AU618755B2 - Moulded part, particularly for motor vehicles - Google Patents

Abstract

For formed parts such as are used, for example, in vehicles, synthetic resins are normally used as binders for the fibre materials. In contrast, it is proposed to use gypsum binders or modified gypsum binders, which can be modified with small additions of plastics, for producing these formed parts, which accurately retain their shape even under the action of moisture. Further advantages are the non-flammability and the reduced gaseous emissions.

Description

618755 Form COMMONWEALTH OF AUSTRALIA PATENTS ACT 1952-62 COMPLETE SPECIFICATION

(ORIGINAL)

FOR OFFICE USE: Application Number, Class Int. Class Lodged: 00 1ompjlte S e ,Iflcatlon Lodged, Accepted: Published: Prioity! Rpe4 Art 0TO BE COMPLETF APPLICANT j Name of Applicant: BVRAUNHOFER-GESELLSCHAFT ZVtY V0RDElUNG DER AN'GEWANDTEN If FORSCHUNG E.V.

Address of Applicant: 11 Leonrodstrasse 54 D-8000 MUNCH-EN 19 Prof Dr Ing habil Gert Kossatz,, Dr rer nat Karsten Lempfer, Dr IEng Heinz Sattler Address for Service: 0/I- R K Maddern Associates, 345 King William Street, Adelaide, State of South Australia, Convnonwealth of Australia, Complete Specification for the invention entitled: "MOULDED PART, PARTICULARLY FOR MOTOR 'VEHICLES" The following statement Is a full description of this Invention, Including the best method of performing It known to MR. us.

i ii .iii l y ru~llll ABSTRACT OF THE DISCLOSURE Synthetic resins are generally used as binding agents for the fibrous materials used in moulded parts such as those installed in vehicles, for example.

In contrast to this, the proposal is hereby made to use plaster binding agents or modified plaster binding agents for the production of such moulded parts which can be modified by the addition of small proportions of synthetic materials. TheLe moulded parts have kept their a0 0 li form even when exposed to moisture. Further advantages are r.n-flammability and reduced gaseous emissions.

o a 0a a 4 04 *4 p 0 0 01 Q 00 The present invention relates to moulded parts which are essentially manufactured from organic filler or strenghtening materials and one or several binding agents.

The concept moulded part relates in this context to structural moulded parts such as interior linings for Smotor vehicles, aircraft, boats or ships, in particular for motor vehicles, but also other moulded parts which .10 are exposed to special conditions. In the case of moulded parts in motor vehicles, this can relate to the inside 4 4 04 o roof lining, cap sleeves, interior body linings, door linings, dashboards or similar. The moulded parts could 0 also be garden table tops, kitchen bench Lops, coffee tables, armchair wings, cupboard tops, window-sills or So pallet blocks.

I It is a known procedure to produce these moulded parts with organic filler or strengthening materials such as wood shavings, wood fibres, paper shreds or paper fibres.

These filler or strengthening materials are combines with a binding agent and worked in moulding presses to form moulded parts. Thus, for example, interior lining parts for motor vehicles made from material containing cellulose in accordance with DE-PS 28 45 117, DE-PS 28 112 or DE-OS 26 35 957 are worked with a thermoplastic synthetic binder. The use of dur.plastic binding agents -2such as isocyanates is also known. According to DE-PS 29 25 630, it is known to use waste products from industrial filters which have been impregnated with phenolic resins as fibrous base material. Garden table tops or window-sills are manufactured fiom a mixture of wood and synthetic resin in heated form tools.

Furthermore, it is known to produce panel blocks in an extrusion moulding process, also from a mixture of wood i r shavings and synthetic resin.

f 0 4 t 4410 f1 4 Apart from the expensive and high-energy production

I

processes used for the moulded parts described above, these mouldel parts have all the known disadvantages; that the finished moulded parts constantly give off noxious gaseous substances (for example formaldehyde), S which has particularly unfavourable consequences when, for instance, the moulded parts are installed in vehicles in such a way that the emission of noxious materials i is directed into a small enclosed area (passenger area), whilst a good heat conductive and gas-proof seal (metal shell) abuts the moulded part or is positioned very close to this. The first requirement to be met is therefore to produce a moulding which is substantially or completely emission-free. What is perhaps the obvious solution: to select a high proportion of organic fibrous materials of 60% to 90% and thus maintain the proportion of synthetic binding agents at a low level, leads to -3- I, ii further disadvantages. The high proportion of organic fillers leads to sensitivity to moisture and thus to considerable distortions in form as well as to a higher fire risk. A particular problem is thickening and a relatively substantial change in length. Change in dimension in either of these directions is not acceptable in vehicle construction, for example. Moulded parts with t low binder contents used in vehicle construction are Oti exposed to this risk of changes in length and thickening occurring, since the temperature inside vehicles 4 t increases particularly severely due to warmth from the sun and the parts are exposed to rain and spray especially while moving. The alternation between 1 temperature increase through the sun and cooling in conjunction with rain and spray lead to condensation 444 forming. This is particularly unfavourable, for example, in the door area because of the diffusion current from the interior of the vehicle to the outside, whereby the abovementioned metal outer shell of the vehicle acts as a vapour trap and therefore as a condensation surface.

There is a great difference in atmosphere between the micro-climate inside a vehicle or in the passenger cabin and the climate outside and this has a direct influence on the moulded part. Varying humidity and temperatures lead to a moisture gradient over the cross-section of the moulded part causing stresses in the moulded part.

These stresses lead to distortions in length, width and thickness of the moulded part. The consequences are changes in length and width, buckling and problems of fit at assembly points or at the inlets for the crankshaft or similar. The moulded parts must however be easily removed and replaced without fitting difficulties for maintenance and repair operations.

4 4r 4 Therefore, the second requirement relates to a low t4 moisbure sensitivity and the third to a high dimensional stability. In short, the object of the invention is to provide an easily pre-formed moulded part which does not emit any noxious substances, even under unfavourable climatic cunditions, and is dimensionally stable.

The problem is essentially solved according to the invention by producing moulded parts of the same type and for the named purpose, which are indeed formed from mixtures of organic filler or strengthening materials such as wood shavings, wood fibres, paper shreds or paper fibres, but in which the essential binding agent content is selected from inorganic materials such as plaster or plaster-cement-pozzuolana, possibly with small amounts of synthetic resin added.

Particularly suitable is tae semi-dry process known from the EP-PS 19 207 for the production of structural panels, according to which the organic filler or strengthening materials in the mixture are also carriers for the minimum amount of moisture necessary for setting.

Naturally, mixtures of fibrous materials and plaster used for the production of structural panels are not only known from EP-PS 19 207, but for example also from DE-PS 100 978 or DE-PS 927 735 or DE-OS 15 71 466 or DE-AS 24 49 015 or DE-AS 24 49 015. However, these all relate to S° the classical use of plaster as a construction material.

In instances where prefabrication of structures bonded 9044 °6.'10 with plaster is known, the prefabrication aspect means S0D that tho plaster work previously carried out by craftsmen 4o is done in a factory. Hence, plaster boards are prefabricated commercially in order to save the amount of a o gypsum plaster used on the construction site and O 00 consequently substitute an industrial prefabrication *00 process for manua, work on site. The aim of these efforts is to change the location of the plaster working hitherto 0*o always related to building construction, the construction 0, site and use in the erection of buildings. The association between plaster application and construction work is so close that no one has as yet considered using plaster as a binding agent in the production of moulded parts, for example for use in the automotive industry.

The use of plaster to produce automobile parts or similar parts is new and has not yet been anticipated, especially because the moist conditions outlined above would cause any thought of using plaster as a binding agent to seem out of place since it is set with water and is traditionally regarded as not being water-resistant.

Nevertheless, tests with the present invention have proved the operability of the invention.

The concept of the invention encompasses the use of plaster-cement-pozzuolana or synthetic resin binding agents although these binding agents are also known in a c the building industry for the production of structural i0 panels. For example, a binding agent mixture of o" sulphatic, lime-yielding pozzuolana materials rich in aluminate is known from P 32 30 406.4. The use of plaster and synthetic resin mixtures is known per se from the |i DE-PS 1 048 531 or DE-PS 1 129 879. Finally, the solutions outlined in our own previous patentjapptiFtae "3>b A& Qhks 36 26- 04-- can also be applied to the present invention.

4 9a 9 9 o The moulded parts according to the invention emit greatly 20 reduced amounts of gaseous substances under normal conditions of use, in contrast to the moulded parts previously used. Even4l- t za synthetic binders are added, there is no longer any emission of noxious gas because of 'he small proportion therof. The moulded parts are less hygroscopic, are less prone to thickening and changes in length and are less sensitive to moisture.

A-7i The change in thickness is less than that in the case of panels bonded with synthetic resin since the shavings or fibres in the binding agent matrix do not adhere directly to one another. Rather, the shavings and fibre content is low in relation to the proportion of plaster.

The shavings or fibres are much more ly dispersed in the end product "moulded part". Therefore, the dimensional changes in the shavings and fibres caused to o by moisture have only slight influence on the dimensions 810 of the composite mixure, which achieves a high degree S 9o of stability of form. Mixtures of binding agents with S0o a high plaster content may even be used for moulded parts which are directly exposed to moisture, such as garden a oo table tops. The undesirable consequences of changes in thickness which would otherwise be apparent on the o oo surface in such moulded parts, or in kitchen benches, do not arise.

0 0 The moulded part is practically non-flammable. This is due, according to the invention, to the fact that in all cases a high proportion of plaster is contained in the binding agent. The inventive concept consists in the fact that especially those moulded parts which are exposed to significant influences of moist conditions, either in the vehicle itself or due to increases in temperature and the resulting formation of vapour, or are exposed to moisture directly, are bonded with plaster -8- I which has hitherto been regarded as not being water-resistant or being sensitive to moisture.

Further details, features and advantages of the invention may be seen from the claims and the following examples: %hejessential components, i.e. 0,1 to 0.35 parts of the organic filler or strengthening material to each part of the mineral binding agent, are mixed in what is known as the semi-dry process, By way of example, wood shavings are given a predetermined moisture content by adding water, taking into o 0 itO' consideration the moisture of the wood. An isocyanate able to r. form an emulsion with water may be added to the water as the o o synthetic material component, The wood shavings prepared in 0 0 0 *0 this matter are then mixed with plaster binder in a mixing drum, where the dry plaster binding agent is mixed into said moist shavings. The moisture content in the shavings is 0 *r sufficient to provide the plaster binder with the amount of moisture necessary for setting, The mixture is removed from the drum and placed in a bottom mould and a male mould is placed on top and the whole is pressed under moderate pressure Z:O to the required thickness and density.

Any additive required can be added to the mixture before pressing. For example, extendors, such as retarding agents or accelerators for the binding agent, can be added, as can dyes, if required. It is not necessary to add a flame-proofing agent -9since the high plaster content acts as an effective fire protective medium.

The process outlined above can be varied, within limits, as shown in the following examples. In the following examples the details relating to the composition of the mixture are based on one part plaster binding agent. Preferably, the moulded part is formed from a mixture of 1 part plaster binding agent, 0,15 to 0.25 parts organic filler or strengthening material, 0.20 to 0.45 parts (more preferably, 0,30 to 0,40 parts) water and 0,0 00 6 10 to 0,30 parts (more preferably, 0.05 to 0.15 parts) synthetic 0 resin. In particular embodiments, 0.05 to 0,20 parts 9 *000 o (preferably, 0,07 to 0,15 parts) of isocyanate or epoxy resin 0 0 o are used as the synthetic resin component.

*0 EXAMPLE 1 ,o To one part plaster binder 0.22 parts shavings are added which a I *T have been mixed with 0,3 parts water. No synthetic resin whatever is added in this example. The material is pressed to a thickness of 6 mm. The measured density amounts to 3 1230 kg/m The flexural strength is established to be I2 O 7.1 N/mm The measured modulus of elasticity amounts to 3820 9 N/mm .Thickening after 24 hours in water is less than 2%.

As regards the specified thickening, it should be noted here and fov the following examples that a thickening rate of between 10 and 15% is regarded as permissible for particle -tY V o i board bonded by synthetic resin. This value is substantially fallen short of in Example 1 and in the following examples.

09 00 4, 0

COHPARATNEV

EXAMPLE 2 To one part plaster binder, 0.33 parts shavings are added, which have been mixed with 0.3 parts water. There is no addition of synthetic resin binders in this example either. A moulded part with a thickness of 8 mm is formed. The density amounts to 1270 kg/m 3 The flexural strength lies at 10.6 N/mm 2 and the modulus of elasticity at 4550 N/mm 2 Thickening after 24 hours in water is less than 2%.

EXAMPLE 3 Once again, to one part plaster binder, 0.22 shavings are added, which have been mixed with 0.3 parts water.

In this example, 0.075 parts isocyanate are added. The moulded part has a thickness of 6 mm. The density amounts to 1290 kg/m 3 The flexural strength lies at 10.8 N/mm 2 and the modulus of elasticity at '000 N/m 2 Thickening after 24 hours in water is less than 1%.

*4 EXAMPLE 4 To the same mixture as given in Example 3, 0.15 parts isocyanate are added. The moulded part is 6.5 mm thick.

The density amounts to 1550 kg/m 3 The flexural strength lies at 16.6 N/mm 2 and the modulus of elasticity at 7710 N/mm 2 Thickening after 24 hours in water is less than 1%.

-11i,

I,

EXAMPLE Example 2 is modified by the addition of 0.075 parts isocyanate. The pressed part has a thickness of 7 mm.

The density amounts to 1263 kg/m 3 The flexural strength lies at 15.1 N/mm 2 and the modulus of elasticity at 4700 N/mm 2 Thickening after 24 hours in water is less than 1%.

a V EXAMPLE 6 "*10 Example 5 is modified by th, addition of 0.15 parts 9 GO a 0 o isocyanate. The moulded part is pressed to a thickness of 6 mm. The density amounts to 1310 Kg/m 3 The flexural strength is measuied at 19.2 N/mm 2 and the V modulus of elasticity lies at 6280 N/mm 2 Thickening S4 after 24 hours in water is less than 1%.

0o EXAMPLE 7 1 The mixture given in Example 4 is pressed to a thickness V V 4. of 6 mm. This results in a density of 1540 kg/m 3 The flexural strength lies at 16.0 N/mm 2 and the modulus of elasticity at 7410 N/mm 2 Thickening after 24 hours in water is less than 1%.

-12- E3XAMPLE 8 The quantities of plaster bindor, shavings and water are the same as in Example 2. However, 0. 15 parts of an epoxy resin are added and the mould part is presseu- a thickness of 6 mm. The density am~ounts to 1260 kg/rn 3 and the flexural strength lies at 12.9 N/mm 2 The modulus of elasticity is measured at 4080 N/mm 2 49 4 Thickening after 24 hours in water is less than 1%.

0* 09 00 a 04 0 4 &9 44139

Claims (7)

1. Compression moulded part for use in vehicles, for example for interior linings, dashboards, cap sleeves or for use in areas exposed to water such as the tops of garden tables, characterised in that the moulded part is formed from a mixture of 0.10 to 0.35 parts of an organic component selected from wood shavings, wood fibres, paper shreds and/or paper fibres with 1 part of a binding agent component selected from plaster binding agents and plaster-cement-pozzuolana binding agents, Se eQ and 0.20 to 0,45 parts of water, together with one *o or more synthetic resins, 4nd by setting the binding agent component, where the water necessary for setting the binding S 0 0 agent component is exclusively or predominantly supplied by way 0 0 of the organic component, to provide a mixture consistency such as will enable moulding through dispersion and compression of the mixture. o

2. Moulded part according to claim 1, characterised in that, S to 1 part of the binding agent component, 0.15 to 0,25 parts of 0.05 the organic component, 0.30 to 0.40 parts water and 4 to 0.30 parts synthetic resin are added.

3. Moulded part according to claim 2, charaoterised in that 0.05 to 0.15 parts synthetic resin are added.

4. Moulded part according to claim 2, characterised in that -1 -14- k. I the synthetic resin component consists of iscayanate and is added in an a:.lount of 0.05 to 0.20 parts.

Moulded part according to claim 2, characterised in that the synthetic resin component consists of epoxy resin and is added in an amount of 0.05 to 0.20 parts.

6. Moulded part according to claim 4 or claim characterised in that the synthetic resin component is added in an amount of 0.07 to 0.15 parts. S

7. Process for the production of a moulded part according to one or several of claims 1 to 6, characterised in that, for 0* uniform dispersion, the water necessary for setting is supplied 0 to 1 part of the binding agent component, apia1~y together with a suitable amount of synthetic resin in the form of a synthetic resin/water emulsion, by intimate mixing with 0.10 to 0.35 parts (dry weight) of moistened wood shavings, wood *a o ao fibres, paper shreds or paper fibres or a mixture thereof, the total amount of added water being 0.20 to 0.45 parts, and in 10 that the resultant mixture of materials hardens to form a moulded part after appropriate moulding in a compression mould, Dated this 6th day of May 1991 FRAUNHOFER-GESELLSCHAFT ZUR FORDERUNG DER ANGEWANDTEN FORSCHUNG eV. By its Patent Attorneys R K MADDERN ASSOCIATES