JPS63235558A - Steaming adhesive nonwoven 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 nonwoven fabric containing ethylene vinyl alcohol copolymer fibers and a method for producing the same.

(Prior art) Fibers made by melt-spinning ethylene vinyl alcohol copolymer (hereinafter abbreviated as EVOH) have excellent hydrophilic properties.''9 Woven or knitted fabrics or non-woven fabrics made from this fiber are similar to those made from other fibers with the same basis weight. In addition to being able to hold a larger amount of water, it is chemically resistant and biocompatible.

Because it has excellent chemical reactivity, it is expected to have a wide range of uses.

There is an inverse relationship between EVOH's hydrophilicity and low melting point depending on the amount of vinyl alcohol and ethylene. That is, when vinyl alcohol is high and ethylene is low, hydrophilicity increases but the melting point is high, and when vinyl alcohol is low and ethylene is high, hydrophilicity is poor but the melting point is low.

One method of producing nonwoven fabric is to use a low-melting point fiber as one of the constituent fibers and heat-melt it to bond the constituent fibers together. However, when producing nonwoven fabric using this method using EVOHm fibers, ethylene This had the drawback that the amount had to be increased, making it difficult to obtain the desired hydrophilicity.

Therefore, in the technique disclosed in JP-A-57-66200, it is said that when EVOH fibers absorb water, the fibers swell, so that wet heat bonding is possible even at temperatures below the melting point.

However, with this technology, the EVOHm fiber has a saturated water absorption rate (in water at 30°C) due to wet heat adhesion.

It is essential that the film absorbs 70% or more of the water (value after 24-hour immersion), and only under this condition is wet heat bonding possible under normal drying conditions and below the melting point. For this reason, it was necessary to immerse the fibrous web in water for a long time before heat treating it.

Therefore, with the above-mentioned method according to JP-A-57-66200, only non-woven fabric, i.e., paper, can be obtained by the papermaking method, and wet EVOH fibers cannot be made into a web by carding. Therefore, it was not possible to obtain a nonwoven fabric with good properties.

(Problems to be Solved by the Invention) The present invention uses EVOH fibers, and after forming a web by defibrating the fibers with a card without using wet paper making, the fibers are thermally fused to form a bulky and flexible web. Furthermore, the purpose is to obtain a nonwoven fabric with sufficient strength.

(Means for Solving the Problems) The present inventors have focused on the characteristics of EVOH fibers, and found that within a certain range of polyvinyl alcohol and ethylene ratios, the desired hydrophilicity can be obtained as a nonwoven fabric, and at relatively low temperatures. Furthermore, the inventors discovered that wet heat bonding is possible even if water is not supplied into the fibers as long as there is a high concentration of water vapor, leading to the present invention.

That is, the first aspect of the present invention is that the ethylene molar ratio (E
mol%) is 20≦E<55. An ethylene vinyl alcohol copolymer having a degree of saponification of 98% or more is used as the first component, and another thermoplastic polymer is used as the second component.

The composition ratio of the first component and the second component is 20:80 to 80:
This is a moisture-thermal bonded nonwoven fabric made of a fiber web containing 30% or more of composite fibers with a ratio of 20% or more.

The reason why the ethylene molar ratio (E%) of the EVOH fiber is required to be 20 or more is that there is a problem with the spinnability of the EVOH fiber. When E=20, the melting point of F and VOH is 207°C, and the temperature at which gelation begins when retained for 5 minutes or more is 240.
Measured at 2°C. To perform stable melt spinning within this range, a temperature at least 2 (1'C) higher than the melting point is required, i.e. 227°C, so the possible temperature range is 2i
o, 2-227 = 13.2 (°C), and it is desirable to have at least this possible temperature range during melt spinning, and a longer temperature range is required for composite spinning with other thermoplastic polymerizable materials. This is because if it is too narrow, it is difficult to perform stable spinning.

Furthermore, if E is large, the melting point of EVOH will be low, but the hydrophilicity will be poor. Therefore, in order to obtain the wet heat adhesive fiber which is the object of the present invention, E was set to 55.

The reason why the degree of saponification of EVOH is 98% or more is that if it is lower than 98%, the molten resin tends to foam and fiber breakage occurs frequently in the spinning process.

Other thermoplastic resins that make EVOH and composite fibers are polypropylene and polybutylene terephthalate.

Nylon 6 and nylon 66 are conveniently used, and polyethylene terephthalate is also applicable.

E V OH can be spun alone, but the fiber strength is weak and there are many problems such as thread breakage during the spinning process.

In the present invention, a composite fiber with the above-mentioned thermoplastic resin is used, but the composite ratio of EVOH (first component) and other thermoplastic polymer (second component) is set to 20:80 to 8o:20. This is because if the content of one component is less than 20%, the wet heat adhesive strength will be poor, and if it exceeds 80%, the fiber strength will be poor. .

A fibrous web containing 30% or more of such composite fibers can be bonded with wet heat at a temperature below the melting point of the composite fibers. 3
Although a nonwoven fabric can be formed with less than 0%, the strength of the nonwoven fabric is insufficient. The manufacturing method will be explained below.

The second aspect of the present invention is that the ethylene molar ratio (E mol %) is 20≦E<55. An ethylene vinyl alcohol-based polymer having a saponification degree of 98% or more is used as the first component, another thermoplastic polymer is used as the second component, and the composition ratio of the first component and the second component is 20:
80-80: 20 v1 combinations. ? g Synthetic fiber 3
In a method for producing a nonwoven fabric by moist heat bonding a fiber web containing 0% or more, water is applied to the 1a fiber web in an amount of 30% or more of its weight, and then a heating element is brought into contact with both surfaces of the fiber web.

Ta2.17E + 46.5. T<~1.9E
This is a method for producing a heat-and-moisture adhesive nonwoven fabric, which is characterized by heating to a heating temperature (T'C) in the range of +245, 7<2°13E + 59.4, and bonding fibers together with heat and humidity.

The composite fiber having the structure of the first invention swells and gels in the presence of sufficient water vapor even at temperatures below the melting point, and changes depending on the component ratio of other alcohols, but if Ta2.17E +46.5, the water content in the web EVOH composite fibers can be bonded in a short period of time using steam of T 1
3E + 59.4 and T<-1, 9E+245 (
melting point).

The graph in Figure 1 shows the relationship between the ethylene molar ratio (E mol%) of the first component of EVOH fiber and the wet heat adhesion temperature (T°C) of the nonwoven fabric. The temperature is within the range where it does not occur. That is, 20≦
Within the range of Eku55, when 20≦E<46 (2,13
When 46≦E55, the temperature is lower than (-1,9E+245)°C (melting point). The temperature at which EVOH fibers can swell in the presence of moisture is (1,17E+46.5)'C or higher, and the shaded area in the graph is the temperature range at which bonding is possible.

It is difficult to cause EVOH fibers to swell and gel simply by heating and increasing the temperature, so both sides of the fiber web must be in contact with a heating element.

The heating body is a roll, flat plate, conveyor, etc.

The fibrous web is heated by sandwiching it from both sides, and the pressure need only be about ]Og,/c7 or more.Heating both sides of the heating element will cause adhesion to occur uniformly in the thickness direction of the web. It is also possible to heat only one side while the other side simply functions as a support, and which method to use may be selected depending on the intended use of the nonwoven fabric.

Figure 2.3 shows an example of the heating method of the present invention.

Figure 2 shows a method in which a fibrous web (2) is held and heated by heat rolls (1). The fibrous web (2) is previously moistened by spraying (3) and then heated to the above temperature range by the heat rolls (1). The non-woven fabric (4) is bonded and rolled up.

Fig. 3 shows a heating method using a heat cylinder (5). 1
The a-fiber web (2) is moistened by a spray (3) and then preheated by a heat cylinder (5) until the moisture content is 30%.
The EVOH fibers are pressed by a pressure roll (6) on the above-mentioned lever, and at this time, the EVOH fibers swell and gel, forming a nonwoven fabric (4), which is then wound up.

(Operation of the invention) In the method of the present invention, it is not necessary that moisture be absorbed inside the EVOH fibers, but it is sufficient that moisture is attached to the surroundings of the EVOH fibers. A major feature of the present invention is that when the EVOH fibers are held between heating bodies using the method described above, the instantaneously generated water vapor is contained within the fiber web by the heating bodies, and the EVOH fibers are instantly swollen and gelled to be bonded.

EVOH with an ethylene molar ratio of 20 to 55% used in the present invention
Since fibers are extremely hydrophilic, moisture imparted to the fiber web is adsorbed around the fibers, making them suitable for use in the above method.

(Effects of the Invention) Not only can the nonwoven fabric of the present invention be produced by wet heat bonding at a temperature lower than the melting point, but the obtained nonwoven fabric can also be bonded with wet heat, and the bonding partner is polyester, nylon, etc. Woven and non-woven fabrics made of synthetic fibers, cotton, rayon, and other natural fibers can be used for appliqués, interlining, etc. of clothing. 1) Since it can be bonded to paper, wood, and metal with a small amount of moisture using moisture heat, it can be used for construction, automobile interior materials, and insulation materials.

Furthermore, if a nonwoven fabric with good hydrophilicity and chemical resistance can be obtained by appropriately selecting other constituent fibers of the nonwoven fabric, it will be useful as sanitary materials, industrial filters, and battery separators.

In addition, the strength of the nonwoven fabric according to the present invention is approximately 0.5 or more when the tensile strength in the direction perpendicular to the fiber direction is expressed as the breaking length, and it can withstand all of the above uses. .

In addition, the tearing length is calculated by calculating the tensile strength (g) of a sample with a width of 50 mm by weight (
The value (km) divided by g/m) was taken.

(Example) As EVOHml, EVOH with ethylene molar ratio E=29°38 and 47 was used as the first component, polypropylene was used as the second component, and the first component was used as the sheath component.

Composite ratio 50.150 (weight ratio) with the second component as the core component
Sheath-core composite fibers were spun at a spinning temperature of 240°C, and
Stretches with different ethylene molar ratios of 2 denier fineness and 51111 cut length were made by stretching at ~130°C, mechanically crimped through a hydrophilic oil, and drying. there was.

Example-1 E=29. EVO) Made of 100% I fiber, mesh f size 3
A card web of 0 g/+n" was made, fixed on a support paper, sprayed with 30 g/m" water using a sprayer, and then pressed between flat heated rolls with a diameter of 165 mm under a pressure of 10 kg/cWa" for processing. 2 at speed 5m/win
It was passed through and bonded with wet heat. Roll temperature starts from 70℃]O'
The heating humidity range according to the method of the present invention is 80.4 to 121.1. It is ℃. Table 1 shows the heating temperature and fracture length.

Example 2 A nonwoven fabric was made using EVOH fibers with E=38 under the same conditions as in Example 1. The heating temperature range according to the present invention was 91
．． The temperature is 0 to 140.3°C. Table showing each heating temperature and fracture length.
Shown in 1.

Example 3 A nonwoven fabric was made using E-47 EVOH fiber under the same conditions as in Example 1. The heating temperature range according to the present invention was 10
The temperature is 1.5 to 155.7°C. Table 1 shows each heating temperature and fracture length.

As shown in Table 1, in Example 1, the tearing length did not reach 0.5 when the heating temperature was 80° C. or lower, which was inappropriate depending on the use of the nonwoven fabric. Also, when the temperature reaches 130℃, EVO is added to the roll.
The H fibers stick to each other, making it impossible to obtain a satisfactory nonwoven fabric.

Similarly, in Example 2, when the temperature is 90°C or lower, the fracture length is small and unsuitable when the temperature is 100°C or lower, but both can be produced satisfactorily at 130°C.

Example 4 The same fibrous web as in Example 1 was heated using a spot bonding heat roll with a diameter of 165 cm and a heated roll having a diameter of 165 mm.
Pressing force 20kg/using a 65m flat heat roll
A nonwoven fabric was produced in the same manner as in Example 1, except that the distance between the rolls was 0.04 mm. Table 2 shows each heating temperature and fracture length.

Example 5 Using the same fiber web as in Example 2, a nonwoven fabric was made in the same manner as in Example 4. Table 2 shows each heating temperature and fracture length.

Example 6 Using the same fiber web as in Example 3, a nonwoven fabric was made in the same manner as in Example 4. Table 2 shows each heating temperature and fracture length.

Below, margin Examples 4, 5, and 6 are both bonded with heat and humidity at various temperatures, but in Example 6, the moisture and heat adhesion of EVOH fibers decreases, so if the number of bonding points is reduced by the spot bonding hot roll, it will cause cracking in the low temperature range. The cross section becomes smaller.

Example 7 Six types of nonwoven fabrics were made under the same conditions as in Example 2, except that the water content was changed to 1 Og/m2, and the heating temperature was similarly changed in 10°C increments. The tearing length of these nonwoven fabrics was about 40% of that of Example 2, but they were generally durable for use.

Example-8 In Example 1, rayon (2 denier,
A nonwoven fabric was produced under the same conditions as in Example 1 except that a 67% blend of 55m5) was used. Table 3 shows the fracture length for each heating temperature.

Example 9 A nonwoven fabric was made under the same conditions as in Example 1 except that the fiber web was mixed with 67% polyester (2 denier, 51 dragon). Table 3 shows the fracture length for each heating temperature.

Although both Examples 8 and 9 contained only 33% of EVOH fibers, the strength of the nonwoven fabrics at each heating temperature was sufficient to withstand use at all temperatures except at 80°C.

[Brief explanation of the drawing]

Figure 1 is EVOHI! 1 is a graph showing the relationship between the ethylene molar ratio (E%) of &l and the wet heat bonding temperature (T'C) of a nonwoven fabric. Figure 2.3 shows the features of the present invention! ! 3 is a flowchart illustrating an embodiment of the sending method. In the following figures, ], heat roll 2, fiber web 3.
Spray 4 Nonwoven fabric 5. Heat cylinder 6, pressure roll

Claims (2)

[Claims] (1) Ethylene molar ratio (E mol%) is 20≦E<55,
An ethylene vinyl alcohol copolymer with a saponification degree of 98% or more is the first component, another thermoplastic polymer is the second component, and the composition ratio of the first component and the second component is 20:80 to 80:20. A wet heat bonded nonwoven fabric comprising a fiber web containing 30% or more of composite fibers. (2) Ethylene molar ratio (E mol%) is 20≦E<55,
An ethylene vinyl alcohol copolymer with a saponification degree of 98% or more is the first component, another thermoplastic polymer is the second component, and the composition ratio of the first component and the second component is 20:80 to 80:20. In a method for producing a nonwoven fabric by wet heat bonding a fibrous web containing 30% or more of composite fibers, after adding moisture of 30% or more of its weight to the fibrous web, a heating element in contact with both surfaces of the fibrous web ≧1.17+46.5,
A method for producing a moisture-heat bonded nonwoven fabric, which comprises heating to a heating temperature (T° C.) within the range of T<-1.9E+245 and T<2.13E+59.4 to bond fibers with moisture and heat.