JPS6211522A - Preparation of statically charged polyolefinic nonwoven cloth - Google Patents

Abstract

PURPOSE:To afford sufficient statically charging effect to polyolefinic nonwoven cloth treated with textile oil fluid, in which sufficient charging effect has not been obtd. conventionally, by heat-treating nonwoven cloth at >=110 deg.C using a nonionic textile oil fluid having <=10 HLB to afford statical charging effect. CONSTITUTION:Textile oil fluid contg. >=40% nonionic surfactant having <=10 HLB is used as textile oil fluid for spinning polyolefinic staple fiber or for carding or traversing the polyolefinic staple fiber for the prepn. of nonwoven cloth. Suitable surfactants are sorbitan base or polyoxyethylene base compds. The nonwoven cloth is then heat-treated at >=110 deg.C for 10sec-10min. Thereafter, the nonwoven cloth is statically charged by the corona discharge, etc.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to polyolefin staples! The present invention relates to a method for producing a charged nonwoven fabric containing fibers as a main component.

[Prior Art] Charged nonwoven fabrics made of synthetic resin staple fibers are used as air filters for dust collection and the like.

The dust collection function of this charged non-woven fabric includes a normal mechanical filtration function using the fiber layer and a collection function using the electrostatic force generated by electrification. Dust is collected. In this way, charged nonwoven fabrics can widen the particle size range of dust that can be collected, improve dust collection efficiency, and significantly reduce pressure loss, making it possible to maintain dust collection for a long time. Because of this, it is attracting attention as an excellent air filter.

Synthetic fibers used in the production of such charged nonwoven fabrics include polyolefin-based, polyester-based, vinyl chloride-based, vinylidene chloride-based, and polyclar-based staple fibers.

[Problems to be Solved by the Invention] However, nonwoven fabrics made from polyolefin staple fibers are difficult to be electrically charged, and even after the electrical charging treatment, the collection efficiency of ultrafine particles of less than one particle is extremely low.

The inventors of the present invention have conducted extensive research to solve these problems with polyolefin staple fiber nonwoven fabrics, and have discovered that the oil adhering to polyolefin staple SaW has a large effect on electrification. We conducted extensive research to ensure that even polyolefin staple fibers with such oils attached could be sufficiently charged. By selecting the type of oil and applying a thermal history above a certain temperature, we found that We have discovered that the influence of oil can be eliminated, and have completed the present invention.

[Means for Solving the Problems] That is, the present invention uses an oil agent containing 40% (wt%, the same shall apply hereinafter) or more of a nonionic oil agent with an HLB@ of less than 1θ, and heats the oil at 110° C. before charging treatment. The present invention relates to a method for producing a charged polyolefin nonwoven fabric, which is characterized by heat treatment at a temperature above.

[Operations and Examples] Oil agents are used in the spinning process of polyolefin staple fibers, the carding process, fiber entanglement process, etc. when producing nonwoven fabrics using the fibers, and oil agents are used in the spinning of polyolefin fibers, It is indispensable for processing.

Polyolefin fibers or nonwoven fabrics to which such oils are attached are not sufficiently charged even if they are subjected to charging treatment such as corona discharge. However, as an oil agent, the HLB value is 10.
When using a nonionic oil containing 40% or more of less than
In addition, it can be sufficiently charged.

If the amount of anionic oil, nonionic oil with an average HLB value of 10 or more, or nonionic oil with an HLB value of less than 10 is small, the nonwoven fabric cannot be sufficiently charged even if the thermal history is applied. Further, even if a nonionic oil with an HLB value of less than 10 is used, it cannot be similarly charged unless heat history is added.

Examples of the nonionic oil having an HLB value of less than 10 used in the present invention include sorbitan compounds, polyoxyethylene compounds, polyoxysorbitan compounds, and mixtures thereof. H.L.B.
l may have an average HLB value of less than 10, but is preferably 1.8 to 8.0. These nonionic oils may be used alone or in combination with other oils. However, when mixing, the HLB value is 1.
The amount of nonionic oil less than 0 must be 40% or more, preferably 60 to 100%. Other oils that can be mixed include nonionic compounds such as polyethylene glycol compounds and polyoxy higher alcohol compounds, anionic compounds such as higher fatty acid esters, higher alcohol sodium sulfate, and alkyl phosphoric acid compounds, and cationic compounds such as higher fatty acid esters, higher alcohol sodium sulfate, and alkyl phosphoric acid compounds. Examples include lauryl trimethylammonium chloride and lauryl betaine.

The heat treatment in the present invention is at least 110°C, preferably at 13°C.
It is carried out at 0 to 160°C. If the treatment is performed at a temperature below 110° C., the influence of the oil during the charging treatment cannot be excluded. The heat treatment can be performed before, after, both, or simultaneously with the production of the nonwoven fabric. Various heat treatment methods can be adopted depending on the manufacturing method of the nonwoven fabric, the thickness, density, texture, etc. of the intended product. For example, in order to obtain a relatively soft and thick nonwoven fabric with low density, It is possible to obtain a thick non-woven fabric by heat-treating raw cotton and then opening it and heat-adhering the garment without applying pressure, or by spraying adhesive after opening to form a thick mat and then heat-treating it. In order to hang a thin, hard, and high-density nonwoven fabric, in addition to the heat treatment of the raw cotton described above, it is also necessary to press the opened garment between multiple heating rollers, or heat embossing rolls. You can use a method such as partially adhering with hot air and then treating with hot air. The heat treatment time is usually 10 seconds m+ to 10 minutes. It should be noted that the amount of oil adhered hardly changes before and after the heat treatment.

All polyolefin staples used in the present invention
Examples include polyethylene staple fibers, polypropylene staple fibers, polypropylene-polyethylene composite staple fibers, composite staple fibers whose sheath component is polyethylene or polypropylene and whose core component is polyester or polyamide, and flame-retardant treatment, softening treatment, and high crimp treatment. Examples include things that have been done.

Further, in order to obtain a charging effect, it is necessary that at least 40% or more of polyolefin staple fibers be included in all the fibers constituting the nonwoven fabric. If the content of polyolefin staple fibers is less than 40%, a sufficient charging effect cannot be obtained, which is inappropriate.

As the method for forming a non-woven fabric, conventional methods such as fiber bonding method, point bonding method, needle punch method, spray bonding method using an adhesive, etc. can be adopted. Heat treatment can be carried out at the same time as non-woven fabric formation in the case of the fiber adhesion method, or at any time before the charging treatment in the point adhesion method and the needle punch method.

Note that the nonwoven fabric in the present invention includes not only the nonwoven fabric produced by the above method but also a net-like fabric.

The nonwoven fabric that has been subjected to a thermal history is then subjected to a charging treatment. As the charging treatment, a conventionally conventional method using corona discharge is employed. The corona discharge method is a method in which a nonwoven cloth is normally passed between a corona electrode and a ground electrode, and a high voltage is applied between both electrodes to generate a corona discharge, thereby charging the nonwoven cloth.

The charged nonwoven fabric of the present invention can be used as it is or after being subjected to processing such as reinforcement, pleat formation, hot melt resin coating, etc., and then cut into a predetermined shape to be used in air filters, masks, etc.
Used as wiping cloth, etc.

Next, the manufacturing method of the present invention will be explained based on examples.
The present invention is not limited to such embodiments.

Example 1 Polypropylene staple fibers (fiber diameter = 2 denier, fiber length = 511) to which the oil shown in Table 1 was attached were subjected to a needle punching method (needle density = 150 pieces/d, needle depth: 10
．． ) made into a non-woven fabric (fabric weight: 2SO9/a11
Thickness: 2.0a) The obtained punch felt nonwoven fabric was heat-treated at a temperature of 140° C. for 2 minutes using a hot air circulation dryer.

An applied voltage of 1 was applied to the obtained heat-treated nonwoven fabric at room temperature (25°C).
After being charged by corona discharge treatment at 4KV for 5 seconds,
It was cut into pieces of 50 mw x 250 m, attached to a cylindrical duct, air containing dust passed through it at a wind speed of 10 m/sec, and the collection efficiency of dust particles of 0.3 ρ was measured.

The results are shown in Table 1. The ventilation resistance was 0.2°820.

In Table 1, the HLB values of sorbitan trioleate and polyoxyethylene nonylphenyl ether were 1.8 and 15.5, respectively.

[Blank below] Example 2 A nonwoven fabric was prepared in the same manner as in Example 1 except that the mixed oil agent shown in Table 2 was used as the oil agent in Example 1, and after heat treatment, it was subjected to charging treatment. The collection efficiency was measured in the same manner as above. The results are shown in Table 1.

[Leaving space] Example 3 A polypropylene-polyethylene composite staple fiber (l fiber diameter: 3 denier, fiber length: 64 m+) to which the oil shown in Table 3 was attached was formed into a sheet by a needle punching method, and then formed into a sheet by a fiber adhesion method. A nonwoven fabric was produced. The conditions for fiber adhesion were as follows.

Heating temperature: Shown in Table 3.

Heating 81J: The resulting heat-treated nonwoven fabric was heated for 3 minutes at 26°C with an applied voltage of 14
Corona discharge treatment at ~14.5 KV for 10 seconds, Example 1
The collection efficiency was measured in the same manner as above. The results are shown in Table 3.

The basis weight, thickness, and ventilation resistance of the nonwoven fabrics in experiment numbers 9 to 11 were 2559/ffl, 2.0°, and 2.6 JIII H2O, respectively, and those in experiment numbers 12 to 14
The basis weight, thickness and air resistance of the non-woven fabric are 250 each.
9/rd, 2.6as+ and 2.6118
20, and the basis weight of the nonwoven fabrics of experiment numbers 15 to 17,
Thickness and airflow resistance are respectively 2209/m, 2.
0 Mm and 1.9.820.

[Margin below] Table 3 Example 4 Bolibu O pyrene fiber (Ia fiber diameter: 2 denier, fiber length:
After roughly opening 64 mg+) of raw cotton using a garnet machine to form a wrap, it was heat-treated in a drying oven at 120° C. for about 8 minutes.

After the heat treatment, the wrap is opened with a card machine to form a garment, which is then passed between heat rolls at 170°C with an embossed pattern on one side for thermal bonding, resulting in a relatively high-density nonwoven fabric.Weight: 2009/Td1 Thickness: 0.8M
) was obtained.

The obtained nonwoven fabric was subjected to charging treatment in the same manner as in Example 1,
° Collection efficiency was measured. The results are shown in Table 4. The ventilation resistance was 6.9IIIH20.

In addition, the collection efficiency was measured for a nonwoven fabric that was produced in the same manner except that no heat treatment was performed, and that was subjected to a charging treatment.

The results are shown in Table 4.

Margin below E] Table 4 Example 5 Polypropylene-polyethylene composite fiber m<m Set diameter: 3 denier, Fiber length: 64. ) and polyester fiber (1
1M diameter: 5 denier, fiber length: 64. ) in the proportions shown in Table 5 was heat treated for 2 minutes in a hot air circulation dryer at 145°C and at the same time bonded at a distance of m to form a relatively thick non-woven fabric (fabric weight: 2509
/ rIt, thickness = 12 ml +) was obtained.

The obtained nonwoven fabric was subjected to charging treatment in the same manner as in Example 1,
The collection efficiency was measured. The results are shown in Table 5. The ventilation resistance was 0.37Ill)120.

Table 5 [Effects of the Invention] According to the present invention, even in oil-adhered polyolefin nonwoven fabrics for which a sufficient charging effect could not be obtained in the past, by using a specific oil and applying a thermal H history of a specific temperature or higher, A sufficient charging effect can be obtained, and the range of materials that can be used for charged nonwoven fabrics can be expanded to include polyolefin fibers that are inexpensive and easy to make into nonwoven fabrics.

Claims (1)

[Claims] 1. When producing a nonwoven fabric containing at least 40% by weight of polyolefin staple fibers treated with an oil agent in the total constituent fibers, and then performing a charging treatment to produce a charged nonwoven fabric,
As an oil agent, use a nonionic oil agent with an HLB value of less than 10.
110% by weight or more before the charging treatment.
A method for producing a charged polyolefin nonwoven fabric characterized by heat treatment at a temperature of ℃ or higher. 2. The manufacturing method according to claim 1, wherein the heat treatment is performed simultaneously with the production of the nonwoven fabric. 3. The manufacturing method according to claim 1, wherein the heat treatment is performed after producing the nonwoven fabric. 4. The manufacturing method according to claim 1, wherein heat treatment is applied to polyolefin staple fibers. 5. The manufacturing method according to claim 1, wherein the oil agent is a nonionic oil agent having an HLB value of less than 10. 6. The manufacturing method according to claim 1, wherein the oil is a nonionic mixed oil and has an average HLB value of less than 10. 7. The manufacturing method according to claim 1, wherein the oil is a mixed oil of a nonionic oil and an anionic oil having an HLB value of less than 10. 8. The manufacturing method according to claim 1, wherein the heat treatment temperature is 130°C or higher. 9. The manufacturing method according to claim 1, wherein the heat treatment time is 10 seconds or more.