KR20040095378A - A high strength membranous material for industrial use - Google Patents

Abstract

PURPOSE: Provided is a membrane material, which has excellent gas barrier property and interlayer adhesion, and high strength at a low weight, and thus is useful for industrial materials, particularly for stratosphere airship materials. CONSTITUTION: The high-strength membrane material for industrial use comprises a base web layer(1) formed of polyparaphenylene benzobisoxazole fiber or polyvinylalcohol fiber having a strength of 10 g/denier or more, coating layers formed of thermoplastic polyurethane resin and disposed on both surfaces of the base web layer(1), and a polyvinylidene chloride film layer(5) laminated on one surface of the coating layers(2,3) via an adhesive layer(2). The membrane material has a helium leakage ratio less than 2 l/m¬2.24h.atm.

Description

High strength membranous material for industrial use}

The present invention relates to an industrial high strength membrane material used for the airbag material of the stratospheric airship. More specifically, the present invention relates to an industrial high strength membrane material which is excellent in gas barrier property and adhesion between membranes, has a high strength as a light weight, and is useful as a bladder material for a high altitude airship.

High-altitude airships, particularly those used in the stratosphere at altitudes above 20 km (hereinafter referred to as the "stratosphere airship"), are buoyed by buoyancy at an altitude of about 1/18 of the air's density. Therefore, assuming that the existing airship is to be lifted into the stratosphere, its weight should be reduced to 1/18, or the volume of the body should be increased by 18 times while maintaining the same weight. In this case, the length increases by about 2.6 times.

In general, both weight reduction and volume increase are limited, so use both methods in parallel. That is, the airship is designed using a lighter structure and design technique while increasing the length of the main body.

The largest proportion of stratospheric airship weight is air sacs. If the air sacs are made of polyester synthetic fiber, which is widely used in airships, it is necessary to develop a lighter and stronger material because the airships are heavy and weak. Stratospheric airship missions are known to require bladder materials that are more than 100kgf / cm in strength and less than 200g / m2 in weight.

The air bag that is mainly used is a synthetic resin series. However, a single material that has high strength, prevents helium leaks, and minimizes environmental effects such as ultraviolet rays has not been developed yet. Instead, it is widely used to bond materials that can handle each function. The materials constituting the respective membranes are classified into load membranes, gas barrier membranes, and protective membranes according to their functions.

Conventional load film (bubble) is composed of a fabric woven synthetic fibers. Commonly used materials include polyester or polyamide (trade name: Nylon) and aramid (trade name: Kevlar). Of these materials, polyester fibers are the most widely used for airships.

Polyester fibers show higher strength and lower water absorption than other synthetic fibers. It also has a good preservation characteristic. Polyamide fibers have many similarities with polyester in their properties. However, the elongation to load easily occurs.

Aramid fibers have a higher strength than polyester and less deformation due to load. However, due to its large rigidity, it is not flexible and has a weak characteristic of fatigue load. As a result, aramid fibers have a problem of being used as a material of curved airships, and have a disadvantage of easily decreasing chemical strength.

Polyethylene-based fibers have high tensile strength but are susceptible to creep fracture because of their high modulus. In addition, polyethylene fibers have a poor adhesive property, which makes it difficult to bond the protective film and the gas barrier film.

On the other hand, the protective film constituting the airship membrane material serves to protect the air sacs from ultraviolet rays and ozone, and the gas barrier film prevents the helium in the airship from escaping to the outside so that the airship can stay at a high altitude for a long time. .

It is more preferable to reduce the weight of the material because the protective film has a high level of gas blocking function and does not use a separate gas blocking film. Neoprene or polyurethane have been mainly used as a protective film.

The conventional protective film materials are inexpensive and excellent in preventing helium leak, but have a disadvantage in that UV protection is poor and easily torn. In addition, when exposed to moisture and ultraviolet light, it is decomposed into hydrochloric acid, which is not suitable for long-term use and is weak to chemicals, making it difficult to adhere to other films or fibers, and easily causing separation between layers.

The present invention is excellent in adhesion between the gas barrier properties and the membrane material, and has a high strength as a light weight to provide a membrane material useful as an industrial material, especially for the stratospheric airship material.

1 is a cross-sectional view of the membrane material of the present invention

※ Explanation of Codes of Major Parts

DESCRIPTION OF SYMBOLS 1 Bubble 2 and 3 Coating layer 4 Adhesive layer 5 Film layer

Industrial high strength membrane material of the present invention for achieving the above object is a bubble (1) consisting of polyparaphenylene benzobisoxazole fiber or polyvinyl alcohol fiber having a strength of 10g / denier or more, and the bubble (1) A coating layer (2,3) of thermoplastic polyurethane resin formed on both sides of the polyvinylidene fluoride film layer (5) laminated by an adhesive layer (4) on one of the coating layers (2,3) It is characterized in that the helium leakage is less than 2 l / ㎡ · 24 hours · atm.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

The present invention is a film laminated by the adhesive layer 4 on any one of the foam (1), the coating layer (2, 3) formed on both sides of the foam (1), the coating layer made of synthetic fibers as shown in FIG. It consists of layer (5).

The bubble (1) is made of polyparaphenylene benzobisoxazloe (poly P-phenylene benzobisoxazloe) fiber or polyvinyl alcohol fiber having a high strength and rigidity, specifically, 10g / denier or more strength, and high strength Has

The polyparaphenylene benzobisoxalol fiber has a very excellent structural performance except for properties that are weak to ultraviolet rays.

In the present invention, since the film layer 5, which is a protective film for protecting against ultraviolet rays, is laminated on one surface of the membrane material, the polyparaphenylene benzobisoxazole fiber may compensate for the weakness of ultraviolet rays.

In addition, the coating layers 2 and 3 formed on both surfaces of the bubble 1 are made of thermoplastic polyurethane resin. The coating layers serve to improve the adhesion strength between the membrane materials when manufacturing the airship gas.

In general, an airship is manufactured by cutting and bonding a membrane material having a width of about 1 m. At this time, the adhesive site is inferior in strength to the bladder membrane, and tends to increase helium leakage.

In the present invention, by heating the thermoplastic polyurethane resins coated on both sides of the bubble (1), the adhesive strength between the membrane materials may be increased, and helium leakage may be minimized.

Polyurethane resins have the advantage of being inexpensive and readily available, while being vulnerable to ultraviolet radiation. However, in the present invention, since the film layer 5, which is a protective film, is laminated on the outside of the film material, the disadvantage of being vulnerable to ultraviolet rays is compensated for.

Polycarbonate, silicon, or the like may be used as the coating layer material for bonding the film materials to each other. However, polycarbonate is more expensive than polyurethane resin, and silicone has a weak friction.

In order to promote heat absorption or radiation, a metal material such as titanium oxide may be added to the coating layers 2 and 3.

When the edge portions of the membrane material are bonded to each other by overlapping, the bonding strength increases as the length of the overlapping portion (adhesive portion) increases. In order to secure more than 80% of the strength of the bladder membrane, the junction length should be 6 ~ 8cm. Since the width of the membrane material is about 1m, weight increase of about 15 ~ 20% occurs when the aircraft is manufactured.

Meanwhile, the film layer 5 laminated on one side of the coating layers 2 and 3 by the adhesive layer 4 is composed of a polyvinylidene fluoride film, and the main component of the adhesive layer 4 is a urethane-based adhesive. Or polycarbonate-based adhesives.

The membrane material of the present invention described above is excellent in interlayer adhesion and has a helium leakage of less than 2 l / m 2 · 24 hours atm. In addition, the membrane material of the present invention is made of high strength fibers, the strength is 100kgf / cm or more, the weight is 200g / ㎡ or less.

Thus, the membrane material of the present invention is very useful as an airship bladder material used at high altitude because it is excellent in gas barrier properties, lightweight and high strength.

In the present invention, the tensile strength and the helium leak of the membrane material were evaluated by the following method.

Tensile strength (kg / cm)

It was evaluated by the STD 191 A method of FED measurement.

Helium leak (ℓ / ㎡, 24 hours, atm)

It was evaluated by the ASTM D 1434 method.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. However, the present invention is not limited only to the following examples.

Example 1

250 denier polyvinyl alcohol fibers with 15g / d tensile strength are used as warp and weft yarns to weave plain weave fabrics with 70 warp and weft densities of 70 yarns / inch. A coating fabric is prepared by coating a thermoplastic polyurethane resin to which titanium oxide is added to both surfaces of the woven fabric. Subsequently, a polyvinylidene fluoride film is laminated using a urethane adhesive on one side of the coating fabric to prepare a membrane material. The results of evaluating various physical properties of the prepared membrane material are shown in Table 1.

Example 2

Weaving a plain weave fabric with both 55 densities and weft densities using 250 denier polyparaphenylene benzobisoxazole fibers with a tensile strength of 15 g / d as warp and weft yarns. The coating fabric is prepared by coating a thermoplastic polyurethane resin on both sides of the woven fabric. Subsequently, a polyvinylidene fluoride film is laminated using a polycarbonate adhesive on one side of the coating fabric to prepare a membrane material. The results of evaluating various physical properties of the prepared membrane material are shown in Table 1.

Example 3

Using 500 denier polyparaphenylene benzobisoxazole fibers with 20g / d tensile strength as warp and weft yarns, weaving plain weave fabrics with 35 warp and weft densities of 35 yarns / inch. A coating fabric is prepared by coating a thermoplastic polyurethane resin to which titanium oxide is added to both surfaces of the woven fabric. Subsequently, a polyvinylidene fluoride film is laminated using a polycarbonate adhesive on one side of the coating fabric to prepare a membrane material. The results of evaluating various physical properties of the prepared membrane material are shown in Table 1.

Comparative Example 1

Using 1000 denier polyester fibers as warp and weft yarns, weaving plain weave fabrics with 22 warps / inch weft density. The coating fabric is prepared by coating a thermoplastic polyurethane resin on both sides of the woven fabric. Subsequently, a membrane film is prepared by laminating a polyester film using a urethane adhesive on one side of the coating fabric. The results of evaluating various physical properties of the prepared membrane material are shown in Table 1.

Comparative Example 2

Using 420 denier polyamide 6 fibers as warp and weft yarns, weaving plain weave fabrics with both 40 warps and 40 weft warp densities. A coating fabric is prepared by coating a thermoplastic polyurethane resin to which titanium oxide is added to both surfaces of the woven fabric. Subsequently, a membrane film is prepared by laminating a polyester film using a urethane adhesive on one side of the coating fabric. The results of evaluating various physical properties of the prepared membrane material are shown in Table 1.

Property evaluation result division Tensile strength (kg / cm) Weight (g / ㎡) Helium leak (ℓ / ㎡, 24 hours, atm) Example 1 108 187 1.8 Example 2 157 192 1.1 Example 3 171 195 1.3 Comparative Example 1 83 256 3.8 Comparative Example 2 78 238 4.3

The present invention is excellent in gas barrier properties and adhesion between membrane materials, and is light and high strength. As a result, the present invention is useful as a material for airships used for industrial use, especially at high altitudes.

Claims (4)

Bubbles 1 composed of polyparaphenylene benzobisoxazole fibers or polyvinyl alcohol fibers having a strength of 10 g / denier or more, and a coating layer of thermoplastic polyurethane resin formed on both sides of the bubbles 1, 2, 3 ) And a polyvinylidene fluoride film layer 5 laminated on one side of the coating layers 2 and 3 by an adhesive layer 4 so that the leakage of helium is 2 L / m 2 · 24 hours. Industrial high strength membrane material, characterized in that less than atm. The industrial high strength membrane material according to claim 1, wherein the strength is 100 kgf / cm or more and the weight is 200 g / m 2 or less. The industrial high strength membrane material according to claim 1, wherein the main component of the adhesive layer (4) is a urethane adhesive or a polycarbonate adhesive. 2. An industrial high strength membrane material according to claim 1, wherein a metal material is contained in the coating layers (2, 3) of the thermoplastic polyurethane resin.