United States Patent c191
`Isoda et al.
`
`I IIIII IIIIIIII Ill lllll lllll lllll lllll lllll lllll lllll lllll llllll Ill lllll llll
`US005298321A
`5,298,321
`[11] Patent Number:
`[45] Date of Patent: Mar. 29, 1994
`
`[75]
`
`[54] RECYCLABLE VEHICULAR CUSHIONING
`MATERIAL AND SEAT
`Inventors: Hideo Isocla, Ootsu; Mitsuhiro
`Sakuda, I wakuni; Y osbihiro Amagi,
`Osaka; Kenji Tanaka, lwakuni; Kunio
`Kimura, Ootsu; Michio Kobayashi,
`Iwakuni; Tadaaki Hamaguchi,
`Iwakuni; Seiji Sawahara, Iwakuni, all
`of Japan
`[73] Assignee: Toyo Boseki Kabushiki Kaisha,
`Osaka,Japan
`[21] Appl. No.: 907,543
`Jul. 2, 1992
`[22] Filed:
`Foreign Application Priority Data
`[30]
`Jul. S, 1991 [JP]
`Japan ............................. 3-060639[U]
`Feb. 26, 1992 [JP]
`Japan .................................. 4-076040
`Feb. 27, 1992 [JP]
`Japan .................................. 4-076217
`Feb. 27, 1992 [JP]
`Japan .................................. 4-076218
`Mar. 16, 1992 [JP]
`Japan .................................. 4-091939
`[51]
`Int. Cl.5 ••••••••••••••••••••••••••••••••••••••••••••••• D04H 1/58
`[52] U.S. Cl •.................................... 428/288; 428/362;
`428/369; 428/373;428/296; 428/297
`[58] Field of Search ............... 428/297, 360, 362, 369,
`428/373, 288
`
`[56]
`
`References Cited
`U.S. PATENT DOCUMENTS
`4,172,174 10/1979 Takagi .
`4,795,668 1/1989 Krueger et al ...................... 428/174
`5,082,720 1/1992 Hayes .................................. 428/224
`5,141,805 8/1992 Nohara et al ....................... 428/296
`
`FOREIGN PATENT DOCUMENTS
`0371807 6/1990 European Pat. Off ..
`Primary Examiner-George F. Lesmes
`Assistant Examiner-Chris Raimund
`Attorney, Agent, or Firm-Wegner, Cantor, Mueller &
`Player
`ABSTRACT
`[57]
`A recyclable vehicular cushioning material which is
`thermoformed from a web composed of three-dimen(cid:173)
`sionally crimped polyester fiber having a fineness lower
`than 45 denier per filament and an initial tensile strength
`(IS) higher than 30 g/d and heat-bonding fiber contain(cid:173)
`ing polyester elastomer, as heat-bonding component,
`which are mixed and dispersed and, if necessary, inter(cid:173)
`laced, said cushioning material having a layer whose
`bulk density is 0.02-0.06 g/cm3.
`
`6 Claims, 1 Drawing Sheet
`
`EX1092
`Yita v. MacNeil
`IPR2020-01139
`
`

`

`U.S. Patent
`
`Mar. 29, 1994
`
`5,298,321
`
`D
`
`(/')
`(/')
`LIJ
`0:
`1-(cid:173)
`(/')
`LLJ
`...J
`
`I-
`
`~ LIJ
`B .,______. E
`G a----n
`
`A
`
`0
`
`CF
`
`ELONGATION (%)
`
`FIG. 1
`
`

`

`RECYCLABLE VEHICULAR CUSHIONING
`MATERIAL AND SEAT
`
`5
`
`1
`
`5,298,321
`
`2
`greatly undergoes plastic deformation because its body
`material is polyester fiber made by a conventional
`method and having a glass transition temperature lower
`than 70° C.
`BACKGROUND OF THE INVENTION
`The covering of vehicular seats is usually made of
`1. Field of the Invention:
`nylon tricot, nylon moquette, polyvinyl chloride, and
`The present invention relates to a recyclable vehicu-
`urethane-impregnated synthetic leather, which are su-
`lar cushioning material and seat.
`perior in durability. The nylon covering is mostly dis-
`2. Description of the Prior Art:
`posed of together with the pad by incineration or land
`Among the known vehicular cushioning materials is lO reclamation because its separation from the pad costs
`polyurethane. Polyurethane is in general use as a vehic-
`too much and it is difficult to collect it in such large
`ular cushioning material because of its good durability,
`quantities as to warrant the cost for recycling. (Nylon 6
`cushioning properties, and processability as well as its
`can be recovered in the form oflactum after depolymer-
`low price. However, polyurethane has a disadvantage
`ization and hence nylon fishing nets are collected for
`of being combustible. Upon combustion, it gives off a 15 recovery.) Moreover, the covering for vehicular seats
`large amount of toxic gases, which endanger passengers
`usually contains a halogen-based flame retardant so that
`in the case of vehicular fire. To cope with this situation,
`it meets the requirements for flame retardance. There-
`polyurethane is incorporated with a halogen-containing
`fore, the covering of nylon, polyvinyl chloride, or poly-
`flame retardant. This flame retardant, however, does
`urethane gives off a large amount of toxic cyan gas and
`n?t make polyurethane inco~bustible completely but 20 halogen gas upon combustion, and these combustion
`gtve~ off a large 8:ID?unt_ of toxic halogen ~as once _com-
`gases are extremely dangerous in the case of vehicular
`bust1on start_s. This 1s quite dangerous particularly m the
`fire. Their disposition by incineration is expensive if an
`case of fire ~ a tunnel or underpass.
`.
`.
`adequate measure is to be taken to prevent air pollution.
`Another disadvantage of polyurethane 1s that 1t be-
`Therefore they are often left or buried The covering of
`':°mes greatly ~eteriorated after use f?r a long J>t:riod of 25 polyester is supposed to be treated in ~he same manner
`time, and d~tenorat:d polyure~hane 1_s usually d1spo_sed
`as mentioned above if it is combined with a cushioning
`of because 1~ reuse ~vo~ves_ d1~cult1es and a_ pract~cal
`material of polyurethane or rubber.
`~ethod fo~ its r~~yclmg 1s still m the _stage of mve_st1~a-
`Nothing has so far been proposed for the vehicular
`tion. The d1spos1t1on of polyurethane 1s usually by mcm-
`.
`.
`.
`.
`.
`.
`11
`t.
`ft
`t'
`b
`· k d al
`O td
`.
`.
`30 seat and its cushioning ·matenal havmg httle stuffiness
`era 10n a er co ec ion y Jun
`e ers. u oor mcm-
`h. h
`·
`d
`· h
`I bir
`·
`ti
`w_ 1~ are _designe wit sa ety and recyc a
`eration brings about air pollution with toxic gases (such
`tty m
`as cyan gas). Incineration by an incinerator can remove
`mm ·
`toxic gases, but it is expensive because the incinerator is
`SUMMARY OF THE INVENTION
`subject to corrosion by toxic gases. Therefore, polyure-
`thane is usually disposed of by dumping in the site of 35
`It is an object of the present invention to provide a
`land reclamation. Being a cellular material, polyure-
`vehicular seat and its cushioning material which offer
`thane keeps the ground unstable. For this reason, a large
`the following advantages.
`amount of polyurethane is now left in an open space,
`Absence of stuffiness which obviates the necessity of
`and a very little of it is recycled at the present time.
`forced ventilation during use.
`Recently, a new vehicular cushioning material has 40 High safety from accidental deaths by toxic combus-
`appeared which is made with fibers to eliminate the
`tion gases.
`stuffiness of seats. It is used for some deluxe cars. The
`Recyclability which obviates the necessity of dispo-
`fibers are natural fiber or synthetic fiber combined with
`sition by incineration or land reclamation. (This
`an adhesive (such as polyurethane and rubber latex) for
`contributes to the reduction of air pollution and
`improved durability. It is anticipated that this cushion- 45
`global warming by combustion gas.)
`ing material will follow the fate of polyurethane on
`Good heat-resistance and cushion property retention.
`account of its unique composition. Another new cush-
`Briefly, the present invention is embodied in a vehicu-
`ioning material is for the breathable seat designed to
`lar cushioning material which is thermoformed from a
`eliminate stuffiness. It is composed of three-dimension-
`web composed of three-dimensionally crimped polyes-
`ally crimped thick polyester fibers bonded together so ter fiber having a fineness lower than 45 denier per
`with rubber latex. This cushioning material, too, will
`filament and an initial tensile strength (IS) higher than
`follow the fate of polyurethane because of its unique
`30 g/d and heat-bonding fiber containing polyester
`composition. Moreover, it involves a risk of candle
`elastomer as heat-bonding component, which are mixed
`effect (i.e. burning like candle) in the case of fire.
`and dispersed and, if necessary, interlaced, said cushion-
`There is known a polyester fiber-based cushioning 55 ing material having a layer whose bulk density is
`0.02-0.06 g/cm3•
`material in which three-dimensionally crimped polyes-
`ter fibers are heat-bonded ~ith lo~-~elting no~-elas-
`BRIEF DESCRIPTION OF THE DRAWING
`tomer copolyester fibers. This cushioning matenal has
`found use for mattresses because of its good moisture
`FIG. 1 is a stress-strain curve for the crimped polyes-
`permeability (which alleviates stuffiness). Being ther- 60 ter fiber.
`moplasti~, it m_ay be regenerated b~ melting into fibers.
`DETAILED DESCRIPTION OF THE
`Altemat1vely, 1t may be recovered m the form of mono-
`INVENTION
`mer after methanolysis. Despite these advantages, it is
`not suitable for vehicular seats to be used under severe
`conditions because it is poor in permanent set resistance 65
`at high temperatures. In other words, it readily under(cid:173)
`goes plastic deformation upon compression at 70° C.
`because the bonding material is amorphous and it also
`
`According to the pr_esent invention, the vehicular
`seat and its cushioning material are entirely made of
`polyester fibers and hence they can be recycled by
`simple melting without the need of separating the cov(cid:173)
`ering from the pad. Alternatively, they can also be
`
`

`

`5,298,321
`
`45
`
`3
`4
`recovered after decomposition into monomers by any
`and the Cn value is higher than 10/inch. These condi-
`known method such as methanolysis. According to the
`tions are necessary for the cushioning material to have
`present invention, more than 95%, preferably more
`very good permanent set resistance at high tempera-
`than 99%, of the constituent is polyester, and the use of
`tures. The polyester fiber that does not satisfy the condi-
`other materials than additives is limited. Preferred addi- s tion IS~(AE+0.6)-2.Sx 103+ 10 will be poor in perma-
`tives should not contain any halogen compound or
`nent set resistance at high temperatures even though it
`nitrogen compound which gives off toxic ¥ases in the
`has an IS value as high as 50 g/d. Moreover, it is desir-
`case of fire. Moreover, those polyesters which are non-
`able that the polyester fiber satisfy the condition
`thermoplastic or infusible due _to crosslinking_ should be
`IS~(AE+0.6)-2.Sx 1()3+ 12, in which case the polyes-
`excluded from the raw matenals of the vehicular seat 10 ter fiber retains more than 70% of the Ci value after 15
`hours under a load of 5 mg/d at 70° c. It is more desir-
`an~ its cushioning material! because they readily burn
`owmg to !he candle effect m. the ~ of fire.
`.
`.
`able that the polyester fiber satisfy the condition
`Ac:or~mg to the present mve!1t10n,. the cus~onmg
`IS~(AE+0.6)-2.Sx 103+ 15, in which case the polyes-
`matenal . ts ~ased. on the three-dune~,o~ally c~ped
`ter fiber retains more than 80% of the Ci value after 15
`I d f 5 g/d at 70° c
`fiber which 1s desirable on account of1ts high bulkiness. 15 h
`d
`ours_un er a oa O m
`Crimping in the wavy form is preferable. The crimp
`·
`index (Ci) should be higher than 15%; otherwise, the
`lnc1dentally, fl~ after heat treatment ~ IS_ were
`desired bulkiness is not obtained. The crimp number
`measured accordmg to the_ method descn~ed m JIS
`(Cn) should be greater than 10/inch; otherwise, the
`L-1063._ The measurement gives a stress-_stram curve ~s
`desired elastic (i.e. bouncing properties are not ob- 20 shown m F~~-_1. The stress between pomts A and C! 1s
`?u~ to the 1D1tial lo~d. T_he stress at 1°';>% elongat10~
`tained. An adequate crimp index and crimp number
`should be selected according to the feel desired. For the
`mdtcated by the straight Im: CD tan~ent1al to the maXI-
`mum slope of the stress-stram curve !s defmed as the IS
`soft layer, Cn should be on the low side and Ci should
`be on the high side. For the soft layer that needs elastic
`(g/d~ a~te~ treatm:nt: The elongat10n_ OF ~p to t~e
`properties, both Cn and Ci should be on the high side. 25 elastic hmit E dev1at!ng from the st_ra1~h~ lme CD 1s
`For the hard layer, Cn should be high. For the interme-
`defmed as the elongation (AE) at elastic limit. The value
`diate cushion layer, Ci should be higher than 15% and
`is indicated as an average of 50 measurements.
`Cn should be higher than 10/inch. Ci higher than 25%
`According to the present invention, the three-dimen-
`and Cn in the range of 15-30/inch are desirable in the
`sionally crimped polyester fiber for the cushioning ma-
`case where not only bulkiness but also. resilience and 30 terial should have a specific cross section, either hollow
`hardness are required.
`or contour, that makes the polyester fiber bulky, stiff,
`According to the present invention, the three-dimen-
`and hard. Anisotropic cross-section is desirable which is
`sionally crimped polyester fiber for the cushioning ma-
`obtained by asymmetric cooling. Hollow cross-section
`terial is formed from polyethylene terephthalate (PET),
`with three projections is most desirable.
`polyubtylene terephthalate (PBT), polye~hylene naph- 35 According to the present invention, the three-dimen-
`thalate (PEN), or polycyclohexylened1methyl tere-
`sionally crimped polyester fiber should have a much
`phthalate (PCHDT), or a copolymer thereof, which are
`higher crystallinity than any other known three-dimen-
`all recyclable. Of these polymers,. PET, PEN, and
`sionally crimped fiber so that it undergoes deformation
`PCHDT are preferable because of their good heat resis-
`little in heat treatment at as high as 200° C. This high
`tance.
`.
`.
`.
`.
`40 crystallinity may be expressed in terms of a specific
`. Accord1~g to the present mvent1on, the th~ee:dtmen-
`gravity higher than 1.39, preferably higher than 1.40.
`s1o~ally cnmped polyester fiber for the cush1o~g ma-
`Although there are no specific restrictions on the
`tenal should ha".'e. ~ fmene_ss lower than 45 ?eruer per
`staple length, it should preferably be 40-120 mm so as to
`filament and an 1mt1al tensile strength (IS) higher than
`facilitate ordinary carding and opening and maintain
`35 g/~, preferably higher t~an 40 g/d, and more prefer-
`entanglement.
`ably higher than 45 g/d._W_1th an IS value l<?wer than 35
`According to the present invention, the cushioning
`pd, the pol>:ester fiber 1s hable to_ damage m the bl_end-
`material is produced by thermoforming from a web
`mg ~d open!ng process and al_so ~able to d~crease m_ IS
`composed of the above-mentioned three-dimensionally
`dunng moldmg mto the cushiomng matenal at a high
`crimped polyester fiber and the heat-bonding fiber con-
`temperat?re. (Low ~S values have an adverse ~ffect on 50 taining polyester elastomer, as heat-bonding compo-
`the. elastic prol?ert1es and permanent set res1stan~e.)
`nent, which are mixed and dispersed and, if necessary,
`Owmg to the hig~ IS valu~, the poly~ster fiber w~th-
`interlaced. Since the heat-bonding fiber is made ofpoly-
`stands the stretchin~ stress m th_e card'!1g and operung
`ester, the cushioning material is recyclable.
`process, under¥oes httl~ heat shrinkage m th~ post treat-
`According to the present invention, the heat-bonding
`mlent~' ~t d retams the high permanent set resistance and 55 fiber should be of sheath-core type. (If the sheath (or the
`e as tci y.
`t bo d.
`h
`d
`I
`t) ·
`It'
`f
`According to the present invention, the three-dimen-
`ea • n mg _compo~en
`is ma e O a ow-me mg
`sionally crimped polyester fiber for the cushioning ma-
`non-elastomenc m~ten~, sue~ as an am?rph?us ~opoly-
`terial should have a heat resistance which satisfies the
`~ter of terephthahc acid _and 1Sophthahc acid d1scl~sed
`following condition.
`~ Japan~e ~atent _Koka1 No. 15:1()50/90, the cushio!1-
`60 mg matenal 1s considerably poor m permanent set resis-
`tance because of its strong tendency toward plastic
`deformation.) According to the present invention, the
`sheath component should preferably be a polyester
`elastomer having a melti.ng point (Tm1) of 160'-220° C.,
`a peak temperature (T/3) lower than -40° C. for the
`/3-dispersion of tan 6, and a rise temperature (Tacr)
`higher than 50' C. for the a-dispersion of tan 6, and the
`core component should preferably be a non-elastomer
`
`(where AE denotes the elongation (%) at elastic limit,
`including the elongation of crimp, which is measured
`after dry-heat treatment at 200° C. for 5 minutes under 65
`no load.) In addition, the preferred material for the
`intermediate cushioning layer should be three-dimen(cid:173)
`sionally crimped so that the Ci value is higher than 15%
`
`IS~(AH0.6)-2·8x toJ+ 10
`
`

`

`5,298,321
`
`s
`6
`crimps, so long as it can be formed into a web by uni-
`polyester having a melting point (Tm2) which is higher
`than Tmt by at least 20° C.
`fonn dispersion in the blending and opening process.
`Accordipg to the present invention, the core of the
`The polyester elastomer as used in the present inven-
`heat-bonding fiber is made of non-elastomer polyester.
`tion denotes a block copolymer composed of hard seg-
`ments and soft segments. The hard segments include, 5 With an elastomer alone, the heat-bonding fiber is poor
`for example, PET, PBT, PEN, and PCHDT. The soft
`in dimensional stability and crimpability and presents
`segments include, for example, polytetramethylene gly-
`difficulties in the web forming owing to its rubbery
`col (PTMG), polyhexamethylene glycol (PHMG),
`resilience which prevents uniform blending and open-
`polypropylene glycol (PPG), and polycaprolactone
`ing. If it were not for the core, the heat-bonding fiber
`(PCL). Their preferred combinations are, for example, 10 will form a coarse net~work structure with the body
`PEN/PTMG,
`PBT/PCL,
`and
`material, yielding a soft cushioning material. This prob-
`PBT/PTMG,
`PBT /PP A.
`lem is solved by making the core from a non-elastomer
`PTMG as the soft segment should preferably have a
`polyester. If the non-elastomer polyester as the core
`molecular weight of 1000-3000. There is an optimum
`component has Tm2 which is lower than Tm1 of the
`combination of the soft segments and hard segments 15 sheath component by at least 20• C., the core (which
`forms the net-work structure with the body material) is
`which depends on their composition and the number of
`repeating units. The optimum combination meets the
`heated beyond the crystal melting point at ihe time of
`above-mentioned requirements-T/3 lower than -40°
`thermoforming. This causes the orientation of fiber to
`C., preferably lower than - 50° C., and Tacr higher
`disappear, resulting in poor permanent set resistance.
`than so• C., preferably higher than 60° C., so that the 20 This problem is solved if Tm2 is higher by at least 20°
`fiber has good recovery after stretching at 70° C. The
`C., preferably at least 30° C. The core component
`heat-bonding fiber with such bonding component is
`should be PET, PBT, etc. which is capable of melt
`spinning at a temperature low enough to prevent the
`combined with the above-mentioned body material so
`deterioration of the elastomer. A crystalline component
`as to produce the vehicular cushioning material having
`the desired properties. With T/3 higher than -40° C., 25 is desirable because of its weak tendency toward ther-
`the cushioning material is poor in recovery; with Tacr moplastic deformation. A copolymer containing a large
`amount of amorphous polyethylene isophthalate is not
`lower than 50° C., the cushioning material is liable to
`desirable because it is liable to plastic deformation and
`plastic deformation.
`hence is poor in permanent set resistance.
`According to the present invention, the polyester
`elastomer should have Tm1 higher than 160° C.; other- 30
`The heat-bonding fiber should have a low heat
`wise, it is poor in heat resistance and long-term heat
`shrinkage, so that it forms bond points uniformly at the
`time of thermoforming. The higher the heat shrinkage,
`stability. Also, the polyester elastomer should have
`Tm1 lower than 220° C.; otherwise, its soft segments are
`the more the delamination is liable to occur. The heat
`shrinkage by dry heating at 130° C. should be lower
`subject to deterioration and decomposition during the
`thermoforming of the cushioning material which is 35 than 20%, preferably lower than 15%. In addition, the
`performed at a temperature higher than Tm1 by at least
`heat-bonding fiber should have a high IS so that it un-
`100 C. At such a high temperature, even the body mate-
`dergoes less stretch deformation in the opening process.
`This leads to a low shrinkage in the web and reduces the
`rial (the three-dimensionally crimped polyester fiber)
`decreases in IS, yielding the cushioning material poor in
`chance of delamination. The preferred IS 15 g/d.
`permanent set resistance. The preferred range of Tm1 is 40
`The heat-bonding fiber in the present invention is not
`from 170° C. to 210° C., at which the cushioning mate-
`specifically limited in the fineness per filament. Any
`fineness will suffice so long as the heat-bonding fiber is
`rial exhibits good permanent set resistance.
`According to the present invention, the heat-bonding
`capable of blending with and dispersion into the body
`fiber should be of sheath-core type, so that bonding
`material in the blending and opening process. If the
`takes place at all the points where the heat-bonding 45 body material has a fineness of 6-15 denier, the heat-
`fibers come into contact with the body material. This
`bonding fiber should have a fineness greater than 3
`denier so that it is capable of uniform dispersion. An
`structure disperses the force applied to the body mate-
`rial and the contact points absorb the force through
`adequate fineness should be established by taking into
`account the ability to produce as many bond points as
`their deformation. This prevents the body material from
`permanent set and improves the recovery of the body SO possible and the capability of uniform blending. It is 2-4
`denier for the 6-denier body material, or 4-8 denier for
`material. If the heat-bonding fiber is not of sheath-core
`type, bonding points will not be enough in number and
`the 13-denier body material.
`strength to construct the satisfactory net-work struc-
`The component for the heat-bonding fiber may be
`ture. This leads to poor force dispersion and hence poor
`optionally incorporated with a delustering agent, pig-
`55 ment, antioxidant, UV light absorber, flame retardant,
`permanent set resistance.
`The sheath/core ratio should preferably be from
`etc. in amounts not harmful to recycling.
`10/90 to 90/10. If the sheath is less than 10%, the heat-
`The cushioning material of the present invention
`bonding fiber does not produce sufficient bond points,
`should preferably contain the body material in an
`amount equal to 30-95 wt %. With an amount less than
`which leads to poor force dispersion and poor perma-
`nent set r~istance. Conversely, if the sheath is more 60 30 wt %, the cushioning material does not have the
`desired bulkiness. With an amount in excess of 95%,
`than 90%, the heat-bonding fiber is poor in dimensional
`stability, which causes trouble during processing. The
`there will not be sufficient bond points required for
`most preferable range is from 30/70 to 60/40. The core
`elastic recovery and dimensional stability. The most
`may be eccentric or composed of two components. In
`preferable amount is 50:-80 wt %. With an amount in
`this case, the heat-bonding fiber is bulky due to three-di- 65 this range, the elastomer forms sufficient bond points
`which disperse the force uniformly in the cushioning
`mensional crimping. The heat-bonding fiber to be used
`for the cushioning material of the present invention may
`material, alleviating the damage which individual fibers
`have either mechanical crimps or three-dimensional
`would otherwise experience.
`
`

`

`5,298,321
`
`7
`8
`The cushioning material of the present invention is
`tired. Conversely, with a bulk density higher than 0.03
`formed by thermoforming from the above-mentioned
`g/cm3, the surface layer feels hard, causing the sitter to
`three-dimensionally crimped polyester fiber and heat-
`feel the rebound of the cushioning layer, although the
`bonding polyester fiber, which are mixed and dispersed
`bottoming-out is small and the sitter does not feel tired
`in the above-mentioned mixing ratio, and interlaced, if 5 soon. The intermediate layer should be designed taking
`necessary.
`into account the function of the elastic body which
`The mixing may be accomplished, for example, by
`insulates the vibration of vehicles and supports the sit-
`placing on the body material fiber the heat-bonding
`ter. With a bulk density lower than 0.02 g/cm3, the
`fiber (in the form of sheet) in the desired mixing ratio,
`intermediate layer does not provide sufficient rebound
`and sending them to the opener for preliminary open- 10 resilience to support the sitter's weight, making the
`ing. The thus obtained staple fibers are fed to a card to
`sitter feel bottoming-out strongly. Conversely, with a
`prepare a web. (It is possible to prepare a web by the aid
`bulk density higher than 0.06 g/cm3, the intermediate
`of air-lay. In this case, the resulting web is composed of
`layer is superior in rebound resilience but is poor in the
`individual staple fibers which are placed on top of the
`ability to insulate vibration. The base layer should be
`other and hence is less liable to delamination.) As many 15 designed taking into account the function to support the
`webs as necessary to achieve the desired basis weight
`cushion body. With a bulk density lower. than 0.06
`are laminated one over another. Webs may be tempo-
`g/cm3, the base layer is too soft to support the cushion
`r~y. bonded to one anothe~ by heating their su1:£aces
`layer, causing the cushioning material to collapse. With
`with infrared rays. ~e lamm~ted webs may"<; mter-
`a bulk density higher than 0.15 g/cm3, the base layer is
`laced by n7~dlepunc~g to adJust t~e bulk density and 20 too hard to cushion the upper two layers against the
`also to facilitate han?lmg. The lami~ate? webs finally
`sitter's weight accelerating the permanent set of the
`undergo thermoforming by compression m such a man-
`'
`.
`.
`d rt. 1 h
`b lk d
`·t th
`upper two layers. Incidentally, 1f the base layer has a
`th t th fi
`1
`ner a
`e orme a 1c e as a ower u
`ens1 y an
`hi h b lk d
`·
`h
`h'
`·
`· 1
`that obta' db
`Id'
`g
`u
`ens1ty, t e cus 10nmg matena may not
`Subs qiuneentlyy mtho
`lmg._
`t d
`b
`di
`h d 25 easily collapse in the burning test. In this case, it is
`e
`,
`e amma e we s, nee epunc e
`d
`. bl h
`h
`hi
`·
`'al b
`·
`d
`webs, or primary thermoformed webs are further lami-
`~ma e t at t e cus onmg maten
`e n~corporat~
`nated and made into a single body by thermoforming
`with flame !etardant polyester fibers which contain
`using a mold. Thus there is obtained a cushioning mate-
`phosphorus man amount of 300-1000 ppm, preferably
`rial desired.
`500-~000 ppm.
`According to the most preferred embodiment of the 30
`It 1s des~able tha~ the surface layer account for 10-30
`present invention, the preliminary thermoforming is
`wt %, the mtermed1ate layer, 60-80 wt %, and the base
`carried out such that the formed article has a bulk den-
`layer, 5-30 wt %.
`sity which is from ½ to i of the intended bulk density.
`T~e above-mentioned fundar_nen~! des~gn may be
`After cooling, the preliminarily formed article is ther-
`modified sue~ th?t ~ach layer 1~ d1v1~ed mto two or
`moformed again by compression to the intended bulk 35 more Iarers ~1ffenng m bulk density "".h1ch are arrange?
`density at a temperature which is higher than 70• c. but
`seque11:t1ally m t~e o~der of bulk density or one layer 1s
`lower than the Tm1 by at least 30° c. This two-step
`sandwiched_ by_ 1dent1cal_ two layers.
`.
`.
`The cushion_n:ig matenal ?f the present ~~ention has
`thermoforming yields the cushioning material having
`greatly improved recovery at 70° c. The conceivable
`both breathabihty and mmsture permeability. There-
`reason for this is that the second thermoforming gives 40 fore, it doe~ not substantially feel stuffy _un~ike polyure-
`rise to a structure, which is not completely crystalline
`thane e~e? m the absence of forced ventdat~on: Presum-
`a~ly, this 1s due to !he rec?very of the cushi~mmg mat7-
`but functions as the cross-linking points to join soft
`segments one another, greatly improving the permanent
`nal from compress10n which pumps out moist warm air
`set resistance. This reasoning is based on the fact that a
`and pumps in outside fresh air.
`small endothermic peak (Tmc), which is lower than the 45
`The cushioning material of the present invention
`melting point by at least 70° C., is noticed in addition to
`should usually conform to the standard for automoti.ve
`Tm1 in the cushioning material which has undergone
`flame retardance when tested according to the method
`heat treatment twice. It is considered that this endother-
`of FM MVSS302. However, it may fail to conform if
`mic peak is due to the melting of crystals in the heat-
`the base layer has a high bulk density or the heat-bond-
`bonding component.
`50 ing fibers are not uniformly distributed.
`The cushioning material of the present invention
`The cushioning material of the present invention is
`should have at least one layer which has a bulk density
`flame retardant presumably because the low-melting
`of0.02-0.06 g/cm3 and exhibits the cushioning function.
`heat-bonding component greatly decreases in melt vis-
`In the case where the cushioning material is placed
`cosity when exposed to high temperatures as in the case
`directly on a base, the cushioning material may be com- 55 where decomposition is promoted by the phosphorus
`posed of a single layer having a bulk density of
`compound incorporated into ordinary flame retardant
`0.02-0.06 g/cm3. However, it is desirable to make the
`fiber, and the low-viscosity melt easily drips, destroying
`cushioning material from several layers-a surface layer
`the structure of the nearby high-melting polyester and
`having a bulk density of 0.008-0.03 g/cm3 for soft feel,
`thereby preventing combustion from spreading. In ad-
`an intermediate layer having a bulk density of0.02-0.06 60 dition, the cushioning material is highly safe even in the
`g/cm3 for adequate resilience and form retention, and a
`case of fire because it only gives off combustion gases
`base layer having a bulk density of 0.06-0.15 g/cm3 for
`such as carbon dioxide and hydrocarbons which have a
`form retention and supporting the cushion through the
`low toxicity index (calculated by dividing the amount of
`cushioning layer and springs.
`combustion gas generat~d by the lethal dose (mg/10 L)
`The surface layer is designed so as to provide a soft 65 by inhalation for 5-10 minutes).
`feel and an adequate degree of bottoming. With a bulk
`This effect is not produced if the bonding component
`density lower than 0.008 g/cm3, the surface layer is too
`contains rubber or incombustible materials. Any part
`soft to prevent bottoming-out, making the sitter feel
`which does not readily burn functions as a candlewick,
`
`

`

`5,298,321
`
`9
`10
`spreading combustion, which constitutes a serious dan-
`point (Tg) and lower than 100" C. Deviation from this
`ger.
`range prevents stretching with an adequate draw ratio
`The seat of the present invention may be made flame
`in the second and third steps. Stretching in the second
`retardant if it is provided with a covering of polyester
`step should be 0.80-0.85 times the MOR at 120°-180°
`fiber, preferably flame-retardant polyester fiber. The 5 C., preferably 150"-170" C. Deviation from this range
`flame retardance of the seat is ensured by using an inner
`prevents stretching with a high tension at a high tern-
`lining fabric of flame-retardant fiber.
`perature in the third step. Stretching in the third step
`According to the preferred embodiment of the pres-
`should be 0.9-0.95 times the MOR at a temperature
`ent invention, the flame-retardant polyester fiber is one
`lower than the crystal melting point by 5° -20° C. Fi-
`which contains a phosphorus-containing flame retar- 10 nally (in the fourth step), the stretched fiber undergoes
`dant or a phosphorus-containing ester-forming com-
`relaxation (less than 1%), or preferably, the stretched
`pound copolymerized therein which does not give off
`fiber is cooled to Tg, with the fiber length kept con-
`toxic combustion gases. Examples of such polyester
`stant, to complete the structure. The known conven-
`fiber are disclosed in Japanese Patent Kokai Nos.
`tional method Jacks this fourth step disclosed in this
`8239/76 and 7888/80 and Japanese Patent Publication 15 invention. Without the fourth step, the stretched fiber
`No. 41610/80. Alternatively, the desired flame retard-
`loses its tension, which results in dec