CA1282309C - Fibrous mat for hot moulding to moulded articles - Google Patents
Fibrous mat for hot moulding to moulded articlesInfo
- Publication number
- CA1282309C CA1282309C CA000543129A CA543129A CA1282309C CA 1282309 C CA1282309 C CA 1282309C CA 000543129 A CA000543129 A CA 000543129A CA 543129 A CA543129 A CA 543129A CA 1282309 C CA1282309 C CA 1282309C
- Authority
- CA
- Canada
- Prior art keywords
- fibres
- tangled
- layer
- binder
- 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.)
- Expired - Lifetime
Links
- 238000000465 moulding Methods 0.000 title claims abstract description 21
- 239000002344 surface layer Substances 0.000 claims abstract description 55
- 239000010410 layer Substances 0.000 claims abstract description 36
- 239000011230 binding agent Substances 0.000 claims abstract description 32
- 239000000835 fiber Substances 0.000 claims abstract description 27
- 230000009471 action Effects 0.000 claims abstract description 7
- 239000012528 membrane Substances 0.000 claims abstract description 5
- 239000007822 coupling agent Substances 0.000 claims description 9
- 239000004033 plastic Substances 0.000 claims description 3
- 229920003023 plastic Polymers 0.000 claims description 3
- 239000004890 Hydrophobing Agent Substances 0.000 claims description 2
- 238000009826 distribution Methods 0.000 claims description 2
- 239000003365 glass fiber Substances 0.000 claims description 2
- 229920001187 thermosetting polymer Polymers 0.000 description 8
- 238000000034 method Methods 0.000 description 7
- 238000010521 absorption reaction Methods 0.000 description 6
- 238000000576 coating method Methods 0.000 description 6
- 230000035699 permeability Effects 0.000 description 6
- 239000000463 material Substances 0.000 description 5
- 230000008569 process Effects 0.000 description 5
- 239000007789 gas Substances 0.000 description 4
- 238000004519 manufacturing process Methods 0.000 description 4
- 238000007493 shaping process Methods 0.000 description 4
- 229920002522 Wood fibre Polymers 0.000 description 3
- 238000004026 adhesive bonding Methods 0.000 description 3
- 238000005452 bending Methods 0.000 description 3
- 239000011248 coating agent Substances 0.000 description 3
- 229910052500 inorganic mineral Inorganic materials 0.000 description 3
- 239000011707 mineral Substances 0.000 description 3
- 238000007789 sealing Methods 0.000 description 3
- 229920001169 thermoplastic Polymers 0.000 description 3
- 239000004416 thermosoftening plastic Substances 0.000 description 3
- 206010042674 Swelling Diseases 0.000 description 2
- 230000002745 absorbent Effects 0.000 description 2
- 239000002250 absorbent Substances 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000004745 nonwoven fabric Substances 0.000 description 2
- 239000000047 product Substances 0.000 description 2
- 229920005989 resin Polymers 0.000 description 2
- 239000011347 resin Substances 0.000 description 2
- 230000000717 retained effect Effects 0.000 description 2
- 238000004381 surface treatment Methods 0.000 description 2
- 230000008961 swelling Effects 0.000 description 2
- 239000000853 adhesive Substances 0.000 description 1
- 230000001070 adhesive effect Effects 0.000 description 1
- 230000009172 bursting Effects 0.000 description 1
- 229920002678 cellulose Polymers 0.000 description 1
- 239000001913 cellulose Substances 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 239000007795 chemical reaction product Substances 0.000 description 1
- 230000006835 compression Effects 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 230000008094 contradictory effect Effects 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 230000008020 evaporation Effects 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- 230000001771 impaired effect Effects 0.000 description 1
- 239000012939 laminating adhesive Substances 0.000 description 1
- 238000003475 lamination Methods 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 230000005012 migration Effects 0.000 description 1
- 238000013508 migration Methods 0.000 description 1
- 238000007639 printing Methods 0.000 description 1
- 230000002035 prolonged effect Effects 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 230000003746 surface roughness Effects 0.000 description 1
- 229920003002 synthetic resin Polymers 0.000 description 1
- 239000000057 synthetic resin Substances 0.000 description 1
- 238000011282 treatment Methods 0.000 description 1
- 239000002966 varnish Substances 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C70/00—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts
- B29C70/04—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts comprising reinforcements only, e.g. self-reinforcing plastics
- B29C70/06—Fibrous reinforcements only
- B29C70/08—Fibrous reinforcements only comprising combinations of different forms of fibrous reinforcements incorporated in matrix material, forming one or more layers, and with or without non-reinforced layers
-
- 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
- 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
- B32B5/02—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 structural features of a fibrous or filamentary layer
-
- 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
- B32B5/28—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 impregnated with or embedded in a plastic substance
-
- 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
- B32B2250/00—Layers arrangement
- B32B2250/40—Symmetrical or sandwich layers, e.g. ABA, ABCBA, ABCCBA
-
- 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
- B32B2307/50—Properties of the layers or laminate having particular mechanical properties
- B32B2307/54—Yield strength; Tensile strength
-
- 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
- B32B2471/00—Floor coverings
- B32B2471/04—Mats
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Composite Materials (AREA)
- Mechanical Engineering (AREA)
- Nonwoven Fabrics (AREA)
- Laminated Bodies (AREA)
Abstract
ABSTRACT
Fibrous mat for hot moulding to moulded articles.
A fibrous mat for hot moulding to moulded articles is described. This comprises a firm sandwich or union formed from a central tangled fibre layer subject to the action of a binder and in each case one heatproof, binder-containing tangled fibre surface layer on the two surfaces of the central layer. The surface layer, at least of the unmoulded mat, has a greater tensile strength than the central layer and in the case of the mat moulded to the moulded article is in the form of a moisture-regulating membrane. The weight per unit area of the binder-free portion of the heatproof tangled fibres of the surface layer is 10 to 100 g/m and the individual tangled fibres are coated in fibre-envel-oping manner with 100 to 200% by weight, based on said weight per unit area, of a binder already precondensed prior to the moulding of the fibrous mat, in such a way that the diameter ratio between the coated and the uncoated tangled fibres of the surface layer is between 1.4 and 1.75.
Fibrous mat for hot moulding to moulded articles.
A fibrous mat for hot moulding to moulded articles is described. This comprises a firm sandwich or union formed from a central tangled fibre layer subject to the action of a binder and in each case one heatproof, binder-containing tangled fibre surface layer on the two surfaces of the central layer. The surface layer, at least of the unmoulded mat, has a greater tensile strength than the central layer and in the case of the mat moulded to the moulded article is in the form of a moisture-regulating membrane. The weight per unit area of the binder-free portion of the heatproof tangled fibres of the surface layer is 10 to 100 g/m and the individual tangled fibres are coated in fibre-envel-oping manner with 100 to 200% by weight, based on said weight per unit area, of a binder already precondensed prior to the moulding of the fibrous mat, in such a way that the diameter ratio between the coated and the uncoated tangled fibres of the surface layer is between 1.4 and 1.75.
Description
Fibrous mat for hot moulding to moulded articles The invention relates to a fibrous mat for hot moulding to moulded articles.
Multilayer fibrous mats, particularly those with special surface coatings are known. In particular, a multilayer fibrous mat for producing moulded articles in a press mould by exposing the fibrous mat to pressure and elevated temperature and formed from cellulose, lignocellulose or similar fibres is known, whose two surface layers are also formed from a tangled fibre fleece and provided with at least a proportion of thermosetting synthetic resins. The thermoplastic binder-containing central tangled fibre layer and the two outer surface layers provided with thermosetting binders are produced here by the layerwise placing of the mat material on a conveyor belt and in the state moulded to moulded articles are simultaneously present in the form of a firm union or sandwich o~ said multi-layer arrangement (P 32 33 385).
However, it has been found that the additional gluing of the surface layers with a thermosetting material which takes place in this known process according to the partial flow principle during the production of the mat and moulding is at least partly ~5 absorbed by the absorbent central layer, which is dis-advantageous in that in such known three-layer mats, the disadvantage thereof, i.e. the thermal and mechanical surface treatment, is lost again through the thermoset-ting binder used therein undesirably migrating into the central layer. This effect can only be compensated by the addition of larger thermosetting binder quantities to the surface layer fibres, which would make the desi-red end product much more expensive.
Another known process for producing insulating plates, using mineral fibres as a basis~ can be advan-tageously realized in that the non-woven fabric is 3~:~
applied to an also moving surface ~ibre fleece during production, so that during compression the insulating plate is joined to the fleece carrier (DE-OS 28 53 316).
In product-dependent manner, particular attention has long been paid to the processing of wood fibre materials of the present type and also non-woven fabrics comprising natural or mineral fibres and the like to plates or three-dimensionally shaped products~ The nature of the surface treatment can range from the lo simplest resin enrichment, primers or varnishes to printing and lining with films or lamination with plastics and the like.
The application of surface layers to supporting central layers, either in the form of special surface layer gluing treatments, additional lining material or the like, generally leads to the desired improved sur-face characteristics, but is generally also linked with a sealing of the surface in the sense of being imperme-able e.g. for gases or liquids, which can be disadvanta-~ geous in many cases and particularly for the processing of such mats to moulded articles excludes certain pro-cedures or other technically simply performable process steps. Reference is made in exemplified manner in this connection to the production-favorable vacuum deep draw-ing process for co-ordinating such moulded articles with thermoplastic films, as well as to certain characteris-tics of completely moulded parts, which are considered to be more advantageous when used as linings in pas-senger areas of motor vehicles if they ensure a certain air permeability and moisture absorption, which can significantly improve the climatic conditions within such passenger areas.
The problem of the present invention is therefore to so further develop a three-layer fibrous mat of the aforementioned type that, in the case of minimum use of higher-grade materials both on the fibre side and on the binder side and with minimum manufacturing expenditure contributes to the provision of moulded articles, whose surface is both insensitive to wetness and breaths mois-ture and whose thermal, chemical and physical charac-teristics can compete with those of comparable surface-sealing coatings or coverings.
According to one embodiment of this invention the invention provides a fibrous mat for hot moulding to moulding to moulded articles, comprising a central tangled fibre layer treated with a binder and in each case one heatproof, binder-containing tangled fibre surface layer Oll the two surfaces of the central layer, the surface layers forming a firm sandwich with the central layer, characterized in that the surface layer of at least the unmoulded mat has a higher tensile strength than the central layer and that the surface layer in the mat moulded to the moulded article is constructed as a moisture-regulating membrane, the weight per unit area of the binder-free portion of the heatproof tangled fibres of the surface layer being between 10 to about 100 g/m2 and the individual tangled fibres with a proportion of about 100 to about 200% by weight, based on this weight per unit area, are coated in fibre-enveloping manner with a binder already pre-~5 condensed prior to the moulding of the fibrous mat, so that the diameter ratio between the coated and uncoated tangled fibres of the surface layer is between 1.4 and 1.75.
In a preferred form of the fibrous mat, the mat is characterized in that between the heatproof, binder-containing tangled fibre surface layer on the surfaces of the central tangled fiber layer for the firm reci-procal sandwich of the layers is provided a heat-resis-tant coupling agent in point, line, grid or grating-like distribution, the sandwich surface portions not subject to the action of the coupling agent being more than 15%
of the total surface.
s3 Thus, according to one preferred embodiment of this invention, the invention is based on surface layers fibres which can be substantially of a random nature, e.g. can be in the form of organic or inorganic fibres and have a natural or synthetic origin, whereby no requirements are made with respect to their moisture absorptivity or sensitivity to other environmental influences. In addition, they need not be inexpensive to manufacture, because only small amounts are used compared with the supporting central layer (weight per unit area of the total mat, as a function of applica-tion, 1000 to 2000 g/m2).
The presently required, high-grade surface seallng, particularly with respect to high thermal stability, is ensured by coating the adequate length of the present individual fibres of the tangled fibre surface layers, preferably in the form of staple fibres, with a thermo-setting binder in a given ratio of the fibre diameter to the binder coating. Simultaneously it is possible to ensure gas permeability and a moisture permeability determinable by the surface density of the surface layer on the finished moulding, because the individual fibres coated with a thermosetting binder within the tangled fibre fleece give between them homogeneously distribu-ted, screen-like passages. Due to the fact that the fibre-enveloping binder is partly precondensed, there is no migration of binder into the central, relatively absorbent tangled fibre layer, which is subject to the action of the thermoplastic binder, so that there is no need to thin the same in the surface area and its posi-tive characteristics have their full effect.
As a result of precondensing, the viscosity of the thermosetting binder in the surface layers can also be previously defined for the moulding process. The quasi-moisture absorption possibility of the central tangled fibre layer through the surface layers acting in 3 ~3 membrane-like manner can be precisely "dosed'1 and adjus-ted in optimum manner to the individual application.
The heat-resistant enveloping of the surface layer ~ibres only seals the individual fibres in moisture-tight manner, but not the tangled fibre fleece formed therefrom. During molding, the fibres are not partly dissolved again and do not come into direct contact with the hot surface of the mould parts. They retain their predetermined strength characteristics substantially lo independently of the parameters for optimum moulding.
The precondensed binders used for enveloping the indi-vidual fibres of the surface layers have a viscosity such that there is not a complete sealing of the tangled fibre layer, such as is the case with film linings. The moisture-regulating membrane action of the surface layers equals out high temperature fluctuations and moisture changes within the passenger area of cars lined with moulded articles made from such multilayer mats in a manner pleasant for the occupants. It has surpris-ingly been found in this connection that even if with prolonged wetness action, moisture absorption in the central layer, e.g. of lignocellulose fibres, has taken place to a relatively high extent, the thickness swel-ling of the moulded article is approximately one decimal power lower than with comparable moulded articles which, in place of the membrane-like surface layers, either carry film seals or are otherwise completely air and moisture-tight as a result of binders or coatings.
The moisture-regulating membrane, even if the fibres of the central layer are sensitive to moisture, makes it possible to so regulate and keep low the moisture absorption or characteristics of the moulded article, that there are no dimensional changes due to swelling if moisture occurs in superfluity on the moul-ded article. Due to the fact that the original charac-teristics of the individual, completely sealed fibres of O~
the surface layer fleeces are fully retained and in par-ticular due to the fact that the high-grade thermoset-ting gluing of said surface layers remains almost com-pletely therein and does not partly diffuse into the central layer, the moulded articles have excellent strength characteristics and in particular a high impact strength, as well as bending strength and bursting limit values, which are otherwise only attainable with much higher thermosetting binder proportions.
Following the moulding of the surface layers, together with the tangled fibre layer to give moulded articles, said surface layers have a microporosity which, in per se contradictory manner and despite a relatively high absorption capaclty for moisture within the moulded article, ensures the aforementioned highly stable accuracy to size of the moulded article.
The precondensed, thermosetting binder of the sur-face layer joins the fibres thereof at their crossing points, so that the surface layer in ~0 2g 3~
the unmoulded state can be given a higher tensile strength than the central layer. Thus, during the moulding of the mat to the moulded article, the shaping or deforming process i9 stabili~ed, particularly if, such as e.g. is the case with wood fibre mats, the mat is plast-icized by evaporation during which the thermoplastically bound fibresof the central layer largely lose their binding, whereas the binding characteristics of the precondensate of the surface layers is largely retained. The permeability of the surface layer makes it posslble, to retain conventional technology for wood fibre mats and namely in 10 the case of extended shaping possibilities, improved moulded article characteristics and due to the stabiliæing action of the surface layers on the shaping process even with reduced wastage.
It is advantageous to use plastic fibres for the surface layer fibres which have a softening point above 200 C~ Unlike many mineral fibres, such fibres have high lateral strength characteristics and are not brittle, even at low temperatures, so that moulded articles with high impact strength in a very wide temperature range are obtained. If increased demands are made on the strength and bending resistance of the parts, it may be appropriate for the surface layers to be at least partly formed from glass fibres, apart from ceramic fibres.
The bending strength and impact strength of the moulded articles can also be improved if at least part of the fibres of the surface layer are natural fibres. As natural fibres generally have an increased moisture absorption during storage, it is appropriate to pretreat them with hydrophobing agents prior to binder addition and precondensation thereof. Improved strength characteristics of the moulded articles can in particular be obtained if the fibres forming the tangled fibre fleeces of the surface layers, are on a~erage longer than 20 mm.
On moulding the fibrous mats to moulded articles, the tangled fibres of the surface layers are further bound and strengthened by the precon-densed resin at the fibre crossing points to the extent that this has not taken place through the precondensation and are consequently able to absorb tensile forces to an even greater extent and optionally ~ 3~30~3 improve the mechanical characteristics of the moulded articlesO
Yirtually all known fibre types can be used for producing the central layers, if the temperature at which the fibrous mat is moulded to moulded articles can be borne by the fibres without suffering damage ~his also applies with respect to the binders used in the central layer. Generally lower demands are made on the quality of the fibres and binder of the central layer than for comparable known fibrous mats, particularly because the moisture-regulating characteristics of the surface layers also permit the use of more moisture sensitive fibres.
The increased viscosity of the fibre-enveloping binder during final moulding not only produces the desired microporosity, but also a fibre diameter-corresponding surface roughness which, in conjunction with the microporosity, ensures a better adhesion of surface finishes and laminating adhesives.
lS Particularly if heat-resistant, crosslinked coupling agents are used between the surface layers and the central fibrous fleece mat, the des-ired gas permeability can suffer. This can be obviated in that said coupling agent is applied in the form of point, line, screen or grating-like patterns, the surface proportion not wetted by the coupling agent `_20 being greater than 15%. This makes it possible to achie~e a satisfactory gas permeability of the coupling agent layer, without the heat-resistant, surface adhesion of the surface layers being impaired. Thus, tensile forces during shaping can be transEerred between the surface layers and the central fibrous fleece mat. The pattern-like coating with coupling agent can e.g. be carried out without difficulty by perse known pressure rollers or other prior art means, such as pressure screens and the like.
The "lattice constants" of the adhesive pattern can be between a few milLimetres and a few centimetres, as a function of the fibre type, length and deformation problem.
.
. ~
Multilayer fibrous mats, particularly those with special surface coatings are known. In particular, a multilayer fibrous mat for producing moulded articles in a press mould by exposing the fibrous mat to pressure and elevated temperature and formed from cellulose, lignocellulose or similar fibres is known, whose two surface layers are also formed from a tangled fibre fleece and provided with at least a proportion of thermosetting synthetic resins. The thermoplastic binder-containing central tangled fibre layer and the two outer surface layers provided with thermosetting binders are produced here by the layerwise placing of the mat material on a conveyor belt and in the state moulded to moulded articles are simultaneously present in the form of a firm union or sandwich o~ said multi-layer arrangement (P 32 33 385).
However, it has been found that the additional gluing of the surface layers with a thermosetting material which takes place in this known process according to the partial flow principle during the production of the mat and moulding is at least partly ~5 absorbed by the absorbent central layer, which is dis-advantageous in that in such known three-layer mats, the disadvantage thereof, i.e. the thermal and mechanical surface treatment, is lost again through the thermoset-ting binder used therein undesirably migrating into the central layer. This effect can only be compensated by the addition of larger thermosetting binder quantities to the surface layer fibres, which would make the desi-red end product much more expensive.
Another known process for producing insulating plates, using mineral fibres as a basis~ can be advan-tageously realized in that the non-woven fabric is 3~:~
applied to an also moving surface ~ibre fleece during production, so that during compression the insulating plate is joined to the fleece carrier (DE-OS 28 53 316).
In product-dependent manner, particular attention has long been paid to the processing of wood fibre materials of the present type and also non-woven fabrics comprising natural or mineral fibres and the like to plates or three-dimensionally shaped products~ The nature of the surface treatment can range from the lo simplest resin enrichment, primers or varnishes to printing and lining with films or lamination with plastics and the like.
The application of surface layers to supporting central layers, either in the form of special surface layer gluing treatments, additional lining material or the like, generally leads to the desired improved sur-face characteristics, but is generally also linked with a sealing of the surface in the sense of being imperme-able e.g. for gases or liquids, which can be disadvanta-~ geous in many cases and particularly for the processing of such mats to moulded articles excludes certain pro-cedures or other technically simply performable process steps. Reference is made in exemplified manner in this connection to the production-favorable vacuum deep draw-ing process for co-ordinating such moulded articles with thermoplastic films, as well as to certain characteris-tics of completely moulded parts, which are considered to be more advantageous when used as linings in pas-senger areas of motor vehicles if they ensure a certain air permeability and moisture absorption, which can significantly improve the climatic conditions within such passenger areas.
The problem of the present invention is therefore to so further develop a three-layer fibrous mat of the aforementioned type that, in the case of minimum use of higher-grade materials both on the fibre side and on the binder side and with minimum manufacturing expenditure contributes to the provision of moulded articles, whose surface is both insensitive to wetness and breaths mois-ture and whose thermal, chemical and physical charac-teristics can compete with those of comparable surface-sealing coatings or coverings.
According to one embodiment of this invention the invention provides a fibrous mat for hot moulding to moulding to moulded articles, comprising a central tangled fibre layer treated with a binder and in each case one heatproof, binder-containing tangled fibre surface layer Oll the two surfaces of the central layer, the surface layers forming a firm sandwich with the central layer, characterized in that the surface layer of at least the unmoulded mat has a higher tensile strength than the central layer and that the surface layer in the mat moulded to the moulded article is constructed as a moisture-regulating membrane, the weight per unit area of the binder-free portion of the heatproof tangled fibres of the surface layer being between 10 to about 100 g/m2 and the individual tangled fibres with a proportion of about 100 to about 200% by weight, based on this weight per unit area, are coated in fibre-enveloping manner with a binder already pre-~5 condensed prior to the moulding of the fibrous mat, so that the diameter ratio between the coated and uncoated tangled fibres of the surface layer is between 1.4 and 1.75.
In a preferred form of the fibrous mat, the mat is characterized in that between the heatproof, binder-containing tangled fibre surface layer on the surfaces of the central tangled fiber layer for the firm reci-procal sandwich of the layers is provided a heat-resis-tant coupling agent in point, line, grid or grating-like distribution, the sandwich surface portions not subject to the action of the coupling agent being more than 15%
of the total surface.
s3 Thus, according to one preferred embodiment of this invention, the invention is based on surface layers fibres which can be substantially of a random nature, e.g. can be in the form of organic or inorganic fibres and have a natural or synthetic origin, whereby no requirements are made with respect to their moisture absorptivity or sensitivity to other environmental influences. In addition, they need not be inexpensive to manufacture, because only small amounts are used compared with the supporting central layer (weight per unit area of the total mat, as a function of applica-tion, 1000 to 2000 g/m2).
The presently required, high-grade surface seallng, particularly with respect to high thermal stability, is ensured by coating the adequate length of the present individual fibres of the tangled fibre surface layers, preferably in the form of staple fibres, with a thermo-setting binder in a given ratio of the fibre diameter to the binder coating. Simultaneously it is possible to ensure gas permeability and a moisture permeability determinable by the surface density of the surface layer on the finished moulding, because the individual fibres coated with a thermosetting binder within the tangled fibre fleece give between them homogeneously distribu-ted, screen-like passages. Due to the fact that the fibre-enveloping binder is partly precondensed, there is no migration of binder into the central, relatively absorbent tangled fibre layer, which is subject to the action of the thermoplastic binder, so that there is no need to thin the same in the surface area and its posi-tive characteristics have their full effect.
As a result of precondensing, the viscosity of the thermosetting binder in the surface layers can also be previously defined for the moulding process. The quasi-moisture absorption possibility of the central tangled fibre layer through the surface layers acting in 3 ~3 membrane-like manner can be precisely "dosed'1 and adjus-ted in optimum manner to the individual application.
The heat-resistant enveloping of the surface layer ~ibres only seals the individual fibres in moisture-tight manner, but not the tangled fibre fleece formed therefrom. During molding, the fibres are not partly dissolved again and do not come into direct contact with the hot surface of the mould parts. They retain their predetermined strength characteristics substantially lo independently of the parameters for optimum moulding.
The precondensed binders used for enveloping the indi-vidual fibres of the surface layers have a viscosity such that there is not a complete sealing of the tangled fibre layer, such as is the case with film linings. The moisture-regulating membrane action of the surface layers equals out high temperature fluctuations and moisture changes within the passenger area of cars lined with moulded articles made from such multilayer mats in a manner pleasant for the occupants. It has surpris-ingly been found in this connection that even if with prolonged wetness action, moisture absorption in the central layer, e.g. of lignocellulose fibres, has taken place to a relatively high extent, the thickness swel-ling of the moulded article is approximately one decimal power lower than with comparable moulded articles which, in place of the membrane-like surface layers, either carry film seals or are otherwise completely air and moisture-tight as a result of binders or coatings.
The moisture-regulating membrane, even if the fibres of the central layer are sensitive to moisture, makes it possible to so regulate and keep low the moisture absorption or characteristics of the moulded article, that there are no dimensional changes due to swelling if moisture occurs in superfluity on the moul-ded article. Due to the fact that the original charac-teristics of the individual, completely sealed fibres of O~
the surface layer fleeces are fully retained and in par-ticular due to the fact that the high-grade thermoset-ting gluing of said surface layers remains almost com-pletely therein and does not partly diffuse into the central layer, the moulded articles have excellent strength characteristics and in particular a high impact strength, as well as bending strength and bursting limit values, which are otherwise only attainable with much higher thermosetting binder proportions.
Following the moulding of the surface layers, together with the tangled fibre layer to give moulded articles, said surface layers have a microporosity which, in per se contradictory manner and despite a relatively high absorption capaclty for moisture within the moulded article, ensures the aforementioned highly stable accuracy to size of the moulded article.
The precondensed, thermosetting binder of the sur-face layer joins the fibres thereof at their crossing points, so that the surface layer in ~0 2g 3~
the unmoulded state can be given a higher tensile strength than the central layer. Thus, during the moulding of the mat to the moulded article, the shaping or deforming process i9 stabili~ed, particularly if, such as e.g. is the case with wood fibre mats, the mat is plast-icized by evaporation during which the thermoplastically bound fibresof the central layer largely lose their binding, whereas the binding characteristics of the precondensate of the surface layers is largely retained. The permeability of the surface layer makes it posslble, to retain conventional technology for wood fibre mats and namely in 10 the case of extended shaping possibilities, improved moulded article characteristics and due to the stabiliæing action of the surface layers on the shaping process even with reduced wastage.
It is advantageous to use plastic fibres for the surface layer fibres which have a softening point above 200 C~ Unlike many mineral fibres, such fibres have high lateral strength characteristics and are not brittle, even at low temperatures, so that moulded articles with high impact strength in a very wide temperature range are obtained. If increased demands are made on the strength and bending resistance of the parts, it may be appropriate for the surface layers to be at least partly formed from glass fibres, apart from ceramic fibres.
The bending strength and impact strength of the moulded articles can also be improved if at least part of the fibres of the surface layer are natural fibres. As natural fibres generally have an increased moisture absorption during storage, it is appropriate to pretreat them with hydrophobing agents prior to binder addition and precondensation thereof. Improved strength characteristics of the moulded articles can in particular be obtained if the fibres forming the tangled fibre fleeces of the surface layers, are on a~erage longer than 20 mm.
On moulding the fibrous mats to moulded articles, the tangled fibres of the surface layers are further bound and strengthened by the precon-densed resin at the fibre crossing points to the extent that this has not taken place through the precondensation and are consequently able to absorb tensile forces to an even greater extent and optionally ~ 3~30~3 improve the mechanical characteristics of the moulded articlesO
Yirtually all known fibre types can be used for producing the central layers, if the temperature at which the fibrous mat is moulded to moulded articles can be borne by the fibres without suffering damage ~his also applies with respect to the binders used in the central layer. Generally lower demands are made on the quality of the fibres and binder of the central layer than for comparable known fibrous mats, particularly because the moisture-regulating characteristics of the surface layers also permit the use of more moisture sensitive fibres.
The increased viscosity of the fibre-enveloping binder during final moulding not only produces the desired microporosity, but also a fibre diameter-corresponding surface roughness which, in conjunction with the microporosity, ensures a better adhesion of surface finishes and laminating adhesives.
lS Particularly if heat-resistant, crosslinked coupling agents are used between the surface layers and the central fibrous fleece mat, the des-ired gas permeability can suffer. This can be obviated in that said coupling agent is applied in the form of point, line, screen or grating-like patterns, the surface proportion not wetted by the coupling agent `_20 being greater than 15%. This makes it possible to achie~e a satisfactory gas permeability of the coupling agent layer, without the heat-resistant, surface adhesion of the surface layers being impaired. Thus, tensile forces during shaping can be transEerred between the surface layers and the central fibrous fleece mat. The pattern-like coating with coupling agent can e.g. be carried out without difficulty by perse known pressure rollers or other prior art means, such as pressure screens and the like.
The "lattice constants" of the adhesive pattern can be between a few milLimetres and a few centimetres, as a function of the fibre type, length and deformation problem.
.
. ~
Claims (6)
EXCLUSIVE PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED
AS FOLLOWS:
1. A fibrous mat for hot moulding to moulding to moulded articles, comprising a central tangled fibre layer treated with a binder and in each case one heatproof, binder-containing tangled fibre surface layer on the two surfaces of the central layer, the surface layers forming a firm sandwich with the central layer, characterized in that the surface layer of at least the unmoulded mat has a higher tensile strength than the central layer and that the surface layer in the mat moulded to the moulded article is constructed as a moisture-regulating membrane, the weight per unit area of the binder-free portion of the heatproof tangled fibres of the surface layer being 10 to 100 g/m2 and the individual tangled fibres with a proportion of 100 to 200% by weight, based on this weight per unit area, are coated in fibre-enveloping manner with a binder already precondensed prior to the moulding of the fibrous mat, so that the diameter ratio between the coated and uncoated tangled fibres of the surface layer is between 1.4 and 1.75.
2. Fibrous mat according to claim 1, characterized in that the fibres of the surface layers comprise plastics, whose softening point is about 200 C.
3. Fibrous mat according to claim 1, characterized in that the fibres of the surface layers are at least in part glass fibres.
4. Fibrous mat according to claim 1, characterized in that the fibres of the surface layer are at least in-part natural fibres pretreaded with hydrophobing agents prior to adding the binder and precondensation.
5. Fibrous mat according to at least one of the claims 1 to 4, characterized in that the average length of the fibres forming the tangled fibre fleeces of the surface layers is greater than 20 mm.
6. Fibrous mat, according to claim 1, characterized in that between the heatproof, binder-containing tangled fibre surface layer on the surfaces of the central tangled fibre layer for the firm reciprocal sandwich of the layers is provided a heat-resistant coupling agent in point, line, grid or grating-like distribution, the sandwich surface portions not subject to the action of the coupling agent being more than 15% of the total surface.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DEP3629891.3 | 1986-08-29 | ||
| DE19863629891 DE3629891A1 (en) | 1986-08-29 | 1986-08-29 | FIBER MAT FOR HOT COMPRESSING TO MOLD |
| DEP3721664.3 | 1987-06-26 | ||
| DE19873721664 DE3721664A1 (en) | 1986-08-29 | 1987-06-26 | FIBER MAT FOR HOT COMPRESSING TO MOLD |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1282309C true CA1282309C (en) | 1991-04-02 |
Family
ID=25847145
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000543129A Expired - Lifetime CA1282309C (en) | 1986-08-29 | 1987-07-28 | Fibrous mat for hot moulding to moulded articles |
Country Status (7)
| Country | Link |
|---|---|
| JP (1) | JP2539843B2 (en) |
| CA (1) | CA1282309C (en) |
| DE (1) | DE3721664A1 (en) |
| ES (1) | ES2004797A6 (en) |
| FR (1) | FR2603310B1 (en) |
| GB (1) | GB2194485B (en) |
| IT (1) | IT1225874B (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5980702A (en) * | 1982-10-29 | 1984-05-10 | Sumitomo Metal Ind Ltd | Production of alloy steel powder |
| DE3935689A1 (en) * | 1989-10-26 | 1991-05-02 | Roeder & Spengler Stanz | Car interior linings prodn. - by depositing thermoplastic powder on two layers combining with two other layers, cutting to sheets and hot pressing |
| DE4034915A1 (en) * | 1990-11-04 | 1992-05-07 | Kinkel Werner Helmut | METHOD FOR PRODUCING SANDWICH-LIKE TEXTILES FIBER STRUCTURES IN THE FORM OF PLATES AND MOLDED PARTS |
| DE4438764A1 (en) * | 1994-10-29 | 1996-05-02 | Hp Chemie Pelzer Res & Dev | Cheap, lightweight, noise-absorbing laminate for use in automobiles |
| DE10153875A1 (en) * | 2001-11-02 | 2003-05-15 | Bpw Bergische Achsen Kg | Component in an elongated construction made of a fiber-plastic composite |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS6030772B2 (en) * | 1975-05-30 | 1985-07-18 | 宏之 金井 | Method for manufacturing multilayer bulky nonwoven fabric |
| JPS55100155A (en) * | 1979-01-26 | 1980-07-30 | Toho Beslon Co | Thermal incorporating laminated structure |
| DE3120459A1 (en) * | 1981-05-22 | 1982-12-09 | Lentia GmbH Chem. u. pharm. Erzeugnisse - Industriebedarf, 8000 München | Readily adhesive and foamable laminate |
| DE3233385C2 (en) * | 1981-10-02 | 1984-05-17 | Günter Hans 1000 Berlin Kiss | Multi-layer fiber composite and process for its manufacture |
| JPS5876561A (en) * | 1981-10-02 | 1983-05-09 | ギユンタ−・ハ−・キス | Multilayer fiber mat and production thereof |
-
1987
- 1987-06-26 DE DE19873721664 patent/DE3721664A1/en active Granted
- 1987-07-20 GB GB8717104A patent/GB2194485B/en not_active Expired - Lifetime
- 1987-07-28 CA CA000543129A patent/CA1282309C/en not_active Expired - Lifetime
- 1987-08-10 ES ES8702356A patent/ES2004797A6/en not_active Expired
- 1987-08-24 JP JP62210020A patent/JP2539843B2/en not_active Expired - Lifetime
- 1987-08-26 IT IT8721717A patent/IT1225874B/en active
- 1987-08-27 FR FR8712108A patent/FR2603310B1/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| FR2603310A1 (en) | 1988-03-04 |
| GB2194485A (en) | 1988-03-09 |
| JPS6366361A (en) | 1988-03-25 |
| ES2004797A6 (en) | 1989-02-01 |
| FR2603310B1 (en) | 1994-04-01 |
| IT8721717A0 (en) | 1987-08-26 |
| IT1225874B (en) | 1990-12-07 |
| DE3721664A1 (en) | 1989-01-19 |
| JP2539843B2 (en) | 1996-10-02 |
| GB2194485B (en) | 1990-07-04 |
| GB8717104D0 (en) | 1987-08-26 |
| DE3721664C2 (en) | 1990-02-08 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKLA | Lapsed | ||
| MKLA | Lapsed |
Effective date: 20000403 |