DK152565B

DK152565B - Pressed sheet containing lignocellulose

Info

Publication number: DK152565B
Application number: DK206685A
Authority: DK
Inventors: James Michael Gaul; Tinh Nguyen
Original assignee: Atlantic Richfield Co
Priority date: 1981-08-17
Filing date: 1985-05-09
Publication date: 1988-03-21
Also published as: DK152565C; DK206685A; DK206685D0

Description

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Den foreliggende opfindelse angår en presset plade, som består af lignocelluloseholdige partikler og et polyisocyanatklæbemiddel samt eventuelt lignin.The present invention relates to a pressed plate consisting of lignocellulosic particles and a polyisocyanate adhesive as well as optionally lignin.

Formningen af lignocellulosefibre, -partikler el-5 ler -lag og lignocelluloseholdige fibre, partikler eller lag til dannelse af pressede plader er kendt. De bindemidler, der sædvanligvis benyttes, er kunstharpiks-lim såsom en opløsning af urinstofformaldehyd- eller phenolformaldehydharpiks i vand. Pressede plader, in-10 deholdende lignocellulose fremstillet på denne måde, er ikke tilstrækkeligt holdbare, og de er følsomme overfor fugtbetingelser og udsat for ødelæggelse ved visse bygningsformål, hvortil de måtte blive anvendt.The formation of lignocellulosic fibers, particles or layers and lignocellulosic fibers, particles or layers to form pressed sheets are known. The binders commonly used are synthetic resin adhesives such as a solution of urea formaldehyde or phenol formaldehyde resin in water. Pressed sheets, including lignocellulose in this way, are not sufficiently durable and are sensitive to moisture conditions and subject to destruction for certain building purposes for which they may be used.

Di- og polyisocyanater som klæbemidler for ligno-15 celluloseholdige materialer er tidligere blevet foreslået, og det er kendt, at de giver produkter af forøget stabilitet og mekanisk styrke. Procestekniske fordele ved polyisocyanater er blevet beskrevet i tysk offentliggørelsesskrift nr. 2.109.686. To problemer, der er 20 forbundet med benyttelsen af polyisocyanatklæbemidler, er 1) selv ved anvendelse af et formindsket indhold af klæbemiddel er prisen på polyisocyanaterne, sammenlignet med urinstofformaldehyd- eller phenolformaldehydharpiks-klæbemidlerne, ugunstig, og 2) viskositeten af de sæd-25 vanligvis anvendte polyisocyanatklæbemidler er langt højere end viskositeten af kunstharpikslimen, og de er derfor vanskelige at påføre lignocellulosen med det sædvanlige påføringsudstyr eller de sædvanlige påføringsmetoder. Fremkomsten af teknologi til emulgering af poly-30 isocyanaterne i vand førte til et klæbemiddel med formindsket viskositet, men med en standtid på kun 2 til 4 timer.Di- and polyisocyanates as adhesives for lignocellulosic materials have been previously proposed and are known to provide products of increased stability and mechanical strength. Process-technical advantages of polyisocyanates have been described in German Publication No. 2,109,686. Two problems associated with the use of polyisocyanate adhesives are 1) even using a diminished adhesive content, the price of the polyisocyanates compared to the urea formaldehyde or phenolic formaldehyde resin adhesives is unfavorable, and 2) the viscosity of the semen 25 The polyisocyanate adhesives used are much higher than the viscosity of the resin adhesive and are therefore difficult to apply to the lignocellulose with the usual application equipment or methods of application. The advent of technology for emulsifying the polyisocyanates in water led to a reduced viscosity adhesive, but with a standing time of only 2 to 4 hours.

Gennem den foreliggende opfindelse, der omfatter en presset plade med et overfor den kendte teknik for-35 bedret polyisocyanatbaseret klæbemiddel, der er blevet fortyndet ved tilsætning af flydende cykliske alkylen-carbonater (cykliske alkylenestere af kulsyre) og eventuelt lignin, undgås de ovennævnte ulemper.The present invention, which comprises a pressed plate having an improved prior art polyisocyanate based adhesive which has been diluted by the addition of liquid cyclic alkylene carbonates (cyclic alkylene esters of carbonic acid) and optionally lignin, avoids the foregoing disadvantages.

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Hovedformålet med opfindelsen er at tilvejebringe en presset plade med samme egenskaber eller bedre egenskaber end hos tidligere kendte pressede plader af den omhandlede art men med dramatisk reduceret indhold af 5 di- eller polyisocyanat (i almindelighed betegnet poly-isocyanater) og følgelig tilsvarende reducerede omkostninger.The main object of the invention is to provide a pressed plate having the same properties or better properties than with previously known pressed plates of the present invention but with dramatically reduced content of 5 di- or polyisocyanate (generally referred to as polyisocyanates) and consequently correspondingly reduced costs.

Den pressede plade ifølge opfindelsen er ejendommelig ved, at klæbemidlet forefindes i en mængde på fra 10 1,5 til 12, fortrinsvis fra 2,5 til 6,5 vægt%, baseret på ovntørrede partikler, og at det består at 20 til 95, fortrinsvis 50 til 75, vægt% af et organisk di- eller polyisocyanat og 80 til 5, fortrinsvis 50 til 25, vægt% af et flydende alkylencarbonat.The pressed sheet according to the invention is characterized in that the adhesive is present in an amount of from 10 1.5 to 12, preferably from 2.5 to 6.5% by weight, based on oven dried particles, and that it consists of 20 to 95, preferably 50 to 75, weight percent of an organic di or polyisocyanate and 80 to 5, preferably 50 to 25, weight percent of a liquid alkylene carbonate.

15 Fordelene ved foreliggende opfindelse er, at de indhold af di- eller polyisocyanatet, der er nødvendige ved fremstilling af en hærdet presset lignocellulosehol-dig plade, kan reduceres væsentligt, medens den pressede plades fysiske egenskaber forbliver de samme eller bli-20 ver bedre. Ved anvendelse af kombinationen di- eller polyisocyanat - cyklisk alkylencarbonat med eller uden anvendelse af lignin som fortyndingsmiddel - bliver klæ-bemiddelharpiksøkonomien uændret eller bedre end økonomien i forbindelse med kunstharpikslim. Den omhandlede 25 pressede plade har bedre fysiske egenskaber end egenskaberne hos produkter fremstillet med urinstofformaldehyd eller phenolformaldehydklæbemiddelsystemerne. Tilsætningen af de flydende cykliske alkylencarbonater til di- eller polyisocyanaterne formindsker den totale 30 viskositet af klæbemidlet væsentligt samtidig med, at den medfører en mærkbar forøgelse af standtiden på op til 30 dage. Klæbemidlet har viskositeter, der svarer til eller er lavere end viskositeten af formaldehydtypeharpiks systemerne i vand, hvilket gør det muligt at 35 påføre det på de lignocelluloseholdige spåner, partikler osv., under anvendelse af gængs påføringsteknologi. Som en yderligere fordel kan nævnes, at klæbemiddelsysternetThe advantages of the present invention are that the content of the di- or polyisocyanate required in the manufacture of a cured pressed lignocellulosic plate can be substantially reduced, while the physical properties of the pressed plate remain the same or become better. By using the combination di- or polyisocyanate - cyclic alkylene carbonate with or without using lignin as a diluent - the adhesive resin economy remains unchanged or better than the economics of synthetic resin adhesives. The disclosed pressed plate has better physical properties than the properties of products made with urea formaldehyde or phenol formaldehyde adhesive systems. The addition of the liquid cyclic alkylene carbonates to the di- or polyisocyanates significantly reduces the total viscosity of the adhesive while at the same time providing a noticeable increase in stand-up time of up to 30 days. The adhesive has viscosities equal to or lower than the viscosity of the formaldehyde type resin systems in water, which allows it to be applied to the lignocellulosic chips, particles, etc., using conventional application technology. As a further advantage, it can be mentioned that the adhesive system

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3 kan anvendes i forbindelse med faste eller halvfaste di- eller polyisocyanater med høj molekylvægt, der som sådanne ville have egenskaber, der ville udelukke deres anvendelse som klæbemidler for lignocelluloseholdige 5 produkter ved hjælp af gængs påføringsteknik.3 may be used in conjunction with solid or semi-solid high molecular weight di or polyisocyanates which as such would have properties which would preclude their use as adhesives for lignocellulose containing products by conventional application technique.

Der kan benyttes forskellige hensigtsmæssige udførelsesformer for den pressede plade ifølge opfindelsen som angivet i krav 2-4.Various convenient embodiments of the pressed sheet according to the invention can be used as set forth in claims 2-4.

De organiske polyisocyanater er i al alminde-10 lighed anvendelige som klæbemidler. Organiske polyisocyanater, der kan benyttes, inkluderer alifatiske, ali-cykliske og aromatiske polyisocyanater, der er karakteristiske ved at indeholde to eller flere isocyanatgrup-per. Sådanne polyisocyanater indbefatter diisocyanater-15 ne og isocyanaterne med flere funktionelle grupper, især de aromatiske polyisocyanater. Der kan benyttes blandinger af polyisocyanater, f.eks. de rå blandinger af di- og højere funktionelle polyisocyanater fremstillet ved phosgenering af anilin-formaldehydkondensater, eller 20 som de fremstilles ved den termiske dekomposition af de tilsvarende carbamater opløst i et egnet opløsningsmiddel som beskrevet i US-patentskrifterne nr. 3.962.302 og 3.919.279, begge kendt som råt MDI eller PMDI. Det organiske polyisocyanat kan være isocyanat-afsluttede pre-25 polymere fremstillet ved under kendte standardbetingelser at omsætte et overskud af et polyisocyanat med en polyol, der på polyisocyanat-polyolbasis kan andrage fra ca. 20:1 til 2:1, og omfattende f.eks. polyethylengly-col, polypropylenglycol, diethylenglycol-monobutylether, 30 ethylenglycolmonoethylether, triethylenglycol osv., samt glycoler eller polyglycoler, der er partielt esterifi-ceret med carboxylsyrer, derunder polyesterpolyoler og polyetherpolyoler. De organiske polyisocyanater eller isocyanat-afsluttede pre-polymere kan også benyttes i 35 form af en vandig emulsion ved at blande sådanne materialer med vand i nærværelse af et emulgeringsmiddel.The organic polyisocyanates are generally useful as adhesives. Organic polyisocyanates which may be used include aliphatic, alicyclic and aromatic polyisocyanates, which are characterized by containing two or more isocyanate groups. Such polyisocyanates include the diisocyanates and the isocyanates having several functional groups, especially the aromatic polyisocyanates. Mixtures of polyisocyanates, e.g. the crude mixtures of di- and higher-functional polyisocyanates prepared by phosgenation of aniline-formaldehyde condensates, or as prepared by the thermal decomposition of the corresponding carbamates dissolved in a suitable solvent as described in U.S. Patent Nos. 3,962,302 and 3,919. 279, both known as raw MDI or PMDI. The organic polyisocyanate may be isocyanate-terminated pre-polymers prepared by reacting, under known standard conditions, an excess of a polyisocyanate with a polyol which, on a polyisocyanate-polyol basis, may range from approx. 20: 1 to 2: 1, and comprising e.g. polyethylene glycol, polypropylene glycol, diethylene glycol monobutyl ether, ethylene glycol monoethyl ether, triethylene glycol, etc., as well as glycols or polyglycols partially esterified with carboxylic acids including polyester polyols and polyether polyols. The organic polyisocyanates or isocyanate-terminated pre-polymers may also be used in the form of an aqueous emulsion by mixing such materials with water in the presence of an emulsifier.

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Isocyanaterne kan også indeholde urenheder eller additiver såsom carbodiimider, isocyanuratgrupper, urinstof, hydrolyserbare chlorider og biureter samt visse slipmidler. Eksempler på sådanne di- eller polyisocyanater, 5 der kan anvendes, er toluen-2,4- og 2,6-diisocyanater eller blandinger deraf, diphenylmethan-4,41-diisocyanat (et fast stof) og diphenylmethan-2,41-diisocyanat (et fast stof) eller blandinger deraf, dvs. blandinger, der indeholder ca. 10 vægtdele eller mere 2,4'-, der er fly-10 dende ved stuetemperatur, polymethylenpolyphenylisocya-nater, naphthalen-1,5-diisocyanat, 3,3'-dimethyldiphe- nylmethan-4,4'-diisocyanat, triphenylmethantriisocyanat, hexamethylendiisocyanat, 3,3'-ditolylen-4,41diisocyanat, butylen-l,4-diisocyanat, octylen-l,8-diisocyanat, 4-15 chlor-1,3-phenylendiisocyanat, 1,4-, 1,3- og 1,2-cyclo- hexylendiisocyanater og i almindelighed de polyisocyana-ter, der er beskrevet i US-patentskrift nr. 3.577.358.The isocyanates may also contain impurities or additives such as carbodiimides, isocyanurate groups, urea, hydrolysable chlorides and biurets as well as certain release agents. Examples of such di- or polyisocyanates which may be used are toluene-2,4- and 2,6-diisocyanates or mixtures thereof, diphenylmethane-4,41-diisocyanate (a solid) and diphenylmethane-2,41-diisocyanate (a solid) or mixtures thereof, i. mixtures containing approx. 10 parts by weight or more 2,4'-liquid at room temperature, polymethylene polyphenyl isocyanates, naphthalene-1,5-diisocyanate, 3,3'-dimethyldiphenylmethane-4,4'-diisocyanate, triphenylmethane triisocyanate, hexamethylene diisocyanate , 3,3'-ditolylene-4,41 diisocyanate, butylene-1,4-diisocyanate, octylene-1,8-diisocyanate, 4-15 chloro-1,3-phenylene diisocyanate, 1,4-, 1,3- and 1 , 2-cyclohexylene diisocyanates and generally the polyisocyanates disclosed in U.S. Patent No. 3,577,358.

De foretrukne polyisocyanater er diphenylmethandiisocya-nat 2,4'- og 4,4'-isomerene inklusive den 2,2'-isomere 20 og de højere funktionelle polyisocyanat- og polymethy-lenpolyphenylisocyanatblandinger, der kan indeholde fra ca. 20 til 85 vægt% af de diphjenylmethandiisocyanatiso-mere. Typiske for de foretrukne polyisocyanater er de, der sælges i handelen som "Rubinat-M" (Rubicon Chemicals 25 Inc.) og "Papi" (The Upjohn Co.). I almindelighed har de organiske polyisocyanater en molekylvægt i området mellem ca. 100 og 10.000, og de anvendes normalt i mængder fra ca. 20 til 95 vægtdele, fortrinsvis 50 til 75 vægtdele, baseret på polyisocyanat-carbonatblandingen.The preferred polyisocyanates are the diphenylmethane diisocyanate 2,4'- and 4,4'-isomers including the 2,2'-isomer 20 and the higher functional polyisocyanate and polymethylene polyphenyl isocyanate mixtures which may contain from ca. 20 to 85% by weight of the diphenylmethane diisocyanatisers. Typical of the preferred polyisocyanates are those commercially sold as "Rubinat-M" (Rubicon Chemicals 25 Inc.) and "Papi" (The Upjohn Co.). In general, the organic polyisocyanates have a molecular weight in the range of about 100 and 10,000, and they are usually used in amounts ranging from approx. 20 to 95 parts by weight, preferably 50 to 75 parts by weight, based on the polyisocyanate-carbonate mixture.

30 De flydende cykliske alkylencarbonater, der an vendes i den pressede plade ifølge den foreliggende opfindelse, anvendes som nævnt i en mængde på fra 80 til 5, fortrinsvis 50 til 25 vægt%, baseret på isocyanat-carbonat-klæbemiddelblandingen, og kan f.eks. være pro-35 pylencarbonat eller butylencarbonat.The liquid cyclic alkylene carbonates used in the pressed plate of the present invention are used, as mentioned, in an amount of from 80 to 5, preferably 50 to 25% by weight, based on the isocyanate-carbonate adhesive mixture, and may e.g. . be propylene carbonate or butylene carbonate.

Som angivet ovenfor medfører tilsætningen af de flydende cykliske alkylencarbonater en væsentlig reduk- 5As indicated above, the addition of the liquid cyclic alkylene carbonates results in a substantial reduction.

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tion af klæbemidlets totale viskositet, hvilket letter påføringen. Typisk for viskositeterne for en PMDI-pro-pylencarbonat-blanding i centipoise (cP) ved 25°C er de nedenstående værdier, der er opnået under anvendelse af 5 en diphenylmethandiisocyanat-polymethylenpolyphenyliso-cyanat-blanding, der sælges kommercielt som "Rubinat-M" af Rubicon Chemicals Inc., hvilken blanding har en viskositet på 230 cP ved 25°c. Viskositeterne blev målt efter henholdsvis 1, 7, 12 og 28 dage ved forskellige 10 vægtforhold mellem polyisocyanat og propylencarbonat.the total viscosity of the adhesive, which facilitates application. Typical of the viscosities of a PMDI propylene carbonate mixture in centipoise (cP) at 25 ° C are the following values obtained using a diphenylmethane diisocyanate polymethylene polyphenylisocyanate mixture sold commercially as "Rubinate-M "by Rubicon Chemicals Inc., which has a viscosity of 230 cP at 25 ° C. Viscosities were measured after 1, 7, 12 and 28 days, respectively, at various 10 weight ratios of polyisocyanate to propylene carbonate.

230 cP Propylen- Centipoise efter isocyanat carbonat 1 dag 7 dage 12 dage 28 dage 3.0 0,5 78 80 80 80 15 2,5 1,0 35 34 36 37 2.0 1,5 19 20 20 20230 cP Propylene Centipoise after isocyanate carbonate 1 day 7 days 12 days 28 days 3.0 0.5 78 80 80 80 15 2.5 1.0 35 34 36 37 2.0 1.5 19 20 20 20

Desuden blev et fast diphenylmethan-4,4'-diisocyanat blandet med propylencarbonat i et vægtforhold 20 mellem den 4,4'-isomere og propylencarbonat på 2,5:1,0, 2,0:1,5 og 3,0:0,5 og gav henholdsvis en flydende blanding med mindre end 60 cP, en klar flydende blanding med 10 cP og en flydende blanding med mindre end 100 cP.In addition, a solid diphenylmethane 4,4'-diisocyanate was mixed with propylene carbonate in a weight ratio of the 4,4'-isomer to propylene carbonate of 2.5: 1.0, 2.0: 1.5 and 3.0: 0.5 and yielded a liquid mixture of less than 60 cP, a clear liquid mixture of 10 cP, and a liquid mixture of less than 100 cP, respectively.

25 Ligninen, der kan anvendes som fortyndingsmiddel i klæbemidlet, benyttes ifølge opfindelsen hensigtsmæssigt i en mængde fra 0 til 60 vægt%, fortrinsvis fra 20 til 35 vægt%, baseret på det totale klæbemiddel. Den nøjagtige sammensætning af ligninen varierer. Der kan i 30 klæbemidlet benyttes lignin opnået fra mange forskellige kilder til dannelse af den klæbende blanding. Een kilde er en blanding af affaldslud fra den kemiske pulpning af lignocellulose. Egnet lignin, der kan anvendes, omfatter f.eks. renset fyrretræslignin, kraftaffaldslud, 35 soda-affaldslud, calcium-, magnesium-, natrium- og ammo-niumbasesulfitlud, chloreret affaldslud osv. Der kan be-The lignin which can be used as a diluent in the adhesive is suitably used according to the invention in an amount of from 0 to 60% by weight, preferably from 20 to 35% by weight, based on the total adhesive. The exact composition of the lignin varies. In the adhesive, lignin obtained from many different sources can be used to form the adhesive mixture. One source is a mixture of waste liquor from the chemical pulp of lignocellulose. Suitable lignin which may be used include, for example, purified pine lignin, kraft waste liquor, soda waste liquor, calcium, magnesium, sodium and ammonium base sulphite liquor, chlorinated waste liquor, etc.

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e nyttes lignin fra nåletræ- og løvtrækilder, såvel som lignin fra syre-fældede og alkali-rekonstituerede kraftlud. De rigelige og tilgængelige chlorerede affaldslud fra papirmølleblegning kan benyttes. Affaldsluden kan 5 benyttes i sin oprindelige tilstand i den klæbende klæ-bemiddelkomposition. Ligninen kan også have et vidt område af pH-værdier og et faststofindhold fra ca. 10 til 90 vægt%. Når den anvendes, blandes ligninen simpelthen fysisk med isocyanat-carbonat-klæbemidlet, når dette er 10 fremstillet, eller den påføres direkte på det lignocel-luloseholdige materiale.e is used lignin from softwood and hardwood sources, as well as lignin from acid-precipitated and alkali-reconstituted kraft liquors. The abundant and available chlorinated waste liquids from paper mill bleaching can be used. The waste liquor can be used in its original state in the adhesive adhesive composition. The lignin can also have a wide range of pH values and a solids content of from approx. 10 to 90% by weight. When used, the lignin is simply physically blended with the isocyanate-carbonate adhesive when made or applied directly to the lignocellulosic material.

Lignocellulose, der benyttes til fremstilling af den omhandlede lignocelluloseholdige pressede plade, omfatter træflis, træfibre, høvlspåner, savsmuld, træ-15 uld, kork, bark og lignende produkter fra træbearbejdningsindustrien. Fibre, partikler osv. fra andre naturlige produkter, der er lignocelluloseholdige såsom strå, hørrester, tørret ukrudt og græsser, nøddeskaller, skaller fra kornafgrøder såsom ris og havre, og lignende kan 20 benyttes. Desuden kan de lignocelluloseholdige materialer blandes med uorganiske flager eller fibrøse materialer såsom glasfibre eller glasuld, mica og asbest såvel som med kautsjuk og plastmateriale i partikelform. Lig-nocellulosen kan have et fugtighedsindhold (vandindhold) 25 på indtil ca. 25 vægt%, men indeholder fortrinsvis mellem 4 og 12 vægt%.Lignocellulose used to manufacture the present lignocellulosic pressed board includes wood chips, wood fibers, wood shavings, sawdust, wood-15 wool, cork, bark and similar products from the woodworking industry. Fibers, particles, etc. from other natural products which are lignocellulosic, such as straw, flax residue, dried weeds and grasses, nutshells, shells from cereal crops such as rice and oats, and the like can be used. In addition, the lignocellulosic materials may be mixed with inorganic flakes or fibrous materials such as glass fibers or glass wool, mica and asbestos, as well as with rubber and plastic particles in particulate form. The lig nocellulose may have a moisture content (water content) of up to approx. 25%, but preferably contains between 4 and 12% by weight.

Ved fremstillingen af de omhandlede lignocelluloseholdige pressede plader, såsom f.eks. spånplader, maler eller blander man simpelthen en lille mængde af 30 klæbemidlet (med eller uden lignin) sammen med det lignocelluloseholdige materiale, så der fås en ensartet blanding. Almindeligvis sprøjtes isocyanat-carbonat-klæbemidlet (med eller uden lignin) på materialet, medens dette blandes eller holdes i bevægelse i et egnet 35 og konventionelt apparat. Der kan benyttes blandeappa-rater af mange forskellige typer såsom en intensiv- 7In the manufacture of the subject lignocellulose-containing pressed sheets, such as e.g. particle board, simply paint or mix a small amount of the adhesive (with or without lignin) with the lignocellulosic material to obtain a uniform mixture. Generally, the isocyanate-carbonate adhesive (with or without lignin) is sprayed onto the material while it is mixed or kept in motion in a suitable and conventional apparatus. Mixers of many different types can be used, such as an intensive 7

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shear-blander. Mængden af klæbemiddel er, baseret på vægten af ovntørret (0% fugtighedsindhold) lignocellulo-seholdigt materiale, fra 1,5 til 12, fortrinsvis 2,5 til 6,5 vægt.%. Lignocellulose-klæbemiddelblandingen 5 strøs eller formes i almindelighed i de ønskede mængder på en støtteplade (caul plate) af aluminium eller stål, der tjener til at føre "kagen" ind i pressen, så man opnår den ønskede tykkelse af produktet, idet pladerne er blevet sprøjtet eller overtrukket med et slipmiddel så-10 som metalsæbe, f.eks. jern-, calcium- eller zinkstearat-forbindelserne. Andre konventionelle slipmidler såsom natriumphenolat og visse tertiære aminer kan også benyttes .shear mixer. The amount of adhesive is, based on the weight of oven dried (0% moisture content) lignocellulosic material, from 1.5 to 12, preferably 2.5 to 6.5% by weight. The lignocellulosic adhesive mixture 5 is generally sprinkled or formed in the desired amounts on an aluminum or steel caul plate which serves to introduce the "cake" into the press to obtain the desired thickness of the product as the plates have become sprayed or coated with an abrasive such as metal soap, e.g. the iron, calcium or zinc stearate compounds. Other conventional release agents such as sodium phenolate and certain tertiary amines may also be used.

De nedenstående eksempler tjener til at illustre-15 re opfindelsen i overensstemmelse med dennes principper.The following examples serve to illustrate the invention in accordance with its principles.

I de følgende eksempler er de angivne prøveresultater udtrykt som ASTM D 1037-værdier, og de anvendte forkortelser har følgende betydninger: M.C. er "Moisture Content" (fugtigheds- 20 indhold) (%) I.B. er "Internal Bond" (indre binding) (psi) (kg/cm^) T.S. er tykkelsekvældning i koldt vand (25°C) ved 24 timers neddykning (%) 25 PMDI er en blanding af flydende diphenyl- methandi i socyanat-polymethylenpoly-phenylisocyanat med 46,5% diphenyl-methandi isocyanatindhold P.C. er propylencarbonat 30 B.C. er butylencarbonat TDI er toluen-2,4-diisocyanat TPMI er triphenylmethantriisocyanat 35 Eksempel 1 580 g fyrretræsspåner, tørret til et fugtigheds-indhold på 6%, anbringes i en åben omvæltningsblander.In the following examples, the test results indicated are expressed as ASTM D 1037 values and the abbreviations used have the following meanings: M.C. is "Moisture Content" (%) I.B. is "Internal Bond" (psi) (kg / cm 2) T.S. is thick swelling in cold water (25 ° C) at 24 hours immersion (%) 25 PMDI is a mixture of liquid diphenylmethane in socyanate polymethylene polyphenyl isocyanate with 46.5% diphenylmethane isocyanate content P.C. is propylene carbonate 30 B.C. is butylene carbonate TDI is toluene-2,4-diisocyanate. TPMI is triphenylmethane triisocyanate. Example 1 580 g of pine wood chips, dried to a moisture content of 6%, are placed in an open upheaval mixer.

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Under omvæltning sprøjtes 3,5 dele, baseret på 100 vægtdele af træet, af et isocyanat-baseret klæbemiddel, fremstillet ved at blande 71 dele rå flydende diphenyl-methandiisocyanat-polymethylenpolyphenylisocyanat (PMDI) 5 blanding med et diphenylmethandiisocyanatindhold på 46,5% og 29 dele propylencarbonat, over spånerne ved hjælp af et lufttrykdrevet system. To støtteplader på 30,5 x 30,5 cm sprøjtes jævnt med et zinkstearatslipmid-del til overfladebrug. Under anvendelse af en formkasse 10 dannes der en "kage" på 26,7 x 26,7 cm af spån-klæbemid-delblandingen på støttepladen. Den anden støtteplade anbringes over kagen, der presses til stop, der bestemmer en tykkelse på 13 mm, ved 190°C i 4½ minut, hvorpå den pressede kage udtages fra pressepladerne og skæres 15 til prøver for fysisk afprøvning. Prøveresultater for den pressede plade er 170 psi (12 kg/cm^) I.B. og en T.S. på 18,4%.While upturned, 3.5 parts, based on 100 parts by weight of the wood, of an isocyanate-based adhesive made by mixing 71 parts of raw liquid diphenylmethane diisocyanate-polymethylene polyphenylisocyanate (PMDI) 5 mixture with a diphenylmethane diisocyanate content of 46.5% and 29 are sprayed. part propylene carbonate, over the chips using an air pressure driven system. Two 30.5 x 30.5 cm support plates are evenly sprayed with a surface zinc stearate abrasive. Using a mold box 10, a "cake" of 26.7 x 26.7 cm of the particle adhesive mixture is formed on the support plate. The second support plate is placed over the cake pressed to a 13 mm thickness stop at 190 ° C for 4½ minutes, then the pressed cake is removed from the pressing plates and cut 15 for physical testing. Test results for the pressed plate are 170 psi (12 kg / cm 2) I.B. and a T.S. of 18.4%.

20 Eksempler 2-6Examples 2-6

Fremgangsmåden ifølge eksempel 1 genages bortset fra, at forskellige mængder propylencarbonat erstatter rå flydende diphenylmethandiisocyanat-polymethylenpoly-phenylisocyanat (PMDI) blanding med 46,5% diphenylme-25 thandiisocyanatindhold, idet det totale klæbemiddelind-hold holdes konstant på 3,5% baseret på træets vægt.The procedure of Example 1 is repeated except that different amounts of propylene carbonate replace crude liquid diphenylmethane diisocyanate-polymethylene polyphenylisocyanate (PMDI) mixture with 46.5% diphenylmethane diisocyanate content, keeping the total adhesive content constant at 3.5% based on wood weight.

TABEL 1TABLE 1

Eks. nr. PMDI P.C. _I.B._ T.S.Ex. No. PMDI P.C. _I.B._ T.S.

30 _{%)_(%) (psi) (kq/cm2) (%) 2 85 15 183 12,9 17,5 3 65 35 153 10,8 19,2 4 57 43 137 9,6 20,1 5 43 57 116 8,2 22,8 35 6 30 70 84 5,9 29,2(%) (Psi) (kq / cm 2) (%) 2 85 15 183 12.9 17.5 3 65 35 153 10.8 19.2 4 57 43 137 9.6 20.1 5 43 57 116 8.2 22.8 35 6 30 70 84 5.9 29.2

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Eksempler 7 - 10Examples 7 - 10

Fremgangsmåden ifølge eksemplerne 1 til 6 gentages bortset fra følgende ændringer: Det totale indhold af klæbemiddel holdes konstant på 4,5% baseret på træets 5 vægt. Der sættes til klæbemiddelblandingen en tredie komponent, lignin, et produkt der stammer fra den kemiske pulpning af lignocellulose. Indholdet af den flydende diphenylmethandiisocyanat-polymethylenpolyphenyl-isocyanat (PMDI) blanding med 46,5% diphenylmethandiiso-10 cyanat og carbonatindholdet varierer indenfor det i nedenstående tabel 2 angivne område.The procedure of Examples 1 to 6 is repeated except for the following changes: The total adhesive content is kept constant at 4.5% based on the 5 weight of the wood. A third component, lignin, is added to the adhesive mixture, a product derived from the chemical pulp of lignocellulose. The content of the liquid diphenylmethane diisocyanate-polymethylene polyphenyl isocyanate (PMDI) mixture with 46.5% diphenylmethane diisocyanate and the carbonate content varies within the range indicated in Table 2 below.

TABEL 2TABLE 2

Eks. nr. PMDI Lignin P.C. I.B. T.S.Ex. No. PMDI Lignin P.C. I.B. T. S.

_(JJ_(JJ_(%J_(psi) (kq/cm2) (%) 15 7 66,8 22,2 11,0 167 11,7 18,8 8 61,0 22,2 16,8 140 9,8 19,9 9 55,5 22,2 22,3 128 9,0 28,7 10 44,4 22,2 33,4 116 8,2 25,4 20(% Y_ (YY _ (% J_ (psi) (kq / cm2) (%)) 7 7 66.8 22.2 11.0 167 11.7 18.8 8 61.0 22.2 16.8 140 9, 8 19.9 9 55.5 22.2 22.3 128 9.0 28.7 10 44.4 22.2 33.4 116 8.2 25.4 20

Eksempler 11 - 15Examples 11 - 15

Fremgangsmåden ifølge Eksemplerne 1 til 10 gentages med følgende ændringer: Der anvendes butylencar- bonat i stedet for propylencarbonat. Klæbemiddelindhol-25 det i eksemplerne 11 til 15 holdes konstant på 3,5% baseret på 100 vægtdele træ. I Eksempel 11 anvendes 100% flydende PMDI med 46,5% diphenylmethandiisocyanat. Eksempel 15 inkluderer 22 vægt% lignin med et klæbemiddel-indhold på 4,5 vægt%. Indholdet af den flydende diphe-3 0 nylmethandiisocyanat-polymethylenpolyphenylisocyanat (PMDI) blanding med 46,5% diphenylmethandiisocyanat og procentmængden af carbonat varierer som angivet i tabel 3 nedenfor.The procedure of Examples 1 to 10 is repeated with the following changes: Butylene carbonate is used instead of propylene carbonate. The adhesive content of Examples 11 to 15 is kept constant at 3.5% based on 100 parts by weight of wood. In Example 11, 100% liquid PMDI with 46.5% diphenylmethane diisocyanate is used. Example 15 includes 22% by weight lignin with an adhesive content of 4.5% by weight. The content of the liquid diphenyl methane diisocyanate polymethylene polyphenyl isocyanate (PMDI) mixture with 46.5% diphenyl methane diisocyanate and the percentage of carbonate varies as indicated in Table 3 below.

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10 TABEL 3TABLE 3

Eks. nr. PMDI B.C. _I.B. T.S.Ex. No. PMDI B.C. _I.B. T. S.

____(%J_(%_)_(psi)(kq/cm2) (%) 11 100,0 - 158 11,1 20,1 5 12 78,0 22 168 11,8 17,8 13 70,0 30 159 11,2 19,0 14 55,0 45 135 9,5 24,6 15 56,0 22 127 8,9 27,2 10____ (% J _ (% _) _ (psi) (kq / cm2) (%) 11 100.0 - 158 11.1 20.1 5 12 78.0 22 168 11.8 17.8 13 70.0 30 159 11.2 19.0 14 55.0 45 135 9.5 24.6 15 56.0 22 127 8.9 27.2 10

Eksempler 16 (Sammenligningseksempel).Examples 16 (Comparative Example).

Fremgangsmåden ifølge eksemplerne 1 til 15 gentages bortset fra, at der benyttes phenolformaldehydhar- 15 piks (6%) som klæbemiddel, og at pressetiden er 9 minutter og pressetemperraturen 220°C. Nedenstående prøveresultater viser, at der må sættes en voks til det pressede materiale for at opnå ønskede egenskaber.The procedure of Examples 1 to 15 is repeated except that phenol formaldehyde resin (6%) is used as an adhesive and the pressing time is 9 minutes and the pressing temperature is 220 ° C. The following test results show that a wax must be added to the pressed material to achieve desired properties.

20 I.B. T.S.I.B. T. S.

(psi)(kq/cm2) (%) 101 7,1 32,3 25 Eksempel 17 - 21(psi) (kq / cm2) (%) 101 7.1 32.3 Examples 17 - 21

Der udføres en række forsøg i overensstemmelse med fremgangsmåden ifølge Eksemplerne 1 til 6 under anvendelse af 30 vægtdele propylen- og butylencarbonat og 70 vægtdele polyisocyanatkompositioner. Eksempel 21 er 30 en blanding af 70 dele PMDI, 15 dele P.C. og 15 vægtdele B.C.. Klæbemiddelindholdet holdes på 3,5 vægt% baseret på 100 vægtdele træ. Carbonatet og isocyanaterne samt prøveresultaterne er angivet i Tabel 4.A number of experiments are performed according to the method of Examples 1 to 6 using 30 parts by weight of propylene and butylene carbonate and 70 parts by weight of polyisocyanate compositions. Example 21 is a mixture of 70 parts of PMDI, 15 parts of P.C. and 15 parts by weight B.C .. The adhesive content is maintained at 3.5% by weight based on 100 parts by weight of wood. The carbonate and isocyanates as well as the test results are given in Table 4.

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11 TABEL 411 TABLE 4

Eks. nr. Alkylen- Polyiso- I.B T.S.Ex. No. Alkylene- Polyiso- I.B T.S.

__caerbonat cyanat (%) (psi) (kg/cm2) (%) 17 P.C. TDI 135 9,5 18,1 5 18 P.C. TPMI 141 9,9 20,2 19 B.C. TDI 136 9,6 17,6 20 BvC. TPMI 139 9,8 19,3 21 P.C. <©g B.C. PMDI 160 11,2 19,5 10 Ved sammenligning af de i sammenligningsekserapel 16 opnåede I.B.— og T.S.—værdier med de tilsvarende,i de øvrige ovenstående ekempler opnåede værdier ses det, at de pressede plader afølge opfindelsen er de kendte plader med phenolformaldehydharpiks som klæbemiddel væsent-15 lig overlegne med hensyn til de pågældende fysiske egenskaber .__caerbonate cyanate (%) (psi) (kg / cm2) (%) 17 P.C. TDI 135 9.5 18.1 5 18 P.C. TPMI 141 9.9 20.2 19 B.C. TDI 136 9.6 17.6 20 BvC. TPMI 139 9.8 19.3 21 P.C. <© g B.C. PMDI 160 11.2 19.5 10 When comparing the IB and TS values obtained in Comparative Example 16 with the corresponding values obtained in the other examples above, it is seen that the pressed plates of the invention are the known phenol formaldehyde resin plates as adhesive is substantially superior to the physical properties concerned.

Claims

A pressed plate consisting of lignocellulose-containing particles and a polyisocyanate adhesive, and optionally lignin, characterized in that the adhesive is present in an amount of from 1.5 to 12, preferably from 2.5 to 6.5 wt. based on oven-dried particles, and consisting of 20 to 95, preferably 50 to 75, weight percent of an organic di or polyisocyanate and 80 to 5, preferably 50 to 25, weight percent of a liquid alkylene carbonate.

Pressed plate according to claim 1, characterized in that from 0 to 60, preferably 20 to 35, by weight of lignin based on the total adhesive is added to the adhesive.

Pressed plate according to claim 1 or 2, 15, characterized in that the particles are wood particles.

Pressed plate according to claim 1, 2 or 3, characterized in that the di or polyisocyanate is a diphenylmethane diisocyanate or a mixture of diphenylmethane diisocyanate and the higher functional polymethylene polyphenylisocyanates.