JP2761595B2 - Multilayer parison extrusion apparatus and method - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus and a method for extruding a multilayer parison, and more particularly to an apparatus and a method for extruding a multilayer parison provided with means for determining the state of an inner layer by infrared rays.

[Prior art] Conventionally, mobile hydrocarbon containers such as fuel tanks for automobiles have been improved in terms of space utility, weight reduction, rust prevention on inner and outer surfaces, improved impact resistance, and labor saving in production processes. Plastic tanks have begun to replace metal tanks. However, plastic tanks have a problem of permeability of the contents such as gasoline (including alternative fuels such as gasohol), and in fact, HDPE (high-density polyethylene) single-layer tanks constitute gasoline itself. Because of high affinity with hydrocarbons, the amount of permeation tends to be large.

Gasoline permeation is strictly regulated for environmental protection.
It is necessary to take measures to prevent gasoline permeation in plastic tanks.

The gasoline permeation-preventing means, processing technology according to an F ₂ gas or SO ₃ gas is established. However, this treatment technique is not generally used because these gases are harmful to the human body.

Another means employed is to extrude and blow-mold the multilayer parison to produce a multilayer plastic fuel tank.

Conventionally, a three- to five-layer multi-layer plastic fuel tank has been invented. In each of these layers, the outer layer is HDPE and the inner layer is
A barrier forming resin such as PA (polyamide or nylon) or ethylene vinyl acetate copolymer resin.

Also, if these expensive barrier layers are laminated on the entire surface of the product tank, the layers up to the upper and lower pinch-off layers will be multilayered, resulting in reduced strength, high cost, and difficulty in recycling. Partial multi-layering (or referred to as important multi-layering) is performed.

In this case, it is necessary to guarantee that the necessary parts are always multilayered.

As a means therefor, there are two methods, a method (1) for controlling the source flow of the extruded amount in a parison extruder and a method (2) for 100% nondestructive inspection in the state of the parison or the product tank.

As the method (1), a method of controlling the torque (current) of the extruder and the pressure obtained by subtracting the resin pressure immediately before the die from the resin pressure at the tip of the extruder is disclosed. (Dr. Reiner H
egie, “COEXTRUSION BLOW MOULDINGS OF LARGE HO
LLOW ARTICLES, "COEX EUROPE'86, p.368) (1A).

However, this method is based on the assumption that the torque (current) of the extruder and the extruded amount are in a proportional relationship. Therefore, if the plasticization condition is changed by changing the extruded resin temperature and the like, the proportional relationship is lost. Correction must be performed, and it is difficult to apply under all molding conditions.

Therefore, as an improved method (1), for example,
As described in -23212, a multi-layer blower characterized in that the operation timing of each solenoid valve on the injection side is shifted by a timer and the rising characteristic of each injection cylinder is controlled by a time constant generation type controller. A parison head controller for a molding machine has been proposed (1B).

However, there is a problem in controlling the parison extruder to guarantee the entire laminated state of the important multilayer blow products.
0% reliability cannot be expected.

As method (2), there is a method of indirectly monitoring the inner layer (barrier layer) during molding.

For example, as an inner layer detecting means at the time of molding, a method of monitoring the accumulator position of the inner layer (adhesive, PA) and the pressure of each resin with respect to the position of the accumulator of the outer layer material and keeping each within a certain allowable width. (2A). This method allows indirect non-destructive parison layer management. Further, it is also possible to cancel the influence of disturbance such as resin clogging and fluctuation of plasticizing conditions. As important as the inner layer confirmation at the time of molding, there is a nondestructive inspection technique of the inner layer of the molded important multilayer plastic fuel tank. This can be theoretically determined by capturing the difference in resin density using ultrasonic waves (2B).

However, the former method has a problem that sufficient reliability cannot be expected because the method is an indirect detection method. In addition, there is a disadvantage that the latter ultrasonic examination cannot be performed without contact,
Immediately after blow molding, it is difficult to measure the state of the inner layer by bringing an ultrasonic probe into contact with a still insufficiently cooled plastic fuel tank via a liquid contact medium at the manufacturing site. In addition, the ultrasonic inspection has a problem that one inspection range is narrow, and it takes too much time to perform an entire inspection.

Further, as another example of (2), as described in JP-A-63-260417, a detection medium such as iron powder or short glass fiber is mixed in the inner layer material (barrier layer material) in advance. After the parison molding, there was a method (2C) of detecting the inner layer material distribution from outside using a magnetic sensor, an ultrasonic sensor, or the like.

However, this method, as a matter of course, cannot avoid harmful effects due to the presence of the detection medium in the parison itself or in the blow-molded product, and has a problem.

[Problem to be Solved by the Invention] An object of the present invention is to measure the existence state of an inner layer (barrier layer) that cannot be directly observed in an extrusion process in a non-contact and non-destructive manner, and feed back the result to form a multilayer parison. An object of the present invention is to provide an apparatus and method for extruding a multi-layer parison that enables accurate extrusion control.

Another object of the present invention is to provide an apparatus and method for extruding a multi-layer parison, which comprises means capable of determining whether or not the entire surface of the parison or blow-molded article is laminated as designed in a short time. Is the thing.

[Means for Solving the Problems] According to the present invention, in a multi-layer parison extrusion molding apparatus in which an outermost layer and at least one inner layer having a higher plasticization temperature are laminated, plasticization of the extruded inner layer is performed. Extrusion of a multilayer parison, comprising: infrared detecting means for selectively detecting infrared light emitted from the inner layer having the highest temperature; and determining means for determining the presence state of the inner layer based on a detection signal of the infrared detecting means. A molding device (claim 1) is provided.

According to the present invention, in the extrusion molding step of the multilayer parison in which the outermost layer and at least one inner layer having a higher plasticization temperature are laminated, the plasticization temperature is the highest among the inner layers extruded by the infrared detecting means. 3. A method for extruding a multilayer parison, wherein infrared rays emitted from an inner layer are selectively detected, and the position of the inner layer is detected based on a detection signal of the infrared detecting means. An inner layer position data detected by the multilayer parison extrusion molding method is fed back to the inner layer extrusion control device, and the inner layer extrusion molding control is performed based on the inner layer position data. Claim 3) is provided.

Hereinafter, the present invention will be described in detail with reference to examples.

FIG. 1 is a sectional and circuit diagram showing an accumulator head 1 and a control circuit of a five-layer parison extrusion molding apparatus according to an embodiment of the present invention.

Usually, in the case of a three-layer parison, it is configured symmetrically with the first layer / second layer / third layer (= first layer) in the thickness direction when viewed from the outside or the inside.

 Similarly, in the case of a five-layer parison, the first layer / second layer / third layer / fourth layer / fifth layer (= second layer) (= first layer) are symmetrically configured.

However, if necessary, it is also possible to adopt an asymmetric configuration in the thickness direction, for example, by providing a weather-resistant resin layer on the outer surface of the tank and a solvent-resistant resin layer (barrier layer) on the inner surface. However, it is inevitable that the extruder becomes complicated. In addition, it will be necessary to devise a resin component and an adhesive constituting each layer.

However, the plasticizing temperature of the resin forming the inner layer whose existence state is to be determined must be the highest than the plasticizing temperature of the other layers.

This is because, as will be described later, it is necessary to selectively detect infrared rays emitted from the inner layer immediately after extrusion in the parison from the outside. That is, unless the plasticization temperature is the highest, infrared energy radiated from the inner layer cannot be detected.

In this embodiment, a case of a symmetrical three-type five-layer parison will be described.

That is, HDPE does not have a polar group and thus has poor adhesion, and it is necessary to interpose an adhesive layer with PA. Therefore, when an adhesive layer is added to the layer, a symmetrical three-type five-layer structure is obtained.

That is, when viewed from the outside, as described above, the first layer / second layer / third layer / fourth layer / fifth layer (HDPE) (adhesive layer) (PA) (adhesive layer) (HDPE) . Here, the first layer is the fifth layer, and the second layer is the fourth layer.

FIG. 2 is a sectional view taken along the line II-II 'of FIG. 1, and FIG. 3 is an enlarged sectional view of a main part showing a resin passage around the annular nozzle.

The structure of the accumulator head 1 is roughly as follows.

1, 2, and 3, the first layer and the fifth layer HDPE are supplied from the extruder 11, pass through the annular resin passage 8, pass through the resin storage chamber 2, and are pressed by the ring plunger 5. Then, it reaches the resin passage 10. Second
The adhesive which becomes the layer and the fourth layer is supplied by the extruder 12, is extruded by the plunger 7 through the accumulator 4 and the adhesive resin passage 42, and is formed in the resin passages 10A and 10B. The PA serving as a barrier layer is supplied from the extruder 13, is extruded by the plunger 6 through the accumulator 3 and the barrier resin passage 41, and is supplied to the resin passage 10 to be stratified.

That is, a structure in which three types and five layers of parisons are finally extruded in a slit (annular nozzle) 16 between the die 14 and the core 15. Here, 40 is a core, 45 is a support part, and 61 is an infrared sensor (CCD camera).

The essential part of the present invention lies in the means for detecting / determining the inner layer existence state described below.

HDPE temperature immediately after extruding parison 50 is 190-210
° C, while PA is 230-250 ° C, with the adhesive layer in between. Therefore, the infrared rays emitted from the PA or the adhesive layer inside pass through the HDPE and come out to the outside.

The infrared rays are separated at 180 ° C. and (200 ° C.) 220 ° C. and selectively detected using a high-sensitivity infrared sensor (here, a CCD camera 61) provided with an infrared filter 61A that passes only infrared rays.
The measurement is sometimes omitted because the adhesive layer has a small thickness and a small output, so that the measurement is difficult. After comparing each measured output with the normal pattern stored in the normal pattern storage 64 in the discriminator 63 via the image processing unit 62, the difference from the set value, whether the DEV is within a certain range, that is, YES Or NO, if YES, YES indicator 65
Is displayed, and in the case of NO, the DEV signal is sent to the inner layer ring parison control circuit 72. Inner layer ring parison control circuit 72
Outputs a correction output signal corresponding to the DEV signal to the servo valve 3.
1 and 32, and the hydraulic pressure controlled by the servo valves 31 and 32 is transmitted from the hydraulic pressure source 30 to the hydraulic cylinders 19 and 20, respectively. As a result, plungers 6 and 7 become ring plungers 5
At the same time as the operation of (1), the thickness of the barrier layer and the adhesive layer is adjusted to a set value of 0 to a set amount. The outer layer (the first layer and the fifth layer) is a mechanism controlled independently of the inner layer, and the resin extruded by the extruder 11 is accumulated in the resin storage chamber 2 and the position where the ring plunger 5 rises is determined. Outer parison control circuit 71 proportionally triggered by detecting plunger position detector 70
The hydraulic pressure is supplied from the hydraulic pressure source 30 to the hydraulic cylinder 18 through the path 34 via the servo valve 33 controlled by a signal output from the hydraulic cylinder 18, and the ring plunger 5 is pressed down by the hydraulic cylinder 18, and At the same time, the multi-layer parison 50 is extruded by the plungers 6 and 7 described above. Ring plunger 5
A trigger signal is sent from the outer layer parison control circuit to the inner layer ring parison control circuit to synchronize the operation of the plungers 6 and 7 with pressure.

Needless to say, the present invention can further improve the accuracy by combining with the above-mentioned prior arts (1) and (2).

HDPE used in the present invention is, for example, a so-called Philips method polyethylene produced by a medium pressure polymerization method, and trade names include BASF Lupolen (registered trademark) 4261A and Showa Denko Shorex (registered trademark) Super 4551H. Polyamide 6: CM1046 [Toray Ramilan (registered trademark)] or the like was used for PA as a nylon resin.

In the present invention, only the self-radiated infrared rays are measured. However, it is considered that a light source such as a laser beam may be separately provided to selectively determine the presence state of the inner layer by transmitted light or reflected light.

[Effects of the Invention] All of the above objects are achieved by implementing the present invention.

In other words, immediately after extrusion, it is possible to measure the existence state of each inner layer such as a barrier layer in a non-contact and non-destructive manner with respect to the multilayer parison. I can do it.

[Brief description of the drawings]

1 is a sectional view and a circuit diagram of an embodiment of the present invention, FIG. 2 is a sectional view taken along the line II-II 'of FIG. 1, and FIG. 3 is an enlarged sectional view of a main part showing a resin passage around an annular nozzle. 1 ... accumulator head, 2 ... resin storage chamber, 5, 6, 7 ... plunger, 8 ... annular resin passage, 11, 12, 13 ... resin extruder, 16 ... slit (annular nozzle), 18 , 19,20 …… Hydraulic cylinder, 31,32,33 …… Servo valve, 40 …… Core, 41 …… Barrier resin passage, 42 …… Adhesive resin passage, 50 …… Parison, 61 …… Infrared sensor (CCD camera).

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI B29C 49/22 B29C 49/22 (56) References JP-A-63-260417 (JP, A) JP-A-62-164522 (JP) , A) JP-A-63-262225 (JP, A) JP-A-61-215033 (JP, A) JP-A-2-80427 (JP, U)

Claims (3)

(57) [Claims] In a multilayer parison extrusion molding apparatus in which an outermost layer and at least one inner layer having a higher plasticizing temperature are laminated, radiation is radiated from the inner layer having the highest plasticizing temperature among the extruded inner layers. A multi-layer parison extrusion molding apparatus, comprising: infrared detection means for selectively detecting infrared light; and determination means for determining the presence state of the inner layer based on a detection signal of the infrared detection means. 2. In the extrusion process of a multilayer parison in which an outermost layer and at least one inner layer having a higher plasticizing temperature are laminated, the plasticizing temperature of the inner layer extruded by infrared detecting means is the highest. A method for extruding a multilayer parison, wherein infrared rays emitted from an inner layer are selectively detected, and the position of the inner layer is detected based on a detection signal of the infrared detecting means. 3. The inner layer position data detected by the multilayer parison extrusion molding method according to claim 2 is fed back to an inner layer extrusion controller, and the inner layer extrusion molding is controlled based on the inner layer position data. Extrusion molding method of multilayer parison.