DK165184B - FORMAL SKIN-BINDING AGENT, METHOD OF MANUFACTURING THE AGENT, AND USE OF IT. - Google Patents

Description

in

DK 165184B

This invention relates to a formaldehyde binding agent for use in sheets made from lignocellulose materials using formaldehyde based adhesives, a process for preparing the formaldehyde binding agent, and the use of the formaldehyde binding agent.

Sheets, such as particle boards, particle boards and the like, are made from lignocellulosic materials using adhesives. The preferred adhesives (or adhesives) are based on formaldehyde such as urea-formaldehyde, melamine-formaldehyde, phenol-formaldehyde and resorcinol-formaldehyde resins or mixtures thereof. It is a well-known fact that sheets made using these adhesives have a formaldehyde odor that is both harmful and unpleasant.

Formaldehyde is released both during the manufacture of such plates and during their storage and final use.

Many methods have been proposed to avoid the release of formaldehyde, but they are either either ineffective or reduce the properties of the plates or require complicated execution procedures. Some of these procedures involve spraying or painting the hot plates coming out of the press with various solutions, such as solutions of urea and / or ammonia 25 or of ammonium salts. In general, these types of processes are not desirable for industrial use, as they require additional processing steps and are in any case not very effective.

Other methods involve the use of very complicated mixtures of a large number of components, some of which are natural adhesives. These products are also not very effective. A handicap thereby is the fact that the properties of the natural products are not constant.

Another way to reduce the content of free formaldehyde involves the use of an aqueous suspension of the urea pellets coated with a special wax.

This method also requires a separate feed line, since

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2 the product is not added to the adhesive formulation itself.

Swedish Patent Specification No. 395,712 discloses the use of molecular compounds as adhesive additives. These molecular compounds have as one component an aliphatic compound containing an amidogroup, or certain other nitrogen-containing groups, and, as the other component, a metal salt or compound containing an alcohol group. The molecular compounds must contain the two components in whole ratios. With the mold-aldehyde-binding agent according to the invention, hereby, both better plate properties of the manufactured sheets are obtained and a greater reduction of the free formaldehyde.

In the present invention, components (a) and (b) should not be present in stoichiometric conditions.

In addition, it is an advantage of the present invention that all components can be added together and dissolved in one step without heating.

In British Patent No. 1,099,088, Example 3 discloses a liquid containing water, urea and sorbitol applied to wood chips. The treated shavings are dried and glued and sprayed with urea and / or melamine formaldehyde resin. The method has the disadvantage of requiring a separate step and its main purpose is to reduce the durability of the plates. This publication does not mention the addition of an aqueous solution of urea and sorbitol to an adhesive based on formaldehyde. Nor is it mentioned that a reduction in the amount of free formaldehyde or a synergistic effect is achieved.

British Patent No. 1,280,961 relates to a process for preparing a modified precondensate of an aminoplastic resin wherein 1 to 20% by weight of the resin is added to the resin of a modifier comprising an amide of the general formula

O H

1 II I 2

R -C-N-R

wherein R 1 represents hydrogen or an alkyl group of 1-4 carbon atoms and R is an alkyl group of 1-6 carbon atoms.

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3

Preferably, a polyhydroxy compound is also added as a supplemental modifier. By direct comparison of wood chipboard containing the modified precondensate of GB 1,280,961 and wood chipboard containing the formaldehyde binding agent of the invention, it is found that the wood chipboards made by the prior art show almost no reduction in the amount of formaldehyde and that the physical properties of the the plates are substantially inferior to the plates containing the formaldehyde binding agent of the invention. The object of the invention is to provide a better-known formaldehyde binding agent which effectively reduces the formaldehyde odor without reducing the properties of the plate, without altering the reactivity of the adhesive formulations, and without requiring additional steps in the manufacture of particle boards, plywood or block boards. . This is achieved as indicated above with the formaldehyde binding agent of the invention.

The invention discloses a formaldehyde binding agent 2Q for use in sheets made from lignocellulosic materials using formaldehyde based adhesives, characterized in that it comprises an aqueous solution of.

a) at least one organic hydroxy compound selected from sorbitol, monosaccharides of up to 6 carbon atoms and disaccharides of up to 12 carbon atoms, and b) at least one amide selected from urea and thiourea, and optionally c) one aliphatic monovalent alcohol, and / or d) a water-soluble halide salt, the ratio of the organic hydroxy compound (s) to the amide or amides and any water-soluble halide salt present being non-stoichiometric, and the weight ratio of, on the one hand, component (a) and the optional components (c) and (d), and on the other hand component (b) is from 10: 100 to 400: 100 and the formaldehyde binding agent contains from 20 to 80% by weight of active ingredients.

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4

Although the individual components are not soluble in water, they can be dissolved in water if a mixture thereof is heated to 70 ° C in water.

The organic hydroxy compounds (component (a)) 5 are preferably soluble in water or in lower monovalent aliphatic alcohols.

Specific examples of suitable organic hydroxy compounds are fructose, mannose, sorbitol, dextrose, sucrose, maltose, lactose, dextrin and the like.

The amides (component (b)) used in the present formaldehyde binder are also preferably soluble in water or in lower monovalent aliphatic alcohols.

Suitable examples of amides are urea and thio-15 urea.

If desired, the present formaldehyde binder may further increase solubility contain additives (component (c)) which are lower monovalent aliphatic alcohols such as methanol, ethanol, isopropanol and the like.

A cheaper and more effective formaldehyde binder is obtained if inorganic compounds (component (d)) are added, consisting of halide salts, preferably halides of alkali metals or alkaline earth metals such as sodium chloride, potassium chloride and calcium chloride.

The ratio of organic hydroxy compound (component (a) to component (c), if present) inorganic compound (component (d), if present) and amide (component (b)) is preferably 10: 100 to 200Ϊ100 after weight. The present formaldehyde binder may be added to the usual adhesive formulations in amounts ranging from 1 to 10%, preferably 3 to 7% formaldehyde binder phase t-35 based on the weight of the liquid resin containing 65% wt% resin solids.

The present formaldehyde binder may contain 20 to 80% by weight, preferably 50 to 70% by weight.

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5 active ingredients (components (a) and (b) and, if present, components (c) and / or (d)). The water content of the formaldehyde binder depends on the solubility of the active ingredients and the amount of water that can be tolerated in the adhesive formulations.

The present formaldehyde binder can be prepared as claimed in claim 4 by simply adding the active ingredients and water to a mixer and mixing until the active ingredients are dissolved. This can be done at room temperature or at a raised temperature up to 70 ° C.

The present formaldehyde binder may be used when making sheets from lignocellulose-containing materials, using adhesives based on formaldehyde such as urea-formaldehyde, mela-15-min-formaldehyde, phenol-formaldehyde or resorcinol-formaldehyde resins or mixtures thereof.

Using the formaldehyde binder according to the invention as set forth in claim 7, it is possible to prepare plates that actually contain less than 10 mg of free formaldehyde per day.

20 g dry plate, determined by F.E.S.Y.P. (Federation of European Syndicates of Manufacturers of Panneaux of Particulars) perforator method No. EN 120.

The size of the free formaldehyde reduction of. depends on many factors and can therefore vary widely.

If the release of free formaldehyde is large (greater than 50 mg of formaldehyde per 100 g of dry plate), the reduction can be as large as up to 60 to 85%. If the release of free formaldehyde is relatively small, ie. 20 to 50 mg of free formaldehyde per day. 100 g of dry plate, the maximum reduction is generally 50 to 60%. The size of the reduction obtained also depends on the amount of formaldehyde binder used: The more form of aldehyde binder used, the smaller the amount * of free formaldehyde.

35 When the active ingredients of formaldehyde binder are readily used in combination with each other, the reduction of free formaldehyde is surprisingly much greater than the sum of the effects of the individual components and they do not

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6 any detrimental effect on the activity of the adhesive formulation or the properties of the sheets.

The following examples illustrate the invention. Parts and percentages are by weight.

5

Example 1 In this example, six different types of polyalcohols of which samples 1, 5 and 6 are according to the invention are shown, two different types of amides, an additive and an alcohol to amide ratio ranging from 57.5 / 100 to 385 / 100th

The various types of formaldehyde binder used are as follows:

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7

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All of the above figures are in parts by weight.

The adhesive preparations used in the various samples are as follows:

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9

Single-layer sheets are made in the laboratory by spraying each of these preparations on 25 kg wood chips. The plates are pressed for 10 and 9 and 8 sec / mm. The thickness of the plates is 17.3 mm. The temperature of the press is 2500 C and the pressure is 35 kg / cm. The dimensions of the sheets produced are 40 x 56 cm.

The results obtained are listed in the following table and are average values.

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11

The above results show that all the samples used have values equivalent to the control values and that the formaldehyde reduction is in the range of 32 to 47%.

5

Example 2

Comparative experiments have been performed to show that the reduction of the amount of free formaldehyde, as well as the properties of the plates, is better when the formaldehyde binding agent of the invention is used than when it is used in Swedish disclosure no.

395,712 discloses additives, especially at higher addition levels.

The preparations used were as follows: TABLE 1

Preparation 1 2 3 · * S *

Dextrose »0 20 Sorbitol - '210 ·

Sucrose - · 300 · · ·

Monoethylene glycol · · · 320

Diethylene glycol - "" "200

Hexanediol - - “* 275 25 Orea 400 330 330 310

Thiourea · · · · 370 355

Water 370 370 370 370 370 370 total 1000 1000 1000 1000 1000 1000 «dry matter 03 03 03 03. 03 03 30

Compositions 1, 2 and 3 are formaldehyde binding agents according to the invention, while compositions 4, 5 and 6 are selected from those proposed in Swedish writing.

The amounts of the compositions are given in parts by weight and are selected such that the total dry matter content of the individual compositions is the same. In compositions 4, 5 and 6, the molar ratios suggested in Swedish writing are used.

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12

Adhesives were prepared as set forth in this specification and the gelation time was determined to compare compositions # 1, 2 and 3 with compositions no.

4, 5 and 6. The composition of the adhesive is listed in parts by weight 5 of Table 2.

TABLE 2

Glue preparation 0 1 2-3 4 5 6 10

Urea Formaldehyde 3077 3077 3077 3077 3077 3077 3077 Resin, 65% (molar ratio F: U = 1.4: 1) Cures 400 500 500 500 500 500 500 (ammonium chloride, 15% solution) 20

Paraffin 250 250 250 250 250 250 emulsion, 50%

Ammonia water 25 ° Baurré 5 ----- -

Preparation 1 from Table. 1 - 460 - - - - - -

Preparation 2 from Table 1 - "460 - - - 25 Preparation 3 from Table 1 - - - 460 - - -

Preparation 4 from Table 1 - - - - 460 - -

Preparation 5 from Table 1 - - - 460

Preparation 6 from Table 1 - - - 460 30 Water 268 ------

Total 4000 4287 4287 4287 4287 4287 4287

Gelling time (s) 57 59 57 58 61 60 62

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13

Single-layer sheets were made in the laboratory by spraying each of these adhesives on 25 kg wood chips. The plates were pressed at 10, 9 and 8 s / mm. The thickness of the plates was 17.3 mm. The temperature of the press was 200 ° C

2 and the pressure 35 kg / cm. The dimensions of the plates were 40 x 56 cm. The results obtained are shown in Table 3, which indicates average values: TABLE · 3 10

Glue preparation 01 23456

Density (kg / ra3) 690 669 690 688 685 687 686 'Bending strength (N / mm2) 22.3 25.2 24.9 24.1 20.9 21.5 20.5 15 Tensile strength (N / mm2) 0, 75 0.81 0.85 0.82 0.65 0.63 0.61

Thickness Increase 69 6 * M 6.5 7.1 7.2 7.1 at 2 hours of swelling (%) 7

Thickness increase at 19.3 18.8 18.6 18.9 20.2 20.5 20.9 24 hour swelling (%)

Free formaldehyde 42 9.3 8.4 7.1 22.3 20.2 21 20 dry plate)

Reduction of · 78 80 83 47 52 50 Amount of formaldehyde (%) 25 The results shown in Table 3 show that the preparations, denoted in Table 1, 1 to 3, give plates with better mechanical strength and water resistance than the control sample (adhesive composition 0) , although the reduction in the amount of formaldehyde is extremely large. In contrast, compositions 4 to 6 of Table 1 yield plates that are inferior to the control sample, despite the reduction in the amount of formaldehyde being much smaller than that obtained with compositions 1 to 3.

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Example 3

Comparative experiments have been carried out to show that the solution of Example 3 of British Patent No. 5,197,107 is a non-standard solution.

1,099,088 (sample 2) is inferior to the formaldehyde binding agent of Examples 1-5 of the present application (sample 1):

The samples used were as follows: J_Weight Parts 2_Weight Parts 10 Sorbitol 140 Sorbitol (1: 1 in water) 10

Methanol 140 Sodium Fluoride 5

Urea 350 Urea 125

Water 370 Ammonium dihydrogen phosphate -160

Water 700

Total 1000 Total 1000 20

Adhesive preparations were prepared as in Example 1 and the gelation time and use time were measured to compare preparations 1, 2 and 3 with the control preparation 0. The preparations as well as the results are given in the following table:

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Parts by weight_O (g) 1 (g) 2 (g) 5 (g)

Urea-formaldehyde resin 65% 3077 3077 3077 3077

Molecular ratio F: U 1.25) Cures (Ammonium - 500 500 - 5 chloride 15% solution) Cures (85% formic acid) - - - 23.5

Paraffin emulsion, 50% 250 250 250 250

Ammonia water, 25 ° Baumé 5 _ -

Sample 1 - 307 - - 10 Sample 2 - - 307 307

Water__ 268 _ — _ ~ _ * 76.5

Total 4000 4134 4134 4134

Gelling time (in seconds) 68 64 49 44 pH 7.88 7.13 5.7 3.75

Application time (40 ° C) 4h 45a 4t15a 2h 20 ain.

Single-layer plates were made in the laboratory 20 by spraying each of these preparations on 25 kg wood chips. The plates were pressed at 10, 9 and 8 s / mm. The thickness of the plates was 17.3 mm. The temperature of the press was 200 ° C and the pressure was 35 kg / m. The dimension of the sheets produced was 40 x 56 cm. The results obtained are listed in the table below and are average values:

Preparation o 12. 3

Density (kg / m3) 690.00 687.00 689.00 650.00 30 Bending strength (N / mm2) 19.70 19.40 14.80 10.50

Tensile strength (N / mm2) 0.72 0.72 0.51 0.25

Thickness increase see, 2 hours of swelling (%) 7> 40 7 »20 8> 30 15'30

Thickness increase at 19.70 19.80 25.40 40.80 24 hour swelling (%) • Free formaldehyde * 18/20 10.10 15.30 16.10 35 (mg / J00 g dry plate)

Decrease of - 45, () 0 15.90 11.50 formaldehyde (%)

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16

It can be seen that the plates prepared with the solution of Example 3 from British Patent 1,099,088 (Preparations 2 and 3 containing Sample 2) have very poor properties as compared to plates made with the formaldehyde binding agent of the invention (Preparation 1 containing sample 1) despite the fact that the decrease in the amount of formaldehyde is considerably greater in preparation 1 than in preparations 2 and 3.

Example 4

Comparative experiments have been made to show that using an aqueous solution or dispersion of a modifier of British Patent No. 1,280,961 gives worse results than that obtained with the formaldehyde binding agent of the invention:

Two samples according to the invention (samples 1 and 2) and two samples according to British Patent No. 1 280 961 (samples 3 and 4) were prepared. The water content of samples 1 and 3 is lower than in samples 2 and 4. The samples were as follows: 20

Samples _-_ 1_2_3_4 parts by weight

Sucrose 250 - 250 -

Ethylene glycol 250 230 250 230 N-methyl formamide - - 250 350 Urea 250 350

Water 250 420 250 420 *

Total 1000 1000 1000 1000 pH 9.3 9.4 6.0 '5.9 30

Adhesives of the following composition were prepared. Gelling time, pH and application time were measured to compare samples 1 to 4 with control preparation 0.

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17

Preparation 0 (g) _H1) 2 (g) 3 (g) _4 (g)

Urea-formaldehyde 65% (molar ratio F: U.

1/25: 1) 3077 3077 3077 3077 3077 Cures (Ammonium in 5 chloride, 15% solution) 400 500 500 500 500

Paraffin emulsion, 50% 250 250 250 250 250, Ammon in water, 25 ° Baumé 5 - - - -

Sample 1 * 307 - · -

Sample 2 "** 707 - - 15 Sample 3" "" 307 "

Sample 4 · 307

Water 36 · - - - -

Total 4000 4134 4134 4134 4134 20 ......... .......................... .........................................

Gelation time (sec) 4 · 63 64 62 60 pH 7.8 7.14 7 ^ 13 7f19 7.10

Application time (40 ° C) 4t45 «4t20e .4t | 5« 3t 15 · 3.t05 · 25 Single layer sheets were made in the laboratory by spraying each of these preparations on 25 kg wood chips. The plates were pressed at 10, 9 and 8 sec / mm. The thickness of the plates was 17.3 mm. The temperature of the press was 200 ° C and the pressure was 35 kg / cm 2. The dimensions of the 30 sheets made were 40 x 56 cm.

The results obtained are shown in the table below, which indicates average values:

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18

Preparation 01234

Density (kg / mm2) 691 681 685 683 681 Bending strength (N / mm2) 19.80 19.95 19.30 17.60 16.70

Tensile strength (N / mm2) 0.71 0.75 0.72 0.60 0.58 5 Thickness increase at 2 hour swelling (%) 7.80 7.40 7.20 8.70 9.30

Thickness increase at 24 hours swelling (%) 20.30 20.10 19.60 21.90 22.90, n Free formaldehyde lu (mg / 100g dry plate) 18.50 10.00 9.50 16.90 17 , 30

Decrease in Formaldehyde Amount (%) - 45.95 48.65 8.65 6.95 15 It is noted that although there is practically no reduction of free formaldehyde in the plates made with samples 3 and 4 of British Patent No. 1 280 961, the properties of these plates are substantially inferior to those obtained with samples 1 and 2, 20 made according to the invention.

Claims (7)

Formaldehyde binding agent for use in sheets made from lignocellulosic materials using formaldehyde based adhesives, characterized in that it comprises an aqueous solution of a) at least one organic hydroxy compound selected from sorbitol, monosaccharides having up to 6 carbon atoms. and disaccharides having up to 12 carbon atoms, and 10 b) at least one amide selected from urea and thiourea, and optionally c) an aliphatic monovalent alcohol, and / or d) a water-soluble halide salt, the ratio of the organic compound (s) the hydroxy compound and the amide or amides and any water-soluble halide salt present are non-stoichiometric, and the weight ratio of component (a) to optional components (c) and (d), and component (b), on the other hand. ranging from 10: 100 to 400: 100 and the 20 formaldehyde binding agent contains from 20 to 80% by weight of active ingredients. Formaldehyde binding agent according to claim 1, characterized in that (d) is a water-soluble halide of an alkali metal or an alkaline earth metal. Formaldehyde binding agent according to claim 2, characterized in that (d) is sodium chloride, potassium chloride or calcium chloride. Process for the preparation of a formaldehyde binding agent as defined in claim 1, characterized in that a) at least one organic hydroxy compound selected from sorbitol, monosaccharides of up to 6 carbon atoms and disaccharides of up to 12 carbon atoms, and 35 b ) at least one amide selected from urea and thiourea, and optionally DK 165184B c) an aliphatic monovalent alcohol and / or d) a water-soluble halide salt, the ratio of organic hydroxy compound to amide and water-soluble halide salt if the latter is present. stoichiometric, and the weight ratio of on the one hand component a) to the optional components c) and d) on the other hand component b) is from 10: 100 to 400: 100 and water is mixed at a temperature from room temperature up to 70 ° C to form a formaldehyde-binding agent containing from 20 to 80% by weight of active ingredients. Process according to claim 4, characterized in that d) is a water-soluble halide of an alkali metal or an alkaline earth metal. Process according to claim 5, characterized in that d) is sodium chloride, potassium chloride or calcium chloride. Use of a formaldehyde binding agent according to any one of claims 1-6 for the preparation of 20 sheets from lignocellulosic materials using a formaldehyde-based adhesive, characterized in that the formaldehyde binding agent is added to the adhesive.