JPS60173114A - Treatment of formed gel - Google Patents

Abstract

PURPOSE:To manufacture a formed article such as fiber, film, etc. having high strength and modulus and uniform physical properties, in high productivity, by drawing and heat-treating an undrawn or semi-drawn formed gel of a high polymer with a dielectric heating means. CONSTITUTION:An undrawn or semi-drawn formed gel of a polymer (preferably an ultra-high-molecular-weight polyethylene having a weight-average molecular weight of >=1X10<6>) is drawn and/or heat-treated by a dielectric heating means, preferably a microwave dielectric heating means using a TM010-mode cylindrical microwave dielectric heating device. The form of the formed gel is preferably fiber or film to obtain a highly oriented product.

Description

[Detailed description of the invention]

The present invention relates to a method for treating a gel-like molded product, and more specifically, it relates to a method for treating an unstretched or semi-stretched gel-like molded product of a high molecular weight polymer.
Regarding a processing method that uniformly and efficiently stretches and/or heat-treats the inner and outer layers without any difference, it is particularly capable of high-speed stretching and high-strength stretching [2. Forming of fibers, films, etc. with uniform physical properties of high strength and high elasticity. Regarding processing methods for obtaining products. One batch of unstretched material obtained by solution extrusion molding 1-2 of a high molecular weight polymer is obtained by stretching a semi-stretched gel-like molded product at a high magnification. Methods for producing high-strength, high-modulus fibers or films are disclosed, for example, in JP-A-55-107506, JP-A-56-15408, JP-A-58-5228, and JP-A-58-1989. It is publicly known from Publication No. 81612 and the like. In order to achieve higher strength and higher elastic modulus than before, the molecular chain has a high U.
[Due to the need for stretching, it is essential to stretch at a high magnification in the stretching process. Shiga

[, because, in this case,
Because the activation energy required to stretch the molecular chain is high, conventional technology requires a low stretching speed or a long stretching heater to achieve the desired high strength and high elastic modulus. There was a drawback that the performance deteriorated. It is possible to improve productivity to some extent by raising the overall drawing temperature, but if the drawing temperature is raised to near the melting point of the material to be drawn, cuts may occur, especially in the case of fibers, the threading operation may be difficult. There are disadvantages such as difficulty in Since the rolling method uses an external heating method, the stretching starts from the outer periphery of the object to be stretched and progresses to the inner layer. Therefore, when an unstretched molded body containing a solvent is stretched by the conventional stretching method, the outer layer is first densified from the outer periphery while the solvent is removed from the outer layer. This prevents the movement and removal of the solvent in the inner layer from the outside of the object to be stretched, resulting in incomplete stretching and inability to increase the stretching ratio sufficiently to obtain the desired molded product with high strength and high elastic modulus. It was difficult. In the conventional method, a gel-like molded product containing a solvent obtained by extrusion molding a solution of the above-described high molecular weight polymer is stretched at a high magnification to obtain a fiber or film with high strength and high elastic modulus.
Such drawbacks were particularly noticeable. In addition, when the gel-like molded product is a fibrous material containing a large amount of solvent, in the conventional stretching method, the cross section of the fiber becomes flat during the stretching process.
12. It is difficult to obtain fibers with a circular cross section and holes. The present inventors have devised a method for eliminating all the drawbacks of such conventional methods and obtaining high-strength, high-modulus fibers, films, and other molded products from unstretched or semi-stretched gel-like molded products of high molecular weight polymers with high productivity. As a result of intensive study, we have arrived at the present invention which achieves the intended purpose. However, the present invention involves stretching and/or stretching an unstretched or semi-stretched gel-like molded product of a high molecular weight polymer using a heating method.
Alternatively, it is a processing method characterized by heat treatment. The unstretched or semi-stretched gel-like molded product of the polymer used in the present invention is disclosed in the above-mentioned JP-A-55-107506, JP-A-56-15408, and JP-A-58-52.
It can be produced by the known solution spinning method and solution extrusion method as described in Japanese Patent Application No. 58-81612, Japanese Patent Application No. 58-81612, etc. No. 152261, patent application No. 5 J3-15
462.2, Japanese Patent Application No. 58-161044, and the like. This can be explained simply as follows. That is, the gel-like molded product used in the present invention is produced by dissolving a high molecular weight polymer (especially an ultra-high molecular weight synthetic polymer) in a selected bath agent and extruding a moldable raw material liquid through an arbitrary die. can get. When selecting a solvent, it is necessary to choose one that satisfies the following basic requirements. In other words, is the solvent used for processing high molecular weight polymers? A single relatively low molecular weight compound or a mixture thereof is used to assist, and the compound must be selected to cause the high molecular weight polymer to go into solution only at elevated temperatures. However, this melting temperature must be lower than the decomposition temperature of the high molecular weight polymer. Therefore, at low temperatures, for example at room temperature, the low molecular weight compound or mixture thereof must be a non-solvent for the high molecular weight polymer. Any solvent may be used as long as it satisfies these basic requirements and is not particularly limited. When producing an unstretched gel-like molded product, it is necessary to synthesize the raw materials in order to obtain the desired high-strength, high-modulus molded product. Polyolefin, polyamide, polyethyl, polyacrylonitrile, polyvinylidene fluoride)
, polyvinyl alcohol, etc., and these polymers t'
Examples include, but are not limited to, M combinations and the like. Among the high molecular weight polymers mentioned above, especially those with a weight average molecular weight (
'Nk) is lXl0" or more, preferably 1x106
The present inventors have found that by carrying out the present invention, extremely high strength and high elastic modulus molded articles can be obtained by using the above-mentioned ultra-high molecular weight polyethylene as a synthetic polymer as a raw material1. ing. It has also been found that good W and performance can be obtained even when ultra-high molecular weight polypropylene of 1×10 6 or more is used as a raw material. The above synthetic polymer containing an appropriate amount of the above solvent can be easily molded by a known melt molding method or solution molding method. The unstretched gel-like molded product obtained by the above method usually contains a solvent. On the other hand, an unstretched gel-like molded product that does not contain a solvent [a solid matrix in which the liquid in the wet gel is replaced with a gas [e.g., an inert gas such as nitrogen or air] corresponding to the solid matrix of the wet gel) IJ Fuchs means (referred to as "xerogel") can be obtained by blowing hot air onto an unstretched gel-like molded product obtained by solution molding to remove the solvent from the gel-like molded product, or by removing the solvent occluded by the gel-like molded product. It can be easily produced by a method in which the solvent is removed by solvent substitution using a low boiling point solvent other than gold. It can be obtained by stretching with. Even if a semi-stretched gel-like molded product is obtained by stretching an unstretched gel-like molded product that contains a solvent, it may be difficult to form a gel-like molded product if it does not contain any solvent at all.
May also contain solvents. The present invention is characterized in that when the above-mentioned unstretched or semi-stretched gel-like molded product is fully stretched to obtain a product with high strength and high elastic modulus, stretching and/or heat treatment is performed using a dielectric heating power method. do. A method of stretching a synthetic polymer molded body using a dielectric heating method is known from, for example, Japanese Unexamined Patent Publication No. 148616/1983. However, unstretched synthetic polymers obtained by ordinary melt molding methods have a high density of molecular chains, and the molecular chains are intricately intertwined. An unstretched or semi-stretched gel-like molded product has a low molecular chain density and slight entanglement between molecular chains, so that it is potentially easy to stretch the molecular chains. Although the present invention can potentially easily stretch molecular chains, it is possible to create high-strength, high-modulus molded products using the dielectric heating method, which was slow or unattainable with conventional techniques. The purpose of this method is to achieve molded products with higher strength and higher modulus of elasticity with higher productivity than those achieved by conventional methods. The feature of the dielectric heating method is that it promotes heat generation from within the polymer by applying an alternating current electric field that corresponds to the frequency of the various dielectric relaxation absorptions that the polymer has. Compared to heating the polymer from outside, it is superior in that it heats the polymer evenly. In particular, for gel-like molded products that contain a large amount of liquid or gas other than the polymer inside the molded product, internal heating methods and dielectric Heating methods are particularly useful. Typically, dielectric heating is l
This can be carried out by applying an alternating current electric field of OMHz to 20 (mz) to the object to be heated. Any form of fiber or film may be used, but a highly oriented product can be obtained easily if it is particularly fibrous or film-like.
A highly strong and highly elastic molded body can be easily obtained by using the stretched body and carrying out the stretching and/or heat treatment method of the present invention. There is no need to apply the ε-sided heating method throughout the stretching process. A gel-like unstretched molded polyethylene product can be easily stretched by a conventional external heating method when the initial stretching ratio is relatively low. For example, tensile strength # below 1ON'P/-:,? Unstretched molded body with? Depending on the reading method, it is relatively easy to obtain a tensile strength of 1,90 Kf/- to less than 180 KP/-. Although this cannot be achieved with high-speed stretching without applying dielectric heating, this is a case where the goal is to improve the strength further, for example, when the strength is 90 Kf.
/ Semi-stretched polyethylene molded body less than d 180
When stretching to a strength of Kf/- or more, a semi-stretched polyethylene molded product with a strength of less than 180 KP/- is stretched to a strength of 280 Kf/- or more. This corresponds to the case where the film is stretched to a strength of /- or more. Although the electrically-proof heating method in the present invention is not particularly limited, it is a microwave dielectric heating method, in particular, a microwave dielectric heating method, in which microwaves are supplied parallel to the gel-like molded body passing through the cavity resonator. It is preferable to use a microwave dielectric heating method that uniformly concentrates the electric field. Assuming this type of microwave dielectric heating device, T Mor
Although an o-mode H-cylindrical microwave dielectric 7JO thermal device is suitable, the cavity resonator may have other shapes, such as rectangular, elliptical, or cocoon-shaped in cross section;
Other modes such as Matt mode may also be used. According to the present invention, it is possible to produce molded products with uniform physical properties, higher strength and higher elastic modulus, from a gel-like molded product with extremely high productivity than in the case of conventional methods. Made from fibers with a circular cross section and uniform physical properties.
It is possible to mold fibers with high flat strength and high elasticity with high productivity. The present invention will be specifically explained below with reference to Examples. Example 1 High density polyethylene 1 with weight average molecular weight 1.9X10”
The mixture was poured into decalin of kP'elLKp and uniformly dissolved while stirring at a temperature of 150'C. The obtained solution was extruded through pores with a diameter of 1 gmm, and the gel-like fibers were taken off with a roller rotating at a circumferential speed of 5 m/min, followed by first-stage stretching using a continuous hot plate heating method. The stretching ratio was 7.6. The tensile strength of the obtained semi-drawn fiber was 78 KP/-1 and the elastic modulus was 1750 to 5 J/i. Using the semi-drawn fiber, the following several methods were used. Stretch at a stretching speed of 1.00 m/min (peripheral speed of the final stretching roller). <Method 1> - Using the stretching heater of the present invention and [1. Two heating devices (oscillation frequency 2400 MHz, output 1.5 k'''W, TMo+o%-t) were installed in series, and the fiber to be stretched was run through the center of the cylindrical cavity resonator. <Method 2> )... Yu comparative example] A stretching heater and two 1.4 m long plate heaters were installed in series, and the first heater was heated at 130°C, 2
The temperature of the second heater was set at t-145°C. The drawn wt fiber was run while being in contact with a plate heater. <Method 3> Comparative Example 2 Two tube-shaped hot air heaters with a length of 1.6 m are connected in series as stretching heaters, and the hot air from the second heater is heated to a temperature of 140°C. The temperature was set at 148°C. The fibers to be drawn were run through the center of the tube. In each method, after threading at a supply roller speed of 80 m/min, the supply roller speed was lowered at a speed of 10 m/min/min, and the maximum stretching ratio (stretching speed (1
00 m/min)/feeding speed at the time of thread cutting (m7 min)] is shown in Table 1. Table 1 shows the maximum stretching ratio x 0.8
It also shows the tensile strength and elastic modulus of the drawn yarn when drawn at a magnification of . It can be seen that the polyethylene fibers having the first surface cross section can be produced with a drawing productivity that is about twice or more than that of the conventional method c method 2 or method 3]. Example 2 When the semi-drawn yarn used in Example 1 was stretched at a drawing speed of 10 m/min using the drawing method 3, the maximum drawing ratio was 3.9 and the following drawing ratio was 3.1 times. The yarn could be stably drawn and had a tensile strength of 175 KP/ad'. Using this two-stage drawn yarn, the drawing heaters of method 1 and method 2 described in Example 1 were used to perform the third drawing step 1-1. 3.8 at a drawing speed of 200 m/min
It was possible to stably draw the yarn at a draw ratio of 2 times, and the finished yarn had a tensile strength of 346 Kp/d and an elastic modulus of 12500 KP/-. On the other hand, when using method 2 stretching heater, 20
At a stretching speed of 0 m/min, L at a stretching ratio of 1.1 times or less
7 could not be stably stretched, and the improvement in strength and elastic modulus was extremely small. Therefore, in order to achieve high strength and high elastic modulus, we use the drawing heater of Method 2.In addition, we have to decide on the drawing speed. When stretched at an extremely low speed of 3 m/min, the maximum speed was 2.
Although stable stretching was possible at a stretching ratio of 0 times, the tensile strength Id 251 Ky / -1 elastic modulus of the finished yarn was 8500 -/-, which was inferior to Method 1 of the present invention. As is clear from this, when the entire drawing method of the present invention is used, the finished yarn has better tensile strength and elastic modulus than those obtained by the conventional method, and the productivity is increased at a much higher drawing speed than the conventional method. It turns out that L...m. Patent applicant: Toyobo Co., Ltd.

Claims (1)

[Scope of Claims] 1. A processing method characterized by stretching and/or heat treating an unstretched or semi-stretched gel-like molded product of a high molecular weight polymer using a dielectric heating method. 2. The treatment method according to claim 1, wherein the gel-like molded product is a gel-like molded product that is obtained by extrusion molding a solution of a high molecular weight polymer and contains or does not contain a solvent. . 3. Claim 1 in which the gel-like molded product is a fibrous material
The treatment method described in Section 2 or Section 2. 4. The treatment method according to claim 1, 2, or 3, wherein the gel-like molded product is a film-like product. 5. The processing method according to any one of claims 1 to 4, wherein the gel-like molded body is made of high molecular weight polyethylene. 6. The treatment method according to any one of claims 1 to 5, wherein the gel-like molded body is made of high molecular weight polypropylene. 7. Stretching a gel-like molded body made of polyethylene with a tensile strength of less than 90 Kp/- [6. Tensile strength t180 KP/-
A processing method according to any one of claims 1 to 5 as set forth above. 8. Tensile strength is 180K? A gel-like molded body made of polyethylene with a total tensile strength of 280 Kp/- is stretched.
- A processing method according to any one of claims 1 to 5. 9. The processing method according to claim 1, wherein the dielectric heating method is a microwave dielectric heating method. 10. Is the dielectric heating method an electric field parallel to the gel-like molded body passing through the inner metal of the cavity resonator to which microwaves are supplied?
The processing method according to claim 1, which is a microwave dielectric heating method that uniformly concentrates the heating.