JPH0586569A - Polyolefin nonwoven sheet - Google Patents

Abstract

PURPOSE:To obtain the subject product, having a high level of antistatic properties and water repellency and capable of exhibiting excellent performance in aspects of safety and practicality when used as protective or working clothes, etc., in atomic power plants, etc., by specifying the water repellency, half-life and surface resistivity value. CONSTITUTION:The objective product having >=80 water repellency, <=1X10<9>OMEGA surface resistivity value and <=2sec half-life of electrification voltage after undergoing electrification by corona discharge. The above-mentioned product is preferably produced by a flash spinning method for dissolving a polyolefinic polymer in a carbon halide, etc., applying a rapid pressure loss and then discharging the resultant solution through a spinning nozzle. Methoxyalkyl phosphates, etc., are preferably used as an antistatic agent for imparting antistatic properties to the resultant polyolefin nonwoven sheet. The surface of the nonwoven sheet is preferably subjected to the corona discharge treatment for facilitating the application of the antistatic agent.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet having a highly balanced water repellency and antistatic property. More specifically, protective clothing,
The present invention relates to a polyolefin non-woven sheet having excellent water repellency and antistatic property, which can be preferably used as a sheet for windbreakers, rain clothes, packaging materials, envelopes, sleeping bags and the like.

[0002]

2. Description of the Related Art Various sheets have been known as polyolefin non-woven sheets used for the above-mentioned applications.
For example, a non-woven sheet obtained by drawing a fiber spun based on a usual melt spinning method at a high speed with a high-speed air flow, a non-woven sheet formed by a melt blow method, or a so-called flash spinning method to make a polyolefin into a fibril three-dimensional reticulated fiber Nonwoven sheets are known. Nonwoven sheets produced by the flash-spinning method are characterized in that the constituent fibers have extremely fine and complicated cross-sectional shapes, and are utilized in various applications by utilizing such characteristics.

When used in the above applications, it is desired that the nonwoven sheet have a highly balanced water repellency and antistatic property. To meet this demand, Japanese Patent Publication No.
The 51068 discloses the chemical formula _{M n R 3-n PO 4} (n is 1 or 2) The compound, the use of the fiber treatment agent n is the compound of compound and n is 2 in 1 has been mixed It is disclosed that antistatic property can be imparted without impairing water repellency.

Further, JP-A-3-146771 discloses a compound (1) represented by the chemical formula RM ₂ PO ₄ (however, for the purpose of improving antistatic property and water repellency).
Here, M is Li, Na, K, H, or an ammonium ion, and R is an alkyl group having 6 or 7 carbon atoms.)
And a compound (2) represented by the chemical formula R ₂ MPO,
Containing 0.05% by weight or more of a fiber treating agent in which the molar ratio of the compound of (1) is twice or more that of the compound of (2), and 0.05% by weight or more of a water repellent composed of a fluorocarbon compound. A polyolefin non-woven sheet having excellent water repellency and antistatic property is disclosed.

However, more highly balanced antistatic property and water repellency are required depending on the application. For example, there are protective clothes and work clothes for nuclear power plants and workplaces where there is a risk of explosion and ignition due to electrification, and it is required that water does not completely penetrate into the clothes and that no electrification occurs. ing. In other words, in terms of water repellency, water does not pass through the non-woven sheet and does not cause wetting in the sheet, and the water repellency is 80 or more. And the surface resistance value is 1 × 10 ⁹
Those that meet the following levels are required. Although the polyolefin non-woven fabric originally has water repellency in the performance of conventional antistatic water repellent treatment, the water repellency decreases when an antistatic agent is added for the antistatic treatment. Depending on the type of antistatic agent and the amount applied, the surface resistance value becomes 1 × 10 ¹⁰ Ω or higher when the water repellency is increased to a level of 80, or the water repellency decreases when the antistatic property is increased. Therefore, no known publicly known antistatic agent for polyolefin nonwoven fabrics has a water repellency of 80 or more and a surface resistance of 1 × 10 ⁹ or less. For example, a fiber treatment agent composed of a compound having the constitution disclosed in Japanese Patent Publication No. 55-51068 can impart water repellency and antistatic property to a non-woven sheet together.
In order to improve the antistatic property, it is necessary to increase the amount of the fiber treatment agent attached, and it is extremely difficult to set the water repellency to 80 or more. In addition, JP-A-3-14677
Even when the fiber treatment agent having the constitution disclosed in Japanese Patent Publication No. 1 is applied, the water repellency can be set to the level of 80, but the performance satisfying the above surface resistance value is not obtained. I can't show you. In other words, it is impossible to achieve the above-mentioned level in terms of antistatic property and water repellency as long as the conventionally known fiber treating agent is used.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a non-woven sheet in which water repellency and antistatic property are highly balanced.

[0007]

The present invention does not use a compound having hydrophilicity which is a characteristic of conventional antistatic agents, but uses a compound having a hydrophilic group but rather hydrophobicity to improve water repellency. The polyolefin non-woven sheet is completed by subjecting it to antistatic processing. The polyolefin non-woven sheet according to the present invention has a water repellency of 80 or more, a half-life of 2 seconds or less, and a surface resistance value of 1 ×. It has physical properties of 10 ⁹ Ω or less.

The polyolefin non-woven sheet of the present invention has a sheet surface composed of extremely fine fibers, and it is necessary that the water repellent surface and the fiber treatment agent are applied to almost the entire surface without unevenness because the sheet has a smooth surface. In addition, a polyolefin non-woven sheet obtained by a flash spinning method or a melt blow method, which will be described in detail below, is preferable from the viewpoint of moisture permeability and air permeability when used for work clothes and the like. The sheet before the antistatic and water repellent treatment of the present invention can be manufactured by a known method.
For example, Japanese Unexamined Patent Publication No. 61-160469 discloses an example of a method for producing a polypropylene continuous filament non-woven fabric, and Japanese Unexamined Patent Publication No. 63-6107 discloses an example of a method for producing a non-woven fabric of polypropylene ultrafine fibers by a melt blow method. .. Further, as an example of the flash spinning method, for example, Japanese Patent Publication No. 62-172073 discloses an example of high density polyethylene, and Japanese Patent Publication No. 62-192598 discloses an example of polypropylene.

As an example of the flash spinning, a polyolefin-based polymer is dissolved under high temperature and high pressure with a halogenated carbon such as trichlorofluoromethane or trichlorotrifluoroethane, a hydrocarbon such as methylene chloride or a mixed solution thereof, and then rapidly melted. When a sufficient pressure loss is applied, the solution is given a structure as if it were phase-separated extremely finely. This liquid material is discharged from a spinning nozzle to orient the polymer and form a three-dimensional reticulated fiber. After this is shaken off on a conveyor belt to form a web, a roll (smooth roll, embossing roll, etc.) kept at room temperature or at an appropriate temperature (below the melting point of polyolefin) or a felt calender is used to press the part or the entire surface to form a sheet. To This non-woven sheet consists of fibers with a very fine and complex cross-sectional structure.

In addition, when it is used for the above-mentioned work clothes, protective clothes, etc., it is necessary to have flexibility in terms of wearing feeling. Since the above-mentioned polyolefin non-woven sheet is paper-like as it is, it can be softened by subjecting it to softening. As a measure of flexibility, the pure bending value of 0.
The range of 01 to 0.3 gfcm ² / cm is preferable. The above-mentioned non-woven sheet has a basis weight of 30 to 200 g / m ² , preferably 40 to 100 g / m ² . If the basis weight is less than 30 g / m ² , sufficient water repellency cannot be obtained. Also, 200 g / m
^{When it is 2} or more, the flexibility is impaired, and wrinkles or breakage easily occur during production, which is not preferable in terms of quality.

The polyolefin nonwoven sheet of the present invention is subjected to antistatic processing in order to impart antistatic property to the above-mentioned nonwoven sheet. As the antistatic agent, cationic, nonionic, or anionic antistatic agents can be used, but those exhibiting hydrophilicity tend to be inconvenient in terms of water repellency and satisfy the physical properties of the present invention. Cannot be made. In the present invention, methoxyalkyl phosphate salts, alkyl alkylene oxide phosphate salts, oxacycloalkyl methyl phosphate salts and the like are preferable. Among these compounds, those having an appropriate carbon number and molecular structure are It has excellent water repellency and has the property that water repellency hardly changes even if the amount of adhesion is increased. It is necessary to give an appropriate amount of these antistatic agents depending on the type of antistatic agent, the molecular structure of the non-woven sheet, the surface state, and the like. For example, when the amount of methoxybutyl phosphate potassium deposited on the polyethylene non-woven sheet prepared by the above-mentioned flash spinning method is set to 0.5 to 10% with respect to the dry sample weight, the water repellency is 80 or more, and the water repellency is reduced to half It is possible to manufacture a non-woven sheet having a period of 2 seconds or less and a surface resistance value of 1 × 10 ⁹ Ω or less.

As an application method of the antistatic agent, a usual application method can be applied. Examples thereof include a dip-nip method, a coating method, a gravure roll method, a kiss roll method, and a spray method. The applied antistatic agent is dried by heating with hot air such as a tenter or contact heating with a heating drum. Further, by applying corona discharge treatment in advance before applying the fiber treatment agent, the wettability of the surface of the nonwoven sheet is improved and the application of the antistatic agent can be facilitated. However,
Depending on the molecular structure and surface condition of the non-woven sheet, it is necessary to perform corona treatment that does not cause a significant decrease in water repellency.
If you do not corona treatment, in an aqueous solution containing antistatic agent,
By adding alcohol (ethanol, isopropanol, etc.) or acetone in an amount of about 1 to 30% by weight, it is possible to easily apply the antistatic agent, and the water repellency of the non-woven sheet is not reduced. This is an effective method.

[0013]

The present invention will be described in detail with reference to the following examples. Prior to the description of the examples, methods for measuring various physical properties of the nonwoven sheet of the present invention will be described. -Antistatic property (half-life measuring method) The antistatic property was evaluated by a method of measuring the time (half-life) until the electrification voltage is reduced to half after charging the test piece by corona discharge. (JIS-L-1094) This measuring method is suitable for evaluating the static electricity attenuation characteristics of a woven or knitted fabric. -Antistatic property (surface resistance measurement method) A voltage of 500 V is applied to the protective electrode from the main electrode on the surface of the sample, and the surface electrical resistivity is determined from the value of the current flowing through the protective electrode. (JIS-L-1094 Surface Leakage Resistance Measurement Main Electrode Diameter: 50 mm Protective Electrode Inner Diameter: 70 mm) Water Repellency Test (Spray Test) The water repellency test method for textile products (JIS-L-1092) was used. However, since the non-woven sheet is not substantially washed, it is evaluated without washing.

The application of the fiber treatment agent and the water repellent and the preparation of the measurement sample in each of the examples described below were carried out by the following methods. The nonwoven sheet was dipped in an aqueous solution containing an antistatic agent and nipped between rubber rolls having a hardness of 75 ± 5 to remove excess solution from the surface of the nonwoven sheet. The wet nonwoven sheet is air dried and then pre-designated at 20 ± 2 ° C. 40 ±.
It adjusted for 24 hours or more in a constant temperature room of 2% RH.

[0015]

Examples 1 to 6 and Comparative Examples 1 to 5 Polyethylene polymer and solvent were discharged from a nozzle to a low temperature and low pressure region under high temperature and high pressure conditions, and the solvent was flushed to form fibrillated reticulated fibers, which were then deposited in a wire mesh form. And thermocompression-bonded with a 130 ° C calender roll, and basis weight 62g / m ² thickness 0.2m
m polyethylene nonwoven sheet was obtained. The sheet was subjected to corona discharge treatment and treated with various antistatic agents as shown in Table 1 in various concentrations of aqueous solutions. All of these antistatic agents are a mixture of mono and bis (about 1: 1) shown in the table.
Molar amount). Since the surface of the non-woven sheet was previously subjected to corona discharge treatment, the non-woven sheet could be sufficiently applied with the treatment solution. Table 1 shows the results of the amount of the antistatic agent attached, the antistatic property, and the water repellency.

[0016]

[Table 1]

As shown in Table 1, it has been found that the nonwoven sheet of the present invention has a highly balanced antistatic property and water repellency.

[0018]

The non-woven polyolefin sheet of the present invention has a high level of anti-static property and water-repellent property, which has been considered to be contradictory performances. Therefore, it is a non-woven polyolefin sheet having excellent performance in terms of safety and practicality when it is used for protective clothes and work clothes for nuclear power plants.

Claims (1)

[Claims] 1. A water repellency of 80 or more and a half-life of 2
A polyolefin non-woven sheet having a surface resistance value of 1 × 10 ⁹ Ω or less for seconds or less.