NO133551B - - Google Patents

Description

The present invention relates to a new method for the production of heat-curable phenolic resins.

According to the known methods, such resins are produced by condensation. In particular, the phenolic resins are produced by condensation of 1 mol of phenol or a phenol derivative with at least 1 mol of formaldehyde in aqueous solution. This condensation, which is carried out in a basic environment, gives a resol

which must be evaporated under vacuum in order to remove as much as possible the water it contains due to the later uses.

It is further known to carry out polymerization of monomers in suspension to produce thermoplastic resins such as vinyl resins which allow obtaining particle aggregates whose diameter can be between 0.1 and 3 mm, which are practically free of water.

- Incidentally, it was not possible with polycondensation

to obtain heat-curable phenolic resins in the form of practically anhydrous beads, and whose grain size distribution could be regulated.,

The invention therefore relates to a method for the production of fusible beads of heat-setting phenolic resin, whereby an aqueous solution of formaldehyde and phenol or a phenol derivative in a molar ratio of formaldehyde to phenol between 1.0 and 3.1 is subjected to catalytic condensation using ammonia or a aliphatic amine in a ratio of 0.02 to 0.5 mol of catalyst to 1 mol of phenol used at a temperature between 50 and 100°C until an insoluble resin is formed, the method being characterized in that the starting reaction to the mixture, 0.01 to 0.2 mol per mole of phenol of a nitrogen-containing compound selected from the group consisting of hydrazine, tetraformaltriazine, piperazine, piperidine, dicyandiamide, melamine, urea and aniline, and that the formed insoluble resin which is present as droplets is stabilized by the addition of a suspending agent, after which the reaction mixture is cooled at the end condensation and the formed beads are separated.

According to an advantage of the present method and according to the invention, the suspending agent which is introduced to isolate the droplets of resin as it is formed and to prevent their coalescence preferably consists in association of a surface-active agent such as an alkali alkyl aryl sulfonate for example, with a protective colloid such such as a carboxymethyl cellulose or a polyethylene glycol, etc.

Advantageous results can be achieved by using an amount of surface-active agent and protective colloid whose sum is between 1 and 2.5 weight# in relation to the dual charge in the reactor including water.

In the method for producing resins according to the present invention, the catalyst used to carry out the polycondensation is ammonia or an aliphatic amine.

Among the catalysts for polycondensation which one with forde! used within the framework of the present method, examples may be mentioned of ammonia, ethylenediamine, diethylenetriamine, hexamethylenediamine, hexa-methylene tetramine, etc. in an order of magnitude of 0.02 to 0.5 mol and preferably of an order of magnitude of 0.05 to 0, 2

mole for one mole of phenol.

In the method for the production of resins which are the subject of the present invention, an additive is incorporated into the original reaction mixture which can lead to insolubility of the resin obtained before the degree of network formation does not make it infusible, which results in an increase in the meltability of the beads of a final prepared thermosetting resin.

For the sake of simplicity, this additive will be referred to in the following as "meltability additive".

As such additives which are used within the framework of the present method, mention can be made of hydrazine in its hydrated form, the known compound obtained by the action of hydrazine on formol according to the scheme:

piperazine, piperidine, dicyandiamide.

You can also use melamine, aniline, urea as a meltability additive.

According to a preferred embodiment of the present invention, the fusibility agent is incorporated into the reaction environment in an amount of 0.01 mol to 0.2 mol and preferably 0.03 to 0.1 mol per moles of phenol used.

The polycondensation can be carried out at a temperature which should be between -50 and 100°C and preferably between 50 and 85°C, particularly in the case of Tenol.

According to another embodiment which is advantageous

in the present invention, when the desired degree of conversion of menomer to polycondensate has been achieved, the suspension is slightly cooled to ambient temperature while stirring is maintained.

Among the reactive monomers that come into consideration in polycondensation - with formaldehyde - examples include phenol or one of its derivatives such as resorcinol, metacresol, paracresol, certain xylenols etc.

The reactive ionomers are preferably used in an amount of 1 mol of phenol, which is condensed with 1 to 3.1 mol of formaldehyde, which is the same as that used in the form of an aqueous solution or prepared by starting from trioxime tyle which has been depolymerized in advance.

It is particularly advantageous to use 1.2 to 1.8 mol of formaldehyde per moles of phenol.

can be of the order of 1/1.

The uses of heat-curable resins obtained according to the present invention are all such of heat-curable resins by raising the temperature and in particular the following: - binder consisting of a paint or a varnish in a resin solvent, the hardening after evaporation of the solvent being obtained by firing in an oven , - injection or molding by pressure in a hot press, - coating of textiles or paper for lamination or reinforced objects, - crushing and use of powders as a binder for felt of mineral or organic fibres, - brake coating when mixed with mainly asbestos fibres, -abrasive coating by "mixing with abrasive particles of a certain size and pressing in heat, -production of panels by mixing with wood waste, -internal enameling of preservative liquids, -concrete by mixing with mineral or fiber aggregates, etc.

It is clear from the description in - the following - that regardless of which method of practice and adopted application is used

methods for the production of heat-curable phenolic resins are obtained which, compared to previously known methods which have the same purpose, offer important advantages, and in particular allow: easy and quick production of a reactive resin

which is less soluble in water than the previously known resins for a lower degree of network formation. It is a very simple separation of the resin with water, which offers a not inconsiderable financial gain compared to previously known methods if one calculates the equipment costs and the necessary energy to expel the water "from a product by distillation f .e.g. under vacuum and the advantage is then that you eliminate distillation or atomization in the heat during which the network formation continues so that it ends up in resins whose properties are no longer what was originally sought. You also get pearls of reactive resins or practically anhydrous non-reactive resins^ while the amount of water existing in these 'beads is always less than 1 weight#.

The invention shall be explained in more detail with help

of some examples:

Example 1. (Previously known).

9^0 g of phenol is added to 19^5 g of 36#-ig formol. The mixture is introduced into a reactor which is kept at 50°C where continuous stirring is carried out at 100 rpm. 85 g of ammonia with a strength of 22° Beaumé is added in one or more parts. The temperature is kept at 75°C, 500 g of water is added and then after 3 hours the condensate separates in two phases. When this step has been reached, the suspension is formed by the addition of 4 g of "Noeconol 90F" (sodium dodecyl-benzenesulfonate) and 20 g of "Tylose VHR" (carboxymethyl cellulose) which are trademarks of such suspending agents as mentioned above. After a further three hours at 75°C, it is cooled and spherical beads of phenolic resin are separated which are washed, rinsed and dried. The beads obtained have an average grain size of 0.5 mm in diameter. They are infusible and illustrate well the method of preparing a non-reactive phenolic resin by polycondensation in suspension in the absence of fusibility constraints.

These beads can serve as filling material or aggregate for traditional materials such as cement, plaster,

etc.

Example 2.

At a temperature of 50°C, 1645 g of 25.5 g of formol, 93 g of aniline and 9 g of phenol are introduced into a reactor. 60 g of ethylenediamine is then added in at least two portions. The temperature rises to 75°C and is held at this temperature. After 75 minutes, 1 g "Noeconol 90 F" and 5 g "Tylose VHR" are added. After 3 hours of condensation, spherical beads with a diameter between 1.25 and 2 mm are separated from the environment. • Place 100 g of these dried pearls in a bowl and put the whole thing into an oven heated to 170°C. After 15 minutes, a compact and cohesive mass of thermosetting phenolic resin is obtained, which shows the phenomenon of melting and reactivity.

Example 3-

282 g of phenol, 3^5 g of formol, which is 36$-ig, and 37.8 g of melamine are introduced into a reactor at a temperature of 50°C. The temperature is brought to 75°C and 513^ g of ammonia with a concentration of 22°B is added in three portions. The temperature rises and stabilizes at 80°C.

After two hours of condensation, a solution of 1 g of "Noeconol 90F" and 4 g of "Tylose VHR" in 150 g of water is added. After five hours total time for condensation, beads with an average diameter of 1.5 mm are obtained. These beads are fusible and can be used as a binder or glue under the same conditions as melting and burning as in example 2.

Example 4.

9^0 g of phenol, 60 g of urea, 1145 g of formol of a strength of 36%, 150 g of ammonia at 22°B are introduced into a reactor at a temperature of 50°C. and 500 g of water. The temperature is brought to 80°C. After 85 minutes, 1 g "Noeconol 90 F" and 5 g "Tylose VHR" are added. After 4 hours of condensation, fusible beads of 0.3 mm average diameter are obtained which can be used as in the previous example. One can e.g. carry out gluing and reinforcement of mineral or organic fibres.

Example 5-

9^0 g of phenol, 1400 g of water and 15 g of hydrated hydrazine are introduced into a reactor at a temperature of 45°C. 420 g of trioxymethylene are added over 4 minutes, then 150 g of ammonia at 22°B and 500 g of water, and the temperature is brought to 80°C. After two hours of condensation, 2 g "Noeconol 90 F" and 10 g "Tylose VHR" are added. After 4 hours of condensation, egg-shaped beads are secreted, which are characterized by the fact that 95% are rejected on a sieve AFNOR no. 28 (mesh size of 0.5 mm). These beads are meltable and can be used as in the previous examples.

Example 6.

In a glass container of 4 liters equipped with piping with 130 revolutions per minute, a reflux cooler and a thermometer are introduced in order at 45-50°C 10 mol of phenol, then 14 mol of formaldehyde in the form of a 36% aqueous solution. 0.33 mol of pure piperazine are then added, then in sequence 2 mol of ammonia in the form of a 30% aqueous solution in NH-j.

The reaction is carried out exothermically at 85°C with additional heating. After a reaction time of 45 minutes at this temperature, 5 g of "TYLOSE C 300" (carboxymethyl cellulose from Hoechst) and 1 g of "Nocconal 90 F" are added in the form of an aqueous solution in 200 g of water. The reaction continues for 2 hours and 30 minutes and is then cooled. The formed spherical beads with an average diameter of 0.1 mm are separated, washed, aerated and dried. They are fusible.

Example 7_.

In general, the same method as in the previous example is used, except with regard to the fusible material. In the present example, 0.33 mol of tetraformaltriazine is used instead of 0.33 mol of piperazine.

Furthermore, the amount of "TYLOSE C 30.0" (carboxymethylcellulose from Hoechst) and "Nocconal 90 F" is introduced to stabilize the suspension 30 minutes after the temperature has reached 85°C and not after 45 minutes as in the previous example. After adding the two suspending substances, the temperature is maintained for 2 hours and not 2 hours and 30 minutes as in the previous example. The beads obtained in this way are separated as in the previous example and are between 0.4 and 0.8 mm in diameter. These beads are fusible under the conditions described in example 2.

Example 8.

In this example, the method according to example 5 is used with the exception of the substance to achieve meltability which

this time is dicyandiamide. Condensation at 85°C ends after 2 hours and 5 minutes. The neutrality of the reaction mixture is achieved by adding acetic acid in an aqueous 10% solution by weight, then cooling followed by separation of the resin particles as already discussed in the previous examples.

Particles that vary less than 1 mm in size and are fusible are obtained.

Example 9.

The procedure according to example 5 is repeated, using piperidine as an aid to achieve meltability.

After 30 minutes of condensation at 85°C, 500 g of water are added and 15 minutes later 5 g of "TYLOSE VHR" and 1 g of "NOCCONAL 90 F". The condensation lasts for 1 hour and 45 minutes. The mixture is cooled and separation is carried out as in the previous examples.

Spherical beads 0.5 mm to 1 mm in diameter are obtained which can be melted under previously indicated conditions.

Example 10.

The reactor is topped up at a temperature of 45°C

'9"40 g phenol, 16.5 g hydrazine hydrate, 1165 g aqueous, 36% formaldehyde solution, 157.5 g ammonia with strength 22° Baumé

and 800 g of water.

It is heated to 85°C and maintained at this temperature

during condensation. One measures the time that elapses from the moment t when the reaction mixture has reached a temperature of

70°C.

At the moment t + 45 minutes add tea-s 2- g

"N0CC0N0L 90 F" and 10 g of "TYLOSE VHR" and the condensation is continued.

The preparation is repeated several times afterwards

same method, but stops the condensation after different periods of time. Condensation is stopped by cooling to room temperature

turn and the produced pearls are pressed, washed and dried.

The trials have reference numbers 1 to 5, i

the table below and the following condensation times:

The different samples are filled into an apparatus of

type BRABENDER (Plastographe) which is kept at a constant temperature

trip equal to 90°C. The attached curves reproduce the torque measured in the apparatus as a function of the residence time of the sample in the apparatus

rated.

The curves illustrate the meltability of the pearls as

function of the condensation time.

Claims (4)

1. Process for the production of fusible beads of thermosetting phenolic resin, whereby an aqueous solution of formaldehyde and phenol or a phenol derivative in one molar form keep formaldehyde to phenol between 1.0 and 3.1 subject to catalytic condensation using ammonia or an aliphatic amine in a ratio of 0^02 to 0.5 mol of catalyst to 1 mol of phenol used at a temperature between 50 and 100°C ., until an insoluble resin is formed, characterized by the fact that 0.01 to 0.2 mol per moles of phenol of a nitrogenous compound selected from the group consisting of hydrazine, tetraformaltriazine, piperazine, piperidine, dicyandiamide, melamine, urea and aniline, and that the formed insoluble resin present as droplets is stabilized by the addition of a suspending agent, after which the reaction mixture is cooled at condensation is finished and the formed beads are separated. 2. Method according to claim 1, characterized in that the amount of nitrogen compound that is incorporated into the reaction mixture is between 0.03 and 0.1 mol per moles of phenol used. 3. Method according to claim 1 or 2, characterized in that a mixture of an alkali alkyl aryl sulphonate and carboxymethyl cellulose is added as suspending agent. 4. Method according to claim 1, characterized in that hydrazine or tetraformaltriazine.