JP2001019779A - Synthetic resin sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a synthetic resin sheet capable of improving heat resistance and thermal dimensional stability while maintaining its transparency. SOLUTION: This transparent synthetic resin sheet 1 consists of a synthetic resin 2 as a main component, and contains super fine particles of an inorganic material having <=100 nm particle diameter as dispersed in the synthetic resin 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transparent synthetic resin sheet mainly composed of a synthetic resin such as polycarbonate.

[0002]

2. Description of the Related Art Today, a transparent synthetic resin sheet is used for various sheets such as a light diffusion sheet and an agricultural sheet provided in a backlight unit of a liquid crystal display device. In order to ensure the transparency of such a synthetic resin sheet, generally, light scattering, eliminating foreign matter that causes absorption,
It is necessary to improve the cleanness of the synthetic resin itself.

[0003]

In the above-mentioned conventional transparent synthetic resin sheet, when a certain material is filled in the synthetic resin for the purpose of improving heat resistance and thermal dimensional stability, the transparency is reduced. There was an inconvenience of being lost.

[0004] The present invention has been made in view of these disadvantages, and has as its object to provide a synthetic resin sheet capable of improving heat resistance and thermal dimensional stability while maintaining transparency. is there.

[0005]

The invention made to solve the above problem is a transparent synthetic resin sheet containing a synthetic resin as a main component, wherein the synthetic resin contains inorganic ultrafine particles dispersed therein. Things. Here, “transparent” is not limited to the case where it is completely transparent, and is a concept including so-called translucent.

According to this synthetic resin sheet, the apparent crystallinity is improved by the ultrafine particles of the inorganic substance contained in the dispersion, and as a result, the heat resistance and the thermal dimensional stability can be improved. In addition, since what is dispersed and contained for improving the heat resistance is ultrafine particles, the degree of hindering the transparency is small. Further, when the particle diameter (meaning the average diameter of the particles) of the ultrafine particles of the inorganic substance is 100 nm or less, it is smaller than the wavelength of visible light, and transparency can be completely maintained.

The amount of the ultrafine particles of the inorganic substance is preferably 0.01 to 100 parts by weight based on 100 parts by weight of the synthetic resin. This is because if the blending amount of the inorganic ultrafine particles is less than the above range, the heat resistance and thermal dimensional stability of the synthetic resin sheet cannot be sufficiently achieved, and conversely, the blending amount falls within the above range. If the amount exceeds the above range, dispersion in the synthetic resin becomes difficult, and the mechanical properties of the synthetic resin sheet are adversely affected.

[0008] The inorganic material may be a metal oxide. Here, the “metal” of the metal oxide is a concept including semimetals such as silicon and cerium in addition to metals. This metal oxide is stable even at a high temperature, and has a great effect of improving the above heat resistance and thermal dimensional stability. Further, the metal oxide is safe to handle, and can also improve the mechanical properties, rigidity, strength, and the like of the synthetic resin sheet.

It is preferable to use the inorganic ultrafine particles whose surfaces have been subjected to a lipophilic treatment. Here, the “lipophilic treatment” means a treatment for making the surface of ultrafine particles having hydrophilicity lipophilic. When the particles become fine, the surface energy increases, and it becomes extremely difficult to disperse the particles in the synthetic resin. Therefore, when the surface of the inorganic ultrafine particles is subjected to the lipophilic treatment as in the means, the affinity with the synthetic resin is improved, and the dispersion in the synthetic resin can be facilitated.

The lipophilic treatment is preferably a fatty acid treatment. The surface treatment of the particles using a higher fatty acid represented by stearic acid can not only improve the affinity with the synthetic resin as described above but also positively modify the synthetic resin sheet. In other words, a fatty acid treatment using acrylic acid or a derivative thereof, an organic titanate coupling agent, a silane coupling agent, or the like imparts a functional group to the surface of the inorganic ultrafine particles, and functions by a bonding reaction between the functional group and the synthetic resin. Performance can be improved.

Preferably, polycarbonate is used as the synthetic resin. Such a polycarbonate itself is excellent in transparency and thermal dimensional stability, and has an effect of improving transparency, heat resistance and thermal dimensional stability by dispersing and containing inorganic ultrafine particles as described above. It can be played even more.

[0012]

Embodiments of the present invention will be described below in detail with reference to the drawings as appropriate. FIG. 1 is a schematic sectional view showing a synthetic resin sheet according to one embodiment of the present invention. FIG.
The synthetic resin sheet 1 includes a synthetic resin 2 formed in a sheet shape and inorganic ultrafine particles 3 dispersed inside the synthetic resin 2.

The synthetic resin 2 is not particularly limited as long as it is transparent. For example, polyethylene terephthalate, polyethylene naphthalate, acrylic resin, polycarbonate, polystyrene, polyolefin, cellulose acetate, weather resistant vinyl chloride and the like can be used. it can. However, considering transparency, heat resistance and thermal dimensional stability, polycarbonate is preferred.

The inorganic substance used for the ultrafine particles 3 includes:
Silicon, copper, nickel, metals such as cerium, oxides and nitrides thereof, specifically, colloidal silica, smectite, colloidal calcium carbonate,
Mica, titanium oxide, zircon oxide, antimony oxide,
Zinc oxide, magnesium oxide, talc, alumina, barium sulfate, asbestos, and the like can be used. Above all, metal oxides are stable even at high temperatures, have a great effect of improving heat resistance and thermal dimensional stability, are safe to handle, and have the mechanical properties, rigidity,
From the viewpoint that strength and the like can be improved,
It is suitable for the ultrafine particles 3.

It is preferable that the ultra-fine particles 3 have a smaller particle diameter in order to prevent a loss of transmitted light. Specifically, the wavelength is preferably 100 nm or less, which is equal to or less than the wavelength of visible light, and particularly preferably 50 nm or less in order to prevent the synthetic resin sheet 1 from becoming bluish and turbid under the influence of a short wavelength. The lower limit is not particularly limited since the smaller the particle size of the ultrafine particles 3 is, the better. However, the particle size of the ultrafine particles 3 generally obtained is 5 nm or more.

The shape of the ultrafine particles 3 is not particularly limited, and examples thereof include a sphere, a cube, a needle, a rod, a spindle, a plate, a scale, and a fiber. Among them, flakes and plates are preferred for improving heat resistance and thermal dimensional stability.

Ultrafine particles 3 in the synthetic resin sheet 1
Is 0.0 to 100 parts by weight of the synthetic resin 2.
It is preferably from 1 to 100 parts by weight, particularly preferably from 10 to 100 parts by weight. This is because if the amount of the ultrafine particles 3 is less than the above range, the heat resistance and the thermal dimensional stability of the synthetic resin sheet 1 cannot be sufficiently achieved. If it exceeds, dispersion in the synthetic resin 2 becomes difficult, and the mechanical properties of the synthetic resin sheet 1 are adversely affected.

The surface of the ultrafine particles 3 may be subjected to a lipophilic treatment. Ultrafine particles 3 subjected to such lipophilic treatment
Has an improved affinity with the synthetic resin 2 and is easily dispersed in the synthetic resin 2. As the lipophilic treatment, fatty acid treatment is preferable. Ultra-fine particles 3 treated with this fatty acid
Has a functional group formed on the surface, and this functional group and the synthetic resin 2
The functionality is improved by the binding reaction with

The synthetic resin sheet 1 having the above structure is
The apparent degree of crystallinity is improved by the inorganic ultrafine particles 3 dispersed and contained in the synthetic resin 2, and as a result, heat resistance and thermal dimensional stability can be improved. Further, since the ultrafine particles 3 are fine as described above, the transparency of the synthetic resin sheet 1 is not hindered.

The size of the synthetic resin sheet 1 may be appropriately determined according to the application to which the sheet is applied.

Next, a method for manufacturing the synthetic resin sheet 1 will be described. First, the ultrafine particles 3 are subjected to the lipophilic treatment. Further, the ultrafine particles 3 may be heated to a considerably high temperature of 25 ° C. to 300 ° C. to remove water. This is because the ultrafine particles 3 have a large specific surface area and a large amount of adsorbed moisture per unit weight, and therefore, if mixed into the synthetic resin 2 while containing moisture, there is a possibility that silver marks and bubbles may be generated. Thereafter, the ultrafine particles 3 are kneaded in the synthetic resin 2 in a molten state, and the kneaded ultrafine particles 3 are formed into a sheet by an extrusion method or the like.

[0022]

As described above, according to the synthetic resin sheet of the present invention, since it has heat resistance while maintaining transparency, the following effects can be exhibited. (1) When the synthetic resin sheet of the present invention is used as a light diffusion sheet or a lens sheet provided in a backlight unit of a liquid crystal display device, the light diffusion sheet or the like has a temperature of about 80 ° C. to 90 ° C. near a lamp. Although exposed below, thermal deformation due to such heat can be prevented. As a result, it is possible to prevent the light diffusion sheet or the like from bending, and to prevent the occurrence of luminance unevenness on the screen of the liquid crystal display device.

(2) When the synthetic resin sheet is used as an agricultural sheet stretched over a house or the like, the occurrence of deterioration due to exposure to sunlight can be delayed, and the life of the agricultural sheet can be extended. . Today, disposal of such a synthetic resin sheet for agriculture has become a problem from the viewpoint of protection of the global environment. Use of the synthetic resin sheet can reduce such a problem.

(3) As described above, the synthetic resin sheet has high transparency, so that even if a light beam is transmitted, heat generation is extremely small, which also contributes to heat resistance.

(4) Since heat resistance dimensional stability is high,
It can be applied to lighting equipment, lamp shades, and the like.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing a synthetic resin sheet according to one embodiment of the present invention.

[Explanation of symbols]

 1 Synthetic resin sheet 2 Synthetic resin 3 Ultra fine particles

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08L 69/00 C08L 69/00 101/16 101/00 F term (Reference) 4F071 AA01 AA50 AB01 AB18 AD02 AD06 AF30 AF45 AF54 AG01 AH01 AH12 BA01 BB06 BC01 4F073 AA01 BA47 BB01 4J002 AA011 CG001 DE046 DE096 DE136 DE236 DJ016 DJ056 FB236 FD016 GA01 GP00

Claims (7)

[Claims] 1. A synthetic resin sheet comprising a synthetic resin as a main component, wherein the synthetic resin sheet contains inorganic fine particles dispersed in the synthetic resin. 2. The inorganic ultrafine particles having a particle size of 100 n
The synthetic resin sheet according to claim 1, which is not more than m. 3. The synthetic resin sheet according to claim 1, wherein the amount of the ultrafine particles of the inorganic substance is 0.01 to 100 parts by weight based on 100 parts by weight of the synthetic resin. 4. The synthetic resin sheet according to claim 1, wherein the inorganic substance is a metal oxide. 5. The synthetic resin sheet according to claim 1, wherein the inorganic ultrafine particles have a surface subjected to a lipophilic treatment. 6. The synthetic resin sheet according to claim 5, wherein the lipophilic treatment is a fatty acid treatment. 7. The synthetic resin sheet according to claim 1, wherein the synthetic resin is polycarbonate.