JPH04189837A - Fine particle-containing polyolefin film - Google Patents

Abstract

PURPOSE:To obtain the subject soft and flexible film, containing a specific amount of polymer particles having a specific particle diameter and a crosslinked structure with an uneven shape on one surface thereof and excellent in blocking resistance and slipperiness without stickiness and dryness. CONSTITUTION:The objective film containing 2-40wt.%, preferably 3-30wt.%) polymer particles having 3-50mum average particle diameter and a crosslinked structure.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention provides a polyolefin film containing 2 to 40% by weight of crosslinked polymer particles with an average particle diameter of 3 to 50 μm and having excellent flexibility and a soft texture. Regarding.

[Prior Art and Problems to be Solved by the Invention] Polyolefins, particularly polyethylene and polypropylene, have excellent physical and chemical properties and are therefore widely used in films, nonwoven fabrics, containers, and other molded products.

However, contrary to its excellent properties, films in particular have poor blocking resistance and slip properties, molded products have a sticky feel that is undesirable in terms of texture, and are easily charged with electricity, resulting in poor workability. It is known to have problems such as poor matting properties and rustling noise.

In order to solve these problems, a method has been proposed in which fine particles are contained in polyolefin to impart appropriate roughness to the surface of the molded article, thereby improving these problems. For example, polymer particles that do not have a melting point are mixed with a polypropylene resin, melted and extruded, and then stretched into a film (Japanese Patent Publication No. 50-36262, Japanese Patent Application Laid-open No. 57-64522).
Although the anti-blocking properties and slip properties were improved to some extent, the film itself still had a sagging feeling and rustling sound, was easily charged with electricity, and lacked matte properties.

In addition, films made by adding inorganic fillers to polyolefin resins (Japanese Patent Publication No. 46-41463, Japanese Patent Publication No. 5
No. 1-34865) had a paper-like texture, and although the hiding performance and printability were improved, the film itself had a feeling of sagging and rustling, and lacked flexibility.

[Means to solve the problem]

The present inventors solved the above problems while retaining the inherent properties of polyolefin films, and as a result of researching polyolefin films that have a soft texture, the inventors found that they have developed a polyolefin film that is insoluble, infusible, and has low swelling properties and has a crosslinked structure. The present inventors have discovered that these characteristics are expressed in a film obtained by mixing a specific amount of polymer particles of a specific particle size with a polyolefin resin and extrusion molding the mixture, and have completed the present invention.

That is, the present invention relates to a polyolefin film having an average particle diameter of 3 to 50 μm and containing 2 to 40% by weight of polymer particles having a crosslinked structure.

As the polyolefin resin used in the present invention, polyethylene, polypropylene, ethylene/vinyl acetate copolymer, etc. are used.

The crosslinked polymer particles used in the present invention are generally obtained as a copolymer of a radically polymerizable compound having a vinyl group and a crosslinking agent (a radically polymerizable compound having two or more vinyl groups in the molecule). It will be done.

Production methods include suspension polymerization, dispersion polymerization, or emulsion polymerization to directly obtain particles, as well as known methods such as pulverizing polymers obtained by solution polymerization or bulk polymerization. Classification may be performed if necessary. May be implemented.

Examples of the radically polymerizable monovinyl compound used in the present invention include styrene, methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate,
l-Butyl (meth)acrylate, monobutyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, (
Monovinyl compounds such as lauryl meth)acrylate. These monovinyl compounds can be used alone or in combination of two or more.

The crosslinking agent used in the present invention is a compound containing two or more vinyl groups, such as divinylbenzene, ethylene glycol di(meth)acrylate, and trimethylolpropane triacrylate. Such a crosslinking agent is used to crosslink and insolubilize the resulting polymer, and to prevent it from melting due to heating.

In order to maintain the properties of insolubility, infusibility and low swelling properties of the crosslinked polymer particles in the present invention, the above crosslinking agent is used in an amount of 0.1% by weight or more, preferably 0.5% by weight or more of the total monomers. There is a need to.

If it is less than 0.1% by weight, the above-mentioned characteristics of the present invention are weakened, and no superior advantages can be found.

Polymerization initiators used in copolymerization include - peroxides such as benzoyl peroxide, lauroyl peroxide, di-L-butyl peroxide, and hydroperoxide; azo compounds such as azobisisobutyronitrile; Redox initiators etc. can be used.

Other methods for producing crosslinked polymer particles include EB (electron beam) crosslinking of polymers such as polyethylene, polypropylene, polystyrene, and polychloropyrene. E
In the case of B crosslinking, in order to maintain insolubility, infusibility, and low swelling, the irradiation dose must be I Mrad or more. If it is less than I Mrad, the above-mentioned characteristics of the present invention are weakened, and no superior advantage can be found.

Regarding the average particle size of 3 to 50 μm, which is a characteristic of the crosslinked polymer particles used in the present invention, if it is less than 3 μm, the blocking resistance and slipperiness will be improved, but the feeling of stiffness and rustling will not be improved, and the particle will become matte. Their gender was also inferior. In addition, particles that are too small are difficult to manufacture. On the other hand, if the thickness exceeds 50 μm, blocking resistance and slipperiness will be improved, but the feeling of sagging and rustling will not be improved, a rough feeling will appear, and it will be difficult to obtain a thin film with a thickness of about 40 μm or less, resulting in reduced productivity. is also significantly reduced.

The content of crosslinked polymer particles in the present invention is 2 to 4% of the total polyolefin resin composition containing polymer particles.
0% by weight, preferably 3-30% by weight. When the amount is less than 2% by weight, blocking resistance and slipperiness are improved to some extent, but floppy noise and rustling noise are not improved. In addition, almost no obliterating effect was observed.

On the other hand, if the weight exceeds 40 weight, the blocking resistance, slipperiness, sticky feeling, and matteness are improved, but the flexibility of the film is impaired, the soft feeling is poor, and the physical properties of the film such as breaking strength are improved. The surface condition was poor, and it was difficult to form a thin film.

In addition, so-called water-absorbing polymers are partially cross-linked hydrophilic polymers, and powdered ones such as cross-linked polyacrylate-based and cross-linked starch-based polymers are widely known, but these are not preferred for the present invention. .

That is, although films containing these water-absorbing polymer particles have improved slipperiness and soft feel to some extent, when stored for a long period of time, the feel and slipperiness change over time due to their hygroscopicity. Further, when forming a film, even if the raw material is sufficiently dried, minute pinholes tend to occur, making it difficult to form a uniform film.

General additives can be added to the polyolefin resin as necessary. For example, for the purpose of preventing static electricity, cationic, anionic, nonionic, amphoteric, and amphoteric metal salt antistatic agents may be added. It is also possible to add pigments for the purpose of coloring.

It is also possible to add inorganic substances as other fillers.

In order to mix and disperse the crosslinked polymer particles in the polyolefin resin, a conventional kneading extruder that melt-extrudes the polyolefin resin can be used. For example, cross-linked polymer particles are mixed with some polyolefin resin in advance and melt-extruded using an extruder to produce master pellets containing many cross-linked polymer particles.This master pellet is then mixed with the remaining polyolefin resin and melted using an extruder. Forming an extruded film is preferred because the crosslinked polymer particles are more uniformly dispersed. Moreover, the uniformity of the film is also good.

As mentioned above, the two-step method involves first mixing a thermoplastic synthetic resin with some polyolefin to produce master pellets, and then mixing the master pellets with the remaining polyolefin. By varying the proportions from time to time, it is easy to select the appropriate amount of particles in the film.

Note that it is easier to obtain a uniform film if the polyolefin resin, crosslinked polymer particles, or master pellets used in the present invention are dried in advance before being fed to an extruder for film production.

Drying is carried out by a known method, such as hot drying at 50 to 80°C and/or vacuum drying for several hours to about half a day.

When the film extruded from the extruder is extruded onto a water-cooled roll, cooled, and then wound up, a film is obtained that has irregularities formed by a large number of crosslinked polymer particles mainly on the surface opposite to the water-cooled roll surface.

The film thus obtained has a basis weight of 5 to 100 g/m2 (
When the average density is Ig/c+n'', the average thickness is 5~
It is in the range of 10100a.

The thickness of the film portion containing only polyolefin resin is 0.03 to 30 times the particle size of the crosslinked polymer particles, particularly 0.1 to 30 times the particle size of the crosslinked polymer particles.
A preferable range is about 30 times.

[Effects of the Invention] The polyolefin film of the present invention has a large number of polymer particles on one surface thereof. This creates an uneven shape, which not only has good bronking resistance and slip properties, but also eliminates the sagging and rustling sounds that are characteristic of polyolefin films.In addition, it has an extremely soft and flexible texture. You can get good film.

Furthermore, even in a system without the addition of an antistatic agent, a film that is difficult to be charged and has excellent matting properties and hiding properties can be obtained.

〔Example〕

The present invention will be explained in detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.

All % in Examples and Comparative Examples means % by weight unless otherwise specified.

(Preparation of polymer beads) - Polymer beads (A-1) 1 water, 860 g, 218 g of 10χ PVA aqueous solution, 71,350 g of styrene, 20.4 g of divinylhenzene, 13.5 g of lauroyl peroxide, 5! Prepared for the hunt,
Stir with a homomixer (3.00 Orpm, 1 minute),
It was pulverized and used as a monomer preparation liquid.

1,120 g of water in a 51 tetrasol flask and 123 g of a 10$ PVA aqueous solution were charged, the atmosphere was purged with nitrogen, and the temperature was raised to 70°C.

After dropping the above monomer preparation solution over 2 hours and polymerizing,
Polymerization and aging were carried out at 80°C for 4 hours. The resulting suspension was cooled to room temperature, allowed to stand for 2 days, then tilted, the supernatant liquid removed, and then dried in a 50°C hot air dryer.

After pulverizing the dried powder or lumps with a coffee mill, a wind classifier (manufactured by NPK, m1ni classif) is used.
ie-r) to obtain 568 g of polymer beads (A-1) with an average particle size of 12.8 μm.

- Polymer beads (A-2) In the production of polymer beads (A-1), the stirring conditions of the homomixer were adjusted to 3. OOOrpm, 5.00 per minute
Orpm, polymer beads (A-2) 290 with an average particle size of 4.3 um using the same recipe except that the time was changed to 10 minutes.
I got g.

・Polymer beads (A-3) In the production of polymer beads (A-1), polymer beads (A-3) with an average particle size of 1.0 μm were prepared using the same recipe except that 330 g of ethanol was added to the monomer preparation solution.
) 450g was obtained.

・Polymer beads (B-1) In the production of polymer beads (A-1), styrene 1
, 350 g was changed to 1,350 g of isobutyl methacrylate, but using the same recipe, 475 g of polymer beads (B-1) having an average particle size of 10.2 μm were obtained.

・Polymer beads (C-1) In the production of polymer beads (A-1), styrene L
350g, ethyl acrylate 675g and methacrylic acid n
- The same recipe was used except that 675 g of butyl was used, followed by dropwise addition and polymerization, followed by liquid separation and drying, with an average particle size of 18.1. cz
1,250 g of m polymer beads (C-1) were obtained.

・Polymer beads (C-2) In the production of polymer beads (C-1), the stirring conditions of the homomixer were 3.000 rpm and 1,500 rpm for 1 minute.
Polymer beads (C-2) with an average particle size of 38.6 μm using the same recipe except that the rpm was changed to 1 minute 1,31
Obtained 0g.

・Polymer beads (1)-1) Flow beads CL-2080 (polyethylene beads, average particle size 11.9 μm, manufactured by Sumitomo Seika ■) 3.9 g to 14
Spread it out on a cm square hole and apply an acceleration voltage of 200 kV using an EB irradiation device (Curetron, manufactured by Nissin High Voltage).
, an electron current of 3.8 mA, and an irradiation dose of 5 Mrad. Next, the once irradiated beads were mixed, spread uniformly again, and EB irradiated under the same irradiation conditions to obtain crosslinked polymer beads (I)-1). This operation was repeated to obtain 300 g of polymer beads (D-1). (The reason for irradiating twice is to perform crosslinking more uniformly, and the total irradiation dose is 10 Mrad.) - Polymer beads (D-2) In the production of polymer beads (D-1), Flow beads CL-2080 Flow beads CL2507 (polyethylene beads, average particle size 185 μm, manufactured by Sumitomo Seika ■)
Crosslinked polymer beads (D-2) were obtained using the same recipe except for changing the formula.

・Polymer beads (E-1) A 5000 mj2 four-day round bottom flask equipped with a stirrer, reflux condenser, dropping funnel, and nitrogen inlet tube was charged with 2300 mf of cyclohexane and ethyl cellulose (manufactured by Vercules, NN-400) Lo. The temperature was raised to 75°C. Separately, in an Erlenmeyer flask, 300 g of acrylic acid was neutralized with an aqueous solution prepared by dissolving 134 g of caustic soda in 390 g of water. The monomer concentration in the monomer aqueous solution is 45% by weight (
The water content was 55% by weight. Next, 0.5 g of potassium persulfate was added and uniformly dissolved. This monomer aqueous solution was added dropwise to the above-mentioned 4-hole flask under a nitrogen atmosphere over 1.5 hours to polymerize, and then at a temperature of 70 to 75°C.
The polymerization was completed by holding for 5 hours.

After this, the water content in the polymer suspended in cyclohexane is reduced to 3 by azeotropic dehydration (cyclohexane is refluxed).
It was bound at 5% by weight.

This is followed by polyglycerol polyglycidyl ether (
An aqueous solution of 0.3 g of Denacol EX-512 (manufactured by Nagase Sangyo ■) dissolved in 10II+2 water was added at a temperature of 73°C, and after keeping at this temperature for 2 hours, the cyclohexane was removed and the polymer was dissolved. Dry under reduced pressure at 80°C,
A water-absorbing polymer was obtained. Five hatches were prepared under the same conditions, and the resulting water-absorbing polymer was applied to an air classifier to reduce the average particle size to 1.
355 g of 6.3 μm polymer beads (E-1) were obtained.

(Raw materials used) ・10ZPVA aqueous solution: 1 part water to 2I27 lasco, 80
0g of polyvinyl alcohol (Gohsenol GH47, manufactured by Nippon Gosei Kagaku ■) was gradually added while stirring. Next, the temperature was raised to 80°C and stirring was continued for 1 hour to dissolve the mixture, and then cooled to room temperature.

・Polyolefin resin・Polyethylene: Urtozex 15100C (manufactured by Mitsui Petrochemical Industries ■) ・Polypropylene: Hypol F600 (manufactured by Mitsui Petrochemical Industries ■) ・Ethylene/vinyl acetate copolymer: Ehaflexox 14
03 (manufactured by Mitsui DuPont Polychemical ■) (Evaluation method) Average particle diameter of polymer beads (μm) Take a photograph with a microscope at 25 to 400 times magnification, measure the diameter of 100 particles, and calculate the average value. did.

・Film basis weight -/m2) Cut the formed film into 15cm x 30cm,
The weight was measured and converted into weight per 1 m2.

- Breaking strength (kg/mm2) and elongation rate (χ) The formed film was punched out into 2 cm x 10 cm, and measured using Tensilon UTM-I11 (manufactured by Toyo Seiki ■) at a tensile speed of 300++ ua/min. It was calculated from the elongation rate. Incidentally, the breaking strength is calculated by dividing the strength by the cross-sectional area, but since the film of the present invention contains polymer beads and the film thickness is partially different, the basis weight of the film was calculated by replacing the film thickness.

・Salt feeling (sagging feeling) Cut the formed film into 15cm x 30cm,
Evaluation was made by touching the surface of the film with the tips of the fingers or by placing the palm on the film and instantly lifting the hand.

The feel at this time was evaluated on a five-point scale.

5: Surant 2: Slightly dull 4: Slightly smooth 1: Slightly dull 3: Neutral/soft feel Cut the molded film into 15 cm x 30 cm.
Grip with your whole palm. The feel at this time was evaluated on a five-point scale.

5: Extremely supple and soft 4: Supple and soft 3: Neutral 2: Slightly hard. It's a little rough.

l: Hard. It feels rough.

・Cut the slippery molded film into 15cm x 30cm,
Fold it in half and slide it. The slipperiness at this time was evaluated on a five-point scale.

5: Slides without any resistance.

4: Slips well.

3: Sliding with some resistance.

2: There is considerable resistance, but it slips a little.

1: No slipping at all.

・Cut the rustling sound molded film into 15cm x 30cm,
Hold the long side with both hands and give it a fir. The magnitude of the rustling sound at this time was evaluated on a five-point scale.

5: No sound at all 2: Quite a bit of noise 4: Very slight sound 1: Loud noise 3: Slight sound Cut the matte molded film into 15cm x 30cm pieces.
The degree of gloss of the film was evaluated on a five-point scale in a bright place.

5: Total (no gloss) 2: Quite glossy 4: Slightly glossy 1: Extremely glossy 3: Slightly glossy Examples 1 to 8 and Comparative Examples 1 to 6 Biaxial kneading of polymer beads and polyolefin resin The mixture was kneaded into pellets using a machine (Laboplast Mill ME type, manufactured by Toyo Seiki).
(manufactured by Sumitomo Heavy Industries, Ltd.) and wound up into a film to obtain a polyolefin film containing fine particles. The blending compositions are shown in Tables 1, 2 and 3, and the various evaluation results are shown in Tables 4 and 5.

In addition, for the purpose of obtaining a partially colored film, tie bake R-
550 (titanium oxide, manufactured by Ishihara Sangyo ■) was added.

In Comparative Example 6, water-absorbing polymer particles were used, but only a thick film was obtained, and the film was non-uniform with many holes.

Table 1 Table 2 Table 3

Claims (1)

[Claims] 1. A polyolefin film having an average particle diameter of 3 to 50 μm and containing 2 to 40% by weight of polymer particles having a crosslinked structure.