JP6978832B2 - Olefin resin sheet - Google Patents

Description

The present invention relates to an olefin-based resin sheet suitable for applications such as name tag cases and clear files. Specifically, the present invention relates to a plate-out phenomenon that stains rolls during sheet molding and bleeding in which additives emerge on the surface of the molded sheet. The present invention relates to an olefin-based resin sheet in which the out phenomenon is sufficiently suppressed and the transparency and high-frequency welder weldability are excellent.

When processing the raw film into a name tag case or clear file, the raw film is cut or die-cut into a specific shape, the overlapped ends are bonded with an adhesive, or welded by heat sealing or high-frequency welder processing. There is a process of fusing).
When bonding with an adhesive, there are problems such as the transparency of the bonded part being impaired and the bonded part becoming hard, and in the heat seal, it depends on the heat conduction of the object to be heated, so even the inside. It takes a long time to heat, which causes a problem that the heat affects the parts that are not welded.
On the other hand, high-frequency welder processing internally heats only the welded portion of the object to be heated, so that it can be welded in a short time without being affected by heat to the portion that is not welded, and the object to be heated can be welded. By heating uniformly from the inside, it has excellent welding strength, and it is possible to perform welding processing with stable quality in just a few seconds of application time. In addition, it is extremely clean because no environmentally harmful substances are generated during or after processing. It can be said that it is an excellent processing method for name tag cases and clear files because it is a simple processing method.
However, high-frequency welder processing can be performed on polar resins such as vinyl chloride resin, ethylene-methacrylate copolymer and ethylene-vinyl acetate copolymer, although it can be welded, but it has excellent scratch resistance such as polyethylene and polypropylene. No resin can be welded.
Therefore, as an olefin resin sheet used for a name tag case or a clear file, a resin having a polarity excellent in high-frequency welder suitability is used as an intermediate layer, and layers of a resin having excellent scratch resistance (for example, polypropylene resin, etc.) are provided on both sides of the layer. A three-layer olefin resin sheet having excellent high-frequency welder suitability and scratch resistance, which is manufactured by providing the resin sheet, has been proposed (see, for example, Patent Documents 1 and 2).

Japanese Unexamined Patent Publication No. 11-198308 Japanese Unexamined Patent Publication No. 2005-055213 Japanese Unexamined Patent Publication No. 2015-24543

Patent Document 1 discloses an olefin resin multilayer film or sheet composed of an intermediate layer made of an olefin resin and an outer layer made of an olefin resin mainly composed of an ionomer resin formed on both sides thereof.
The multilayer film or sheet made of an olefin resin has high-frequency welder suitability, scratch resistance, and the like, but the obtained film or sheet has tackability and poor moldability, and in some cases, a molding machine. It turned out that there was a problem of burning in the film, and in addition, its transparency was not always sufficient.
Patent Document 2 uses an ethylene-based copolymer selected from an ethylene-vinyl acetate copolymer and an ethylene-alkyl (meth) acrylate copolymer as a central layer, and uses a single-site catalyst having a melting point of 115 to 130 ° C. on both sides thereof. A laminated film in which a polymerized propylene-ethylene random copolymer is laminated is disclosed.
Although the laminated film can be subjected to high-frequency welder processing and has excellent scratch resistance, it cannot be said that the high-frequency welder processability is always sufficient. For example, welding cannot be performed or welding is performed unless the output of electromagnetic waves is increased. It was found that there was a problem that it took time (in some cases, the sheet may be burnt if it took time), and its transparency was not always sufficient.

In addition, the applicant has previously contained an ionomer resin in the outer layer of a three-layer olefin resin sheet composed of an intermediate layer made of an ethylene-based copolymer and an outer layer made of a polypropylene-based resin formed on both sides thereof. It proposes a solution to the above problem by making it (Patent Document 3).
The sheet was excellent in transparency and high-frequency welder weldability, but had the following problems.
When the ionomer resin is added to the polypropylene resin constituting the outer layer, the compatibility between the polypropylene resin and the ionomer resin is not excellent, so that a so-called sea-island structure is formed and the ionomer resin exists as a lump, so that the sheet is smooth. It is hard to become. In addition, the ionomer resin expels some of the additives such as lubricants and antioxidants contained in the resin composition that forms the outer layer, or the low molecular weight components of the polypropylene-based resin, so that the rolls are soiled during sheet molding. It is prone to problems such as the phenomenon and the bleed-out phenomenon in which the additive emerges on the surface of the sheet after molding.

Therefore, it is an object of the present invention to provide an olefin resin sheet having excellent transparency and high frequency welder weldability without solving the above-mentioned problems, that is, without inducing a plate-out phenomenon or a bleed-out phenomenon.

As a result of diligent studies to solve the above problems, the present inventors have found that an olefin-based resin sheet composed of an intermediate layer made of an ethylene-based copolymer and an outer layer made of a polypropylene-based resin formed on both sides thereof. We have found that when the middle layer contains 0.5 to 15% by mass of ionomer resin, it becomes an olefin resin sheet having excellent transparency and high frequency welder welding without inducing plate-out phenomenon or bleed-out phenomenon. Completed the invention.

That is, the present invention is an olefin-based resin sheet composed of (1) an intermediate layer containing an ethylene-vinyl acetate copolymer and an outer layer containing a polypropylene-based resin formed on both sides thereof, and the polypropylene-based outer layer. The resin is random polypropylene polymerized by a metallocene catalyst, and the ratio of the thickness of the intermediate layer to the outer layer is in the range of outer layer: intermediate layer: outer layer = 1: 4 : 1 to 1: 16 : 1, said intermediate layer. Is characterized by containing 0.5 to 5% by mass of an ionomer resin, the olefin resin sheet having a haze value of less than 10 in transparency, and a thickness of 0.03 to 2.0 mm. Oh olefin-based resin sheet for a high-frequency welder working for, (2) the metal ion of the ionomer resin is characterized in that it is a potassium ion (1) an olefin-based resin sheet, wherein a.

INDUSTRIAL APPLICABILITY The present invention provides an olefin resin sheet having excellent transparency and high-frequency welder welding without inducing a plate-out phenomenon or a bleed-out phenomenon.
Further, the olefin-based resin sheet of the present invention sufficiently exhibits high-frequency welder properties even if the amount of ionomer resin added is small.
Furthermore, the olefin-based resin sheet of the present invention has excellent strength at low temperatures, and therefore is less likely to cause cracking in winter, and has excellent dimensional stability at high temperatures, which is advantageous for use in high-temperature processing.

The present invention will be described in more detail.
Olefin resin sheet of the present invention is composed of an outer layer including an intermediate layer and a polypropylene-based resin formed on both surfaces including the ethylene copolymer, the ratio of the intermediate layer and the outer layer thickness of the outer layer: intermediate layer : Outer layer = 1: 3: 1 to 1: 20: 1, and the intermediate layer contains 0.5 to 15% by mass of ionomer resin.

The outer layer of the olefin resin sheet of the present invention contains a polypropylene resin.
Various polypropylene-based resins can be used, but random polypropylene polymerized with a metallocene catalyst is preferably used.
Random polypropylene polymerized with a metallocene catalyst has higher transparency than random polypropylene or homopolyprepylene polymerized with other catalysts, and is therefore advantageous for producing an olefin resin sheet having excellent transparency. be.
Further, the random polypropylene polymerized by the metallocene catalyst preferably has a melt flow rate of 3 g / 10 min or more at 230 ° C. × 2.16 kgf.

In addition to the polypropylene resin, the outer layer is colored with antistatic agents, antioxidants, light stabilizers such as hindered amine compounds, lubricants, ultraviolet absorbers, inorganic fillers, pigments and the like, if necessary. Various additives such as agents may be added.

The outer layer of the olefin-based resin sheet of the present invention is a polymer other than the above-mentioned polypropylene-based resin, specifically, low-density polyethylene or linear low-density, as long as the characteristics of the obtained olefin-based resin sheet are not impaired. Polyethylene such as polyethylene, medium density polyethylene, high density polyethylene; isotactic or syndiotactic polypropylene (including random propylene and ethylene, block copolymers, that is, random polypropylene, block polypropylene, etc.); polybutene; olefinic rubber ; Polyethylene-based elastomer; etc. may be mixed.

Olefin-based resin sheet interlayer of the present invention include ethylene copolymer.
By adding the ionomer resin to the intermediate layer, high frequency welder welding can be performed with lower output and in a shorter time than in a sheet containing no ionomer resin.
Further, since the ethylene-based copolymer and the ionomer resin have excellent compatibility, it is unlikely that additives or low molecular weight resins will elute. Even if the additive or low molecular weight resin elutes, it will not stain the sheet surface because it is blocked by the outer layer. Therefore, it is possible to suppress a plate-out phenomenon that stains the roll during sheet molding, a bleed-out phenomenon in which additives and the like emerge on the surface of the film after molding, and the like.
Further, as will be described later, the intermediate layer of the olefin resin sheet of the present invention is thicker than the outer layer formed on both sides thereof, but by adding the ionomer resin to the middle layer having a high thickness ratio, the sheet is formed. Since the whole heat is generated efficiently, the high frequency welder property is sufficiently exhibited even if the amount of the ionomer resin added is small.

The content of the ionomer resin contained in the intermediate layer is 0.5% by mass or more, and the effect is obtained, and the specific range thereof is 0.5 to 15% by mass, and the range is 1 to 5% by mass. Is preferable. If it exceeds 15% by mass, the transparency tends to be impaired.
Further, the ionomer resin is prepared by cross-linking an ethylene-based binary copolymer or ternary copolymer with metal ions, but in the present invention, those cross-linked with potassium ions are preferable. Used. The ionomer resin cross-linked with potassium ions has a higher dielectric constant than the case of cross-linking with other metal ions (for example, zinc ion, sodium ion, lithium, magnesium, etc.), so that the ionomer resin has a high dielectric constant. The welder property is high.

The ionomer resin is an ethylene-based binary copolymer or ternary copolymer crosslinked with metal ions.
Examples of the binary copolymer include polymers containing ethylene and (meth) acrylic acid or (meth) acrylic acid acrylic ester as a monomer component, and examples of the ternary copolymer include ethylene, (meth) acrylic acid or. Examples thereof include (meth) acrylic acid acrylic ester and a polymer containing (methyl) acrylic acid or (methyl) acrylic acid acrylic ester as a monomer component.

The acid content of the ionomer resin is preferably 5% by mass or more and 30% by mass or less, and more preferably 5% by mass or more and 15% by mass or less.

The ethylene-based copolymer is not particularly limited as long as it is an ethylene-based copolymer having high-frequency welder welding property, and examples thereof include an ethylene-vinyl acetate copolymer and an ethylene-methyl methacrylate copolymer.
Preferred ethylene-based copolymers include ethylene-vinyl acetate copolymers, which are flexible, have high polarity, and have excellent compatibility with ionomer resins.
The ethylene-vinyl acetate copolymer preferably has a vinyl acetate content of 10% by mass or more, and preferably in the range of 10 to 35% by mass.

In addition to the ethylene-based copolymer and the ionomer resin, the middle layer contains, if necessary, antistatic agents, antioxidants, light stabilizers such as hindered amine compounds, lubricants, ultraviolet absorbers, and inorganic fillers. , Colorants such as pigments, and various additives may be added.

The intermediate layer of the olefin-based resin sheet of the present invention is a polymer other than the above-mentioned ethylene-based copolymer, specifically, low-density polyethylene or wire, as long as the characteristics of the obtained olefin-based resin sheet are not impaired. Polyethylene such as low density polyethylene, medium density polyethylene, high density polyethylene; isotactic or syndiotactic polypropylene (including random propylene and ethylene, block copolymers, that is, random polypropylene, block polypropylene, etc.); polybutene; Olefin-based rubber; polyethylene-based elastomer; etc. may be mixed.

The olefin-based resin sheet of the present invention is formed by forming an outer layer on both sides of an intermediate layer, and a coextrusion method or a coextrusion inflation method, which simplifies the manufacturing process, is preferable as a means for forming the outer layer. Of course, the olefin of the present invention can also be formed by separately molding the intermediate layer and the outer layer by means such as a calendar method, an extrusion method, an inflation method, etc., and laminating them by means such as thermal laminating or bonding with an appropriate adhesive. A based resin sheet can be obtained. The olefin-based resin sheet of the present invention also has an advantage of being excellent in interlayer adhesiveness without interposing an adhesive between the intermediate layer and the outer layer.

The thickness of the olefin-based resin sheet of the present invention is not particularly limited, but is generally 0.03 to 2.0 mm for the above-mentioned applications.

In the olefin-based resin sheet of the present invention, the ratio of the thickness of the intermediate layer to the outer layer is in the range of 1: 3: 1 to 1: 20: 1 in the outer layer: intermediate layer: outer layer, preferably 1: 4: 1. The range is 1 to 1:16: 1.
If the ratio of the thickness of the intermediate layer is less than the above range, the high frequency welder weldability is difficult to develop unless the ratio of the ionomer resin is increased. On the other hand, if the ratio of the thickness of the intermediate layer exceeds the above range (that is, if the thickness of the outer layer is small), not only the scratch resistance is impaired, but also the sheet molding itself becomes difficult.
The transparency of the obtained olefin resin sheet is preferably a haze value of 10 or less.

The olefin-based resin sheet of the present invention obtained by the above method is excellent in transparency and high-frequency welder welding property, and is therefore suitable for use in applications requiring secondary processing.

Next, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the Examples.
<Manufacturing of olefin resin sheet>
Example 1
The intermediate layer contains 1% by mass of an ionomer resin 1 having an MFR of 5.0 g / 10 min (230 ° C. × 2.16 kgf) in which an ethylene-methacrylic acid copolymer having an acid content of 12% by mass is crosslinked with potassium ions. Ethylene-vinyl acetate copolymer (Evaflex P1403 manufactured by Mitsui DuPont Polychemical Co., Ltd.) is used, and random polypropylene with MFR of 7.0 g / 10 min (230 ° C x 2.16 kgf) is used for both outer layers, and the main screw. With a three-layer T-die test extruder having a diameter of 40 mm and a subscrew diameter of 25 mm, coextrusion was performed so that the ratio of layer thickness was outer layer: intermediate layer: outer layer = 1: 12: 1, and the thickness was 0. A 3 mm three-layer olefin resin sheet was produced.

Example 2
An olefin resin sheet was produced by performing the same operation as in Example 1 except that the content of the ionomer resin 1 was 5% by mass.

Example 3
An olefin resin sheet was produced by performing the same operation as in Example 1 except that the content of the ionomer resin 1 was 0.5% by mass.

Example 4
An olefin resin sheet was produced by performing the same operation as in Example 1 except that the content of the ionomer resin 1 was 15% by mass.

Example 5
The ionomer resin 1 used in Example 1 was crosslinked with an ethylene-methacrylic acid-acrylic acid ester copolymer having an acid content of 12% by mass with zinc ions, and the MFR was 1.0 g / 10 min (230 ° C. × 2.16 kgf). ) Was changed to the ionomer resin 2, and the same operation as in Example 1 was carried out to produce an olefin resin sheet.

Example 6
The ionomer resin 1 used in Example 1 is crosslinked with an ethylene-methacrylic acid copolymer having an acid content of 7% by mass with sodium ions, and the ionomer resin has an MFR of 0.9 g / 10 min (230 ° C. × 2.16 kgf). An olefin-based resin sheet was produced by performing the same operation as in Example 1 except that the value was changed to 3.

Example 7
An olefin resin sheet was produced by performing the same operation as in Example 1 except that the ethylene-vinyl acetate copolymer was changed to an ethylene-methyl methacrylate copolymer (Aklift WH206 manufactured by Sumitomo Chemical Co., Ltd.).

Comparative Example 1
The same operation as in Example 1 was carried out except that the ionomer resin 1 was not used, to produce an olefin resin sheet.

Comparative Example 2
An olefin resin sheet was produced by performing the same operation as in Example 1 except that the content of the ionomer resin 1 was 20% by mass.

Comparative Example 3
An ethylene-vinyl acetate copolymer (Evaflex P1403 manufactured by Mitsui DuPont Polychemical Co., Ltd.) was used for the intermediate layer, and an ethylene-methacrylic acid copolymer having an acid content of 12% by mass was crosslinked with potassium ions on both outer layers. , MFR 5.0 g / 10 min (230 ° C x 2.1)
MF polymerized by a metallocene catalyst containing 1% by mass of ionomer resin 1 of 6 kgf)
An olefin resin sheet was produced by performing the same operation as in Example 1 except that random polypropylene having an R of 7.0 g / 10 min (230 ° C. × 2.16 kgf) was used.

Test Examples Table 1 shows the roll contamination property, bleed-out property, transparency and high frequency welder weldability of the olefin resin sheets produced in Examples 1 to 7 and Comparative Examples 1 to 3.
The evaluation method and evaluation criteria are as shown below.

Evaluation method / evaluation criteria <Roll contamination>
It was confirmed that the metal mirror surface roll was dirty during the production of the olefin resin sheet.
・ No stains occur even after 2 hours ◎
・ Dirt occurs within 2 hours ×
<Bleed-out property>
The molded olefin resin sheet was left at 25 ° C. for 1 month.
・ No bleed out ◎
・ With bleed out ×
<Transparency>
・ Haze value less than 10 ◎
・ Haze value 10 or more and less than 12 ○
・ Haze value 12 or more ×
<High frequency welder weldability>
Measure the tuning rate and welding time in high frequency welder welding (Conditions: 4kW high frequency welder machine, 5 × 250mm brass flat bar, insulation sheet Nikaply used)
・ Welding with a synchronization rate of 70 and a transmission time of 2 seconds ◎
・ Welding with a synchronization rate of 70 and a transmission time of 4 seconds ○
・ Welding with a synchronization rate of 80 and a transmission time of 4 seconds △
・ No welding ×

Claims (2)

An olefin-based resin sheet composed of an intermediate layer containing an ethylene-vinyl acetate copolymer and an outer layer containing a polypropylene-based resin formed on both sides thereof.
The polypropylene-based resin in the outer layer is random polypropylene polymerized by a metallocene catalyst.
The ratio of the thickness of the intermediate layer to the outer layer is in the range of outer layer: intermediate layer: outer layer = 1: 4 : 1 to 1: 16 : 1.
The intermediate layer contains 0.5 to 5% by mass of ionomer resin.
The olefin resin sheet, and a haze value of less than 10 transparency, and, Oh olefin-based resin sheet for a high-frequency welder machining, wherein the thickness is 0.03～2.0Mm. The olefin-based resin sheet according to claim 1, wherein the metal ion of the ionomer resin is potassium ion.