JPS6115818B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a laminated sheet that is breathable, waterproof and stretchable.

Breathable and waterproof sheets are expected to be used as constituent materials for various articles such as tents, rain gear, sportswear, shorts, and diaper covers.

By the way, as a breathable waterproof sheet of this type, there has been known a sheet in which a porous plastic sheet and a fiber cloth are partially bonded together, as described in Japanese Utility Model Application Publication No. 54-34213.

However, the above-mentioned conventional products have the problem of poor usability since they do not have elasticity, although they have good breathability and waterproof properties.

In addition, when tension is applied, the tension acts directly on the plastic porous sheet or the partial bond between the porous sheet and the fiber cloth, enlarging the micropores of the porous sheet and increasing the waterproof property. In some cases, the adhesiveness may deteriorate considerably, or the partial adhesion between the porous sheet and the fiber cloth may be destroyed, resulting in separation of the two.

These problems are particularly noticeable when conventional products are used as constituent materials for items such as ski wear, clothing used for intense sports such as rain gear for mountain climbing, shorts, or diaper covers, and improvements have been desperately needed. .

In view of the above-mentioned current situation, the inventors of the present invention have conducted intensive studies and found that
Unfired polytetrafluoroethylene (hereinafter
PTFE) porous sheets and calcined PTFE porous sheets with a true specific gravity below a specific value have a high elongation rate, and these porous sheets can be used as base fabrics and parts with elasticity in a non-stretched state or a stretched state. Once the base fabric is stretched, the porous sheet will follow suit and expand. When the base fabric is released from stretching, only the base fabric will recover to approximately the same dimensions as before stretching, and the porous sheet will expand. The sheet is left with approximately the same dimensions as when it is stretched, and as a result, when no tension is applied to the base fabric and it is in a non-stretched state, the porous sheet is in an arc-relaxed state, and tension is applied to the base fabric, causing it to stretch. The inventors have discovered that it is possible to obtain a laminated sheet having a novel structure in which the loose state of the porous sheet is reduced or eliminated depending on the amount of elongation of the base fabric, and has thus completed the present invention.

That is, the method for producing a laminated sheet according to the present invention involves partially joining a stretchable base fabric with an unfired porous PTEF sheet or a fired PTFE porous sheet with a true specific gravity of 2.20 or less, and then bonding the base fabric with the base fabric. After stretching the cloth in a predetermined direction and stretching the PTFE porous sheet accordingly, the stretched state of the base fabric is released and the base fabric is restored to approximately the same dimensions as before stretching.
This method is characterized in that the porous PTFE sheet is held in approximately the same size as during follow-up elongation.

The stretchable base fabric used in the present invention is one that stretches a predetermined amount in at least one direction when tension is applied, and when the tension is removed, the stretched state is released and the size returns to approximately the same size as before stretching. It is a woven fabric, knitted fabric, or non-woven fabric that has the function of

Specific examples of these include Neoron (Teijin),
Polyurethane fibers (collectively called spandex) are commercially available under trade names such as ESPA (Toyobo), Mobilon (Nisshinbo), Fujibo Spandex (Fujibo), Opelon (Toray), Asahi Kasei Spandex (Asahi Kasei), and Lylac (DuPont). For example, fabrics or knits whose main material is

The base fabric used in the present invention has elasticity as described above, and its elongation rate is usually 5% or more, preferably 10 to 100%. The elongation rate of this base fabric can be measured by method A (constant speed elongation method) of the elongation rate test in JIS-L-1080.

As described above, the base fabric of the present invention has elasticity, but also has breathability. The air permeability of the base fabric can be measured according to JIS-L-1004, and in the present invention, a base fabric with an air permeability of 0.1 cc/cm ² ·sec or more is usually used.

On the other hand, PTFE is laminated with a stretchable base fabric.
The porous sheet is made of PTFE alone or a mixture of PTFE mixed with appropriate amounts of additives such as colorants, fillers, antistatic agents, etc., and is unfired or fired with a true specific gravity of 2.20 or less, with countless micropores formed. It is a sheet-like material that is both waterproof and breathable.

In the present invention, when the PTFE porous sheet is a fired product and its true specific gravity is 2.20 or more, when the base fabric is stretched after partially joining the base fabric and the porous sheet, the base fabric of the porous sheet is This is not preferable because it becomes difficult to follow the elongation of the porous sheet, and problems such as breakage of the porous sheet are likely to occur. On the other hand, when the PTFE porous sheet is an unfired product, the elongation rate is high, so there is no restriction on use based on specific gravity as in the case of a fired product.

The pore size of this PTFE porous sheet is usually
Set in the range of 0.01~50μ, porosity is 15~90
%, and the thickness is preferably 20μ to 1mm. Incidentally, as the porous sheet, either a fired product or an unfired product can be used as described above, but a fired product is more preferable in consideration of durability or strength.

The porous PTFE sheet used in the present invention can be produced by a stretching method in which a sheet-like material made of PTFE mixed with additives such as an anti-aging agent and a filler, if desired, is stretched to form countless micropores. Alternatively, it can be obtained by a solvent extraction method, etc., in which a sheet-like material made of PTFE mixed with a solvent-extractable substance is immersed in a solvent to extract and remove the solvent-extractable substance, thereby forming countless micropores.

In the present invention, first, at least one of each of the stretchable base fabric and the PTFE porous sheet is
The base fabric is partially joined under a non-stretched state or a low-stretched state. Partial joining of the two can be carried out by adhering the unstretched base fabric 1 and the PTFE porous sheet 2 in dots with an adhesive 3, for example, as shown in FIG. This partial joint may also be in the form of a stripe, a mesh, or the like.

In addition, if the base fabric is particularly flexible, it is likely to wrinkle when unstretched, which may reduce the workability of joining with the porous PTFE sheet. By keeping the cloth in a stretched state and bonding it to the porous sheet,
This is preferable because deterioration in bonding workability can be prevented.

In addition, in the present invention, under the stretched state of the base fabric,
When bonding with a PTFE porous sheet, if the base fabric has elasticity in one direction,
When joining, the base fabric is stretched slightly in that direction, and the base fabric is
If it has elasticity in more than one direction,
The material is slightly elongated in at least one direction during bonding. This is a matter that should be especially taken into account because it allows the base fabric to be stretched in at least one direction after joining.If this condition is not met, the base fabric cannot be stretched any further after joining.
The desired laminated sheet cannot be obtained.

In the present invention, the area of the joint between the base fabric and the PTFE porous sheet is determined in order to prevent the two from peeling off when the laminated sheet is used, to prevent an extreme decrease in air permeability due to the joint, and to maintain a good texture. It is preferable to set it within a range of 20 to 80% of the surface area of the bonding surface with the porous sheet (in a non-stretched state). In addition, in order to ensure that the area of each joint does not inhibit the expansion and contraction of the base fabric and maintain a good texture of the laminated sheet, the joint strength is set to an extent that does not cause peeling at the joint between the base fabric and the porous sheet during use. It is preferable to make it as small as possible within a guaranteed range.

In the present invention, after the elastic base fabric and porous sheet are joined as described above, the base fabric is bonded at a rate of 1 mm/sec to 1 m/sec by the action of tension.
It is expanded in a predetermined direction at a speed of approximately 1.0 sec.

When the base fabric is stretchable in one direction, the base fabric is stretched in that direction, and when the base fabric is stretchable in two or more directions, the base fabric is stretched in at least one of the directions.

The amount of elongation of the base fabric at this time can be set variously depending on the purpose, as described below. For example, when obtaining a laminated sheet for use in applications where the base fabric is stretched to its maximum elongation due to severe expansion and contraction during use, the base fabric and porous sheet are partially bonded, and then the base fabric is is extended to its maximum extension state.

Further, when obtaining a laminated sheet for use in applications where the amount of elongation during use is small, the amount of elongation of the base fabric after bonding can be set to be lower than the maximum amount of elongation. For example, we use a base fabric that can stretch up to 40%, but as a laminated sheet, we use a material that can stretch up to 40%.
In cases where the base fabric can only be stretched by up to 20%, the base fabric can be stretched by about 20% after the base fabric and the porous PTFE sheet are bonded.

In addition, the elongation rate of the base fabric is 20 to 90% of that of the base fabric alone due to partial bonding with the PTFE porous sheet.
Considering this,
The amount of elongation in the elongation step performed after joining with the PTFE porous sheet is specifically determined.

Furthermore, in the case where the base fabric and the PTFE porous sheet are partially bonded while the base fabric is stretched, the stretch of the base fabric after bonding can be determined by the following methods: This can be done by a method of stretching in a direction other than the stretching direction, or by a method of further stretching in the stretching direction during bonding and also stretching in other directions.

Due to the elongation of the base fabric after the above-mentioned bonding, the non-bonded parts of the PTFE porous sheet 2 with the base fabric 1 are elongated as shown in FIG. 2, and its dimensions increase (each bonded part becomes a fixed part). , the joint elongates accordingly).

Therefore, in the present invention, an unfired porous PTFE sheet or a fired PTFE porous sheet with a true specific gravity of 2.20 or less is used.
PTFE porous sheets are used, and these sheets inherently have a high elongation rate, with unfired products typically having a
%, up to about 300%, and fired products can usually be elongated by 70%, and up to about 200%, so there will be no inconveniences such as sheet breakage during the elongation process.

It should be noted that during this stretching, the micropores of the PTFE porous sheet expand, so in the present invention, the porous sheet to be used is adjusted in consideration of the stretching direction, amount of stretching, etc. so that the pore diameter after expansion becomes the desired pore diameter. The pore diameter of the micropores is set in advance. in particular,
The PTFE porous sheet has a micropore diameter of 0.01~60.
When μ, the balance between breathability and waterproofness is the best, so the pore diameter of the porous sheet used should be adjusted in advance so that the pore diameter of the porous sheet after expansion by stretching falls within the above range. is suitable.

Furthermore, in the case of obtaining a laminated sheet to be used in a heated state in the present invention, in order to prevent the PTFE porous sheet from losing its loose arc state due to heating during use, the elongation should be kept at a temperature higher than the working temperature of the laminated sheet. and then after elongation, maintain the elongated state at or above the working temperature for a predetermined period of time, or after elongating at a temperature below the working temperature of the laminated sheet, heat the laminated sheet at or above the working temperature of the laminated sheet for a predetermined period of time while maintaining the elongated state. It is preferable to heat set the elongated state by a method or the like. Further, even in the case of a laminated sheet used at room temperature, it is preferable to stretch the sheet at room temperature and then maintain the stretched state at that temperature for a predetermined period of time to fix the stretched state.

In the present invention, the stretchable base fabric is partially joined to the PTFE porous sheet as described above, and then the stretched base fabric is released from the stretched state to obtain the desired laminated sheet.

When the stretched state of the base fabric is released, the base fabric recovers to approximately the same size as before stretching due to its elasticity, but it should be noted that the porous sheet does not have dimensional recovery properties and remains approximately the same size as when stretched. Therefore, as shown in FIG. 3, for example, the laminated sheet has a unique and novel structure in which the PTFE porous sheet 2 is in a relaxed state when no tension is applied and the base fabric 1 is in a non-stretched state. Become something.

Although FIG. 3 shows the structure of a laminated sheet obtained using one base fabric and one porous sheet, in the present invention, PTFE porous sheets 2 and 2' are bonded to both sides of the base fabric 1. After the base fabric 1 is partially bonded with the agents 3 and 3', the base fabric 1 is stretched, and then the stretched state of the base fabric 1 is released, thereby forming the base fabrics 1 and 1 on both sides of the laminated sheet 2 as shown in FIG. 1' are partially joined with adhesives 3 and 3', the base fabric 1 is stretched, and then the stretched state of the base fabrics 1 and 1' is released, thereby producing a laminated sheet as shown in FIG. is obtained.

Further, although not shown, in the present invention, two or more base fabrics and two or more porous sheets each can be laminated.

The laminated sheet obtained by the present invention has a structure such that when the base fabric is in a non-stretched state, the PTFE porous sheet is in a relaxed state, so when tension is applied to the base fabric and the base fabric becomes stretched, It has the function of reducing or eliminating the arc-loose state of the porous sheet depending on the amount of stretching, and the elasticity of the base fabric is maintained.

That is, for example, when tension acts on the laminated sheet shown in FIG. 3, the tension acts intensively on the base fabric 1,
The base fabric 1 is in a stretched state. On the other hand, no tension acts on the PTFE porous sheet 2, but the base fabric 1
Following the elongation of the arc, the slow arc state decreases and gradually becomes flat. Then, when the tension acting on the base fabric 1 is removed, the base fabric 1 recovers to approximately the same size as before stretching due to its elasticity, and the porous sheet 2 also returns to its original size due to the dimensional recovery of the base fabric 1. Return to the arc-relaxed state shown in Figure 3. Note that since no tension is applied to the porous sheet 2 when the base fabric 1 is stretched, the diameter of the micropores in the sheet will not expand, and the breathability and waterproofness of the sheet will not change. Performance can be maintained for a long period of time.

The present invention is configured as described above, and not only can a laminated sheet that has elasticity, breathability, and waterproofness be easily manufactured, but the resulting laminated sheet can also be made into a PTFE porous sheet even after repeated expansion and contraction. The waterproofness of the porous sheet is maintained without any tension acting on it.
It has features such as no change in air permeability and high reliability.

Hereinafter, the present invention will be explained in more detail with reference to Examples.

Example 1 A polyester knit with an elongation rate of 40% in both the length and width directions, a thickness of 1.5 mm in the non-stretched state, and a length and width of 30 cm each was coated with grain size
0.5 mm of nylon-based hot melt adhesive (manufactured by Daicel Industries, Ltd., trade name: Diamid T-450) was sprinkled at approximately uniform intervals to cover 35% of the surface area on one side of the knit, and the adhesive was bonded by heating at 160°C for 1 minute. Fix the agent on one side of the knit.

Next, each end was fixed to the four ends of a steel plate with a length and width of 30 cm and a thickness of 3 mm, and a 30 cm thick piece was fixed onto the adhesive-fixed surface of the above-mentioned knit, which was maintained in an unstretched state.
μ, porosity 88%, average micropore diameter 0.8μ, true specific gravity
Place 2.175 calcined PTFE porous sheets;
After heating and pressing at a temperature of 170°C and a pressure of 1 kg/cm ² for 3 minutes to partially bond the knit and porous sheet, the sheet was cooled to room temperature (25°C).

After that, tension was applied at 25℃ and the speed was 5.
The base fabric was stretched at a rate of 25% and 35% in the length and width directions at a rate of mm/sec, and the PTFE porous sheet was stretched between the joints, and this state was maintained for 5 seconds to form a porous sheet. After fixing the stretched state of the fabric sheet, the tension is removed and the stretched state of the base fabric is released. As a result, the base fabric recovered to approximately the same dimensions as before stretching, while the porous sheet remained in approximately the same dimensions as before stretching, yielding a laminated sheet having the same structure as in FIG. 3.

This laminated sheet has elasticity, with an elongation rate of 25% in the length direction and 35% in the width direction, and is stretched so that the amount of elongation in each direction is the above elongation rate, and then this stretched state is released. Even after repeating the stretching motion many times, no peeling occurred at the joint. In addition, the area of the joint is 38% of the surface area of one side of the knit, and it is
The average pore diameter of the micropores in the PTFE porous sheet was 1 μ. In addition, the true specific gravity of the PTFE porous sheet is n-
It was measured using butanol according to ASTM, D1505.

For comparison, the work was carried out in the same manner as above, except that a fired PTFE porous sheet with a thickness of 30μ, a porosity of 86%, an average micropore diameter of 28μ, and a true specific gravity of 2.264 was used, but the elongation after bonding was When the elongation rate reached 13% in the length direction and 10% in the width direction, the PTFE porous sheet broke, and the desired laminated sheet could not be obtained.

Example 2 Thickness 40μ, porosity 87%, average pore diameter 1.2
Example 1 except that a fired PTFE porous sheet with μ and true specific gravity of 2.194 was used, and the elongation rate of the knit was 15% in the length direction and 30% in the width direction during the elongation work after joining. A stretchable laminated sheet was obtained in the same manner as above.

The elongation rate of this laminated sheet is 15% in the length direction and 20% in the width direction, and it is stretched so that the amount of elongation in each direction reaches the above elongation rate, and then the stretching movement is repeated many times to release this stretched state. Even after repeated testing, no peeling occurred at the joint. Furthermore, the average pore diameter of the micropores in the PTFE porous sheet that had been subjected to follow-elongation was 1.3μ.

Example 3 One side of a highly flexible nylon knit with an elongation rate of 2.0% (in the length direction) and 30% (in the width direction), a thickness of 0.3 mm in the non-stretched state, and a length and width of 30 cm each. The hot melt adhesive is fixed in the same manner as in Example 1.

Next, stretch this knit in both directions by 5% in each direction.
Stretch it so that it looks like this, and fix each end to the four ends of a steel plate with a length and width of 31.5 cm and a thickness of 4 mm (fix it so that the side to which the adhesive is not fixed is on the steel plate side). Maintain the elongated state so that it does not change.

The same calcined material used in Example 1 was then used.
Using a PTFE porous sheet, bonding, elongation (however, the elongation rate was set to 20% in the length direction and 30% in the width direction) and release of elongation were performed in the same manner as in Example 1 to obtain a laminated sheet.

This laminated sheet has elasticity, with an elongation rate of 30% in the length direction and 40% in the width direction, and is stretched so that the amount of elongation in each direction is the above elongation rate, and then this stretched state is released. Even after repeating the stretching motion many times, no peeling occurred at the joint.

Example 4 Thickness: 40μ, porosity: 88%, average pore diameter: 0.2μ
Using an unfired PTFE porous sheet of
% and 60% in the width direction, all operations were carried out in the same manner as in Example 1 to obtain a stretchable laminate sheet.

The elongation rate of this laminated sheet is 30% in the length direction and 60% in the width direction, and the elongation movement in each direction is made to reach the above elongation rate, and then the elongation movement is repeated many times to release the elongation state. However, no peeling occurred at the joint.

Furthermore, the average pore diameter of the micropores in the PTFE porous sheet that had been subjected to follow-up elongation was 0.3μ.

[Brief explanation of the drawing]

FIGS. 1 and 2 are enlarged cutaway sectional views showing examples of the state of the base fabric and the PTFE porous sheet in the joining process and stretching process in the present invention;
FIG. 5 is an enlarged cutaway sectional view showing an example of a laminated sheet obtained by the method of the present invention. 1... Base fabric, 2, 2'... PTFE porous sheet, 3, 3'... Adhesive.

Claims (1)

[Claims] 1 Stretchable base fabric and unfired polytetrafluoroethylene porous sheet or true specific gravity of 2.20
The following fired polytetrafluoroethylene porous sheets are partially joined together, and then the base fabric is stretched in a predetermined direction and the polytetrafluoroethylene porous sheet is stretched accordingly, and then the stretched state of the base fabric is released. A method for producing a laminated sheet, comprising: recovering the base fabric to approximately the same dimensions as before stretching, and retaining the polytetrafluoroethylene porous sheet at approximately the same dimensions as during subsequent stretching.