JPS63132625A - Wiping cloth and its production - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a wiping cloth and a method for manufacturing the same, and more specifically, the present invention relates to a wiping cloth that does not generate lint and is optimally used in clean rooms such as the food industry and electronic industry. in,
Moreover, the present invention relates to a wiping cloth with unprecedented soft texture and wiping performance, and a method for manufacturing the same.

[Conventional technology] Conventionally, wiping cloths used in clean rooms, etc. have been made of direct method nonwoven fabrics using melt blowing, spunbonding, or flash spinning methods, while dry nonwoven fabrics using stable fibers and ultrashort fibers have been used as wiping cloths. Compared to paper or wet-laid non-woven fabric made using a paper-making method, it is suitable for use because it generates extremely little lint.

In addition, as a technology using the melt blow method, improvements have been made to prevent the generation of lint due to fiber cutting during use, such as European Patent No. 16474.
No. 0 discloses an apertured nonwoven fabric using hot embossing and hot stretching that is most similar to the present invention, and similarly, U.S. Pat. has been done.

[Problems to be solved by the invention] The above-mentioned European Patent No. 164740 and US Patent No. 4469
The wiping cloth disclosed in No. 734, which utilizes a micro-fine web with a fiber diameter that is extremely V&Tight, has a much tighter fiber diameter than those made using the spunbond method, so it is effective in wiping V&Fine dust. It has the advantage of being of good quality and having a soft surface so that equipment, test parts, etc. do not come into contact with it. However, wiping cloths made of these ram fibers have inferior mechanical properties such as strength compared to those made using spunbond methods, and also have the disadvantage of generating lint when fibers are cut due to their low single fiber strength. Ta.

For this reason, the technology disclosed in the above-mentioned European patents improves mechanical properties and improves ta
Although the above disadvantages can be prevented by using heat fusion, the texture becomes stiff and does not fit well with equipment, etc., and when used as a wet wipe. has disadvantages such as difficulty in forming marks, and lacks suitability as a wiping cloth.

Furthermore, the above-mentioned European patents and US patents are characterized in that various performances as a wiping cloth are improved by providing openings, so it is thought that mechanical properties and liquid retention properties are improved. Since the fibers in these openings are melted and turned into resin, there is a risk that the resin may be lost due to friction during wiping and generate dust, so it is not necessarily satisfactory as a wiping cloth for use in clean rooms, etc. Ta.

Therefore, it is an object of the present invention to obtain a wiping cloth that uses fine fibers, has extremely excellent wiping performance, does not generate any lint, and is much softer than conventional wiping cloths. .

[Means for Solving the Problems] The present invention provides a wiping cloth made of a melt-blown non-woven fabric in which the intersection points of each wt fiber constituting the web are fully or partially heat-sealed.
A wiping cloth having a structure oriented in an axial or biaxial direction, and characterized in that: (i) it is a nonwoven fabric and/or an electret nonwoven fabric to which a dust adsorbent is attached;
Then, the intersection points between the fibers constituting the web formed by the melt-blowing method are fully or partially heat-sealed at a temperature of 100°C below the melting point of the navy blue to 30°C below the melting point, and then heated to room temperature to 30°C below the melting point. The present invention relates to a method for producing a wiping cloth, characterized in that a stretching process of 1.1 to 1.5 times is performed in 10 or 2 axial directions at a temperature of 60°C.

[Function] First, the melt-blown nonwoven fabric that is the main component of the wiping cloth of the present invention will be explained. Web forming technology by the melt-blowing method is described in, for example, the US Naval Research Institute's report Manufacture of 5up.
erfine Organic Fibers' (10
It is possible to use well-known techniques such as those published on April 15, 1954).

As materials suitable for these melt blowing methods, all thermoplastic resins such as polyamide, polyester, polyolefin, and polystyrene can be used, but in particular, when polypropylene is used, it has excellent web forming properties, and Since polypropylene is essentially lipophilic, by making it hydrophilic with a surfactant, etc., it is possible to obtain extremely excellent wiping performance against both oil and water, so it is considered optimal. It will be done.

Usually, the nonwoven fabric formed by the melt blowing method described in "-" has an extremely fine fiber diameter of 10μ or less, and is used as a wiping cloth. [It has the effect of reliably collecting dust and preventing re-scattering, and the fine fiber diameter makes the surface of the wiping cloth soft,
It has the effect of eliminating frictional problems.

The web formed by the melt-blowing method is then heated to a temperature of 100° C. below the melting point of the fibers to 3° C. below the melting point of the fibers in order to improve mechanical properties and prevent the dark blue from falling off.
Fully or partially fused at a temperature of 0°C.

This heat fusion means does not require any special equipment, for example, a method in which the web is passed between two wooden heat rolls with a smooth surface or a heat roll with embossing on one side;
Alternatively, a method of hot pressing into a flat plate can be adopted.

Temperature control is important as a condition for this heat fusion process, and temperature is 100°C below the melting point of the fibers that make up the melt-blown nonwoven fabric.
It is necessary to perform thermal fusion at a temperature of 30°C to 30°C. If the heat treatment temperature is more than 100°C lower than the melting point of the fibers, the bonding at the intersections between fibers will be poor, resulting in poor mechanical properties.
In addition, it is inconvenient because it does not prevent the TA fibers from falling off.
If the temperature is higher than 30°C below the melting point of the fibers, the bonds between the fibers will become stronger and the mechanical properties will improve, but the nonwoven fabric will not become flexible during the stretching process, and the fused portions will become resinous. This is not desirable as it may generate dust.

The above temperature range is much lower than the temperature range used in the well-known heat fusion method, and can be suitably used only for melt-blown nonwoven fabrics.

The pressure in v4 fusion process is 10 to 200 kg/c
A condition of about m2 is preferable, but it is determined as appropriate in consideration of the production speed, emboss shape, texture of the product, etc.

Next, the enlarging process, which is the gist of the present invention, will be explained.

The conventional wiping cloth using the melt blow method is
Two series of heat-sealed products were used as they were, or they were used with auxiliary agents attached, or they were used after undergoing hole-opening treatment, etc. as in the above-mentioned European patents, etc. As explained above, the material has a hard texture and does not blend well with equipment when wiping dust, and may cause scratches when wiping soft materials.

For this reason, the inventor of the present invention, as a result of intensive studies, found that the ratio of 1.1 to 1! They discovered that when subjected to a 5x enlargement treatment, the texture was significantly improved compared to that before treatment, and they completed a wiping cloth that could take full advantage of the advantages of melt-blown nonwoven fabrics. .

The reason why the stretching process makes the heat-sealed melt-blown non-woven fabric extremely flexible is not clear, but it is possible that it increases the degree of freedom of the non-woven fabric by destroying a part of the fused structure, or , the fine particles that make up the non-woven fabric! It is thought that the orientation of the I fibers improves the slippage between the fibers.

These drawing treatments need to be carried out at temperatures ranging from room temperature to 60° C., that is, under conditions where the fibers do not exhibit crystal orientation due to drawing. If the temperature exceeds 60°C, the bonding state due to heat fusion will not substantially change, and the fibers will simply be stretched, resulting in poor softening effect, and if the temperature is lower than room temperature. The enlarging process in
This is not preferable because it may cause fibers to fall off or the joints to be damaged and dust to be generated.

Also, regarding the enlargement magnification, a good softening effect can be obtained in the range of 1.1 to 1.5 times, preferably 1.2 to 1.3 times; inferior to chemical action, 1
．． If it exceeds 5 times, it is not preferable because there is a risk of generation of lint due to fiber breakage.

The flexibility of melt-blown nonwoven fabric subjected to stretching treatment is J
The degree of softening can be measured by a bending test using the cantilever method specified in IS L-1096. Usually, the melt-blown nonwoven fabric softened by the method of the present invention has a bending resistance of 2 to 3 compared to that before stretching.
Below, the bending strength is preferably reduced to about 1/2, and the bending resistance is 80++v.
Although a product with a bending resistance of 701 or less can be obtained, it is desirable to have a bending resistance of 701 or less in order to suitably use it as a wiping cloth.

To explain these methods of offshore removal processing,
A method of stretching the material by passing it between 2IJ'I nip rolls having a predetermined speed difference, a method of passing the material while applying tension between gears having a predetermined peak height, or a method in which the feed width and the feed width are set to a predetermined size. There are methods such as passing the nonwoven fabric through a designed pin tenter, but in terms of productivity and stable mass production, the method of passing the nonwoven fabric between two sets of nip rolls is considered optimal.

The wiping cloth produced by the method described above can be further subjected to post-treatment to improve its wiping performance.

Post-treatment is extremely effective in improving wiping performance and preventing dust once attached from being scattered again.

As the adsorbent used in the post-treatment, anionic or nonionic surfactants, adhesives, or the like can be used. Suitable surfactants for the wiping cloth of the present invention include sulfosuccinic acid type and nonylphenyl polyalkoxy alcohol type, and adhesives include natural rubber type, acrylic type, polyvinyl ether type, etc. , mixtures of these are available.

As an alternative technique to using these dust adsorbents, applying a high voltage to a melt-blown nonwoven fabric to turn it into an electret is also a desirable means for improving the performance of the wiping cloth. Various methods are known regarding electretization technology, but the method proposed by the present inventors is disclosed in Japanese Patent Application No. 59-23678, which allows nonwoven fabric to be electretized at room temperature without heating.
The most suitable method is to bring a nonwoven fabric into close contact with a ground electrode having a smooth surface, form an electric field between it and a high voltage electrode, and apply the electric field by corona discharge.

With this electret technology, the melt-blown nonwoven fabric is permanently charged and exhibits an electrostatic adsorption effect, so that a wiping cloth capable of adsorbing even extremely V&M dust can be obtained.

These post-treatment techniques are usually performed on melt-blown nonwoven fabrics that have undergone web formation, heat-sealing treatment, and stretching treatment, but needless to say, treatments may be applied during these steps as necessary. It is also possible to do so, and the present invention does not exclude these aspects.

EXAMPLES Hereinafter, the wiping cloth of the present invention and its manufacturing method will be described in more detail with reference to Examples, but the present invention is not limited to these Examples.

[Example 1 A web made of polypropylene with an average fiber diameter of about 2 It and a weight ff of 160 g/m2 was formed by the comel blow method, and the area of the pressed part with the surface temperature set at 95°C was 12
% heated embossing roll and a smooth surface roll to obtain a melt-blown nonwoven fabric in which inter-fiber intersections were bonded.

Next, this nonwoven fabric was passed between a nip roll with a speed of 50 m/s+in and a nip roll with a speed of 60+++/win at room temperature, and was passed about 1 in the processing direction of the nonwoven fabric.
, 2 ('') to soften it, and then impregnate it with a nonylphenyl polyalkoxy alcohol-based surfactant so that it adheres to about 0.5% of the solid content M to the nonwoven fabric. After drying, the wiping cloth of the present invention was obtained.

In order to evaluate the mechanical performance of the obtained wiping cloth, the strength and elongation were measured according to 6.12 of JIS L-1096, and the bending resistance was measured according to the cantilever method according to 6.19. In addition, the lint-free performance as a wiping cloth for clean rooms is JISL-1085.
Using the apparatus shown in 5.11, in a 1 quart container,
Two 10 cm square test pieces and 400 cc of ethanol were added, and after shaking for 20 minutes, the ethanol was filtered through black paper, and the weight of the filtered lint was measured using a precision balance. The lint weight per gram is shown in the table.

In addition, the wiping performance was evaluated by using carbon black powder with a particle size of about I B, water, and kerosene as dust, and scattering each on an acrylic plate. In order to evaluate the size of the wiping residue and examine the friction damage during wiping, we created a black soft polyvinyl chloride sheet that is prone to chalk marks by filling it with Calcylano carbonate to a large size. A wiping cloth was pasted on the sheet surface to a test member with a weight of 00 g and a base area of ICII+2, and the presence of scratches was examined and evaluated when rubbed at a speed of IOc+++/see.

For comparison with the wiping cloth of the present invention, a paper wiping cloth of the same weight as Example 1 and a paper wiping cloth that was the same as Example 1 but not subjected to the enlarging process were also subjected to the same test as comparative examples. The results are shown in Table 1.

As is clear from Table 1, the wiping cloth according to the present invention is much softer than conventional wiping cloths, generates virtually no lint, and even in actual wiping tests. It showed extremely excellent wiping performance without damaging the target.

[Example 2] Made of the same polypropylene as in Example 1, the average fiber diameter was about 2 lt and the weight was 60 g/n+ by the melt blow method.
The melt-blown nonwoven fabric was passed between a heated embossing roll with a pressing area of 0% and a smooth surface roll whose surface temperature was set to 5]0°C and a smooth surface roll to bond the intersection points between the fibers. I got it.

This nonwoven fabric was then heated to 40°C at a rate of 50+
nip roll of s/+sin and speed of 70 m/s at room temperature.
The nonwoven fabric was passed between win nip rolls and stretched 1.4 times in the processing direction of the nonwoven fabric to soften it.

Next, this softened nonwoven fabric was placed on a grounded electrode with a smooth surface at room temperature, and subjected to corona charging treatment between a 14 KV DC high voltage electrode to form an electret fabric according to the present invention. Got a wiping cloth.

The obtained wiping cloth was subjected to the same tests as in Example 1, and the results are also shown in Table 1. Like Example 1, this cloth was also extremely flexible and had excellent wiping performance. Moreover, the carbon black powder, which is a fine powder with a particle size of approximately 1/J, has a wiping performance that is even better than that of Example 1, making it the most suitable wiping cloth for V&fine dust. there were.

[Example 3] A web made of polyester with an average fiber diameter of about 3 B, m ff1808/m2 was formed by the melt blowing method, and the pressing area area was 4 months with the surface temperature set at 80°C.
% heated embossing roll and a smooth surface roll to obtain a melt-blown nonwoven fabric in which inter-fiber intersections were bonded.

This nonwoven fabric was then heated at a surface temperature of 55°C and a speed of 50 m/min.
+win two, tuberol and speed is 65s+/ at room temperature
The nonwoven fabric is made to pass through a thin nip roll and stretched 1.3 times in the processing direction to make it soft.Then, the softened nonwoven fabric is coated with an acrylic hot melt adhesive using a hot melt spray device. , about 153/
By uniformly adhering s2, another wiping cloth according to the present invention was obtained.

This cloth was also subjected to the same tests as in Example 1, and the results are shown in Table 1. It is a disposable wiping cloth that is extremely flexible, has excellent wiping performance, and does not re-scattering dust. It was the most suitable one.

Table 1 [Margins below] [Effects of the Invention] The wiping cloth [1] made of the melt-blown nonwoven fabric according to the present invention is more flexible than the conventional one made of long fiber nonwoven fabric, which is said to generate less lint. Excellent. This not only prevents damage to equipment, etc., but also adapts extremely well to complex shapes, minute gaps, corners, etc. As a result, wiping performance is further improved and the work environment is kept safe and secure. Make it comfortable.

Moreover, products with dust adsorbents or electret products have high wiping speed and efficiency, so cleaning can be done in an extremely short time.
Production efficiency can be increased.

In addition, the method for manufacturing the wiping cloth of the present invention simply adds one step of stretching treatment to the conventionally known melt-blown non-woven fabric 1 in which the fibers are heat-sealed. It can be made flexible very easily and reliably, and has extremely high productivity and production value.

Therefore, the wiping cloth and its manufacturing method of the present invention have not only the wiping performance as a wiping cloth, but also productivity, safety, and economical quality, which has an unprecedented utility value. It provides high-quality products.

Claims (9)

[Claims] (1) A wiping cloth made of a melt-blown non-woven fabric in which the intersections between the fibers constituting the web are fully or partially heat-sealed, the melt-blown non-woven fabric having a structure oriented in one or two axes, In addition, a wiping cloth characterized by having a dust adsorbent attached thereto. (2) The wiping cloth according to claim 1, which has a bending resistance measured by a cantilever method of 70 mm or less. (3) The wiping cloth according to claim 1, wherein the adsorbent is an anionic or nonionic surfactant. (4) The wiping cloth according to claim 1, wherein the adsorbent is an adhesive. (5) A wiping cloth made of a melt-blown non-woven fabric in which the intersections between the fibers constituting the web are fully or partially heat-sealed, the melt-blown non-woven fabric having a structure oriented in one or two axes, Furthermore, a wiping cloth characterized by being made of an electret nonwoven fabric. (6) The wiping cloth according to claim 5, which has a bending resistance measured by a cantilever method of less than 70 mm. (7) The intersection points between the fibers constituting the web formed by the melt blowing method are fully or partially heat-sealed at a temperature of 100°C below the melting point of the fibers to 30°C below the melting point, and then at room temperature to 60°C. 1. A method for manufacturing a wiping cloth, characterized in that a stretching process of 1.1 to 1.5 times is carried out in one or two axes at a temperature of °C. (8) The method for manufacturing a wiping cloth according to claim 7, wherein the enlargement processing magnification is 1.2 to 1.3 times. (9) The wiping cloth according to any one of claims 7 to 8, to which a surfactant or adhesive is attached as a dust adsorbent.