JPS6330844B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for blow-molding poly-4-methyl-1-pentene and a blow-molding die, and more specifically to a die for blow-molding poly-4-methyl-1-pentene, which has excellent transparency.
The present invention relates to a method for manufacturing a pentene hollow molded body and a blow molding die suitably used in the process. Poly-4-methyl-1-pentene is characterized by its transparency,
Taking advantage of its heat resistance and chemical resistance, it is used for molding into chemical laboratory instruments such as beakers and graduated cylinders, syringes for syringes, optical measurement shells, trays for microwave ovens, etc., but most of these are injection molded. It's drifting. Since poly-4-methyl-1-pentene has a low viscosity when melted, the drawdown of the parison is large, making it somewhat difficult to apply it to blow molding. Although there is a method of improving drawdown properties by lowering the molding temperature, this method causes surface roughness in the parison due to melt fracture and reduces the transparency of the resulting hollow molded product. Further, the die of a blow molding machine is usually heated from the outside of the die by a band heater or an embedded heater. Furthermore, as a method to prevent the surface of the parison from becoming rough, a method has been proposed in which the die is heated by a band heater. If the resin is opaque or translucent, such as high-density polyethylene or polypropylene, the surface roughness of the parison can be eliminated by this method, and a hollow molded article with a good appearance can be obtained. However, even when this method is applied to poly-4-methyl-1-pentene, the rough surface of the inner surface of the parison is not resolved at all, and a hollow molded article with good transparency cannot be obtained. One way to eliminate rough skin is to add lubricants such as higher fatty acids or their metal salts, higher fatty acid amides, higher fatty acid esters, higher alcohols, and wax. It is necessary to add a lubricant, and as a result, the lubricant oozes out, making the resin surface cloudy and potentially reducing transparency. Therefore, the present inventors investigated a method for obtaining a hollow molded body of poly4-methyl-1-pentene having excellent transparency, and as a result, they arrived at the present invention. That is, the present invention provides a method for blow molding poly-4-methyl-1-pentene.
1- After melting pentene at a temperature of 200-350℃,
Poly 4 is characterized by extrusion through a blow molding die in which the temperature of the die is set at 200 to 350°C and the temperature of the core is set independently to 100 to 350°C.
- A blow molding method for methyl-1-pentene is provided, and a die for blow molding is provided, which is characterized in that it comprises a die having a die butt heating device and a core having a core heating device. The poly-4-methyl-1-pentene used in the method of the present invention is a homopolymer of 4-methyl-1-pentene or a polymer of 4-methyl-1-pentene and other α
- olefins, such as ethylene, propylene, 1-butene, 1-hexene, 1-octene,
4-Methyl-1- is a copolymer with α-olefin having 2 to 20 carbon atoms such as 1-decene, 1-tetradecene, and 1-octadecene, and usually contains 85 mol% or more of 4-methyl-1-pentene. It is a crystalline polymer mainly composed of pentene. Then, the melt flow rate of poly4-methyl-1-pentene (load:
5 kg, temperature: 260°C, hereinafter abbreviated as MFR) is preferably in the range of 0.5 to 50 g/10 minutes.
If the MFR is less than 0.5 g/10 minutes, the melt viscosity is high and moldability is poor, and even if the method of the present invention is applied, there is a possibility that rough skin will not be resolved. On the other hand, MFR is 50
If it exceeds g/10 minutes, the melt tension is low and the drawdown of the parison is large, making blow molding impossible. In the blow molding method of the present invention, the poly-4-methyl-1-pentene is heated at 200 to 350°C, preferably at 240 to 350°C.
After melting at a temperature of 280°C, it is extruded through a blow molding die with a die set at a temperature of 200 to 350°C, preferably 250 to 280°C, and a core temperature of 100 to 350°C, preferably 150 to 280°C. It's a method. The melting temperature of poly4-methyl-1-pentene is 200℃
If the temperature is below 350℃, the extrusion skin of the parison will not be improved even if the temperature of the divertail and core is increased.
If it exceeds this, the drawdown of the parison will become large and hollow molding will not be possible. The temperature of the diver is
If the temperature is less than 200℃ or the core temperature is less than 100℃,
This is undesirable because the extrusion skin of the parison is not improved and the transparency of the obtained hollow molded body is poor.On the other hand, if the die butt temperature exceeds 350℃ or the core temperature exceeds 350℃, the drawdown of the parison will deteriorate. This is not preferable because it becomes large and cannot be hollow-molded. The heating of the dive shaft and the heating of the core include:
The heating is performed separately using an electromagnetic induction heating device and an electric resistance heating device. General blow molding dies are designed to heat only the die bush, and using such a die, poly 4-methyl-
In order to eliminate rough skin on the inner surface of the 1-pentene parison, it is necessary to raise the temperature of the dive shell to at least 350°C. However 350
If the temperature exceeds ℃, the drawdown of the parison will increase, making hollow molding difficult.
The surface of the parison may also undergo thermal deterioration, which may reduce the appearance and strength of the product. An embodiment of the die of the present invention is shown in FIGS. 1 and 2. FIG. 1 shows a blow molding die head equipped with the die of the invention of FIG. 1; The dive shaft 1 and the core 3 are each equipped with a heater 2 and a heater 4, and the temperature can be adjusted separately. The die 1 and core 3 are connected to a die body 5 and a mandrel 6, respectively, and via a crosshead 9 to a cylinder 10 of the extruder. The heating of the die body 5 and crosshead 9 can be controlled by heaters 7, respectively. FIG. 2 shows a die of the present invention. Dive Tsushi 1
The core 3 is each independently equipped with a heater 2 and a heater 4. The melting of the poly-4-methyl-1-pentene is
This can be done using a normal extruder, but if an orifice is used in place of a breaker plate in the screw head of the extruder, the formation of vertical streaks on the hollow molded product due to the split flow of resin caused by the breaker plate can be suppressed. This is preferable because it can be done. The extrusion method for poly4-methyl-1-pentene parison includes continuous extrusion using screw rotation;
This can be carried out by a known method such as injection extrusion using an in-line screw or extrusion using an accumulator method. In the method of the present invention, various known die heads for blow molding can be used, such as a side-inflow type head, a center-inflow type head, a spiral type head, and the like. Poly4-methyl- obtained by the method of the present invention
The 1-pentene hollow molded product has excellent transparency and has the heat resistance, rigidity, chemical resistance, boiling water resistance, food hygiene properties, etc. inherent to poly4-methyl-1-pentene, so it is suitable for flasks, blood, etc. It can be used for chemical and medical instruments such as industrial cells, containers for food, containers for industrial chemicals, etc. EXAMPLES Next, the present invention will be explained in more detail with reference to examples, but the present invention is not limited to these examples unless the gist thereof is exceeded. Example 1 Using a resin (product name TPXDX845 manufactured by Mitsui Petrochemical Industries, Ltd.) with an MFR of 8 g/10 minutes as poly-4-methyl-1-pentene, blow molding was performed using a die equipped with a cartridge heater in the core. A 400 c.c. cylindrical bottle was molded using a machine (model V8 manufactured by Japan Steel Works, Ltd.). The molding temperature conditions are the extruder cylinder at 260℃,
The temperature of the crosshead was 250°C, the die body was 250°C, the die was 270°C, and the core was 300°C, and the mold was cooled with water. Haze (ASTM D 1003) and gloss (ASTM D
523) are shown in Table 1. Example 2 The same procedure as in Example 1 was carried out except that the temperature of the dive shaft was 220°C and the temperature of the core was 120°C.
The results are shown in Table 1. Example 3 The same procedure as in Example 1 was carried out except that the temperature of the dive shaft was 300°C and the temperature of the core was 320°C.
The results are shown in Table 1. Comparative Example 1 The same procedure as in Example 1 was carried out except that the temperature of the dive shaft was 150°C and the temperature of the core was 80°C.
The results are shown in Table 1. Comparative Example 2 The same procedure as in Example 1 was carried out except that the temperature of the dive shaft was 370°C and the temperature of the core was 380°C.
The results are shown in Table 1. Comparative Example 3 Except for setting the extruder cylinder temperature to 190℃,
The same procedure as in Example 1 was carried out. The results are shown in Table 1. Comparative Example 4 The same procedure as in Example 1 was carried out except that the temperature of the dive gun was 240° C. and the core was not heated. The results are shown in Table 1. Comparative Example 5 The same procedure as in Example 1 was conducted except that the core temperature was 240° C. and the dive bush was not heated.
The results are shown in Table 1. 【table】

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional view of a die body equipped with a blow-forming die of the present invention, and FIG. 2 is a vertical cross-sectional view of the blow-forming die of the present invention. 1... diver, 2... heating device, 3...
Core, 4...Heating device.

Claims (1)

[Claims] 1. A blow molding method for poly-4-methyl-1-pentene, in which poly-4-methyl-1-pentene is
After melting at a temperature of 200-350℃, the temperature of the diverging shaft is 200-350℃, and the temperature of the core is 100-350℃.
Poly 4-methyl-1 characterized by being extruded through blow molding dies independently set at 350°C.
- Penten blow molding method. 2. A blow molding die characterized by comprising a die buttock equipped with a die buttock heating device and a core equipped with a core heating device.