JP2820611B2 - Multilayer polyolefin sheet and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a covering material for a binder,
The present invention relates to a multilayer polyolefin sheet suitable as a material for a document case, a book case, and the like, and a method for producing the same.

[0002]

2. Description of the Related Art Hitherto, polyolefin sheets such as polypropylene sheets obtained by an extrusion method or the like have been widely used as a material for a binder covering material, a document case, a book case, or the like. Such a polyolefin sheet is roughly classified into a non-foamed polyolefin sheet and a microfoamed polyolefin sheet which is foamed about 1 to 3 times.

[0003]

Among the above-mentioned polyolefin sheets, the specific gravity is large, so that the weight of the product is increased, or the feel of the product is hard, or the rigidity is low. It has a drawback that it has a weak waist and a drawback that it is difficult to apply coloring, printing of a picture or the like, or embossed pattern on the surface.

The above-mentioned polyolefin sheet is usually formed by extrusion molding from a T-die. At this time, the sheet is deformed in a wavy shape due to expansion in the width direction, and the foaming unevenness is caused. However, there is also a disadvantage that the thickness tends to vary.

[0005] To solve the above-mentioned problems, for example, one disclosed in JP-A-63-252715 is known. This proposal proposes a method in which a resin composition containing a foaming agent and a composition containing a filler are melt-kneaded and laminated, respectively.
It is intended to prevent the extruded foam sheet from being deformed in a wavy shape by producing it by a co-extrusion method of extruding from a die.

According to the above proposal, the extruded foam sheet is certainly prevented from being deformed in a wavy manner, but since the layer to be the surface layer contains a relatively large amount of filler, At the time of melt extrusion, the resin mass easily adheres to the vicinity of the discharge port of the T-die, and the resin mass occasionally drops on the product sheet, causing a defect.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and has high rigidity, good surface properties, and can easily and clearly apply coloring, printing of a pattern, embossed pattern, and the like to the surface. And a method for producing the same.

[0008]

The multi-layer polyolefin sheet of the present invention comprises a resin 1 on both sides of a foamed polyolefin layer.
00 parts by weight per characterized by comprising sequentially laminating a non-foam polyolefin layer substantially free of non-foamed polyolefin layer Contact and fillers containing from 5 to 30 parts by weight filler by coextrusion. A method for manufacturing a multilayer polyolefin sheets of the present invention described above, expandable polyolefin resin composition containing a foaming agent, non-foaming against the 100 parts by weight of the resin containing charge <br/> Hamazai 5-30 parts by weight that the non-expandable polyolefin resin composition containing no polyolefin resin composition Contact and filler substantially sequentially laminated with each melt-kneaded, characterized by molding by co-extrusion method of extruding from a T-die It is.

The polyolefin resin used in the present invention includes polyethylene, polypropylene, a copolymer of these with other α-olefins, or other monomers copolymerizable therewith, such as vinyl acetate, chloride, and the like. Examples thereof include copolymers with vinyl, (meth) acrylic acid, (meth) acrylic acid ester, vinyl alcohol, and the like, and mixtures thereof. Particularly, copolymers mainly composed of polypropylene or propylene, or copolymers mainly composed of these. Preferred mixtures are: The polyolefin resin used in the present invention may be a crosslinked one. Also,
Various additives conventionally used, for example, antioxidants, coloring agents, ultraviolet absorbers, antistatic agents, plasticizers, lubricants, and the like can be added to these polyolefin resins as needed. A filler may be added to the foamed polyolefin layer within a range that does not impair the properties of the foamed polyolefin layer.

[0010] The above layers constituting the multilayer polyolefin sheet of this invention may be those each composed of the same resin, but may be one each consisting of different resins, the adhesion of each layer In consideration of the above, it is desirable that each layer is made of a resin having good mutual adhesion.

Specific examples of the foaming agent contained in the foamed polyolefin layer include azodicarbonamide, azobisisobutyronitrile, diazoaminobenzene, N, N'-dinitrosopentamethylenetetramine, and N, N'-. Dimethyl-N, N'-dinitroterephthalamide, benzenesulfonyl hydrazide, p-toluenesulfonyl hydrazide, p, p'-oxybisbenzenesulfonyl hydrazide, carbonate, organic acid salt and other chemical blowing agents, propane, butane, pentane, Dichlorodifluoromethane, dichloromonofluoromethane, trichloromonofluoromethane,
Examples include physical foaming agents such as methanol and ethanol, and microcapsules containing a thermal expansion agent.

The expansion ratio of the foamed polyolefin layer depends on the use of the multilayer polyolefin sheet and the like, but in order to obtain preferable physical properties when used as a material for a binder covering material, document case, book case, etc. It is desirable to make it about 1 to 10.0 times.
If the expansion ratio of the foamed polyolefin layer is too small, the obtained multilayer polyolefin sheet will have a large weight and a hard feel. Conversely, if the expansion ratio of the expanded polyolefin layer is too large , the resulting multi-layer polyolefin sheet will have low stiffness.

The filler added to the non-foamed polyolefin layer containing a filler, which is laminated on both sides of the foamed polyolefin layer, is specifically calcium carbonate, calcium hydroxide, magnesium hydroxide, aluminum hydroxide, phosphorus hydroxide, or the like. Aluminum oxide, talc, mica, clay, carbon black, white carbon, graphite, zeolite, barium sulfate, hydrous calcium silicate inorganic powder, phenol resin powder, ebonite powder, and other organic powders, glass fiber, pulp, Various fibers such as asbestos fibers are exemplified.

The amount of the filler is 5 to 30 parts by weight, preferably 10 to 20 parts by weight, based on 100 parts by weight of the resin. If the amount of the filler is too large, the moldability deteriorates. On the other hand, if the amount is too small, the rigidity of the obtained multilayer polyolefin sheet becomes insufficient or the sheet is deformed in a wavy shape, which is not preferable.

The filler-free polyolefin layer, which is the surface layer of the multilayer polyolefin sheet of the present invention, preferably does not contain any filler. The filler may be included as long as it does not adhere to the vicinity of the discharge port. The upper limit of the amount of the filler to be added at this time varies depending on the molding conditions and the resin used, but is about 5 parts by weight based on 100 parts by weight of the resin.

The thickness of each layer constituting the multilayer polyolefin sheet of the present invention and the thickness of the entire multilayer polyolefin sheet vary depending on the use of the multilayer polyolefin sheet and the like. In order to obtain preferable physical properties when used, the total thickness of the multilayer polyolefin sheet is 600 to 3000 μm, and the thickness of the expanded polyolefin layer is 400 μm.
２2800 μm, the filler-containing non-foamed polyolefin layer is 80 to 200 μm, the filler-free polyolefin layer is about 10 to 100 μm, and the thickness of the filler-containing non-foamed polyolefin layer is the thickness of the foamed polyolefin layer. And the thickness of the polyolefin layer substantially containing no filler is preferably about 0.5 to 5% of the thickness of the foamed polyolefin layer.

The multilayer polyolefin sheet of the present invention may be subjected to embossing, printing of a pattern or the like, or various surface treatments, if necessary, similarly to a conventional polyolefin sheet. When embossing, printing, or surface treatment is performed on the surface of the multilayer polyolefin sheet, it can be performed by the same means as a conventional polyolefin sheet.

[0019]

The multilayer polyolefin sheet of the present invention is formed by sequentially laminating a non-foamed polyolefin layer containing a filler and a non-foamable polyolefin layer substantially containing no filler on both sides of the foamed polyolefin layer, and thus has a high rigidity. Is strong, the feel is soft and lightweight, and the surface is colored,
It is also good when printing or embossing a picture or the like. Moreover, multilayer polyolefin sheet of the present invention,
Because it is formed by co-extrusion method, without polyolefine foam layer is deformed in a wave shape, it is possible to obtain a multilayer polyolefin sheet having a property such higher thickness precision, resin discharge portion during the extrusion With lump
There is no drawback that it is easy to wear, and there is little occurrence of defects in the manufacturing process.

[0020]

The present invention will be described in more detail with reference to specific examples.

Example 1 A foamable polypropylene composition shown in Table 1, a filler-containing non-foamable polypropylene composition shown in Table 2, and a non-filler-containing non-foamable polypropylene composition shown in Table 3 were kneaded. The laminate was extruded into five layers immediately before the T-die, extruded, and a filler-containing non-foamable polypropylene layer and a non-filler-containing non-foamable polypropylene layer were sequentially laminated on both sides of a foamed polypropylene layer. A multilayer polypropylene sheet was obtained. The multilayer polypropylene sheet has a foamed polypropylene layer having a thickness of 1240 μm, a filler-containing non-foamable polypropylene layer having a thickness of 100 μm,
The thickness of the non-filler-containing non-foamable polypropylene layer is 30μ
m, the expansion ratio of the expanded polypropylene layer was 2 times. Moreover, the obtained multilayer polypropylene sheet has no variation in thickness, has excellent surface smoothness, and has a density of 0.6 g /
It was light in weight and its feel was soft, yet it had sufficient rigidity to be used as a material for binder surface materials, document cases and book cases. When a pear-skinned embossed pattern was applied to the surface of the obtained multilayer polypropylene sheet, a clear embossed pattern was formed.

[Table 1] [Expandable polypropylene composition] Polypropylene block copolymer 100 parts by weight Blowing agent (sodium bicarbonate) 3 parts by weight

[Table 2] [Non-foamed polypropylene composition containing filler] Polypropylene homopolymer 100 parts by weight Filler (talc) 20 parts by weight

[Table 3] [Unfilled non-foamed polypropylene composition] Polypropylene homopolymer 100 parts by weight

Comparative Example 1 The foamable polypropylene composition shown in Table 1 was extruded from a T-die to obtain a foamed polypropylene sheet having a foaming ratio of 2 and a thickness of 1500 μm. The resulting foamed polypropylene sheet was lightweight, having a density of 0.45 g / cm3, and was soft to the touch, but had a variation in thickness, a rough surface, a binder covering material, a document case, a book case, etc. The stiffness was insufficient for use as a material for the steel.

Comparative Example 2 A non-expandable polypropylene composition shown in Table 2 was extrusion molded from a T-die to obtain a 1500 μm thick polypropylene sheet. Although the obtained polypropylene sheet had sufficient rigidity to be used as a material for a binder surface covering material, a document case, a book case, etc., it had a heavy density of 1.02 g / cm 3 and a hard feel. Was.

[0024]

Multilayer polyolefin sheet is issued of the present invention
Non-foaming containing filler on both sides of foam polyolefin layer
Polyolefin layer, substantially free of filler
Non-foamable polyolefin layers are sequentially laminated by co-extrusion
Therefore , while being lightweight and soft to the touch, it has high rigidity and high thickness accuracy. In addition, the surface properties are good, and clear printing, coloring, embossing, and the like can be performed.

Further, the method for producing a multi-layer polyolefin sheet of the present invention is easy to produce a multi-layer polyolefin sheet having a high rigidity, a high thickness accuracy, and a good surface property while being lightweight and soft to the touch. Can be made
The occurrence of defects in the manufacturing process is small.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI B29K 105: 04 105: 16 B29L 9:00

Claims (2)

(57) [Claims] 1. A resin 1 on both sides of a foamed polyolefin layer.
00 parts by weight of non <br/> onset Awapo Li olefin layer containing substantially no non-foamed polyolefin layer Contact and fillers containing from 5 to 30 parts by weight filler sequentially stacked to meet multilayer polyolefin sheet comprising , Foamed polyolefin layer, filler to 100 parts by weight of resin
A non-foamed polyolefin layer containing 5 to 30 parts by weight;
A non-foamed polyolefin layer containing substantially no filler
Multi-layer polyolefin sheet laminated by co-extrusion method
G. Wherein expandable polyolefin resin composition containing a foaming agent, non-foaming that is substantially free of non-expandable polyolefin resin composition and fillers containing from 5 to 30 parts by weight against filler 100 parts by weight of the resin sex Po Li olefin resin composition, and respectively melt-kneaded, containing a blowing agent originating
100 weight resin on both sides of the foamable polyolefin resin composition
Non-foamable poly containing 5 to 30 parts by weight of filler per part by weight
Substantially free of olefin resin composition and filler
The non-foamable polyolefin resin composition is sequentially laminated.
A method for producing a multi-layer polyolefin sheet, wherein the sheet is formed by a coextrusion method extruding from a T-die .