FR2678628A3 - Regenerated product from fibre-containing heat-curables, process for its preparation and its use - Google Patents

Abstract

It is proposed to grind waste originating from fibrous sheet structures impregnated with incompletely cured heat-curables with addition of inorganic filling matter and to employ this regenerated product as curable component in moulding materials, in products for friction linings or in refractory products.

Description

REGENERATION PRODUCT FROM THERMOSETTING PRODUCTS

  CONTAINING FIBERS, PROCESS FOR ITS PREPARATION AND ITS USE

  The invention relates to a regeneration product from fibrous web structures impregnated or coated with thermosetting, the thermosetting not being

  not yet fully cured but in an intermediate morphological state, as well as a process for the preparation and use of this regeneration product.

  During the transformation of fibrous structures impregnated with thermosets, waste forms which

  must be sent to the landfill An example for this is the manufacture of cut-off wheels or abrasive discs.15 In this case, for example, glass fiber fabrics are impregnated with solutions of curable resins based on phe-

  nol and, after drying between 80 and 160 WCs, circular discs are cut from there. The discs are coated with a mixture of abrasive and hardened discs Since the drying process is only carried out up to a point o, on the one hand the resin is non-sticky and, on the other hand it has not yet gone to state B according to DIN 16916,

  part 1, the resin is in an uneven morphological state

  intermediate. Another example is the waste from the processing of prepregs. The fiber fabrics are for example impregnated with an epoxy resin solution and dried. The sticky state and the residual gelation time.

  are adjustable by oven temperature The prepregs are cut to size, deposited on the surface of the mold and hardened under pressure As in the present case also10 the resin indeed begins to gel but has not completely hardened, it becomes also found in a morpholo-

  intermediate logic. Another example is cutting waste from technical filter paper which is for example impregnated

  gné of phenolic resins It is known to grind hardened reinforced curable thdr such as for example pa -

  Bakelized piers and to incorporate therein as filler phenolic resin-based molding materials (Becker / Braun: Kunststoffhandbuch, Hanser edition, volume 10, "Duroplast"). 20 The use of this filler material well that of higher quality, however, leads to a higher cost of the material

  to be molded as a result of the high grinding costs Since small proportions of regeneration product increase

  feels the viscosity in the molten state of the material to be molded and thereby changes the hardening flow behavior, the use of the regeneration product by the trans-

  Molding material trainer frequently leads to quality problems. Attempts to chemically disaggregate from

  such waste or subjecting it to pyrolysis have not been imposed to date In particular, with a high pro-

  portion of long fibers, it is necessary to reckon with considerable technological problems The new version of the waste catalog for 1985 reworked by a working group of the 35 Lânderarbeitsgemeinscha; 'ft Abfall subdivides ther curable waste into two categories: hardened waste and uncured waste According to this, the hardened waste can be in

  3 seen at the landfill as household waste, i.e.

  Waste in a controlled landfill or incinerated in a household waste incineration plant. Uncured waste, the disposal of which is the subject of this invention, must be treated as special waste. obligation of verification and must, to the extent

  if possible, be sent to a special waste incineration.

  Since the elimination of a residue by incineration is to be considered as the last resort when a reuse is not possible, there was then the problem of treating the waste coming from fiber structures impregnated or coated non-hardened thermosets so that reuse is possible. The problem is solved by a regeneration product consisting of crushed waste from fibrous structures.

  en impregnated and / or coated with thermosetting ply in an intermediate morphological state and, where appropriate,

  by inorganic fillers. 20 By flat fibrous structures is meant lattices, fabrics, fillings, plywood, papers, tablecloths, etc. of mineral and organic fibers. The r'g 4 neration product contains fibers no longer than 10 mm in length, preferably from 0.5 to

  5 mm and a proportion of thermosetting from 10 to 50% by weight, preferably from 20 to 40% by weight relative to the metal

  fiber / thermosetting cloth. As mineral fillers, the regeneration product may contain, depending on the intended application of the pro-

  regeneration product, calcium oxide, aluminum oxide, pulverized rock, among others.

  In the case of waste containing phenolic resin, the resin is in an intermediate state between

  state A and state B according to DIN 16916, part 1, but is preferably non-sticky. With regard to waste containing an epoxy resin, the resin begins to develop.

  lification and still has some sticky condition.

  The waste is first submitted, in case it is very large for the subsequent grinding process.

  quent, to a prior grinding which can for example be carried out in a knife mill The previously grinded waste is then fragmented, for example in a toothed crown mill, to inferior fiber lengths

  less than 10 mm The softer the resin in the waste, the more difficult the prior grinding and in particular the grinding process. To overcome this difficulty, there are in principle three ways.

  Waste can, for example, be further dried, in which case crosslinking

  hardenable continues without necessarily going into the hardened state They can also be made brittle by cooling below the glass transition point. It is in fact often necessary in this case also to cool the grinding device. They can also be ground with the addition of mineral fillers which coat the pressing surfaces and those newly formed during the grinding and thus prevent agglomeration. The choice of the appropriate process depends on the degree of drying of the thermosetting agent and the intended application of the regeneration product. The suggested methods can be combined with one another. For insufficiently dried waste, it is for example advisable to dry them first. at higher temperatures and then grind them by adding

  fillers The reactivities of the thermosets and the ease of flow of the regeneration product are obtained by this means. The grinding at low temperature has the disadvantage that the thermosets are separated at least in part from the fibers and that the product of regeneration

  Glomorous during subsequent storage Agglomeration can be avoided by the addition of fillers during or after grinding.

  Among the three proposed routes, we prefer the

  addition of fillers before or during grinding, because a regeneration product can be prepared in this way

  free-flowing with a thermosetting fraction in reactive core which remains bound to the fibrous material, even when

  during the grinding process. The regeneration product can be used as a hardenable component in molding materials, in friction lining products and in refractory products. The molding materials often contain pulverized rock as a filler material. that, in the present case, pulverized rock is added during the crushing of the waste. Among the products for friction linings, barium sulphate, magnesium oxide, oxide

  Zirconium and aluminum oxide are suitable fillers, while the refractory products contain magnesium oxide, aluminum oxide or silicon carbide.

  It has surprisingly been found that the thermosetting fraction of the regeneration product in an intermediate morphological state can replace the corresponding fraction of fresh ungelled thermosetting in the products, without adversely affecting the physical properties of the hardened bodies prepared from The regeneration product is therefore not an inert filler, but contributes significantly to saving raw materials based on thermosets. Thanks to the invention, the elimination, in the form of special waste, of waste cons containing non-hardened fibrous thermosets and the waste is sent to judicious reuse. The invention will be explained in more detail by means of the following examples without being limited to these modes of

production.

E x e m p 1 e s

Example 1

  58 kg of stamping waste of glass fiber fabrics impregnated with a phenolic resin with a proportion of resin of 30% by weight are homogenized in a twin screw mixer with 42 kg of chalk and 5 kg of water at a maximum temperature 6 of 80 WC This results in a plastic mass which is

  broken after cooling and ground into granules of less than 200 μm. The regeneration product is reused in Examples 2, 3 and 4.

Example 2

  1.5 kg of regeneration product from Example 1,

  3 kg of phenolic novolac with a softening point of 80 to 85 WC according to DIN 16916, part 1, 0.45 kg of hexamethy-

  lenetetramine, 0.08 kg of magnesium stearate, 0.03 kg of lignite wax, 0.5 kg of softwood flour, 1.5 kg of glass fibers with an average length of 4 mm and 2.94 kg of chalk are intimately premixed and loaded onto cylinders heated to 100-1300 C. The mass is compressed and homogenized into a coherent skin for a rolling time of approximately 3 minutes. The formed skin is transformed into molded bodies according to a

  usual pressing process The physical values of the hardened molded bodies are above the minimum values of type 2 according to DIN 7708.

Example 3

  12.5% by weight of regeneration product of Example 1, 7.75% by weight of mineral fibers, 34.0% by weight of metal shavings, 21.0% by weight of rubber, 2.0% by weight weight of phenolic resin, 2.5% by weight of additives

  friction and 20.25% by weight of filler materials are mixed in a powerful mixer The mixture is pressed

  in the usual way in friction linings at -2 WC and under a pressure of 150 da N cm The hardened and finished friction linings are checked on the bench

  The test results are shown in the table.

  The hardness of the linings is measured according to DIN 50103 (Rockwell hardness) in several places with a half inch ball and a force of 600 N. The linings are all35 in the range of series dispersion from 40 to 80 HRR. Microscope examinations do not reveal changes 7 in the structure of the linings The results of the

  noise in continuous operation at more than 14,000 km does not show any difference in comfort compared to the comparison pads (example 5).

Example 4

  As in Example 3, a mixture of 25.0% by weight of the regeneration product of Example 1, 2.5% by weight of mineral fibers, 34.0% by weight of metal shavings, 21.0% by weight of rubber, 2.5% by weight of friction additives and 15.0% by weight of filler materials is transformed into friction linings The test results are collected in the table The properties of the linings do not present any essential modifications compared to those according to example 3, although the quantity of regeneration product has been doubled and that we have given up

  to additional phenolic resin.

  Example 5 (comparison with Examples 3 and 4) As in Examples 3 and 4, a mixture without regeneration product consisting of 13.0% by weight of mineral fibers, 34.0% by weight of metal chips, 21.0% by weight of rubber, 4.0% by weight of phenolic resin, 2.5% by weight of friction additives and 25.5% by weight of filler materials is transformed into friction linings . The test results are shown in Table 25 with those of Examples 3 and 4. The properties of the packings without regeneration product show no advantage by

  compared to those of fittings containing regeneration product.

  T a b 1 e a u Examples 3 4 5 Coefficient of friction at

 C 0.45 0.44 0.45

200 C 0.43 0.44 0.44

300 C 0.38 0.39 0.38

400 C 0.37 0.39 0.38

  Abrasion (100 stops with TA = 100 C) primary lmm J 0.16 0.14 0.15 secondary lmm J 0.06 0.08 0.06 Rockwell hardness LHRRJ 52 73 50 75 55 77

Example 6

  30 kg of cutting residues from technical filter paper impregnated with resin are homogenized in an extru-

  twin screw deuse with 70 kg of chalk and 3 kg of water at a temperature of 90 ° C. The resulting plastic mass is broken up after cooling and ground into granules smaller than 20 0.5 mm The regeneration product thus obtained is used in Example 7.

Example 7

  8-500 g of a mixture based on magnesia of the most diverse granulations are mixed homogeneously

  with 1000 g of the regeneration product according to the invention coming from example 6 as well as with 500 g of a phenol resol

  70% aqueous liquor (phenol-formaldehyde ratio of 1: 1.55). After compression into molded bodies for the refractory industry, resistance to compaction is obtained.

cold pressure of 89 N / mm.

  The molded bodies bonded by synthetic resin are then heated to a temperature of 180 ° C. and thus hard

  cis They then have such a high resistance that they can be easily transported and integrated in sets For hardened molded bodies, the resistance to

  the cold bending measured is around 20 N / mm and its

  thus meets the requirements of the refractory industry.

O

Claims (4)

Claims   1 Regeneration product from fibers and thermosets, characterized in that it consists of crushed waste of fibrous web structures impregnated and / or coated with thermosets being in an intermediate morphological state and, optionally by materials of inorganic filler. 2 regeneration product according to claim 1, characterized in that the length of the fibers is not greater   laughing at 10 mm, but is preferably between 0.5 and 5 mm.   3 regeneration product according to claim 1 or 2, characterized in that it contains 10 to 50% by weight, -from   preferably 20 to 40% by weight of thermosets relative to the fiber / thermosetting mixture. 15 4 Process for preparing the regeneration product according to one of claims 1 to 3, characterized in that   the waste, possibly after prior grinding, is first subjected to a pretreatment in order to improve the grinding behavior and is then ground so that the fiber length is less than 10 mm.   Method according to claim 4, characterized in that at least one of the following methods is chosen   as a pretreatment a) drying the waste without curing the thermosets   bissible, b) cooling of the waste below the glass transition point of the thermosetting,   c) incorporation by mixing of inorganic filler materials   picnics. 5 Method according to claim 4 or 5, characterized in that during grinding, fillers   inorganics are incorporated into the waste. 7 Use of the regeneration product according to one of claims 1 to 3 as a cured component sand in molding materials.   8 Use of the regeneration product according to one of claims 1 to 3 as a cured component -1.1   sand in masses for friction linings.   9 Use of the regeneration product according to   one of claims 1 to 3 as a cured component   sand in refractory products.