JP2002046222A - Sheet for thermal welding, composite molded article using the same and manufacturing method of the article - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sheet for thermal welding intended for thermally welding a molded article of polyolefin and a molded article of polyoxymethylene excellently, and further a composite molded article using this sheet and a manufacturing method of the article. SOLUTION: The sheet for thermal welding is formed of a binding layer (2), a polyolefin layer (3) provided on one surface of the binding layer (2) and a polyoxymethylene layer (4) provided on the other surface this layer, and the binding layer (2) is constituted of a modified polyolefin having a functional group. The molded article of the polyolefin and that of the polyoxymethylene are thermally welded by hot plate welding with the sheet interlaid.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat welding sheet for heat welding a polyolefin molded article and a polyoxymethylene molded article, a method for producing a composite molded article using the same, and a composite molded article obtained by the method. About goods.

[0002]

2. Description of the Related Art In general, a molded article made of a thermoplastic resin has been molded by a single molding means using a single resin. On the other hand, in recent years, in order to obtain a molded product having a complicated shape that cannot be molded by a single molding means, or to obtain a molded product that makes full use of the individual characteristics of various resins, a composite molded product has been developed. There is a movement. As one method for obtaining such a composite molded article, individual molded articles constituting the composite molded article are molded in advance, and these are heat-welded and joined and integrated. Among molded articles made of resin materials, composite molded articles that can be practically used have been obtained. However, the compatibility between different resins is poor, and it has been difficult to obtain a composite molded product having a sufficient welding strength even when a molded product made of different resins is thermally welded and joined and integrated. Among them, polyolefins and polyoxymethylenes represented by polyethylene and polypropylene are typical of resins with poor compatibility and low reaction activity.A molded product made of polyoxymethylene and a molded product made of polyolefin are joined by heat welding. It was impossible to obtain a composite molded article. In order to improve the weldability between molded articles made of such dissimilar materials, it has been studied to heat weld through a heat welding sheet according to the combination of the respective resins. No heat-sealing sheet has been known so far which can weld a molded article composed of a product and a polyolefin with sufficient strength.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a heat-sealing sheet for favorably heat-sealing a molded article made of polyolefin and a molded article made of polyoxymethylene. And a method for producing the same.

[0004]

Means for Solving the Problems The present inventors comprise a bonding layer, a polyolefin layer provided on one side of the bonding layer, and a polyoxymethylene layer provided on the other side of the bonding layer, wherein the bonding layer has a functional group. It has been found that such a problem can be solved by using a heat welding sheet made of a modified polyolefin, and the present invention has been completed.

That is, a first aspect of the present invention is a bonding layer (2),
Thermal welding comprising a polyolefin layer (3) provided on one side and a polyoxymethylene layer (4) provided on the other side of the bonding layer (2), wherein the bonding layer (2) is made of a modified polyolefin having a functional group. Provide a sheet for use. A second aspect of the present invention provides the first heat-sealing sheet of the present invention, wherein the modified polyolefin of the bonding layer (2) is a modified polyethylene or a modified polypropylene. A third aspect of the present invention is that the modified polyolefin of the bonding layer (2) is an unsaturated carboxylic acid,
Modified by one or more selected from the group consisting of unsaturated carboxylic anhydrides, isocyanate group-containing polymerizable unsaturated compounds, epoxy group-containing polymerizable unsaturated compounds, hydroxy group-containing polymerizable unsaturated compounds and derivatives thereof. The first or second heat welding sheet of the present invention is provided. A fourth aspect of the present invention provides the heat-sealing sheet according to the first or second aspect, wherein the modified polyolefin of the bonding layer (2) is modified with maleic anhydride. The fifth of the present invention
Provides the heat-sealing sheet according to any one of the first to fourth aspects of the present invention, wherein the polyolefin layer (3) is made of polyethylene or polypropylene. A sixth aspect of the present invention is that the polyoxymethylene layer (4) is made of a polyoxymethylene homopolymer or a polyoxymethylene copolymer.
The heat-sealing sheet according to any one of the above, is provided. According to a seventh aspect of the present invention, there is provided the heat-sealing sheet according to any one of the first to sixth aspects of the present invention, which is used as a welding layer between a molded article (B) made of polyolefin and a molded article (C) made of polyoxymethylene. provide. According to an eighth aspect of the present invention, there is provided the heat welding sheet according to any one of the first to seventh aspects, wherein the heat welding is performed by hot plate fusion. According to a ninth aspect of the present invention, a molded article made of polyoxymethylene and a molded article made of a polyolefin are heat-bonded through the heat-sealing sheet using any one of the heat-welding sheets of the first to seventh aspects of the present invention. Provided is a method for producing a composite molded article, which is characterized by being welded and integrated. According to a tenth aspect of the present invention, a molded article made of polyoxymethylene and a molded article made of a polyolefin are heat-sealed via the heat-welding sheet using the heat-welding sheet of any one of the first to seventh aspects of the present invention. The present invention provides a composite molded product which is made to be integrated. Hereinafter, the present invention will be described in detail.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Heat-welding sheet (A) The heat-welding sheet (A) of the present invention comprises a tie-layer.
Also called. ) 2, a polyolefin layer 3 provided on one surface of the bonding layer 2, and a polyoxymethylene layer 4 provided on the other surface of the bonding layer 2.

The bonding layer 2 is made of a modified polyolefin (a) having a functional group. The polyolefin used for the modified polyolefin (a) is high-pressure polyethylene (LDPE), which is produced by a gas phase method, a solution method, a liquid phase slurry method, etc. using a Ziegler catalyst, a Phillips catalyst, or a metallocene catalyst. Various linear high density polyethylene (HDPE), polypropylene, medium density polyethylene (MDPE), etc .; linear low density polyethylene (L
LDPE) and ultra low density polyethylene (VLDPE, UL)
DPE) and the like; ethylene-propylene random copolymers or block copolymers, and ethylene / α-olefin copolymers such as low crystalline ethylene / butene-1 random copolymer (EBM). As the α-olefin, 1-butene, 1-hexene, 4-methyl-1-pentene, 1-
Octene, 1-decene and the like. Preferably, polyethylene or polypropylene is modified.

Examples of the modifier for imparting a functional group to the polyolefin chain include unsaturated carboxylic acids, unsaturated carboxylic anhydrides or derivatives thereof, such as (meth) acrylic acid, maleic acid, fumaric acid, itaconic acid and citraconic acid. Or derivatives thereof such as anhydrides, amides, imides and esters; hydroxy-containing polymerizable unsaturated compounds such as hydroxyalkyl (meth) acrylate; epoxy-group containing polymerizable unsaturated compounds such as 1-vinyl-3,
4-epoxycyclohexene, 3,4-epoxycyclohexylmethyl (meth) acrylate and the like; isocyanate group-containing polymerizable unsaturated compounds such as isocyanate-modified (meth) acrylate and the like. A particularly preferred modifier is maleic anhydride. The modifier may be copolymerized during the production of the polyolefin, or may be grafted to the polyolefin. The amount of the modifier is from 0.01 to 20% by weight, preferably from 0.1 to 20% by weight, based on the polyolefin.
10% by weight.

In the bonding layer 2, the above-mentioned modified polyolefin (a) may be used alone, but if necessary, an adhesive (b) or another polymer (c) may be added. Examples of the pressure-sensitive adhesive (b) include petroleum resins, rosin-based resins, terpene-based resins, and hydrogenated products thereof. As the petroleum resin, for example, aliphatic petroleum resin,
Examples thereof include aromatic petroleum resins, copolymers thereof, and hydrogenated products thereof. As rosin resin
Examples include natural rosin, polymerized rosin and derivatives thereof, for example, pentaerythroester rosin, glycerin ester rosin and hydrogenated products thereof. Examples of the terpene-based resin include polyterpene-based resins, terpene-phenol-based resins, and hydrogenated products thereof. As the other polymer (c), a block copolymer having at least one polymer block mainly composed of a vinyl aromatic compound and at least one polymer block mainly composed of a conjugated diene compound, or a block copolymer thereof. And hydrogenated products. These are represented by the general formulas AB; ABA; BA-
BA: a block copolymer represented by ABABA or the like (wherein A represents a polymer block mainly composed of a vinyl aromatic compound exhibiting thermoplasticity; Represents a polymer block mainly composed of a conjugated diene compound exhibiting elastomer properties, or a hydrogenated product of the polymer block). Examples of the compound mainly composed of the vinyl aromatic compound constituting the polymer block portion A include styrene, α-methylstyrene, vinyltoluene and the like, or a mixture thereof. Examples of the conjugated diene compound include butadiene and isoprene. 1,3-pentadiene, or a mixture thereof. As the other polymer (c), ethylene / vinyl acetate or a saponified product of ethylene / vinyl alcohol and the like; ethylene / α-olefin copolymer and the like can also be used.

[0010] The thickness of the bonding layer 2 is 10 µm to 1 mm, preferably 0.05 to 0.5 mm.

As the resin used for the polyolefin layer 3, high-pressure polyethylene (LDPE); a Ziegler catalyst, a Phillips catalyst, or a metallocene catalyst;
Various linear high-density polyethylene (HDPE), polypropylene, medium-density polyethylene (MDPE), linear low-density polyethylene (LLDPE), ultra-low High-density polyethylene (VLDPE or ULDPE); ethylene-α-olefin copolymers such as ethylene-propylene random copolymer or block copolymer, and low-crystalline ethylene-butene-1 random copolymer (EBM); As the α-olefin, 1-butene, 1-hexene, 4-methyl-
Examples thereof include 1-pentene, 1-octene, 1-decene and the like. These resins forming the polyolefin layer 3 are preferably of high viscosity in consideration of the manufacturability of the sheet for heat welding, and have an MFR (based on JIS K7210, 190 ° C.,
2.16N) is preferably 10 g / 10 min or less.
The resin used for the polyolefin layer 3 may be the same as or different from the polyolefin for the modified polyolefin used for the bonding layer 2. The modified polyolefin itself may be used. The thickness of the polyolefin layer 3 is 10 μm to 5 mm, preferably 0.1 to 2 mm.

As the resin used for the polyoxymethylene layer 4, a polyoxymethylene homopolymer or copolymer is used. As the polyoxymethylene copolymer, those in which oxyalkylene groups such as oxyethylene groups or oxybutylene groups are polymerized randomly or in blocks can be used. Comonomers used in the copolymer include ethylene oxide, dioxolane, butanediol formal, diethylene glycol formal, trioxolane, and the like. Further, it may have a branched or crosslinked structure obtained by adding a small amount of a component that forms a branched or crosslinked structure, and may have a terminal or an alkylene oxide addition product to an alcohol. Although these polyoxymethylenes used in the present invention are not particularly limited, from the viewpoint of productivity of the heat-weldable sheet, the MFR (190 ° C., 2.16
N) is preferably 5 g / 10 min or less. The thickness of the polyoxymethylene layer 4 is 10 μm to 5 mm, preferably 0.1 to 2 mm.

The heat-sealing sheet (A) of the present invention comprises a bonding layer 2 and a polyolefin layer 3 and a polyoxymethylene layer 4 provided on both sides thereof. be able to. The heat welding sheet (A) has a thickness of 30 μm to 10 mm, preferably 0.1 μm to 10 μm.
It is 1 to 5 mm, particularly preferably 0.5 to 2 mm. If the thickness of the heat welding sheet is too small, the welding strength becomes insufficient, and if it is too thick, the productivity of the sheet and the welding processability using the sheet become poor. In order to obtain a sufficient welding strength, it is important that the heat-welding sheet (A) has a high interlayer peeling strength, and it is preferably 10 kgf / cm ² or more.

The heat-welding sheet (A) has a polyolefin layer 3 on the molded article (B) side composed of polyolefin and a polyoxymethylene layer 4 on the molded article (C) side composed of polyoxymethylene. Through
The molded article (B) composed of polyolefin and the molded article (C) composed of polyoxymethylene can be used very effectively to obtain a composite molded article by heat welding. Molded Article Made of Polyolefin (B) Examples of the resin constituting the molded article made of polyolefin include various polyethylenes, polypropylenes, ethylene-propylene random copolymers or block copolymers, and low-crystalline ethylene-butene-1.
Examples include an ethylene / α-olefin copolymer such as a random copolymer. The resin used for the polyolefin molded article (B) may be the same as or different from the polyolefin used for the polyolefin layer 3 of the heat welding sheet. In order to obtain higher welding strength, it is preferable that they are the same. The molded article made of polyolefin may be a single material, a laminated article having the above-mentioned polyolefin in the outermost layer, or a film or sheet. Molded product (B)
Is not limited.

Molded Article Made of Polyoxymethylene (C) The molded article made of polyoxymethylene may be a single material or a laminated article having the polyoxymethylene in the outermost layer. The material of the molded article made of polyoxymethylene may be the same as or different from the polyoxymethylene used for the polyoxymethylene layer 4 of the heat welding sheet. Further, the shape of the molded product (C) is not limited.

The heat welding sheet (A) of the present invention can be used for hot plate welding. For example, a hot plate is brought into contact with a molded product (B) made of polyolefin and a molded product (C) made of polyoxymethylene, each of them is melted to a certain thickness, the hot plate is removed, and a heat welding sheet (A)
Is placed on any molded product, for example, molded product (B),
Another molded product, for example, the molded product (C) is put thereon, and the molded product (B) and the molded product (C) are pressed and thermally welded.
The heat welding between each molded product and the heat welding sheet (A) is 1
It can be performed in stages or in two or more stages. For example, in the above example, a hot plate is brought into contact with the molded article (B), a sheet for heat welding is welded, and then both the molded article (C) and the molded article (B) on which the sheet for heat welding is welded are heated. After contacting the board,
A crimping method can be adopted. The temperature of the hot plate and the contact time with the hot plate may be different between the first stage and the second stage in consideration of heat welding properties. Heat welding sheet (A)
Can be used in the form of, for example, a packing connecting the tubular molded body parts.

The usable temperature range of the heat welding sheet is 15
It is 0-300 degreeC, Preferably it is 180-280 degreeC.

The heat welding sheet of the present invention is suitably used for producing a composite molded article in which a molded (part) article composed of polyoxymethylene and a molded (part) article composed of polyolefin are joined and integrated. It can be used for various types of composite molded products that make use of the characteristics of each resin.
For example, a gasoline tank obtained by blow molding a three-layer film having a high-density polyethylene layer as an outermost layer and an ethylene-vinyl acetate copolymer as a barrier layer, and a polyoxymethylene fuel for supplying gasoline It can be used for heat welding with a cut valve.

[0019]

EXAMPLES The present invention will now be described specifically with reference to examples, but the present invention is not limited to these examples.

[Examples 1 to 8 and Comparative Examples 1 to 6] In the examples, the heat-sealing sheet (A) was prepared by the method described below.
Then, using the sheet (A) for heat welding, a heat-welded composite molded article (10) was manufactured. on the other hand,
As a comparative example, a composite molded product (10 ') directly heat-sealed without using the heat-welding sheet (A) was manufactured.

[Production of heat-welding sheet (A)] Each of the following resin materials is extruded into a sheet by a multi-layer extruder under the following production conditions and laminated and laminated.
By pressing, a sheet (A) for heat welding was prepared. The thickness of the obtained heat welding sheet (A) was about 2 mm. (Resin material used) Binding layer (2): Modified polyethylene (Modic F ^TM 2
500K (manufactured by Mitsubishi Chemical Corporation)) Polyolefin layer (3): high-density polyethylene (HD5
48B (manufactured by Idemitsu Petrochemical Co., Ltd.) Polyoxymethylene layer (4): polyoxymethylene copolymer (Duracon ^™ M25-44 (manufactured by Polyplastics Co., Ltd.)) (Production conditions for heat welding sheet (A)) Etc.) Bonding layer (2): cylinder temperature 190 ° C., sheet thickness 8
0 μm polyolefin layer (3): cylinder temperature 200 ° C., sheet thickness 1 mm polyoxymethylene layer (4): cylinder temperature 200
℃, sheet layer 1mm

[Production of composite molded article] Polyoxymethylene (Duracon ^™ M90-7 manufactured by Polyplastics Co., Ltd.)
1) and high-density polyethylene (Nippon Polyethylene Co., Ltd.)
The molded articles (C) and (B) each having the shape shown in FIG. 1 were molded by using J-REX4551H manufactured by the Company. FIG. 1 is a longitudinal sectional view of one of the cylindrical containers. In FIG. 1, reference numeral 11 denotes a welded portion having a thickness of 2 mm, and reference numeral 12 denotes a protruding portion. Next, a molded article (C) made of polyoxymethylene and a molded article (B) made of high-density polyethylene are heat-welded through the heat-welding sheet (A) as shown in FIG. (10)
I got The heat welding was performed as follows. The weld area is 3.01 cm ² . First, a heated hot plate is applied to a welded portion of a molded article made of high-density polyethylene and melted to a depth of about 1 mm. Then, the hot plate is removed, and the sheet for heat welding (A) is placed on the polyolefin layer (3). ) Was welded by applying pressure so as to be joined. Next, a heated hot plate was applied to the welded portion of the molded product made of polyoxymethylene and melted to a depth of about 1 mm. Then, the hot plate was removed, and the hot plate was welded to the molded product made of high-density polyethylene by the above operation. By joining the polyoxymethylene layer (4) side of the heat welding sheet (A) and pressing and fusing for 1 minute, a molded article made of high-density polyethylene and poly is interposed through the heat welding sheet (A). A composite molded product (10) in which a molded product made of oxymethylene was thermally welded was obtained. PW-1 manufactured by Nakamori Kogyo was used as a hot plate welding device. Table 1 shows the hot plate temperature and heating time in the above operation.

[Evaluation of Composite Molded Article] With respect to the composite molded article (10) obtained by the above method, the appearance of weldability was evaluated, and the airtightness and strength of the welded portion were measured by the following method. A hole in the projecting out portion of the (air tightness evaluation) composite molded (12), arranged as shown in FIG. 3, the air pressure of the inner pressure 1 kg / cm ² in the composite molded article (10) or (10 ') Airtightness was evaluated by checking the presence or absence of leakage in water. In addition, since there is a partition wall formed of the heat welding sheet (A) in the middle, there is a case where pressure is applied from the polyoxymethylene molded product (C) side and a case where pressure is applied from the high density polyethylene molded product (B) side. Both were evaluated for airtightness. (Welding part strength) As shown in FIG.
Was cut off, and an unnecessary portion (partition-like portion) of the heat welding sheet (A) was removed to prepare a test piece.
Using an autograph manufactured by Shimadzu Corporation, by applying a force (P) and applying a pressing speed of 5 mm / min. , The punching strength of the welded portion was measured. Table 1 also shows the performance evaluation results.

[0024]

[Table 1]

[0025]

By using the heat welding sheet of the present invention, a polyolefin product and a polyoxymethylene product were successfully welded.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a cylindrical container-shaped molded product (B) or (C) in Examples and Comparative Examples.

FIG. 2 shows a molded article of two kinds of materials (B) in the embodiment.
And (C) is a schematic diagram for obtaining a composite molded product (10) by heat welding via a heat welding sheet (A).

FIG. 3 is a conceptual diagram showing an airtightness test method for a composite molded product (10) obtained in an example or a composite molded product (10 ′) obtained in a comparative example.

FIG. 4 is a conceptual diagram showing a method for testing the punching strength of a welded portion of a composite molded product (10) obtained in an example or a composite molded product (10 ′) obtained in a comparative example.

[Explanation of symbols]

 Reference Signs List 2 bonding layer 3 polyolefin layer 4 polyoxymethylene layer 10 composite molded product via thermal welding sheet (A) 10 ′ composite molded product without thermal welding sheet (A) 11 welded portion 12 projecting portion A thermal welding Sheet B Molded product made of polyolefin C Molded product made of polyoxymethylene

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4F100 AK03A AK03G AK54B AL06G AL07G BA02 GB16 GB90 4F211 AD05 AD20 AD35 AG06 AH55 TA01 TC07 TC09 TC14 TD07 TD11 TN07 TN53 TN54 TN56 TQ01

Claims (10)

[Claims] 1. A bonding layer (2) comprising a polyolefin layer (3) provided on one side of the bonding layer (2) and a polyoxymethylene layer (4) provided on the other side of the bonding layer (2). Is a heat-sealing sheet comprising a modified polyolefin having a functional group. 2. The modified polyolefin of the tie layer (2) comprises:
2. The heat-sealing sheet according to claim 1, which is a modified polyethylene or a modified polypropylene. 3. The modified polyolefin of the bonding layer (2) is an unsaturated carboxylic acid, an unsaturated carboxylic anhydride, a polymerizable unsaturated compound containing an isocyanate group, a polymerizable unsaturated compound containing an epoxy group, or a polymerizable unsaturated compound containing a hydroxy group. The heat-sealing sheet according to claim 1, wherein the sheet is modified with at least one selected from the group consisting of a saturated compound and a derivative thereof. 4. The heat welding sheet according to claim 1, wherein the modified polyolefin of the bonding layer (2) is modified with maleic anhydride. 5. The heat welding sheet according to claim 1, wherein the polyolefin layer (3) is made of polyethylene or polypropylene. 6. The heat welding sheet according to claim 1, wherein the polyoxymethylene layer (4) comprises a polyoxymethylene homopolymer or a polyoxymethylene copolymer. 7. The heat welding sheet according to claim 1, which is used as a welding layer between a molded article (B) made of polyolefin and a molded article (C) made of polyoxymethylene. 8. The heat welding sheet according to claim 1, wherein the heat welding is performed by hot plate fusion. 9. A molded article made of polyoxymethylene and a molded article made of polyolefin are heat-welded using the heat-welding sheet according to any one of claims 1 to 7 via the heat-welding sheet. A method for producing a composite molded product, comprising: 10. A molded article made of polyoxymethylene and a molded article made of polyolefin are heat-sealed with the heat-sealing sheet according to any one of claims 1 to 7 via the heat-sealing sheet. Composite molded product made by unifying.