JPH083389A - Polypropylene resin composition for biaxially stretched film - Google Patents

Abstract

PURPOSE:To simultaneously improve transparency and scratching resistance of a biaxially orientated film by adding a small amount of a prescribed hydrocarbon polymer to a polypropylene resin mixed with an organic polymer fine particles as an anti-blocking agent. CONSTITUTION:100 pts.wt. of a propylene homopolymer or a copolymer of propylene and another alpha-olefin is blended with 0.005-0.5 pts.wt. of an anti- blocking agent composed of an organic polymer fine particles having >=0.5mu and <=5mu average particle diameter and 0.01-2 pts.wt. of a hydrocarbon polymer containing at least one hydroxyl group and comprising a saturated or a partially saturated main chain to give the objective polypropylene resin composition for a biaxially orientated film.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polypropylene resin composition for a biaxially stretched film which is excellent in transparency and scratch resistance (scratch resistance).

[0002]

BACKGROUND OF THE INVENTION Polypropylene biaxially stretched films are widely used as various packaging films, print laminating films, etc. because they have good optical properties such as transparency and gloss, and mechanical properties such as tensile strength and rigidity. Has been done. The polypropylene resin used for these purposes usually contains inorganic fine particles such as synthetic silica and talc as an antiblocking agent.

[0003]

However, the biaxially stretched film containing such an anti-blocking agent has scratches on the film surface when the films are rubbed with each other and the appearance of the film is deteriorated. There was a problem that it would end up. In order to solve such problems, it has been tried to use organic polymer fine particles having low hardness as an anti-blocking agent, but there is a problem that the transparency of the film is deteriorated as compared with the case where inorganic fine particles are used. there were.

[0004]

[Means for Solving the Problems] The inventors of the present invention have conducted extensive studies to solve the above problems, and as a result, in particular, a small amount of a specific hydrocarbon polymer was added to a polypropylene resin containing fine organic polymer particles as an antiblocking agent. It was found that the transparency and scratch resistance of the biaxially stretched film obtained by the above can be improved at the same time, and the present invention was completed.

That is, the gist of the present invention is an anti-blocking agent comprising fine particles of organic polymer having an average particle size of 0.5 to 5 μm based on 100 parts by weight of a propylene homopolymer or a copolymer of propylene and another α-olefin. 0.005-
Polypropylene resin composition for biaxially stretched film, containing 0.5 part by weight and 0.01 to 2 parts by weight of a saturated or partially saturated hydrocarbon polymer having a main chain having at least one hydroxyl group at the end. Exist in.

The present invention will be described in more detail below. The polypropylene resin used in the present invention is a homopolymer of propylene or a random or block copolymer of propylene and other α-olefin (ethylene or other α-olefin having at most 12 carbon atoms) (ethylene or The copolymerization ratio of the other α-olefin is at most 15% by weight, preferably 0.1 to 5.0% by weight).

The melt flow index (abbreviated as MFI) of the polypropylene resin may be any one used in the field of biaxially stretched films, but JIS K-72.
According to the method of 10, the value measured at 230 ° C. under a load of 2.16 kg is usually 0.2 to 10 g / 10 minutes, preferably 0.4 to 6 g / 10 minutes.

The composition of the present invention also contains organic polymer fine particles as an anti-blocking agent. Specifically, fine particles of polyethylene terephthalate, fine particles of polyamide, fine particles of crosslinked polymethylmethacrylate, etc. can be preferably used, but in particular, since crosslinked polymethylmethacrylate fine particles can better balance transparency and scratch resistance. It is suitable for

In this case, the average particle size of the organic polymer fine particles needs to be between 0.5 μm and 5 μm.
Below is less effective as an anti-blocking agent
The above is not preferable because both transparency and scratch resistance are deteriorated. Moreover, the compounding quantity is polypropylene resin 10
It is necessary to be 0.005 to 0.5 part by weight, preferably 0.01 to 0.3 part by weight, based on 0 part by weight. If the lower limit or less, the antiblocking property is insufficient, and if the upper limit or more, transparency is obtained. Is not preferable because the deterioration of

In the present invention, the above-described polypropylene resin is blended with a saturated or partially saturated hydrocarbon polymer having a main chain having at least one hydroxyl group at the terminal. The saturated or partially saturated hydrocarbon polymer having a main chain having at least one hydroxyl group at the terminal specifically refers to, for example, the following.

This polymer has at least one hydroxyl group at the terminal, is saturated in the main chain, and has a molecular weight of 500 to 20.
It includes polymers that are liquid, semi-solid and solid at room temperature of 10,000. The average number of hydroxyl groups per molecule is preferably 1.5 to 8.0. Further, a saturated or partially saturated hydrocarbon polymer having a main chain having at least one hydroxyl group at the terminal used in the present invention (hereinafter, simply referred to as "saturated carbonization of a main chain having at least one hydroxyl group at the terminal"). Abbreviated as "hydrogen-based polymer") refers to a polymer in which main chain hydrocarbons are completely or partially saturated. 1,4-
As for polybutadiene, the hydrogenation rate is at least 20%, preferably 50% or more, more preferably 80%.
% Or more.

The main chain saturated hydrocarbon polymer having at least one hydroxyl group at these terminals is a diene polymer produced by a well-known method using a diene as a raw material, such as a radical polymerization method or an anionic polymerization method.
Alternatively, the diene-based copolymer is usually obtained by hydrogenation. However, in the case of anionic polymerization, depending on the conditions, the main amount, for example 50% or more, especially 70% or more of vinyl groups on the alternating carbon atoms of the polydiene skeleton,
Hydrocarbon-based polymer having a saturated main chain, that is, 1, 2
It does not need to be further hydrogenated, since polybutadiene is obtained.

The method for producing a diene polymer having at least one hydroxyl group at the terminal is as follows:
It can be easily obtained by polymerizing a diene monomer using hydrogen peroxide as a polymerization initiator. To obtain a polymer having a hydroxyl group at the terminal by an anionic polymerization method, the living polymer may be reacted with, for example, a monoepoxy compound, formaldehyde, acetaldehyde or acetone, or a halogenoalkylene oxide or a polyepoxide.

The living polymer referred to here is
A polymer produced by polymerizing a conjugated diene alone or a conjugated diene and a vinyl monomer with an anionic polymerization catalyst, for example, an alkali metal or organic alkali metal compound according to a well-known method, and at least one of both ends thereof. It has a structure in which an alkali metal is bonded to.

At least one conjugated diene monomer is used as a raw material monomer for these polymers. As the conjugated diene monomer, butadiene-1,3-, isoprene, chloroprene, bentadiene-1,3,2,
3-dimethyl butadiene-1,3, 1-phenyl butadiene 1,3 etc. are mentioned. On the other hand, as a copolymerization component of the conjugated diene-based copolymer, one or more vinyl monomers are used depending on the purpose. These vinyl monomers include vinyl aromatic compounds such as styrene, α-methylstyrene and vinyltoluene; (meth) acrylates such as methyl acrylate, butyl acrylate and methyl methacrylate.
Acrylic acid derivatives; Nitrile compounds such as acrylonitrile and methacrylonitrile; Vinyl pyridines such as 2-vinylpyridine and 4-vinylpyridine; Vinyl ethers such as methyl vinyl ether and 2-chloroethyl vinyl ether; Halogenation of vinyl chloride, vinyl bromide, etc. Vinyl: Vinyl ester such as vinyl acetate can be used. Also, 2
Vinyl monomers having active hydrogen, such as hydroxyethylmethacrylate, acrylic acid, acrylamide can also be used. When used in combination with the conjugated diene-based monomer, the amount of the vinyl monomer used is preferably 50% by weight or less based on the total amount of the monomers in consideration of the physical properties of the final target product.

The unsaturated double bonds in the main chain of these diene-based polymers and / or diene-based copolymers are used after being wholly or partially hydrogenated. However, 1,2-bonded polybutadiene having substantially no unsaturated bond in the main chain, 3,
In the case of a 4-bond polyisoprene polymer, it is used as it is. The above hydrogenation may be complete hydrogenation saturation or partial hydrogenation. However,
With respect to 1,4-polybutadiene, the hydrogenation rate is at least 20%, preferably 30% or more.
If the hydrogenation rate is less than 20%, the adhesiveness is insufficient, and even if there is some adhesive strength, the adhesive surface is uneven, which is not preferable.
Since 50% of carbon atoms involved in double bonds are present in the main chain of 1,4 polybutadiene, it is necessary in the present invention to keep this to 40% or less. Further, as already described above, for example, 1,2 polybutadiene having 50% of 1,2 bonds has 33 carbon atoms involved in the double bond in the main chain.
Since it is present only in%, it can be used as it is as a polymer for use in the present invention without special hydrogenation.

For the hydrogenation, generally used catalytic hydrotreating means can be adopted. That is, as the hydrogenation catalyst, a nickel catalyst (for example, Raney nickel) which has been used for a long time, cobalt, platinum, palladium, ruthenium, rhodium catalyst, a mixture thereof or an alloy catalyst can be used. These catalysts can be used alone, as a solid or soluble homogeneous complex, or supported on carbon, silica, diatomaceous earth or the like. Furthermore, hydrogenation may be performed using a metal complex obtained by reducing a compound containing nickel, titanium, cobalt or the like with an organometallic compound (eg, trialkylaluminum, alkyllithium, etc.). As the hydrogen used, molecular hydrogen is usually used, but a hydrogen-containing gas can also be used as long as it does not contain a substance that becomes a catalyst poison. The hydrogen pressure may be either atmospheric blow or pressurized system. The temperature is room temperature to 200 ° C,
It is preferably 180 ° C. or lower. The diene-based polymer and / or diene-based copolymer can be used alone or as a solvent solution. As such a solvent, aliphatic hydrocarbons, alicyclic hydrocarbons, aromatic hydrocarbons, alcohols, aliphatic carboxylic acids and the like can be used alone or in a mixed system.

Other methods for producing saturated hydrocarbon polymers used in preparing the compositions of the present invention include:
A method of oxidizing and decomposing a copolymer of an α-olefin and another monomer, and then reducing the copolymer can be used. For example,
A butyl rubber-based polymer obtained by cationically polymerizing isobutylene and butadiene or 1,3-pentadiene is subjected to ozonolysis, and then reduced with lithium aluminum hydride to obtain polyhydroxypolyisobutylene. In addition, polyhydroxy polyolefin can be obtained by subjecting poly-α-olefin having an unsaturated bond obtained by copolymerizing ethylene with ethylene alone or in the coexistence of propylene with diene to ozonolysis, and then reducing it. .

In the present invention, the blending amount of the main chain saturated hydrocarbon polymer having at least one hydroxyl group at the terminal is added to improve the transparency of the polypropylene resin blended with the antiblocking agent. Is used in an amount of 0.01 to 2 parts by weight, preferably 0.05 to 2 parts by weight, and more preferably 0.1 to 1 part by weight, based on 100 parts by weight of the polypropylene resin. When the blending amount of the hydrocarbon-based polymer is at the end of the above range, the effect of improving the transparency of the polypropylene resin is small, and when it exceeds the above range, the effect of improving the transparency does not increase any more, and conversely during molding. It is not preferable because it causes problems such as smoking and odor.

The polypropylene resin composition of the present invention is obtained by dry blending the above polypropylene resin, the antiblocking agent and the saturated hydrocarbon polymer having a main chain having at least one hydroxyl group at the terminal with a blender or by dry blending. After blending, by a usual melt-kneading method, for example, Banbury mixer, continuous mixer, mixing roll, extruder, etc., 190 to 3
It is obtained by melt mixing and pelletizing at a temperature of 00 ° C.

The polypropylene resin composition of the present invention comprises
If necessary, various known additives used for polypropylene, such as heat stabilizers, antioxidants, ultraviolet absorbers, lubricants, and other additives may be added. The method for producing a biaxially stretched film using the polypropylene resin composition obtained by the present invention may be any known method, for example, T
A method of forming a sheet-shaped unstretched film using a die-type molding machine, and then sequentially stretching in a longitudinal and lateral directions using a roll or a tenter, or a method of simultaneously stretching in the longitudinal and lateral directions, or a tubular shape using an inflation-type molding machine. After forming the unstretched film, the film is blown up by heated air to stretch it. In this case, it is preferable that the stretching ratio is 3 times or more, preferably 4 times or more in both the length and the width in view of transparency and mechanical properties of the film.

[0022]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to the following examples as long as the gist thereof is not exceeded. Example 1 (1) Production of Saturated Hydrocarbon-Based Polymer Having Hydroxyl Group at Terminals Polyhydroxypolybutadiene (R-45H manufactured by Arco Chem.) Was placed in an autoclave having a capacity of 10 liters.
T, [-OH] = 0.82 meq / g, cis 1,4: 1
5%, trans-1,4: 58%, vinyl: 27%) 3
kg, cyclohexane 3 kg and carbon-supported ruthenium (5%) catalyst [manufactured by Nippon Engelhard Co., Ltd.] 300
After g was charged and the system was replaced with purified argon gas, high-purity hydrogen gas was started to be supplied into the autoclave, and heating was started at the same time. It took about 30 minutes to reach a steady condition (internal temperature 100 ° C., internal pressure 150 kg / cm ² ) in the autoclave. After 15 hours under these conditions, the hydrogenation reaction was stopped, and the polymer was purified and dried according to the following ordinary method.

As a result of analysis by infrared absorption spectrum, the obtained polymer was a hydrocarbon polymer containing almost no double bond. -OH group of hydrogenated product is 0.81 meq /
g, and the molecular weight measured by the vapor pressure method was 3000. (2) Production of polypropylene resin composition and production of biaxially stretched film Propylene-ethylene random copolymer having an MFR of 2.0 g / 10 min (ethylene copolymerization amount 0.5% by weight) 100
To each part, crosslinked poly (methyl methacrylate) fine particles having an average particle diameter of 2 μm and a saturated hydrocarbon polymer having a hydroxyl group at the terminal obtained in the above (1) were added in an amount shown in Table 1 as Henschel. After stirring with a mixer, 250 with a single screw extruder with a cylinder diameter of 40 mm.
The mixture was melt-kneaded at a temperature of ° C and extruded into pellets.

The pellets thus obtained have a cylinder diameter of 65 mm.
A φ-shaped T-die molding machine was used to form a sheet having a thickness of 2 mm at a resin temperature of 260 ° C., and then a batch-type stretching machine was used to stretch the film 7 times in length and width, and biaxially stretch to a thickness of about 40 μ. I got a film. The transparency and scratch resistance of the obtained film were evaluated by the methods described below. The results are shown in Table 1. (I) Transparency The haze of the obtained film was measured with a haze meter. (Ii) Scratch property The obtained films were rubbed strongly 20 times, and the scratches were visually evaluated on the following two levels. ◯: Almost no scratch is observed. X: A scratch is clearly recognized.

(Comparative Example 1) In Example 1, OH was added to the end.
Example 1 was repeated except that the polymer having a group was not added. (Comparative Example 2) Average particle size of 1.
Example 1 was repeated except that 8 μm of synthetic silica was added in the amount shown in Table 1. (Example 2) MFR as polypropylene resin is 2.0
The same procedure as in Example 1 was carried out except that the above propylene homopolymer was used.

(Example 3) The same procedure as in Example 1 was carried out except that the amount of the polymer having an OH group at the terminal was as shown in Table 1. (Comparative Example 3) 9 μm average particle size as an anti-blocking agent
The same procedure as in Example 1 was carried out except that the crosslinked poly (methyl methacrylate) fine particles were used.

[0027]

[Table 1]

[0028]

[Table 2]

[0029]

According to the present invention, the transparency and scratch resistance of a biaxially stretched film obtained by adding a small amount of a specific hydrocarbon polymer to a polypropylene resin containing organic polymer fine particles as an anti-blocking agent ( Scratch resistance) can be improved at the same time.

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Claims (4)

[Claims] 1. An anti-blocking agent 0.005 comprising organic polymer fine particles having an average particle size of 0.5 μm or more and 5 μm or less based on 100 parts by weight of a propylene homopolymer or a copolymer of propylene and other α-olefin. ~ 0.5 parts by weight and main chain saturated or partially saturated hydrocarbon polymer having at least one hydroxyl group at the end 0.01
The polypropylene resin composition for biaxially stretched films which mixes 2 to 2 weight part. 2. An anti-blocking agent 0.01 to 0 consisting of organic polymer fine particles having an average particle diameter of 1 μm to 3 μm based on 100 parts by weight of a propylene homopolymer or a copolymer of propylene and other α-olefin. A polypropylene resin composition for a biaxially stretched film, containing 3 parts by weight and 0.05 to 2 parts by weight of a saturated or partially saturated hydrocarbon polymer having a main chain having at least one hydroxyl group at the end. 3. The polypropylene for a biaxially stretched film according to claim 1, wherein the anti-blocking agent composed of organic polymer fine particles is polyethylene terephthalate fine particles, polyamide fine particles or crosslinked polymethyl methacrylate. Resin composition. 4. A hydrocarbon polymer having at least one terminal hydroxyl group and having main chain hydrocarbons completely or partially saturated, and having a molecular weight of 500 to 200,000, which is a liquid or a semisolid at room temperature. Alternatively, the polypropylene resin composition for a biaxially stretched film according to any one of claims 1 to 3, comprising a solid polymer.