JPH01136706A - Molding of multi-layer parison in blow molding and its device - Google Patents

Abstract

PURPOSE:To prevent melt fractures produced on the flow path from a confluence portion to an outlet slit, by extruding a inner layer resin of high viscosity and a outer layer resin of low viscosity separately and adjacently from a head body into the atmosphere and laminating it immediately thereafter. CONSTITUTION:A resin plasticated in a main extruder 21 is extruded to the outside of a head body 1 through a inner layer outlet slit 15. On the other hand, the resin for an outer layer parison top is plasticated in a sub-extruder 20 and stored in the chamber 22a of an accumulator 19, an actuator 25 is set up in conjunction with a cylinder 23 for inner layer and extrudes the resin for outer layer being in the accumulator 19. While the resin for outer layer is extruded from a cylindrical path 18, it is laminated on the swell-shaped surface of the resin for inner layer extruded from the outlet slit 15, so that a beautiful laminating is continuously realized.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a multilayer parison forming method and apparatus in blow molding.

Conventional technology In conventional blow molding, multilayer parisons are formed by plasticizing the resin in an extruder, then feeding the resin into the entire head to form an inner layer parison and an outer layer parison. ! 1 are successively merged and laminated in a head, extruded through an exit slit to form a multilayer parison, and this is blow-molded in a mold. And by this blow molding, gas.

Small food containers with barrier properties and cosmetic bottles with good appearance are molded, but the development of multilayer gasoline tanks with gas and barrier properties is the main focus for molding large products such as automobile gasoline tanks. However, as the size of the product increases, it is impossible to mold it using extrusion molding, and high-speed parison molding is required. In order to ensure high speed and accurate parison wall thickness distribution, the multilayer head is implemented as an intermittent multilayer parison molding method in which each /1liy is extruded with a ring plunger.

One point that the invention is trying to solve is that, among conventional blow-molded products, small products such as cosmetic bottles have good skin, but large molded products have poor skin and poor appearance. . As a method to improve the skin's appearance, there is multilayer molding using a nine-layer parison, which combines an outer layer resin with good surface properties (mainly low viscosity) and an inner layer resin (high molecular weight, high viscosity) with drawdown resistance. The reason why your skin is bad is the following ((A9).
- In order to prevent this, it is necessary to extrude the parison from the head quickly, but since the inner layer resin and outer layer resin are merged in the head and extruded as a multilayer from the exit slit, there is a flow of lamination from the merge section to the exit slit. When this laminated layer is extruded at high speed, turbulence occurs in the laminated flow, and when the high viscosity inner layer resin adheres to the wall surface where the low viscosity outer layer resin flows, the adhesive force of the inner layer resin is large, so the tail cannot be removed easily. It was not possible to obtain a parison with good pulling texture, and in addition, it was developed to extrude at high speed, which is an essential method for large-scale molding. The reason for this was that the flow of the stack up to the slit was even more disturbed.

The present invention utilizes the difference in viscosity between the inner layer parison and the outer layer parison to be laminated, and the tension caused by the expansion of the inner layer parison that occurs when the inner layer parison is extruded at high speed, for the stacking pressure against the outer layer parison. The multilayer parison is The outer layer is a resin that improves the lamination state and has good surface properties such as smoothness, texture transferability, and paintability, and the inner layer is a high molecular weight and high viscosity resin that is resistant to drawdown (the main material is a multilayer parison). The purpose is to effectively mold a multilayer parison that can produce large-sized blow-molded products with beautiful skin even through high-speed and intermittent extrusion, and in which the wall thickness ratio of the outer layer to the inner layer is less than one-third. This is a dangerous invention.

Ninth Means for Solving the Problem The present invention uses resin for the inner layer and resin for the outer layer in the head body (1).
When the inner layer resin is extruded, the outer layer parison (Ro) is extruded from the head body (1) using the product pressure generated by the balancing effect of the inner layer parison (A). ) to the inner layer parison (A).

The ring (5) or CI die (6) attached to the lower part of the head body +1) is fitted into the head body (1) so that it can be raised and lowered, and the next ring plunger (2) and flow pin (4) are attached.
A chamber is formed between the flow bin (
4) Attach the trapezoidal core (8) to the lower end of the core (8).
8) and the lower end of the ring (5) or the lower end of the guide (6), an inner layer outlet slit (toward) communicating with the chamber (2) is formed downwardly and outwardly, and the die ( 6
) and the die chip support ()) with an outer layer exit pickpocket.

The outer layer is formed with a taper a*' along the swell shape formed in the inner layer parison (A) when the resin for the inner layer is extruded from the inner layer outlet slit section (2). It extends from the exit of the exit slit member.

According to the present invention, the inner layer resin stored in the lower chamber (to) of the head body (1) comes out from the inner layer exit slit (to) to the outside of the head body (1) and is transferred to the inner layer parison (a). When this occurs, a swell shape is formed due to the ballast effect, and the outer layer resin spreads from the outer layer loss slit part to the head body (1
), and at the same time, due to the stacking pressure generated by the ballast effect of the inner layer parison (a) and the taper α extended to the outlet of the outer layer exit slit (18), the outer layer parison (b) is pushed out of the inner layer parison (i). They are laminated along the swell shape of j.

Example Embodiments of the present invention will be described with reference to the drawings.

Example 1 What is shown in FIG. 1 is the molding of a two-layer parison of a resin with melt adhesive properties, for example, the base material is polyolefin resin, and the outer layer is a resin of the same type with improved appearance or an elastomer resin of the same type. Furthermore, it is a laminated part of a device that uses materials such as polymer alloys.

(!) is a cylindrical head body, and a first annular passage (to) through which the inner layer resin passes is bored in the upper part of the inner surface, and the first annular passage is installed outside the head body (1). C! Aperture of υ (
21m). A ring plunger (2) is fitted coaxially in the head body (1) so as to be movable up and down, leaving a narrow passage (a1) communicating with the first annular passage (to), and a ring plunger (2) ), and a flow bin (4) is fitted coaxially through the guide plug/jar (31'e) so that it can be raised and lowered, and a ventilation passage (2) is fitted in the center of the flow bin (4).
is formed. (5) is a T-ring attached to the lower end of the head body (1), and a heat insulating material (
The gouy (6) is attached via 13. The heat insulating material I sets the temperature of the resin of the inner layer and the outer layer to an appropriate temperature.
This is effective in reducing heat conduction. A truncated cone-shaped core (8) is fixed to the lower end of the flow bin (4), and the core (8) is connected to the air passage (to) and has a 7t#ll
An air hole (8a) is provided. and Flobin (4)
, guide plunger (3), ring plunger (2)
) A chamber serving as a resin passage is provided between the inner surface of the peripheral ring (5) and the guide (6) at the lower end of the core (8) and the surface of the core (8).
(to) and the cha/bar (to).
Next, the inner layer exit slit ()sacJ, which is shaped so that the cross section is in the shape of a square and becomes gradually narrower toward the lower end, in the direction along the swell shape when the inner layer parison (A) is extruded. Form radially outward.

(7) is attached to the lower part of Goui (6) with a die tip chip boat concentric with the outer diameter of the lower part of Goui (6).
A second annular passage through which the outer layer resin passes is formed between the inner surface of the inner surface and the outer surface of the Daitebuna port (7), and nine cylindrical passages al communicating with the passage are formed. Furthermore, an adjustment ring (II) is fitted into the inner surface of the die tip support (7),
The gap eccentricity is adjusted by this adjustment ring. (
9) is a die fy pipe, which is attached to the lower surface of the Daite Buna boat (7) by the presser ring (14), the upper surface of the die tip (9) is in contact with the adjustment ring a1, and the upper inner surface is a cylindrical resin passage that becomes the outer layer outlet slit. The lower part of the inner surface is formed into a bar-shaped taper ae close to the outlet of the inner layer outlet slit section αS, so that it becomes an extension of the inner layer outlet slit section α, that is, No. 2 annular passage (2). The outer layer parison (B) extruded from the cylindrical passage α type through the inner layer exit slit part A5 from the chamber (to) can be laminated accurately along the shape expanded by the swell effect of the inner layer parison (A). The second part is formed into a shape.
The annular passage (to) is installed outside the guide (6) and is connected to the nine sub-extruder (a).
). The lower section of the core (8) includes a core,
Puka and adjustment bolt α31! - The adjustment bolt (1) is formed so that the eccentricity can be adjusted from the inside of the inner layer exit slit part ← 3. (2) is the plunger inside the Achim letter hand, @ is the ring plan for extruding the inner layer resin. Jar (2) Cylinder for inner layer that can be raised and lowered completely, (Foundation)
is the control cylinder for the parison, and (to) is the tth plunge (2) that extrudes the outer layer resin in the sub-extruder.
) is an actuator that operates.

Next, the operation of Example 1 will be explained.

The resin that is plasticized by the main extruder Q and extruded from the opening (21a) flows downward from the first annular passage of the head body (1) through the narrow passage can' and is sent into the chamber (toward). It will be done.

Depending on the amount of resin sent into the chamber (to) for the inner layer, the coaxially arranged ring plunger (2) is pulled up by the inner layer cylinder (to), and when a predetermined amount is reached, the inner layer cylinder (to) is pulled up. ), the ring plunger (2) is lowered by the ring plunger (2), so the resin in the chamber (to) passes through the inner layer exit loss slit part αI and reaches the head body (1).
) is pushed outside. The thickness distribution on the circumference is adjusted to be uniform by adjusting the adjustment bolt at the bottom of the core (8), so the resin that has passed through the inner layer exit slit (L!9) has a uniform thickness and has a balancing effect. By WeII!!
The shell-shaped metal inner layer parison (A) is extruded from the inside. On the other hand, the resin that will become the outer layer parison (b) is plasticized in the sub-extruder (2), and then
The resin is stored in the bar (22a), and the actuator (1) is set in conjunction with the inner layer cylinder (22), and operates synchronously to push out the outer layer resin within the accumulator haze. Then, the resin for the outer layer is applied to the second annular passage (F) and the cylindrical passage (I).
At this time, the resin for the outer layer, that is, the outer layer parison (
b) The surface of die chip (9) is 2. It conforms to the shell shape of the inner layer parison (A) along the taper αe of the P shape,
They are beautifully stacked and extruded continuously without being collapsed by the stacking pressure of the inner layer parison.

Example 2 Summary Figure 2 shows a 3PJ parison molding device.
As shown in the figure, the inner side of the ring (5) attached to the lower end of the head body (1) of the two-layer parison forming apparatus is bulged to form a bulge (5a). ), ring plunger (2) and guide plunger (3)
) and the flow bin (4), and between the lower surface (5b) of the bulge (5a) and the outer surface (8b) of the core (8), following the chamber phase. The cross section is in the shape of a square, and as it goes to the lower end, it is gradually shaded so that it becomes narrower, forming a loss slit portion α1 with an inner layer. Attached to the bottom of the ring (5) is a third annular passageway (toward) for the intermediate layer or adhesive layer between it and the die (6).
A cylindrical passage (α) is formed which serves as an outer layer exit slit communicating with this, and the third annular passage (to) is installed outside the die (6) and is used as a sub-layer for the material for the intermediate layer or the adhesive layer. Connected to the extruder. A spacer (to) is attached to the bottom of the die (6), and the die (6) and spacer (to) are attached.
A second annular passage for the outer layer resin and a companion outer layer resin passage (2) connected thereto are formed between the outer layer resin passage and the outer layer resin passage.
The cylindrical passage A communicates with the middle of the cypress. The second annular passage (b) is connected to an extruder (not shown) installed outside the head body (1). An adjustment ring 1 is fitted into the inner surface of the die chip support (7) attached to the lower part of the spacer (to). (9) is a die tip attached to the lower surface of the die tip support (7) by a presser ring α4, the upper inner surface constitutes the lower end of the cylindrical resin passage α barrel, and the lower inner surface is tapered (le).

To explain the effect of Example 2, as in Example 1, the inner layer resin in the chamber (2)
The resin for the intermediate layer or the adhesive layer is extruded from the cylindrical resin passage α barrel through the third annular passage (to) by the sub-extruder kane, and the resin for the outer layer is extruded from the extruder ( (not shown) to the outside through the second annular passage (b), join with the resin for the intermediate layer that has flown from the cylindrical resin α through the first resin passage (to), and be pushed out. Then, the resin for the inner layer is extruded to the outside and the inner layer parison (A) is formed.
At this time, the resin for the intermediate layer and the resin for the outer layer which have been extruded at the same time are merged and laminated, and the outer layer parison is laminated with VC on the surface of the swell shape. ) along the taper αe to fit the swell shape of the inner layer parison (a), and the inner layer balin/
Beautiful without being destroyed by the stacking pressure; 3
A layer parison is formed.

effect According to the invention, therefore, the stacking of multilayer parisons is possible.

The high-viscosity inner layer resin and the low-viscosity outer layer resin are extruded from the head body separately and in close proximity to each other into the atmosphere without merging inside the head body. There is no problem of melt fracture on the flow path from the merging part to the exit slit when merging at the outlet slit, and there are no viscosity restrictions on the selection of the outer layer resin, allowing the molding of high-quality multilayer parisons. The stacking pressure generated by the ballast effect of the inner layer parison during the next stacking process is utilized, and the taper is formed in the nine-extended part close to the outer layer exit slit, which causes the inner layer parison to expand (balance effect).
Alternatively, the outer layer parison can be protected against the lamination pressure and the two can be effectively crimped together without causing deformation or the like. Furthermore, the outer layer resin can be extruded at a high temperature with good surface properties, and in combination with effective and accurate lamination of the outer layer parison to the inner layer parison, a product with an excellent appearance can be molded. In addition, the present invention is an effective means for laminating a thin outer layer resin onto an inner layer resin that has a base resin, and since the expansion rate due to the ballast effect of the inner layer parison is constant under the same resin pressure, the pressing force against the outer layer parison is constant. Then,
It is possible to maintain good lamination strength and contribute to the molding of good products. l? In the present invention, it is not necessary to extrude the outer layer resin with high viscosity and high resin pressure, which corresponds to the high viscosity and high resin pressure of the inner layer resin, as in the conventional case of merging in the head main body, and the outer layer resin can be extruded at low pressure. This allows the device to be made more compact. A further noteworthy advantage is that the difference in viscosity between the resins does not become a problem when the layers are combined. Therefore, the inner layer resin that serves as the base material is set at a high viscosity with drawdown resistance in a low temperature range, and the outer layer resin is set at a temperature in a low viscosity high temperature range to improve smoothness, grain transferability, and paintability. The material can be selected, and the inner layer resin can be freely set with nine conditions, emphasizing drawdown resistance. Also, since the problem of appearance, which is considered to be a weak point of blow molding, has been solved, useful large blow molded products can be provided in wide range at low cost.

te, the resin used as the outer layer resin to improve the surface is 3-5% higher than the ultra-high molecular weight polyethylene used as the base material.
Although it is about twice as expensive, the present invention can form a multilayer parison in which the thickness of the outer layer resin is one-third or less of that of the inner layer resin, so the economic effect is also very large.

[Brief explanation of the drawing]

The figures show embodiments of the present invention, and FIG. 1 shows embodiment 10.
FIG. 2 is a sectional view of the two-layer parison forming apparatus, which is an enlarged sectional view of the lower part of the head body of the apparatus shown in FIG. Figure 3 shows Example 2
FIG. 2 is an enlarged cross-sectional view of the lower part of the head main body of the 03-layer parison forming apparatus. Code: 1... Head body 9...
・・・・・・ DaiTep 2 ・・・・・・・・・ Ring plunger 10 ・・・・・・・・・ Adjustment ring 3 ・・・・・・・・・ Guide plunger 1) Song-Song CoreTep 4・・・・・・・・・
・・Flow pin 12・・・・・・Adjustment bolt 5・・・・・・Ring 13・・・・・・
...Insulating material 5a...Bulging part
14...... Presser ring 5b-”°°°
°゛°° Lower surface 15... Inner layer outlet 6... Gui
Slit part 7 ...... Taichi Kate juice 16 ...... Taper 8 ・
········ · a
(7-shaped inner surface) 8a... Exhaust port (cylindrical passage) 26 Spacer 19 Achim letter 27
......Outer population 19a...
...Opening 28...Resin passage 20
・・・・・・・・・ Sub-extruder 29 ・・・
......Outer layer resin passage 21... Main extruder 30... First annular passage 21a
・・・・・・・・・Opening 31・・・・・・・・・
・Narrow path 22・・・・・・Plunger
32 ...... Ventilation path 22a...
・・・・・・ Chamber 33 ・・・・・・・・・ Chamber 23 ・・・・・・・・・ Inner layer cylinder
34 ...... Second annular passage cylinder 25 ...... Actuator I
・・・・・・・・・ Inner layer parison (plunger
(B) Outer layer parison (2)) Inventor: Hiroshi Takano Takayuki Koji All four parts patent applicant: Shatai Kogyo Co., Ltd.

Claims (2)

[Claims] (1) The resin for the inner layer and the resin for the outer layer are extruded separately and close to each other from the head body (1) to the outside, and when the resin for the inner layer is extruded, the lamination pressure generated by the parallax effect of the inner layer parison (a) is used. A multilayer parison forming method in blow molding, characterized in that an outer layer parison (b) is laminated on an inner layer parison (a) on the outside of the head body (1). (2) Ring (5) attached to the bottom of the head body (1)
) or a die (6), a ring plunger (2) fitted in the head body (1) so as to be able to rise and fall freely, and a flow pin (
A trapezoidal core (8) is attached to the lower end of the flow pin (4), and a trapezoidal core (8) is formed between the core (8) and the lower end of the ring (5) or the die (6).
An inner layer outlet slit (15) communicating with the chamber (33) is formed downwardly and outwardly between the lower end of the die (6) and the die chip support (7), and an outer layer outlet slit (15) is formed between the die (6) and the die chip support (7). The slit part (18) is connected to the inner layer exit slit part (15).
When the resin for the inner layer is extruded from the inner layer outlet slit part (15), the inner layer parison (a)
A multilayer parison forming apparatus for blow molding, characterized in that a taper (16) extending along the swell shape formed in the outer layer exit slit section (18) is provided.