JPH11268157A - Foam multilayer material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress a transcription of a surface by laminating a thermoplastic resin non-foam layer in which particles having a specific particle size are dispersed on at leas tone surface of a thermoplastic resin foam layer, thereby providing a light weight and a strength and diffusing a light from a light source. SOLUTION: A thermoplstic resin non-foam layer 3 in which particles having a particle size of 30 to 50 μm are dispersed is laminated at least on one surface of a thermoplastic resin foam layer 1 to form the foam multilayer material 4. When the thermoplastic resin is used, for example, as an illumination cover, as the resin, an acrylic resin, polystyrene resin, polycarbonate resin or the like is suitably used. As foams 5 of the foam layer, foams containing closed cell foams as a main body are suitable in view of points of a strength and light diffusing properties. Its foam size is normally about 50 to 300 μm and its foaming magnification is normally about an equal size to three times. As the thermoplastic resin for constituting the non-foam layer, in the case of using it as the illumination cover, an acrylic resin, polystyrene resin, polycarbonate resins or the like is suitable.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a foamed multilayer body.

[0002]

2. Description of the Related Art Conventionally, as a lighting cover or the like, a thermoplastic resin plate containing a light diffusing agent or the like has been frequently used in order to appropriately diffuse light from a light source to obtain soft illumination. Such a thermoplastic resin plate generally has a smooth surface, so that reflection due to surface reflection is large. Therefore, in order to suppress such reflection, the particle diameter is 3 to 50.
A thermoplastic resin plate further containing transparent particles of about μm and having fine irregularities on the surface is also used.

However, in a thermoplastic resin plate containing such a light diffusing agent and transparent particles, in order to sufficiently diffuse the light from the light source and to suppress the reflection on the surface,
At least a certain amount of light diffusing material and transparent particles must be contained per unit area. For that purpose, for example, the content of the light diffusing agent and the transparent particles in the thermoplastic resin may be increased. However, the content of the thermoplastic resin is reduced, and the strength of the thermoplastic resin plate is reduced. On the other hand, to reduce the decrease in strength, the content of the light diffusing agent and the transparent particles may be reduced, but in order to sufficiently diffuse the light from the light source, the thickness of the thermoplastic resin plate must be reduced. There is a problem that the weight must be increased, and the weight of the entire thermoplastic resin plate increases.

[0004]

Accordingly, the present inventors have developed a thermoplastic resin which can sufficiently diffuse the light from the light source to suppress the reflection of the surface, and can have both sufficient strength and light weight. As a result of intensive studies to develop a resin plate, a foamed multilayer body in which a thermoplastic resin non-foamed layer in which particles are dispersed is laminated on at least one surface of the thermoplastic resin plate,
Relatively lightweight and strong, and has the ability to diffuse light from the light source, and found that reflection on the surface can be suppressed,
The present invention has been reached.

[0005]

That is, the present invention relates to a non-foamed thermoplastic resin layer in which particles (2) having a particle diameter of 30 to 50 μm are dispersed on at least one surface of a foamed thermoplastic resin layer (1). The present invention provides a foamed multilayer body (4) obtained by laminating (3). One example of such a foamed multilayer body of the present invention is shown in FIGS.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The thermoplastic resin constituting the thermoplastic resin foam layer (1) in the foamed multilayer body of the present invention includes, for example, acrylic resin, polystyrene resin, polycarbonate resin, polyolefin resin, and the like.
Above all, when used as a lighting cover, acrylic resin, polystyrene resin, polycarbonate resin and the like are preferably used. Examples of the acrylic resin include methacrylic resin and methacrylic acid-styrene copolymer, and examples of the polyolefin resin include polyethylene, polypropylene, and ethylene-propylene copolymer. The cells (5) of the thermoplastic resin foam layer may be open cells, but are preferably composed mainly of closed cells in view of strength and light diffusibility.

The cell diameter of such a foamed layer is usually 50 μm to 3 μm.
It is about 00 μm. If the bubble diameter is less than 50 μm, the light transmittance tends to be insufficient, and if it exceeds 300 μm, the strength tends to decrease. The expansion ratio is usually more than 1 and about 3 or less. When the expansion ratio exceeds 3 times, the light transmittance tends to decrease.

The thickness of the foamed thermoplastic resin layer is not particularly limited. For example, when the foamed multilayer body of the present invention is used as a lighting cover, it is usually about 1 mm to 3 mm.
Such a thermoplastic resin foam layer may contain other additives such as a pigment, a dye, an antioxidant, an antistatic agent, an ultraviolet absorber, and a light diffusing agent.

The thermoplastic resin non-foamed layer (3) is a layer made of a thermoplastic resin containing almost no air bubbles therein, and is formed on at least one surface of the thermoplastic resin foamed layer (1). Examples of the thermoplastic resin constituting the thermoplastic resin non-foamed layer include, for example, an acrylic resin, a polystyrene resin, a polycarbonate resin, and a polyolefin resin. Resins and the like are preferably used. As acrylic resin, methacrylic resin, methacrylic acid-styrene copolymer and the like,
Examples of the polyolefin resin include polyethylene, polypropylene, and ethylene-propylene copolymer.

The non-foamed thermoplastic resin layer has a particle size of 3 to 5
Particles (2) of 0 μm, preferably 5 to 40 μm are dispersed. If the particle diameter is less than 3 μm, the irregularities on the surface tend to be small, and the suppression of reflection on the surface tends to be insufficient. If it exceeds 50 μm, the surface roughness tends to be noticeable.

Usually, such particles are used in a transparent state, for example, crosslinked acrylic resin particles, crosslinked polystyrene particles, silicon particles, glass particles and the like. The refractive index (n ₁ ) of the particles may be substantially the same as or different from the refractive index (n ₀ ) of the thermoplastic resin constituting the thermoplastic resin non-foamed layer. When different, the thermoplastic resin non-foamed layer can diffuse light,
For example, as in the case of using an acrylic resin as the thermoplastic resin constituting the thermoplastic resin non-foamed layer and using crosslinked polystyrene particles as the particles, the difference between n ₁ and n ₀ is 0.04.
In this case, light can be sufficiently diffused. The content of the particles is not particularly limited as long as the reflection of the surface can be suppressed, but is usually about 2 to 16 parts by weight per 100 parts by weight of the thermoplastic resin constituting the thermoplastic resin non-foamed layer.

The thermoplastic resin non-foamed layer contains other additives such as pigments, dyes, antioxidants, ultraviolet absorbers, antistatic agents, light diffusing agents, rubber particles for improving impact resistance, and the like. It may be. The thickness of the thermoplastic resin non-foamed layer may be generally about 0.05 mm to 0.5 mm.

The non-foamed thermoplastic resin layer (3) may be laminated on one side of the foamed thermoplastic resin layer (FIG. 1) or on both sides (FIG. 2). When laminated on one side, the other side of the thermoplastic resin foam layer does not have to be laminated with another layer, for example, a layer containing no particles, for example, a thermal layer constituting a thermoplastic resin non-foamed layer A thermoplastic resin layer made of the same thermoplastic resin as the thermoplastic resin may be laminated.

In the foamed multilayer body of the present invention, for example, a thermoplastic resin foamed molded article (11) and a thermoplastic resin non-foamed molded article (31) in which particles are dispersed are separately manufactured and then laminated with an adhesive. Method, a method of laminating by hot pressing (FIG. 2), a foamable thermoplastic resin layer (12) made of a thermoplastic resin containing a foaming agent, and a thermoplastic resin non-foamed layer (32) in which particles are dispersed. Are obtained (FIG. 4), and the foamable thermoplastic resin layer is foamed.

To obtain a foamable thermoplastic resin layer (42) in which a foamable thermoplastic resin layer (12) and a thermoplastic resin non-foamed layer (32) are laminated, for example, a thermoplastic resin and a foaming agent are contained. Foamable composition, and a non-foamable composition containing a thermoplastic resin and particles may be co-extruded,
The foamable thermoplastic resin molded article obtained by molding the foamable composition and the thermoplastic resin non-foamed molded article obtained by molding the non-foamable composition may be laminated by a method such as hot pressing. .

In order to foam the foamable thermoplastic resin layer,
For example, when using a pyrolytic foaming agent as the foaming agent,
What is necessary is just to heat a foamable multilayer body above the thermal decomposition temperature.
Examples of the thermal decomposition type foaming agent include dinitrosopentamethylenetetramine, azodicarbonamide, P, P'-oxybisbenzenesulfonylhydrazide, 4,4'-oxybisbenzenesulfonylhydrazide, P-toluenesulfonylhydrazide, P-toluene Examples include sulfonylacetone hydrazide, hydrazodicarbonamide, sodium carbonate, sodium bicarbonate and the like. Are commercially available. The type and amount of the foaming agent are appropriately selected depending on the desired expansion ratio, cell diameter, and the like, and are usually about 0.5 to 2 parts by weight per 100 parts by weight of the thermoplastic resin in the foamable composition.

[0017]

The foamed multilayer body of the present invention can sufficiently diffuse light from a light source without containing a light diffusing agent, and therefore can have sufficient strength for practical use, and is relatively lightweight. In addition, since the reflection of the surface can be suppressed, it is useful as, for example, an indoor lighting cover or a signboard lighting cover that is decorated with a picture or the like.

[0018]

EXAMPLES The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

The evaluation of the foamed multilayer body obtained in the examples was carried out by the following method. (1) Plate Thickness From the cross-sectional micrograph of the obtained foamed multilayer body, the thickness of the entire foamed multilayer body was measured. (2) Non-foamed layer thickness The thickness of the thermoplastic resin non-foamed layer (3) was measured from a cross-sectional photograph of the obtained foamed multilayer body. In addition, since the thermoplastic resin non-foamed layer (3) was on both surfaces of the thermoplastic resin foamed layer (1), the thickness of each layer was measured. (3) Expansion Ratio From the weight per unit area of the obtained foamed multilayer body, it was calculated based on the density (1.49 g / cm ³ ) of the thermoplastic resin used. (4) Total light transmittance Measured according to the method B of JIS K-7105. (5) Specular reflectance The 60-degree specular reflectance was measured according to JIS K-7105. (6) Light Diffusion Coefficient Using an automatic goniophotometer, light was irradiated from the normal direction of the obtained foamed multilayer body, and the luminance at 5 ° from the normal direction (A ₅ ) and the luminance at 20 ° ( A ₂₀ ) and luminance at 70 ° (A ₇₀ ) were measured, and the light diffusion coefficient was calculated by the following equation (1): Light diffusion coefficient = (A ₂₀ + A ₇₀ ) / A ₅ × 2 (1) (7) Yield stress According to JIS K-7203, the bending speed is 2 mm / min.
Bending span 50mm, sample size 15mm x 100m
m, MD (extrusion direction). (8) Cell diameter Observing the obtained foamed multilayer body from the surface with an optical microscope,
The cell diameter was determined.

Example 1 A methacrylic resin [SUMIPEX EXA, Sumitomo Chemical Co., Ltd.
92 parts by weight and crosslinked acrylic resin particles [MBX-12, manufactured by Sekisui Chemical Co., Ltd., average particle size 1
2 μm] of 8 parts by weight was mixed with a Henschel mixer and then melt-extruded at 230 ° C. to obtain a pellet-like non-foamable composition. In addition, methacrylic resin [Sumipex G5
056, manufactured by Sumitomo Chemical Co., Ltd.] 100 parts by weight and a pyrolytic foaming agent [CELLMIC M188, manufactured by Sankyo Chemical Co., Ltd.] 1
The parts by weight were dry-blended to obtain a foamable composition.

The non-foamable composition and the foamable composition obtained above are co-extruded from a T-die using a multilayer extruder to form a foamable thermoplastic resin layer (12) made of a thermoplastic resin containing a foaming agent. )) A foamable multilayer body (42) comprising a thermoplastic resin non-foamed layer (3, 32) in which particles are dispersed on both sides.
(FIG. 5), which is obtained by foaming the thermoplastic resin layer (12) simultaneously with the multilayer extrusion to form the thermoplastic resin foam layer (1).
And a foamed multilayer body (4) was obtained (FIG. 2). In addition,
The melting temperature of the foamable composition in the multilayer extrusion is 230 ° C,
The melting temperature of the non-foamable composition was 260 ° C, and the die temperature of the multilayer extruder was 250 ° C. Table 1 shows the evaluation results of the obtained foamed multilayer body. The bubbles of the foamed thermoplastic resin layer had an elliptical shape of about 200 μm in the MD direction and about 100 μm in the TD direction (direction orthogonal to the extrusion direction) over the entire surface. When this foamed multilayer body was used as a lighting cover, it had practically sufficient strength as a lighting cover.

Example 2 Crosslinked acrylic resin particles [MBX-12, average particle size 12
μm], the same procedure as in Example 1 was carried out except that 8 parts by weight of crosslinked acrylic resin particles [XC1A, manufactured by Sumitomo Chemical Co., Ltd .; Obtained. This foamed multilayer body had practically sufficient strength as a lighting cover. Table 1 shows the evaluation results.
The bubbles in the foamed thermoplastic resin layer had an elliptical shape of approximately 200 μm in the MD direction and approximately 100 μm in the TD direction over the entire surface. When this foamed multilayer body was used as a lighting cover, it had practically sufficient strength as a lighting cover.

Example 3 Pyrolytic foaming agent [Celmic M188, Sankyo Chemical Co., Ltd.
) Was obtained in the same manner as in Example 1 except that the amount used was 0.2 parts by weight. This foamed multilayer body
It had sufficient strength for practical use as a lighting cover. Table 1 shows the evaluation results. The bubbles in the foamed thermoplastic resin layer had an elliptical shape of approximately 200 μm in the MD direction and approximately 100 μm in the TD direction over the entire surface. When this foamed multilayer body was used as a lighting cover, it had practically sufficient strength as a lighting cover, had sufficient light diffusing properties, and was transparent.

Example 4 Pyrolytic foaming agent [Celmic M188, Sankyo Chemical Co., Ltd.
) Was obtained in the same manner as in Example 2 except that the used amount of the compound was 0.2 parts by weight. This foamed multilayer body
It had sufficient strength for practical use as a lighting cover. Table 1 shows the evaluation results. The bubbles in the foamed thermoplastic resin layer had an elliptical shape of approximately 200 μm in the MD direction and approximately 100 μm in the TD direction over the entire surface. When this foamed multilayer body was used as a lighting cover, it had practically sufficient strength as a lighting cover, had sufficient light diffusing properties, and was transparent.

Comparative Example 1 Methacrylic resin [Sumipex EXA, Sumitomo Chemical Co., Ltd.
(Powder manufactured by Co., Ltd.) at 230 ° C. to obtain a pellet-like non-foamable composition. A foamed multilayer body was obtained in the same manner as in Example 1 except that this non-foamable composition was used instead of the non-foamable composition obtained in Example 1. This foamed multilayer body had practically sufficient strength as a lighting cover. Table 1 shows the evaluation results. Further, the bubbles of the thermoplastic resin foam layer are approximately 200 μm in the MD direction over the entire surface, and T
It had an elliptical shape of about 100 μm in the D direction.

Comparative Example 2 Pyrolytic foaming agent [Celmic M188, Sankyo Chemical Co., Ltd.
) Was obtained in the same manner as in Comparative Example 1 except that the amount used in Example 1 was changed to 0.2 part by weight. This foamed multilayer body had practically sufficient strength as a lighting cover. Table 1 shows the evaluation results. The bubbles in the thermoplastic resin foam layer are approximately 200 μm in the MD direction and approximately 1 μm in the TD direction over the entire surface.
It was an elliptical shape of about 00 μm. When this foamed multilayer body was used as a lighting cover, it had practically sufficient strength as a lighting cover, had sufficient light diffusing properties, and was transparent.

[0027]

[Table 1] 厚 Thickness Non-foamed layer Foamed All light Mirror surface Light diffusion Yield stress Thickness Magnification Transmittance Reflectance coefficient (mm) (mm) (times) (%) (%) (kg / cm ² ) ──────────────────── ─────────────── Example 1 1.60 0.12 / 0.14 2.03 29.7 19.5 0.89 322 Example 2 1.59 0.16 / 0.13 2.00 26.4 18.7 0.89 340 Example 3 1.91 0.43 / 0.26 1.20 57.9 22.1 0.91 720 Example 4 2.00 0.32 / 0.23 1.24 48.9 15.2 0.50 780 Comparative Example 1 1.59 0.17 / 0.08 1.92 27.8 71.6 0.48 358 Comparative Example 2 1.73 0.43 / 0.19 1.21 65.3 51.4 0.75 798 ───────────── ──────────────────────

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing an example of a foamed multilayer body of the present invention.

FIG. 2 is a schematic sectional view showing another example of the foamed multilayer body of the present invention.

FIG. 3 is a schematic sectional view showing an example of the method for producing a foamed multilayer body of the present invention.

FIG. 4 is a schematic cross-sectional view showing an example of a foamable multilayer body for producing the foamed multilayer body of the present invention.

FIG. 5 is a schematic sectional view showing an example of a foamable multilayer body for producing the foamed multilayer body of the present invention.

[Explanation of symbols]

 1: foamed thermoplastic resin layer 2: particles 3: non-foamed thermoplastic resin layer 4: foamed multilayer body 5: air bubbles 11: foamed thermoplastic resin body 31: thermoplastic resin non-foamed body 12: foamable thermoplastic resin Layer 32: thermoplastic resin non-foamed layer 42: foamable multilayer body

Claims (11)

[Claims] 1. A foamed multilayer body comprising a thermoplastic resin foamed layer and a thermoplastic resin non-foamed layer in which particles having a particle diameter of 3 to 50 μm are laminated on at least one surface of the foamed thermoplastic resin layer. 2. The foamed multilayer body according to claim 1, wherein the thermoplastic resin constituting the foamed thermoplastic resin layer is an acrylic resin, a polystyrene resin, a polycarbonate resin or a polyolefin resin. 3. The thermoplastic resin foam layer has a cell diameter of 50 μm or less.
The foamed multilayer body according to claim 1, which has a thickness of 300 µm. 4. The foamed multilayer body according to claim 1, wherein the foaming ratio of the foamed thermoplastic resin layer is more than 1 and not more than 3 times. 5. The thermoplastic resin foam layer has a thickness of 1 mm to 3 m.
The foamed multilayer body according to claim 1, wherein m is m. 6. The thermoplastic resin constituting the thermoplastic resin non-foamed layer is an acrylic resin, a polystyrene resin, a polycarbonate resin or a polyolefin resin.
2. The foamed multilayer body according to item 1. 7. The foamed multilayer body according to claim 1, wherein the particles are crosslinked acrylic resin particles, crosslinked polystyrene particles, silicon particles or glass particles. 8. The foamed multilayer body according to claim 1, wherein the difference between the refractive index of the particles and the refractive index of the thermoplastic resin constituting the thermoplastic resin non-foamed layer is 0.04 or more. 9. The foamed multilayer body according to claim 1, wherein the content of the particles is 2 to 16 parts by weight per 100 parts by weight of the thermoplastic resin constituting the thermoplastic resin non-foamed layer. 10. A thermoplastic resin non-foamed layer having a thickness of 0.05
The foamed multilayer body according to claim 1, which has a thickness of 0.5 mm to 0.5 mm. 11. A lighting cover comprising the multilayer foam according to claim 1.