CS209523B2 - Method of making the particle boards - Google Patents

Description

The present invention relates to a process for the production of formaldehyde-free particle board using amino resins.

Hitherto, acid curing catalysts have been used for the polycondensation of amino resins used to bond water-permeable cellulose particles in the manufacture of particle board. Their disadvantage is that the useful cure rates of the resin achieved by their use are relatively low at higher temperatures. The addition of acid curing catalysts, while increasing the curing rate, gradually achieves a value at which further increasing the rate of water to deteriorate the properties of the bonded material.

In addition, when these known catalysts are added in greater quantities, polycondensation also occurs at ambient temperature (despite the addition of inhibitors such as ammonia or hexamethylenetetramine). This shortens the shelf life of the binder at ambient temperature and leads to curing of the mixture before it is introduced into the press and all other known drawbacks associated therewith.

The aforementioned drawbacks have no process for the production of non-formaldehyde-flavored flake plates using the amino resins according to the invention, which comprises mixing 100 parts by weight of cellulose particles with 99 to 70 parts by weight of amino resin together with a conventional amount of ammonium chloride; to 30 wt%, VZ ^for shifting on solid resin, a catalyst for the polycondensation anrnopryskyřic, wherein said catalyst comprises a solution of from 30 to 150 parts by weight of a mixture of organic and inorganic components in 100 parts by weight of water, wherein the organic component is formaldehyde and urea or nezpryskyřičnatělý condensing the formaldehyde and urea product and the inorganic component is a water-soluble alkali metal halide and said solution comprises an organic and inorganic component in a ratio of 0.1 to 10 parts by weight of the organic component per 1 part by weight of the inorganic ingredients, the amount of water depends on the solubility of organic and inorganic components and the solids content desired for a production system used, whereupon the mixture thus obtained is compressed.

An advantage of the process according to the invention is that it increases the curing rate of the amino resin at a higher temperature to a value that cannot be achieved by simply adding acid curing catalysts.

By adding the catalyst used in the process according to the invention, the curing rates can be further increased and at the same time the subsequent pressing times can be shortened without any deterioration in the properties of the bonded material. The addition of said catalyst is effective only at high temperatures. Therefore, the rate of polycondensation of the amino resin is substantially increased at the pressing temperature but not at room temperature, so that the problems associated with premature curing are eliminated. The catalyst is bonded to and formed into the resin.

The combination of the organic and inorganic components of the catalyst used in the process of the invention exhibits synergistic behavior. When the individual components are added to the resin itself, although some cure speed increases, but when used in the form of a blend, the increase is greater than the sum of the effects that occur when each component is added separately.

The salt derived from halides may be a soluble alkali metal halide. The organic material may be a resinous condensation product of urea with formaldehyde. In order to improve the resin dispersion, it is advantageous to also add a small amount of surfactant to the catalyst, such as 0.1 to 2%.

The catalyst used in the process of the invention (calculated as 100% solids content) may be added in an amount of 1 to 30% solids content of the resin used. The most important aspect of the invention is that the catalyst can replace part of the resin without compromising the properties of the final product. However, this is not achieved by adding the catalyst in amounts that are directly equal to the amount of the resin replaced, but by adding the catalyst in an amount of from 50 to 70% of the replaced resin (calculated on a weight percent basis) 100% solids).

Due to its synergistic behavior, the catalyst used in the process according to the invention can replace the resin in an amount up to twice its own weight. The above-mentioned property of this catalyst results in the addition of 20% by weight of resin, which corresponds to a replacement of about 40% by weight of the resin used. When added in minor amounts, for example 3 to 10%, the properties of the final product will be greatly improved. When added in larger amounts, for example up to 30%, no difference in the properties of the end product will occur, but the cure rate will increase significantly and the resin will be saved.

Amino resin bonding in a known manner is influenced by curing the resin at higher temperatures and pressures. The catalyst can be used for all types of products in which urea-formaldehyde resins are used to bond lignocellulose products, regardless of whether wood particles are used for the production of particle board using flat presses or calenders or wood veneers such as for the production of plywood. The quality of the boards produced was checked weekly over a period of 6 months and no deterioration of the board properties was observed. This suggests that no polymer degradation has occurred and the aging-related properties of the boards are comparable to those of products manufactured in the normal way.

The prior art resin replacement substitutes do not permit the maintenance of the conditions of the known chipboard manufacturing processes using higher amounts of the substitute and also do not lead to a simultaneous increase in the production rate. The known substitutes are in particular halide salts, but the mixture of halide salts with the addition of urea and formaldehyde is not used.

The addition of salt (halides) alone allows the replacement of a portion of the resin compared to the catalyst used in the process of the invention, with the following limitations:

1. the rate of production shall not increase; in the case of a larger amount of substitute, this rate actually decreases as the substitutes act as an inhibitor instead of a catalyst due to the high amount of water present;

2. substitution is possible in a ratio of 1: 1, while ratios of up to 1: 2 are possible using the catalyst used in the process of the invention;

3. larger replacement amounts are achieved by separate spraying with a halide solution followed by drying and spraying of the binder: in the case of using the catalyst used in the process of the invention, a larger quantity can be replaced without the need for spraying and then drying; the catalyst is added to the resin solution and this solution is used to spray the wood mass in one step.

The method of the invention provides yet another advantage. Due to the smaller amount of resin used and the improved effects achieved, the amount of free formaldehyde in the production of the boards is greatly reduced and the boards produced are almost odorless.

The process according to the invention will be explained in the following part of the description by way of examples.

He did

I i

This example illustrates the advantages achieved in the manufacture of particle board with the addition of the catalyst used in the process of the invention.

Three experiments will be described in which the same total amount of the mixture will always be used. The differences are only related to the different properties of the individual components of the solution used, as shown in Table I below. Column B refers to the production of the outer surface of the particle board. Column B refers to the solution used to spray wood chips that are used to make the particle board core.

Particle boards were produced in this case by Bison system, ie. under continuous production under controllable conditions which were kept constant for all experiments:

Moisture content of the lot before the draw 10,0 ± 0,5%

Pressing temperature 210 ° C

Pressure 3.5 MPa

The quality of the particle boards produced in this way shows no apparent differences in any of the three tests (see results in Table I).

The different solutions prepared in all three experiments in accordance with the conditions of the process according to the invention lead to a reduction of the pressing time as follows:

Experiment 1:

9.25 s / mm uncut chipboards. Experiment 2:

8,00 s / mm uncut chipboards. Experiment 3:

7,00 s / mm uncut chipboards.

The third experiment, which involves using the largest amount of organic component compared to the organic component, shows the best results:

The example shows that in the process according to the invention it is possible to shorten the pressing times in the manufacture of particle board and that it is also possible to reduce the amount of resin used in the process according to the invention by about 30 ° / o, about 16.90 θ / o (experiment 2) or about 21% (experiment 3).

TABLE I Components (parts by weight) Attempts 1 AND 2 (B) 3 AND (B) AND (B) Urea-formaldehyde resin (solids content 65%) 100 ALIGN! 203 70 140 70 140 Ammonium chloride (20% aq solution) - 8 - 8 - 8 Water 68 5 31.0 53-5 30 0 58 5 20.0 Ammonia density 25 ° Baumé 1.5 1.0 1.5 2,0 1.5 2,0 Catalyst solution - - 40 70 40 70 Total 170 240 170 240 170 240 Components (parts by weight) Try > y 1 2 3 AND (B) AND (B) AND (B) Urea (100%) - - 5.35 5.35 10.70 10.70 Formaldehyde (100%) - - 2.75 2.75 5 50 5.50 Sodium chloride (103%) Surfactant - - 20 May 20 May 20 May 20 May  (10% aqueous solution) - - 1 1 1 1 Water - - 70.9 70.9 62.8 62.8 Total - - 100 ALIGN! 100 ALIGN! 100 ALIGN! 100 ALIGN! Properties Try •OF 1 ' 2 3 Density (kg / m ³ ) 660 640 625 Thickness (mm) 16.2 16.0 16.1 Modulus of elasticity L 26 000 23 200 24 003 Tensile strength (MPa) 0.50 0 45 0.42 Flexural strength (MPa) Water absorption capacity 25 23 22.5 in ° / o after 24 hours of draft Proportion in θ / ο increment of swelling 40 45 52 after 24 h dive 13 15 Dec 20 May

Example 2

This example illustrates the rate of increase in particle board production achieved by the process of the invention (i.e. by adding the catalyst used in the process of the invention to a mixture of sodium chloride and urea formaldehyde monomer) compared to the rate achieved with a simple addition sodium chloride (without urea-formaldehyde monomer).

The results obtained are shown in Table II below, in which Experiment 1 comprises the use of sodium chloride only, in addition to the usual additives which are added to the resin mixture for the manufacture of particle board, achieving a gelation time of 80 s. in experiment 1; in addition, urea-formaldehyde monomer and the same amount of sodium chloride are added. The gellation time in this case is 28 s.

For particle boards obtained under the same conditions using the Bison for both experiments according to the invention, the production speeds of 9 s / mm for test 1 and 7 s / mm for test 2 resulted in the mechanical properties achieved according to DIN 52 350 to 52 365 the same cases.

TABLE II

Components (parts by weight)

Moea-formaldehyde resin (65% solids content)

Water

Ammonium chloride (20% aqueous solution)

Hexamethylenetetramine

Sodium chloride (100%)

Urea (100%)

Formaldehyde (100%)

Total

Gelling time (s)

Pressing time in s / mm thickness of unground plate

Density (kg / m ³ )

Thickness (mm)

Modulus of elasticity L

Tensile strength (MPa)

Flexural strength (MPa)

Water absorption in% after 24 h dive Increase in% swelling after 24 h dive

Attempts

1 2 140 140 58 43.42 12 12 8 8 12 12 - 6.93 - 4.95 230 230 80 28 9 7 660 640 16.05 16.20 500 23 200 0.60 052 23 5 24.0 45 60 13.4 14.9

Example 3

This example illustrates the enhanced compensation _mo: urea-formaldehyde resins with addition of a catalyst employed in the process of the invention compared with less compensation, which was achieved using only sodium chloride without the addition of the monomer of urea and formaldehyde, whereby the produced chip board, which in both cases exhibit equivalent mechanical properties.

This example will explain in particular where the substitution can be expressed as 1: 1 for sodium chloride based on resin, whereas for 1: 2 the sodium chloride-urea-formaldehyde substitution ratio was 1: 2. processed with the corresponding recipes listed in Table III.

Formulation 1 serves as a blank test without resin replacement. The formulations differ from each other in that in the formulation 2 the resin solids are replaced only with sodium chloride, whereas according to the formula 3 (formulation according to the invention) the resin is replaced by a mixture of NaCl with urea and formaldehyde monomers.

In Formulation 2, 19.5 parts of solid resin were replaced with 19.5 parts of sodium chloride.

In recipe 3, 39 parts of solid resin were replaced with 19.5 parts of solid catalyst (i.e., sodium chloride, urea and formaldehyde).

Thus, there was a 1: 1 replacement in formula 2 and a 1: 2 replacement in formula 3.

Particle boards produced using both mixtures had the same mechanical properties, although in the formulation 3 there was a lower solids content. In both cases the particle boards were produced by the Bison system. continuous production of the layer under controllable conditions, which were kept constant in both cases:

Moisture of matter

before pressing 10.5 ± 0.5% Properties of produced particle boards Pressing temperature 210 Noc: 2 ° C are given in Table III below. Pressure 3.5 MPa TABLE III Components (parts by weight) Attempts 1 2 3 AND B A B A B

Urea-formaldehyde

resin 100 ALIGN! 200 90 180 80 60 Solids content of urea formaldehyde resins 65 130 58.5 117 52 104 Ammonium chloride (20% solution) - 8 - 8 - 8 Water 68.5 31.0 72.0 38.0 66.17 26.33 Ammonia (25 ^c Bé) 1.5 1.0 1.5 1.0 1.5 1.0 Sodium chloride (100%) - - 6.5 13.0 - - !) Reactive catalyst (100% solid) - - - 6.5 13.0 Reactive catalyst (100% solids) A + B - - ' 19.5 Water - - - - 15.83 31.67 Total amount of solution resin 170 240 170 240 170 240

!) Reactive catalyst components: urea (100%) - 19 parts, formaldehyde (100%) - 10 parts, sodium chloride (100%) - 71 parts: total 100 parts.

Components (parts by weight) Experiments

1 2 A B 3 AND (B) AND (B) Total solids content 65.0 131.6 65.0 131.6 58.5 118.60 Solids content in% Parts replaced by solids 38.5 54.8 38.2 54.8 34.4 49.4 resin Solid resin parts - 6.5 13.0 13.0 26.0 - compensation A + B - 19.5 39.0 % resin, substituted A + B The ratio of the amount of solid added - 10 20 May substitutes to the amount of substituted solid resin _ 1 - 1 1: 2 Properties Attempts 1 2 3 Density (kg ³ ) 645 630 625 Thickness (mm) 16.1 16.5 16.2 Modulus of elasticity L 24 500 25 000 23 800 Tensile strength (MPa) 0.45 0.50 0.48 Flexural strength (MPa) Water absorption in% after 24 h 23.5 22.3 24.0 dive % Swelling increment 45 50 53 after 24 h dive 14 17 16

Example 4

The novelty of the invention results from the fact that when a high degree of resin replacement is desired, it is absolutely necessary to use the composition according to the invention in order to sprinkle the cellulose particles in one step as is done with all types of particle board systems .

If only sodium chloride is added to the resin without the addition of urea and formaldehyde, apart from the fact that the velocity is negligible, as shown in the previous examples, it is also necessary to spray the wood chips separately with sodium chloride followed by wood drying mixture and further binder spraying. This procedure requires the use of additional equipment which is expensive and reduces production capacity.

Additional manufacturing steps are required for the low solubility of sodium chloride in water and also when the resin replacement is achieved by adding a solids amount equal to the solids of the replaced resin. To replace a larger amount of resin, too much water is required in the mixture, which cannot be dried in a single stage in a press for the usual pressing time.

The process according to the invention achieves the replacement of larger amounts of resin without the use of too much water and where it is possible to produce the boards in one stage, as is usually done in the production of particle boards, there is no need to change the production process at all. This is possible according to the invention because of the fact that the solubility in water is higher and therefore less water is used, but also because the replacement is achieved by adding half the amount of the replaced material, calculated as a solid material.

To achieve an equally high degree of substitution (35% in this case) using the process of the invention, the gelation time is shorter and, consequently, the production rate is higher (mixture 3). When using only sodium chloride without the addition of urea monomer and formaldehyde, the gelation time is much longer, since in this case the added substitutes act as an inhibitor instead of a catalyst (mixture 2). All the above points result from the formulas listed in Table IV below. This table lists three mixtures:

mixture 1 serves as a blank test in which the resin is used without any substitutes;

mixture 2 contains only sodium chloride, which replaces the resin, and mixture 3 contains the catalyst used in the process of the invention, i. sodium chloride and urea-formaldehyde monomer.

The percentage of resin replaced is in mixtures of 2 and 3 to 35 ´%. In mixture 3, 37.5 parts of the catalyst according to the invention were replaced, replacing 68.5 parts of solid resin, and in mixture 2, 68.5 parts of sodium chloride was added, replacing the same amount of resin, i.e., the same amount of resin. 68.5 parts prys12 resin. This indicates that a 1: 1.8 replacement was achieved in the method of the invention, while a 1: 1 replacement was achieved using only sodium chloride.

The total amount of resin solution in mixture 3 containing the catalyst used in the process according to the invention was the same as in the case of mixture 1. However, this was not possible with a large amount of water whose presence in the mixture 2 was only sodium chloride added. a high degree of resin replacement is required.

The gelation time of the blank was 60 s. For mixture 3 containing the catalyst used in the process of the invention, the gelation time was lower (40 sj, which allowed a higher production rate; in mixture 2, where only sodium chloride was used, the gelation time was 110 s). s, the added components acted as an inhibitor instead of a catalyst.

Column A refers in all three cases to the solution used to sprinkle the wood flour used to produce the outer surface of the particle board. Column B refers in all three cases to the solutions used for spraying wood chips, which are used to make the particle board core.

Particle boards were produced using the resin mixture listed in Table IV for three cases. The production method used is the Bison system and the conditions were kept constant in all three cases:

Material moisture before pressing 10.5 ± 0.5% Pressing temperature 120 ° C

Pressure 3.5 MPa

The quality of the produced particle board complied with the DIN 52 360 to 365 standard and showed no differences in cases 1 and

3. In case 2, where only sodium chloride was contained in place of the catalyst used in the process according to the invention, the properties of the particle board produced could not be measured, since the produced plates were already squeezed out during normal pressing time. This suggests that the use of sodium chloride alone will not allow high degrees of substitution of the order of 35% when used to produce particle boards in a single spray stage according to the known method.

TABLE IV

Components (parts by weight) Experiments

3

AND (B) AND (B) AND (B) Urea-formaldehyde resin 100 ALIGN! 100 ALIGN! 65 130 65 130 Solid resin 65 130 42 84.5 42 84.5 Ammonium chloride (20% solution) -. 8 - 8 - 8 Water 68.5 31 - - 68.5 31 Ammonia (25 ° Bé) 1.5 1.0 1.5 1.0 1.5 1.0 Sodium chloride (100%) - - 23 45.5 - - Sodium chloride A + B - 68.5 - ^x j reactive catalyst (100%) - - - - 12.5 25 Reactive catalyst A + B - - 37.5 Water - - 82 161.5 22.5 45 Total amount of solution resin 170 240 213.5 346 170 240 ^X J Catalyst composition in%: urea (100%) 30, formaldehyde (100% J - 15,

Sodium Ride (100%) - 55.

A B

A B

Total solids content 65 131.6 65 131.6 54.5 111.1 Solids content in% 38.2 54.8 30.8 38 54 53 Fixed parts replaced resin - - 23 45.5 23 45.5

Parts of the replaced solid resin A + B% of the replaced resin A + B

68.5 68.5

35

The ratio of the amount of solid substitute added to the amount of resin solid replaced -

Gelation time (s)

1: 1 1: 1.8

110 40

Example 5

This example relates to the manufacture of a veneered particle board. In particular, the example shows that the method according to the invention can also be used for gluing flat slats, such as for the manufacture of plywood, laminated boards, veneered boards or other multilayer boards.

In this case, on both surfaces of the ground chipboard of a thickness of 15 mm, size 185 x 305 cm and a moisture content of 9 o / o, a 0.7 mm thick Tianna veneer foil and a moisture content of 10% _were glued. The binder was applied to the chipboard by a coating device.

The plates were pressed at a pressure of 0.7 MPa at a temperature of 120 ° C. Two experiments are presented. In Experiment 1, normal binder preparation was used, in Experiment 2 the method of the invention was used. These preparations are shown in Table V below.

While the boards produced with the binder prepared according to Test 1 required a pressing time of 2 minutes, for the boards produced by the method of the invention, a pressing time of only 1.7 minutes was sufficient.

In the preparation of the boards according to the invention, the following were achieved:

15% increase in production speed and binder savings: 26%.

1S

TABLE V

Components (parts by weight)

Attempts

Urea-formaldehyde resin (solids content 65%) 100 70

Ammonium chloride (20 θ / ₀ aqueous solution)

Sodium chloride - 6.0

Urea (100%) - 1.62

Formaldehyde (100%) - 0.83

Water - 21 ^ 55

Flour 7 10

Total quantity 115 118

Example 6

In this embodiment, it will be shown that the process according to the invention achieves the described effect even at the limit ratios of the organic and inorganic components. Three solutions were prepared, the composition of which is shown in Table VI below.

TABLE VI

Components (parts by weight) 1 Solutions 2 3 Formaldehyde (100%) 103 11 183 Urea 160 16 292 Sodium chloride 27 Mar: 260 98 Water 707 713 427 Total 1000 1000 1000

In solution 1 the ratio of organic component / / inorganic component is 10: 1, while the same ratio for solution 2 is 0.1: 1. Both solutions have a solids content of 29%. Solution 3 is more concentrated. It has a solids content of 57 o / o with an organic / inorganic component ratio of solution 3 of 4.8: 1.

These solutions were used in Formulations I, II and III, the compositions of which are shown in Table VII below. These formulations, in turn, are used to produce 16 mm thick particle board.

Formulation IV is a control formulation consisting of a normal urea-formaldehyde binder to which the catalyst used in the process of the invention is not added.

Said chipboards are produced using a laboratory press of dimensions 40 x x56 c, m. 10 kg of wood chips are sprinkled with each formulation. Three plates are formed (manually) from the obtained mixtures. These plates are pressed at a speed of 11 s / mm. The press has a temperature of 200 ° C and a pressure of 3.5 MPa is used. The quality of the final boards is described in the table. The values given are the average of the three values measured for each of the three plates for each formulation.

TABLE VII

Components (parts by weight) Formulation

AND II III IV Urea-formaldehyde binder (65%) 1177 1177 1177 1385 15% ammonium chloride solution 270 270 270 270 Emulsion 77 77 77 77 20% solution of liexamethyl- tetramlnu 203 203 203 203 Solution 1 208 - - - Solution 2 —- 208 - - Solution 3 -. - 208 - Water 53 53 53 53

TABLE VIII

Formulation Density (kg / m ³ ) Flexural strength (MPa) Tensile strength (MPa) Percentage of% swelling increment after 2 h po 24 h AND 712 18.4 0.52 6.0 21.4 II 668 14.4 0.49 8.0 24.3 III 701 20.4 0.68 5.0 17.0 IV 731 19.5 0.44 13.1 23.2

From the results obtained, it is clear that the particle boards obtained using the process according to the invention using a catalyst in which the organic and inorganic components are contained in limiting amounts have better properties than the particle boards obtained in a manner known per se.

Example 7

This example illustrates the possibility of using other halides, such as sodium iodide and sodium bromide. Two solutions were prepared, the composition of which is shown in Table IX below. The contents of the individual components are given in parts by weight.

TABLE IX

Solution

Components (parts by weight)

Formaldehyde (100%) 40 40 Urea 100 ALIGN! 100 ALIGN! Sodium iodide 260 - Sodium bromide - 260 Water 600 600 Total 1000 1090

Said solutions were used in the formulations I and II, the compositions of which are given in the following Table X, and which in turn were used to produce 16 mm thick particle board. Formulation III is a control formulation containing a normal urea-formaldehyde binder to which the catalyst used in the process of the invention has not been added.

Particle boards were made using a 40x56 cm laboratory press.

10 kg of wood chips are sprinkled with each formulation. Three plates are formed (manually) from the mixtures thus obtained, which are pressed at a speed of 11 s / mm, the press is at a temperature of 200 ° C using a pressure of 3.5 MPa. the values are the average of the values measured for each of the three plates.

TABLE X

Formulation

I II

Components (parts by weight)

III

Urea-formaldehyde

binder (65%) 15% chloride solution 1177 1177 1385 ammonium 30 30 30 Emulsion 77 77 77 Solution 1 208 - - Solution 2 - 208 —- Water 53 53 53

TABLE XI Formulation Density (kg / m ³ ) Flexural strength (MPa) Tensile strength (MPa) Percentage of% swelling increment after 2 h po 24 h AND 720 15.9 0.65 17.4 27.5 II 711 14.5 1.00 13.2 25.4 III 732 16.9 0.74 17.2 26.0

From the above results, it is apparent that both formulations of the invention are equivalent and even better than formulation III, which is a control formulation and in which therefore the addition of the catalyst used in the process of the invention has not been used.

Example 8 The formaldehyde to urea ratio within the organic component of the catalyst used in the process of the invention.

Three catalyst solutions were prepared by mixing the ingredients listed in Table XII below at ambient temperature.

This example is to illustrate the effect of reciprocal TABLE XI

Components (parts by weight) AND Solution II III 30% aqueous formaldehyde solution 257 20 May 180 Urea 5 142 94 Sodium chloride 220 220 220 Water 518 618 506 Weight ratio of urea to formaldehyde (based on 100o / ₀ solids) 5:35 55: 5 1.4: 1

The above solutions were used in formulations whose composition is shown in parts by weight in Table XIII below.

TABLE XIII

Components (parts by weight) Formulaco and b C d Urea-formaldehyde resin (65% solution) 70 70 70 100 ALIGN! Solution I 30 - -. - Solution II - 30 -. -. Solution III -. - 30 - 20% chloride solution ammonium 7 7 7 7 Gelling time at 100 ° C (s) 27 Mar: 50 45 55

From the obtained gelling time values is roaring condensation product form- it is clear that the synergistic effect of aldehyde and urea. used in the method according to the invention can be seen even at extreme weight- Example 9 their urea to formaldehyde ratios (5:95 and 95: 5). This synergistic effect Prepare three solutions whose composition is This is also achieved if it is instead listed in % by weight parts in the table- mixtures of formaldehyde and urea used in ce XIV ........ the same weight ratio TABLE . XIV Components (parts by weight) Solution AND II III 44% aqueous formaldehyde solution 239 28 151 Urea 6 219 94 Sodium chloride 220 220 220 Water 535 533 535 Weight ratio of urea to formaldehyde du (calculated on 100% solids) 5:95 95: 5 59:41

These solutions were used in formulations the composition of which by weight is shown in Table XV.

.........

TABLE XV

Components (parts by weight) and b Formulation C d McKechino-formaldehyde resin (65% solution) 15% chloride solution 1247 1247 1247 1385 ammonium 150 150 150 150 Emulsion 77 77. 77 77 Ammonia 5 5 5 5 Solution I 138 - - - Solution II - 138 - - Solution IJI - —- 138 - Water 53  53 53 53 Total 1670. 1670 1670 1670

These formulations were used in the manufacture of 16 mm thick particle board, wherein formulation d is a control formulation consisting of a normal urea-formaldehyde binder, which did not use the catalyst used in the process of the invention. Particle boards were made using a 40 x x56 cm laboratory press.

10 kg of wood chips are sprinkled with each formulation. Three plates are prepared (manually) from the mixtures thus obtained. These plates are pressed at 10 s / mm, 9 s / mm and 8 s / mm. The temperature of the press is 200 ° C, with a pressing pressure of 3.5 MPa.

The properties of the boards obtained are shown in Table XVI below.

TABLE XVI

Formulation Pressing time (sbnm) Density (kg / m ³ ) Flexural strength (MPaj and 10 709 16.6 b io 714 18.4 C 10 711 16.6 d 10 713 13.5 and 9 699  14.7 b 9 704 170 C 9 687 1 5,4 d 9 708 14.6 and 8 679 14.1 b 8 683 17.1 C 8 697 15.5 d 8 680 14.4 From the above results it is clear that for-

the formulations a, b, c are the same or even better in terms of the results obtained than formulation d, which is a control formulation in which the catalyst used has not been used.

Strength 2hour 24hrs Module in turn swelling swelling flexibility (MPa) (%) (%) (M ^D a) 0.62 14.3 24.9 25 690 0.92 6.0 20.9 27 250 0.71 8.5 22.8 25 450 0.59 14.1 25.6 20 020 0.74 15.3 25.1 23 800 0.87 6.5 19.4 25 920 0.68 10.1 22.5 24 900 0.61 13.3 24.9 24 550 0.55 14.6 22.9 21 900 0.75 6.0 18.4 25 200 0.60 10.7 22.2 24 750 0.66 9.4 20.4 22 776

in the process according to the invention. The same results are obtained when a non-resinous condensation product of formaldehyde and urea is used instead of formaldehyde and urea.

Claims (1)

SUBJECT A process for the production of formaldehyde-free particle board using amino resins, characterized in that 100 parts by weight of cellulose particles are mixed with 91 to 70 parts by weight of amino resin together with a conventional amount of ammonium chloride and 1 to 30% by weight, based on solids. the resin, the catalyst for polycondensation of amino resins, said catalyst comprising a solution of 30 to 150 parts by weight of a mixture of organic and anorrhagic component in 100 parts by weight of water, the inventive organic component being formaldehyde and urea; is a water-soluble alkali metal halide and said solution comprises an organic and an inorganic component in a ratio of 0.1 to 10 parts by weight of the organic component per 1 part by weight of the inorganic component, the amount of water depending on the dissolution the organic and inorganic components and the solids content required for the production system used, and the mixture thus obtained is compressed.