JP6790711B2 - Polypropylene-based resin composition, laminates and biaxially stretched polypropylene films - Google Patents

Description

The present invention relates to a biaxially stretched polypropylene film having excellent blocking resistance and dispersibility of an antiblocking agent and having few white spots. More specifically, since the antiblocking agent is excellent in dispersibility, aggregation and poor dispersion of the antiblocking agent The present invention relates to a polypropylene-based resin composition used for a biaxially stretched polypropylene film, which has extremely few white spots generated due to the above and can improve stains due to removal of an antiblocking agent, a laminate made of the same, and a biaxially stretched polypropylene film.

In recent years, the required performance of biaxially stretched polypropylene film has been increasing more and more, and there is a strong demand for a film having optical properties with high commercial value. Above all, the dispersibility of the anti-blocking agent greatly affects the transparency, appearance, secondary processability, etc., and significantly affects the commercial value.
Blocking resistance is an essential performance during film molding, secondary processing, etc., and in order to improve these performances, anti-blocking agents are usually used as suitable compounding agents, but dispersion of this anti-blocking agent Sex has a great influence on vitiligo. If the dispersibility of the anti-blocking agent is poor, the appearance will be poor due to vitiligo and the value as a commercial product will be reduced. Therefore, it is essential that the anti-blocking agent has less vitiligo. As the anti-blocking agent, silicon dioxide, for example, synthetic silica or the like is often used because it is relatively soft and the film surface is not easily scratched by rubbing between the films.

However, when this anti-blocking agent is blended with a resin by a stirrer, the particles of the anti-blocking agent tend to disintegrate, the particles become smaller, and not only the blocking resistance is deteriorated, but also they cause secondary aggregation. Therefore, there is a problem that a vitiligo-like appearance defect is generated and the product value is lowered.

Various methods have been proposed as an attempt to solve such a problem (see, for example, Patent Documents 1 to 6).
Patent Document 1 discloses a polypropylene resin composition containing synthetic silica having specific properties in polypropylene resin particles having specific properties. However, when synthetic silica having a pore volume of 0.7 ml / g or less and being relatively hard is used, and this is blended with a highly crystalline propylene-based polymer and used for the surface layer to form a biaxially stretched film, Is difficult to support the anti-blocking agent due to the interfacial peeling between the propylene-based polymer and the anti-blocking agent generated in the stretching process. Therefore, I was not satisfied.
Further, Patent Document 2 discloses a stretched film obtained by blending polypropylene resin particles having specific properties with silicon dioxide powder synthesized by a sedimentation method and melt-extruding the particles. However, other than the sedimentation method, a product that sufficiently satisfies the balance between dispersibility and shedding ability has not been obtained.
Further, Patent Document 3 describes a polypropylene-based film obtained from a resin composition containing spherical synthetic silica and a propylene-based polymer having values of average particle size, specific surface area, pore volume, and oil absorption in a specific range. Although described, the transparency, blocking resistance, dispersibility, appearance, moldability, etc. were insufficient.
Further, Patent Document 4 discloses prevention of the anti-blocking agent from falling off by blending a specific propylene-based resin composition.
However, the shedding property of the antiblocking agent can be improved even if it is not necessarily within the scope of Patent Document 4, which is different from the present application.
Patent Document 5 discloses a stretched polypropylene-based film in which organic fine particles and an acid-modified polyolefin resin are blended and excellent in transparency, blocking resistance, appearance, and drop resistance.
It is also effective to improve the drop-off property by blending an acid-modified polyolefin resin as in the above document and improving the affinity with the organic fine particles, but it is not necessarily within the scope of Patent Document 5, but the antiblocking agent The dropability can be improved, which is different from the present application.
Patent Document 6 discloses a method for producing a masterbatch in which a specific inorganic particle antiblocking agent is blended with an olefin polymer, but it is outside the scope of the porefin polymer specifically described in the examples of this patent document. The present invention has been found to exhibit an effect that is not expected in the present patent document, and is different from the present application.

Japanese Unexamined Patent Publication No. 2001-072812 Japanese Unexamined Patent Publication No. 2008-144043 Japanese Unexamined Patent Publication No. 2008-208210 Japanese Unexamined Patent Publication No. 2016-30767 Japanese Unexamined Patent Publication No. 2001-72813 Japanese Unexamined Patent Publication No. 2006-96939

Conventionally, when a polypropylene homopolymer is laminated and a standard spherical silica or an organic antiblocking agent having high sphericity is blended in the layer to produce a biaxially stretched polypropylene film, the interface between the antiblocking agent and polypropylene is peeled off. However, due to the generation of voids, the anti-blocking agent will fall off when it comes into contact with the roll in the subsequent process, and there is a problem of contaminating the roll and the product. It has not been possible to blend an organic anti-blocking agent with high crystallinity.
Therefore, an object of the present invention is to describe in more detail a biaxially stretched polypropylene film having excellent blocking resistance and dispersibility of an anti-blocking agent and less white spots in order to meet the high performance required for the biaxially stretched polypropylene film. Since the anti-blocking agent used in the present invention has excellent dispersibility, white spots generated due to aggregation and poor dispersion are extremely small, and there is no fusion to the seal bar in the heat sealing process during bag making. The present invention relates to a polypropylene-based resin composition used for an axially stretched polypropylene film, a laminate made of the polypropylene-based resin composition, and a biaxially stretched polypropylene film.

As a result of intensive studies to solve the above problems, the present inventors have obtained a resin composition containing a specific propylene-based copolymer and a specific anti-blocking agent and a specific propylene-based polymer. When the polypropylene-based resin composition contained therein is used, the crystallinity of the resin component existing around the antiblocking agent particles is lowered, the interfacial stress between the antiblocking agent and the resin component generated in the stretching step is reduced, and the interface It has been found that the peeling is remarkably reduced and the generation of voids, which is a factor for the antiblocking agent to fall off, is extremely reduced, so that the shedding property is improved without necessarily requiring acid-modified polypropylene or surface treatment.
Further, since the above-mentioned specific anti-blocking agent has excellent dispersibility, vitiligo is extremely small even when mixed with polypropylene particles having a relatively large particle size.
In general, when antiblocking agent particles are blended with polypropylene particles, it is important to make the mixing polypropylene particle diameter as small as possible and make it difficult to classify in order to improve dispersibility.
If that is difficult, there are methods such as reducing the pore volume of the anti-blocking agent, hydrophilizing or hydrophobizing the surface of the anti-blocking agent, or blending an acid-modified resin to obtain dispersibility. Used. However, since the anti-blocking agent used in the present invention has excellent dispersibility, even when the polypropylene particles are relatively large, the anti-blocking agent can be blended in a high concentration while maintaining good dispersibility, resulting in vitiligo. There are few.
Further, from the viewpoint of heat resistance, it is necessary that the heat resistance of the entire film is high in terms of heat applied during printing and fusion to the heat seal bar during bag making.
In particular, for fusion to the heat seal bar, it is preferable that the surface that comes into contact with the heat seal bar has a high melting point, and when heat seal is applied in the bag making process, the surface that comes into contact with the heat seal bar is made of a polypropylene resin. If the melting point of the seal bar is lower than the set temperature of the seal bar, the film melts and sticks, and the suitability for bag making is significantly lowered.
Therefore, by adjusting the resin composition of the film within the scope of the present invention, the amount of low crystal components is suppressed to the utmost limit to prevent the melting point from being lowered while maintaining heat resistance, and the blocking resistance and dispersibility are excellent, and white spots are formed. We have completed a biaxially stretched polypropylene film that reduces stains caused by the removal of anti-blocking agents and the like.
Based on these findings, the polypropylene-based resin composition of the present invention, a laminate made of the same, and a biaxially stretched polypropylene film have been provided, and the present invention has been completed.

That is, according to the first invention of the present invention, the polypropylene-based resin composition (A) containing the propylene-based polymer (a) having a melting point of 150 ° C. or higher and the propylene-α-olefin resin composition (B). The propylene-α-olefin resin composition (B) is a composition obtained by blending a propylene-α-olefin copolymer (b) having a melting point of 110 to 140 ° C. and an antiblocking agent. The antiblocking agent is a standard spherical silica (c) having an average particle size of 1.0 to 5.0 μm by the laser diffraction method, a specific surface area of 1 to 300 m ² / g by the BET method, and a pore volume of less than 0.7 ml / g. ) Or an organic antiblocking agent (d) having an average particle size of 1.0 to 5.0 μm by a laser diffraction method, and the content of the antiblocking agent in the polypropylene-based resin composition (A) is a propylene-based polymer. (A) 0.01 to 1 part by weight with respect to 100 parts by weight, and the ratio of the resin component in the polypropylene-based resin composition (A) is propylene with respect to 100 parts by weight of the propylene-based polymer (a). The −α-olefin copolymer (b) is 1 to 15 parts by weight, and the ratio of the resin component in the propylene-α-olefin resin composition (B) is propylene-α- to 100 parts by weight of the resin component. Provided is a polypropylene-based resin composition (A), which comprises 50 to 100 parts by weight of the olefin copolymer (b).
Further, according to the second invention of the present invention, in the first invention, the propylene-α-olefin copolymer (b) has a melt flow rate (230 ° C., 2.16 kg load) of 1 to 20 g / 10. Provided is a polypropylene-based resin composition which is a propylene-ethylene-random copolymer or a propylene-ethylene-1-butene random copolymer having a melting point of 120 to 140 ° C.

Further, according to the third invention of the present invention, it is a laminate composed of at least two layers having different layers (1) and (2), and the layer (1) is the polypropylene in the first or second invention. The layer (2) is composed of a based resin composition, the layer (2) contains the propylene-based polymer (a), and the content of the standard spherical silica (c) or the organic anti-blocking agent (d) is the propylene-based polymer. (A) A laminate having less than 0.01 parts by weight with respect to 100 parts by weight is provided.

Further, according to the fourth invention of the present invention, the biaxially stretched polypropylene film composed of the laminate according to the third invention is provided.

Further, according to the fifth invention of the present invention, the food packaging film made of the biaxially stretched polypropylene film according to the fourth invention is provided.

According to the polypropylene-based resin composition of the present invention, it is excellent in blocking resistance and dispersibility, reduces stains due to white spots and falling off of the anti-blocking agent, and further fuses to the seal bar in the heat sealing process during bag making. A biaxially stretched polypropylene film can be obtained.

Hereinafter, the polypropylene-based resin composition of the present invention, a laminate made of the same, and a biaxially stretched polypropylene film will be described in detail for each item, but the present invention is not limited to the following description, and the present invention is not limited to the following description. It can be arbitrarily modified and implemented as long as it does not deviate from the gist. In addition, when a numerical value or a physical property value is inserted before and after using the expression "-" in this specification, it is used in the meaning of including the numerical value or the physical property value before and after that.

[1] Polypropylene resin composition (A), propylene-α-olefin resin composition (B)
The polypropylene-based resin composition of the present invention is a polypropylene-based resin composition (A) containing a propylene-based polymer (a) having a melting point of 150 ° C. or higher and a propylene-α-olefin resin composition (B). , The propylene-α-olefin resin composition (B) is a composition obtained by blending a propylene-α-olefin copolymer (b) having a melting point of 110 to 140 ° C. and an antiblocking agent, and is an antiblocking agent. However, the standard spherical silica (c) or laser having an average particle size of 1.0 to 5.0 μm by the laser diffraction method, a specific surface area of 1 to 300 m ² / g by the BET method, and a pore volume of less than 0.7 ml / g. The organic anti-blocking agent (d) having an average particle size of 1.0 to 5.0 μm by the diffraction method, and the content of the anti-blocking agent in the polypropylene-based resin composition (A) is the propylene-based polymer (a). It is 0.01 to 1 part by weight with respect to 100 parts by weight, and the ratio of the resin component in the polypropylene-based resin composition (A) is propylene-α-with respect to 100 parts by weight of the propylene-based polymer (a). The olefin copolymer (b) is 1 to 15 parts by weight, and the ratio of the resin component in the propylene-α-olefin resin composition (B) is the propylene-α-olefin common weight with respect to 100 parts by weight of the resin component. The polypropylene-based resin composition (A) is characterized in that the coalescence (b) is 50 to 100 parts by weight.

As described above, the propylene-α-olefin resin composition (B) is a composition obtained by blending a propylene-α-olefin copolymer (b) having a melting point of 110 to 140 ° C. and an anti-blocking agent. The anti-blocking agent is a standard spherical silica (c) having an average particle size of 1.0 to 5.0 μm by the laser diffraction method, a specific surface area of 1 to 300 m ² / g by the BET method, and a pore volume of less than 0.7 ml / g. ) Or an organic antiblocking agent (d) having an average particle size of 1.0 to 5.0 μm by laser diffraction.

[1-1] Propylene-based polymer (a)
The propylene-based polymer (a) is a propylene homopolymer having a melting point of 150 ° C. or higher, or a copolymer of propylene and an α-olefin other than propylene (hereinafter, simply referred to as “propylene-α-” in the present specification. It may be referred to as "olefin copolymer"). The propylene-based polymer (a) preferably has a melting point of 155 ° C. or higher, more preferably 157 ° C. or higher, and even more preferably 160 ° C. or higher. A particularly preferable propylene-based polymer (a) is a propylene homopolymer having a melting point of 160 ° C. or higher. When the melting point of the propylene-based polymer (a) is 150 ° C. or higher, it is preferable in terms of heat resistance, and as a result, when a film used for a suitable application in the present invention is made into a bag, it is melted into a heat seal bar. There is no wear and the suitability for bag making is greatly improved.
On the other hand, the upper limit of the melting point of the propylene-based polymer (a) is not particularly limited, but is usually 170 ° C. or lower as a product that can be produced. The melting point of the propylene-based polymer (a) can be appropriately controlled mainly by the type of α-olefin other than propylene and propylene used as a raw material, the copolymerization ratio, MFR and the like. The "melting point" as used herein is a differential scanning calorimetry method (DSC method) based on the method described in JIS K7122 (1987) "Method for measuring transition heat of plastics", that is, a differential scanning calorimeter (DSC). : The melting peak temperature measured by Differential Scanning Calorimetry).

The propylene-α-olefin copolymer is preferably a copolymer containing propylene and an α-olefin having 2 to 8 carbon atoms excluding propylene as a comonomer, more preferably having a propylene content of 99% by weight or more, still more preferably 99. It is a random copolymer of propylene and α-olefin in an amount of 5.5% by weight or more, particularly preferably 99.65% by weight or more and less than 100% by weight. Here, it may be a mixture of random copolymers having different α-olefins. Further, one type of comonomer which is an α-olefin having 2 to 8 carbon atoms excluding propylene to be copolymerized with propylene may be used, or two or more types may be used in combination. As the propylene-α-olefin copolymer, a propylene-ethylene random copolymer, a propylene-ethylene-1-butene random copolymer and the like are preferable.

Examples of α-olefins having 2 to 8 carbon atoms excluding propylene include ethylene, 1-butene, 2-methyl-1-propene, 1-pentene, 2-methyl-1-butene, and 3-methyl-1-butene. , 1-Hexene, 2-ethyl-1-butene, 2,3-dimethyl-1-butene, 2-methyl-1-pentene, 3-methyl-1-pentene, 4-methyl-1-pentene, 3,3 Examples thereof include -dimethyl-1-butene, 1-hexene, methyl-1-hexene, dimethyl-1-pentene, ethyl-1-pentene, trimethyl-1-butene, 1-octene and the like.

The propylene-based polymer (a) preferably has an isotactic index (II) indicating the degree of crystallinity of 95% or more, and more preferably 96% or more. When the isotactic index (II) is 95% or more, the heat resistance is high, which is preferable in terms of heat applied during printing and fusion to the heat seal bar during bag making. The crystallinity of the propylene-based polymer (a) can be controlled by controlling the molecular weight distribution depending on the copolymerization ratio of the raw materials and the catalyst used. The isotactic index (II), which indicates the index of crystallinity, is measured from the remaining amount (% by weight) when extracted with boiling heptane for 6 hours with an improved Soxhlet extractor.

[1-2] Propylene-α-olefin copolymer (b)
The propylene-α-olefin copolymer (b) used in the present invention is a propylene-α-olefin copolymer having a melting point of 110 to 140 ° C. When the melting point is 140 ° C. or lower, the crystallinity of the propylene-α-olefin copolymer (b) is lowered, and the crystallinity of the resin component existing around the antiblocking agent particles is also lowered, so that voids are generated. It becomes difficult and the dropout of the antiblocking agent is suppressed. On the other hand, when the melting point is 110 ° C. or higher, the production of a propylene-α-olefin copolymer becomes easy. The melting point of the propylene-α-olefin copolymer (b) is preferably 120 to 140 ° C, more preferably 125 to 140 ° C.
The heat of fusion is preferably 80 kJ / kg or less, more preferably 70 kJ / kg or less. As described above, the propylene-α-olefin copolymer (b) having a heat of fusion of 80 kJ / kg or less can maintain good dropout resistance due to a decrease in crystallinity. Here, the melting point and the calorific value for melting are values measured by a differential scanning calorimetry method (DSC method) based on the method described in JIS K7122 (1987).

The propylene-α-olefin copolymer is preferably a copolymer containing propylene and an α-olefin having 2 to 8 carbon atoms excluding propylene as a comonomer, more preferably having a propylene content of 85 to 97% by weight, still more preferably. It is a random copolymer of 85 to 95% by weight, particularly preferably 85 to 90% by weight of propylene and α-olefin. When the propylene content of the propylene-α-olefin copolymer (b) is 97% by weight or less, the crystallinity of the propylene-α-olefin copolymer (b) is lowered and is present around the antiblocking agent particles. Since the crystallinity of the resin component is also lowered, voids are less likely to be generated and the antiblocking agent is suppressed from falling off. On the other hand, when the propylene content is 85% by weight or more, the production of the propylene-α-olefin copolymer becomes easy. Here, it may be a mixture of random copolymers having different α-olefins. Further, one type of comonomer which is an α-olefin having 2 to 8 carbon atoms excluding propylene to be copolymerized with propylene may be used, or two or more types may be used in combination. As the propylene-α-olefin copolymer, a propylene-ethylene random copolymer, a propylene-ethylene-1-butene random copolymer and the like are preferable.

Examples of α-olefins having 2 to 8 carbon atoms excluding propylene include ethylene, 1-butene, 2-methyl-1-propene, 1-pentene, 2-methyl-1-butene, and 3-methyl-1-butene. , 1-Hexene, 2-ethyl-1-butene, 2,3-dimethyl-1-butene, 2-methyl-1-pentene, 3-methyl-1-pentene, 4-methyl-1-pentene, 3,3 Examples thereof include -dimethyl-1-butene, 1-hexene, methyl-1-hexene, dimethyl-1-pentene, ethyl-1-pentene, trimethyl-1-butene, 1-octene and the like.

The propylene-based polymer (a) and the propylene-α-olefin copolymer (b) used in the present invention preferably have a melt flow rate (hereinafter, also referred to as MFR) of 1 to 20 g / 10 minutes. More preferably, 1 to 10 g / 10 minutes. When the MFR is 1 g / 10 minutes or more and 20 g / 10 minutes or less, it is preferable in terms of extrudability and appearance.
The MFR was measured in accordance with ISO 1133: 1997 under the conditions of 230 ° C. and a 2.16 kg load. The unit is g / 10 minutes.
The MFR of the propylene-based polymer (a) and the propylene-α-olefin copolymer (b) can be obtained by changing the conditions of the polymerization temperature and the polymerization pressure, or by adding a chain transfer agent such as hydrogen at the time of polymerization. Easy to adjust.

The catalyst used to obtain the propylene-based polymer (a) and the propylene-α-olefin copolymer (b) used in the polypropylene-based resin composition of the present invention is not particularly limited, and known catalysts are not particularly limited. Can be used.
The Ziegler-Natta catalyst is, for example, "Polypropylene Handbook" Edward P. Moore Jr. It is a catalyst system as outlined in Section 2.3.1 (pages 20-57) of the Industrial Research Council (1998), edited and supervised by Tetsuo Yasuda and Nobu Sakuma. For example, titanium trichloride and halogen. For titanium trichloride catalysts made of organoaluminum, solid catalyst components containing magnesium chloride, titanium halide, and electron donating compounds as essentials, magnesium-supporting catalysts made of organoaluminum and organosilicon compounds, and solid catalyst components. It refers to a catalyst in which an organoaluminum compound component is combined with an organosilicon-treated solid catalyst component formed by contacting an organoaluminum and an organosilicon compound.
If it is a metallocene catalyst (for example, described in JP-A-5-295022), a Kaminsky-type catalyst using a metallocene compound can be used.

The polymerization process used to obtain the propylene-based polymer (a) and the propylene-α-olefin copolymer (b) used in the polypropylene-based resin composition of the present invention is not particularly limited. A known polymerization process can be used. For example, a slurry polymerization method, a bulk polymerization method, a gas phase polymerization method and the like can be used. Further, either a batch polymerization method or a continuous polymerization method can be used, and if desired, a multi-stage continuous polymerization method such as two-stage or three-stage may be used. It can also be produced by mechanically melt-kneading two or more kinds of propylene-based polymers (a) or propylene-α-olefin copolymers (b).
Further, the propylene-α-olefin copolymer (b) used in the present invention is preferably a propylene-ethylene random copolymer and a propylene-ethylene-1-butene random copolymer, and any ratio thereof is used. It may be a mixture mixed with.

The proportion of the resin component in the polypropylene-based resin composition (A) of the present invention is 100 parts by weight of the propylene-based polymer (a) from the viewpoint of heat applied during printing and fusion to a heat seal bar during bag making. On the other hand, the propylene-α-olefin copolymer (b) is 1 to 15 parts by weight, preferably 1 to 12 parts by weight, and more preferably 1 to 10 parts by weight.
The ratio of the resin component in the propylene-α-olefin resin composition (B) used in the present invention is a propylene-α-olefin copolymer (1 part by weight of the resin component) based on the viewpoint of shedding property of the antiblocking agent. b) is 50 to 100 parts by weight, preferably 80 to 100 parts by weight, more preferably 90 to 100 parts by weight, still more preferably 95 to 100 parts by weight, and particularly preferably 100 parts by weight. Here, as the resin component other than the propylene-α-olefin copolymer (b) that can be used in a proportion of 50 parts by weight or less, polypropylene having a higher melting point than the propylene-α-olefin copolymer (b). It is at least one selected from the based resin, that is, the propylene-α-olefin copolymer having a melting point of more than 140 ° C. and less than 150 ° C. and the propylene-based polymer (a).

[1-3] Anti-blocking agent The anti-blocking agent used in the present invention has an average particle size of 1.0 to 5.0 μm by the laser diffraction method, a specific surface area of 1 to 300 m ² / g by the BET method, and a pore volume. Is a standard spherical silica (c) having a surface area of less than 0.7 ml / g or an organic antiblocking agent (d) having an average particle size of 1.0 to 5.0 μm by laser diffraction.
The standard spherical silica (c) used in the present invention is standard spherical silicon dioxide. When the shape is spherical, the pore volume is smaller and the specific surface area is smaller than that of the amorphous shape, so that the dispersibility is excellent and the secondary aggregation is suppressed. As a result, in order to form a surface state having uniform roughness, it is possible to improve the blocking resistance and suppress the occurrence of vitiligo due to aggregation.
The standard spherical silica (c) used in the present invention has an average particle size of 1.0 to 5.0 μm, preferably 1.0 to 4.0 μm, and more preferably 1.5 to 3.5 μm. When it is 1.0 μm or more, the blocking prevention effect is excellent, and when it is 5.0 μm or less, the transparency is excellent.
The average particle size is a value measured by a laser diffraction method (based on ISO 13320 / JIS Z 8825-1).
Also, amorphous spherical silica (c) has a specific surface area of 1~300m ² / g, according to BET method is preferably 10~250m ² / g.
The standard spherical silica (c) used in the present invention has a pore volume of less than 0.7 ml / g, preferably 0.6 ml / g or less, while the lower limit is preferably 0.1 ml / g. Is.

The oil absorption of the standard spherical silica (c) is not particularly limited, but the oil absorption has a correlation with the specific surface area and can be said to indicate the structure of synthetic silica. Therefore, it is considered that the causal relationship is mainly high in the three-dimensional aggregate structure due to the property such as the amount of oil adsorbed. That is, if this value is large, it means that the synthetic silica simple substance tends to exist as an agglomerate. Therefore, the standard spherical silica used in the present invention is preferably 1 to 150 ml / 100 g, preferably 10 to 150 ml / 100 g. More preferred. When the oil absorption amount is 150 ml / 100 g or less, it is preferable from the viewpoint of dispersibility.

When the average particle size of the standard spherical silica (c) is 5.0 μm or less, the unevenness on the surface of the obtained film is reduced, so that the dropout property is improved. On the other hand, when the average particle size is 1.0 μm or more, the slip property and blocking resistance of the film at the time of winding are improved, which is preferable.
Further, when the specific surface area of the standard spherical silica (c) is 300 m ² / g or less, the silica is hard and has a structure that does not easily disintegrate, so that secondary aggregation is difficult. As a result, the number of vitiligo is reduced and the appearance is improved.
Similarly, when the pore volume is less than 0.7 ml / g, silica is hard and hard to disintegrate, so that when mixed with the powdery propylene-based polymer (a), it is hard to aggregate and white spots are reduced. Further, when the pore volume is less than 0.7 ml / g and is within the range of 0.1 ml / g or more, secondary agglutination due to silica particle decay is reduced, so that the number of white spots is unlikely to increase, and the appearance. It is preferable in that. Here, the measurement method of the pore volume is due to mercury porosimetry or N ₂ adsorption method.

The standard spherical silica (c) may be surface-treated with a surface treatment agent, and by treating with the surface treatment agent, the effect of improving the shedding property of the standard spherical silica (c) particles can be obtained. Examples of the surface treatment agent include paraffin, fatty acid, polyhydric alcohol, silane coupling agent, silicone oil, modified silicone oil, citric acid and the like. Among these, those surface-treated with a silane coupling agent, silicone oil, modified silicone oil or citric acid are preferable, and in particular, in order to further enhance the effect of improving the shedding property of silicon dioxide used as the standard spherical silica (c). A silane coupling agent or citric acid is preferably used as the surface treatment agent. The surface treatment agents listed above may be used alone or in combination of two or more.
Further, by using the standard spherical silica (c) surface-treated with a surface treatment agent, the dispersibility of the standard spherical silica (c) in the polypropylene resin can be improved, and the transparency and blocking resistance can be improved. A good biaxially stretched film can be obtained.

The surface treatment method is not particularly limited, and various known methods can be used. However, the surface treatment when a silicone oil or a modified silicone oil is used as the surface treatment agent and when a silane coupling agent is used is used. The method is illustrated below.

(1) In the case of silicone oil or modified silicone oil (1-1) Standard spherical silica while stirring a solution of silicone oil or modified silicone oil (dissolved in toluene, xylene, petroleum ether, isopropyl alcohol, volatile silicone oil, etc.) Is impregnated with a surface treatment agent, the solvent is removed, and heat baking treatment is performed.
(1-2) Using a mixer or a blender, the standard spherical silica is sprayed with silicone oil or modified silicone oil or a solution thereof while stirring, and heat-baked.

(2) In the case of silane coupling agent (2-1) Prepare a solution of silane coupling agent such as water and an organic solvent, add standard spherical silica while stirring this solution, and impregnate the surface treatment agent. The solvent is removed by filtration, squeezing, centrifugation, etc., and the solution is dried.
(2-2) Using a mixer or a blender, the standard spherical silica is sprayed with a solution of a silane coupling agent, water thereof, an organic solvent, etc. while stirring, and dried.
In addition, there is also a method of coating the surface of silica with a fatty acid metal salt, wax or the like.

The amount of silicone oil, modified silicone oil, or silane coupling agent used as a surface treatment agent for the standard spherical silica (c) cannot be unconditionally determined because it depends on the degree of surface treatment and the specific surface area of the standard spherical silica. The optimum amount can be determined by actually performing surface treatment on 100 parts by weight of spherical silica with about 0.5 to 20 parts by weight.
When using silicone oil and / or modified silicone oil, the heat baking treatment is usually about 5 to 30 minutes at a temperature of 200 to 350 ° C. for dimethyl silicone oil, and usually 120 for methylhydrogen silicone oil. It can be carried out at a temperature of about 150 ° C. for about 1 to 2 hours.

The silicone oil and the modified silicone oil that can be used for the surface treatment are not particularly limited, and examples of the silicone oil (straight silicone oil) include dimethylpolysiloxane, methylphenylpolysiloxane, and methylhydrogenpolysiloxane. The modified silicone oil includes those having an organic functional group in the side chain of dimethylpolysiloxane, those having an organic functional group at the end of the molecular chain, and those having both the side chain and the end. For example, fluoroalkylpolysiloxane, Carbinol-modified polysiloxane, polyether-modified polysiloxane, amino-modified polysiloxane, epoxy-modified polysiloxane, carboxyl-modified polysiloxane, methacryl-modified polysiloxane, mercapto-modified polysiloxane, phenol-modified polysiloxane, alkyl group-modified polysiloxane, methylstyryl Examples thereof include group-modified polysiloxane and fluorine-modified polysiloxane. Of these, methylhydrogen polysiloxane, carbinol-modified polysiloxane, amino-modified polysiloxane, epoxy-modified polysiloxane, carboxyl-modified polysiloxane, methacryl-modified polysiloxane, or mercapto-modified polysiloxane are preferably used.

The silane coupling agent that can be used for the surface treatment is not particularly limited, but for example, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris (β-methoxyethoxy) silane, vinyltriacetoxysilane, methyltrimethoxysilane, γ -Methyloxypropyltrimethoxysilane, methyltriethoxysilane, isobutyltrimethoxysilane, decyltrimethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane and the like can be mentioned. Among these, γ-methacryloxypropyltrimethoxysilane (organosilane) or 3-aminopropyltriethoxysilane (aminosilane) is preferable.

The organic antiblocking agent (d) used in the present invention has an average particle size of 1.0 to 5.0 μm by laser diffraction, preferably 1.0 to 4.0 μm, and more preferably 1.5 to 4.0 μm. It is 3.5 μm. When it is 1.0 μm or more, the blocking prevention effect is excellent, and when it is 5.0 μm or less, the transparency is excellent. Examples of the organic anti-blocking agent include crosslinked polymethyl methacrylate fine particles, non-melted polysiloxane fine particles, polyamide fine particles, acrylic resin fine particles, and condensed fine particles having a triazine ring. Among these, it is preferable to use crosslinked polymethylmethacrylate fine particles.

The content of the antiblocking agent used in the present invention is selected in the range of 0.01 to 1 part by weight, preferably 0.05 to 0.5 parts by weight, based on 100 parts by weight of the propylene-based polymer (a). .. When this content is 0.01 parts by weight or more, the blocking resistance when made into a film is excellent. Further, when it is 1 part by weight or less, the transparency when made into a film is excellent. The proportion (blending amount) of the anti-blocking agent in the propylene-α-olefin resin composition (B) used in the present invention is the resin component 100 in the resin composition (B) from the viewpoint of dispersibility of the anti-blocking agent. It is preferably 1 to 50 parts by weight, more preferably 1 to 20 parts by weight, still more preferably 1 to 10 parts by weight, and particularly preferably 1 to 5 parts by weight with respect to parts by weight.
As the anti-blocking agent used in the present invention, the corresponding product can be selected and used. The product corresponding to the standard spherical silica (c) can be obtained from, for example, Mizusawa Industrial Chemicals Co., Ltd., and as a specific commercially available product, a trade name: Mizupearl series can be mentioned. The product corresponding to the organic anti-blocking agent (d) can be obtained from Soken Chemical Co., Ltd., for example, and specific commercially available products include the trade name: Chemisnow MX series.

[1-4] Other Blending Agents In the polypropylene-based resin composition of the present invention, if necessary, additives usually used for polypropylene-based resins are appropriately blended within a range that does not impair the object of the present invention. Can be done. Examples of the additive include an antioxidant, an antistatic agent, a neutralizing agent, a stabilizer, an inorganic filler and the like.

[1-5] Method for preparing polypropylene-based resin composition (A) and propylene-α-olefin resin composition (B) As a method for preparing the polypropylene-based resin composition (A) of the present invention, a propylene-based polymer ( In the method of directly adding a predetermined amount of the propylene-α-olefin copolymer (b) and the standard spherical silica (c) or the organic antiblocking agent (d) to the powder or pellet of a), the periphery of the antiblocking agent particles It is not possible to reduce the crystallinity of the resin component present in the resin component and prevent the antiblocking agent from falling off.
In order to prepare the polypropylene-based resin composition (A) in order to exhibit the effects of the present invention, the propylene-α-olefin resin composition (B) described later, that is, the propylene-α-olefin copolymer (b) A composition (masterbatch) prepared by blending a powder or pellet with a predetermined amount of a standard spherical silica (c) or an organic antiblocking agent (d) and an additive to be used as needed is prepared in advance. A method of adding the masterbatch to the powder or pellet of the propylene-based polymer (a) is required.

The polypropylene-based resin composition (A) of the present invention is melted after mixing a predetermined amount of each of a propylene-based polymer (a), a propylene-α-olefin resin composition (B), and an additive used if necessary. Obtained by kneading.
For mixing, known methods such as a tumbler mixer, a super mixer, a Henschel mixer (trade name), a screw blender, and a ribbon blender can be applied. The melt-kneading is not particularly limited as long as it is a method of melt-kneading at a temperature equal to or higher than the melting point of the propylene-based polymer (a) using, for example, a melt extruder or a Banbury mixer.
The melt-kneading method can be easily carried out by either a single-screw extruder or a twin-screw extruder. However, in order to more effectively disperse the standard spherical silica (c) or the organic antiblocking agent (d), A shaft extruder is suitable.

The propylene-α-olefin resin composition (B) used in the present invention includes a propylene-α-olefin copolymer (b), a standard spherical silica (c) or an organic antiblocking agent (d), and if necessary. It is obtained by mixing each predetermined amount of the additive to be used and then melt-kneading.
For mixing, known methods such as a tumbler mixer, a super mixer, a Henschel mixer (trade name), a screw blender, and a ribbon blender can be applied. The melt-kneading is not particularly limited as long as it is a method of melt-kneading at a temperature equal to or higher than the melting point of the propylene-α-olefin copolymer (b) using, for example, a melt extruder or a Banbury mixer.
The melt-kneading method can be easily carried out by either a single-screw extruder or a twin-screw extruder. However, in order to more effectively disperse the standard spherical silica (c) or the organic antiblocking agent (d), A shaft extruder is suitable.

As a method for preparing the propylene-α-olefin resin composition (B) used in the present invention, it can also be obtained by the following side feed method. That is, in a melt extruder provided with a main hopper and a side feed supply port, a predetermined amount of propylene-α-olefin copolymer (b) powder or pellets is supplied from the main hopper, and standard spherical silica (standard spherical silica) (from the side feed supply port). It is obtained by a method of supplying a predetermined amount of c) or the organic antiblocking agent (d) and melt-kneading the propylene-α-olefin copolymer (b) at a temperature equal to or higher than the melting point. The powder or pellet of the propylene-α-olefin copolymer (b) is a powder or a mixture of the propylene-α-olefin copolymer (b) and a predetermined amount of an additive to be used as needed, and then melt-kneaded. It is a pellet.
For mixing, known methods such as a tumbler mixer, a super mixer, a Henschel mixer (trade name), a screw blender, and a ribbon blender can be applied. The melt-kneading performed after mixing is not particularly limited as long as it is a method of melt-kneading at a temperature equal to or higher than the melting point of the propylene-α-olefin copolymer (b) using, for example, a melt extruder or a Banbury mixer.
The melt-kneading method in a melt extruder equipped with a main hopper and a side feed supply port can be easily carried out by either a single-screw extruder or a twin-screw extruder, but a standard spherical silica (c) or an organic anti-blocking agent ( A twin-screw extruder is suitable for more effective dispersion of d).

[2] Laminated body The laminated body of the present invention is a laminated body composed of at least two layers having different layers (1) and (2), and the layer (1) is made of the polypropylene-based resin composition of the present invention. The layer (2) contains the propylene-based polymer (a), and the standard spherical silica (c) or the organic anti-blocking agent (d) is based on 100 parts by weight of the propylene-based polymer (a). The content is less than 0.01 parts by weight, preferably 0 parts by weight.

[2-1] Layer (1)
The layer (1) is a layer made of the polypropylene-based resin composition of the present invention. As will be described later, the biaxially stretched polypropylene film obtained from the laminate of the present invention obtained by forming a film is useful as a food packaging film, and at this time, the layer (1) is used as a non-printing surface. It is preferable to be used. By using the polypropylene-based resin composition of the present invention for the layer (1), a film having excellent blocking resistance and dispersibility as shown in Examples and good resistance to vitiligo and shedding can be obtained. Can be done.

[2-2] Layer (2)
The layer (2) is a layer containing the propylene-based polymer (a). When the biaxially stretched polypropylene film obtained from the laminate of the present invention obtained by forming a film is used as a food packaging film, it is preferably a laminate consisting of at least three layers. In this case, the layer (2) Is the core layer. Hereinafter, when the expression "core layer" is used, the description assumes a laminated body consisting of at least three layers.
The core layer is usually not blended with an anti-blocking agent, or even if it is used, the amount is preferably small. In the laminate of the present invention, in the layer (2), 100 parts by weight of the propylene-based polymer (a) is added. On the other hand, the content of the antiblocking agent is less than 0.01 parts by weight. In the resin composition used for the layer (2), the lower limit of the content of the antiblocking agent is 0.
The layer (2) is not particularly limited as long as it is a layer containing the propylene-based polymer (a), but the propylene-based polymer (a) may have good adhesion when laminated with the layer (1). ) Is preferably 50% by weight or more, more preferably 70% by weight or more, with the total component contained in the layer (2) as 100% by weight. In the laminate of the present invention, the same type of propylene-based polymer (a) may be used for the layer (1) and the layer (2), or different ones may be used. However, it is possible to use a combination of propylene-based polymers (a) used in each of the layer (1) and the layer (2) having similar physical properties such as melting point, MFR, and crystallinity. It is preferable from the viewpoint of adhesion between layers when

When the layer (2) is used as a core layer, the layer (2) preferably contains an antistatic agent. In the resin composition used for the layer (2), any conventionally known antistatic agent can be used, and examples thereof include cationic, anionic, and nonionic (glycerin, amine, and amide). Antistatic agents such as. These antistatic agents may be used alone or in combination of two or more.
In the layer (2), the antistatic agent is preferably 0.1 part by weight or more, more preferably 0.1 part by weight or more and 8 parts by weight with respect to 100 parts by weight of the propylene-based polymer (a). It is as follows. When it is 0.1 part by weight or more, the antistatic effect in the layer (2) becomes good, and the upper limit is usually 10 parts by weight from the viewpoint of the adhesion between the layer (1) and the layer (2).

[2-3] Other Layers In addition to the layers (1) and (2), the laminate of the present invention has other layers such as a laminate layer, an anchor coat layer, a sealant layer, and a printing layer. May be good. In particular, when the laminate of the present invention is used for a food packaging film or the like, it is possible to laminate the printing layer on the opposite side of the layer (2) with the layer (2) in between so that the laminate can be used for the food packaging film or the like. Is preferable.

[3] Biaxially Stretched Polypropylene Film The biaxially stretched polypropylene film of the present invention comprises the above-mentioned laminate of the present invention obtained by forming a film. Therefore, the biaxially stretched polypropylene film of the present invention is a multilayer film composed of two or more layers. The layer (1), which is a layer made of the polypropylene-based resin composition of the present invention described above, is a non-printing surface, and the layer in contact with the non-printing surface is a layer containing the propylene-based polymer (a) of the layer (2), specifically. It is preferable that the core layer is described above.

In the biaxially stretched polypropylene film of the present invention, the total thickness thereof is preferably 5 to 60 μm, more preferably 15 to 40 μm. The biaxially stretched polypropylene film of the present invention is widely used in packaging applications such as food packaging, textile packaging, and miscellaneous goods packaging.

The film surface of the biaxially stretched polypropylene film obtained from the polypropylene-based resin composition containing the standard spherical silica (c) or the organic anti-blocking agent (d) according to the present invention was subjected to a surface roughness meter manufactured by Tokyo Seimitsu Co., Ltd. SURFCOM 1500DX) or an equivalent device, in accordance with JIS B 0651 (2001) "Product Geometric Characteristics Specifications (GPS) -Surface Properties: Contour Curve Method-Characteristics of Stylus Surface Roughness Measuring Machine" The measured ten-point average roughness value (SRRz) is preferably in the range of 1.0 to 2.3 from the viewpoint of the balance between scratch resistance, dropout resistance, and blocking resistance. In particular, in the range of the ten-point average roughness value of 1.0 to 2.3, the smaller the value, the better the dropout property tends to be, while the ten-point average roughness value is 1.0 to 2. In the range of 3, the larger the value, the better the blocking resistance tends to be, which is preferable.

[3-1] Stretching Method of Biaxially Stretched Polypropylene Film The biaxially stretched polypropylene film of the present invention can be produced by a simultaneous or sequential biaxial stretching method or an inflation method. Above all, the sequential biaxial stretching method shown below is preferable.
The polypropylene-based resin composition of the present invention described above is melt-molded with a T-die to prepare a raw sheet, and then longitudinally stretched by utilizing the difference in roll peripheral speed. Specifically, the raw sheet is passed between two rolls having different rotation speeds at a temperature of usually 90 to 150 ° C., preferably 100 to 140 ° C., and usually 3 to 3 to in the rotation direction (longitudinal direction) of the rolls. Stretch 7 times, preferably 4 to 6 times. The longitudinally stretched film is then stretched in a tenter oven, usually 6-12 times, preferably 7-10 times.

Subsequently, it is desirable to heat-set this biaxially stretched polypropylene film at a temperature of usually 130 to 180 ° C. Further, for the purpose of improving printability and promoting the manifestation of the effect of the antistatic agent, heat treatment by corona discharge treatment or corona treatment and heating of the winder roll is preferably performed at 80 to 130 ° C., more preferably 90 to 120 ° C. It is carried out at ° C., more preferably 100 to 110 ° C.

[3-2] Applications of Biaxially Stretched Polypropylene Film The biaxially stretched film of the present invention is widely used in packaging applications such as food packaging, textile packaging, and miscellaneous goods packaging. It is preferably used on the opposite side of the food packaging film, which is not printed on the surface. In the case of the opposite side of the food packaging film that is not printed, it is required to add product value such as dropout property that occurs during production, blocking property that occurs in the secondary processing process and final product, transparency and appearance. Since the biaxially stretched polypropylene film of the present invention is excellent in these properties, it can be preferably used. When the biaxially stretched polypropylene film of the present invention is used as a food packaging film, the layer (1) made of the polypropylene-based resin composition of the present invention described above is used as a layer on the opposite side (non-printing surface) to which printing is not performed. It is preferable to use it because it can improve the product value and impart performance such as maintaining high quality.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the examples shown below are examples of embodiments of the present invention, and the present invention is not limited to the following examples. .. Further, the values of various production conditions and evaluation results in the following examples have meanings as preferable values of the upper limit or the lower limit in the embodiment of the present invention, and the preferable range is the above-mentioned upper limit or lower limit value. And may be in the range specified by the combination of the values of the following examples or the values of the examples.
The physical properties of Examples and Comparative Examples were measured by the following methods.

[Polypropylene resin characteristics]
1. 1. MFR:
The measurement was performed using a melt indexer L244 manufactured by Takara Thermistor, in accordance with ISO 1133: 1997, at 230 ° C. and a load of 2.16 kg. The unit is g / 10 minutes.
2. 2. Melting point:
The measurement was performed by a differential scanning calorimetry method (DSC method) based on the method described in JIS K7122 (1987) “Method for measuring transition heat of plastic”. The unit is ° C.
Specifically, 5.0 mg of a sample was taken using a Q2000 type differential thermal scanning calorimeter (DSC) manufactured by TA Instruments, and the temperature was once raised to 200 ° C. to erase the thermal history. After that, the temperature was lowered to −10 ° C. at a temperature lowering rate of 10 ° C./min, and the temperature was raised to 200 ° C. at a temperature rising rate of 10 ° C./min again, and the heat absorption peak top temperature was defined as the melting point. When a plurality of peaks were observed, the highest peak temperature was taken as the melting point.
3. 3. GPC (Q value)
The polypropylene-based resin in the present invention has a ratio [Mw / Mn (hereinafter referred to as Q value)] of a weight average molecular weight (Mw) and a number average molecular weight (Mn) obtained by gel permeation chromatography (GPC). It is preferably 5 to 5.5.
The Q value is an index showing the spread of the molecular weight distribution, and the larger this value is, the wider the molecular weight distribution is. Therefore, from the viewpoint of moldability, the Q value is preferably 2.5 or more, more preferably 2.6 or more, still more preferably 2.7 or more. On the other hand, from the viewpoint of cleanliness due to the amount of low molecular weight components, the Q value is preferably 5.5 or less, more preferably 5.2 or less.
The Q value is a physical property value affected by the uniformity of the active site of the catalyst, and since the catalyst containing a single metallocene complex has a relatively uniform active site, a catalyst containing a single metallocene complex is used. The propylene-based polymer thus obtained often has a Q value of about 2 to 2.5.
The specific measurement method of GPC is as follows.
-Device: Waters GPC (ALC / GPC 150C)
-Detector: MIRAN 1A IR detector manufactured by FOXBORO (measurement wavelength: 3.42 μm)
-Column: Showa Denko AD806M / S (3 in series)
-Mobile phase solvent: orthodichlorobenzene (ODCB)
・ Measurement temperature: 140 ℃
-Flow velocity: 1.0 ml / min
・ Injection amount: 0.2 ml
-Sample preparation: As a sample, prepare a 1 mg / mL solution using ODCB (containing 0.5 mg / mL BHT) and dissolve it at 140 ° C. for about 1 hour.
The conversion from the retention capacity obtained by GPC measurement to the molecular weight is performed using a calibration curve prepared in advance using standard polystyrene (PS). The standard polystyrenes used are all the following brands manufactured by Tosoh Corporation.
A solution dissolved in ODCB (including 0.5 mg / mL BHT) so that each of F380, F288, F128, F80, F40, F20, F10, F4, F1, A5000, A2500, and A1000 is 0.5 mg / mL. 0.2 mL is injected to create a calibration curve. The calibration curve uses a cubic equation obtained by approximating with the least squares method.
The following numerical values are used for the viscosity formula [η] = K × M ^α used for conversion to the molecular weight.
PS: K = 1.38 × 10 ^-4 , α = 0.7
PP: K = 1.03 × 10 ^-4 , α = 0.78
4. Comonomer composition
^{13 The} comonomer content was measured by the C-NMR method. That is, the measurement was carried out using GSX-400 FT-NMR manufactured by JEOL Ltd. at a measurement temperature of 130 ° C. and an integration number of 6000 times. The obtained peak is J. Apple. Polym. Sci. 80, 2001, 1880-1890. The comonomer (ethylene, 1-butene) content was calculated accordingly.

[Anti-blocking agent properties]
1. 1. Average particle size; measured using a laser diffraction particle size distribution measuring device.
2. 2. BET specific surface area: Calculated from nitrogen adsorption measurement using an automatic gas adsorption amount measuring device.
3. 3. Pore volume: Calculated from nitrogen adsorption measurement using an automatic gas adsorption amount measuring device.
4. Oil absorption: Measured according to JIS K5101.

[Film evaluation method]
1. 1. Evaluation of fusion to the seal bar The evaluation of fusion to the seal bar is as follows.
-Device: "TP-701-B HEAT SEAL TESTER" manufactured by Tester Sangyo Co., Ltd.
・ Seal temperature: 155 ° C
-Seal pressure: 2 kg / cm ² (0.20 MPa)
・ Sealing time: 1 sec
・ Seal bar: 1 cm x 20 cm
Two films described in Examples and Comparative Examples were stacked and inserted into the seal bar, and it was evaluated whether or not the films were fused to the seal bar when the film was sealed under the above-mentioned conditions.
⊚: No fusion to the seal bar is seen.
◯: Almost no fusion to the seal bar is seen ×: Fusion to the seal bar.
2. 2. Haze:
It was measured according to ASTM D-1003 using a turbidity meter (NDH2000) manufactured by Nippon Denshoku Co., Ltd. It was evaluated that the smaller the haze value, the better the transparency.

3. 3. Blocking strength (N / 10 cm ² ):
Measurements were made according to the method described in ASTM D-1893. Adjust the films to a size of 30 cm (width) x 20 cm (length), stack these films on the corona-treated and untreated surfaces, and place them in a gear oven at 40 ° C. under a load of 15 kg / cm ² (1.47 MPa). After leaving it in Tabi Espec / Tabi Gear Oven: GPH-100) for 7 days, the test piece cut into ² cm (width) x 15 cm (length) and overlapping area 10 cm ² was cut into a tensile tester (Toyo Seiki Seisakusho Co., Ltd.) The peel strength at a tensile speed of 500 mm / min was measured using a C-type shopper tensile strength tester). It was evaluated that the smaller the value of the peel strength, the better the blocking resistance.

4. Stacking blocking:
A sample of biaxially stretched polypropylene film is subjected to corona discharge treatment on both sides, the obtained film is adjusted to a size of 20 cm (width) x 20 cm (length), 20 sheets are stacked, and then sandwiched between glass plates to create an atmosphere of 50 ° C. The film was allowed to stand in a gear oven (manufactured by Tabie Spec Co., Ltd./Tabai Gear Oven: GPH-100) adjusted to the above for 5 days with a load of 50 kg applied.
The film peeling state when both ends of the obtained film were held and loosened by hand three times was evaluated by sensory evaluation, and the blocking resistance was evaluated in the following five stages.
Good blocking resistance: ◎ → ○ → △ → × → XX: Poor blocking resistance ◎: The films are already peeled off without being loosened by hand.
◯: After loosening by hand, the film is peeled off.
Δ: After loosening by hand, 50% or more of the film is in a peeled state.
X: After loosening by hand, 50% or more of the film is in close contact with the plate.
XX: After loosening by hand, the film is in close contact with the plate, and there is no peeled part.

5. Anti-blocking agent dropout test:
In the winding stroke of the biaxially stretched polypropylene film, a black mount was attached to a guide roll fixed so as not to rotate, and then the biaxially stretched polypropylene film was held for 5 minutes by sliding it on the surface of the mount. Then, the whiteness of the white powder portion of the anti-blocking agent adhering to the black mount was visually evaluated to evaluate the shedding property on a 5-point scale, and a value of ◯ or higher was considered good.
Good dropout: ◎ → ○ → △ → × → XX: Poor dropout ◎: Almost no white part.
◯: There is a white part.
Δ: There is a thin white part on the whole.
×: There is a clear white part on the whole.
XX: There is a dark white part on the whole.

6. Ten-point average roughness value (SRRz):
The surface of the film was measured with a surface roughness meter (SURFCOM 1500DX) manufactured by Tokyo Seimitsu Co., Ltd. In the present invention, the measurement was performed in accordance with JIS B 0651 (2001) "Geometric characteristic specifications (GPS) of the product-Surface texture: Contour curve method-Characteristics of stylus type surface roughness measuring machine". The measurement conditions of the measuring instrument are: radius of curvature of the tip of the stylus: 5 μm, cutoff wavelength: 0.05 mm, cutoff type: 2CR (phase compensation), measurement speed: 0.3 mm, measurement direction: MD direction of film, measurement range. : 2 mm ² . The MD direction, which is the measurement direction, refers to the feed direction of the film during extrusion molding, that is, the direction parallel to the longitudinal direction of the film.
The ten-point average roughness value is defined by JIS B 0601 (2001) "Geometric characteristic specifications (GPS) of the product-Surface texture: Contour curve method-Terms, definitions and surface texture parameters". When the ten-point average roughness value was in the range of 1.0 to 2.3, it was evaluated that the balance between dropout resistance and blocking resistance was good.

7. Maximum height (SRt)
The measurement was performed in the same manner as the ten-point average roughness value. The maximum height is defined in JIS B0601 (2001) "Geometric characteristic specifications (GPS) of products-Surface texture: Contour curve method-Terms, definitions and surface texture parameters". The smaller the value, the better the scratch resistance and dropout resistance.

8. Central plane mean (SRa)
The surface of the film was measured with a surface roughness meter (SURFCOM 1500DX) manufactured by Tokyo Seimitsu Co., Ltd. In the present invention, the measurement was performed in accordance with JIS B 0651 (2001) "Geometric characteristic specifications (GPS) of the product-Surface texture: Contour curve method-Characteristics of stylus type surface roughness measuring machine". The measurement conditions of the measuring instrument are: radius of curvature of the tip of the stylus: 5 μm, cutoff wavelength: 0.05 mm, cutoff type: 2CR (phase compensation), measurement speed: 0.3 mm, measurement direction: MD direction of film, measurement range. : 2 mm ² . The MD direction, which is the measurement direction, refers to the feed direction of the film during extrusion molding, that is, the direction parallel to the longitudinal direction of the film.
The mean value of the central surface is defined by JIS B 0601 (2001) "Geometric characteristic specifications (GPS) of the product-Surface texture: Contour curve method-Terms, definitions and surface texture parameters". When the mean value of the central surface was in the range of 0.01 to 0.03, it was evaluated that the balance between the dropout resistance and the blocking resistance was good.
9. Surface protrusion:
The film surface was measured under the same conditions as the ten-point average roughness value, and the number of protrusions of 0.1 μm or more per 2 mm ² was measured. When the value of the surface protrusions of 0.1 μm or more was 200 or more, the blocking resistance was evaluated as good.

10. Number of vitiligo:
Ten films were visually evaluated. A frame of 30 cm × 21 cm was arbitrarily made on the film, and the number of white spots in the frame was counted. It was evaluated that the smaller the number of vitiligo, the better the appearance.

[Material used]
[1] Polypropylene resin Various polypropylene resins shown in Table 1 were used.
[2] Anti-blocking agent The following is used as the standard spherical silica (c), and its characteristics are shown in Tables 2 and 3.
1. 1. Made by Mizusawa Industrial Chemicals, Inc., trade name "Mizupearl K-150" (average particle size 1.6 μm, BET specific surface area 149 m ² / g, pore volume 0.2 ml / g, oil absorption 55 ml / 100 g)
2. 2. Made by Mizusawa Industrial Chemicals Co., Ltd., trade name "Mizupearl K-300" (average particle size 2.8 μm, BET specific surface area 146 m ² / g, pore volume 0.5 ml / g, oil absorption 131 ml / 100 g)
3. 3. Mizusawa Industrial Chemicals Co., Ltd., trade name "Mizpearl K-500" (average particle size 4.9 μm, BET specific surface area 186 m ² / g, pore volume 0.4 ml / g, oil absorption 76 ml / 100 g)
The following are used as organic antiblocking agents, and their characteristics are shown in Tables 2 and 3.
1. 1. Made by Soken Chemical Co., Ltd., trade name "Chemisnow MX-180TA" (average particle size 1.8 μm)
The following is used as the amorphous silica (B), and its characteristics are shown in Table 3.
B-1: "Silicia 550" manufactured by Fuji Silysia Chemical Ltd. (average particle size 3.7 μm, BET specific surface area 500 m ² / g, bulk density 0.31 g / cm ³ , pore volume 0.8 ml / g, oil absorption Volume 140ml / 100g)

[Example 1]
As a method for obtaining the polypropylene-based resin composition (A), first, regarding the propylene-based polymer (a), the propylene-based polymer (a) shown in Table 1, that is, the propylene single weight obtained by using a Ziegler catalyst. against powder particles 100 parts by weight of polymer, from BASF Irganox (TM: Irganox) as an antioxidant 1010 and BASF Corp. Irgafos (TM Irgafo s) 168 respectively 0.05 parts by weight, a neutralizing agent After 0.05 parts by weight of calcium stearate was mixed and mixed with a Henshell mixer (trade name), melt extrusion was performed at a resin temperature of 230 ° C. using a 30 mmφ twin-screw extruder (PCM30 manufactured by Ikekai Co., Ltd.) to granulate. to obtain a composition of flops propylene-based polymer (a).
The resulting propylene polymer in the composition of the flop propylene-based polymer (a) (a) is a homopolymer of isotactic index showing a degree of crystallinity (II) 98% polypropylene (PP) Yes, MFR (ISO 1133: 1997 compliant MFR (measurement temperature 230 ° C, 2.16 kg load (21.18 N))) is 3 g / 10 minutes, and the lifting temperature speed is 10 ° C / min by SII DSC device RDC220U. The measured melting point was 165 ° C.
Next, regarding the propylene-α-olefin resin composition (B), the powder particles of the propylene-α-olefin copolymer (b) -1 shown in Table 1, that is, the propylene-ethylene-1-butene random copolymer. relative to 100 parts by weight, manufactured by BASF Irganox as an antioxidant (trademark: Irganox) 1010 and BASF Corp. Irgafos (TM Irgafo s) 168 respectively 0.05 parts by weight of calcium stearate as a neutralizing agent 0 1.8 parts by weight of the standard spherical silica (c) having an average particle size of 1.6 μm shown in Table 2 as 0.05 parts by weight and silicon dioxide was mixed, mixed with a Henschel mixer (trade name), and then a biaxial 30 mmφ. using an extruder (Ikegai Corporation PCM 30) was granulated at a resin temperature of 230 ° C. was melt-extruded to obtain a flop propylene -α- olefin resin composition (B) -1.
Then, with respect to the propylene polymer (a) 100 parts by weight of the composition of the flop propylene-based polymer (a), at a ratio of propylene -α- olefin copolymer (b) -1 is 10 parts by weight As described above, the propylene-α-olefin resin composition (B) -1 was blended and mixed with an auto blender (trade name, automatic weight weighing and coloring mixer manufactured by Tamaki Co., Ltd.) to form a polypropylene resin composition (A). I got -1.
[Example 2]
As silicon dioxide, the standard spherical silica (c) having an average particle size of 2.8 μm shown in Table 2 was used, and propylene- using the powder particles of the propylene-α-olefin copolymer (b) -1 shown in Table 1. A polypropylene-based resin composition (A) -2 was obtained in the same manner as in Example 1 except that the α-olefin resin composition (B) -2 was used.
[Example 3]
As the silicon dioxide, the standard spherical silica (c) having an average particle size of 2.8 μm shown in Table 2 was used, and the propylene-α-olefin copolymer (b) -2 shown in Table 1, that is, propylene-ethylene-1-butene. A polypropylene-based resin composition (A) -3 was obtained in the same manner as in Example 1 except that the propylene-α-olefin resin composition (B) -3 was prepared by using powder particles of a random copolymer.
[Example 4]
As the silicon dioxide, the standard spherical silica (c) having an average particle size of 2.8 μm shown in Table 2 was used, and the propylene-α-olefin copolymer (b) -3 shown in Table 1, that is, propylene-ethylene-1-butene. A polypropylene resin composition (A) -4 was obtained in the same manner as in the method of Example 1 except that the propylene-α-olefin resin composition (B) -4 using powder particles of a random copolymer was prepared.
[Example 5]
Using the standard spherical silica (c) having an average particle size of 2.8 μm shown in Table 2 as silicon dioxide, the propylene-α-olefin copolymer (b) -4 shown in Table 1, that is, the propylene-ethylene random copolymer. A polypropylene-based resin composition (A) -5 was obtained in the same manner as in Example 1 except that the propylene-α-olefin resin composition (B) -5 was prepared using the powder particles of.
[Example 6]
As silicon dioxide, standard spherical silica (c) having an average particle size of 4.9 μm shown in Table 2 was used, and propylene- using powder particles of the propylene-α-olefin copolymer (b) -1 shown in Table 1. A polypropylene resin composition (A) -6 was obtained in the same manner as in Example 1 except that the α-olefin resin composition (B) -6 was used.
[Example 7]
The organic antiblocking agent (d) having an average particle size of 1.8 μm shown in Table 2 as polymethylmethacrylate (PMMA) is used as the powder of the propylene-α-olefin copolymer (b) -1 shown in Table 1. relative to the particle 100 parts by weight of a propylene resin composition obtained by blending 3.6 parts by weight and (B) -7, thereafter propylene polymer in the composition of the flop propylene-based polymer (a) (a) 100 parts by weight On the other hand, the method of Example 1 except that the propylene-α-olefin resin composition (B) -7 was blended so that the proportion of the propylene-α-olefin copolymer (b) -1 was 7 parts by weight. The polypropylene-based resin composition (A) -7 was obtained in the same manner as in the above.
[Example 8]
The organic antiblocking agent (d) having an average particle size of 1.8 μm shown in Table 2 as polymethylmethacrylate (PMMA) is used as the powder of the propylene-α-olefin copolymer (b) -1 shown in Table 1. relative to the particle 100 parts by weight, the propylene resin composition containing 3.6 parts by weight (B) -8, thereafter propylene polymer in the composition of the flop propylene-based polymer (a) (a) 100 parts by weight On the other hand, the method of Example 1 except that the propylene-α-olefin resin composition (B) -8 was blended so that the proportion of the propylene-α-olefin copolymer (b) -1 was 8 parts by weight. The polypropylene-based resin composition (A) -8 was obtained in the same manner as in the above.

[Comparative Example 1]
An anti-blocking agent masterbatch containing 1.8 parts by weight of amorphous silica having an average particle size of 3.7 μm shown in Table 3 as silicon dioxide with respect to 100 parts by weight of powder particles of the propylene-based polymer (a) (hereinafter, , MB abbreviated.) MB (to create the a) -1, to then propylene polymer in the composition of the flop propylene-based polymer (a) (a) 100 parts by weight, MB (a) in -1 The polypropylene-based resin composition (A) -9 was prepared in the same manner as in the method of Example 1 except that MB (a) -1 was blended so that the proportion of the propylene-based polymer (a) was 10 parts by weight. Obtained.
[Comparative Example 2]
MB (a) containing 1.8 parts by weight of standard spherical silica (c) having an average particle size of 2.8 μm shown in Table 3 as silicon dioxide with respect to 100 parts by weight of powder particles of the propylene-based polymer (a). -2 create, to then propylene polymer in the composition of the flop propylene-based polymer (a) (a) 100 parts by weight, MB (a) propylene polymer in -2 (a) is 10 A polypropylene-based resin composition (A) -10 was obtained in the same manner as in the method of Example 1 except that MB (a) -2 was blended in a proportion of parts by weight.
[Comparative Example 3]
Flop propylene-based polymer of propylene -α- olefin copolymer according to Table 1 is a melting point of 126 ° C. as instead of the composition of (a) (b) -1 i.e. a propylene - ethylene-1-butene random copolymer and flop propylene -α- olefin copolymer using powder particles (b) -1 of the composition, and methods and propylene -α- olefin resin composition obtained in the same manner (B) -2 example 2 The polypropylene-based resin composition (A) -11 was obtained in the same manner as in the method of Example 1 except that
[Comparative Example 4]
Table 1 shows that the standard spherical silica (c) having an average particle size of 2.8 μm shown in Table 3 is used as silicon dioxide, and the melting point is 142 ° C. instead of the propylene-α-olefin copolymer (b) -1. The polypropylene resin composition is the same as that of the method of Example 1, except that the propylene-α-olefin copolymer (b'), that is, MB (B) -9 using powder particles of the propylene-ethylene random copolymer is used. Object (A) -12 was obtained.
[Comparative Example 5]
The organic antiblocking agent (d) having an average particle size of 1.8 μm shown in Table 3 as polymethylmethacrylate (PMMA) was added by 1.8 weight with respect to 100 parts by weight of the powder particles of the propylene polymer (a). part create a MB (a) -3 formulated, to then propylene polymer in the composition of the flop propylene-based polymer (a) (a) 100 parts by weight, MB (a) propylene in the -3 A polypropylene-based resin composition (A) -13 was obtained in the same manner as in Example 1 except that MB (a) -3 was blended so that the polymer (a) was in an amount of 10 parts by weight.
[Comparative Example 6]
The organic antiblocking agent (d) having an average particle size of 1.8 μm shown in Table 3 as polymethyl methacrylate (PMMA) was added to 83 parts by weight of the powder particles of the propylene polymer (a) and propylene-α-olefin. create a copolymer (b) -1 of powder particles 17 parts by weight of the total of 100 parts by weight of MB blended 1.8 parts by weight with respect to the powder particles of (a) -4, then flop propylene-based polymer (a ) , The total of the propylene-based polymer (a) and the propylene-α-olefin copolymer (b) -1 in MB (a) -4 with respect to 100 parts by weight of the propylene-based polymer (a) in the composition of ). A polypropylene-based resin composition (A) -14 was obtained in the same manner as in the method of Example 1 except that MB (a) -4 was blended so that the amount was 10 parts by weight.
[Comparative Example 7]
The organic antiblocking agent (d) having an average particle size of 1.8 μm shown in Table 3 as polymethylmethacrylate (PMMA) was added to 67 parts by weight of the powder particles of the propylene polymer (a) and propylene-α-olefin. create a copolymer (b) -1 powder particles 33 MB blended 1.8 parts by weight based on 100 parts by weight of powder particles of the parts (a) -5, then flop propylene-based polymer (a ) , The total of the propylene-based polymer (a) and the propylene-α-olefin copolymer (b) -1 in MB (a) -5 with respect to 100 parts by weight of the propylene-based polymer (a) in the composition of ). A polypropylene-based resin composition (A) -15 was obtained in the same manner as in Example 1 except that MB (a) -5 was blended so that the amount was 10 parts by weight.
[Comparative Example 8]
Instead of blending the propylene-α-olefin resin composition (B) prepared in advance with the propylene-based polymer (a), Table 3 represents silicon dioxide as silicon dioxide with respect to 100 parts by weight of the powder particles of the propylene-based polymer (a). 0.18 parts by weight of the standard spherical silica (c) having an average particle size of 2.8 μm, 10 parts by weight of the powder particles of the propylene-α-olefin copolymer (b) -1, BASF as an antioxidant. Ltd. Irganox (TM: Irganox) 1010 and BASF Corp. Irgafos (TM Irgafo s) 168 respectively 0.05 parts by weight, and 0.05 part by weight of calcium stearate as a neutralizing agent, except where directly blended , A polypropylene-based resin composition (A) -16 was obtained in the same manner as in Example 1.

Next, the polypropylene-based resin compositions (A) of Examples 1 to 8 and Comparative Examples 1 to 8 were used as raw materials for the surface layer (corresponding to the layer (1)) and as raw materials for the intermediate layer (corresponding to the layer (2)). , PP-1 (Novatec (registered trademark) PP FL203D manufactured by Japan Polypropylene Corporation (propylene polymer, MFR 3.0 g / 10 minutes, melting point 162 ° C)) was melt-extruded at a resin temperature of 250 ° C. It was rapidly cooled with a cooling roll at ° C. to prepare a two-kind, three-layer raw sheet.
The sheet was stretched 5 times in the vertical direction using a longitudinal stretching machine adjusted to a roll temperature of 120 ° C. and 10 times in a horizontal direction using a transverse stretching machine adjusted to a furnace temperature of 160 ° C., and the thickness was 20 μm (the surface layer was 20 μm). A biaxially stretched polypropylene film (1.5 μm) was obtained. At this time, corona discharge treatment was performed so that the wetting index of one side of the wetting reagent was 40 dyne / cm.
Table 2 shows the physical properties of the obtained biaxially stretched polypropylene film.

As is clear from Tables 1 to 3, a biaxially stretched polypropylene film using silicon dioxide or an organic antiblocking agent used in Examples 1 to 8, that is, the standard spherical silica (c) or organic according to the present invention. The biaxially stretched polypropylene film using the anti-blocking agent (d) was excellent in blocking resistance and dispersibility, had few white spots, and was good in terms of the anti-blocking agent's shedding property.
On the other hand, in the films of Comparative Examples 1 to 8, a film having an excellent balance of various physical properties could not be obtained.
That is, Comparative Example 1 was an anti-blocking agent outside the scope of the present invention, and had poor dispersibility.
The anti-blocking agent of Comparative Example 2 was the same as that of Example 2, but dropped out because the propylene-α-olefin copolymer (b) was not blended with the propylene-based polymer (a). The sex is getting worse.
In Comparative Example 3, a standard spherical anti-blocking agent was used, and the propylene-α-olefin copolymer (b) was blended with each other without using the propylene-based polymer (a), but the dropability and dispersion were observed. Although the property is good, the melting point of the base polypropylene is low and the heat resistance is lowered, so that the meltability to the seal bar is deteriorated.
In Comparative Example 4, a standard spherical antiblocking agent was used, and the melting point of the propylene-α-olefin copolymer (b) was higher than the claimed range, so that the crystallinity of the resin component existing around the antiblocking agent could be lowered. Since it is not, the dropout property is getting worse.
Comparative Example 5 is an organic anti-blocking agent, and similarly to Comparative Examples 1 and 2, a propylene-α-olefin copolymer (b) is blended with the propylene-based polymer (a). Since there is no dropout, the dropout property is worsening.
In Comparative Examples 6 and 7, the organic antiblocking agent (d) was blended with the mixture of the propylene-based polymer (a) and the propylene-α-olefin copolymer (b). Since the proportion of the propylene-α-olefin copolymer (b) in the resin component in the propylene-α-olefin resin composition (B) is not satisfied, the crystallinity of the resin component existing around the antiblocking agent can be lowered. Since there is no such thing, the dropout property is worsening.
In Comparative Example 8, 0.18 parts by weight of the direct standard spherical silica (c) and 10 parts by weight of the propylene-α-olefin copolymer (b) -1 were added to 100 parts by weight of the propylene-based polymer (a). Although it is partially blended, it is not a method of masterbatch using the propylene-α-olefin copolymer (b) in advance and blending it, so that the crystallinity of the resin component existing around the antiblocking agent can be lowered. Since it is not, the dropout property is getting worse.

The polypropylene-based resin composition of the present invention, a laminate made of the same, and a biaxially stretched polypropylene film have a good balance of various physical properties such as blocking resistance, dispersibility, transparency, and shedding property. Therefore, for example, food packaging and fiber packaging. , Widely used in packaging applications such as miscellaneous goods packaging, and can be particularly suitably used in applications of food packaging films.

Claims (5)

A polypropylene-based resin composition (A) containing a propylene-based polymer (a) having a melting point of 150 ° C. or higher and a propylene-α-olefin resin composition (B), wherein the propylene-α-olefin resin composition ( B) is a composition obtained by blending a propylene-α-olefin copolymer (b) having a melting point of 110 to 140 ° C. and an antiblocking agent, and the antiblocking agent has an average particle size obtained by a laser diffraction method. Fixed spherical silica (c) with a specific surface area of 1.0 to 5.0 μm, a specific surface area of 1 to 300 m ² / g by the BET method, and a pore volume of less than 0.7 ml / g, or an average particle size of 1.0 by the laser diffraction method. It is an organic antiblocking agent (d) of ~ 5.0 μm, and the content of the antiblocking agent in the polypropylene resin composition (A) is 0.01 with respect to 100 parts by weight of the propylene polymer (a). The ratio of the resin component in the polypropylene-based resin composition (A) is 1 to 1 part by weight, and the ratio of the propylene-α-olefin copolymer (b) is 1 to 100 parts by weight of the propylene-based polymer (a). The ratio of the resin component in the propylene-α-olefin resin composition (B) is 15 parts by weight, and the ratio of the propylene-α-olefin copolymer (b) is 50 to 100 parts by weight with respect to 100 parts by weight of the resin component. der is, the polypropylene resin composition resin component and propylene -α- olefin resin composition in (a) polypropylene-based resin composition in which the resin component in (B) is characterized by a polypropylene resin der Rukoto (a) .. The propylene -α- olefin copolymer (b), the melt flow rate (230 ° C., 2.16 kg load) is from 1 to 20 g / 10 min, a melting point of 120 to 140 ° C. propylene - ethylene Nra random copolymer polymer or a propylene - ethylene-1-butene random copolymer der is, propylene - ethylene random copolymer polypropylene resin composition according to claim 1 Ru copolymer der bicomponent propylene and ethylene .. A laminate composed of at least two layers having different layers (1) and (2), wherein the layer (1) is made of the polypropylene-based resin composition according to claim 1 or 2, and the layer (2) is The content of the standard spherical silica (c) or the organic antiblocking agent (d) containing the propylene-based polymer (a) is 0.01 with respect to 100 parts by weight of the propylene-based polymer (a). A laminate that is less than parts by weight. A biaxially stretched polypropylene film comprising the laminate according to claim 3. A food packaging film comprising the biaxially stretched polypropylene film according to claim 4.