JPS63142242A - Method and apparatus for inspecting heat resistant multilayer container made of synthetic resin - Google Patents

Abstract

PURPOSE:To judge the quality of a product in a non-destructive manner, by projecting ultraviolet rays on the mouth part of a heat resistant multilayer container made of a synthetic resin and receiving transmitted ultraviolet rays to detect ultraviolet rays having a specific wavelength. CONSTITUTION:A heat resistant multilayer container 3 is molded by laminating PET (polyester resin) as a main resin and a polyallate resin as a heat resistant resin. Said main resin is more excellent in ultraviolet ray transmissivity as compared with the heat resistant resin and this property is utilized to perform inspection. In this inspection method, ultraviolet rays are passed through an optical quartz fiber 22 to be throttled by a slit 32 and projected on the upper end part 33 of the mouth part of the container 3. The light transmitted through the upper end part 33 of said mouth part is received by the quartz fiber 24 for a detector and the specific wavelength thereof is extracted by a sensor part and converted to an electrical signal to detect the transmissivity of ultraviolet rays. Then, the adhesion state of the main resin and the heat resistant resin is judged from the transmissivity of ultraviolet rays. Since the transmissivity of ultraviolet rays is detected, the quality of the container can be certainly judged within a short time.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field of the Invention) The present invention relates to a method and apparatus for inspecting a heat-resistant multi-layered container made of synthetic resin, which enables non-destructive determination of the quality of the product.

(Technical background of the invention and its problems) The market for containers made of synthetic resin, particularly containers made of PET (polyethylene terephthalate), continues to expand, mainly for large soft drink containers. Recently, the need for heat-resistant multilayer containers has increased, and in response, research and development are progressing. The manufacturing method for general synthetic resin containers (including heat-resistant multilayer containers) will be explained with reference to FIGS. (A)), then hold the mouth of the parison l in the mold 2 of a stretch blow molding machine (not shown) (see Fig. 6 (A)).
B)), by stretch blow molding (Fig. 6 ([:))
, a container 3 with a predetermined shape can be obtained (see FIG. 6(D)
)).

As is clear from Figure 6, the problem with heat-resistant multilayer containers is that the mouth of the container remains in the injected state without being stretched.
In order to improve these problems, conventional methods include (a) heating and crystallizing the mouth, (b) forming the mouth by two-color molding of heat-resistant resin, and (C) heat-resistant. There are two methods in which the outer periphery of the mouth part is preformed using a plastic resin, etc., and the mouth part is made by insert molding using this preformed product. The mouth part to be manufactured is
Shape deformation is likely to occur during the heating crystallization process, so not only are the threads at the mouth and thread root diameter 9 dimensions not stable, the sealing performance is poor due to deformation of the top surface of the sealing part, and it becomes opaque due to crystallization. It has the disadvantage that it cannot be applied when the entire container must be transparent. Furthermore, since a separate process for crystallization is required, productivity is poor and costs increase.

In addition, the opening obtained by the method (b) above does not have sufficient interlayer adhesive strength between the main resin and the heat-resistant resin, and multiple molds must be prepared in order to manufacture it. , the process becomes complicated and costs increase.

Furthermore, the mouth part manufactured by the method (C) above still does not have sufficient interlayer adhesive strength between the main resin and the heat-resistant resin, and in order to manufacture it, not only multiple molds but also inserts are required. Since a device is also required, a large amount of man-hours and costs are required.

Therefore, as a method for solving the above-mentioned drawbacks, there is a method of making the mouth part by co-injecting the main resin and the heat-resistant resin.

This method requires injection molding conditions between the cavities, that is, a hot runner for uniformly co-injecting the molten resins of the main resin and the heat-resistant resin at a predetermined timing and filling amount. The present applicant has proposed that a portion of the hot runner excluding the hot runner branching point and its vicinity consists of a pair of molten resin channels having the same cross-sectional shape running close to each other, and that there are two wood runners at the hot runner branching point. We have developed a hot runner provided with a region where the resin flows of 2 and 3 are temporarily merged, and obtained a co-injection molding machine to which this hot runner is applied (see Japanese Patent Application No. 252997/1982).

FIG. 7 shows a schematic cross-sectional side view of this co-injection molding machine, and the co-injection hot runner nozzle section 4 has a hot runner nozzle 5 for main resin and a hot runner nozzle 6 for heat-resistant resin. Furthermore, a hot runner main block 7 that supports the co-injection hot runner nozzle section 4, and a spacer block 8. It is equipped with a hot runner sub-block 9 and a heat insulating plate 1O, and a main resin runner 11 is provided in the hot runner main block 7, and a heat-resistant resin runner 12 is provided in the hot runner sub-block 9. It is being At the top of the co-injection hot runner nozzle section 4, there is an ink injection cavity mold 13 which is a mold. A lip cavity mold 14 and an injection core 15 are provided.

Next, a mold for parison 1 is installed in the above-mentioned co-injection molding machine, and the molding process will be described with reference to FIGS. 8(8) to 8(D).

First, the main resin 16 is injected from the main resin hot runner nozzle 5, and the main resin 16 is injected into the injection cavity mold 13.
The heat-resistant resin 17 enters the cavity a formed between the ink injection core 15 and the ink injection core 15 (FIG. 8(A)), and after a short delay, the heat-resistant resin 17 is injected from the heat-resistant resin hot runner nozzle 6 and enters the cavity a. The main resin 16 is press-fitted into the intermediate layer of the main resin (FIG. 8 (B)), and the heat-resistant The distal end portion of the adhesive resin 17 is ejected from the distal end portion of the main resin 16 and covers the distal end surface of the main resin 16 (FIG. 8(C)).

Proceeding further, when the covering heat-resistant resin 17 formed in the previous step reaches the closed part of the cavity b, the heat-resistant resin 17 wraps around along the wall surfaces of the lip cavity mold 14 and the injection core 15 (the first Figure 8 (D)
), a molded body (parison 1) consisting of a mouth part with a five-layer structure and a body part with a three-layer structure can be obtained.

However, it is necessary to judge the performance of a heat-resistant multilayer container made by stretch-blow molding the parison obtained by the method described above, and the criterion for this is that the heat-resistant resin is uniformly present throughout the heat-resistant multilayer container. If so, it is judged as good.

The conventional method of determination is visual inspection, but
There is a drawback that determination cannot be made when the main resin and the heat-resistant resin are the same color or transparent. In addition, destructive testing using sampling can determine pass/fail, but
Compared to single containers, heat-resistant multilayer containers have many manufacturing instability factors, and problems such as a lack of reliability due to the risk of unexpected defects have been resolved.

(Object of the Invention) The present invention was made in view of the above-mentioned circumstances, and the purpose of the present invention is to determine the quality of all products without destroying the product, even when it is impossible to visually determine the quality of the product. An object of the present invention is to provide a method and apparatus for inspecting a heat-resistant multilayer container made of synthetic resin, which enables the inspection of heat-resistant multilayer containers made of synthetic resin.

(Summary of the Invention) The present invention relates to a method for inspecting a heat-resistant multilayer container made of synthetic resin, in which ultraviolet rays are projected onto the upper end of the mouth of the heat-resistant multilayer container, and ultraviolet rays transmitted through the upper end of the mouth are received. However, after extracting and detecting ultraviolet rays of only a specific wavelength, it is output as an electrical signal, and the quality of the heat-resistant multilayer container is determined based on the value. Further, as a device for realizing the above method, a light source device for generating ultraviolet rays, and a device connected to this light source device to transmit the ultraviolet rays and project the light onto the upper end of the mouth of a heat-resistant multilayer container made of synthetic resin. a light-emitting fiber, a light-receiving fiber placed opposite to the light-emitting fiber for receiving and transmitting the ultraviolet light transmitted through the upper end of the mouth, and a light-receiving fiber having a specific wavelength output from the light-receiving fiber. We propose an inspection device for heat-resistant multilayer containers made of synthetic resin, which is equipped with a sensor for extracting and detecting electrical signals, and a processing circuit for receiving and processing electrical signals from the sensors.

(Embodiments of the Invention) The principle of the inspection method according to the present invention utilizes the property that the main resin has superior ultraviolet transmittance at a specific wavelength compared to heat-resistant resins.

Figure 1 shows a heat-resistant multilayer container 1 manufactured by the method described above using PET (polyethylene terephthalate) resin as the main resin and polyarylate resin as the heat-resistant resin.
8 shows the ultraviolet transmittance according to the wavelength of a single container 19 manufactured by the method described above using only PET resin.

As is clear from the figure, the difference in transmittance is noticeable around a wavelength of 350 nm.

Here, P is the main resin used in heat-resistant multilayer containers.
The ET resin is made by polymerizing terephthalic acid or its ester-forming derivatives (e.g., lower alkyl esters, phenyl esters, etc.) and ethylene glycol or its ester-forming derivatives (e.g., monocarboxylic acid ester ethylene oxide, etc.). There is a polyester obtained, and further contains less than about 20 moles of dicarboxylic acids or aromatic dicarboxylic acids such as phthalic acid, isophthalic acid, naphthalene dicarboxylic acid, diphenyl dicarboxylic acids, diphenoxyethane dicarboxylic acids, or adipic acid, sepatic acid, azelaic acid. , aliphatic or alicyclic dicarboxylic acids such as decanedicarboxylic acid and cyclohexanedicarboxylic acid, or copolymerize less than about 20 moles of glycol or trimedylene glycol, propylene glycol, tetramethylene glycol, neopentyl glycol, hexa Aliphatic or alicyclic glycols such as methylene glycol, dodecamethylene glycol, and cyclohexane dimetatool; or aromatic diols such as bisphenols, hydroquinone, and 2,2-bis(4-β-hydroxyethoxyphenyl)propane. It may be polymerized. Also, P-hydroxyethoxybenzoic acid, α
It is also possible to copolymerize oxyacids such as -oxycaproic acid, lower alkyl esters of oxyacids, and other ester-forming derivatives. Next, polyarylate resins that are heat-resistant resins include blend polymers of polyarylate and polyethylene terephthalate.

FIG. 2 is a perspective view of the general configuration of the inspection device, and FIG. 3 is a cross-sectional side view of the structure of the sensor section.

This inspection device 20 uses a mercury/xenon lamp (not shown)
a light source device 21 that generates ultraviolet rays and visible rays; and a quartz-based fiber 2 for light with a diameter of 2+n+n that is connected to this light source device 21 to condense and transmit the ultraviolet rays and visible rays.
2 and a diameter 1 for receiving the projected light.
It has a light-receiving section 2δ having a quartz-based fiber 24 for a detector of mm and a guide 25 that supports the quartz-based fiber 24 for a detector. Here, the reason why a mercury/xenon lamp is used as a light source is to increase the amount of light in the ultraviolet region. Further, when aligning the ends of the light quartz fiber 22 and the detector quartz fiber 24, it is easy to align the ends of the light quartz fiber 22 and the detector quartz fiber 24 because visible light is emitted, although it cannot be seen with ultraviolet light alone. Further, in the middle of the quartz-based fiber 24 for the detector, there is a sensor section consisting of an interference filter 27 that transmits only a specific wavelength (350±1 onm) and a photoelectric conversion type gallium phosphide element 28 that receives the ultraviolet rays and visible light. 29, and an amplifier (not shown) and a determination circuit (
A determination unit 31 consisting of (not shown) is provided.

Due to the molding process, if a heat-resistant resin layer is present at the upper end of the mouth of the container, it means that there is a heat-resistant resin layer over the entire container. It is even more effective if measurements are taken over a period of time. Generally, the mouth of the container is often equipped with a screw to seal it with a cap, so measurements cannot be taken at the screw, but the rubber gasket installed inside the cap can be crushed to seal the container. Measurement is performed using the cylindrical shape of the container, which has no threaded part at the upper end of the mouth, which is provided for the purpose of increasing the effectiveness. However, the fourth
As shown in the figure, when the light quartz fiber 22 and the detector quartz fiber 24 are arranged in a straight line using the visible light, the light generated from the light source device 21 is transmitted to the light quartz fiber 22. The light is projected through the slit 32 and is focused on the upper end 33 of the mouth of the container 3 . The light transmitted through the mouth upper end 33 is received by the detector quartz fiber 24, and the sensor part 29
A specific wavelength (350+10nm
), and when this specific wavelength of light is detected by the gallium phosphide element 28, the gallium phosphide element 28 generates a voltage, which is amplified by an amplifier and input to the judgment circuit to determine whether the container 3 is good or not. is determined.

The results of specific measurements using the above-mentioned inspection apparatus and method will be explained using FIGS. 5(A) to 5(C).

PET (polyethylene terephthalate) [Mitsui PET Resin J125] is used as the main resin, and U polymer consisting of a blend of polyarylate and polyethylene terephthalate [Unitika %1I8400] is used as the heat resistance.
Measurements were taken over the entire circumference (0° to 360°) of the upper end of the mouth of a heat-resistant multilayer container manufactured by the container manufacturing method described above and a single container manufactured using only PET. Figure 5 (
A) shows the measurement results for a single container.
Output of 50mV or more is obtained. Figure 5 (B) shows the measurement results of a defective heat-resistant multilayer container, and the position angle is 90°.
", an output of 25 to 50 mV was obtained near 180° and 270°. FIG. 5(C) shows the measurement results of a good heat-resistant multilayer container, and there was hardly any output.

(Effects of the Invention) As described above, according to the inspection device and method for a heat-resistant multilayer container made of synthetic resin of the present invention, after detecting the transmittance of light of a specific wavelength of the main resin and the heat-resistant resin, it is output as a voltage. Since the quality of the heat-resistant multilayer container is judged based on this value, the inspection can be performed reliably in a short time, which not only greatly reduces the number of inspection steps, but also allows us to supply products with high reliability.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the transmittance of a container depending on the wavelength of light, FIG. 2 is a perspective view showing an outline of a container inspection device that implements the method of the present invention, and FIG. 3 is a cross-sectional side view showing the sensor section. FIG. 4 is a side view showing an inspection method using a container inspection device that implements the method of the present invention, FIGS. 5(A) to (C) are views showing measurement results by the method of the present invention, and FIGS. 6(A) to ( D) is a diagram showing the manufacturing method of a synthetic resin container, Figure 7 is a cross-sectional side view showing a co-injection molding machine, and Figures 8 (A) to (D) are diagrams showing the resin flow in the mold of the coinjection molding machine. It is a diagram showing a process. 1...Parison, 16...Main resin, 17...
Heat-resistant resin, 20... Inspection device, 22... Quartz fiber for light, 24... Quartz fiber for detector. Applicant's agent: Yasugata Yu Sanroku Tsune Hone Do Tsuri 2 Figure) 2゜ Tsuri 3 days

Claims (2)

[Claims] (1) In a method for inspecting a heat-resistant multilayer container made of synthetic resin, projecting ultraviolet light onto the upper end of the mouth of the heat-resistant multilayer container,
The container is characterized in that the ultraviolet rays transmitted through the upper end of the opening are received, the ultraviolet rays of only a specific wavelength are extracted and detected, and then outputted as an electric signal, and the quality of the heat-resistant multilayer container is determined based on the value. Inspection method for heat-resistant multilayer containers made of synthetic resin. (2) a light source device for generating ultraviolet rays; a light projecting fiber connected to the light source device to transmit the ultraviolet rays and project the light to the upper end of the opening of the heat-resistant multilayer container made of synthetic resin; A light-receiving fiber that is placed opposite to the light-emitting fiber and receives and transmits the ultraviolet light that has passed through the upper end of the mouth, and a sensor that extracts and detects the ultraviolet light output from the light-receiving fiber. 1. An inspection device for a heat-resistant multilayer container made of synthetic resin, comprising: a processing circuit for receiving and processing electrical signals from the sensor.