JP2016199699A - Manufacturing method of granulated body of polypropylene resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a granulated body of a polypropylene resin composition having high intrinsic viscosity and suppressed generation of fish eye even with having a propylene ethylene random copolymer with high percentage of content.SOLUTION: There is provided a manufacturing method of a granulated body of a polypropylene resin composition of the like including granulation of a polypropylene resin composition (C) containing at least two kind of a propylene (co)polymer (A) having MFR of 0.5 to 100 g/10 min. and a propylene ethylene random copolymer (B) having intrinsic viscosity of 6 to 20 dl/g by using a metal filter (D) knitted by a longitudinal wire and a lateral wire as shown in Figure 1, where the longitudinal wire is lined with a predetermined distance interval and the lateral wire satisfies requirements such as having a structure with a phase contact with neighboring lateral wire.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for producing a granulated body of a polypropylene resin composition, and more specifically, in a polypropylene resin composition containing a propylene / ethylene copolymer having a high intrinsic viscosity, polypropylene capable of suppressing the occurrence of fish eyes. The present invention relates to a method for producing a granulated body of a resin composition.

Polypropylene-based resin compositions are usually produced by melting and extruding (co) polymer powder, (co) polymer pellets, and a mixture thereof to form a granulated product. Widely used in various applications such as parts.
Among them, many propylene / ethylene copolymers with high intrinsic viscosity are included for the purpose of improving impact resistance, improving melt tension, improving flow marks, and reducing surface gloss to make high-quality matte. A polypropylene resin composition may be desired.
However, in a granulated product of a polypropylene resin composition containing a large amount of propylene / ethylene copolymer having a high intrinsic viscosity, there is a problem in that a component having a high intrinsic viscosity is poorly dispersed, resulting in a poor appearance called so-called fish eye. It was.

For example, Patent Document 1 and Patent Document 2 disclose techniques for producing a polypropylene resin composition containing a propylene / ethylene random copolymer component having a high intrinsic viscosity by reducing the generation of fish eyes.
Patent Document 1 discloses that a polypropylene resin composition with reduced fish eye can be produced by kneading three components each having a specific composition and melt viscosity at a specific ratio. ing.
Patent Document 2 discloses that a polypropylene resin composition with reduced fish eye can be produced by stepwise melting and kneading three components each having a specific composition and melt viscosity at a specific ratio. It is disclosed.
However, although all of the above methods have some effects, the content of components with high intrinsic viscosity is low in the final product stage, and the content of components with higher intrinsic viscosity is increased, and further fish eye improvement technology is desired. It is rare.

In addition, as a technique for removing fish eyes from a polymer in a polypropylene blend, Patent Document 3 discloses that in order to reduce the amount of polymer gel in a polypropylene blend containing at least two types of polypropylene polymers, the polypropylene blend is 44 to 900 μm. A method of reducing the amount of polymer gel is disclosed which includes reducing the number and size of gels in a polypropylene blend through a plurality of screen filters.
However, in the method of Patent Document 3, the effect when the melt viscosity of the propylene / ethylene copolymer is high is not disclosed.
In addition, when fisheye is exposed to the end-users of products, it can cause consumers to feel uneasy, so the market demand for fisheye has become higher in recent years. Further technical improvements were desired.

Japanese Patent No. 3937696 (Japanese Patent Laid-Open No. 2002-012734) Japanese Patent No. 5082200 (Japanese Patent Laid-Open No. 2005-325339) Japanese Patent No. 3244711 (Special Table 2000-511967)

  The object (problem) of the present invention is to suppress the generation of fish eyes even in the case of having a high proportion of propylene / ethylene random copolymer having a high intrinsic viscosity and a high content in view of the problems of the prior art. Another object of the present invention is to provide a method for producing a granulated product of a polypropylene resin composition.

  As a result of intensive studies in order to solve the above problems, the present inventors have adopted the production conditions of a specific range of resin granule for the specific composition range of resin, and thereby the intrinsic viscosity and The inventors have found that a granulated product of a polypropylene resin composition having a propylene / ethylene random copolymer having a high content ratio can be produced without the problem of fish eyes, and completed the present invention.

That is, according to the first invention of the present invention, the propylene (co) polymer (A) satisfying the following requirements (A-1) and (A-2), the following (B-1) and (B- 2) The polypropylene resin composition (C) containing at least two types of the propylene / ethylene random copolymer (B) that satisfies the requirements of (2) satisfies the requirements of (D-1) to (D-4) below. There is provided a method for producing a granulated body of a polypropylene resin composition, characterized by granulating using the metal filter (D).
Requirement (A-1): Melt flow rate (MFR: 230 ° C., 2.16 kg load) is 0.5 to 100 g / 10 min.
Requirement (A-2): The content of the propylene (co) polymer (A) is 100% by weight in total of the propylene (co) polymer (A) and the propylene / ethylene random copolymer (B). 10 to 95% by weight.
Requirement (B-1): Intrinsic viscosity [η] copy is 6 to 20 dl / g.
Requirement (B-2): Content of propylene / ethylene random copolymer (B) with respect to 100% by weight in total of propylene (co) polymer (A) and propylene / ethylene random copolymer (B) Is 5 to 90% by weight.
Requirement (D-1): Woven from a vertical wire and a horizontal wire, the vertical wires are arranged at a predetermined distance, and the horizontal wire has a structure having a phase contact with an adjacent horizontal wire.
Requirement (D-2): The horizontal wire repeats the structure which cross | intersects so that a space may be vacant after crossing the fixed number of vertical wires which are at least 2 or more.
Requirement (D-3): The crossing point of the horizontal wire with the vertical wire is arranged so as to exhibit a ninety-nine fold aspect on the layer.
Requirement (D-4): It has a structure in which the horizontal wires do not overlap in the vertical direction with respect to the layer on the layer.

According to the second invention of the present invention, in the first invention, the polypropylene resin composition (C) is continuously polymerized using at least two or more connected polymerization tanks. By the above, the manufacturing method of the granulated body of the polypropylene resin composition characterized by being manufactured is provided.
Furthermore, according to a third invention of the present invention, in the second invention, the at least two or more connected polymerization tanks are such that the first polymerization tank and the second polymerization tank are fluidized bed reactors. A method for producing a granulated product of a polypropylene resin composition is provided.

According to a fourth invention of the present invention, in the second invention, the at least two or more connected polymerization tanks are horizontal reactors in which the first polymerization tank and the second polymerization tank have stirring blades. There is provided a method for producing a granulated body of a polypropylene resin composition, which is characterized in that
Furthermore, according to the fifth invention of the present invention, in the second invention, the at least two or more connected polymerization tanks are the following: (i) to (v) A method for producing a granulated body of a polypropylene resin composition characterized by satisfying the above requirements is provided.
Requirement (i): The polymerization temperature of the second polymerization tank is 70 ° C. or lower.
Requirement (ii): The average reaction time of the powder held in the first polymerization tank is an average residence time of the powder held in the second polymerization tank + 0.5 hours or less.
Requirement (iii): The average polymerization temperature difference between the second polymerization tank and the first polymerization tank is −10 to 10 ° C.
Requirement (iv): The molar concentration ratio (H ₂ / propylene) of hydrogen and propylene in the second polymerization tank is 0.01 or less.
Requirement (v): The molar ratio (alcohol / organoaluminum compound) of the alcohol supplied to the second polymerization tank to the organoaluminum compound supplied to the first polymerization tank is 0.8 to 2.0.

  The method for producing a granulated product of the polypropylene resin composition of the present invention suppresses the generation of fish eyes by using a granulated material of a polypropylene resin composition having a high content of propylene / ethylene random copolymer having a high intrinsic viscosity. However, it is highly productive and manufacturable.

Fig.1 (a) is a photograph explaining the metal filter of the special twilling weave used by the manufacturing method of the granulated body of the polypropylene resin composition of this invention, FIG.1 (b) is a special twilling weave. It is an enlarged photograph of the photograph explaining the metal filter of. FIG. 2 is a photograph explaining a twill metal filter usually used in a method for producing a propylene-based resin granulated body. FIG. 3 is a photograph explaining a plain woven metal filter usually used in a method for producing a propylene-based resin granulated body.

  Hereinafter, embodiments of the present invention will be described in detail for each item. The description of the constituent requirements described below is an example of embodiments of the present invention, and the present invention is not limited to these contents.

The present invention includes a propylene (co) polymer (A) that satisfies the following requirements (A-1) and (A-2), and propylene / ethylene that satisfies the following requirements (B-1) and (B-2): A polypropylene resin composition (C) containing at least two types of random copolymer (B) and a metal filter (D) satisfying the following requirements (D-1) to (D-4) are used. And granulating the polypropylene resin composition, which is characterized by granulating.
Requirement (A-1): Melt flow rate (MFR: 230 ° C., 2.16 kg load) is 0.5 to 100 g / 10 min.
Requirement (A-2): The content of the propylene (co) polymer (A) is 100% by weight in total of the propylene (co) polymer (A) and the propylene / ethylene random copolymer (B). 10 to 95% by weight.
Requirement (B-1): Intrinsic viscosity [η] copy is 6 to 20 dl / g.
Requirement (B-2): Content of propylene / ethylene random copolymer (B) with respect to 100% by weight in total of propylene (co) polymer (A) and propylene / ethylene random copolymer (B) Is 5 to 90% by weight.
Requirement (D-1): Woven from a vertical wire and a horizontal wire, the vertical wires are arranged at a predetermined distance, and the horizontal wire has a structure having a phase contact with an adjacent horizontal wire.
Requirement (D-2): The horizontal wire repeats the structure which cross | intersects so that a space may be vacant after crossing the fixed number of vertical wires which are at least 2 or more.
Requirement (D-3): The crossing point of the horizontal wire with the vertical wire is arranged so as to exhibit a ninety-nine fold aspect on the layer.
Requirement (D-4): It has a structure in which the horizontal wires do not overlap in the vertical direction with respect to the layer on the layer.

Hereinafter, the present invention will be described in detail for each item.
1. Propylene (co) polymer (A)
The propylene (co) polymer (A) according to the present invention is usually a propylene homopolymer (homopolymer) obtained by homopolymerization of propylene, but a small amount of comonomer is added within a range not impairing the effect of the present invention. It may be a copolymerized propylene copolymer.
Such comonomers include α-olefins such as ethylene and 1-butene. The comonomer content is preferably less than 3% by weight, more preferably less than 1% by weight, based on the propylene copolymer.

  The propylene (co) polymer (A) according to the present invention may be produced by single-stage polymerization or multistage polymerization, and is usually produced by single-stage polymerization. When the propylene (co) polymer (A) is produced by multistage polymerization, the physical properties such as MFR and intrinsic viscosity [η] are the propylene (co) polymer (A) obtained at the end of the final polymerization. The physical properties of When the propylene (co) polymer (A) is produced by multistage polymerization, among the (co) polymers produced in the respective polymerization stages, the (co) weight having a comonomer content of less than about 6% by weight The coalescence should be considered as a constituent of the propylene (co) polymer (A).

  The melt flow rate (MFR) of the propylene (co) polymer (A) is 0.5 to 100 g / 10 minutes, preferably 1 to 60 g / 10 minutes, more preferably 2 to 50 g / 10 minutes, and still more preferably 3. ~ 40 g / 10 min. When the MFR is less than 0.5 g / 10 min, the mesh pressure of the screen mesh is easily generated due to an increase in the resin pressure due to a decrease in the fluidity of the resin. That is, when the MFR is within the above range, the fish eye improving effect is easily obtained.

2. Propylene / ethylene random copolymer (B)
The propylene / ethylene random copolymer (B) according to the present invention is a propylene / ethylene random copolymer usually obtained by copolymerization of propylene and ethylene, but in a range not impairing the object of the present invention, a small amount Multi-component copolymers such as terpolymers obtained by copolymerizing other comonomers may also be used.
Such other monomers include α-olefins such as 1-butene.

  The propylene / ethylene random copolymer (B) according to the present invention may be produced by single-stage polymerization or multistage polymerization, and is usually produced by single-stage polymerization. When a propylene / ethylene random copolymer is produced by multistage polymerization, among the copolymers produced in the respective polymerization stages, a copolymer having an ethylene comonomer content of about 6% by weight or more is produced by propylene / ethylene random copolymer. It should be considered as a constituent of the ethylene random copolymer.

  In the propylene / ethylene random copolymer (B) according to the present invention, the ethylene content is preferably 5 to 80% by weight, more preferably 5 to 45% by weight, and still more preferably 15 to 43% by weight. Most preferably, it is 20 to 40% by weight. When the ethylene content is within the above range, the molded product of the polypropylene resin composition (C) itself described later is excellent in appearance, and physical properties such as low temperature impact resistance and melt tension are also good.

In addition, the intrinsic viscosity [η] copolymer of the propylene / ethylene random copolymer (B) according to the present invention is 6 to 20 dl / g, preferably 8 to 14 dl / g, more preferably 8.5. It is 13 dl / g, More preferably, it is 9-12 dl / g. When the intrinsic viscosity [η] copy is within the above range, various physical properties such as impact resistance and melt tension are improved.
Here, the intrinsic viscosity is a value obtained by measuring at a temperature of 135 ° C. using decalin as a solvent using an Ubbelohde viscometer. The intrinsic viscosity obtained by measuring decalin as a solvent at a temperature of 135 ° C. is said to have a correlation with MFR. For example, in the case of propylene homopolymer, MFR of 0.28 g / 10 min has an intrinsic viscosity of 3.624 dl / It is said that an MFR of 0.99 g / 10 min corresponds to an intrinsic viscosity of 2.879 dl / g, and an MFR of 4.00 g / 10 min corresponds to an intrinsic viscosity of 1.991 dl / g.

3. Polypropylene resin composition (C) and production method thereof Propylene (co) polymer (A) content in the polypropylene resin composition (C) according to the present invention is as follows: propylene (co) polymer (A) and propylene The content of the propylene (co) polymer (A) is 10 to 95% by weight, preferably 60 to 95% by weight with respect to the total 100% by weight of the ethylene random copolymer (B). Preferably it is 70 to 90 weight%, More preferably, it is 70 to 80 weight%. On the other hand, the content of the propylene / ethylene random copolymer (B) is 5 to 90% by weight, preferably 5 to 40% by weight, more preferably 10 to 30% by weight, and still more preferably 20%. ~ 30% by weight. Here, the total of the proportion of the propylene (co) polymer (A) and the proportion of the propylene / ethylene random copolymer (B) is 100% by weight. When the content ratio is within the above range, desired physical properties such as melt tension are easily obtained, and the effect of improving fish eyes is easily obtained.

  The polypropylene resin composition (C) according to the present invention is a blend of propylene (co) polymer (A) and propylene / ethylene random copolymer (B) produced separately, or propylene (co) heavy. The polymer (A) can be obtained by a production process including polymerization (first process) and subsequent polymerization of a propylene / ethylene random copolymer (B) (second process). In the former, the propylene (co) polymer (A) can be used singly or in combination of two or more, and the propylene / ethylene random copolymer (B) can be used singly or in combination of two or more. In the latter case, the propylene (co) polymer (A) is produced in a polymerization step of one stage or two or more stages (the reaction conditions in each stage are the same or different), and the propylene / ethylene random copolymer (B) is also produced. In addition, since it is produced in a polymerization process of one or more stages (reaction conditions in each stage are the same or different), the entire production process of the polypropylene resin composition (C) is at least a two-stage sequential multi-stage polymerization process. It becomes. The latter may be a production process in which the order of the polymerization of the propylene (co) polymer (A) (first process) and the polymerization of the propylene / ethylene random copolymer (B) (second process) are reversed. .

In addition, although superposition | polymerization may be any of a batch type, a semibatch type, and a continuous type, industrially a continuous type is preferable.
As polymerization methods, slurry polymerization using inert hydrocarbons such as hexane, heptane, octane, benzene, and toluene as a polymerization solvent, bulk polymerization using propylene itself as a polymerization solvent, and polymerization of propylene as a raw material in a gas phase state Gas phase polymerization is possible. Moreover, it is also possible to carry out by combining these polymerization formats.
For example, a method in which pre-stage polymerization is carried out by bulk polymerization and post-stage polymerization is carried out by gas-phase polymerization, a method in which pre-stage polymerization is carried out by gas-phase polymerization, and post-stage polymerization is carried out by gas-phase polymerization, Examples thereof include a method in which polymerization is performed and post-stage polymerization is performed by gas phase polymerization.
In the present invention, since the propylene / ethylene random copolymer (B) has a relatively high ethylene concentration, propylene is hardly liquefied, and it is necessary to increase the pressure to carry out the bulk polymerization. Therefore, slurry polymerization and gas phase polymerization are preferable. More preferably, pre-stage polymerization is performed in a gas phase first reactor, and post-stage polymerization is performed in a gas phase second reactor.

The polymerization reactor is not particularly limited in shape and structure, but in slurry polymerization and bulk polymerization, a reactor with a stirrer generally used, a tube reactor, a fluidized bed reactor generally used in gas phase polymerization, agitation A horizontal reactor having blades and the like can be mentioned.
A fluidized bed reactor and a horizontal reactor having a stirring blade are preferable because the activity in producing the propylene (co) polymer (A) can be easily controlled. In particular, a fluidized bed reactor is more preferable because a wide range of operating conditions can be adopted.
In the present invention, a preferred embodiment is that the first reactor and the second reactor are fluidized bed reactors, or the first reactor and the second reactor are horizontal reactors having stirring blades. .
Moreover, in this invention, a preferable aspect is that a 1st reactor (polymerization tank) and a 2nd reactor (polymerization tank) satisfy | fill the requirements of following (i)-(v).
Requirement (i): The polymerization temperature of the second polymerization tank is 70 ° C. or lower.
Requirement (ii): The average reaction time of the powder held in the first polymerization tank is an average residence time of the powder held in the second polymerization tank + 0.5 hours or less.
Requirement (iii): The average polymerization temperature difference between the second polymerization tank and the first polymerization tank is −10 to 10 ° C.
Requirement (iv): The molar concentration ratio (H ₂ / propylene) of hydrogen and propylene in the second polymerization tank is 0.01 or less.
Requirement (v): The molar ratio (alcohol / organoaluminum compound) of the alcohol supplied to the second polymerization tank to the organoaluminum compound supplied to the first polymerization tank is 0.8 to 2.0.

  In the polymerization (pre-stage polymerization) of the propylene (co) polymer (A), a chain transfer agent such as propylene, and if necessary, a comonomer and hydrogen is supplied to the reactor, and in the presence of a polymerization catalyst, for example, temperature 50-150 ° C., preferably 50-70 ° C., partial pressure of propylene 0.5-4.5 MPa, preferably 1.0-3.0 MPa, average residence time of retained powder present in the reactor 0.5- Propylene is polymerized under a condition of 5.0 Hr to produce a propylene (co) polymer (A). At this time, the MFR of the propylene (co) polymer (A) is controlled by adjusting the concentration of a chain transfer agent such as hydrogen, depending on the type of process and catalyst.

  Subsequently, polymerization (post polymerization) of the propylene / ethylene random copolymer (B) is carried out, and a chain transfer agent such as propylene, ethylene, comonomer, and hydrogen is supplied to the reactor, and the polymerization catalyst is supplied. In the presence of (the catalyst used in the pre-polymerization), for example, the temperature is 50 to 150 ° C., preferably 50 to 90 ° C., and the partial pressures of propylene and ethylene are each 0.3 to 4.5 MPa, preferably 0.5 to Propylene and ethylene random copolymer (B) is produced by random copolymerization of propylene and ethylene under conditions of 3.5 MPa and average residence time of the retained powder existing in the reactor of 1.0 to 7.0 Hr. Thereby, a polypropylene resin composition (C) can be obtained as a final product.

At this time, the intrinsic viscosity [η] copolymer of the propylene / ethylene random copolymer (B) according to the present invention is 6 to 20 dl / g, preferably 8 to 14 dl / g. However, it is preferable to adjust the chain transfer agent such as hydrogen to a relatively low concentration.
When producing the propylene / ethylene random copolymer (B), the chain transfer agent may or may not be present, but the intrinsic viscosity [η] copolymer of the resulting propylene / ethylene random copolymer is subtly set. For the purpose of adjusting, it is preferable to be present in a small amount. When the amount of the chain transfer agent is too large, the intrinsic viscosity [η] copolymer is lowered and desired physical properties cannot be obtained.
When hydrogen is used as the chain transfer agent, the molar ratio of hydrogen and propylene in the second reactor is preferably 0.00001 to 0.05, more preferably 0.0001 to 0.001.

A polypropylene resin composition (C) is produced by a sequential multistage polymerization process of the polymerization of the propylene (co) polymer (A) in the former stage and the polymerization of the propylene / ethylene random copolymer (B) in the latter stage. At this time, in order to increase the proportion of the propylene / ethylene random copolymer (B), it is desired that the activity of the catalyst in the latter polymerization can be maintained high. In the first polymerization, the polymerization temperature and the propylene partial pressure are low, and the polymerization is performed. It is preferred to adopt conditions that suppress the activity of the catalyst for a short time. On the other hand, in post-stage polymerization, it is preferable to employ conditions that increase the activity of the catalyst (polymerization temperature, propylene, ethylene partial pressure is high, and polymerization time is long).
Specifically, the polymerization time (average residence time) of the former stage polymerization is preferably shorter than the polymerization time (average residence time) of the latter stage polymerization + 0.5 hour. Here, the average residence time is the polymerization time in the case of batch polymerization, and in the case of continuous polymerization, the weight of the retained powder in the reactor (kg) and the weight of the polymer powder withdrawn from the reactor per unit time (kg) / Hour) is a value calculated by the following formula: weight of retained powder in the reactor (kg) / weight of polymer powder withdrawn from the reactor per unit time (kg / hour). When the former stage polymerization is performed in multiple stages, the total of the average residence time of each stage is regarded as the average residence time of the powder retained in the first reactor. Similarly, when the latter stage polymerization is performed in multiple stages, the total of the average residence time of each stage is regarded as the average residence time of the powder retained in the second reactor.

  Moreover, it is preferable that the polymerization temperature of pre-stage polymerization is lower than the polymerization temperature of post-stage polymerization. That is, it is preferable that the polymerization temperature of the first reactor is lower than the polymerization temperature of the second reactor. The polymerization temperature in the first reactor is preferably 2 ° C. or lower than the polymerization temperature in the second reactor. When the pre-stage polymerization is performed in multiple stages, the arithmetic average of the polymerization temperature in each stage is regarded as the polymerization temperature of the first reactor. Similarly, when post-stage polymerization is performed in multiple stages, the arithmetic average of the polymerization temperatures of each stage is regarded as the polymerization temperature of the second reactor.

Fish eye can be further reduced by charging the alcohol in the middle of the polymerization in the subsequent polymerization step after the polymerization in the previous polymerization step. The amount of alcohol to be charged is preferably 1.0 to 2.0 mol ratio (alcohol / organoaluminum) with respect to the amount of the organoaluminum compound charged at the time of the previous polymerization. That is, the molar ratio (alcohol / organoaluminum) between the alcohol supplied to the second reactor and the organoaluminum compound supplied to the first reactor is preferably 1.0 to 2.0.
Examples of the alcohol include methyl alcohol, ethyl alcohol, n-propyl alcohol, i-propyl alcohol and the like.

The kind of the polymerization catalyst used for the production of the polypropylene resin composition (C) according to the present invention, for example, the propylene block copolymer, is not particularly limited, and a known catalyst can be used. For example, a so-called Ziegler-Natta catalyst or a metallocene catalyst (for example, see JP-A-5-295022) in which a titanium compound and organoaluminum are combined can be used.
In order to increase the intrinsic viscosity of the propylene / ethylene random copolymer (B), a Ziegler-Natta catalyst that has few chain transfer reactions and easily increases the molecular weight is preferable. The Ziegler-Natta catalyst is a titanium compound obtained by reducing titanium trichloride or a titanium trichloride composition obtained by reduction with an organic aluminum or the like as a titanium compound, and further activating the electron donating compound (for example, JP-A 47- 34478, JP-A-58-23806, JP-A-63-146906), a so-called supported catalyst obtained by supporting titanium tetrachloride on a carrier such as magnesium chloride (for example, JP No. 58-157808, JP-A 58-83006, JP-A 58-5310, JP-A 61-218606, etc.).

  Moreover, an organoaluminum compound is used as a promoter. For example, trialkylaluminum such as trimethylaluminum, triethylaluminum and triisobutylaluminum, alkylaluminum halide such as diethylaluminum chloride and diisobutylaluminum chloride, alkylaluminum hydride such as diethylaluminum hydride, alkylaluminum alkoxide such as diethylaluminum ethoxide, methyl Examples include alumoxanes such as alumoxane and tetrabutylalumoxane, and complex organoaluminum compounds such as dibutyl methylboronate and lithium aluminum tetraethyl. It is also possible to use a mixture of two or more of these.

  Since the organoaluminum compound used as a co-catalyst also acts as a chain transfer agent during polymerization, it is preferably used at a concentration as low as possible so as not to impair the effect of the activity as a co-catalyst. Specifically, the amount of the organoaluminum used is adjusted so that the aluminum atom concentration of the retained powder existing in the reactor is 30 to 80 ppm at the time of the polymerization (after stage) of the propylene / ethylene random copolymer (B). It is preferable to adjust.

  In addition, various polymerization additives for the purpose of improving stereoregularity, controlling particle properties, controlling the amount of solvent-soluble components, controlling molecular weight distribution, and the like can be used for the catalyst. For example, organic silicon compounds such as diphenyldimethoxysilane and tert-butylmethyldimethoxysilane, esters such as ethyl acetate, butyl benzoate, methyl p-toluate, and dibutylphthalate, ketones such as acetone and methyl isobutyl ketone, diethyl ether And electron donating compounds such as ethers such as benzoic acid and propionic acid, and alcohols such as ethanol and butanol.

4). Metal filter (D)
Examples of the filter used for the filtration of fish eye in the granulation process of olefin resin include, for example, metal mesh, laminated wire mesh sintered body, metal nonwoven fabric sintered body, resin woven fabric, resin nonwoven fabric, resin membrane, filter fabric. In the present invention, the filter (D) used is a metal net.

In general, the metal filter used for filtering molten resin is a plain weave, a twill weave shown in Reference FIG. 2, and a flat tatami weave shown in Reference FIG. 3, but the metal used in the present invention. As shown in FIG. 1, the filter (D) is knitted from a vertical wire and a horizontal wire, and the vertical wires are arranged at a predetermined distance, and the horizontal wire is a phase contact with an adjacent horizontal wire. The horizontal wire crosses a certain number of vertical wires, at least two, and then crosses over the vertical wires so that there is space between them. The crossing point with the vertical wire is arranged so that it looks like a ninety-nine fold on the layer, and on the layer, the horizontal wires do not overlap with each other in the vertical direction. ing.
That is, the metal filter (D) used in the present invention satisfies the following requirements (D-1) to (D-4).
Requirement (D-1): Woven from a vertical wire and a horizontal wire, the vertical wires are arranged at a predetermined distance, and the horizontal wire has a structure having a phase contact with an adjacent horizontal wire.
Requirement (D-2): The horizontal wire repeats the structure which cross | intersects so that a space may be vacant after crossing the fixed number of vertical wires which are at least 2 or more.
Requirement (D-3): The crossing point of the horizontal wire with the vertical wire is arranged so as to exhibit a ninety-nine fold aspect on the layer.
Requirement (D-4): It has a structure in which the horizontal wires do not overlap in the vertical direction with respect to the layer on the layer.

The diameter of the vertical wire is preferably selected from the range of 10 nm to 1 m, more preferably 100 nm to 10 cm, and still more preferably 1000 nm (1 μm) to 1 cm.
Moreover, the diameter of a horizontal wire becomes like this. Preferably it is selected from the range of 10 nm-1 m, More preferably, it is 100 nm-10 cm, More preferably, it is 1000 nm (1 micrometer)-1 cm.
As a material used for the wire of the metal filter (D), for example, iron, aluminum, SUS or the like can be used, SUS is preferable, and SUS304 or SUS306 is more preferable.
The size of the filter openings is not particularly limited, and it is desirable to use a finer opening than the fish eye whose size is desired to be removed. The opening space diameter (maximum diameter) of the space formed by the horizontal wire and the vertical wire is preferably selected from the range of 0.1 μm to 1 cm, more preferably 2 to 1000 μm, and still more preferably 40 to 300 μm.
In the present invention, removal of fish eyes means removal by filtration, generation of shearing with a wire, and reduction in size of fish eyes before and after the filter, and the like.

The crossing angle between the vertical wire and the horizontal wire is approximately 90 degrees.
Here, in the definition of the vertical wire and the horizontal wire, the filter may be rotated by 90 °, and the rules for the vertical wire and the horizontal wire may be exchanged.
That is, the metal filter (D) used in the present invention may satisfy the following requirements (D-1 ′) to (D-4 ′).
Requirement (D-1 ′): Woven from a horizontal wire and a vertical wire, the horizontal wires are arranged at a certain distance, and the vertical wire has a structure having a phase contact with an adjacent vertical wire.
Requirement (D-2 ′): The vertical wire has a structure in which it intersects with the horizontal wire so that a space is vacant after crossing a certain number of horizontal wires of at least two.
Requirement (D-3 ′): The crossing points of the vertical wires and the horizontal wires are arranged so as to exhibit a ninety-nine fold aspect on the layer.
Requirement (D-4 ′): On the layer, the vertical wires do not overlap in the vertical direction with respect to the layer.

Moreover, the metal filter (D) used by this invention may use 1 sheet, or may use 2 or more sheets in piles. Further, other filters having a mesh structure may be used in an overlapping manner. For the purpose of reinforcing mechanical strength and removing preliminary fish eyes, etc., a structure in which at least one or more different filters with wider openings are laminated in at least one front and rear direction with respect to the resin flow direction. be able to.
As an example of a preferable combination when the metal filters are used in an overlapping manner, from the upstream side in the resin flow direction, a # 40 to # 60 mesh plain weave metal filter / # 100 to # 120 mesh plain weave metal filter / present invention Metal filter (D) / # 100-120 mesh plain weave metal filter / # 40- # 60 mesh plain weave metal filter. In this configuration, mechanical strength is improved and preliminary fisheye removal is suitably performed, and the screen filter can be used stably for a long period of time.
Here, # 40 to 60 mesh indicates that 40 to 60 openings are provided in one inch, and the larger the numerical value, the finer fish eye can be removed.

5. Other Components The polypropylene resin composition (C) according to the present invention may contain various additives as long as the effects of the present invention are not impaired.
Examples of additives include antioxidants, dyes, organic pigments, inorganic pigments, inorganic reinforcing agents, plasticizers, processing aids such as acrylic processing aids, ultraviolet absorbers, light stabilizers, foaming agents, lubricants, and waxes. , Crystal nucleating agent, plasticizer, mold release agent, hydrolysis inhibitor, antiblocking agent, antistatic agent, radical scavenger, antifogging agent, antifungal agent, rustproofing agent, ion trapping agent, flame retardant, flame retardant An auxiliary agent, an inorganic filler, an organic filler, etc. can be mentioned.

6). Propylene-based resin granule and method for producing the same The method for producing the propylene-based resin granule according to the present invention includes at least two of the propylene (co) polymer (A) and the propylene / ethylene random copolymer (B). Examples thereof include a method for producing a polypropylene-based resin composition (C) containing seeds by, for example, an underwater cut granulation method disclosed in Japanese Patent Application Laid-Open No. 2007-326898.

  The propylene-based resin granule according to the present invention is usually obtained by melt-mixing a propylene (co) polymer (A) and a propylene / ethylene random copolymer (B) to obtain a uniform resin composition (C), For example, although it is manufactured by an underwater cut granulation method, when mixing the propylene (co) polymer (A) and the propylene / ethylene random copolymer (B), other components may be blended as necessary. it can. For example, an antioxidant, a neutralizing agent, an antistatic agent, a weathering agent and the like, which are the other components, can be blended.

  Mixing of each component is carried out at a set temperature of 180 to 250 ° C. using a normal kneader such as a single screw extruder, twin screw extruder, Banbury mixer, roll, Brabender plastograph, kneader, It can be manufactured by granulating with an underwater cut granulator. Among these kneaders, it is preferable to produce using an extruder, particularly a twin screw extruder.

  An example of the underwater cut granulation method will be described. Polymer particles including a propylene (co) polymer (A) and a propylene / ethylene random copolymer (B) are supplied from a hopper to a kneading extruder. Via a die plate provided at the tip of the kneading extruder, it is extruded in the form of a strand into an underwater cutting device provided in the cooling chamber, and pelletized by an underwater cutter that rotates on the surface of the die plate by a drive motor. Disconnected. The metal filter (D) used in the present invention is preferably installed in the kneading extruder tip and the die plate connection, the inside of the die plate, or the like. The cut pellets are sent to a dewatering / drying device and a vibrating sieve together with cooling water (PCW) circulated and supplied to the underwater cutting device by a cooling water pump, and stored in the product silo as dry pellets.

EXAMPLES Hereinafter, although this invention is demonstrated further more concretely based on an Example, this invention is not limited to these Examples.
Analysis and evaluation methods performed in Examples and Comparative Examples are as follows.

1. Melt flow rate (MFR) (Unit: g / 10 min)
The measurement was performed according to JIS K7210, temperature 230 ° C., load 21.18 N (2.16 kg).

2. Method for Analyzing Physical Properties of Polypropylene Resin Composition Measurement of ratio (Wc), ethylene content, and intrinsic viscosity of propylene / ethylene random copolymer portion (hereinafter sometimes referred to as rubber component) of polypropylene resin composition Using the following apparatus and conditions, the measurement is performed according to the following procedure.
(1) Analytical device to be used (i) Cross fractionation device CFC T-100 (abbreviated as CFC) manufactured by Dia Instruments Co., Ltd.
(Ii) Fourier transform infrared absorption spectrum analysis FT-IR, Perkin Elmer 1760X
The fixed wavelength infrared spectrophotometer attached as the CFC detector is removed, and an FT-IR is connected instead, and this FT-IR is used as the detector. The transfer line from the outlet of the solution eluted from the CFC to the FT-IR is 1 m long, and the temperature is maintained at 140 ° C. throughout the measurement. The flow cell attached to the FT-IR has an optical path length of 1 mm and an optical path width of 5 mmφ, and the temperature is maintained at 140 ° C. throughout the measurement.
(Iii) Gel permeation chromatography (GPC)
The GPC column in the latter part of the CFC is used by connecting three AD806MS manufactured by Showa Denko KK in series.

(2) CFC measurement conditions (i) Solvent: orthodichlorobenzene (ODCB)
(Ii) Sample concentration: 4 mg / mL
(Iii) Injection volume: 0.4 mL
(Iv) Crystallization: The temperature is lowered from 140 ° C. to 40 ° C. over about 40 minutes.
(V) Fractionation method: Fractionation temperatures at the time of temperature-raising elution fractionation are 40, 100, and 140 ° C., and fractionation is performed in three fractions in total. In addition, the elution ratio (unit:% by weight) of the component eluting at 40 ° C. or lower (fraction 1), the component eluting at 40 to 100 ° C. (fraction 2), and the component eluting at 100 to 140 ° C. (fraction 3), respectively It is defined as W40, W100, and W140. W40 + W100 + W140 = 100. Moreover, each fractionated fraction is automatically transported to the FT-IR analyzer as it is.
(Vi) Solvent flow rate during elution: 1 mL / min

(3) Measurement conditions of FT-IR After elution of the sample solution from GPC at the latter stage of CFC was started, FT-IR measurement was performed under the following conditions, and GPC-IR data was collected for each of the above-described fractions 1 to 3. To do.
(I) Detector: MCT
(Ii) Resolution: 8 cm-1
(Iii) Measurement interval: 0.2 minutes (12 seconds)
(Iv) Number of integrations per measurement: 15 times

(4) Post-processing and analysis of measurement results The elution amount and molecular weight distribution of components eluted at each temperature are determined using the absorbance at 2945 cm-1 obtained by FT-IR as a chromatogram. The elution amount is normalized so that the total elution amount of each elution component is 100%. Conversion from the retention volume to the molecular weight is performed using a calibration curve prepared in advance with standard polystyrene.
Standard polystyrenes used are the following brands manufactured by Tosoh Corporation.
F380, F288, F128, F80, F40, F20, F10, F4, F1, A5000, A2500, A1000.
A calibration curve is created by injecting 0.4 mL of a solution dissolved in ODCB (containing 0.5 mg / mL BHT) so that each is 0.5 mg / mL. The calibration curve uses a cubic equation obtained by approximation by the least square method. Conversion to molecular weight uses a general-purpose calibration curve with reference to “Size Exclusion Chromatography” written by Sadao Mori (Kyoritsu Shuppan). The following numerical values are used for the viscosity equation ([η] = K × M ^α ) used at that time.
(I) Calibration curve using standard polystyrene K = 0.000138, α = 0.70
(Ii) Sample measurement of propylene-based block copolymer K = 0.000103, α = 0.78
The ethylene content distribution (distribution of ethylene content along the molecular weight axis) of each eluted component is a ratio of the absorbance of 2956 cm ⁻¹ and the absorbance of 2927 cm ⁻¹ obtained by FT-IR, and is obtained by using polyethylene, polypropylene, or ¹³ Using ethylene-propylene rubber (EPR) and mixtures thereof whose ethylene content is known by C-NMR measurement, etc., converted to ethylene content (% by weight) using a calibration curve prepared in advance. And ask.

(5) Propylene / ethylene random copolymer portion ratio (Wc)
The ratio (Wc) of the propylene / ethylene random copolymer portion in the propylene-based block copolymer in the present invention is theoretically defined by the following formula (I), and is determined by the following procedure.
Wc (weight%) = W40 × A40 / B40 + W100 × A100 / B100 (I)
In formula (I), W40 and W100 are the elution ratios (unit: weight%) in each of the above-mentioned fractions, and A40 and A100 are the average ethylene content of actual measurement in each fraction corresponding to W40 and W100. B40 and B100 are the ethylene content (unit: wt%) of the propylene / ethylene random copolymer portion contained in each fraction. A method for obtaining A40, A100, B40, and B100 will be described later.
The meaning of the formula (I) is as follows.
That is, the first term on the right side of the formula (I) is a term for calculating the amount of the propylene / ethylene random copolymer portion contained in the fraction 1 (portion soluble at 40 ° C.). When fraction 1 contains only a propylene / ethylene random copolymer and no crystalline propylene polymer portion, W40 accounts for the content of propylene / ethylene random copolymer portion derived from fraction 1 as it is in the whole. Fraction 1 includes a component derived from a small amount of a crystalline propylene polymer portion (a component having an extremely low molecular weight and atactic polypropylene) in addition to a component derived from a propylene / ethylene random copolymer. It is necessary to correct the part. Therefore, by multiplying W40 by A40 / B40, the amount derived from the propylene / ethylene random copolymer component in fraction 1 is calculated. For example, when the average ethylene content (A40) of fraction 1 is 30% by weight and the ethylene content (B40) of the propylene / ethylene random copolymer contained in fraction 1 is 40% by weight, / 40 = 3/4 (ie, 75% by weight) is derived from a propylene / ethylene random copolymer, and 1/4 is derived from a crystalline propylene polymer portion. Thus, the operation of multiplying A40 / B40 in the first term on the right side means that the contribution of the propylene / ethylene random copolymer is calculated from the weight% (W40) of fraction 1. The same applies to the second term on the right side, and for each fraction, the content of the propylene / ethylene random copolymer portion is calculated by adding the contribution of the propylene / ethylene random copolymer and adding it.

(I) As described above, the average ethylene contents corresponding to fractions 1 and 2 obtained by CFC measurement are A40 and A100, respectively (the unit is% by weight). A method for obtaining the average ethylene content will be described later.
(Ii) The ethylene content corresponding to the peak position in the differential molecular weight distribution curve of fraction 1 is defined as B40 (unit is% by weight). Fraction 2 is considered to be substantially defined as B100 = 100 in the present invention because it is considered that the rubber part is completely eluted at 40 ° C. and cannot be defined with the same definition. B40 and B100 are the ethylene content of the propylene / ethylene random copolymer portion contained in each fraction, but it is practically impossible to determine this value analytically. This is because there is no means for completely separating and fractionating the propylene homopolymer and the propylene / ethylene random copolymer mixed in the fraction. As a result of examination using various model samples, it was found that B40 can explain the effect of improving the material properties well by using the ethylene content corresponding to the peak position of the differential molecular weight distribution curve of fraction 1. It was. Further, B100 has crystallinity derived from ethylene chain, and the amount of propylene / ethylene random copolymer contained in these fractions is relative to the amount of propylene / ethylene random copolymer contained in fraction 1. For the reason of two points, the approximation to 100 is closer to the actual situation and hardly causes an error in calculation. Therefore, analysis is performed with B100 = 100.

3. Fisheye (FE) Evaluation Method The propylene-based resin granule was put into a single-screw extruder, and formed into a sheet shape from a T die having a width of 750 mm and a Lip width of 0.4 mm through a feed block.
The extruded sheet is a 50 mm diameter roll installed immediately after the die exit. First, one side is cooled, then both sides are cooled by four 100 mm diameter rolls, and the sheet is taken up at a constant speed by a nip roll. Processed into a shape.
The number of fish eyes (FE) contained in 1 g of the sheet thus obtained was visually counted and evaluated. The evaluation criteria are as follows.
-FE large: The diameter of a fish eye is 1.0 mm or more.
-During FE: The diameter of the fish eye is 0.5 mm or more and less than 1.0 mm.
-FE small: The diameter of the fish eye is less than 0.5 mm.

The typical sheet forming conditions are shown below.
・ Aperture 65mm, L / D = 45
・ Screw rotation speed: 75rpm
Set temperature: C1-180, C2-4-240, C5-190, C6-9-175 ° C
・ Discharge rate: Approximately 65kg / h
-Feed block temperature: 175 ° C
-Die temperature: 175 ° C
・ Cooling roll temperature: 15 ℃
-Winding speed: 4.5 m / min

[Example 1]
(Production Example 1 of Propylene Resin Granules)
1. Production of catalyst A 10-liter autoclave equipped with a stirrer was sufficiently replaced with nitrogen, and 2 liters of purified toluene was introduced. To this, 200 g of diethoxymagnesium Mg (OEt) ₂ and 1 liter of titanium tetrachloride were added at room temperature. The temperature was raised to 90 ° C. and 50 ml of n-butyl phthalate was introduced. Thereafter, the temperature was raised to 110 ° C. and the reaction was carried out for 3 hours. The reaction product was thoroughly washed with purified toluene.
Subsequently, the refined toluene was introduce | transduced and the whole liquid quantity was adjusted to 2L. 1 liter of titanium tetrachloride was added at room temperature, the temperature was raised to 110 ° C., and the reaction was carried out for 2 hours. The reaction product was thoroughly washed with purified toluene. Further, using purified n-heptane, toluene was replaced with n-heptane to obtain a slurry of a solid catalyst component (catalyst 1-1).
A portion of this slurry was sampled and dried. As a result of analysis, the titanium content of the solid catalyst component was 2.7% by weight, and the magnesium content was 18% by weight. The average particle size of the solid catalyst component was 33 μm.

Next, a 20 liter autoclave equipped with a stirrer was sufficiently replaced with nitrogen, and 100 g of the slurry of the solid catalyst component (catalyst 1-1) was introduced as the solid catalyst component (catalyst 1-1). Purified n-heptane was introduced to adjust the concentration of the solid catalyst component (catalyst 1-1) to 25 g / liter. 50 mL of silicon tetrachloride SiCl ₄ was added and reacted at 90 ° C. for 1 hour. The reaction product was thoroughly washed with purified n-heptane.
Thereafter, purified n-heptane was introduced to adjust the liquid level to 4 liters. Here, 30 ml of dimethyldivinylsilane, 30 ml of t-butylmethyldimethoxysilane (t-C ₄ H ₉ ) (CH ₃ ) Si (OCH ₃ ) _2, and n-heptane diluted solution of triethylaluminum Et ₃ Al are Et _3. 80 g of Al was added and reacted at 40 ° C. for 2 hours. The reaction product was thoroughly washed with purified n-heptane, and a portion of the resulting slurry was sampled and dried. Analysis, in the solid component, titanium _1.2% by weight and contained ₂ 8.8 _{wt% (t-C 4 H 9} ) (CH 3) Si (OCH 3).

Prepolymerization was performed by the following procedure using the solid component obtained above.
Purified n-heptane was introduced into the slurry, and the solid component concentration was adjusted to 20 g / liter. After cooling the slurry to 10 ° C., and 10g added n- heptane dilution of triethylaluminum _Et 3 Al as _Et 3 Al, were added over 4 hours propylene 280 g. After the supply of propylene was completed, the reaction was continued for another 30 minutes.
Next, the gas phase was sufficiently replaced with nitrogen, and the reaction product was thoroughly washed with purified n-heptane. The obtained slurry was extracted from the autoclave and vacuum dried to obtain a solid catalyst component (catalyst 1). This solid catalyst component (Catalyst 1) contained 2.5 g of polypropylene per 1 g of the solid component. Analysis, in the polypropylene obtained by removing part of the solid catalyst component (catalyst 1), titanium _1.0% by weight, _{2 (t-C 4 H 9)} (CH 3) Si (OCH 3) 8.2 It was included by weight.

2. Production of Propylene / Ethylene Block Copolymerization Polymerization was carried out using a continuous reaction apparatus formed by connecting two fluidized bed reactors having an internal volume of 2000 liters.
First, in a first reactor, a polymerization temperature of 65 ° C., a propylene partial pressure of 1.8 MPa (absolute pressure), and hydrogen as a molecular weight control agent are continuously added so that the molar ratio of hydrogen / propylene is 0.015. While feeding, triethylaluminum was fed at 4.0 g / hr, and the catalyst 1 was fed at a polymer polymerization rate of 16 kg / hr. The powder polymerized in the first reactor (crystalline propylene polymer) is continuously withdrawn at a rate of 16 kg / hr so that the amount of powder held in the reactor is 40 kg, and continuously into the second reactor. Transferred (first stage polymerization step).

Next, in the second reactor, propylene and ethylene are continuously fed so that the molar ratio of ethylene / propylene is 0.44 at a polymerization temperature of 70 ° C. and a monomer pressure of 1.5 MPa, In addition, hydrogen as a molecular weight control agent is continuously supplied so that the molar ratio of hydrogen / propylene is 0.0008, and ethyl alcohol is 1.17 with respect to triethylaluminum supplied to the first reactor. It supplied so that it might become a double mole.
The powder polymerized in the second reactor is continuously withdrawn into the vessel so that the amount of powder held in the reactor is 60 kg, and the reaction is stopped by supplying moisture-containing nitrogen gas. A polymer was obtained (second stage polymerization step).
Propylene (co) polymer (A), which is a crystalline propylene polymer obtained in the first stage polymerization step, and propylene / ethylene random copolymer (B) and propylene obtained in the second stage polymerization step Table 1 shows the composition and properties of the polypropylene resin composition (C), which is an ethylene block copolymer.

  With respect to 100 parts by weight of the resulting propylene / ethylene block copolymer powder, 0.2 parts by weight of “IRGASTAB FS 301 FF” (manufactured by BASF), 1,3,5-tris (2, 6-dimethyl-3-hydroxy-4-tertiarybutylbenzoyl) isocyanate (Songwon, trade name: SONGNOX1790) 0.1 parts by weight, 3,9-bis (2,6-di-tert-butyl-4-) Methylphenoxy) -2,4,8,10-tetraoxa-3,9-diphosphaspiro [5.5] undecane (manufactured by ADEKA, trade name: PEP-36) 0.05 parts by weight, calcium stearate 0 as neutralizer 0.03 part by weight was added and mixed for 5 minutes with a super mixer (manufactured by Kawada Seisakusho).

Using the obtained blend, a propylene-based resin granule-1 was obtained by an underwater cut granulation method under the following apparatus and conditions.
・ Twin screw extruder (Technobel KZW25TW-45MG-NH)
・ Aperture 30mm, L / D = 25 (PMS30-25 manufactured by IK Corporation)
・ Screw: Full flight CR2.0, Feed part groove depth 4mm + Dalmage ・ Screw speed: 60rpm
・ Set temperature: hopper sewage cooling, C1-C4 each 220, 200, 200, 200 ° C.
・ Die: Strand die ・ Granulation rate: 200 kg / hr
・ Cooling water temperature: 43 ℃
Screen mesh: BMT140ZZ (obtained from Ishikawa Wire Mesh Co., Ltd., special twill woven)
BMT140ZZ is a metal filter that satisfies the requirements (D-1) to (D-4) of the present invention.

[Example 2]
(Production Example 2 of Propylene Resin Granule)
Using the catalyst 1 prepared above, the hydrogen / propylene molar ratio in the first stage polymerization was changed to 0.021 according to the production procedure of the propylene / ethylene block copolymer of Production Example 1 above, Propylene / ethylene block copolymer was produced by setting the hydrogen / propylene molar ratio in the two-stage polymerization to 0.00025 and the amount of ethyl alcohol charged to 1.19 times the amount of triethylaluminum fed to the first reactor. Then, by performing the same granulation as in Production Example 1, a propylene-based resin granulation body-2 was obtained.

[Comparative Example 1]
(Production Example 3 of Propylene Resin Granule)
Using the catalyst 1 prepared above, a propylene / ethylene block copolymer was produced according to the procedure for producing the propylene / ethylene block copolymer of Production Example 1, and the propylene-based resin granule according to Production Example 1 was produced. From the production method, the screen mesh to be used was changed to a 100 mesh plain weave (obtained from Ishikawa Wire Mesh Co., Ltd.) to obtain propylene-based resin granule-3.
The plain weave screen mesh is a metal filter that does not satisfy all the requirements (D-1) to (D-4) of the present invention.

[Comparative Example 2]
(Production Example 4 of Propylene Resin Granule)
Propylene / ethylene block copolymer is produced in accordance with the production procedure of the propylene / ethylene block copolymer of Production Example 3 using the catalyst 1 prepared above, and the same granulation as in Production Example 3 is performed. Thus, a propylene-based resin granule-4 was obtained.

[Evaluation of Examples 1 and 2]
The propylene-based resin granules obtained in Production Examples 1 and 2 were put into a single screw extruder, and formed into a sheet shape from a T die having a width of 750 mm and a Lip width of 0.4 mm through a feed block.
The extruded sheet is a roll with a diameter of 50 mm installed immediately after the die exit, and one side is first cooled, then both sides are cooled with four rolls with a diameter of 100 mm, and taken up at a constant speed by a nip roll, Processed into a sheet.
Each sheet was evaluated by visually counting the number of fish eyes (FE) contained in 1 g. Table 1 shows the number of FEs.

[Evaluation of Comparative Examples 1 and 2]
The propylene-based resin granules obtained in Production Examples 3 and 4 were processed into sheets in the same manner as in Examples 1 and 2.
Further, as in Examples 1 and 2, for each sheet, the number of fish eyes (FE) contained in 1 g was visually counted and evaluated. Table 1 shows the number of FEs.

From the comparison of each of the above examples and comparative examples, the following matters were found.
In Examples 1 and 2, the propylene / ethylene random copolymer (B) has an extremely large intrinsic viscosity [η] copolymer, and has a high proportion of propylene / ethylene random copolymer having a high intrinsic viscosity [η] copolymer. A polypropylene resin composition (C) made of a propylene / ethylene block copolymer is knitted from a vertical wire and a horizontal wire, and the vertical wires are arranged at regular intervals, and the horizontal wires are adjacent to each other. It has a structure with a phase contact with the wire, and the horizontal wire repeats the structure that crosses the vertical wire and the space so as to be vacant after crossing a certain number of vertical wires that are at least 2 or more, The crossing point of the horizontal wire with the vertical wire is arranged so that it looks like a ninety-nine fold on the layer. This is an example in which a propylene-based resin granule is obtained by using a screen mesh (BMT140ZZ) having a structure in which a worker does not overlap vertically with a layer.
It can be seen that the number of fish eyes is small as compared with Comparative Examples 1 and 2 produced using a plain weave # 100 screen mesh.

  The method for producing a granulated body of the polypropylene resin composition according to the present invention involves granulating a polypropylene resin composition having a high intrinsic viscosity and a high content ratio of the propylene / ethylene random copolymer (B) that is likely to generate fisheye. When molding a body, fish eyes can be suppressed or eliminated, and the industrial applicability is high.

Claims (5)

Propylene (co) polymer (A) that satisfies the following requirements (A-1) and (A-2), and a propylene / ethylene random copolymer that satisfies the following requirements (B-1) and (B-2) A polypropylene resin composition (C) containing at least two types with (B) is granulated using a metal filter (D) that satisfies the following requirements (D-1) to (D-4): The manufacturing method of the granulated body of the polypropylene resin composition characterized by doing.
Requirement (A-1): Melt flow rate (MFR: 230 ° C., 2.16 kg load) is 0.5 to 100 g / 10 min.
Requirement (A-2): The content of the propylene (co) polymer (A) is 100% by weight in total of the propylene (co) polymer (A) and the propylene / ethylene random copolymer (B). 10 to 95% by weight.
Requirement (B-1): Intrinsic viscosity [η] copy is 6 to 20 dl / g.
Requirement (B-2): Content of propylene / ethylene random copolymer (B) with respect to 100% by weight in total of propylene (co) polymer (A) and propylene / ethylene random copolymer (B) Is 5 to 90% by weight.
Requirement (D-1): Woven from a vertical wire and a horizontal wire, the vertical wires are arranged at a predetermined distance, and the horizontal wire has a structure having a phase contact with an adjacent horizontal wire.
Requirement (D-2): The horizontal wire repeats the structure which cross | intersects so that a space may be vacant after crossing the fixed number of vertical wires which are at least 2 or more.
Requirement (D-3): The crossing point of the horizontal wire with the vertical wire is arranged so as to exhibit a ninety-nine fold aspect on the layer.
Requirement (D-4): It has a structure in which the horizontal wires do not overlap in the vertical direction with respect to the layer on the layer.   The polypropylene resin composition according to claim 1, wherein the polypropylene resin composition (C) is produced by continuously polymerizing using at least two or more connected polymerization tanks. A method for producing a granulated product of the composition.   The granulated body of the polypropylene resin composition according to claim 2, wherein the at least two or more connected polymerization tanks are a first polymerization tank and a second polymerization tank which are fluidized bed reactors. Production method.   The polypropylene-based resin composition according to claim 2, wherein the at least two or more connected polymerization tanks are horizontal reactors in which the first polymerization tank and the second polymerization tank have stirring blades. A method for producing granules. The polypropylene resin composition according to claim 2, wherein the at least two or more connected polymerization tanks satisfy the following requirements (i) to (v): the first polymerization tank and the second polymerization tank. A method for producing a granulated product.
Requirement (i): The polymerization temperature of the second polymerization tank is 70 ° C. or lower.
Requirement (ii): The average reaction time of the powder held in the first polymerization tank is an average residence time of the powder held in the second polymerization tank + 0.5 hours or less.
Requirement (iii): The average polymerization temperature difference between the second polymerization tank and the first polymerization tank is −10 to 10 ° C.
Requirement (iv): The molar concentration ratio (H ₂ / propylene) of hydrogen and propylene in the second polymerization tank is 0.01 or less.
Requirement (v): The molar ratio (alcohol / organoaluminum compound) of the alcohol supplied to the second polymerization tank to the organoaluminum compound supplied to the first polymerization tank is 0.8 to 2.0.