JPS5914594B2 - Manufacturing method of breathable leather - Google Patents

Description

[Detailed Description of the Invention] 5 The present invention is suitable for automobile seats, chair upholstery, sofa skins, cushion covers, sports mat covers, bag materials for various backrests, etc., which have water resistance and durability as well as appropriate breathability. The present invention relates to a method for producing breathable leather made of synthetic resin.

10 Traditionally, leather, textiles, and synthetic resin leather have been widely used for this type of application, but leather is expensive in addition to material constraints such as dimensional restrictions and difficulty in obtaining stable quality. The problem is that it is difficult to secure quantities.

In addition, although textiles have no problems with breathability and moisture absorption (15 points), they tend to get dirty easily, and spilled drinks such as juice and coffee are instantly absorbed. Furthermore, it has drawbacks such as poor weather resistance and strength. From these points, PVC leather, polyurethane leather,
It is a so-called synthetic resin leather such as No. 20 synthetic leather.
Synthetic resin leather is limited to a maximum width of 1500m7, but it can be made to any length, so there are no dimensional restrictions, and the quality is completely stable and of the same quality. It has a wide variety of properties, such as being extremely durable in terms of stain resistance and strength, and can be freely colored and printed, as well as being able to be made into hard or soft foam structures. Because of this, it is used in large quantities for the above-mentioned purposes. 30 However, this excellent synthetic resin leather had an extremely large drawback.

The point is that there is no breathability at all. Therefore,
Despite having the above-mentioned characteristics, there is the inconvenience that natural leather or textiles have to be used in fields where breathability is essential.

Due to this, many researches have been made to develop breathable leather, and various inventions for manufacturing breathable leather have been proposed, but nothing that can be put to practical use has yet appeared, and the emergence of effective breathable leather is still in progress. This is why it has been long awaited. The present invention relates to a novel method for manufacturing breathable leather with excellent performance, and an example of its implementation will be described below with reference to the drawings.

First, a continuous foamable synthetic resin paste 2 containing a foaming agent and a stabilizer is applied to the release surface of the release paper 1 (FIG. 3).

The release paper 1 used here is usually a high-strength paper such as kraft paper, one side of which has been treated with a resin that has mold release properties such as silicone resin or polyethylene resin, and is "compatible" with the synthetic resin paste. 2) When the synthetic resin paste is heat-gelled, it must not dissolve in the paste and must not transfer or peel off from the surface in contact with the paste coating. The open-cell foaming synthetic resin paste 2 used here is a viscous liquid paste made by adding a plasticizer and a diluent to the vinyl chloride resin obtained by emulsion polymerization. It is decomposed by heating, such as azodicarbonamide, to generate gas, and this gas causes the synthetic resin to foam.

So-called chemical blowing agents are added. Normally, azodicarbonamide is used to produce synthetic resin foam with a closed-cell structure, but as mentioned above, when the synthetic resin is in paste form, it can be used in combination with paraffin, wax, and surfactants to create an open-cell structure. It is known that a so-called open-cell foam can be obtained, and a paste made by this method is also used in the present invention. Such a paste can also be obtained using, for example, the foaming agent Uniform AZ-F manufactured by Otsuka Chemical Co., Ltd., and the stabilizer F, a stabilizer made specifically for this foaming agent manufactured by the same company, but the ingredients of both of these products are not clear. isn't it.

According to experiments by the present inventors, Zeon 25, Zeon 27
In the case of a resin system developed as a paste resin for closed cell foaming, the foaming agent azodicarbonamide and Na-Zn
Adeka Argus' MarkFL- system composite stabilizer
It can also be obtained by using 23. In addition to these stabilizers, synthetic resin pastes contain plasticizers as important ingredients. The plasticizer is a general plasticizer for PVC paste, such as phthalic acid esters represented by dioctyl phthalate (DOP), adipic acid esters represented by dioctyl adipaste (DOA), and butylbenzyl phthalate (BBP). Aromatic phthalate ester,
In addition to phosphoric acid esters such as tricresyl phthalate (TCP), epoxidized soybean oil, petroleum byproducts,
A large number of plasticizers such as secondary plasticizers such as chlorinated paraffin and high molecular weight plasticizers can be used alone or in combination. Further, if necessary, pigments, extenders, fillers, and fluidity regulators such as thixotropic agents are used. Apply the paste 2 obtained in this way to the release paper 1.
After being applied on top, the paste is placed in a heating furnace at a temperature at which the foaming agent does not decompose, i.e., 120-130°C, and heated for 2 to 3 minutes, causing the paste to lose its fluidity and enter a so-called semi-gelled state.

The semi-gelled film 7 in this state has a moderate adhesiveness on its surface, and can be attached to fabric or a synthetic resin sheet.

Such tackiness is lost as the semi-gelled film 7 cools, so that the semi-gelled film 7 sticks to the perforated sheet 3 immediately after leaving the heating furnace (FIG. 4).

The perforated sheet 3 is made of a soft vinyl chloride sheet or leather, and has pores with a diameter of about 0.8 to 2.0 and a perforation ratio of 2 to 5%, that is, the ratio of the perforated area to the total area. do. The porosity of the perforated sheet 3 has extremely important meaning.

In other words, this type of perforated sheet 3 has holes 4 to provide ventilation, so it is assumed that the holes have the diameter necessary for ventilation, but if the holes are too small, it will be difficult to actually use the sheet. can easily cause clogging.

Moreover, if it is too large, it not only looks artificial and undesirable, but also reduces the strength required as a skin material. From these points, the hole diameter is 0.8 m1
1). Above, it is better if it is 2.0 or less, and the porosity is 2 to 2.
If it is within the range of 5%, it will exhibit good air permeability and will maintain the tensile strength and tear strength required for a skin material. Further, the perforated sheet 3 may have a printed pattern and/or a squeezed pattern on its surface.
These should be chosen arbitrarily. Perforated sheet 3
The lamination with the semi-gelled film 7 is as described above.
If the process is carried out while the film is still hot, no adhesive is required, but depending on the temperature of the semi-gelled film, proper lamination may not be possible.

In that case, a method is used in which a thin layer of adhesive is applied to the back surface of the perforated sheet 3 in advance so as not to block the perforated portions 4, and after a suitable open time, the adhesive is laminated onto the semi-gelled film 7. . The adhesive used in this case is Pinilite VMCHO
MEKlO% solution, heat-activated acrylic adhesive, etc. are suitable. The perforated sheet 3 is laminated onto the semi-gelled film 7 with the release paper 1 attached to the semi-gelled film. This is 5.0 to 6.0 kg/i in terms of lamination of the perforated sheet 3.
This is because the release paper 1 needs to be reinforced to withstand the pressure. Also, if appropriate tension is not applied to each layer,
This can cause wrinkles, but if the release paper 1 is attached to the semi-gel 1 film, sufficient tension can be applied to prevent wrinkles. After the perforated sheets 3 are laminated in this manner, the release paper 1 is peeled off and removed (FIG. 5).

The laminated sheet thus obtained has enough strength to be manipulated independently and does not stick to other objects or cause blocking. Next, this laminated sheet is introduced into a heating and foaming furnace to gel the semi-gelled film layer and foam at the same time. ) The synthetic resin layer is introduced into a foaming furnace and foamed (Figure 2).

In this case, the term "placing" literally means "placing" and does not mean introducing the semi-gelled film and the backing material 5 into a foaming furnace after bonding, but rather positioning the laminated sheet on the backing material 5. This means that the laminated sheet has not been fixed in any way, such as by adhesion, in that state.

Although this placement with the backing material 5 is considered to be a unique technique, in reality, the semi-gelled film layer is heated and melted in the foaming furnace, and at the same time foams due to the decomposition of the foaming agent, increasing its volume. This melting and
Due to foaming, the foam 2'' naturally penetrates into the gaps in the backing material, and the bond is completed in the most stable shape without losing communication or enclosure.

Therefore, if an adhesive or the like is applied to the backing material to partially fix the semi-gelled film, the above-mentioned natural penetration will be inhibited, resulting in a negative impression. Also, during this melting and foaming, the perforated sheet 3 on the surface is heated at the same time, and the sheet itself becomes soft and sticky, so it welds with the foam layer T to complete a strong lamination. A laminated leather is obtained (Figure 2).

The laminated leather thus obtained has a foamed leather structure with high cushioning properties as a whole, but the foamed layer 2"
has an open cell structure.

The perforated sheet, that is, the skin layer 3, is a vinyl sheet or vinyl leather, and is perforated with holes 4 with a porosity in the range of 2 to 5%, so the laminated leather with the open-air foam has excellent breathability. Becomes a leather with a handle. Furthermore, no matter what material the backing material 5 is made of, such as non-woven fabric, knitted cloth, twill fabric, etc., the adhesiveness with the backing material 5 is achieved through natural penetration of the foam layer 2'' itself, so that continuity is completely lost. The result is a leather with excellent breathability that has never been seen before.Next, specific embodiments of the present invention will be described with reference to Examples.Examples
1. Manufacture of perforated sheet A soft vinyl chloride sheet with a thickness of 0.4 m1 and a leather-wrapped surface with a hole diameter of 1.0 m! Small circular holes of φ were punched over the entire surface in the shape of a base plate at five-round intervals using a punching machine.

The porosity in this case was 3%. The changes in strength and air permeability before and after opening the holes were as follows. As a result, the rate of change in physical properties of the material with a porosity of 370 was extremely small at 15% to 30%, and this degree of change in strength did not cause any problems in practice.

1 Air permeability was measured by the method below.
According to the "breathability" test method specified in 5, 19 of 4-72 "Testing methods for cotton fabrics".

*2 Retention rate was calculated using the following formula (B) Preparation of open-cell foamable synthetic resin paste *3 Nippon Zeon, emulsion polymer product, for paste The above ingredients were kneaded in a Lipon blender, and a low of about 4000 cps was obtained. Make a viscous paste.

Viscosity modifiers include, for example, texanol isoptylate (TX
IB) etc. which act as a plasticizer after film formation are suitable. (Production of laminated sheet) Apply the paste obtained in (B) to a thickness of 0.4 cm on release paper (for vinyl chloride paste) using a doctor blade method coater, and immediately heat for 2 minutes in a hot air heating oven at 120°C. It turned into a semi-gel.

In this case, there was no decomposition of the blowing agent.

The prepared Komei sheets were laminated using a lamination device installed immediately after coming out of the heating furnace, and the sheets were temporarily attached.

After this laminated sheet was sufficiently cooled using a cooling device, the release paper was peeled off, and the release paper and the laminated sheet were wound up using separate turret winders.

Because the release paper was only heated at a relatively low temperature of 120°C, it could be used repeatedly, and the longest-lasting paper was able to withstand 6 repetitions. (D) Foaming → Production of breathable leather Next, the double-sided knitted fabric that has been heat set in advance is introduced with a pin tenter into a hot-air foaming furnace heated to 21C, and the knitted fabric is introduced onto the double-sided knitted fabric. Introduce the laminated sheet obtained in step O at the same speed as the speed.

Foaming is completed after about 1.5 minutes of heating, and when it comes out of the oven, it is foamed leather with a thickness of 1.570 mm. In this case, the foaming ratio of the foam layer was approximately 2.5 times. There was no penetration of the foam layer into the area where the small holes were made, and the original shape of the small holes was maintained. The breathability of this foamed leather is 1.2d/(1
-JMoVf/SeC, it had extremely excellent air permeability, and surprisingly, it also showed excellent water permeability and moisture permeability. Example 2 (4) The perforated sheet was produced in the same manner as in Example 1.
I went further.

(3) Preparation of open-cell foaming synthetic resin paste During the formulation in Example 1, Zeon 121 was changed to Zeon 27, and Uniform AZ-F was replaced with azodicarbonamide (AC).
Example 1
Similarly, a paste with a viscosity of about 4000 cps was obtained using a viscosity modifier.

The steps of manufacturing the (O laminated sheet and (O foaming → manufacturing of breathable leather) were performed in the same manner as in Example 1, and breathable leather was obtained.

The breathability of this breathable leather is 1.8cd/Cd/Sec
It had water permeability and moisture permeability similar to that of Example 1. Example 3 (4) The thickness of the vinyl layer is 0.3 m1
Then, a small circular hole with a hole diameter of 1.5 mmφ was inserted into a soft vinyl sheet with an ancient stain pattern printed on the surface and a leather drawing.
After perforating the entire surface with a punching machine at intervals of 7 nm, this sheet was layered on cheesecloth through an extremely thin non-woven heat-sensitive adhesive cloth of 25 f1/Trl and heated at 120°C.
It was heated to a temperature of 100 mL and made into a leather cloth shape.

The physical properties and air permeability of the leather cloth with the same shape without holes and the leather cloth with holes are shown in Table 2. As a result, the porosity was 2.5%, and in the case of a leather cloth-like perforated sheet, the retention rate was better than that of Example 1, 0% to 1.2%.
It can be said that there is almost no change within the range of change.

(8) Preparation of open air permeable synthetic resin paste The above-mentioned mixture was processed in the same manner as in Example 1 to form a paste with a viscosity of about 4000 cps.

(Production of O laminated sheet and (D) foaming → production of breathable leather were performed in the same manner as in Example 1 to obtain breathable leather. The breathability of this breathable leather was 1.5Ci.
t/d/SeC, and an excellent breathable leather similar to that of Example 1 was obtained.

[Brief explanation of the drawing]

The drawings show an example of the implementation of the method for manufacturing breathable leather of the present invention, in which FIG. 1 is a perspective view of the manufactured breathable leather, FIG. 2 is an enlarged sectional view, and FIGS. 3 to 6 are cross-sectional views. These are cross-sectional views showing the order of the steps, in which 1 is a release paper, 2 is a synthetic resin paste, 2' is a semi-gelled layer, 2'' is a foam layer, 3 is a perforated sheet, and 5 is a backing material.

Claims (1)

[Claims] 1. A continuous foaming synthetic resin paste containing a foaming agent and a stabilizer is applied onto a release paper, and the paste is heated to gel at a temperature range in which the foaming agent contained in the synthetic resin paste does not separate. After gelation, under conditions where the gelling surface is heated and tackiness is maintained on the surface, a pre-prepared 0.
A perforated sheet with small holes having a hole diameter of 8 to 2.0 mm and a porosity of 2 to 5% is pressed and crimped,
After cooling, the release paper is peeled off, and then a backing material is laminated or placed on the backing material and introduced into a foaming furnace, and the open foamable synthetic resin layer is heated and foamed to form an open foam layer. A method for producing breathable leather, characterized by: 2. Air permeability according to claim 1, wherein the foaming agent contained in the synthetic resin paste is azodicarbonamide, and the stabilizer for these contains alkali metals such as Na and K and Zn. How to make leather.