JP2009275150A - Polypropylene-based extruded foam and method for producing it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polypropylene-based extruded foam with a high foaming ratio and a method for producing it, which can be produced by using a conventional extrusion foaming device and using nitrogen gas as a foaming agent. <P>SOLUTION: The polypropylene-based extruded foam is obtained by melting and kneading a mixture containing a polypropylene-based resin and nitrogen gas in an extruder, and then, extrusion-foaming the mixture from a die. The polypropylene-based resin satisfies the following requirements A and B, and when extrusion molding is carried out to a low pressure area, a foaming ratio is 3 times or more. The requirement (A) is that the pressure correction value for Bargley correction is 4 MPa or more in the capillary flow test carried out at a measuring temperature of 210°C and a shearing rate of 1,216 s<SP>-1</SP>. The requirement (B) is that the melt flow rate (MFR) is 0.5 g/10min or more. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a polypropylene-based extruded foam and a method for producing the same.

Conventionally, resin foams are frequently used for the interior and exterior of automobiles and the interior and exterior of buildings such as houses. For example, in automobiles, boards and panels using resin foam are used for interiors such as ceilings, doors, and floors facing indoor spaces, or exteriors such as cowls and bodies. Resin foams are also used in housing facilities as building materials such as residential heat insulation boards.
Polystyrene or the like has been used as a material for such a resin foam, but a polypropylene resin is preferred from the viewpoint of heat resistance, chemical resistance, and light weight.

However, since the polypropylene-based resin is inferior in foam moldability as compared with polystyrene, it is difficult to stably supply an extruded foam molded article having a foaming ratio exceeding 3 times in extrusion foam molding. In particular, linear polypropylene was poor in strain hardening of elongational viscosity, and adjacent bubble walls were easily broken in the foam molding process.
In view of this, a material has been developed in which a branched structure is imparted to the molecular chain of polypropylene to develop a high melt tension and to improve foam moldability (see, for example, Patent Document 1).

In addition, by optimizing the molecular weight and quantity ratio of the ultra-high molecular weight component, a polypropylene resin composition was invented that made it difficult to break the cell walls by generating a large extensional viscosity in the high-speed extension flow field of the bubble formation process. (For example, refer to Patent Document 2).
And according to the said polypropylene resin composition, the high foaming whose foaming magnification exceeds 10 times is obtained by the extrusion foaming molding using a supercritical carbon dioxide (for example, patent document 3).

  Furthermore, a foam molding method using a supercritical nitrogen as a foaming agent is disclosed as foam molding using a polypropylene resin (see, for example, Patent Document 4).

Japanese Examined Patent Publication No. 7-45551 JP 2007-119760 A WO2006 / 118160 JP 2005-97389 A

  However, in Patent Document 1, since the polymer having a branched structure is easily broken, the viscoelastic property may be changed in the flow process in extrusion molding. In addition, there is a problem that a polymer having a branched structure is not suitable for recycling. In addition, because of the branched structure, it is effective for improving the drawability of the sheet by increasing the rise of the extension viscosity at a low strain rate, but it is effective for extension deformation under high speed that contributes to the destruction of bubbles. However, good characteristics were not always obtained.

Patent Documents 2 and 3 also suggest the use of nitrogen as a foaming agent, but do not disclose production examples of foams having a foaming ratio of 3 to 20 times using nitrogen.
Furthermore, the foam of Patent Document 4 shows an embodiment in which a foam having a foaming ratio exceeding 3 times is obtained by injection foam molding using a polymer having a branched structure. With respect to, no embodiment is shown. In the injection foam molding, in order to take the process of injecting the molten resin material into the mold, and then moving the mold by a predetermined amount and foaming, the temperature of the mold and until the mold is moved Since the time, the moving speed of the mold and the like can be arbitrarily set, the adjustment of the expansion ratio is relatively easy. However, in extrusion foam molding, the surface after the die exit is a free surface, and it is difficult to control the expansion ratio.

  Further, when the flow path area at the die outlet is reduced, the shear rate of the die wall surface increases, melt fracture is likely to occur, and defective phenomena such as corrugated marks are likely to occur. That is, there exists a problem that the appearance defect of a foam tends to arise.

  An object of the present invention is to provide a polypropylene-based extruded foam that can be produced using a conventional extrusion foaming apparatus and has a relatively high expansion ratio and good surface appearance, and a method for producing the same.

The method for producing a polypropylene-based extruded foam of the present invention comprises a melt-kneading step of melt-kneading a mixture containing a polypropylene-based resin and a foam material in an extruder, and a composition melt-kneaded in the melt-kneading step from a die. An extrusion foaming process for extruding and foaming, wherein the polypropylene resin is used in (A) a capillary flow test under the conditions of a measurement temperature of 210 ° C. and a shear rate of 1216 s ⁻¹ . , The pressure correction value in the Bargley correction is 4 MPa or more, and (B) the melt flow rate (MFR) is 0.5 g / 10 min or more. In the melt-kneading step, nitrogen gas is used as the foaming material in the polypropylene resin. The polypropylene resin is contained in an amount of 0.6% by mass to 5% by mass with respect to the polypropylene resin. Characterized by the condition that the expansion ratio of the emission based extruded foam is more than three times.
Here, the capillary flow test is performed based on the provisions of “flow characteristic test method using capillary rheometer (JIS K 7199)”.
The shear rate here represents an apparent shear rate and can be determined from the diameter and flow rate of the capillary die.
The pressure correction value in the Bargley correction is the sum of pressure losses at the inlet and outlet of the capillary die. It is obtained by setting a plurality of ratios (L / D) of the diameter D of the capillary die and the length L of the capillary die and performing each test. When this pressure correction value is large, it indicates that the inlet pressure loss is large, and the resistance against the reduced flow at the inlet is large. That is, the elongational viscosity is large.

Specifically, for example, the pressure correction value is set by setting three types: a barrel diameter of 9.55 mm, a capillary die diameter of 1.0 mm, a capillary die inflow angle of 90 °, and an L / D of 30, 40, and 50. Can be sought. However, the present invention is not limited to these values, and it is sufficient that the inflow angle is 90 ° or more and the ratio of the diameter of the barrel and the capillary die is 8 or more.
When there is no measurement value at a shear rate of 1216S ^-1, by interpolation using the data of the pressure correction value at a shear rate of the upper and lower two adjacent points of the shear rate, the pressure at a shear rate of 1216S ^-1 A correction value may be calculated.

According to this invention, the polypropylene-based resin, which is a material of the polypropylene-based extruded foam, has a high speed as in bubble formation because the pressure correction value at a high speed of shear rate of 1216 s ⁻¹ is 4 MPa or more. It can be said that the elongational viscosity is high below. That is, the bubbles are difficult to break. Therefore, a polypropylene-based extruded foam having a foaming ratio of 3 times or more can be obtained even with nitrogen gas which is difficult to dissolve in polypropylene-based resin.

  Further, the melt flow rate (MFR) of the polypropylene resin was set to 0.5 g / 10 min or more. When the MFR is less than 0.5 g / 10 min, the fluidity of the resin is poor and the productivity is poor. That is, when the MFR of the resin is 0.5 g / 10 min or more, the production with an extruder can be easily performed. On the other hand, when MFR exceeds 100 g / 10 minutes, it should be noted that the melt tension and viscosity of the polypropylene resin are lowered, and extrusion molding may be difficult. Therefore, the more preferable range of MFR is 1.0 g / 10 min or more and 10.0 g / 10 min or less, and particularly preferably 2.0 g / 10 min or more and 5.0 g / 10 min or less.

  As the polypropylene resin satisfying the above properties, a propylene-based multistage polymer, a propylene homopolymer, a copolymer of propylene and another olefin, or a blend of these is used.

The propylene-based multistage polymer includes the following component (P1) and component (P2).
(P1) A propylene homopolymer component having an intrinsic viscosity [η] of more than 10 dL / g measured in a tetralin solvent at 135 ° C. or a copolymer component of propylene and an α-olefin having 2 to 8 carbon atoms, 5-20 mass% is contained in the polymer.
(P2) Copolymerization of propylene homopolymer component having intrinsic viscosity [η] measured in tetralin solvent at 135 ° C. of 0.5 to 3.0 dL / g or propylene and α-olefin having 2 to 8 carbon atoms The coalescence component is contained in the total polymer in an amount of 80 to 95% by mass.
This propylene-based multistage polymer achieves a high melt tension by adding component (P1), that is, an ultrahigh molecular weight propylene polymer, and a linear propylene-based polymer whose viscoelastic properties are adjusted by adjusting the molecular weight distribution. It is a coalescence.

When the intrinsic viscosity of the component (P1) is 10 dL / g or less, the melt tension becomes insufficient and the desired foaming performance may not be obtained. Moreover, when the mass fraction of a component (P1) is smaller than 5 mass%, melt tension will become inadequate and desired foaming performance may not be obtained. On the other hand, if the mass fraction exceeds 20% by mass, so-called melt fracture may become severe, which may cause rough skin of the foamed molded product, resulting in a decrease in product quality.
As described above, the intrinsic viscosity of component (P1) is preferably more than 10 dL / g, more preferably in the range of 12 to 30 dL / g, and in the range of 13 to 18 dL / g. Is particularly preferred.
Moreover, it is preferable that the mass fraction of a component (P1) exists in the range of 8-18 mass%, and it is especially preferable that it exists in the range of 10-16 mass%.

When the intrinsic viscosity of the component (P2) is less than 0.5 dL / g, the melt tension becomes insufficient and the desired foaming performance may not be obtained. On the other hand, if it exceeds 3.0 dL / g, the viscosity is too high and a suitable foamed molded product may not be formed.
Further, when the mass fraction of the component (P2) is less than 80% by mass, it may be difficult to carry out suitable foam molding. When the mass fraction exceeds 95% by mass, the melt tension becomes low. However, it may be difficult to form a suitable foamed molded article.
The intrinsic viscosity of component (P2) is preferably in the range of 0.5 to 3.0 dL / g as described above, but more preferably in the range of 0.8 to 2.0 dL / g. More preferably, it is in the range of 1.0 to 1.5 dL / g.
Moreover, it is preferable that the mass fraction of a component (P2) exists in the range of 82-92 mass%, and it is especially preferable that it exists in the range of 84-90 mass%.
Furthermore, the intrinsic viscosity of the propylene-based multistage polymer is preferably 1.0 dL / g or more and 6.0 dL / g or less, more preferably 2.0 dL / g or more and 4.0 dL / g or less, and still more preferably 3.0 dL / g. g to 3.5 dL / g. If it is less than 1.0 dL / g, the foamability may be deteriorated, and if it exceeds 6.0 dL / g, molding may be difficult.

In the propylene-based multistage polymer used in the present embodiment, examples of the α-olefin having 2 to 8 carbon atoms constituting the copolymer component include ethylene and 1-butene which are α-olefins other than propylene. . Among these, it is preferable to use ethylene.
In the propylene-based multistage polymer, the relationship between the melt flow rate (MFR) at 230 ° C. and the melt tension (MT) at 230 ° C. preferably satisfies the following formula (I).

    log (MT)> − 1.33 log (MFR) +1.2 (I)

Here, when the relationship between the melt flow rate (MFR) at 230 ° C. and the melt tension (MT) at 230 ° C. does not satisfy the formula (I), it is difficult to perform high-magnification foam molding. It may become. The constant (1.2) is preferably 1.3 or more, and particularly preferably 1.4 or more.
In addition, what is necessary is just to make it contain 5-20 mass% of components (P1) so that a propylene type multistage polymer may have the relationship of above-mentioned Formula (I).

  In addition, the propylene-based multistage polymer has a storage elastic modulus slope on a high frequency side as a certain amount or more as dynamic viscoelasticity in a molten state (relation between angular frequency ω and storage elastic modulus G ′). Specifically, specifically, the storage elastic modulus G ′ (10) when the angular frequency is 10 rad / s (radians / second) and the storage elastic modulus G ′ (1) when the angular frequency is 1 rad / s. G ′ (10) / G ′ (1) is preferably 2.0 or more, and particularly preferably 2.5 or more. If this ratio G ′ (10) / G ′ (1) is smaller than 2.0, the stability when an external change such as stretching is applied to the foamed molded product may be lowered.

  Similarly, the propylene-based multistage polymer preferably has a storage elastic modulus slope on the low frequency side as a dynamic viscoelasticity in a molten state having a certain amount or less, specifically, an angular frequency. Is the ratio of the storage elastic modulus G ′ (0.1) when the angular frequency is 0.1 rad / s and the storage elastic modulus G ′ (0.01) when the angular frequency is 0.01 rad / s. 0.1) / G ′ (0.01) is preferably 6.0 or less, and particularly preferably 4.0 or less. When the ratio G ′ (0.1) / G ′ (0.01) exceeds 6.0, it may be difficult to increase the expansion ratio of the foamed molded product at a low shear rate.

  Such a propylene-based multistage polymer uses an olefin polymerization catalyst composed of the following components (a) and (b) or the following components (a), (b) and (c) in a polymerization process of two or more stages. It can be produced by polymerizing propylene or copolymerizing propylene and an α-olefin having 2 to 8 carbon atoms.

(A) Solid catalyst component obtained by treating titanium trichloride obtained by reducing titanium tetrachloride with an organoaluminum compound with an ether compound and an electron acceptor (b) Organoaluminum compound (c) Cyclic ester compound

  In the solid catalyst component (a), as the organoaluminum compound for reducing titanium tetrachloride, for example, (a1) alkylaluminum dihalide, specifically, methylaluminum dichloride, ethylaluminum dichloride, and n-propylaluminum dichloride, (A2) alkylaluminum sesquihalide, specifically ethylaluminum sesquichloride, (a3) dialkylaluminum halide, specifically, dimethylaluminum chloride, diethylaluminum chloride, di-n-propylaluminum chloride, and diethylaluminum bromide (A4) trialkylaluminum, specifically, trimethylaluminum, triethylaluminum, and triisobutylaluminum, (a5) Alkylaluminum hydride, specifically, may be mentioned diethyl aluminum hydride and the like. Here, “alkyl” is lower alkyl such as methyl, ethyl, propyl, butyl and the like. The “halide” is chloride or bromide, and the former is particularly common.

  The reduction reaction with an organoaluminum compound for obtaining titanium trichloride is usually carried out in the temperature range of −60 to 60 ° C., preferably −30 to 30 ° C. If the temperature in the reduction reaction is lower than −60 ° C., a long time is required for the reduction reaction. On the other hand, if the temperature in the reduction reaction exceeds 60 ° C., excessive reduction may occur in some cases. The reduction reaction is preferably carried out in an inert hydrocarbon solvent such as pentane, heptane, octane and decane.

It is preferable that the titanium trichloride obtained by the reduction reaction of titanium tetrachloride with an organoaluminum compound is further subjected to ether treatment and electron acceptor treatment.
Examples of the ether compound preferably used in the ether treatment of titanium trichloride include, for example, diethyl ether, di-n-propyl ether, di-n-butyl ether, diisoamyl ether, dineopentyl ether, di-n-hexyl ether, Examples include ether compounds in which each hydrocarbon residue is a chain hydrocarbon having 2 to 8 carbon atoms such as di-n-octyl ether, di-2-ethylhexyl ether, methyl-n-butyl ether and ethyl-isobutyl ether. Of these, di-n-butyl ether is particularly preferred.

  As the electron acceptor used in the treatment of titanium trichloride, it is preferable to use halogen compounds of elements of Group III to Group IV and Group VIII of the Periodic Table. Specifically, titanium tetrachloride, Examples include silicon chloride, boron trifluoride, boron trichloride, antimony pentachloride, gallium trichloride, iron trichloride, tellurium dichloride, tin tetrachloride, phosphorus trichloride, phosphorus pentachloride, vanadium tetrachloride and zirconium tetrachloride. be able to.

  When preparing the solid catalyst component (a), the treatment with the ether compound of titanium trichloride and the electron acceptor may be performed using a mixture of both treatment agents, and after the treatment with one treatment agent, the other You may make it perform the process by the processing agent of. Of these, the latter is preferred, and treatment with an electron acceptor is further preferred after ether treatment.

  Prior to treatment with the ether compound and electron acceptor, it is preferred to wash the titanium trichloride with a hydrocarbon. The above-mentioned ether treatment with titanium trichloride is carried out by bringing titanium trichloride into contact with an ether compound, and the treatment of titanium trichloride with an ether compound is carried out by bringing them into contact with each other in the presence of a diluent. Is advantageous. As such a diluent, it is preferable to use an inert hydrocarbon compound such as hexane, heptane, octane, decane, benzene and toluene. In addition, it is preferable that the process temperature in an ether process is 0-100 degreeC. Moreover, it does not restrict | limit especially about processing time, Usually, it is performed in the range of 20 minutes-5 hours.

The amount of the ether compound used is generally 0.05 to 3.0 mol, preferably 0.5 to 1.5 mol per 1 mol of titanium trichloride. If the amount of the ether compound used is less than 0.05 mol, the stereoregularity of the produced polymer cannot be sufficiently improved, which is not preferable. On the other hand, if the amount of the ether compound used exceeds 3.0 mol, the stereoregularity of the produced polymer is improved, but the yield is lowered, which is not preferable. Strictly speaking, titanium trichloride treated with an organoaluminum compound or an ether compound is a composition containing titanium trichloride as a main component.
In addition, as such a solid catalyst component (a), Solvay type titanium trichloride can be suitably used.

What is necessary is just to use the thing similar to the organoaluminum compound mentioned above as an organoaluminum compound (b).
Examples of the cyclic ester compound (c) include γ-lactone, δ-lactone, ε-lactone, etc., and it is preferable to use ε-lactone.
By mixing the above components (a) to (c), an olefin polymerization catalyst for producing the propylene-based multistage polymer used in the present embodiment can be obtained.
In addition, when a propylene-type resin is manufactured with the catalyst which consists of these components (a)-(c), it is known that a polypropylene-type resin with comparatively high isotacticity will be obtained.

In order to obtain the propylene-based multistage polymer used in this embodiment, it is preferable to polymerize propylene or copolymerize propylene and an α-olefin having 2 to 8 carbon atoms in the absence of hydrogen among the two-stage polymerization methods. .
Here, “in the absence of hydrogen” means substantially in the absence of hydrogen, and includes not only the case where no hydrogen is present, but also the case where a very small amount of hydrogen is present (for example, about 10 molppm). . In short, even if hydrogen is contained in such an extent that the intrinsic viscosity [η] of the first-stage propylene-based polymer or propylene-based copolymer measured in a 135 ° C. tetralin solvent does not fall below 10 dL / g, It is included in the meaning of “in the presence”.

By carrying out polymerization of propylene or copolymerization of propylene and α-olefin in the absence of such hydrogen, the components (P1) and (P2) of the ultrahigh molecular weight propylene-based polymer, that is, the propylene-based multistage polymer, are obtained. ) Can be manufactured.
In the absence of hydrogen, the component (P1) has a raw material monomer as a polymerization temperature, preferably 20 to 80 ° C., more preferably 40 to 70 ° C., and a polymerization pressure, generally at normal pressure to 1.47 MPa, preferably 0. It is preferably produced by slurry polymerization under the condition of 39 to 1.18 MPa.

The component (P2) of the propylene-based multistage polymer is preferably produced after the second stage.
The production conditions for the component (P2) are not particularly limited except that the olefin polymerization catalyst described above is used, but the raw material monomer is preferably 20 to 80 ° C., more preferably 60 to 70 ° C. as the polymerization temperature. In general, the polymerization pressure is preferably from normal pressure to 1.47 MPa, preferably from 0.19 to 1.18 MPa, and polymerized under the presence of hydrogen as a molecular weight regulator.

  In the above-described production method, preliminary polymerization may be performed before the main polymerization. When the prepolymerization is carried out, the powder morphology can be maintained well. In general, the prepolymerization is generally a polymerization temperature, preferably 0 to 80 ° C, more preferably 10 to 60 ° C, and a polymerization amount as a solid catalyst. Preferably, 0.001 to 100 g, more preferably 0.1 to 10 g of propylene is polymerized or copolymerized with propylene and an α-olefin having 2 to 8 carbon atoms per 1 g of the component.

Moreover, what blended the propylene homopolymer and the propylene-alpha-olefin copolymer can be used as a polypropylene resin used by this invention.
Examples of the propylene-α-olefin copolymer include a propylene-based block copolymer, which can be produced by the production method described in JP-A No. 2003-286060.
That is, in the presence of an olefin polymerization catalyst composed of the following components [A], [B] and [C], propylene is polymerized or ethylene and propylene are copolymerized to give a polypropylene component having an ethylene content of 0 to 5% by mass. Alternatively, the propylene / ethylene copolymer component is formed in an amount of 1 to 25% by mass of the total polymerization amount, and ethylene and propylene are copolymerized to form the propylene / ethylene copolymer component in an amount of 99 to 75% by mass of the total polymerization amount. The ethylene content is 10 to 80% by mass of the total polymerization amount.

[A] Solid catalyst component obtained by reacting the following compounds (a), (b), (c) or the following compounds (a), (b), (c), (d) (a) Magnesium compound (b) ) Titanium tetrachloride (c) Dialkyl phthalate (the alkyl group represents a straight or branched hydrocarbon group having 3 to 20 carbon atoms)
(D) Silicon tetrachloride [B] Organoaluminum compound [C] Organosilicon compound represented by the following general formula (II) (R ¹ ) (R ² CH ₂ ) Si (OR ³ ) (OR ⁴ ) (II) )
[Wherein, R ¹ is an alicyclic hydrocarbon group having 3 to 12 carbon atoms, R ² is a branched hydrocarbon group having 3 to 20 carbon atoms, and R ³ and R ⁴ are each independent, Represents a hydrocarbon group having 1 to 20 carbon atoms]

The solid catalyst component [A] is a catalyst component containing titanium, magnesium, halogen, and an electron donating compound, and specifically, the compound (a), (b), (c) or the compound (a). , (B), (c), (d).
Although there is no restriction | limiting in particular as a magnesium compound (a), What is represented by the following general formula (III) can be used preferably.
MgR ⁵ R ⁶ (III)
In the above general formula (III), R ⁵ and R ⁶ represent a hydrocarbon group, OR ⁷ (R ⁷ is a hydrocarbon group) or a halogen atom. Here, as the hydrocarbon group of R ⁵ , R ⁶ and R ⁷ , an alkyl group having 1 to 12 carbon atoms, a cycloalkyl group having 3 to 12 carbon atoms, an aryl group having 6 to 20 carbon atoms, and 7 to 20 carbon atoms. Examples of the aralkyl group of R ⁵ and R ⁶ include chlorine, bromine, iodine and fluorine. R ⁵ , R ⁶ and R ⁷ may be the same or different.

Specific examples of the magnesium compound (a) represented by the above general formula (III) include dimethylmagnesium, diethylmagnesium, diisopropylmagnesium, dibutylmagnesium, dihexylmagnesium, dioctylmagnesium, ethylbutylmagnesium, diphenylmagnesium, dicyclohexylmagnesium. Alkyl magnesium and aryl magnesium such as butyl octyl magnesium; alkoxy magnesium such as dimethoxy magnesium, diethoxy magnesium, dipropoxy magnesium, dibutoxy magnesium, dihexyloxy magnesium, dioctoxy magnesium, diphenoxy magnesium, and dicyclohexyloxy magnesium; Allyloxymagnesium; ethylmagnesium chloride, butyl magne Alkyl magnesium halides such as um chloride, hexyl magnesium chloride, isopropyl magnesium chloride, isobutyl magnesium chloride, t-butyl magnesium chloride, phenyl magnesium bromide, benzyl magnesium chloride, ethyl magnesium bromide, butyl magnesium bromide, phenyl magnesium chloride, butyl magnesium iodide, Arylmagnesium halides; butoxymagnesium chloride, cyclohexyloxymagnesium chloride, phenoxymagnesium chloride, ethoxymagnesium bromide, butoxymagnesium bromide, ethoxymagnesium iodide and other alkoxymagnesium halides and allyloxymagnesium halides; magnesium chloride, magnesium bromide Examples thereof include magnesium halides such as nesium and magnesium iodide.
Among these magnesium compounds (a), magnesium halide, alkoxymagnesium, and alkylmagnesium halide can be preferably used. Of these, alkoxymagnesium is particularly preferable.
The magnesium compound (a) can be prepared from metallic magnesium or a compound containing magnesium.

The alkyl group of the dialkyl phthalate (c) is a linear hydrocarbon group or branched hydrocarbon group having 3 to 20 carbon atoms, specifically, an n-propyl group, an isopropyl group, an n-butyl group, Isobutyl group, t-butyl group, n-pentyl group, 1-methylbutyl group, 2-methylbutyl group, 3-methylbutyl group, 1,1-dimethylpropyl group, 1-methylpentyl group, 2-methylpentyl group, 3- Methylpentyl group, 4-methylpentyl group, 1-ethylbutyl group, 2-ethylbutyl group, n-hexyl group, cyclohexyl group, n-heptyl group, n-octyl group, n-nonyl group, 2-methylhexyl group, 3 -Methylhexyl group, 4-methylhexyl group, 2-ethylhexyl group, 3-ethylhexyl group, 4-ethylhexyl group, 2-methylpentyl group, 3-methylpentene Group, 2-ethylpentyl, 3-ethylpentyl group, and the like. Among these alkyl groups, a linear or branched aliphatic hydrocarbon group having 4 or more carbon atoms is preferable.
Specific examples thereof include di-n-butyl phthalate, diisobutyl phthalate, di-n-heptyl phthalate and the like. Of these, di-n-butyl phthalate and diisobutyl phthalate are particularly preferable. In addition, these compounds may be used alone or in combination of two or more.

  To the solid catalyst component [A], silicon tetrachloride (d) can be further added to the compounds (a), (b) and (c). Silicon tetrachloride (d) is used in such a ratio that the molar ratio to the magnesium compound (a) is usually 0.01 or more, preferably 0.10 or more. If this molar ratio is less than 0.01, the catalyst activity and stereoregularity may not be sufficiently improved, or the amount of fine powder in the produced polymer may increase.

  There is no restriction | limiting in particular as a method of making said each compound contact, What is necessary is just to make it contact by a well-known method. Examples thereof include methods described in JP-A-53-43094, JP-A-55-135102, JP-A-55-135103, JP-A-56-18606, and the like. Specifically, (1) a magnesium compound (a) or a complex compound of a magnesium compound (a) and a dialkyl phthalate (c), a dialkyl phthalate (c) and a grinding aid used as desired A method of pulverizing in the presence and reacting with titanium tetrachloride (b), (2) a liquid compound of magnesium compound (a) having no reducing ability and titanium tetrachloride (b), dialkyl phthalate (c) (3) a method in which titanium tetrachloride (b) is reacted with the product obtained in (1) or (2) above, (4) A method in which a dialkyl phthalate (c) and titanium tetrachloride (b) are further reacted with the product obtained in (1) or (2) above; (5) a magnesium compound (a) or a magnesium compound (a); Phthalic acid dial The complex compound with ru (c) is pulverized in the presence of a dialkyl phthalate (c), titanium tetrachloride (b), and a pulverization aid used as desired, and then silicon tetrachloride ( The method etc. which are processed by d) are mentioned.

In addition to these methods, JP-A-56-166205, JP-A-57-63309, JP-A-57-190004, JP-A-57-300407, JP-A-58- The solid catalyst component [A] can also be prepared by the method described in JP 47003A.
The amount of titanium tetrachloride (b) used is usually in the range of 0.5 to 100 mol, preferably 1 to 50 mol, per 1 mol of magnesium in the magnesium compound (a). The amount of dialkyl phthalate (c) used is usually 0.01 to 10 mol, preferably 0.05 to 0.15 mol, per 1 mol of magnesium in the magnesium compound (a). . Furthermore, when adding silicon tetrachloride (d), it is good to make the usage-amount into said ratio.

In the preparation of the solid catalyst component [A], the contact temperature of the compounds (a) to (d) is usually in the range of −20 to 200 ° C., preferably 20 to 150 ° C., and the contact time is usually 1 Minutes to 24 hours, preferably 10 minutes to 6 hours.
At this time, the contact procedure of the compounds (a) to (d) is not particularly limited. For example, each compound may be contacted in the presence of an inert solvent such as a hydrocarbon, or each compound may be previously contacted after being diluted with an inert solvent such as a hydrocarbon. Examples of the inert solvent include aliphatic hydrocarbons such as n-pentane, isopentane, n-hexane, n-heptane, n-octane and isooctane; aromatic hydrocarbons such as benzene, toluene and xylene, or a mixture thereof. Can be mentioned.
Further, in the preparation of the solid catalyst component [A], the titanium tetrachloride (b) is contacted twice or more, and is sufficiently supported on the magnesium compound (a) serving as a catalyst carrier.
The solid catalyst component [A] obtained by the above contact may be washed with an inert solvent such as hydrocarbon. Examples of the inert solvent include the same ones as described above. Further, the solid catalyst component [A] can be stored in a dry state, or can be stored in an inert solvent such as a hydrocarbon.

  As the organoaluminum compound [B], those containing an alkyl group, a halogen atom, a hydrogen atom or an alkoxy group, an aluminoxane and a mixture thereof can be preferably used. Specifically, trialkylaluminum such as trimethylaluminum, triethylaluminum, triisopropylaluminum, triisobutylaluminum, trioctylaluminum; dialkyl such as diethylaluminum monochloride, diisopropylaluminum monochloride, diisobutylaluminum monochloride, dioctylaluminum monochloride Examples include aluminum monochloride; alkylaluminum sesquihalides such as ethylaluminum sesquichloride; chain aluminoxanes such as methylaluminoxane. Among these organoaluminum compounds [B], trialkylaluminum having a lower alkyl group having 1 to 5 carbon atoms, particularly trimethylaluminum, triethylaluminum, tripropylaluminum and triisobutylaluminum are preferable. These organoaluminum compounds [B] may be used alone or in combination of two or more.

The organosilicon compound [C] is represented by the general formula (II).
Specific examples of R ¹ include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, a 1-norbornyl group, a 2-norbornyl group, and the like. A cyclohexyl group is preferred. Examples of R ² include isopropyl group, isobutyl group, sec-butyl group, t-butyl group, neopentyl group and the like, and isopropyl group is particularly preferable. R ³ and R ⁴ are alkyl groups such as methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, hexyl group, octyl group and cyclohexyl group, alkenyl groups such as allyl group, propenyl group and butenyl group. Group, aryl group such as phenyl group, tolyl group and xylyl group, aralkyl group such as phenethyl group and 3-phenylpropyl group. Among these, an alkyl group having 1 to 10 carbon atoms is particularly preferable.

Specific examples of the organosilicon compound [C] include cyclopropylisobutyldimethoxysilane, cyclopropylisopentyldimethoxysilane, cyclopropyl-2-methylbutyldimethoxysilane, cyclopropylneopentyldimethoxysilane, and cyclopropyl-2-methyl. Xyldimethoxysilane, cyclobutylisobutyldimethoxysilane, cyclobutylisopentyldimethoxysilane, cyclobutyl-2-methylbutyldimethoxysilane, cyclobutylneopentyldimethoxysilane, cyclobutyl-2-methylhexyldimethoxysilane, cyclopentylisobutyldimethoxysilane, cyclopentyliso Pentyldimethoxysilane, cyclopentyl-2-methylbutyldimethoxysilane, cyclopentylneopentyldimethoxy Silane, cyclopentyl-2-methylhexyldimethoxysilane, cyclohexylisobutyldimethoxysilane, cyclohexylisopentyldimethoxysilane, cyclohexyl-2-methylbutyldimethoxysilane, cyclohexylneopentyldimethoxysilane, cyclohexyl-2-methylhexyldimethoxysilane, cyclohex Butyl isobutyldimethoxysilane, cycloheptylisopentyldimethoxysilane, cycloheptyl-2-methylbutyldimethoxysilane, cycloheptylneopentyldimethoxysilane, cycloheptyl-2-methylhexyldimethoxysilane, cyclooctylisobutyldimethoxysilane, Cyclooctylisopentyldimethoxysilane, cyclooctyl-2-methylbutyldimethoxysilane, cycl Octylneopentyldimethoxysilane, cyclooctyl-2-methylhexyldimethoxysilane, 1-norbornylisobutyldimethoxysilane, 1-norbornylisopentyldimethoxysilane, 1-norbornyl-2-methylbutyldimethoxysilane, 1-nor Bornyl neopentyldimethoxysilane, 1-norbornyl-2-methylhexyldimethoxysilane, 2-norbornylisobutyldimethoxysilane, 2-norbornylisopentyldimethoxysilane, 2-norbornyl-2-methylbutyldimethoxysilane, 2 -Norbornyl neopentyl dimethoxysilane, 2-norbornyl-2-methylhexyl dimethoxysilane and the like. Of these, cyclopentylisobutyldimethoxysilane and cyclohexylisobutyldimethoxysilane are preferred.
These organosilicon compounds [C] may be used alone or in combination of two or more.

Although there is no restriction | limiting in particular about the usage-amount of said component [A]-[C], Solid catalyst component [A] is 0.0005-1 mmol normally per liter of reaction volume converted into a titanium atom. An amount that is in the range is used.
The organoaluminum compound [B] is used in such an amount that aluminum / titanium (atomic ratio) is usually in the range of 1 to 1,000, preferably 10 to 500.
When this atomic ratio deviates from the above range, the catalytic activity may be insufficient.
The organosilicon compound [C] is such that the organosilicon compound [C] / organometallic compound [B] (molar ratio) is usually in the range of 0.02 to 2.0, preferably 0.05 to 1.0. The correct amount is used. If this molar ratio deviates from the above range, sufficient catalytic activity may not be obtained.

  The propylene-based block copolymer used in the present application is preferably prepared by polymerizing propylene or copolymerizing ethylene and propylene in the first stage using the above-mentioned olefin polymerization catalyst, and the ethylene content is 0 to 5% by mass. Polypropylene component or propylene / ethylene copolymer component, preferably a polypropylene component having an ethylene content of 0% by mass, that is, a propylene homopolymer part is 1 to 25% by mass, preferably 5 to 20% by mass of the total polymerization amount. Then, in the second stage, ethylene and propylene are copolymerized, and the propylene / ethylene copolymer component, that is, the copolymerized portion is 99 to 75% by mass of the total polymerization amount, preferably 95 to 80%. A block copolymer having a mass% of ethylene and an ethylene content of 10 to 80% by mass, preferably 15 to 45% by mass, of the total polymerization amount is produced.

Furthermore, prepolymerization of olefins, preferably α-olefins, can be performed before forming the polypropylene component or propylene / ethylene copolymer component.
In the preliminary polymerization, the catalyst to be used is not particularly limited, but preferably, the above-described olefin polymerization catalyst is used. In this case, as an electron donating component, in addition to the organic compound [C], dicyclopentyldimethoxysilane, cyclopentylethyldimethoxysilane, cyclopentylisopropyldimethoxysilane, cyclopentyltertiarybutyldimethoxysilane, texylcyclopentyldimethoxysilane, texyl Cyclohexyldimethoxysilane, diisopropyldimethoxysilane, diisobutyldimethoxysilane, ditertiarybutyldimethoxysilane, and the like can be used. Of these, dicyclopentyldimethoxysilane is preferred.
The α-olefin is not particularly limited, and specifically, ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-decene, 3-methyl-1 -Pentene, 4-methyl-1-pentene, vinylcyclohexane and the like. Of these, ethylene and propylene are preferred. These α-olefins may be used alone or in combination of two or more.

In the prepolymerization, the α-olefin in the presence of the above components [A], [B] and [C] or other organosilicon compounds is usually used at a temperature in the range of 1 to 100 ° C. and normal pressure to 5 MPa (Gauge). The polymerization may be performed at a pressure of The polymerization time is 1 minute to 10 hours, preferably 10 minutes to 5 hours. The prepolymerization amount is usually 0.1 to 1,000% by mass, preferably 1.0 to 500% by mass, based on the solid catalyst component [A].
Furthermore, the olefin polymer obtained by prepolymerization can be used as a prepolymerization catalyst component. That is, the prepolymerization catalyst component can be used as an olefin polymerization catalyst component to produce a propylene-based block copolymer used in the present invention.

The method for producing a propylene-based block copolymer is not particularly limited with respect to the polymerization type, and can be applied to any of solution polymerization, slurry polymerization, gas phase polymerization, bulk polymerization, and the like. In addition, the polymerization method may be either batch polymerization or continuous polymerization. For example, in the case of producing in a continuous mode, the raw material propylene gas, the molecular weight regulator hydrogen gas and the catalyst are supplied to the former stage polymerization tank, and the propylene homopolymerization part is produced by controlling the polymerization amount by the polymerization time, and then the latter stage. Then, the block is obtained by adding the ethylene propylene gas, ethylene gas, hydrogen gas, and a catalyst as necessary to produce a copolymer part.
In the production of the copolymerization part, ethylene may be used alone, but if necessary, the α-olefin other than ethylene and propylene may be combined.
The conditions for propylene homopolymerization are not particularly limited as long as the above-mentioned polymerization amount can be obtained during polymerization, but the polymerization pressure is usually from atmospheric pressure to 8 MPa (Gauge), preferably from 0.2 to 5 MPa ( Gauge) and the polymerization temperature are usually selected appropriately in the range of 0 to 200 ° C, preferably 30 to 100 ° C. The polymerization time is usually about 5 minutes to 20 hours, preferably about 10 minutes to 10 hours.

  The conditions for copolymerization of ethylene and propylene are not particularly limited as long as the above-described ethylene content and polymerization amount can be obtained at the time of copolymerization, but the polymerization pressure is usually from atmospheric pressure to 8 MPa (Gauge), Preferably it is 0.2-5 Mpa (Gauge), and a polymerization temperature is 0-200 degreeC normally, Preferably it is suitably selected in the range of 20-100 degreeC. The polymerization time is usually about 1 minute to 20 hours, preferably about 1 minute to 10 hours. The ratio of ethylene to propylene to be supplied is 0.01 to 9, preferably 0.05 to 2.3 in terms of a molar ratio of ethylene / propylene.

In this invention, the polypropylene-based extruded foam is formed by extrusion foaming. In particular, a known extrusion foaming apparatus that is generally used can be used.
Specifically, the above-mentioned polypropylene resin and various additives are put into an extrusion foaming apparatus, and after melt-kneading, for example, the low pressure region where the pressure is lower than the pressure in the extruder that becomes a reduced pressure atmosphere or a pressurized atmosphere from atmospheric pressure or atmospheric pressure. To obtain a polypropylene-based extruded foam.

As a means for foaming the polypropylene resin, a foam material is contained. Specifically, physical foaming in which nitrogen gas as a foaming material is injected into a molten resin raw material at the time of molding, chemical foaming in which a chemical foaming agent that generates nitrogen gas as a foaming material is mixed into the resin raw material, etc. may be employed. it can.
In physical foaming, it is easy to set the expansion ratio of the polypropylene-based extruded foam by controlling the amount of nitrogen gas injected, and manufacturability is easy. The nitrogen gas is particularly preferably a supercritical nitrogen gas that has good solubility in the resin raw material.
On the other hand, in chemical foaming, uniform mixing with a resin raw material is easier than physical foaming, and manufacturability is easy.

Examples of the foaming agent used in chemical foaming include azo compounds such as azodicarbonamide and barium azodicarboxylate, nitroso compounds such as N, N′-dinitrosopentamethylenetetramine, and 4,4′-oxybis (benzenesulfonyl). Examples thereof include hydrazine derivatives such as hydrazide.
In addition, you may use what produces | generates not only nitrogen gas but carbon dioxide gas, ammonia etc. like the foaming agent mentioned above.
In addition, when using an inorganic chemical foaming agent, a masterbatch of a polyolefin resin having a concentration of 10% by mass or more and 50% by mass or less is usually from the viewpoint of handleability, storage stability, and dispersibility in polypropylene resin. It is preferable to be used as What is necessary is just to select the addition amount of these inorganic type chemical foaming agents suitably by a kind and the density | concentration in a masterbatch. In general, it is preferably contained in the range of 0.1 to 40 parts by mass, more preferably in the range of 0.5 to 30 parts by mass with respect to 100 parts by mass of the polypropylene resin of the present invention. Can be selected.
These foam materials may be used alone or in combination of two or more.

The amount of the foam material used may be added to 1 g of polypropylene resin so that the amount of gas generated to generate bubbles is 2.2 × 10 ⁻⁴ mol or more and 1.9 × 10 ⁻³ mol or less. preferable. More preferably, it is 6.3 × 10 ⁻⁴ mol or more and 1.9 × 10 ⁻³ mol or less.
Specifically, it is preferably contained in an amount of 0.6% by mass to 5% by mass with respect to the resin raw material in terms of nitrogen gas. More preferably, it is contained at 1.7% by mass or more and 5% by mass or less. If the amount is less than 0.6% by mass, a sufficient function as a foam such as heat insulating properties may not be obtained. Even if the amount is more than 5% by mass, an increase in the expansion ratio according to the content cannot be expected. The resin raw material and nitrogen gas may be separated in the extruder, and the extruded foam may be discontinuous.
Also in chemical foaming, it is preferable to adjust the addition amount of various chemical foaming agents so that the amount of gas generated in the extrusion process is the same as the range of the number of moles.
In the present invention, melt-kneading is performed under the condition that the expansion ratio is 3 times or more. For this reason, while setting it as the quantity of the said foaming agent, what is necessary is just to select suitably the cylinder temperature from 170 degreeC or more and 210 degrees C or less, and extrusion discharge amount from 1 kg / hr or more and 150 kg / hr or less. When supercritical nitrogen gas is used, the pressure in the cylinder may be appropriately selected from 10 MPa to 20 MPa.

And when performing extrusion foaming, additives, such as antioxidant, a neutralizing agent, a flame retardant, can be used as needed. The blending amount of the additive is not particularly limited and can be adjusted as appropriate.
Further, silica, activated carbon, zeolite, silica gel, or fibrous activated carbon may be blended as the powdery or fibrous porous filler.
In addition, as a crystallization nucleating agent, talc, an organic carboxylate, an organic phosphate, or a sorbitol-based nucleating agent may be blended.

The polypropylene-based extruded foam thus obtained is excellent in heat insulation performance because the expansion ratio is 3 times or more.
Further, even when the apparent shear rate is low, a high-foamed body having a foaming ratio of 3 times or more can be produced, so that the clearance at the die exit can be widened. Therefore, a thick extruded foam can be formed and the surface appearance is good.
Furthermore, since the polypropylene resin used in the present invention is excellent in recycling performance and also has good chemical resistance and heat resistance, the polypropylene-based extruded foam also has recycling performance, chemical resistance and heat resistance. Excellent. Moreover, since the polypropylene resin is relatively low cost, the material cost can be reduced.
Thus, the extruded foam having a thickness and excellent in recycling performance, chemical resistance and heat resistance is highly useful as an interior / exterior material in the housing field and the automobile field.
And since a well-known extrusion foaming apparatus can be used as it is, it is not necessary to invest in new equipment. Therefore, since there is no significant change in the manufacturing process, it can be easily implemented. Furthermore, polypropylene-based extruded foam can be used as it is for interior and exterior materials in the field of housing and automobiles, and even when molded by pressing, the bubbles are maintained without being damaged, and the characteristics may be impaired. Since there is no, versatility such as secondary processing can be improved.

In the polypropylene-based extruded foam of the present invention, the expansion ratio is preferably 3 times or more and less than 20 times.
In the present invention, a polypropylene-based extruded foam having a foaming ratio of 3 times or more can be formed because it is used as the above-mentioned polypropylene-based resin material. In order to obtain a foam having an expansion ratio exceeding 20 times, it is necessary to supply a large amount of a foaming agent in a high pressure state, and particularly nitrogen which is less soluble in polypropylene resin than carbon dioxide. When is used as a foaming agent, equipment with higher pressure resistance is required, so the cost of capital investment becomes enormous and there may be a problem in molding stability.

In the polypropylene-based extruded foam of the present invention, the die preferably has a slit or cylindrical flow path at the outlet.
The shape of the polypropylene-based extruded foam is determined by the shape of the die outlet formed on the die. The shape of the die outlet can be any shape such as a circle, a rhombus, a slit, or a cylinder, but among these, the adjustment of the thickness is easy, and from the point that the moldability is excellent, the slit or A cylindrical shape is preferred.
In addition, as a molding method of a foam, it is also possible to use a so-called strip-shaped converging body in which foams extruded from a plurality of die outlets are converged to form one foam. In this case, the shapes of the plurality of die outlets may all be the same, or a plurality of various shapes may be formed on one die.

In the polypropylene-based extruded foam of the present invention, the set temperature of the die is preferably 170 ° C. or higher and 210 ° C. or lower.
If the set temperature of the die is less than 170 ° C, extrusion may be difficult, and if it exceeds 210 ° C, the foaming performance of the resin raw material may be deteriorated.
Therefore, when the set temperature of the die is set to 170 ° C. or higher and 210 ° C. or lower, a polypropylene-based extruded foam having excellent moldability and a high expansion ratio can be obtained.

The polypropylene-based extruded foam of the present invention is preferably extruded to have a thickness of 2 mm to 30 mm.
Conventionally, it has been difficult for a polypropylene-based extruded foam to be highly foamed at a low shear rate, and thus it is necessary to reduce the clearance of the die, and the thickness is small.
According to this invention, the polypropylene-based extruded foam has a thickness of 2 mm or more and 30 mm or less. In addition, when extrusion foaming is performed with a die having a circular die outlet, a thick foam having a diameter of 2 mm or more and 30 mm or less can be obtained.
Therefore, since the polypropylene-based extruded foam is thick or thick, it is very useful for use as an interior / exterior material in the field of housing and automobiles.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
As the extrusion foaming apparatus used in the present invention, a known extrusion foaming apparatus capable of heating the resin raw material in a molten state, kneading while applying an appropriate shear stress, and performing extrusion foaming can be used. Further, as the extruder constituting the extrusion foaming apparatus, either a single screw extruder or a twin screw extruder can be used. Specifically, for example, a tandem extrusion foam molding apparatus connected to two extruders disclosed in JP-A-2004-237729 is exemplified.
In this embodiment, an extrusion foaming apparatus that performs extrusion foaming by physical foaming is used.
FIG. 1 is a schematic view schematically showing an extrusion foaming apparatus according to an embodiment of the present invention.

[Configuration of extrusion foaming equipment]
As shown in FIG. 1, the extrusion foaming apparatus 100 includes a hopper 110 into which a resin raw material is charged, a cylinder 120 as an extruder for melting and kneading the resin raw material, and a gas introduction path 130 for introducing a blowing agent gas into the cylinder 120. And a gear pump 140 for extruding the resin material, a die 150 for molding the resin material, and a cooling mandrel 160.

The hopper 110 also functions as a measuring device, and can also measure at the same time as the resin raw material is charged.
The cylinder 120 is formed in a substantially cylindrical shape, and has a substantially columnar screw 121 having a diameter smaller than the inner diameter of the cylinder 120. The screw 121 has a spiral wing 122 on its outer peripheral surface, and is supported so as to be rotatable about the axis of the screw 121. As the screw 121 rotates inside the cylinder 120, the resin material in the cylinder 120 is melted and kneaded.
The extrusion temperature in the cylinder 120 may be set as appropriate, but for example, it is preferably set to 170 ° C. or higher and 230 ° C. or lower. If the extrusion temperature is less than 170 ° C, extrusion may be difficult, and if it exceeds 230 ° C, foaming performance may be reduced.

The gas introduction path 130 is a flow path connected to the inside of the cylinder 120 and introduces foaming gas, that is, nitrogen gas. By introducing the foaming gas, the resin raw material and the foaming gas are mixed in the cylinder 120.
The gear pump 140 adjusts the flow rate of the mixture of the resin raw material melted and kneaded in the cylinder 120 and the foaming gas, and stably pushes it out to the die 150.

The die 150 is for molding a resin material into a desired shape. In this embodiment, the die shown in FIG. 2 was used.
2A and 2B are schematic views showing the shape of the die according to the present embodiment, in which FIG. 2A is a sectional view of the die, and FIG. 2B is a side view on the die outlet side.
As shown in FIGS. 2A and 2B, the die 150 has a cylindrical flow channel 151 having an annular cross section. The diameter of the ring on the die exit side of the flow channel 151 is preferably 4 mm or more and 1000 mm or less. When the diameter is less than 4 mm, they are integrated when extruded and foamed, and may not be formed into a cylindrical shape. If the diameter exceeds 1000 mm, stable continuous molding becomes difficult.

  In addition, the flow path 151 is formed in series inside the die 150 with the radius of the ring of the die outlet 151 </ b> A being larger than the radius of the ring of the die entrance. Further, the closer the channel 151 is to the die outlet 151A, the smaller the clearance becomes. Assuming that the site where the clearance is minimized is the minimum site S, the clearance at the minimum site S may be set as appropriate, but is preferably 0.2 mm or more. When the thickness is less than 0.2 mm, the surface appearance is deteriorated and it is difficult to obtain a foam having a sufficient thickness. A more preferable range of the clearance is 1 mm or more and 5 mm or less.

The temperature of the die 150 is preferably set to 170 ° C. or higher and 210 ° C. or lower.
If the temperature of the die 150 is less than 170 ° C, extrusion may be difficult, and if it exceeds 210 ° C, the foaming performance of the resin raw material may be deteriorated.

  The mandrel 160 is normally cooled to 10 ° C. or more and 120 ° C. or less by water cooling or the like, and cools the foam extruded from the die 150. In the present embodiment, the mandrel 160 is formed in a substantially cylindrical shape, and the foam extruded from the die 150 in a cylindrical shape comes into contact with the outer peripheral surface 161 thereof. Thereby, a foam is shape | molded and cooled.

[Operation of extrusion foaming equipment]
Next, the operation | movement at the time of implementing extrusion foaming with the extrusion foaming apparatus 100 is demonstrated.
First, the above-mentioned polypropylene resin is put into the hopper 110. Since the hopper 110 also functions as a measuring device, a desired amount of resin can be measured by the hopper 110.
The resin charged into the hopper 110 is supplied to the cylinder 120.
Inside the cylinder 120, the screw 121 rotates about the axis, so that the resin is melted and kneaded by the screw 121. At this time, since nitrogen is introduced as the foaming fluid from the gas introduction path 130, the resin and nitrogen are mixed.
The melt-kneaded resin and nitrogen mixture is pushed out of the cylinder 120 and introduced into the gear pump 140. The flow rate of the resin is adjusted by the gear pump 140 and pushed out to the die 150.

The die 150 is molded by extruding resin along the internal shape.
Then, the resin is extruded from the die 150 and foams simultaneously to form a foam, and is shaped by being brought into contact with the mandrel 160 and cooled. Finally, it is cut by a cutter (not shown) to obtain a sheet-like foam.

[Effects of Embodiment]
As described above, in the present embodiment, the following operational effects can be achieved.
In this embodiment, extrusion foaming is performed by using a nitrogen gas as a foaming agent by a known extrusion foaming apparatus using the above-described polypropylene resin. Thereby, even foaming with nitrogen gas, which has been difficult in the past, can be obtained as a polypropylene-based extruded foam having a foaming ratio of 3 times or more.
Since this polypropylene-based extruded foam uses a polypropylene-based resin as a material, it is excellent in heat resistance, chemical resistance and recycling performance. Further, since the polypropylene resin is low in cost, the cost of the material can be reduced.

In addition, since the polypropylene-based extruded foam is a high foam having a foaming ratio of 3 times or more, it is excellent in heat insulating properties, and is highly useful as an interior / exterior material in the housing and automobile fields.
In this embodiment, a polypropylene-based extruded foam having a foaming ratio of 3 times or more can be produced by a known extrusion foaming apparatus. That is, it can be manufactured by a method similar to the conventional method. Therefore, no new capital investment is required, and since there is no significant change in the manufacturing method, it does not take time and can be manufactured easily.

[Modification of Embodiment]
In the above embodiment, a cylindrical die is used. However, the shape of the die can be a shape according to the purpose, and is not limited thereto.
For example, as shown in FIG. 3, a die 170 having a parallel tubular flow path having a slit-like cross section may be used.

  Further, as shown in FIG. 4, a die 180 having a circular channel having a circular cross section may be used.

  Furthermore, the die may have a conical flow path having a circular cross section, or a parallel tubular flow path having an arbitrary cross section. Thus, a die having a shape according to the purpose can be used.

In the above embodiment, a die having only one cylindrical outlet is used. However, by using a die having a plurality of outlets, a plurality of extruded foams are converged to form a single one. It is also possible to form a so-called strip-shaped bundle of two foams.
In this case, all of the plurality of outlet shapes may be the same shape, or each outlet may have a different shape, for example, a circular shape, a diamond shape, a slit shape, or the like. Moreover, even if it is the same circular shape, it can also be set as several types of circular shapes by changing the magnitude | size of each diameter.

  Moreover, in the said embodiment, although extrusion foaming was performed by physical foaming, it may be based on chemical foaming. In this case, it can be carried out by adding the aforementioned foaming agent or the like.

Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. In addition, this invention is not limited to the content of an Example etc. at all.
<About resin>
In this example, the following two types of polypropylene resin compositions are used.

Resin A: Linear polypropylene Resin B: Branched polypropylene (trade name “PF814”, manufactured by Basell)

[Production Method of Resin A (Propylene Multistage Polymer)]
(1) Preparation of prepolymerization catalyst component:
After thoroughly drying a 5-liter flask equipped with a stirrer with an internal volume of 5 liters and replacing with nitrogen gas, 4 liters of dehydrated heptane and 140 grams of diethylaluminum chloride were added, and a commercially available Solvay type titanium trichloride catalyst ( 20 g of Tosoh Finechem Co., Ltd. was added. While maintaining this at 20 ° C. with stirring, propylene was continuously introduced. After 80 minutes, stirring was stopped to obtain a prepolymerized catalyst component in which 0.8 g of propylene was polymerized per 1 g of titanium trichloride catalyst.

(2) Propylene polymerization:
A stainless steel autoclave with a stirrer with an internal volume of 10 liters was sufficiently dried and replaced with nitrogen gas, 6 liters of dehydrated heptane was added, and nitrogen in the system was replaced with propylene. Thereafter, propylene was introduced while stirring, and the system was stabilized at an internal temperature of 50 ° C. and a total pressure of 0.78 MPa. Then, 200 ml of heptane slurry containing 0.75 g of the prepolymerized catalyst component in terms of solid catalyst was added. The polymerization was started. Propylene was continuously supplied for 1.0 hour for polymerization to obtain a polymer (P1 component). As a result of sampling and analyzing a part thereof, the intrinsic viscosity was 15.4 dL / g. Thereafter, the internal temperature was lowered to 40 ° C. or lower, stirring was weakened, and depressurization was performed.
Again, the internal temperature was 65 ° C., 0.10 MPa of hydrogen was added, and propylene was introduced while stirring. While continuously supplying propylene at a total pressure of 0.78 MPa, polymerization was carried out at 65 ° C. for 4 hours to obtain a polymer (P2 component). At this time, as a result of sampling and analyzing a part of the polymer, the intrinsic viscosity was 3.31 dL / g.
After completion of the polymerization, 50 ml of methanol was added, and the temperature was lowered and the pressure was released. The entire contents were transferred to a filtration tank equipped with a filter, 100 ml of 1-butanol was added, and the mixture was stirred at 85 ° C. for 1 hour, followed by solid-liquid separation. Further, the solid part was washed twice with 6 liters of heptane at 85 ° C. and vacuum-dried to obtain 3.3 kg of a propylene polymer.
As a result, the mass ratio of the polymer components of the polymer (P1) and the polymer (P2) is 15.3: 84.7, and the intrinsic viscosity of the polymer produced in the second stage is 1.13 dL / g.

[Measurement method for physical properties, etc.]
(1) Pressure correction value:
The pressure correction value in the Bargray correction was measured for the above four types of polypropylene resin compositions. The pressure correction value in the Bargley correction can be measured based on a plastic flow characteristic test method using a capillary rheometer defined in “JIS K 7199”.
Specifically, with respect to the above-mentioned resin A, resin B, and resin C, the capillograph type 1C (trade name, manufactured by Toyo Seiki Seisakusho Co., Ltd.) was used, and the respective shear pressure correction values were changed under the following conditions. It was measured. The capillograph type 1C is widely used in related industries. When measurement is performed under the following conditions using this, the shear rate is 1216 s ⁻¹ .

Barrel diameter (inner diameter): 9.55 mm
Capillary diameter D: 1.0 mm
Piston extrusion speed: 100 mm / min
Measurement temperature: 210 ° C
Capillary diameter / length ratio L / D: 30/40/50

(2) Mass fraction of propylene polymer component (P1 component) and propylene polymer component (P2 component):
It calculated | required from the mass balance using the flowmeter integrated value of the propylene supplied continuously at the time of superposition | polymerization.
(3) Intrinsic viscosity [η]:
Measurements were made in a 135 ° C. tetralin solvent.
The intrinsic viscosity [η ₁ ] of the first stage (P1 component) of the propylene-based multistage polymer and the intrinsic viscosity [η _total ] of the entire propylene polymer are sampled and evaluated during the polymerization process. The intrinsic viscosity [η ₂ ] of the stage (P2 component) was calculated by the following formula (IV).

[Η ₂ ] = ([η _total ] × 100− [η ₁ ] × W ₁ ) / W ₂ (IV)
[Η _total ]: The intrinsic viscosity of the entire propylene polymer (dL / g)
[Η ₁ ]: Intrinsic viscosity of P1 component (dL / g)
W ₁ : Mass fraction of P1 component (mass%)
W ₂ : P2 component mass fraction (% by mass)

(4) Melt flow rate (MFR):
In accordance with JIS K7210, the temperature was 230 ° C. and the load was 2.16 kgf (21.2 N).

(5) Foaming ratio:
The density was calculated by dividing the mass of the molded product by the volume determined by the submersion method, and calculated as the expansion ratio by dividing by the density of the unfoamed product.

(6) Continuous formability:
When the amount of nitrogen gas mixed in the resin is too large, the resin and nitrogen gas are not uniformly dispersed in the cylinder of the molding machine, and the nitrogen gas is separated.
When a mixture of resin and nitrogen gas is extruded and foamed from the molding machine in this state, a region where only nitrogen gas is extruded is generated in the middle of the extruded molded product, and the foam is cut off.
Therefore, the presence or absence of foam breakage was confirmed by visual evaluation.

[Evaluation of physical properties of resin]
FIG. 5 shows the result of measuring the pressure correction value of the above resin A and resin B by the above method. FIG. 5 is a graph showing the relationship between the shear rate and the pressure correction value.

As shown in FIG. 5, the resin B, which is a conventional polypropylene resin composition, has a shear rate of 1000 s ⁻¹ or less and the pressure correction value does not change significantly. On the other hand, the resin A has a shear rate of 1000 s ^-1 or less, and the pressure correction value increases rapidly. If the pressure correction value is large in the vicinity of 1000 s ⁻¹ , the elongation viscosity is high and the bubbles are difficult to break. Therefore, it can be said that the resin A has a higher elongation viscosity than the resin B, and a highly foamed foam can be obtained.

Moreover, the measurement result of the pressure correction value (bargley correction) and the melt flow rate (MFR) at a shear rate of 1216 s ⁻¹ for the above two types of resins is shown below.

As shown in Table 2 below, using the resin A and the resin B, an extrusion experiment of a foamed molded article by physical foaming and chemical foaming of nitrogen gas was performed.
(1-1) Physical foaming production equipment and production conditions Molding machine: Mucell injection molding machine manufactured by Nippon Steel Works, product name “J180ELIII-MuCell” (used after removing the mold)
Extrusion time: 12 seconds Extrusion amount: 95g
Cylinder set temperature: 180 ° C
(1-2) Manufacturing method of physical foaming Using a MuCell injection molding machine (used after removing the mold), the above-mentioned resin is mixed with nitrogen gas in a supercritical state at 15 MPa, and the resulting mixture is put into the atmosphere. Foam was obtained by extrusion.
The results are shown in Table 2 below.

(2-1) Chemical foaming production apparatus and production conditions Extruder: Extruder manufactured by Mac International Associates (screw diameter: 45 mm)
Die: Cylindrical die (45 mm in diameter)
Extrusion amount: 10 kg / hr
Extruder: Cylinder set temperature 210 ° C
Chemical foaming agent A: Mainly composed of azodicarbonamide, the amount of gas generated when the temperature was raised under the conditions of 0.500 g of sample, temperature rising rate 2 ° C./min, liquid paraffin 10 ml, 165 ° C., 5 ml, 170 ° C., 80 ml Blowing agent having gas generation characteristics Chemical foaming agent B: Mainly composed of azodicarbonamide, the amount of gas generated when the temperature is raised under the conditions of 0.500 g of sample, heating rate of 2 ° C./min, and liquid paraffin of 10 ml A foaming agent having gas generation characteristics of 5 ml at 175 ° C. and 80 ml at 180 ° C. (2-2) Chemical foaming production method 5 parts by weight of foaming agent (equivalent to 0.7 parts by weight of generated nitrogen) per 100 parts by weight of resin raw material ) And the dry blended mixture is charged into the hopper 110. And it sets to the predetermined | prescribed screw rotation speed of an extruder, fuse | melts a resin raw material within an extruder, is mixed with a foaming agent, and supplies a mixture to die | dye with fixed extrusion amount.
The supplied mixture is extruded vertically downward from the die and foamed in the atmosphere. Then, the molten foam extruded into a cylindrical shape was cut out at the die outlet and allowed to cool naturally in the air, thereby obtaining a cylindrical foam.
The results are shown in Table 2 below.

As shown in Table 2, in Examples 1 to 6 using Resin A, sufficient foaming was obtained regardless of physical foaming or chemical foaming. On the other hand, in the foam of Comparative Example 1 using the resin B, the foaming ratio is less than twice even in physical foaming, and even if the nitrogen gas injected to increase the foaming ratio is increased, the nitrogen gas blows out from the die. As a result, extrusion foaming was not possible.
In addition, in FIG. 6, the situation is shown for the appearance after molding of Example 3 and Comparative Example 1. In the drawing, the left side is Example 3 and the right side is Comparative Example 1, and a 15 cm ruler is placed in front as a comparison.
Moreover, in the comparative example 2 whose nitrogen gas is 0.5 weight% or less, only the foam whose foaming ratio is less than 3 times was obtained. On the other hand, in Comparative Example 3 and Comparative Example 4, although the foaming ratio exceeded 16 times, the foam was broken by the separation of nitrogen gas, and a continuous foam could not be obtained.
The foam electron micrographs obtained in Comparative Example 1 are shown in FIG. 7 (magnification: 50 times) and FIG. 8 (magnification: 180 times), respectively. Moreover, the foam electron micrograph obtained in Example 3 is shown in FIG. 9 (magnification: 50 times) and FIG. 10 (magnification: 180 times), respectively.
As can be seen from these electron micrographs, foaming was sufficient in the examples, but foaming was insufficient in the comparative examples.

  The polypropylene-based extruded foam of the present invention is suitable for interior and exterior materials in, for example, the housing field and the automobile field, because it is excellent in light weight and heat insulation properties while utilizing the properties as a polypropylene resin.

BRIEF DESCRIPTION OF THE DRAWINGS Schematic which shows typically the extrusion foaming apparatus of one Embodiment of this invention. It is a schematic diagram which shows the shape of the die | dye concerning this embodiment, (A) is sectional drawing of die | dye, (B) is a side view by the side of die | dye exit. It is a schematic diagram which shows the modification of die | dye concerning the said embodiment, (A) is sectional drawing of die | dye, (B) is a side view by the side of die | dye exit. It is a schematic diagram which shows the modification of die | dye concerning the said embodiment, (A) is sectional drawing of die | dye, (B) is a side view by the side of die | dye exit. The graph which shows the relationship between a shear rate and a pressure correction value. It is an external view which shows the foaming condition of an Example and a comparative example. It is an electron micrograph (magnification: 50 times) which shows the foaming condition of a comparative example. It is an electron micrograph (magnification: 180 times) which shows the foaming condition of a comparative example. It is an electron micrograph (magnification: 50 times) which shows the foaming condition of an Example. It is an electron micrograph (magnification: 180 times) which shows the foaming condition of an Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 ... Extrusion foaming apparatus 110 ... Hopper 120 ... Cylinder 130 ... Gas introduction path 140 ... Gear pump 150, 170, 180 ... Die 151 ... Flow path 160 ... Mandrel S, T, U ... Minimum part of clearance

Claims (11)

A polypropylene system for performing a melt-kneading step of melt-kneading a mixture containing a polypropylene resin and a foam material in an extruder, and an extrusion foaming step of extrusion-foaming the composition melt-kneaded in the melt-kneading step from a die A method for producing an extruded foam, comprising:
The polypropylene-based resin has a pressure correction value of 4 MPa or more and a (B) melt flow rate (MFR) of 0 in a capillary flow test under the conditions of (A) a measurement temperature of 210 ° C. and a shear rate of 1216 s ^−1. .5 g / 10 min or more,
In the melt-kneading step, the polypropylene resin contains nitrogen gas as the foaming material in an amount of 0.6% by mass to 5% by mass with respect to the polypropylene resin, and the polypropylene-based extruded foam has an expansion ratio of 3%. A method for producing a polypropylene-based extruded foam, characterized in that the condition is at least double. A method for producing a polypropylene-based extruded foam according to claim 1,
The method for producing a polypropylene-based extruded foam, wherein the polypropylene-based resin is linear and has an intrinsic viscosity of 1.0 dL / g or more and 6.0 dL / g or less. A method for producing a polypropylene-based extruded foam according to claim 2,
The intrinsic viscosity of the polypropylene resin is 3.0 dL / g or more and 6.0 dL / g or less. A method for producing a polypropylene-based extruded foam, wherein: A method for producing a polypropylene-based extruded foam according to any one of claims 1 to 3,
The melt flow rate (MFR) of the polypropylene resin is 1.0 g / 10 min or more and 10.0 g / 10 min or less. A method for producing a polypropylene-based extruded foam according to any one of claims 1 to 4,
A method for producing a polypropylene-based extruded foam, wherein the foaming material is a chemical foaming agent that decomposes by heat that is melt-kneaded with the polypropylene-based resin to generate gas. A method for producing a polypropylene-based extruded foam according to any one of claims 1 to 4,
A method for producing a polypropylene-based extruded foam, wherein the nitrogen gas is mixed with the polypropylene-based resin melted in an extruder and dissolved. A method for producing a polypropylene-based extruded foam according to any one of claims 1 to 6,
The expansion ratio is 3 times or more and less than 20 times. A method for producing a polypropylene-based extruded foam according to any one of claims 1 to 7,
A method for producing a polypropylene-based extruded foam, wherein the die has a slit or cylindrical outlet channel. A method for producing a polypropylene-based extruded foam according to any one of claims 1 to 8,
The set temperature of the die is 170 ° C. or higher and 210 ° C. or lower. A method for producing a polypropylene-based extruded foam according to any one of claims 1 to 9,
A method for producing a polypropylene-based extruded foam, which is extruded into a polypropylene-based extruded foam having a thickness of 2 mm to 30 mm. A polypropylene-based extruded foam obtained by extrusion-foaming from a die after a mixture containing a polypropylene-based resin and a foam material is melt-kneaded in an extruder,
The polypropylene-based resin has a pressure correction value of 4 MPa or more and a (B) melt flow rate (MFR) of 0 in a capillary flow test under the conditions of (A) a measurement temperature of 210 ° C. and a shear rate of 1216 s ^−1. .5 g / 10 min or more,
Under the condition that the expansion ratio is 3 times or more, nitrogen gas is contained in the polypropylene resin as the foaming material in an amount of 0.6 mass% or more and 5 mass% or less with respect to the polypropylene resin, and is extruded and foamed. A featured polypropylene-based extruded foam.