JPS5936849B2 - Pressure stretching method of plastic sheet - Google Patents

Description

Detailed Description of the Invention The present invention involves extrusion molding a thermoplastic synthetic resin having a crystalline chain polymer structure into a sheet, which is then compressed at a high magnification using rolling rollers heated to an appropriate temperature and stretching rollers. By applying a combination of stretching and tensile stretching, and maintaining a good balance between each other, pressure stretching is carried out in stages, thereby producing excellent physical properties such as tensile strength, counter pressure, elasticity, and piezoelectricity required for various industrial materials. Processing of a plastic sheet that can reduce the number of steps in the rolling stage, reduce the occurrence of rolling strain, and effectively increase the stretching ratio in the direction perpendicular to the stretching direction. This invention relates to improvements in rolling and stretching methods.

The purpose of the present invention is to maintain extremely strong tensile force at all times.
Large compressive forces that act locally, tensile and compressive forces that act simultaneously, or when these effects are accompanied by impact, bending, etc., can cause unnecessary elongation, compression, creep deformation, or cracks on the sheet surface. It has excellent molecular orientation structure with high resilience due to its high elasticity, and it also has tensile strength and resistance to wear without lubrication, which is a property difficult to obtain with ordinary metal sheets. The aim is to obtain a pressure-resistant plastic sheet.

In order to achieve the above object, the present invention first extrudes a thermoplastic synthetic resin having a crystalline chain polymer structure into a sheet shape, and extrudes it into a sheet at a high magnification using rolling rollers heated to an appropriate temperature and stretching rollers. The tensile strength and pressure resistance are improved by sequentially performing pressure stretching and tensile stretching in a stepwise manner, and applying the pressure stretching and tensile stretching stepwise over several stages as appropriate. In the pressure-stretching method, when a thermoplastic synthetic resin is extruded into a sheet shape and rolled by rolling rollers heated to an appropriate temperature, there is a gap between the opposing upper and lower rollers of each pair of rolling rollers during the rolling stage. By adjusting the inclined gap, the stress points of the rolling parts are sequentially changed, and the sheet is stretched while freely releasing the elongation in the direction perpendicular to the rolling direction, so that the sheet is rolled evenly over the entire width. , is a pressure stretching method for a plastic sheet, characterized in that a stretching roller applies tension between each pair of rolling rollers according to the rolling rate of each roller.

In general, if a chain polymer substance with crystallinity is stretched in a certain direction under suitable conditions at the highest possible magnification until it reaches breakage, and the orientational alignment of the molecular structure is increased, the tensile strength in the stretching direction is increased. Although the strength is significantly improved, on the other hand,
It is already well known that the strength in the direction perpendicular to the stretching direction decreases and brittle fracture occurs.

Nylon filament fishing line has conventionally been manufactured simply by a drawing process, and it satisfies the tensile strength requirements required for industrial materials.

In addition, for sheet-like products, nylon 6 oriented sheets with molecular alignment are used as the core material for flat belt manufacturing, but this is also simply done by the stretching method as described above, and is not subject to strong impact or bending. It has the disadvantage that cracks are likely to occur in the stretching direction when a tensile action is applied.

This can be said to be a drawback due to the stretching method, but this drawback is also exacerbated by the physical properties of the raw materials. That is, nylon 6 maintains its toughness by absorbing water and is resistant to stretching, but it becomes brittle in a dry state without absorbing water.

For this reason, when used in dry air, especially in low-temperature dry air, a tensile action accompanied by an impact acts on the belt at the start of the transmission operation, resulting in both the inevitable disadvantages of the physical properties of the raw material and the disadvantages of the stretching method. It is thought that the phenomenon of undesirable crack generation occurs as a result of entanglement. In order to eliminate and improve these defects, it is necessary to select raw materials whose physical properties are not affected by moisture absorption.
i.e. 6 like nylon 11 or nylon 12
If we use a material that has an extremely low water absorption rate compared to nylon and is even more elastic, we can achieve this goal, but simply stretching it will not improve the strength in the direction perpendicular to the stretching direction. In addition, the tensile strength is considerably inferior to that of nylon 6.

For example, if an extruded sheet of nylon 11 or nylon 12 is stretched under appropriate conditions, it is easy to stretch the length by 400%, but the width is 67% and the thickness is 37%.
% will be reduced.

The tensile strength at this time is approximately 2500 to 2800 kg/d,
The elongation is about 25%. The tensile strength in the stretching direction improves as the stretching ratio increases, but this is a result of the reduction in thickness and width. Therefore, in order to prevent a decrease in strength in the direction perpendicular to the stretching direction, the width reduction ratio is increased. If the thickness is made smaller, the stretching rate decreases unless the thickness reduction rate is increased proportionally, and the tensile strength in the stretching direction decreases accordingly.

There is a limit to the change in thickness when using the stretching method, and a decrease in thickness cannot be expected beyond the limit, resulting in a decrease in the stretching ratio and an unavoidable decrease in tensile strength.

While maintaining the tensile strength improved by stretching, in order to expect even higher strength, and to obtain a good sheet material with improved tensile strength and no compression creep deformation, it is necessary to It is considered that the most effective method is to reduce the thickness beyond the limit while also stretching in the direction of , and at the same time keep the width reduction rate small to increase the stretching rate.

The pressure stretching method of the present invention is most suitable for this purpose, namely, the reduction rate in the thickness direction can be freely adjusted and the width direction (direction perpendicular to the stretching direction)
This is because a satisfactory stretching effect can be achieved by maintaining a suitable reduction ratio. For example, if an extrusion molded sheet of nylon 11 or nylon 12 is rolled over rolling rolls heated to an appropriate temperature and rolled stepwise at an appropriate rolling rate, the thickness will be reduced to 25% and the width will be reduced to 130%.
, it was confirmed that the length could be stretched to 300%.

Although this rolling method can be expected to improve the counter pressure, there is also considerable stretching in the width direction (direction perpendicular to the stretching direction).
As a result, the stretching ratio is as small as 300%, and the tensile strength is therefore lower than that obtained by a simple stretching method, to about 80%. Also, the sheet form has a large amount of rolling strain, and cannot be called a practical sheet material. Therefore, in order to obtain a plastic sheet that does not retain rolling strain, has a tensile strength equal to or higher than that of the stretching method, and has excellent resistance to pressure, the rolling method and stretching method according to the present invention are necessary. The best results can be obtained by using a pressure stretching method in combination with the above methods. In order to prevent the occurrence of rolling strain by the pressure-stretching method of the present invention, pressure-stretching may be carried out in stages while maintaining an appropriate balance between the rolling ratio and the stretching ratio.

The sheet obtained by the pressure stretching method of the present invention has a thickness of 27
．． 5%, the width is reduced to 80% and the length is stretched to about 460%, and the tensile strength is significantly improved to 3500k9/C7.
It reaches 7l.

Also, the tensile strength in the direction perpendicular to the stretching direction is 500 kg/C.
The tensile strength of the unstretched sheet is increased by 30% or more.

The sheet in this state is rich in resistance pressure and elasticity, and even if compressed and deformed to 95% of its thickness, it will recover to 97% of its deformed amount after two minutes.

It was found that the sheet material obtained by the stretching method only recovered to 75%, and moreover, it was found that a large compression creep deformation occurred in the direction perpendicular to the stretching direction. The sheet obtained by the pressure drawing method of the present invention is most suitable as a core material for flat belts, and can also be used as sliding plates, brake plates, electrical insulation plates, high-pressure packing materials, etc. used under high pressure conditions. This plastic sheet is widely used in applications such as wear-resistant materials that involve rolling friction under high pressure and low speed, and has superior performance compared to conventional products.

The present invention is based on the above-mentioned viewpoint, and in order to produce a plastic sheet having excellent properties as described above and having high tensile strength and pressure resistance by a pressure stretching method, firstly, the method shown in FIG. , using a rolling roller device and a stretching roller device as shown in FIGS. 2 and 3, the appropriate rolling action and stretching action are carried out step by step in a well-balanced manner to perform pressure drawing, and remove any remaining rolling strain. This resulted in a flat plastic sheet that could be used in a wide range of applications as a suitable sheet material for various industrial materials.

FIG. 1 is an explanatory diagram showing only one pair of rolling roller devices, and FIG. 2 is an explanatory diagram showing a pressure stretching device in which a stretching roller device is provided in succession to the pair of rolling roller devices.

That is, in FIG. 2, section A indicates a rolling section, section C indicates a rolling section, and section C indicates a stretching section. FIG. 3 shows a series of pressure and stretching devices in which two or more pairs of rolling roller devices are successively provided with a stretching roller device so that the entire process can be completed in one continuous operation. It is something. The more steps there are in the rolling stage, the less rolling strain will occur.
Moreover, since the stretching ratio in the direction perpendicular to the stretching direction increases, rolling roller devices as shown in FIG. 1 are installed in stages and the rolling process is performed two or more times.
Further, the sheet is applied to a pressure stretching device as shown in FIG. 2, and the pressure stretched sheet is obtained by this method through the steps of pressure stretching, cutting of both edges of the notebook, stretching, and winding.

Next, to further explain the implementation device in the drawings, the first
In the figure, 1 and 1 are rollers for feeding the sheet material 20;
, 2 is a heating roller, 3 is a guide roller, 4 is a guide plate for the heated sheet material 20, and 5 is a rolling roller, all of which are heated to an appropriate temperature.

The sheet material 20 until it reaches the rolling rollers 5, 5
In order to give appropriate tension to the
The heating rollers 2, 2 each press the sheet material 20 with their own weight. Rolling roller 5
, 5, and the take-up rollers 6 and 6 are rollers that are heated to an appropriate temperature and require uniform temperature distribution.

Reference numerals 7, 7 are cooling rollers, and 8 is a take-up reel for the rolled sheet.

In order to repeatedly perform the rolling process of the material sheet 20 using a pair of rolling roller devices configured as shown in FIG. The rolling process is carried out step by step using a rolling roller device having a configuration in which a pair of rolling roller devices are further provided in series ahead of the take-up rollers 6, 6 of the rolling roller device shown in FIG.
Next, this rolled sheet material is guided to a stretching roller 9 and subjected to a rolling process as shown in the rolling section at the opening in FIG.

The stretching rollers 9 need to be controlled at appropriate temperatures and have uniform heating temperature distribution. In order to stretch the rolled sheet material between the take-off rollers 6, 6 and the stretch roller 9 at the opening of the rolling section shown in FIG. 2, the speed ratio of the take-off rollers 6, 6 and the stretch roller 9 is calculated in advance In addition, the distance between the take-up rollers 6, 6 and the stretching roller 9 is set to a distance-adjustable movable structure in order to minimize neckdown (a conventionally known structure is used).

That is, as shown in FIG.
6 and a stretching roller 9 to a predetermined ratio, and the rolling strain is also removed therebetween, the sheet passes through guide rollers 10 and 10 to become a pressure-stretched sheet 21, and is further processed by a trimming cutter 11 to form a pressure-stretched sheet 21. Both ears of No. 21 are appropriately cut to almost complete the press-stretching process. The pressure-stretched sheet 21 with both edges cut in this way is placed on the guide roller 1.
2 and 12, and then taken up by take-up rollers 13 and 13, and further guided to a stretching roller 14 to complete the stretching process, as shown in the stretching section of FIG. 2C. The pressure-stretched sheet 21 is re-stretched by the stretching roller 14, thereby satisfying the remaining stretching amount to a predetermined amount.
Thoroughly remove rolling strain. Then the guide roller 15,
15 and take-up rollers 16, 16, the pressurized stretched sheet 21 is wound onto a take-up reel 17. The take-off rollers 13, 13 that take over the pressurized and stretched sheet 21 in this stretching process are rollers that are controlled at an appropriate temperature and require uniform temperature distribution.

The stretching roller 14 and the tension roller 14' also serve as cooling rollers and stretch the stretched sheet 21 while cooling it. In FIG. 2, 9' is a tension roller made of silicone rubber, and 14' is a tension roller also made of synthetic rubber.

In addition, the speed ratio of the take-up rollers 13, 13 and the stretching roller 14 in FIG. 2 is the amount of stretching remaining in the pressure stretching process of the previous step, that is, the final stretching rate, for example, in the case of nylon 11, the stretching is performed until reaching 450 to 470%. It is set in advance by calculation so that

FIG. 3 shows a series of pressure-stretching devices in which a stretching roller device is installed in series with two or more pairs of rolling roller devices, and the entire process is completed in one continuous operation. That is, four pairs of rolling roller groups 5A, 5A,
5B, 5B, 5C, 5C, 5D, 5D are arranged in series,
The rolling process is completed in one operation using these rolling roller groups.

In FIG. 3, 9 is a stretching roller, q is a silicone rubber tension roller 18, 18 is a take-up roller, 19 is a stretching roller, and 19'' is a synthetic rubber tension roller.

FIG. 3 shows a continuous press-stretching apparatus having three steps in the rolling section, one step in the rolling section, and one step in the stretching section.
In general, the greater the number of rolling steps, the less rolling strain will occur, and the stretching ratio in the direction perpendicular to the stretching direction will also increase.

In the present invention, the number of rolling steps can be minimized to reduce the occurrence of rolling strain, and the stretching in the direction perpendicular to the stretching direction can also be effectively increased. Furthermore, when a plastic sheet is rolled, the central part of the plastic sheet is generally rolled the most compared to other parts, and the rolling effect is reduced on both sides, resulting in curling.

The curvature that occurs at this time can be removed by increasing the number of rolling steps and carrying out appropriate stretching in accordance with the rolling rate of each step, but this is complicated because the number of rolling steps must be increased. At the same time, the stretching effect in the direction perpendicular to the stretching direction is also small. In rolling metal sheets, a method is used in which the rolling rollers are crowned or rolled with the rolling rollers slightly crossing each other, but such methods are not very effective in the case of plastic sheets. Taking these points into consideration, the present invention incorporates the following additions in order to reduce rolling strain, improve the stretching effect in the direction perpendicular to the stretching direction, and shorten the number of rolling steps as much as possible. It was decided to use a rolling and stretching method.

The method is an inclined gap adjustment method, in which a series of continuous pressure and stretching apparatus shown in FIG. 3 is used, and as shown in FIGS.
, 5B, 5B, 5C, 5C, 5D, and 5D, by partially adjusting the gap between the upper and lower rollers of each pair, the pressure point of the rolling part is moved to the center position A, and to the biased position B to one side. , the offset position C to the other side on the opposite side, and the central position D, and by changing the position of the rolling pressure point in this way, the elongation in the direction perpendicular to the stretching direction can be increased. The sheet is stretched so that it can easily escape freely, and the rolling is performed evenly over the entire width of the sheet.

Therefore, rolling roller groups 5A, 5A, 5B, 5B, 5
Pressure-stretching can be performed favorably between C, 5C, 5D, and 5D while applying stretching according to the rolling ratio of each pair of rollers. According to this method, in order to obtain a good pressure-stretched sheet using a general pressure-stretching method, a total of 10 steps are required, that is, 8 steps of rolling, 1 step of rolling and 1 step of stretching, and 1 step of stretching. On the other hand, the total process is 5 steps, that is, rolling step 3
Compared to the general pressure-stretching method, which includes one step of rolling process and one step of stretching process, it is possible to obtain a pressure-stretched sheet of excellent quality with the same or higher strength in only % of the steps in the rolling process. It was found that it was possible to shorten the entire process by %.

Figure 4 is a schematic diagram showing how the stress points of the rolling area have been changed;
The figure is a schematic diagram showing a state in which the gap between the upper and lower rollers in each pair of rolling rollers is partially changed in inclination by adjusting the inclination gap.

In some cases, in addition to the above method, the central part of the rolling material 20 or the rolling roller groups 5A, 5A, 5B, 5B may be
, 5C, 5C, 5D, paraffin in the center of each of 5D,
By applying a relatively thin layer of lubricant, such as beeswax or a low-viscosity lubricant, the rolling progress of the central portion of the rolled sheet can be properly controlled by the slip during the rolling process, and therefore the rolling sheet can be It is also possible to obtain a uniform rolling effect over the entire width.

Next, examples of the pressure stretching method according to the present invention will be shown.

Example 1 The apparatus shown in FIGS. 3, 4, and 5 was used.

In addition, rolling roller groups 5A, 5A, 5B, 5B, 5C, 5
The gaps between the upper and lower rollers of each pair of C, 5D, and 5D are made to be inclined gaps as shown in FIGS. 4 and 5, and pressure points A,
Rolling was performed by changing B, C, and D so that rolling was performed evenly over the entire width of the sheet to shorten the number of steps.

Rolling is repeated in stages so that the rolling ratio does not exceed 30% and reaches 15%, so that the first stage is the center part, the second stage is the left part in the direction of travel, and the third stage is the right part. A gap difference of 0.03 mm is taken between the widths of the material sheets 20, and the pressure points at the rolling locations are sequentially changed, and rolling roller groups 5A, 5A, 5B, 5B, 5C, 5C, 5D are rolled at each stage.
, 5D, 7% tension was applied between each pair of rollers.

In the rolling process, the stress point of rolling was set at the center and the stretching rate was 20%, and in the stretching process, tension was applied to 30%. The results were as follows.

Compressive strength when compressed by 95% of its thickness is 1940k9/C
r! 1, and 95.6% of the compressive deformation was restored within 2 minutes.

Furthermore, no cracks were generated even when subjected to impact during tensile rupture.

Example 2 Similar to Example 1, the apparatus shown in FIGS. 3, 4, and 5 was used, and rolling roller groups 5A, 5A,
Rolling and stretching was performed by changing the rolling and stretching pressure points of each pair of upper and lower rollers 5B, 5B, 5C, 5C, 5D, and 5D.

In this case, since the rolling process was reduced to two steps and one step was shortened, the rolling ratio of the rolling rollers 5A and 5A was set to 0.

Stretching was carried out at a rolling rate of 15% and a stretching rate of 30% in the rolling process, a rolling rate of 45% and a stretching rate of 45% in the rolling process, and a stretching rate of 30% in the stretching process.

As a result, it was possible to obtain a substantially flat rolled sheet with very little residual rolling strain.

Similarly, 95% of the thickness of the rolled sheet, the compressive strength during compression is 20401<g/Cd, and 95% of the amount of compressive deformation.
was restored within 2 minutes.

Furthermore, no cracks were generated even when subjected to impact during tensile rupture. In the method of this Example 2,
It can be seen that the stretching ratio in the direction perpendicular to the stretching direction was large, and the stretching ratio in the stretching direction was correspondingly small, and the tensile strength was controlled, but the tensile strength in the direction perpendicular to the stretching direction was greatly improved. .

According to the pressure-stretching method of the present invention, the relationship between the thickness and width of the pressure-stretched sheet can be freely adjusted and set. It has the advantage of being able to freely select the direction and tensile strength.

Therefore, when the stretching ratio in the direction perpendicular to the stretching direction is increased, the tensile strength in the stretching direction decreases, but the resisting pressure increases, resulting in high elasticity recovery with very little compression creep deformation in the direction perpendicular to the stretching direction. It is possible to obtain a plastic sheet rich in strength.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram showing a pair of rolling roller devices;
The figure is an explanatory diagram of a pressure-stretching device in which a stretching roller device is provided consecutively to one pair of rolling roller devices, and Fig. 3 is an explanatory diagram of a pressure-stretching device in which a stretching roller device is provided in succession to two or more pairs of rolling roller devices → Fig. 4 is a schematic explanatory drawing showing a modified state in which rolling is performed by changing the pressure point of the rolling part in the rolling process, and Fig. 5 is an explanatory drawing showing the rolling process between the upper and lower rollers in each pair of rolling rollers. It is a schematic explanatory view showing a state where the inclination is partially changed by adjusting the gap. 1, 1... Sheet material feeding roller, 2, 2...
... Heating roller, 3 ... Guide roller, 4 ... Heating sheet material guide plate, 5, 5 ...
...Rolling roller 6, 6...Take-off roller,
7, 7... Cooling roller, 8... Take-up reel, 9... Stretching roller 9'...
・Silicone rubber tension roller, 10, 10...
...Guide roller, 11...Trimming cutter 1, 12,12...Guide roller, 13,
13... Take-up roller, 14... Stretching roller, 14'... Synthetic rubber tension roller 15, 15... Guide roller, 16, 16
...Take-up roller, 17... Take-up reel, 18, 18... Take-up roller, 19...
...Stretching roller, 19''...Synthetic rubber tension roller, 20...Sheet material, 21...
...Pressure stretched sheet, 5A, 5A, 5B, 5B, 5
C, 5C, 5D, 5D... Stretching roller group, A,
B, C, D... Pressure points at rolling locations.

Claims (1)

[Claims] 1. A thermoplastic synthetic resin having a crystalline chain polymer structure is extruded into a sheet shape and is sequentially subjected to pressure stretching and tension stretching at a high magnification using rolling rollers and stretching rollers heated to an appropriate temperature. In the pressure stretching method for plastic sheets, which improves tensile strength and pressure resistance by performing pressure stretching and tension stretching in stages, the synthetic resin sheet is heated to an appropriate temperature. During rolling by rolling rollers, during the rolling stage, the gap between the opposing upper and lower rollers of each pair of rolling rollers is adjusted by tilting the gap to sequentially change the pressure points at the rolling location, so that the pressure point at the rolling location is changed in a direction perpendicular to the rolling direction. Stretching the sheet while freely releasing the elongation so that the sheet is rolled uniformly over the entire width of the sheet, and applying tension between each pair of rolling rollers according to the rolling ratio of each roller using the stretching rollers. A pressure stretching method for plastic sheets characterized by: