DE10312819A1 - Covering layer for engine room cladding, comprises fleece material, including melt-adhesive fibers, bonded with a binder that changes from thermoplastic to duroplastic at high temperature - Google Patents

Abstract

Covering layer (A) for engine room cladding comprises at least one binder-bonded fleece material layer (X). The new feature is that (X) is made from a mixture of viscose, polyester, cellulose, polyamide, polyolefin and/or preoxidized polyacrylonitrile fibers, also melt-adhesive fibers, using a binder (Y) that is thermoplastic at 20-200[deg]C but is duroplastic above 200[deg]C. An independent claim is also included for a method for preparing (A).

Description

The invention relates to a cover layer for engine compartment lining, consisting of at least one binder-bound nonwoven layer.

Engine compartment linings serve the acoustic isolation of engine noise. From document WO 02/053373 multilayer materials are known as engine compartment linings be used. A substrate layer is made by impregnation or coating of a fabric or nonwoven fabric made of inorganic Fibers or a paper with a resin compound, the inorganic filler Contains loess, being the resin is a thermosetting Resin selected from the group consisting of phenolic resins, modified phenolic resins, modified phenol-urea resins, melamine resins and modified Is melamine resin, and one on the back Layer of aluminum or a galvanized steel plate.

From the document JP 20021004164 a flame-retardant, resin-bonded nonwoven fabric is known in which the nonwoven fabric is impregnated with an emulsion of resin and a phosphorus-based flame retardant. The nonwoven should consist of flame-retardant viscose fibers produced in a mixed spinning process and flame-retardant fibers made of partially carbonized normal viscose and / or polyacrylonitrile fibers.

Furthermore, from document JP 02/070428 a cover layer for a hot melt molding known in which a styrene resin on the surface of a polyester fiber and carbon fibers existing copolymerized and in a hot pressing process is formed.

As engine compartment linings are predominant Mats made of phenolic resin soaked Reclaimed cotton used with a black colored nonwoven on the later visible Side are covered. The nonwoven has to cover the tear cotton liquid repellent against various liquids like water, petrol, diesel, brake fluid, engine oil and in some places flame retardant his. The connection with the tear cotton is made by hot melt adhesive fibers. Preferably bicomponent bevels made of polyolefins and / or polyester, the one on the back of the nonwoven are produced. This procedure does unnecessary additionally Operation for hot glue Coating. The composite is shaped at 200-230 ° C in heated presses for 60-120 s.

Binder-bound are used and needled nonwovens, usually in a second process step through an impregnation process flame retardant and liquid repellent equipped and back in one step can be coated with the adhesive medium by powdering or printing.

Cost gates usually become linked Nonwovens preferred, however, when deformed into deeper Forms tear often and then be replaced by the needle punch nonwovens at an increased cost have to.

The automotive industry is calling Material for the covering layer of the engine compartment lining, which is a very high shows three-dimensional thermal formability above 200 ° and with flame protection and liquid-repellent properties equipped and their thermal bonding ability against the sub-material, which mostly consists of inexpensive rice wool, is large equipment without an additional Process step is to take place.

The invention has the task asked to develop a binder-bound nonwoven that also like Needle fleece for deeper deformations is suitable and at the same time through integration the flame retardant and liquid repellent finish in basic nonwovens can be manufactured at significantly lower cost can.

According to the invention the task is thereby solved, that a cover layer consisting of at least one binder-bound Nonwoven layer, the nonwoven layer consisting of a mixture of viscose (VC), polyester (PES), cellulose, polyamide (PA), polyolefin and / or preoxidized polyacrylonitrile (PAN) fibers and hot-melt adhesive fibers with a Binder is solidified, which is a thermoplastic behavior in the temperature range from 20 to 200 ° C and a thermosetting behavior above 200 ° C having. This behavior is due to the cross-linking hardening of the Binder reached.

The nonwoven fabric is advantageously bound with a condensing crosslinking binder which only pre-crosslinks at a temperature up to 200 ° C. and cures at a temperature above 200 ° C. The binder is selected from the group of acrylic acid copolymers and terpolymers with styrene, butadiene and / or acrylonitrile, preferably from the group of acrylic acid copolymers and terpolymers with styrene. The binder can also contain flame retardants, water repellents and / or oil repellants. A halogen-free and heavy metal-free nitrogen-containing phosphorus is preferred as the flame retardant binding available. A phosphonic acid derivative with an elemental content of 10 10% by weight of nitrogen and 5 5% by weight of phosphorus is preferred, which shows a high synergism. No hygroscopic behavior of the flame retardant and no softening effect on the binder is found. The nonwoven layer itself consists of a mixture of viscose (VC), polyester (PES), cellulose, polyamide (PA), polyolefin and / or preoxidized polyacrylonitrile (PAN) fibers and hot-melt adhesive fibers made of polyolefin or polyester bicomponent fibers ,

The covering layer according to the invention has a basis weight of 20 to 200 g / m ² , the weight ratio of the fibers used per square meter to the binder used per square meter being in the range from 0.5: 1 to 2: 0.5.

The invention also relates to a method in which staple fibers with a length of 20 to 200 mm and a fiber titer of 0.8 to 40 dtex are laid to a fiber pile with a basis weight of 10 to 200 g / m ² and impregnated with a binder, which has a thermoplastic behavior in the temperature range from 20 to 200 ° C and a thermosetting behavior above 200 ° C. The binder is applied in foam form. The pile is laid so that the ratio of the elasticity transverse to the machine direction (cross direction CD) to that in the machine direction (machine direction MD) is in the range from 1: 4 to 2: 1. The nonwoven layer has a proportion of bicomponent fibers in the fiber mixture, which serve as a hot melt adhesive for permanent anchoring to the tear cotton mat underneath. The proportion of bicomponent fibers in the nonwoven layer is at least 5.0% by weight. The bicomponent fibers consist of a polymer with a melting range of 240 ° C to 265 ° C as the core and a polymer with a melting range of 120 ° C to 170 ° C as the sheath.

The main advantage of the covering layer according to the invention for engine compartment linings consists in the simplified design of the production process, with staple fibers made of white or dyed black Fibers deposited in a disordered manner by a carding process become. The pile obtained can be strong in the machine direction be oriented. Subsequently the impregnation takes place with a mixture of binders in the form of a foam that forms the pile penetrated and for a complete Wetting the pile of fibers and thus the absorption of binders. What is essential is the selection of the binder, which is two different Has phases of plastic behavior. First, a thermoplastic Behavior in the range from room temperature to 195 ° C and second, one phase which by a thermosetting behavior above 200 ° C by the full curing of the binder is achieved. Other additives in the binding system are flame retardants, Fluorine resins and possibly pigments around the cover layer provide flame protection and liquid repellent properties as well as a uniform black coloring to rent. The drying process is at a temperature below of 200 °. Corresponding these process conditions, a nonwoven fabric is obtained that has a thermoplastic character and a thermal binding ability has. The hot melt adhesive, for example made of a polyolefin or polyester bicomponent fiber allows the cover material to be bound after thermal shaping at temperatures above 200 ° C against the tear wool material. For the In contrast, achieving the three-dimensionally stable formability no preference for the covering materials used so far in the orientation of the nonwoven pile before connecting to the Shoddy material required. While conventional binder-bound nonwoven for the covering layer of engine compartment linings always had to be used at right angles to the machine direction this is no longer necessary. The with the cover layer according to the invention Engine compartment linings produced show a very good three-dimensional Formability above 200 ° C. There is no delamination of the molded parts. Own the parts very good thermal dimensional stability and show no shrinkage. The cover layer has a highly effective flame protection before and after thermal molding at temperatures above 200 ° C and a permanently hydrophobic and oliophobic character. Through the proposed manufacturing process the costs decrease because of a separate finishing step with flame retardants and liquid repellants can be dispensed with and the additional operation of a Coating with a hot glue can be dispensed with.

The invention is described below of three examples in more detail explains:

example 1

A fiber pile with a basis weight of 17 g / m ^{2 is} laid crosswise from white and black spun-dyed polyester fibers of low strength and a fiber titer of 3.3 dtex and a fiber length of 60 mm. A second fiber pile with a basis weight of 5 g / m ² is made of polyolefin or polyester bicomponent hot-melt adhesive fibers with a fiber titer of 3.3 and a fiber length of 60 mm placed transversely to the first, with an increase in the speed of a reorientation of the fibers and the elasti cross machine direction to machine direction (CD / MD) ratio is approximately 2.0: 1. The fibrous web is impregnated with a binder foam of an acrylic acid copolymer or terpolymer with styrene, butadiene and / or acrylonitrile, which leads to a solids content of approximately 18 g / m ² . Drying is carried out by hot air below 200 ° C, whereby binder hardening is avoided. The finished basis weight of the covering material is 40 g / m ² . The finished cover layer is used in a three-dimensional molding process at temperatures above 200 ° C against a sub-material made of, for example, rip wool and bonded by the hot melt adhesive fibers it contains. The molding takes place at a pressure of greater than 200 bar / cm ² for a period of 60 to 90 seconds. The molded parts obtained with the cover layer according to the invention are perfectly covered with the cover layer and also adhere to the sharp creases of the part without cracks and delamination. The edges can be cut cleanly. The flame retardant and liquid repellent properties that are obtained after the thermal molding process.

Example 2

From white or black spun-dyed polyester fibers with low strength, a fiber lattice of 3.3 dtex and a fiber length of 60 mm, a fiber pile of 20 g / m ^{2 is produced} in a transverse configuration. A second fiber pile with a basis weight of 11 g / m ² is made from a mixture of 50% by weight white or black spun-dyed polyester fibers with a low strength, a fiber grid of 3.3 dtex and a fiber length of 60 mm and 50% by weight of a polyolefin - or polyester bicomponent hot-melt adhesive fibers with a fiber titer of 3.3 and a fiber length of 60 mm laid transversely to the first, with an increase in the speed of reorientation of the fibers and the elastic properties CD / MG being 2: 1. The fleece is impregnated with a binder made of a thermally crosslinking co-polymer or terpolymer of styrene and / or butadiene and acrylic acid with a solids content of 49 g / m ² and dried with hot air below 200 ° C., so that a complete hardening of the Binder is avoided. The basis weight of the finished covering material is 75 g / m ² .

Example 3

60% by weight of black spun-dyed polyester fibers with a fiber fineness of 1.7 dtex and a fiber length of 40 mm and 40% by weight of a black preoxidized PAN fiber with a fiber fineness of 2.4 dtex and a fiber length of 60 mm a pile of 48 g / m ^{2 is} occupied. The pile is laid in a transverse configuration. A second fiber pile with a basis weight of 18 g / m ² is made from a mixture of 50% by weight white or black spun-dyed polyester fibers with a low strength, a fiber lattice of 1.7 dtex and a fiber length of 38 mm and 50% by weight of a polyolefin - or polyester bicomponent hot-melt adhesive fibers with a fiber titer of 3.3 and a fiber length of 60 mm placed transversely to the first, the fibers reorienting as the speed increases and the CD / MD elasticity ratio being 2: 1. The fiber web is impregnated with a binder mixture which has a dry content of 54 g / m ² . Drying is carried out with hot air below 200 ° C in such a way that complete hardening of the binder is avoided. The weight per unit area of the finished covering material is 120 g / m ² .

Table 1 shows the flame resistance and the repulsion resistance according to the norm regulations DIN 75200 and DIN 53906 according to the examples 1 to 3 cover layers obtained compiled.

Claims (12)

Cover layer for engine compartment lining consisting of at least one binder-bound nonwoven layer, characterized in that the nonwoven layer consists of a mixture of viscose (VC), polyester (PES), cellulose, polyamide (PA), polyolefin and / or preoxidized polyacrylonitrile (PAN ) Fibers and hot-melt adhesive fibers is solidified with a binder, which has a thermoplastic behavior in the Tempe temperature range from 20 to 200 ° C and a thermosetting behavior above 200 ° C. Covering layer according to claim 1, characterized in that the Nonwoven layer with a condensing crosslinking binder is bound, which pre-crosslinks at a temperature up to 200 ° C and at a temperature above 200 ° C is cured. Covering layer according to one of claims 1 or 2, characterized in that the Binder selected is from the group of acrylic acid co and terpolymers with styrene, butadiene and / or acrylonitrile. Covering layer according to one of claims 1 to 3, characterized in that the Binder flame retardant, water repellent and / or oil repellent contains. Covering layer according to one of claims 1 to 4, characterized in that as Flame retardants containing halogen and heavy metal free nitrogen Phosphorus compounds are included. Covering layer according to claim 5, characterized in that as Flame retardant containing nitrogenous phosphonic acid derivatives are contained with an elemental content of nitrogen ≥ 10% by weight and phosphorus ≥ 5 Wt .-%. Covering layer according to one of Claims 1 to 6, characterized in that it has a weight per unit area of 20 to 200 g / m ² , the weight ratio of the fibers used per square meter to the binder used per square meter being in the range from 0.5: 1 to 2 : 0.5 lies. Covering layer according to one of claims 1 to 7, characterized in that the Nonwoven layer Hot melt adhesive fibers made of polyolefin or polyester bicomponent fibers contains. Process for producing a cover layer according to one of claims 1 to 8, characterized in that staple fibers with a length of 20 to 200 mm and a fiber titer of 0.8 to 40 dtex to form a fiber pile with a basis weight of 20 to 200 g / m ² laid and impregnated with a binder which has a thermoplastic behavior in the temperature range from 20 to 200 ° C and a thermosetting behavior above 200 ° C. A method according to claim 9, characterized in that this Binder in foam form is applied. A method according to claim 9, characterized in that the The pile is laid in such a way that Ratio of elasticity transverse to the machine direction to that in the machine direction in Range from 1: 4 to 2: 1. Method according to one or more of claims 9 to 11, characterized in that the At least the proportion of hot melt adhesive fibers in the nonwoven layer Is 5% by weight.