JP2007223073A - Extrusion mold and long article manufacturing method using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an extrusion mold for performing the extrusion molding of a long article having high transparency or a uniformly highly foamed long article. <P>SOLUTION: In the extrusion mold 1 for performing the extrusion molding of the long article comprising a thermoplastic resin, a core space 2a is formed to the mold body 2 which constitutes the mold 1 and a core 3 comprising polyethylene fluoride having a through-hole becoming a resin flow channel 3a at the time of molding is arranged in the core space 2a. Herein, the thickness of the core 3 is preferably 2-50 mm and the size thereof is preferably 97-99% with respect to the core space 2a of the mold body 2. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an extrusion mold and a manufacturing method for manufacturing a long object such as a rod, a plate, and a pipe using the extrusion mold.

  Conventionally, various long objects are manufactured by extrusion molding. For example, highly transparent thermoplastic resin pipes used as protective pipes for cleaning agent transport pipes in the semiconductor industry, etc., and foams such as thermoplastic resin rods and boards used in decoration, foam pipes, foam boards, surrounding edges, baseboards, etc. Profiles are produced by extrusion.

  Thermoplastic resins used for extrusion are usually heat stabilizers, heat stabilization aids, plasticizers, lubricants, processing aids, impact modifiers, heat resistance improvers, antioxidants, light stabilizers, etc. The additive is added. For this reason, when the thermoplastic resin is a crystalline resin, most of them are low in transparency and cloudy. On the other hand, in the case where the thermoplastic resin is an amorphous resin, in order to improve transparency, acid resistance, alkali resistance, water resistance, electrical insulation, flame resistance, mechanical strength, etc., which are characteristics of the thermoplastic resin Therefore, it is necessary to reduce the amount of the additive within a range not impairing the resistance.

  However, if the amount of heat stabilizer or lubricant added is reduced, the thermoplastic resin may be discolored by heat inside the mold, or degradation products generated by the resin staying in the product may be mixed into the product, reducing transparency. Furthermore, the mold is corroded by a gas generated by decomposition of hard vinyl chloride or the like. Therefore, in order to produce a long shaped article with high transparency even if the amount of heat stabilizer or lubricant added is small, it is important to suppress degradation due to resin retention. Further, when molding the foam, it is important to reduce the shear, which is the resin flow resistance of the mold wall surface, and improve the slipperiness in order to uniformly increase the foam.

In response to such problems, the resin flow path of the mold is coated with a fluororesin to improve the lubricity, or as disclosed in Patent Document 1, a fluorine-based lubricant is applied over the entire circumference of the resin composition. It has been proposed to improve lubricity by supplying.
JP 7-117103 A

  However, in the case where the resin flow path of the mold is coated with a fluororesin, there is a problem that the coating portion is peeled off due to long-term molding, and the resin stays in the peeled dent, or a decomposition product is likely to be generated due to the stay. It was. Also, in the case of supplying a lubricant, the mold structure is complicated and the cost of the mold is increased, and it is difficult to adjust the development of the lubricant at the interface between the mold and the resin. There was a problem that it had to be removed.

  The present invention has been made in view of such a problem, and it is possible to extrude a highly transparent long product without generating a decomposition product due to the retention of the thermoplastic resin, or the residence time is small. In addition to providing an extrusion mold that can extrude a long foam that has been uniformly highly foamed by reducing shear at the mold wall surface, and using an extrusion mold, the transparency is high. Or the manufacturing method which can extrude the elongate thing uniformly high-foamed is provided.

  The extrusion mold of the present invention is an extrusion mold for extruding a long product made of a thermoplastic resin, and a nested space is formed in a part of the mold, and a resin flow path is formed in the nested space at the time of molding. This is characterized in that a nesting made of polyfluorinated ethylene having through-holes is provided.

  In the present invention, examples of the polyfluorinated ethylene include polytetrafluoroethylene resin (PTFE), perfluoroalkoxy resin (PFA), and fluorinated ethylene propylene resin (FEP). Among these, PFA and PTFE having high heat resistance can be preferably used.

  In the present invention, the placement position of the insert is preferably provided in a portion where the resin stays noticeably in the mold. Specifically, since the resin stays frequently at the site where the flow path changes suddenly at 60 ° or less, it is preferable to dispose the resin at the sudden change portion of the flow path. Further, in the foam mold, it is preferable to reduce the wall shear to the discharge of the resin, and therefore it is preferable to provide a nesting up to the tip outlet. In this case, in order to fix the insert to the mold, it is preferable to provide a step in the mold and the insert.

  According to the present invention, since the nesting made of polyfluorinated ethylene is arranged in the resin flow path, the residence of the thermoplastic resin can be suppressed. Long objects such as tall bars, plates and tubes can be extruded. In addition, it is possible to extrude long objects such as rods, plates, and pipes made of a foam that has a short residence time and is uniformly foamed with reduced wall shear.

  In the present invention, the thickness of the insert is preferably 2 mm or more and 50 mm or less, and the insert size is 97% or more and 99% or less with respect to the insert space formed in the mold.

  When the thickness of the nesting is less than 2 mm, there is a risk of deformation due to resin pressure or peeling from the mold. On the other hand, if the thickness exceeds 50 mm, the thermal conductivity of the insert is small, so that it does not follow the mold temperature and it is difficult to control the temperature appropriately. More preferably, it is 2 mm or more and 20 mm or less.

  In addition, the nesting dimension is set in consideration of expansion at the use temperature so that resin leakage does not occur at the connecting portion between the nesting and the mold. Specifically, if the dimensional ratio of the nesting relative to the nesting space of the mold is less than 97%, a gap may be generated between the nesting and the mold, and resin leakage may occur. Further, if the dimensional ratio of the nesting to the nesting space of the mold exceeds 99%, a step is generated between the mold and the nesting space, the nesting may be deformed, and the resin may be retained.

  A method for producing a long product using an extrusion mold according to the present invention is characterized in that a long product made of a thermoplastic resin is extruded using the extrusion mold according to claim 1. It is.

  According to the present invention, it is possible to extrude a long object such as a highly transparent rod, plate, or pipe without generating a decomposition product due to resin retention. In addition, it is possible to extrude long objects such as rods, plates, and pipes made of a foam that has a short residence time and is uniformly foamed with reduced wall shear.

  In the present invention, the thermoplastic resin, especially the polyvinyl chloride resin that is severely deteriorated, loses the acid resistance, alkali resistance, water resistance, electrical insulation, flame resistance, and mechanical strength, which are the characteristics of the polyvinyl chloride resin. Additives generally added when molding a polyvinyl chloride resin composition, if necessary, for example, heat stabilizer, heat stabilization aid, lubricant, processing aid, heat resistance An improver, a light stabilizer and the like may be added.

  The heat stabilizer is not particularly limited as long as it is a heat stabilizer used in molding a polyvinyl chloride resin composition. For example, dimethyltin mercapto, dibutyltin mercapto, dioctyltin mercapto, dibutyl Organotin stabilizers such as tin malate, dibutyltin malate polymer, dioctyltin malate, dioctyltin malate polymer, dibutyltin laurate, dibutyltin laurate polymer, lead stearate, dibasic lead phosphite, tribasic Lead stabilizers such as basic lead sulfate, calcium-zinc stabilizers, barium-zinc stabilizers, barium-cadmium stabilizers, and the like. These may be used alone or in combination of two or more.

  The stabilizing aid is not particularly limited as long as it is a stabilizing aid used when molding a polyvinyl chloride resin composition. For example, epoxidized soybean oil, epoxidized linseed bean oil, epoxy Tetrahydrophthalate, epoxidized polybutadiene, phosphoric acid ester and the like. These may be used alone or in combination of two or more.

  Examples of the lubricant include an internal lubricant and an external lubricant used when molding a polyvinyl chloride resin composition.

  The internal lubricant is a lubricant added for the purpose of reducing the flow viscosity of the molten resin during molding and preventing frictional heat generation. For example, lauryl alcohol, stearyl alcohol, stearic acid, butyl stearate, glycerin monostearate , Epoxidized soybean oil, bisamide and the like. These may be used alone or in combination of two or more.

  The external lubricant is a lubricant added for the purpose of enhancing the sliding effect between the molten resin and the mold surface during molding, and examples thereof include montanic acid wax, paraffin wax, polyethylene wax, ester wax and the like. These may be used alone or in combination of two or more.

  The processing aid is not particularly limited as long as it is a processing aid used when molding a polyvinyl chloride resin composition. For example, an alkyl acrylate-alkyl having a weight average molecular weight of 100,000 to 2,000,000. Examples include acrylic processing aids that are methacrylate copolymers, and specific examples include n-butyl acrylate-methyl methacrylate copolymer, 2-ethylhexyl acrylate-methyl methacrylate-butyl methacrylate copolymer, and the like. These may be used alone or in combination of two or more.

  The heat resistance improver is not particularly limited as long as it is a heat resistance improver used when molding a polyvinyl chloride resin composition. For example, α-methylstyrene-based, N-phenylmaleimide-based, etc. Examples include heat resistance improvers. These may be used alone or in combination of two or more.

  The antioxidant is not particularly limited as long as it is an antioxidant used when molding a polyvinyl chloride resin composition, and examples thereof include phenol antioxidants. These may be used alone or in combination of two or more.

  The light stabilizer is not particularly limited as long as it is a light stabilizer used in molding a polyvinyl chloride resin composition, and examples thereof include hindered amine light stabilizers. These may be used alone or in combination of two or more.

  The method for mixing the additive and the polyvinyl chloride resin composition is not particularly limited, and examples thereof include a hot blend method, a cold blend method, and a solution mixing method.

  Examples of the thermoplastic resin used for foaming include polyethylene, polystyrene, polypropylene, polyvinyl chloride, polyamide, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, and the like. These may be used alone or in combination of two or more.

  For foaming, an inorganic gas such as nitrogen gas or carbon dioxide gas, a chemical reaction foaming agent (ADCA), or the like can be used.

  According to the present invention, it is possible to extrude a highly transparent long product without generating a decomposition product due to the residence of the thermoplastic resin, and the residence time is small, and the wall surface shear is reduced to increase the foam uniformly. It is possible to extrude a long product made of a foamed material.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 shows an embodiment of an extrusion mold 1 of the present invention together with an extruder 10.

  The extrusion mold 1 is a mold for extruding a rod made of a thermoplastic resin composition, and includes a mold body 2, a insert 3 disposed in a insert space 2a of the mold body 2, A tip mold 4 integrally fixed to a downstream end of the mold body 2 in the resin flow direction, and an upstream end of the mold body 2 in the resin flow direction of the extruder 10 It is held by an adapter 12 attached to the tip of the barrel 11.

  In the mold body 2, a nesting space 2 a having a shape substantially corresponding to the outer dimension of the nesting 3 is formed from the upstream end portion to the downstream end portion in the resin flow direction. The nesting space 2a includes a cylindrical upstream nesting space 21a formed at the upstream end and a cylindrical downstream nesting space formed at the downstream end and having a smaller diameter than the inner diameter of the upstream nesting space 21a. 22a and a truncated cone-shaped intermediate nested space 23a having a tapered surface which is formed from the downstream end of the upstream nested space 21a to the upstream end of the downstream nested space 22a at a substantially intermediate portion, and has a tapered surface whose sectional area gradually decreases toward the downstream side. And is composed of.

  On the other hand, the nesting 3 disposed in the nesting space 2a of the mold body 2 is formed of polyfluoroethylene with an outer shape substantially corresponding to the inner shape of the nesting space 2a, and resin is formed inward from the upstream end to the downstream end. A through hole serving as the flow path 3a is formed. Specifically, as shown in FIG. 2, the nesting 3 includes a cylindrical upstream nesting portion 31 having an outer diameter substantially corresponding to the inner diameter of the upstream nesting space 21a of the nesting space 2a, and a downstream nesting space 22a. A cylindrical downstream nesting portion 32 having an outer diameter substantially corresponding to the inner diameter, the upstream nesting portion 31 and the downstream nesting portion 32 are connected, and a truncated cone having a taper surface substantially corresponding to the taper surface of the intermediate nesting space 23a. The intermediate nesting portion 33 is formed to have a constant thickness from the upstream end to the downstream end, and the space formed by the inner peripheral surface thereof becomes the resin flow path 3a.

Here, the size of the nesting 3 is set in consideration of the expansion at the use temperature, and specifically, the size of the nesting space of the mold / (linear expansion coefficient × (molding temperature−normal temperature) +1) is obtained. It is done. For example, when polytetrafluoroethylene is used as the polyfluorinated ethylene, the linear expansion coefficient of polytetrafluoroethylene is 10 × 10 ⁻⁵ / ° C., the length of the nested space 2a is 100 mm, the molding temperature is 220 °, When the normal temperature is 20 ° C., the length of the insert 2 is 98.04 mm from the above formula. Further, when the inner diameter of the upstream end of the resin flow path 3a during molding is 65 mm and the inner diameter of the downstream end is 25 mm, the inner diameter of the upstream end of the insert 3 is 63.73 mm, and the inner diameter of the downstream end Is 24.51 mm. Similarly, the outer diameter of the insert 3 is set in accordance with the inner diameter of the insert space 2a of the mold body 2.

  Note that the linear expansion coefficient of the mold body 2 is one-tenth to one-tenth of the linear expansion coefficient of polytetrafluoroethylene, and the length is short and the temperature change is small. The expansion is small and can be ignored.

  Further, an inner diameter resin flow path 4a serving as an outlet of the molded product is formed in the tip die 4 from the upstream end to the downstream end.

  Next, a method for forming a bar using the extrusion mold 1 configured as described above will be described.

  First, the insert 3 is disposed in the insert space 2a of the mold body 2 through the opening at the upstream end thereof, the tip mold 4 is fixed to the mold body 2, and then the mold 1 is attached to the adapter 12 of the extruder 10. To do. Next, the mold 1 is preheated to the molding temperature, and the insert 3 disposed in the insert space 2a of the mold body 2 is expanded. As a result, the insert 3 is thermally expanded to fit into the insert space 2a of the mold body 2 without any gap, and from the opening at the upstream end of the inner diameter corresponding to the diameter of the extruder 10, the resin flow path of the tip mold 4 A resin flow path 3a is formed over the opening at the downstream end of the inner diameter corresponding to 4a.

  Next, when the extruder 10 is driven, the thermoplastic resin composition is melted and extruded by the screw 13, shaped into a rod shape by the mold 1, and extruded from the tip mold 4. The bar extruded from the mold 1 is cooled and taken up by a take-up machine (not shown).

  Here, since the insert 3 made of polyfluorinated ethylene is disposed in the extrusion mold 1 to form the resin flow path 3a, the molten resin stays on the taper surface which is the flow path sudden change portion. It does not occur, and therefore, no decomposition product is generated due to resin retention. As a result, a rod made of a thermoplastic resin having high transparency can be stably produced over a long period of time.

  FIG. 3 shows a modification of the extrusion mold 1.

  The extrusion mold 1 is a mold for extruding a rod made of a foamable resin composition, and the mold 1 is composed only of a mold body 2 and is upstream of the mold body 2 in the resin flow direction. A nesting space 2b is formed over the entire length between the end and the downstream end, and the nesting 3 is disposed in the nesting space 2b and held by the adapter 12 of the extruder 10 as described above.

  That is, the nesting space 2b of the mold body 2 is substantially intermediate between a cylindrical upstream nesting space 21b formed at the upstream end and a cylindrical downstream nesting space 22b formed at the downstream end. And a frustoconical intermediate nesting space 23b having a tapered surface formed from the downstream end of the upstream nesting space 21b to the upstream end of the downstream nesting space 22b. In the downstream nesting space 22b, the nesting 3 A step 221b for positioning is formed.

  On the other hand, the insert 3 is formed with polyfluoroethylene in an outer shape substantially corresponding to the inner shape of the insert space 2b of the mold body 2, and a through-hole serving as a resin flow path 3a is formed inward from the upstream end to the downstream end. Is formed. That is, the nesting 3 includes an upstream nesting portion 31 substantially corresponding to the upstream nesting space 21b of the nesting space 2b, a downstream nesting portion 32 substantially corresponding to the downstream nesting space 22b, the upstream nesting portion 31 and the downstream side. The nesting portion 32 is connected to the intermediate nesting portion 33 substantially corresponding to the intermediate nesting space 23b. The downstream nesting portion 32 is formed with a step portion 321 capable of contacting the step 221b of the downstream nesting space 22b. Further, the downstream end vicinity portion serving as the outlet of the downstream nesting portion 32 is formed to have a constant thickness except that it is formed relatively thin, and the resin flow path 3a is formed from the upstream end to the downstream end by the inner peripheral surface thereof. ing.

  Also in the case of molding a rod made of a foamable resin composition using the extrusion mold 1 configured as described above, the insert 3 is disposed in the insert space 2b of the mold body 2 through the opening at the upstream end thereof. After the mold body 2 is mounted on the adapter 12 of the extruder 10, the mold 1 is preheated to a molding temperature, and the insert 3 disposed in the insert space 2b of the mold body 2 is expanded. As a result, the insert 3 is thermally expanded to fit into the insert space 2b of the mold body 2 without a gap, and from the upstream end to the downstream end, from the opening at the upstream end of the inner diameter corresponding to the diameter of the extruder 10, the molded product The resin flow path 3a is formed over the opening at the downstream end of the inner diameter corresponding to the outer diameter of the outlet. At this time, the nest 3 is positioned by the stepped portion 321 abutting against the step 221b of the nest space 22b.

  Next, when the extruder 10 is driven, the foamable resin composition is melted and extruded by the screw 13, shaped into a rod shape by the mold 1 and extruded.

  Here, in the mold body 2 constituting the extrusion mold 1, a polyfluorinated ethylene insert 3 is disposed from the upstream end to the downstream end serving as the outlet to form a resin flow path 3 a. Therefore, the molten resin does not stay, the residence time is small, and the rod made of the expandable resin composition that is uniformly foamed with reduced wall shear can be extruded.

  In the above-described embodiments and modifications, it is possible to extrude a long plate material instead of a rod material by forming the resin flow path of the mold 1 corresponding to the plate material having a square cross section until illustrated. It is clear without a doubt.

  Further, FIG. 4 shows another embodiment of the extrusion mold 1 of the present invention.

  This extrusion mold 1 is a mold for extruding a tube material made of a foamable resin composition, and the mold 1 is integrated with the bridge mold 5 and the downstream end of the bridge mold 5 in the resin flow direction. Are connected to each other, and a tip mold 4 in which a nesting space 4 a is formed from the upstream end to the vicinity of the downstream end in the resin flow direction, a nesting 3 disposed in the nesting space 4 a of the tip mold 4, and a bridge mold 5. The mandrel 6 is supported through the bridge 61 and disposed over the bridge mold 5 and the tip mold 4, and is held by the adapter 12 of the extruder 10.

  The nesting space 4a formed in the tip die 4 is formed in the cylindrical upstream nesting space 41a formed in the upstream end and the downstream end excluding the vicinity of the downstream end, and the upstream nesting space 41a A cylindrical downstream nesting space 42a having a smaller diameter than the inner diameter, and formed at a substantially intermediate portion from the downstream end of the upstream nesting space 41a to the upstream end of the downstream nesting space 42a, and the sectional area gradually decreases toward the downstream side. And a frustoconical intermediate nested space 43a having a tapered surface.

  On the other hand, the nesting 3 disposed in the nesting space 4a of the tip die 4 is formed by polyfluoroethylene in an outer shape substantially corresponding to the inner shape of the nesting space 4a, and resin is formed inward from the upstream end to the downstream end. A through hole serving as the flow path 3a is formed. Specifically, as shown in FIG. 4, the nesting 3 includes a cylindrical upstream nesting portion 31 having an outer diameter substantially corresponding to the inner diameter of the upstream nesting space 41a of the nesting space 4a and the inner diameter of the downstream nesting space 42a. A cylindrical downstream nesting portion 32 having an outer diameter substantially equivalent to the upper nesting portion 31 and the downstream nesting portion 32, and a truncated cone-shaped intermediate nesting having a tapered surface substantially corresponding to the tapered surface of the intermediate nesting space 43a. The portion 33 is formed with a constant thickness from the upstream end to the downstream end, and a space formed by the inner peripheral surface and the outer peripheral surface of the mandrel 6 becomes the resin flow path 3a.

  In addition, the mandrel 6 is a well-known thing used when extruding a pipe material, The detailed description is abbreviate | omitted.

  In the case where a tubular material made of a thermoplastic resin composition is molded using the extrusion mold 1 configured as described above, the insert 3 is disposed in the insert space 4a of the tip mold 4 through the opening at the upstream end thereof. The tip die 4 is fixed to the bridge die 5 holding the mandrel 6, the bridge die 5 is attached to the adapter 12 of the extruder 10, the die 1 is preheated to the molding temperature, and the tip die 4 The nesting 3 disposed in the nesting space 4a is expanded. As a result, the insert 3 is thermally expanded and fits in the insert space 4a of the tip mold 4 without any gap, and the resin outlet exits from the opening at the upstream end of the inner diameter corresponding to the inner diameter of the downstream end opening of the bridge mold 5. The resin flow path 3 a is formed together with the mandrel 6 over the opening at the downstream end of the inner diameter corresponding to the inner diameter of the downstream end opening of the tip die 4.

  Next, when the extruder 10 is driven, the foamable resin composition is melted and extruded by the screw 13, shaped into a tube by the mold 1 and extruded.

Here, in the front end mold 4 constituting the extrusion mold 1, a polyfluorinated ethylene insert 3 is disposed from the upstream end to the vicinity of the downstream end which is the outlet, and the mandrel 6 and the resin flow path 3 a. Therefore, the molten resin does not stay on the tapered surface, which is the flow path sudden change portion, and therefore, the decomposition product accompanying the resin stay does not occur. As a result, it is possible to stably manufacture a tube material made of a foamable resin composition having high transparency over a long period of time.
Example 1
A bar was extruded using the molding die shown in FIG. The upstream inner diameter of the mold during molding (the inner diameter of the upstream nesting portion of the nesting) is 65 mm, the downstream inner diameter (the inner diameter of the nesting downstream of the nesting portion) is 25 mm, and a tapered resin flow path (the intermediate nesting portion of the nesting) ) Is set to 20 mm, and the taper angle in this case is 45 °.

As described above, the nesting space length of the mold body is 100 mm, and the polytetrafluoroethylene nesting is 10 × 10 ⁻⁵ / ° C., the molding temperature is 220 ° C., and the room temperature is 20 ° C. The thickness and inner diameter were set.

  The thermoplastic resin composition includes 100 parts by weight of a thermochlorinated hard vinyl chloride resin having a polymerization degree p = 600 and a chlorination degree Cl = 64.8%, 5 parts by weight of a butyltin mercapto stabilizer, a PMMA system ( (Extrasmooth) A processing aid comprising 1.5 parts by weight was used.

  Furthermore, a single screw extruder manufactured by Ikegai Seisakusho with an extrusion rate of 20 kg / h and a diameter of 65 mm was used as the extruder.

When molding was carried out under the above conditions, no stagnant burn occurred in the molded product, and the light transmittance at a wavelength of 650 nm was maintained at a high transparency of 90% and could be stably produced.
(Comparative Example 1)
As a mold of Comparative Example 1, a mold without nesting, specifically, a resin flow path corresponding to the resin flow path of the nesting of Example 1 is formed, and the inner peripheral surface thereof is subjected to hard chrome plating. A mold was used.

When the resin composition of Example 1 was used and molding was performed in the same manner using the same extruder, a resin staying burn occurred in the flow path sudden change portion (taper surface portion), and foreign matter was found in the molded product. It was mixed.
(Example 2)
The foamable plate material was extruded using the molding die shown in FIG. The upstream opening height of the mold at the time of molding is set to 65 mm, the downstream opening height is set to 25 mm, and the length of the tapered resin flow path is set to 90 mm. In this case, the taper angle is 12.8 °. It has become.

The mold body has a nesting space length of 150 mm, and the polytetrafluoroethylene nesting has a linear expansion coefficient of 10 × 10 ⁻⁵ / ° C., a molding temperature of 180 ° C., and a normal temperature of 20 ° C. The opening height was set.

  The foamable thermoplastic resin composition includes 100 parts by weight of a polyvinyl chloride resin having a polymerization degree p = 900 and a chlorination degree Cl = 56.8%, 0.5 parts by weight of a foaming agent (ADCA), and a stabilizer 4. A part consisting of 10 parts by weight of a foam nucleating agent (calcium carbonate) was used.

  Furthermore, a single screw extruder manufactured by Ikegai Seisakusho with an extrusion rate of 20 kg / h and a diameter of 65 mm was used as the extruder.

  Under the above conditions, molding was performed at a molding temperature of 180 ° C., the cross-section of the molded product was divided into 10 equal parts in the width direction, and the density at the center in the thickness direction was measured using a density measuring device.

As a result of the measurement, the average expansion ratio was 1.97 times, and the expansion ratio distribution had a standard deviation value of 0.09.
(Comparative Example 2)
As the mold of Comparative Example 2, a non-nested mold of Example 2 is formed, specifically, a resin flow path corresponding to the resin flow path of the nested of Example 2 is formed, and the inner peripheral surface thereof is hard chrome. A metal mold subjected to plating was used.

  While using the resin composition of Example 2, it shape | molded similarly using the same extruder, The foaming ratio of the molded article was measured similarly. As a result of the measurement, the expansion ratio was 1.78, and the expansion ratio distribution had a standard deviation value of 0.17.

  As described above, according to the present invention, it is possible to extrude a long product with high transparency, and it is possible to extrude a long product made of a foam that is uniformly highly foamed. It is possible to improve the yield.

It is sectional drawing which shows typically one Embodiment of the extrusion die of this invention with an extruder. FIG. 2 is a half cross-sectional view showing an enlarged insert of the extrusion mold of FIG. 1. It is sectional drawing which shows the modification of the extrusion die of FIG. It is sectional drawing which shows typically other embodiment of the extrusion mold of this invention with an extruder.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Mold for extrusion molding 2 Mold body 2a, 2b Nesting space 3 Nesting 4 Tip mold 4a Nesting space 5 Bridge mold 6 Mandrel

Claims (3)

  Polyethylene fluoride which is an extrusion mold for extruding a long product made of a thermoplastic resin, having a nesting space in a part of the mold, and having a through hole serving as a resin flow path in the nesting space An extrusion mold characterized in that an insert made of is disposed.   The extruded metal mold according to claim 1, wherein the thickness of the insert is 2 mm or more and 50 mm or less, and the insert size is 97% or more and 99% or less with respect to the insert space of the mold. Type.   A method for producing a long article using an extrusion mold, comprising: extruding a long article made of a thermoplastic resin using the extrusion mold according to claim 1.

Images