WO2019169614A1

WO2019169614A1 - Thermoformed automotive product with reduced voc

Info

Publication number: WO2019169614A1
Application number: PCT/CN2018/078477
Authority: WO
Inventors: Jinjing CHEN; Xiaoning YAN
Original assignee: Autoneum Management Ag; Autoneum (Shanghai) Management Co. Ltd.
Priority date: 2018-03-08
Filing date: 2018-03-08
Publication date: 2019-09-12
Also published as: CN112638996A

Abstract

Thermoformed automotive trim part comprising at least a fibrous felt layer comprising fibers and a thermoplastic binder and whereby the fibers comprise recycled or reclaimed fibers, characterised in that at least one surface of the fibrous felt layer is impregnated with a first substance selected from the group of urea, preferably ethylene urea, propylene urea or a mixture thereof and whereby the first substance is adhered to at least the fibers forming the outer boundaries of the layer.

Description

THERMOFORMED AUTOMOTIVE PRODUCT WITH REDUCED VOC

Summary of invention

The application is directed to thermoformed automotive trim parts comprising recycled fibers and a method for producing such trim part.

Description of embodiments

The passenger compartment is prone to malodorous and chemical substances either released by the materials the various trim parts are made off or originating from the normal use of the vehicle.

Formaldehyde is a common low molecular weight molecule that belongs to a class of volatile organic compounds that are released by automotive parts or other surrounding products. In particularly in a closed environment like the passenger compartment of a car the level of formaldehyde can increase above a threshold deemed healthy for a human being.

Acetaldehyde and formaldehydes might be released from the products as unreacted and or by-product of the product itself, but might also be adsorbed from the surrounding air by the part. In particularly recycled or reclaimed materials like for instance shoddy fibrous materials, shoddy cotton for instance, might also pick formaldehyde from the air and absorb the molecules to the fibers or the source of the recycled fibers might be contaminated with formaldehyde.

If this type of materials is used in the passenger compartment of a vehicle the level of free formaldehyde and acetaldehyde might become above a defined threshold as measured according to the VOC emission test.

It is therefore the object of the current invention to supply a method of treating fibrous materials, in particularly thermoplastic or natural fiber mats or felts, to reduce the level of free formaldehyde and free acetaldehyde in overall VOC emission of the fibrous material and or part.

Summary of Invention

This object is achieved by the product according to claim 1, and by a method of producing such a product according to claim 12.

In particular by a thermoformed automotive trim part

comprising at least a fibrous felt layer comprising fibers and a thermoplastic binder and whereby the fibers comprise recycled or reclaimed fibers, characterised in that at least one surface of the fibrous felt layer is impregnated with a first substance selected from the group of urea, preferably ethylene urea, propylene urea or a mixture thereof and whereby the first substance is adhered to at least the fibers forming the outer boundaries of the layer.

By incorporating at least one substance from the group consisting of urea, preferably ethylene urea, propylene urea and mixtures thereof in at least the surface of the fibrous felt layer, it is possible to decrease the free formaldehyde. Surprisingly, also the amount of free acetaldehyde was found to be reduced. The reduction of both formaldehyde and acetaldehyde was not only measurable during the treatment of the felt material, but was maintained after thermoforming of the part as well as after storage of parts. Thermoformed automotive trim parts comprising a fibrous felt layer according to the invention have an excellent odour eliminating property so that the VOCs as described above are captured and not released.

This treatment is versatile enough to use on fibrous mats comprising recycled fibers without knowledge on the actual source or contamination of the recycled fibers used.

Preferably the final concentration of ethylene urea is between 3 and 20 gr/m ² treated surface of the fibrous mat.

Preferably the VOC reducing effect is further enhanced by incorporating at least a second substance from the group consisting of dihydrazides, in at least the surface of the fibrous felt layer.

Preferred the dihydrazide compound used is one selected from carbodihydrazide, succinic acid dihydrazide, adipic acid dihydrazide, isophthalic acid dihydrazide, preferably carbodihydrazide.

The use of more than one dihydrazide is less preferred as it might have a negative impact on the capturing and release of the acetaldehyde and or formaldehyde. Most preferred is carbodihydrazide.

The minimal concentration should be enough to at least capture the free formaldehyde and/or acetaldehyde already available in the material when it is processed. Concentration above the needed concentration to capture the existing contamination will be beneficial however for capturing and binding VOCs from adjacent layers or from the surrounding air around the part. If this is in the vehicle, it would help eliminate additional contamination in the car coming from other components in addition, which is an advantage.

Preferably the final concentration of the two combined substances -ethylene urea and carbodihydrazide-is between is between 3 and 25 gr/m ² treated surface of the fibrous mat, preferably between 5 and 10 gr/m ² treated surface of the fibrous mat.

Preferably the weight ratio of ethylene urea and carbodihydrazide is between 1∶4 and 4∶1, preferably 1∶1.

The fibrous felt layer comprises at least thermoplastic binder and fibers. Preferably the thermoplastic binder is one selected from the group of polyesters, like polyethylene terephthalate (PET) or copolyesters like Co-polyethylene terephthalate (CoPET) , polyolefin, like polyethylene or polypropylene, or polyamide, like polyamide 6 or polyamide 6-6 or combinations of those. The binder can be added in the form of a binder fiber. Alternatively the binder is combined in a bicomponent fiber of for instance the core/sheath type whereby the outer surface functions as the binder and during thermoforming melts and binds the fibers together while the core of the fiber stays intact and become part of the fibers.

The fibrous mat preferably comprises natural fibers, like cotton, or thermoplastic fibers, like polyester, like PET, polyolefins, like polyethylene or polypropylene, polyamides, like polyamide 6 or polyamide 6-6 or combinations of those.

The fibers can be virgin based or might come from reclaimed or recycled textiles, post-consumer fibers or a combination of those sources. Recycled fibers might also include fibers from scraps of automotive part production.

An example of a source for recycled fibers that can be used for the automotive part according to the invention are shoddy materials, made from reclaimed post-consumer textiles, cloths coming from other type of industries or scrap fiber material from other productions within or outside of the automotive industry, like for instance cut offs of fabric industry or jeans productions. Shoddy material is defined over the main type of fibers it contains for instance shoddy cotton contains at least 51%of cotton type fibers, while polyester shoddy contains at least 51%of polyester based fibers. The other %might be a combination of a wide range of fiber types and is less defined.

The fibrous felt layer according to the invention might further comprise a low amount of non-fibrous content, like non-fibrous scrap material, like foam, or shredded thermoplastic material for instance in the form of foam chips.

The automotive trim part according to the invention comprises at least a fibrous felt layer. It might comprise additional layers, for instance at least one of an additional felt layer, a film or foil layer, for instance based on polyolefin, like polypropylene or polyethylene, a synthetic rubber layer, like EPDM or EVA, a nonwoven or scrim layer, a foam layer, for instance an open cell polyurethane foam layer or a decorative surface layer like a tufted or nonwoven carpet or a knitted fabric.

The automotive trim part is thermoformed to a shape compliant with the function and surface it is placed upon. Therefore the outer surfaces of both sides of the formed part are not necessary the same. An automotive trim part might have one surface facing the body in white of the car or another car part to be covered; hence it will mirror the contour to fit the area.

While the other surface not facing the body in white or another car part to be covered, might have an additional decorative surface layer attached.

Preferably at least one surface or both surfaces of the fibrous felt layer comprises at least the ethylene urea, and preferably in addition the carbodihydrazide. However, also additional layers might be treated the same, in particular additional fibrous layers, like additional fibrous felt layers, scrims or nonwoven layers to further enhance the effect.

Process

Method of producing a thermoformed automotive trim part comprising a fibrous felt layer according to claim 1, said method comprising at least one step of applying an aqueous solution comprising a first substance being ethylene urea to at least one side of the fibrous felt layer.

Preferably followed by a subsequent thermal drying step, preferably in a hot air oven, such that said solution is dried and the substances adhere to the fibers.

In addition the hot air oven might also melt the thermoplastic binder and bind the fibers in the fibre mat to form a pre-bonded fibrous layer.

Unexpectedly, the combination of the water in the aqueous solution might enhance the capturing of the formaldehyde and or acetaldehyde by the ethylene urea and or carbodihydrazide either before or during this heating step. It was found that using an aqueous solution is more beneficial than a powder treatment using the same substances and process conditions.

A method of producing a thermoformed automotive part comprising at least a fibrous felt layer, with the consecutive steps of

(1) forming a fibrous felt mat, preferably by air lay and or carding and cross lapping;

(2) applying to at least one surface of the fibrous mat an aqueous solution comprising at least ethylene urea;

(3) heating the fibrous mat in a hot air oven, preferably at a temperature between 110 and 220, preferably between 140 and 200℃;

(4) compression moulding the fibrous mat to form the automotive part, eventually combined with at least one additional layer to form a multilayer automotive trim part.

The substances -Ethylene urea, Carbodihydrazide-may be dissolved or dispersed in a volatile inert carrier selected from the group consisting of water, a lower alkyl alcohol and mixtures thereof. Preferably water is used as the main carrier, as it may further enhance the capturing effect of the substances used, however pre-solutions in solvents or the addition of small amounts of solvents might be necessary to make the solution more stable or enable an easier dissolving of the substances used.

The aqueous solution may further comprise at least one of a stabiliser, surfactant or a binder, like poly-vinyl-alcohol.

The aqueous solution preferably has a solid content of between 5 to 50 %by weight and having a pH from mildly acidic to mildly alkaline (pH of about 5 to 9) .

The solution comprising ethylene urea is applied in a wet state. The term “wet state” refers to the compound comprising the reducing composition as well as the carrier -such as water. The carrier may comprise at least wt. 95%of water -based on the total weight of the carrier. Preferably the carrier is 100%water. After application of the solution, the carrier is evaporated for instance using a thermal process, yielding the coating being substantially in a dry state on the substrate. The term “dry state” refers to the coating being substantially solid at room temperature (i.e. about 21° to 23℃) having less than 5%moisture and being substantially free of carrier based on the total weight of the coating.

The felt might be treated by spraying an aqueous solution of ethylene urea on the fibrous mat, directly after the felt forming process, or on the fibrous felt layer, after part production, or on the fibers before or during formation of the felt.

The fibrous felt layer and the automotive trim part comprising it are preferably glass fiber free.

A possible production process of such an automotive trim part might comprise the following steps. An alternative order of the steps might be possible unless stated otherwise. Additional steps not disclosed might be included without diverting from the inventive idea.

Thermoplastic binder and fibers are mixed in an opening and or mixing device and transported to either a carding and eventual cross lapping unit or an air laying device to form an even fibrous mat. Alternatively the fibers can be formed in a pre-formed mat using a injected fiber device like for instance disclosed in EP 2532777 A .

The thus formed fibrous mat is laid on a transport belt and passed underneath or through a device that is able to apply the correct amount of aqueous solution comprising at least the first substance, and preferably the first and second substance, to at least one surface of the web. The device can either be a spraying device, able to spray an even mist or shower of small droplets on the surface of the fibrous mat as it passes underneath.

Alternatively the application device can be an application roll, for instance made of an open cell foam or fibrous material that is rolled over a surface, eventually under light pressure, thereby passing on the aqueous solution to the fibrous layer.

The roller can be placed on either side of the fibrous mat. For instance it can be placed underneath the fibrous layer, whereby the lower part of the roller is moved through a bath reloading the solution on the roller and the top part of the roller is rolled against the back surface of the fibrous layer passing on the aqueous solution to its surface.

Depending on the thickness and or density of the mat used it might be beneficial to use a combination of two rollers simultaneously treating both sides of the fibrous layers.

Other ways of applying small amounts of liquid on a fibrous surface known in the state of the art might be used like for instance foam application, or dipping baths. It might be necessary to add additional additives to the aqueous solution to enable such application forms.

Preferably the subsequent step after the application of the aqueous solution is a heating step, preferably in a hot air oven. Preferably the fibrous mat is treated at a temperature of at least between 110 and 220℃, preferably between 140 and 200℃.

Preferably the fibrous layer is moved on the same transport band through the hot air oven, preventing any unnecessary movement of the unbound fibrous mat.

The effect of the hot air treatment on the fibrous mat is at least two fold; the fibers are bound by the melting of the thermoplastic binder forming small droplets between the fibers, which solidify again after the hot air treatment during a cooling step. While at the same time the aqueous solution containing the substance is heated, whereby the water is partially vaporised while the first and eventual second substance is adhered to the fibers in the top layer of the fibrous mat.

The thus pre-bonded fibrous mat can either be stored for later processing of transferred in a hot state to a compression moulding device to directly form the automotive trim part.

Later processing can include another heating step followed by a cold compression moulding step or a one-step process using a steam moulding or hot moulding combining the heating and forming.

Independent of the moulding step chosen, additional layers can be included in this step to form a multilayer automotive trim part including at least one fibrous layer according to the invention.

After moulding at least the fibrous layer according to the invention and eventually other layers, also a combination with a process step containing reaction injection moulding of foam can be possible.

In case of a combination of the fibrous layer according to the invention with an injection moulded layer it might be beneficial to increase the load of the first and eventually the second substance and or to treat at least the side adjacent or close to the foam layer, to enable capture and binding any formaldehyde coming from the foam layer in addition to the contamination of the felt layer itself.

Example

A first set of thermoformed automotive parts were produced by forming a fibrous felt mat of shoddy cotton fibers with 20%bicomponent polyester fibers, heating the fibrous mat in a hot air oven, preferably at a temperature of 180℃; and compression moulding the fibrous mat to form the automotive part.

A second set of thermoformed automotive parts were produced by forming a fibrous felt mat of shoddy cotton fibers with 20%bicomponent polyester fibers, applying to one surface of the fibrous mat an aqueous solution comprising substance 1 in the form of ethylene urea; heating the fibrous mat in a hot air oven, preferably at a temperature between 160 and 200℃; and compression moulding the fibrous mat to form the automotive part.

A third set of thermoformed automotive parts were produced by forming a fibrous felt mat of shoddy cotton fibers with 20%bicomponent polyester fibers, applying to one surface of the fibrous mat an aqueous solution comprising substance 1 in the form of ethylene urea and substance 2 in the form of carbodihydrazide in a 1∶1 weight ratio; heating the fibrous mat in a hot air oven, preferably at a temperature between 160 and 200℃; and compression moulding the fibrous mat to form the automotive part.

All 3 sets were produced on a full scale production line using substantially the same batch of fibrous material. From all 3 sets sample were taken directly after production and after 7 days of storage of the parts in a standard warehouse for newly produced goods. Roughly 5g of substance 1 and eventually substance 2 per m ² surface of the fibrous mat was applied.

The released amount of formaldehyde and acetaldehyde was measured using the standardised method of Ford FLTM BZ 108-01 10-L Bag Method for measuring VOC Emissions from Vehicle Interior Materials.

The change in release of formaldehyde and acetaldehyde was calculated using set 1 as reference sample.

For set 2 it was found that the directly after production the level of formaldehyde released was reduced by 73%, and after storage the level of reduction increased to 77%. Surprisingly the level of acetaldehyde released was also reduced by 23%, while after storage this value was not substantially altered.

For set 3 it was found that directly after production the level of formaldehyde released was reduced by 84%, after storage it was not substantially altered. Interestingly also the level of released acetaldehyde was reduced by 92%. Although the level of released acetaldehyde was lower in the samples after storage. It only reduced by 84%, it is still significant better than set 2.

Depending on the initial level of contamination and the ratio of releasable formaldehyde and acetaldehyde in the fibre material used to make the automotive trim part only using substance 1, like ethylene urea, might reduce enough the contamination level to be sufficient. In case a higher level of acetaldehyde is expected, the combination of ethylene urea and carbodihydrazide might be preferred.

Claims

Thermoformed automotive trim part comprising at least a fibrous felt layer comprising fibers and a thermoplastic binder and whereby the fibers comprise recycled or reclaimed fibers, characterised in that at least one surface of the fibrous felt layer is impregnated with a first substance selected from the group of urea, preferably ethylene urea, propylene urea or a mixture thereof and whereby the first substance is adhered to at least the fibers forming the outer boundaries of the layer.
Thermoformed automotive trim part according to claim 1, whereby the at least one surface is impregnated with a second substance selected from the group of dihydrazides and whereby the second substance is adhered to at least the fibers forming the outer boundaries of the layer.
Thermoformed automotive trim part according to claim 2, whereby the dihydrazide compound used is one selected from carbodihydrazide, succinic acid dihydrazide, adipic acid dihydrazide or isophthalic acid dihydrazide, preferably the dihydrazide compound is carbodihydrazide.
Thermoformed automotive trim part according to one of the preceding claims, whereby the fibers comprise natural fibers, preferably cotton, thermoplastic fibers, preferably polyester, polyolefin or polyamide based fibers or combinations of such fibers.
Thermoformed automotive trim part according to one of the preceding claims whereby the thermoplastic binder is one selected from the group of polyesters, like polyethylene terephthalate (PET) or copolyesters like Co-polyethylene terephthalate (CoPET) , polyolefin, like polyethylene or polypropylene, or polyamide, like polyamide 6 or polyamide 6-6 or combinations of those.
Thermoformed automotive trim part according to one of the preceding claims further comprising at least one of an additional felt layer, a film or foil layer, for instance based on polyolefin, like polypropylene or polyethylene, a synthetic rubber layer, like EPDM or EVA, a nonwoven or scrim layer, a foam layer, for instance an open cell polyurethane foam layer or a decorative surface layer like a tufted or nonwoven carpet.
Thermoformed automotive trim part according to one of the preceding claims whereby the final concentration of the first substance eventually in combination with the second substance, is between 3 and 25 gr/m ² treated surface of the fibrous mat, preferably between 5 and 10 gr/m ² treated surface of the fibrous mat.
Thermoformed automotive trim part according to one of the preceding claims whereby the fibrous layer further comprises non-fibrous scrap material, preferably foam, or shredded thermoplastic material.
Thermoformed automotive trim part according to one of the claims 2 to 6 whereby the weight ratio of ethylene urea and dihydrazide is between 1 to 4 and 4 to 1, preferably in an equal weight ratio.
Method of producing a thermoformed automotive trim part comprising a fibrous felt layer comprising recycled or reclaimed fibers, said method comprising at least one step of applying an aqueous solution comprising a first substance being ethylene urea to at least one surface of the fibrous felt layer.
Method of producing according to claim 10, whereby the aqueous solution comprises a second substance being a dihydrazide, preferably carbodihydrazide.
Method according to 10 or 11, whereby the aqueous solution further comprises at least one of a stabiliser, surfactant or a binder, like polyvinylalcohol.
Method according to one of the claims 10, 11 or 12 whereby the aqueous solution is applied on both surfaces of the fibrous felt layer.
Method according to one of the claims 10 to 13, comprising a subsequent thermal drying step, preferably in a hot air oven, such that the aqueous solution is dried and the substances bonded to the fibers.