JP2001315198A - Stretched polyolefin resin sheet for shaping and molding, and method for manufacturing polyolefin resin molded object using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a stretched polyolefin resin sheet for shaping and molding having strength and elastic modulus corresponding to those of a glass fiber reinforced composite material, capable of being recycled perfectly, having good handleability and excellent in the followability to a curved surface or the like in shaping and molding, and a method for manufacturing a polyolefin resin molded object using the same. SOLUTION: The stretched polyolefin resin sheet for shaping and molding is formed by unidirectionally stretching a polyolefin resin by 10 times or more and slits with a width of at least 2 mm or more are formed in the stretched polyolefin resin sheet for shaping and molding in the stretching direction thereof at places corresponding to regions to which curved parts are added.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stretched drawn polyolefin resin sheet having drawability and a process for producing a polyolefin resin molded article using the same.

[0002]

2. Description of the Related Art Currently, civil engineering applications, housing equipment, machine parts,
Plastic molded products are used in a wide variety of applications, such as electric parts and sporting goods. Among these, many products emphasize mechanical properties, and therefore, a resin alone cannot satisfy required quality, and there are many products in which reinforcing fibers are compounded. As the reinforcing fibers, carbon fibers, glass fibers, and the like occupy most. Reinforced fibers are available in the form of short fibers, long fibers, rovings, mats (continuous
Chop), etc., which are integrated with a thermosetting resin / thermoplastic resin binder to develop strength.

[0003] Molded products having a drawn shape include press molding (SMC / BMC), stamping molding, hand lay-up, spray-up, injection molding, RIM molding, and the like.
Cast molding and the like are used. Among these, as a molding material that can be deep drawn and has little variation in physical properties considered to be due to fiber orientation due to the flow of resin during molding,
For example, Japanese Patent Application Laid-Open No. 07-164439 proposes a glass fiber mat for reinforcement.

The glass fiber mat for reinforcement described in Japanese Patent Application Laid-Open No. H07-164439 has a structure in which continuous filaments of glass are bonded with a binder. The shape can be maintained by the binder. Furthermore,
This preform is impregnated with a resin by injection or the like, and cured and integrated.

However, molded articles reinforced with glass fibers and the like have poor recyclability, and when incinerated, must be incinerated at high temperatures, which not only adversely affects the durability of the incinerator but also has a problem of glass residue. Actually, it is actually landfilled.

[0006] On the other hand, a fiber drawn at a high magnification mainly composed of polyolefin has a high rigidity comparable to that of glass fiber. It is comparable to a molded article and is excellent in recyclability because it does not contain fibers of another composition.

At present, fibers drawn at a high magnification are commercially available. However, in order to obtain a molded product, an adhesive layer must be interposed between the fibers, and as a result, it is necessary to increase the volume content of the fibers. Has a limit and has problems in strength and rigidity of the molded article. In addition, since it is a fiber, there is also a problem that the handleability at the time of molding is poor. On the other hand, a sheet stretched at a high magnification has problems of poor elongation and difficulty in following a curved surface, and is not suitable as a molding material for a deformed product.

[0008]

SUMMARY OF THE INVENTION In view of the above, the present invention has strength and elasticity comparable to those of glass fiber reinforced composite materials, is completely recyclable, and has good handling properties. An object of the present invention is to provide a stretched polyolefin resin sheet for forming and shaping, which has excellent followability to a curved surface or the like in a forming shape, and a method for producing a polyolefin resin molded article using the same.

[0009]

The present invention relates to a stretched polyolefin resin sheet for shaping formed by stretching a polyolefin resin at least 10 times in a uniaxial direction, wherein the stretched polyolefin resin sheet for shaping comprises: A stretched polyolefin resin sheet for shaping, which has a width of at least 2 mm and is slit in a stretching direction at a portion corresponding to a portion to which a curved portion is added.

[0010] The present invention is also a method for producing a polyolefin resin molded article in which a plurality of the above-mentioned stretched shaped polyolefin resin sheets for forming are stacked at an arbitrary angle and arranged, and then pressed and heated and bonded by a forming mold. . Hereinafter, the present invention will be described in detail.

The present invention is a stretched polyolefin resin sheet for shaping formed by stretching a polyolefin resin at least 10 times in a uniaxial direction. The polyolefin resin may be a homopolymer such as polyethylene, polypropylene, 1-butene and 1-pentene, a copolymer having a copolymerization component of 10% by weight or less, or a vinyl monomer such as vinyl acetate. , Vinyl alcohol, vinyl chloride, acrylic acid and the like, preferably 10% by weight or less, may be copolymerized.

In the present invention, among the above polyolefin resins, a high-density polyethylene monomer is preferably used. When using high-density polyethylene, its density is
It is preferably 0.94 g / cm ³ or more. If the density is low, the strength and elastic modulus cannot be expected to be much improved even after stretching. Also, its melt index (MI)
Is preferably from 0.1 to 10, more preferably from 1 to 7. If the melt index is smaller than 0.1, a load is imposed on a molding machine such as an extruder, and if it is larger than 10, molding becomes difficult. In the case of the present invention, the above polyethylene may be used alone, or other polyolefin-based resins, for example, polypropylene, low-density polyethylene,
It may be one containing 10% by weight or less of an ethylene-vinyl acetate copolymer, polyvinyl acetate, polyvinyl alcohol, or the like. Here, the melting point means a maximum point of an endothermic peak accompanying melting of a crystal, which is observed when a thermal analysis is performed by a differential scanning calorimeter (DSC) or the like.

The method for producing a stretched polyolefin resin sheet in the present invention is not particularly limited. For example, the above polyolefin resin is extruded into a sheet by a T-die or the like using an extruder, and then the obtained extruded resin is extruded. It can be performed by stretching and orienting the sheet-like material in a uniaxial direction at least 10 times by rolling and stretching.

The above-mentioned roll forming is a method in which the clearance of a pair of rolls whose temperature is controlled by heating is made narrower than the thickness of a sheet-like material, and is extended in a uniaxial direction. The stretching is usually performed by a roll stretching method, a gel stretching method, a zone stretching method or the like, and is not particularly limited. Here, when the thickness of the sheet-like material extruded by a T-die or the like is 0.5 mm or more, a stretched polyolefin resin sheet can be stably obtained by performing stretch forming after performing roll forming.

[0015] The above-mentioned stretched polyolefin resin sheet comprises
It is preferable that the film is stretched to 0 times or more. If the stretching ratio is less than 10 times, it is difficult to expect improvement in tensile properties by stretching. More preferably, it is 15 times or more. The higher the draw ratio, the more the physical properties can be improved, but from the viewpoint of molding stability, it is usually about 60 times.

In order to obtain a molded product in a shaping shape which will be described in detail later, it is necessary to impart thermal adhesiveness to the stretched polyolefin resin sheet. May be inserted, but from the viewpoint of moldability, it is preferable to provide a thermal adhesive layer on the stretched polyolefin resin sheet. The method for providing the thermal adhesive layer is not particularly limited, for example,
There are a method of thermally laminating a heat-sealing resin film with a heating roll, a method of surface-coating a heat-adhesive resin, and the like, and the former is more simply used.

The stretched polyolefin resin sheet for shaping according to the present invention has a width of at least 2 mm and is slit in the stretching direction at a portion corresponding to a portion where a curved portion is to be added. The method for slitting the stretched polyolefin resin sheet in the stretching direction is not particularly limited. For example, the slitting can be performed by making a cut using a slit blade, a cutter blade, or the like.

When the drawn polyolefin resin sheet is slit, the fibers forming the sheet are slightly cut. Therefore, if it is less than 2 mm, the amount of cut fibers cannot be ignored with respect to the slit width. There is a possibility that the bending properties and the tensile properties of the molded article to be obtained are reduced.
Therefore, it is preferable that the slit width be 2 mm or more, and 5 mm or more. In addition, the slit width means the width between the cut lines. The slit width and the portion are arbitrarily determined according to the shape of the molded product, and the slit corresponding to the curved portion may be slit to a required length. For this reason,
There is no particular upper limit on the slit width.

In the method for producing a polyolefin resin molded article of the present invention, a plurality of the above-mentioned stretched polyolefin resin sheets for shaping are stacked at an arbitrary angle, arranged, and bonded by pressing and heating using a shaping mold. In such a manufacturing method, FIG.
And the hot press molding method shown in FIG. 3 can be used, and can be selected according to the purpose.

In the above hot press molding method, in order to heat-melt the adhesive layer between the stretched polyolefin resin sheets and integrate them by shaping, the shaping mold is set at a temperature higher than the melting point of the adhesive layer.
Alternatively, the stretched polyolefin resin sheet needs to have a melting point of the adhesive layer or higher. At this time, if the temperature of the stretched polyolefin resin sheet is equal to or higher than the melting point, the orientation of molecules due to stretching may be relaxed, and the physical properties may be reduced. for that reason,
The temperature of the shaping mold is preferably a temperature lower than the melting point of the polyolefin resin sheet. More preferably, the temperature is adjusted to a temperature lower than the melting point by 5 ° C. or less.

In the above injection molding method, it is necessary to adjust the temperature of the injection resin and the temperature of the mold so that the temperature of the adhesive layer is equal to or higher than the melting point. In addition, since the stretched polyolefin resin sheet may flow due to the flow of the injection resin, it is preferable to perform injection molding by setting a preform preformed on a molded body in a mold using the above hot press molding method.

By using the stretched polyolefin resin sheet for shaping according to the present invention, since the restraining force in the sheet width direction at the curved portion is eliminated, the followability to the curved surface and the corner portion is improved, as shown in FIG. A molded article can be obtained. In addition, since the obtained molded article is in a completely tensioned state of the polyolefin resin sheet,
A molded article that can effectively utilize the strength and elastic modulus of the sheet. Such a molded article is excellent in thermal dimensional stability, water resistance, chemical resistance, and the like, and has characteristics that it is easy to recycle.

[0023]

EXAMPLE 1 High-density polyethylene having a weight-average molecular weight of 3.3 × 10 ⁵ and a melting point of 135 ° C. (manufactured by Nippon Polychem, grade: HY)
540) with the same-direction twin-screw kneading extruder (Ikegai
CM30) and melt kneading at a resin temperature of about 200 ° C,
Width 3 using a calendering machine with roll temperature controlled to 90 ° C
The sheet was formed into a sheet having a thickness of 00 mm and a thickness of 3.3 mm, wound up, and then rolled 10 times using a hot roll (manufactured by Kodaira Seisakusho Co., Ltd., roll diameter 6 inches) heated to 120 ° C. The obtained stretched raw fabric was stretch-formed at a total stretch ratio of 25 times using a hot-air vertical uniaxial stretching machine controlled at 100 ° C. At this time,
The stretched sheet had a thickness of 0.2 mm and a width of 200 mm.

A heat-sealing resin sheet made of a linear low-density polyethylene resin having a melting point of 120 ° C. and a thickness of 0.03 mm was laminated and integrated on the obtained stretched sheet by a heat laminating apparatus. The laminating roll temperature at this time was 130 ° C.
Met. Next, this stretched sheet was slit with a cutter blade at a width of 10 mm and a length of 200 mm. The slit site was as shown in FIG. A total of 25 of the obtained sheets were alternately laminated in the 0/90 ° direction, and placed on a shaping mold of the molded article in FIG. 4, and then laminated and integrated by a hand press molding machine. At this time, the temperature of the press board surface was 125 ° C., the press pressure was 0.2 MPa, and the press time was 10 minutes. After cooling for 2 minutes, the mold was removed. The shape of the obtained molded product was 6 mm in thickness, 200 mm in length and width, 100 mm in upper surface curvature, 15 mm in curved surface-plane curvature, and was good without wrinkles.

Comparative Example 1 A molded product was obtained in the same manner as in Example 1 except that the stretched sheet obtained in Example 1 was used as a shaping material without slitting. The obtained molded product had more wrinkles at the corners, and the wrinkles were uneven in thickness, and the other surface was poor in adhesion due to insufficient pressure.

[0026]

The stretched polyolefin resin sheet for shaping according to the present invention has higher strength and elastic modulus than the above-mentioned structure,
In addition, it has excellent recyclability, good handling properties, and excellent ability to follow a curved surface or the like in a formed shape.

[Brief description of the drawings]

FIG. 1 is a view showing a stretched shaped polyolefin resin sheet for shaping used in Example 1. FIG.

FIG. 2 is a conceptual diagram for explaining an injection molding method used in the present invention.

FIG. 3 is a conceptual diagram for explaining a hot press molding method used in the present invention.

FIG. 4 is a view showing an example of the shape and dimensions of a formed product obtained in the present invention.

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Claims (2)

[Claims] 1. A stretched shaped polyolefin resin sheet formed by stretching a polyolefin resin at least 10 times in a uniaxial direction, wherein the stretched shaped polyolefin resin sheet corresponds to a portion where a curved portion is to be added. A stretched polyolefin resin sheet for forming shaping, characterized in that a slit is formed in a stretching direction at least in a width of 2 mm or more at a portion to be formed. 2. A polyolefin resin molding, wherein a plurality of the stretched polyolefin resin sheets for forming and shaping according to claim 1 are stacked at an arbitrary angle and arranged, and are pressurized and heated and bonded by a shaping mold. How to make the body.