JP6473304B2 - Olefin resin film - Google Patents

Description

  The present invention relates to an olefin resin film suitable for uses such as a name tag case and a clear file, and more particularly, to an olefin resin film excellent in lubricity, transparency and high frequency welder weldability.

When processing an original film into a name tag case or clear file, the original film is cut or die-cut into a specific shape, and the overlapping edges are bonded with an adhesive, or heat-sealed or welded by high-frequency welding ( Or the like.
When pasting with an adhesive, there is a problem that the transparency of the bonded part is impaired or the bonded part becomes hard, and in heat sealing, depending on the heat conduction of the heated object, the heated object It takes a long time to heat the inside of the steel, and there is a problem that the heat affects the part that is not welded.

  On the other hand, since the high-frequency welding process is to heat only the welded portion of the article to be heated, it can be welded in a short time without affecting the portion to be welded. In addition, since it is heated uniformly from the inside of the object to be heated, it has excellent welding strength and can perform welding with stable quality in an application time of only a few seconds. Because it is a very clean processing method that does not occur, it can be said that it is an excellent processing method for name tag cases and clear files.

  By the way, when winding up an original film, if the original film is not slippery, air is likely to be entrained, and the portion where the air is entrained is uneven and has a problem in appearance. Also, when processing into a name tag case or a clear file, there is a problem that the work is very difficult if the raw film is not slippery. In order to impart lubricity to the raw film, conventionally, powdering was performed during film formation. However, when powdering is performed, the transparency of the film is deteriorated and the film is wound while the powder is held on the surface. Furthermore, there is also a problem that production in a clean room cannot be performed because dusting causes contamination of the molding line.

  As a method for imparting lubricity to a film, a method of adding an organic lubricant or inorganic particles to a resin composition constituting the film is known in addition to powdering (Patent Document 1 and the like).

JP 2009-265499 A

However, since organic lubricants impart lubricity by being exposed to the surface of the film over time, there is no immediate effect, and no lubricity can be imparted when winding the raw film. There are many cases. Even if it could be wound up, this time it was inferior in printability and was difficult to use.
In addition, when inorganic particles are added, it is difficult to maintain the original transparency of the film, which is not suitable for applications such as name tag cases and clear files.

The present invention has been made by intensively studying the above problem, and the gist thereof is as follows.
(1) A resin composition comprising a random polypropylene having a melting point of 135 ° C. or lower and a random polypropylene having a melting point of 136 ° C. or higher in which silica particles are dispersed, on both surfaces of an intermediate layer made of an ethylene-based copolymer. A surface layer in which the weight ratio of random polypropylene having a melting point of 135 ° C. or less and random polypropylene having a melting point of 136 ° C. or more is 50 to 95:50 to 5 is formed.
(2) The olefin-based resin film according to (1), wherein 0.1 to 1.0 part by weight of silica particles is added to 100 parts by weight of the synthetic resin constituting the surface layer.
(3) The olefin resin film according to (1) or (2), wherein the silica particles have an average particle diameter of 1 to 10 μm.

  By this invention, the olefin resin film excellent in lubricity can be provided, without impairing transparency. Moreover, the olefin resin film of the present invention is also excellent in high-frequency welder weldability.

  Hereinafter, the present invention will be described in detail. The olefin-based resin film of the present invention is a resin in which a random polypropylene having a melting point of 135 ° C. or lower and a random polypropylene having a melting point of 136 ° C. or higher in which silica particles are dispersed are mixed on both surfaces of an intermediate layer made of an ethylene copolymer. A surface layer made of the composition is formed.

The surface layer is composed of a resin composition in which a random polypropylene having a melting point of 135 ° C. or lower and a random polypropylene having a melting point of 136 ° C. or higher in which silica particles are dispersed are blended.
By constituting the surface layer with a polypropylene resin, the olefin film of the present invention is excellent in scratch resistance.

The olefin resin film of the present invention comprises silica particles in the surface layer. When silica particles are contained in the surface layer, the surface layer has lubricity, and winding and secondary processing during film formation are very easy.
Generally, when inorganic particles such as silica particles are added, lubricity can be imparted, but on the other hand, there is a problem that transparency is impaired. However, in the present invention, instead of simply adding inorganic particles to the resin composition constituting the surface layer, silica particles are selected as the inorganic particles, and the silica particles are previously added to random polypropylene having a melting point of 136 ° C. or higher. By mixing the added high melting point polypropylene and the low melting point polypropylene, which is a random polypropylene having a melting point of 135 ° C. or less, to form a surface layer, an olefin-based resin film that is smooth and does not impair transparency can be obtained. Was found.
The content ratio of random polypropylene having a melting point of 135 ° C. or lower and random polypropylene having a melting point of 136 ° C. or higher is a weight ratio of random polypropylene having a melting point of 135 ° C. or lower: random polypropylene having a melting point of 136 ° C. or higher = 50 to 95:50 to 5. When the content of the random polypropylene having a melting point of 136 ° C. or higher is less than 5% by weight, the dispersibility of the silica particles is insufficient, and the silica particles are biased in the film. On the other hand, when the content of random polypropylene having a melting point of 136 ° C. or higher exceeds 50% by weight, the high frequency welder weldability is poor.

  The silica particles are preferably contained in an amount of 0.1 to 1 part by weight with respect to 100 parts by weight of the synthetic resin constituting the surface layer. If the amount is less than 0.1 part by weight, sufficient lubricity may not be imparted. On the other hand, if it exceeds 1 part by weight, the transparency of the olefin resin film tends to be impaired.

Moreover, it is preferable that the average particle diameter of a silica particle is 1-10 micrometers. If it is less than 1 μm, the lubricity cannot be obtained unless the addition amount is increased, and if the addition amount is increased, the transparency is lowered, so that it is difficult to satisfy the balance between transparency and lubricity. On the other hand, when it exceeds 10 μm, the dispersibility of the silica particles deteriorates, so that the transparency tends to be lowered or sufficient lubricity cannot be obtained.
In addition, the average particle diameter of the silica particle in this invention is measured by the laser diffraction scattering type particle size distribution measuring method.

  The surface layer may contain a resin other than the polypropylene resin as long as the effects of the present invention are not impaired. Examples of the other resin include low density polyethylene, linear low density polyethylene, medium density polyethylene, homopolypropylene, block polypropylene, polybutene, olefin rubber, and olefin elastomer.

  Moreover, you may add various additives, such as an antistatic agent, antioxidant, a light stabilizer, a ultraviolet absorber, an inorganic filler, and a pigment, to a surface layer as needed.

The intermediate layer of the olefin resin film of the present invention is made of an ethylene copolymer.
The ethylene copolymer is not particularly limited as long as it is an ethylene copolymer having high-frequency welder weldability, and examples thereof include an ethylene-vinyl acetate copolymer and an ethylene-methyl methacrylate copolymer. A flexible and highly polar ethylene-vinyl acetate copolymer is preferred. The vinyl acetate content of the ethylene-vinyl acetate copolymer is preferably 10% by weight or more, particularly preferably in the range of 10 to 35% by weight.

  For the intermediate layer, a polymer other than the above-mentioned ethylene copolymer, specifically, low density polyethylene, linear low density polyethylene, medium density, as long as the properties of the resulting olefin resin film are not impaired. Polyethylene such as polyethylene and high density polyethylene, isotactic or syndiotactic polypropylene (including random propylene and ethylene, including block copolymers, ie, random polypropylene and block polypropylene), polybutene, olefin rubber, olefin elastomer, etc. Can be mixed.

  Moreover, you may add various additives, such as an antistatic agent, antioxidant, a light stabilizer, a ultraviolet absorber, an inorganic filler, and a pigment, to an intermediate | middle layer like a surface layer as needed.

  The olefin-based resin film of the present invention is formed by forming a surface layer on both surfaces of the intermediate layer, and preferably a co-extrusion method or a co-extrusion inflation method with a simple manufacturing process. Of course, the intermediate layer and the surface layer can also be obtained by separately molding them by means of a calendering method, an extrusion method, an inflation method, etc., and laminating them by heat lamination or adhesive. The olefin-based resin film of the present invention also has an advantage that the interlayer has excellent interlayer adhesion without interposing an adhesive layer between the surface layers.

  Although it does not specifically limit about the thickness of the olefin resin film of this invention, Generally, it is 0.03-2.0 mm as the said use.

  The ratio of the thickness of the intermediate layer and the surface layer in the olefin resin film of the present invention is in the range of 1: 2: 1 to 1: 20: 1 in the surface layer: intermediate layer: surface layer, preferably 1 : 4: 1 to 1: 16: 1.

  Since the olefin resin film of the present invention is excellent in lubricity, transparency and high frequency welder weldability, it is suitable for use in applications requiring secondary processing such as name tag cases and clear files.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated concretely, this invention is not limited by these Examples.

<Examples 1-13, Comparative Examples 1-6>
The resin composition comprising the formulation described in Table 1 was T-die coextruded (2 types, 3 layers) to produce an olefin resin film having a layer ratio of 1/12/1 and a total thickness of 300 μm.
In Examples 1 to 13 and Comparative Examples 2 to 5, silica particles or talc and an organic lubricant were added and dispersed in high melting point random polypropylene, and then low melting point random polypropylene was mixed to form a surface layer. In Comparative Example 6, after adding and dispersing silica particles in a low melting point random polypropylene, a high melting point random polypropylene was mixed to obtain a resin composition for surface layer molding.
The unit of numerical values in the table is “parts by weight”.

In the table;
・ Low melting point random polypropylene 1 Melting point 125 ℃
・ Low melting point random polypropylene 2 Melting point 135 ℃
・ High melting point random polypropylene 1 Melting point 140 ℃
・ High melting point random polypropylene 2 Melting point 160 ℃
-Ethylene copolymer 1 Ethylene-vinyl acetate copolymer Acid content: 25% by weight
-Ethylene copolymer 2 Ethylene-methyl methacrylate Acid content: 20% by weight
・ Silica 1 Average particle size 2.0μm
・ Silica 2 Average particle size 4.0μm
・ Silica 3 average particle size 0.5μm
・ Silica 4 Average particle size 12μm
・ Talc average particle size 2.5μm
-Organic lubricant Phosphoric acid ester The average particle diameter of silica and talc is a value measured by a laser diffraction scattering particle size distribution measurement method.

  The following evaluation was performed about the mode at the time of shaping | molding of the film of each Example and a comparative example, and the film obtained by shaping | molding.

<Dispersibility of particles>
The obtained film 1 m ² was visually confirmed and evaluated according to the following criteria.
○ ・ ・ ・ No particle bias △ ・ ・ ・ Partial particles seem to be biased × ・ ・ ・ Particle bias can be confirmed Note that in Comparative Examples 1 and 5, particles (silica or talc) were added. Not evaluated because it has not.

<Transparency>
About the obtained film, the haze value was measured with the haze meter, and the following references | standards evaluated.
○ ・ ・ ・ Haze value less than 10 △ ・ ・ ・ Haze value 10 or more to less than 12 × ・ ・ ・ Haze value 12 or more

<Lubricity>
The state when the two olefin resin films were rubbed together was observed and evaluated according to the following criteria.
○ ・ ・ ・ Can be easily dragged △ ・ ・ ・ Although there is a slight catch, it can be scraped ××… Cannot be dragged

<High frequency welder weldability>
Using a high-frequency welder device with an output of 4 W, the synchronization rate and the welding time when two films were stacked and welded were measured and evaluated according to the following criteria.
○: Welding when the tuning rate is 70 and the oscillation time is less than 3 seconds. Δ ... Welding when the tuning rate is 70 and the oscillation time is 3 seconds or more and less than 5 seconds.

<Printability>
Immediately after forming the film, it was subjected to corona treatment, allowed to stand at room temperature for 6 days, and evaluated the wetting index after standing using a wetting index standard solution (manufactured by Wako Pure Chemical Industries, Ltd.) 48 dynes).
○ ・ ・ ・ Wetting index is 45 dynes or more × ・ ・ ・ Wetting index is less than 45 dynes

  The films of Examples 1 to 13 are excellent in lubricity, transparency, and high-frequency welder weldability, and are therefore suitable for applications that require secondary processing, such as name tag cases and clear files.

Claims (3)

  It consists of a resin composition in which a random polypropylene having a melting point of 135 ° C. or lower and a random polypropylene having a melting point of 136 ° C. or higher in which silica particles are dispersed is blended on both surfaces of an intermediate layer made of an ethylene-based copolymer. A surface layer in which a weight ratio of the following random polypropylene and a random polypropylene having a melting point of 136 ° C. or higher is 50 to 95:50 to 5 is formed.   The olefin resin film according to claim 1, wherein 0.1 to 1.0 parts by weight of silica particles are added to 100 parts by weight of the synthetic resin constituting the surface layer.   3. The olefin resin film according to claim 1, wherein the silica particles have an average particle diameter of 1 to 10 [mu] m.