JPH0326344B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for inspecting the quality of vinyl chloride resin.

Vinyl chloride resin is a general-purpose resin that is produced at low cost, and its sheet or film molded products have excellent transparency and oxygen permeation resistance, so it is used in large quantities for food packaging, clothing packaging, agricultural vinyl film, etc. has been done.

As such, sheets and films that are consumed in large quantities are desired to be of high quality and have excellent commercial value, with as little foreign matter or debris as possible.
A sheet or film containing a large amount of foreign matter or fissures not only has a significantly inferior appearance and physical properties and has low commercial value, but also has the disadvantage of tearing or cracking during secondary processing of such a sheet or film.

In order to avoid such disadvantages, it is necessary to conduct a quality inspection on the raw material vinyl chloride resin as part of quality control. The method is to mold a transparent blended resin compound into a film and make a ^100cm2 film.
The method used was to visually count the number of fisheyes and foreign objects. However, this method does not allow for accurate testing and results in rough judgments.
It was difficult to manage high-quality vinyl chloride resin, and troubles often occurred.

The present invention was completed as a result of intensive research into this technical problem, and this method for inspecting the quality of vinyl chloride resin uses a transparent soft vinyl chloride resin compound containing a plasticizer and a heat stabilizer. It is made into a film by continuous extrusion molding, and when the film is continuously run after being cooled and the foreign matter and fissures in the film are measured using a gas laser light scanning detector, the resin compound is preliminarily added to the resin compound with an average particle size of 20 μm or less. The gist is to blend fine powder silica.

The present invention will be explained in detail below based on the accompanying drawings.

The drawings schematically show an apparatus for carrying out the method for inspecting the quality of vinyl chloride resins according to the present invention. That is, first, the vinyl chloride resin to be inspected is made into a compound in advance, and then fed to the extruder 1 and continuously extruded into a film. The extruded film 7 is guided to a cooling roll 2, where it is cooled, and then passed through a pulse generating roll 3 to a gas laser beam scanning type detector 4, where foreign objects and fisheyes in the film 7 are classified. The size is also determined and continuously detected and counted, passed through a take-up roll 5, and then wound up by a take-up roll 6.

Since the extruder 1 is not used for industrial film production, it cannot be used for products with a diameter of 30 mm or less, such as 20 mm.
Preferably around φ. However, in order to be able to see the actual film formability, this extruder was designed to allow the screw compression ratio to be changed freely, and to be a breaker plate type in which a screen could be inserted to adjust the back pressure.
Screw compression ratios of 1, 2, 3, or 4 are used, and screens of 42# to 325# are used as required. Furthermore, cylinder 1, cylinder 2, head, and die have a temperature control mechanism, and the die is of a coat hanger type and the thickness can be adjusted freely. The desirable thickness of the film for measuring foreign objects, fish eyes, etc. using gas laser light in the detector 4 is
It is 0.1±0.05mm. Screw rotation speed is 10~
100rpm range, especially in relation to resin residence time.
It is best to set it around 50 rpm. Furthermore, by attaching a torque meter and a resin pressure gauge, more accurate data for determining the moldability of the resin can be obtained.

When disassembling and assembling the die, it is necessary to move the extruder 1 a little away from the normal installation position (cooling roll 2, pulse generating roll 3, detector 4).
Therefore, it is convenient to install it on a rail as shown in the figure so that it can be moved back and forth and also be adjustable in the vertical direction.

The cooling roll 2 is generally of a water-cooled type. Since the film 7 extruded from the extruder is still hot, it is necessary to cool it with the cooling roll 2. If the film is not cooled sufficiently, uneven thickness will occur, so a water flow regulator is installed to provide sufficient cooling capacity. . The pulse transmission roll 3 has a function of checking the running speed of the film, and has the function of adjusting the time lag when the detector 4 detects the count. 8, 8' are film guide rollers.

The detector 4 is constructed on the following principle.
That is, the gas laser beam (scanning laser beam) emitted from the laser passes through a lens system, further passes through a rotating octagonal mirror, and reaches the film 7. The light spot on the film is scanned in the width direction of the film by a high-speed rotating octagonal mirror, and the entire surface of the film is irradiated as the film travels. This scanning light passes through the film 7, enters the light receiver, is photoelectrically converted by a built-in photomultiplier tube, becomes an electrical signal, and is displayed as a count.
The scanning laser beam is applied to the film 7 so that it does not absorb light, generate heat, or cause chemical changes.
It is desirable to use one with a wavelength of λ1000nm or less and an output of 10mW or less. For example, He-Ne (λ632.8nm output
5mW) gas laser is used, a half mirror is used to distinguish between foreign objects and fish eyes, two light receivers are used, and the pulse transmitter described above (pulse transmitter roll 3) is used to adjust the time lag. Ru. Fish eyes can be detected in three stages: large, medium, and small, and the size range of each can be adjusted freely.

The take-up roll 5 has the function of determining the traveling speed of the film 7 and adjusting the thickness of the film 7. That is, the thickness of the film 7 is determined by the take-up speed and the amount of extrusion. It is necessary to change the speed of the cooling roll and the take-up roll between hard and soft films, and therefore it is desirable to incorporate a speed ratio changing device for this purpose.

The take-up roll 6 may be of any type as long as it can take up the film at an appropriate speed, and its mechanism is not limited.

In the quality inspection method for vinyl chloride resin according to the present invention, as described above, a transparent soft vinyl chloride resin compound containing a plasticizer and a heat stabilizer is used as a raw material. Therefore, it is desirable that the transparency is 30 or less, especially 5 or less in haze value.

Furthermore, since this compound contains a considerable amount of plasticizer, it is required to include an inorganic filler in order to maintain good dry flow properties of the compound in order to stabilize extrusion. However, as mentioned above, calcium carbonate or titanium dioxide cannot be used as this filler due to the requirement for gas laser beam transmission (each particle of the filler must be completely dispersed, and if any particles aggregate, the ). According to studies conducted by the present inventors, fine powder silica with an average particle size of 20 μm or less is extremely suitable as this filler. In other words, by using this filler, dry flow properties can be maintained stably, and gas laser light It was confirmed that there was no scattering of the particles, and that the detection and counting of the target foreign object and fisheye was carried out without any problems.
We have arrived at the present invention.

The plasticizers used in the above compound include DOP, DOA, DBP, polyester plasticizers, and epoxy plasticizers, and the heat stabilizers include Zn-Ca and tin stabilizers. be done.

Further, a lubricant may be appropriately added to the above compound, and higher alcohols, fatty acids, fatty acid esters, metal soaps, etc. are used for this.

According to the present invention, the time required to count fish eyes with the naked eye was approximately 90 minutes per case (1 kg of compound, 250 m in length) (extrusion time not included), but in extrusion Other than the approximately 25 minutes required, the time required for sorting, counting, and recording is virtually zero, resulting in shorter testing times and more accurate analysis results. In addition, in the case of conventional visual observation, there are inevitably individual differences, and even the same measurer cannot avoid the disadvantage that the judgment differs from day to day.

Example [Soft compound] Γ Vinyl chloride resin with an average degree of polymerization of approximately 1300
100 parts by weight Γ DOA 45 〃 Γ Ca-Zn stabilizer 3 〃 Γ Thyroid 404 (*) 1 〃 (*) Product name manufactured by Fuji Davison Chemical Co., Ltd., fine powder silica The above mixture was stirred in a Henschel mixer at a speed of 1800 rpm. , and mixed at a discharge temperature of 120°C to form a soft blended compound.

This compound was supplied to the extruder of the apparatus shown in the figure, and film extrusion was performed under the following extrusion conditions.
When a film with a thickness of 0.1 mm and a width of 25 mm was run at a speed of 10 m/min, foreign objects and fish eyes were detected and measured using a He-Ne gas laser light scanning detector.The following results were obtained after a measurement time of 25 minutes. was gotten.

[Extrusion conditions]

An extruder with a diameter of 20 mm was used, L/D = 22, screw CR = 2, rotation speed 50 rpm, and screens = 1 each of 80# and 120#.

Temperature conditions: C ₁ = 155℃, C ₂ = 190℃, H = 170℃,
D=205℃ [Measurement results] (Number per 1 m of film) Thyroid eye Large (0.5 mm or more) 0 Medium (0.4 to 0.5 mm) 3 Small (0.3 to 0.4 mm) 11 Foreign matter 1 Comparative example 1 In the previous example, Thyroid 404 I made a soft compound in the same way except that I didn't add it, and tried to extrude it under the same conditions, but the dry flow properties were poor and I was unable to stably form a film with a thickness of 0.1 mm and a width of 25 mm. Nakatsuta.

Comparative Example 2 A soft blended compound was prepared in the same manner as in Example except that 1 part by weight of titanium dioxide, type CP (manufactured by Hayashi Pure Chemical Industries, Ltd., fine powder) was used in place of Thyroid 404, and the same procedure was used. Thickness under extrusion conditions
A film having a size of 0.1 mm and a width of 25 mm was run at a speed of 10 m/min to detect foreign matter and fish eyes in the same manner as in the example, and the following results were obtained.

〔Measurement result〕

Number of pieces per meter of film Large (0.5 mm or more) 6 Medium (0.4 to 0.5 mm) 15 Small (0.3 to 0.4 mm) 30 Foreign matter 2 In other words, when fine powder titanium dioxide is used as an inorganic filler, the gas laser beam transmittance increases. It was found that since the filler had poor dispersibility and was prone to agglomeration, this was also counted as a fissure, resulting in a value that was worse than the actual value.

[Brief explanation of drawings]

The drawing shows a schematic diagram of an apparatus for carrying out the method for inspecting the quality of vinyl chloride resin according to the present invention. DESCRIPTION OF SYMBOLS 1... Extruder, 2... Cooling roll, 3... Pulse transmission roll, 4... Gas laser beam scanning system detector, 5... Taking-up roll, 6... Winding roll, 7... Film, 8, 8'...Guide roller.

Claims (1)

[Claims] 1 A transparent soft vinyl chloride resin compound containing a plasticizer and a heat stabilizer is continuously extruded into a film, and after cooling, the film is continuously run and a gas laser light scanning detector is used to detect foreign matter in the film. A method for inspecting the quality of vinyl chloride-based resins, which includes the step of blending finely powdered silica with an average particle size of 20 μm or less into the resin compound in advance.