FI64621C - PROCEDURE FOR THE FRAMSTATION OF A CLEANER WITH A CROSS PARAGRAPH OF ANALYZING THE ENVIRONMENT OF AN ORGANIC P OLISOCYANAT - Google Patents

Description

ΓΓ3ΚΓΓ1 γβι advertisement publication [B] <11) UTLÄGGN I NGSSKRIFT 64621 C (4S) Paten Iti cyl ;; :: '·' .ty 12 12 1923 j & jrjpJ Patent ceddalat V »(51) Kv.! K. ^ Int.ci. 3 C 08 L 97/02, B 29 J 5/00 FINLAND — FINLAND CM) Patent application - Patentansöknlnj 760651 (22) Hakamlaplhri — Ans & knlnftda | 12.03. 76 (Fl) (23) Alkupllvi — Giftlghetsdag 12.03.76 (41) Become Public - Bllvlt offentllf 13.09-76

Patent, and the National Board of Registration NihtMk.1, »™„

The Patent and Registration Office 's application was published in the Official Journal on 31.00. oi (32) (33) (31) Privilege claimed — Baglrd prlorltet 12.03.75 United Kingdom-Storbritannien (GB) 1026U / 75 (71) Imperial Chemical Industries Limited, Imperial Chemical House, Millbank,

London SW1, UK-UK (GB) (72) Alan Metcalf Wooler, Blackley, Manchester, UK-UK (GB) (7 * 0 Oy Kolster Ab (5U) Method for making sheets or castings using organic polyol cyanate in water emulsion - For the production of water or water emulsion under an organic water emulsion

The invention relates to a method for producing plates or cast parts.

Integral sheets and flat sheets or castings and the like are generally made by hot pressing a pulp of wood chips, wood fibers or other lignocellulosic materials mixed with binders, especially solutions of urea formaldehyde or phenol formaldehyde resins. The compression temperatures are usually about 150 to 220 ° C, because otherwise there will not be sufficient adhesion within an acceptable time, even if conventional high pressures (20 to 100 kp / cm) are used.

It is known to use isocyanate solutions as binders instead of urea formaldehyde or phenol formaldehyde resins as binders in particle boards.

U.S. Patent Nos. 2,968,575 and 3,711,238 describe a process in which an aqueous emulsion of an isocyanate-containing polyurethane prepolymer for gluing wood is 2,64621. They do not deal with the impregnation of the lignocellulosic material with an isocyanate emulsion and the pressing of the material into sheets.

The invention relates to a process for the production of sheets or castings by hot pressing a mass of lignocellulosic material mixed with an organic polyisocyanate as a binder, which process is characterized in that the organic polyisocyanate is added to the lignocellulosic material as an aqueous emulsion containing a surfactant.

R0 (CH2CH2O) n CONHX

wherein R is an alkyl group having 1 to U carbon atoms, n is an integer such that the compound contains an average of at least 5 oxyethylene groups, and X is a di- or polyisocyanate residue containing at least one free isocyanate group.

In the process according to the invention, wood chips, wood fibers, chips, chip wool, cork and bark, sawdust and other similar waste products from the wood processing industry and / or other natural lignocellulosic products, e.g. fibers obtained from flowers and grasses. In addition, an inorganic flaky or fibrous material, e.g. glass fibers, mica or asbestos, can be mixed with the lignocellulosic material.

Among the organic isocyanates, mention may be made of diisocyanates, in particular aromatic diisocyanates, and isocyanates with higher functionality.

Examples of polyisocyanates to be used in the process according to the invention are aliphatic isocyanates, such as hexamethylene diisocyanate, aromatic isocyanates, such as m- and p-phenylene diisocyanate, toluene-2, U- and 2,6-diisocyanates, -phenylmethane-1 ', U'-diisocyanate, chlorophenylene-2-diisocyanate, naphthylene-1,5-diisocyanate, diphenylene-N, U'-diisocyanate, * +, 1 *' isocyanate-3,3'-dimethyldiphenyl, 3-methyldiphenylmethane-U, 1 + '-diisocyanate and diphenyl ether diisocyanate, cycloaliphatic diisocyanates such as cyclohexane-2, U- and 2 , 3-diisocyanates, 3-methylcyclohexyl-2, h- and 2,6-diisocyanates and mixtures thereof, and bis- (isocyanate-cyclohexyl) -methane> and triisocyanates, such as 2, k, 6-tri-i cyanate toluene and 2, U, 1+'-tri-i cyanate diphenyl ether.

Mixtures of isocyanates can also be used, e.g. mixtures of tolylene diisocyanate isomers such as the commercially available 2, U and 2,6 isomers and also mixtures of di- and higher polyisocyanates prepared by phosgenation of aniline-formaldehyde condensates. Such mixtures are known in the art and also include crude phosgenation products containing methylene-crosslinked polyphenyl polyisocyanates, including diisocyanate, triisocyanate and higher polyisocyanates, and any accompanying phosgenating agents. mixtures of by-products.

Preferred polyisocyanates for use in the process of the invention are those in which the isocyanate is an aromatic diisocyanate or a higher functional polyisocyanate, especially crude mixtures of methylene-crosslinked polyphenyl polyisocyanates polyisocyanates and triisocyanates containing triisocyanates. Methylene-crosslinked polyphenyl polyisocyanates of the general formula -O-o are already known in the art.

NCO NCO, NCO

* - - n-1 where n is one or more and, in the case of crude mixtures, represents an average of more than 1. These polyisocyanates are prepared by phosgenating corresponding mixtures of polyamines prepared by condensing aniline and formaldehyde. For convenience, the abbreviation MDI is used below for crude mixtures of methylene-crosslinked polyphenyl polyisocyanates containing diisocyanate, triisocyanate and higher functional polyisocyanates.

11 64621

Particularly preferred organic isocyanates for use in the present invention include isocyanate-terminated osipolymerates prepared by reacting an alioiso cyanate or a higher functionality polyisocyanate with an excess of a functionalization of a polyacidate with a hydroxyl-terminated polyester or hydroxyl-terminated polyether or hydroxyl-terminated polyether. cyanate in excess when used to react with a monomeric polyol or a mixture of monomeric polyols such as ethylene glycol, trimethylolpropane or butanediol. However, isocyanate-terminated prepolymers prepared using water-repellent polyols, such as castor oil, are particularly valuable because they react more slowly with water. This point is explained in more detail below.

One useful class of isocyanate-terminated prepolymers is isocyanate-terminated prepolymers of MDI.

The aqueous emulsion of the organic polyisocyanate used in the process of the invention may suitably contain a nonionic surfactant free of hydroxy, amino and carboxylic acid groups, in particular condensates of ethylene oxide molecules which do not have chain-terminated hydroxy, amino or carboxylic acid group.

These particular surfactants, i.e. emulsifiers, have the formula RO (CH_CHoO) CONHX ddn wherein R represents an alkyl group having 1 to U carbon atoms, n is an integer such that the compound contains on average at least 5 oxyethylene groups, and X is di- or a polyisocyanate residue having at least one free isocyanate group. Examples of R are ethyl, propyl and butyl, and methyl is particularly suitable. The pin-active urethane must have a sufficient number of oxyethylene groups (CH2CH2O) so that there are on average at least 5 such groups per molecule. Suitably n represents an average of 5 ~ 120, especially 10-25.

5,64621

Group X is a residue remaining after one isocyanate group is removed. The group X may be a residue of a diisocyanate or a higher polyisocyanate. If, for example, toluene diisocyanate is the diisocyanate, the residue X will be

NOO

Residue X suitably contains an isocyanate group.

Isocyanates from which residue X can be derived include the di- and polyisocyanates listed above.

Such urethane surfactants can be prepared by reacting an alcohol of formula R0 (CH2 CH2O) H2 with an isocyanate containing at least two isocyanate groups, using at least one mole of isocyanate per mole of alcohol. However, the isocyanate is suitably used in excess.

The reaction can be carried out by adding alcohol to the isocyanate and stirring until the mixture clarifies, and allowing the reaction to proceed at room temperature. The reaction can be accelerated by heating up to 100 ° C.

To obtain emulsions for use according to the invention, a surfactant of the above-mentioned type can be prepared in isocyanate "in situ". If it is desired to prepare an isocyanate emulsion of the formula X (NC0) 2, a small amount of polyethyleneoxy alcohol R0 (CH0CHO0) H can be added to a large excess of isocyanate X (NC0) O and form an emulsifier in the isocyanate "in situ".

In cases where the polyisocyanate is a prepolymer, the prepolymer and surfactant can be formed "in situ" simultaneously or in two different steps, and the prepolymer / surfactant can then be mixed with water to form an emulsified prepolymer. Emulsification can be facilitated by first mixing the prepolymer / surfactant with water used at 25% by weight of this mixture, followed by further dilution with water if necessary.

6,64621

In case it is desired that the polyisocyanate in the emulsion belongs to the class of the above-mentioned preferred prepolymers, namely the MDI prepolymer, the prepolymer emulsion can be prepared by applying one of the following methods: 1. MDI is reacted with the required amount of polyol to prepare the prepolymer CH 3 O (CH 2 CH 2 O) nH with a small amount and then emulsified by mixing with water.

2. The MDI is reacted with polyethyleneoxy alcohol (CH 2 Cl 2 CH 2 O 2), followed by reaction with the amount of polyol required to form the prepolymer, and then emulsification is performed.

3. The MDI is reacted simultaneously with the required amounts of polyol and polyethyleneoxy alcohol, followed by emulsification in water.

In the above methods, the surfactant is prepared in polyisocyanate "in situ". The general formula of the surfactant is R0 (CH_CH_O) X in which X represents isocyanate residues and R is an alkyl group having 1 to U carbon atoms.

Preferred surfactants are those derived from a polyethyleneoxy compound of the formula RO (CH 2 Cl 2) n H, wherein R is methyl and n is on average 10-25 · Typical examples of polyethyleneoxy compounds are methoxy polyethylene glycols having a molecular weight of 300-1000.

The surfactant can, of course, be prepared separately and dissolved to a small extent in the prepolymer preparation mixture or in the preformed prepolymer.

The prepolymers can be prepared by any of the methods known in the art, e.g. by heating the components together or reacting them at room temperature, optionally in the presence of catalysts.

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

Emulsions suitably used according to the invention are those in which 99 to 25 parts by weight of water are incorporated in 1 to 25 parts by weight of polyisocyanate (in particular those in which T5 ~ 50 parts by weight of water are added to 7 to 64 parts by weight of polyisocyanate). part of an isocyanate, and which also contain a stabilizing amount of a nonionic surfactant) having no hydroxy, amino and carboxylic acid groups. A suitable amount of surfactant is 5 to 15 parts by weight per 100 parts by weight of isocyanate.

Emulsions can be prepared by applying methods known in the art, suitably mixing the emulsifier with an organic polyisocyanate and mixing this mixture with water. Alternatively, in some cases, the nonionic surfactant may be prepared in polyisocyanate "in situ" and, if desired, this product further diluted with polyisocyanate may be mixed with water and the entire mixture mixed to obtain the desired emulsion.

To apply the method of the invention, the binder is mixed with the lignocellulosic material, suitably by spraying a finely divided aqueous emulsion into the material to provide good coverage. Aqueous viscosities of organic polyisocyanates have been found to have such a low viscosity that they can be sprayed at a concentration of up to 65%, whereas solutions of urea formaldehyde and phenol formaldehyde resins commonly used in the manufacture of particle board and similar materials are generally not sprayable if Ho%. The invention thus provides a production method which uses less water than has hitherto been possible, so that less water must be removed during the hot-pressing step or the subsequent compaction. Alternatively, the lignocellulosic material does not need to be dried as thoroughly as hitherto before it is mixed with the binder. The use of warm water and / or organic polyisocyanate can facilitate emulsification and spraying.

It has further been found that the hot-pressing step of the process of the invention can be efficiently carried out at temperatures below 100 ° C, e.g. 90-95 ° C instead of the 150-220 ° C normally used for urea formaldehyde and phenol formaldehyde resins. The use of such lower temperatures saves power, reduces environmental impact and prevents the formation of vapors. The use of such lower temperatures is also advantageous in that it avoids the generation of steam inside the sheets or molded articles made at higher temperatures. 8 64621, which is particularly important in the manufacture of laminates with impermeable surface layers. In the compression step, better compression can thus be achieved, since it is no longer necessary to leave the product with sufficient permeability to allow the steam to escape.

Of course, it is also possible to continue to use higher temperatures than usual, which in some circumstances may in fact be advantageous, since thus shorter curing times are achieved and the detachment of the chipboard from the press plates is improved. This latter fact may be relevant in the case of the production of uncoated sheets.

According to a preferred embodiment of the invention, a process for the production of sheets or castings is thus obtained, which is characterized by injecting into a lignocellulosic material an organic polyisocyanate a surface wetting agent having no hydroxy, amino and carboxylic acid groups and in which 75 to 50 parts by weight of water are added to 25 to 50 parts by weight of organic polyisocyanate, optionally drying at 20 to 10 ° C in a portion of water to remove the part, and to achieve cohesiveness, the lignified raw material sprayed with the binder is hot-pressed at a temperature of less than 200 ° C, and in particular of less than 100 ° C, and in particular of 90-95 ° C.

In this way, firmly bonded sheets or castings can be economically produced.

In practice, delays will inevitably occur between the emulsion preparation steps, the injection of the lignocellulosic material and the hot pressing of this material, and delays will also occur due to the detection of processing errors and the performance of operating adjustments. The reaction between the isocyanate and the water in the emulsion must suitably be sufficiently slow to allow a rod of e.g. two hours between the preparation of the emulsion and hot pressing. The reaction rate can be slowed to obtain an emulsion with an acceptable shelf life by using less surfactant or by using less effective agent, but both of these measures adversely affect the stability of the binder and the distribution of isocyanate in the lignocellulosic material, in addition to spraying difficulties. Therefore, the reaction rate is suitably slowed down by using an isocyanate-terminated prepolymer derived from a water-repellent polyol, as already mentioned above, and / or by incorporating an inert water-repellent diluent into the emulsion, which may also be advantageous in improving the water-repellent nature of the chipboard. the press plates. Suitable diluents include aromatic and aliphatic hydrocarbons as well as esters optionally containing a halogen substituent. Examples are mineral oil and compressed paraffin (crude paraffin wax), didodesyl phthalate, tris-β-chloropropyl phosphate, and especially chlorinated paraffin waxes. These diluents, which are not reactive with the isocyanate groups, can be added during the preparation of the prepolymer or just before emulsification.

Example 1 320 g of wood chips were dried to a moisture content of 6%. The chips were placed in an open mixing bowl, and as they were mixed, the binder fluid was sprayed using a simple hand-held sprayer, the amount applied being measured on the basis of weight loss. The chips were mixed for one minute after spraying, after which they were evenly spread over an area of 18 cm x 18 cm in the casting box. Thereafter, the mass was compressed as much as possible by hand after a cover plate of the same size was fitted to the box, forming a loosely sized chip mat about U, 5 ~ 5 cm thick. This mat was transferred between metal plates treated to facilitate detachment, and the combination was placed in a hydraulic press where the mat was pressed at a pressure of 50 kp / cm for 5 minutes between the plates at 90-95 ° C. A spacer about 1. U cm thick was used to limit the density to about 0.7 · The plates were removed from the mold and then allowed to equilibrate to a water content of about 10%. Physical experiments were performed in a central area of 15 cm x 15 cm of the obtained plate pieces.

A comparison was made between the emulsifiable product MDI and the emulsifiable MDI prepolymer having a composition of 10,64621 MDI 100

Oxypropylated glycerol MW 1000

Methoxy polyethylene glycol (methoxy PEG) MW 650

Each product was emulsified by mixing water with half of its weight and then with an amount of water equal to its weight to obtain emulsions with a solids content of 1 + 0%.

1 + 0 g of these emulsions were sprayed into 320 g batches of wood chips as described above.

Both plates were well cured when removed from the press, and no visible water vapor or other vapors were generated at this temperature, and no swelling was observed after the plates were removed from the press.

A similar series of experiments was performed using only half the amounts of emulsion to give only 2.5% solids, based on the weight of the chips.

The physical properties were tested by performing the experiments described in BS 1811, Part 2. The results are shown in the following table, which uses the following abbreviations:

EMDI = emulsifiable MDI

EMDIPP = "" MDI prepolymer.

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The stability of the emulsion was such that the emulsion could be used for up to 1/2 hour at 20-22 ° C, and a completely satisfactory sheet was obtained even if freshly injected chips were kept for one hour at 20-22 ° C before being compressed into sheets.

By including a catalyst in the emulsion, curing can be accelerated and thus either a shorter preparation period at 90-95 ° C or the possibility of operating at a lower temperature can be achieved. For example, the addition of $ 1 dimethylhexadecylamine to the emulsion, based on the weight of the EMDIPP, reduced the stability so much that the emulsion had to be sprayed within 2 minutes and the sprayed slabs had to be compressed within 5 minutes, At C within a minute.

An improvement in water resistance is expected in the case of the addition of additional water repellents in a manner similar to that described above to existing systems for producing conventional urea formaldehyde / phenol formaldehyde bonded particle board.

Example 2

Four emulsifiable MDI prepolymers (1) to (4) were prepared by mixing together 100 parts MDI, 10 parts methoxy-PEG MW 650 and the following polyols and 30 parts oxypropylated glycerol, OH number 160 (1) 9 parts oxypropylated glycerol, OH Chapter 540 (2) 9 parts polyester, OH number 540, derived from adipic- (3) nitric acid diethylene glycol and glycerol 30 parts castor oil, OH number 168 (4) These polyols were emulsified in water in a weight ratio of 1: 1.

o

The NCO content of each emulsion was determined after 2 hours at 22 ° C using a standard method of adding excess di-n-butylamine to a 40% aqueous emulsion, followed by back-titration with hydrochloric acid. The loss of activity for each emulsion was as follows: Emulsion derived from product (l) $ 55 "(2)" "30 #" (5) "" 24 1 ° "(4)" "17 i> These results show that the more water repellent the polyol used in the preparation of the prepolymer is, the longer the useful life of the emulsion.

The loss of activity of emulsions derived from 7 parts of emulsifiable prepolymer and 12 parts of water and the loss of activity of the corresponding emulsions containing 13,64621 chlorinated wax "Cereclor S45" (registered trademark) as diluent were as follows:

Non-polymer with castor oil -27 $> "" "+ 4 parts" Cereclor S45 "-18.9 #

Polymer with hydrogenated castor oil -22.9 ° "" "" + 4 parts "Cereclor S45" -13.7

Polymer with ocular propylated glycerol (OH number 940) -30.4 i »f» ΤΪ ft ft tl + 4 parts "Cereclor S45" -17.2 # «" "" (OH number 540) + 7 parts " Cereclor S45 "-13.5 # These results show that the incorporation of paraffin wax into the aqueous emulsion of the prepolymer results in an increase in the useful life of the emulsion. Example 3

A prepolymer was prepared by mixing together 100 parts of MDI

30 "castor oil (first compression), OH number 160, and 10" motoxy-PEG MW 650, followed by heating at 60 ° 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, (b) 6 parts of a mixture of 4 parts of the above castor oil prepolymer and 2 parts of "Cereclor S45 "10 parts water.

Two chipboard samples were then prepared using 102 parts of wood chips with a moisture content of 2 and by separately injecting into each sample the above-mentioned emulsions which were sufficiently liquid to achieve good fogging. During spraying, the chip charges were mixed. Each batch of treated chips was sprinkled on a frame lowered onto a washer to form a cake, which was covered with an aluminum plate after the frame was removed. Both metal plates had been treated with a wax-based release agent.

The cakes were compressed in a hydraulic press at a pressure of 135 kp / cm at 175 ° C. The spacer was placed in place to limit compression to a thickness of 19 mm, and the amount of treated chips was selected such that the final density of the chipboard was about 680 kg / m · *. The bite time of 64621 was U 3M minutes. After the compression force had ceased, the sheet in which the product "Cereclor SU5" was used in the binder was better cohesive than the sheet in which emulsion (a) was used, and which showed a tendency to stick, especially when using a steel sheet.

; The plates were allowed to cool and equilibrate, after which they were tested, f The results were as follows: l a b t Density, kg / m ^ 70U 713

Swelling in water 2 hours,% 23.0 18.0 \ "" 2h hours,% 26.0 21.6

German V20 test, kN / m2 703 822 t "V100 test, kN / m2 157 190 * I Example 1 I A batch of wood chips of the same type with a chip moisture content of 2% was injected with an emulsion prepared using I 6 part of a mixture of 1+ parts of the castor oil used in Example 3

The prepolymer, 2 parts of "Cereclor SU5" and 6 parts of water, and then 5 parts of a 20% emulsion of compressed paraffin were sprayed onto the treated chips, which were then sprinkled on frames and subjected to the same treatment as above.

ί When the cooled equilibrated plate was tested, the following results were obtained: density 690 i swelling in water for 2 hours,% 13.5 l "2h hours,% 22.0 iV20, kN / m2 790 i f

Claims (3)

15. . 64621 A process for preparing sheets or castings by hot-pressing a mass of lignocellulosic material mixed with an organic polyisocyanate as a binder, characterized in that the organic polyisocyanate is added to the lignocellulosic material as an aqueous emulsion containing a surfactant of the formula R0 (CH_CH2 n wherein R is an alkyl group having 1 to ¾ carbon atoms, n is an integer such that the compound contains an average of at least 5 oxyethylene groups, and X is a di- or polyisocyanate residue containing at least one free isocyanate group. Process according to Claim 1, characterized in that the aqueous emulsion is added to the lignocellulosic material by spraying, the sprayed material being optionally dried at 20 ° C to partially remove water and hot-pressing at a temperature below 200 ° C. Process according to Claim 1 or 2, characterized in that the hot pressing is carried out at a temperature of less than 100 ° C. U. Process according to one of the preceding claims, characterized in that the hot pressing is carried out at 90-95 ° C.