JPS6140540B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for inspecting the quality of thermoplastic resins, particularly vinyl chloride resins. 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. Therefore, sheets and films that are consumed in large quantities are desired to be of high quality and have excellent commercial value, with as little initial discoloration, foreign matter, and stains as possible. Sheets or films with many initial discolorations, foreign substances, and fissures not only have poor appearance and low commercial value, but also sheets or films with many foreign substances and fissures have inferior physical properties, and the secondary properties of the sheet or film are poor. There is a disadvantage that tears and cracks occur during processing. Products with strong initial coloring often have poor thermal stability;
Further, if there is a large variation in initial coloring properties, this often results in a fatal defect such as a defective product in the final product. In order to avoid such disadvantages, it is necessary to perform quality inspections on raw resins in advance as part of quality control, but no efficient, simple, and accurate inspection methods have been developed for thermoplastic resins such as vinyl chloride resins. Not yet. For example, in order to check the degree of initial coloration of vinyl chloride resins, etc., a sheet of transparent blended compound is kneaded in a roll and then press-molded into a plate of a certain thickness. The tristimulus values of color, X, Y, and Z, were measured using a method that used Hunter's L (lightness), a (redness), and b (yellowness) to manage color, for example. However, there are many work steps, especially roll kneading, which requires skill, cannot allow for individual errors, and requires a considerable amount of time, which poses many problems in terms of quality control during manufacturing. The present invention was completed as a result of intensive research into this technical problem, and consists of the following summary. 1 Continuously extrude the thermoplastic resin to be tested into a transparent film, pass this film through a cooling zone, and then run it continuously through a non-contact reflective/transmissive colorimeter while identifying and recording the coloration of the film. A quality inspection method for thermoplastic resin characterized by: 2. The thermoplastic resin to be tested is continuously extruded into a transparent film, and after passing through a cooling zone, the film is passed through a non-contact reflection/transmission colorimeter and a gas laser light scanning detector while being continuously extruded. A method for inspecting the quality of thermoplastic resin, characterized by identifying and recording the coloring of the film, and detecting and counting foreign matter and fish eyes in the film. The present invention will be explained in detail below based on the accompanying drawings. FIG. 1 shows a schematic diagram of a quality inspection apparatus for vinyl chloride resin according to the present invention (particularly the first invention), and the operating mechanism of this apparatus is as follows. 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 continuously run through a non-contact reflective/transmissive colorimeter 4.
Here, the initial coloring of the film 7 is identified, the tristimulus values X, Y, and Z are measured, and the final color management values such as L (lightness), a (reddish), b (yellowish), △L, △
Obtain a and Δb. The film passes through a take-up roll 5 and is taken 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, or 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 screw rotation speed is preferably in the range of 10 to 100 rpm, particularly around 50 rpm in relation to the resin residence time. Furthermore, by attaching a torque meter and a resin pressure gauge, more accurate data for determining the moldability of the resin can be obtained. Note that the desirable thickness of the film is 0.05 to 0.50 mm for identifying the coloration of the film and measuring and recording X, Y, Z, and L, a, and b using the non-contact reflective/transmissive colorimeter 4. be. When disassembling and assembling the die, it is necessary to move the extruder 1 a little away from the normal installation position (the cooling roll 2, pulse sending roll 3, color measuring machine 4, fixing eye, foreign object detector 9, etc. must be moved frequently). ), therefore, the first
As shown in the figure, it is convenient to install it on a rail 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 measuring device 4 is constructed on the following principle.
In other words, visible light from a light source section is applied to a traveling film, the transmitted light is directed to a reflecting plate, the reflected light is transmitted from the back side of the traveling film, and the transmitted light is sent to a light receiving section that has a built-in light receiving element. The received tristimulus values X, Y, and Z are measured to obtain final color management values such as L, a, b, ΔL, Δa, and Δb. Next, the second invention is a quality inspection method for identifying and recording the coloring of a film, and detecting and counting foreign matter and stains in the film. This is carried out using a device incorporating a gas laser light scanning type detector 9. This detector 9 is constructed on the following principle. That is, the gas laser beam (scanning laser beam) emitted from the laser passes through a lens system, then a rotating octagonal mirror, and then passes through the film 7.
reach the top. 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 at a
It is desirable to use one with an output of 10,000nm or less and an output of 10mW or less. For example, He-Ne (λ632.8nm output
A 5mW) gas laser is used, a half mirror is used to distinguish between foreign objects and fish eyes, two light receivers are used, and a pulse transmitter (pulse transmitter roll 3) is used to adjust the time lag. Fish eyes can be detected in three stages: large, medium, and small, and the range of each size can be adjusted freely. In FIG. 2, the detector 9 is arranged next to the measuring device 4 when viewed in the film running direction, but the arrangement is not limited to this order. It's okay. Further, the pulse transmission roll 3 includes a guide roller 8' and a take-up roll 5.
It may be subordinated to either. 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. The quality inspection method according to the method of the present invention is widely applied to thermoplastic resins in general, but to explain this in detail specifically in the case of vinyl chloride resins, first, the vinyl chloride resin to be inspected is prepared in advance. It is said to be a transparent compounded vinyl chloride resin compound, but there are hard compounded compounds and soft compounded compounds, and in both cases, the transparency is required to be transparent to visible light and gas laser light. It is desirable that the value be 30 or less, preferably 5 or less. A hard blend compound is a vinyl chloride resin blended with a heat stabilizer (for example, a tin stabilizer), and a small amount of epoxidized soybean oil and a lubricant such as butyl stearate, cetyl alcohol, etc., and contains almost no plasticizer. On the other hand, since soft compound compounds contain a considerable amount of plasticizer, it is necessary to maintain good dry flow properties of the compound in order to stabilize the amount supplied to the extruder, so it is required to incorporate an inorganic filler. . However, as mentioned above, calcium carbonate and titanium dioxide cannot be used as this filler due to the requirement for visible light and gas laser light transmission (each particle of the filler must be completely dispersed, and some may aggregate. According to the studies conducted by the present inventors, fine powder silica with an average particle diameter of 20 μm or less is extremely suitable as this filler. It was confirmed that the system could be kept stable, the gas laser light was not scattered, and the detection and counting of target foreign objects and fish eyes could be performed without any problems. Further, from the viewpoint of measuring the colorability of the vinyl chloride resin, it is naturally desirable that the filler be small. From this point of view, the soft blended compound used is one in which the vinyl chloride resin to be tested is blended with a plasticizer, a heat stabilizer, and finely powdered silica with an average particle size of 20 μm or less. In addition, commercially available plasticizers for vinyl chloride resin such as DOP, DOA, DBP, polyester plasticizers, and epoxy plasticizers can be used as heat stabilizers.
Commercially available stabilizers for so-called vinyl chloride resins, such as Zn-Ca type or tin type, are used. Further, these hard or soft compounds may be blended with a lubricant as appropriate, such as higher alcohols, fatty acids, fatty acid esters, metal soaps, and the like. According to the present invention, the conventional method, that is, roll-kneading a vinyl chloride resin compound,
The sheets are stacked to a certain thickness and press-formed.
Furthermore, compared to the method of measuring the actual color using a colorimeter, the inspection time can be significantly reduced. Moreover, this color difference, foreign matter, and fish eyes can be measured simultaneously within the extrusion time. On the other hand, conventionally, the time required to count fish eyes with the naked eye is 1 (compound 1).
(extrusion time not included), but apart from the approximately 25 minutes required for extrusion, the time required for identification, counting, and recording is virtually zero, and inspection This brings about the expected effects of time reduction and accurate analysis results. In the case of conventional naked-eye observation, there are inevitably individual differences, and even the same person performing the measurement cannot avoid the disadvantage that the judgment differs from day to day. However, according to the inspection method of the present invention, there is no error due to individual skill as in the case of roll kneading, and since multi-point measurement and statistical processing are performed, extremely effective quality control is possible. Next, examples of the present invention will be given. Example 1 Three vinyl chloride resins (manufactured by Shin-Etsu Chemical, trade name TK-1000) with an average degree of polymerization of 1050 (No. 1, No. 2, No.
The quality inspection of 3) was conducted on the following soft compound compound. Vinyl chloride resin 100 parts by weight DOP 40 〃 Ca-Zn stabilizer 3 〃 Thyroid 404 (*) 0.05 〃 (*) Product name manufactured by Fuji Davison Chemical Co., Ltd., fine powder silica Stir the above mixture with a Henschel mixer at a speed of The mixture was mixed at 1800 rpm and a discharge temperature of 120°C to form a soft blended compound. This compound was supplied to the extruder (*) of the equipment shown in Figure 2, and film extrusion was performed under the following extrusion conditions to form a film with a thickness of 0.20 mm and a width of 25 mm at a rate of 6 m/s.
While running at a speed of
When we measured a and b (L = brightness, a = reddish, b = yellowish) and detected foreign objects and fish eyes using a He-Ne gas laser light scanning detector, the measurement time was 20 minutes. The results shown in Table 1 were obtained. (*) Use a 20mmφ extruder,
L/D = 22, Screw CR = 2.0, Screw rotation speed 50 rpm, 2 screens with #80, Temperature conditions: C ₁ = 155℃, C ₂ = 190℃, H = 170℃, D = 205℃. Regarding the coloring value, the results measured by the conventional method below are also shown. Measurement of initial coloring value by conventional method: Formulation: 100 parts by weight of vinyl chloride resin, 50 parts by weight of DOP, and 1.5 parts by weight of Cd-Zn stabilizer were mixed in a beaker. Roll kneading: surface temperature 160 with 6 inch roll
Rotation speed at °C Before roll 20rpm After roll
The mixture was kneaded for 5 minutes at 19 rpm with a sheet thickness of 0.8 mm. Press molding: Pressure 50Kg/cm ² with 37 ton press,
A test piece of 15 mm x 40 mm x 40 mm was made at a press temperature of 160°C, preheating for 5 minutes, and pressurizing for 5 minutes. Measurement: Hunter's L, a, and b were measured using an integrating sphere colorimeter reflection method.

[Table] Example 2 Three vinyl chloride resins with an average degree of polymerization of 700 (No. 1,
No. 2 and No. 3) were tested for quality as soft compound compounds as shown below. Vinyl chloride resin 100 parts by weight Sn-based stabilizer 2.5 〃 Epoxidized soybean oil 3 〃 Butyl stearate 1 〃 Cetyl alcohol 0.7 〃 The above formulation was mixed in a Henschel mixer at a stirring speed of 1800 rpm and a discharge temperature of 120°C to form a hard It was made into a compound. This compound was supplied to the extruder (*) of the equipment shown in Figure 2, and film extrusion was performed under the following extrusion conditions to form 5 films with a thickness of 0.20 mm and a width of 25 mm.
While running at a speed of m/min, the initial coloring value, that is, Hunter's L, a, b (L = lightness, a = reddish, b = yellowish) was measured with a non-contact reflective transmission colorimeter, Detection of foreign objects and fish eyes was carried out using a He--Ne gas laser beam scanning type detector, and the results shown in Table 2 were obtained in a measurement time of 10 minutes. (*) Use a 20mmφ extruder,
L/D = 22, Screw CR = 1.0, Screw rotation speed 220 rpm, 2 screens with #100, Temperature conditions: C ₁ = 150°C, C ₂ = 175°C, H = 170°C, D = 205°C. Regarding the coloring value, the measurement results using the conventional method described in the previous example are also listed.

[Table] Example 3 Commercially available polypropylene (from companies A, B, and C, all in pellet form) with a melt index of 3 to 5 (g/10 minutes) was used in the apparatus shown in Figure 2. Extrude the film under the following conditions to produce a film with a thickness of 0.25 mm and a width of 25 mm at 5 m/min.
The initial coloration was measured using a non-contact reflective/transmissive colorimeter while running at a speed of
Foreign matter and fissure eyes were measured using a He-Ne gas laser optical scanning detector. The measurement time was 20 minutes, and the results shown in Table 3 below were obtained. In addition, the extruder used is one with a diameter of 20 mm, L/D=
22, Screw CR = 2, rotation speed 40 rpm, 2 screens 80 #, temperature conditions C ₁ = 170℃, C ₂ = 190
℃, H=180℃, D=190℃. In addition, in order to judge the initial color evaluation ability of the in-line extruded film according to the present invention, as comparative data, the sheets discharged from the die under the above extrusion conditions were cooled, overlapped, and press-formed (37 ton press-forming). machine, pressure 50Kg/cm ² , press temperature 185℃, 5 minutes of preheating, 5 minutes of pressurization, then quenching to 30℃) Make a test piece with a thickness of 15mm x 40mm x 40mm, and use an integrating sphere colorimeter ( Hunter's L, a, and b were measured by reflection method).

[Table] Example 4 Commercially available GP type polystyrene (products of Company D and Company E, both in pellet form)
The film was fed into the apparatus shown in the figure and extruded under the following conditions. The film was run at a speed of 6 m/min with a thickness of 0.25 mm and a width of 25 mm. Measurement of
Furthermore, foreign matter and fish eyes were measured using a He--Ne gas laser scanning type detector.The measurement time was 20 minutes, and the results shown in Table 4 below were obtained. In addition, the extruder used is one with a diameter of 20 mm, L/D=
22, Screw CR = 2, rotation speed 40 rpm, screen 80# x 2, temperature conditions: C ₁ = 170℃, C ₂ =
185℃, H=185℃, D=190℃. In addition, in order to judge the initial coloring evaluation ability of the isline extruded film according to the present invention, as comparative data, sheets discharged from a die under the above extrusion conditions were cooled, overlapped, and press-formed (37-ton press, Pressure 50Kg/cm ² , press temperature
190℃, preheat for 5 minutes, pressurize for 5 minutes, then cool to 40℃),
A test piece with a thickness of 15 mm x 40 mm x 40 mm was made, and Hunter's L, a, and b were measured using an integrating sphere colorimeter (reflection method).

【table】

【table】 [Brief explanation of the drawing]

FIGS. 1 and 2 show a schematic diagram of a quality inspection apparatus for vinyl chloride resin according to the present invention. DESCRIPTION OF SYMBOLS 1...Extruder, 2...Cooling roll, 3...Pulse transmission roll, 4...Non-contact reflection/transmission colorimeter, 5...Take-up roll, 6...Take-up roll, 7
...Film, 8,8'...Guide roller, 9
...Gas laser optical scanning type detector.

Claims (1)

[Claims] 1. The thermoplastic resin to be inspected is continuously extruded into a transparent film, and after passing through a cooling zone, the film is continuously run through a non-contact reflection/transmission colorimeter. A quality inspection method for thermoplastic resin characterized by identifying and recording coloration. 2. The thermoplastic resin to be tested is continuously extruded into a transparent film, and after passing through a cooling zone, the film is passed through a non-contact reflection/transmission colorimeter and a gas laser light scanning detector while being continuously extruded. A method for inspecting the quality of thermoplastic resins, which includes identifying and recording the coloring of the film, and detecting and counting foreign matter and fish eyes in the film.