US1211227A - Process for the manufacture of insoluble condensation products. - Google Patents

Description

rnrrz POLLAK, or BERLIN, GERMANY.

PROCESS FOR THE MANUFACTURE OF INSOLUBL'E UONDENSATION TRODUCTS. I

1,211,227. No Drawing.

To all whom it may concern:

Be it known that I, FRITZ POLLAK, analytical chemist, residing in. Berlin, Germany,

(who'se'post-ofiice address is 107 Kiinig .gratzerstrasse, Berlin, Germany,) have 1nvented certain new and useful Improvements in Processes for the Manufacture of Insoluble Condensation Products; and I do herefuF'as is desirable in practice notwithstanding many valuable properties. The reasons for this want of unqualified success are of various kinds. The chief impediment is the strong phenol odor of many of such prodaqueous solution.

ucts; also their liability in some cases to alter their color suddenly after the lapse of some time; their often small electrical in sulating capacity and their dark naturalcolor. In manufacturing these products phenols'have been caused to act on formaldehyde with or without the employment of pressure in the presence of basic contact agents (see for example British Patent No. 1921/08 and German Patent No. 228,639.)

In this operation it is immaterial whetherthe contact agents are bases, basic salts or salts which separate electronegative ions in In all cases an oily or resinous initial product is formed which upon heating for a considerable time or to a high temperature assumes the form of a thicker mass in polymerizing andfinally becomes completely hard and insoluble. Now it has been observed that the formaldehyde odor has disappeared as soon as the oily mass has formed. It may therefore be assumed that the total quantity of formaldehyde has been entirely combined almost from the beginning. The intermediate prodnets of this reaction (A) are readily soluble in alcohol, ether, acetone and soda lye respectively and they also present considerable solubility in water so that purification there for the purpose of eliminating the contact medium employed is an operation entailing much loss and one which cannot be carried out on a large scale.- Now a lengthy series Specification of Letters Patent.

Patented Jan. 2, 1917.

Application filed August 15, 1912. Serial No. 715,164.

of experiments has demonstrated that such i a purification is necessary in order to obtaln good final products. It has also been found that the bad properties of the condensation products ofphenol and formaldehyde already described are due mainly to the employment of large quantities of basic contact agents in their manufacture; This causes the production of yellow, brown or red coloring agents. Then again phenol salts are formed which dissociate in contact with the air or under the action of an electric current and remain within the mass in its final state, thus giving rise tothe phenol odor and the poor insulating properties of themass. The pure phenol'also assumes a red'color in contact with the air and to this fact as well is attributable the change of color of these products. The elimination of the contact medium by purifying the mass, is, as already explained, a process which does not answer in practice owing to the diminution in the output thereby occasioned. For these reasonsit would appear to be desirable to provide a process which can be carried into practice technically and which leads to improved products.

Now it is known that phenols act upon formaldehyde by the intermediary of acid contact media or without any contact media (see for example German. Patents Nos. 140,552, 17 3,990, etc.) and it is probable that the insoluble final products thus obtained are identical with the basically condensed products. On the other hand there is no doubt that'the initial and intermediate products of the two' processes are entirely differcut one from the other.

By the action of phenols upon formaldehyde inv the presence of acid contact substances'in the first place soluble resins (B) are formed which present the character of shellacsubstitutes. These are readily soluble in alcohol, ether, acetone and soda lye, but (contrary to what, is the case with products of class A) they are insoluble in water. Theydo. not present the property possessed by the products (A) of passing when heated directly into another insoluble state, but separate water and phenol in considerable quantities when further heated. If additional quantities of formaldehyde are caused to act color after a short exposure to light. This phenomenon is attributable to the formation of uncolored or slightly colored leuco substances which on exposure to the air become coloring substances. These leuco substances without contact media, the condensation products obtainable after the elimination of the phenol contained therein, although to some extent air proof, are in such a low state of polymerization that their conversion into the hard final product in treating them with further quantities of formaldehyde solution occupies a very long time. A very lengthy heating or heating to a very high tempera-' ture during the hardening process is, however, not only a disadvantage owing to the long period during which the molds are in use, but also leads to the formation of highly colored products and gives rise to irregularities which make themselves evident in'the form of cracks, gaps, bubbles or great superficial oxidation in the mass. Finally, if in the first or the second process the operation is carried on without contact media at a high temperature under pressure, it is true that the process will be expedited but in this case the final product is irregularly clouded and of dark brown color owing to the presence of water during the process.

The present invention is based upon the knowledge that only such products of this kind, which retain their physical properties unaltered upon being exposed to the air,

have been produced without the employment of contact media of an acid or basic nature. In the first place it has been found that a good yield of soluble resins can be obtained from phenols and formaldehyde without employing contact media, if in place of a formaldehyde solution, those products that are designated polyoxymethylenes, are used.

Broadly speaking two different processes are employed in the manufacture of the polymers of formaldehyde. If an aqueous formaldehyde solution is evaporated to a dry product, an amorphous residuum is left which is commercially termed para formaldehyde and also, although erroneously, tri oxymethylene. This product contains a small percentage of water and. is wholly or partially soluble in hot water. It also dissolves completely or almost completely in cold sodium sulfite solution. According to its quality, its-volatilization point is located between 110 and 165 C. Auerbach and Barschall (Zllz'tteilg. ales Deut. Gem/nullwitsa-mts, 1907) have shown that this product is para formaldehyde. On the other hand by the treatment of the commercial formaldehyde solution containin methylated spirit with dehydrating. me ia (principally concentrated sulfuric acid) a mixture of various anhydrous crystalline bodies is obtained which the outhors referred to alapve term 5 and y polyoxymethylenes. A mixture of (5 and Y polyoxymethylene is marketed as trioxymethylene by the firm of C. A. F. Kahlbaum of Berlin for instance. As I have shown in my copending application Serial No. 701,572, a mixture of {5 and y polyoxymethylene presents the property of reacting with phenols even at a relatively low temperature without the addition of contact agents.

Now it need not be discussed here whether the extremely small quantities of acid which obstinately adhere to many polyoxymethylenes produced by an acid process notwithstanding repeated purification, exert any influence upon the reaction or not. Upon a-nanalysis commercial t and Y polyoxymethylene has given a proportion of 0.0044:% of free sulfuric acid. The present invention relates rather to turning to account the newly discovered fact that without ex ressly adding a contact medium it is possible to manufacture soluble as well as insoluble products from phenols and a mixture of {5 and 7 polyoxymethylenes, said insoluble products being sufiiciently invariable in contact with the air.

The nature of the phenols is also of importance for the process. The purer the phenol the lighter the final product. The lightest, most resistant and purest products would appear to be furnished by synthetic carbolic acid. The addition of small quantities of m and o cresol, resorcin, chlorphenols or other slightly acid substituted phenol derivatives to the carbolic acid, influence the reaction favorably in as much as it takes place more readily. This condition .can readily be fulfilled as the 3537 carbolic acid of commerce for instance contains a small percentage of free cresols, while synthetic carbolic acid generally contains some resorcin. vNow it is advantageous in those cases in which polyoxymethylenes are employed without contact media, to add substituted phenols facilitating the reaction.

The quantity of @aud Y polyoxymethylene, which is preferably employed, is small. The first manufactured, soluble resin-like product is somewhat thick in a cold-state owing to its high state of polymerization. It should not be too thick because even when an excess of trioxymethylene has been used, the mass always contains free phenol dissolved and this must be eliminated if it be desired to obtain durable final products. It is therefore necessary. to wash the mass thoroughly with water. The first washing water should not-preferably be hotter than 40 C. because it has been found that when free phenol is present the emplo ment of hot or boiling water leads to the ormation of a brown coloring substance which cannot be eliminated later. Accordingly the thickening of the mass should not be carried too far. If approximately 20parts by weight of 5 and 7 polyoxymethylene be used to 94 parts by weight of phenol, a product is formed which can conveniently be washed with water at a temperature below 40 C. The washing waters contain but small quantities of substance dissolved, the residuum forms a white, soap-like mass whichis then freed from further quantities of phenol and from water. This is effected by heating the moist mass to temperatures exceeding 105C. This causes the resin to yield up the water that it contains for the greater part and there remains a resinous mass which when purified intermediate product thus obtained, is now ready for use in the manufacture of insoluble resins. The product is subjected to a .further'process which serves to store up a given quantity of para formaldehyde in it and to eliminate the last, traces of free phenol.

The present, high polymerized product re- I acts at temperatures exceeding 100 C. fairly speedily with para formaldehyde in forming insoluble masses or masses soluble with difliculty. These masses, however, still contain free phenol and are cloudy, unless care be taken that the water is able to escape completely. Furthermore the para formaldehydes behave differently. There are para formaldehydes which dissolve completely in the mass and also para formaldehydes which are only partially soluble or quite insoluble. It is therefore simplest to make para formaldehyde by evaporating aqueous formaldehyde solutions and to dissolve the para formaldehyde in the mass while it is formed, in-order to convert it with the mass. Part of the formaldehyde reacts at once with the resin, but the greater part first polymerizes to para formaldehyde before reacting.

It is known that in order to obtain a good yield of para formaldehyde it is advantageous to effect the distillation of the formaldehyde solutions at temperatures at which no sublimation of the para formaldehyde takes place. Para formaldehyde however is sublimed even below 100 C., so that it appears probable that the maximum of residues would be obtained by operating in cacao. This is in fact the case. The uantity of these residues is, however, variable and the proportion of formaldehyde that.

is conducted ina special manner.

' boil.

they contain (100%) varies according to the operative conditions between 50 and 90% of the originally employed quantity of formaldehyde (100% It has, however, been found that these residues are very approximately uniform when the distillation.

The novel process resides in the fact that the formaldehyde solution is maintained at a temperature of from 30 to 40 C. in 'vwcuo (10 to 30 millimeters) until the distillation ceases almost completely. At this stage the condenser must always contain a certain normal quantity of distillate. The residuum forms'a paste which when cold sets into a white slimy mass. This paste of'para formaldehyde can either be manufactured by itself and the soluble resin then added, or the procedure may be such that the formaldehyde solution is evaporated mixed with the resin. In both cases the temperature in the interior of the boiler should be gradually raised as soon as the reaction mixture yields no more water at 3040 C. It will soon be seen that the interrupted distilla- Above C. however considerable quantity of reaction water.'.

The mass inside the boiler then begins to A large part of the para formaldehyde is then chemically combined with the resin, and a small part of the water formed in the reaction is carried off. The last traces of phenol are also carried into the condenser with the water vapors. If the temperature of the bath is very gradually raised to 100 C. the temperature in the interior of the boiler also rises to 88 to 96 C. As soon as this point has been reached, the distillation again ceases almost completely. The mass is then ready for pouring into the molds. 'In this manner a mass of approxifmately uniform quality is obtained.

The evaporating process described can of course also be carried out in the presence of acid, basic or neutral contact agents. The

, eflect of this is only to accelerate the separation of the water and to reduce the hardening temperature somewhat. For this purpose the addition of extraordinarily small quantities of these contact media is sufficient.

Larger quantities of contact media are directly harmful because the mass thickens too readily in the condenser. This effect appears in a highly" disadvantageous manner when the quantity of basic contact medium added, calculated upon the molecular weight of the caustic soda, exceeds 0.05% of the phenol employed. Relatively large quantities of basic contact media, such as employed by other inventors (0.5 to 10% of the phenol employed 'see British Patent No. 1921/1908) are quite unsuitable. Furthermore the object of such an addition is quite dfifierent in the present case. While there it desired to start a reaction between phenols and formaldehyde, here a mass is present which is already a highly polymerized condensation product and contains no free phenol except for exceedingly small traces. It is, however, advantageous where possible to make the addition of alkali (caustic soda for example) not more than 0.02% of the phenol employed. In this case also when the evaporation process is finished the product will have thickened to such an extent that it is no longer possible to use it for casting small objects. Such a process can :only be used in cases in which other substances are-mixed with the mass and especially speedy hardening at temperatures below 100 C. is desired. The addition of contact agents can of course be made during or after the distillation instead of at the beginning, the result being the same.

- The mass manufactured without contact media or with the addition of a minimum quantity of such media is liquid at 100 C.,

with other materials of a solid, semi-solid or li uid nature. The hardening temperature is located between 90 and 130 (3., according to the operative process adopted and lasts for from 2 to 30 hours. If the mass be pulverized in this condition of hardness or when further hardened and pressed in molds at a high temperature, it speedily passes into a solid state. The hardening in the casting molds can also be effected under pressure at a high temperature in which case the period of heating is shortened. It is also possible to dissolve the mass in solvents or to bring it into a fine state of sus .pension and to employ it on materials of the The following is an example of the operative method Example: 360 parts by weight of the purified resin are maintained at a temperature of from 25 to 40 C. with 190 parts by weight of formaldehyde solution of 40% by volume in a vacuum boiler placed in a water bath at pressures below 30 mm. until the distillation of the water ceases. It is then graduall heated to 70 C. until again no further distillation takes place. The water serving for the bath is then gradually heated to boiling point and kept at this temperature until the internal temperature of the boiler has risen to 88 to 95 C. The distillation then ceases almost completely and the mass can be poured into molds. In these molds it coagulates at a temperature of 95 C. after several hours and eventually can be heated to 110-130 G. for the purpose of completely hardening it. If heated higher the mass becomes somewhat brown.

Having now particularly described and ascertained the nature of my said invention and in what manner the same is to be performed, I declare that what I claim is:

1. The method of producing insoluble resins from bodies of the phenolic series and polymerized formaldehyde, which consists in heating a mixture of a body of the phenolic series and Li and y polyoxymethylene, repeatedly washing the soluble products obtained with water, heating to more than 105 degr. 0., adding suitable quantities of formaldehydev solution, concentrating the mixture in cameo at a low temperature, gradually heating to' approximately 95 degr. (1., until no more water is yielded, and hardening the mass by further heating.

. 2. The method of producing insoluble resins from a body of the phenolic series and polymerized formaldehyde, which consists in heating a mixture of a body of the phenolic series and B and "r polyoxymethylene, repeatedly washing the solution products obtained with water, heating to more than 105 degr. (l, in presence of suitable quantities of polymerized formaldehyde soluble in water, concentrating the mixture in mwuo at a low temperature, gradually heat-. ing to approximately 95 degr. 0., until no more water is yielded up, and hardening the mass by further heating.

In testimon whereof I aflix my signature, in presence '0 two witnesses.

' DR. FRITZ PQLLAK. Witnesses;

AUGUST FUGGER,

ADA MARIA Burns.