Cushioning member

BACKGROUND OF THE INVENTION .

(1) Field of the Invention

-The present invention relates to a cushioning member used for air-planes, ships, vehicles, furniture, and interior articles.

(2) Description of the Related Art

Fabrics, paddings and laminates formed by using inorganic compounds or organic compounds are used as materials having a heat-insulating or flame-proofing property. For example, there are known a wall covering material comprising an elastic air-permeable foam layer containing a flame-proofing additive and a fiber-containing covering layer, in which hollow granules of an inorganic material having independent cells are incorporated in continuous cells in the foam layer (see Japanese Unexamined Patent Publication No. 55-158384), and a furniture covering fabric having an improved flame-proofing property, which is a laminate of a fabric and a foam, wherein the foam layer comprises 100 parts by weight of a neoprene, about 5 to about 15 parts by weight of a carbonization promoter and about 10 to about 180 parts of alumina hydrate or the same amount, based on hydration water, of a hydrate of other inorganic compound, the inorganic compound hydrate retains the majority of the hydration water at temperatures for drying and curing the foam but loses hydration water at temperatures below about 500°C, the neoprene is a homopolymer of chloroprene or a copolymer of chloroprene with other organic monomer, and when the neoprene is a copolymer of chloroprene with acrylonitrile or an a,β-saturated carboxylic acid, the carbonization promoter need not be present (see Japanese Unexamined Patent Publication No. 55-40890).

Recently, a light-weight characteristic, an easy moldability, and an enhanced heat insulating property are required for a cushioning member comprising a heat insulating material such as mentioned above. For example, in connection with airplanes for which especially high heat insulating, flame-proofing, and light-weight characteristics are required, the FAA (Federal Aviation Administration) fireproof regulations for seat cushions of airplanes have been effective since November 26, 1984, and it is stipulated that new regulations that cannot be satisfied by conventional products should be satisfied within three years from the above date.

SUMMARY OF THE INVENTION

Under this background, it is an object of the present invention to provide a cushioning member having a light weight and an easy moldability and also having heat insulating and flame-proofing characteristics capable of satisfying the FAA fireproof regulations.

In accordance with the present invention, there is provided a cushioning member comprising a cushioning layer, a heat insulating layer and a dress covering, the heat insulating layer being a laminate comprising (A) a flame-proofing layer and (B) a reinforcing layer, wherein the main fibers of the flame-proofing layer (A) has a melting point not lower than 300°C, a specific gravity not higher than. 1.6 g/cm^-3, and a limiting oxygen index (LOI) of at least 33, and the main fibers of the reinforcing layer (B) have a limiting oxygen index (LOI) smaller than 33 but not smaller than 25, a specific gravity not higher than 1.6 g/cm³, a tensile strength of at least 3.2 g/d, and a toxicity test value of at least 10.

The toxicity test value used herein is the time - (minutes) required for a mouse to die when the smoke generated by burning the fiber at 700°C at an air feed rate of 11.4 1/min at an oxygen concentration of 21% by volume in the fed air is introduced into a box having a volume of 125 1 in which the mouse is confined.

BRIEF DESCRIPTION OF THE DRAWINGS

• Figure 1 is a sectional side view illustrating a heat insulating layer of the cushioning member of the present invention;
• Fig. 2 is a perspective view illustrating an apparatus for testing the abrasion property;
• Fig. 3 is a sectional side view illustrating an apparatus for determining the toxicity test value;
• Figs. 4 through 6 are front, side, and plane views of a stand for supporting a test sample for the combustion test; and
• Figs. 7 and 8 are side and plane views illustrating the setting of a test sample.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The cushioning layer of the cushioning member of the present invention may be made of a known cushioning material. For example, a polyurethane foam, a polystyrene foam, and foamed polyvinyl resins may be used.

The flame-proofing layer and reinforcing layer constituting the heat insulating layer of the cushioning member of the present invention are woven fabrics, non-woven fabrics, scrims, or networks composed of specific fibers or laminates thereof. The heat insulating layer of the cushioning member of the present invention is a. laminate comprising (A) a flame-proofing layer and (B) a reinforcing layer.

The fiber constituting the fire-proofing layer (A) is a fiber having a melting point not lower than 300°C, a specific gravity not higher than 1.6 g/cm³, and a limiting oxygen index (LOI) of at least 33. In connection with the melting point there is included a fiber which is thermally decomposed and carbonized without substantial melting when exposed to a temperature not lower than 300°C. A fiber having a specific gravity not higher than 1.46 g/cm³ and an LOI value of at least 40 is preferred. As the fiber having the above-mentioned properties, there can be mentioned, for example, a polybenzimidazole fiber (such as PBI supplied by Celanese Corp.), a flame-proofing fiber obtained by preoxidizing a polyacrylonitrile fiber to effect surface carbonization (such as Pyromex supplied by Toho Rayon K.K.), and a novoloid fiber (such as Kynof supplied by Nippon Kynol K.K.).

It is preferable that the flame-proofing layer (A) may be composed of two layers, i.e., a layer (A,) having flame-proofing and reinforcing functions and a layer (A₂) having a flame-proofing function. The fiber constituting the layer (A,) is a fiber having a melting point not lower than 300°C, a specific gravity not higher than 1.6 g/cm³, a limiting oxygen index (LOI) of at least 33 and a tensile strength of at least 2.5 g/d. Such a fiber includes, for example, a polybenzimidazole fiber. The fiber constituting the layer (A2) is a fiber having a melting point not lower than 300°C, a specific gravity not higher than 1.6 g/cm³ and a limiting oxygen index (LOI) of at least 33. Such a fiber includes, for example, pyromex (registered trademark, surface-carbonized polyacrylonitrile fiber supplied by Toho Rayon K.K.), Kynol - (registered trademark, polyphenol fiber supplied by Nippon Kynol K.K.) and a polybenzimidazole fiber.

When the flame-proofing layer (A) is composed of the two layers (A,) and (A₂), and these layers (A,) and (A2) are superimposed so that the layer (A₂) is sandwiched between the layer (A,) and the reinforcing layer (B), the resulting cushioning member exhibits enhanced durability, light weight and flame proofness.

The fiber constituting the reinforcing layer (B) is a fiber having a limiting oxygen index (LOI) smaller than 33 but not smaller than 25, a specific gravity not higher than 1.6 g/cm³, a tensile strength of at least 3.2 g/d, and a toxicity test value of at least 10 minutes. A fiber having a specific gravity not higher than 1.46 g/cm³ and a tensile strength of at least 4.0 g/d, which is thermally decomposed and carbonized, as in case of the fiber constituting the flame-proofing layer, without substantial melting when exposed to a flame, is preferred. The toxicity test value referred to herein is the time (minutes) required for a mouse to die when the smoke generated by burning the fiber at 700°C at an air feed rate of ₁1.₄ i/min at an oxygen concentration of 21 % by volume in the fed air is introduced into a box having a volume of ₁25 1 in which the mouse is confined.

As specific examples of the fiber having the above-mentioned characteristics, there can be mentioned a poly-p-phenylene-terephthalamide fiber (such as Kevler fiber supplied by Du Pont Co.), a poly-m-phenyleneisophthalamide fiber (TEIJINCONEX fiber supplied by Teijin Ltd.), a polychlal fiber, a polyester fiber subjected to the flame-retardent treatment, a rayon fiber subjected to the flame-retardent treatment, and an aromatic polyamide fiber comprising units of the following formulae (1), (2), and (3) (such as Polyetheramide fiber supplied by Teijin Ltd.):

wherein Ar,, Ar₂, and Ar₃, which may be the same or different, are an aromatic hydrocarbon ring residue having bonding chains oriented coaxially or in parallel, and Ar4 and Ar., which may be the same or different, are a group selected from a p-phenylene group and a m-phenylene group.

As pointed out hereinbefore, the flame-proofing layer may be a woven fabric, a knitted fabric, a non-woven fabric, a scrim, or a network or a laminate thereof. In view of the simplicity of the manufacturing process and easy moldability, a layer containing a non-woven fabric is preferably used as the flame-proofing layer. A single layer of a non-woven fabric may be used as the layer containing a non-woven fabric, but a web laminate or a laminate or a woven or knitted fabric and a web is preferably used.

For integration of the flame-proofing layer with the reinforcing layer for forming a laminate, there may be used a bonding method using a heat-resistant adhesive resin, a heat-resistant and heat-fusible fiber or a heat-fusible powder. However, it is preferred that a laminate be prepared by integrating both the layers by interlacing by mechanical means such as needling.

The basic weights of the flame-proofing layer and reinforcing layer are at least 10 g/m', preferably the basic weight of at least one of the flame-proofing and reinforcing layers be at least 30 g/m². More preferably both the layers should have a basic weight of at least 30 g/m² and at least one of the two layers should have a basic weight of at least 50 g/m^2. However, in view of the light-weight characteristic of the cushioning member, it is preferred that the upper limit of the basic weight be not more than 700 g/m², especially not more than 500 g/m².

Any customarily used sidepieces may be used in the present invention, but it is preferred that a sidepiece composed of a material having high flame retardancy and flame proofness be used. For example, there may be used a fabric composed completely of wool, a fabric composed completely of wool and subjected to flame-proofing treatment, a fabric composed of a blended yam comprising 10% of an aliphatic polyamide fiber and 90% of wool, a fabric composed of the same blended yam and subjected to the flame-proofing treatment, a fabric composed completely of a modacrylic fiber, a fabric composed of a blended yam of wool, a modacrylic fiber and a polychlal fiber, and a fabric composed of a poly-m-phenylene-isophthalamide fiber. A woven fabric is ordinarily used, but a knitted fabric, a non-woven fabric, or a laminate may be used.

The cushioning member of the present invention has a light-weight characteristic and an easy moldability and also has a very high heat-insufating property and a very high flame-proofing property. This cushioning member can satisfy the FAA flame-proofing regulations which conventional cushioning members fail to satisfy.

The present invention will now be described in detail with reference to the following examples. In the examples, the melting point, specific gravity, limiting oxygen index - (LOI) value), tensile strength, and toxicity test value were determined according to methods described below.

Melting Point

The melting point was determined from the position of the endothermic peak in the differential thermal analysis - (DTA).

Specific Gravity:

• The specific gravity was measured according to the density gradient tube method.

Limiting Oxygen Index (LOI Value):

• The limiting oxygen index was measured according to the method of JIS (Japanese Industrial Standard) K-7201-1972.

Tensile Strength:

• The tensile strength was measured according to the method of JIS L-₁096.

Toxicity Test Value:

• The test apparatus shown in Fig. 3 was used.

The oxygen concentration in circulated air was 21% by volume and the temperature of an electric furnace was adjusted to 700°C, 2 g of a fiber sample was burnt and the generated smoke was introduced into a box having a volume of 125 ℓ in which a mouse was confined. The time - (minutes) of from the point of introduction of the smoke to the point of death of the mouse was measured and expressed as the toxicity test value. Figure 3 is a sectional side view of the test apparatus, in which reference numeral 11 represents a mouse box, reference numeral 12 represents an electrical furnace, reference numeral 13 represents a heat-insulating material according to the present invention, reference numeral 1₄ represents a test fiber-hoiding porous vessel, reference numeral 15 represents a fan, reference numeral 16 represents a fan motor, reference numeral 17 represents an air inlet, and reference numeral ₁8 represents an exhaust outlet

Combustion Test:

• The combustion test was carried out according to the method given in FAA Regulations, Docket No. 2379₁, Notice No. 83-14 (October 26, 1984) described below.

1. FAA Combustion Test Method

1.1 Test Sample

A polyurethane cushion is wrapped with a heat-insulating layer and is then covered with a side-piece to form a seat cushion for an airplane.

• (1) a bottom cushioning member on which the hip is placed has a width of 457 ± 3 mm, a length of 508 3 3 mm, and a thickness of 102 ± 3 mm.
• (2) A back cushioning member had a width of 457 ± 3 mm, a height of 635 ± 3 mm, and a thickness of 51 + 3 mm.

1.2 Test Sample Supporting Stand

Figures 4, 5, and 6 show a steel stand for supporting a test sample (front, side, and plane views respectively). Reference numeral 19 represents a steel plate.

1.3 Setting of Test Sample

Figures 7 and 8 are side and plane views, respectively, illustrating setting of a test sample. The back cushion member 20 and bottom cushioning member 21 are set on the above-mentioned supporting steel stand as shown in Figs. 7 and 8.

1.4 Burner

• (1) A conical burner such as Lennon Model OB-32, Carlin Model 200CRD or Park Model DPL 3₄00 is used. The opening of burner has a height of 152 mm and a width of 280 mm.
• (2) A nozzle capable of spraying a fuel at a rate of 2.25 gallons per hour under 100 psi is used.
• (3) a fuel pressure adjuster is attached to the burner so that a grade #2 kerosine is supplied at a rate of 2.0 gallons per hour.

1.5 Weight Measuring Device

In order to measure the weight before and after the test, a measuring device capable of measuring the total weight of the sample supporting stand and the test sample is used.

1.6 Test Method

• (1) The sample is placed so that the distance between the side face end of the bottom cushioning member of the test sample and the burner end is 102 ± 3 mm.
• (2) The power of the burner is adjusted before setting of the sample, and the introduction rate of air into the bumer is adjusted so that the quantity of heat at the flame-touching central part on the side face end of the cushioning member is 10.5 ± 0.5 BTU/ft²sec (11.9 ± 0.6 W/cm²) and the temperature is 1038 ± 38 °C.
• (3) The sample is placed under the conditions described in (2) above, and the sample is brought into contact with a flame of the burner for 2 minutes.
• (4) The burner is turned off after 2 minutes, and after the elapsing of 5 minutes, the fire is put out by a C0₂ gas fire extinguisher to complete the test.
• (5) The total weight of the sample supporting stand and the test sample is measured before and after the test, and the weight decrease ratio based on the weight of the test sample before the test is calculated.
• (6) The carbonization length of the charred portion is measured.
• (₇) If the weight decrease ratio is not more than ₁0% and the carbonization length is not larger than 17 inches, it is judged that the sample has passed the test.

Abrasion Test

• 1. A polyurethane cushion seat customarily used for an airplane is wrapped with a heat insulating layer and is further wrapped with a dress cover customarily used for an airplane (for example, a woven fabric having a basis weight of 420 g/m² and being composed of a blended yarn comprising 90% wool and 10% nylon-66) to form a test cushioning body.
• 2. A human hip model portion of an abrasion test apparatus is clad in underpants of a 2B tricot texture composed completely of a polyethylene terephthalate fiber. The underpants are exchanged with new ones at intervals of 25 hours.

3. The test apparatus is driven in the following manner.

• (₁) The human hip model portion (weight 63.5 Kg) is brought into contact with the cushioning member for 1 minute and 40 seconds and is then moved upward and kept out of contact with the cushioning member for 20 seconds. Simultaneously with this vertical movement of one cycle per 2 minutes, the hip model portion is caused to make a rocking movement of 14 cycles per minute while drawing a circular arc of 12.3°.
• (2) The test cushioning member is reciprocatively moved at 19.5 cycles per minute while drawing a circular arc of 19.2°.
• (3) The above. operations (1) and (2) are continuously carried out for 25, 50, 75 or 100 hours.

4. The dress cover is removed, and the surface condition and destruction state of the fire-blocking layer are checked.

Example 1

A flame-proofing layer was formed by laminating a polybenzimidazole fiber non-woven fabric having a basis weight of 50 g/m² (PBI non-woven fabric) with a non-woven fabric or a flame-proofing fiber (Pyromex supplied by Toho Rayon K.K.) prepared by preoxidizing a polyacrylonitrile fiber having a basis weight of 50 g/m². Separately, a reinforcing layer was formed by laminating a non-woven fabric composed of a poly-m-phenyleneisophthalamide fiber (TEIJINCONEX, registered trademark, supplied by Teijin Ltd.) and having a basis weight of 50 g/m² Comex, registered trademark, supplied by Teijin Ltd. with a plain weave fabric having a basis weight of 70 g/m², which was prepared by using spun yarns of the above TEIJINCONEX fiber as warps and wefts. The thus-obtained flame-proofing layer and reinforcing layer were laminated as shown in Fig. 1, and the laminate was needle-punched and integrated to form a needle felt heat-insulating layer. Figure 1 is a sectional side view illustrating the heat-insulating layer, wherein reference numeral 1 represents a PBI non-woven fabric, reference numeral 2 represents a Pyromex non-woven fabric, reference numeral 3 represents a TEIJINCONEX non-woven fabric, and reference numeral 4 represents a TEIJINCONEX woven fabric. The results of the evaluation are shown in Table 1.

Examples 2 through 7

Cushioning members were prepared in the same manner as described in Example 1 except that fibers of the flame-proofing and reinforcing layers shown in Table 1 were combined and sidepieces shown in Table 1 were used. The results of the evaluation of these cushion members are shown in Table 1.

^*TEIJINCONEX: registered trademark, poly-m-phenylene-isophthalamide fiber supplied by Teijin Ltd.

TEIJINCONEX-FR: registered trademark, new type poly-m-phenylene-isophthalamide fiber having improved flame and melt resistance over conventional TEIJINCONEX.

PBI: trademark, polybenzimidazole fiber supplied by Celanese Corp.

Pyromex: registered trademark, surface-carbonized polyacrylonitrile fiber supplied by Toho Rayon K.K.

Kynol: registered trademark, polyphenol fiber supplied by Nippon Kynol K.K.

Kevler: registered trademark, poly-p-phenylene-terephthalamide fiber supplied by E.I. Du Pont Co.

Fibers used in the examples and comparative examples and properties thereof are shown in Table 2.

Comparative Examples 1 through 9

Cushioning members were prepared in the same manner as described in Example 1 except that flame-proofing and reinforcing layers were combined as shown in Table 3 and sidepieces- shown in Table 3 were used. In Comparative Examples 1 through 4, the flame-proofing and reinforcing layers were not distinguished from each other but a mixed layer (mixed felt) composed of fibers for the flame-proofing layer and fibers for the reinforcing layer was formed. The results of evaluation are shown in Table 3.