JPS61166875A - Adhesive - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an adhesive for manufacturing plywood, chipboard, fiberboard and other similar wood products, consisting of a lignin derivative fractionated by molecular weight and a phenol formaldehyde resin.

Adhesives consisting of lignin derivatives and phenol formaldehyde resins and used in the production of plywood, chipboard and fibreboard are described, for example, in Danish Patent No. 10.
0984, Finnish Patent Application No. 965/69, Finnish Patent Application No. 1965/72, Canadian Patent Application No. 735389
No. 2,786,008, U.S. Pat. No. 3,185,654
No., TAPPI No. 50 @ No. 92-94 published in 1967
The paper published on page [Thermosetting Atheroscium from Electrodialyzed Lignosulfonate] and TAPPI Vol. 44, No. 823, published in 1961.
It is known from the article "Reactive Lignin-Private Products in Phenolinox Hypressosure Laminates" published on pages 830-830. Weather-resistant adhesives made from fractionated lignin derivatives and phenol formaldehyde resins are also known from the applicant's previous Finnish patents 51105 and 51946. Among the lignin derivatives, lignosulfonate or alkali lignin used in the production of adhesives according to Kyoshu in both of the above-mentioned patents has an amount of more than 50%, respectively.
It has a molecular weight greater than 0. Such adhesives prepared from fractionated lignin derivatives have shown to be significantly superior to all previous adhesives made from lignin derivatives, especially in terms of weather resistance, but the strength properties are superior to that of commercially available phenol-formaldehyde adhesives. The strength was exactly the same as that of .

The aforementioned adhesives having a molecular weight greater than 50% of the lignin derivative or greater than 5000 are produced from lignin derivatives that have been digested from cellulose and fractionated according to molecular weight. Fractionation is usually carried out by ultrafiltration of the waste liquid from the cooking stage using a semi-permeable membrane. Another separation method is that described in Finnish patent application no. 3626/72.

In an attempt to develop the aforementioned adhesives produced from lignin derivatives into ones suitable for use in industrial large-scale production, the parts containing large amounts of polymeric lignin derivatives, which are essential for the production of adhesives, were subjected to cellulose vapor deposition. It constitutes a relatively small portion of the dry matter in the liquid obtained from the stage. This is because, for example, only about 25-30% of the alkaline lignin obtained from the sulfate cooking stage has a molecular weight greater than 5000. If the aim is for more than 50% by weight of the lignin derivatives used in adhesive production to have a molecular weight of more than 5000, only a small portion of the initially dry substance of the waste liquid will be used. ,
This naturally reduces the importance of the invention in terms of full utilization of wood and waste liquid.

The adhesive of the present invention is manufactured by mixing the fractionated lignin derivative and phenol formaldehyde resin. Phenol-formaldehyde resins are commonly made from phenol and formaldehyde. The use of large amounts of formaldehyde promotes the formation of methylol groups in the phenol formaldehyde resin. The abundance of methylol groups in phenol formaldehyde resins is advantageous for adhesives made from fractionated lignin derivatives, as these appear to be the specific groups that react with lignin derivatives. However, if a large amount of formaldehyde is used in the production of phenol-formaldehyde resin, the resulting phenol-formaldehyde resin will contain a large amount of free formaldehyde, which poses a great danger to safety during work due to the volatility and toxicity of formaldehyde. It should be noted that

Therefore, the use of such phenol formaldehydes containing free formaldehyde as adhesive components is less recommended and is prohibited in some countries.

The object of the present invention is to eliminate such drawbacks.

The adhesive of the present invention is composed of lignin derivatives and phenol formaldehyde resins separated by molecular weight. 35% by weight or more 50% by weight 1%
The lignin derivative used has a molecular weight of less than or greater than 5000 and is an alkaline lignin.

In addition, the adhesive of the present invention is used as an adhesive in the production of plywood, chipboard, fiberboard, and similar wood products, so it also contains a lignin derivative separated by molecular weight, a phenol formaldehyde resin, and, in some cases, a filler. in an aqueous solution, wherein at least 35% by weight of the lignin derivative mixed with the phenol-formaldehyde resin has a molecular weight greater than 5000, and 50% by weight of the lignin derivative used If the lignin derivative used is alkaline lignin and has a larger molecular weight, the lignin derivative to be mixed is
+ is adjusted to be in the range of 8 to 11, and the phenol formaldehyde resin is preferably 1:1.4 to 1:3.
:t, a to l: Produced from phenol and formaldehyde in a molar ratio of 3.

The present invention has shown that during recent research, fractionated lignin derivatives having a molecular weight greater than 5000 in amounts as low as 35% by weight, preferably as much as 49% by weight, are useful for the production of plywood, chipboard, fiberboard and similar materials. The invention is based on the completely unexpected discovery that it is possible to produce weather-resistant adhesives with increased strength. In producing phenol-formaldehyde resin used in adhesives, phenol and formaldehyde are mixed in an i:1 ratio. A molar ratio of s to l:3 is advantageously used.

According to the invention, it is only necessary to carry out the fractionation until at least 35% and preferably 40% by weight of the lignin derivative has a molecular weight greater than 5000. Therefore, the production of the adhesive according to the present invention is disclosed in Finnish Patent No. 5
It is significantly more efficient and less expensive than the adhesives described in No. 1105 and No. 51946.

In the case of the adhesives of both patents, it was necessary to significantly advance the fractionation of lignin derivatives for use in adhesives, so that more than 50% by weight of the lignin derivatives had molecular weights greater than 5000. Because of its importance, the production of the adhesive of the present invention is significantly superior in terms of simplicity and lower cost than adhesives of the same type previously known.

The molecular weight distribution of lignosulfonate and alkali lignin can be measured by gel chromatography. This method is described, for example, in Anal, published in 1963, Ch.
J.R. Hoysoteken's paper published in Em, Vol. 35, No. 12, pp. 1950-1953, 196
Articles by K. G. Forss and B. G. Stenlund published in Paperi ja Puu Vol. 48, No. 9, pp. 565-574 and No. 11, pp. 673-676, published in 1976, and John Wiley End, 1976. .

Song Incobole Tenodo Published by AppliedP
olymer Symposium No. 28 No. 1185
It is described in the paper by K. G. Forss, B. G. Stenlund, and B. E. Sarkfors published on pages 1194-1194. In the methods of these papers, the sample is loaded into a gel chromatography column and eluted. Molecular weight distribution is determined based on the correlation between molecular weight and corresponding retention volume. This correlation can be established by measuring the molecular weight of the various moieties by light scattering, osmotic pressure application techniques or ultracentrifugation techniques.

However, these methods are extremely laborious and from a practical point of view it is convenient to calibrate gel chromatography columns using readily available substances of known molecular weight.

Such a substance is, for example, glucagon with a molecular weight of 3483. Thus, the molecular weight of the lignin derivative used in the adhesive of the invention can also be compared to glucagon. In such a relationship, at least 40% by weight, preferably at least 45% by weight of the lignin derivative used for the adhesive of the invention has a molecular weight greater than that of glucagon.

The pH of the aqueous solution of the adhesive of the invention is 8-14.

When adhesives are prepared from lignin derivatives, such as fractionated or gutsulfonates obtained from waste liquors after cooking by the sulfite process, additives such as alkali metal hydroxides or alkaline earth metal hydroxides are added to the adhesive. Add to pH
It is advantageous to increase the value in the range from 8 to 14. The lignin derivatives are best used in the form of alkali metal or alkaline earth metal salts, each of which can also contain an excess of alkali. The alkalinity of the adhesive is also advantageous as alkaline adhesives are less corrosive than acidic adhesives.

Furthermore, when sodium hydroxide is added to the adhesive, for example, the sodium hydroxide reduces the viscosity of the adhesive and facilitates its subsequent conditioning and handling.

In one advantageous embodiment of the invention, the adhesive is present at a concentration of 1 to 1% by weight of dry matter in the phenol formaldehyde resin.
It contains urea in an amount of 5% by weight, preferably 5-10% by weight. When urea is mixed with the phenol formaldehyde resin, the urea reacts with the excess formaldehyde and thus combines with the excess formaldehyde present in the mixture. The use of urea in adhesives thus increases operational safety and
Excess formaldehyde makes it possible to enhance the strength properties of adhesives used in connection with the production of phenol formaldehyde resins. Urea together with formaldehyde forms a permanent polymer and increases the strength of the adhesive in this manner as well.

Urea can also be used successfully in adhesives based on phenol formaldehyde in which more than 50% of alkaline lignin or lignosulfonates are constituents of lignin derivatives with molecular weights greater than 5000.

As the lignin derivative used in the production of the adhesive of the present invention, for example, lignosulfonate obtained from sulfite cooking of a crude raw material containing lignocellulose (the cooking liquor contains bisulfite and sulfur dioxide) can be used. can. Also,
For the production of adhesives, crude raw materials containing lignocellulose are subjected to alkaline relysis, such as alkaline lignin obtained from the soda process (the cooking liquor contains sodium hydroxide), sulfate process (the cooking liquor contains sodium hydroxide, sodium sulfide and Alkaline lignin obtained from the oxygen-alkali metal process (in which cooking is carried out using sodium hydroxide in the presence of oxygen) can be used.

Fractionation of lignin derivatives can be carried out by any conventionally known fractionation method, such as sedimentation, extraction, or ultracentrifugation. Such separation methods are described, for example, in US Pat. No. 3,825,526 and Finnish Patent Application No. 36.
It is described in No. 26/72.

The invention will now be explained in more detail with reference to the figures and examples.

The molecular weight distribution of alkaline lignin and guts sulfonate was measured by the following method in the examples.

A sample of lignosulfonate alkaline lignin was analyzed by gel chromatography using a Sephadex column with a length of 150 cm and a diameter of 1 cm.

Lignosulfonate contains Sephadex G-75.
It was eluted in a 1 volume column using a 0.1M Tris/HCI buffer solution at pH 8.0 containing 0.5M NaCl as eluent. On the other hand, alkaline lignin was dissolved in an aqueous solution of sodium hydroxide, which was eluted in a Sephadex G-50 column using 0.5M Na011 as an eluent. The elution rate was 20 ml/hour.

The lignin concentration in the eluate portion was determined by absorption measurement method (280 nm
). Retention volume was determined by weighing the eluate portion.

To obtain results independent of gel packing density, two calibrators were used as internal standards and a relative retention volume scale was introduced. The retention peak generated by blue dextran (M = 2 x 10b) was taken as the first reference point, the value at this point was set to 0, and the retention peak obtained using sulfosalicylic acid (M = 218) was measured. The value of the second reference point was set to 1 (see Sephadex G-75 in FIG. 1 and Sephadex G-50 in FIG. 2).

Each column was calibrated by simultaneously measuring the logarithmic ratio of the amount and relative retention volume of a readily available material of known molecular weight. The Sephadex G-75 column contains ovalbumin (M = 45,000), chymotrypsinogen A (M = 25,000), cytochrome C (M =
12500) was used as a control, 0.5M Na
0.1 M Tris/II with po 8.0 containing C1
Calibration was done by using cI buffer solution as eluent (see Figures 1 and 3). Sephadex G-50 column contains cytochrome C, glucagon and bacitracin (M
= 1423) was used as a control substance, 0.5M
-Calibrated by using NaOH as eluent (
Figures 2 and 4).

In these cases, the lignin derivatives (those with lower relative retention volumes) that are eluted earlier than glucagon by the gel chromatography column consist of molecules with a molecular weight greater than the molecular weight of glucagon, 3483.

Pine (Pinus 5ilvestris) by the snoring sulphate method
) was thickened to a dry matter content of 33%. The ρ■ of the solution was 12.7. The molecular weight distribution was measured by the method described above using a Cefazo, Kusu G-50 column. The resulting claw 71-crumb is shown in FIG. The molecular weight distribution calculated using the calibration club shown in FIG. 4 is shown as 82 in FIG. Therefore, 25.3% by weight of alkaline lignin in the sulfate process wastewater is 50% by weight.
00, and 32.9% by weight had a molecular weight higher than the glucagon molecule 13483.

In manufacturing phenol formaldehyde resin,
The molar ratio of phenol to formaldehyde was 1:2.5. The phenol formaldehyde resin had a dry matter content of 146.3% and a pH of 11.1.

450 g of the phenol-formaldehyde resin thus prepared were mixed with 418 g of the thickened sulfate process effluent, the mixture was stirred for 10 minutes, and then 132 g of a mixed filler consisting of 13 g of wheat flour, 32 g of keflacho, 161 g of white and 26 g of wood flour was added. An adhesive was prepared by adding .

The adhesive had a viscosity of 240 mPa,s and a pH of 12.1.

This adhesive was used to make a 3-ply birch veneer board.

Coating amount is 150 g/cm2, Y decoration pressure is 0.7M
Add Pa for 6 minutes. The three signboards were heated to 135°C'iJ.
High temperature pressure was applied at a pressure of 7 MPa for 2 minutes, 3 minutes, or 4 minutes. The properties of the veneers were tested in accordance with the Finnish Plywood Standard 5FS2416, both dry and after boiling. The results are shown in Table 1 below. Each number in the table is an average value of 5 samples.

The sulfate process waste liquid from Snoring Example 1 was ultrafiltered to obtain an Alka IJ lignin product. The molecular weight distribution of this product is curve B in Figure 7.
2 (gel chromatogram B1 in FIG. 6). Therefore, 30.9% by weight of lignin derivative has a molecular weight of 5000
40.0% by weight of the lignin derivative had a molecular weight greater than the glucagon molecule 13483.

An adhesive was produced in the same manner as in Example 1 using the same phenolic resin as in Example 1. The viscosity after adding filler is 320mPa,
It was s.

Using this adhesive, a 3-ply plywood board was manufactured under the same conditions as in Example 1. The properties of the plywood are shown in Table 1.

(1) Alt alkaline lignin products were obtained by ultrafiltration of the main sulfate process waste liquid. The molecular weight distribution of this product was measured by gel chromatography, and the chromatogram is shown in curve C1 in FIG. 6, and the molecular weight distribution is shown in curve C2 in FIG. Therefore, 36.0% by weight sulfate lignin has a molecular weight of 50
00 and 46.5% by weight has a molecular weight higher than the glucagon molecule ffl'3483. An adhesive was prepared analogously to Example I. Adhesive is 420mPa
, s, and pu was 12.0.

Using this adhesive, a 3-ply birch plywood board was manufactured in the same manner as in Example]. The properties of the plywood are shown in Table 1.

Example 4 An alkaline lignin fraction was produced by ultrafiltration. The gel chromatogram of this product is shown in curve D1 in Figure 6,
The molecular weight distribution is shown at curve 2 in FIG.

Therefore, 43.2% by weight of alkaline lignin is 5000%
It had a higher molecular weight, with 54.1% by weight having a molecular weight greater than the molecular weight of glucagon, 3483.

An adhesive was produced in the same manner as in Example 1. Viscosity is 470mP
pH was 12.0 in a, s.

A 3-ply birch veneer board was manufactured as in Example 1 using this adhesive. The properties of the plywood are shown in Table 1.

The sulfate process waste liquid similar to that used in Example 5 was ultrafiltered to obtain an alkaline lignin fraction. The gel chromatogram of this product was as shown in curve E in FIG. 6, and the molecular weight distribution was as shown in curve 'itM E Z in FIG. Therefore, 46.9% by weight of the lignin derivative is soo.

It had a larger molecular weight, 57.7@wt% had a larger molecular weight than the glucagon molecule 1i3483.

An adhesive was produced in the same manner as in Example 1 using this alkaline lignin fraction. Viscosity after adding filler is 560mPa
, s and the pH was 11.9.

A 3-ply plywood board was manufactured in the same manner as in Example 1 using this adhesive. The properties of the plywood are shown in Table 1.

Example - Color The same sulfate process waste liquid used in Example 1 was subjected to ultrafiltration to obtain a high molecular weight alkali lignin fraction.

The gel chromatogram of this product is shown by curve F1 in FIG. 6, and the molecular weight distribution is shown by curve F2 in FIG. According to this, 53.4% by weight of the alkaline lignin had a molecular weight greater than 5000, and 64.7% by weight had a molecular weight greater than 3483 (glucagon). An adhesive was produced in the same manner as in Example 1. Viscosity is 680mPa,s at 25℃
, pH was 11.8.

Using this adhesive, a 3-ply birch veneer board was manufactured under the same conditions as in Example 1. The properties of the plywood are shown in Table 1.

Table 1 Comparison of adhesive properties of sulfate process waste liquid and various alkaline lignin fractions As specified in the Finnish National Plywood Standard 5FS2415, the shear strength in the dry state is 2. ION/llll1
"It should not be less than 1.4 ON/as after boiling"
If the shear strength value falls below this standard, the fracture in the wood must not be less than 50%. However, in reality, an extremely high degree of wood breakage is required;
In other words, 80% or more is still required after boiling.As is clear from the examination of the characteristics of the plywood boards shown in Table 1, in the tests of Examples 3 to 6, the required conditions were already met with a pressurization time of 2 minutes and 3 minutes. has been achieved. The adhesive of Example 2 required prolonged pressure to pass specifications. In the test of Example 1, long pressurization times were not available. The joints bonded with adhesive could not be cured and did not become water resistant.

Sodium lignosulfonate was used in the production of snore adhesive. The weight proportion of high molecular weight sodium ligutsulfonate with molecules l M >5000 was 72%, and 61% by weight had a molecular weight larger than that of glucagon, which had a molecular weight of 3843. 50% of these sulfonates
The aqueous solution has a viscosity of 80.000 mPa, s or more,
The ρ■ of the 10% aqueous solution was 6.4.

The phenol formaldehyde resin used to make this adhesive was made from a 1:3 molar ratio of phenol and formaldehyde, and the resin contained 3.4% free formaldehyde. To remove free formaldehyde, 8% urea per weight of phenol formaldehyde resin dry matter was added to the phenolic resin. The mixture was stirred for 2 hours. Free formaldehyde was measured again 24 hours later. The formaldehyde content this time was 0.1%. Phenol formaldehyde resin thus treated (dry matter content 48% by weight) 41
7 g were added to 417 g of the previously described aqueous solution of sodium gutsulfonate with a dry matter content of 32% by weight. Stir the mixture for 10 minutes until the dry matter content is 50% by weight.
26 g of sodium hydroxide solution were added. Thereafter, 140 g of a mixed filler containing 40% by weight of wheat flour, 24% by weight of Quebracho, 20% by weight of wood flour, and 46% by weight of flour was added. The viscosity of the adhesive after mixing was 800 mPa, s, and the pH was 9.3.

Using this adhesive, a 15-brie mixed wood veneer board was manufactured. Adhesive application amount is 150g/m2, open time is 45
minutes, pre-pressurization time was 6 minutes, and pre-pressurization pressure was 0.7 MPa. The plate was hot pressed at a pressure of 1.37 MPa for 18 minutes at a temperature of 130°C. The properties of the veneer board, measured according to the Finnish National Plywood Standard 5FS2416 in the dry state and after soaking, are shown in Table 2 below. However, the unit of shear strength in the table is N1w'', and the unit of wood breakage is %.One piece of data is the average value of five samples.

According to the Finnish National Standard 5FS2415, the shear strength in the dry state must be at least 2.1 ON/++n'', after boiling it must be at least 1,4 ON/+n2, and after soaking it must be at least 1,6 ON/ w 2 or more, and if the shear strength value does not reach the above specification value, the fracture in the wood must be at least 50% or more, but these veneers fully meet this requirement. Ta.

As a crude raw material for charcoal adhesive, the proportion of large molecular weight components with nw >5000 accounts for 40% by weight of the total lignin derivatives, and
A sulfate-method lignin having a molecular weight larger in weight percent than glucagon was used.

As phenol formaldehyde resin, molar ratio 1:2
．． 2. Produced from phenol and formaldehyde of 5.
One containing 1% by weight of free formaldehyde was used. 3% by weight of urea per resin dry matter was added to the resin solution. The mixture was heated to 30°C and stirred for 3 hours. The formaldehyde content was then reduced to 6.4%.

This treated 46% phenol formaldehyde resin 5
20 g were mixed with 340 g of a sulphate lignin solution with a dry matter content of 30%. This adhesive has a viscosity of 160mP
a, s, pH 11.8. Next, flour 1
4g, white! 56g, Quebrachi=F35g and wood flour 35g
140 g of mixed filler containing g were added. The viscosity after 30 minutes of mixing was 640 mPa.s.

A 3-ply birch hennya board was manufactured using the mixed adhesive. The coating amount was 150 g/m2, the pre-pressing time was 6 minutes, and the pre-pressing pressure was 0.8 MPa. 1 at 135℃
．． High temperature pressurization was performed at a pressure of 8 MPa. Pressure time is 2 minutes, 2
．． 5 minutes, 3 minutes, and 4 minutes. The properties of the plywood were measured in the dry state and after boiling. Each data in Table 3 is an average value from 5 veneers or 25 samples.

Table 1 Temporary characteristics of 3-ply birch hennya Even when the pressurization time is shorter than normal (2 minutes and 2.5 minutes),
Good results were obtained using this adhesive.

Example” - for the production of adhesives, large molecular weight (Ml, I > 5000)
The proportion of lignin derivatives accounts for 48% by weight of the total lignin derivatives,
Alkaline lignin, 59% by weight of which has a higher molecular weight than glucagon, was used.

A phenol-formaldehyde resin containing 1.7% by weight of free formaldehyde was produced using phenol and formaldehyde in a molar ratio of 1:2.2. To this was added 5% by weight of urea based on resin dry matter. The mixture was stirred at room temperature for 5 hours. As a result, the content of free formaldehyde was reduced to 0.08% by weight. A mixture of resin and urea was added to the alkaline lignin solution in an amount of 42% by weight on a dry basis (51% for 524 g of alkaline lignin solution).
% resin 432g).

To this was added 44 g of 50% sodium hydroxide solution.

The mixture was stirred for 30 minutes. pH was 11.8.

The viscosity was 320 mPa,s at 25°C.

Chip boats were made using the adhesive prepared in the above manner. To this was then added a paraffin emulsion of 10% based on the dry substance weight of the adhesive.

Using this adhesive, the thickness of the nominal type 1750g/m3 was 15.
Chip boats of ゜20 and 30 Tsuru were manufactured. The amount of adhesive sprayed onto the thousand knobs was 10% by weight on dry matter. A combination of contact high-frequency heating was used to press the chipboard at high temperatures. The pressure plate temperature was 180°C, and the pressure was 2.65N/+n2. The pressurization time and characteristics of the chipboard are shown in Table 4 below.

These chipboards fully complied with the requirements specified in the former German National Standard N68761 for phenolic bonded chipboards. These chip boats' had no free formaldehyde after high temperature pressurization.

To prepare an anti-adhesive agent, a phenol-formaldehyde resin was prepared using a molar ratio of phenol to formaldehyde of 1:3. The as-produced resin contained 4.8% free formaldehyde by weight. 10% by weight urea was added to the resin and the mixture was stirred at 25° C. for about 4 hours. Next, this mixture was allowed to stand for 24 hours, and the amount of free formaldehyde was measured, and it was found to have decreased to 0.1% by weight.

An alkaline lignin fraction having the properties described in Example 9,
Used in the production of adhesives. To 640 g of alkaline lignin solution with a dry matter content of 42% by weight, dry matter '! Contains 15
360 g of the previously described phenol formaldehyde-urea resin at 0% by weight were added. The ratio of lignin to phenol formaldehyde resin was 60:40. The pl+ of the adhesive was 11.0.

Using this adhesive, a chipboard containing no free formaldehyde was manufactured as follows.

The amount of adhesive was 8% dry matter based on the dry weight of the center chip and 10% of the surface chip weight.

The chips were further sprayed with a paraffin emulsion in an amount of 1% dry matter based on the weight of the dry chips.

Using this adhesive, a 3-ply chipboard made of 15 silk thick and having a volumetric weight of 1750 kg/m3 was manufactured. The pressure plate temperature was 215° C., the pressure was 2.96 MPa, and the pressure time was 20 S/lI+1. After hot pressing, the chipboard was post-cured at 180°C.

The characteristics of the chipboard are shown in Table 5 below.

The chipboard met the DIN68761 standard. No formaldehyde odor was observed during manufacturing, and no formaldehyde was released from the chipboard after manufacturing.

The viscosities listed on each side above were measured using a Brookfield viscometer at 25° C. and 5 Orpm.

It will be understood that the invention is not limited to the examples described above, and that various changes and modifications can be made without departing from the broader spirit and scope of the invention.

The dry weight ratio of the lignin derivative and phenol formaldehyde resin contained in the adhesive is, for example, 90:
10-20: Can be changed within the range of 10. Further, the ratio of phenol to formaldehyde in the phenol resin can be varied, for example, within the range of 1:1.4 to 123. Furthermore, the produced adhesive may contain fillers known per se, such as white paper, wood flour, quebracho, etc.
Flour, etc. can be added.

Furthermore, it is also possible to add urea to an adhesive having a different type of molecular weight distribution than the one according to the invention to bind the amount of formaldehyde contained therein. for example,
Urea can be added to adhesives using more than 50% by weight of lignin derivatives having a molecular weight higher than 5000, or less than 50% by weight of lignin derivatives used having a molecular weight higher than 5000. Urea can be added to the adhesive using those with.

Next, the main differences between the present invention and the invention of Japanese Patent Application No. 51-7224 will be described.

The invention of Japanese Patent Application No. 51-7224 relates to riftunosulfonate obtained from lignocellulosic materials by the sulfite valve method using an art solution containing bisulfite and sulfur dioxide. A sulfonate is produced, and this lignosulfonate is water-soluble.

In contrast, the present invention utilizes alkaline lignin. Alkaline lignin is produced by the alkaline method (the cooking liquor contains sodium hydroxide in the presence of oxygen), the sorter method (the cooking liquor contains sodium hydroxide) and the sulfate method (the cooking liquor contains sodium hydroxide). obtained from the alkaline pulp process, such as IJum, sulfite containing IJum and bisulfite;
Only for alkaline aqueous solutions? Understand.

Therefore, even if an alkali is added to lignosulfonate, lignosulfonate does not change into alkali lignin, so the present invention and the invention of Japanese Patent Application No. 7224/1988 are different in contrast.

[Brief explanation of the drawing]

Figures 1 and 2 show the calibrators and internal method (f
! Characteristic diagrams showing the elution of substances, Figures 3 and 4 are light 11
Characteristic diagrams showing the relationship between the relative retention volume of the calibrator and the logarithm of the molecular weight measured by the citurbation method and the elution method. Gutsuruhot 7-8'
Figure 6 is a gel chromatogram of unfractionated lignin from the Kraft cooking liquor of Scottish pine; Gel chromatogram B++C++D,,E,
and Fl, and FIG. 7 is a characteristic diagram showing accumulated values of molecular weight distribution corresponding to the chromatogram shown in FIG. 6, respectively. FIG, 1゜FIG, 2゜FIG, 3゜FIG, 6゜FIG, 4゜FIG, 5a sa= 5b. FIG, 7°

Claims (1)

[Scope of Claims] 1. Three lignin derivatives used in adhesives for manufacturing plywood, chipboard, fiberboard and other similar wood products, consisting of lignin derivatives separated by molecular weight and phenol formaldehyde resin.
An adhesive characterized in that 5% by weight or more and less than 50% by weight have a molecular weight greater than 5000, and the lignin derivative used is alkali lignin. 2. In the adhesive according to claim 1, the pH is 8.
~14 adhesive. 3. The adhesive according to claim 1 or 2, in which more than 40% by weight and less than 50% by weight of the lignin derivative used has a molecular weight greater than 5000. 4. The adhesive according to claim 1 or 2, in which 45% by weight or more and less than 50% by weight of the lignin derivative used has a molecular weight greater than 3483. 5. The adhesive according to claim 1, 2, 3 or 4, wherein the lignin derivative used is in the form of an alkaline salt. 6. In the adhesive according to claims 1, 2, 3, 4 or 5, from 1 to 15% by weight, preferably from 5 to 10% by weight, based on the dry substance weight of the phenol formaldehyde resin.
adhesive containing urea.