JP2000322916A - Illumination cover molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide good light diffusibility, chemical resistance, and saw cutting machinability by using a resin composition containing polystyrene-based resin, polyolefin-based resin, petroleum resin, polymer containing soluble parameter in a specific range, no polystyrene-based resin, no polyolefin-based resin, and no petroleum resin, respectively by specific wt.%. SOLUTION: As this illumination cover molding, a resin composition containing component (A)-component (D) is used. The component (A) is 1-96 wt.% polystyrene-based resin, the component (B) is 96-1 wt.% polyolefin-based resin, the component (C) is 0-20 wt.% petroleum resin, and the component (D) is 3-25 wt.% polymer (containing no polystyrene-based resin, no polyolefin-based resin, and no petroleum resin) with 8.40-8.70 soluble parameter(SP). In this illumination cover molding, the polyolefin-based resin component is high-density polyethylene with density higher than 0.95 g/cm3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an illumination cover molded product of a type which is milky white and diffuses light to reduce light from a light source such as a fluorescent lamp. More particularly, the present invention relates to a molded article of a lighting cover having excellent low specific gravity, light diffusion property, chemical resistance, impact strength, saw cutting property, and molding cycle.

[0002]

2. Description of the Related Art In a lighting apparatus, a glass, an acrylic resin such as polymethyl methacrylate, or a polystyrene resin has conventionally been used for a lighting cover mounted so as to cover a front surface of a lighting lamp. For light-covered molded products that are milky white and diffuse light to reduce light from light sources such as fluorescent lamps, use a transparent acrylic resin or polystyrene resin by adding a light diffusing agent to make it cloudy. I was While these materials are excellent in rigidity, they have the disadvantage that they are brittle and easily broken. Glass has a problem that it is heavy because it has very high safety and specific gravity at the time of breakage due to impact or the like. In addition, acrylic resin has a problem that a molding cycle is long at the time of molding a lighting cover, and also has a problem that, due to its high specific gravity, a molded product having the same volume becomes heavy and difficult to handle, and the cost of raw materials increases. . Polystyrene resins have a problem of poor chemical resistance.

[0003]

SUMMARY OF THE INVENTION In view of these circumstances, the problem to be solved by the present invention is low specific gravity, excellent light diffusion without adding a light diffusing agent, chemical resistance and impact strength. Another object of the present invention is to provide a milky white type lighting cover molded product which is excellent in saw cutting performance and molding cycle.

[0004]

Means for Solving the Problems The present inventors have made intensive studies to solve the above-mentioned problems, and have reached the present invention. That is, the present invention is as follows.

(1) A lighting cover molded article using a resin composition containing the following components (A) to (D). (A): 1 to 96% by weight of a polystyrene resin (B): 96 to 1% by weight of a polyolefin resin (C): 0 to 20% by weight of a petroleum resin (D): A solubility parameter (SP) of 8.40 to 8.7
0 to 3% to 25% by weight of one or more polymers (excluding the above (A), (B) and (C)) (2) Component (B) has a density of 0.95 g / cm A lighting cover molded article using the resin composition according to (1), which is ³ or more high-density polyethylene.

(3) Component (D) is an unsaturated carboxylic acid,
The resin composition according to any one of (1) and (2), wherein the resin composition is at least one polymer selected from a copolymer of ethylene and at least one vinyl monomer among unsaturated carboxylic acid esters or vinyl acetate, and a styrene copolymer. Lighting cover moldings using objects.

(4) A molded article of a lighting cover using the resin composition according to any one of (1) to (3), wherein the component (C) is an ethylene-unsaturated carboxylic acid ester copolymer.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.

The lighting cover in the present invention is a lighting fixture which is mounted so as to cover the front of the lighting lamp, and which is milky white and diffuses light, thereby reducing light from a light source such as a fluorescent lamp. It is a type of lighting cover.

As an index of light diffusivity, JIS K710 is used.
The total light transmittance and haze determined by the measurement specified in 5 are often used. The higher the total light transmittance, the higher the transparency and the light from the light source reaches the human eye, and the lower the total light transmittance, the lower the transparency and the light from the light source is softened. However, if it is too low, the surroundings become too dark and lose the original purpose of the lighting fixture. The preferred total light transmittance depends on the application, but is believed to be in the approximate range of 20-60%. The haze indicates the degree of opacity, also called the haze value. The higher the haze, the more opaque the lower the haze. The preferred value of haze also varies depending on the application, but is considered to be in the approximate range of 70-95%.

As the polystyrene resin (A) used in the present invention, so-called general-purpose polystyrene resins, rubber-modified polystyrene resins, and mixtures thereof can be used. From the viewpoint of impact strength, a rubber-modified polystyrene resin is preferable. It does not include crystalline syndiotactic polystyrene recently marketed.

Here, the general-purpose polystyrene resin is G
PPS (general purpose poly)
This is also called styrene, and is usually a styrene homopolymer. The rubber-modified polystyrene-based resin is obtained by polymerizing a styrene-based monomer in the presence of a rubber-like polymer, and is made of impact-resistant polystyrene (HIPS =
It is also referred to as high impact polystyrene. Further, as the molecular structure of the polystyrene resin, any of a linear structure and a branched structure may be used.

As the styrene monomer, styrene is generally used, but alkyl-substituted styrene such as α-methylstyrene, o-methylstyrene, m-methylstyrene and p-methylstyrene can also be used.

As the rubbery polymer, polybutadiene,
Polyisoprene, styrene-butadiene copolymer and the like can be used.

The polyolefin resin (B) used in the present invention includes olefin homopolymers, olefin copolymers copolymerized using copolymerizable olefins, and mixtures thereof. And copolymers other than olefins.

As these specific resins, for example,
So-called high density polyethylene (HDPE), low density polyethylene (LDPE), linear low density polyethylene (L
Propylene polymers such as polyethylene, polypropylene, propylene-ethylene block copolymer, propylene-ethylene random copolymer such as LDPE),
And mixtures thereof. Among them, high-density polyethylene is particularly preferable, and the density is 0.95.
g / cm ³ or more is preferable.

The petroleum resin (C) used in the present invention includes terpene resins and their hydrogenated products, alicyclic hydrocarbon resins and their hydrogenated products, DCPD resins, polyterpenes and mixtures thereof. Yes, for example 1269
5 Chemical Products (Chemical Daily) pp. 944-945, 9
Those described on page 35 and the like are also used. The terpene-based resin is a copolymer of terpene and aromatic vinyl hydrocarbon or a copolymer thereof, and a resin obtained by hydrogenating the copolymer. Styrene, α as the aromatic vinyl hydrocarbon
-Methylstyrene, vinyltoluene and the like are used. As the terpene, α-pinene, β-pinene, limonene, a mixture thereof and the like can be used. The hydrogenation rate is not particularly limited, but is preferably 10% or more, preferably 20% or more. Alicyclic hydrocarbon resins are:
It can be obtained by hydrogenating C9 petroleum resin or it. Among these petroleum resins, those having a refractive index of 1.55 or more are preferable.

The solubility parameter (SP) of the component (D) of the present invention is from 8.40 to 8.70, preferably from 8.40 to 8.40.
When it is 8.65 and is smaller than 8.40 or larger than 8.70, the impact strength and the like of the molded product are inferior.

Here, the solubility parameter is defined as Hil
It defines the attractive force between molecules according to the debrand-Scatchard theory. A detailed explanation is given in a general textbook of polymer science, for example, “Polymer Blend, Saburo Akiyama et al.
5 to 144 (1991). However, the solubility parameter includes a method obtained by experiments such as a viscosity method and a degree of swelling method and a method obtained by calculation from a molecular structure. Is slightly different.
The method of calculating from the molecular structure proposed by Mall was used here. This method and theory is described in "Journal of Applied Chemistry".
al of Applied Chemistry),
3, 71-80 (1953) ", whereby the solubility parameter was calculated using the following equation (Equation 1).

[0020]

(Equation 1) Fi represents the molar attraction force of a constituent group such as an atom or atomic group constituting the molecule, a bond type, V represents the molar volume, and ρ represents the density. M indicates a molecular weight, and in the case of a polymer, indicates a molecular weight of a monomer unit. As the value of Fi, the value of Small described in the above two documents was used. Regarding ρ, ΔFi or M of the copolymer, assuming that additivity is satisfied, calculate the sum of values obtained by multiplying the numerical value of ρ, ΔFi or M of each homopolymer of the monomer units constituting the copolymer by the molar fraction of the monomer units. Used.

As the polymer having a solubility parameter (SP) of the component (D) of 8.40 to 8.70 used in the present invention, one of unsaturated carboxylic acid, unsaturated carboxylic acid ester and vinyl acetate is used. Copolymers composed of the above vinyl monomer and ethylene, styrene copolymers and the like are mentioned. Examples include ethylene-unsaturated carboxylic acid copolymers, ethylene-unsaturated carboxylic acid ester copolymers, ethylene-vinyl acetate copolymers, ethylene-unsaturated carboxylic acid ester-vinyl acetate terpolymers, ethylene and two or more unsaturated Examples include a multi-component copolymer composed of a carboxylic acid ester, a styrene-butadiene copolymer, a styrene-isoprene copolymer, a hydrogenated product of a styrene-butadiene copolymer, and a hydrogenated product of a styrene-isoprene copolymer.

Specific examples of the unsaturated carboxylic acid include acrylic acid and methacrylic acid. Specific examples of the unsaturated carboxylic acid ester include ethyl acrylate, methyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, glycidyl acrylate, methyl methacrylate, ethyl methacrylate,
Examples thereof include 2-ethylhexyl methacrylate, stearyl methacrylate, and glycidyl methacrylate.

Preferred examples of the copolymer comprising ethylene and at least one vinyl monomer selected from unsaturated carboxylic acids, unsaturated carboxylic esters or vinyl acetate used in the present invention include ethylene-acrylic acid copolymer and ethylene-methacrylic acid. Copolymer, ethylene-methyl methacrylate copolymer, ethylene-ethyl methacrylate copolymer, ethylene-ethyl acrylate copolymer, ethylene-methyl acrylate copolymer, ethylene-vinyl acetate copolymer, ethylene-methyl acrylate-glycidyl methacrylate copolymer, ethylene-methyl methacrylate-glycidyl methacrylate copolymer, And ethylene-vinyl acetate-glycidyl methacrylate copolymer.

The proportion of the above-mentioned vinyl monomer and ethylene in the copolymer is determined by a solubility parameter (SP) of 8.40 to
It can be determined appropriately within a range that gives a copolymer of 8.70, preferably 8.40 to 8.65. The ratio of the vinyl monomer in the copolymer of the vinyl monomer is 5 to 5.
It is preferably 60% by weight, more preferably 10 to 50% by weight. Further, there is no particular limitation on the bonding mode (for example, random, block, or alternating) between the vinyl monomer and ethylene in the copolymer. The melt flow rate of the copolymer is not particularly limited (according to JIS, K7210, at a temperature of 190 ° C. and a load of 2.16 kgf), but is preferably about 1 to 500 g / 10 minutes.

Specific examples of the styrene copolymer include a styrene-butadiene copolymer, a styrene-isoprene copolymer, a hydrogenated product of a styrene-butadiene copolymer, a hydrogenated product of a styrene-isoprene copolymer, and the like.

As the styrene monomer, alkyl-substituted styrenes such as α-methylstyrene, o-methylstyrene and m-methylstyrene, and mixtures thereof can also be used.

The proportion of the styrene monomer and its comonomer in the styrene copolymer is determined by the solubility parameter (S
P) It can be determined appropriately within a range that gives a polymer of 8.40 to 8.70. The proportion of the comonomer in the styrenic copolymer is preferably from 20 to 80% by weight. More preferably, the content is 35 to 70% by weight. Further, there is no limitation on the bonding mode (for example, random, block, alternate) of the styrenic monomer and comonomer in the copolymer.

In the present invention, (D) a polymer having a solubility parameter (SP) of 8.40 to 8.70 is the same as the above-described (A) polystyrene resin, (B) polyolefin resin and (C) petroleum resin. Not included.

In the present invention, the proportion of the components (A) to (D) used is (A) 1 to 96% by weight of a polystyrene resin,
(B) 96 to 1% by weight of a polyolefin-based resin, (C) 0 to 20% by weight, preferably 5 to 10% by weight, and (D) solubility parameter (SP) of 8.40 to 8.
70 to 3% to 25% by weight of the polymer, preferably 3 to 1%.
0% by weight.

By changing the use ratio of the components (A) to (D) within the above range, the light diffusing property can be freely adjusted without adding an inorganic light diffusing agent such as calcium carbonate or barium sulfate. Can be adjusted.

(A) If the amount of polystyrene resin is too small, the rigidity is insufficient, while if it is too large, the chemical resistance is poor.
(B) If the amount of the polyolefin resin is too small, the chemical resistance is poor, while if it is too large, the rigidity is insufficient. (C) When the amount of the petroleum resin is too small, the transparency is poor. On the other hand, when the amount is too large, the rigidity is insufficient. (D) solubility parameter (SP) is 8.
If the amount of the polymer is less than 40 to 8.70, the compatibility between (A) and (B) is low, and the impact strength and the like are poor. On the other hand, if the amount is too large, the rigidity is poor.

In order to obtain the lighting cover of the present invention, a method such as injection molding into a molded article having a desired shape or molding into a sheet and then vacuum-pressure forming into a desired shape can be used. When molding, a predetermined amount of each component is previously dry-blended with a mixing device such as a Henschel mixer or a tumbler, or a single-screw or twin-screw extruder, or a kneader such as a Banbury mixer is used.
The mixture is sufficiently heated and kneaded at a temperature of ２６０260 ° C., and then granulated to pelletize the composition. If necessary, additives such as an antioxidant, a heat stabilizer, an ultraviolet absorber, a light stabilizer, a lubricant, a flame retardant, an antistatic agent, and a mineral oil can be used.

The molded article is a lighting cover and is exposed to light for a long time. To prevent yellowing and deterioration of mechanical properties due to the irradiation, an ultraviolet absorber and a light fasting agent may be added. In general, it is known that a benzotriazole-based or benzophenone-based compound is effective as an ultraviolet absorber. It is generally known that benzotriazoles have a high synergistic effect when used in combination with hindered amine light stabilizers.

The injection molded product of the lighting cover of the present invention can be obtained by using a generally used injection molding machine.

The resin sheet to be used as the lighting cover of the present invention can be obtained by a method in which the resin sheet is melted using a generally used extruder and then extruded from a T-die. As a method of vacuum-pressure forming a resin sheet into the shape of the lighting cover of the present invention, using a commonly used vacuum-pressure forming machine, after heating the sheet, press it against a mold and vacuum or pressurize, then air for several seconds Known techniques such as a method of cooling by spraying or the like can be used. If necessary, unnecessary portions are removed by punching with a punching blade or the like or cutting with a saw.

[0036]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, which should not be construed as limiting the present invention. The measurement and evaluation methods are as follows. Items other than those described below were performed as described above.

(1) Transparency Total light transmittance and haze were measured according to JIS, K7105.

(2) Chemical Resistance The molded article was pressed against a 1/4 elliptical jig and fixed, a reagent was applied to the surface, and left at 23 ° C. for 24 hours. Observing the location where the crack occurred, the value of the distortion of the molded article at the tip where the crack occurred was calculated, and the critical strain was calculated. The case where the critical strain value was 0.3% or more was evaluated as ○, and the case where the critical strain value was lower than 0.3% was evaluated as ×.

(3) Specific gravity Measured by the method A according to JIS, K7112.

(4) Flexural modulus (rigidity) Measured according to JIS, K7203. A test piece was cut out in the sheet flow direction (MD) and measured.

(5) Impact Strength In accordance with ASTM, D3763, a 7.5 kg load striker equipped with a load cell was dropped from a height of 80 cm and the energy required to break the striker was measured. A graphic impact tester manufactured by Toyo Seiki was used.

(6) Saw cutting properties When three sheets are stacked and sawed into a 45 cm square size with a saw, even one sheet that cannot be cut to the desired size and is broken is marked X. ○

(7) Forming cycle After the sheet is heated with a heater at 230 ° C. for 60 seconds, it is compressed and adhered to a mold for a lighting cover. The molded article was taken out from the molded article after taking out a period of time that does not cause distortion or deformation, and then the molded article was taken out. The molding cycle was determined by subtracting 60 seconds of heating from the entire molding cycle.

Examples 1 to 18 and Comparative Examples 1 and 2 The components shown in Table 1 were melted at 230 ° C. in a single-screw extruder having a cylinder diameter of 115 mmφ and extruded from a T-die to obtain a sample having a width of 670 mm and a thickness of about 2 mm. A resin sheet was obtained.
The physical properties of this sheet were evaluated. This sheet was cut into a 45 cm square size with a saw and cutability was examined. The cut sheet was heated and pressure-formed to obtain a molded product for a 30 W fluorescent lamp. Further, as Comparative Example 1, a sheet of trade name Acrylite manufactured by Mitsubishi Rayon Co., Ltd., in which a light diffusing agent was added to PMMA, was used to examine the sheet properties, saw cutting properties, and molding cycle in the same manner as the above sheet. Table 3 (1)-
This is shown in (4).

The components (A) to (D) used are as follows.

Component (A) A1: Polystyrene resin (H available from Nippon Polystyrene Co., Ltd.)
IPS, trade name Nippon Polysty H640, MFR = 2.8
g / 10 min, density 1.04 g / cm ³ , average gel particle size 2.2 μm, MFR measurement conditions: 200 ° C., load 5 kg
f) A2: Polystyrene resin (H made by Nippon Polystyrene Co., Ltd.)
IPS, trade name Nippon Polysty H655, MFR = 2.7
g / 10 min, density 1.04 g / cm ³ , average gel particle diameter 0.2 μm, MFR measurement conditions: 200 ° C., load 5 kg
f) Component (B) B1: Polypropylene (manufactured by Sumitomo Chemical Co., Ltd., trade name: Noblen AD571, MFR = 0.5 g / 10 min, density: 0.90 g / cm ³ , MFR measurement conditions: 230 ° C., load: 2. 16 kgf) B2: Polyethylene (manufactured by Mitsui Chemicals, Inc., trade name HIZEX 5202B, MFR = 0.33, density 0.964)
g / cm ³ , MFR measurement conditions: 190 ° C., load 2.16
kgf) (C) component C1: hydrogenated terpene resin (manufactured by Yashara Chemical Co., Ltd.)
C2: hydrogenated terpene resin (manufactured by Yashara Chemical Co., Ltd.)
Product name CLEARON M-115, refractive index 1.542 (20
° C)) C3: alicyclic saturated hydrocarbon resin (Arakawa Chemical Industry Co., Ltd.)
Manufactured by Alcon M-135, with a refractive index of 1.552 (2
(0 ° C.)) (D) Component: Table 2 shows the result of calculating the solubility parameter (SP) of the component (D) by the above (Equation 1). D1: ethylene-methyl methacrylate copolymer (manufactured by Sumitomo Chemical Co., Ltd., trade name: ACLIFT CM5019,
Methyl methacrylate content 30% by weight, MFR = 20 g
/ 10 min, MFR measurement conditions: 190 ° C., load 2.16 k
gf) D2: styrene-butadiene copolymer (JSR Corporation)
D3: ethylene-methyl methacrylate copolymer (manufactured by Sumitomo Chemical Co., Ltd., trade name: ACLIFT WM403, methyl methacrylate content 38% by weight, MFR = 15 g /
10 minutes, MFR measurement conditions: 190 ° C, load 2.16 kg
f) D4: ethylene-methyl acrylate copolymer (manufactured by Sumitomo Chemical Co., Ltd., trade name: CG4002, methyl acrylate content: 30% by weight, MFR = 7 g / 10 min, MFR)
(Measurement conditions: 190 ° C., load 2.16 kgf) The following can be understood from the results. In Tables 3 (1) to (4), the compositions of Examples 1 to 18 of the present invention have a low specific gravity, and are excellent in light diffusion, impact strength, saw cutting properties, and molding cycle. Comparative Example 1 has high rigidity, but has a high specific gravity, is brittle, has low impact strength, and is inferior in saw cutting performance and molding cycle. Chemical resistance and heat resistance are almost the same. Comparative Example 2 is inferior in chemical resistance.

[0047]

[Table 1]

[0048]

[Table 2]

[0049]

[Table 3]

[0050]

[Table 4]

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat (Reference) C08L 23:04 33:06) (72) Inventor Takahiro Ishi 1-6-6 Takasago, Takaishi City, Osaka Japan Polystyrene Inside (72) Inventor Akio Uemura 1-6 Takasago, Takaishi-shi, Osaka Japan Polystyrene Co., Ltd. (72) Inventor Masato Takaku 1-6-6 Takasago, Takaishi-shi, Osaka F-term in Polystyrene Co., Ltd. Reference) 4J002 BA013 BB01X BB064 BB074 BB084 BC024 BC03W GP00

Claims (4)

[Claims] 1. A lighting cover molded article using a resin composition containing the following components (A) to (D). (A): polystyrene resin, 1 to 96 wt% (B): polyolefin resin, 96 to 1 wt% (C): petroleum resin, 0 to 20 wt% (D): solubility parameter (SP) is 8 .40-8.7
0 to 3 or 25% by weight of one or more polymers (but not including the above (A), (B) and (C)) 2. A molded article of a lighting cover using the resin composition according to claim 1, wherein the component (B) is a high-density polyethylene having a density of 0.95 g / cm ³ or more. 3. The component (D) is at least one polymer selected from a copolymer of ethylene and at least one vinyl monomer of unsaturated carboxylic acid, unsaturated carboxylic acid ester or vinyl acetate, and a styrene copolymer. An illumination cover molded article using the resin composition according to claim 1. 4. A molded article of a lighting cover using the resin composition according to claim 1, wherein the component (D) is an ethylene-unsaturated carboxylic acid ester copolymer.