WO1990011978A1

WO1990011978A1 - Cellulosic product, process for the production thereof and uses thereof

Info

Publication number: WO1990011978A1
Application number: PCT/GB1990/000475
Authority: WO
Inventors: Andrew Bickford Hayns
Original assignee: Fosse Limited
Priority date: 1989-03-31
Filing date: 1990-03-30
Publication date: 1990-10-18
Also published as: JPH04506191A; AU5400690A; EP0466760A1; CA2050600A1

Abstract

Cellulosic pulp material is dewatered and/or dried to a water content of up to 20 % by weight. With its dry matter content of up to 55 % by weight of cellulosic fibres and not less than 45 % by weight of inorganic filler particles, the product obtained finds use as such as an extender in horticultural products, as cat litter, inter alia, and, if sufficiently dry and mixed with a binder forms a moulding composition from which shaped products having useful properties and which may be biodegradable are obtainable.

Description

CELLU OSIC PRODUCT. PROCESS FOR THE PRODUCTION THEREOF

AND USES THEREOF This invention relates to a cellulosic product, process for the production thereof and uses thereof. The invention has particular application to the processing of waste from paper mills.

In the United Kingdom alone, over 500,000 tonnes of waste are produced annually from paper mills. The waste is approximately 70% water and 30% dry matter by weight; the latter is made up of approximately equal proportions of clay (from the mineral filler used in paper making) and cellulose fibres.

Although large quantities of this waste have been generated for many years, a satisfactory means of utilising the material has not hitherto been available. Paper makers currently bear the cost of disposing of the material.

EP-B-0039 522 discloses a process for the manufacture of liquid and shock absorbing material from a suspension consisting wholly or substantially of cellulose fibres. The suspension is waste from a manufacturing process in which fibres consisting wholly or substantially of cellulose material are processed by a wet method. The dry matter content of the waste is required to contain 60-80% by weight of cellulose fibres, from 20-40% by weight of inorganic filler and from 0-10% of an admixture which is incorporated to modify the properties of the end product (pellets). The process involves dewatering the initial suspension to a water content in the range of 40-80% by weight and then pelletising the semi-dry mass by squeezing it through one or more narrow apertures. The resultant pellets undergo a drying process. The pelletising and drying conditions are adjusted so that the end product has a bulk density of 150-400 kg/m and a water content of 0.5-10% by weight. The initial dewatering step is preferably such as to give a semi-dry mass containing 55-65% by weight water.

The need to use a starting material consisting substantially of cellulose fibres limits the applicability of the process disclosed in

EP-B-0 039 522 in that the bulk of the waste material produced from paper making is unsuitable by virtue of its high clay (filler) content.

It is an object of this invention to find a use for waste material as such produced from paper making. According to one aspect of this invention, there is provided a material in block or sheet form or in free-flowing particulate form which is a dewatered or dried cellulosic pulp material having a water content in the range of up to 20% by weight and whose dry matter content comprises up to 55% by weight of cellulosic fibres and not less than 45% by weight of inorganic filler particles.

In a second aspect, this invention provides a process for the production of a material according to the first aspect of this invention, which process comprises dewatering an aqueous slurry or sludge containing cellulose fibres and inorganic filler, the resulting product having a dry matter content which comprises up to 55% by weight of cellulosic fibres and not less than 45% by weight of inorganic filler particles and drying the resulting product to a residual water content of up to 20% by weight, which dried product is recovered in block, sheet or free- flowing particulate form.

When the dried product is to be recovered in particulate form, a pelletising step may be caried out before or even after the drying step. Alternatively a dry product in the form of a sheet or block may be comminuted to form a free-flowing meal. A dried product containing above 10% by weight water content is typically grey in colour and has the texture of cotton wool. Hence it may be termed "flock". Such dried product preferably has a moisture content in the range from 10 to 15% by weight. A product with such moisture content, even if only in sheet or block form can be used, with the minimum of breaking up, as an extender, for example in horticultural products, typically in peat-based products.

For many uses, however, the dried product is pelletised or otherwise comminuted, as will be described hereinafter.

The dewatering step is advantageously carried out on a sludge containing cellulose and inorganic filler using a filter press, preferably a screw press. Such sludge is generally to be obtained by flocculation of the slurry obtained in paper production. The final water content of the mass resulting from the dewatering stage is preferably 45-50% by weight. We have found that the "Perrin" Pusher Screw Press manufactured by William R. Perrin, Inc., 432 Monarch Avenue, Ajax,

Ontario, Canada L1S 2G7 works well in the process of this invention.

Unlike the process disclosed in EP-B-0 039 522, the present invention may have a drying step preceding a comminuting step. When drying precedes comminuting or in the more specific case pelletising, the surprising result is obtained that starting materials containing higher proportions of mineral filler are amenable to processing and give useful end products. The aforementioned drying step carried out after dewatering is preferably a flash drying step. Advantageously, the drying step is carried out in an apparatus which simultaneously pulverises and dries further the dewatered feed mass of flock material. Apparatus suitable for this purpose is manufactured by Atr tor Limited, P.O. Box 101, Coventry CV6 5RD, England. The process of this invention is not limited however to the use of this particular apparatus or to any specific means for subdividing the flock.

Alternatively, when lower residual moisture contents are required, in particular in the range of 0.25 to 1% by weight for reasons which will become apparent hereinafter, drying, with or without use of an intermediate flash drying step, is advantageously carried out on a vibrating fluidizing bed or on a rotary louvered dryer.

After the dewatering step, selected additives may be incorporated into the semi-dry mass prior to its entry into the drying phase. Typical additives (which will be selected according to the intended end use of the final product) are colorants, fertilisers, odourants and absorbent.

When pelletising as such is carried out in the process of the present invention, it is preferably carried out using an animal feed pelleting mill or an equivalent mill, so as to produce pellets which, if desired, may then be compressed. The product obtained in this way is useful as cat litter or as hygenic bedding for the broiler industry.

Suitably divided very dry material (generally 0.25 to 1% by weight water content) has been found to have additional important uses. By for example incorporating a resin into the material fed to the drying stage, a final product can be obtained which is suitable for shaping. This resin may be biodegradable and may be starch derived. In any case it will generally be present only in minor amount. A product can thus be obtained which is suitable for example for shaping into plant pots which because of their constitution can be set in earth as such with a plant therein, there is no need to remove the pot and discard it when planting. Thus, according to a third aspect of the invention, there is provided a moulding composition comprising an intimate mixture comprising (a) dried or dewatered cellulosic pulp having a dry matter content of up to 60% by weight cellulose fibres and at least

40% by weight inorganic filler and containing little or no water, and (b) a binder, the binder constituting at least 2% by weight of the composition.

The binder is preferably a synthetic resin. For many products, it will be sufficient to use scrap polymer as binder. If the proportion of pulp residue present in the material with which the binder is blended is high (50% or more by weight) the polymer should be in finely divided form. The binder is advantageously present in an amount of at least 5% by weight of the composition. For many applications, a binder content in the range from 10-60% by weight will be acceptable. Preferred binder contents are in the range 10-30% by weight; moulding compositions of the invention having a binder content in this range are exceptional in that they are suitable for injection moulding, despite the very high filler content.

Both thermoplastic and thermosetting resins may be used as synthetic resin binder. The presently preferred thermoplastic resin binder materials are for example low density polyethylene (LDPE), polypropylene (PP), ethylene-propylene copolymers, acrylonitrile-butadiene-styrene copolymers, polyamides, especially nylon, in particular nylon-6, and thermoplastic rubbers. LDPE and PP are preferred because of melting ranges.

Thermosetting resins which may be employed include urea/formaldehyde, phenolic, polyurethane, polyisocyanurate, polyurea, polyester, epoxy and bismaleimide resins as well as polyamide casting systems, e.g. Nyrim (Registered Trade Mark). The _*

-6- resin forming material in general may be fixed with the cellulose-containing material either before drying or after drying thereof to a suitable state for moulding. The character of the thermosetting system to be employed will determine the stage at which mixing with cellulose-containing material which is to be dried, is being dried or has been dried is to occur and the material to be then mixed with such material. Some systems will generally require a peroxide or other catalyst and the character of the system will depend upon how it is constituted. Thus, when unsaturated polymers or cross-linkable monomers are to be cured in situ using a peroxide or other catalyst, for example when using unsaturated polyesters, acrylics and allyl resins, it is necessary to consider two-pack systems with catalyst only being introduced prior to the moulding stage. Where catalysts are only activated at high temperatures, for example above 150°C, a "two- pack" approach is not required. Such situation applies to such general thermosetting materials as phenolic resins, urea-formaldehyde resins, melamine-formaldehyde resins, polyester sheet moulding compounds (SMC) and dough moulding compounds (DMC).

The mixing of additives into a composition containing large quantities of pulp residue will generally require a dough mixer or planetary mixer owing to the viscosities involved. The high viscosities resulting from the presence of large quantities of pulp residue (i.e. more than 30%) in the compositions will also prevent the processing of these compositions by traditional casting techniques. Should relatively high pressures be necessary to ensure adequate filling of moulds, compression moulding is therefore a suitable technique to adopt. Alternatively, injection moulding may be feasible, although its use will be limited to lower melting polymer-containing moulding compositions as too high a temperature will induce degradation of the cellulose. A preferred moulding composition according to a fourth aspect of the invention is an injection moulding composition which comprises an intimate mixture derived from (a) dried or dewatered pulp obtained as a waste product from a paper making process, the pulp containing, as dry material, up to 60% by weight cellulose fibres and not less than 40% by weight inorganic filler and containing little or no water; and (b) a thermoplastic resin, e.g. low density polyethylene, the resin constituting at least 5% by weight of the composition.

Compression moulding of compositions embodying the invention works satisfactorily over a wide range of binder contents in the composition. It is possible to form articles from preferred compositions in accordance with the invention by injection moulding even at relatively low binder contents. Injection moulding of materials conventionally requires a considerable proportion of binder to be present in order for the injection moulding to work satisfactorily. We have found that successful injection moulding runs can be achieved with compositions of this invention with a binder content (specifically, but not necessarily only with low density polyethylene) as low as 5% by weight of this composition and generally as low as 10% by weight.

If desired, one or more additives may be incorporated into a moulding composition in accordance with this invention, typically in relatively small amounts, e.g. up to about 10% by weight of the composition. Such additives include fire retardants, colorants, water repellants and other conventional ingredients. Moulding compositions embodying this invention like the aforementioned "flock" and similar material are hygroscopic and need to be bagged as soon as possible after their production. However, moulded products produced therefrom, as a result of the effect of the binder, are less hygroscopic. For use in forming a moulding composition of this invention, the waste from paper making is preferably dried directly to a very low water content after being subjected to preliminary dewatering. Thereafter the dried pulp can be mixed intimately with a binder, typically a resin, to form the moulding composition of this invention. Mixing with binder is preferably carried out using a Z-blade mixer or a planetary mixer and/or by feeding the starting materials for producing the moulding composition through an extruder. More homogenous mixing can be achieved if an initial Z-blade mixing process is followed by one or two passes through an extruder, e.g. a Betol extruder. It is convenient for the dried cellulosic pulp to be in the form of pellets or granules as it is supplied to the mixing process. Granulation of air dried pulp may be carried out in a Christy Norris Spruemaster granulator which can be fitted with different size sieves to control crumb size. If mixing with binder takes place at an early stage in the drying, cellulose containing waste whose water content is still as high as 40% by weight may be contemplated. Such cellulose-containing material will however have a bulk which is disadvantageous; mixing of the flock with the binder is less convenient than using dried granules or pellets. Moreover the presence of substantial amounts of water produces vapour problems in an extruder used for mixing and in subsequent moulding equipment.

When the compounding of pulp residue with binder comprises an extrusion technique, compounding can be successfully carried out in a conventional twin-screw compounding extruder. For low density polyethylene, barrel temperatures in the region of 150-160°C and die temperatures around 170°C can be used. The extrudate itself can be pelletised. To obtain a completely uniform product, overall intensive mixing is required and this may be achieved by (a) passing the extrudate through the extruder a second time or (b) fitting a cavity transfer mixer between the barrel and the die or (c) using a specialised compounding machine, e.g. Bus Ko-Kneader. Polymers which have high melt temperatures may cause difficulties as the cellulose fibres present can degrade. For example, nylon-6 having a melting point of about 215°C can only be blended with cellulose- containing material provided that the residence time of the mix in the barrel of an extruder is kept as short as possible. No problem in this respect is achieved with polypropylene which has a melting point of about 170°C.

Pulp residue containing injection moulding compositions mould easily. The pulp residue appears to have a lubricating effect. However, when high filler and fibre contents are employed (greater than 50% by weight of pulp residue), difficulties may be encountered in injection moulding of thin sections. Moulding compositions containing pulp residue mould more easily than compositions containing similar levels of more conventional fillers. In some embodiments of the invention, one or more conventional fillers may be incorporated into a moulding composition according to this invention. Such fillers include powders, glass, wood, fibre, talc and whiting; the inclusion of these additional fillers may be deleterious if the composition is to be injected moulded. Higher filler loadings are possible with pulp residue than conventional fillers such as glass fibre, whiting, china clay etc. used as sole source of filler. Although the use of cellulosic pulp in the practice of this invention is mainly described herein with reference to utilization of paper mill waste, pulped waste paper can also be as an alternative or in addition thereto.

The following examples illustrate the invention. In the examples, reference will be made to the accompanying drawing. The term "flock" is used in the examples to denote feedstock containing cellulose and filler with which binder is mixed.

EXAMPLE 1 Waste from a paper mill is supplied at 1 to a screw press 2. The waste contained dry matter consisting, by weight of 50% inorganic filler (clay) and 50% cellulose fibres. The solid matter content of the waste was approximately 30% by weight. The output of the screw press (at 3) had a moisture content of about 45% by weight. This partially dewatered material was supplied to a flash dryer 4, which was an "Atritor dry r-pulveriser" manufactured by Atritor Limited of

Coventry, England. The output from dryer 4 was a grey fluffy material with a low water content. In one embodiment of the invention, this material may be used directly as a drying or absorbing agent or as an extender, e.g. for horticultural composts.

In another embodiment, the output at 5 from the dryer 4 is fed to the input 6 of the pelletising press. This may be a conventional pelletising press of the type used for pelletising animal feed. The pelletised product passes (at 8) to a two-stage packing plant 9, 10.

If desired, additives may be incorporated into the feed stock at the input to the flash dryer 4.

The final, pelletised product may be used as cat litter, or for other applications where good liquid absorbing and/or shock-absorbing products are required. The product may also be used in the production of moulding compositions when its moisture content is reduced further.

EXAMPLE 2 The procedure of Example 1 was modified in that using a "Perrin" Pusher Screw Press, the starting sludge was initially dewatered to around 50% dry weight. The output from the screw press was fed to a "Atritor" dryer-pulveriser which reduced the water content of the material to approximately 30%. The resultant grey flock product was then dried to substantially complete dryness in an oven at 110°C. At the end of this process, the dry cellulosic flock contained only 0.6% by weight of water. The dry flock was then mixed in a Kenwood planetary mixer with a commercially available low density polyethylene (LDllO manufactured by Plascoat Systems) for three minutes. In a first run, 124 parts by weight of the dry flock were mixed with 16 parts by weight low density polyethylene, this corresponding to 11.4% by weight resin in the composition (dry weight). The mixture obtained in the planetary mixer was then passed twice through a Betol extruder. The resultant intimate mixture was then used to form injection moulded pots using a Daniels Press operating at 180°C. The resulting product was easily demouldable and had a smooth uniform glossy dark grey appearance.

A second sample of the dry flock was treated in the same way as described above, except that the mixture supplied to the planetary mixer consisted of 138 parts by weight dry flock and 40 parts by weight low density polyethylene (LDllO). This corresponds to 22.5% by weight resin in the composition (dry weight). As with the previous sample, injection moulding produced a satisfactory product with no processing difficulties. EXAMPLE 3 Following the procedure of Example 2, further injection moulded products containing pulp residue and low density polyethylene were produced, the contents of flock (dry weight) in the moulding produced amounting to 50, 65 and 85% by weight. For comparison, a moulding was produced from the low density polyethylene alone.

The properties of the products thus obtained were then investigated. Firstly strength and modulus values were determined and yielded the following values:-

TABLE 1

Property % Flock in Compound

0 50 65 85

Flexural Strength No failure 17.1 16.4 10.8

Mpa

Flexural Modulus 0.24-0.33 1.3 1.69 2.5

GPa

Tensile Strength 8.3-31.4 4.97 8.84 5.97 MPa

As with the flexural and tensile properties, the intensity of mixing and the moulding conditions will considerably influence the impact properties. In particular, the impact strength will be subject to greater variability if mixing has not been intensive. All the -aforementioned samples were mixed under the same conditions and they were subjected to impact test measurement which yielded the following results:- TABLE 2

% Pulp Residue 0% 50% 65% 85%

Impact KJ/m² No break 4.4 5.4 6.5 Izod Test

The moulded articles were all subjected to working following woodworking techniques, for example, drilling, nailing, screwing and sawing, and no problems were encountered when the pulp residue constituted 50- 85% by weight of the moulding.

The incorporation of flock enhances the fire resistance of polyethylene moulded bodies which will not melt, drip or lose integrity in the same manner as unmodified polyethylene when pulp residues are high, e.g. 85-80%. However the compositions still burn and are not self extinguishing. Further tests were carried out on the aforementioned mouldings, which, being relatively porous, can absorb significant amounts of water or solvents. Mouldings containing high levels of pulp residue are most affected as shown by the following results:-

TABLE 3

% Pulp-Residue % by wt. of water absorbed by immersion in moulding 24 hr. 1 week 1 month 2 months

0 <0.01 NA NA NA 50 1. 1 3.0 6.3 8. 4 65 1.5 4.2 8.9 10.2 85 2. 6 8. 5 12. 1 12.3

NA - Not available

If the moulding compositions are not uniformly compounded, this may lead to warping. Significant dimensional changes may occur in humid environments owing to water uptake. Water may extract material from the mouldings during prolonged immersion as suggested by the following results:-

TABLE 4

% pulp Residue 50 65 85 in moulding

% extracted after <.l <.l 1.5 2 months immersion in water

Comparable experiments carried out using an organic solvent (petrol) showed the extent to which it may also be absorbed by pulp residue/polyethylene mouldings or extracts material from such mouldings. TABLE 5

% Pulp Residue % by wt. of petrol absorbed by immersion in moulding 48 hr. 1 week 1 month 2 months

50 6.2 7.1 7.3 7.7 65 5.9 6.5 6.4 7.0 85 3.3 3.1 3.2 3.7

TABLE 6

% Pulp Residue 50 65 85 in moulding

% by wt. material NA 1.9 2.6 4.8 extracted in 2 months

In each of the following examples, there was used a pulp residue from a waste paper mill which had been dewatered and dried to a residual water content of less than 1% by weight, the pulp residue having a dry weight composition of 50% cellulose and 50% clay.

EXAMPLE 4

100 grams of dried pulp residue were placed in the mixing chamber of a small planetary mixer followed by 47.5g of epoxy resin (Epikote 828, Shell Chemicals). The curing agent, 2.5g of benzyl dimethylamine, was added over a 5 minute period and mixed in for a further 15 minutes. This was designated Compound A.

A portion of Compound A was pressed in a steel mould at 80°C to produce sheet mouldings approximately 1.2mm X 115mm X 115mm. A pressure of approximately 900kg was applied to the mould and the moulding was removed after 15 minutes. The product was a hard, rigid sheet.

A second portion of Compound A was pressed in a different steel mould at 80/100°C for 30 minutes to produce a sheet 2.7mm X 115mm. A pressure of approximately 900kg was applied to the mould. The product was a hard, black, rigid sheet.

When Compound A was left overnight before use unsatisfactory mouldings were produced owing to moisture uptake.

EXAMPLE 5 4 grams of phthalic anhydride were dissolved in 50 grams of acetone and this was mixed into 45 grams pulp residue using a small planetary mixture. Then 10 grams of an epoxy resin (Epikote 828 from Shell Chemicals) was mixed in. The mixture was spread out on a tray to allow most of the acetone to evaporate. This took approximately 1 hour. This was designated Compound B. A portion of Compound B was then pressed in 115mm X 1.2mm sheet mould for 1 hour at 150°C. The product was a hard rigid black sheet.

If Compound B was left overnight before use unsatisfactory mouldings were produced owing to moisture uptake.

EXAMPLE 6 lOOg of dried pulp residue were placed in the mixing vessel of a small planetary mixer. Then a premix of 20g linear polyether diol (Desmophen 1900 from Bayer UK), 0.01 dibutyl tin dilaurate and 0.05g of a 33% solution of triethylene diamine in polyethylene glycol molecular weight 200 was prepared. This premix was mixed into the pulp residue for 30 minutes. Then 27.4g of polymeric diphenylmethane diisocyanate (Suprasec DND from ICI) were mixed in for 20 minutes. This was designated Compound D. The amount of isocyanate and polyether used were such that an excess of isocyanate was present. A portion of Compound C was immediately pressed at 80/100°C in a 115mm X 115mm X 1.2mm sheet mould. A pressure reading of 2000psi (13790 kpa) was used for 20 minutes . The product was a tough rigid sheet.

Approximately 30 minutes after mixing, a portion of Compound C was pressed at 80 to 100°C in a 115mm X 115mm X 2.7mm sheet mould. A pressure reading of 2000psi (13790 kpa) was used for 100 minutes, This product was a tough rigid sheet.

If Compound C was left overnight before use, unsatisfactory mouldings resulted.

EXAMPLE 7 lOOg of dried pulp residue and a pre-mix of 50g Desmophen 1900, O.lg of a 33% solution of triethylene diamine in polyethylene glycol of molecular weight 200 and 0.03 dibutyl tin dilaurate were mixed on a planetary mixer before mixing in 7.8g Suprasec DND. This was designated Compound D. A portion of Compound D was compression moulded as in Examples 4 and 5. The compression moulded sheets were soft and exuded traces of unreacted polyether diol. The amounts of isocyanate and polyether used were of stoichiometric equivalent molar quantities.

EXAMPLE 8

100g of dried pulp residue were mixed with 34g of a pre-mix of 68% Desmophen 1200 (a branched polyester polyol), 0.02g dibutyl tin dilaurate and 0.08g of a 33% solution of triethylene diamine in polyethylene glycol (m.w. 200). This was carried out in a planetary mixer over a 1 hour period. Then 14g Suprasec DND were added and mixed in over 15 minutes. This was designated Compound E. The products were pressed into sheets as in Example 6.

The sheets were hard, rigid and black. An improvement had been brought about by using a more reactive polyol with a branched structure. Also, though equivalent amounts of polyester polyol and isocyanate were used, the formulation contained a higher percentage of isocyanate and was better able to tolerate trace quantities of water.

Claims

CLAIMS :

1. A material in block or sheet form or in free- flowing particulate form which is a dewatered or dried cellulosic pulp material having a water content in the range of up to 20% by weight and whose dry matter content comprises up to 55% by weight of cellulosic fibres and not less than 45% by weight of inorganic filler particles.

2. A material as claimed in claim 1, having a water content in the range of from 10 to 15% by weight and having the texture of cotton wool.

3. A material as claimed in claim 1, having a water content in the range from 0.25 to 1% by weight.

4. A material as claimed in claim 2 or 3 which is in the form of pellets.

5. A material as claimed in claim 3 which is in the form of a granulate.

6. A process for the production of a material according to claim 1, 2 or 3, which comprises dewatering an aqueous slurry or sludge containing cellulose fibres and inorganic filler, the resulting product having a dry matter content which comprises up to 55% by weight of cellulosic fibres and not less than 45% by weight of inorganic filler particles, and drying the resulting product to a residual water content of up to 20% by weight, which dried product is recovered in block, sheet or free-flowing particulate form.

7. A process as claimed in claim 6, which comprises pelletising the material before or after said drying.

8. A process as claimed in claim 6 or 7, whose product is subjected to granulation.

9. A process as claimed in any one of claims 6 to 8, wherein said drying is carried out by flash drying and/or on a vibrating fluidizing bed and/or a rotary louvred dryer.

10. A process as claimed in any one of claims 6 to 9, wherein the dewatering is carried out to a water content of from 45 to 50% by weight.

11. A moulding composition comprising an intimate mixture comprising (a) dried or dewatered cellulosic pulp having a dry matter content of up to 60% by weight of cellulose fibres and at least 40% by weight inorganic filler and containing little or no water and (b) a binder, the binder constituting at least 2% by weight of the composition.

12. A moulding composition as claimed in claim 11, having a resin binder content in the range of from 10 to 60% by weight.

13. A moulding composition as claimed in claim 11 or 12, comprising a thermoplastic resin binder selected from low density polyethylene, polypropylene, ethylene- propylene copolymers, acrylonitrile-butadiene-styrene copolymers, polyamides and thermoplastic rubbers.

14. A moulding composition as claimed in claim 11 or 12, comprising a thermosetting resin or precursors thereof, selected from urea-formaldehyde, phenolic, polyurethane, polyisocyanurate, polyurea, polyester, epoxy and bismaleimide resins.

15. An injection moulding composition which comprises an intimate mixture derived from (a) dried or dewatered pulp, the pulp containing as dry material up to 60% by weight cellulose fibres and not less than 40% by weight inorganic filler and containing little or no water; and (b) a thermoplastic resin, the resin constituting at least 5% by weight of the composition.

16. A moulding composition as claimed in claim 15, wherein the thermoplastic resin is low density polyethylene.

17. A moulding composition as claimed in claim 15 or 16, wherein the pulp is obtained as a waste product from a paper making process.

18. A process for producing a shaped product which comprises compression moulding a moulding composition as claimed in any one of claims 11 to 14.

19. A process for the production of a shaped product which comprises injection moulding a composition as claimed in any one of claims 11 and 15 to 17.