EP1677971A1 - Composite insulation - Google Patents

Composite insulation

Info

Publication number
EP1677971A1
EP1677971A1 EP04768960A EP04768960A EP1677971A1 EP 1677971 A1 EP1677971 A1 EP 1677971A1 EP 04768960 A EP04768960 A EP 04768960A EP 04768960 A EP04768960 A EP 04768960A EP 1677971 A1 EP1677971 A1 EP 1677971A1
Authority
EP
European Patent Office
Prior art keywords
layer
fibres
layers
sheet insulation
fibre
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP04768960A
Other languages
German (de)
French (fr)
Inventor
Peter John Harris
Robert Charles Harris
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Auto Insulations Ltd
Original Assignee
Auto Insulations Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from GB0324657A external-priority patent/GB0324657D0/en
Priority claimed from GB0400560A external-priority patent/GB0400560D0/en
Priority claimed from GB0411897A external-priority patent/GB0411897D0/en
Application filed by Auto Insulations Ltd filed Critical Auto Insulations Ltd
Publication of EP1677971A1 publication Critical patent/EP1677971A1/en
Withdrawn legal-status Critical Current

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B5/00—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts
    • B32B5/22—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts characterised by the presence of two or more layers which are next to each other and are fibrous, filamentary, formed of particles or foamed
    • B32B5/24—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts characterised by the presence of two or more layers which are next to each other and are fibrous, filamentary, formed of particles or foamed one layer being a fibrous or filamentary layer
    • B32B5/26—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts characterised by the presence of two or more layers which are next to each other and are fibrous, filamentary, formed of particles or foamed one layer being a fibrous or filamentary layer another layer next to it also being fibrous or filamentary
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60R—VEHICLES, VEHICLE FITTINGS, OR VEHICLE PARTS, NOT OTHERWISE PROVIDED FOR
    • B60R13/00—Elements for body-finishing, identifying, or decorating; Arrangements or adaptations for advertising purposes
    • B60R13/08—Insulating elements, e.g. for sound insulation
    • D—TEXTILES; PAPER
    • D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
    • D04H—MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
    • D04H1/00—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres
    • D04H1/40—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties
    • D04H1/42—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties characterised by the use of certain kinds of fibres insofar as this use has no preponderant influence on the consolidation of the fleece
    • D04H1/4282—Addition polymers
    • D04H1/4291—Olefin series
    • D—TEXTILES; PAPER
    • D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
    • D04H—MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
    • D04H1/00—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres
    • D04H1/40—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties
    • D04H1/42—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties characterised by the use of certain kinds of fibres insofar as this use has no preponderant influence on the consolidation of the fleece
    • D04H1/4326—Condensation or reaction polymers
    • D04H1/435—Polyesters
    • D—TEXTILES; PAPER
    • D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
    • D04H—MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
    • D04H1/00—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres
    • D04H1/40—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties
    • D04H1/54—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties by welding together the fibres, e.g. by partially melting or dissolving
    • D04H1/559—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties by welding together the fibres, e.g. by partially melting or dissolving the fibres being within layered webs
    • D—TEXTILES; PAPER
    • D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
    • D04H—MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
    • D04H1/00—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres
    • D04H1/40—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties
    • D04H1/58—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties by applying, incorporating or activating chemical or thermoplastic bonding agents, e.g. adhesives
    • D04H1/593—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties by applying, incorporating or activating chemical or thermoplastic bonding agents, e.g. adhesives to layered webs
    • D—TEXTILES; PAPER
    • D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
    • D04H—MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
    • D04H13/00—Other non-woven fabrics
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01H—MEASUREMENT OF MECHANICAL VIBRATIONS OR ULTRASONIC, SONIC OR INFRASONIC WAVES
    • G01H3/00—Measuring characteristics of vibrations by using a detector in a fluid
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/16—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/162—Selection of materials
    • G10K11/168—Plural layers of different materials, e.g. sandwiches
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2262/00—Composition or structural features of fibres which form a fibrous or filamentary layer or are present as additives
    • B32B2262/02—Synthetic macromolecular fibres
    • B32B2262/0253—Polyolefin fibres
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2262/00—Composition or structural features of fibres which form a fibrous or filamentary layer or are present as additives
    • B32B2262/02—Synthetic macromolecular fibres
    • B32B2262/0276—Polyester fibres
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2307/00—Properties of the layers or laminate
    • B32B2307/10—Properties of the layers or laminate having particular acoustical properties
    • B32B2307/102—Insulating
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60R—VEHICLES, VEHICLE FITTINGS, OR VEHICLE PARTS, NOT OTHERWISE PROVIDED FOR
    • B60R13/00—Elements for body-finishing, identifying, or decorating; Arrangements or adaptations for advertising purposes
    • B60R13/08—Insulating elements, e.g. for sound insulation
    • B60R13/0815—Acoustic or thermal insulation of passenger compartments
    • B60R13/083—Acoustic or thermal insulation of passenger compartments for fire walls or floors
    • E—FIXED CONSTRUCTIONS
    • E04—BUILDING
    • E04B—GENERAL BUILDING CONSTRUCTIONS; WALLS, e.g. PARTITIONS; ROOFS; FLOORS; CEILINGS; INSULATION OR OTHER PROTECTION OF BUILDINGS
    • E04B1/00—Constructions in general; Structures which are not restricted either to walls, e.g. partitions, or floors or ceilings or roofs
    • E04B1/62—Insulation or other protection; Elements or use of specified material therefor
    • E04B1/74—Heat, sound or noise insulation, absorption, or reflection; Other building methods affording favourable thermal or acoustical conditions, e.g. accumulating of heat within walls
    • E04B2001/742—Use of special materials; Materials having special structures or shape
    • E04B2001/745—Vegetal products, e.g. plant stems, barks
    • E—FIXED CONSTRUCTIONS
    • E04—BUILDING
    • E04B—GENERAL BUILDING CONSTRUCTIONS; WALLS, e.g. PARTITIONS; ROOFS; FLOORS; CEILINGS; INSULATION OR OTHER PROTECTION OF BUILDINGS
    • E04B1/00—Constructions in general; Structures which are not restricted either to walls, e.g. partitions, or floors or ceilings or roofs
    • E04B1/62—Insulation or other protection; Elements or use of specified material therefor
    • E04B1/74—Heat, sound or noise insulation, absorption, or reflection; Other building methods affording favourable thermal or acoustical conditions, e.g. accumulating of heat within walls
    • E04B1/76—Heat, sound or noise insulation, absorption, or reflection; Other building methods affording favourable thermal or acoustical conditions, e.g. accumulating of heat within walls specifically with respect to heat only
    • E04B2001/7691—Heat reflecting layers or coatings
    • E—FIXED CONSTRUCTIONS
    • E04—BUILDING
    • E04B—GENERAL BUILDING CONSTRUCTIONS; WALLS, e.g. PARTITIONS; ROOFS; FLOORS; CEILINGS; INSULATION OR OTHER PROTECTION OF BUILDINGS
    • E04B1/00—Constructions in general; Structures which are not restricted either to walls, e.g. partitions, or floors or ceilings or roofs
    • E04B1/62—Insulation or other protection; Elements or use of specified material therefor
    • E04B1/74—Heat, sound or noise insulation, absorption, or reflection; Other building methods affording favourable thermal or acoustical conditions, e.g. accumulating of heat within walls
    • E04B1/82—Heat, sound or noise insulation, absorption, or reflection; Other building methods affording favourable thermal or acoustical conditions, e.g. accumulating of heat within walls specifically with respect to sound only
    • E04B1/84—Sound-absorbing elements
    • E04B2001/8457—Solid slabs or blocks
    • E04B2001/8461—Solid slabs or blocks layered
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
    • Y02A30/00—Adapting or protecting infrastructure or their operation
    • Y02A30/24—Structural elements or technologies for improving thermal insulation
    • Y02A30/244—Structural elements or technologies for improving thermal insulation using natural or recycled building materials, e.g. straw, wool, clay or used tires

Definitions

  • This invention relates to insulation, and particularly though not exclusively to sound insulation for motor vehicles.
  • Insulation materials for motor vehicles have been known for many years. Such materials were typically natural fibres, and used for both heat and sound insulation. They usually comprised a thick mat which tended to limit heat transmission and deaden sound in a rather unscientific manner.
  • a typical mat comprising a dense foam aggregate and a heavy elastomeric layer has a mass per unit area of over 5 kg/m 2 , and the weight of insulation in a medium sized car may exceed 60 kg.
  • a further requirement is that recycling directives make the use of mixed materials problematic. It is therefore desirable to use lightweight sound insulating materials which are compatible with each other and the components to which they are attached.
  • a sheet insulation comprising a thick layer of substantially thermobonded fine fibres, and a relatively thin layer of melt blown fine fibres adhered thereto, said thin layer being substantially of polypropylene.
  • the thin layer may include polyester micro fibre.
  • the layers are preferably adhered directly to one another.
  • thermobonded fibre layer is preferably substantially of polyester and may be wholly of polyester or a mixture of polyester and other fibres, such as cotton wool, flax and other natural or synthetic materials.
  • the ratio of thickness of thick and thin layers is in the range 10:1 or less.
  • Fine fibres are generally in the range 0.5-5.0 decitex, and micro fibres in the range 0.01-0.1 decitex.
  • the thick layer comprises a mixture of basic and bonding fibres formed into a mat of substantially constant thickness by vertical lapping of a fibre stream.
  • the vertical lapping results in a layer having excellent resistance to loads perpendicular to the surface of the layer (generally in line with the vertical lapping), and has good recyclability.
  • the fibre stream is air laid.
  • the layers can be adhered in any manner sufficient to maintain them in contact, for example by adhesive, welding or inter engagement of surface level fibres.
  • the thick and thin layers may be of uniform density, or may be graded through the thickness thereof from low to high density.
  • the invention provides a composite sheet insulation comprising a uniform layer substantially of fine fibre air layered polyester, and a uniform layer substantially of micro fibre melt blown polypropylene adhered thereto.
  • the thickness ratio of polyester to polypropylene is preferably in the range 2-5:1 to 6:1, most preferably in the range 3 : 1 to 4: 1.
  • the uncompressed relative thicknesses are 20 mm and 6 mm
  • the fine fibre is about 1.75 decitex
  • the micro fibre has a diameter of 2 ⁇ m (about 0.03 decitex).
  • the fibres are applied as one or more single filaments.
  • One or both surfaces of the composite sheet may have a scrim layer adhered thereto, the scrim layer being relatively thin and being typically of polyester fibres, polypropylene fibres, a combination thereof, or another suitably compatible plastics fibre material.
  • the scrim layer may be of multiple materials and/or of several layers.
  • the scrim layer may for example comprise an oil repellent or fire retardant surface, or be used to improve the mechanical strength of the composite.
  • a scrim layer may also affect the performance of the insulation in a known manner, for example by improving high or low frequency attenuation according to the scrim material and/or binder.
  • a thin scrim layer may further be provided between the layers of the composite sheet.
  • An impervious layer and or a heat resistant layer may also be provided on one or both outer surfaces, or between the fibre layers.
  • the impervious material is for example polyethylene, and is provided to prevent transmission of water through the layers.
  • the heat resistant layer may for example be foil or an aluminised plastic.
  • a method of manufacturing a composite sheet insulation comprising the steps of: creating an air blown uniform layer of substantially thermobonded fine fibre; applying thereto a melt blown layer of substantially of polypropylene micro fibre; and providing that the respective layers are adhered.
  • the layers may be formed successively, so that one layer is formed directly on a substrate comprising the other layer.
  • the layers may comprise separate sheets adhered together in any suitable manner, for example by heat fusing using a temperature reactive polymer powder, or by using an adhesive.
  • the layers may be adhered substantially continually across the surface of the fibres, or in desired regions such as around the edge of an insulation mat.
  • the method may further include the step of adhering a thin scrim layer substantially of polypropylene fibres, polyester fibres, or a mixture thereof to one or both surfaces of the composite sheet.
  • the sheet insulation comprising a thick layer substantially of fine fibre air layered polypropylene, and a thin layer substantially of micro fibre melt blown polypropylene adhered thereto.
  • the thickness ratio of air layered and melt blown layers is preferably in the range 1-5:1 to 10: 1 , and most preferably about 8:1.
  • the uncompressed relative thicknesses are 26mm and 6mm, and the fine fibre is between 1.5 and 3.0 decitex.
  • the micro fibre is preferably about 0.03 decitex.
  • each layer includes from about 20 to about 35% uniformly distributed polyester fibre as binder to permit heat bonding of the layers to each other and to substrates such as ABS panels and carpets.
  • the insulation, or an outer surface thereof is coloured.
  • Coloured fibre is useful in vehicle insulation because it is less noticeable.
  • Polypropylene fibre is preferable because some grades are better able to retain loft over a longer period than polyester fibre, and thus maintain insulation properties.
  • a scrim layer or layers may be applied to one or both surfaces and/or to the interface, as previously described.
  • the insulation material may be coiled into a roll after manufacture thereof, and may be cut subsequently into suitable pre-forms, before or after the application of surface layers and/or surface treatments.
  • Fig.l is a cross section through insulation according to the invention
  • Fig.2 is a comparative graph of attenuation plotted against increasing f equency
  • Fig.3 is a cross-section through a second embodiment of the invention
  • Fig.4 is a comparative graph of attenuation plotted against increasing frequency.
  • a first embodiment of the invention comprises a two layer composite sheet material 10 comprising a layer of polypropylene 11, to which is bonded by any suitable method a layer of polyester 12.
  • the polyester layer 12 comprises fine fibres (typically 1.75 dtex) having a density of around 450g/m 2 and a free thickness of about 20 mm. It will be appreciated that such a material contains a significant volume of air voids and is thus somewhat resilient and compressible.
  • a suitable material is all carded, cross laid, thermally bonded PET.
  • the polypropylene layer 11 comprises melt blown micro fibre (typically 0.03 dtex) having a density of around 370g/m 2 and a free thickness of about 6 mm. This material also contains air voids and is resilient and compressible, though the density per unit thickness is much greater than the layer 12.
  • the two layers may be bonded together, by for example a heat sensitive powder coating, or may be directly formed one on the other so that a bond is created directly by the heat of the applied fibre.
  • a polyester/polypropylene composite of this kind has superior sound insulation characteristics in the audible range, as demonstrated by Fig. 2 in which the lower line represents a single layer of air layered polyester fine fibres, and the upper line represents a composite according to Fig. 1 of the same overall thickness.
  • the relative thickness of the polyester and polyethylene layers are of course possible. Generally, the preferred ratio is between 3 : 1 and 6:1.
  • a composite according to the invention can relatively easily be cut, shaped, moulded and welded to create a three-dimensional insulation panel adapted, for example, to fit against or around a motor vehicle component.
  • Welding may for example be by spot or seam weld according to design requirements; adhesives and/or sewing may be used as alternative forming techniques.
  • a composite according to the invention is suitable for welding to other components of plastic, in order to provide a unitary assembly.
  • two or three dimensional insulation may be attached to the rear of a vehicle instrument panel to reduce sound transmission.
  • the insulation also constitutes a dust and thermal shield, and that exposed components are covered so as to prevent contact or impact damage during transit.
  • a scrim layer is applied to one or both surfaces of the composite to improve handling characteristics, and to protect the fibres from abrasion damage.
  • a suitable scrim layer is of polyester or polypropylene, has a density of between 15 g/m 2 and 60 g/m 2 and is as thin as possible commensurate with mechanical effectiveness. The scrim layer may further improve high frequency attenuation.
  • the scrim may be applied as a sheet, and secured in any suitable manner, for example by a heat reactive powder.
  • the scrim may be applied to one or both surfaces of the polyester or polypropylene sheet during manufacture, or directly to the surface of the composite if manufactured in a unitary process.
  • a scrim layer may be incorporated between the polyester and polypropylene layers.
  • the polypropylene layer 11 is intended to be outermost when applied to a surface to be insulated.
  • An alternative embodiment incorporates a minor proportion of polyester micro fibre in the polypropylene micro fibre, for example in the ratio 30:70. Such a material is available under the trade mark 'Thinsulate 1 .
  • Figure 3 illustrates a second preferred embodiment comprising a mat 20 having a thin layer 21 and a thick layer 22.
  • An outer layer of scrim or a non-porous membrane such as EVA may be applied, but is not illustrated.
  • the thin layer comprises a layer of melt blown polypropylene 21 corresponding to the embodiment of Fig.l.
  • the thick layer 22 comprises a serpentine layer of non-woven fibres in which each vertical lap orientates the fibres generally perpendicular to the surface.
  • the layer 22 exhibits excellent resistance to surface loads, and has good recovery on removal of a load, typically an immediate recovery better than 90%.
  • Such a layer is thus ideally suited for carpet underlays and the like.
  • the fibres which comprise the layer 22 comprises thermobondable material, typically polyester, and other basic fibres of natural or synthetic materials.
  • the fibres of the thick layer are typically carded into a web after mixing, and the web is formed into a mat by vertical lapping during which the mat is thermobonded by, for example, passing through a hot air oven.
  • a suitable density of the thick layer 22 is in the range 300 g/m 2 to 1000 g/m 2 .
  • Figure 4 illustrates the improvement in performance over conventional noise insulation materials.
  • the audible range is indicated by 'a'.
  • Lines 'b' and 'c' respectively show the typical maximum and minimum performance of conventional noise insulation materials; these are relatively ineffective at low frequency, as illustrated.
  • the composite material according to Fig.3 is represented by line 'd', and shows a dramatic improvement at low frequencies, and sustained performance at high frequencies.
  • the material is much lighter than conventional sound deadening mats which are of the order of 5000 g/m 2 in density, and is of similar manufacturing cost.
  • the composite material is especially suitable for carpet underlay or the like, because of the excellent recovery from perpendicular loads.

Landscapes

  • Engineering & Computer Science (AREA)
  • Textile Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Acoustics & Sound (AREA)
  • Mechanical Engineering (AREA)
  • Multimedia (AREA)
  • General Physics & Mathematics (AREA)
  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Laminated Bodies (AREA)
  • Vehicle Interior And Exterior Ornaments, Soundproofing, And Insulation (AREA)

Abstract

A composite insulation material, particularly for said insulation, comprises a thick layer substantially of thermobonded fine fibre adhered to a thin layer substantially of polypropylene micro fibre. The composite material has low density, low mass per unit area, and improved said attenuation over the audible frequency range. Various external layers and/or coatings may be optionally applied.

Description

Composite Insulation
This invention relates to insulation, and particularly though not exclusively to sound insulation for motor vehicles.
Insulation materials for motor vehicles have been known for many years. Such materials were typically natural fibres, and used for both heat and sound insulation. They usually comprised a thick mat which tended to limit heat transmission and deaden sound in a rather unscientific manner.
More recently the insulating of unwanted sound has assumed great importance, especially in the manufacture of luxury vehicles. Particular combinations of material have been found to be highly effective in absorbing certain noise frequencies, and now a number of different materials are used to insulate sources of unwanted sound. The old methods of bulk deadening are ineffective, heavy and space hungry. Nevertheless, said deadening mats which rely on mass continue to be used because they are moderately effective. A typical mat comprising a dense foam aggregate and a heavy elastomeric layer has a mass per unit area of over 5 kg/m2, and the weight of insulation in a medium sized car may exceed 60 kg.
These heavy prior art insulations are very undesirable in view of current requirements to reduce weight and cost.
A further requirement is that recycling directives make the use of mixed materials problematic. It is therefore desirable to use lightweight sound insulating materials which are compatible with each other and the components to which they are attached.
According to the invention there is provided a sheet insulation comprising a thick layer of substantially thermobonded fine fibres, and a relatively thin layer of melt blown fine fibres adhered thereto, said thin layer being substantially of polypropylene. The thin layer may include polyester micro fibre. The layers are preferably adhered directly to one another.
The thermobonded fibre layer is preferably substantially of polyester and may be wholly of polyester or a mixture of polyester and other fibres, such as cotton wool, flax and other natural or synthetic materials.
Preferably the ratio of thickness of thick and thin layers is in the range 10:1 or less.
Fine fibres are generally in the range 0.5-5.0 decitex, and micro fibres in the range 0.01-0.1 decitex.
In a preferred embodiment the thick layer comprises a mixture of basic and bonding fibres formed into a mat of substantially constant thickness by vertical lapping of a fibre stream. The vertical lapping results in a layer having excellent resistance to loads perpendicular to the surface of the layer (generally in line with the vertical lapping), and has good recyclability. Preferably the fibre stream is air laid.
Typically elastic recovery of the layer, on application of orthogonal loads is better than 90%.
The layers can be adhered in any manner sufficient to maintain them in contact, for example by adhesive, welding or inter engagement of surface level fibres.
The thick and thin layers may be of uniform density, or may be graded through the thickness thereof from low to high density.
In a preferred embodiment the invention provides a composite sheet insulation comprising a uniform layer substantially of fine fibre air layered polyester, and a uniform layer substantially of micro fibre melt blown polypropylene adhered thereto. The thickness ratio of polyester to polypropylene is preferably in the range 2-5:1 to 6:1, most preferably in the range 3 : 1 to 4: 1. In one embodiment the uncompressed relative thicknesses are 20 mm and 6 mm, the fine fibre is about 1.75 decitex, and the micro fibre has a diameter of 2 μm (about 0.03 decitex). Preferably the fibres are applied as one or more single filaments.
One or both surfaces of the composite sheet may have a scrim layer adhered thereto, the scrim layer being relatively thin and being typically of polyester fibres, polypropylene fibres, a combination thereof, or another suitably compatible plastics fibre material. The scrim layer may be of multiple materials and/or of several layers. The scrim layer may for example comprise an oil repellent or fire retardant surface, or be used to improve the mechanical strength of the composite. A scrim layer may also affect the performance of the insulation in a known manner, for example by improving high or low frequency attenuation according to the scrim material and/or binder.
A thin scrim layer may further be provided between the layers of the composite sheet. An impervious layer and or a heat resistant layer may also be provided on one or both outer surfaces, or between the fibre layers. The impervious material is for example polyethylene, and is provided to prevent transmission of water through the layers. The heat resistant layer may for example be foil or an aluminised plastic.
According to another aspect of the invention there is provided a method of manufacturing a composite sheet insulation comprising the steps of: creating an air blown uniform layer of substantially thermobonded fine fibre; applying thereto a melt blown layer of substantially of polypropylene micro fibre; and providing that the respective layers are adhered.
The layers may be formed successively, so that one layer is formed directly on a substrate comprising the other layer.
Alternatively, the layers may comprise separate sheets adhered together in any suitable manner, for example by heat fusing using a temperature reactive polymer powder, or by using an adhesive. The layers may be adhered substantially continually across the surface of the fibres, or in desired regions such as around the edge of an insulation mat.
The method may further include the step of adhering a thin scrim layer substantially of polypropylene fibres, polyester fibres, or a mixture thereof to one or both surfaces of the composite sheet.
In another preferred embodiment the sheet insulation comprising a thick layer substantially of fine fibre air layered polypropylene, and a thin layer substantially of micro fibre melt blown polypropylene adhered thereto.
The thickness ratio of air layered and melt blown layers is preferably in the range 1-5:1 to 10: 1 , and most preferably about 8:1.
In one embodiment the uncompressed relative thicknesses are 26mm and 6mm, and the fine fibre is between 1.5 and 3.0 decitex. The micro fibre is preferably about 0.03 decitex.
In a preferred embodiment each layer includes from about 20 to about 35% uniformly distributed polyester fibre as binder to permit heat bonding of the layers to each other and to substrates such as ABS panels and carpets.
Preferably the insulation, or an outer surface thereof, is coloured. Coloured fibre is useful in vehicle insulation because it is less noticeable. Polypropylene fibre is preferable because some grades are better able to retain loft over a longer period than polyester fibre, and thus maintain insulation properties.
A scrim layer or layers may be applied to one or both surfaces and/or to the interface, as previously described. The insulation material may be coiled into a roll after manufacture thereof, and may be cut subsequently into suitable pre-forms, before or after the application of surface layers and/or surface treatments.
Other features of the invention will be apparent from the following description of preferred embodiments illustrated by reference to the accompanying drawings in which:
Fig.l is a cross section through insulation according to the invention; Fig.2 is a comparative graph of attenuation plotted against increasing f equency; Fig.3 is a cross-section through a second embodiment of the invention; and Fig.4 is a comparative graph of attenuation plotted against increasing frequency.
With reference to Fig. 1, a first embodiment of the invention comprises a two layer composite sheet material 10 comprising a layer of polypropylene 11, to which is bonded by any suitable method a layer of polyester 12.
The polyester layer 12 comprises fine fibres (typically 1.75 dtex) having a density of around 450g/m2 and a free thickness of about 20 mm. It will be appreciated that such a material contains a significant volume of air voids and is thus somewhat resilient and compressible. A suitable material is all carded, cross laid, thermally bonded PET.
The polypropylene layer 11 comprises melt blown micro fibre (typically 0.03 dtex) having a density of around 370g/m2 and a free thickness of about 6 mm. This material also contains air voids and is resilient and compressible, though the density per unit thickness is much greater than the layer 12.
The two layers may be bonded together, by for example a heat sensitive powder coating, or may be directly formed one on the other so that a bond is created directly by the heat of the applied fibre.
The extent and strength of the bond can be adjusted to suit requirements according to methods known in production of blown fibre mats. A polyester/polypropylene composite of this kind has superior sound insulation characteristics in the audible range, as demonstrated by Fig. 2 in which the lower line represents a single layer of air layered polyester fine fibres, and the upper line represents a composite according to Fig. 1 of the same overall thickness.
Variations in the relative thickness of the polyester and polyethylene layers are of course possible. Generally, the preferred ratio is between 3 : 1 and 6:1.
A composite according to the invention can relatively easily be cut, shaped, moulded and welded to create a three-dimensional insulation panel adapted, for example, to fit against or around a motor vehicle component. Welding may for example be by spot or seam weld according to design requirements; adhesives and/or sewing may be used as alternative forming techniques.
Furthermore a composite according to the invention is suitable for welding to other components of plastic, in order to provide a unitary assembly. Thus for example two or three dimensional insulation may be attached to the rear of a vehicle instrument panel to reduce sound transmission. A further advantage of this arrangement is that the insulation also constitutes a dust and thermal shield, and that exposed components are covered so as to prevent contact or impact damage during transit.
In a modification of the invention a scrim layer is applied to one or both surfaces of the composite to improve handling characteristics, and to protect the fibres from abrasion damage. A suitable scrim layer is of polyester or polypropylene, has a density of between 15 g/m2 and 60 g/m2 and is as thin as possible commensurate with mechanical effectiveness. The scrim layer may further improve high frequency attenuation.
The scrim may be applied as a sheet, and secured in any suitable manner, for example by a heat reactive powder. Alternatively the scrim may be applied to one or both surfaces of the polyester or polypropylene sheet during manufacture, or directly to the surface of the composite if manufactured in a unitary process. It will be appreciated that a scrim layer may be incorporated between the polyester and polypropylene layers. In use the polypropylene layer 11 is intended to be outermost when applied to a surface to be insulated.
An alternative embodiment incorporates a minor proportion of polyester micro fibre in the polypropylene micro fibre, for example in the ratio 30:70. Such a material is available under the trade mark 'Thinsulate1.
Figure 3 illustrates a second preferred embodiment comprising a mat 20 having a thin layer 21 and a thick layer 22. An outer layer of scrim or a non-porous membrane (such as EVA) may be applied, but is not illustrated.
The thin layer comprises a layer of melt blown polypropylene 21 corresponding to the embodiment of Fig.l. The thick layer 22 comprises a serpentine layer of non-woven fibres in which each vertical lap orientates the fibres generally perpendicular to the surface. As a result the layer 22 exhibits excellent resistance to surface loads, and has good recovery on removal of a load, typically an immediate recovery better than 90%. Such a layer is thus ideally suited for carpet underlays and the like.
The fibres which comprise the layer 22 comprises thermobondable material, typically polyester, and other basic fibres of natural or synthetic materials.
The fibres of the thick layer are typically carded into a web after mixing, and the web is formed into a mat by vertical lapping during which the mat is thermobonded by, for example, passing through a hot air oven.
A suitable density of the thick layer 22 is in the range 300 g/m2 to 1000 g/m2.
Figure 4 illustrates the improvement in performance over conventional noise insulation materials. The audible range is indicated by 'a'. Lines 'b' and 'c' respectively show the typical maximum and minimum performance of conventional noise insulation materials; these are relatively ineffective at low frequency, as illustrated. The composite material according to Fig.3 is represented by line 'd', and shows a dramatic improvement at low frequencies, and sustained performance at high frequencies. The material is much lighter than conventional sound deadening mats which are of the order of 5000 g/m2 in density, and is of similar manufacturing cost. The composite material is especially suitable for carpet underlay or the like, because of the excellent recovery from perpendicular loads.

Claims

Claims
1. Sheet insulation comprising a thick layer of thermobonded fine fibres and a relatively thin layer of melt blown micro fibres adhered thereto, said thin layer being substantially of polypropylene.
2. Sheet insulation according to claim 1 wherein said thick layer is substantially of polyester.
3. Sheet insulation according to claim 1 wherein said thick layer is substantially of polypropylene.
4. Sheet insulation according to any preceding claim wherein said layers are each of uniform density.
5. Sheet insulation according to any preceding claim wherein said layers are directly adhered.
6. Sheet insulation according to any preceding claim and further including a scrim layer adhered thereto.
7. Sheet insulation according to any preceding claim and having a thickness ratio of the layers in the range 1-5:1 to 10:1.
8. Sheet insulation according to any preceding claim wherein said fine fibres are in the range 0.5-5.0 decitex, and said micro fibres are in the range 0.01-0.1 decitex.
9. Sheet insulation according to any preceding claim wherein said thick layer is lapped orthogonally to the sheet surface thereof.
10. A method of manufacturing composite sheet insulation and comprising the steps of creating an air blown layer substantially of thermobonded fine fibre applying thereto a melt blown layer substantially of polypropylene micro fibre and providing that the respective layers are adhered.
EP04768960A 2003-10-22 2004-10-20 Composite insulation Withdrawn EP1677971A1 (en)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
GB0324657A GB0324657D0 (en) 2003-10-22 2003-10-22 Composite insulation
GB0400560A GB0400560D0 (en) 2004-01-12 2004-01-12 Composite insulation
GB0411897A GB0411897D0 (en) 2004-05-27 2004-05-27 Composite insulation
PCT/GB2004/004434 WO2005044553A1 (en) 2003-10-22 2004-10-20 Composite insulation

Publications (1)

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EP1677971A1 true EP1677971A1 (en) 2006-07-12

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GB (1) GB2407296B (en)
WO (1) WO2005044553A1 (en)

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GB2407296A (en) 2005-04-27
WO2005044553A1 (en) 2005-05-19
GB0423304D0 (en) 2004-11-24
GB2407296B (en) 2006-03-08

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