JPS6222051A - Fish eye measuring method for thermoplastic resin - Google Patents

Abstract

PURPOSE:To detect a fish eye FE from a thermoplastic resin without fail by pushing the resin which is heated and melted at the temp. higher usually by 30-70 deg.C than the m.p. by a piston and extruding the resin from a flit die without kneading the resin. CONSTITUTION:In this embodiment, a PE sample 7g is put into a cylinder 1, and is melted by heating the same for about 6min at 200 deg.C; thereafter the piston 3 is pushed at a specified speed to extrude the resin from the slit die 5 and to form the film 7; at the same time gaseous nitrogen is ejected from a cooling gas ejection port 10 to cool the film 7 and further the film 7 is taken off at a specified speed (2m/min). Light is irradiated by a light projector 11 to the traveling film 7 from one side thereof and the light transmitted through the film 7 is detected by a photodetector 12 of an image sensor on the other side to measure the FE of the film 7. The FE is thereby detected from the thermoplastic resin without fail.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for measuring fish eyes (hereinafter referred to as F and E) of thermoplastic resin films.

[Conventional technology]

P, E, (corn-shaped defects that appear on the film) that often occur in thermoplastic films such as polyethylene and polypropylene not only significantly impair the appearance of the film, but also reduce mechanical strength such as tensile strength and impact strength. This also reduces the product value. The causes of such F and E are foreign substances such as high molecular weight substances and dust contained in the thermoplastic resin.
Among them, F and E due to high molecular weight substances cannot be detected unless the thermoplastic resin is made into a thin piece such as a film. Therefore, in order to test the F' and E that occur in a film, it is necessary to make it into a film by some method, so the thermoplastic resin that is the test material is usually processed using a screw extruder in the same way as the normal film forming method. After melting and kneading the film, a film is formed by a blown film method, a T-die method, etc., and the number of F and E generated in the film is counted visually or by laser light.

However, although a film with good external appearance was obtained in the F and E tests without any occurrence of F or E, P and E often occur at film processing manufacturers, causing problems. Many things happened.

However, even if we try to confirm the factors of F and E, F.

Since there were no problems at the time of the E test, we often had to worry about countermeasures, and in some cases even the F, E test was meaningless.

In addition, because the conventional method uses a screw extruder and a die with a complicated structure, it naturally requires a large amount of thermoplastic resin, and it takes a lot of time to clean the molding equipment. .

[Problem that the invention seeks to solve]

The inventor believes that the difference in the size and amount of F and E generated in the film due to differences in the specifications of the extruder used for film forming is due to the difference in the crosstalk effect of the screw extruder, but is essentially F, E.

Even if a thermoplastic resin containing the above factors is F at the time of the test.

Even if E does not occur, depending on the specifications of the extruder, there is a possibility that F, E, may occur to a greater or lesser extent.
Developing a method that always generates F and E from thermoplastic resins that contain factors such as , E, a measurement method that actually increases the occurrence of FE, and a method that is easy to operate and quick to measure. For this purpose, we conducted several studies.

[Means and operations for solving the problems] The present invention provides films F and E extruded from a slit die 5 without pressing and kneading thermoplastic resin 6 heated and melted in a cylinder 1 with a piston 3. It is a method of measurement.

Hereinafter, the method for measuring F and E performed by the method of the present invention will be specifically explained.

In the present invention, the cylinder l is filled with thermoplastic resin 6,
The resin is heated and melted in a furnace 2 provided outside the cylinder 1 at a temperature usually 30 to 70°C higher than the melting point, and then the resin 6 is pushed by a piston 3 automatically with a weight or a linear head or the like. A film 7 (with a thickness of 3 to 1010 Ga) is formed by extruding it from the slit die 5 without kneading.

As a thermoplastic resin to which the method of the present invention can be applied
(Regardless of whether crystalline or non-crystalline, low density polyethylene, high density polyethylene, polypropylene, poly l-butene, poly 4-methyl-1-pentene or ethylene,
propylene,! - Polyolefins such as random or block copolymers of α-olefins such as butene and 4-methyl-1-pentene, ethylene/acrylic acid copolymers, ethylene/vinyl acetate copolymers, ethylene/vinyl alcohol copolymers , ethylene/vinyl compound copolymers such as ethylene/vinyl chloride copolymers, polystyrene, acrylonitrile/styrene copolymers, ABS, methyl methacrylate/styrene copolymers, α-methylstyrene/
Styrenic resins such as styrene copolymers, polyvinyl chloride, polyvinylidene chloride, vinyl chloride/vinylidene chloride copolymers, polyvinyl compounds such as polymethyl acrylate and polymethyl methacrylate, nylon 6, nylon 6-6
, nylon 6-10, nylon 11. Any resin such as polyamide such as nylon 12, thermoplastic polyester such as polyethylene terephthalate or polybutylene terephthalate, polycarbonate, polyphenylene oxide, etc., or a mixture thereof may be used.

In the present invention, F and E are measured using the film produced by the first method. Specifically, the measurement method may include enlarging and projecting the film using an overhead projector, and measuring the number and size of F and E using appropriate means such as visual inspection of the projected image, or
Alternatively, it is also possible to adopt a method newly invented by the present inventor, in which the number and size of P and B are measured using an image sensor. In the present invention, the method for measuring the number and size of F and E of the film formed by the method of the present invention is limited to the above method.
Although conventionally employed methods may be used, among these methods, the method using the image sensor described above is particularly preferable. A method of using this image sensor will be specifically explained below.

The film 7 formed by the above method is taken up and run by a take-up machine 9 at a speed of usually 0.1 to 10 n+/sin while being stretched as necessary.

In the present invention, light is irradiated from one side of the traveling film 7 (by the light projector 11), and the light that has passed through the film 7 is transmitted to the light receiver 1 of the image sensor on the other side of the film 7.
By receiving light at 2, F and E of the film 7 are measured.

〔Effect of the invention〕

If the method of the present invention is adopted, in which a film is formed without kneading a heat-molten thermoplastic resin and the F and E of the film are measured, the thermoplastic resin containing the factors F and E can be F and E can always be detected, and in practice, it is possible to increase the occurrence of F and E to make them easier to detect. Further, according to the method of the present invention, the amount of thermoplastic resin required for measuring F and E can be reduced, and the operation is simple and the measurement can be performed quickly.

〔Example〕

(Examples 1 to 3) Using the film forming device of the piston type extruder shown in FIG. 1 and FIG. Types of polyethylene film (PEl-PE3) F, E,
was measured.

The device used for measurement has an inner diameter of cylinder I of 10 mm.
, has a length of 160 mm, is equipped with a heating furnace 2 on the outside of the cylinder l, has a cooling gas outlet IO below the slit die 5, and is rotated by a take-up motor Ml at a position 400 mm below the cylinder 1. A film winding machine 9 is provided.

Note that two rollers may be provided in place of the film winder 9, and the film 7 may be picked up by the rollers.

The image sensor has a number of light receiving elements: CCD type image sensor Number of light receiving elements: 2048 bits Field of view: 3Gha Resolution: 0.15mm Lens:
Focal length f50. Brightness F 1.4 Scanning frequency:
70GHz Scan width 50μm Aperture = between 5.6 and 8 (transparent film) I! 4
and 5.6 (translucent film) Light source: Fluorescent lamp (high frequency lighting method) Floodlight angle: 30 degrees.

Then, 7 g of polyethylene sample was put into the cylinder 1, heated at 200° C. for about 6 minutes to melt it, and then pushed out through the slit die 5 by pushing the piston 3 at a constant speed.
While forming the film 7, the cooling gas outlet 10
The film 7 was cooled by blowing out more nitrogen gas, and then the film 7 was wound up with a film winder 9, and the film 7 was taken off at a constant speed (2 m 2 /5 in). At this time, the film 7 had a width of 20 mm and a thickness of 30 am.

As mentioned above, while the film 7 is taken at a constant speed, the image sensor detects F, E, etc. in the film 7.
The measurement results shown in Table 1 were obtained by continuously measuring the measurement data and processing the measurement data with a program.

(Hereinafter, blank spaces) Table 1 (Examples 4 to 7 and Comparative Examples 1 to 4) Polyethylene films were created in the same manner as Examples 1 to 3 using four types of polyethylene resins (Samples 1 to 4). Then, F and E in the film were measured using an overhead projector equipped with a built-in light source as shown in FIG. 3 (Examples 4 to 7). On the other hand, in Examples 4 to 6, F and E in the film made using the above-mentioned polyethylene resin using a conventionally employed screw type extruder were used.
It was measured by the same method as (Comparative PJ 1-4).

These results are shown in Table 2 together with the physical property values of the sample polyethylene resin.

Table 2 * 0, 3mm or larger pieces/g) * * MF
R = Melt Flow Rate (Examples 8 to 10 and Comparative Examples 5 to 7) Using three types of polyethylene terephthalate resins A, B, and C, thoroughly dry them and then replace the resin with nitrogen inside the cylinder l. and set the temperature of cylinder l to 295
℃, a film of the resin was prepared in the same manner as in Examples 1 to 3, and unmelted proboscis-like F and E in the film were measured using an overhead projector (Examples 8 to 3).
10). Separately, F and E in a film made using the same resin using a conventional screw extruder were measured in the same manner as in Examples 8 to 1 (Comparative Examples 5 to 7). ). The results are shown in Table 3 together with the physical property values of the resin.

(Hereafter, blank space) Table 3 * Same as Table 2 - Figure 4 shows an example of the counting method in this example, and Figure 5 shows the equipment used in this example. It is something.

In this embodiment, as a method of pushing out the piston 3 at a constant speed, a motor M2 controlled by pulse drive is used to push the piston 3 at a constant speed with a linear head.
The amount of extrusion of the molten resin is kept constant, and the motor M2 rotates at a constant speed in response to pulses generated by a pulse generator controlled by a comprehensive controller.

In addition, the measurement section of the image sensor is also controlled by the image sensor controller in accordance with the pulses from the pulse generator, so that the pulse drive that defines the amount of extrusion of the molten resin and the measurement section of the image sensor are synchronized. This allows the number of F and E per unit weight of the film 7 to be measured immediately.

Then, the film 7 extruded from the slit die 5 is scanned with an image sensor in the X-axis direction (the width direction of the film 7 is the X-axis, and the length direction, that is, the winding direction is the Y-axis). At the same time as measuring the potential in the direction (related information (hereinafter referred to as X-axis information, see Figure 5)),
Pulses having a certain appropriate interval (pulses corresponding to the length in the Y-axis direction in FIG. 4) are generated as a quantity corresponding to the length of the film 7 in the Y-axis direction, and this pulse and the above-mentioned X-axis information are generated. By processing the program, one large F 2 , E 2 , A on the film 7 was counted with appropriate weighting, such as 2 or 3, depending on its size.

In other words, this program will always detect F and E as X-axis information by the image sensor, even if there is a plurality of them in one trough part of the pulse corresponding to the length in the Y-axis direction. It is assumed that ,E, has only one loss.

To explain this using an example in FIG. 4, three large F, E, and A appearing on the film 7 are counted as X-axis information, and one small F, E, and B are counted as X-axis information.

And the big F, E, and A as three pieces of X-axis information are:
Since they are located between the valleys 1 and 2 of the pulses corresponding to the length in the Y-axis direction, they are detected as two pulses. Also,
Small F, E, and B are naturally detected as one in valley 3.

As mentioned above, F per unit weight of the film 7,
Regarding the shape of E, we were able to evaluate the number of F and E by weighting the size as large, medium, and small.

(Experimental Examples 1 to 8) Figure 6 shows Experimental Examples 1 to 3, in which a transparent resin film was used to detect F and E using an image sensor (image sensor used in Examples 1 to 3). No. 1 is 100 μm, No. 2 is 120, E
ZllllS No. 3 is 900 μm F, Ili:, detected with an oscilloscope.

FIG. 7 shows Experimental Examples 4 to 8, in which a translucent film was used to conduct an experiment to detect F and E using an image sensor.

"5 is 220μm charring, N006 is 100μm charring is charring, No. 7 is 240μm charring is charring, No.
, 8 indicates that cellulose of 300 μm was detected.

[Brief explanation of drawings]

FIG. 1 is a side view showing an example of a measuring device used in the method of the present invention, FIG. 2 is a front view thereof, FIG. 3 is a diagram showing a counting method using an overhead projector, and FIG. 4 is a diagram showing an example of the measuring device used in the method of the present invention. FIG. 5 is a diagram showing another measuring device used in the method of the present invention, and FIGS. 6 and 7 are diagrams showing an example of the counting method of F and E used in the method of the present invention. It is a figure showing a state. 1. Cylinder, 3. Piston, 5. Slit die, 6. Melted resin, 7. Resin film, 9. Take-up machine formed as a winder, 11. Floodlight, 12. Image sensor° receiver. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5rM Figure 6 Figure 7

Claims (2)

[Claims] (1) Fisheye of a thermoplastic resin characterized by measuring the fisheye of a film 7 extruded from a slit die 5 by pressing a thermoplastic resin 6 heated and melted in a cylinder 1 with a piston 3 and extruded from a slit die 5 without kneading. Measurement method. (2) The film 7 is picked up and run, light is irradiated from one side of the running film 7, and the light that has passed through the film 7 is received by the light receiver 12 of the image sensor on the other side of the film 7. The method according to claim 1, characterized in that the fish-eye of the film 7 is measured using the following method.