CS200488B2 - Adhesive for manufacturing plywoods or particle boards or insulation boards - Google Patents

Abstract

Abstact of the Disclosure An adhesive for the manufacture of plywood, fiber board, particle board, and similar products, and containing the combination of pehnol formaldehyde resin, and a sulfate lignin. A major portion of the lignin derivatives have a molecular weight of over 5000.

Description

The invention relates to an adhesive for the production of plywood, particle board, fibreboard and the like.

In MS. patent δ. No. 188903 discloses a binder for the manufacture of plywood, particle board, fibreboard and the like, wherein the binder comprises lignosulfonates and phenol-formaldehyde resins and the subject matter of the invention is that most of the lignosulfonates used have a high molecular weight. Thus, the invention is based on the assumption that the adhesive properties of high molecular weight lignin derivatives are better than those of low molecular weight derivatives.

Binder according to MS. No. 188903 is therefore based on lignosulfonates obtained from a sulfite pulp process. However, it has been found that lignin derivatives obtained from alkaline pulp production processes can advantageously be used as a binder for the main application.

In the alkaline pulp production processes, the wood chips are heated under pressure with an aqueous sodium hydroxide solution. The most widespread alkaline production process is the sulphate process, in which the cooking liquor additionally contains sulphide and hydrosulphide ions. The leachate of the sulphate process, often called black lye, contains wood lignin in the form of derivatives soluble in alkaline solutions. These lignin derivatives are hereinafter referred to as sulfate || lignin.

i: It was found, as J. B. Doughty and C. F. Schulerud pointed out in their article Reactive Lignin Derived Products in Phenolic High Pressure Laminates, Tappi 44 (1961), 823-830, that sulphate lignin reacts poorly with phenol formaldehyde resins. Thus, an attempt has been made to produce a lignin product with better reactivity, for example by chemically treating black liquor or kraft lignin derived therefrom.

U.S. Pat. No. 3,185,645 discloses a process in which kraft lignin is precipitated from black liquor by acid and the lignin thus obtained, in acid form, is dissolved in a phenol-oxaldehyde resin. A volatile liquid such as methane, ethanol, or propanol is used as the solvent and the pH of the adhesive solution is maintained between 3 and 7. The patent tosses that the sulfate lignin can be separated into fractions by acid precipitation. It has been found that these shares have somewhat different characteristics. It will be appreciated by the inventors that all of these moieties are useful as long as lignin is in the free acid form.

The invention relates to an adhesive for use in the manufacture of plywood, fibreboard, particle board and the like of wood. The adhesive comprises a mixture of phenolforaaldelyrd resin and kraft lignin.

Poddtata invention consists in that the lignin derivatives are alkali salts aiyaailigoinů ⁴ piišemž adhesive comprises as alkalilígniny vysokoolo0lkkSálmí alkalliiniinovou oosahuuící fraction of at least 35% hmoonnotních ЛУаИНЕг !! ^ molecular hmootoosi greater than 5000, wherein the ratio hmoonootní aiyalilggnioů and fenolfomaldehydové resin 'between 90:10 to 20:80 based on dry matter.

Unexpectedly, it has been found that the moocular hmoonoot of sulphate lignin is of critical importance with respect to the tacky properties of the product and at least 35% of the 100%, preferably 40%, of the sulphate lignin should have a molecular weight of over 5,000. The lignin should be in the form of an alkali salt and the pH of the adhesive should be between 8 and 14.

When the inventive adhesives are used, the same production conditions, such as pressing times and temperatures, can be used, such as when using commercial phenolphomaldehyde resins in the manufacture of plywood. Since the plywood thus produced meets the requirements of the outdoor elastic and cast iron derivatives used for the adhesive are considerably cheaper than the phenol-formaldehyde resins, the use of the inventive adhesive is economically advantageous. Due to the mild alkalinity of the adhesive, the adhesive does not cause corrosion or hydrolytic defects in veneers, such as when using acid adhesives.

It is possible to produce a weatherproof chipboard using the inventive adhesive. This is a considerable advantage since the board sized with phenol-molybdenum is not weather-resistant. The advantage of the manufacturing process compared to other processes using a sulfuric liquor or lignosulfonates comprises a single-phase plate curing process and the short pressing times required for it. Corrosive and hydrolytic effects of acid adhesives are also excluded. The above advantages of the invention have a particularly beneficial effect from an economical point of view on an industrial scale production process.

With respect to the invention, it is only necessary to form a fraction such that at least 35% by weight, preferably 40% by weight, for example between 35 and 50% by weight of lignin derivatives, have a molecular weight of more than 5,000. The present invention is then considerably more advantageous and cheaper than, for example, adhesives of higher fluorescence properties.

The ligoin derivative may be sulphate lignin from an alkaline cellulose production process, for example a soda process wherein the cooking liquor comprises sodium hydroxide or a sulphate process wherein the cooking liquor comprises both sodium hydroxide and sodium sima and sodium hydrogen stearate; an alkaline process in the presence of oxygen, wherein the cooking is performed with sodium hydroxide in the presence of oxygen.

The invention is based on the unexpected facts found in the recent past. It has been investigated that fractionated derivatives in which at least 35% by weight, preferably 40% by weight, have a compound of greater than 5,000 may be prepared to provide a glue resistant to light and excellent strength for use in the manufacture of plywood, wood printing plates and fibreboard and equivalent products. In the preparation of the phenolic aldehyde resin used in the adhesive, phenol and formaldehyde are preferably used in a molar ratio between 1: 1.8 to 1: 3.

The lignin derivatives are most preferably used in the form of alkali or alkaline earth metal salts, which optionally contain an excess amount of the corresponding alkali. The alkalinity of the adhesive is advantageous since the alkaline adhesive causes less corrosion than the acidic adhesive. Further, for example, when sodium hydroxide is added to the adhesive, the sodium hydroxide will reduce the viscosity of the adhesive, and this will facilitate preparation and further handling of the mass.

In a preferred embodiment of the invention, the adhesive comprises 1 to 15, preferably between 5 and 10% by weight of urea, based on the dry matter amount of the phenol-formaldehyde resin. After at _f к Moving the urea formaldehyde resin the urea is reacted with an excess of formaldehyde, which binds to said excess of formaldehyde is present in the mixture. Thus, the use of urea in an adhesive increases the safety of work and allows excess formaldehyde to increase the strength properties of the adhesive to be used in conjunction with the production of phenol-formaldehyde resin. Together with formaldehyde, urea forms a stable polymerate, thereby increasing the adhesive strength in this way as well.

Urea can also be successfully applied to those phenol-formaldehyde-based adhesives from lignin, alkalilignin or lignosulfonate derivative components in which more than 50% of a molecular weight of more than 5,000 is used.

The molecular weight distribution of the lignosulfonates and the alkilignins can be determined by a gel chromatography method as exemplified by Whitaker, J. R., Anal. Chem. 35 (1963): 12, 1970-1953, Forssem, KG and Stenlund, BG, Paperi and Puu 48 (1966): 9, 565-574 and 11, 673-676, and Forssem, KG, Stenlund, BG and Sagfors, PE, Applied Polymer Symposium 28 (1976), 1185-1194, John Wiley and Sons, Inc.

In these procedures, samples are eluted by gel by column chromatography. The molecular weight distribution is determined based on the correlation between the molecular weights and the corresponding retention volumes. This correlation can be determined by determining the molecular weights of the different fractions by light scattering or by means of osmometry from an ultracentrifuge technique. These methods are very strenuous and it is therefore preferable in practice to calibrate the chromatographic gel column with readily obtainable substances having known molecular weights.

Such a substance is, for example, glucagon having a molecular weight of 3,483. It is also possible to compare the molecular weights of the lignin derivatives used in the adhesive of the invention with glucagon. Under these conditions, more than% by weight and preferably more than 45% by weight of the lignin derivatives used in the adhesive of the present invention have a molecular weight higher than that of glucagon.

In order to obtain the desired molecular weight distribution of kraft lignin from alkaline processes, ultrafiltration can be used in an analogous manner to separate lignosulfonates.

_The inventive adhesive is obtained by preparing an aqueous solution comprising a lignin derivative and a phenol-formaldehyde resin. Two basic types of phenol-formaldehyde resins are resols and novolaks, and both can be used in the invention. Resols are prepared using an alkaline catalyst at a ratio of phenol to formaldehyde by weight usually ranging from 1: 1 to 1: 5. Novolaks may be prepared using an acidic or alkaline catalyst cell, although an acid such as oxalic acid is preferred. The ratio of phenol to formaldehyde is usually in the range of 1: 0.8 to 1: 1. Novolaks require the addition of a curing agent such as paraformaldehyde, hexamethylenetetramine or furfuraldehyde.

The ratio of lignin derivative to phenolforaaldelyd resin when used for the production of plywood is 70:30 to 20:80, and for particle boards and corresponding products 90:10 to 20:80. The water content of the adhesive used can be 30-70% and the viscosity can be varied by controlling the water content or by heating the adhesive. A suitable viscosity range is typically 100 to 2000 mPas. Traditional fillers such as chalk, wood flour and wheat may be added to the adhesive.

When a particle board is manufactured using the inventive adhesive, paraffin may be added separately to the adhesive or chips to improve the swelling properties of the board.

The resolution of the alkalinity of the alkali and lignosulfonates was determined by the following procedure.

Samples were analyzed by gel chromatography using Sephadex columns (150 cm in length, 1 cm in diameter). Comparative lignosulfonate samples were eluted with a column containing Sephadex G-75 and using Tris / HCl buffer (pH 8.0, 0.1 M) containing

NaCl (0.5 M) as the eluent, while the alkalilinins dissolved in sodium hydroxide solution in water were eluted with a Sephadex G-50 column using NaOH (0.5 M) as the eluent. The elution rate was 20 mi / h.

The lignin coincidence in the elution fraction was determined by absorption measurements (280 nm). The retention volume was determined by weighing the elution fractions.

In order to obtain results independent of the gel filling density, a relative scale of the retention volume was introduced using two calibration substances as internal standards. Retention. the blue dextrinium peak (M = 2.10 ^) was accepted as the first reference point giving a zero value. The second reference point, equal to 1, was obtained by determining the retention peak obtained with sulfosalicylic acid (M = 218) (Fig. 1, Sephadex C-75 and Fig. 2, Sephadex G-50).

Column calibration was performed by simulating the ratio of the logarithm of the molecular weight to the relative retention volume for substances of known molecular properties that were readily obtainable. The Sephadex G-75 column was calibrated using egg albumin (M = 45,000), chymoorypsinogen A (M = 25,000), cytochrome C (M = 12,500) and glucagon (M = 3,483) as reference. tri / HCl buffer solution (pH 8.0, 0.1 M) containing NaCl (0.5 M). (Figures 1 and 3). ...

The Sephadex G-50 column was calibrated using reference cytochrome C, glucagon and bacitracin (Μ = 1,423) and as an eluent of sodium hydroxide (0.5 M) (Figures 2 and 4).

Thus, those lignin derivatives that elute with a gel column more rapidly than glucagon (which have a lower relative retention volume) consist of moiects having a molecular weight greater than 3,483 (glucagon).

The invention is further described in the embodiments referring to the accompanying drawings, in which Figures 1 and 2 show the elution of calibrators and internal standards by a column of gel-X-ray gallows from Sephadex · G-75 and Sephadex G-50 determined by absorbance at 280 nm. and 4 illustrate a comparison of logarithms of molecular weights versus relative retention volume for calibrators determined by the light scattering method in the elution method;

Fig. 5 a / ab / shows gel chromatograms · a distribution of mmoekular properties of unfractionated (A ^z ) and fractionated (B ') · comparative lignosulfonate samples from Weeiern Hemlock waste liquor; Fig. 6 shows gel chromatognes of non-fractionated (A) and fractionated (B, C, D, E and F) lignins from kraft-wood pine and ob. 7 shows the cumulative distribution of molecular properties corresponding to the chromatognes in FIG. 6.

The following example illustrates the suitability of two black liquors for preparing the adhesive. One was the black liquor evaporated to a dry matter content of 37.5%, the other was the sulphate lignin obtained from the black liquor by acid precipitation. The sulfate lignin was dissolved in sodium hydroxide solution after filtration and washing. (See Table I).

Example 1 (comparative example)

Table AND black liquor acid precipitated kraft lignin dissolved in NaOH solution dry matter 37.5% 37.5% pH 12.7 12.2 viscosity measured by Brookfield RVT-viscometer, 23 ° C 43 mPaS 3,336 mPaS weight molecular distribution weight M.h. > 5,000 25% 32% M.h. > 10,000 14% 18% M.h. > 15,000 9% 11%

Adhesives were prepared as follows: 450 g of NaOH acid-precipitated sulfate lignin solution was mixed with 500 g of resol type commercial phenol-formaldehyde resin with a dry matter content of 46%.

g of a mixture containing 30 parts by weight of wood flour, parts by weight of chalk and 20 parts by weight of wheat flour was added to the solution.

The adhesive was coated on birch veneer 1.5 mm thick with a moisture content of about 3%. The amount of adhesive applied to each side of the veneer was 150 gAr-. By? у prepared three-layer boards. The pre-compression pressure was 0.7 MPa and the time was 7 minutes. The temperature of the hot pressing was 135 ° C, the pressure was 1.6 MPa and the time was 4 minutes and 2 minutes.

The properties of the boards produced were determined according to the Finnish standard 0.IV.1 and are given in Table II.

Table II shows that using both adhesive mixtures it was possible to prepare plywood with shear stress values that meet the requirements of Finnish Standard 0.IV.1. Wood cracking, which is of utmost importance in terms of weather resistance of the product, does not meet all requirements. As shown in the table, these values could not be improved even by a double pressing time.

Table II

* Press time min Dry shear stress MPa wet cracking wood % shear stress MPa cracking wood % black liquor 2 2, 44 57 1, 60 8 4 2.85 73 1, 68 12 acid precipitated 2 2.64 68 1.60 23 sulfate lignin 4 2.81 76 1, 80 27 Mar: Finnish Standard 2.09 50 1.41 50

б

Example 2

Preparation of plywood using kraft lignin in a molecular weight distribution adhesive as required by the invention.

The sulfate lignin derivative, which was separated from the black liquor and had the following properties, was used to prepare the adhesive:

Table III

Lignin derivative separated from black liquor dissolved in NaOH solution

Dry matter 37,5%

Viscosity measured

Brookfield RVT viscometer

Deň: 18 ° C 45 41 pH 4,5 Weight distribution molecular weight M.h. > 5,000 58% M.h. > 10,000 38% M.h. > 15,000 24%

450 g of a NaOH solution of the above lignin derivative was mixed into 550 g of phenol-formaldehyde resol with a dry matter content of 46%. The viscosity of the mixture was 388 mPaS at 23 ° C. 84 g of a mixture containing 30 parts by weight of wood flour, 50 parts by weight of chalk and 20 parts by weight of wheat flour were added to this solution. After this addition, the viscosity was 1000 mPaS at 23 ° C.

The production conditions of the plywood were the same as in Example 2. The properties of the plywood are given in the following table:

Table IV

pressing time min dry shear MPa wet shear stress MPa cracking wood and voltage cracking wood% 2 3.01 89 1 »73 ⁸⁰ 4 3.20 9i 2.00 96 Finnish Standard 2.09 & 50 ь 1,41 50

The boards fully complied with the requirements of Finnish standard O.IV.1 for outdoor plywood.

Example -3

Production of particle board,

An adhesive was prepared using kraft lignin as in Example 8. 540 g of a 46% aqueous solution containing 210 g of kraft lignin and 40 g of sodium hydroxide was admixed into 460 g of a resol type commercial phenol-formaldehyde resin with a dry matter content of 46%.

The viscosity of the adhesive was 1040 mPaS at 23 ° C and the pH was 12.0.

184 g of paraffin emulsion (dry matter 50%, the viscosity of which was then 850 mPaS / 23 ° C as measured by a Brookfield RVT viscometer) were mixed into the adhesive. A three-layer particle board was prepared containing an outer particle layer and a 70% inner particle layer. The dry matter of the sprayed adhesive was 12% of the dry mass of the surface chips and 10% of the chips of the inner layer. The chip moisture content was about 1% before gluing and about 11% after gluing. The plate thickness was 15 mm and the density was 750 kg / m 2. The pressing temperature was 210 DEG C., the pressure was 2.7 MPa and the time 60 s / mm. The board properties given in Table V were determined in accordance with German standards DIN 52 360-65 and 68 761.

Table V

Flexural strength MPa tensile strength MPa thickness 2 h % swelling 24 h % V 100 MPa invented t adhesive 20.8 0.62 1.9 12.9 0.25 requirements to DIN 18.0 0.35 6.0 15.0 0.15

As can be seen from Table V, the inventive adhesive can be used in the manufacture of particle board that meets the West German (DIN) standards for weatherproof particle board.

Example 4

The sulphate waste liquor from pine cooking (Pinus silvestris) was concentrated to a dry matter content of 33%. The pH of the solution was 12.7. The molecular weight distribution was determined using a Sephadex'G-50 column as described above. The chromatogram obtained is shown in FIG. 6 (A). The molecular weight distribution, Fig. 7, (A) was calculated using the calibration graph shown in Fig. 4. Accordingly, 25.3% by weight of alkilignins in kraft waste liquor had a molecular weight of more than 5,000 and 32.9% by weight had a molecular weight of greater than 3,483 (glucagon).

A 1: 2.5 molar ratio of phenol to formaldehyde was used to prepare the phenol-formaldehyde resin. The resin had a dry matter content of 46% and a pH of 11.1. The adhesive was prepared by mixing the phenolic resin (450 g) with the evaporated kraft waste liquor (418 g). The mixture was blended for 10 minutes and then 132 g of a filler mixture containing wheat flour (13 g), kebrač (32 g), chalk (61 g) and wood flour (26 g) were added. The adhesive had a viscosity of 240 mPas and a pH of 12.1.

The adhesive was used to make three-layer birch veneer boards. The deposition was 150-150 g / cm @ 2 of pre-pressures of 70 bar and a pre-pressing time of 6 minutes. The plates were hot pressed at 135 ° C at a pressure of 1.7 MPa, the pressure times used were 2.3 and 4 minutes.

The board properties were determined in the dry state and after cooking according to the Finnish standard for plywood SFS ^ 2 416. The board properties are given in Table VI, where each digit is an average of 5 measurements.

Example 5

The waste kraft liquor of Example 4 was subjected to ultrafiltration to obtain an alkalilignin product whose molecular weight distribution is shown in Fig. 7, graph V (gel chromatogram), in Fig. 6, B. Accordingly, 30.9% by weight of the lignin derivatives had a molecular weight of greater than 5,000 and 40% by weight had a molecular weight of greater than 3,483 (glucagon). The adhesive was prepared as in Example 4 using the same fentlic resin.

The viscosity after the addition of filler was. 320 mPa.s.

Using this adhesive, three-layer veneer sheets were produced under the same conditions as in Example 4. The properties of these sheets are shown in Table VI.

Example-6

The alkaline product was isolated by filtration of the waste kraft liquor. Its molecular weight distribution was determined by gel-chromooraflion, the chromatogram being shown in Fig. 6, and the moocular mass distribution in Fig. 7, respectively. 5% by weight had a molecularocmolar content greater than 3,483 (glucagon). The adhesive was prepared as in Example 4. The adhesive had a viscosity of 420 mPaas and a pH of 12.0.

Using this adhesive, three layers were produced. birch veneer panels as in Example 4 and the properties of these panels are shown in Table VI.

Example 7

Ullraffltrací was prepared alkaliligo ^ι 0nsvá fraction having chromatogrim gel is shown in Fig. 6, D, -a division of m ^ o ^ <^^ i ^; ^ ltvé ЬооОпои in FIG. 7, D. Accordingly, 43.2% by weight The alkilignins had a moteculus weight greater than 5,000 and 54.1% by weight had a moteculus weight greater than 3,483 (glucagon).

The adhesive was prepared as in Example 4 and had a viscosity of 470 ° C and a pH of 12.0. Using tshsts glue, triple layer birch veneer sheets were produced as in Example 4. The properties of these sheets were found in Table VI.

PPExample. ;

The waste kraft liquor used in Example 4 was ultrafiltered to obtain the alkaline-nignal fraction, whose gel chromatography is given in tbr. 6, E. Rotation of motcultural mass is shown in tbr. Accordingly, 46.9% by weight of the Hron derivatives have a molecular weight greater than 5,000 and 57.7% by weight has a molecular weight greater than 3,483 (glucagon).

The alkaliignin fraction was used to prepare the adhesive as in Example 4. The filler addition viscosity was 560 mPa · s and the pH was 11.9. Three-ply veneer boards were produced using the adhesive, as in Example 4. The properties of the boards are shown in Table VI.

Example 9

The filtration was used to isolate the high-solid alkali metal fraction from the waste kraft liquor used in Example 4, wherein the gels chromium attgram of this fraction is shown in FIG. 6, F and weight distribution in tbr. 7, F, wherein 53.4% by weight of the alkilignins had a molecular weight greater than 5,000 and 64.7% by weight had a molecular weight greater than 3,483 glucagon).

The adhesive was prepared as in Example 4. Its viscosity was 680 mPa · s at 25 ° C and needles pH 11.8. The adhesive was used in the manufacture of three-layer birch veneer sheets under the same conditions as in Example 4 The properties of the boards are shown in Table VI.

Example 10

Alkalilignin was precipitated from the Black liquor used in Example 4 with hydrochloric acid. The precipitated lignin was filtered off, washed and dissolved in sodium hydroxide solution. The pH of the solution was 12.2 and the dry matter content was 33%. The molecular weight distribution was determined as described above, according to which 38% by weight of alkilignins had a molecular weight greater than 3,483 based on glucagon and 29% by weight had a molecular weight greater than 5,000.

The adhesive was prepared in the same manner using the same commercial phenol formaldehyde resin as in Example 4. The viscosity of the adhesive composition was 284 mPa · s, measured at 25 ° C with a Brookfield RVT-viscosimeter. The pH was 12.2 and the ratio of alkilignins to resol based on dry matter was 40:60.

Using this adhesive, three-layer birch veneer boards were made as in the example and the properties of these boards are shown in Table VI.

They did

Alkalilignin was precipitated from the black liquor of Example 4 using carbon dioxide. The precipitated alkalilignin was filtered off, washed and dissolved in sodium hydroxide solution. The pH of the alkalilignin solution was 12.0 and the dry matter content was 33%. The molecular weight distribution was determined according to the procedure described above. Of the alkilignins, 44.2% by weight had a molecular weight of more than 3,483 based on glucagon and 34% by weight greater than

000.

Using the same phenol-formaldehyde resin and composition as in Example 4, an adhesive having a pH of 12.2 was prepared. In the adhesive composition, the ratio of lignin to resol, based on dry matter, was 40:60. The viscosity of the adhesive composition was 528 mPa · s at 25 ° C as measured by Brookfield. RVT viscometer.

Using this adhesive, three-layer birch veneer boards were prepared as in Example 4. The properties of these boards can be read from Table VI.

Example 12

The alkali-lignin fraction was separated from the black liquor from the Finnish pulp mill by ultrafiltration. The molecular weight distribution was determined as described above and 42.0% by weight of alkilignins had molecular weights in excess of 3,483 based on glucagon and 31% by weight greater than 5,000. The pH of the solution was 11.0 and the caustic was evaporated to a dry matter content of 33%. . ’

An adhesive was prepared using the same formaldehyde resin and composition as in Example 4. The viscosity of the adhesive composition was 420 mPa · s at 25 ° C as measured by a Brookfield viscometer.

Using this adhesive, three-layer birch veneer boards were prepared as in Example 4. The properties of these boards were found in Table VI.

Example 1 a d 13

The black liquor of Example 12 was subjected to ultrafiltration and the alkalilignin fraction was separated. The molecular weight distribution was determined. 50% by weight of alkilignins had a molecular weight greater than 3,483 based on glucagon, and 41% by weight had a molecular weight greater than 5,000.

An adhesive was prepared using the same composition as in Example 4. The pH of the alkali was 10.8 and the pH of the adhesive mixture was 11.3. The viscosity of the adhesive composition measured at 25 ° C with a Brookfield viscometer was 1520 mPa · s. ’

Using this adhesive, three-layer birch veneer sheets were produced as in Example 4. These boards are listed in Table VI. ,. 4

As specified in the Finnish standard for plywood SFS 2,415, the shear strength in the dry state should not be less than 2.10 MPa, after cooking should not be less than 1.40 MPa, and if these values are lower, it is broken:! in wood should not be less than 50%. In practice, however, a considerably higher failure in wood is required, that is, higher than 80% after cooking.

A detailed examination of the properties of the plates shown in Table VI reveals that the requirements were achieved in experiments 6 to 8 p in experiments 12 and 13 already with a 2 and 3 minute lysis times. The adhesive of Example 5 required a longer pressing time to meet the requirements. In Examples 4, 10 and 11, the extended pressing time was not useful: the adhesive bond could not harden to become waterproof.

Table VI ^;

Comparison of the sticky properties of the waste kraft liquor of different alkali (5 fractions)

Example of pressing ^{in the} dry state after the cooking time

min tensile strength MPa wood breach% tensile strength MPa ' wood breach% 4 2 1.80 57 0.55 8 3 1, 84 70 0.63 14 4 1.98 73 0.71 12 5, 2 2.00 63 '37 38 3 2.10 80 1.38 39 ' 4 2.08 90 1.50 82 6 2 2.20 88 1.43 71 3 2.42 93 1.55 89. 4 2.39 98 1.71 94 7 2 2.35 90 1.49 88 3 2.40 92 1.68 97 4 2.42 92 1.65 98 8 2 2.46 98 1.58 90 3 2.55 .96 1.63 93 4 2.43 99 1.70 96 9 2 2.57 100 ALIGN! 1, 65 99 3 2.60 100 ALIGN! 1.76 100 ALIGN! 4 2.58 98 1.72 92 10 2 2.61 68 1.56 23 4 2.74 76 1.75 27 Mar: 1 1 2 2.33 40 1, 85 39 4 2.61 .42 1.56 38 12 2 2.74 69 1.56 71 4 2.85 93 1.85 94 13 2 2.91 87 1.78 72 4 2.81 95 1.69 95

1 • 200488

Example 14

For the preparation of the adhesive, alkilignin was used in which the high molecular weight (molecular weight greater than 5,000) was 48% by weight of all lignin derivatives and 59% by weight had a molecular weight higher than the molecular weight of glucagon.

The phenol-formaldehyde resin was prepared with a molar ratio of 1: 2.2 and contained

1.7% free formaldehyde. 5% urea, based on dry weight, was added to the resin. The mixture was stirred at room temperature for 5 hours. The amount of free formaldehyde thus decreased to 0.08%. The resin-urea mixture was added to an alkalilignin solution having a 42% solids content (432 g 51% resin to 524 g lignin solution). 1.4 g of 50% sodium hydroxide solution were added. The mixture was stirred for 30 minutes, and the pH was 1.8. The viscosity was 320 mPa.s at 25 ° C.

Particle boards were made using this adhesive. To this was then added 10% and paraffin emulsion (dry weight based on dry weight of the adhesive).

Using this adhesive, chipboards of 15, 20 and 30 mm thicknesses were produced having a nominal weight of 750 g / m 3. The amount of chip adhesive sprayed was 10% by weight, based on dry matter. Contact and high-frequency heating was used for hot pressing. The press plate temperatures were 180 ° C and the pressure was 2.65 MPa. Press plates and plate properties can be found in Table 7.

The requirements required by the German standard DIN 68 761 for phenolically bonded particle boards have been fully achieved for these boards. The plates were completely free of formaldehyde after hot pressing.

Example 15

A phenol-formaldehyde resin having a molar proportion of phenol to formaldehyde of 1: 3 was prepared for the adhesive. After preparation, it contained 4.8% free formaldehyde. 10% urea was added to the resin and the mixture was stirred at 25 ° C for about 4 hours. The mixture was then allowed to stand for an additional 24 hours and free formaldehyde was determined. Its amount decreased to 0.1%.

The alkali-lignin fraction, the properties of which were given in Example 14, was used to prepare the adhesive. To 640 g of alkalilignin solution, with a dry matter content of 42%, 360 g of phenol-formaldehyde urea resin, with a dry matter content of 50%, was added. The proportion of lignin to the phenol-formaldehyde resin was 60:40. The adhesive had a pH of 11.0.

The adhesive was used to produce formaldehyde-free particle board. The amount of adhesive was 8%, based on dry matter, calculated on the weight of dry center chips and 10% by weight of the surface chips. The chips were then sprayed with paraffin emulsion in an amount of 1% dry matter to the weight of the dry chips.

Using this glue, 15mm three-layer particle board with a density of 750 kg / тЗ was produced. The press plate temperature was 215 ° C, the press pressure was 2.96 MPa and the press time was 20 s / mm. After hot pressing, the plates were hardened at 180 ° C. The properties of the plates are given in Table VIII.

200488 ₁₂

Table VII.

Properties of particle board using combined contact and high frequency heating ·

plate thickness mm pressing time used bending strength MPa tensile strength MPa. tloušika 2 h% V 100. 24 h % swelling MPa min s / mm 15 Dec 4 1/2 18 19.8 0.47 2.3 11.5 0.21 20 May 5 ' 15 - 19.2 0.52 1,8 10.8 0.19 30 5 1/2 1 1 19.2 0.49 2.2 11.1 0.23 requirements DIN 68 761 * 17.7 * 0.34 4 6,0 • i 12.0 * 0.15

Table VIII Properties of triple-edge boards when using hardening plate thickness volumetric strength strength Thickness V 100 swelling C. mm hmoOnost in bend in turn % % kg / m3 MPa MPa 2 h 24 h MN / mm 2 1 15.08 760 20.6 0.47 2.4 9.8 0.18 2 15.10 758 20.3 0.46 2.5 10.2 0.19 3 15.08 756 20.5 0.55 ', 9 10.5 0.21 4 15.09 762 20.9 0.54 2.8 1 1, 0 0.20 5 16.10 755 19.4 0.46 2.5 10.8 0.15

The boards reached the requirements of DIN 68 761. No formaldehyde odor was detectable during production and even then no formaldehyde was released from the boards.

Example 16

The lignin fraction of Example 7 was used in an adhesive intended for gluing Douglas fir veneers. The phenol-formaldehyde resin used in the adhesive had a dry matter content of 40 pH of 11.5% and a viscosity of 480 mPa.s, at 25 ° C.

The glue mixture was prepared as follows: to 170 g of a 33% alkali metal solution was added 46 g of water (25 ° C), 206 g of phenolforaaldehyde resin (40% dry matter), 88 g of co-cobu and 22 g of wheat moniage. The mixture was stirred for 5 minutes and 30 g of 50% sodium hydroxide was added with stirring. Then 15 g of anhydrous sodium carbonate was added and stirring was continued for 30 minutes. 170 g of alkaliignin solution, 46 g of water and 206 g of phenol-aldehyde resin were additionally added and the adhesive mixture was stirred until homogeneous.

The viscoozta adhesive composition measured at 25 ° C with a Brookfield RVT viscometer was

500 mma.s. The ratio in phenolphomaldehyde resin; based on dry matter, it was 40:60 and the pH was 11.9. ’

Using glue, 5-ply 2.54 mm plywood plywood panels were made using 2.54 mm veneers. The adhesive coating was 58 lbs / Mdgl, a pre-press time of 3 min and a pressure of 1.37 MPa. The open veneering time was 20 minutes and the closed time 30 minutes. The hot pressing temperature was 149 ° C and the pressure was 1.37 MPa. The pressing times that were used are shown in Table IX. Panel properties were determined according to US Product Standard 1-74 and are listed in Table IX.

Table IX

Number of layers veneer thickness applied quantity 1 bs / Mdgl press. hot vacuum test cooking test temp. Noc: 2 ° C time min. shear stress MPa breaking wood % shear stress MPa breaking wood % 5 2,54 .mm 58 149 3.5 2.76 100 ALIGN! 2.26 100 ALIGN! 1.98 86 2.02 95 1, 84 90 1.71 83 2.06 96 1-, 85 90 H II II ·· 4,5 1, 82 94 1.56 99 2.19 82 2.08 88 5 2.54 mm 58 149 3.5 2.20 90 2.13 95 2.09 95 2.06 90

* Example 17 '

The preparation of the alkilignins described in Example 8 was used and was used in the composition of the adhesive developed for the production of triple plate. For this purpose, the alkilignin solution was evaporated to a dry matter content of 45%. The phenolforaaldehyde resin used was a commercial resol type foraaldehyde resin. .

556 g of alkalilignin solution were mixed with - 363 g of phenolforaaldehyde resin (46% dry matter) and 81 g of 50% sodium hydroxide solution. The viscosity of the adhesive was 1,100-mPp.s at 25 ° C, as measured by a Brookfiedd viscometer, and the pH was 12. The ratio of alkilignin to phenolforaaldehyde resin, based on dry matter, was 60:40. 100 g of paraffin emulsion having a dry matter content of 50% was mixed into the adhesive before the chips were inserted. Then the viscosity at 25 ° was 840 mPaS.

The adhesive was used in the manufacture of three-layered chipboard boards containing 30% - chips for the outer layer and - 70% chips for the inner layer. The amount of adhesive sprayed onto the chips was 12% (calculated on dry matter) for surface chips and 10% for internal chips. The moisture content of the chips was about 1% before gluing and about 11% after gluing. The thickness of the plates was 15 mm and the density was 750 kg / m @ 2. The plates were hot pressed at 204 ° C, at a pressure of 25 bar and for 60 s / mm.

Properties of boards determined according to German standards 52 365 and 68 761 - are listed in the table. X, each value being the average of 5 plates or 25 test pieces.

Table X ‘ flexural strength tensile strength botnění v tloušlce tensile strength MPa MPa 2 h 24 h after cooking % % (V 100), MPa 19.0 0.604 1.9 12.9 0,25, i 17.55 -0.343 ^from 6.0 - 12,0 - 0,14 1 Requ. DIN Example 18 Lignin fraction of Example 9 in aqueous solution of dry matter content 45% was used

in an adhesive composition for the manufacture of particle boards using both contact and high frequency heating during hot pressing.

405 g of the alkalilignin solution (45% dry matter) were mixed with 474 g of the commercial phenol-formaldehyde resin of Example 6 (46% dry matter). The ratio of lignin to phenol-formaldehyde resin, based on dry matter, was 40:60. 90 g of paraffin emulsion (50% dry matter) was added before the chip adhesive was sprayed. The viscosity at 25 ° C was now 350 mPa.s.

The adhesive composition was used to produce particle board using a combination of contact and high frequency heating during hot pressing. The temperature of the press plates was 180-200 ° C. A 4 kW high frequency generator operating at a frequency of 13.6 MHz was used. Three-layer particle board containing 70% of internal chips and 30% of external chips was produced. The adhesive was sprayed onto the chips at 10% for the chips for the inner layer and 12% for the chips for the outer layer. The chip humidity was 1 to 2% before and 11 to 12% after gluing.

Plates of 20 mm and 30 mm thickness and a density of 650 kg / m 3 were prepared using pressing times of 10, 15 and 20 s / mm. The swelling properties after soaking in water for 2 and 24 hours and the tensile strength after cooking (V 100) were determined according to German standards, see Tab. XI.

Table XI

pressing time s / mm plate thickness mm swollen thickness tensile strength after cooking (V 100), MPa 2 h% 24 h% 10 20 May 10.2. 20.1 0.12 15 Dec H 6.3 12.0 0.16 20 May 4.1 10.3 0.22 10 30 8.0 16.6 0.14 15 Dec 1 * '4,2 11.0 0.19 20 May II 1.5 S, 3 0.25 DIN requirements é6.0 - 12,0 > 0.14

Example 19

The alkali-lignin fraction of Example 9 was spray dried to a powder with a moisture content of 4%. Phenol-formaldehyde resin developed for the production of particle board having a dry matter content of 53%, a viscosity of 272 mPa.s at 25 ° C and a pH of 11.5 was used for the production of the boards.

To 1000 g of the resin solution 212 g of paraffin emulsion with a dry matter content of 50% before gluing was added. The alkali-lignin powder was mixed with the chips in an amount of 5% dry powder for dry chips. Then the phenol-formaldehyde paraffin solution was sprayed onto the chips in an amount of 6% dry matter on dry chips. The moisture content of the chips was 2% before and 8

12 mm plates were produced by hot pressing at 215 ° C and 2.91 MPa using a pressing time of 40 s / mm. The properties of the plates are given in Table XII.

Table XII

density density kg / m3 flexural strength MPa tensile strength MPa thickness 2 h % swelling 24 h% ' tensile strength after cooking (V 100), · MPa 700 19.2 0.48 4.0 13.5 0.16 H 17.8 0.45 3.8 14.2 0.165 II - 20.0 0.55 4.1 14.3 0.145 H 21.3 0.52 3.8 14.0 0.17

Example 20

For the production of fiber boards, an adhesive was prepared using the preparation of the alkalilignin of Example 7 and a commercial phenolforaaldelyd resin.

400 g of a 25% alkali metal solution were mixed with 375 g of a 40% phenol-formaldehyde resin and 8,225 g of water to form a 5% solution having a pH of 12.0. The ratio of lignin to phenolphomaldehyde, based on dry matter, was 70:30. The adhesive was used for the production of fiber boards. The adhesive was added to the fiber suspension, followed by the addition of an aluminum sulfate solution with a dry matter content of 2% to precipitate the resin solids on the fibers. Adhesive solids, as well as aluminum sulphate, were added in an amount of up to 1% based on dry fibers. The fiber plates were produced at 200 ° C, a printing pressure of 0.68 Pa.s and a pressing time of 5 minutes. The plates were subsequently cured at 160 ° C for 4 minutes. Their properties are shown in Table XIII.

Table XIII.

Example bending strength MPa tensile strength MPa absorbed water 24 · h,% swelling thickness 24 · h,% 15 Dec 53.3 24.5 23.6 19.2 16 51.7 24.2 25.5 18.0 17 48.9 23.8. . 27.0 17.0 18 46.6 24.0 25.8 17.5

SUBJECT OF THE INVENTION

Claims (4)

SUBJECT OF THE INVENTION 1. An adhesive for the manufacture of plywood, particle board or fibreboard, comprising: - lignin derivatives and phenol-thialialdehyde resins, characterized in that the lignin derivatives are alkali alkali-alkali salts, wherein the adhesive comprises as high alkali alkali lignin fractions at least 35% The molecular ratio of alkalinegnins to phenolphomaldehyde resin is between 90:10 and 20:80, based on dry weight. 2. An adhesive according to claim 1, wherein 35 to 50% by weight of the alkaline substances have a molecular weight greater than 5,000. 3. An adhesive according to claim 1, characterized in that at least 50% by weight of the alkalinegiins have a molecular weight greater than 5,000. 4 Sheets · Drawings SinvvofrofM. n. livod 7. Moit