JPH0622891A - Wiping cloth and its production - Google Patents

Abstract

PURPOSE:To provide the wiping cloth which has excellent wiping performance, entirely obviates the generation of lint and is much softer than the conventional wiping cloths. CONSTITUTION:The wholly or partially thermally fused melt-blow non-woven fabric of the wiping cloth consisting of the melt-blow non-woven fabric which is wholly or partially thermally fused by a heating and pressurizing treatment at the intersected points of the respective fibers constituting a web has a structure oriented in the uniaxial or biaxial directions by a stretching treatment. The wiping cloth having 70mm or less bending resistance by a cantilver method is thus obtd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wiping cloth and a method for manufacturing the same, and more particularly, it is optimally used in a clean room such as the food industry or the electronic industry, and is free from the occurrence of lint. The present invention relates to a wiping cloth having a soft feeling and a wiping performance, and a manufacturing method thereof.

[0002]

2. Description of the Related Art Conventionally, as a wiping cloth used in a clean room or the like, a direct method non-woven fabric such as a melt blow method, a spun bond method, or a flash spinning method is used. Compared to the paper or wet-laid nonwoven fabric produced by the papermaking method used, it has very little lint generation and is therefore preferably used.
In addition, as a technique utilizing the melt blow method, for example, as a technique using an improved technique for preventing lint generation due to fiber cutting during use, for example, European Patent No. 16474.
No. 0 discloses a perforated nonwoven fabric that utilizes hot embossing and hot stretching, which is the most similar to the present invention. Similarly, US Pat. No. 4,469,734 discloses a perforated nonwoven fabric with less lint generation due to heat treatment. .

[0003]

Problems to be Solved by the Invention European Patent No. 1 mentioned above
No. 64740 and U.S. Pat. No. 4,469,734 use a wiping cloth that uses a microfine web having an extremely fine fiber diameter. It has the advantages of excellent wiping action, soft surface condition, and no damage to equipment, test parts, etc. However,
Wiping cloth made of these fine fibers is inferior in mechanical properties such as strength as compared with those such as spunbond method,
Further, since the strength of the single fiber is low, there is a drawback that lint is generated by cutting the fiber. Therefore, the technique disclosed in the above-mentioned European patent is to improve the mechanical properties and prevent the fibers from falling off by heat-sealing the intersections between the fibers. If it does, although the above drawbacks can be prevented, the texture becomes hard, it is not familiar with equipment etc., and further, there are drawbacks such as difficulty in squeezing when used as a wet wipe, and it is said that it is not suitable as a wiping cloth. There was a flaw. Further, the above-mentioned European patents and US patents are both characterized by improving various performances as a wiping cloth by providing an opening portion, so it is considered that mechanical properties and liquid retention are improved, Since fibers are melted and resinized in these openings,
Since there is a risk that the resin may be lost due to friction during wiping to generate dust, it is not always satisfactory as a wiping cloth used in a clean room or the like. Therefore, the present invention has an object to obtain a wiping cloth which has extremely excellent wiping performance by using fine fibers, has no lint, and is significantly softer than conventional ones. .

[0004]

The present invention provides a wiping cloth made of a meltblown nonwoven fabric in which the intersections between fibers constituting a web are wholly or partially heat-sealed by heat and pressure treatment. The melt blown non-woven fabric partially or partially thermally fused is uniaxially or biaxially stretched.
A wiping cloth having a structure oriented in the axial direction and having a bending resistance of 70 mm or less by a cantilever method, and an intersection point between fibers constituting a web formed by a melt blow method, By heat and pressure treatment at a temperature of 100 ° C. below the melting point to 30 ° C. below the melting point, the whole or a part of the heat fusion is performed, and then room temperature to 6
1.1 to 1.5 times the stretching treatment at 0 ° C
The present invention relates to a method for manufacturing a wiping cloth, which is performed in an axial or biaxial direction.

[0005]

First, the melt-blown nonwoven fabric, which is the main constitution of the wiping cloth of the present invention, will be described. Regarding the web forming technique by the melt-blown method, for example, a report "Manufacture of Superfine Org" of the United States Naval Research Institute is used.
Well-known techniques such as "anic Fibers" (issued April 15, 1954) can be used. As materials suitable for these melt-blowing methods, polyamide, polyester, polyolefin, or all thermoplastic resins such as polystyrene can be used, but particularly when polypropylene is used, excellent web formability is obtained, and Since polypropylene is essentially lipophilic, by applying a hydrophilic treatment with a surfactant, etc.,
It is considered to be the most suitable because it can obtain extremely excellent wiping performance against water. Usually, the non-woven fabric formed by the above-mentioned melt-blowing method has an extremely fine fiber diameter of 10 μ or less, and has a function as a wiping cloth to reliably catch fine dust and prevent re-scattering. In addition, the fact that the fiber diameter is fine has the effect of softening the surface of the wiping cloth and eliminating frictional obstacles.

The web formed by the melt-blowing process then has the intersections of the fibers at 100 below the melting point of the fibers in order to improve the mechanical properties and prevent the fibers from falling off.
The whole or part is fused by heat and pressure treatment at a temperature of 30 ° C. to 30 ° C. below the melting point. This means of heat fusion also
No special material is required, and for example, a method of passing the web between two surface smooth heat rolls or a heat roll having an emboss on one surface, or a method of performing a flat-plate hot press can be adopted. As a condition of this heat fusion treatment, temperature control is important, and it is necessary to perform heat fusion at a temperature of 100 ° C. to 30 ° C. below the melting point of the fibers constituting the melt blown nonwoven fabric. If the heat treatment temperature is lower than the melting point of the fiber by more than 100 ° C., the bonding at the intersections of the fibers becomes poor, the mechanical properties are inferior, and the fibers cannot be prevented from falling off. Is higher than 30 ° C. below the melting point of the fiber, the inter-fiber bond is strengthened and the mechanical properties are improved, but the non-woven fabric is not softened during the stretching treatment, and the fused portion is resinized to generate dust. This is not preferable because it may occur. The above temperature range is much lower than the temperature range used in the known heat fusion method, and can be suitably used only for meltblown nonwoven fabric. The pressure in the heat fusion treatment is 10 to 20
A condition of about 0 kg / cm ² is preferable, but it is appropriately determined in consideration of the production speed, embossed shape, or the texture of the product.

Next, the enlargement processing which is the gist of the present invention will be described. The conventional wiping cloth by the melt-blowing method is used as it is after being subjected to the above-mentioned heat fusion, or it is used by adhering an auxiliary agent or the like, or a perforating treatment is performed as in the above-mentioned European patents and the like. However, as described above, these materials have a hard texture, are not well compatible with equipment when wiping dust, and scratch when wiping soft materials. I was afraid. Therefore, as a result of continuing diligent studies, the present inventor has found that at a temperature of room temperature to 60 ° C., a uniaxial or biaxial direction of 1.1 is obtained.
It was found that, when subjected to a stretching treatment of 1.5 times to 1.5 times, the texture is significantly improved as compared with that before the treatment without substantially lowering the strength, and the advantages of the melt blown nonwoven fabric are as follows. This is a completed wiping cloth that can be used to the maximum. Regarding the action of the stretching treatment to make the melt-blown nonwoven fabric that has been heat-sealed extremely flexible, the reason is not clear, but the degree of freedom of the nonwoven fabric is increased by destroying a part of the fused structure, or It is conceivable that the orientation of the constituent fine fibers improves the slippage between the fibers.

These stretching treatments must be carried out at a temperature from room temperature to 60 ° C., that is, under the condition that the fibers do not exhibit crystal orientation due to stretching. When the temperature exceeds 60 ° C, the bonding state due to heat fusion does not substantially change, and the fiber is simply stretched, so the softening effect is poor, and the temperature is lower than room temperature. In this case, a large amount of tension is required for the stretching, and the stretching treatment may cause the fibers to fall off or the dust to be broken at the joint, which is not preferable. Further, the stretching ratio is 1.1 to 1.5 times, preferably 1.2 to 1.3 times in order to obtain a good softening effect, and if less than 1.1 times, the softening effect is obtained. If it is inferior in action and exceeds 1.5 times, lint may occur due to fiber cutting, which is not preferable.

Regarding the flexibility of the melt-blown nonwoven fabric subjected to the stretching treatment, the degree of softening can be measured by the bending resistance test by the cantilever method shown in JIS L-1096. In general, the melt-blown nonwoven fabric softened by the method of the present invention has a bending resistance of 2/3 or less, preferably about 1/2, and a bending resistance of 80 mm or less as compared with those before being stretched. However, it is desirable that the bending resistance is 70 mm or less in order to use it suitably for the wiping cloth.

The means for performing the stretching process will be described. A method of stretching by passing between two sets of nip rolls having a predetermined speed difference, and a method of passing between gears having a predetermined peak height while applying tension. There are methods such as passing through a pin tenter whose feed-in width and feed-out width are designed to the specified dimensions, but from the viewpoint of productivity and mass production stability, the method of passing the non-woven fabric between two sets of nip rolls is optimal. it is conceivable that.

The wiping cloth produced by the above-mentioned method can be further post-processed in order to improve the wiping performance. The post-treatment is extremely effective for improving the wiping performance and preventing re-scattering of dust once attached. As the adsorbent used in the post-treatment, an anionic nonionic surfactant, an adhesive or the like can be used. The surfactant suitable for the wiping cloth of the present invention is preferably sulfosuccinic acid-based or nonylphenyl polyalkoxy alcohol-based surfactant, and the pressure-sensitive adhesive is natural rubber-based, acrylic-based, polyvinyl ether-based, or the like. , Mixtures of these are available.

As a technique different from those utilizing these dust adsorbents, applying electrification by applying a high voltage to the meltblown nonwoven fabric is also a desirable means for improving the performance of the wiping cloth. Although various methods are known for electretization technology, Japanese Patent Application No. 59-236, which enables the non-woven fabric by the present inventors to be electretized at room temperature without heating.
The method shown in No. 78, in which a non-woven fabric is brought into close contact with a ground electrode having a smooth surface, an electric field is formed between the ground electrode and a high voltage electrode, and application is performed by corona discharge is most suitable. By this electretization technique, the melt-blown nonwoven fabric is permanently charged and exhibits an electrostatic adsorption action, so that a wiping cloth capable of adsorbing extremely fine dust can be obtained.

These post-treatment techniques are usually carried out on a melt-blown nonwoven fabric which has undergone web formation, heat fusion treatment, and stretching treatment, but needless to say, in the course of these steps, if necessary. However, the present invention does not exclude these aspects.
Hereinafter, the wiping cloth of the present invention and the method for manufacturing the same will be described more specifically according to examples, but the present invention is not limited to these examples.

[0014]

【Example】

Example 1 A web made of polypropylene having an average fiber diameter of about 2 μm and a weight of 60 g / m ² was formed by a melt blow method, and a heating embossing roll having a pressing portion area of 12% and a surface temperature set at 95 ° C. was smoothed. It was passed between surface rolls to obtain a melt-blown non-woven fabric in which inter-fiber intersections were bonded. Next, this non-woven fabric is passed between a nip roll having a speed of 50 m / min and a nip roll having a speed of 60 m / min at room temperature to perform a stretching treatment of about 1.2 times in the treatment direction of the non-woven fabric to soften it, and then A nonylphenyl polyalkoxy alcohol-based surfactant was impregnated so that about 0.5% of the solid content by weight of the non-woven fabric was adhered, and the impregnated product was dried to obtain the wiping cloth of the present invention.

In order to evaluate the mechanical performance of the obtained wiping cloth, the strength and elongation were measured according to JIS L-1096, 6.12, and the bending resistance by the cantilever method was measured according to 6.19. did. In addition, lint-free performance as a wiping cloth for clean rooms is JIS
Using a device shown in L-1185 5.11, two 10 cm square test pieces and 400 cc of ethanol were put into a 1-liter container, shaken for 20 minutes, and then the ethanol was filtered through a black filter paper. Then, the filtered lint weight was measured with a precision balance, and the lint weight per 1 g of the nonwoven fabric is shown in the table. In addition, the evaluation of the wiping performance was performed by using as dust, carbon black powder having a particle size of about 1 μm, water, and
Using kerosene, each was sprayed on an acrylic plate, evaluated by the size of the wiping residue when actually wiped, and a large amount of calcium carbonate was added to check the friction damage during wiping. Create a black soft polyvinyl chloride sheet that easily produces chalk marks.
A wiping cloth was attached to a test member having a bottom area of 1 cm ² at 00 g, and the presence or absence of scratches when rubbed at a speed of 10 cm / sec was examined and evaluated.

For comparison with the wiping cloth of the present invention, as a comparative example, a paper-made wiping cloth having the same weight as that of Example 1 (Comparative Example 1) and the same as Example 1 but not subjected to only stretching treatment. The same test was performed for the product (Comparative Example 2), and the results are shown in Table 1. As is clear from Table 1, the wiping cloth according to the present invention is significantly softer than the conventional one, and the occurrence of lint is not substantially recognized, and the wiping cloth is wiped even in the actual wiping test. It showed extremely excellent wiping performance without damaging the object.

Example 2 According to the melt-blowing method, the same polypropylene as in Example 1 was used to form a web having an average fiber diameter of about 2 μm and a weight of 60 g / m ² , and the pressing area was set to a surface temperature of 90 ° C. A 10% heated embossing roll and a smooth surface roll were passed between them to obtain a melt blown nonwoven fabric having interfiber intersections bonded. Then, this non-woven fabric is passed between a nip roll heated at 40 ° C. and a speed of 50 m / min and a nip roll at a normal temperature and a speed of 70 m / min,
The nonwoven fabric was stretched 1.4 times in the treatment direction to soften it. Then, this softened non-woven fabric is placed on a ground electrode having a smooth surface at room temperature and subjected to corona charging treatment with a high voltage electrode having a direct current high voltage of 14 KV to obtain an electretized present invention. Got a wiping cloth. The obtained wiping cloth was subjected to the same test as in Example 1 and the results are also shown in Table 1. This is also very flexible like Example 1 and has excellent wiping performance. The carbon black powder, which is a fine powder and has a particle size of about 1 μm, has more excellent wiping performance than that of Example 1, and was optimal as a wiping cloth for fine dust.

Example 3 A heated embossing roll having a pressing portion area of 14% and having a surface temperature of 80 ° C. was formed by a melt-blowing method to form a web of polyester having an average fiber diameter of about 3 μm and a weight of 80 g / m ^2. , And let it pass between the smooth surface rolls,
A melt blown non-woven fabric in which the fiber intersections were bonded was obtained. Next, this non-woven fabric was heated at a surface temperature of 55 ° C and a speed of 50 m / m.
It is made to pass between an in-nip roll and a nip roll having a speed of 65 m / min at room temperature to perform a stretching treatment 1.3 times in the direction of treatment of the non-woven fabric to soften it. The hot-melt pressure-sensitive adhesive was uniformly applied by a hot-melt spray device at about 15 g / m ² to obtain another wiping cloth according to the present invention. The same test as in Example 1 was conducted for this product, and the results are also shown in Table 1. However, it is extremely flexible and has excellent wiping performance, and there is no dust re-scattering.
It was the best as a disposable wiping cloth.

[0019]

[Table 1]

[0020]

EFFECT OF THE INVENTION The wiping cloth made of the melt-blown nonwoven fabric of the present invention is far superior in flexibility to the conventional one made of long-fiber nonwoven fabric which is said to generate less lint. Not only does this not damage the equipment, it is extremely familiar with complicated shapes, minute gaps, corners, etc. As a result, wiping performance is further enhanced, and the work environment is safe and comfortable. It should be Moreover, since the dust adsorbent is adhered to the electret product and the electretized product has a high wiping speed and wiping efficiency, the cleaning work can be performed in an extremely short time, and the production efficiency can be improved. In addition, the method for producing the wiping cloth of the present invention is very easy because it is only necessary to add one step of stretching treatment to the conventionally known melt-blown nonwoven fabric in which fibers are heat-sealed. In addition, it can surely be made flexible, and its productivity and production value are extremely high. Therefore, the wiping cloth and the method for manufacturing the same of the present invention provide not only a wiping performance as a wiping cloth, but also a product having a high utility value which is excellent in productivity, and further excellent in economic efficiency. It is provided.

Claims (2)

[Claims] 1. A wiping cloth made of a melt-blown nonwoven fabric in which intersections between fibers constituting a web are wholly or partially heat-sealed by heat and pressure treatment, and are wholly or partially heat-sealed. A wiping cloth, wherein the melt-blown nonwoven fabric has a structure in which it is uniaxially or biaxially oriented by a stretching treatment and has a bending resistance of 70 mm or less according to a cantilever method. 2. The entire or partial heat treatment is carried out by heating and pressing the intersection point between the fibers constituting the web formed by the melt-blowing method at a temperature of 100 ° C. to 30 ° C. below the melting point of the fibers. A method for manufacturing a wiping cloth, which comprises fusion-bonding, and then performing a 1.1 to 1.5-fold stretching treatment at room temperature to 60 ° C. in a uniaxial or biaxial direction.