FI58788B - BINDEMEDEL BESTAOENDE AV ENLIGT MOLEKYLVIKTEN FRAKTIONERADE LIGNINDERIVATER OCH FOERFARANDE FOER FRAMSTAELLNING AV DETSAMMA - Google Patents

Description

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JM · lJ '' UTLAQG NI NOSSKHI FT 30/00 ^ (45) Patent granted 10 04 1931 'Patent neddelat ^ ^ (51) Kv.ik.3 / int.a.3 0 09 J 3/28, 3/16 FINLAND —FINLAND (21) P * t «nuis * k.mu * -Pit» t «» eknln | 773091 * (22) HakamlipltvtAn «6kninpdag 18.10.77 ^ '(23) Alkupllvl — Glltl | h # ti4» g 18.10.77 (41) Tullut kiikikuksi - Bllvlt offuncllg 19. OU. 79

National Board of Patents and Registration .... ........,,. .....

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Patent · och reglsterityrelien AnaMcan utJagd odt uti. * Krifun puUkend 31.12.80 (32) (33) (31) Requested «uoUteu * —Saglrd prlorlut (71) Metsäliiton Teollisuus Oy, Revontulentie 6, 02100 Espoo 10, Suomi-Finland (FI ) (72) Kaj G. Forss, Helsinki, Agnete GM Fuhrmann, Helsinki,

Suomi-Fin1and (FI) (7 * 0 Berggren Oy Ab (5I +) Binder consisting of molecular weight fractionated lignin derivatives and method for its preparation -Bindemed best available molecules for the fractionation of lignin derivatives and fractions derived from decamma

The invention relates to a binder for the production of plywood, particle board and fibreboard and the like, which binder consists of phenol-formaldehyde resin and lignin derivatives fractionated according to molecular weight. The invention further relates to a process for preparing a binder according to the invention, in which a phenol-formaldehyde resin is mixed with molecular weight fractionated lignin derivatives for use as a binder in the production of plywood, particle board and fibreboard and similar products, possibly with other substances such as fillers.

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Adhesives made from lignin derivatives and phenol-formaldehyde resins for the production of .auer, chipboard and fibreboard are known .mu. Danish Patent Publication 10098U, Finnish Patent Applications 965/69 and 1965/72, Canadian Patent Publication 735389, American Patent Publication Nos. 2786008 and 318565k, and the articles Thermosetting Adhesives from electrodialyzed lignosulfonates, Tapp 50 (1967) -Pressure Laminates, Tappi Μ »(1961), 823-830. Furthermore, weatherproof binders made of fractionated lignin derivatives and phenol-formaldehyde resin are known from the applicant's earlier Finnish patent publications 51105 and 519-6. According to the inventions disclosed in the latter publications, more than 50% of the lignin derivatives, lignosulfonates or time-11 lignins used for the preparation of the binder have a molecular weight of more than 5,000. Such binders made from fractionated lignin derivatives are likely to prove to be! -ri-r, y \ eesti significantly improved the weathering properties of binders previously made from lignin derivatives, while their strength properties fully correspond to the strength properties of commercial phenol-formaldehyde resin adhesives.

The binders shown above, which contain more than 5 * '· t of lignin derivatives and a molecular weight of more than 5,000, are prepared from molecular weight fractionated lignin derivatives obtained from cellulose cooking. Fractionation is usually carried out by ultrafiltration of the waste liquor from the broth by means of a semipermeable membrane. Other fractionation methods have been described e.g. in Finnish patent application 3626/72.

In an effort to develop the above-mentioned binders made from fractionated lignin derivatives suitable for large-scale industrial production, the fraction rich in high molecular weight lignin derivatives necessary for the production of the binder forms a relatively small part of the pulp dry matter. £ has a molecular weight of more than 5,000. If 50 ρ-ϊ of the lignin derivatives used to make the binder are to have a molecular weight of more than 5,000, only a small fraction of the original waste liquor dry matter will be used, which of course reduces the importance of the invention for total waste liquor and wood.

It is an object of the present invention to obviate the above drawbacks. The characteristic features of the invention are set out in the claims.

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The invention is based on the surprising fact found in recent studies that fractionated alkali lignins, of which up to only 35% by weight, preferably 1 * 0 pZ, have a molecular weight of more than 5,000, can be made into a high-strength, weatherproof binder for plywood, particle board and fiberboard. in the manufacture of similar products. In the preparation of the phenol-formaldehyde resin used in the binder, phenol and formaldehyde are preferably used in a molar ratio of 1: 1.8 to 1: 3.

Thanks to the invention, the lignin derivatives only need to be fractionated to such an extent that at least 35% by weight of the lignin derivatives have a molecular weight of more than 5,000. The preparation of the binder according to the invention is then considerably cheaper and cheaper than in Finnish patents 51105 and 519½. for the preparation of the binders according to the invention, in which the lignin derivatives used have had to be fractionated considerably further, so that more than 50 · ρ-% of said lignin derivatives have a molecular weight of more than 5,000.

The molecular weight distributions of lignosulfonates and alkali lignin can be determined by gel permeation chromatography as described, e.g., by Whitaker, J.R., Anal. Chem. 35. (1963): 12, 1950-1953, Forss., K.G. and Stenlund, B.C., Paper and Wood (1966): 9, 565-57li and 11, 673_676, and Forss, K.G., Stenlund, B.C. and Sägfors, P-E., Applied Polymer Symposium No. 28 (1976), 1185-119, John Wiley & Sons, Inc. In these methods, samples are eluted through a gel permeation chromatography column. Molecular weight distributions are determined from the correlation between molecular weights and corresponding retention volumes. This correlation can be set by determining the molecular weights of the different fractions using a light scattering method or using osmometry or ultracentrifugation techniques. However, these methods are very laborious and it is therefore more practical to calibrate the gel permeation chromatography column with readily available substances of known molecular weights. Such a substance is, for example, glucagon having a molecular weight of 31 * 83. Thus, the molecular weights of the lignin derivatives used in the binder according to the invention can also be compared with glucagon. According to this, more than 1 * 5 p-Z of the lignin derivatives used in the adhesive according to the invention have a higher molecular weight than glucagon.

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The lignin derivatives used in the preparation of the adhesive according to the invention may be from an alkaline cooking of the lignocellulosic raw material, e.g. from a soda process (cooking solution contains sodium hydroxide), sulphate process available alkali lignins.

The pH of the aqueous binder solution of the invention is 8 to 1U. When preparing the binder from acidic lignin derivatives, e.g. alkali or alkaline earth hydroxide α can be advantageously added to the binder to raise the pH to 8-1H. The lignin derivatives are preferably used in the form of alkali or alkaline earth metal salts, optionally containing an excess of the corresponding alkali. The alkalinity of the binder is also advantageous because the basic binder causes less corrosion than the acidic binder. In addition, when e.g. sodium hydroxide is added to the binder, the sodium hydroxide lowers the viscosity of the binder, which facilitates the preparation and further processing of the binder.

The fractionation of the lignin derivatives can be carried out by any fractionation method known per se, such as doping, extraction method or ultrafiltration. Such fractionation methods have been described e.g. in American patent publication 3825526 and in Finnish patent application 3626/72.

The invention will now be described in detail by way of example and with reference to the accompanying drawings, in which Figures 1 and 2 show the elution of reference substances through certain columns containing molecular weight distributions. , Figures 5a, 5b and 6 show the elution of some lignin derivatives through the columns containing the buffer solution used, and Figure 7 shows the cumulative molecular weight distributions of some of the lignin derivatives studied.

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The molecular weight distributions of alkali lignins and some lignosulfonates were determined in the working examples according to the following method:

Lignosulfonate and alkali lignin samples were analyzed by gel chromatography using "Sephadex" columns (length 150 cm, diameter 1 cm). Lignosulfonates were eluted through a column containing "Sephadex G-75" using "Tris" / HCl buffer (pH 8.0, 0.1 M) containing NaCl (0.5 M) as eluent, while alkali lignins dissolved in sodium hydroxide aqueous solution, eluted through a "Sephadex G-50" column with NaOH (0.5 M) as eluent. The elution rate was 20 ral / h.

The concentration of lignin in the eluent fractions was determined by absorbance measurements (280 nm). The retention volume was determined by weighing the eluent fractions.

To obtain results independent of gel filling density, a relative retention volume scale was introduced using two calibrators as internal standards. The retention volume peak given by Blue Dextran (M 2.10 ^) was taken as the first reference point on the retention volume scale, giving a value of 0. The second reference point, giving a value of 1, was obtained by determining the retention volume peak given by sulfosalicylic acid (M «218) (Figure 1" Sephadex G-75 "and Figure 2" Sephadex G-50 ").

Calibration of the columns was performed simultaneously by determining the ratio of the logarithm of the molecular weight to the relative retention volume for readily available substances of known molecular weight. The "Sephadex G-75" column was calibrated using egg albumin (M = U5,000), Chymotrypsinogen A (M = 25,000), Cytochrom C (M * 12,500) and glucagon (M «) as reference. 3 U83) and Tris / HCl buffer (pH 8.0, 0.1 M) containing NaCl (0.5 M) as eluent (Figures 1 and 3). The "Sephadex G-50" column was calibrated using "Cytochrom C", glucagon and "Bacitracin" (M 1 U23) as reference materials and NaOH (0.5 M) as eluent (Figures 2 and U). In this case, lignin derivatives (lower relative retention volume) eluting faster than glucagon through a gel permeation column consist of molecules with a molecular weight higher than 3 U83 (glucagon).

Example 1.

The sulphate waste liquor obtained from pine sulphate soup (Pinus Silvestris) was evaporated to a dry matter content of 33% · The pH of the solution was 12.7. Molecular weight distribution was determined using a "Sephadex G-50" column according to the method described above. The obtained 58788 έ chromatogram is shown in Figure 6 (A). The molecular weight distribution, Figure 7 (A), was calculated using the calibration curve shown in Figure k. According to this, 25.3% of the alkali lignins of the sulphate waste liquor had a molecular weight of more than 5,000 and 32.9 p- / S of more than 3 * + 83 (glucagon).

A 1: 2.5 molar ratio of phenol to formaldehyde was used in the preparation of the phenol-formaldehyde resin. The dry matter content of the resin was k6% and the pH was 11.1. The binder was prepared by mixing the prepared phenolic resin (1 + 50 g) with evaporated sulfate broth (1 x 18 g). The mixture was stirred for 10 min and then 132 g of a filler mixture consisting of wheat flour (13 g), quebrachö (32 g), chalk (61 g) and wood flour (26 g) was added. The viscosity of the binder was 2 k0 mPa.s and the pH was 12.1.

The binder was used to make 3-ply birch plywood boards. The application rate was 150 g / m, the pre-compression pressure 0.7 MPa and the pre-compression time 6 min. The sheets were hot pressed at 135 ° C, 1.7 MPa, the pressing times used were 2, 3 and 1+ min. The properties of the boards were determined dry and after cooking according to the Finnish plywood standard SFS 2U16. The properties of the plates are shown in Table 1, where each value is the average of 5 specimens.

Example 2.

The sulfate waste liquor used in Example 1 was ultrafiltered to give the alkali lignin product, the molecular weight distribution of which is shown in Figure 7, curve B (gel chromatogram in Figure 6, B). According to this, 30.9 p-β lignin derivatives had a molecular weight of more than 5,000 and U0.0 p-Jf had a molecular weight of more than 3 UÖ3 (glucagon). The binder was prepared as in Example 1, using the same phenolic resin. The viscosity after the addition of filler was 320 mPa.s.

Using a binder, 3-ply plywood sheets were prepared under the same conditions as in Example 1. The properties of the boards are shown in Table 1.

Example 3 ·

The alkali lignin product was isolated from a sulphate waste liquor by ultrafiltration. Its molecular weight distribution was determined by gel permeation chromatography, the chromatogram is shown in Figure 6, C and the molecular weight distribution in Figure 7, C. Accordingly, 36.0% of sulfate tilignins had a molecular weight above 5,000 and 1 + 6.5 wt% a molecular weight above 3 1 * 83 (glucagon). The binder was prepared as in Example 1. The viscosity of the binder was 58 ± 28888 τ and the pH was 12.0.

Using a binder, 3 ′ ′ ply birch plywood boards were prepared as in Example 1, the properties of the boards are shown in Table 1.

Example k, by alkaline filtration, an alkali lignin fraction was prepared, the gel chromatogram of which is shown in Figure 6, D and the molecular weight distribution in Figure 7, D. According to this, U3 »2 p- / 5 of alkali lignins had a molecular weight of more than 5,000 and 5 ^ * 1 P ~ f more than 3 1 + 83 (glucagon).

The binder was prepared as in Example 1, had a viscosity of 1 + 70 mPa.s and a pH of 12.0.

Using a binder, 3-ply birch plywood boards were prepared as in Example 1. The properties of the boards are shown in Table 1.

Example 5 ·

The sulfate waste liquor used in Example 1 was ultrafiltered to give an alkali lignin fraction, the gel chromatogram of which is shown in Figure 6, E. Its molecular weight distribution is shown in Figure 7, E. According to this, 1 + 6.9 w / w of lignin derivatives had a molecular weight of more than 5,000 and 57 * 7 P ~% over 3 1 + 83 glucagon).

♦ .... ..... .

The alkali lignin fraction was used to prepare the binder according to Example 1.

The viscosity after filler addition was 560 mPa.s and the pH was 11.9 ·

Using a binder, 3 ** ply plywood boards were prepared as in Example 1. The properties of the boards are shown in Table 1.

Example 6.

A high molecular weight alkali lignin fraction was isolated from the sulphate waste liquor used in Example 1 by ultrafiltration, the gel chromatogram of which is shown in Figure 6, F and the molecular weight distribution in Figure 7 »F, according to which 53.1 + P ~% of alkali lignins had a molecular weight above 5,000 and 61 + .7% 3 1 + 83 (glucagon).

k 58788 β

The binder was prepared as in Example 1. It had a viscosity of 680 mPa.s at 25 ° C and a pH of 11.8.

The binder was used to make 3-ply birch plywood boards using the same conditions as in Example 1. The properties of the boards are shown in Table 1.

Table 1. Comparison of sizing properties of sulphate waste liquor and different alkali lignin fractions

Example Pressing time Dry After cooking ___ _ · shear strength puustamurt. leikk.luj. puustamurt.

n: ° _min R / mm2% _N / mm2% 1 2 1.80 57 0.55 8

3 1.81 * 70 0.63 1U

1 * 1.98 73 0.71 12 2 2 2.00 63 1.37 38 3 2.10 80 1.38 39 1 »2.08 90 1.50 82 3 2 2.20 88 1.1 * 3 71 3 2.1 * 2 93 1.55 89 1 * 2.39 98 1.71 91 * 1 * 2 2.35 90 1.1 * 9 88 3 2.1 * 0 92 1.68 97 1 * 2 , 1 * 2 92 1.65 98 5 2 2.1 * 6 98 1.58 90 3 2.55 96 1.63 93 1 * 2.1 * 3 99 1.70 96 6 2 2.57 100 1, 65 99 3 2.60 100 1.76 100 1 * 2.58 98 1.72 92

According to the Finnish plywood standard SFS 21 * 15, the dry shear strength o o must be at least 2.10 N / mm, after cooking at least 1.1 * 0 N / mm and if the values remain lower, the wood edge fracture must be at least 50%. In practice, however, significantly higher wood fractures are required, i.e. more than 80% even after cooking.

Examining the properties of the plates shown in Table 1, it is stated that the requirements were met for Examples 3-6 with compression times of 2 and 3 min. The binder of Example 2 required a longer compression time to meet the requirements. J

S-9 58788 pages. In the case of Example 1, the extension of the pressing time no longer helps, the adhesive joint does not harden to be water-resistant.

Example 7.

Sulfate lignin was used as the binder raw material, in which the weight fraction of the high molecular weight (Mv> 5,000) was 40 p-JJ of all lignin derivatives and 50 p-J had a higher molecular weight than glucagon.

As the phenol-formaldehyde resin, a product prepared from phenol and formaldehyde in a molar ratio of 1: 2.5 and containing 2.1 .mu.l of free formaldehyde was used. To the solution was added 3 .mu.l of urea / resin dry matter. The mixture was warmed to 30 ° C and stirred for 3 hours. The formaldehyde content then decreased to 0.4%.

The treated 46% phenol-formaldehyde resin (520 g) was mixed with a sulfate lignin solution (340 g) having a dry matter content of 30%. The pH of the adhesive was 11.8 and the viscosity was 160 mPa.s. Then 140 g of a filler mixture containing 14 g of wheat flour, 58 g of chebracho 35 and 35 g of wood flour were added, the viscosity of which was 3040 mPa.s. after 30 min of mixing.

The adhesive mixture was used to make 3-ply birch plywood boards. The application rate was o 150 g / m, the pre-compression time was 6 min and the pressure was 0.8 MPa. The plates were hot pressed at 135 ° C, 1.8 MPa. Compression times were 2, 2 1/2, 3 and 4 min. The properties of the plates were determined dry and after cooking. In the table below (Table 2), each value is the average of 5 plates, i.e., 25 specimens.

Table 2. Properties of 3-ply birch plywood boards

Pressing time dry after cooking (min) N / mm2% N / mm2% 2 3.31 93 1.58 81 2 1/2 2.95 100 1.62 92 3 3.06 98 1.88 94 4 3.21 97 1.66 91

Also with shorter than normal compression runs (2 and 2 1/2 min) good results were obtained with this binder.

Example 8.

Alkali lignin was used to prepare the binder, with the high molecular weight fraction (Mw> 5,000) accounting for U8% of all lignin derivatives and 59 P “Ä based on higher molecular weight glucagon.

The phenol-formaldehyde resin was prepared in a molar ratio of 1: 2.2 and contained free formaldehyde. 1.7% urea / resin dry matter was added to the resin. The mixture was stirred at room temperature for 5 hours. Thereafter, the amount of free formaldehyde had decreased to 0.08%. The resin-urea mixture was added to an alkali lignin solution with a dry matter content of k2% (h32 g 51% resin / 52U g lignin solution). UU g of 50% sodium hydroxide solution was added. The mixture was stirred for 30 min, the pH was 11.8. The viscosity at 25 ° C was 320 mPa.s.

Particleboards were made using the prepared binder. An additional 10% paraffin emulsion, calculated as dry matter / adhesive-dry matter, was then added.

15, 20 and 30 mm thick particleboards with a nominal bulk density of 750 g / m 2 were prepared using the binder. The amount of binder injected into the chips was 10 p-J based on dry matter. Combined contact and large cycle heating was used to hot press the chipboard. The temperatures of the squeegee plates were 180 ° C and the compression pressure was 2.65 N / mm. The pressing times and plate properties are shown in the following table.

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Table 3 · Particleboard properties using combined contact and large cycle heating.

Plate wear time bending strength tensile strength thick peat V 100 thickness 2 h 2k h mm min s / mm N / mm ^ N / mm ^%% N / mm ^ 15 U 1/2 18 19.8 0.1 * 7 2.3 .11.5 0.21 20 5 15 19.2 0.52 1.8 10.8 0.19 30 5 1/2 11 19.2 0, U9 2.2 11.1 0.23 DIN 68761> 17.7> 0.3¾ < 6.0 <12.0> 0.15 requirement 11,58788

The boards fully met the requirements of the German standard DIN 68761 for phenol-glued chipboard. The plates were completely formaldehyde-free after hot pressing.

Example 9.

A phenol-formaldehyde resin having a phenol: formaldehyde molar ratio of 1: 3 was prepared for the binder. After preparation, it contained 1 *, 8% free formaldehyde. 10% urea was added to the resin and the mixture was stirred at 25 ° C for about 1 * hour. The mixture was then allowed to stand for another day, after which free folmaldehyde was determined. This had fallen to 0.1%. .

The alkali lignin fraction, the properties of which are shown in Example 9, was used to prepare the binder. To a 61 * 0 g alkali lignin solution, dry matter content 1 * 2%, 360 g of the above-mentioned phenol-formaldehyde-urea resin having a dry matter content of 50% was added. The ratio of lignin to phenol-formaldehyde resin was 60: U0. The pH of the binder was 11.0.

The binder was used to make formaldehyde-free particle boards.

The amount of binder was 8% by dry weight based on the weight of the dry average chips and 10% by weight of the surface chips. In addition, 50% paraffin emulsion 1% dry matter by weight of dry chips was sprayed onto the chips. Using a binder, 15 mm 3-layer chipboards with a bulk density of 750 kg / m 3 were prepared. The press plates had a temperature of 215 ° C, a compression pressure of 2.9 ** MPa and a compression time of 20 s / mm. After hot pressing, the sheets were post-cured at 180 ° C.

The properties of the plates are shown in Table U.

Table U. Properties of particle boards using post-curing.

Plate thickness bulk weight bend strength tensile strength thick peat V 100 No. mm kg / m ^ N / mm ^ N / mm ^ jj ** ^ ** N / mm ^ 1 15.08-760 20.6 0.1 * 7 2, U 9.8 0, 18 2 15.10 758 20.3 0.1 * 6 2.5 10.2, 0.19 3 15.08 756 20.5 0.55 1.9 10.5 0.21 1 * 15.09 762 20.9 0.51 * 2.8 11.0 0.20 5-15.10 755_12aJ * _0.1 * 6 2.5 10.8 0.15 58788 12

The boards met the requirements of DIN 68761. The odor of formaldehyde was not felt during manufacture and no formaldehyde was released from the plates afterwards.

The viscosity values mentioned in the working examples have been measured with a Brookfield viscometer, 25 ° C, 50 rpm.

The invention is, of course, not limited to the embodiments shown, but its applications may vary within the scope of the appended claims. In this case, the dry weight ratio of the lignin derivatives contained in the binder to the phenol formaldehyde resin can vary, for example, between 90:10 and 20:10. Furthermore, the molar ratio of phenol to formaldehyde in the phenolic resin can vary, for example, between 1: 1, U - 3.

v *.

Claims (6)

13 58788 A binder for the manufacture of plywood, particle board, fibreboard and similar products, which binder consists of phenol-formaldehyde resin and molecular weight fractionated lignin derivatives, characterized in that at least 35% by weight of the lignin derivatives used have a molecular weight of more than 5,000 and less than 50% by weight. - The 1 igni ini derivatives used have a molecular weight of more than 5,000, and that the 1 igni ini derivatives used are early 1 Htjni in. Binder according to Claim 1, characterized in that the pH of the binder is 8 to IA. Binder according to Claim 1 or 2, characterized in that more than AO w / w% of the lignin derivatives used have a molecular weight of more than 5 000. A. Binder according to one of Claims 1 to 3, characterized in that more than A5 wt% of the lignin used derivatives of its own glucagon higher mo-1ekyy1i pa Inon. Binder according to one of Claims 1 to A, characterized in that the 1-derivative derivatives used are in the form of a basic alkali salt. A process for preparing a binder according to any one of claims 1 to 5, wherein the phenol-formaldehyde resin is mixed with molecular weight fractionated lignin derivatives for use as an adhesive in the manufacture of plywood, particle board and fibreboard and the like in aqueous form, optionally with fillers. 35% by weight of the lignin derivatives used have a molecular weight of more than 5,000 and less than 50% by weight of the lignin derivatives used have a molecular weight of more than 5,000, that the pH of the binder is adjusted to 8-1A, preferably 9-13, that the lignin derivatives used are the formaldehyde resin is prepared from phenol and formaldehyde in a molar ratio of 1: 1.4 to 1: 3, preferably 1: 1.8 to 1: 3. ¥