JP2019038967A - Method for producing polypropylene-based foam filament - Google Patents

Abstract

To provide method for producing a polypropylene-based foam filament that constitutes a structure, which is lightweight, has such heat resistance as to hold a shape even on temperature condition of high temperature, preferably, 121°C or higher, and has deformation recovery property when a load is removed after having been continuously deformed by a continuous load, and is molded by free fall with good productivity by a simple device.SOLUTION: A method producing a polypropylene-based foam filament includes blending more than 0 pt.wt. and 5 pts.wt. or less of a foaming agent (Y) to 100 pts.wt. (component (X)+component (Z) is 100 wt.%) of a polypropylene-based resin composition (G) which contains 1-99 wt.% of a polypropylene-based resin composition (X) satisfying characteristics (x1) and 1-99 wt.% of a polypropylene-based resin (Z) satisfying characteristics (z1) to (z2) and satisfies characteristics (g1) to (g2), extrusion molding the mixture, and forming a filament by free fall.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a method for producing a polypropylene-based foamed wire, and in particular, is lightweight, has heat resistance capable of maintaining a shape even at high temperature, preferably at a temperature of 121 ° C. or higher, and continues with a continuous load. A method for producing a polypropylene-based deformation-recoverable heat-resistant foamed wire formed by free fall that forms a structure having deformation-recoverability when the load is removed after being deformed by a simple apparatus with high productivity About.

  Conventionally, deformation-recoverable structures, for example, bedding such as beds, cushion materials for homes, vehicles, ships, aircraft seats, etc., have been made of urethane foam, non-elastic crimped cotton, and non-elastic crimped fibers. Bonded resin cotton or hard cotton has been used.

In recent years, attempts have been made to use a three-dimensional network structure obtained by extruding a thermoplastic resin in a loop shape by extrusion molding, and thermally bonding and cooling and solidifying this strand as the cushioning material. Yes. As the thermoplastic resin, it is known to use a polyester-based elastomer, a polyurethane-based elastomer, or a polyamide-based elastomer (see, for example, Patent Document 1: Japanese Patent Laid-Open No. 7-068061). However, these resins are expensive and difficult to recycle.
On the other hand, Patent Document 2 (Japanese Patent Laid-Open No. 2004-218116) and Patent Document 3 (Japanese Patent Laid-Open No. 2006-2001117) describe an ethylene-vinyl acetate copolymer (EVA) and an ethylene / α-olefin copolymer. Certain polyethylene-based resins are disclosed and widely used. However, although three-dimensional network structures using these polyethylene-based resins have excellent performance, they place importance on flexibility and thermal adhesiveness. There is a problem that the melting point of the resin is lowered and the deformation recovery property at a high temperature (for example, 70 ° C.) is inferior. For this reason, when a polyethylene-based resin is used, application to automobile cushions, cushioning parts, and bed cushions with a heating function is greatly limited.
In order to solve this problem, for example, in Patent Document 4 (Japanese Patent Laid-Open No. 2013-181117), a specific ethylenically unsaturated silane compound is grafted to a specific ethylene polymer, and the resulting graft reaction product is grafted. A method of imparting heat resistance by a method of storing a silanol condensation catalyst after molding, storing it in a room for spraying 40 ° C. warm water in a mist for one week, and performing a crosslinking treatment is disclosed. The cross-linking treatment takes a long time of one week, and is inferior in productivity. Further, since the cross-linking treatment is performed, the recyclability is inferior.

Furthermore, in recent years, hospitals and the like have a need for cleaning the cushion itself and, in some cases, sterilizing treatment, and there is a demand for resistance to steam sterilization treatment at high temperatures, preferably 121 ° C. or higher.
Those using a polyethylene resin composition melt during steam sterilization, making it difficult to maintain the shape. Examples of the resin that can withstand the steam sterilization treatment include a polypropylene-based resin. However, since polypropylene causes plastic deformation, there is a problem of poor deformation recovery.
In order to solve this problem, for example, Patent Document 5 (Japanese Patent Laid-Open No. 2002-061059) discloses a three-dimensional structure in which 5 to 30% by weight of SBS is blended with polypropylene. It is unclear whether it can withstand steam sterilization, and the compressive residual strain that shows deformation recovery is only shown in the test results without holding time at room temperature. However, after being continuously deformed by a continuous load, it is impossible to know the deformation recovery property when the load is removed and the deformation recovery property at high temperatures.
In order to solve these problems, for example, Patent Document 6 (Japanese Patent Laid-Open No. 2006-028121) and Patent Document 7 (Japanese Patent Laid-Open No. 2006-028122) disclose a deformation-recoverable heat-resistant structure made of a specific propylene-based resin composition. Is disclosed.
However, it has not been able to fully meet the growing needs for weight reduction.

As one technique for reducing the weight of the deformation-recoverable structure, a method of foaming the deformation-recoverable structure is conceivable. For example, in Patent Document 8 (Japanese Patent Application Laid-Open No. 2002-266223), dynamically crosslinked EPDM is used. A filament having an apparent specific gravity of 0.45 to 0.35, which is foamed using the thermoplastic elastomer contained therein, is disclosed. However, since it was dynamically crosslinked, it was inferior in recyclability.
Patent Document 9 (Japanese Patent Laid-Open No. 2001-248050), Patent Document 10 (Japanese Patent Laid-Open No. 08-064101), and Patent Document 11 (Japanese Patent Laid-Open No. 2011-256479) describe a resin composition and a foaming agent. A technique is disclosed in which an unfoamed filament is formed and then foamed at a high temperature. However, a foaming process is required and the productivity is poor.
In Example 2 of Patent Document 12 (Japanese Patent Laid-Open No. 08-187806), azodicarbonamide chemistry was applied to low density polyethylene having a melt flow rate of 9.5 g / 10 min and an initial flexural modulus of 900 kgf / cm ^2. A filament formed by blending a foaming agent and a color pigment is disclosed. However, since it is made of low density polyethylene, heat resistance is poor.
Further, by simply blending a foaming agent with the resin compositions disclosed in the aforementioned Patent Documents 6 and 7, when forming a filament by free fall, the bubble film on the surface of the filament is broken, and the filament There are problems such as excessive unevenness on the surface, resulting in kinks when continuously deformed by a continuous load, and unpleasant sounds due to rubbing of the filaments.

As a method for preventing breakage of the bubble film on the surface of the foamed filament formed by free fall, for example, Patent Document 13 (WO2014 / 192790) includes a thermoplastic resin containing a foaming agent as a core layer and a foaming agent. There is disclosed a continuous filament body in which a thermoplastic resin not containing water is coextruded so as to form a sheath layer, and the bubble portion is present more on the center side than on the surface layer side. However, since a thermoplastic resin that does not contain a foaming agent is arranged in the sheath layer, the bubble film is not easily broken on the surface of the filament, but a nozzle having a complicated structure is used to form a multilayered filament. There is a problem that the equipment cost becomes expensive.
As a method of forming a single-layer structure filament, the bubble film is hardly broken on the filament surface. For example, in the example of Patent Document 14 (Japanese Patent Laid-Open No. 2009-293020), a specific MFR, A propylene-based polymer having a Q value, a ratio of components having a weight average molecular weight of 2 million or more, an elution amount to orthodichlorobenzene at 40 ° C. or less, an isotactic triad fraction, a strain hardening degree, and a melt tension at 230 ° C. There is disclosed a strand-like foamed molded article obtained by melt-extruding a resin composition obtained by blending a foaming agent and continuously taking it out. However, since 100% by weight of a specific propylene polymer is used as a resin component, there is no degree of freedom in adjusting physical properties, and it was obtained continuously, not due to free fall. .

Japanese Patent Laid-Open No. 7-068061 JP 2004-218116 A JP 2006-200117 A JP 2013-181117 A JP 2002-061059 A JP, 2006-02811, A JP 2006-028122 A JP 2002-266223 A JP 2001-248050 A Japanese Patent Application Laid-Open No. 08-064110 JP2011-256479A Japanese Patent Laid-Open No. 08-187806 WO2014 / 192790 JP 2009-293020 A

  In view of the above-mentioned problems of the prior art, the object of the present invention is lightweight, has heat resistance capable of maintaining the shape even under high temperature, preferably at 121 ° C. or higher, and is continued by a continuous load. Provided is a method for producing a polypropylene foam filament formed by free fall that constitutes a structure having deformation recovery properties when a load is removed after being deformed by a simple apparatus with high productivity. .

  As a result of intensive studies to solve the above problems, the inventor of the present invention has a polypropylene resin composition (G) containing a polypropylene resin composition (X) and a specific polypropylene resin (Z) in a specific ratio. (Here, component (X) + component (Z) is defined as 100% by weight) 100 parts by weight of foaming agent (Y) is blended at a specific ratio and melt extruded to form a filament by free fall. By this method, the obtained filaments are lightweight, exhibit excellent deformation recovery properties, and exhibit an unprecedented characteristic that the shape can be maintained even at a high temperature of 121 ° C. or higher. As a result, the present invention was completed.

That is, the present invention provides a method for producing the following polypropylene foam filaments.
[1] 1 to 99% by weight of a polypropylene resin composition (X) satisfying the following characteristic (x1) and 1 to 99% by weight of a polypropylene resin (Z) satisfying the following characteristics (z1) to (z2) And 100 parts by weight of a polypropylene resin composition (G) satisfying the following characteristics (g1) to (g2) (wherein component (X) + component (Z) is 100% by weight): A method for producing a polypropylene-based foamed filament, in which (Y) is blended in an amount exceeding 0 part by weight and 5 parts by weight or less, melt-extruded, and forming a filament by free fall.
Polypropylene resin composition (X):
(X1) MFR and MT (melt tension unit: g 230 ° C.) satisfy the following relational expression (a).
Log (MT) <− 0.9 × Log (MFR) +0.7 and MT <15 Formula (a) Polypropylene resin (Z):
(Z1) The melt flow rate (MFR: 230 ° C., 2.16 kg load) is 1.0 to 100 g / 10 min.
(Z2) MFR and MT (melting tension unit g 230 ° C.) satisfy the following relational expression (b).
Log (MT) ≧ −0.9 × Log (MFR) +0.7 or MT ≧ 15 Formula (b)
Polypropylene resin composition (G)
(G1) The melt flow rate (MFR: 230 ° C., 2.16 kg load) is 1.0 to 100 g / 10 minutes.
(G2) Melting peak temperature (Tm) is 121-170 degreeC.
[2] The polypropylene resin composition (X) further satisfies the following characteristics (x2) and (x3), and the following component (A) 1 to 99% by weight and the following component (B) 1 to 99% by weight ( However, the method for producing a polypropylene foam filament according to [1] above, wherein the total of the component (A) and the component (B) is 100% by weight).
(X2) The melt flow rate (MFR: 230 ° C., 2.16 kg load) is 1.0 to 100 g / 10 minutes.
(X3) Melting peak temperature (Tm) is 121-170 degreeC.
Component (A): One or more propylene homopolymers and / or propylene-α-olefin copolymers satisfying the following (a1) to (a2).
(A1) The melting peak temperature (Tm) is 121 to 170 ° C.
(A2) The melt flow rate (MFR: 230 ° C., 2.16 kg load) is 0.1 to 500 g / 10 minutes.
Component (B): At least one propylene-α-olefin copolymer satisfying the following (b1).
(B1) It is composed of 51 to 90% by weight of propylene, 10 to 49% by weight of ethylene and / or an α-olefin having 4 to 10 carbon atoms.
[3] The method for producing a polypropylene-based foamed filament according to [1] or [2], wherein the polypropylene-based foamed filament is a deformation-recoverable heat-resistant foamed filament.
[4] The method for producing a polypropylene-based foamed filament according to any one of [1] to [3], wherein the polypropylene-based foamed filament is used for a deformation-recoverable heat-resistant structure.
[5] The deformation-recoverable heat-resistant structure is formed by twisting a continuous linear body composed of a plurality of strands obtained by extrusion into a three-dimensional random loop so that at least a part of contact portions of the plurality of loops is melted. The method for producing a polypropylene-based foamed filament according to [4] above, which is a network structure having a three-dimensional network structure formed by wearing.

  The present invention is lightweight, has heat resistance capable of maintaining its shape even under high temperature, preferably 121 ° C. or higher, and after being continuously deformed by a continuous load, when the load is removed The present invention provides a method for producing a polypropylene foam filament formed by free-falling that constitutes a structure having deformation recovery properties with a simple apparatus with high productivity.

FIG. 1 is a flow sheet of a polymerization apparatus according to the present invention used in Examples. It is a digital microscope image of the surface of the filament of Example 4 obtained by the manufacturing method of the present invention. It is a digital microscope image of the surface of the filament of the comparative example 2 obtained by the manufacturing method other than this invention.

The method for producing a polypropylene foam filament according to the present invention comprises 1 to 99% by weight of a polypropylene resin composition (X) satisfying the following property (x1) and a polypropylene resin satisfying the following properties (z1) to (z2) ( Z) A polypropylene resin composition (G) containing 1 to 99% by weight and satisfying the following characteristics (g1) to (g2) (wherein component (X) + component (Z) is 100% by weight) This is a method for producing a polypropylene-based foamed filament, in which the foaming agent (Y) is blended by more than 0 part by weight and less than 5 parts by weight with respect to 100 parts by weight, melt-extruded, and free-falling to form a filament.
Polypropylene resin composition (X):
(X1) MFR and MT (melting tension unit g 230 ° C.) satisfy the following relational expression (a).
Log (MT) <− 0.9 × Log (MFR) +0.7 and MT <15 Formula (a)
Polypropylene resin (Z):
(Z1) The melt flow rate (MFR: 230 ° C., 2.16 kg load) is 1.0 to 100 g / 10 min.
(Z2) MFR and MT (melting tension unit g 230 ° C.) satisfy the following relational expression (b).
Log (MT) ≧ −0.9 × Log (MFR) +0.7 or MT ≧ 15 Formula (b)
Polypropylene resin composition (G)
(G1) The melt flow rate (MFR: 230 ° C., 2.16 kg load) is 1.0 to 100 g / 10 minutes.
(G2) Melting peak temperature (Tm) is 121-170 degreeC.

  Hereinafter, the polypropylene resin composition (X), the polypropylene resin (Z), the polypropylene resin composition (G), and the foaming agent (Y) used in the method for producing a polypropylene foam filament of the present invention will be described in detail. To do.

1. Polypropylene resin (Z)
The polypropylene resin (Z) used in the present invention has the characteristics (z1) and (z2) described below.

(1-1) Characteristic (z1): MFR
The melt flow rate (MFR) of the polypropylene resin (Z) used in the present invention needs to be in the range of 1.0 to 100 g / 10 minutes, preferably 1.0 to 20 g / 10 minutes, and more preferably Is 1.0 to 15 g / 10 min, particularly preferably 1.5 to 10 g / 10 min. When the MFR is 1.0 g / 10 min or more, the fluidity is good, and the load on the extruder during foaming line forming can be reduced. On the other hand, when the MFR is 100 g / 10 min or less, the foamed wire It is possible to prevent tearing of the bubble film on the surface at the time of strip forming.

  In the present invention, the MFR of the polypropylene-based resin (Z) is JIS K7210: 1999 “Method for plastic melt-flow rate (MFR) and melt volume flow rate (MVR) test method” in JIS K7210: 1999. Measured according to M (230 ° C., 2.16 kg load), the unit is g / 10 minutes.

(1-2) Characteristic (z2): Melt tension (MT)
Furthermore, the polypropylene resin (Z) used in the present invention has a melt tension (MT) and MFR having the following relational expression (b):
log (MT) ≧ −0.9 × log (MFR) +0.7
Or formula (b)
MT ≧ 15
It is necessary to satisfy one of the expressions described as:

  Here, MT is Capillograph 1B manufactured by Toyo Seiki Seisakusho Co., Ltd. Capillary: 2.0 mm in diameter, 40 mm in length, cylinder diameter: 9.55 mm, cylinder extrusion speed: 20 mm / min, take-off speed: 4. The melt tension when measured under the conditions of 0 m / min and temperature: 230 ° C. is expressed in grams. However, when the MT of the polypropylene resin (A) is extremely high, the resin may break at a take-up speed of 4.0 m / min. In such a case, the take-up speed is lowered and the take-off speed is reduced. Let MT be the tension at the highest possible speed. The measurement conditions and units of MFR are as described above.

This rule is an index for having a sufficient melt tension to prevent the bubble film on the surface of the filament from being broken at the time of forming the foamed filament comprising the polypropylene resin (Z). In general, MT is MFR. Therefore, it is described by the relational expression with MFR.
Thus, the method of defining the melt tension MT with the relational expression with MFR is a normal method for those skilled in the art. For example, JP 2003-25425 discloses the definition of polypropylene having a high melt tension as follows: The following relational expression has been proposed.
log (MS)> − 0.61 × log (MFR) +0.82
(Here, MS is synonymous with MT.)

Japanese Unexamined Patent Application Publication No. 2003-64193 proposes the following relational expression as a definition of polypropylene having a high melt tension.
11.32 × MFR ^−0.7854 ≦ MT

Furthermore, JP-A-2003-94504 proposes the following relational expression as a definition of polypropylene having a high melt tension.
MT ≧ 7.52 × MFR ^−0.576

In the present invention, the polypropylene resin (Z) is represented by the relational formula:
log (MT) ≧ −0.9 × log (MFR) +0.7 or MT ≧ 15
If any of the above is satisfied, it can be said that the resin has a sufficiently high melt tension, and when forming a filament due to free fall, it prevents the bubble film from tearing on the surface of the filament, and does not cause excessive irregularities on the surface of the filament Suitable for forming foamed filaments by free fall.

The polypropylene resin (Z) has the following relational expression:
log (MT) ≧ −0.9 × log (MFR) +0.9 or MT ≧ 15
It is more preferable to satisfy | fill, and it is still more preferable to satisfy | fill the following relational expressions.
log (MT) ≧ −0.9 × log (MFR) +1.1 or MT ≧ 15

  Although it is not necessary to provide the upper limit of MT in particular, if MT is 40 g or less, a take-up speed suitable for measurement in the above-described measurement method is exhibited. In such a case, the resin has excellent extensibility. It is thought that. Therefore, MT is preferably 40 g or less, more preferably 35 g or less, and most preferably 30 g or less.

(1-3) Other Properties of Polypropylene Resin (Z) The melting point of the polypropylene resin (Z) used in the present invention is preferably 110 to 170 ° C, more preferably 115 ° C or more, and still more preferably 120. It is more than 165 degreeC, More preferably, it is 165 degrees C or less, More preferably, it is 160 degrees C or less. When the melting point is 110 ° C. or higher, the cooling and solidification does not become too slow when bubbles are formed, and the bubble film on the surface of the filaments can be prevented from being broken. Moreover, if melting | fusing point is 170 degrees C or less, manufacture is easy.

  The melting point was determined by using differential scanning calorimetry (DSC), once the temperature was raised to 200 ° C. and the thermal history was erased, then the temperature was lowered to 40 ° C. at a temperature lowering rate of 10 ° C./min, and the temperature rising rate was again It is set as the temperature of the endothermic peak top when measured at 10 ° C./min. In addition, about 5 mg-10 mg are normally used for a measurement sample, and heat followability is good in this range.

  The polypropylene resin (Z) used in the present invention only needs to satisfy the above characteristics (z1) and (z2) and may be obtained from a polymer mainly composed of propylene. The polymer mainly composed of propylene refers to a polymer in which 50 mol% or more of the monomer constituting the polymer is propylene, such as propylene homopolymer, propylene-α-olefin random copolymer, propylene-α. -Olefin block copolymers or mixtures thereof are exemplified.

  Moreover, the polypropylene resin (Z) used for this invention has the characteristics that melt tension is high as above-mentioned. As a polypropylene resin having such a feature, one having a branched structure is known. Those having a branched structure are known to cause branching in the polymerization process and those that cause branching by crosslinking using an electron beam or organic peroxide after the polymerization process, both of which are used without particular limitation I can do it. However, since the crosslinked type has a problem that gel is likely to be generated at the time of forming the filament, one that causes branching in the polymerization step is more preferable. Examples of the branching in the polymerization step include those disclosed in Japanese Patent Application Laid-Open No. 2014-132068, but are not limited thereto.

2. Polypropylene resin composition (X)
The polypropylene resin composition (X) satisfies the characteristics (x1) described below.
(2-1) Characteristic (x1): Melt tension (MT)
The polypropylene resin (X) used in the present invention has a melt tension (MT) and MFR having the following relational expression (a):
log (MT) <− 0.9 × log (MFR) +0.7
And formula (a)
MT <15
It is necessary to satisfy.
Here, the measurement conditions and units of MT and MFR are as described above.

  This rule is a characteristic necessary for adjusting the thickness of the filament to a desired value by free fall when the foamed filament comprising the polypropylene resin composition (X) is formed. When the characteristic (x1) is satisfied, the melt tension of the polypropylene resin composition (G) composed of the polypropylene resin composition (X) and the polypropylene resin (Z) does not become excessively high, and the filament caused by free fall At the time of formation, thinning of the filament due to so-called draw-down is likely to occur, and it becomes easy to adjust the thickness of the filament to a desired value.

(2-2) Other characteristics of polypropylene resin composition (X) The polypropylene resin composition (X) preferably further falls within the ranges of the following characteristics (x2) and (x3).

Characteristics (x2): Melt flow rate (MFR: 230 ° C., 2.16 kg load)
The MFR is preferably 1.0 to 100 g / 10 minutes, more preferably 2.0 to 50 g / 10 minutes, still more preferably 5.0 to 30 g / 10 minutes, and particularly preferably 10 to 30 g / 10 minutes. is there.
Here, MFR is measured according to JIS K7210: 1999 method A, condition M (230 ° C., 2.16 kg load).
When the MFR is 1.0 g / 10 min or more, the load during molding is small, and the molding of the filament itself is easy. On the other hand, if the MFR is 100 g / 10 min or less, the molding stability is hardly impaired.

Characteristic (x3): Melting peak temperature (Tm)
Tm is preferably 121 to 170 ° C, more preferably 125 to 170 ° C, still more preferably 130 to 170 ° C, and particularly preferably 135 to 170 ° C.
When the melting peak temperature is 121 ° C. or higher, the polypropylene-based foamed filament obtained by the production method of the present invention is likely to exhibit heat resistance sufficient to maintain its shape at a high temperature, preferably 121 ° C. or higher. . On the other hand, if the melting peak temperature is 170 ° C. or lower, the production is easy.

Further, the flexural modulus of the polypropylene resin composition (X) is preferably 10 to 500 MPa, more preferably 40 to 400 MPa, still more preferably 40 to 200 MPa, and particularly preferably 50 to 150 MPa.
If the flexural modulus is 10 MPa or more, the structure formed from the polypropylene foam filaments obtained by the production method of the present invention has sufficient rigidity to maintain its shape. Moreover, if a bending elastic modulus is 500 Mpa or less, the polypropylene-type foamed filament obtained by the manufacturing method of this invention has a preferable softness | flexibility.
The flexural modulus can be adjusted to a desired value by appropriately selecting the composition of component (A) and component (B), the blending ratio, the blending amount of the following other components, and the like.
In addition to the flexural modulus, examples of the flexibility index include tensile modulus, D hardness, A hardness, and the like. For example, the tensile modulus measured according to JIS K7161 is 10 to 500 MPa, measured according to JIS K7215. A D hardness of about 20 to 60 is also preferable.

(2-3) Form of polypropylene-based resin composition (X) The polypropylene-based resin composition (X) used in the present invention may satisfy the above characteristic (x1). Examples thereof include a propylene homopolymer, a propylene-α-olefin random copolymer, a propylene-α-olefin block copolymer, and a combination of two or more components thereof.
Examples of combinations of two or more components include, for example, 1 to 99% by weight of the following component (A) and 1 to 99% by weight of the following component (B) (however, the total of component (A) and component (B) is 100% by weight) And a polypropylene-based resin composition.

Component (A): One or more propylene homopolymers and / or propylene-α-olefin copolymers satisfying the following (a1) to (a2).
(A1) The melting peak temperature (Tm) is 121 to 170 ° C.
(A2) The melt flow rate (MFR: 230 ° C., 2.16 kg load) is 0.1 to 500 g / 10 minutes.
Component (B): At least one propylene-α-olefin copolymer satisfying the following (b1).
(B1) It is composed of 51 to 90% by weight of propylene, 10 to 49% by weight of ethylene and / or an α-olefin having 4 to 10 carbon atoms.

[Component (A) or (A ′)]
The component (A) or (A ′) used in the present invention satisfies the above characteristics (a1) and (a2).
Each of the above characteristics will be specifically described below. In addition, a component (A ') originates in the polypropylene resin composition (X') demonstrated below.

Characteristic (a1): Melting peak temperature (Tm)
The melting peak temperature (Tm) of the component (A) or (A ′) used in the present invention is 121 to 170 ° C. Preferably they are 125 to 170 degreeC, More preferably, it is 130 to 170 degreeC, More preferably, it is 135 to 170 degreeC.
The component (A) or (A ′) is composed of one or more propylene homopolymers and / or propylene-α-olefin copolymers, and when composed of two or more components, two or more components As a blended product, the melting peak temperature may be 121 ° C to 170 ° C.
Examples of the combination of two or more types of component (A) or (A ′) include a case where the component (A) or (A ′) is composed of two or more types of propylene homopolymers or a case where the component (A) or (A ′) is composed of two or more types of propylene-α-olefin copolymers. Examples include one or more types of propylene homopolymer and propylene-α-olefin copolymer.
When the melting peak temperature is 121 ° C. or higher, the structure obtained from the resin composition of the present invention easily develops heat resistance sufficient to maintain its shape in an environment of 121 ° C. or higher. On the other hand, those having a melting peak temperature of 170 ° C. or less are easily available.

Characteristic (a2): Melt flow rate (MFR: 230 ° C., 2.16 kg load)
The melt flow rate (MFR) of the component (A) or (A ′) used in the present invention is 0.1 to 500 g / 10 minutes, preferably 1.0 to 500 g / 10 minutes, more preferably 5 0.0 to 200 g / 10 minutes, more preferably 5.0 to 100 g / 10 minutes.
The component (A) or (A ′) is composed of one or more propylene homopolymers and / or propylene-α-olefin copolymers, and when composed of two or more components, two or more components As the blended product, the MFR may be 0.1 to 500 g / 10 minutes.
Here, MFR is measured according to JIS K7210: 1999 method A, condition M (230 ° C., 2.16 kg load).
If the MFR is 0.1 g / 10 min or more, it becomes easy to set the MFR of the polypropylene resin composition (X) used in the present invention to 1.0 g / 10 min or more, the load during molding is small, and the wire The forming of the strip itself is easy. On the other hand, if the MFR is 500 g / 10 min or less, it becomes easy to make the MFR of the polypropylene resin composition (X) of the present invention 100 g / 10 min or less, and the molding stability is hardly impaired.

Other characteristics:
The component (A) or (A ′) used in the present invention only needs to satisfy the above characteristics (a1) and (a2). As the component (A) or (A ′), propylene-α-olefin copolymer When using coalescence, component (A) or (A ′) has a propylene content of more than 90% by weight and less than 100% by weight, and an α-olefin content of more than 0% by weight and less than 10% by weight. Is more preferable.
When a propylene-α-olefin copolymer is used as the component (A) or (A ′), the α-olefin is preferably ethylene and / or 1-butene.
The manufacturing method of a component (A) is not specifically limited, It can select suitably from a commercially available propylene homopolymer and a propylene-alpha-olefin copolymer. Specifically, the product name “Novatech PP” manufactured by Nippon Polypro Co., Ltd. and the product name “Wintech” can be mentioned.

[Component (B) or (B ′)]
The component (B) or (B ′) used in the present invention is composed of one or more propylene-α-olefin copolymers that satisfy the above characteristic (b1).
The above characteristics will be specifically described below. In addition, a component (B ') originates in the polypropylene resin composition (X') demonstrated below.

Characteristic (b1): Content of propylene and α-olefin Component (B) or (B ′) used in the present invention is 51 to 90% by weight of propylene, ethylene and / or α-olefin 10 having 4 to 10 carbon atoms. -49% by weight.
If the propylene content is 51% by weight or more, the compatibility with the component (A) or (A ′) is good, and the interface is less likely to be destroyed during deformation. Therefore, the foamed filament obtained by the production method of the present invention It becomes difficult to reduce the deformation recovery property. On the other hand, if the propylene content is 90% by weight or less, the component (B) or (B ′) is less likely to undergo plastic deformation at the time of deformation, so that the deformation recovery property of the foamed filament obtained by the production method of the present invention is improved. It becomes difficult to decrease.
The preferred range of the propylene content is 60% by weight or more and 90% by weight or less, more preferably 70% by weight or more and 90% by weight or less, still more preferably 80% by weight or more and 90% by weight or less, and particularly preferably 83% by weight. % To 90% by weight.

Other characteristics:
The component (B) or (B ′) used in the present invention may satisfy the above characteristic (b1), and the α-olefin is preferably ethylene and / or 1-butene.
The manufacturing method of a component (B) is not specifically limited, It can select suitably from a commercially available propylene-alpha-olefin copolymer. Specifically, ExxonMobil brand name “Vistamaxx”, Dow Chemical brand name “Versify”, Mitsui Chemicals brand name “Toughmer PN”, “Notio SN”, “Toughmer XM”, Sumitomo Chemical The brand name “Tough Selenium” is available.

[Polypropylene resin composition (X) comprising component (A) and component (B)]
The polypropylene-based resin composition (X) composed of the component (A) and the component (B) used in the present invention comprises the above component (A) and / or (A ′) 1 to 99% by weight and the following component (B). And / or (B ′) 1 to 99% by weight is preferable. However, the total of the component (A) and / or (A ′) and the component (B) and / or (B ′) is 100% by weight. In addition, the components (A ′) and (B ′) are derived from the polypropylene resin composition (X ′) described below.
When the component (A) and / or (A ′) is 1% by weight or more, the foamed filament obtained by the production method of the present invention has a heat resistance sufficient to maintain its shape at high temperature, preferably at 121 ° C. or higher. It becomes easy to express sex. On the other hand, when the component (A) and / or (A ′) is 99% by weight or less, plastic deformation hardly occurs at the time of deformation, so that the deformation recovery property of the foamed filament obtained by the production method of the present invention decreases. It becomes difficult.
The more preferable range of the component (A) and / or (A ′) in the polypropylene resin composition (X) and / or (X ′) is 1 to 70% by weight, more preferably 10 to 60% by weight. Particularly preferably, it is 20 to 50% by weight.

[Polypropylene resin composition (X ′)]
In part or all of the polypropylene-based resin composition (X), 1 to 99% by weight of the component (A ′) satisfying the above (a1) and (a2), and the component (B ′) satisfying the above (b1) A polypropylene resin composition (X ′) obtained by sequential polymerization of 1 to 99% by weight (provided that the total amount of (A ′) and (B ′) is 100% by weight) can be used.
The method for producing the polypropylene resin composition (X ′) is not particularly limited, but for example, the method described in JP-A-2005-132799 can be used. Is incorporated herein.
The catalyst for producing the polypropylene resin composition (X ′) is not particularly limited, but the polypropylene resin composition (X ′), the polypropylene resin composition (G), and further the polypropylene resin composition (G) and Since it becomes easy to suppress stickiness of the polypropylene-based foamed filaments produced from the foaming agent (Y), it is preferable to use a metallocene catalyst.
The polypropylene resin composition (X ′) may be appropriately selected from commercially available products, and examples of commercially available products include Nippon Polypro's trade name “Newcon”, trade name “Wellnex” and the like. .

3. Polypropylene resin composition (G)
The polypropylene resin composition (G) used in the present invention comprises 1 to 99% by weight of the polypropylene resin composition (X) and 1 to 99% by weight, preferably 1 to 70% by weight of the polypropylene resin (Z). %, More preferably 2 to 50% by weight, still more preferably 5 to 50% by weight.
When the polypropylene resin composition (X) is 1% by weight or more, that is, when the polypropylene resin (Z) is 99% by weight or less, the polypropylene resin containing the polypropylene resin composition (X) and the polypropylene resin (Z) The degree of freedom in adjusting the physical properties other than the foaming characteristics of the composition (G) is high, and the application is not easily restricted.
When the polypropylene resin composition (X) is 99% by weight or less, that is, when the polypropylene resin (Z) is 1% by weight or more, the polypropylene resin containing the polypropylene resin composition (X) and the polypropylene resin (Z) The composition (G) can have a sufficient melt tension, and it is easy to prevent the bubble film from being broken on the surface of the filament during foamed filament molding.

Unless the effect of this invention is impaired, resin components other than a polypropylene resin (Z) and a polypropylene resin composition (X) can be mix | blended with a polypropylene resin composition (G).
The amount of the other resin component is not particularly limited as long as the effect of the present invention is not hindered, but is usually 100 parts by weight or less with respect to 100 parts by weight of the polypropylene resin composition (X).
Components other than the polypropylene resin (Z) and the polypropylene resin composition (X) are not particularly limited, but ethylene-α-olefin copolymers such as low density polyethylene, linear low density polyethylene, and high density polyethylene. Polyethylene resins represented by ethylene elastomer and ethylene-vinyl acetate copolymer, and polyolefins such as 1-butene homopolymer, 1-butene-propylene copolymer, 1-butene-ethylene copolymer, etc. Can be mentioned. In addition, alicyclic hydrocarbon resins represented by petroleum resins, terpene resins, rosin resins, coumarone indene resins, and hydrogenated derivatives thereof, for example, trade names “Apel” and polyplastics manufactured by Mitsui Chemicals, Inc. A cyclic olefin (co) polymer represented by the trade name “TOPAS” manufactured by the company, the trade name “ZEONOR” or “ZEONEX” manufactured by ZEON Corporation may be added.

  Furthermore, a styrene-based elastomer can be added, and the styrene-based elastomer can be appropriately selected from commercially available ones. For example, as a hydrogenated product of a styrene-butadiene block copolymer, Kraton “Clayton G” from Polymer Japan Co., Ltd., “Tough Tech” from Asahi Kasei Chemicals, Inc., “Septon” from Kuraray Co., Ltd. as a hydrogenated product of styrene-isoprene block copolymer. As a hydrogenated product of styrene-vinylated polyisoprene block copolymer, Kuraray Co., Ltd. under the trade name “Hibler”, and as a hydrogenated product of styrene-butadiene random copolymer, “Dynalon” from JSR Co., Ltd. It is sold under the trade name, and it is selected and used appropriately from these product groups. It may be. Moreover, according to a desired property, it can mix | blend individually or in combination of multiple types.

In addition, additives such as an antioxidant that can be added to the polypropylene resin can be appropriately blended with the polypropylene resin composition (G) used in the present invention as long as the effects of the present invention are not hindered.
Specifically, 2,6-di-t-butyl-p-cresol (BHT), tetrakis [methylene-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] methane (BASF Japan) And trade name “IRGANOX 1010”) and n-octadecyl-3- (4′-hydroxy-3 ′, 5′-di-t-butylphenyl) propionate (trade name “IRGANOX 1076” manufactured by BASF Japan) Phosphite stabilizers represented by bis (2,4-di-t-butylphenyl) pentaerythritol diphosphite and tris (2,4-di-t-butylphenyl) phosphite Agents, higher fatty acid amides such as oleic acid amide and erucic acid amide, higher fatty acid esters and lubricants represented by silicone oil Antistatic agent represented by glycerin ester, sorbitan acid ester, polyethylene glycol ester and the like of fatty acid having 8 to 22 carbon atoms, sorbitol nucleating agent (for example, trade name “Gelol MD” manufactured by Shin Nippon Rika Co., Ltd.), aroma Group phosphates (for example, trade names “NA-21” and “NA-11” manufactured by ADEKA), trade names “Millad” series manufactured by Milliken, trade names “Hyperform” manufactured by Milliken, talc, high-density polyethylene Nucleating agents represented by, such as anti-blocking agents represented by silica, calcium carbonate, talc, etc., molecular weight regulators represented by organic peroxides, crosslinking aids, higher fatty acid metal salts such as calcium stearate, Neutralizers, light stabilizers, UV absorbers, metal inertness typified by hydrotalcite Agents, peroxides, fillers, antibacterial and antifungal agents, fluorescent brighteners, antifogging agents, colorants, pigments, natural oils, synthetic oils, waxes, and organic and inorganic flame retardants depending on the application Etc. may be added, and the blending amount thereof is an appropriate amount.

  Examples of organic flame retardants include brominated flame retardants and phosphorus flame retardants, and it is preferable to use a flame retardant aid such as antimony trioxide as necessary. For example, the blending amount of the brominated flame retardant may be appropriately adjusted according to the desired flame retardant performance, but is 0.1 to 10 parts by weight in 100 parts by weight of the polypropylene resin composition (G) of the present invention. In addition, the flame retardant aid can be exemplified by blending about 1/4 to 1/2 amount of the brominated flame retardant. Furthermore, the blending amount of the phosphorus-based flame retardant may be appropriately adjusted according to the desired flame retardant performance, but about 1 to 30 parts by weight in 100 parts by weight of the polypropylene resin composition (G) of the present invention, Examples of blending can be given.

  As antibacterial and antibacterial agents, the product name “Novalon” manufactured by Toagosei Co., Ltd., the product name “Zeomic” manufactured by Sinanen Zeomic Co., the product name “Bacte Killer” manufactured by Fuji Chemical Co., Ltd., and the product name “Ion Pure” manufactured by Ishizuka Glass Co., Ltd. Examples include silver antibacterial agents, organic antibacterial agents exemplified by the trade name “Royal Guard” manufactured by ADEKA, and the product name “Wasaolo” manufactured by Mitsubishi Chemical Foods, Inc. The use of antibacterial agents is preferred. The blending amount of the antibacterial agent and the antibacterial agent may be appropriately adjusted according to the desired antibacterial and antibacterial performance, but 0.1 to 10 in 100 parts by weight of the polypropylene resin composition (G) of the present invention. It is possible to exemplify blending by about parts by weight.

[Production Method of Polypropylene Resin Composition (G)]
The polypropylene resin composition (G) used in the present invention comprises the above-mentioned polypropylene resin composition (X) and polypropylene resin (Z) and, if necessary, other additives and polymer components in a Henschel mixer (commercial product). Name), V blender, ribbon blender, tumbler blender, and the like. Further, if necessary, it can also be obtained by a method of melt-kneading with a kneader such as a single-screw extruder, a multi-screw extruder, a kneader, a Banbury mixer after the mixing step.
Moreover, each component may be mixed and / or melt-kneaded at the same time, or may be mixed and / or melt-kneaded after making a part of the master batch.

4). Foaming agent (Y)
The foaming agent (Y) used in the present invention is a thermal decomposition type chemical foaming agent, and can be appropriately selected from known ones, and may be any thermal decomposition type chemical foaming agent of an inorganic compound or an organic compound.
Specific examples of the pyrolytic chemical foaming agent include a mixture of sodium bicarbonate and an organic acid such as citric acid, an azo foaming agent such as azodicarbonamide and barium azodicarboxylate, N, N′-dinitrosopentamethylenetetramine, N Nitroso blowing agents such as N, N'-dimethyl-N, N'-dinitrosotephthalamide, sulfohydrazide blowing agents such as p, p'-oxybisbenzenesulfonyl hydrazide, p-toluenesulfonyl semicarbazide, trihydrazinotriazine Etc.

The foaming agent (Y) may be added directly to the polypropylene-based resin composition (G) at the time of foaming line molding, but from the viewpoint of workability, a master batch previously kneaded into a thermoplastic resin is foamed line molding. It is sometimes preferred to blend with the polypropylene resin composition (G).
Examples of such commercially available master batches include, but are not limited to, Hydrocerol series manufactured by Clariant Japan Co., Ltd. and Polyslen series manufactured by Eiwa Kasei Kogyo Co., Ltd.

  The blending amount of the foaming agent is more than 0 part by weight and not more than 5 parts by weight, preferably 0.05, with respect to 100 parts by weight of the resin component in the polypropylene resin composition (G) from the viewpoint of forming a desired cell shape. It is the range of -5 weight part, More preferably, it is 0.5-5.0 weight part, More preferably, it is 0.5-3.0 weight part, Most preferably, it is 1.0-3.0 weight part. If the blending amount of the foaming agent is within the above range, the bubbles on the surface of the foamed filaments are light and difficult to break.

5. Foaming Line Molding The foamed line molding method of the present invention is a method of melt-extruding a mixture of a polypropylene resin composition (G) and a foaming agent (Y) using an extruder or the like, and extruding from a hole provided in a die. It is obtained by free-falling the foamed filaments. As a preferred form, the foamed filaments extruded from the holes provided in the die reach the water surface of the water tank provided under the die by free fall, and are cooled and solidified. Foamed filaments that have reached the water surface of the aquarium by free-falling are drawn at a speed that is substantially the same as the falling speed, or taken at a speed that is slower than the falling speed, and when they reach the water surface, they take a loop-like form. In addition, a method of simultaneously heat-bonding and cooling and solidifying is mentioned. As a more preferable form, the foamed filament is extruded by free-falling from a plurality of holes provided in the die, reaches the water surface of the water tank provided under the die, is taken at a speed slower than the dropping speed, and reaches the water surface. At that time, a loop-like form is taken, and at the same time, heat bonding and cooling solidification are performed, and a three-dimensional network structure composed of a plurality of foamed filaments is taken. Here, pulling at substantially the same speed as the dropping speed means that the speed at the time of drawing the foamed wire is the same as the dropping speed or 50% or less faster than the dropping speed. For example, when the dropping speed is 10 m / min, the take-up speed is 15 m / min or less. Under such a take-up condition, the state of the foamed filament obtained can be regarded as substantially equivalent to that obtained by free fall.

(5-1) Mixing of the polypropylene resin composition (G) and the foaming agent (Y) The mixing method of the polypropylene resin composition (G) and the foaming agent (Y) can be any known method without particular limitation. . For example, the polypropylene resin composition (G) and the foaming agent (Y) are mixed with a Henschel mixer (trade name), V blender, ribbon blender, tumbler blender, etc., or immediately before being fed into the extruder using a quantitative feeder. A predetermined amount may be mixed.
In addition, the polypropylene resin composition (X) constituting the polypropylene resin composition (G), the polypropylene resin (Z), and all or a part of additive components and other resin components blended as necessary At the same time, the foaming agent (Y) can be mixed.

(5-2) Melt extrusion Any known method can be used for the melt extrusion of the mixture of the polypropylene resin composition (G) and the foaming agent (Y).
For example, various extruders such as a known single-screw extruder or twin-screw extruder can be used as the extruder, but the foaming agent (Y) can be reliably decomposed and the resin temperature when leaving the die can be adjusted. From the viewpoint of controlling to a desired temperature, it is preferable to select one having a large ratio (L / D) between the screw length L and the screw diameter D. Specifically, L / D is 20 or more, preferably 24 or more, more preferably 28 or more, and further preferably 32 or more. Alternatively, a tandem type, specifically, two extruders connected in series can be used.
The temperature setting at the time of melt extrusion needs to be a temperature exceeding the melting point of the polypropylene resin composition (G) and the decomposition temperature of the foaming agent (Y). When the temperature control of the extruder can be set in a plurality of sections, it is necessary to set the temperature exceeding the melting point of the polypropylene resin composition (G) and the decomposition temperature of the blowing agent (Y) in at least one section. Specifically, it is set at 5 ° C. or more, preferably 10 ° C. or more higher than the melting point of the polypropylene resin composition (G) in at least one compartment, and 10 ° C. or more, preferably 20 ° C. higher than the decomposition temperature of the foaming agent (Y). It is set at a high temperature of at least 50 ° C, more preferably at least 30 ° C, even more preferably at least 40 ° C, particularly preferably at least 50 ° C. By setting the temperature 5 ° C. or more higher than the melting point of the polypropylene resin composition (G), the components and the foaming agent (Y) constituting the polypropylene resin composition (G) can be easily mixed uniformly. By setting it higher by 10 ° C. or more than the decomposition temperature of (Y), the foaming agent (Y) can be more reliably decomposed. In the other compartments, it is not always necessary to stick to the above temperature setting, but it is preferable to set the temperature higher by 5 ° C. or more than the melting point of the polypropylene resin composition (G).

(5-3) Die and Hole A mixture of the melt-extruded polypropylene resin composition (G) and the foaming agent (Y) is provided in a die (a general term for a mechanism having a structure for releasing the molten resin outside the extruder system). It is extruded from the formed hole (sometimes called a nozzle or an orifice).
There are no particular restrictions on the structure of the die, and any structure including known ones may be used. In order to prevent foaming before the molten resin is released into the atmosphere, the resin pressure is unlikely to drop. Are preferred.
The shape of the hole provided in the die is not particularly limited, and examples thereof include a perfect circle shape, an ellipse shape, a triangle shape, a square shape, a star shape, a Y shape, and the like, and further, solid and hollow shapes. It is done.
The number of holes provided in the die may be one or plural, and may be appropriately selected depending on the use of the obtained filament. In the case where a plurality of holes are provided, for example, a method using one exemplified in JP2013-040437A can be mentioned, but the method is not limited thereto.

(5-4) Formation of foamed filament The mixture of the polypropylene resin composition (G) and the foaming agent (Y) extruded from the holes provided in the die forms a foamed filament by free fall. Foamed filaments formed by free fall can be cooled and solidified in the air, but in order to prevent the bubble film on the filament surface from tearing due to excessive bubble growth, it is dropped into a water tank provided under the die. It is preferable to cool and solidify with a refrigerant such as water. Details of the preferred form are as described above.
Although there is no restriction | limiting in particular in the distance from the hole provided in die | dye to a water tank, It is preferable that it is 15 cm or more. It is easy to adjust the wire diameter of the foamed filament extruded from the hole to a desired value when it is 15 cm or more. Moreover, it is also preferable that the distance from the hole provided in die | dye to a water tank is 100 cm or less. When it is 100 cm or less, cooling and solidification does not take time, and the bubble film on the surface of the filaments is not easily broken due to excessive bubble growth.
The refrigerant for cooling the foamed filaments is preferably water in terms of cost, and the temperature may be lower than the melting point of the resin composition, but is preferably in the range of 10 ° C to 100 ° C.

(5-5) Polypropylene-based foamed filaments The polypropylene-based foamed filaments obtained by the production method of the present invention are lightweight, excellent in deformation recovery at high temperatures, and at high temperatures, preferably at an environment of 121 ° C. or higher. However, it has heat resistance that can maintain its shape.
The polypropylene foam filament obtained by the production method of the present invention preferably has a foaming ratio of 1.1 times or more. This is because if the expansion ratio is 1.1 times or more, a weight reduction effect of 10% or more can be expected as compared with non-foamed ones. The upper limit of the expansion ratio is not particularly limited, but is usually within 10 times, preferably within 5 times, and more preferably within 3 times. If the expansion ratio is increased excessively, the bubble film on the surface of the filament is likely to be broken, and it is not preferable to increase the expansion ratio excessively.
The average wire diameter of the foamed filament is preferably 0.1 to 5.0 mm, more preferably 0.3 to 4.0 mm, still more preferably 0.5 to 3.0 mm, and particularly preferably 0.5 to 2.5 mm. It is. When the average wire diameter is in the range of 0.1 to 5.0 mm, the filament has excellent tactile sensation and deformation recovery property.
Here, the average wire diameter means a diameter obtained from a cross-sectional area when it is assumed that the cross section of the filament is a perfect circle. A specific calculation method is as described later.

The foamed filament can be used by forming a structure according to the purpose. There are no particular restrictions on the shape, molding method, and usage of the structure consisting of foamed filaments, but it can be used for applications that require deformation recovery when the load is removed after being continuously deformed by a continuous load. Preferably used.
For example, the case where it applies to uses like a buffer spring, the case where it applies to support bodies, such as a cushion and a mattress, are mentioned.
As an example of a suitable application form, a continuous linear body composed of a plurality of strands obtained by extrusion is twisted into a three-dimensional random loop, and at least a part of contact portions of the plurality of loops is fused. And a network structure having a three-dimensional network structure.

The net-like structure may be used, for example, as a bedding such as a bed, or a cushioning material for a home, vehicle, ship or aircraft seat. In these applications, a person lies down or sits down for a long time. Therefore, it is continuously deformed by the continued load. In addition, after removing the load, in order to use it again as a cushioning material, it is necessary to recover the deformation to such an extent that there is no practical problem.
Furthermore, since there are cases where a load is applied at a high temperature (for example, 70 ° C.) in an automobile cushion, a cushioning part, a bed cushion with a heating function, etc., a deformation recovery property at a high temperature is also required.
In recent years, hospitals and the like have a need not only to reduce the weight of the cushion itself but also to clean and in some cases sterilize, and have been required to withstand steam sterilization at a high temperature, preferably 121 ° C or higher. It can be said that it is a particularly suitable form as an application to which the polypropylene-based foamed filament manufactured by the manufacturing method of the invention is applied.

  In addition to the above, for example, the production of the present invention is also applied to civilian material use, building material use, industrial material use, etc., which are buried or laid on the ground for the purpose of improving drainage, improving air permeability and retaining earth and sand. The structure using the foamed filament obtained by the method can be suitably used. In these applications, for example, it is assumed that the outdoor environment is in a high temperature environment during the daytime and is deformed by the load of a person, vehicle, animal, etc., but the foam obtained by the production method of the present invention is used. By using a structure using a filament, not only is it lightweight, it is expected to be easily restored to its original shape. Furthermore, since it has excellent shape retention at high temperatures, preferably at 121 ° C. or higher, it can be applied to cleaning with a steam cleaner.

As a method for producing the network structure, a known method may be appropriately employed. For example, Japanese Patent Application Laid-Open No. 2013-040437, Japanese Patent Application Laid-Open No. 7-173753, Japanese Patent No. 5549438, and Japanese Patent No. 5559436. Although the method of patent 5454733 is mentioned, it is not limited to these.
In addition, when applied to an application in which a load under high temperature is applied, it is molded at a temperature not higher than a temperature at which the shape of the structure can be maintained, preferably at a temperature not lower than an assumed use condition temperature and not higher than a temperature at which the shape of the structure can be maintained. It is preferable to adjust the state of the structure for about 10 seconds to 1 day since deformation recovery at high temperatures is more likely to be improved.
In the case of the structure obtained by the production method of the present invention, for example, 40 ° C, 50 ° C, 60 ° C, 70 ° C, 80 ° C, 90 ° C, 100 ° C, 110 ° C, 120 ° C, 130 ° C, 140 ° C, 150 ° C. A temperature condition such as 160 ° C. can be exemplified.

Moreover, in the case where the foamed filament is applied to a use similar to a buffer spring, the case where it is applied to a support such as a cushion, and the case where the network structure is applied to a cushion material, The deformed form of the filament that is continuously deformed by the continuous load is a bending deformation.
For example, in the case of the network structure, the seemingly deformed form tends to be seen as a compressive deformation. However, if attention is paid to each filament constituting the network structure, the deformed form is a bending deformation.
Therefore, it is possible to sufficiently analogize the deformation recoverability of the various structures listed in the above example by continuously bending and deforming with the continued load, and then evaluating the deformation recovery when the load is removed. it can.

EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited only to these Examples.
In addition, the physical properties of the polypropylene resin compositions used in Examples and Comparative Examples, their constituent components, and foamed filaments were measured and evaluated according to the following evaluation methods.

[Physical properties of each polypropylene resin]
(1) Melt flow rate (MFR, unit: g / 10 minutes):
Measured in accordance with JIS K7210: 1999, Method A, Condition M (230 ° C., 2.16 kg load).
(2) Melting peak temperature (melting point) (Tm, unit: ° C.):
Using a trade name Q2000 differential scanning calorimeter (DSC) manufactured by TA Instruments Inc., once the temperature was raised to 200 ° C. and the thermal history was erased, the temperature decreased to 10 ° C./min to 40 ° C. The temperature at the top of the endothermic peak when the temperature was lowered and measured again at a heating rate of 10 ° C./min was defined as the melting peak temperature (melting point) (Tm). The measurement sample was 5 mg.
(3) Melt tension MT (unit: grams):
The measurement was performed under the following conditions using a Capillograph manufactured by Toyo Seiki Seisakusho.
・ Capillary: Diameter 2.0mm, length 40mm
・ Cylinder diameter: 9.55mm
・ Cylinder extrusion speed: 20 mm / min ・ Pickup speed: 4.0 m / min ・ Temperature: 230 ° C.
When the MT is extremely high, the resin may break at a take-up speed of 4.0 m / min. In such a case, the take-up speed is lowered and the tension at the highest speed at which the take-up can be taken is MT. And

(4) α-olefin content (unit: wt%)
About the commercially available propylene-alpha-olefin copolymer component (B), the value of the catalog description published by the manufacturer was used.
About component (A ') and (B') in polypropylene resin composition (X '), it measured by the method as described in Unexamined-Japanese-Patent No. 2005-132799.
The components (A ′) and (B ′) correspond to the components (A) and (B) described in JP-A-2005-132979, respectively.
(5) Content of the components (A ′) and (B ′) in the polypropylene resin composition (X ′) (unit: wt%)
The measurement was performed by the method described in JP-A-2005-132979 described above.
The components (A ′) and (B ′) correspond to the components (A) and (B) described in JP-A-2005-132979, respectively.
(6) Flexural modulus (unit: MPa)
The bending elastic modulus of the injection molded product was measured according to JIS K7171.

[Evaluation of foamed filaments]
(7) Foaming ratio (unit: times)
The ratio between the specific gravity of the non-foamed filament and the specific gravity of the obtained foamed filament was defined as the expansion ratio. The specific gravity was determined by an underwater substitution method using an electronic hydrometer MD-300S manufactured by Alpha Mirage Co., Ltd. in a thermostatic chamber adjusted to 23 ° C.
(8) Average wire diameter (unit: mm)
The weight per 10 m of the obtained filament was measured, and the average sectional area (mm ² ) of the filament was calculated by dividing the weight by the filament length (10 m) and the specific gravity. The diameter (mm) when the filament was assumed to be a perfect circle was taken as the average wire diameter. In calculating the average wire diameter, specific gravity was read as density (g / cm ³ ).
(9) Residual strain (unit:%)
(I) Preparation of sample After adjusting the line obtained in Examples and Comparative Examples described later for 48 hours or more under the conditions of 23 ° C and 50% relative humidity, it was further subjected to 80 ° C in a gear oven. The condition was adjusted under conditions of 30 minutes, and the condition was further adjusted for 48 hours or more under conditions of 23 ° C. and 50% relative humidity, and then cut out with sharp scissors to obtain a 140 mm long strip, which was used for the following test. did.
(Ii) Constant displacement bending test Two glass plates having a length of 220 mm, a width of 150 mm, and a thickness of 3 mm were arranged in parallel on a work table with an interval of 100 mm.
A marked line is attached to each 20 mm position from both ends in the length direction of the filament prepared by the above-described method (that is, the distance between marked lines is 100 mm), and is attached to each of the opposite ends of the glass plate and the filament. Lines were installed so that the marked lines matched, and the part where the line and the glass plate overlapped was strictly fixed with cellophane tape. The glass plates on which the filaments were fixed were overlapped through a 50 mm thick spacer so that the surfaces fixed with cellophane tape faced each other and the four corners of the glass plates overlapped.
In this state, the filament is bent so that the gap between the marked lines becomes 50 mm through the space, and the deformation amount of 50% is given to the original length between the marked lines of 100 mm. . In addition, three or one to five kinds of samples were fixed to one set of glass plates.
Then, in the gear oven adjusted to 23 ° C., 50% relative humidity or 40 ° C., or gear oven adjusted to 70 ° C. for 22 hours, the same conditions were applied. Then, the vicinity of the marked line of the filaments attached to the glass plate was cut with sharp scissors or a cutter knife to remove the load.
The cut filament was immediately brought into a constant temperature and humidity chamber of 23 ° C. and 50% relative humidity, and the condition was adjusted for 30 minutes. The cut filaments remained bent to some extent, and the distance between the two ends that were cut in the bent state was measured using a ruler. This distance was set to L1.
Moreover, the bending deformation of the filaments cut on the workbench was extended so as to be parallel to the workbench, and the lengths of the cut ends were measured using a ruler. This length was defined as L0.
Residual strain was determined using the following formula. Residual strain is an index of deformation recovery, and the smaller the value, the better the deformation recovery.
Residual strain = (L0−L1) / L0 × 100 (%)

(10) Heat resistance The 140 mm long filament obtained in the above-mentioned sample preparation section (conditions are 23 ° C., 50% relative humidity) is marked at 20 mm from both ends in the length direction. A line was attached (that is, the distance between marked lines was 100 mm).
One end of the filament was sandwiched between clips and placed in a gear oven adjusted to 100 ° C. or 121 ° C. in a suspended state, and the condition was adjusted for 15 minutes.
After completion of the condition adjustment, it was taken out from the gear oven, immediately brought into a constant temperature and humidity chamber at 23 ° C. and 50% relative humidity, and the length (L2) between the marked lines was immediately measured for the unmelted structure.
Those that contract during the condition adjustment have an L2 of less than 100 mm, and those that sag due to expansion or dead weight have an L2 greater than 100 mm. For those melted by the above-mentioned condition adjustment, there was no heat resistance, and for those not melted, the absolute value of the amount of change (%) from the original distance between the marked lines of 100 mm was used as the heat resistance index, and the value was The smaller the value, the better the heat resistance.
(11) Appearance Using a digital microscope (manufactured by Keyence Co., Ltd .: VHX-900 type), the magnification of the objective lens is 50 times in the reflected light mode from the side surface (direction not in cross section) of the filament obtained by molding. The film was photographed, the presence or absence of tearing of the bubble film on the surface of the filament, and the nonuniformity of the wire diameter were observed, and evaluated according to the following criteria.
No bubble film breakage, uniform wire diameter ○
No bubble film breakage is observed, and a slight non-uniformity of the wire diameter is seen.
Bubble membrane breakage is observed, or markedly non-uniform wire diameter ×

[Components of Polypropylene Resin Composition (X)]
The following propylene-ethylene copolymer (B-1), polypropylene resin (A-1) and the resin obtained in the following production example (X′-1) were used.
(B-1) Product name “Vistamaxx 6202” manufactured by ExxonMobil Co., Ltd. (propylene-ethylene copolymer, MFR 20 g / 10 min, ethylene content 15% by weight)
(A-1) manufactured by Nippon Polypro Co., Ltd., trade name “Novatec PP MA3” (propylene homopolymer, MFR 11 g / 10 min, melting peak temperature 160 ° C.)
(Production Example X′-1)
(I) Preparation of prepolymerized catalyst (chemical treatment of silicate)
To a 10-liter glass separable flask with a stirring blade, 3.75 liters of distilled water was added slowly followed by 2.5 kg of concentrated sulfuric acid (96%). At 50 ° C., 1 kg of montmorillonite (Menzawa Chemical Co., Ltd. Benclay SL; average particle size = 50 μm) was further dispersed, heated to 90 ° C., and maintained at that temperature for 6.5 hours. After cooling to 50 ° C., the slurry was filtered under reduced pressure to recover the cake. 7 liters of distilled water was added to this cake to reslurry it, and then filtered. This washing operation was performed until the pH of the washing liquid (filtrate) exceeded 3.5.
The collected cake was dried at 110 ° C. overnight under a nitrogen atmosphere. The weight after drying was 707 g.

(Drying silicate)
The silicate previously chemically treated was dried with a kiln dryer.
Specifications and drying conditions are as follows.
Rotating cylinder: Cylindrical, inner diameter 50 mm, heating zone 550 mm (electric furnace)
Rotating speed with lifting blade: 2rpm
Tilt angle: 20/520
Silicate supply rate: 2.5 g / min Gas flow rate: Nitrogen 96 liters / hour Countercurrent drying temperature: 200 ° C. (powder temperature)

(Preparation of catalyst)
200 g of the dried silicate obtained above was introduced into a glass reactor equipped with a stirring blade having an internal volume of 3 liters, mixed with 1,160 ml of mixed heptane and further 840 ml of a heptane solution of triethylaluminum (0.60 M), Stir with. After 1 hour, the mixture was washed with mixed heptane to prepare a silicate slurry at 2.0 liters.
Next, 9.6 ml of a heptane solution of triisobutylaluminum (0.71 M / L) was added to the prepared silicate slurry and reacted at 25 ° C. for 1 hour. In parallel, [(r) -dichloro [1,1′-dimethylsilylenebis {2-methyl-4- (4-chlorophenyl) -4H-azurenyl}] zirconium] (the synthesis is disclosed in JP-A-10-226712) 33.1 ml of a heptane solution of triisobutylaluminum (0.71 M) was added to 2,180 mg (3 mmol) and 870 ml of mixed heptane (performed according to the Examples), and the mixture reacted at room temperature for 1 hour was treated with a silicate slurry And stirred for 1 hour.

(Preliminary polymerization)
Subsequently, 2.1 liters of n-heptane was introduced into a stirring autoclave having an internal volume of 10 liters that had been sufficiently replaced with nitrogen, and maintained at 40 ° C. The catalyst slurry prepared previously was introduced there. When the temperature was stabilized at 40 ° C., propylene was supplied at a rate of 100 g / hour to maintain the temperature. After 4 hours, the supply of propylene was stopped and maintained for another 2 hours. After completion of the prepolymerization, the remaining monomer was purged, stirring was stopped and the mixture was allowed to stand for about 10 minutes, and then about 3 liters of the supernatant was decanted.
Subsequently, 9.5 ml of a heptane solution of triisobutylaluminum (0.71 M / L) and 5.6 liters of mixed heptane were added, and the mixture was stirred at 40 ° C. for 30 minutes and allowed to stand for 10 minutes. Removed 6 liters. This operation was further repeated 3 times.
When the component analysis of the final supernatant was performed, the concentration of the organoaluminum component was 1.23 mmol / L, the Zr concentration was 8.6 × 10 ⁻⁶ g / L, and the presence in the supernatant with respect to the charged amount The amount was 0.016%.
Subsequently, 170 ml of a heptane solution of triisobutylaluminum (0.71 M / L) was added, followed by drying at 45 ° C. under reduced pressure.
By this operation, a prepolymerized catalyst containing 2.1 g of polypropylene per 1 g of catalyst was obtained.

(Ii) First Polymerization Step FIG. 1 is a flow sheet of the polymerization apparatus used in the examples.
The amount of bed polymer is controlled in advance in a horizontal polymerization vessel 5 (L / D = 5.2, internal volume: 50 m ³ ) having a stirring blade so that the holding amount is 45 vol%, and the reaction temperature is fed by the catalyst. The upstream part of the reactor was set to 59 ° C., the part from which the powder was extracted was set to 65 ° C., and the temperature in between was set to 63 ° C. While maintaining the reaction pressure of 2.05 MPaG and the stirring speed of 19.5 rpm, the mixed gas was continuously supplied from the pipe 2 so that the gas phase gas composition of the reactor was ethylene / propylene = 0.06, Further, hydrogen gas was continuously supplied so that the hydrogen concentration in the gas phase of the reactor was maintained at a hydrogen / propylene = 0.00064 molar ratio, and the prepolymerized catalyst was 0.12 kg / h (preliminary). Triisobutylaluminum as an organoaluminum compound was supplied from the pipe 1 so as to be constant at 1 kg / h. The molecular weight (MFR) of the produced polymer, that is, the propylene-ethylene random copolymer component (A ′) was adjusted.

The reaction heat was removed by the heat of vaporization of the raw material propylene supplied from the pipe 3. The unreacted gas discharged from the polymerization vessel was cooled and condensed outside the reactor system through the pipe 4 and then refluxed to the polymerization vessel 5. The propylene-ethylene random copolymer component (A ′) obtained by the main polymerization is intermittently withdrawn from the polymerization vessel 5 through the pipe 6 so that the retained level of the polymer is 45 vol% of the reaction volume. The polymerization vessel 11 was supplied to the process. A part of the propylene-ethylene random copolymer component (A ′) was extracted from the gas shut-off tank 7 and used as a sample for analysis.
When the propylene-ethylene random copolymer obtained in the first polymerization step was analyzed, the MFR was 46 g / 10 min and the ethylene content was 1.95 wt%.

(Iii) Second polymerization step A propylene-ethylene random copolymer component (A ′) from the first polymerization step is added to a horizontal polymerization vessel 11 (L / D = 5.2, internal volume: 50 m ³ ) having a stirring blade. Were intermittently supplied from the pipe 8 to carry out copolymerization of propylene and ethylene.
The reaction conditions were a stirring speed of 18 rpm, a reaction temperature of 70 ° C., a reaction pressure of 1.95 MPaG, and the gas composition in the gas phase was adjusted to be ethylene / propylene = 0.38 and hydrogen / ethylene = 0.0012 molar ratio. . Unreacted gas in the reactor is extracted from the unreacted gas extraction pipe 13 and re-supplied from the raw material circulation gas supply pipe 15 through the circulation path. As a polymerization activity inhibitor for adjusting the polymerization amount of the propylene-ethylene random copolymer component (B ′), an oxygen / nitrogen mixed gas (oxygen concentration: 21 wt%) was supplied from the pipe 12 at 10 L / h.

The reaction heat was removed by the heat of vaporization of the raw material propylene supplied from the pipe 14. The unreacted gas discharged from the polymerization vessel was cooled and condensed outside the reactor system through the pipe 13 and refluxed to the polymerization vessel 11.
The polypropylene resin (X′-1) produced in the second polymerization step was intermittently withdrawn from the polymerizer 11 through the pipe 18 so that the retained level of the polymer was 55 vol% of the reaction volume.
At this time, a part of the polymerized polypropylene resin (X′-1) was extracted and used as an analytical sample. At this time, the production amount of the polypropylene resin (X′-1) was 6.0 t / h.
Various analysis results of the polypropylene resin (X′-1) thus obtained are shown in Table 1.

  Tetrakis [methylene-3- (3 ′, 5′-di-t-butyl-4′-hydroxyphenyl) as an additive (antioxidant) was added to 100 parts by weight of the obtained polypropylene resin (X′-1). Propionate] methane (trade name “IRGANOX1010”, manufactured by BASF Japan Ltd.) 0.05 parts by weight, tris (2,4-di-t-butylphenyl) phosphite (trade name) which is a phosphite antioxidant “IRGAFOS 168” (manufactured by BASF Japan Ltd.), 0.05 parts by weight, was charged into a Henschel mixer (trade name), mixed at high speed at 750 rpm for 1 minute at room temperature, and then KZW-25 extruded from Technobel with a screw diameter of 25 mm. In the machine, melt kneaded at a screw speed of 250 rpm, a discharge rate of 15 kg / hr, and an extruder temperature of 200 ° C. The molten resin extruded from (a) is taken out while being cooled and solidified in a cooling water tank, and the strand is cut into a diameter of about 2 mm and a length of about 3 mm using a strand cutter to obtain a polypropylene resin composition (X′-1). Obtained.

Polypropylene resin (Z)
Z-1: Nippon Polypro Co., Ltd. Product name: Waymax MFX3 MFR8g / 10min MT5g

Foaming agent (Y)
Y-1: Eiwa Chemical Industry Co., Ltd. Product name: Polyslen EE275F

Analysis result of (X'-1)

[Reference Example 1]
[Preparation of Polypropylene Resin Composition (X-1)]
A Henschel mixer (trade name) containing 10% by weight of the polypropylene resin (A-1), 40% by weight of the polypropylene resin composition (X′-1) and 50% by weight of the propylene-ethylene copolymer (B-1). Were blended and melt kneaded using a single screw extruder of φ30 mm under the conditions of a cylinder temperature of 200 ° C. and a discharge rate of 6 kg / min to obtain polypropylene-based resin composition (X-1) pellets.
[Forming foamed filaments]
The filament was molded using a molding machine equipped with a die having a nozzle having a diameter of 1 mm at the tip of a single screw extruder (hereinafter referred to as Ex1) having a screw diameter of 30 mm and L / D32.
Ex1 and die temperatures were set as follows.
Temperature setting: C1 / C2 / C3 / C4 / A / D = 240/240/200/170/170/170 ° C.
Here, C1, C2, C3, and C4 indicate the cylinder temperature of the extruder, A indicates the temperature of the adapter that connects the extruder and the die, and D indicates the temperature of the die.

  100% by weight of X-1 pellets is added to Ex1 as a resin composition (G-1), and the resin is placed in a water tank installed so that the water level is 57 cm directly below the die under the condition that the discharge amount is 500 g / h. Was extruded and allowed to fall freely. Using a pulley arranged in a water tank, the filament formed by free-falling is wound up at a speed of 6.6 m / min, which is approximately the same speed as the filament free-falling, and various measurements are performed. A sample for was obtained. When the take-up speed was lowered to 6.4 m / min, the filaments showed a loop-like shape on the water surface of the aquarium, so the free fall speed of the filaments when reaching the water surface of the aquarium was 6.4 m / min. It was confirmed that. The evaluation results of the obtained filaments are summarized in Table 5.

[Reference Example 2]
The filaments were molded in the same manner as in Reference Example 1 except that a resin composition (G-2) obtained by dry blending 90% by weight of X-1 and 10% by weight of Z-1 was added to Ex1. The wire was wound up at a speed of 3.7 m / min, which is approximately the same speed as the free fall of the wire, and samples for various measurements were obtained. When the take-up speed was reduced to 3.5 m / min, the filaments showed a loop-like shape on the water surface of the aquarium, so the free fall speed of the filaments when reaching the water surface of the aquarium was 3.5 m / min. It was confirmed that. The evaluation results of the obtained filaments are summarized in Table 5. The dry blended resin composition (G-2) was melt kneaded at a cylinder temperature of 200 ° C. and a discharge rate of 6 kg / min using a single screw extruder of φ30 mm, and the resulting pellets were analyzed. did. The results are shown in Table 4.

[Reference Example 3]
Ex1 and die temperatures were set as follows.
Temperature setting: C1 / C2 / C3 / C4 / A / D = 240/240/200/170/170/170 ° C.
100% by weight of X-1 pellets is used as a resin composition (G-1), and 100 parts by weight of the resin composition (G-1) is dry blended with 2 parts by weight of a foaming agent (Y). , Under conditions where the discharge amount is 500 g / h, the resin is extruded into a water tank installed so that the water surface is located 10 cm directly below the die, and the free fall speed of the line using a pulley with the line arranged in the water tank The filament was wound up at a sufficiently faster speed of 13.4 m / min to obtain samples for various measurements. When the take-up speed was reduced to 1.4 m / min, the filaments showed a loop-like shape on the water surface of the aquarium, so the free fall speed of the filaments when reaching the water surface of the aquarium was 1.4 m / min. It was confirmed that. The evaluation results of the obtained filaments are summarized in Table 5.

[Example 1]
Ex1 is obtained by dry blending 2 parts by weight of a foaming agent (Y) with respect to 100 parts by weight of a resin composition (G-2) obtained by dry blending 90% by weight of X-1 and 10% by weight of Z-1. The filaments were molded in the same manner as in Reference Example 2 except that they were added to the above. The wire was wound up at a speed of approximately 3.9 m / min, which is a speed approximately equal to the speed at which the wire freely dropped, and samples for various measurements were obtained. When the take-up speed was reduced to 3.7 m / min, the filaments showed a loop-like shape on the water surface of the aquarium, so the free fall speed of the filaments when reaching the water surface of the aquarium was 3.7 m / min. It was confirmed that. The evaluation results of the obtained filaments are summarized in Table 5.

[Example 2]
Strips were formed in the same manner as in Example 1 except that Ex1 and the die temperature were set as follows.
C1 / C2 / C3 / C4 / A / D = 240/240/200/180/180/180 ° C.
The wire was wound up at a speed of 4.0 m / min, which is approximately the same speed as the speed at which the wire freely dropped, and samples for various measurements were obtained. When the take-up speed was reduced to 3.8 m / min, the filaments showed a loop-like shape on the water surface of the aquarium, so the free fall speed of the filaments when reaching the water surface of the aquarium was 3.8 m / min. It was confirmed that. The evaluation results of the obtained filaments are summarized in Table 5.

[Example 3]
Strips were formed in the same manner as in Example 1 except that Ex1 and the die temperature were set as follows.
C1 / C2 / C3 / C4 / A / D = 240/240/200/200/200/200 ° C.
The wire was wound up at a speed of 5.0 m / min, which is approximately the same speed as the free fall of the wire, and samples for various measurements were obtained. When the take-up speed was reduced to 4.8 m / min, the filaments showed a loop-like shape on the water surface of the aquarium, so the free fall speed of the filaments when reaching the water surface of the aquarium was 4.8 m / min It was confirmed that. The evaluation results of the obtained filaments are summarized in Table 5.

[Example 4]
Strips were formed in the same manner as in Example 1 except that Ex1 and the die temperature were set as follows.
C1 / C2 / C3 / C4 / A / D = 240/240/220/220/220/220 ° C.
The wire was wound up at a speed of 6.3 m / min, which is approximately the same speed as the free fall of the wire, and samples for various measurements were obtained. When the take-up speed was reduced to 6.1 m / min, the filaments showed a loop-like shape on the water surface of the aquarium, so the free fall speed of the filaments when reaching the water surface of the aquarium was 6.1 m / min. It was confirmed that. The evaluation results of the obtained filaments are summarized in Table 5.

[Example 5]
Ex1 is obtained by dry blending 2 parts by weight of a foaming agent (Y) with respect to 100 parts by weight of a resin composition (G-3) obtained by dry blending 70% by weight of X-1 and 30% by weight of Z-1. A filament was formed in the same manner as in Example 4 except that it was added to the above. The wire was wound up at a speed of 4.0 m / min, which is approximately the same speed as the speed at which the wire freely dropped, and samples for various measurements were obtained. When the take-up speed was reduced to 3.8 m / min, the filaments showed a loop-like shape on the water surface of the aquarium, so the free fall speed of the filaments when reaching the water surface of the aquarium was 3.8 m / min. It was confirmed that. The evaluation results of the obtained filaments are summarized in Table 5. The dry blended resin composition (G-3) was melt-kneaded at a cylinder temperature of 200 ° C. and a discharge rate of 6 kg / min using a separate single screw extruder of φ30 mm, and the resulting pellets were analyzed. did. The results are shown in Table 4.

[Comparative Example 1]
100% by weight of X-1 pellets was used as a resin composition (G-1), and a mixture obtained by dry blending 2 parts by weight of a foaming agent (Y) with respect to 100 parts by weight of the resin composition (G-1) was added to Ex1. Except for this, the filaments were molded in the same manner as in Reference Example 1. The wire was wound up at a speed of about 7.4 m / min, which is a speed substantially equal to the speed at which the wire freely falls, and samples for various measurements were obtained. When the take-up speed was reduced to 7.2 m / min, the filaments showed a loop-like shape on the water surface of the aquarium, so the free fall speed of the filaments when reaching the water surface of the aquarium was 7.2 m / min. It was confirmed that. The evaluation results of the obtained filaments are summarized in Table 5.

[Comparative Example 2]
The filaments were formed in the same manner as in Comparative Example 1 except that Ex1 and the die temperature were set as follows.
C1 / C2 / C3 / C4 / A / D = 240/240/200/180/180/180 ° C.
The wire was wound up at a speed of approximately 9.9 m / min, which is approximately the same speed as the free fall of the wire, and samples for various measurements were obtained. When the take-up speed was reduced to 9.7 m / min, the filaments showed a loop-like shape on the water surface of the aquarium, so the free fall speed of the filaments when reaching the water surface of the aquarium was 9.7 m / min. It was confirmed that. The evaluation results of the obtained filaments are summarized in Table 5.

[Comparative Example 3]
The filaments were formed in the same manner as in Comparative Example 1 except that Ex1 and the die temperature were set as follows.
C1 / C2 / C3 / C4 / A / D = 240/240/200/200/200/200 ° C.
The wire was wound up at a speed of 13.4 m / min, which is approximately the same speed as the free fall of the wire, and samples for various measurements were obtained. When the take-up speed was reduced to 13.2 m / min, the filaments showed a loop-like shape on the water surface of the aquarium, so the free fall speed of the filaments when reaching the water surface of the aquarium was 13.2 m / min. It was confirmed that. The evaluation results of the obtained filaments are summarized in Table 5.

Analysis result of polypropylene resin composition X

Analysis results of polypropylene resin Z

Analysis result of polypropylene resin composition G

Evaluation result of filament

  As described above, when the production method of the present invention is not used, it is not possible to obtain a foamed filament having a good foamed form by free fall, but by using the production method of the present invention, the foamed form is also obtained by free fall. A structure that is good and lightweight, has heat resistance capable of maintaining its shape even under temperature conditions of 121 ° C. or more, and has deformation recovery properties when the load is removed after being continuously deformed by a continuous load The foamed filament which comprises a body can be obtained with a simple apparatus.

DESCRIPTION OF SYMBOLS 1 Catalyst component supply piping 2 Raw material mixed gas supply piping 3 Raw material propylene supply piping 4 Unreacted gas extraction piping 5 Horizontal polymerizer which has a stirring blade (1st polymerization process)
6 Polymer extraction piping 7 Gas shut-off tank (degassing tank)
8 Polymer supply pipe 9 Condenser 10 Compressor 11 Horizontal polymerizer with stirring blades (second polymerization step)
12 Pipe for adding activity inhibitor 13 Unreacted gas extraction pipe 14 Raw material propylene supply pipe 15 Raw material circulation gas supply pipe 16 Condenser 17 Compressor 18 Polymer extraction pipe

Claims (5)

1 to 99% by weight of a polypropylene resin composition (X) satisfying the following characteristics (x1), 1 to 99% by weight of a polypropylene resin (Z) satisfying the following characteristics (z1) to (z2), and Polypropylene resin composition (G) satisfying characteristics (g1) to (g2) (wherein component (X) + component (Z) is 100% by weight) with respect to 100 parts by weight, foaming agent (Y) Is produced by blending more than 0 parts by weight and 5 parts by weight or less, melt extruding, and forming the filaments by free fall.
Polypropylene resin composition (X):
(X1) MFR and MT (melting tension unit g 230 ° C.) satisfy the following relational expression (a).
Log (MT) <− 0.9 × Log (MFR) +0.7 and MT <15 Formula (a) Polypropylene resin (Z):
(Z1) The melt flow rate (MFR: 230 ° C., 2.16 kg load) is 1.0 to 100 g / 10 min.
(Z2) MFR and MT (melting tension unit g 230 ° C.) satisfy the following relational expression (b).
Log (MT) ≧ −0.9 × Log (MFR) +0.7 or MT ≧ 15 Formula (b)
Polypropylene resin composition (G)
(G1) The melt flow rate (MFR: 230 ° C., 2.16 kg load) is 1.0 to 100 g / 10 minutes.
(G2) Melting peak temperature (Tm) is 121-170 degreeC. The polypropylene resin composition (X) satisfies the following characteristics (x2) and (x3), and the following component (A) 1 to 99% by weight and the following component (B) 1 to 99% by weight (provided that the component ( The manufacturing method of the polypropylene-type foamed filament of Claim 1 which consists of 100 weight% of the sum total of A) and a component (B).
(X2) The melt flow rate (MFR: 230 ° C., 2.16 kg load) is 1.0 to 100 g / 10 minutes.
(X3) Melting peak temperature (Tm) is 121-170 degreeC.
Component (A): One or more propylene homopolymers and / or propylene-α-olefin copolymers satisfying the following (a1) to (a2).
(A1) The melting peak temperature (Tm) is 121 to 170 ° C.
(A2) The melt flow rate (MFR: 230 ° C., 2.16 kg load) is 0.1 to 500 g / 10 minutes.
Component (B): At least one propylene-α-olefin copolymer satisfying the following (b1).
(B1) It is composed of 51 to 90% by weight of propylene, 10 to 49% by weight of ethylene and / or an α-olefin having 4 to 10 carbon atoms.   The method for producing a polypropylene-based foamed filament according to claim 1 or 2, wherein the polypropylene-based foamed filament is a deformation-recoverable heat-resistant foamed filament.   The manufacturing method of the polypropylene-type foamed filament of any one of Claims 1-3 in which the said polypropylene-type foamed filament is used for a deformation | transformation heat-resistant structure.   The deformation-recoverable heat-resistant structure is formed by twisting a continuous linear body composed of a plurality of strands obtained by extrusion molding into a three-dimensional random loop shape, and at least a part of contact portions of the plurality of loops is fused. The method for producing a polypropylene-based foamed filament according to claim 4, which is a network structure having a three-dimensional network structure.

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