JPS60209141A - Method for inspecting quality of thermoplastic resin - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an inspection method effective for quality control of thermoplastic resins, particularly thermoplastic resins used as raw material resins for manufacturing thin-walled sheet or film molded products, blow molded products, etc. It is.

There are various types of thermoplastic resins, including vinyl chloride resin, polyethylene, polypropylene, and polyethylene terephthalate, which can be plasticized by heat and extruded, but in order to obtain high-quality products, the quality of these raw resins must be checked. Control is an extremely important point industrially, and preliminary quality inspection is required. To explain vinyl chloride resin in detail below, vinyl chloride resin is a general-purpose resin that is manufactured at low cost, and its sheet or film molded products have excellent transparency and oxygen permeation resistance, so it can be used for food packaging, clothing packaging, etc. Sheets and films that consume a large amount of carbon are considered to be of high quality and have excellent commercial value, and are free from initial discoloration, foreign matter, and fish eyes. It is desired that there be as few as possible. A sheet or film with many initial discolorations, foreign substances, and fish eyes not only has an inferior appearance and low commercial value, but also has poor physical properties, and tears and cracks occur during secondary processing of the sheet or film. A disadvantage arises. Products with strong initial coloring often have poor thermal stability, and if there are many variations in initial coloring, this often results in fatal defects such as defective final products.

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, and colors were managed using, for example, Henter's L (lightness), a (redness), and b (yellowness). This method involves many work steps, requires special skill in roll cross-wiring, makes it impossible to avoid individual errors, and requires a considerable amount of time, resulting in many problems in terms of quality control during manufacturing.

The present invention has been completed as a result of intensive research to solve 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 dual-reflection/transmission colorimeter to color the film. A quality inspection method for thermoplastic resin characterized by recording identification.

2) Continuously extrude the thermoplastic resin to be inspected into a transparent film, pass this film through a cooling zone, and then continuously extrude it into a non-contact two-sided multiple reflection/transmission colorimeter and a gas laser light scanning detector. A method for inspecting the quality of thermoplastic resin, which is characterized by identifying and recording the coloring of the film while running the film, and detecting and counting foreign objects and fish eyes in the film.

The quality inspection method of the present invention is applicable to various thermoplastic resins including vinyl chloride resins, and can also be applied for the purpose of quality control in large-scale equipment such as resin production processes. .

The case of vinyl chloride resin will be explained below based on a dedicated quality inspection apparatus illustrated in the attached 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, a vinyl chloride resin to be inspected is made into a compound in advance, and then fed to an extruder 1 to be continuously extruded into a film C. The extruded film 7 is guided to a cooling roll 2, where it is cooled, and then the initial coloring of the film 7 is identified while being continuously run through a non-contact dual-reflection-transmission colorimeter 4. , tristimulus value x
, y, and z, and finally obtain color management values such as L (lightness), a (redness), b (yellowness), ΔL, Δa, and Δb. The film passes through a take-up roll 5 and is taken up by a take-up roll 6.

The extruder 1 is one with a diameter of 30 mm or less, for example, 20 m.
A small size around mφ is desirable because it allows efficient inspection with a relatively small amount of resin. In order to be able to check the film formability, this extruder has a screw compression ratio that can handle two free C liquids, and a breaker plate type in which a screen can be inserted to adjust the back pressure. The compression ratio should be 1.2.3 or 4, and whether or not a screen is required, or if a screen is provided, a 42# to 325# screen should be used as necessary. Furthermore, cylinder 01. The cylinder 02, head, and die have a temperature control mechanism, and the die is a set of coat hangers, and the thickness can be adjusted by attaching an appropriate die spacer and appropriately adjusting the take-up speed.

The screw rotation speed is preferably in the range of 10 to 1100 rpm, particularly around 20 to 60 rpm in relation to the resin retention 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.

In addition, the coloring of the film is identified using a non-contact dual-reflection transmission colorimeter 4, and x, y, z, a, a,
The desired film thickness for measuring and recording b is 0.
05 to 0.50m+.

Extruder 1 needs to be moved a little away from the normal installation position when disassembling and assembling the die (cooling roll 2
, it is difficult to frequently move the pulse transmitter roll 3, colorimeter 4, fish eye, foreign object detector 49, etc.) Therefore, as shown in Fig. 1, it is difficult to move the It is convenient to be able to adjust the height in the vertical direction as well as 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 needs to be cooled by the cooling roll 2, and it is recommended to install a water volume regulator or temperature regulator to ensure sufficient cooling and maintain a constant temperature. This makes it possible to eliminate uneven thickness, width, and surface unevenness.

The color measuring device 4 consists of the following principle. In other words, a film or sheet runs between two special reflective plates sandwiching it, and visible light from a light source is projected from the other end of the two plates of the bracket and repeatedly passes through the running film or sheet. After reaching one end, the light is received by a light receiving part that has a built-in light receiving element and has tristimulus values x, y.
, z, and the final color management values, for example, a, 'b
, ΔL, Δa1Δb are obtained.

Next, the second invention is a quality inspection method that identifies and records the coloring of the film and detects and counts foreign objects and fish eyes in the film. Furthermore, this is carried out by using a device incorporating a gas laser light scanning type detector 9.

This detector 9 is based 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 surface mirror, and reaches the film 7. The light spot on the film is scanned in the width direction of the film by a mirror rotating at high speed, and as the film travels, the entire surface of the film is irradiated. 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 counted and displayed. The scanning laser beam has an output of 10m below λ11000n so as not to cause light absorption, heat generation, or chemical change to the film 7.
It is desirable to use W or less, for example, He-
A Ne (λ632.8nm output 5mW) gas laser is used, and in order to distinguish between foreign objects and fisheyes, an eight-frame mirror is used, two light receivers and a pulse transmitter (pulse transmitter) are used to adjust the time lag. Roll 8)
is used. Fish eyes can be detected in three sizes: large, medium, and small, and each size range can be measured freely.

In FIG. 2, the detector 9 is arranged next to the measuring device 4 when viewed in the running direction of the film, but there is no limitation to this arrangement order, and the arrangement order may be reversed. It's okay. Further, the pulse generating roll 8 may be subordinated to either the Jid roller 8' or the take-up roll 5.

Note that 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 speeds of the cooling roll and 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.

Although the quality inspection method according to the present invention is widely applied to thermoplastic resins in general, it will be specifically explained in detail in the case of vinyl chloride resins. First, the vinyl chloride resin to be inspected is preliminarily made into a transparent compounded vinyl chloride resin compound, but there are two types of this compound: a hard compounded compound and a soft compounded compound, and in both cases, visible light and Since it is required to transmit gas laser beams, its transparency is desired to be 30 or less, preferably 5 or less in terms of Haze value.

The hard compound compound is a vinyl chloride resin with a heat stabilizer (
For example, it contains a soot-based stabilizer) and a small amount of a lubricant such as epoxidized soybean oil, butyl stearate, or cetyl alcohol, and contains almost no plasticizer.

On the other hand, soft compounding compounds contain a considerable amount of plasticizer, so in order to stabilize the amount supplied to the extruder, it is necessary to maintain good dry flow properties of the compound, so the solution is to incorporate an inorganic filler. be done. However, as mentioned above, due to the requirement for visible light and gas laser light transmission, calcium carbonate and titanium dioxide cannot be used as fillers (each particle of the filler must be completely dispersed; If there is, it will be counted as a right-on-your-eye).

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. In other words, by using this filler, it is possible to maintain stable dry blow properties, and the gas laser beam is It was confirmed that there was no scattering and that the target foreign object, fisheye, could be detected and counted without any problems. Further, from the viewpoint of measuring the colorability of the vinyl chloride resin, it is naturally desirable that the amount of this filler is small. From this point of view, as a soft compound,
A polyvinyl chloride resin to be tested mixed with a plasticizer, a heat stabilizer, and finely powdered silica having an average particle diameter of 20 μm or less is used. In addition, this plasticizer includes DOP, DOA,
DBP, polyester plasticizer, epoxy plasticizer, etc.
Commercially available plasticizers for so-called vinyl chloride resins are used, and commercially available stabilizers for so-called vinyl chloride resins such as Zn7Oa type or Cd-an type are used as the heat stabilizer.

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, compared to the conventional method, that is, roll-kneading a vinyl chloride resin compound, stacking the sheets to a certain thickness, press-molding, and then measuring the same with a colorimeter. Inspection time can be significantly reduced. Furthermore, since the present invention uses a non-contact dual-reflection-transmission colorimeter, the detection ability is significantly improved, and the method is excellent even for samples with only slight color differences. What's more, it is possible to simultaneously measure coloration, foreign matter, and fish eyes within the extrusion time.

On the other hand, conventionally, the time required to count fish eyes with the naked eye is 1 (1 compound mark, 250 mm length).
The time required for identification, counting, and recording is virtually zero, which reduces inspection time and reduces inspection time. This brings about the effect that accurate analysis results can be expected.

In addition, 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, and since multi-point measurements are performed and statistical processing is performed, extremely effective quality control is possible.

Although the present invention has been explained above mainly using vinyl chloride resin,
Needless to say, this is effective for other thermoplastic resins 62 as described above, and is also effective when a large extruder is used.

Next, examples of the present invention will be given.

Example 1 Vinyl chloride resin with an average degree of polymerization of 1050 (manufactured by Shin-Etsu Chemical Co., Ltd., trade name TK-1000) 3 points (A61.42, /1
63) The quality test was carried out on the following soft blended compound.

Vinyl chloride resin 100 parts by weight DoP 40 (a-Zn stabilizer 3) Thyroid 404 (*) 0.05 # (Qa) Product name, manufactured by Fuji Davison Chemical Co., Ltd. Fine powder silica The above compound was mixed in a Henschel mixer. Stirring speed 1
The mixture was mixed at 800 rpm and a discharge temperature of 120°C to form a soft blended compound.

This compound was supplied to extruder #1 (see below) of the equipment shown in Figure 2, and film extrusion was performed under the following extrusion conditions, and a film with a thickness of 0.15 m+ and a width of 40 mm was run at a speed of 5 m/min. The initial coloring value, that is, Henter's L% a, b, was measured using a non-contact dual-reflection transmission colorimeter while
(L=lightness, a=redness, b=yellowness) was measured, and He-N
When foreign matter and fish eyes were detected and measured using an e-gas laser light scanning type detector, the results shown in Table 1 were obtained in a measurement time of 25 minutes.

Extruder: Use a 20 Imφ extruder, L/
D = 22, Suff 9 Knee OR = 2', 0° screw rotation speed 50 rpm, temperature conditions when extruding two 80# screens: cx = 155°C, 02 = 190°C,
H2 170℃, D=205℃ Table 1 (Note) Number of pieces per compound lKy Example 2 3 vinyl chloride resins with an average degree of polymerization of 700 (164, 5
．． 46) The quality test was carried out on a hard blended compound as shown below.

Vinyl chloride resin 100 parts by weight Sn stabilizer 2.5 Epoxidized soybean oil 3 Butyl stearate 1 Cetyl alcohol 0.7 The above mixture was stirred for 1 time in a Henschel mixer.
The mixture was mixed at 800 rpm and a discharge temperature of 120° C. to form a hard compound.

This compound was supplied to the extruder of the apparatus shown in Figure 2 (see below), and film extrusion was performed under the following extrusion conditions to form a film with a thickness of 0.15 mm and a width of 40 mm at a speed of 4 m/min. While running, the initial coloring values, i.e., Hunter glue, a, b, were measured using a non-contact dual-reflection transmission colorimeter.
(L=lightness, a=redness, b=yellowness) was measured, and He
- Foreign matter detected by Ne gas laser light scanning detector
When I performed the fish eye detection measurement, the measurement time was 1.
The results shown in Table 2 were obtained in 0 minutes.

Extruder: Use a 20mmφ extruder, L/
D=22, screw rotation speed 1.0, screw rotation speed 2 Orpm.

Temperature conditions during extrusion: 01 = 150°C, Cz = 175°C)
(=170°C, D=205°C Table 2 (Note) Number of pieces per 1 m of film Example 3 Commercially available polypropylene with a melt index of 3 to 5 (//10 minutes) (Company A, Company 3 and Company 0, Both pellets were fed into the apparatus shown in Figure 2 and extruded into a film under the following conditions to form a film with a thickness of 0.15 mm and a width of 4 mm.
While running a 0mn film at a speed of 4m/min,
Initial colorability was measured using a non-contact dual-reflection transmission type colorimeter, and foreign matter and fish eyes were further measured using a He-Ne gas laser light scanning type detector.

The measurement time was 1.0 minutes, and the results shown in Table 3 below were obtained.

In addition, the extruder used is one with a diameter of 20 anrφ, L/D=2
2.Screw 0R=2, rotation speed 4Qrpm.

2 screens 80#, temperature condition 01=170℃, C2
Richness: 190°C, H: 180°C, D: 190°C.

Table 3 (Note) Number of pieces per 1m of film

[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. 1...Extruder 2...Cooling roll 8...Pulse transmission roll 4...Non-contact type two-sided multiple reflection/transmission color measuring device 5
...Take-up roll 6... Take-up roll 1 lure... Film 8,8'... Guide roller 9... Gas laser light scanning method detector patent applicant Shin-Etsu Chemical Co., Ltd. company

Claims (1)

[Claims] 1. The thermoplastic resin to be inspected is continuously extruded into a transparent film, and the film is passed through a cooling zone and then continuously passed through a non-contact dual-reflection transmission colorimeter. A method for inspecting the quality of thermoplastic resins, characterized by identifying and recording the coloration of a film while 2. The thermoplastic resin to be tested is continuously extruded into a transparent film, passed through a cooling zone, and then continuously passed through a non-contact two-sided multi-reflection transmission chromatic meter and a gas laser light scanning detector. A quality inspection method for thermoplastic resin, which is characterized by identifying and recording the coloring of the film while running it, and detecting and counting foreign objects and fish eyes in the film.