JP2016222782A - Storage method of granulated products of soft resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a storage method of granular products, capable of suppressing blocking of granulated products of a soft resin and storing the granulated products.SOLUTION: A storage method of granulated products of a soft resin uses a storage system comprising: a storage device 10 for receiving granulated products of a soft resin which are transported by pneumatic transport from an upstream step and storing the granulated products; a pipe 12 for returning again the granulated products of the soft resin which are extracted from the storage device 10 to the storage device 10; and a pneumatic transport device 14 for circulating the granulated products of the soft resin in a circulation path formed of the storage device 10 and the pipe 12. The storage method is configured to: receive the granulated products of the soft resin which are transported from the upstream side by pneumatic transport in the storage device 10; circulate the granulated products of the soft resin by the pneumatic transport device 14 through the circulation path; thereby promote crystallization of the soft resin; and then store the granulated products of the soft resin whose crystallization proceeds.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for storing a granulated product of a soft resin.

Soft resins are widely used as raw materials for films and the like as substitutes for soft vinyl chloride resins with a large environmental load. Due to the nature of this soft resin, the surface of the granulated product may be sticky. Therefore, among the soft resins, particularly when the soft polyolefin resin is granulated to a size that is easy to handle as a product, there is a problem that the granulated materials stick to each other and easily form a block (blocking).
In order to solve this problem, after the polymerized and devolatilized, the molten soft resin is cooled to a certain temperature, and then granulated by an underwater granulation method, thereby reducing the adhesion between the granulated products. Furthermore, a method has been proposed in which the granulated product is transferred to a dehydration step together with a circulating water stream (cooling water), and cooling is performed during this period to improve efficiency (see, for example, Patent Document 1).

International Publication No. 2006/117963

  However, the soft resin is not reduced in surface tackiness until crystallization is sufficiently advanced, and if it is transported as it is to a storage device for storing it, it will adhere to each other in a state where the granulated material is deposited. There is a problem that it may cause a blockage in the storage device.

Therefore, the present inventors do not send the granulated product, which has not sufficiently progressed crystallization, to the storage device as it is, but once sends it to a water tank called a crystallization tank, where the granulated product is cooled. The inventors also found a method for promoting crystallization of a granulated product by stirring with water for a predetermined time (see Patent Document 1).
However, in order to process a large amount of granulated material, a huge water tank is required, and in order to sufficiently promote crystallization, it takes a long time from 5 minutes to 24 hours in some cases. Thus, regarding the crystallization of the granulated product, there is still room for improvement in the method for producing the granulated product from the viewpoint of the equipment cost of the crystallization process and the production efficiency of the crystallized granulated product.

  This invention is made | formed in view of the said situation, and it aims at providing the storage method of the granulated material which can store this, suppressing blocking of the granulated product of a soft resin.

As a result of intensive research, the inventors of the present invention have stored the granulated product of the soft resin while circulating it by air transportation, promoting crystallization during that time, and softening the crystallization is not sufficiently advanced. “Blocking” due to “stickiness” of the resin granulated product can be suppressed, and even if the granulated product is not sufficiently crystallized, it is accepted in the storage device and crystallized. It has been found that both processing and storage can be performed, and the present invention has been completed.
That is, the present invention provides the following inventions.
[1] A storage device for receiving and storing a granulated product of soft resin that is air-fed from an upstream process, and for returning the granulated product of soft resin extracted from the storage device to the storage device again. From the upstream process, using a storage system comprising: a piping system; an air feeding device for circulating the granulated product of the soft resin in a circulation path formed by the storage device and the piping; Crystallization of the soft resin by circulating the soft resin granule through the circulation path by the air feeding device while receiving the granulated product of the soft resin to be air sent to the storage device The method for storing a granulated product of a soft resin, in which the granulated product of the resin that has been accelerated and crystallized is stored.
[2] In order to receive and store the granulated product of the soft resin that is air-fed from the upstream process, the storage device further includes the storage system including another storage device. While the granulated product of the soft resin is circulated, the crystallization of the soft resin is promoted, and the granulated product of the resin that has been crystallized is stored, while the other storage device newly starts from the upstream process. The method for storing a granulated product of a soft resin according to [1], wherein the granulated product of a soft resin that is air-fed is received.
[3] When the granulated product of the soft resin is air-fed in the circulation path, the ratio of the soft resin pellet and the air volume in the pipe is 0.02 ton / Nm ³ or less. [1] Or the storage method of the granulated material of the soft resin as described in [2].
[4] The method for storing a granulated product of a soft resin according to any one of [1] to [3], wherein the soft resin is a propylene-based polymer satisfying at least one of (1) and (2). .
(1) [mmmm] is 20 to 60 mol%.
(2) Using a differential scanning calorimeter (DSC), hold the sample at −10 ° C. for 5 minutes in a nitrogen atmosphere, and then raise the temperature at 10 ° C./min. The melting point (Tm-D) defined as the observed peak top is 0-120 ° C.
[5] The tensile elastic modulus of the soft resin is 1 to 200 MPa in accordance with JIS K 7113, the resin pellet having adhesiveness is in accordance with JIS K7210, a temperature of 230 ° C. and a load of 21.18 N. The method for storing a granulated product of a soft resin according to any one of [1] to [4], wherein the melt flow rate (MFR) is 1 to 10,000 g / 10 min.
[6] The method for storing a granulated product of a soft resin according to any one of [1] to [5], wherein a time for circulating the granulated product of the soft resin in the circulation path is 4 hours or more.
[7] The method for storing a granulated product of a soft resin according to any one of [1] to [6], wherein a temperature in a storage device for storing the granulated product of the soft resin is 35 ° C. or lower.
[8] The granulated product of the soft resin according to any one of [1] to [7], wherein the temperature in the pipe where the granulated product of the soft resin is air-fed is 10 ° C. or more and 30 ° C. or less Storage method.

  According to the present invention, the granulated product of soft resin is stored while being circulated, so that crystallization is promoted during that time, and “greasiness” of the granulated product of soft resin that is not sufficiently crystallized. The resulting “blocking” can be suppressed.

It is the structure schematic which shows an example of the storage system of the granulated material of the soft resin of this invention. It is the structure schematic which shows the other example of the storage system of the granulated material of the soft resin of this invention. It is a flowchart which shows an example of the manufacturing process of the granulated product of resin of this invention.

  Before describing the method for storing the granulated product of the soft resin of the present invention, a method for producing a resin obtained by crystallization through a soft resin will be described.

A method for producing a resin crystallized through a soft resin is shown in FIG. Here, a soft polyolefin resin will be described as an example of the soft resin. The soft resin will be described in detail later.
A method for producing a granulated product of a resin made of a soft polyolefin resin is as shown in FIG. First, an olefin monomer as a raw material is polymerized by a solution polymerization method, a gas phase polymerization method, or the like to become a soft polyolefin resin (S100). In order to remove a solvent, an unreacted monomer component, etc. from this resin, it heats and volatilizes (S102). Since the temperature of the devolatilization step is usually about 100 ° C. to 250 ° C., the resin is in a molten state. Next, the molten resin is directly transferred to the cooling step (S104). This eliminates the need for a resin reheating step, thereby improving production efficiency.

In the cooling step, the melted soft polyolefin-based resin is granulated after cooling to a temperature range of the melting point (Tm-D) ± 50 ° C. of the resin, preferably to a temperature range of the melting point (Tm-D) ± 20 ° C. To do. Thereby, the adhesiveness of resin at the time of granulation can be reduced. Therefore, it can suppress that a pellet adheres and forms a lump at the time of granulation.
In addition, in this specification, melting | fusing point (Tm-D) of resin is calculated | required as mentioned later.

  As a device for cooling the resin, a polymer cooler, a jacketed kneader, a jacketed polymer mixer, or the like can be used. A polymer cooler is preferred because it is relatively inexpensive and can reduce equipment costs.

After cooling the resin, underwater granulation is performed (S106). As an example of underwater granulation, the resin cooled by a cooler passes through a die having one or more holes of a predetermined shape attached to the tip of the cooler, and then is cut into a pellet shape by a cutting chamber. .
The cut pellets are conveyed from the chamber to the dehydrator by a water flow. Then, the granulated product of the soft resin and the cooling water are separated by the dehydrator, and the granulated product of the soft resin is recovered.

Next, the granulated product of the soft resin obtained in the underwater granulation step (S106) is subjected to a crystallization step (S108), and the granulated product of the resin after crystallization is packed as a final product (S110). ).
In the present invention, the crystallization step (S108) is divided into two steps: a first crystallization step (S202) and a second crystallization and storage step (S204) using a storage system described later. Thereby, compared with the granulation time only by the granulation method which completes crystallization in water, granulation time can be shortened. Moreover, compared with the granulation method which completes crystallization in water, since the crystallization is promoted by air transportation using an existing storage device, the equipment cost can be reduced. As a result, the crystallization step (S108) The total time can be shortened.

In the first crystallization step of the present invention, crystallization proceeds from a granulated product of an amorphous resin to a granulated product of a soft resin while stirring in water (S202).
In the first crystallization step, the temperature in water is preferably about 30 ° C. Note that crystallization will not proceed if the temperature is too low. Thereby, crystallization of the granulated product of the amorphous resin is promoted.
In the first crystallization step, it is preferable to shorten the time within a range where the pellets do not conflict from the viewpoint of shortening the total time of the crystallization step and reducing the equipment cost.
An anti-fusing agent may be added to the water for stirring. Silicone or the like can be used as the anti-fusing agent.
The addition amount of the anti-fusing agent is appropriately adjusted depending on the type of anti-fusing agent used. For example, when silicone is used, the cooling water is 100 mass ppm to 5000 mass ppm, preferably 500 mass ppm. Add ~ 1000 mass ppm.

[Storage method of granulated soft resin]
<First Embodiment>
The present invention relates to the second crystallization and storage step in FIG. 3, and relates to a method for storing a granulated product of soft resin obtained in the first crystallization step.
As shown in FIG. 1, the first embodiment of the method for storing a granulated product of soft resin according to the present invention is a storage device 10 for receiving and storing a granulated product of soft resin that is air-fed from an upstream process. In the circulation path formed by the pipe 12 for returning the granulated product of the soft resin extracted from the storage apparatus 10 to the storage apparatus 10 again and the storage apparatus 10 and the pipe 12, the soft resin Using the storage system 100 including the air feeding device 14 for circulating the granulated material, the granulated product of the soft resin that is air-fed from the upstream process is received in the storage device 10 while the air feeding device 14 is received. By circulating the granulated product of the soft resin through the circulation path, the crystallization of the soft resin is promoted, and the granulated product of the soft resin that stores the granulated product of the crystallized resin is stored. Storage method.

  According to the method for storing a granulated product of the soft resin of the present invention, even a granulated product that has not been sufficiently crystallized is received by the storage device and subjected to both crystallization and storage processes. It can be carried out. Therefore, it is possible to reduce the time for granulation by the underwater granulation method, to reduce the equipment cost for producing a granulated product of soft resin, and to shorten the total time as a crystallization process. Manufacturing efficiency can be improved.

Furthermore, the storage system 100 used for the storage method of the granulated product of the soft resin of this invention is demonstrated in detail using FIG.
The storage system 100 shown in FIG. 1 is provided with a pipe 22 for transporting the granulated product of the soft resin obtained in the first crystallization process to the storage apparatus 10, and the pipe 22 includes an air feeding device 24 and a valve. 26 is provided. Further, the storage device 10 is provided with a thermometer 11 capable of measuring the internal temperature, and further has a pipe 12 for returning the granulated product of the soft resin extracted from the lower portion of the storage device 10 to the upper portion of the storage device 10. Is provided. Further, the pipe 12 is provided with a thermometer 13 capable of measuring the temperature in the pipe, and further provided with a valve 16 and a three-way valve 36. A pipe 32 for conveying the granulated resin after crystallization is provided to branch from the pipe 12 via a three-way valve 36.
Next, a method for storing a granulated product of resin crystallized from a soft resin will be described.
First, the valve 26 is set to “open”, and the granulated material of the soft resin is air-fed to the storage device 10 through the pipe 22 via the air-fed device 24. When the granulated product of soft resin is conveyed to the storage device 10, the three-way valve 36 is operated so as to be “open” on the pipe 12 side at the same time or when a certain amount of granulated product is stored, The valve 16 is set to “open”, and the granulated product of the soft resin is returned from the storage device 10 to the storage device 10 through the pipe 12 again using the air feeding device 14.
On the other hand, the granulated product of the soft resin from the upstream process to the storage device 10 is set to a capacity that does not cause blocking in the circulation path composed of the storage device and the piping. After discharging the granulated material of the soft resin inside, the air feeding device 24 is stopped and the valve 26 is closed.

In the storage system 100, when the granulated product of the soft resin is air-fed in the circulation path formed by the storage device 10 and the pipe 12, the ratio of the soft resin pellet to the air volume in the pipe is 0. 0.02 ton / Nm ³ or less is preferable, 0.015 ton / Nm ³ or less is more preferable, and 0.01 ton / Nm ³ or less is more preferable. By being the said air volume ratio, blocking of the granulated material of a soft resin is suppressed more notably.
Here, “blocking” refers to adhesion or binding of a granulated product of a soft resin, and is not said to be blocking if it is close but not attached.

  Further, the time for which the granulated product of the soft resin is circulated in the circulation path is preferably 4 hours or more, more preferably 6 hours or more from the viewpoint of crystallization while suppressing blocking. More preferably, it is 8 hours or more.

  The temperature in the storage device 10 for storing the granulated product of the soft resin, which is measured by the thermometer 11, is preferably 35 ° C. or less, more preferably 25 ° C. or less, from the viewpoint of promoting crystallization of the soft resin. 20 degrees C or less is still more preferable.

  From the viewpoint of promoting crystallization of the soft resin, it is preferable that the temperature in the pipe measured by the thermometer 13 where the granulated product of the soft resin is air-fed is 20 ° C. or higher and 30 ° C. or lower.

  After accelerating crystallization of the granulated product of the soft resin in the circulation path by the above-mentioned air transport and temperature conditions, the three-way valve 36 was closed, and the resin granule in the pipe 12 was discharged by the air transport device 14. Thereafter, the valve 16 is closed. Subsequently, the granulated product of the crystallized resin is packed as a final product by operating the three-way valve 36 toward the pipe 32 so as to be “open”.

<Second Embodiment>
The present invention relates to the second crystallization and storage step in FIG. 3, and relates to a method for storing a granulated product of another soft resin obtained in the first crystallization step.
As shown in FIG. 2, the second embodiment of the method for storing the granulated product of the soft resin of the present invention is a storage device 10 for receiving and storing the granulated product of the soft resin that is air-fed from the upstream process. In the circulation path formed by the pipe 12 for returning the granulated product of the soft resin extracted from the storage apparatus 10 to the storage apparatus 10 again and the storage apparatus 10 and the pipe 12, the soft resin Using a storage system comprising an air feeding device 14 for circulating the granulated material, and another storage device 40 for receiving and storing the granulated material of the soft resin air-fed from the upstream process. The storage device 10 circulates the granulated product of the soft resin through the circulation path, promotes crystallization of the soft resin, stores the granulated product of the crystallized resin, and stores other storages. In the device 40, the new softly air-fed from the upstream process Accept granules of fat, it is storage method of the granulated product of soft resin.

  In the second embodiment of the method for storing a granulated product of the soft resin of the present invention, at least two storage devices are provided. Therefore, crystallization and storage of the granulated product of the soft resin can be sequentially performed in a plurality of storage devices. The number of storage devices is appropriately selected in consideration of the production amount and production time of the granulated resin product.

Furthermore, the manufacturing method using the storage system 200 of 2nd Embodiment is demonstrated using FIG.
In the storage system 200 shown in FIG. 2, pipes 23 and 25 are provided for transporting the granulated product of the soft resin obtained in the first crystallization process to the storage devices 10 and 40. A device 24 and a three-way valve 26 are provided, and a valve 56 is provided in the pipe 25. Further, the flow path can be changed from the pipe 23 to the pipe 22 by switching the three-way valve 26 provided in the pipe 23.
Further, the storage device 10 is provided with a thermometer 11 capable of measuring the internal temperature, and further, a pipe 12 for returning the granulated product of the soft resin extracted from the lower portion of the storage device 10 to the upper portion of the storage device 10. Is provided. Further, the pipe 12 is provided with a thermometer 13 capable of measuring the temperature in the pipe, and further provided with a valve 16 and a three-way valve 36. A pipe 32 for conveying the granulated resin after crystallization is provided to branch from the pipe 12 via a three-way valve 36.
Further, the storage device 40 is provided with a thermometer 41 capable of measuring the internal temperature, and further has a pipe 42 for returning the granulated product of the soft resin extracted from the lower portion of the storage device 40 to the upper portion of the storage device 40. Is provided. Further, the pipe 42 is provided with a thermometer 43 capable of measuring the temperature in the pipe, and further provided with a valve 46 and a three-way valve 66. A pipe 62 for conveying the granulated resin after crystallization is provided to branch from the pipe 62 via a three-way valve 66.

Next, the storage method of the granulated product of the resin crystallized from the soft resin in the second embodiment will be described.
First, the three-way valve 26 is operated to “open” toward the pipe 22. Next, the granulated product of the soft resin is air-fed to the storage device 10 through the pipe 22 via the air-fed device 24. The three-way valve 36 is operated so that it opens to the pipe 12 side at the same time or when a certain amount of granulated material is stored in the storage device 10 when the granulated product of soft resin is conveyed. Is opened, and the granulated product of the soft resin is returned from the storage device 10 to the storage device 10 through the pipe 12 again using the air feeding device 14.
On the other hand, the granulated product of the soft resin from the upstream process to the storage device 10 is limited to a capacity that does not cause blocking in the circulation path composed of the storage device 10 and the pipe 12, and then the air transport device 24. After discharging the granulated material of the soft resin in the pipe 22, the air feeding device 24 is stopped and the valve 26 is closed.
In the storage system 200, when the granulated product of the soft resin is air-fed in the circulation path formed by the storage device 10 and the pipe 12, the ratio of the soft resin pellet and the air volume in the pipe is The description is omitted here because it is the same as that described in the first embodiment.
Further, the time for circulating the granulated product of the soft resin in the circulation path, the temperature in the storage device 10 for storing the granulated product of the soft resin, measured by the thermometer 11, and the thermometer 13 Since the measured temperature in the pipe where the granulated product of the soft resin is air-fed is the same as described in the first embodiment, the description is omitted here.

  After accelerating crystallization of the granulated product of the soft resin in the circulation path by the above-mentioned air transport and temperature conditions, the three-way valve 36 was closed, and the resin granule in the pipe 12 was discharged by the air transport device 14. Thereafter, the valve 16 is closed. Next, the granulated product of the crystallized resin is packaged as a final product by operating the three-way valve 36 to open toward the pipe 32.

In the circulation path between the storage device 10 and the pipe 12, the three-way valve 26 is operated to “open” toward the pipe 25 at or after the start of the circulation of the granulated product of the soft resin. Next, the granulated material of the soft resin is air-fed to the storage device 40 through the pipe 25 via the air-fed device 24. When the granulated material of the soft resin is conveyed to the storage device 40, the three-way valve 66 is operated so as to be “open” on the pipe 42 side at the same time or when a certain amount of the granulated material is stored, The valve 46 is opened, and the granulated product of the soft resin is returned from the storage device 40 to the storage device 40 via the pipe 42 using the air feeding device 44.
On the other hand, the granulated product of the soft resin from the upstream process to the storage device 40 is limited to a capacity that does not cause blocking in the circulation path composed of the storage device 40 and the pipe 42, and then the air transport device 44. After discharging the granulated material of the soft resin in the pipe 42, the air feeding device 44 is stopped and the valve 46 is closed.
In the storage system 200, when the granulated product of the soft resin is air-fed in the circulation path formed by the storage device 40 and the pipe 42, the ratio of the soft resin pellet and the air volume in the pipe is The description is omitted here because it is the same as that described in the first embodiment.
Also, the time for circulating the granulated product of the soft resin in the circulation path, the temperature in the storage device 40 for storing the granulated product of the soft resin, measured by the thermometer 41, and the thermometer 43 Since the measured temperature in the pipe where the granulated product of the soft resin is air-fed is the same as described in the first embodiment, the description is omitted here.

  After promoting the crystallization of the soft resin granulated material in the circulation path due to the air transport and temperature conditions described above, the three-way valve 66 was closed, and the resin granule in the pipe 42 was discharged by the air transport device 44. Thereafter, the valve 46 is closed. Next, the granulated product of the crystallized resin is packed as a final product by operating the three-way valve 66 to open toward the pipe 62.

Next, a soft resin to which the method for producing a granulated product of the present invention can be applied will be described.
The tensile elastic modulus of the soft resin is preferably 1 to 200 MPa, more preferably 5 to 150 MPa, and still more preferably 10 to 100 MPa in accordance with JIS K 7113.
Further, the soft resin in the present invention conforms to JIS K7210, and the melt flow rate (hereinafter also referred to as “MFR”) under the conditions of a temperature of 230 ° C. and a load of 21.18 N is 1 to 10,000 g / 10 minutes. Is preferable, more preferably 3 to 5,000 g / 10 minutes, and still more preferably 5 to 3,000 g / 10 minutes.
Here, the soft resin is used in the meaning of including an uncrystallized resin before crystallization in a resin having crystallinity.
A specific example of the soft resin will be described later.
Even if the soft resin has a tensile elastic modulus and MFR in the above-described range, blocking of the resin pellets is suppressed by using the method for producing a granulated product of the present invention.
In addition, the measuring method of a tensile elasticity modulus and MFR is as having described below.

(Measurement of tensile modulus)
Based on JIS K7113, the tensile modulus was measured under the following conditions.
-Test piece (No. 2 dumbbell) Thickness: 1mm
・ Crosshead speed: 100mm / min ・ Load cell: 100N
・ Measurement temperature: 23 ℃

[Measurement of melt flow rate (MFR)]
According to JIS K7210, the measurement was performed under conditions of a temperature of 230 ° C. and a load of 21.18N.

The resin having adhesiveness used in the method for stirring resin pellets of the present invention has the above-mentioned physical properties, and specifically includes the following.
[Olefin polymer]
The olefin polymer used as an adhesive resin is a differential scanning calorimeter (DSC), and the sample is held at −10 ° C. for 5 minutes in a nitrogen atmosphere and then heated at 10 ° C./min. The melting endotherm (ΔH−D) obtained from the melting endotherm curve is preferably 1 to 80 J / g.
The olefin polymer of the present invention is preferably an olefin polymer obtained by polymerizing one or more monomers selected from ethylene and an α-olefin having 3 to 28 carbon atoms.
Examples of the α-olefin having 3 to 28 carbon atoms include propylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-octene, 1-decene, 1-undecene and 1-dodecene. 1-tridecene, 1-tetradecene, 1-pentadecene, 1-hexadecene, 1-heptadecene, 1-octadecene, 1-nonadecene, 1-icocene and the like. Among these, Preferably it is C3-C24 alpha-olefin, More preferably, it is C3-C12 alpha-olefin, More preferably, it is C3-C6 alpha-olefin, Most preferably, it is C3-C4 An α-olefin, most preferably propylene. An olefin polymer obtained by polymerizing one of these alone may be used, or an olefin copolymer obtained by copolymerizing two or more of them may be used. In the present invention, the term “olefin polymer” simply includes an olefin copolymer.
Examples of the olefin polymer include an ethylene polymer in which 50 mol% or more of the monomer constituting the polymer is an ethylene monomer, a propylene polymer in which 50 mol% or more of the monomer constituting the polymer is a propylene monomer, Examples include a butene-based polymer in which 50 mol% or more of the monomers constituting the coalescence are butene monomers, and a propylene-based polymer that provides excellent molded article properties, for example, film properties, from the viewpoint of rigidity and transparency. More preferred.

Examples of the olefin polymer used in the present invention include propylene homopolymer, propylene-ethylene random copolymer, propylene-butene random copolymer, propylene-α-olefin random copolymer, propylene-ethylene-butene random. A propylene polymer selected from a copolymer, a propylene-ethylene block copolymer, a propylene-butene block copolymer, a propylene-α-olefin block copolymer, a propylene-α-olefin graft copolymer, etc. Preferably there is.
Further, in the propylene polymer, it is more preferable that 50 mol% or more of the monomers constituting the olefin polymer is a propylene monomer, and the propylene polymer is (i) and / or (ii). The polymer which satisfy | fills may be sufficient.
(I) The structural unit of ethylene is contained in excess of 0 mol% and 20 mol% or less.
(Ii) The structural unit of 1-butene is contained in an amount of more than 0 mol% and 30 mol% or less.

[Melting endotherm (ΔH−D)]
The melting endotherm (ΔH-D) of the olefin polymer and the propylene polymer is preferably 0 to 80 J / g, more preferably 10 to 70 J / g, and still more preferably 20 to 60 J / g. g, particularly preferably 20 to 50 J / g.
In the present invention, a differential scanning calorimeter (DSC-7, manufactured by Perkin Elmer Co., Ltd.) is used, and 10 mg of a sample is held at −10 ° C. for 5 minutes in a nitrogen atmosphere and then heated at 10 ° C./min. Calculated by calculating the area enclosed by the line (baseline) connecting the line part including the peak of the melting endotherm curve obtained by the above, the point on the low temperature side where there is no change in calorie, and the point on the high temperature side where there is no change in calorie Is done.

The propylene polymer used in the present invention is preferably a propylene polymer that satisfies at least one of the following (1) and (2), more preferably satisfies the following (3) and (4), and Preferably, the following (5) and (6) are satisfied.
(1) [mmmm] is 20 to 60 mol%.
(2) Using a differential scanning calorimeter (DSC), hold the sample at −10 ° C. for 5 minutes in a nitrogen atmosphere, and then raise the temperature at 10 ° C./min. The melting point (Tm-D) defined as the observed peak top is 0-120 ° C.
(3) [rrrr] / (1- [mmmm]) ≦ 0.1
(4) Molecular weight distribution (Mw / Mn) <4.0
(5) [rmrm]> 2.5 mol%
(6) [mm] × [rr] / [mr] ² ≦ 2.0

(1) Mesopentad fraction [mmmm]
The mesopentad fraction [mmmm] is an index representing the stereoregularity of the propylene-based polymer, and the stereoregularity increases as the mesopentad fraction [mmmm] increases.

(2) Melting point (Tm-D)
The melting point (Tm-D) of the propylene polymer is preferably higher from the viewpoints of strength and moldability. Preferably it is 0-120 degreeC, More preferably, it is 50-100 degreeC, More preferably, it is 55-90 degreeC, More preferably, it is 60-80 degreeC.
In the present invention, a differential scanning calorimeter (DSC-7, manufactured by Perkin Elmer Co., Ltd.) is used, and 10 mg of a sample is held at −10 ° C. for 5 minutes in a nitrogen atmosphere and then heated at 10 ° C./min. The peak top of the peak observed on the highest temperature side of the melting endothermic curve obtained by the above is defined as the melting point (Tm-D). The melting point can be controlled by appropriately adjusting the monomer concentration and reaction pressure.

(3) [rrrr] / (1- [mmmm])
The value of [rrrr] / (1- [mmmm]) is obtained from the mesopentad fraction [mmmm] and the racemic pentad fraction [rrrr] and is an index indicating the uniformity of the regularity distribution of polypropylene. When this value of [rrrr] / (1- [mmmm]) is increased, it becomes a mixture of highly stereoregular polypropylene and atactic polypropylene like conventional polypropylene produced using an existing catalyst system, and the polypropylene is stretched after molding. It causes stickiness of the film. The unit of [rrrr] and [mmmm] in the above is mol%.
The value of [rrrr] / (1- [mmmm]) in the propylene-based polymer is preferably 0.1 or less, more preferably 0.001 to 0.05, and still more preferably 0.00 from the viewpoint of stickiness. 001 to 0.04, particularly preferably 0.01 to 0.04.

Here, the mesopentad fraction [mmmm], the racemic pentad fraction [rrrr], and the racemic mesoracemi mesopentad fraction [rmrm] to be described later are determined according to “Macromolecules, 6, 925 (1973) ”, and meso fraction, racemic fraction, and racemic meso-racemic meso in pentad units in the polypropylene molecular chain measured by the methyl group signal of the ¹³ C-NMR spectrum. It is a fraction. As the mesopentad fraction [mmmm] increases, the stereoregularity increases. Further, triad fractions [mm], [rr] and [mr] described later are also calculated by the above method.

(4) Molecular weight distribution (Mw / Mn)
The molecular weight distribution (Mw / Mn) of the propylene-based polymer is preferably less than 4 from the viewpoint of high strength. If the molecular weight distribution (Mw / Mn) is less than 4, low molecular weight components that adversely affect stretchability and film physical properties (for example, mechanical properties and optical properties) are suppressed, and the film properties of the polypropylene stretched film of the present invention described later are described. Is suppressed. The molecular weight distribution (Mw / Mn) of the olefin polymer and the propylene polymer is preferably 3 or less, more preferably 2.5 or less, and further preferably 1.5 to 2.5.
In the present invention, the molecular weight distribution (Mw / Mn) is a value calculated from the polystyrene-equivalent weight average molecular weight Mw and number average molecular weight Mn measured by gel permeation chromatography (GPC).

(5) Racemic meso racemic meso pentad fraction [rmrm]
The racemic meso racemic meso pentad fraction [rmrm] is an index representing the randomness of the stereoregularity of polypropylene, and the randomness of polypropylene increases as the value increases.
The racemic meso racemic meso pentad fraction [rmrm] of the propylene polymer is preferably more than 2.5 mol%, more preferably 2.6 mol% or more, and even more preferably 2.7 mol% or more. It is. The upper limit is usually preferably about 10 mol%, more preferably 7 mol%, still more preferably 5 mol%, and particularly preferably 4 mol%.

(6) [mm] × [rr] / [mr] ²
The value of [mm] × [rr] / [mr] ² calculated from the triad fraction [mm], [rr] and [mr] represents an index of randomness of the polymer. Becomes higher. The propylene polymer used in the present invention has a value of the above formula of usually 2 or less, preferably 1.8 to 0.5, more preferably 1.5 to 0.5. In addition, the unit of [mm] and [rr] in the above is mol%.

  The effect of the present invention becomes larger as the resin crystallization time of the resin pellet having adhesiveness becomes longer, and a large blocking suppression effect is obtained in the case of a resin having a half crystallization time of 1 minute or longer. The effect is even greater with resins longer than 5 minutes.

As the propylene polymer, for example, a propylene homopolymer can be produced using a metallocene catalyst and propylene as described in WO2003 / 087172. In particular, those using a transition metal compound in which a ligand forms a cross-linked structure via a cross-linking group are preferred, and in particular, a transition metal compound that forms a cross-linked structure via two cross-linking groups and Metallocene catalysts obtained by combining promoters are preferred.
For example,
(I) General formula (I)

[In the formula, M represents a group 3-10 of the periodic table or a lanthanoid series metal element, and E ¹ and E ² represent a substituted cyclopentadienyl group, an indenyl group, a substituted indenyl group, a heterocyclopentadienyl group, respectively. A ligand selected from a substituted heterocyclopentadienyl group, an amide group, a phosphide group, a hydrocarbon group, and a silicon-containing group, which forms a cross-linked structure via A ¹ and A ² In addition, they may be the same or different from each other, X represents a σ-bonded ligand, and when there are a plurality of X, the plurality of X may be the same or different, and other X, E ¹ , E ² or Y may be cross-linked. Y represents a Lewis base, and when there are a plurality of Y, the plurality of Y may be the same or different, and may be cross-linked with other Y, E ¹ , E ² or X, and A ¹ and A ² are A divalent bridging group that binds two ligands, a hydrocarbon group having 1 to 20 carbon atoms, a halogen-containing hydrocarbon group having 1 to 20 carbon atoms, a silicon-containing group, a germanium-containing group, a tin-containing group _{, -O -, - CO -,} - S -, - SO 2 -, - Se -, - NR 1 -, - PR 1 -, - P (O) R 1 -, - BR 1 - or -AlR ¹ - R ¹ represents a hydrogen atom, a halogen atom, a hydrocarbon group having 1 to 20 carbon atoms, or a halogen-containing hydrocarbon group having 1 to 20 carbon atoms, which may be the same as or different from each other. q represents an integer of 1 to 5 and represents [(M valence) -2], and r represents an integer of 0 to 3. ]
And (ii) (ii-1) a compound capable of reacting with the transition metal compound of component (i) or a derivative thereof to form an ionic complex, and (ii-2) aluminoxane And a polymerization catalyst containing a component selected from:

  As the transition metal compound (i), a ligand is preferably a (1,2 ′) (2,1 ′) double-bridged transition metal compound, such as (1,2′-dimethylsilylene) ( 2,1'-dimethylsilylene) -bis (3-trimethylsilylmethylindenyl) zirconium dichloride.

  Specific examples of the compound of component (ii-1) include triethylammonium tetraphenylborate, tri-n-butylammonium tetraphenylborate, trimethylammonium tetraphenylborate, tetraethylammonium tetraphenylborate, methyl tetraphenylborate (tri- n-butyl) ammonium, benzyl tetraphenylborate (tri-n-butyl) ammonium, dimethyldiphenylammonium tetraphenylborate, triphenyl (methyl) ammonium tetraphenylborate, trimethylanilinium tetraphenylborate, methylpyridinium tetraphenylborate, tetra Benzylpyridinium phenylborate, methyl tetraphenylborate (2-cyanopyridinium), trikis (tetrafluorophenyl) borate triethyla Monium, tetrakis (pentafluorophenyl) tri-n-butylammonium borate, tetrakis (pentafluorophenyl) triphenylammonium borate, tetrakis (pentafluorophenyl) tetra-n-butylammonium borate, tetraethylammonium tetrakis (pentafluorophenyl) borate Benzyl tetrakis (pentafluorophenyl) ammonium borate (tri-n-butyl), methyldiphenylammonium tetrakis (pentafluorophenyl) borate, triphenyl (methyl) ammonium tetrakis (pentafluorophenyl) borate, tetrakis (pentafluorophenyl) boric acid Methylanilinium, tetrakis (pentafluorophenyl) borate dimethylanilinium, tetrakis (pentafluoropheny L) Trimethylanilinium borate, methyl pyridinium tetrakis (pentafluorophenyl) borate, benzyl pyridinium tetrakis (pentafluorophenyl) borate, methyl tetrakis (pentafluorophenyl) borate (2-cyanopyridinium), benzyl tetrakis (pentafluorophenyl) borate (2-cyanopyridinium), methyl tetrakis (pentafluorophenyl) borate (4-cyanopyridinium), triphenylphosphonium tetrakis (pentafluorophenyl) borate, tetrakis [bis (3,5-ditrifluoromethyl) phenyl] dimethylaniline borate Ferrocenium tetraphenylborate, silver tetraphenylborate, trityl tetraphenylborate, tetraphenylporphyrin manganese tetraphenylborate, Trakis (pentafluorophenyl) borate ferrocenium, tetrakis (pentafluorophenyl) borate (1,1′-dimethylferrocenium), tetrakis (pentafluorophenyl) decamethylferrocenium borate, tetrakis (pentafluorophenyl) silver borate, Tetrakis (pentafluorophenyl) triborate borate, tetrakis (pentafluorophenyl) lithium borate, tetrakis (pentafluorophenyl) sodium borate, tetrakis (pentafluorophenyl) borate tetraphenylporphyrin manganese, silver tetrafluoroborate, silver hexafluorophosphate, hexa Examples thereof include silver fluoroarsenate, silver perchlorate, silver trifluoroacetate, and silver trifluoromethanesulfonate.

  Examples of the aluminoxane as the component (ii-2) include known chain aluminoxanes and cyclic aluminoxanes.

  Trimethylaluminum, triethylaluminum, triisopropylaluminum, triisobutylaluminum, dimethylaluminum chloride, diethylaluminum chloride, methylaluminum dichloride, ethylaluminum dichloride, dimethylaluminum fluoride, diisobutylaluminum hydride, diethylaluminum hydride, ethylaluminum sesquichloride, etc. These organoaluminum compounds may be used in combination to produce a propylene polymer.

[Other resins with adhesive properties]
Similarly, examples of propylene polymers produced with metallocene catalysts include copolymers of propylene and ethylene (such as vistamaxx manufactured by Exxon Mobel), and copolymers of ethylene and octene (such as Engage manufactured by Dow Chemical). , Propylene and ethylene, butene copolymer (Degussa Bestplast etc.) and the like.

  EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited at all by these examples.

Below, the measuring method of the olefin polymer used in the Example, the propylene-type polymer, and resin which has adhesiveness is demonstrated.
[DSC measurement]
Using a differential scanning calorimeter (DSC-7, manufactured by Perkin Elmer Co.), a melting endotherm obtained by holding 10 mg of a sample at −10 ° C. for 5 minutes in a nitrogen atmosphere and then raising the temperature at 10 ° C./min. It calculated | required as melting endotherm (DELTA) HD from a curve. Moreover, melting | fusing point (Tm-D) was calculated | required from the peak top of the peak observed on the highest temperature side of the obtained melting endothermic curve.
The melting endotherm (ΔH-D) is a differential scanning calorimeter (manufactured by Perkin Elmer Co., Ltd.) with a line connecting a point on the low temperature side where there is no change in heat quantity and a point on the high temperature side where there is no change in heat quantity as the baseline. , DSC-7), and calculating the area surrounded by the line portion including the peak of the melting endothermic curve obtained by DSC measurement and the base line.

[Weight average molecular weight (Mw), molecular weight distribution (Mw / Mn) measurement]
The weight average molecular weight (Mw) and the number average molecular weight (Mn) were measured by gel permeation chromatography (GPC) method to determine the molecular weight distribution (Mw / Mn). For the measurement, the following equipment and conditions were used, and polystyrene-reduced weight average molecular weight and number average molecular weight were obtained. The molecular weight distribution (Mw / Mn) is a value calculated from these weight average molecular weight (Mw) and number average molecular weight (Mn).
<GPC measurement device>
Column: “TOSO GMHHR-H (S) HT” manufactured by Tosoh Corporation
Detector: RI detection for liquid chromatogram "WATERS 150C" manufactured by Waters Corporation
<Measurement conditions>
Solvent: 1,2,4-trichlorobenzene Measurement temperature: 145 ° C
Flow rate: 1.0 ml / min Sample concentration: 2.2 mg / ml
Injection volume: 160 μl
Calibration curve: Universal Calibration
Analysis program: HT-GPC (Ver.1.0)

[NMR measurement]
The ¹³ C-NMR spectrum was measured with the following apparatus and conditions. In addition, the attribution of the peak followed the method proposed by A. Zambelli et al. In “Macromolecules, 8, 687 (1975)”.
Apparatus: JNM-EX400 type ¹³ C-NMR apparatus manufactured by JEOL Ltd. Method: Proton complete decoupling method Concentration: 220 mg / ml
Solvent: 90:10 (volume ratio) mixed solvent of 1,2,4-trichlorobenzene and heavy benzene Temperature: 130 ° C
Pulse width: 45 °
Pulse repetition time: 4 seconds Integration: 10,000 times

<Calculation formula>
M = m / S × 100
R = γ / S × 100
S = Pββ + Pαβ + Pαγ
S: Signal intensity of side chain methyl carbon atoms of all propylene units Pββ: 19.8 to 22.5 ppm
Pαβ: 18.0 to 17.5 ppm
Pαγ: 17.5 to 17.1 ppm
γ: Racemic pentad chain: 20.7 to 20.3 ppm
m: Mesopentad chain: 21.7-22.5 ppm

The mesopentad fraction [mmmm], the racemic pentad fraction [rrrr] and the racemic mesoracemi mesopentad fraction [rmrm] are described in “Macromolecules, 6, 925 (1973)” by A. Zambelli et al. are those determined in conformity with the proposed method, meso fraction in pentad units in the polypropylene molecular chain as measured by the signal of the methyl groups of the ^{13 C-NMR} spectrum, the racemic fraction and the racemic meso racemic meso It is a fraction. As the mesopentad fraction [mmmm] increases, the stereoregularity increases. The triad fractions [mm], [rr] and [mr] were also calculated by the above method.

[Melt flow rate (MFR) measurement]
Based on JIS K7210, the measurement was performed under conditions of a temperature of 230 ° C. and a load of 2.16 kg.

Production Example 1 [Production of Polypropylene Polymer (PP1)]
To a stainless steel reactor with an internal volume of 20 L with a stirrer, n-heptane was 20 L / hr, triisobutylaluminum was 15 mmol / hr, dimethylanilinium tetrakispentafluorophenylborate, (1,2'-dimethylsilylene) ( 2,1′-dimethylsilylene) -bis (3-trimethylsilylmethylindenyl) zirconium dichloride and triisobutylaluminum in a mass ratio of 1: 2: 20 were converted to zirconium in the catalyst component obtained in advance by contacting with propylene. At 6 μmol / hr.
Propylene and hydrogen were continuously supplied so as to keep the total pressure in the reactor at 1.0 MPa · G, and the polymerization temperature was appropriately adjusted around 65 ° C. to obtain a polymerization solution having a desired molecular weight.
To the obtained polymerization solution, an antioxidant was added so that the content ratio was 1000 mass ppm, and then n-heptane as a solvent was removed to obtain a polypropylene polymer (PP1).

Production Example 2 [Production of Polypropylene Polymer (PP2)]
To a stainless steel reactor with an internal volume of 20 L with a stirrer, n-heptane was 20 L / hr, triisobutylaluminum was 15 mmol / hr, dimethylanilinium tetrakispentafluorophenylborate, (1,2'-dimethylsilylene) ( 2,1′-dimethylsilylene) -bis (3-trimethylsilylmethylindenyl) zirconium dichloride and triisobutylaluminum in a mass ratio of 1: 2: 20 were converted to zirconium in the catalyst component obtained in advance by contacting with propylene. At 30 μmol / hr.
Propylene and hydrogen are continuously fed under conditions where the ratio of hydrogen is much smaller than that of Production Example 1 so as to keep the total pressure in the reactor at 1.0 MPa · G, and the polymerization temperature is appropriately adjusted around 70 ° C. to obtain a desired molecular weight A polymerization solution having was obtained.
To the obtained polymerization solution, an antioxidant was added so that the content ratio was 1000 mass ppm, and then n-heptane as a solvent was removed to obtain a polypropylene polymer (PP1).

  The above-mentioned measurement was performed for the polypropylene polymer (PP1) and the polypropylene polymer (PP2) obtained in Production Examples 1 and 2. The results are shown in Table 1 below.

Next, Irganox 1010 was added to the polymerization solution of the polypropylene polymer (PP1) produced in Production Example 1 before the addition of the antioxidant and before the solvent removal so as to be 500 ppm by mass. The solvent was removed at an internal temperature of 150 ° C. using a stainless steel devolatilization tank having an internal volume of 3 m ³ .
Thereafter, the molten resin was transferred to a polymer mixer with jacket (L84-VPR-3.7, manufactured by Satake Corporation) with a transfer pump. After cooling the resin to 65 ° C. with a polymer mixer, it was granulated in water with a granulator. As the granulator, PASC-21HS manufactured by Tanabe Plastics Machine Co., Ltd. was used, the cooling water temperature was 10 ° C., and the peripheral speed of the cutter was 3.8 m / s. Moreover, silicone (Shin-Etsu Chemical Co., Ltd. product, X-22-904) was added to cooling water so that it might become 600 mass ppm.

The time from the underwater granulation step to the first crystallization step is 80 minutes, and then, as the second crystallization step, dehydration is performed, and the resulting semi-crystalline polypropylene pellets are stored in the storage system shown in FIG. When the inside of the circulation path formed by the storage device 10 and the pipe 12 is circulated for 8 hours at a ratio of pellet to air volume of 0.01 ton / Nm ³ , no lump is formed. It was.

Comparative Example 1
The same operation as in Example 1 was performed except that the inside of the circulation path formed by the storage device 10 and the pipe 12 shown in FIG. 1 was not circulated. The results are shown in Table 1.

Examples 2-6
The same operation as in Example 1 was performed except that the conditions in the circulation path formed by the storage device 10 and the pipe 12 shown in FIG. 1 were changed to the conditions shown in Table 1. The results are shown in Table 1.
In addition, the possibility of discharge from the silo was also evaluated.

  ADVANTAGE OF THE INVENTION According to this invention, the storage method of the granulated material which can store this can be provided, suppressing the blocking of the granulated material of a soft resin.

  DESCRIPTION OF SYMBOLS 10 Storage device, 11, 13 Thermometer, 12, 22 Piping, 14, 24 Air transport device, 16, 26 Valve, 36 Three-way valve, 100 Storage system.

Claims (8)

A storage device for receiving and storing a granulated product of soft resin that is air-fed from an upstream process;
A pipe for returning the granulated product of the soft resin extracted from the storage device to the storage device again;
In the circulation path formed by the storage device and the pipe, an air feeding device for circulating the granulated product of the soft resin,
Using a storage system with
The soft resin granulated product is circulated through the circulation path by the air feeding device while receiving the granulated product of the soft resin air-fed from the upstream process into the storage device, thereby the soft resin A method for storing a granulated product of a soft resin, which promotes crystallization of the resin and stores the granulated product of the resin that has been crystallized. In order to receive and store the granulated soft resin that is air-fed from the upstream process, using a storage system equipped with another storage device,
In the storage device, the granulated product of the soft resin is circulated through the circulation path, the crystallization of the soft resin is promoted, and the granulated product of the resin that has been crystallized is stored.
The method for storing a soft resin granulated product according to claim 1, wherein the other storage device receives a soft resin granulated product that is newly air-fed from the upstream process. The ratio of the soft resin pellet and the air flow rate in the pipe when the granulated product of the soft resin is idled in the circulation path is 0.02 ton / Nm ³ or less. The storage method of the granulated material of the soft resin as described. The method for storing a granulated product of a soft resin according to any one of claims 1 to 3, wherein the soft resin is a propylene polymer satisfying at least one of (1) and (2).
(1) [mmmm] is 20 to 60 mol%.
(2) Using a differential scanning calorimeter (DSC), hold the sample at −10 ° C. for 5 minutes in a nitrogen atmosphere, and then raise the temperature at 10 ° C./min. The melting point (Tm-D) defined as the observed peak top is 0-120 ° C.   The tensile elastic modulus of the soft resin is 1 to 200 MPa, and the melt flow rate (MFR) of the soft resin under conditions of a temperature of 230 ° C. and a load of 21.18 N is 1 to 10,000 g / 10 minutes. Item 5. A method for storing a granulated product of the soft resin according to any one of Items 1 to 4.   The method for storing a granulated product of a soft resin according to any one of claims 1 to 5, wherein the time for which the granulated product of the soft resin is circulated in the circulation path is 4 hours or more.   The storage method of the granulated product of a soft resin as described in any one of Claims 1-6 whose temperature in the storage apparatus which stores the granulated product of the said soft resin is 35 degrees C or less.   The method for storing a granulated product of a soft resin according to any one of claims 1 to 7, wherein a temperature in a pipe where the granulated product of the soft resin is air-fed is 10 ° C or higher and 30 ° C or lower.