JPH01197630A - Method for inspecting container made of synthetic resin - Google Patents

Abstract

PURPOSE:To surely inspect a container without applying more than a required quantity of light to a photodetector by detecting the UV rays transmitted through the upper part of a mouth part through a filter having a pass band of 370+ or -10 (half-amplitude level). CONSTITUTION:Both the outside layer 2 and inside layer 3 of the container consists of PET (polyethylene terephthalate) and the intermediate layer 4 consist of a mixture composed of a U polymer consisting of a blend of polyarylate and PET as a heat resistant resin and benzotriazole as a UV absorptive resin at a ratio of 10:1. A xenon lamp is used for the light source of the inspection apparatus and an interference filter on a photodetecting side has the pass band of 370+ or -10 (half-amplitude level). The light transmitted through the top end 63 of the mouth part is detected by a quartz fiber 54 for the detector and is passed through the interference filter 100. A gallium-phosphorus element 58 generates current when the light of a specific wavelength is detected by the element 58. The current is amplified by an amplifier and is inputted to a deciding circuit, by which the non-defectiveness and defectiveness of the container 1 are decided.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a synthetic resin container, particularly a synthetic resin container whose main resin is polyethylene terephthalate resin, containing a heat-resistant resin and an ultraviolet absorbing resin. The present invention relates to a method for inspecting synthetic resin containers to determine whether or not they are.

[Conventional technology]

Containers made of synthetic resin, especially containers made of PET (polyethylene terephthalate), have excellent properties such as weather resistance, so the market for large soft drink containers continues to expand. Recently, the need for heat-resistant containers has increased,
In order to meet these needs, the applicant has already proposed a co-injection molding machine for producing a laminate of a main resin such as polyethylene terephthalate resin and a heat-resistant resin (patent application filed in 1983).
1-252997). Furthermore, based on the parison injection molded with this molding machine, a multilayer synthetic resin container was manufactured by blow molding, and he also proposed the invention of an inspection method and device for this container (Japanese Patent Application No. 1983- No. 289864).

By the way, as the heat-resistant resin constituting at least one layer of the resin laminate constituting the synthetic resin container, it is preferable to use polyarylate resin because of its excellent heat-resistant properties. However, this one has a wavelength of about 365rv
Transparent resin containers using this material have the problem of yellowing due to the effects of natural light or ultraviolet light in illumination during use. .

In response to such problems, the present applicants have further proposed an improved invention for a synthetic resin container in which a heat-resistant resin contains an ultraviolet absorbing resin (patent application filed on January 12, 1988).

The transmittance of each resin constituting this container with respect to the wavelength of transmitted light is as shown in FIG. 4, respectively.

According to Figure 4, heat-resistant resin (polyarylate and polyethylene terephthalate blend polymer (U-8400 manufactured by Unitika)
) has a low transmittance (dotted line), and furthermore, Tinuvin, an ultraviolet absorbing resin, is mixed in the heat-resistant resin (Tinuvin:
tJ-8400=1:10), the transmittance (double-dashed line) decreases.

Based on the difference in light transmittance of each resin to a certain wavelength, it is possible to test whether each resin component is effectively contained.

Inspection of synthetic resin containers using a two-component system consisting of a laminate of each resin, using PET as the main resin and U-8400 as the heat-resistant resin, is mainly conducted using 365 nn as shown in Fig. 7. Hg with a wavelength distribution peak of
The transmittance was measured using a -Xe lamp at a wavelength peaking at 350 ni. In this case, the fourth
It is confirmed that the closer the transmittance shown in the figure is to 0%, the more U polymer exists.

[Problem to be solved by the invention]

However, when U polymer, which is a heat-resistant resin, is mixed with Tinuvin, which is an ultraviolet absorbing resin, as shown in Fig. 4, 350±10r+n
The transmittance of light at a specific wavelength (half width) is almost O. In this case, the presence of U polymer and Tinuvin can be confirmed by setting the transmittance to O', but for example, when continuously measuring the circumferential surface of the upper end of the mouth of the container, This results in the inconvenience that the rate distribution cannot be clearly confirmed.

In such a case, if the wavelength is shifted to the longer wavelength side, the content distribution of the contained components can be confirmed to some extent. For example, as shown in FIG. 7, the wavelength peak is approximately 365 wavelengths.
The Hg-Xe lamp located at r+n may be used.

However, this device has a base that is centered around the wavelength 365r+n and expands toward the short wavelength and long wavelength sides, and if the measurement wavelength is set around this wavelength, there will be a problem that the amount of light received will exceed the input value.

Therefore, an object of the present invention is to provide a method for inspecting synthetic resin containers in order to eliminate the above-mentioned disadvantages.

[Means to solve the problem]

The present invention projects ultraviolet rays from a xenon lamp onto the upper end of the mouth of a synthetic resin container containing polyethylene terephthalate resin as the main resin, polyarylate resin as the heat-resistant resin, and benzotriazole resin as the ultraviolet absorbing resin. Then, a wavelength of 370±10 (half width) nn of the ultraviolet light transmitted through the upper end of the opening is received as the measurement wavelength, the amount of received light is output as an electrical signal, and the quality of the synthetic resin container is determined using that value. It is characterized by making judgments.

[Effect]

A xenon lamp is used to emit ultraviolet light to the upper end of the mouth of a synthetic resin container containing polyethylene terephthalate resin as the main resin, polyarylate resin as the heat-resistant resin, and benzotriazole resin as the ultraviolet absorbing resin. Therefore, it is possible to suppress the excessive amount of light at the measurement wavelength of 370 nm±10 (half width), and also to reliably test for the presence or absence of heat-resistant resin and ultraviolet absorbing resin.

〔Example〕

The principle of the inspection method according to the present invention utilizes the property that a heat-resistant resin containing an ultraviolet absorbing resin has a lower ultraviolet transmittance on the short wavelength side than the main resin.

Synthetic resin container to be inspected and its inspection method 1
An example is shown in FIG.

The cross-sectional shape of the body of the synthetic resin container 1 has a three-layer structure including an outer layer 2, an inner layer 3, and an intermediate layer 4 as shown in the figure.

Both the outer layer 2 and the inner layer 3 have a PET resin as the main resin 20, and the intermediate layer 4 has a heat resistant resin 41.
Polyarylate resin and ultraviolet absorbing resin 4
2, benzotriazole resin (Tinuvin) in a mixed state.

The cross-sectional shape of the opening of the container 1 has a three-layer structure similar to the cross-sectional shape of the body, or the middle layer and the outermost layers on both sides are made of the heat-resistant resin 41 and the ultraviolet absorbing resin 4, respectively.
2, and the two layers located between these layers each have the main resin 20, or the like. Such a mouth portion is normally used as an inspection site in the inspection method of the present invention, which will be described later.

Further, the polyarylate resin that is the heat-resistant resin 41 includes a blend polymer of polyarylate and polyethylene terephthalate (U3400 manufactured by Unitika).

In addition, the PET resin that is the main resin 20 includes terephthalic acid or its ester-forming derivatives (for example, lower alkyl esters, phenylnisdel, etc.) and ethylene glycol or its ester-forming derivatives (for example, monocarboxylic acid ester, ethylene, etc.). There are polyesters obtained by polymerizing dicarboxylic acids (such as oxides, etc.), and further contain less than about 20 mol% of dicarboxylic acids or aromatic dicarboxylic acids such as phthalic acid, isophthalic acid, naphthylene dicarboxylic acids, diphenyl dicarboxylic acids, diphenoxyethane dicarboxylic acids, etc. Adipic acid, sepatic acid, azelaic acid,
Copolymerizing aliphatic or alicyclic dicarboxylic acids such as decanedicarboxylic acid and cyclohexanedicarboxylic acid,
Less than about 20 mol% of glycol or aliphatic or alicyclic glycols such as trimethylene glycol, propylene glycol, tetramethylene glycol, neopentyl glycol, hexamethylene glycol, dodecamethylene glycol, cyclohexane dimetatool, or bisphenols, hydroquinone , 2.2-bis(
Aromatic diols such as 4-β-hydroxyethoxyphenyl)propane may be copolymerized, and oxyacids such as P-hydroxyethoxybenzoic acid and α-oxycaproic acid or lower alkyl esters of oxyacids,
It is also possible to copolymerize other ester-forming derivatives.

The mixing ratio of the ultraviolet absorbing resin 42 in the intermediate layer 4 is preferably about 0.005 to 10 wt%.
Note that the intermediate layer 4 may contain a PET resin as the main resin 20.

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 50 has a light source device 51 that generates ultraviolet rays and visible rays, and a light projection light source device 52 that is connected to the light source device 51 to collect and transmit the ultraviolet rays and visible rays. 53, a light receiving section 56 having a detector quartz fiber 54 having a diameter of one inch that receives the projected light, and a guide 55 that supports the detector quartz fiber 54.

In the middle of the detector quartz fiber 54, there is a sensor section 59 consisting of an interference filter 100 and a photoelectric conversion type gallium phosphorus element 58 that receives ultraviolet light that has passed through the filter, and a cable 60 extending from the sensor section 59.
There is an amplifier (not shown) and a judgment circuit (not shown) at the end of the
A determining section 61 consisting of:

In the inspection method of the present invention, the ultraviolet light projected onto the upper end of the opening of the synthetic resin container is provided by a xenon lamp. By using this xenon lamp, the measurement wavelength 37
The excessive amount of light at 0 nn can be suppressed, and the presence or absence of heat-resistant resin and ultraviolet absorbing resin can be reliably tested.

In other words, as shown in Figure 6, the radiation intensity of a xenon lamp draws a gentle curve with respect to the wavelength, and the radiation intensity is a necessary and appropriate value, which eliminates the disadvantages of the mercury-xenon lamp shown in Figure 7. This is because it does not show any peaks that cause .

Note that the scales indicating the radiation intensity on the vertical axes in FIGS. 6 and 7 are the same.

In the present invention, a wavelength in the range of 370±10 (half width) nn is normally used as the measurement wavelength. Within this range, it is possible to reliably test whether or not a predetermined heat-resistant and ultraviolet-absorbing resin component is present in the container.

To obtain such a measurement wavelength, an interference filter 100 on the light receiving side, which will be described later, is used.

As is clear from Fig. 4, when the mixing ratio of U polymer and Tinuvin is 10=1, for example, even if a wavelength of 400 nn is used, the mixed material of PET, U polymer and Tinuvin at that time is Since the difference in transmittance is small, it is not possible to accurately measure the presence or absence of a mixture of U polymer and Tinuvin. The inspection method is sufficient to measure the upper end of the container, and it is preferable to measure the entire circumference.

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, when the light quartz fiber 52 and the detector quartz fiber 54 are arranged in a straight line as shown in FIG. 1, the light generated from the light source device 51 passes through the light quartz fiber 22. The light is projected and illuminates the upper end 63 of the mouth of the container 1 .

The light that has passed through the upper end 63 of the mouth is received by the detector quartz fiber 54 and passes through the interference filter 100. When the light of a specific wavelength is received by the gallium phosphorus element 58, the potassium phosphorus element 58 generates a current,
This current is amplified by an amplifier and input to a determination circuit to determine whether the container 1 is good or bad.

In order to measure the entire circumferential direction of the upper end 63 of the mouth of the container, for example, as shown in FIG. The inspection may be performed while rotating the container around the central axis of the container 1.

As a method for rotating the container, as shown in the figure, a simple method is to rotate the container stationary stand 70 by a drive motor 71, but it is more preferable to use a container rotation mechanism already proposed by the present applicant (Japanese Patent Application No. 62-7743) is preferably used.

The results of specific measurements using the above-mentioned inspection apparatus and method will be described below.

First, a synthetic resin container to be inspected was manufactured.

During production, the above parison was injection molded and then blow molded to form a laminate container shape as shown in FIG. Both the outer layer 2 and the inner layer 3 shown in FIG. 1 are made of PET (polyethylene terephthalate) [Mitsui PET Resin J125], and the middle layer 4 is a heat-resistant resin made of U polymer made of a blend of polyarylate and polyethylene terephthalate [Unitika]. Made in U34
00) and benzotriazole as an ultraviolet absorbing resin at a ratio of 10:1.

The objects to be inspected were those manufactured under predetermined conditions for injection molding and blow molding to obtain a good product (sample kl);
Products manufactured under conditions other than the predetermined setting conditions (sample N
There were two types: Q2).

The upper ends of the mouths of the containers, which were two types of objects to be inspected, were measured using the method of the present invention over the entire circumference (0° to 360'').The light source of the inspection device was a xenon lamp. The interference filter 100 on the light receiving side has a passband of 370±10 (half width) nIl.

The results for each sample are shown in FIG. Fifth
Figure (a) shows the results for sample Nα1, which is a good product, and a constant output is obtained over the entire circumference. This is because the intermediate layer consisting of a mixed layer of heat-resistant resin and ultraviolet absorbing resin has a uniform concentration. , which suggests that it is formed on the circumference with a constant layer thickness.

On the other hand, for sample No. 2 shown in FIG. 5(b), a sharp drop in output is seen at each angular position as shown. This suggests that an intermediate layer consisting of a mixed layer of a heat-resistant resin and an ultraviolet absorbing resin cannot be obtained satisfactorily at these positions.

〔Effect of the invention〕

According to the present invention, ultraviolet rays from a xenon lamp are applied to the upper end of the mouth of a synthetic resin container containing polyethylene terephthalate resin as the main resin, polyarylate resin as the heat-resistant resin, and benzotriazole resin as the ultraviolet absorbing resin. The ultraviolet rays transmitted through the upper end of the mouth are received through a filter having a pass band of 370±10 (half width) r+n, and the amount of received light is output as an electrical signal. In the inspection method for determining the quality of containers, a wavelength of 370 ± 10 (half width) nn was used as the measurement wavelength for the received ultraviolet light, so the inspection could be performed reliably without giving more light than necessary to the light receiving element. I can do it.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of the inspection method of the present invention, FIG. 2 is a perspective view schematically showing a container inspection device that implements the method of the present invention, and FIG.
The figure is a cross-sectional side view showing the sensor part, FIG. 4 is a diagram showing the transmittance of the resin contained in the container used as the object to be inspected in the inspection method of the present invention, with respect to the wavelength of light, and FIG. (
b) is a diagram showing measurement results according to the method of the present invention, and FIGS. 6 and 7 are diagrams showing wavelength distributions of a xenon lamp and a mercury-xenon lamp, respectively. 1...Synthetic resin container, 2...Outer J-sign, 3...
Inner layer, 4... Intermediate layer, 20... Main resin, 41...
・Heat-resistant resin, 42... Ultraviolet absorbing resin, 50...
- Inspection device, 52... quartz fiber for light, 54
...Quartz fiber for detector. Applicant's representative Yasushi Ishikawa 2 Figure Measurement angle [degrees] (a) Measurement angle [degrees] (b) Figure 5 Wavelength (nm) Figure 6

Claims (1)

[Claims] Ultraviolet light from a xenon lamp is projected onto the upper end of the mouth of a synthetic resin container containing polyethylene terephthalate resin as the main resin, polyarylate resin as the heat-resistant resin, and benzotriazole resin as the ultraviolet absorbing resin,
Of the ultraviolet rays transmitted through the upper end of the mouth, 370±10(
A method for inspecting synthetic resin containers, which comprises: receiving light at a wavelength of (half width) nm as a measurement wavelength, outputting the amount of the received light as an electrical signal, and determining the quality of the synthetic resin container based on the value.