FI58141B - SAETT ATT FRAMSTAELLA HAERDBARA KONDENSATIONSHARTSER AV FENOL OCH / ELLER KRESOL - Google Patents

Description

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Federal Republic of Germany-Förbundsrepubliken Tyskland (DE) P 2363357-0 (71) Th. Goldschmidt AG, Goldschmidtstrasse 100, * + 3 Essen, Federal Republic of Germany Förbundsrepubliken Tyskland (DE) (72) Arnold Laqua, Essen, Ulrich Holtschmidt, Essen, Dietmar Schedlitzki, Niedervenigern, Federal Republic of Germany (Förbundsr) +) Oy Borenius & Co Ab (5 * +) Method for the production of phenolic and / or cresol curable condensation resins -Sätt att framställa härdbara condensation resins with phenol and / or cresol

The invention relates to a process for the preparation of phenol and / or cresol curable condensation resins, in which case up to 60 mol% of phenol and / or cresol have been replaced by melamine, urea or thiourea, and the molar ratio of phenol and / or cresol to formaldehyde is 1: 1. ..1: 3, and when melamine, urea or thiourea are used in addition, the molar ratio to formaldehyde is up to 1: 4, in the presence of basic catalysts at elevated temperature.

It is known from DE-A-1,905,814 to use guanidine carbonate as a curing accelerator. The addition of guanidine carbonate takes place after precondensation. Addition directly to the reaction charge is impossible because phase separation occurs. The addition of guanidine carbonate raises the pH by about 0.5 to 0.8 pH units, which reduces the product's storability. In addition, guanidine carbonate slows the curing of aminoplast resins.

U.S. Patent No. 2,636,019 discloses water-insoluble, i.e., cured, exchange resins containing quaternary ammonium groups as alternating groups. Mannich bases, which are a significant proportion of resins, must be added to the reaction to the greatest extent possible to incorporate interchangeable quaternary ammonium groups into the resin. There is still R.W. From Martin's book "The Chemistry of Phenolic Resins", 2 58141

New York (1956), John Wiley & Sons Inc. p. 4, it is known that phenol-aldehyde or phenol ketone compounds, such as phenol-derived Mannich bases, act as catalysts in the curing of polyepoxide resins.

Curable phenol-formaldehyde resins, in which part of the phenol may be replaced by e.g. cresol, as well as mixtures or mixed condensation products of these resins with amino resin formers, e.g. melamine, urea or thiourea, are used to impregnate and coat load-bearing webs. or as adhesive resins.

The preparation of these curable condensation resins can be accelerated by adding alkali or alkaline earth metal hydroxide and operating at an elevated temperature. In this case, limits are set for the reaction temperature and the addition of the catalyst, which depend on the technical conditions of the preparation and the final properties of the resin.

In the case where the hardening precondensates of the above-mentioned condensing resins are mainly used for impregnating and coating paper-bearing load-bearing webs in order to improve the surface quality of wood-based panels, the impregnated and coated load-bearing webs must be dried to a certain concentration of volatile components. "Jitter value". During drying, condensation of the resin continues. Thus, the rate of the condensation reaction also affects the drying of such resin-treated support webs, which is necessary to achieve a certain vibration value necessary for use.

The object of the invention is first and foremost to accelerate the reaction rate in the preparation of resin precondensates, as well as in the curing of resin precondensates to finished cured final products.

According to the invention, this object is achieved by adding 10 to 10 moles of Mannich base per mole of phenol and / or cresol or a mixture containing melamine, urea or thiourea at a time or in portions to the reaction charge or to the partially pre-condensed resin.

By Mannich base is meant, as is known, the reaction product of a CH-acid compound, 58141 3 aldehyde and an amine. As the CH-acidic compound, for example, ketones such as acetone, butanone, cyclohexanone, cyclopentanone, acetophenone, propiophenone, p-methoxyacetophenone, benzacetone and the like can be used. Other CH-acidic compounds which may be mentioned are aromatic or heterocyclic compounds which can be subjected to electrophilic substitution, e.g. phenol, thiophene, pyrrole or indole. Formaldehyde is suitably used as the aldehyde, lower secondary amines are suitably used as the amine, e.g. dimethylamine, diethylamine, morpholine or piperadine. The list of compounds mentioned above is, of course, not exhaustive. Information on the type and course of the Mannich reaction can be found, for example, in Benno Reichert's "Die Mannich condensation", Springer-Verlag, Berlin 1959 and "Organikum" eines Autorenkollektivs, Verlag VEB Deutscher Verlag der Wissenschaften, Berlin 1970, page 511.

Mannich bases in the synthesis of which ketones are used as CH-acidic components are particularly suitable for the process according to the invention. In particular, 2-dimethylaminomethyl-cyclohexanone has proven to be advantageous.

If, instead, the components necessary for the formation of such a Mannich base, i.e. the CH-acidic compound, formaldehyde and amine, are used in the resin synthesis instead of the Mannich base, no acceleration of the reaction is achieved.

According to the invention, the Mannich base can be added at the beginning of the reaction or in several single doses during the reaction. In the case where less value is given to the acceleration of the impregnation resin preparation, "but instead it is desired to accelerate the drying time and the curing rate of the precondensed resin, the addition can also be performed after the precondensation preparation.

The preparation according to the invention has the advantage of substantially accelerating the reaction rate without significantly increasing the pH of the resin. Due to the acceleration of the reaction rate, the precondensate can be prepared in a short time. However, the advantage of acceleration is also that after the load-bearing webs have been impregnated and coated with the resin precondensate, the desired vibration value (concentration of volatile components) can be reached more quickly, because further condensation is also accelerated. Due to this, shorter drying times are also required to achieve the vibration value. At the same time, complete curing under heat and pressure is accelerated.

581 41 it

Due to the acceleration of the reaction, it is possible to reduce the content of catalysts, in particular alkali or alkaline earth metal hydroxides, and in many cases even to completely abandon the use of such catalysts. This is of particular interest in the case where, due to the intended use, resins with little or no electrolytes are desired.

In the case where the precondensation resins prepared according to the invention are used for impregnation and coating of load-bearing webs, it appears that the properties essential for this use, such as permeability, water dilutability and storage stability, are the same as those of known resins.

The mechanical and chemical properties of the cured resins, such as tear strength, weather resistance, solvent resistance, ability to withstand basic media, are not adversely affected.

The preparation method according to the invention is further illustrated by the following examples.

Example 1

Preparation of a typical phenol impregnating resin and effect of different Mannich bases on condensation time 752 g of phenol, 648 g of 37% by weight formalin and 17.6 g of 50% by weight sodium hydroxide solution are heated to 70 ° C. 240 g of paraformaldehyde are added in several portions over a period of 30 minutes, so that the temperature of the reaction mixture does not rise above 85 ° C. It is then heated to 90 ° C and condensed until the DIN gate viscosity of the phenolic resin at 20 ° C is 80 seconds.

In other preparations, different Mannich bases are added at the beginning of the reaction. Otherwise, proceed as described above.

The following Table 1 gives the Mannich bases used, their dosages and the total preparation time of the phenolic resin.

table 1

Dosage in moles of phenolic resin

Marmich base moles of phenols Preparation time, __to_h_ without Mannich base - 3.0 2-Dimethylaminoethyl-cyclohexanone 0.0067 1.6 2-Dimethylaminomethyl-cyclohexanone 0.013 1.2 2-Dimethylaminomethyl-cyclohexanone 0.020 1.0 581 41 Phenolic resin board. 1 cont. moles of phenols preparation time, per_h__ 1-dimethylamino-butanone- (3) 0.022 1,2 1-morpholino-butanone- (3) 0.020 1.6 1-dimethylamino-3-phenyl-propanone- (3) 0.014 1.3 2 - dimethylaminomethylphenol 0.017 2.3 2.4.6-tris- (dimethylaminomethyl) phenol 0.010 2.4 2.4.6-tris- (diethylaminomethyl) phenol 0.007 2.5 3-dimethylaminomethylindole 0.014 2, 3

Example 2

Determination of the pH of phenolic resins prepared according to Example 1

It can be seen from the following Table 2 that the pH of the resin changes only slightly when Mannich base is added. Thus, the acceleration of the reaction cannot be due to the increased pH of the resin, but depends exclusively on the catalytic effect of the Mannich bases.

Table 2

Mannich base Dosage pH without Mannich base - 8.2 2-Dimethylaminomethyl-cyclohexanone 0.0067 8.2 2-Dimethylaminomethyl-cyclohexanone 0.013 8.25 2-Dimethylaminomethyl-cyclohexanone 0.020 8.3 1-Dimethylamino-1-dimethylamino 3) 0.022 8.3 1-Morpholino-butanone- (3) 0.020 8.35 1-Dimethylamino-3-phenyl-propanone- (3) 0.014 8.2 2-Dimethylaminomethyl-phenol 0.017 8.2 2.4.6-tris - (Dimethylaminomethyl) -phenol 0.010 8.15 2.4.6-Tris- (diethylaminomethyl) -phenol 0.007 8.2 3-Dimethylaminomethyl-indole 0.014 8.25

Example 3

Effect of Mannich bases on drying time in the production of phenolic resin films

The phenolic resins described in Example 1 are used for the production of core films for layered structures, in which unbleached sulphate kraft paper with a basis weight of 150 g / m 2 is impregnated with resins and then dried to a final concentration of volatile components at ambient temperature of 150 ° C.

2 vibration value $ 6. The basis weight of the film is 220 g / m. The vibration value is determined by vibrating the films for 5 minutes at 160 ° C.

During drying, the phenolic resin continues to condense, especially in the final stage of drying, since the temperature at the phenolic resin film is then at its highest. It is noted that when using phenolic resins containing Mannich base, the drying time of the films is 5. ·.

20shorter than when using a resin without a Mannich base. Mannich bases. Mannich bases thus also have an accelerating effect during the continuous condensation of the resin.

If the same amounts of different Mannich bases are subsequently added to the phenolic resin without Mannich base of Example 1, a similar accelerating effect can be observed in the drying of the phenolic resin film.

Example 4

Effect of Mannich bases on final curing of phenolic resins

From the core films described in Example 3, laminates are prepared together by pressing 6 phenolic resin foils in each case at 145 ° C and 50 kp / cm. The pressing time is varied.

The final curing of the phenolic resins in the laminates is tested by keeping these laminates in water at 96 ° C for 48 hours, after which the degradation of the laminate is examined. The degradation of the laminate generally decreases with increasing compression time in the manufacture of laminates because the curing state of the phenolic resin increases in the same direction.

The shortest compression time after which the degradation of the laminate is no longer detectable is 10 minutes in the case of a phenolic resin without a Mannich base, but instead 7 to 9 minutes in the case of phenolic resins containing a Mannich base. This is also the case if the Mannich base is subsequently added to the impregnating resin.

7 58141

Example 5 This example shows that when using the components from which the Mannich base is formed, no acceleration of the phenolic resin condensation is achieved.

Under the conditions described in Example 1, a phenolic resin is prepared using 752 g of phenol, 648 g of 37% by weight formalin, 240 g of paraformaldehyde and 17.6 g of 50% by weight sodium hydroxide solution. At the beginning of the preparation, no Mannich bases are now added, but instead the equimolar molecular components required for the synthesis of Mannich bases: • a * a) instead of using 0.020 moles of 2-dimethylaminomethylcyclohexanone per mole of phenol, the same mole amounts of cycloxone are used, formaldehyde and dimethylamine.

b) instead of using 0.020 moles of 1-morpholino-butanone-3 per mole of phenol, the same mole amounts of acetone, formaldehyde and morpholine are used in each case.

c) instead of using 0.007 moles of 2,4,6-tris- (diethyl) aminomethyl) phenol per mole of phenol, the same mole amounts of phenol and in each case 0.021 moles of formaldehyde and diethylamine per mole of phenol are used.

No clear reduction in the production time of the penol resin can be observed in any of the “a), b) or c).

Example 6

Effect of Mannich bases at condensing temperatures below 90 ° C 752 g of phenol, 648 g of 37% by weight formalin, 240 g of paraformaldehyde, 17.6 g of 50% by weight sodium hydroxide solution and 24.9 g of 2-dimethylaminomethyl-cyclohexanone are heated: until the phenolic resin has reached a DIN flash viscosity of 25 seconds at 20 ° C. This is already the case after 50 minutes. Without Mannich base, on the other hand, it takes 4.5 hours.

8 58141

If 24.9 g of 1-morpholino-butanone- (3) is added to the reaction mixture instead of 2-dimethylaminomethyl-cyclohexanone, it takes 1.5 hours to prepare the resin.

Example 7

Preparation of low-electrolyte phenolic resin 376 g of phenol, 235 g of 37% by weight formalin and 11.1 g of 2-dimethylaminomethyl-cyclohexanone are heated to 80 ° C.

At this temperature, 129 g of paraformsdehyde are added portionwise over 30 minutes and the mixture is then heated at 90 [deg.] C. until a DIN rapid viscosity of 25 seconds is reached at 20 [deg.] C. This value is reached after a total of 80 minutes.

Without Mannich base, a viscosity of only 13 seconds at 20 ° C is achieved for up to 8 hours at 90 ° C. However, despite the long reaction time, the degree of precondensation of this resin is lower than that of the phenolic resin containing Kannich base.

Only Mannich-base catalyzed phenolic resin is particularly suitable for the production of phenolic resin films which, when cured, must have a particularly high resistance to water or aqueous media.

Example 8

A phenolic resin is prepared using barium hydroxide as the basic catalyst, heating 282 g of phenol, 279 g of 37% by weight of formalin and 11.7 g of barium hydroxide octahydrate to 70 DEG C., and 76.5 g of paraformaldehyde are added portionwise over 20 minutes. It is then heated at 85 ° C until a DIN flash viscosity is reached for 30 seconds at 20 ° C. This happens after a total of 2.5 hours.

The initial addition of 9 to 7 g of 2-dimethylaminomethyl-cyclohexanone to the reaction mixture shortens the phenol resin preparation time to 55 minutes.

Example 9

Phenol resin, which is particularly suitable for preparing phenolic resin films for plywood coating, is prepared using 376 g of phenol, 648 g of 37% by weight formalin and 32 g of 50% by weight sodium hydroxide solution, and heating the mixture for 2 1/2 hours at 90 ° C. The DIN quick viscosity of the phenolic resin is then about 80 seconds at 20 ° C.

When 16.9 g of 2-dimethylaminomethyl-cyclohexanone are initially added to the reaction mixture, the reaction time is only 50 minutes.

Example 10

The phenolic resins described in Example 9 are used to prepare phenolic resin films by impregnating unbleached sulfate kraft paper having a basis weight of 40 g / m 2 with phenolic resins and then drying at 150 ° C to a vibration value of $ 6.5. The basis weight o of the film is 120 g / m.

o 2 The phenolic resin films are then pressed at 130 ° C and 16 kp / cra into a five-ply MGaboon "cross plywood made of wood.

The minimum compression time for curing the phenolic resin is 8 minutes in the case of using a phenolic resin without a Mannich base, but only 6 minutes in the case of using a phenolic resin with 2-dimethylaminomethyl-cyclohexanone.

Example 11

Preparation of cresol resin 338 g of cresol with an m-cresol content of 50% by weight, 405 g of 37% by weight of formalin, 7.7 g of 2-dimethylaminomethyl-β-cyclohexanone and 24.8 g of 50% by weight of sodium hydroxide solution are heated 1.9 hours at 80 ° C until the cresol resin has reached a DIN goblet viscosity of 60 seconds at 20 ° C. Without Mannich base, instead, 4 hours are required for the condensation reaction.

Example 12

Manufacture of phenolic resins specially used for gluing purposes 581 41 ίο

In the first step of the resin synthesis, 752 g of phenol, 292 g of 37% by weight of formalin, 54 g of paraformaldehyde, 12.5 g of 50% by weight of sodium hydroxide solution and 130 g of ethanol are heated at 90 ° C until the free formaldehyde content has dropped to about 0.1 weight-#. Then, in a second step, 150 g of paraformaldehyde are added and the mixture is further heated at 90 [deg.] C. until the phenolic resin has reached a DIN flash viscosity of 80 seconds at 20 [deg.] C.

The length of the reaction time is 4 hours in the first step and 3 hours in the second step.

When 18.9 g of 2-dimethylaminomethyl-cyclohexanone are added at the beginning of the first stage, the first stage takes only 40 minutes and the second stage 2 hours. If, on the other hand, half of the Mannich base is added at the beginning of the first and half at the beginning of the second stage, the condensation times are 1 hour and 1 3/4 hours.

! / The addition of the Iannich base does not affect the gluing property of the phenolic resin in.

Example 13

A mixed resin of phenol and urea is prepared by heating 282 g of phenol, 351 g of 37% by weight formalin, 108 g of urea, 13.6 g of 2-dimethylaminomethyl-cyclohexanone and 6 g of 50% by weight sodium hydroxide solution at 80 ° C and adding portionwise over 20 minutes 157.5 g of paraformaldehyde. The reaction mixture is then heated for an additional 15 minutes at 90 ° C until a LIN flash viscosity of 80 seconds is reached.

Without Mannich base, the resin takes a total of 3 1/4 hours to prepare.

The mixed resin is suitable for making films for layered products.

Example 14

Manufacture of phenolic-melamine mixed resin suitable for impregnation of decorative papers

Claims (4)

58141 11 Preparation of phenolic-melamine mixed resin suitable for impregnating decorative papers 282. phenol, 227.4 g of melamine, 420 g of 37% formalin, 16.0 g of 2-dimethylaminomethyl-cyclohexanone and 6 g of 50% strength by weight sodium hydroxide solution are heated at 80 ° C: and 133.2 g of paraformaldehyde are added portionwise over 20 minutes. Heat at 85 ° C for about 30 minutes until a DIN rapid viscosity of 60 seconds is reached at 20 ° C. If no Mannich base is added, the total length of the condensation time is 2.5 hours. A process for the preparation of phenol and / or cresol curable condensation resins, optionally up to 60 mol% of phenol and / or cresol being replaced by melamine, urea or thiourea, and when phenol and / or cresol are used the molar ratio to formaldehyde is 1: 1. 1: 3, and when melamine, urea or thiourea are used in addition to a molar ratio of formaldehyde of up to 1: 4, in the presence of basic catalysts at elevated temperature, characterized in that 10 to 3 or more portions are added to the reaction charge or partially pre-condensed resin. .10 moles of Mannich base per mole of phenol and / or cresol or a mixture containing melamine, urea or thiourea. Process according to Claim 1, characterized in that "Mannich bases prepared from ketones, formaldehyde and secondary amines are used. Process according to Claim 1, characterized in that 2-dimethylaminomethylcyclohexanone is added as Mannich base. 1. Sät att framställa haradbara condensation resin from phenol ooh / eller cresol, varvar optionally up to 60 mol-% phenol och / eller cresol ersatts med melamine, urea or thiourea och and fall from the formation of phenol och / eller cresol formaldehyde