Resin composition and extrusion molded article

Abstract

To provide a resin composition in which the occurrence of void and whitening is suppressed and a b value is low, and to provide an extrusion-molded body.SOLUTION: A resin composition is an extrusion-molding resin composition that contains a polyacetal resin, in which the area from the start of crystallization to the top of the crystallization peak when the resin composition is isothermally crystallized at 148°C is in a range of 40 to 50% of the area of the whole crystallization peak.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a resin composition and an extrusion molded article. In particular, it relates to a material mainly composed of a polyacetal resin and used for extrusion molding, and its molded article.

Background Art

[0002] The polyacetal resin is an engineering plastic excellent in the balance of mechanical properties and is also used as a material for cutting such as round bars and plates. However, since the polyacetal resin has high crystallinity and large shrinkage during solidification, when it is melted and then molded, voids and whitening are likely to occur inside the molded article, which is disadvantageous in terms of physical properties and appearance. For example, among round bars, those with a large diameter are generally molded by a so-called solidification extrusion method in which they are solidified in a cooled die. In such a case, voids and whitening are likely to occur in the central part. A resin composition in which the generation of such voids and whitening is suppressed is described in Patent Document 1.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] As described above, Patent Document 1 discloses a resin composition in which the generation of voids and whitening is suppressed. However, with technological innovation, further suppression of the generation of voids and whitening is required, and materials with low yellowness (for example, low b value) are required. An object of the present invention is to solve such problems, and to provide a resin composition in which the generation of voids and whitening is suppressed and the b value is low, and an extrusion molded article.

Means for Solving the Problems

[0005] Based on the above problems, as a result of the study by the present inventors, it was found that the above problems can be solved by adjusting so that the entire resin composition solidifies slowly and uniformly. Specifically, the above problems were solved by the following means. <1>A resin composition for extrusion molding containing a polyacetal resin, wherein the area from the start of crystallization to the peak of crystallization when isothermally crystallized at 148°C of the resin composition is in the range of 40 to 50% of the total area of the crystallization peak. <2>The resin composition according to <1>, wherein the time from the start of crystallization to the crystallization peak when isothermally crystallized at 148°C is 50 seconds or more. <3>The resin composition according to <1>, wherein the time from the start of crystallization to the crystallization peak when isothermally crystallized at 148°C is 60 seconds or more. <4>The resin composition according to any one of <1> to <3>, containing paraffin wax and / or a polyolefin resin. <5>The resin composition according to <4>, wherein the polyolefin resin contains a polyethylene resin. <6>An extruded molded body formed from the resin composition according to any one of <1> to <5>. <7>The extruded molded body according to <6>, wherein the extruded molded body is in the shape of a round bar or a plate. <8>The area of the extrusion cross-section of the extruded molded body is 50 to 2000 cm 2 The extruded molded body according to <6> or <7>.

Advantages of the Invention

[0006] According to the present invention, it is possible to provide a resin composition in which the generation of voids and whitening is suppressed and the b value is low, and an extruded molded body.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2

Embodiments for Carrying Out the Invention

[0008] Hereinafter, embodiments for carrying out the present invention (hereinafter simply referred to as "the present embodiment") will be described in detail. Note that the following present embodiment is an exemplification for explaining the present invention, and the present invention is not limited only to the present embodiment. In this specification, "~" is used in the sense of including the numerical values described before and after it as the lower limit value and the upper limit value. In this specification, various physical property values and characteristic values shall be those at 23°C unless otherwise specified.

[0009] The resin composition of the present embodiment is an extrusion molding resin composition containing a polyacetal resin, and is characterized in that the area from the start of crystallization to the top of the crystallization peak when the resin composition is isothermally crystallized at 148°C is in the range of 40 to 50% of the total area of the crystallization peak. By adopting such a configuration, it becomes possible to provide a resin composition in which the generation of voids and whitening is suppressed and the b value is low.

[0010] As mentioned above, polyacetal resin is also used as a cutting material for round bars, plates, etc. However, when a resin composition containing polyacetal resin is melted, extruded into a rod shape such as a round bar or a plate, and solidified, a region called a white core is formed in the center when the cross section is observed. When light is irradiated and observed, the white core is a part that looks white because the way light is scattered changes. When the present inventor investigated the cause of this white core, it was found that, for example, in the case of an extrusion molded product of a round bar, the size of the crystals of the polyacetal resin is different between the center and the outer periphery. More specifically, it was speculated that the crystal size is large. When the resin composition containing polyacetal resin is solidified, as shown in FIG. 2, it was speculated that the conventional one (corresponding to the comparative example) does not solidify uniformly because the crystallization proceeds quickly. In other words, it was speculated that the polyacetal resin has parts that solidify quickly and parts that solidify slowly, and the crystal size is likely to change. In contrast, in the case of the example shown in FIG. 1, crystallization proceeds slowly, so that the overall crystal size tends to be uniform, and it is assumed that white cores are less likely to form. Under these circumstances, it has been discovered that by controlling the area from the start of crystallization to the top of the crystallization peak during isothermal crystallization at 148°C to be within the range of 40 to 50% of the entire area of ​​the crystallization peak, it is possible to provide a resin composition that suppresses the occurrence of voids and whitening and has a low b value.

[0011] In Fig. 1, 1 is the crystallization start time, 2 is the crystallization end time, and 3 is the crystallization peak top time. The area surrounded by the curve between crystallization start time 1 and crystallization start time 2 and the dotted line connecting crystallization start time 1 and crystallization end time 2 is the area of ​​the entire crystallization peak, and the area from crystallization start time 1 to crystallization peak top time 3 is the area indicated by the diagonal line.

[0012] In this embodiment, when isothermal crystallization is carried out at 148°C, the area from the start of crystallization to the top of the crystallization peak is 40 to 50% of the area of the entire crystallization peak, preferably 40 to 48%, more preferably 40 to 46%, still more preferably 40 to 44%, and even more preferably 40 to 43%. By setting it within such a range, the effects of this embodiment can be more effectively exerted.

[0013] In this embodiment, when isothermal crystallization is carried out at 148°C, the time from the start of crystallization to the top of the crystallization peak is preferably 50 seconds or more, more preferably 60 seconds or more, and still more preferably 65 seconds or more. By setting it to be equal to or higher than the lower limit value, it is possible to make it more difficult to form a white core. Also, the upper limit of the time is, for example, 200 seconds or less, and may be 150 seconds or less. By setting it to be equal to or lower than the upper limit value, it is possible to make it difficult to generate a vacuum void.

[0014] Regarding the above resin composition, there is no particular limitation on the means for making the area from the start of crystallization to the top of the crystallization peak within the range of 40 to 50% of the area of the entire crystallization peak when isothermal crystallization is carried out at 148°C. Means capable of making the crystallization of the resin composition proceed within a desired range can be widely adopted. Specifically, adding additives, in particular, adding paraffin wax and / or polyolefin resin (preferably polyethylene resin), increasing the oxyethylene content of the polyacetal resin, etc. are exemplified.

[0015] Next, the polyacetal resin used in this embodiment will be described. The polyacetal resin is not particularly limited in terms of its type, etc., and may be a homopolymer containing only a divalent oxymethylene group as a structural unit, or a copolymer containing a divalent oxymethylene group and a divalent oxyalkylene group having 2 or more carbon atoms as structural units. Examples of the oxyalkylene group having 2 or more carbon atoms include an oxyethylene group, an oxypropylene group, and an oxybutylene group.

[0016] In the polyacetal resin, the proportion of the oxyalkylene group having 2 or more carbon atoms in the total number of moles of the oxymethylene group and the oxyalkylene group having 2 or more carbon atoms is preferably 0.5 to 10 mol%. The number of carbon atoms in the oxyalkylene group may be 2 or more, preferably 6 or less, and more preferably 4 or less. Furthermore, in the present embodiment, the proportion of the oxyethylene group (oxyethylene content) in the total number of moles of the oxymethylene group and the oxyalkylene group having 2 or more carbon atoms in the polyacetal resin is preferably 1.2 mol% or more, more preferably 1.3 mol% or more, further preferably 1.4 mol% or more, still more preferably 1.5 mol% or more, and may be 1.7 mol% or more. Also, the upper limit of the oxyethylene content is preferably 2.5 mol% or less, more preferably 2.4 mol% or less, further preferably 2.3 mol% or less, and still more preferably 2.2 mol% or less. In particular, by setting the oxyethylene content to 1.7 mol% or more, the crystallization of the polyacetal resin can proceed slowly.

[0017] In general, trioxane is used as the main raw material to produce the above polyacetal resin. In addition, to introduce an oxyalkylene group having 2 to 6 carbon atoms into the polyacetal resin, for example, cyclic formal or cyclic ether can be used. Specific examples of the cyclic formal include 1,3-dioxolane, 1,3-dioxane, 1,3-dioxepane, 1,3-dioxocane, 1,3,5-trioxepane, and 1,3,6-trioxocane. Specific examples of the cyclic ether include ethylene oxide, propylene oxide, and butylene oxide. To introduce an oxyethylene group into the polyacetal resin, for example, 1,3-dioxolane can be used. To introduce an oxypropylene group, 1,3-dioxane can be used. To introduce an oxybutylene group, 1,3-dioxepane can be introduced.

[0018] In the polyacetal resin, it is preferable that the amount of hemiacetal terminal groups, the amount of formyl terminal groups, and the amount of terminal groups unstable to heat, acid, and base are small. Here, the hemiacetal terminal group is represented by -OCH 2 OH, and the formyl terminal group is represented by -CHO.

[0019] The melt volume rate (MVR) value of the above polyacetal resin is preferably 0.5 cm 3 / 10 min or more, more preferably 1.0 cm 3 / 10 min or more, still more preferably 1.5 cm 3 / 10 min or more, and may be 2.0 cm 3 / 10 min or more. By setting such a value, the load on the motor of the extruder can be reduced, and the productivity of the resin composition (for example, pellets) can be improved. Further, the MVR is preferably 4.5 cm 3 / 10 min or less, more preferably 4.0 cm 3 / 10 min or less, and still more preferably 3.5 cm 3 / 10 min or less. By setting it below the above upper limit value, it is possible to make it less likely to generate vacuum voids. The MVR value of the polyacetal resin (A) means the MVR value measured under the conditions of 190°C and a load of 2.16 kg based on ISO1133.

[0020] The content of the polyacetal resin in the resin composition of this embodiment is preferably 80% by mass or more, more preferably 85% by mass or more, still more preferably 90% by mass or more, even more preferably 95% by mass or more, and even more preferably 98% by mass or more. The resin composition of this embodiment may contain only one kind of polyacetal resin or two or more kinds. When two or more kinds are contained, the total amount is preferably within the above range.

[0021] <Other components> The resin composition of this embodiment may contain other components other than the polyacetal resin in order to adjust the crystallization rate or to exhibit other functions. Specifically, examples of other components include nitrogen-containing compounds such as melamine compounds and hydrazine compounds, inorganic fillers, heat stabilizers, antioxidants, weather stabilizers, light stabilizers, ultraviolet absorbers, mold release agents, lubricants, crystal nucleating agents, antistatic agents, antibacterial agents, coloring agents (pigments, dyes), etc. These can be used alone or in combination of two or more. Specifically, in order to adjust the crystallization rate, it is preferable to contain paraffin wax and / or polyolefin resin. As the paraffin wax, paraffin wax 155 manufactured by Nippon Seiro Co., Ltd. is exemplified. As the polyolefin resin, polyethylene resin is exemplified. When the resin composition of the present embodiment contains paraffin wax and / or polyolefin resin, its content is preferably 0.01 part by mass or more, more preferably 0.05 part by mass or more, still more preferably 0.1 part by mass or more, even more preferably 0.2 part by mass or more, and even more preferably 0.3 part by mass or more, based on 100 parts by mass of the polyacetal resin. Also, the upper limit value of the paraffin wax and / or polyolefin resin content is preferably 2.0 parts by mass or less, more preferably 1.5 parts by mass or less, still more preferably 1.0 parts by mass or less, even more preferably 0.8 parts by mass or less, and even more preferably 0.7 parts by mass or less, based on 100 parts by mass of the polyacetal resin. By setting it below the upper limit value, it is possible to make it more difficult for vacuum voids to occur. In addition, the resin composition of the present embodiment may contain a metal hydroxide, but preferably does not substantially contain it. Not substantially containing means that the content of the metal hydroxide is, for example, less than 3 parts by mass, preferably less than 1 part by mass, and more preferably less than 0.5 parts by mass, based on 100 parts by mass of the polyacetal resin. By setting it within such a range, yellowing of the molded body can be more effectively suppressed.

[0022] <Method for producing resin composition> The method for producing the resin composition of the present embodiment is not particularly limited, and it can be prepared by various conventionally known methods as a method for preparing a resin composition. For example, (1) a method of mixing all the components constituting the resin composition, supplying this to an extruder and melt-kneading to obtain a pelletized composition, (2) a method of supplying a part of the components constituting the resin composition from the main feed port of the extruder and the remaining components from the side feed port and melt-kneading to obtain a pelletized composition, (3) a method of once preparing pellets having different compositions by extrusion or the like and mixing the pellets to adjust to a predetermined composition, (4) a method of mixing a predetermined amount of compounding components with pellets or pulverized products of the polyacetal resin, or coating the surface of pellets or pulverized products of the polyacetal resin with a predetermined amount of compounding components to obtain a predetermined resin composition, etc. can be adopted.

[0023] Next, an extruded molded body formed from the resin composition of the present embodiment will be described. The resin composition of the present embodiment is used for producing molded bodies of various shapes such as round bars or plates by extrusion molding. The extruded molded body of the present embodiment is not only used as a product as it is after molding, but is also used for producing various parts and the like by further processing such as cutting. When extrusion molding, unlike injection molding, since no mold is used, cost reduction can be expected depending on the application. The resin composition of the present embodiment is excellent in extrusion moldability and can significantly reduce voids that are not preferable in terms of physical properties and whitening that is not preferable in terms of appearance, which occur inside the extruded molded body. Therefore, the extruded molded body formed from the resin composition of the present embodiment has extremely high physical property reliability even after being formed into a molded body such as a gear or a container through subsequent cutting. Furthermore, due to the reduction of voids, molding at a low pressure becomes possible, and accordingly, the residual stress of the extruded molded body can also be reduced, and the moldability is also improved. The resin composition of the present embodiment is particularly suitable for molding extruded molded bodies of round bars with a diameter of 10 to 300 mm and extruded molded bodies such as plates with a thickness of 10 to 100 mm. Examples of those formed from the molded body by cutting include gears, containers, screws, and the like. Also, the area of the extrusion cross-section of the extruded molded body is preferably 50 to 2000 cm 2 is preferred.

Examples

[0024] The present invention will be described more specifically with reference to the following examples. The materials, amounts used, ratios, treatment contents, treatment procedures, etc. shown in the following examples can be appropriately changed without departing from the spirit of the present invention. Therefore, the scope of the present invention is not limited to the specific examples shown below. When the measuring instruments used in the examples are difficult to obtain due to obsolescence or the like, measurements can be made using other instruments having equivalent performance.

[0025] Raw materials Polyethylene: Manufactured by Japan Polyethylene Corporation, Novatec LDLJ803 Paraffin wax: manufactured by Nippon Seiro Co., Ltd., Paraffin Wax 155 Magnesium hydroxide: manufactured by Kyowa Chemical Industry Co., Ltd., Mag-Sarat F

[0026] <Method for Measuring Melt Volume Flow Rate (MVR) of Polyacetal Resin> In accordance with ISO 1133, the MVR was measured under the conditions of 190 °C and a load of 2.16 kg. The unit is cm 3 / 10 min.

[0027] Examples 1 to 3, Comparative Examples 1 to 3 <Preparation of Polyacetal Copolymer (Polyacetal Resin)> To 100 parts by mass of trioxane, a desired amount of 1,3-dioxolane, boron trifluoride diethyl etherate as a catalyst in a benzene solution (0.62 mol / Kg-benzene) at 0.05 mmol per 1 mol of all monomers, and a benzene solution of methylal (25% by mass) as a molecular weight regulator were continuously added in such amounts that methylal would have the MVR shown in Table 1 with respect to all monomers, and polymerization was continuously carried out in a twin-screw kneader having a self-cleaning paddle with a jacket whose temperature was set at 65 °C so that the residence time of the polymerization machine would be 15 minutes. To the resulting polymer, a benzene solution of triphenylphosphine (25% by mass) was added in such an amount that triphenylphosphine would be 2 mol per 1 mol of the added boron trifluoride diethyl etherate. After deactivating the catalyst, it was pulverized to obtain a crude polyacetal copolymer. For Polyacetal Resin-1 to 3, the amount of 1,3-dioxolane was adjusted so that the ethylene oxide content would be the value shown in Table 1.

[0028] <Manufacture of Pellets> With respect to 100 parts by mass of the polyacetal resin, the components shown in Table 1 were used in the amounts (parts by mass) shown in Table 1 and mixed by a tumbler-type blender. Next, the resulting mixture was melt-kneaded and pelletized using a twin-screw extruder (L / D = 30) to obtain pellets (resin composition).

[0029] <Time from the start of crystallization to the top of the crystallization peak and area ratio from the start of crystallization to the top of the crystallization peak with respect to the entire crystallization peak> The measurement of the time from the start of crystallization to the top of the crystallization peak and the area ratio from the start of crystallization to the top of the crystallization peak with respect to the entire crystallization peak were determined from the values measured by DSC (differential scanning calorimetry). Specifically, the pellets obtained above were crushed, heated from 40°C to 210°C at a rate of 320°C / min, and held at 210°C for 5 minutes. Then, it was cooled from 210°C to 148°C at 80°C / min, held at 148°C (crystallization start temperature), and the crystallization peaks of each sample were obtained. Furthermore, for the crystallization peak, the area of the peak was obtained by connecting the crystallization start time and the crystallization end time, and the area ratio from the start of crystallization to the top of the crystallization peak with respect to the entire area of the crystallization peak was obtained. Also, the time from the start of crystallization to the top of the crystallization peak was measured. Taking Figure 1 as an example, 1 is the crystallization start time, 2 is the crystallization end time, and 3 is the crystallization peak top time. The area surrounded by the curve between the crystallization start time 1 and the crystallization start time 2 and the dotted line connecting the crystallization start time 1 and the crystallization end time 2 is the entire area of the crystallization peak, and the area from the crystallization start time 1 to the crystallization peak top time 3 is the area indicated by the hatching. As the DSC measuring device, Pyris Diamond DSC manufactured by PerkinElmer was used.

[0030] <Manufacture of round bar> Using the pellets obtained above as raw materials, a solidification extrusion molding machine with a cooling die installed at the head of a Novent single-screw extruder (L / D = 25) was used to obtain a round bar molded product with a diameter of 100 mm. The round bar extrusion molding was carried out under the following conditions.

[0031] Cylinder temperature: 180 - 195°C Die temperature: 195°C Die cooling temperature: 40°C Resin pressure: 3.5 - 4.5 MPa

[0032] <Whitening, void, b value of the core> The round bar molded product obtained above was cut into 3-mm slices, and after applying a micro-check penetrant for detecting red metallic defects to the cross section, it was washed with n-hexane. The area where the liquid had penetrated was magnified with a digital microscope to calculate the area, and the area (unit: mm 2 ) of the region where voids were formed was measured. In addition, for the sliced round bar, the presence or absence of whitening was visually confirmed. Evaluation was performed as follows. The evaluation was carried out by five experts and decided by a majority vote. A: No whitening B: Slight whitening can be confirmed C: Other than A and B, for example, clear whitening can be confirmed, etc. The b value was measured for the sliced round bar under the conditions of C light source and a viewing angle of 2° using SE-6000 manufactured by Nippon Denshoku Industries Co., Ltd. At this time, the measurement was performed avoiding the white core part.

[0033]

Table 1

[0034] As is clear from the above results, the molded body formed from the resin composition of the present invention had no voids, no or only slight whitening of the core, and furthermore, the b value was also low (Examples 1 to 3). On the other hand, when the area ratio from the start of crystallization to the crystallization peak top with respect to the entire crystallization peak was outside the range of 40 to 50%, voids were generated, whitening of the white core was observed, or the b value was high (Comparative Examples 1 to 3).

Explanation of Reference Numerals

[0035] 1 Crystallization start time 2 Crystallization end time 3 Crystallization peak top

Claims

1. An extrusion molding resin composition containing a polyacetal resin, paraffin wax and / or a polyolefin resin, and not containing a release agent other than the paraffin wax and / or the polyolefin resin and a melamine compound, wherein the area from the start of crystallization to the peak top of crystallization when the resin composition is isothermally crystallized at 148°C is in the range of 40 to 50% of the total area of the crystallization peak, the resin composition is molded into a round bar molded product with a diameter of 100 mm by a solidification extrusion molding machine at a cylinder temperature of 180 to 195°C, a die temperature of 195°C, a die cooling temperature of 40°C, and a resin pressure of 3.5 to 4.5 MPa, cut into 3-mm slices, and the b value measured under the conditions of a C light source and a viewing angle of 2° is -3 or less.

2. An extrusion molding resin composition containing a polyacetal resin, paraffin wax and / or polyethylene, and not containing a release agent other than the paraffin wax and / or polyethylene and a melamine compound, wherein the area from the start of crystallization to the peak top of crystallization when the resin composition is isothermally crystallized at 148°C is in the range of 40 to 50% of the total area of the crystallization peak, the content of the polyethylene and paraffin wax is 0.1 part by mass or more and 2.0 parts by mass or less with respect to 100 parts by mass of the polyacetal resin, not containing a melamine compound, a hydrazine compound, a heat stabilizer, an antioxidant, a weather stabilizer, a light stabilizer, an ultraviolet absorber, an antibacterial agent, and a colorant, and the content of the metal hydroxide with respect to 100 parts by mass of the polyacetal resin is less than 3 parts by mass.

3. An extrusion molding resin composition containing a polyacetal resin, paraffin wax and / or a polyolefin resin, and not containing a release agent other than the paraffin wax and / or the polyolefin resin and a melamine-formaldehyde polycondensate, wherein the area from the start of crystallization to the peak top of crystallization when the resin composition is isothermally crystallized at 148°C is in the range of 40 to 50% of the total area of the crystallization peak, when the resin composition is molded into a round bar molded product with a diameter of 100 mm by a solidification extrusion molding machine at a cylinder temperature of 180 to 195°C, a die temperature of 195°C, a die cooling temperature of 40°C, and a resin pressure of 3.5 to 4.5 MPa and cut into 3-mm slices, no whitening is confirmed. The resin composition is formed into a round bar molded product with a diameter of 100 mm by a solidifying extrusion molding machine at a cylinder temperature of 180 to 195°C, a die temperature of 195°C, a die cooling temperature of 40°C, and a resin pressure of 3.5 to 4.5 MPa, cut into 3-mm slices, and has a b value of -3 or less when measured under the conditions of a C light source and a viewing angle of 2°.

4. An extrusion molding resin composition containing a polyacetal resin, paraffin wax and / or polyethylene, and not containing a mold release agent other than the paraffin wax and / or polyethylene and a melamine-formaldehyde polycondensate, when the resin composition is isothermally crystallized at 148°C, the area from the start of crystallization to the crystallization peak top is in the range of 40 to 50% of the total area of the crystallization peak, when the resin composition is formed into a round bar molded product with a diameter of 100 mm by a solidifying extrusion molding machine at a cylinder temperature of 180 to 195°C, a die temperature of 195°C, a die cooling temperature of 40°C, and a resin pressure of 3.5 to 4.5 MPa and cut into 3-mm slices, no whitening can be confirmed, the content of the polyethylene and paraffin wax is 0.1 part by mass or more and 2.0 parts by mass or less based on 100 parts by mass of the polyacetal resin, not containing a melamine compound, a hydrazine compound, a heat stabilizer, an antioxidant, a weather stabilizer, a light stabilizer, an ultraviolet absorber, an antibacterial agent, and a colorant, a resin composition in which the content of the metal hydroxide is less than 3 parts by mass based on 100 parts by mass of the polyacetal resin.

5. The resin composition according to any one of claims 1 to 4, wherein the time from the start of crystallization to the crystallization peak when isothermally crystallized at 148°C is 50 seconds or more.

6. The resin composition according to any one of claims 1 to 4, wherein the time from the start of crystallization to the crystallization peak when isothermally crystallized at 148°C is 60 seconds or more.

7. The resin composition according to claim 1 or 3, wherein the polyolefin resin contains a polyethylene resin.

8. An extrusion molded body formed from the resin composition according to any one of claims 1 to 7.

9. The extrusion molded body according to claim 8, wherein the extrusion molded body is in the shape of a round bar or a plate.

10. The area of the extrusion cross-section of the extrusion molded body is 50 to 2000 cm 2 The extrusion molded body according to claim 8 or 9, wherein the extrusion molded body is as described above.

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