DE1901295A1 - Aqueous emulsions of polyamides and processes for their production - Google Patents

Description

WR Oraoe ft Co. (OB 1995/68 - prio 12.I.I968

A / 13269 - 596?)

Mew York. NY. V.St.A. Hamburg, January 10, 1969

Aqueous emulsions of polyamides as well as processes too

their manufacture

The invention relates to the preparation of aqueous emulsions of high molecular weight polyamides, i.e. with an amine value below 10. The recent development in the field of the use of polyamides for Adhesives and coatings, as well as processing from hot melts, are moving towards the use of high molecular weight polymers, which have greater flexibility, higher tensile strength and greater resistance to solvents and chemicals as low molecular weight polyamides. The main obstacle in the Use of these substances is that they have so far only been in the form of hot melts or in the form of solutions can be used and that, due to their high molecular weight, their melting point is so high that it difficult to use when molten,

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without incidentally decomposing at the same time. AUOH lead local coolings Xn of Schrcalsappari ^ ur easy to solidify and thus stopf in rojn to Ver allowing the use of these substances difficult ^ esfcaltet than is the case with conventional melting. The use of such high molecular weight polyamides would be made much easier if they could be used in the form of emulsions in a dispersant such as water.

Low molecular weight polyamides, i.e. polyamides

high
with a / Smlnwert, can be obtained in the form of stable, aqueous emulsions if they are acetylated with glacial acetic acid. The salt formation is carried out in water at a temperature of 95 to 100 ° C (this temperature is above the softening point of the resin) . On the other hand, it is not possible to emulsify high molecular weight polyamides in this way, which is partly due to their low amine value, due to which only an inadequate amount of acetate groups are introduced, and partly to their well above 100 ° C , ie the maximum temperature that can be achieved in an aqueous system under normal pressure, can be attributed to the softening temperatures.

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Suspensions of high molecular weight polyamides are present by grinding the solid resin in water of a dispersant, but such suspensions have a very large particle size and are therefore unstable and, what is more serious, such emulsions can get through Drying and heating do not produce films.

In the German patent application ?. 1694255 is a procedure described, with the aid of which fUmbildende, aqueous emulsions of high molecular weight polyamides are obtained can be. This process starts from salts of polyamides of low molecular weight as emulsifying agents and the emulsions are made by adding water to a mixture of both high and high polyamides low molecular weight and a solvent for the polyamides and an acid is added and then the most of the solvent is distilled off.

The present invention provides another process for the preparation of film-forming, aqueous emulsions of high molecular weight polyamides which has the advantage that no salt of a polyamide is lower Molecular weight is used. Expressed differently,

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almost the entire solids content of the emulsions can consist of a high molecular weight polyamide.

The invention relates, on the one hand, to aqueous emulsions of alkali complex compounds of high molecular weight polyamides. The invention further relates to the preparation of such emulsions by adding water to a solution of a high molecular weight polyamide in an organic solvent, separating at least a portion of the organic solvent, and emulsifying the remaining mixture in the presence of alkali or by adding alkali after formation the emulsion.

The polyamides which can be used according to the invention have an amine value of less than 10, preferably less than 5 or less, for example from 1 to 4 (the amine value is the amount of potassium hydroxide given in mg, which is equivalent to 1 g of the polyamide). The softening temperature of the polyamides is normally between 100 and 200 ° C, for example around 180 ° C; the specific gravity is 0.925 to 0.980 and the viscosity of the melt at 200 ° C. is 10 to 50 poise (the softening temperatures are determined by the Kugel and Hing method).

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The base used to prepare the complexes can be inorganic or organic. Examples of suitable inorganic alkalis are alkali metal hydroxides and Ammonia. Organic bases or ammonia can be used be, if desired, the "formation of permanent To report salts; strong organic bases, such as = wise primary, secondary and tertiary alkylamines are preferred, especially diisopropylamine,

The mixtures used to make the emulsions or solutions can and will preferably contain a small proportion of one or more additives, in particular compounds that either reduce the viscosity of the solution temporarily or permanently increase »high polyoxyethylene Molecular weights, i.e., having a molecular weight of, for example, 1,000,000 or above are particular useful. It is true that polyoxymethylenes can also have a

Molecular weight less than 1,000,000 use

the find, yet are / to recruit a certain The quantities required are then higher. So with for example a polyoxymethylene with a molecular weight of about 200,000 may be present in a concentration which about 12 times greater than the amount of polyoxymethylene required to achieve the same effect with one

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Molecular weight should be around 1,000,000, since that The presence of large amounts of polyoxymethylene can make the coatings produced from the emulsions water-sensitive, if polymers are used having a molecular weight substantially less than about 1,000,000 are generally avoided.

Instead of or preferably together with the polyoxymethylene, a water-soluble polymer of the vinyl type, for example sodium polyacrylate, or a water-soluble cellulose derivative such as sodium carboxymethyl cellulose or a hydroxyethyl cellulose can be used. It is believed that these agents prevent coagulation of the polyamide particles which are formed in the formation of the emulsion. The use of an agent of this type for replacing a portion of the other "if the generation of a certain viscosity necessary polyoxymethylenes reduces any tendency to" thread formation ¹¹ in the aqueous phase, which know exist otherwise.

Generally speaking, the emulsions can be prepared by adding water, preferably distilled or demineralized Water, to a solution of the polyamide, removing some or all of the solvent by distillation and adding

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the base at a certain stage up to or after the actual formation of the emulsion are generated. It is however, preference is given to non-volatile bases, for example Alkaliraetallh ^ i.roxyde before the actual formation of the Add emulsion. Like that? e.g. potassium hydroxide or sodium hydroxide advantageously during the dissolving stage to be inflicted; this can conveniently be done by adding the polyamides to an alcoholic alkali solution take place. On the other hand, volatile bases such as ammonia have to be added after the distillation. Alkenols and mixtures of alkanols have proven to be suitable solvents for the polyamide and it is in any case preferred to use a solvent that is readily distilled either alone or as an azeotropic mixture with water: lets run off. Thus, lower alkenols and mixtures thereof are preferred. Generally have Xsoproparol and n ~ propanol have proven to be particularly suitable, while n-butanol can also be used, but is less cheap. Methanol and ethanol can replace a smaller portion of the propanol, but they are alone generally not practically useful. So can Polyamides with lower molecular weight and softening temperatures up to about 112 ° C up to 20 $ of the ISO ~ or

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n ~ propanol by replacing methanol or ethanol "- but with significantly higher softening points, the maximum usable proportion of methanol or ethanol is lower, for example 10 $ _o

If the base is added to the emulsion already formed, then a polyoxymethylene should be used as described above be present during the distillation.

The polyamide content of the emulsion can vary within a wide range, for example between 10 and 50 % (based on the free polyamide); Polyamide contents from about JO to 40 # are suitable for most applications. If the viscosity of the emulsion initially obtained is too high for a particular application, it can be diluted with water.

Various agents can be added to the emulsion to modify its properties. Example catfish can be yours Already very good shelf life can be increased even further by adding a soap and / or their activity

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can be improved by adding one or more epoxy resins or epoxidized oils, such as epoxidized soybean oil or linseed oil as described in German patent application P1694355 .- ^; plasticizers can also be added »

Although various well-known working environments can be used to develop » removal of the solvent from the mixture can be used, but it is generally particularly advantageous « to carry out a steam distillation, because this not only part of the water required for the emulsion to be produced is obtained, but more than that at the same time an automatic mechanical movement of the mixture is achieved and thus the setting of a constant temperature in the reaction vessel is facilitated

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The emulsions can be used for the known applications of Polyamides are used, e.g. as adhesives or for the production of coatings «which in general melted into a continuous film by heating. You can apply «e.g. a metal» to a substrate surface or a fabric can be applied in a conventional manner, such as by rolling, brushing or knurling.

Polyamides of the type used in the context of the present invention are known and available on the market, e.g. under the trade names "Versand.d" and "Versalon". "Versamlde" are created by condensation of polymeric fatty acids, as can be produced from naturally occurring glycerides, e.g. from linseed, cotton yarn or soybean oil, with polyalkylene polyamines, such as ethylenediamine, diethylenetriamine or trimethylenetetramine shown. The representation is described in U.S. Patent 2,726,570, "Versalone * are probably condensation products of polymeric fatty acids of a similar type with amines of a more complex structure.

The following examples are intended to provide a more detailed explanation of the invention:

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Example I.

The polyamide used had an expectation of less than 2p has an acid value of less than 2, a & i> ezl f ical Geuiohfc from 0.925 to 0.975 and a softening täsiperatw of 170 to 180 ° Cj it is under the designation Verseion 1X75 in trade.

100 g of this polyamide were in 100 ml n »PropaEio3. solved and 1 g of a polyoxymethylene with a molecular weight of 6 χ 10 and 6 g of a sodium molar polyacrylate solution (4 # pesticide content) a viscosity; 2000 ep were added to the solution. Bie Misihur.g was touched and heated until all of the polyamide had dissolved. 200 mJ of distilled water were added to the boiling solution at a rate of 5 ml per minute added. The polyoxyethylene swells in the alcohol " whereby the viscosity of the solution increases and coagulation of the polyamide particles during the precipitation by the added water is prevented. (Flexibility of the Solution is further increased at the beginning by the fact that the polyamide becomes increasingly less soluble).

After adding about 50 ml of water, the viscosity of the solution began to decrease. After adding 100 ml of water 100 ml of a water / alcohol azeotrope were distilled off, where the rate of distillation is roughly based on the addition »

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speed of the last 100 ml of water was limited. Distilling off the water / alcohol azeotrope before adding all of the water had two advantages, viz on the one hand the shortening of the total time required to produce the emulsion and on the other hand the maintenance of a sufficiently high viscosity of the mixture to prevent coagulation of the polyamide parts, which otherwise could possibly have taken place.

The amount of alcohol in the distillate was determined by determining the specific gravity and was pretty much exactly that for. the azeotrope to be expected, namely 71 ί> alcohol: 29 % water. After separation of ~,; 00 ml of azeotrope, the residue is diluted with water and the emulsifying polyamide tends to foam strongly. It appears that the alcohol remaining in the emulsion is strongly associated with the polyamide particles, so that it is difficult to completely remove it. For this reason, only 100 ml of distillate were separated off.

At this stage the mixture consisted of an emulsion with a solids content of 34%, a water content of 57.9 % and an alcohol content of £ 8; it was darkly colored and lumpy. The emulsion was then processed further with a Greaves stirrer or in a Silverson emulsifier, in both cases a white emulsion

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sion was generated. To the stirring mixture was added 10 ml of 0.880 ammonia, whereby a Emulsion was obtained, which is much easier distributed and that was stable. By heating the emulsion, e.g. after applying it in the form a coating on a substrate, became the Ainitoniak released and the polyamide returned to its original shape. The distillate could be recycled to dissolve the next polyamide batch after the n-propanol content has been replenished to 100 ml had been.

Example 2

The same polyamide was used as in Example 1. 100 g of this polyamide were dissolved in 100 ml of normal propanol dissolved containing 0.25 S potassium hydroxide and 6 g of the above-mentioned sodium polyacrylate solution. The mixture was refluxed until all of the polyamide had dissolved, whereupon 200 ml of distilled water with were added at a rate of 5 ml per minute. Again, 100 ml of azeotrope were distilled off while the second 100 ml of water were added, followed by the residue with a further 10 g of the sodium polyacrylate solution enriched and in a Greaves mixer or Sllverson emulsifier was emulsified. It is believed, that the structure of the polymer by the addition of the

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Potassium hydroxide is constantly changed, perhaps by salt formation on the terminal cartoxyl residues, but due to the high molecular weight of the polyamide, its properties are not noticeably changed. If desired can the emulsion by adding 10 ml of 0.880 ammonia during the formation of the emulsion as in Example 1 can be made even thinner.

In a further experiment, 0.5 S was potassium hydroxide used with similar results.

Example 3

Example 2 was repeated, with 10 ml of diisopropyl « amine was used instead of potassium hydroxide; a similar result was obtained, but the Polyamide was not permanently changed, but practically returned to its original state by subsequent heating Porm could be transformed back.

Example 4

The general working procedure of Example 2 was shown in Repeatedly using the same polyamide but with the potassium hydroxide in the added distilled Water and was not dissolved in the n-propanol and wherein 10 g of the sodium polyacrylate solution at the beginning and another amount was added later

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The emulsion obtained was similar in color and consistency to that obtained in Example 2.

Solutions! In the above example, solutions can be used, for example mixtures of isopropanol and n-propanol with an isopropanol content of up to 20%.

The resulting emulsions are stable indefinitely so long the alkali is present. They can be found in the examples of German patent application P 16 94 355-4 can be examined with similar results.

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Claims (12)

(5963) W.R. Grace & Co. New York, N.Y./USA Hamburg, January 10, 1969 claims 1. Aqueous J £ tmilslon high molecular weight of polyamides with an amine value of less than 10, characterized in that the polyamide is present in the form of an alkali complex. 2. Emulsions according to claim 1, characterized in that that the polyamide in the form of a complex with an alkali metal hydroxide, an ammonium hydroxide or a hydroxide of an organic nitrogen base is present. 3. Emulsions according to claim 1 or 2, characterized in that they are also a high polyoxymethylene Molecular weight and / or a water-soluble polymer of the yinyl type or a water-soluble one Contain cellulose derivative. 4. Emulsions according to claim 1-3, characterized in that they also contain a soap, an epoxy resin or contain an epoxidized oil and / or a plasticizer. 909835 / U97 5. Emulsions according to claim 1-4 "characterized" that the polyamide concentration IO to 50 #. 6. Process for the preparation of a polyaniide emulsion according to claims 1-5 _P, characterized in that water is added to a solution of the polyamide in an organic solvent and at least part of the organic solvent is separated off from the mixture obtained and the mixture is emulsified in the presence of an alkali or add an alkali after the emulsion is formed. 7. The method according to claim 6, characterized in that the solvent is separated off by distillation. 8. The method according to claim 6 or 7, characterized in that that one turns the water into a solution of the Polyamide in n-propanol or isopropanol adds. 9 * The method according to claim 6 to 8, characterized in that a non-volatile before the distillation Alkall adds. 10. The method according to claim 6 to 8, characterized in that that a volatile base is added after the distillation. 909835/1497 BATH ORIGINAL 11. The method according spoke 6 to IQ _0, characterized in that a water-soluble vinyl polymer or a water-soluble cellulose-
derivative qüx »solution added» tez ~ - '~ T ir. distilled to the * solvent. 12. The method according to claim 10, characterized by geicennseish « netp that a polyoxymethylene high I-iolsÄUlargewlchts added to the solution before distillation, IJ. Process according to claim 6 to 12, characterized in that iran does not contain at least part of the
Adding water during the separation of the solvent. ugsisch: cm 909835 / U97 BADORIGtNAL