 8 Imidation rate distribution width (%) 1.7 YI value 1.0 Amount of amide segment in polymer (%) l, 1 Residual monomer (methyl methacrylate) in polymer, (ppm ) 10
0GPC measurement molecular weight (Mw) 8500
0 Iron content in polymer (ppm) 1. .

As described above, a lamp cover made of a methacrylimide-containing polymer having a high degree of transparency, excellent heat resistance, and excellent yellowness and yellowing was obtained.

Example 2 Two types of cured films were formed on the lamp cover obtained in Example 1.

"Curing liquid composition 1" - 39 parts of dipentaerythritol hexaacrylate - 26 parts of dipentaerythritol pentaacrylate - 35 parts of tetrabodrofurfuryl acrylate - 2
-10 parts of hydroxy 4-n octoxybenzophenone, 4 parts of benzoin iso-propyl ether, and 7 parts of isopropyl alcohol as an organic solvent.
Add 5 parts and 75 parts of toluene to make a hardening liquid.

"Curing liquid composition 2" - 33 parts of dipentaerythritol hexaacrylate - esterification reaction product synthesized from dipentaerythritol pentaacrylate (molar ratio 2/1/4.4)
10 parts, 35 parts of tetrahydrofurfuryl acrylate, 2.4 parts, 10 parts of dihydroxybenzophenone, benzoin ethyl ether
4 parts To the above composition, 75 parts of organic solvent isopropyl alcohol and 75 parts of n-butyl acetate were added to prepare a curing liquid.

Coat the lamp cover with the above two types of curing liquid,
After leaving to stand at room temperature for 5 minutes to evaporate the organic solvent, it was irradiated with a high-pressure mercury lamp ("I-Graphic" 10B-L21J) to harden.

When the cured film of the obtained lamp cover was evaluated, the results shown in Table 1 were obtained.

Table 1 [Effects of the Invention] Since the present invention has the configuration as detailed above, it is possible to provide a lamp cover for a lamp that has high transparency, high heat resistance, excellent weather resistance, and is lightweight. There are vine benefits to offer.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and FIG. 1 is a perspective view of a lamp cover for a lamp, and FIGS. 2 and 3 are partially enlarged sectional views. (1)・・・Base material (2)・・・Coating patent applicant, Patent attorney representing Mitsubishi Rayon Co., Ltd.
Satoshi Yoshizawa Fuizumi 7 figure tail 2 figure tail 3I! I

Claims (1)

[Scope of Claims] 1. A lamp cover for a lamp, characterized in that it is molded from a thermoplastic polymer containing glutarimide units, and has the following requirements a to e: The imide structural unit content is 60% by weight or more, b. The amount of amide segment in the polymer is 2% by weight or less, c. The iron content in the polymer is 20 ppm or less, d. The YI value measured with a color difference meter is 3. Below, e, the total light transmittance measured with an integrating sphere haze meter is 8
More than 7%.