JPH09234780A - Thermoplastic resin molding method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To extend the period of continuous operation without wiping off gums by using a die having the surface roughness of the given value or less in the vicinity of a discharge opening and either one or both of vertical distances of the given value or more from an average line to crests or from roots adjoining the crests to the average line within the range of reference length and having the number of crests of the given value or more. SOLUTION: In the thermoplastic resin molding method, a die to be used therein is provided with the surface roughness of 0.1-5μm at the maximum height Rmax in the vicinity of a discharge opening, and either one or both of vertical distances of 0.05μm or more from an average line to crests and from roots adjoining crests to the average line within the range of reference length and also provided with the number of crests of 5-300. As for a method of finding the data provided with the maximum height Rmax and the number of crests within the proper range, for instance, the method of finishing an object surface by using a paste composed of oil and whetstones mixed together, the method of emitting very small spots of very high frequency energy to the object surface and forming small crator-shaped sites or the like is used.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a thermoplastic resin,
The present invention relates to a thermoplastic resin extrusion molding method in which a die is used to extrude into a shape such as a linear shape, a rod shape, a sheet shape, or a plate shape. More specifically, the present invention relates to a molding method for preventing the generation of a heat-discolored substance called so-called "meyer" that gradually adheres and accumulates in the vicinity of a discharge port of a die during extrusion molding.

[0002]

2. Description of the Related Art When the eye-catching glue that has adhered and accumulated near the discharge port of a die is mixed in a molded product, it causes a defective product. For this reason, the operation is stopped after every fixed time of operation to remove the porcelain, but if this is frequent, there is a problem that the manufacturing efficiency is reduced. Therefore, the following proposals have been conventionally made in order to suppress the adhesion and deposition of the eye drops.

As an improvement in terms of the material of the die, for example, as shown in Japanese Patent Publication No. 61-24973, the use of a ceramic mainly composed of zirconia as the material of the die is disclosed in JP-A-5-77305. As shown, it has been proposed to apply a fluorine coating to the inner surface of the die and the surface near the discharge port.

As an improvement in terms of the structure of the die, for example, as shown in JP-A-5-253997, the discharge port of the die has a tapered half-vertical angle of 4 to 20 degrees. As shown in Japanese Patent Laid-Open No. 5-77306, it has been proposed to chamfer the inner surface of the die by 60 degrees.

Further, as an improvement from the surface roughness of the inner surface of the die, JP-A-4-235015 and JP-A-5-22.
As disclosed in Japanese Patent Publication No. 0811, the center line average roughness Ra
It has been proposed to make the maximum height Rmax as small as possible.

[0006]

Although the above-mentioned conventional improvements can certainly reduce the adhesion and deposition of the eye-growth, this reduction has not been sufficient for practical use. Specifically, it is possible to extend the operation period until the wiping of the eyelids is required to some extent, but in practice, it is desired to further extend this period.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to further extend the period during which continuous operation is possible without wiping off the eyelids.

[0008]

According to the present invention, there is provided:
The surface roughness near the discharge port has a maximum height Rmax of 0.1 μm.
5 μm or more and within the range of the reference length L,
One or both of the vertical distance from the average line to the summit and the vertical distance from the valley bottom adjacent to the summit to the average line is 0.0
The thermoplastic resin molding method uses a die having 5 μm or more and 5 or more and 300 or less peaks.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is intended to improve the surface roughness in the vicinity of the discharge port of a die. However, the improvement from the surface roughness of a conventional die is to make the surface as smooth as possible. Although it is considered, it has a great feature in that it has been found that a certain degree of roughness is required. That is, according to the present invention, in the vicinity of the discharge port, the maximum height Rmax is 0.1 μm or more and 5 μm or less, and at the same time, the predetermined number of peaks in the reference length L is 5 or more and 30 or more.
It is characterized by the fact that it was found that the amount of adhered and deposited porcelain was minimized when a die of 0 or less was used.

The maximum height Rmax is JIS B060
With the value defined in 1, when the extracted part is sandwiched by two straight lines parallel to the average line of the part (referred to as the extracted part) extracted from the sectional curve by the reference length L, the interval between these two straight lines is This value is expressed in micrometers (μm) when measured in the direction of longitudinal magnification. The reference length L is a standard value defined in JIS B0601, and when the maximum height Rmax is 0.8 μm or less, the reference length L is 0.25 mm and the maximum height Rmax is 0. The reference length L in the case of more than 8 μm and 6.3 μm or less is 0.8 mm.

The maximum height Rmax is 0.1 μm or more 5
It must be less than or equal to μm. Even if the maximum height Rmax is less than 0.1 μm or exceeds 5 μm, the amount of mesiness is increased. If the maximum height Rmax exceeds 5 μm, the resistance between the extruded molten thermoplastic resin and the surface in the vicinity of the die discharge may increase, and the resin residue that leads to the occurrence of blisters may easily occur. To be Further, when the maximum height Rmax is less than 0.1 μm, it seems that a good result can be obtained at first for suppressing the occurrence of burr, but the contact area between the extruded molten thermoplastic resin and the surface near the discharge port of the die It is conceivable that the increase in the amount of the resin tends to cause the resin to remain, which also leads to the generation of the porcelain.

The number of peaks in the present invention means, within the range of the reference length L, one or both of the vertical distance from the average line to the peak and the vertical distance from the valley bottom adjacent to the peak to the average line. The number of peaks is 0.05 μm or more. In the present invention, the number of peaks is required to be 5 or more and 300 or less, and preferably 10 or more and 200 or less. In particular, the preferable range of the number of peaks is also related to the value of the maximum height Rmax, and when the maximum height Rmax is 0.1 μm or more and 3 μm or less, it is preferably 50 to 200, and the maximum height is Rmax exceeds 3 μm and 5
In the case of μm or less, it is preferably 10 to 120. It is not always clear why the number of peaks affects the occurrence of burr and the suppression of deposition, but if the number of peaks is too small and the surface is too smooth, the molten thermoplastic resin and the surface near the discharge port of the die The contact area with the swelling becomes large, and the porcelain component easily accumulates, and even if the number of peaks is too large, the contact area near the peaks on the surface of the molten thermoplastic resin near the discharge port of the die is large. It is considered that this is because the porridge component is likely to stay.

The above peaks, valley bottoms, and average lines are all JI
It refers to the contents defined in S.B.0601. Although the number of peaks is not defined in JIS in this way, the present invention makes it possible to grasp the shape of the surface in more detail by adding this number of peaks to the criterion. The major feature is that the detailed surface shape in the vicinity of the die discharge port, which is effective in suppressing generation and deposition, is clarified.

In the present invention, as long as the maximum height Rmax and the number of peaks are adjusted as described above, a film in which the fine particles of the ceramic material are co-deposited in the metal matrix is formed on the inner surface of the extrusion port. A die for extrusion molding may be used. In this case, the maximum height Rmax of the surface of the film is preferably 4 μm or less.

The thermoplastic resin referred to in the present invention includes a styrene resin, a polyphenylene ether resin, an acrylic resin, a polyamide resin and an olefin resin, and a styrene resin and a polyphenylene ether resin are particularly preferable. Styrene-based resins include polystyrene (including high-impact polystyrene with synthetic rubber added), styrene-acrylonitrile copolymer, acrylonitrile-butadiene-styrene copolymer, and other styrene and ethylenically unsaturated monomers. It is also effective for copolymers.
In the polyphenylene ether-based resin, modified polyphenylene ether is particularly preferable.

The ethylenically unsaturated monomer used in the present invention is represented by the following formula.

R-CH = CH ₂ (In the above formula, R represents an alkyl group having 1 to 25 carbon atoms, a phenyl group, an allyl group or an ester.) Specific examples include styrene, α-methylstyrene, acrylonitrile and methacrylonitrile. , Butyl acrylate, methyl acrylate, methyl methacrylate,
2-ethylhexyl acrylate, acrylic acid, methacrylic acid, ethyl methacrylate, butyl methacrylate, isobutyl methacrylate, 2-ethylhexyl methacrylate, lauryl methacrylate, tridecyl methacrylate, stearyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate 2-hydroxyethyl methacrylate,
2-hydroxypropyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, glycidyl methacrylate, tetrahydrofurfuryl methacrylate, ethylene glycol dimethacrylate, triethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, 1,3 Examples include butylene glycol dimethacrylate and trimethylolpropane trimethacrylate.

The term "die" as used in the present invention means an extruder, a kneader,
The portion of the molding machine where the molten thermoplastic resin is discharged, and the portion within 50 cm from the discharge port.

The vicinity of the discharge port in the present invention means the circumference of the discharge side port and within 50 mm from this circumference.

In the measurement of the surface roughness in the present invention, a very fine diamond needle is brought into contact with the surface to be measured and moved at a constant speed, and the size at which the diamond needle moves up and down due to the unevenness of the object surface is measured. Electronically enlarged and recorded, JI
It can be performed by automatically calculating with a data processor using the definition of surface roughness defined by S. In particular,
It can be measured using a surface roughness measuring device (surf coder: model “SE-3300” manufactured by Kosaka Laboratory).

As a method of obtaining a die having the maximum height Rmax and the number of peaks in the appropriate range described above, for example, a target surface is rubbed and finished with a paste in which oil and a grindstone are mixed, or a very high frequency wave is applied to the target surface. There is a method of irradiating thermal energy with a very small spot to form a small crater-like object.

On the other hand, spherical glass beads having a diameter of about 0.01 mm are sprayed on the target surface with a high-speed air stream to form a concave spherical shape on the surface, or fine powder of chromium oxide is oiled on a disk-shaped felt. In the buffing method in which the mixed liquid is applied and the surface to be finished is pressed against the rotating surface of the felt to be polished, it is difficult to obtain Rmax and the number of peaks in the appropriate ranges described above.

[0023]

EXAMPLES The present invention will be specifically described below with reference to examples.

Example 1 Using an extruder, a GPPS (General Purpose Polystyrene) strand (wire material) was molded at a die temperature of 220 ° C. and a take-up speed of 0.5 m / sec.
m, the number of discharge ports is 160, and the surface roughness in the vicinity of the discharge port outlet measured by a surface roughness measuring device (surf coder) has a maximum height Rmax = 1.8 μm. A die as shown in FIGS. 1 and 2 is used. Then, the amount of porridge generated was measured. The results are shown in Table 1.

Examples 2 to 8 and Comparative Examples 1 to 8 Thermoplastic resins shown in Table 1 and maximum height Rmax shown in Table 1
Also, the amount of porridge generated was measured in the same manner as in Example 1 using a die having the number of peaks per reference length L. The results are summarized in Table 1.

As is clear from the results shown in Table 1, when the number of peaks per reference length L is 5 or more and 300 or less, the amount of eyebrow generation can be suppressed and contamination of the product can be prevented. On the other hand, for the number of peaks per standard length L exceeding 300 and less than 5, the amount of mesiness is 10 times or more, and the operation is frequently stopped to avoid mixing into the product. Had to wash.

[0027]

[Table 1]

[0028]

According to the present invention, it is possible to reduce the frequency of stoppage of the process for the cleaning work for preventing the mixing of the melanin, and to greatly improve the productivity by the continuous operation over a long period of time. it can.

[Brief description of drawings]

FIG. 1 is a front view (discharge side) of a die used in Examples and Comparative Examples.

FIG. 2 is a cross-sectional view of a die used in Examples and Comparative Examples.

Claims (3)

[Claims] 1. The surface roughness in the vicinity of the discharge port has a maximum height Rma.
x is 0.1 μm or more and 5 μm or less, and the reference length L
Within the range of, the vertical distance from the average line to the summit,
A thermoplastic resin molding method comprising using a die having 5 or more and 300 or less peaks, one or both of which is a vertical distance of 0.05 μm or more from a valley bottom adjacent to the peak to the average line. 2. The maximum height Rmax is 0.1 μm or more and 3 μm.
The thermoplastic resin molding method according to claim 1, which is a die having the number of peaks of 50 or more and 200 or less. 3. The thermoplastic resin molding method according to claim 1, wherein the maximum height Rmax is more than 3 μm and 5 μm or less and the number of peaks is 10 or more and 120 or less.