JP2610793B2 - Propylene polymer composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a propylene polymer composition containing a special silicone resin powder. This propylene polymer composition, particularly when formed into a film, can be a film having improved blocking resistance, opening properties, slipperiness, and improved transparency and appearance as compared to conventional films. Things.

[0002]

2. Description of the Related Art Hitherto, propylene polymer films have been most widely used as various packaging materials. However, this type of propylene polymer film tends to cause blocking due to its tackiness, which may impair workability during film formation and high-order processing.
In addition, when the film is used for packing or packaging, for example, troubles such as poor opening of the bag are likely to occur. In order to solve such a drawback, a method of blending silicic anhydride with a propylene polymer (Japanese Patent Publication No.
Various methods have been proposed, including a method of blending kaolinite (Japanese Patent Publication No. 43-24523) and a method of blending finely ground zeolite powder (Japanese Patent Publication No. 52-16134). However,
Although these methods can exhibit some improvement in terms of blocking resistance, they have not been able to sufficiently satisfy other recently required higher performances.

That is, first, the transparency of a film has recently been emphasized from the viewpoint of aesthetics. However, in order to increase the blocking resistance of the film, the amount of the antiblocking agent to be added may be increased, but as the amount of addition increases, the dispersibility of the antiblocking agent deteriorates, and the transparency deteriorates. Second, in recent film forming apparatuses, speeding up has been attempted, so that winding workability during film forming has become very important. However, the film cannot be wound well due to poor slipperiness at the time of winding the film, and many defective products are produced. However, even if various lubricants are added, it is not improved. Third, regarding the slipperiness of the formed film such as a bag made of the film after opening, such as the opening property, a higher fatty acid amide or the like is conventionally added as a lubricant, and the lubricant is bleed on the film surface. It is improved by a method such as letting out. However, if a large amount of a lubricant is added to increase the degree of improvement in slipperiness, whitening occurs and the transparency of the film is impaired.

Japanese Patent Application Laid-Open No. Sho 59-68333 discloses that a spherical cured product of a silicone resin is used for rubbers such as natural rubber and polybutadiene rubber, nylon, polyester, and the like.
It describes that when applied to polymer materials such as resins such as polyethylene, polypropylene, and polyvinyl chloride, an anti-adhesion effect can be imparted, and it can be used as a lubricant or a release agent. However, the publication does not describe the blending ratio of the spherical cured product of the silicone resin, and furthermore, in the examples, the spherical cured product of the silicone resin is spread on the surface of butyl rubber or asphalt to give an anti-adhesion effect. Only. In addition, the publication describes that spherical cured products of silicone resin can be applied to various polymer materials, but by blending spherical cured products of silicone resin, the above-mentioned various polymer materials can be used. Normally, it is not possible to exert effects other than the lubricating effect, the peeling effect, and the anti-adhesion effect, for example, the effects of improving transparency and appearance, which are important properties when used as a film.

On the other hand, in order to improve the poor dispersion of the conventional inorganic antiblocking agent, a method in which silicon dioxide and a magnesium salt or aluminum salt of a fatty acid are used in combination (Japanese Patent Laid-Open No.
JP-A-225142) and a method using an inorganic fine powder having a layered structure in combination (see JP-A-57-18747) have been proposed. However, these methods can also provide a material having a satisfactory appearance. Not.

[0006]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to improve the following problems in these conventional propylene polymer films. The workability during film forming and high-order processing should be improved since blocking is likely to occur due to the tackiness. To improve troubles such as poor opening of bags when packing or packing. To reduce the amount of an anti-blocking agent added to increase the anti-blocking property of a film to improve the deterioration of transparency due to the deterioration of dispersibility of the anti-blocking agent. To improve the slipperiness (winding workability) at the time of film winding in film forming and to increase the speed of the film forming apparatus. To improve the opening property of molded articles such as bags, prevent whitening due to bleed-out of lubricant, and improve the transparency of films. To prevent deterioration in transparency due to poor dispersion of an anti-blocking agent, prevent fish eyes from occurring in a film, and improve the film appearance.

[0007]

[Means for Solving the Problems]

SUMMARY OF THE INVENTION The present invention has been made as a result of intensive studies to solve the above-mentioned problems in the conventional propylene polymer film, and as a result, a propylene polymer obtained by blending a silicone resin having a specific property in a specific ratio. Based on the finding that the composition can be a propylene polymer film having not only improved blocking resistance, slipperiness, and opening property but also significantly improved transparency and appearance, the present invention has been completed. It has been reached. That is, the propylene polymer composition of the present invention comprises a crystalline propylene polymer 1
The average particle size of the non-melting silicone resin having a three-dimensional network structure is 0.5 to 7 μm in 00 parts by weight, and the sphericity f represented by the following formula (I) is 0.8 or more. Is mixed at a ratio of 0.01 to 1 part by weight.

[0008]

(Equation 2)

(Where A is the cross-sectional area of the powder (m
m ² ), and Dmax represents the longest diameter (mm) of the section. )

[Specific Description of the Invention] [I] Propylene polymer composition (1) Constituent components (essential components) (a) Crystalline propylene polymer

Kind The crystalline propylene polymer used in the present invention is a polymer containing a copolymer of a propylene homopolymer and a minor proportion of an α-olefin having 20 or less carbon atoms such as ethylene and butene. . Among them, it is preferable to use a propylene homopolymer, a propylene / ethylene random copolymer, or a propylene / ethylene / butene random copolymer, and it is particularly preferable to use a propylene polymer having an ethylene content of 0 to 6% by weight. The melt flow rate (MFR) of these propylene polymers is not particularly limited as long as it can be molded, but is preferably 1 to 30 g / 1.
A time of 0 minutes is preferable from the viewpoint of film formation. Even if a polymer other than the crystalline propylene polymer is used, a sufficient effect as in the present invention cannot be exerted. For example, in place of the crystalline propylene polymer, even if a crystalline polyethylene polymer or asphalt, butyl rubber, or the like is used, these polymer materials cannot exhibit a remarkable transparency improving effect because the transparency is extremely poor in the first place. . Therefore, in the present invention, it is important to use a crystalline propylene polymer.

Average Particle Size These crystalline propylene polymers are preferable because they have a large effect when they are powders having an average particle size of 50 to 3,000 μm. Here, the powder refers to a powder having the same shape obtained by polymerization and not being pelletized.

[0013] The polymer powder obtained in the polyolefin production process is specific to the process, and the olefin is polymerized or copolymerized using a Ziegler catalyst in a slurry process, a solvent-free liquid phase process, or a gas phase process. It is said that the shape of the powder generally reflects the shape of the catalyst particles used for the polymerization.

(B) Non-melting type silicone resin network having a three-dimensional network structure The non-melting type silicone resin powder used in the present invention is a silicone resin powder having a three-dimensional network structure by siloxane bonds. Examples of the organic group bonded to silicon include an aliphatic hydrocarbon group such as a methyl group and an ethyl group, an aromatic hydrocarbon group such as a phenyl group, and an unsaturated hydrocarbon group having a vinyl group. Of these, those having a methyl group are preferably used.

[0015] The silicone resin is generally available as a silicone varnish prepared by dissolving a precondensate in an appropriate solvent. However, the non-melt type silicone resin used in the present invention is a powder containing no solvent. Is a substantially insoluble, infusible substance that has been thermally cured.

The non-melting silicone resin used in the average particle size present invention,
It is a powder having an average particle size of 0.5 to 7 μm, preferably 1 to 5 μm. If the average particle size of the non-melting type silicone resin powder exceeds the above range, the transparency of the film is deteriorated, and the commercial value is significantly reduced. When the average particle size of the non-melt type silicone resin powder is less than the above range, the effect of improving the slip property and the anti-blocking property at the time of forming and winding becomes small, and the forming speed at the time of forming a film is reduced.

Sphericity The shape of the silicone resin powder used in the present invention is such that the sphericity f represented by the formula (I) is 0.8 or more, and the sphericity is 0.85 or more. Are preferred. If the sphericity is smaller than the above range, the blocking resistance and the slipping property are unsatisfactory. The sphericity of the silicone resin powder is determined by the following method. That is,
The powder is placed on a grid for an electron microscope having a collodion support film, and observation and photographing are performed at an appropriate magnification. The obtained photograph is processed with an image analyzer, and the above-mentioned general formula (I)
To determine the sphericity f. The silicone resin powder having such special properties can be appropriately selected and used from commercially available products (for example, "Tospearl" manufactured by Toshiba Silicone Co., Ltd., "Trefill" manufactured by Toray Silicone Co., Ltd.). In addition, various modified silicone resin powders can be used as long as the effects of the present invention are not impaired.

(2) Compounding ratio The compounding ratio of the crystalline propylene polymer and the silicone resin powder used in the present invention is 0.01 to 100 parts by weight of the propylene polymer.
1 part by weight, preferably 0.03 to 1 part by weight. If the amount of the silicone resin powder is less than the above range, the transparency is good, but the blocking resistance and the slipperiness at the time of forming and winding are insufficient, and the forming speed at the time of film forming is reduced. On the other hand, if the amount of the silicone resin powder is too large, the blocking resistance and the slipperiness are good, but the transparency is deteriorated and the commercial value is significantly reduced.

(3) Other components (optional components) In the present invention, in addition to these essential components, stabilizers, processing aids, antistatic agents and the like usually used for polyolefin resins are added. A system rubber or the like may be added within a quantitative range that does not significantly impair the effects of the present invention.

(4) Mixing As a method of mixing the above-mentioned components, a known powder mixer, for example, a V-type blender, a screw-type blender, a drive blender, a ribbon blender, a Henschel mixer, a Nauter mixer or the like is used. It is preferable to mix, knead and pelletize. Of course, the silicone resin does not melt during the mixing / kneading step.

[II] Applications Although the propylene polymer composition of the present invention can be formed into various shapes, it is generally formed into a film from the characteristics of the obtained composition. As a method for forming the film, a conventional forming method is applied. That is, an inflation molding method, a T-die molding method, a solvent cast molding method, a uniaxial stretching molding method, a biaxial stretching molding method, or the like can be used.

[0022]

The present invention will be described more specifically with reference to the following experimental examples. [I] Evaluation method Various measurements and evaluations in each example described below were based on the following methods. (1) Sphericity To measure the sphericity of the silicone resin powder, the powder is placed on a grid for an electron microscope on which a collodion support film is stretched, and observed and photographed at an appropriate magnification. The obtained photograph is processed by an image analyzer, and the above equation (1) is obtained.

[0023]

(Equation 4)

Thus, the sphericity f was determined. (2) Transparency of film The haze was measured according to JIS-K6714. (3) Blocking resistance Two films were stacked so that the contact area was 10 cm ² , sandwiched between two glass plates, and allowed to stand under an atmosphere of 40 ° C. with a load of 50 g / cm ^{2 under} a load of 50 g / cm ² . Thereafter, the maximum load at the time of peeling was measured with a shopper type testing machine. (4) Slipperiness of Film The slipperiness of the film was measured for static friction coefficient and dynamic friction coefficient using a surface property measuring instrument manufactured by Shinto Chemical Co., Ltd. in accordance with ASTM-D1894.

(5) Film Opening Immediately after the film was formed, the film was evaluated according to the following criteria. Evaluation point 1: Open easily if pressed with fingertip. Evaluation point 2: When opening, some resistance is felt. Evaluation point 3: When opening, a considerable resistance is felt. Evaluation point 4: The mouth is opened but very difficult to open. (6) Appearance of Film Fine spots on the surface of the film were visually observed and evaluated according to the following criteria. Evaluation point 1: No spots are observed. Evaluation point 2: There are some spots, but there is no practical problem. Evaluation point 3: Many spots are observed, and there is a problem in practical use. Evaluation point 4: The number of spots is considerably large and cannot be put to practical use.

[II] Experimental Example Example 1 An average particle size of 2 μm and a sphericity of 0.989 were added to 100 parts by weight of a crystalline propylene homopolymer having an MFR of 9.8 g / 10 min.
Non-melting silicone resin powder (made by Toshiba Silicone Co., Ltd.)
0.8 g parts by weight, 0.16 parts by weight of 2,6-di-t-butyl-p-cresol as an antioxidant, and 0.05 part by weight of calcium stearate as a catching agent for hydrochloric acid were blended, and mixed with a super mixer for 2 minutes. After mixing, 30
The mixture was melt-kneaded at a temperature of 250 ° C. by a single-screw extruder having a diameter of mm to form pellets.

Using the pellets, an unstretched film having a film thickness of 25 μm was obtained at a temperature of 250 ° C. by a 35 mm diameter extruder having a T-shaped die. The transparency, blocking resistance, slippage immediately after molding, and film appearance of the obtained film were evaluated. Table 1 shows the results.

Example 2 The procedure of Example 1 was repeated, except that the propylene polymer was changed to a propylene homopolymer having an MFR of 8.5 g / 10 min and the amount of the silicone resin powder added was changed to 0.3 g by weight. . Table 1 shows the results.

Example 3 A propylene polymer was used as a propylene / ethylene random copolymer having an MFR of 6.8 g / 10 min (ethylene content: 4.
6% by weight), and the same procedure as in Example 1 was carried out except that the addition amount of the silicone resin powder was changed to 0.5 g by weight. Table 1 shows the results.

Comparative Example 1 The procedure of Example 1 was repeated except that the silicone resin powder was changed to a silicon dioxide powder having an average particle diameter of 3 μm. Table 1 shows the results.

COMPARATIVE EXAMPLE 2 A propylene polymer was prepared by mixing a propylene / ethylene random copolymer having an MFR of 6.5 g / 10 min (ethylene content: 4.5).
Wt%), and the silicone resin powder was changed to an average particle size of 3
The same operation as in Example 3 was carried out except that the silicon dioxide powder was changed to μm. Table 1 shows the results.

Comparative Example 3 A silicone resin powder was prepared using a sphericity of 0.745 and an average particle size of 4
Example 3 was carried out in the same manner as in Example 3 except that the powder was changed to a non-melting type silicone resin powder of μm. Table 1 shows the results.

Example 4 100 parts by weight of a propylene / ethylene / butene random copolymer (ethylene content: 2.0% by weight, butene content: 7.3% by weight) having an MFR of 8.0 g / 10 min. .
0.39 parts by weight of a non-melting silicone resin powder having a mean particle size of 989 and an average particle size of 2 μm, 2,6-di-t as an antioxidant
0.10 parts by weight of -butyl-p-cresol, 0.05 parts by weight of calcium stearate as a catching agent for hydrochloric acid, and 0.10 parts by weight of erucic acid amide as a lubricant were mixed, and mixed with a super mixer for 2 minutes.
The mixture was melt-kneaded at a temperature of 230 ° C. by a single-screw extruder having a diameter and pelletized.

Using these pellets, a 30 μm blown film was obtained. The transparency, blocking resistance, slip property immediately after molding, and film appearance of the obtained film were evaluated. Table 2 shows the results.

Comparative Example 4 The procedure of Example 4 was repeated, except that 0.6 parts by weight of silicon dioxide powder having an average particle size of 3 μm was added instead of the silicone resin powder. Table 2 shows the results.

Example 5 100 parts by weight of a crystalline propylene homopolymer having an MFR of 1.9 g / 10 min and a sphericity of 0.989 and an average particle size of 2 μm
0.05 g parts by weight of the non-melting type silicone resin powder, 0.10 parts by weight of 2,6-di-t-butyl-p-cresol as an antioxidant, 0.05 parts by weight of calcium stearate as a hydrochloric acid catching agent, and charging 0.6 parts by weight of stearic acid monoglyceride is compounded as an inhibitor,
After mixing with a super mixer for 2 minutes, the mixture was melt-kneaded at a temperature of 230 ° C. with a 30 mm diameter single screw extruder to form pellets. The pellets were formed into a sheet-like film using an extruder, and sequentially stretched 5 times in the longitudinal direction and 10 times in the transverse direction to finally obtain a stretched film having a thickness of 30 μm. The transparency, blocking resistance, slip property immediately after molding, and film appearance of the obtained stretched film were evaluated. Table 3 shows the results.

Example 6 The procedure of Example 5 was repeated, except that the propylene polymer was changed to a propylene homopolymer having an MFR of 1.6 g / 10 min and the amount of the silicone resin powder was changed to 0.03 g by weight. Was. Table 3 shows the results.

Comparative Examples 5 and 6 Instead of the silicone resin powder, 0.15 parts by weight (Comparative Example 5) or 0.05 parts by weight of silicon dioxide powder having an average particle size of 1 μm was used.
The same operation as in Example 5 was carried out except that parts by weight (Comparative Example 6) were added. Table 3 shows the results.

Comparative Example 7 The procedure of Example 5 was repeated except that the silicone resin powder was changed to 0.02 parts by weight of a non-melting type silicone resin powder having a sphericity of 0.745 and an average particle size of 4 μm. Table 3 shows the results.

Comparative Example 8 Instead of the silicone resin powder used in Example 1,
Pelleting was attempted in the same manner as in Example 1 except that 0.8 parts by weight of dimethyl silicone oil having a viscosity of 200 centistokes (25 ° C.) was used. Further, a non-stretched film having a thickness of 25 μm was formed by using the pellets, but the film was pulsated too much to obtain a film having a uniform thickness.

Comparative Example 9 Instead of the silicone resin powder used in Example 5,
A film was prepared and evaluated in the same manner as in Example 5, except that 0.05 parts by weight of dimethyl silicone oil having a viscosity of 100 centistokes (25 ° C.) was used. As a result, the haze was 2.1% and the blocking resistance was 1,100 g / 10 cm.
^2. The film had an appearance evaluation point of 1.

Comparative Examples 10 and 11 The addition amount of the silicone resin powder used in Example 1 was 0
A film was prepared and evaluated in the same manner as in Example 1 except that the amount was changed to parts by weight (Comparative Example 10) and 2 parts by weight (Comparative Example 11). Table 4 shows the results.

Comparative Examples 12 and 13 Silicone resin powder having an average particle diameter of 0.3 μm and a sphericity of 0.980 (Comparative Example 12) or a silicone resin having an average particle diameter of 12 μm and a sphericity of 0.975 was used. The same operation as in Example 1 was performed except that the powder was changed to Comparative Example 13 (Comparative Example 13). Table 4 shows the results.

[0044]

[Table 1]

[0045]

[Table 2]

[0046]

[Table 3]

[0047]

[Table 4]

[0048]

The propylene polymer composition of the present invention, when formed into a film, is excellent in blocking resistance, opening property and slipperiness, and has high transparency and improved appearance and transparency. Can be obtained.

Also, a propylene polymer having a sphericity of 0.8 or more, from which a film having a good dispersibility of an additive could not be obtained, has a good film appearance and is free from fish eyes and bumps. Can be obtained.

Claims (1)

(57) [Claims] (1) To 100 parts by weight of a crystalline propylene polymer,
A powder having a three-dimensional network structure of a non-melting type silicone resin having an average particle size of 0.5 to 7 μm and a sphericity f of 0.8 or more represented by the following formula (I) is defined as 0.1.
A propylene polymer composition characterized by being blended in an amount of from 01 to 1 part by weight. (Equation 1) (In the above formula, A represents the cross-sectional area (mm ² ) of the powder,
Dmax represents the longest diameter (mm) of the section. )