JPS6011147B2 - Web joining method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for joining fleece-like non-woven webs made of thermoplastic filaments, and more specifically, to a method for joining such webs to provide excellent strength and drape properties, and to prevent fuzz. This invention relates to a method for producing nonwoven fabrics.

Nonwoven fabrics have developed significantly in recent years due to their simplified processes and excellent properties, and among these methods, the method of forming webs using long fibers is attracting attention in terms of strength and productivity. .

It is known that the properties of nonwoven fabrics vary greatly depending on not only the material used to form the web, but also the method of joining the webs.

The main bonding methods for conventional long-fiber nonwoven fabrics include methods using adhesives, interlacing yarns by needle punching, and methods using thermocompression bonding and heat fusion.
Although actually used in manufacturing, each individual method has both advantages and disadvantages as described below. That is, in the method using adhesive, the fuzz on the surface is suppressed, and
Although it has the advantage of being easy to join coarse nonwoven fabrics, it has disadvantages such as a stiff texture and difficulty in penetrating the adhesive into thick nonwoven fabrics, making it difficult to bond them properly.

The method using needle punching has the advantage of providing a soft texture and texture, but it can only be applied to thick nonwoven fabrics, and has the disadvantage of not being able to punch thin fabrics and causing fluff. The method of thermocompression bonding/thermal fusion is as follows:
The apparatus is simple, as it consists of thermo-compression bonding of a web made of one component or a web made of two components having a difference in melting point using heated rolls, or by melting a low melting point component by heating.
It has the advantage of being able to be applied to thin materials, but it also has a poor texture.
The problem is that there is an inverse relationship between the amount of heat and fluff, and it is difficult to satisfy both requirements at the same time.There are also drawbacks that thick nonwoven fabrics cannot be heated to the inside and cannot be applied. As described above, with the conventional joining methods, it has not been possible to simultaneously satisfy the requirements for texture, fluffiness, and web thickness.

In order to use nonwoven fabrics in the clothing field, the present inventors believe that it is important to freely change the texture, fluff, and web thickness, and have developed a web joining method that satisfies these factors at the same time. The present invention was arrived at as a result of intensive research. When joining fleece-like nonwoven webs made of thermoplastic filaments, the present invention heats and fuses only the surface layer of the web, and then uses ultrasonic waves to reach the inside of the web in spots and parts. Provided is a method for joining fleece-like non-woven webs, which is characterized by melt-joining the fleece-like non-woven web until it reaches the desired temperature.

That is, the present invention uses a combination of partial but internal soldering using ultrasonic waves and bonding of only the surface layer using heat fusion. It has now become possible to obtain a nonwoven fabric that has a thickness selected to be as high as 100%, and also has various properties such as softness and a drapey texture, which were previously unobtainable.

Moreover, in the past, thick non-woven fabrics with a thickness of 100 mm or more were unavoidably textured and only hard materials could be obtained.
It has become possible to provide a nonwoven fabric that is soft to the touch and has no fluff, and can be used as a substitute for textiles. As shown in FIG. 1, the ultrasonic device used here includes, for example, an ultrasonic oscillator 1 that causes a vibrator 2 to generate ultrasonic vibrations of 15 to 5,000 kilohertz, and the tip of a horn 3 There is one in which the projections 6 on the surface 4 are pressed against the web 5 and are brought together after melting.

The protrusions 6 on the working surface 4 are formed into circular shapes as shown in FIGS. Or, it has a non-circular tip surface and has a dotted pattern like polka dots (
They must be arranged in an embossed pattern).

By adopting such a shape, the vibration energy of the ultrasonic wave is preferably concentrated at the tip of the horn, and there is an advantage that bonding can be performed easily and firmly. Further, it is preferable that the output of the ultrasonic wave is high, and for example, 500 W or more is required. Although this ultrasonic acting surface may apply acid pressure to the web by vertical movement, it is more convenient to apply pressure to the web as a rotating body. This ultrasonic bonding is adjusted by the output of the ultrasonic waves, the shape and pressure of the working surface pressed against the web, and the pressing time.

When the web is pressed by the working surface of the horn, the parts that receive the ultrasonic energy from the protrusions on the working surface are melted and bonded, but other parts of the web are melted and bonded even if the surface of the web touches the concave part of the working surface. There is almost no change at all.

Therefore, a web that has only been partially melted and bonded by ultrasonic waves exhibits sufficient resistance to tension, has a texture, and is extremely soft (like cotton to the touch). However, it becomes extremely fluffy when subjected to friction, so it can hardly be used in the clothing field as it is. In order to suppress this surface fuzz, in the present invention, it is necessary to heat and adhere only the surface layer of the web.

The most effective method is to use heated rolls. That is, this objective can be achieved by defining the gap between the heating rolls so as not to compress the web too much and passing the web through the gap while controlling the surface temperature of the rolls. According to the results of the experiment, the distance between the rolls was set to 50 to 80% of the thickness when the web was compressed at room temperature with a pressure of lk9', and the roll temperature was set to It has been found that by setting the temperature at T°C, expressed as t+102TZr30, where the softening point is t°C, and passing the web through the gap, it is possible to prevent only surface fuzz while maintaining the web's softness. Ta.

There is no difference in the physical properties and texture of the resulting nonwoven fabric between bonding the web surface layer and melt bonding using ultrasonic waves, but after the web surface layer is heated and woven, ultrasonic melt bonding is performed. It is preferable to use sound waves to prevent troubles caused by fluffing of the web.

Next, the present invention will be explained with reference to examples, and the drapability and number of folds shown in the examples are used to indicate the cloth-like feel.

That is, the drape property is measured using a normal drave meter, and is expressed as the area projected onto a plane. and the drave coefficient is distributed between 0 and 100%,
The smaller the value, the easier it is to drape.

The number of bends was determined as follows.

In other words, a double sheet of 25 sides x 25 sides obtained by folding a test sheet of 5 enemies x 26 sides into two has 100
Apply the evening load for 5 minutes. Remove the load, open the double sheet and leave it for 1 minute, leaving it as a single sheet. Thereafter, an attempt is made to fold the sheet in two as described above. If the sheet does not fold but unfolds without applying a load, repeat the above cycle.
The number of cycles until the test sheet continues to bend without applying any load is defined as the number of bends. In addition, the fuzziness was evaluated using a Gakushin type friction fastness tester (manufactured by Daiei Kagaku Kasuki Seisakusho), and friction was performed 100 times under a load of 3009, and the fuzziness was evaluated in the following five stages. . For practical clothing fabrics, the drape is 50-70%, the number of folds is 5 or more, and the fuzz rating is 1-2.

Example 1 Polypropylene (MI=5) was extruded at 270 qo through a rectangular grade hole having a diameter of 0.45 willow and a number of holes of 300. After suction and stretching with a air sucker installed at 800 feet under the grade hole, a web accumulation device made of a wire mesh was produced. A non-woven fleece-like web was formed.

When the thickness of this web was measured at room temperature and under a pressure of 1 kg/ground, it was found to be on the 0.18 side.

This web was passed between two heated rolls with smooth surfaces heated to 135° C. and whose gap was adjusted to 0.13 mm at a speed of 5 mm/min, and then passed through at a speed of 19 mm. String position, output 7
Ultrasonic waves of 00 W were applied to the web through an action surface (FIG. 3a) in which cylindrical protrusions each having a diameter of 1.5 legs were arranged in a dot shape to melt and bond them. The strength and elongation, drapability, number of bends, and fluff of the thus obtained web were measured and the following values were obtained.

Tensile strength: 7k9-3 Tensile elongation in skin
75% drapeability
63% number of bends
8 times fluff measurement 2
All of these values fall into the realm of cloth,
In fact, the texture of the web was very similar to that of cloth.

Example 2 Polycabrolactam with a relative viscosity of 2.3 (1% solution of 99% concentrated sulfuric acid) was extruded at 270 mm through a rectangular paper with a diameter of 0.25 willow and 300 holes, and stretched with suction using an air sucker. Then, a web was formed using a web accumulating device made of a 30-mesh wire mesh.

The thickness of this web was measured under a pressure of lk9/ground and was found to be 0.15 willow.

This web (while still being placed on a wire mesh) is transferred and passed between two heating rolls controlled at 16yo with varying gaps, and then 19. Ultrasonic waves with a frequency of 100 W and an output of 100 W were applied to the web from the working surface (FIG. 3c) on which the willow square prism-shaped protrusions were arranged at a pitch of 5; the web was melted and bonded. The web conditions obtained under each condition are as follows. According to this, when the web is fused to the inside with a heating roll, it becomes paper-like in texture, and conversely, if the surface is not sufficiently fused, it becomes too fluffy and cannot be used as a cloth.

As described above, in the present invention, when joining webs, the joining up to the inside and the joining of the surface layer can be separated and adjusted separately, which has the advantage of being able to freely change the texture. We have it.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram of the ultrasonic bonding device used in the present invention, Fig. 2 is an enlarged view of the working surface of the device shown in Fig. 1, and Fig. 3 a, b, c, and d are respectively functional views. FIG. 3 is a schematic diagram showing an example of an embossed pattern on a surface. 1 is an ultrasonic oscillator, 2 is a vibrator, 3 is a horn, 4 is a working surface, and 6 is a protrusion. 5 is the web. Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] 1 When joining fleece-like non-woven webs made of thermoplastic filaments, only the surface layer of the web is heated and fused, and then the web is dotted and partially melted by ultrasonic waves until it reaches the inside of the web. A method for joining a fleece-like non-woven web, characterized by joining.