JP2000109598A - Polyolefin resin film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a polyolefin resin film causing little contamination of die and suppressed generation of void, having excellent transparency, slipperiness and antiblocking property and useful as a packaging material, or the like, by adding a specific amount of a porous spherical crosslinked particle of an organic polymer having a prescribed average particle diameter. SOLUTION: The objective resin film contains 0.01-3 wt.% porous spherical crosslinked particles of an organic polymer having an average particle diameter of 1-20 μm, a porosity of preferably 5-50% and a pore diameter of 5-5,000 nm. The porous spherical crosslinked particle of organic polymer is preferably produced by the copolymerization of monomers comprising 50-99.9 wt.% alkyl (meth)acrylate, 0.1-30 wt.% polyfunctional monomer having two or more vinyl groups in the molecule, e.g. divinylbenzene and 0-49.9 wt.% other copolymerizable monomers such as styrene in the presence of a pore-forming agent such as toluene.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to transparency, slipperiness,
The present invention relates to a polyolefin resin film which is excellent in blocking resistance and scratch resistance, has less occurrence of resin droplets called "eye oil" generated in die slip during film formation, and is excellent in film productivity.

[0002]

2. Description of the Related Art Conventionally, as a method for improving the slipperiness and blocking resistance of a polyolefin resin film, a method in which fine inorganic particles such as silica or talc are added to a resin, and a method in which organic polymer crosslinked particles are added. It has been known. Among these methods, the method of adding the organic polymer crosslinked particles is more transparent than the method of adding the inorganic fine particles,
A polyolefin resin film having excellent scratch resistance can be obtained (JP-A-5-214120). However, the method of adding the organic polymer cross-linked particles has a higher incidence of "eye oil" during film formation than the method of adding the inorganic fine particles, and when the "eye oil" adheres to the film, the film becomes Since a scratch is formed, it is necessary to remove it, and there is a problem that the frequency of cleaning the die slip increases, and the film productivity decreases.

[0003]

DISCLOSURE OF THE INVENTION The present invention is excellent in transparency, slipperiness, blocking resistance, and scratch resistance, has less contamination of dies called "eye oil" at the time of film formation, and has improved film productivity. It is to provide an excellent polyolefin resin film.

[0004]

As a result of various studies, the present inventors have found that, based on 100 parts by weight of a polyolefin resin, 0.01 to 3 parts by weight of a porous spherical organic polymer crosslinked particle having an average particle diameter of 1 to 20 μm. The inventors of the present invention have found that all the above-mentioned problems can be solved by blending, and have completed the present invention. That is, the present invention relates to (1) a polyolefin resin film containing 0.01 to 1% by weight of porous spherical organic polymer crosslinked particles having an average particle diameter of 1 to 20 μm, and (2) a porous spherical organic polymer crosslinked particle. The polyolefin resin film according to (1), wherein the porosity is 5 to 50% and the pore diameter is 5 to 5,000 nm; and (3) the porous spherical organic polymer crosslinked particles are alkyl (meth) Acrylate 50
A monomer mixture comprising 0.1 to 30% by weight of a polyfunctional monomer having two or more vinyl groups in the molecule and 0 to 49.9% by weight of another copolymerizable monomer. The polyolefin resin film according to the above (1), which is obtained by copolymerization in the presence of an agent.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The polyolefin resin film containing the porous spherical organic polymer crosslinkable particles according to the present invention includes, for example, ethylene, propylene, butene, 4-
Examples thereof include homopolymers or copolymers of olefinic hydrocarbons having 2 to 6 carbon atoms in the main chain such as methylpentene-1, or a mixture of these polymers. The porous spherical organic polymer crosslinked particles in the present invention are defined as 50 to 99.9% by weight of an alkyl (meth) acrylate and 0.1 to 30% by weight of a polyfunctional monomer having two or more vinyl groups in a molecule.
And a monomer mixture consisting of 0 to 49.9% by weight of other copolymerizable monomers in the presence of a porosifying agent. Examples of the alkyl (meth) acrylate include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, and isononyl ( An alkyl group such as meth) acrylate having 1 to 10 carbon atoms is exemplified.

Examples of polyfunctional monomers having two or more vinyl groups in the molecule include aromatic divinyl monomers such as divinylbenzene, ethylene glycol di (meth) acrylate, butylene glycol di (meth) acrylate, and the like.
Different reactivity of alkane polyols such as hexanediol di (meth) acrylate, trimethylolpropane di (meth) acrylate, trimethylolpropane tri (meth) acrylate, poly (meth) acrylate, allyl (meth) acrylate, diallyl itaconate Examples of the monomer include a vinyl group-containing monomer, urethane di (meth) acrylate, and epoxy (meth) acrylate. As other copolymerizable monomers, styrene, vinyl toluene, aromatic vinyl such as α-methylstyrene,
Examples thereof include vinyl cyanide such as aromatic vinylidene, acrylonitrile, and methacrylonitrile, vinylidene cyanide, and urethane (meth) acrylate. Further, a monomer having a functional group can be copolymerized. For example, a monomer having an epoxy group such as glycidyl methacrylate, a monomer having a carboxyl group such as acrylic acid, methacrylic acid, maleic acid, and itaconic acid; a monomer having a hydroxyl group such as 2-hydroxyethyl (meth) acrylate; ) Monomers having an amino group such as acrylate. As a method for synthesizing the porous spherical organic polymer crosslinked particles in the present invention, methods such as emulsion polymerization, suspension polymerization, and dispersion polymerization are used, and preferably, suspension polymerization is performed. The suspension polymerization is carried out using the above-mentioned monomer mixture, dispersion stabilizer, surfactant, oil-soluble radical polymerization initiator, porogen, and the like. It is desirable that the oil-soluble radical polymerization initiator and the porogen are previously dissolved or dispersed in the monomer mixture described above.

Examples of the dispersion stabilizer include aqueous solutions of gelatin, methylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, carboxymethylcellulose, polyethylene glycol, polyacrylamide, polyacrylic acid, polyacrylate, sodium alginate and partially saponified polyvinyl alcohol. Inorganic substances such as conductive polymers, tricalcium phosphate, titanium oxide, calcium carbonate, and silicon dioxide are used. One or more of these dispersion stabilizers can be used. Examples of the surfactant include anionic surfactants such as sodium dodecylbenzenesulfonate, sodium dialkylsulfosuccinate, and sodium lauryl sulfate, and nonionic surfactants such as polyethylene glycol nonylphenyl ether. One or more of these surfactants can be used. Examples of oil-soluble radical polymerization initiators include benzoyl peroxide, o
Organic peroxides such as -methoxybenzoyl peroxide, o-chlorobenzoyl peroxide, lauroyl peroxide, cumene hydroperoxide,
Azo compounds such as 2'-azobisisobutyronitrile and 2,2'-azobis-2,4-dimethylvaleronitrile are used. One or more of these oil-soluble radical polymerization initiators can be used.

[0008] Porous agents are substances that make organic polymer crosslinked particles porous, and include several types. One of them is a solvent such as toluene, isooctane, methyl isobutyl ketone, which is soluble in the above-mentioned monomer mixture but is insoluble in the polymer after polymerization. In this case, the amount of the solvent used is 20 to 20 parts by weight per 100 parts by weight of the monomer mixture.
It is about 0 parts by weight, and the used porogen is removed in the step of drying the particles, and the portion from which the solvent has been removed becomes pores. Further, as another porous agent, an inorganic substance which can be dissolved by a strong acid such as calcium carbonate and tricalcium phosphate can be used. In this case, the amount of the inorganic substance used is 20 to 20 parts by weight per 100 parts by weight of the monomer mixture.
It is about 0 parts by weight, and the used porosifying agent is removed by dissolving with a strong acid in the step of purifying the particles after the polymerization, and the dissolved and removed portions become pores. As another porogen, for example, a linear polymer soluble in the above-mentioned monomer mixture, such as poly (alkyl methacrylate), is used. In this case, the amount of the linear polymer used is about 1 to 10 parts by weight based on 100 parts by weight of the monomer mixture. Causes phase separation with the polymer, and the particles become porous. The type of linear polymer used is not particularly limited, but the shape and size of the pores differ depending on the type of polymer. These porous spherical polymer crosslinked particles may be used alone or in combination of two or more.

The average particle size of the porous spherical organic polymer crosslinked particles used in the present invention is usually in the range of 1 to 20 μm, preferably 2 to 15 μm. When the average particle size is smaller than the above range, the effect of blocking resistance is reduced, a large amount is required, and the transparency of the polyolefin resin film is impaired. On the other hand, when the average particle size is larger than the above range, the film has a grainy feeling and transparency is impaired. “Spherical” in the particles of the present invention does not necessarily have to be a true sphere, but means a particle without large projections. The porous spherical organic polymer cross-linked particles obtained by the above method preferably have a porosity of 5 to 50% and a pore diameter of 5 to 5,000 nm. No effect is obtained, and the generation of "eye oil" cannot be reduced. The compounding ratio of the porous spherical organic polymer crosslinked particles obtained by the above method to the polyolefin resin is usually from 0.01 to 3 parts by weight, preferably from 0.1 to 1 part by weight, per 100 parts by weight of the polyolefin resin. is there. If the compounding ratio is smaller than the above range, sufficient sliding properties and blocking resistance cannot be imparted. On the other hand, when the mixing ratio is larger than the above range, sufficient slipperiness and blocking resistance are imparted, but transparency is significantly impaired.

The average particle size of the porous spherical organic polymer cross-linked particles and the optimum value of the resin composition greatly vary depending on the type of polyolefin resin, the thickness and configuration of the polyolefin resin film, the presence or absence of stretching, and the like. It is preferable to appropriately set the above range appropriately in accordance with the characteristics of the polyolefin resin film. In the present invention, additives other than the porous spherical organic polymer crosslinked particles may be blended as long as the effects of the present invention are not impaired. Examples of the additive include various stabilizers such as an antioxidant and an ultraviolet absorber, a lubricant, an antistatic agent, and in some cases, an inorganic filler. The method of mixing the above-mentioned porous spherical organic polymer crosslinked particles and additives is not particularly limited, but is mixed with a Hensyl mixer, a tumbler or the like, and melt-kneaded with a single or twin screw extruder. In general, pelletization is performed. In the present invention, the present invention can be applied to an unstretched casting film simply extruded or a stretched film obtained by stretching the casting film in a uniaxial or biaxial direction. Further, the present invention can be applied to both a single-layer configuration and a multilayer configuration. In the case of a multilayer structure, the porous spherical organic polymer crosslinked particles described above are:
It is generally added to the surface layer, but is not limited to this.

[0011]

EXAMPLES The present invention will be described more specifically with reference to Reference Examples, Examples and Comparative Examples, but the present invention is not limited to these. Reference Example 1 Preparation of Porous Spherical Organic Polymer Cross-Linked Particles To 555 g of water was added polyvinyl alcohol (Kuraray Povar 2).
05, manufactured by Kuraray Co., Ltd.), a mixed solution consisting of 190 g of methyl methacrylate, 10 g of trimethylolpropane trimethacrylate, 1 g of lauroyl peroxide, and 100 g of methyl isobutyl ketone was added to an aqueous solution in which 5 g was dissolved. The mixture was stirred to prepare a dispersion of the monomer mixture. At this time, the rotation speed of the stirring blade of the homomixer was set to 5,000 rpm and 3,200 rpm, respectively.
The mixture was stirred at m and 2,100 rpm to prepare three types of dispersion solutions having different particle diameters. Each of the dispersion solutions was transferred to a four-necked flask equipped with a stirrer, a reflux condenser, a thermometer, and a nitrogen inlet. The temperature was raised to 60 ° C. while stirring under a nitrogen stream, and the reaction was allowed to proceed for 3 hours. The obtained suspension was cooled to room temperature, filtered and washed with water, and the filter cake was dried at 110 ° C. for 24 hours to obtain porous spherical organic polymer crosslinked particles. The obtained porous spherical organic polymer cross-linked particles were A-1 and A-
2, A-3. The properties of the particles are shown in [Table 1].

Reference Example 2 Preparation of Nonporous Spherical Organic Polymer Cross-Linked Particles 555 g of water was mixed with polyvinyl alcohol (Kuraray Povar 2).
05 (manufactured by Kuraray Co., Ltd.) in an aqueous solution having 5 g dissolved therein, 190 g of methyl methacrylate, 10 g of trimethylolpropane trimethacrylate, lauroyl peroxide 1
g of the mixture was added. This was stirred using a homomixer to prepare a dispersion of the monomer mixture. At this time, the intensity of stirring of the homomixer was changed to three stages as in Reference Example 1, and three types of dispersion solutions having different particle diameters were prepared. Each of the dispersion solutions was transferred to a four-necked flask equipped with a stirrer, a reflux condenser, a thermometer, and a nitrogen inlet, and heated to 60 ° C. while stirring under a nitrogen stream, and reacted for 3 hours as it was. The obtained suspension was cooled to room temperature, filtered and washed with water, and the filter cake was dried at 110 ° C. for 24 hours to obtain nonporous spherical organic polymer crosslinked particles. The obtained non-porous spherical organic polymer crosslinked particles were designated as B-1, B-2, and B-3, respectively, from the smaller particle diameter. The properties are shown in [Table 1].

The physical properties of the particles obtained in each of the above Reference Examples were tested by the following methods. [Average particle size (μm)] Coulter Multisider II
(Manufactured by Coulter KK), and the value of the arithmetic diameter of the weight distribution was adopted. [Porosity (%)] It was determined by a mercury intrusion method. [Diameter of hole (nm)] The size of the hole was confirmed by SEM.

[0014]

[Table 1]

Example 1 A polypropylene containing 0.3% by weight of porous spherical organic polymer crosslinked particles A-1 was extruded from a T-die at a resin temperature of 270 ° C. to obtain a film having a thickness of 30 μm. The obtained film was a film excellent in transparency, slipperiness and scratch resistance, and further, the generation of "eye oil" during film formation was small. The properties of the obtained film are shown in [Table 2]. Comparative Example 1 A film was obtained in the same manner as in Example 1 except that the porous spherical organic polymer crosslinked particles B-1 were used instead of the porous spherical organic polymer crosslinked particles A-1. The obtained film was excellent in transparency, slipperiness and scratch resistance, but generated much "eye oil" during film formation. The properties of the obtained film are shown in [Table 2]. Comparative Example 2 A film was obtained in the same manner as in Example 1, except that the porous spherical organic polymer crosslinked particles A-3 having a large average particle diameter were used instead of the porous spherical organic polymer crosslinked particles A-1. Was. The obtained film was excellent in slipperiness and scratch resistance, but was inferior in transparency. However, the generation of "eye oil" during film formation was small. The properties of the obtained film are shown in [Table 2]. Comparative Example 3 A film was obtained in the same manner as in Example 1, except that fine powdered silica (average particle diameter of 2.5 μm) was used instead of the porous spherical organic polymer crosslinked particles A-1. The resulting film was inferior in transparency, slipperiness and scratch resistance,
The generation of "eye oil" during film formation was small. The properties of the obtained film are shown in [Table 2].

Example 2 A polyethylene containing 0.3% by weight of porous spherical organic polymer crosslinked particles A-2 was extruded from a T-die at a resin temperature of 240 ° C. to obtain a film having a thickness of 20 μm. The obtained film was a film excellent in transparency, slipperiness and scratch resistance, and further, the generation of "eye oil" during film formation was small.
The properties of the obtained film are shown in [Table 2]. Comparative Example 4 A film was obtained in the same manner as in Example 2, except that the porous spherical organic polymer crosslinked particles B-2 were used instead of the porous spherical organic polymer crosslinked particles A-2. The resulting film was excellent in transparency, slipperiness, and scratch resistance, but generated much "eye oil" during film formation. The properties of the obtained film are shown in [Table 2]. Comparative Example 5 A film was formed in the same manner as in Example 2 except that the non-porous spherical organic polymer crosslinked particles B-3 having a large average particle diameter were used instead of the porous spherical organic polymer crosslinked particles A-2. Obtained.
The obtained film was excellent in slipperiness and scratch resistance, but was inferior in transparency. However, "eye oil" was frequently generated during film formation. The properties of the obtained film are shown in [Table 2].

Comparative Example 6 A film was obtained in the same manner as in Example 2 except that fine powdered silica (average particle diameter of 2.5 μm) was used instead of the porous spherical organic polymer crosslinked particles A-2. . The resulting film was inferior in transparency, slipperiness and scratch resistance,
The generation of "eye oil" during film formation was small. The properties of the obtained film are shown in [Table 2]. In addition, the test of each film obtained by the said Example and the comparative example was performed by the following method. [Haze (%)] The haze was measured using a haze tester J according to JIS-K6714. [Scratch resistance] Measured according to JIS-LO823-1971. That is, a 50 times friction test was performed under a load of 200 gf using a dyeing fastness friction tester manufactured by Toyo Seiki Co., Ltd.
The haze was measured before and after the test to determine the degree of increase in haze. [Occurrence of eye oil] Twin screw extruder (Ikegai Iron and Steel Co., Ltd.)
Using PCM-30), melt-knead the polyolefin resin and particles, additives, etc., and mix at a discharge rate of 4 kg / hr.
The amount of "greasy oil" generated in the dies when extruded and pelletized for a time, and the pellets are converted to T dies (manufactured by Chugai Trading:
EXTRUDER (Type: MK-B4)) was used to visually observe the amount of "smear" generated when forming a film, and the overall evaluation was displayed as a five-step "smear" generation degree (the larger the number, the better). This indicates that the amount of "eye oil" generated is large).

[0018]

[Table 2]

[0019]

The polyolefin resin film blended with the porous spherical organic polymer crosslinked particles of the present invention is excellent in transparency, slipperiness, blocking resistance and scratch resistance, and tends to occur on a die slip during film formation. The productivity is improved with less generation of resin droplets called "eye oil", and the generation of voids is suppressed because the particles do not fall off the film even when the film is stretched.

Continued on the front page F term (reference) 4F071 AA15 AA20 AA32 AD06 BC01 4F074 AA48 BA35 BA74 BA84 BB02 BB10 BB28 BC02 BC04 CA33 CB03 CB14 CB17 CB37 CC06W DA02 DA03 DA59 4J002 AA002 BB011 BB023 BG111 BG111 BG111 BB111 BG151 BB151 BB151 DE236 DH046 EA016 EA056 EE036 FA092 FD323 FD326

Claims (3)

[Claims] 1. A polyolefin resin film containing 0.01 to 3% by weight of porous spherical organic polymer crosslinked particles having an average particle diameter of 1 to 20 μm. 2. The polyolefin resin film according to claim 1, wherein the porous spherical organic polymer crosslinked particles have a porosity of 5 to 50% and a pore diameter of 5 to 5,000 nm. 3. A crosslinked porous spherical organic polymer particle comprising 50 to 99.9% by weight of an alkyl (meth) acrylate, and a polyfunctional monomer having at least two vinyl groups in a molecule of 0.1.
~ 30% by weight and other copolymerizable monomers.
The polyolefin resin film according to claim 1, which is obtained by copolymerizing a mixture comprising 9% by weight of a monomer in the presence of a porosifying agent.