JPH03213324A - Manufacture of thin-walled molding - Google Patents

Abstract

PURPOSE:To perform cooling, shaping and furthermore stretching even for a film and a sheet in the inside of a die by forming a die into a tapered shape so that the cross-sectional area of the die vertical to the extrusion direction of molding material is made minimum in the position of an extrusion port and performing molding while resonating the die by vibration. CONSTITUTION:A die 1 is tapered as it approaches an extrusion port part. The driving force based on vibration imparted to the die 1 is made maximum in the extrusion port 1b. Further the flow path of the molding material in the die 1 is narrowed in coincidence with the thickness of a required molding. The nozzle 4 of an extruder is joined to the die 1. The molding material is supplied to the die 1 and extrusion is performed. Further the die 1 is resonated by generating ultrasonic vibration by the use of an ultrasonic vibrator 5 of an ultrasonic wave oscillator 6. Thereby cooling, shaping and stretching are performed in the inside of the die for the thin-walled molding such as a film and a sheet which is heretofore made impossible.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a method of supplying a molding material into a die and manufacturing a thin-walled molded product of a desired shape by extrusion molding, and particularly relates to a method of supplying a molding material into a die and manufacturing a thin-walled molded product of a desired shape by extrusion molding. cooling.

This invention relates to a method for manufacturing thin-walled molded products that can be stretched.

[Prior Art] When processing various products by extrusion molding, the process can be simplified and productivity can be improved by performing processing from shaping to cooling inside a die.

Conventionally, in the case of products to be extruded, such as thick-walled round bars or vibrators, sufficient rigidity is generated after solidification, so even if the molded product is shaped and cooled inside the die, it is difficult to extrude the product from the die. It was possible to push it out. On the other hand, in the case of thin-walled molded products such as films and sheets, such operations cannot be performed because of their low rigidity after solidification. Therefore, the gap at the die extrusion opening is set wider than the thickness of the product to be molded, and the intermediate product, which is thicker than the final product, is extruded in a molten state, and then the molded product is extruded at a speed faster than the extrusion speed. The method used was to take it off or roll it to a desired thickness, and then cool it.

[Problems sought to be solved by the invention] However, when shaping and cooling are performed outside the die as described above, the film extruded from the die hits the edge of the film when taken off due to a phenomenon called neck-in. Since the parts are thicker than the central part, there was a problem in that the molding process was complicated by the process of cutting off the ears and recycling the cut parts.

In addition, when forming a biaxially stretched film using crystalline resin, conventionally, an amorphous and non-oriented raw sheet is first extruded, and then a separate device is used to form a biaxially stretched film in the longitudinal and transverse directions. Biaxial stretching was performed to produce the final product. In this case, in addition to processing the portion of the sheet that corresponds to the ears mentioned above,
Since a two-wheel stretching process using separate equipment was required, the molding process became more complicated, resulting in low productivity.

The present invention has been made in view of the above problems, and by forcibly extruding the molding material inside the die to the outside of the die using the propulsion force generated by vibration, thin-walled molded products such as films and sheets, which have been impossible until now, can be produced. Another object of the present invention is to provide a method for manufacturing thin-walled molded products in which cooling, shaping, and furthermore stretching can be performed inside a die.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a method of supplying a molding material into a die and manufacturing a thin-walled molded product of a desired shape by extrusion molding, in which the extrusion direction of the molding material is This is a method in which molding is performed while a die having a tapered shape in which the area of the cross section of the die perpendicular to the die is minimized at the position of the extrusion port is resonated by vibration.

In addition, as a preferable aspect of the present invention, the abdominal part of the resonance,
A method may also be used in which molding is performed while causing resonance to match the position of the extrusion port in the die.

Another preferred embodiment is a method in which molding is performed while resonating so as to match the position of the resonant node or the inlet of the molding material in the die.

A preferred embodiment when molding a thin-walled molded product using a crystalline resin as a molding material is a method in which the molding material is supplied in a molten state into a die and is rapidly cooled to below the crystallization temperature in the die. It is.

In the present invention, thin-walled molded products refer to products with a thickness of 5 cm or less, preferably 0.5 m to 500 m, and include products of various uses and shapes such as films, sheets, pipes, etc. There is.

[Example code] A specific example of the above solution will be described below.

First, a specific example of an apparatus preferable for carrying out the method of the present invention will be explained based on FIGS. 1(a) and 1(b).

FIG. M1 (a) is a side sectional view of a die in an extrusion molding apparatus, and shows a T die for film and sheet molding.

FIG. 5B is a diagram showing a displacement waveform of the die captured at a certain moment during molding.

In the same figure (a), l is a die, which is designed in advance to resonate by vibration. This dice l
is tapered as it approaches the extrusion port, so that the propulsive force due to vibration applied to the die l becomes maximum at the extrusion port 1b (maximum vibration displacement during resonance) (Figure (b))
. Further, in the portion 1c near the extrusion port where the displacement due to vibration during resonance of the die 1 becomes large to some extent, the flow path of the molding material in the die 1 is narrowed to match the desired thickness of the molded product.

Depending on the material to be molded, it may be better to place the portion of the maximum propulsive force inside the extrusion port 1b. A built-in heater 2 is provided at the resonance node near the extrusion port tb, and a cooling medium flow path 1d is provided around the outer periphery of the narrow passage IC. The built-in heater 2 acts effectively when cooling the molding material by passing, for example, cooling water through the cooling medium flow path 1d, and prevents the molding material from solidifying before it becomes thin. Therefore, if there is no need to cool the molding material inside the die, there is no need to provide the built-in heater 2 and the cooling medium flow path 1d.

Various materials can be used for the die l, including metal materials used in conventional extrusion equipment dies, as well as ceramics and graphite. It is preferable to use a material with low vibration transmission loss, and particularly preferable are duralumin, titanium alloy, K-sensor, phosphor bronze, and graphite.

Further, the die 1 may be provided with a choke bar, a lip adjustment mechanism, etc. Depending on the shape of the molded product to be molded, the die 1 can be divided into two or more parts and constructed by assembling each divided member. In this case, it is preferable that the joints of each divided member coincide with the resonance abdomen. When the die is composed of a plurality of members, the die may be made of the same material or different materials. good. Furthermore, the die 1 can be subjected to various plating treatments, coating treatments, and even texturing treatments to improve wear resistance, corrosion resistance, or lower the coefficient of friction with the molding material.

Furthermore, the die l may be constructed such that only a portion including the extrusion port, for example, resonates.

It is also possible to include a mechanism for converting the vibration direction. It is possible to equip the die with a converter such as

In the resonant state, most parts of the die 1 vibrate, so in the conventionally used plate-shaped heater, the wiring inside the heater may break due to the vibration. Therefore, the far-infrared heater 3 is used to heat the dice 1, which can heat the dice 1 without contacting the dice 1. Far infrared heater 3.

It is fixed with a screw (not shown) to a non-vibrating part of the dice l in a resonant state, that is, a resonant node.

4 is a nozzle of an extrusion molding device (not shown) such as a single-screw extruder or a multi-screw extruder, and the molding material is supplied from this nozzle 4 into the die 1 through the inlet 1a of the die 1, and the final Then, the molding material is extruded from the extrusion port 1b.

Further, the nozzle 4 is fixed to the die l by means of attachment means such as screws at a position corresponding to approximately the resonance node of the die l. In this way, the vibration applied to the die 1 can be hardly transmitted to the nozzle 4. Furthermore, in order to suppress the transmission of vibration to the nozzle, it is preferable to incorporate a cushioning material such as titanium alloy fiber into the contact area between the nozzle and the die l.

The extrusion direction of the molding material extruded from the extrusion port 1b of the die 1 and the direction of the vibrations transmitted through the extrusion port may not be limited.If the molding material is also dispersed or stirred by vibration at the extrusion port, It is preferable that the extrusion direction and the vibration direction are perpendicular to each other.

Furthermore, by changing the shape of the extrusion port, the effect of vibration at the extrusion port can be increased or decreased.

Reference numeral 5 denotes an ultrasonic vibrator that gives vibration to the die 1, and is coupled to a position where the die 1 resonates due to the vibration applied. As the vibration generator that causes the dice 1 to resonate, it is possible to use not only this ultrasonic type device but also an electrodynamic type device, an electrohydraulic type device, and the like. As vibration modes, longitudinal vibration, transverse vibration, torsional vibration, radial vibration, deflection vibration, etc. can be used.

It is also possible to incorporate a vibration transmitting body between the die 1 and the ultrasonic vibrator 5. If the shape of the vibration transmitting body is selected appropriately, the vibration generated by the ultrasonic vibrator 5 can be It becomes possible to easily increase or decrease the amplitude of vibration. In order to transmit the vibration generated by the ultrasonic vibrator 5 to the die 1 with high efficiency and easily, the contact portion between the ultrasonic vibrator 5 and the die 1 is vibrated with the largest amplitude in the die 1 in a resonant state. It is preferable to match the region, ie, the resonance abdomen.

Furthermore, the number of vibration generators coupled to the die l or the number of vibration transmitters interposed between them is not particularly limited, and when a plurality of them are coupled, the timing of vibration is adjusted, and the number of vibration transmitters interposed between them is not particularly limited. Is it necessary to take care not to disturb the resonance state? The more vibration generators or vibration transmitters that are connected, the more strongly the die 1 can be vibrated.

Reference numeral 6 denotes an ultrasonic oscillator, which causes the ultrasonic vibrator 5 to generate ultrasonic vibrations and excites the die l at a resonance frequency, thereby causing the die l to resonate.

The resonant frequency of this die l is designed and manufactured to a frequency that can be tracked by the ultrasonic oscillator 6, and the molding material is supplied to the die 1 from the nozzle 4 of the extrusion molding machine, and finally from the extrusion port 1b. It is possible to constantly track slight changes in the resonant frequency due to momentary load fluctuations until the molding material is extruded. Further, the supply of necessary power is also set to supply the necessary amount (below the maximum output) in accordance with momentary changes. i.e. automatic frequency tracking.

An automatic power control method is adopted.

Next, an embodiment of the method for producing a thin-walled molded product of the present invention using the above-mentioned extrusion molding apparatus will be described.

A nozzle 4 of an extruder (not shown) is connected to a die 1, and a molding material is supplied to the die 1 to perform extrusion molding.
The die 1 is caused to resonate by causing the ultrasonic vibrator 5 to generate ultrasonic vibrations using the ultrasonic oscillator 6. Here,
The resonance is n-wavelength resonance (n=m/2.m is a natural number), and in order to maximize the vibration effect, the abdomen of the resonance is located at the extrusion port 1a of the die l and the contact area between the ultrasonic vibrator 5 and the die l. It is preferable to match the In addition, nozzle 4 of the extruder
In order to prevent vibrations from flowing out, it is preferable to align the resonance node with the position of the inlet of the molding material in the die 1.

The vibration frequency at this time can usually be arbitrarily selected within the range of 1ON, ~IOM) + 2, or in order to make the vibration effect extremely effective on the material that changes from a fluid state to a solid state, it can be selected arbitrarily within the range of 1ON, ~IOM) 1. It is preferable to set the frequency to .

Furthermore, the amplitude when vibrating the die 1 is preferably O-IBm to 100 gm in order to effectively push out the material that has become difficult to flow due to cooling by the driving force.

When the die is divided into multiple parts, each die member can be made to resonate at a different frequency and amplitude. This method is effective when curling a molded product, or when intentionally making the structure of the film non-uniform, such as orientation in the thickness direction, crystallinity, and filler dispersion.

Further, in a preferred embodiment of the present invention, in the method for manufacturing a thin-walled molded article described above, a crystalline resin is used as the molding material, and the molding material supplied in a molten state into the die 1 is rapidly cooled to a temperature below the crystallization temperature within the die 1. This is a method for manufacturing thin-walled molded products while molding. By this method, thin-walled molded products in an amorphous state or an oriented state can be easily obtained.

Molding materials that can be molded using the extrusion method and apparatus described above include organic materials such as plastics and rubber elastomers, inorganic materials such as inorganic polymers, ceramics, metals, and glass, other foods, and mixed materials thereof. Examples include materials that have at least some fluidity during molding.

Here, the following can be mentioned as plasti-links.

As a thermoplastic resin.

α-olefin resins (polyethylene, polypropylene, polystyrene, syndiotactic polystyrene, vinyl chloride resin, polybutene, ultra-high molecular weight polyethylene,
Polymethylpentene, ionomer, polybutylene, etc.) Polyester resins (polyethylene terephthalate, polybutylene terephthalate, polyarylate, etc.) Polyether resins (polysulfone, polyethersulfone, polyetherketone, polyetheretherketone, polyallylsulfone, polyester resins) Oxybenzylene, polyphenylene oxide, bossyanoallyl ether [JP-A No. 62-223226, etc.) Polycarbonate resin Polyimide resin Polyamide resin Polyamideimide resin Methacrylic resin Fluorine resin MBS (methacrylate butadiene styrene) resin AAS (acrylate) acrylonitrile styrene)
Resin AS (acrylonitrile styrene) Resin AC3 (chlorinated acrylonitrile polyethylene styrene) Resin ABS (acrylonitrile butadiene styrene)
ResinsPolyacetal resinsCellulose resinsPolyvinylidene chlorideChlorinated polyethyleneEVA resins (Ethylene Vinyl Acetate'G) Bowurethane resinsSilicone resinsAllyl resinsFuran resinsLiquid crystal polymersEpoxy resinsPhenol resinsPolybutadiene resinsSilicone resins As thermoplastic elastomers such as saturated polyester resins and amino resins.

Styrene-phtadiene elastomer polyester elastomer Polyethylene elastomer Urethane elastomer Examples include vinyl chloride elastomers.

Among these plastics, examples of the crystalline resin include polyethylene, polypropylene, syndiotactic polystyrene, polyethylene terephthalate, polyether needle ketone, and polycyanoallyl ether.

In particular, sheets and films made of plastic, etc.
When applied to thin-walled molded products with low rigidity, it becomes possible to simultaneously perform shaping, cooling, and stretching within the die, which was previously impossible, dramatically improving productivity and reducing capital investment. There is an advantage to being able to do this.

In addition, the method for manufacturing thin-walled molded products in the present invention refers to molding methods conventionally targeted at film-like molded products, such as inflation molding, sheet molding, multilayer coextrusion molding, etc. For molded products that cannot be extruded well when cooled in a die, molding materials in a fluid state are used in a die to form a predetermined shape, such as round bar molding, pipe molding, profile extrusion molding, blow molding, and extrusion foam molding. It is also possible to apply a method of extrusion followed by cooling or stretching (including rolling).

The thin-walled molded product thus obtained can of course be used as a film, sheet, etc., and can also be further used after being subjected to stretching, heat treatment, etc.

Experimental Examples> Hereinafter, the results of experiments conducted using the extrusion molding method and apparatus of the present invention will be explained while comparing with comparative examples.

Equipment used in the experiment - Extrusion molding equipment equipped with the die shown in Figure 1 and its peripheral equipment (the die is 200mm I@T tie, the lip opening is 0.1mm)
Layer, material titanium alloy) Molding material, syndiotactic polystyrene (MW=1
050,000) Ultrasonic oscillator, basic frequency 19.15Kl (manufactured by Seidensha Electronics Industry ■, 5ONOPET 1200B) Extrusion conditions Resin temperature at inlet: 295℃ Die surface temperature at far-infrared heater attachment part: 300℃ Built-in heater Set temperature 320°C Cooling medium High pressure water 120°C Vibration at extrusion port end 93 m Screw rotation speed 20 rpm Under the above conditions, extrusion molding is performed while making the die resonate, the extrusion amount is determined, and the molded product is The thickness distribution in the width direction, birefringence, and density of the film were evaluated.

The results of the experimental examples are shown in Table 1.

Salt Gloss 1 The molded product was not extruded, probably because the experiment was conducted with the ultrasonic oscillation stopped as in the conventional film molding method.

After the experiment, we disassembled the die and found that the part where the cooling medium was passed was cloudy and solidified.

Table 1 Results ■ By applying ultrasonic waves to the tie so that it resonates, a thin film made of syndiotactic polystyrene can be cooled in a die and extruded without much force, and a film with less uneven thickness in the radial direction can be produced. It has been found that it is possible to form the material into a low-density amorphous state and a highly oriented state.

As a result, the conventional process of removing the edge of the film and the production of two-wheel stretched film have been improved.
It becomes possible to omit the longitudinal stretching process, and the film manufacturing time can be significantly shortened.

[Effects of the Invention] As described above, according to the method for manufacturing a thin-walled molded product of the present invention, the molding material inside the die is forcibly pushed out of the die by the propulsive force generated by vibrations, thereby achieving an improvement that has never been possible before. It has become possible to cool, shape, and even stretch thin-walled molded products such as films and sheets within a die, which has the effect of simplifying the process and improving productivity.

Furthermore, in the production of two-wheel stretched films, the process of longitudinal stretching can be carried out within a die, making it possible to simplify the process.

[Brief explanation of drawings]

FIG. 1(a) is a side sectional view of a die in an extrusion molding apparatus for implementing the method of the present invention, and FIG. 1(b) is a displacement waveform diagram of the die. 1: Dice la: Inlet 1b; Extrusion 0
1c: Narrow passage ld: Cooling medium flow path 2: Built-in heater 3: Far-infrared heater 5: Ultrasonic transducer 6: Ultrasonic oscillator

Claims (2)

[Claims] (1) In a method of supplying molding material into a die and manufacturing a thin-walled molded product of a desired shape by extrusion molding, the die has a tapered shape in which the cross-sectional area of the die perpendicular to the extrusion direction of the molding material is minimized at the position of the extrusion port. 1. A method for manufacturing a thin-walled molded product, characterized in that molding is carried out while a die having a dies having the following characteristics is resonated by vibration. (2) A thin-walled molded product is formed by using a crystalline resin as a molding material, and molding the molding material supplied in a molten state into a die while rapidly cooling it to below the crystallization temperature in the die. The method for manufacturing a thin-walled molded article according to claim 1.