JPH07178805A - Stretched propylene polymer film - Google Patents

Abstract

PURPOSE:To obtain a polypropylene film good in anti-blocking properties, slip properties, scratch resistance, haze and gloss by allowing a specific number of projections having a specific size to be present on the surface of a stretched film obtained from a mixture of specific fine polymer particles and a propylene polymer. CONSTITUTION:A mixture of fine particles composed of a copolymer consisting of 3-15wt.% of a compd. containing two or more polymerizable unsaturated bonds (U), 15-97wt.% of a (meth)acrylate compd. having one U and a 0-70wt.% of other compd. containing U and a propylene polymer with a melt flow index of 0.5-50g/10min is extruded in a molten state and stretched at least uniaxially. Among projections formed on the surface of the film obtained herein, the number of projections whose height is 0.06mum or more from the center surface of the film is 15-1000/mm<2> and the number of projections with height of 0.06-0.39mum to that of projections with height of 0.6mum or more is 95% or more and the number of projections with height of 0.06-0.15mum is 50% or more.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stretched propylene polymer film, and more specifically, a stretched propylene polymer film having good physical properties such as anti-blocking property, slipperiness, scratch resistance, HAZE (haze) and gloss. It is about.

[0002]

2. Description of the Related Art Generally, it is known that a thermoplastic resin film, particularly a polypropylene film, tends to adhere to each other and has a so-called anti-blocking property. As an improvement method, inorganic particles such as zeolite and silica are added during molding (Japanese Patent Publication No. Sho 42-24523,
Japanese Examined Patent Publication No. 52-16134).

However, in the above-mentioned method, when the above-mentioned inorganic particles are added in an amount necessary to obtain sufficient anti-blocking property and slipperiness, voids having the inorganic particles as cores are generated at the time of stretching the film, and internal HAZE of the film is generated. (Haze) is deteriorated, and external particles are deteriorated due to large particles and poor gloss occurs. Further, there is a problem that surface scratch resistance due to the rubbing of the films due to the shape and hardness of the surface protrusions of the film, that is, scratch resistance becomes poor. Recently, in order to solve such problems, a method of adding polymer fine particles (Japanese Patent Laid-Open No. 61-18183).
No. 7, JP-A-04-189837, and JP-A-04-220436) are known.

[0004]

However, the conventional thermoplastic resin film containing polymer fine particles can improve scratch resistance because the hardness of the polymer fine particles is lower than that of the inorganic particles. The protrusions formed on the surface are not uniform in shape, and the protrusions having a particularly high height cause deterioration of the external HAZE and gloss of the film, and the antiblocking property is inferior to that of the inorganic particle system, and therefore the antiblocking property should be improved. When the amount added was increased, transparency and gloss were deteriorated.

The present invention solves these problems and has anti-blocking property, slip property, scratch resistance and HAZ.
It is an object of the present invention to provide a propylene-based polymer stretched film having good physical properties such as E and gloss.

[0006]

Means for Solving the Problems As a result of intensive studies aimed at achieving the above object, the inventors of the present invention achieved the above object by allowing a certain number of surface projections having a size in a specific range to exist on the film surface. I found that I can achieve.

That is, the present invention provides (1) a radically polymerizable compound containing two or more polymerizable unsaturated bonds, and (2)
Methacrylate having one polymerizable unsaturated bond and /
Alternatively, it is composed of a copolymer of an acrylate compound and (3) a compound having one polymerizable unsaturated bond other than methacrylate and / or an acrylate compound, and the weight ratio thereof is (1) 3 to 15% by weight, respectively. %, (2) 15 to 97% by weight, (3) 0 to
A film obtained by melt-extruding a mixture of 70% by weight of polymer fine particles and a propylene-based polymer having a melt flow index (MI) of 0.5 to 50 g / 10 min and stretching the film at least uniaxially. Of the protrusions formed, the number of protrusions having a height of 0.06 μm or more from the center surface of the film is 15 to 1000 per 1 mm ^{2 of the} film.
0.06μm to 0.39μm for protrusions with a height of 0.06μm or more
The propylene-based polymer stretched film is characterized in that the number of protrusions is 95% or more and the number of protrusions of 0.06 μm to 0.15 μm is 50% or more.

The propylene polymer used in the film of the present invention includes propylene homopolymers, copolymers of propylene and other α-olefins, propylene / ethylene random copolymers, propylene / ethylene block copolymers, propylene / ethylene / Examples include 1-butene random copolymers, mixtures of these,
If necessary, polyethylene, polybutene, styrene resin, EPR (ethylene-propylene rubber), EPD
It is also possible to add a polyolefin polymer such as M (ethylene-propylene-diene terpolymer).
The melt flow rate of these propylene-based polymers (measured in accordance with ASTM-D1238 using 230 ° C. and a weight of 2.16 kg, hereinafter referred to as MI) is 0.5 to.
It is 50 g / 10 min, and those of 1.0 to 20 g / 10 min are particularly preferably used.

The polymer fine particles contained in the film of the present invention include (1) a radically polymerizable compound having two or more polymerizable unsaturated bonds, and (2) a methacrylate having one polymerizable unsaturated bond, And / or an acrylate compound and (3) a copolymer of a compound having one polymerizable unsaturated bond other than methacrylate and / or an acrylate compound. A radical-polymerizable compound containing two or more saturated bonds has a role as a cross-linking agent. For example, a divinyl compound represented by divinylbenzene, ethylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate. Such as di (meth) acrylate compounds, tri (meth) acrylate compounds, and the like,
It is necessary that the weight ratio with respect to the whole polymer fine particles is in the range of 5 to 15% by weight. If it is less than 5% by weight, the heat resistance is poor, and if it is more than 15% by weight, the scratch resistance is poor.

Further, (2) is a methacrylate compound and / or an acrylate compound represented by the chemical formula of CH ₂ CHCH ₃ COOR (the acrylate compound is CH ₂ CH ₂ COOR), in which R has 1 to 15 carbon atoms, One kind or a combination of two or more kinds can be used. For example, methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, i-butyl (meth) acrylate, t-butyl (meth) acrylate, 2- (meth) acrylate Ethylhexyl, (meth) acrylic acid lauryl hydroxypropyl (meth) acrylate, hydroxyethyl (meth)
Acrylate, hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate, hydroxy (meth) acrylate and the like can be mentioned, and the weight ratio to the whole polymer fine particles must be in the range of 15 to 95% by weight. If it is less than wt%, scratch resistance may be poor, and if it is more than 95 wt%, heat resistance may be poor.

Further, (3) is a copolymer composed of a compound having one polymerizable unsaturated bond except a methacrylate and / or acrylate compound, and examples thereof include styrene, p-methylstyrene, α-methylstyrene and chloro. Examples thereof include aromatic monovinyl compounds such as styrene and bromostyrene, and among them, styrene is preferably used.
Originally, these compounds are one of the important components for constituting polymer fine particles like the compounds of (1) and (2) above, but they may be replaced with the methacrylate and / or acrylate compounds of (2) above. Because it is possible,
It can be used if necessary, and therefore the weight ratio to the whole polymer fine particles needs to be in the range of 0 to 70% by weight, and if it deviates from this range, the scratch resistance tends to be poor.

Examples of the polymer fine particles of the present invention composed of the above compounds include, for example, divinylbenzene / methyl (meth) acrylate / styrene copolymer, divinylbenzene / methyl (meth) acrylate / hydroxypropyl methacrylate / styrene copolymer. , Divinylbenzene / n-butyl (meth) acrylate / styrene copolymer, divinylbenzene / n-butyl (meth) acrylate / hydroxypropylmethacrylate / styrene copolymer, divinylbenzene / methyl (meth) acrylate / styrene copolymer , Divinylbenzene / n-butyl (meth) acrylate / methyl (meth) acrylate /
Examples thereof include styrene copolymers, divinylbenzene / n-butyl (meth) acrylate / methyl (meth) acrylate / hydroxypropyl methacrylate / styrene copolymers, and the like.

By using polymer fine particles having a uniform particle size, it is possible to easily control the surface projections having a certain height on the surface of the film and the number thereof. The particle size is preferably 0.1 to 3 μm. Such polymer particles having a uniform particle size are available on the market, and if necessary, commercially available polymer particles may be classified, emulsion polymerization, dispersion polymerization, suspension polymerization,
Those synthesized by a method such as precipitation polymerization can be used.

The amount of the fine polymer particles added to the propylene polymer is preferably 0.01 to 0.50% by weight, and
If it is less than 01% by weight, it is difficult to obtain sufficient anti-blocking property and slipperiness, and if it is more than 0.50% by weight, H
It is not preferable because the AZ and gloss are deteriorated.

In the present invention, among the protrusions formed on the surface of the film comprising the propylene-based polymer and the polymer fine particles obtained by the method described below, 0.
The number of projections with a height of 06 μm or more is 15 to 1000 in the area of the film 1 mm ² , and the number of projections with a height of 0.06 μm to 0.39 μm is 95% or more and 0.06 with respect to the projections with a height of 0.06 μm or more.
The number of protrusions of μm to 0.15 μm is 50% or more, and if the number of surface protrusions of the film is less than 15, anti-blocking property is poor, and if it is more than 1000, HAZE and gloss are deteriorated. Will end up. Also from the center plane
If the number of protrusions with a height of 0.06 μm to 0.39 μm is less than 95% of the number of protrusions with a height of 0.06 μm or more, the smoothness of the surface is impaired and the HAZE and gloss are deteriorated. If the number of protrusions 0.06 μm to 0.15 μm in height from the center plane is less than 50% of the number of protrusions 0.06 μm or more in height, the anti-blocking property is deteriorated and the commercial value is greatly reduced. The film thickness is preferably 4 μm to 200 μm, but the above object can be achieved by controlling the height of projections and the number of projections at any film thickness.

The surface projections referred to herein are projections (mountains) formed by the fine polymer particles contained in the stretched film, and the center plane is the peaks of the film surface formed by the fine polymer particles. Is a surface divided so that the areas of the valley cross sections are equal. The height of the surface protrusion means the height from the center plane, and the average thereof is called the average height. As a method of measuring these surface protrusions, it is general to measure using a roughness tester in accordance with JIS-B0601.

In addition to the above polymer fine particles, if necessary, additives such as an antioxidant, an ultraviolet absorber, a coloring agent and a hydrochloric acid scavenger which are usually added to a propylene polymer are added to the film of the present invention. Of course, it is also possible.

The film in the present invention is a raw material obtained by melt-extruding the above-mentioned propylene-based polymer with a polymer material containing the polymer fine particles and, if necessary, the above additives in the range of 200 to 300 ° C. It can be obtained by stretching the anti-sheet at least uniaxially.

When obtaining a stretched film, the conditions are not limited to those shown below, but in uniaxial stretching, for example, after the raw sheet is once cooled using a batch type biaxial stretching machine, it is heated at 100 to 160 ° C. It can be obtained by stretching in the machine direction 4 to 10 times. Further, in the biaxial stretching, the film obtained by the uniaxial stretching is further sequentially stretched at a right angle to the machine direction under the same conditions as the uniaxial stretching, or simultaneously stretched in the machine direction and the direction perpendicular to the machine direction. It can be obtained by performing simultaneous biaxial stretching. Further, industrially, a tubular film method in which a molten polymer extruded from an extruder is simultaneously stretched on both axes as a tube, or a molten polymer extruded from an extruder is cooled and solidified by a cooling roll, and a preheating roll and The film can be obtained by a continuous biaxially stretching tenter method in which the film is longitudinally stretched by a plurality of longitudinal stretching rolls, and then the film is introduced into a lateral stretching device (tenter) and stretched in the lateral direction.

The thickness of the film obtained by stretching in this way is arbitrarily determined according to the application and is not particularly limited, but is usually 4 to 200 μm, preferably 8 to 100.
It is in the range of μm. Also, the above film can be laminated on a base layer film which does not contain the polymer fine particles to obtain anti-blocking property, slip property, scratch resistance, HA
It is also possible to exert a sufficient effect on ZE and gloss. Examples of the laminating method include a method in which the polymer for the base layer film and the polymer for the surface layer containing the polymer fine particles are melt-extruded by using different extruders to obtain a film.

[0021]

EXAMPLES The present invention will be described in detail below with reference to examples. In addition, the film physical properties in the following examples were measured by the following methods. -Haze: Based on ASTM D1003. -Gloss: According to ASTM D523-62T. -Surface protrusion length and number of surface protrusions: Measured using a three-dimensional roughness measuring device (MODELSE-3AK (A) and three-dimensional roughness analyzer MODEL SPA-11 (B)) manufactured by Kosaka Laboratory. For details, 1000μm × 1000μ in the film
After measuring the surface roughness with a pitch width of 2 μm using the device of (A) for the area of m, the height of the center plane is set to 0 and 0.03 μm.
The number of surface protrusions was analyzed at the slice level.・ Scratch resistance: Two films are prepared and one film (6 cm x 20 cm) is fixed as the lower film,
The other film is the upper film,
A 2.1 kg weight was placed on the lower film to make contact with the lower film in an area of 2.5 cm × 13 cm, and the upper film was moved horizontally to rub it back and forth 10 times between 5 cm. Haze before and after performing this operation was measured according to ASTM D1003. -Friction: According to ASTM D1894. -Anti-blocking property: Two 60mm x 60mm samples are piled up, and a weight of 2kg is placed on the top, 40 ℃, humidity.
After being left in an atmosphere of 70% for 24 hours, the two films were picked up with a thumb and an index finger, and a blocking state at the time of peeling them off with the force of the fingertips was subjected to a sensory evaluation. The evaluation index is shown in (Table 1) described later, but ◯ easily peels off with a fingertip. △ feels a considerable resistance, but peeling with fingertips is possible. In the case of ×, peeling with a fingertip is impossible. Enter.

Example 1 [Synthesis of fine polymer particles] A 5 liter separable flask equipped with a stirrer, a thermometer and a reflux condenser was prepared, 900 parts by weight of water was charged, and nitrogen was replaced with stirring to 70 ° C. Up to. While maintaining the internal temperature at 70 ° C, 4 parts of sodium persulfate was added as a polymerization initiator to completely dissolve it, and then 300 parts by weight of water and sodium lauryl sulfate were previously prepared.
To 3.2 parts by weight, 720 parts by weight of methyl methacrylate, 40 parts by weight of divinylbenzene and 40 parts by weight of 2-hydroxypropyl methacrylate were added with stirring, and 1% by weight of the total amount of the emulsion prepared was added to 70 ° C. Polymerization was carried out for 30 minutes. Next, the rest of the emulsion was continuously added over the course of about 3 hours, and the temperature was further raised to 75 ° C. for aging for 3 hours to obtain a resin particle emulsion having a solid content of 40% and an average particle diameter of 0.2 μm. Obtained.

Subsequently, 1150 parts by weight of water and 15 parts by weight of the above resin particle emulsion are charged into a separable flask similar to the above, and the temperature is raised to 70 ° C. while substituting with nitrogen while stirring.
While maintaining the internal temperature at 70 ° C, the total amount of the polymerization initiator aqueous solution prepared by previously dissolving 4 parts by weight of sodium persulfate in 40 parts by weight of water was added. Next, an emulsion prepared by adding 300 parts by weight of water, 1.6 parts by weight of sodium lauryl sulfate, 720 parts by weight of methyl methacrylate, 40 parts by weight of divinylbenzene and 40 parts by weight of 2-hydroxypropyl methacrylate under stirring in advance is prepared. After adding all the amount over about 5 hours and polymerizing, the temperature was further raised to 75 ° C and aging was performed for 4 hours to obtain a solid content.
A resin particle emulsion having 35% by weight and an average particle diameter of 0.9 μm was obtained. The obtained resin particle emulsion was dried by a spray dryer and powdered to give polymer particles. The composition of the fine polymer particles thus obtained is
From the charged weight ratio, (1) component / (2) component / (3) component = 5 /
It was 85/10% by weight.

[Production of Film] Next, the propylene-based polymer has a melt flow rate of 2.0 g / 10 minutes and an isotactic index (boiling n-heptane insoluble matter).
To 100 parts by weight of 96.0% polypropylene homopolymer, 0.05 parts by weight of the polymer fine particles synthesized by the above method, 0.30 parts by weight of BHT as an antioxidant and 0.05 parts by weight of calcium stearate as a chlorine scavenger were added and mixed with a Henschel mixer. After pre-mixing, the resulting composition was
Pelletization was performed under the condition of 250 ° C or lower. Then, the obtained pellets were melt-extruded at 250 ° C. or lower using a 50 mm diameter extruder to obtain a raw material for stretching. The obtained original thickness is 750 μ
It was m.

The raw sheet thus obtained was subjected to 145 using a batch type biaxial stretching machine (TM-LONG).
After preheating at 60 ° C. for 60 seconds, sequential stretching was carried out 5 times in the machine direction and 7 times in the transverse direction to obtain a biaxially stretched film. The results of physical property evaluation of this film are shown in (Table 1).

Comparative Example 1 In the same manner as in Example 1 except that inorganic particles (Shilton MC manufactured by Mizusawa Chemical Co., Ltd., average particle diameter 1.8 μm) were used in place of the polymer fine particles, scratch resistance was deteriorated. The results are shown in (Table 1).

Comparative Example 2 The procedure of Example 1 was repeated except that organic particles (Nippon Shokubai Co., Ltd .: Eposter 1004, average particle size 4 ± 1 μm) were used in place of the polymer particles, and scratch resistance and anti-blocking were obtained. The result was inferior in sex. The results are (Table 1)
Shown in.

Example 2 As a propylene-based polymer, among the pellets obtained in the same manner as in Example 1, (A) a homopolymer pellet containing no polymer fine particles was fed from a 50 mm extruder to (B) polymer fine particles. A homopolymer pellet having the same composition as in Example 1 containing
Simultaneous co-extrusion from 40mm extruder, (B) / (A) = 150
Evaluation was performed in the same manner as in Example 1 except that a laminated original fabric having a thickness composition of μm / 600 μm was obtained. The results are shown in (Table 1).

Example 3 Example 1 except that the addition amount of fine polymer particles was 0.20 parts by weight.
Same as. The results are shown in (Table 1).

Example 4 Same as Example 2 except that the addition amount of the polymer fine particles to be laminated on the surface layer (B) was 0.20 parts by weight. The results are shown in (Table 1).

[0031]

[Table 1]

[0032]

EFFECTS OF THE INVENTION By carrying out the present invention, it is possible to provide a stretched propylene polymer film having good anti-blocking properties, slipperiness, scratch resistance, HAZE and gloss, and excellent physical property balance. , Its value is very high industrially.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical indication location B29L 7:00 (72) Inventor Yukio Ishii 1-6 Takasago, Takaishi-shi, Osaka Mitsui Toatsu Chemical Co., Ltd. In-house (72) Inventor Futoshi Hoshino 1190 Kasama-cho, Sakae-ku, Yokohama-shi, Kanagawa Mitsui Toatsu Chemical Co., Ltd.

Claims (1)

[Claims] (1) A radically polymerizable compound having two or more polymerizable unsaturated bonds, (2) a methacrylate and / or acrylate compound having one polymerizable unsaturated bond, and (3) ) A copolymer with a compound having one polymerizable unsaturated bond other than a methacrylate and / or an acrylate compound, and the weight ratio thereof is (1) 3 to 15% by weight and (2) 15 to 97% by weight, respectively. %, (3) 0 to 70% by weight of polymer fine particles and a melt flow index (MI) of 0.5
A film obtained by melt-extruding a mixture with a propylene-based polymer, which is -50 g / 10 min, and stretched at least uniaxially, wherein protrusions formed on the film surface have a height of 0.06 μm or more from the film center plane. The number of protrusions is 15 to 1000 per 1 mm ² of the film, and the number of protrusions of 0.06 μm to 0.39 μm is 95% or more and the number of protrusions of 0.06 μm to 0.15 μm is 0.06 μm or more. A propylene-based polymer stretched film having a content of 50% or more.