JP2006043901A - Laminate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laminate using a honeycomb structure made of paper, reduced in weight, having high rigidity, low in cost, excellent in recyclability and hard to form the warpage or bending caused by the absorption of moisture in air or the thermal expansion and contraction due to the temperature difference between the upper and under surfaces of the laminate. <P>SOLUTION: The laminate is characterized in that a stretched olefinic resin sheet is laminated at least on one side of the honeycomb structure made of paper (preferably, the stretched olefinic resin sheet is laminated on the honeycomb structure made of paper through a fibrous sheet). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a laminated body, and more particularly to a laminated body suitably used for a building material panel, a vehicle member panel, a civil engineering material panel, a kite or folding screen core material, and the like.

  Conventionally, as a material used for a panel for building material, a panel for vehicle member, a panel for civil engineering material, a material using a honeycomb structure is frequently used. For example, in Patent Document 1, a fiber-reinforced thermoplastic resin plate is laminated. At least one laminated body (1, 2) is laminated on the surface of the core material (3) having a honeycomb structure and integrated into a laminated molded product, and the fiber reinforced thermoplastic resin plate is reinforced. The volume content of the fiber is 30% or more and 85% or less, the core material (3) includes the fiber (3-1), and at least a portion of the surface in contact with the laminate (1, 2) is a fiber (3- A laminated molded product in which 1) is exposed is disclosed.

  However, even if the laminated molded product can be bonded to a core material having a honeycomb structure under low pressure, the material becomes expensive or heavy, and depending on the use conditions, Further, due to moisture absorption and thermal expansion and contraction, warping and bending may occur, and a lightweight and inexpensive laminate cannot always be obtained.

  In general, a laminate in which paper is laminated on both sides of a paper honeycomb structure is light, rigid and inexpensive, and is widely used as a laminate having excellent recyclability. Due to moisture absorption and thermal expansion and contraction due to a temperature difference between the front and back surfaces of the laminate, there has been a problem that warping and bending are likely to occur.

  In order to solve the above-mentioned problem of moisture absorption in particular, for example, a method of laminating paper on both sides of a paper honeycomb structure via a metal sheet has been studied, but a sufficient effect can always be obtained. In addition, there is a problem that recycling becomes difficult, for example, separation disposal is required.

JP-A-7-88888

  In view of the above-described conventional problems, the object of the present invention is a laminated body using a paper honeycomb structure, which is lightweight, highly rigid and inexpensive, excellent in recyclability, and capable of removing moisture in the air. An object of the present invention is to provide a laminate in which warpage or bending is unlikely to occur due to moisture absorption or thermal expansion / contraction due to a temperature difference between the front and back surfaces of the laminate.

  The laminate according to claim 1 is characterized in that the stretched olefin resin sheet is laminated on at least one side of a paper honeycomb structure.

  The laminated body according to claim 2 is the laminated body according to claim 1, wherein the stretched olefin resin sheet is laminated on the honeycomb structure via a fibrous sheet.

  A laminated body according to claim 3 is the laminated body according to claim 2, wherein the stretched olefin resin sheet and the fibrous sheet are laminated via a thermoplastic resin layer, and the fibrous sheet and the honeycomb structure are bonded. It is characterized by being laminated through an agent layer.

  The laminate according to claim 4 is the laminate according to claim 3, wherein the adhesive constituting the adhesive layer is an ethylene vinyl acetate adhesive.

Hereinafter, the present invention will be described in detail.
In the present invention, the stretched olefin resin sheet is a product obtained by rolling and / or stretching (hereinafter simply referred to as “stretching”) of a polyolefin resin sheet.

  The stretch ratio of the stretched olefin resin sheet is preferably 10 to 40 times, more preferably 15 to 35 times. If the rolling and / or stretching ratio is too small, sufficient tensile elastic modulus may not be exhibited, and thermal expansion and contraction may become too large. If the stretch ratio is too large, the sheet may be easily broken during stretch molding.

  As the olefin resin constituting the stretched olefin resin sheet, any olefin resin having sheet forming ability can be used, for example, high density polyethylene resin, medium density polyethylene resin, low density polyethylene resin, linear low density polyethylene. Resin, polypropylene resin, ethylene-propylene copolymer, ethylene-pentene-1 copolymer, ethylene-vinyl acetate copolymer, ethylene- (meth) acrylate copolymer, ethylene-vinyl chloride copolymer, ethylene -A propylene-butene copolymer etc. are mentioned, A high density polyethylene resin is used suitably.

If the density of the high-density polyethylene resin is small, the shape following property is not improved even if it is stretched, so 0.94 g / cm ³ or more is preferable.

  Also, the weight average molecular weight of the high density polyethylene resin is preferably 200,000 to 500,000 because the rigidity does not improve much even if stretched if it becomes too small, and molding and stretching becomes difficult if it becomes too large. (MI) is preferably 0.1 to 20 and more preferably 0.2 to 10 because of its excellent moldability.

  In the present invention, the high-density polyethylene may be used alone, but other polyolefins may be mixed in a proportion of 30 parts by weight or less with respect to 100 parts by weight of the high-density polyethylene. Examples of other polyolefins used in combination include low density polyethylene, ethylene-vinyl acetate copolymer, and polyvinyl acetate.

  Further, the high-density polyethylene may be cross-linked. In this case, it is preferable that the gel fraction of the resin sheet obtained is 20% or more.

  Any conventional known method may be adopted as the method for stretching the olefin resin sheet. However, when the olefin resin sheet is highly stretched 10 to 40 times, the olefin resin sheet is rolled and then stretched or stretched several times. A method of repeated multistage stretching is preferred.

  The rolling is a method in which an olefin-based resin sheet is supplied to a pair of rolls rotating in opposite directions and pressed to reduce the thickness of the sheet and extend, and the rolled sheet differs from the stretched sheet in that it is an olefin-based sheet. Since the resin is dense without being oriented, it is highly stretchable.

  The rolling temperature cannot be uniformly rolled when the temperature is low, and melt-cut when it is high. Therefore, the roll temperature during rolling is preferably in the range of "melting point-40 ° C" to the melting point of the olefin resin of the olefin resin sheet to be rolled. More preferably, it is “melting point−30 ° C.” to “melting point−5 ° C.” of the olefin resin.

  In the present invention, the melting point refers to the maximum point of the endothermic peak that accompanies melting of the crystal, which is recognized when thermal analysis is performed with a differential scanning calorimeter (DSC).

  If the rolling ratio is small, the subsequent stretching is burdened, and increasing the rolling ratio makes rolling difficult, so 4 to 10 times is preferable. In the present invention, the rolling ratio and the stretching ratio are values obtained by dividing the cross-sectional area of the sheet before rolling or stretching by the cross-sectional area of the sheet after rolling or stretching.

  The stretching may be any conventionally known method, and examples thereof include a method of stretching while heating with a heater or hot air by a roll stretching method or a zone stretching method.

  The stretching temperature cannot be uniformly stretched when the temperature is lowered, and the sheet melts and cuts when the temperature is increased. Therefore, the range of “melting point−60 ° C.” to the melting point of the olefin resin of the stretched olefin resin sheet is preferable, more preferably It is “melting point−50 ° C.” to “melting point−5 ° C.” of the base resin.

  Moreover, since the draw ratio after rolling is preferably 10 to 40 times as a whole, considering the rolling ratio, the overall draw ratio may be determined to be in this range, When the stretching after rolling is small, the mechanical strength is not improved, so it is preferably 2 times or more, more preferably 3 times or more. In addition, the whole draw ratio is a numerical value obtained by multiplying the draw ratio after rolling and the draw ratio after rolling.

  When the stretched olefin-based resin sheet is thin, the mechanical strength is lowered, and when it is thick, the stretched olefin-based resin sheet is easily cracked in the stretching direction. Therefore, the thickness is generally 0.05 to 1.5 mm, preferably 0.15 to 0.7 mm. is there.

  The laminate of the present invention is obtained by laminating the stretched olefin resin sheet on at least one side of a paper honeycomb structure. In this case, the stretched polyolefin resin sheet may be directly laminated on the honeycomb structure, but when the stretched olefin resin sheet is laminated on the honeycomb structure via the fibrous sheet, the paper honeycomb structure is formed. It is preferable at the point which the adhesiveness at the time of lamination | stacking improves.

The fiber sheet is not particularly limited as long as it is a sheet containing fibers, and examples thereof include non-woven fabrics including resin fibers and inorganic fibers, and resin felts, in addition to plant fibers such as paper and wood.
Among them, it is preferable that the fibrous sheet is paper because it is the same material as the paper honeycomb structure, and is excellent in adhesion at the time of lamination.

  In the above, a stretched olefin resin sheet and a fibrous sheet are laminated via a thermoplastic resin layer, and the fibrous sheet and a honeycomb structure are laminated via an adhesive layer. When it is, it is preferable at the point from which the laminated body in which each material was integrated firmly is obtained.

  The method for laminating the fibrous sheet on the stretched olefin resin sheet is not particularly limited. Usually, however, the stretched olefin resin sheet has poor adhesion to other materials. Laminated fibrous sheets laminated by laminating and crimping a plastic resin while being continuously extruded are laminated so that the thermoplastic resin side of the laminated fibrous sheet is in contact with the stretched olefin resin sheet, and then crimped while heating. Method, and a thermoplastic sheet is sandwiched between the fiber sheet and the stretched olefin-based resin sheet while being continuously extruded and pressure-bonded, and the fiber sheet is attached to the stretched olefin-based resin sheet via the thermoplastic resin layer. An extrusion lamination method for laminating is suitable. Among these, the latter method is more preferable in that a composite sheet that is firmly laminated and integrated can be easily obtained.

  A plurality of stretched olefin resin sheets or fibrous sheets are used as the composite sheet, and for example, a multilayer structure in which layers are alternately stacked may be used. Moreover, the structure laminated | stacked so that the extending | stretching direction of the extending | stretching olefin resin sheet might be orthogonal may be sufficient. The multilayer structure and the stacked structure described above are preferable in that the rigidity of the obtained stacked body is improved.

  The method of laminating the composite sheet and the honeycomb structure is not particularly limited, and for example, an adhesive layer is provided by applying an adhesive on one side of the honeycomb structure or placing a hot melt adhesive. A method of laminating and bonding so that the fiber sheet side of the composite sheet is in contact with the composite sheet may be used.

  In the above, the adhesive constituting the adhesive layer is not particularly limited, for example, cellulose adhesive, vinyl acetate adhesive, epoxy resin adhesive, cyanoacrylate adhesive, synthetic rubber adhesive, Examples include hydrocarbon adhesives and protein adhesives. Of these, the ethylene vinyl acetate adhesive is preferable because the adhesiveness to the composite sheet is improved.

  The honeycomb shape of the paper-made honeycomb structure in the present invention includes not only an aggregate of hexagonal cylinders but also all structures formed by combining a large number of flat plates or curved plates parallel to one common axis. That is, this honeycomb structure includes all of the cross-sectional shapes perpendicular to the common uniaxial axis, in which thin hexagons, squares, rectangles, rhombuses, equilateral triangles, circles, etc. have a continuous shape in a lattice pattern. Is. And they may be configured by combining strip-shaped flat plates, or may be formed integrally as a whole.

  The paper in the present invention is not particularly limited, and commonly used paper and Japanese paper are exemplified, and examples thereof include kraft paper, cardboard base paper, carton paper, cardboard, and chip paper.

  The thickness of the honeycomb structure is not particularly limited, but is thicker than the thickness of the laminated sheet in which the stretched olefin resin sheet, the fibrous sheet, and the thermoplastic resin film are used in terms of a balance between lightness and rigidity. It is preferable that the thickness is 5 to 50 mm.

(Function)
According to the present invention, since a specific olefin resin sheet, a fibrous sheet, and a paper honeycomb structure are used, it is excellent in recyclability, and the olefin resin sheet is stretched to a high level. The thermal stretchability, which is a defect of the olefin resin sheet, is improved, and when laminated on a paper honeycomb structure, the honeycomb structure is highly reinforced and the dimensional stability of the laminate can be improved. .

  In general, the polyolefin-based material may have insufficient adhesion to other materials, but by using the above-mentioned stretched polyolefin-based resin sheet and fibrous sheet, the adhesion to the honeycomb structure can be improved. And an excellent laminate can be obtained.

  According to the present invention, the stretched olefin-based resin sheet is laminated on at least one side of the paper honeycomb structure, so that it is lightweight, highly rigid and inexpensive, excellent in recyclability, and excellent in dimensional stability, It is possible to provide a laminate that is less likely to warp or bend.

  When the stretched olefin-based resin sheet is laminated on the honeycomb structure via the fibrous sheet, the adhesiveness at the time of lamination on the honeycomb structure is improved, and the above effect is further ensured.

  The above effect is further ensured when the stretched olefin-based resin sheet and the fibrous sheet are laminated via a thermoplastic resin layer, and the fibrous sheet and the honeycomb structure are laminated via an adhesive layer. It will be a thing.

  When the stretched olefin resin sheet and the fibrous sheet are laminated via a thermoplastic resin layer, and the fibrous sheet and the honeycomb structure are laminated via an adhesive layer, the respective materials are firmly integrated. When the laminated body obtained is obtained and the adhesive constituting the adhesive layer is an ethylene vinyl acetate adhesive, the above-described effect is further ensured.

FIG. 1 is a schematic cross-sectional view showing an example of a laminate according to the present invention.
The laminated body 10 is a paper honeycomb structure 5 in which a composite sheet 6 in which a stretched olefin resin sheet 1 and a fibrous sheet 3 are laminated via a thermoplastic resin layer 2 is provided with an adhesive layer 4 on both sides. The composite sheet 6 is laminated and bonded so that the fiber sheet 3 side of the composite sheet 6 is in contact with both surfaces.

Hereinafter, the present invention will be described more specifically by showing Examples and Comparative Examples.
In addition, this invention is not limited only to the following Example.

Example 1
After supplying high density polyethylene (“HY540” manufactured by Nippon Polychem Co., Ltd.) to the same-direction biaxial kneading extruder (Plastics Engineering Laboratory) and melt-kneading at a resin temperature of 200 ° C., the melt-kneaded product is brought to a roll temperature of 110 ° C. The sheet was formed into a sheet having a width of 250 mm and a thickness of 2.2 mm using a controlled calender molding machine and wound up. This high-density polyethylene sheet was rolled at a rolling ratio of 10.2 times using a rolling molding machine (manufactured by Sekisui Koki Co., Ltd.) heated to 120 ° C. to obtain a PE rolled sheet having a width of 250 mm and a thickness of 215 μm.

The above-mentioned PE rolled sheet and kraft paper (weight per unit area 75 g / m ² ) are bonded while being laminated via low density polyethylene (LD) by an extrusion laminating method, and a PE laminated sheet (PE rolled sheet layer 215 μm, LD layer 15 μm, Kraft paper layer 75 g / m ² ) was obtained.

Next, about 50 g / m ² of vinyl acetate adhesive was applied to both sides of a paper honeycomb (“Roll Core” manufactured by Shin Nihon Core Co., Ltd., thickness 10 mm) as a paper honeycomb structure. The sheet was laminated on both sides so that the kraft paper side was in contact with the paper honeycomb, and pressure-bonded at a pressure of 1.0 kg / cm ² to obtain a laminate.

(Example 2)
The PE rolled sheet obtained in the same manner as in Example 1 was further stretched 1.7 times with a multi-stage stretching machine to obtain a PE stretched sheet having a total magnification of 17.3 times, a width of 190 mm, and a thickness of 165 μm. A laminate was obtained in the same manner as in Example 1 except that the obtained PE stretched sheet was used instead of the PE rolled sheet.

(Comparative Example 1)
A laminated body was obtained in the same manner as in Example 1 except that chip paper (weight per unit area: 430 g / m ² ) was used instead of the PE laminated sheet.

The following evaluation was performed about the said Example and comparative example.
(Hygroscopic linear expansion)
A sample having a width of 100 mm and a length of 1820 mm was cut out from the obtained laminate, and allowed to absorb moisture at room temperature (23 ° C.) in a constant temperature and humidity condition of humidity 50% RH for 24 hours. Was measured.
(Lamination of laminate)
The obtained laminate was cut to a width of 100 mm and a length of 1820 mm, and the laminate was placed on a hot plate at about 60 ° C. in a constant temperature and humidity state at room temperature (23 ° C.) and humidity of 50% RH. The amount of warpage (lifting amount) of the part was measured, and the warpage of the laminate was evaluated.

  As is clear from Table 1, the laminate of the present invention has a smaller hygroscopic linear expansion than that of the conventional one, and it has been found that the laminate is less likely to warp due to heat.

It is a schematic cross section which shows an example of the laminated body in this invention.

Explanation of symbols

1 Stretched olefin resin sheet 2 Thermoplastic resin layer 3 Fibrous sheet (paper)
4 Adhesive Layer 5 Paper Honeycomb Structure 6 Composite Sheet 10 Laminate

Claims (4)

  A laminate comprising a stretched olefin resin sheet laminated on at least one side of a paper honeycomb structure.   The laminate according to claim 1, wherein the stretched olefin-based resin sheet is laminated on the honeycomb structure via a fibrous sheet.   The laminate according to claim 2, wherein the stretched olefin resin sheet and the fibrous sheet are laminated via a thermoplastic resin layer, and the fibrous sheet and the honeycomb structure are laminated via an adhesive layer. body.   4. The laminate according to claim 3, wherein the adhesive constituting the adhesive layer is an ethylene vinyl acetate adhesive.

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