JPH107818A - Polyester resin sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prepare a sheet and a molding made of a polyester resin having a high light diffusion effect and optical transmission properties and not causing whitening due to crystallization even when a light diffusing agent is blended. SOLUTION: This polyester resin sheet consists of 98-99.9wt.% polyethylene naphthalate resin containing 5-25wt.% naphthalenedicarboxylic acid component in the acid component and 0.1-2wt.% light diffusing agent, and at least one side thereof is subjected to matte finishing so that the whole light transmittance is 20-90% and the diffuse transmittance is 20-70%. The light diffusing agent is selected from calcium carbonate, titanium oxide, aluminium hydroxide, silicate, silicon dioxide, zinc sulfide, silicone rubber, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyester resin sheet having a light diffusing property suitable for a component of a lighting device such as a cover of a lighting device and a lighting window. That is, the sheet and the molded product thereof uniformly diffuse light emitted from a light source such as a fluorescent lamp, a light bulb, a lamp, and the like, so that the shape of the light source is not directly seen, and at the same time, the light transmittance is good. Therefore, efficient lighting is possible. In addition, since the material itself is excellent in moldability, handleability, and heat resistance, it is possible to expand the degree of freedom of lighting fixture design and the field of use, and to reduce costs in both materials and processes. In addition, the polyester resin used is recyclable and emits no harmful gases or remarkable black smoke during combustion. ing. As described above, the present invention provides a polyester resin sheet and a molded article which are excellent in heat resistance, light diffusion property, moldability, environmental suitability at the time of disposal, and the like.

[0002]

2. Description of the Related Art Heretofore, an injection molded product or a vacuum molded product made of a polymethyl methacrylate resin (hereinafter, referred to as PMMA resin) composition has been used for a cover of a lighting fixture. However, PMMA resins have the property of being relatively hard and brittle. In particular, when the thickness is reduced, it is liable to be broken by an impact, and there is a problem that it is difficult to reduce the cost by designing with a thin thickness and reducing the weight. In addition, a relatively long molding cycle time is required when forming a desired shape from a PMMA resin plate, and a separate cutting step is required when cutting out a product portion. Including the work of removing powder and the like, it takes a lot of time to finish, and raises the production cost. Therefore, a material having a low total cost has been desired.

When a polyester resin is used in the form of a film or sheet, it may be necessary to add various light diffusing agents or use a roll having a rough surface to roughen the surface to impart light diffusing properties. It has been done. However, in the method of kneading the light diffusing agent, in the case of a polyester resin, in particular, in the case of an essentially crystalline polyethylene terephthalate resin (hereinafter referred to as PET resin), a light diffusing agent such as inorganic particles generally used is used. Also acts as a crystallization nucleating agent,
In addition, it is necessary to add a large amount in order to have sufficient light diffusivity by using only those materials, and crystallization is apt to progress depending on the environmental conditions at the time of molding or the subsequent use of the molded product, and as a result, Problems such as changes in optical properties and dimensions,
There is a problem that the lighting becomes dark, and furthermore, there is a problem that the use items are limited due to insufficient heat resistance in some applications.

[0004]

As described above, when the weight of a lighting fixture cover or the like is reduced, the impact resistance is weak when the PMMA resin is made thinner, the molding process requires a relatively long time, and the post-processing is troublesome. As a result, it is difficult to reduce the cost of the lighting equipment in terms of both raw material price and workability. On the other hand, as an alternative material, PET resin is selected because it is excellent in transparency, has higher impact strength than PMMA resin, and can reduce the cost by thinning, molding cycle up and simplification.
That is, a single shot molding of a conventional cut plate of PMMA resin,
From manual operations such as NC router cutting, cutting powder processing, and stacking, continuous forming and punching from a continuous rolled sheet, which is a general sheet forming, and automation of stacking are also possible, thereby enabling a significant cost reduction. However, since polyester resins such as PET resins are crystalline resins in nature, there is a problem that if a large amount of a substance having a nucleating agent effect of accelerating crystallization is mixed in, whitening occurs during molding and the molded article becomes brittle.

[0005] In order to obtain a light diffusion effect, various kinds of patents for adding a specific inorganic substance or organic substance have been made on a plate made of PMMA resin or the like. In the case of PET resin, the above substances are used to improve the light diffusion performance. Even if it is added to improve the crystallization, the above-mentioned crystallization problem occurs, and it is difficult to finally obtain one having sufficient light diffusivity and intensity balance. Further, in general, when a large amount of a light diffusing agent is added, the amount of transmitted light is reduced as a whole, so that there is a problem that the illumination becomes dark and the energy efficiency is low, which is not preferable. Further, since the unstretched PET resin sheet has a glass transition temperature of about 70 to 80 ° C., there is a problem that it cannot be used depending on a lighting equipment cover or an installation environment that generates a large amount of heat. The present invention seeks to solve these problems.

[0006]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies in order to solve these problems in the light diffusion sheet used for lighting equipment covers and the like made of PET resin.
The inventors have invented a polyester resin sheet having a light diffusing property without significantly impairing the excellent properties inherent in the polyester resin by the sheet surface treatment conditions in the following specific composition. Hereinafter, the present invention will be described in detail.

The polyester resin sheet of the present invention is a polyethylene naphthalate resin having 99.5% by weight to 9% by weight of a naphthalene dicarboxylic acid component of 5% to 25% by weight.
A sheet comprising 8% by weight and 0.1 to 2 parts by weight of a light diffusing agent, wherein at least one surface of the sheet has a total light transmittance of 20% to 90% and a diffuse transmittance of 20% to 70%. It is a polyester resin sheet subjected to matte processing and a molded article made thereof.

The polyester resin used in the present invention comprises:
The glycol component is a polyethylene naphthalate resin (hereinafter, referred to as a PEN resin) mainly composed of ethylene glycol, and the acid component is mainly composed of terephthalic acid and 1,5-naphthalenedicarboxylic acid (NDC). It is preferably from 5% by weight to 25% by weight. If it is less than 5% by weight, heat resistance is insufficient,
If it exceeds 25% by weight, the impact resistance is undesirably reduced.

The NDC component can be obtained by directly forming a raw material pellet in which NDC is a copolymer as a copolymer component into a sheet with a single-screw or twin-screw extruder, a homo-PEN resin having a high NDC concentration or a copolymer and a PET resin. Is blended and then melt-mixed with a twin-screw extruder, etc., and once re-pelleted into a sheet with an extruder, the blend of PEN resin and PET resin is directly melt-kneaded with a twin-screw extruder without repelleting Any method of forming a sheet may be used.

Other copolymerizable monomers include diethylene glycol, 1,4-tetramethylene glycol, 1,4-cyclohexanedimethanol and heptamethylene glycol for the glycol component, and isophthalic acid and adipic acid for the dicarboxylic acid component. Can be used as a monomer with a part thereof being replaced. In addition, for the purpose of improving heat resistance, weather resistance, workability, and texture, a small amount of a polyarylate resin, a polycarbonate resin, a polybutylene terephthalate resin, a polyester elastomer, a polystyrene resin, an acrylic resin, a polyamide resin, or the like is added. You can do things.

The light diffusing agent used in the present invention is selected from calcium carbonate, titanium oxide, aluminum hydroxide, silicate, silicon dioxide, zinc sulfide, silicone rubber, etc.
Alternatively, a light diffusing agent using them in combination can be used. The addition amount of the light diffusing agent is desirably 2% by weight or less. 2
If the amount is more than 10% by weight, the total light transmittance is remarkably reduced, and the illumination feels dark, which is not desirable. Further, the light diffusing agent is desirably 0.1% or more. Even if the light diffusing agent is less than 0.1%, if the thickness of the molded article is sufficient, the effect that the shape of the light source cannot be determined by surface processing can be obtained. Considering the case where the wall thickness is partially reduced after the secondary molding, it is desirable to add at least 0.1% or more. In addition, if necessary, the sheet may contain a pigment, a dye, a fluorescent whitening agent, a dispersant, a stabilizer, an ultraviolet absorber, an energy quencher, an antistatic agent,
It is also possible to appropriately add an antioxidant, a heat stabilizer, a lubricant and the like. The thickness of the sheet of the present invention is 0.1 mm to 1.5 m
m is preferred, and more preferably 0.2 mm to 1.0 mm.

At least one side of the PET resin sheet according to the present invention is matted. In the matting process, the resin exiting from the die opening is immediately quenched and solidified into a sheet by a roll having an uneven surface in advance. At the same time, the process of transferring the uneven shape of the roll surface to apply a matting process, make it with a plated metal roll so that both sides have a glossy surface, wind it once in a roll shape into a sheet product, then heat the surface again ,
There is a method in which a sheet is passed through a roll having an uneven shape to form an uneven shape on the sheet surface, and either of them is possible.
The uneven shape and material of the roll are not particularly limited, but in the case of a metal roll, in general, various sculptures such as a lattice, a pyramid, a trapezoid, a silk pattern, a cup, and a sand blast treatment are performed. Such a material can be used, and the depth and pitch of the unevenness are desirably in the range of 5 μm to 100 μm, and more desirably, about 20 to 40 μm in terms of texture and surface strength.

The material of the rolls having an uneven surface used in the above method can be selected from various materials such as metal, rubber, thermosetting resin and thermoplastic resin. It is desirable that the material has heat resistance enough to withstand the temperature, and in general, metal, silicon rubber, thermosetting resin and the like are desirable. Roll surface temperature is 1
The temperature is desirably from 30 ° C to 200 ° C. If the temperature is lower than 130 ° C., the sheet is glossy when reheated during the secondary processing, and the effect is lost. If the temperature is higher than 200 ° C., the sheet sticks to the roll and becomes wrapped, or the sheet is insufficiently cooled and the sheet is warped. Not preferred.

The sheet of the present invention has a total light transmittance of 20% or more.
90% and a diffuse transmittance of preferably 20% to 70%.
A more preferable range of the total light transmittance is 40% to 90%. If the total light transmittance is lower than 20%, the illumination becomes dark.
Total light transmittance exceeds 90% or diffuse transmittance is 20%
If it is lower, the shape of a light bulb or the like becomes visible. A sheet whose total light transmittance and diffuse transmittance are within the above-mentioned range uniformly diffuses the light emitted from the light source, such as a fluorescent lamp or a light bulb, to prevent the shape of the light source from being seen. Is relatively good in transmission, so that efficient illumination is possible. This sheet also has excellent handling properties including moldability,
In particular, it is intended to provide a polyester resin sheet material which can expand the degree of freedom in design for lighting equipment use and can reduce costs in both materials and processes. In addition, the polyester resin used is recyclable, emits no harmful gases or remarkable black smoke during combustion, burns no more calories than wood, and does not damage the combustion furnace. It also has excellent environmental suitability for nature and the human body, such as having harmful ultraviolet absorption performance. As described above, the present invention can provide a polyester resin sheet excellent in light diffusibility, moldability, environmental suitability at the time of disposal, and the like.

[0015]

The present invention will be described in more detail with reference to the following examples. (Evaluation method) The physical properties of the sheet and the molded article were measured at 23 ° C. and 50% humidity under the following environmental conditions. (1) Total light transmittance and diffuse transmittance Samples for measurement were cut out from the sheets of the examples and comparative examples, and JIS K-71 was measured using a turbidimeter manufactured by Nippon Denshoku Industries Co., Ltd.
05. (2) Impact resistance 500 g load using a DuPont impact tester (manufactured by Toyo Seiki)
A 50% breaking energy (unit: J) was calculated according to JIS K-7221 by using a 1 kg, 1/2 inch hemispherical hitting core and a cradle. In addition, in the case of the single-sided matte sheet, the matte side was tested as the shooting center side and the mirror side was used as the receiving side. (3) Heat resistance Using a single-shot vacuum forming machine (FK-0431-10 manufactured by Asano Laboratories) under the conditions of a sheet surface temperature of 130 ° C. and a length of 150 mm × width of 120 mm.
mm × 30 mm depth molded product was prepared and set at 65 ° C. and 7 ° C. in an oven (DH62 manufactured by Yamato Scientific Co., Ltd.).
Heat treatment was performed at 0 ° C. and 75 ° C. for 148 hours, and the degree of deformation was evaluated according to the following criteria. ：: No deformation. Δ: slightly deformed X: significantly deformed

Example 1 90% by weight of PET resin (PET 9921 manufactured by Eastman) and calcium carbonate 1
A master batch (5 wt%) obtained by melt-kneading 0 wt% at an extrusion temperature of 260 to 280 ° C. and 95 wt% of a PEN resin (9508A manufactured by Shinkyo Industry Co., Ltd .; NDC content: 10 wt%) are blended, and the NDC content in the acid component is adjusted. 9.5% was extruded with a 65 mm extruder at an extrusion temperature of 260 to 300 ° C., and the extruded molten material was cooled and solidified between a touch roll surface of a silicon rubber roll and a metal mirror surface chill roll surface, and one side was matte treated. A sheet having a thickness of 0.8 mm was obtained. This has a total light transmittance of 46% and a diffuse transmittance of 45%,
When the sheet was viewed through the light source, the practical light source shape was sufficiently concealable. The DuPont impact strength is 5.0J
There was enough impact resistance.

Further, the single-side matte sheet is vacuum-formed at 130 ° C. under sheet heating conditions by a single-shot vacuum forming machine so that the surface opposite to the matte-treated surface is in contact with the mold, and is 100 mm long × 80 mm wide.
A rectangular molded product having a size of 20 mm x 20 mm was obtained. This was put in a gear oven at a temperature of 65 ° C, 70 ° C, 75 ° C, respectively.
Heat treatment at 168 ° C. for 168 hours showed good heat resistance without deformation under any conditions.

[0018]

[Table 1]

Comparative Example 1 A PEN resin having an NDC content of 87
A sheet was prepared in the same manner as in Example 1 except that the weight% (PEN9508B, manufactured by Shinkyo Industry Co., Ltd.) was used. The NDC content in the acid component was 83% by weight. Excellent in total light transmittance, diffuse transmittance and heat resistance but impact strength is 1.2J
And it was not practical.

Example 2 PEN resin (TN80 manufactured by Teijin Limited)
50, 5 wt% of PEN homopolymer) and 95 wt% of PET resin (9921 manufactured by Eastman) are dried and blended to a water content of 50 ppm or less, and extruded at an extrusion temperature of 260 to 300 ° C. with an extruder. Pellets having an NDC content of about 4.8% by weight in the components were once prepared. 95% by weight of these pellets and 70% by weight of PET resin
And 30% by weight of calcium carbonate were blended with 5% by weight of a master batch prepared in the same manner as in Example 1 to obtain a mixture of 65% by weight.
A 0.8 mm thick double-sided glossy sheet was prepared with a millimeter extruder. The NDC content in the acid component was about 4.8% by weight. This was further passed between a 200-mesh sandblasted matte roll and a rubber roll having a hardness of 90 degrees, and treated at a roll temperature of 150 ° C. and a linear pressure of 130 kg / cm to obtain a single-side matte sheet. The light transmittance was 26%, the diffuse transmittance was 24%, and the diffusivity was good. The impact strength was 5.0 J, but the heat resistance was slightly deformed at 75 ° C.

Example 3 A sheet was prepared in the same manner as in Example 2 except that the amount of the PEN resin was changed to 10% by weight.
The light diffusion property was good, the impact resistance was high, and the heat resistance at 75 ° C. for 168 hours was not a problem.

Example 4 A sheet was prepared in the same manner as in Example 3 except that the blending amount of the PEN resin was changed to 20% by weight.
The light diffusion property was good, the impact resistance was high, and the heat resistance at 75 ° C. for 168 hours was not a problem.

Comparative Example 2 A sheet was prepared in the same manner as in Example 3 except that the amount of the PEN resin was changed to 50% by weight.
Although this sheet had sufficient heat resistance, it was brittle and easily broken, which was not very practical.

Comparative Example 3 PE without any PEN resin
The same sheet and molded product as in Example 1 except for the T resin alone were evaluated. 65 ° C x 16 with impact strength but no heat resistance
Deformation was observed even after 8 hours.

Comparative Example 4 Sheets and molded products were evaluated in the same manner as in Example 1 except that only the PEN resin was used and no light diffusing agent was used. Although heat resistance was good, there was no impact strength and there was no practicality.

[0026]

As described above, the sheet of the present invention and the molded product thereof can diffuse light uniformly to prevent the shape of the light source from being seen, and have relatively good light transmittance, so that efficient illumination is possible. Also, it has excellent moldability. The polyester resin used is recyclable and has excellent environmental suitability.

──────────────────────────────────────────────────続 き Continuation of the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical indication location C08K 3/26 C08K 3/26 3/36 KJS 3/36 KJS C08L 67/02 KJR C08L 67/02 KJR F21V 1/22 F21V 1/22 // B29K 67:00 B29L 7:00

Claims (3)

[Claims] 1. A polyester resin comprising a naphthalenedicarboxylic acid component in an acid component in an amount of 5 to 25% by weight, a polyethylene naphthalate resin in an amount of 99.9% to 98% by weight, and a light diffusing agent in an amount of 0.1 to 2% by weight. A polyester resin sheet, characterized in that at least one surface thereof is matted so that the total light transmittance is 20% to 90% and the diffuse transmittance is 20% to 70%. 2. The method according to claim 1, wherein the total light transmittance is 40% to 90%.
% Polyester resin sheet. 3. A molded article comprising the polyester resin sheet according to claim 1 or 2.