IE42654B1 - Sheets or moulded bodies - Google Patents

Abstract

A compound of lignocellulose material mixed with a binder is hot-pressed. The binder used is an aqueous emulsion of organic polyisocyanate. This emulsion contains a nonionic surfactant that is free of hydroxyl, amino and carboxyl groups. The emulsions have a polyisocyanate content of up to 65%. The hot pressing can take place at temperatures as low as below 100 DEG C. The process is used with reference to producing board, for example chipboard.

Description

PATENT APPLICATION BY (71) IMPERIAL CHEMICAL INDUSTRIES LIMITED, A BRlTISt COMPANY, OF IMPERIAL CHEMICAL HOUSE, MILLBANK, LONDON S.W.I., ENGLAND.

Putt 12ip This invention relates to a process for manufacturing sheets or moulded bodies.

Composite boards and flat sheets or moulded bodies are commonly prepared by hot pressing of a mass of wood chips, wood fibres or other lignocellulosic material mixed with binding agents, particularly solutions of urea-formaldehyde or phenol-formaldehyde resins. Pressing temperatures are usually from 15G to 22O°C otherwise adequate adhesion does not occur in an acceptable time even at the high pressures {20 to 70 kilograms force per square centimetre fkgf/cm^j) which are normally used.

It is known to use isocyanate solutions as binding agents for chipboard in place of the urea-formaldehyde or phenol-formaldehyde resins. - 2 According to the present invention a process for manufacturing sheets or moulded bodies comprises hot pressing of a mass of lignoceilulosic material mixed with a binding agent comprising an aqueous emulsion of an organic polyisocyanate containing a non-ionic surface active agent devoid of hydroxy, amino and carboxylic acid groups.

Lignoceilulosic material which can be used in the process includes wood chips, wood fibres, shavings, wood wool, cork and bark, sawdust and like waste products from the woodworking industry, and/or fibres from other natural products which are lignoceilulosic, for example, begasse, straw, flax residues and dried rushes, reeds and grasses. Additionally, there may be mixed together with the lignoceilulosic materials inorganic flake or fibrous material e.g. glass fibre, mica or asbestos.

Organic polyisocyanates include di-isocyanates, particularly aromatic di-socyanates, and isocyanates of higher functionality.

Examples of organic polyisocyanates which may be used in the process of the invention include aliphatic isocyanates such as hexamethylene diiocyanate, aromatic isocyanates such as m- and £ - phenylene di isocyanate, tolylene -2,4-and 2,6di isocyanate, diphenylmethane-4,4’-diisocyanate, chlorophenylene2, 4-dii.socyanate, naphthylene-1,5-diisocyanate, diphenylene4,4 *-diisocyanate, 4,4’“diisocyanate-2,3’-dimethyldiphenyl, 3-methyldiphenylmethane-4,4’-diisocyanate and diphenyl ether diisocyanate, cycloaliphatic diisocyanates such as cyclohexane2,4- and 2,3-diisocyanates, 1-methyl cyclohexyl-2,4- and 2,6diisocyanates and mixtures thereof and bis-(isocyanatocyclohexyl-) methane and tri-isocyanates such as 2,4,6-triisocyanatotoluene and ... 2,4,4,-briisocyanabodiphenylether. 2 6 o 'i Mixtures of isocyanates may be used, for example a mixture of tolylene diisoeyanate isomers such as the commercial available mixtures of 2,4 and 2,6-isomers and also the mixture 5 of di- and higher poly-isocyanates produced by phosgenation o'f aniline/formaldehyde condensates. Such mixtures are well-known in the art and include the crude phosgenation products containing mixtures of methylene I bridged polyphenyl polyisocyanates, including diisoeyanate, triisocyanate and higher polyisocyanates together with any phosgenation by-products.

Preferred polyisocyanates to be Used'in the present invention are those wherein the isocyanate is an aromatic diisoeyanate or polyisocyanate of higher functionality in particular crude mixtures of methylene bridged polyphenyl polyisocyanates containing diisocyanates, triisocyanate and higher functionality polyisocyanates. Methylene bridged polyphenyl polyisocyanates are well Jcnown in tho art and have the generic formula: where n is one or more and in the case of the crude mixtures represents an average of more than one. They are prepared by phosgenation of corresponding mixtures of polyamines obtained by condensation of aniline and formaldehyde. For convenience, crude mixtur of methylene bridged polyphenyl polyisocyanates containing diisoeyanate, triisocyanate and higher functionality polyisocyanates are referred to hereinafter as MDI.

Especially preferred organic isocyanates which can be used in the invention include isocyanate-ended prepolymers made by - 4 42654 reaction of an excess of a diisocyanate or higher functionality polyisocyanate with a hydroxyl-ended polyester or hydroxyl-ended polyether and products obtained by reacting an excess of diisocyanate or higher functionality polyisocyanate with a monomeric polyol or mixture of monomeric polyols such as ethylene glycol, trimethylol propane or butane-diol. Of particular value, however, because of their slower reaction with water, a desideratum hereinafter discussed, are isocyanate-ended prepolymers prepared using, hydrophobic polyols such as castor oil.

One class of isocyanate-ended prepolymers which may be used are the isocyanate-ended prepolymers of MDI.

The aqueous emulsion of organic polyisocyanate used in the process of the invention contains a non-ionic surface active agent devoid of hydroxy, amino and carboxylic acid ή5 groups, for example condensates of ethylene oxide molecules which are devoid of chain-end hydroxy, amino or carboxylic acid groups.

These include for example condensates of ethylene oxide with alkyl phenols, long chain alcohols or amides, wherein in each case the end-hydroxy group is for example etherified or esterified. 2o °f particular value are the reaction products of diisocyanates and higher functionality polyisocyanates with monoalkyl ethers of polyethylene glycols. These particular surface active agents or emulsifying agents have the formula: RO(CHCHO) CONHX 2 2 Ii 2$ wherein R is an alkyl group of from 1 to 4 carbon atoms, n is an integer such that the compound contains an average of at least 5-oxy - 5 42654 ethylene groups and X is the residue of a di or polyisocyanate and contains at least one free isocyanate group. Examples of R. include ethyl, propyl and butyl, preferably methyl. There must be sufficient oxyethylene groups (CK^CH^O) present in the surface active urethane that there is an average of at least 5 such groups per molecule. It is preferred that n represents an average of from 5 io 120 and especially from 10 to 25< The group X is the residue which would remain after one isocyanate group had been removed. The group’ X may be the residue of any diisocyanate or higher polyisocyanate and for example if the diisocyanate is a tolylene diisocyanate the residue X will be NCO Isocyanates from which the group X can be derived include the di- and poly-isocyanates listed above.

Such surface active urethanes may be manufactured by 15 reacting an alcohol of the formula ROiCH^CH^Oj^H with an isocyanate having at least two isocyanate groups, there being used at least one molar- proportion of isocyanate for each molar proportion of the alcohol. Preferably an excess of the isocyanate is U6ed.

The reaction may be carried out by adding the alcohol 20 to the isocyanate with stirring until clear and allowing the reaction to proceed, at room temperature. She reaction may be accelerated by heating at temperatures up to 100°C. - 6 42654 In order to obtain tho emulsions used in the present invention, the above type of surface active agent may be prepared in situ in the isocyanate. Thus if it ie desired to produce an emulsion of an isocyanate of the formula X(NC0)2 a small amount of the polyethenoxy alcohol HOiCHgCH^O)^ may be added to a large excess of the isocyanate XCNCO)^ and tho emulsifying agent formed ia situ in the isocyanate.

In the cases where the polyisocyanate is a prepolymer, formation of the prepolymer and an in situ surfactant may be carried out simultaneously or as two separate steps and the prepolymer/ surfactant then mixed with water to give the emulsified prepolymer. Emulsification is facilitated by initially mixing the prepolymer/ surfactant with about one quarter of its own weight of water and then diluting with more water as required.

Thue when the polyisocyanate present in the emulsion is to be one of the class of preferred prepolymers mentioned hereinbefore, namely a prepolymer of MDI, the emulsion of the prepolymer may be made by any of the following three methods: (1) Reaction of the MDI with the required amount of polyol to give the prepolymer followed by reaction with a small amount of the polyethenoxy alcohol CH^OfCH^CHgO)^ followed by emulsification by agitation with water. (2) Reaction of the MDI with the required small amount of the polyethenoxy alcohol CHjO(CH2CI!2O)nH followed by roaction with the amount of polyol required to give the prepolymer followed by - 7 4 2 6 5 4 emulsification. (3) Reaction of the MDI with the required amounts of polyol and polyethenoxy alcohol simultaneously followed by emulsification in water.

In the above three methods the preparation of the surfactant is carried out in situ in the polyisocyanate, the surfactant being of the general formula RO RX where X is the residue of the isocyanate and R is an alkyl group of from 1 to 4 carbon atoms.

Preferred surfactants are those derived from the polyethenoxy compound RO(CH2CH2O)nH wherein R is methyl and n is an average of from 10 to 25. Typical examples of the polyethenoxy compounds are methoxypolyethylene glycols of molecular weight of 300 to 1000.

The surfactant can of course be prepared separately and a small amount dissolved in the prepolymer-forming mixture or in the preformed prepolymer.

Formation of the prepolymers can be carried out by any of the known methods, i.e. by heating the components together or by allowing them to react at ambient temperature optionally in the presence of catalysts.

The emulsions of the prepolymers prepared by the methods described above are oil-in-water emulsions.

A further type of surface active agent which may be utilised is that which has the general formula: X - NHCOCH COCHCHjCH^hR1 COO(CH2CH2O) r1 wherein X is the residue of an organic isocyanate, R''- is an alkyl group of from 1 to 4 carbon atoms, n and m are integers such that m + n is at least 10 and R which is only present when X represents the residue of a diisocyanate or a higher functionality polyisocyanate, is an isocyanate group or a group of the formula: - NHCOCH COOiCH^^O^R1 COO (CH2CH2O) ^1 r1 is preferably methyl and the sum of m and n is preferably between 20 and 80.When X represents the residue of a monoisocyanate the group R is absent.

X may for example be the residue of any of the isocyanates listed earlier In this specification. 2 6 5 4 These surface active agents or emulsifiers may be made hy reaction of an isocyanate with a bis(alkoxy polyethenoxy) ester of malonic acid, and may if'desired be prepared in situ in the isocyanate.

Preferred emulsions for use in the present invention are those in which from 99 to 25 parts by weight of water are associated with from 1 part to 75 parts by weight of organic polyisocyanate per 100 parts by weight of water and organic polyisocyanate,(especially those in which 75 to 50 parts by weight of water are associated with 25 to 50 parts by weight of organic isocyanato per 100 parts hy weight of water and organic polyisocyanate). A preferred amount of the surface active agent is from 5 parts to 15 parts by weight based on 100 parts by weight of the isocyanate.

The emulsions can be prepared by conventional methods, preferably by mixing the emulsifying agent with the organic polyisocyanate and mixing this mixture with water. Alternatively in some cases the non-ionic surface active agent can be prepared in situ in the polyisocyanate and this product, diluted if desired with further polyisocyanate, mixed with water and the whole agitated to obtain the desired emulsion.

To carry out the process of the invention the lignocellulosic material is mixed with the binding agent, desirable by spraying it finely with the aqueous emulsion so as to produce good coverage It has been found that aqueous emulsions of the organic polyisocyanates are of sufficiently low viscosity to be sprayed at strengths of up to 65%, whereas the solutions of ureaformaldehyde and phenol-formaldehyde resins nornally use.d - 10 42654 in manufacture of chipboard and like materials are not normally sprayable at strengths above Ao%. Ihus the invention provides a means of operation in which less water is present than has hitherto been possible, so that less water needs to be expelled during the hot pressing stage or subsequent conditioning. Alternatively, the lignocellulosic material need not be dried to the hitherto normal extent before mixing with the binding agent. Bie use of warm water and/or organic polyisocyanate may facilitate emulsification and spraying.

It has further been found that the hot pressing stage in the process of the invention can be effectively operated at temperature^ below 100°C (e.g. at 90 to 95°c) instead of the usual 150 to 220°0 used with urea-formaldehyde and phenol-formaldehyde resins. Ihe use of such lower temperatures saves energy, reduces environmental discomfort, and eliminates fumes. It is also advantageous because it avoids the disruptive influence of steam pressures generated internally within sheets or moulded articles made at the higher temperatures, particularly important in the manufacture of laminates having impermeable facings. Improved consolidation can therefore be obtained during the pressing stage because it is no longer necessary to leave sufficient permeability for steam to escape.

Ihe more conventional higher temperatures may of course still be used and may in fact be desirable in certain circumstances, eince they give rise to shorter curing times and tend to promote improved release of the chipboard from the press platens. -11-. /136 5 4 This latter consideration may be of importance where unfaced sheets are to be produced.

In a preferred form therefore the invention provides a process for manufacturing sheets Or moulded bodies which comprises spraying lignocellulosic material with an aqueous emulsion of an organic polyisocyanate, desirably an isocyanateended prepolymer of a crude mixture of methylene bridged polyphenyl polyisocyanates, said aqueous emulsion containing a stabilising proportion of non-ionic surface agent devoid of hydroxy, amino and carboxylic acid groups and having 75 to 50 parts by weight of water associated with 25 to 50 parts by weight of the organic polyisocyanate per 100 parts by weight of water and organic polyisocyanate, optionally drying at 20 to 40°C to remove a portion of the water and hot pressing the sprayed lignified raw material at a temperature below 200°C, and especially below 100°C, particularly 9O-95°C, to effect cohesion.

By this means strongly bonded sheets or moulded bodies are obtainable economically.

In practice, there will inevitably be periods of delay between the stages of preparing the emulsion, spraying the lignocellulosic material and hot pressing the sprayed material, and delays also arising from clearing processing faults and making operational adjustments. Desirably the reaction between the isocyanate and water of the emulsion will be sufficiently slow that a delay of, say, two hours between preparing the emulsion and hot pressing can be tolerated. The reaction rate can be slowed down to provide an emulsion having an acceptable working life by using less surface active agent or by using a less efficient agent but 2 6 5 4 either of these courses adversely influences the stability of the binder and distribution of the isocyanate over the lignocellulosic material in addition to causing spraying difficulties. It is preferable therefore to slow down the reaction rate by using an isocyanate-ended prepolymer derived from a hydrophobic polyol, as already mentioned, and/or by including in the emulsion an inert hydrophobic diluent which may also provide benefits in terms of improving the water repellent nature of the resultant chipboard and assisting release of the chipboard from the press platens. Suitable diluents are fatty hydrocarbons, aromatic and aliphatic, and esters, optionally containing a halogen substituent. As examples we mention, mineral oil and slack wax(impure paraffin wax), didodecyl phthalate, tris-β-chloropropylphosphate and, in particular, chlorinated paraffin waxes. These diluents, which are not reactive towards isocyanate groups, may be added during the preparation of the prepolymer or just prior to emulsification.

The invention is illustrated by the following Examples in which all parts and percentages are by weight unless otherwise stated.

Example 1 320 g of wood chips were dried to a moisture content of 6%. They were placed in an open mixer bowl and whilst being tumbled bonding agent fluid was sprayed in by means of a sirfiple hand operated spray, the amount applied being controlled by reference to the loss in weight. Agitation of the sprayed chips was continued for 1 minute after which they were sprinkled evenly over the area of l8 cm x l8 cm in a mould box. The mass was then compressed manually as much as possible after fitting a - 13 5 42854 similar sized upper plate thus producing a looselyconsolidated mat of chips about 4-2-5 cm thick. The mat was transferred on to release treated metal plates and placed in a hydraulic press where it was compressed using a pressure of 50 Icgf/cm^ between platens at 90-95^0 for 5 minutes. A clearance plate of 1.4 cm was used to restrict the density to about 0.7 SG. After removal the boards were conditioned to obtain the water content at about 10% and physical testing was carried out on the representative 15 cm x 15 cm central region of the resultant pieces of board.

A comparison was made as bonding agent of emulsions based on emulsifiable MDI and emulsifiable MDI prepolymer.

The emulsifiable MDI contained: MDI 100 parts Methoxy polyethylene glycol (Methoxy PEG) 10 parts The emulsifiable MDI prepolymer contained: MDI 100 parts Oxypropylated glycerol MW 1000 30 parts Methoxy polyethylene glycol (Methoxy PEG) MW 650 10 parts Each was emulsified by mixing with half its weight of water followed by its own weight of water to thus produce emulsions with 40% solids” content. 40 g of these emulsions were used in spraying onto 320 g batches of wood chips as described above.

The boards both displayed good cure at removal from the press and at this temperature there was produced no visible steam or fumes and no swelling was observed when removed from the press. •12 6 5 4 Λ similar pair of tests was made using half quantities of the emulsions to give only 2¾% solids as bonding agent on the weight of chips.

Physical properties by tests described in BS 1811 part 2 were as follows :EMDI = emulsifiable MD1 EMDIPP = emulsifiable MD1 prepolymer 43654 PM P< H 8 C- in + tn t- VO Ch in • co t“ o in « o CM -d* VO co V s- CM IS t o n- • Ov CS tn • v co tn • tn s cv. O in l-l V o VO in tn CM VO VO r· .+ * 4* • « . · • rn o o K\ Jf o CO « n- CM • in -d* • $ VO & CS r· V r· o in CM o n- CM tn -± Πι co -d· CM PM IS ch in » ch Γ” o & M ch + VO • co co + .& • n. Jf g w tn « CM • o tn • VO CM KO V 00 in o in ύ ¢- r~ Γ* V tn H VO V vo m -d* co rtf O o t VO • VO • tn CS VO o in -d· « -d· Ch «? • r~ rtf • o VO as* vo T” ch w o Ch tn o r- r r V CM X X X X X X Φ to 0 ω 3 φ Φ fi φ Φ CM fi ω fi *9 CM o ra φ o ra Φ 1 B fi •rt o fi a .9 Φ fi a 1 & o P g P X (0 fi & (0 fi P< g ω •rt fi to § •rl fi 1 Λ P fi P W fi 3 CM P bp §) Λ o P tp «fi bo to Φ a rrt fi I B •rt fi •rt •rt fi fi fi Ό .fi 0 Φ . .fi φ Φ P P O &3 q > s > V) ca 35 Ό. Φ to P 10 to fi Φ fi 3 tn P 3 o o fi fi Λ to o -± X Λ CM CM to 0! p •rt w Φ Ό fi 8 fi t fi O E-i 8 Φ o 0 •rt 0 € p •rt Pi V) fi 1 fi - to p 0 0 fi fi s «H o Φ 0« Ό o w H *c w φ o fi B •rt $ Φ p fi 3 H 5 P fi fi •rt ω ϋ to Φ c W a «Η •rt P Φ fi φ X? o fi Φ « & a G e 2 6 5 4 The stability of the emulsion, was such that it could be used for up to J hour at 20-22°C and it was possible to obtain fully satisfactory board even when the freshly sprayed chips were kept at 20-22°C for 1 hour before being compressed into board.

By the inclusion of a catalyst in the emulsion it is possible to accelerate the cure thus permitting either a shorter cycle at gO-95eC or operation at a lower temperature e.g. by including 1% dimethyl hexadecylamine on the weight of EMDIPP into the emulsion the stability was reduced so that it had to he sprayed within 2 minutes, and the sprayed chips had to be pressed within 5 minutes but tlie board was cured in 3 minutes at 95°θ or in 5 minutes at 70°C.

Improvement in the water· resistance may be expected by inclusion of supplementary water repellants on similar lines to the systems already used with the conventional urea-formaldehyde phenolformaldehyde bonded chipboard.

Example 2 Four emulsifiable MDI prepolymers (i) to (iv) made by mixing together MDI (100 parts), methoxy P.E.G. MW 650 (10 parts and the following polyols:(i) oxypropylated glycerol, OH value ICO (30 parts) (ii ) oxypropylated glycerol, OH value 540 (9 parts) (III) a polyester, OH value 540, derived from adipic acid diethylene glycol and glycerol (9 parts) (TV) castor oil, OH value 16O (30 parts) Each emulsifiable MDI prepolymer was emulsified with water in the weight ratio of 1:1.

The NCO content of each emulsion was determined after 2 hours at 22°C using the standard method of adding excess di-n-butylamine to a 4 2 a <> 4υ'ό aqueous emulsion followed by back titration wild hydrochloric acid. The loss ot aclivily of each emulsion was as followr.:emulsion derived I coni (i) - 55¾ ·' (ii) - 307. (iii) - 24·ύ ” ” (iv) - 17¾ These results show that the more hydrophobic is the polyol used in the preparation of the prepolymer, the greater is the working life of the emulsion.

Further, the loss of activity of emulsions derived from 7 parts of an emulsifiable prepolymer and 12 parts of water and the corresponding emulsions incorporating a chlorinated paraffin wax diluent, Cereclor S45 (Registered Trade Mark) was as follows :Castor oil prepolymer - 27.3¾ + 4 parts Cereclor S45 - 18.9¾ Prepolymer from hydrogenated castor oil -22.9¾ + 4 parts Cereclor S45 - 13.7¾ Prepolymer from oxypropylated glycerol (OH value 540) - 30.4Ϊ + 4 parts Cereclor S45 - 17.2S I» I» It tl It .J. y parts Cereclor Ξ45 - 13.5¾ These results show that by including a paraffin wax in an aqueous emulsion of a prepolymer the working life of the emulsion is extended. 2 6 5 4 Example 5 A prepolymer was prepared by mixing together 100 parte HDI parte Caetor oil (first pressing) OH 16O, and 10 parte Methoxy PEG MW 650, heating at 80°C overnight, and then cooling. -Two emulsions (a) and (b) were prepared by mixing together: (a) 4 parts of the above castor oil prepolymer and 10 parts of water; and (b) 6 parts of a mixture of the above castor oil prepolymer (4 parts) , and Cereclor S45 (2 parts), arid 10 parts of water.

. Two chipboard samples were then prepared by taking 102 parts of wood chips containing 2% moisture and spraying separately whilst tumbling with the above emulsions which were sufficiently fluid to give good atomisation. Each batch of treated chips was sprinkled into a frame laid on a still plate to form a cake which after removal of the frame was covered with an aluminium plate, both metal plates having, been treated with a wax based release agent. The cakes were compressed in a hydraulic press with platens at 1?5eC using a pressure of 135 Kg/cm . A distance plate was fitted to limit the compression to 19 mm and the amount of treated chips was chosen to give a final chipboard density of about 680 Kg/m^. The time of pressing was 4¾ minutes and when pressure was released the adhesions of the board using the Cereclor S45 in the binder was better than that of the blank (a), which showed some tendency for sticking especially in the case of the steel plate. - 19 4 2 5 5 4 Bie boards were allowed to cool and condition and wore subsequently tented. The results were as followed. a b •z Density Kg/nr 704 715 Water swell 2 hours % 23-0 18.0 24 hours % 26.0 21.6 German V20 test KN/m2 703 822 ·· V100 test KN/m2 157 190 Example 4 A batch of the same type wood chips with 25ί Moisture was sprayed with an emulsion prepared' from parts of a mixture of castor oil prepolymer used in Example 3 (4 par and CerecLor S45 (2 parts), and 6 parts of water and subsequently V parts of 205? slack wax emulsion were sprayed on and the treated 15 chips then sprinkled and processed as before. The cooled conditioned board was tested, the results being as follows: Density 690 Water swell 2 hrs /? 13-5 24 hrs % 22.0 20 V20 kN/ra2 790

Claims (22)

1. CLAIMS:1. Λ process for manufacturing sheets or· moulded bodies wiii eb comprises hoi, pressing oi' a mass oi' I.igno-celjul osie material mixed witii a binding agent comprising an aqueous 5 emulsion of an organic isocyanate containing a non-ionic surface active agent devoid of hydroxy, amino and carboxylic acid groups.

2. A process as claimed in claim 1 wherein the organic isocyanate is an aromatic diisocyanate or polyisocyanate of jo higher functionality.

3. A process as claimed in claim 1 wherein ohe organic isocyanate is a crude mixture of methylene bridged polyphenyl polyisocyanates containing diisocyanates, triisocyanates and higher functionality polyisocyanates. 15

4. A process as claimed in claim 1 wherein the organic isocyanate is an isocyanate-ended prepolymer made by reaction ol' an excess of a diisocyanate or higher functionality polyisocyanate with a hydroxyl-ended polyester or hydroxyl-ended polyetlier or with a monomeric polyol or mixture of monomeric 20 polyols.

5. A process as claimed in either of claims 1 or 4 wherein the organic isocyanate is an isocyanate-ended prepolymer derived from a crude mixture of methylene bridged polyphenyl polyisocyanates containing diisocyanates, triisocyanates and higher 25 functionality polyisocyanates.

6. A process as claimed in any one of Claims 1,4 or 5 wherein the organic isocyanate is an isocyanate-ended prepolymer prepared using ;t hydrophobic polyol .

7. A process as claimed in claim b wherein the hydrophobic ;0 polyol is castor oil. 4. 2 6 5 4

8. Λ process . as claimed in any one of the preceding claims wherein the surface active agent has the formula; RO(CH 2 CII 2 O) n CONHX in which R is an alkyl group of from 1 to 4- carbon atoms, n is an integer such that the compound contains an average of at least 5 oxyethylene groups and X is the residue of a di or polyisocyanate and contains at least one free isocyanate group.

9. A process as claimed in claim 8 wherein R is methyl.

10. A process as claimed in either one of claims 8 or 9 wherein n represents an average of from 5 to 120.

11. A process as claimed in either one of claims 8 or 9 wherein n represents an average of from 10 to 25.

12. A process as claimed in any one of the preceding claims wherein the emulsion is that in which from 99 to 25 parts by weight of water are associated with from 1 to 75 parts by weight of organic isocyanate per 100 parts by weight of water and organic isocyanate.

13· A process as claimed in any one of the preceding claims wherein tho emulsion is that in which from 75 to 50 parts by weight of water are associated with from 25 to 5θ parts by weight of organic isocyanate per 100 parts by weight of water and organic isocyanate.

14. A process as claimed in any one of the preceding claims wherein the amount of surface active agent used is from 5 parts to 15 parts by weight based on 100 parts by weight of the organic isocyanate.

15. A process for manufacturing sheets or moulded bodies which comprises spraying lignocellulosic material with an aqueous - 22 :854 emulsion ol' an organic polyi.socyaual e, said aqueous emulsion containing a stabilising proportion of a non-ionic surface active agent devoid of liydroxy, amino and carboxylic acid groups and having 75 to 50 parts by weight of water associated

5. With 25 to 50 parts by weight of the organic polyisocyanate per 100 parts by weight of water and organic polyisocyanates optionally drying at 20 to 40°C to remove a portion of the water and hot pressing the sprayed lignified raw material at a temperature below 200°C. 20 16. Λ process as claimed in claim 15 wherein the organic polyisocyanate is an isocyanate-ended prepolymer of a crude mixture of methylene bridged polyphenyl polyisocyanates .

17. A process as claimed in either one of claims 15 or 15 16 wherein the sprayed lignified raw material is hot pressed at a temperature below 100°C.

18. A process as claimed in either one of claims 15 or 16 wherein the sprayed lignified raw material is hot pressed at a temperature of from 90 to 95°C. 20

19. A process for manufacturing moulded wood chip boards as herein described with reference to Example 1.

20. A process as claimed in any one of claims 1 to lE wherein there is included in tho emulsion an Inert hydrophobic diluent. 25

21. A process as claimed in claim 20 wherein the hydrophobic diluent is a chlorinated paraffin wax.

22. A process for manufacturing moulded wood chip boards as herein described with reference to either one of Examples 3 or 423 4 2 8 5 4 Dated this the 12th day of March, 1976.