DE2414186A1 - PROCESS FOR FOAMING IONIAN COPOLYMERS AND PRODUCTS MANUFACTURED THEREOF - Google Patents

Description

DR. JUR. DIPL-CHEM. WALTER BEIL **

ALFRED HOsTPf'Siira '^ fZ / Q7 /

DR. JUR. DI.Hl.-C: - :: "//» V -.- l VVOLFF *

DR. JUR. HANS O * .. L ⁷ CiL

FRANKFÜRT ΛΜ / ViAiN-HOCHSf APElONSiRASSi: 58

Our no. 19 221 Be / Pb

Esso Research and Engineering Company Linden, N.J., V.St.A.

Process for foaming ionic copolymers and products made therefrom

The present invention relates to a new process for the production of new foamed polymer products with more uniform / cell structure by mixing a polar substance, a propellant and an ionic one Polymers, the polar substance being a preferred plasticizer for the ionic polymer and the aforesaid Propellant is sparingly soluble in the ionic polymer, subsequent exposure of this mixture to a elevated temperature and pressure, causing the blowing agent and the polar substance to be said ionic polymer soak, and foaming of the soaked ionic polymer. The ionic polymer preferably contains between about 0.2 and 20 mole pendant ionic groups, particularly sulfonate groups. In a preferred Embodiment of the present invention is a sulfonated polystyrene polymer with a polar compound and a propellant, which by a soluble

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keltparameter less than 7.9 and a boiling point
is characterized by less than 100 ⁰ C, mixed under increased pressure and temperature, the blowing agent and the polar compound impregnating the sulfonated polystyrene polymer mentioned, and the mixture obtained at atmospheric pressure and a temperature of
foamed at least 105 ° C. Mach cooling is a foam of low to moderate density with uniform cell structure formed by mixing with a low
boiling solvent for polystyrene and a polar substance, removing the low-boiling solvent and repeating the above foaming process again
can be treated.

There are essentially only two major flexible ones
Foam products that are available today in any desired quantity
are available. These are polyurethane foams and soft poly (vinyl chloride) foams. Semi-flexible polyolefin foams are also currently available for special applications
offered in stores, but they are not large-scale products.

Flexible polyurethane foams are produced through a reaction
in which the polymer is formed, foamed and crosslinked. It can be seen that once the cured polyurethane foam has been obtained, the process is irreversible. That is why this is
Product of little or no value, if it is
Requirements are not sufficient.

Foamed polyvinyl chloride (PVC) can be more suitable
Mold can be plasticized to obtain a flexible porous product.

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US-PS 3322 73 ¹ I teaches that ionic polymers, such as partially sulfonated polystyrenes and partially carboxylated polystyrenes, can be used as resins for shaped articles and for the production of foams. The present invention differs from this patent in a number of very important respects. U.S. Patent 3,322,734 teaches that the presence of a small proportion of carboxylic or sulfonic acid groups, when neutralized to a critical degree, allows treatment by conventional plastics processes at elevated temperatures and yet maintains the ionic compounds at ambient temperature. The neutralization takes place by reaction of the acidic component with a suitable metal salt, metal oxide, metal hydroxide or the like to the desired extent. This reference teaches that the acidic form should not be completely neutralized. The neutralization should preferably only be 80 % (ie the metal hydroxide or another compound should only be added in an amount corresponding to 80 % of the stoichiometric amount of the acid present) and should in no case exceed 90% of the stoichiometric equivalent. (At the same time, this patent teaches that a minimum proportion of the acid groups must be neutralized, namely 10%.) It is thus clearly emphasized in this reference that incomplete neutralization of the acidic part is crucial in order to obtain a workable product.

So these products are similar to normal plastic systems, by reacting to elevated temperatures and stress in such a way that the ionic compounds decrease or nearly eliminated. Accordingly, flow occurs and the products can be pressed or foamed, very similar to normal thermoplastics, such as

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-I ₁ -

Polynbyrene or Polyäthyl.i.i. Wean raan from these ionic. Polymers one. Produces foam and raises it to temperatures (for example 100 - 150 ° C), the ionic relationships are reduced and flow occurs a, i.e. the foam, collapses. The dimensional stability such a material at elevated temperatures is innately weak.

The present invention differs from the ionic polymer foams according to the prior art in FIG the following key areas:

(a) The products according to the invention are preferably completely neutralized.

(b) The neutralized compounds according to the invention cannot easily be handled by plastic processing equipment, even at very high temperatures because in the absence of suitable additives the ionic groups adhere very strongly to one another, i.e. the composition is characterized in that ionic domains in a continuous non-ionic Phase are dispersed.

(c) The products described here show, because of their strong connections, little tendency to flow at high Temperatures and iron an unusual and fourth full dimensional stability.

(d) These compounds of the ionic polymers are weakened by the addition of suitable plasticizers which penetrate ionic areas and enable the foaming process.

(e) In the absence of suitable plasticizers for the ionic regions, these substances can be used under practical conditions Conditions cannot be foamed into desired products because of the strong ionic compounds the formation of Eliminate low density foaming and uniform cell structures.

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Ea is from the former S ^ remarks seen i d'', dia chemically crosslinked foams resistance κ £: ■ £ possess η flow at elevated temperatures> *. These advantages, however, are only obtained at the cost of the complexity of the chemical reactions, the procedural problems, the impossibility of reusing waste or re-foaming defective parts, etc.

On the other hand, conventional thermoplastic foams have the advantages of ease of handling, the Reuse of waste and the simplicity of the foaming process. However, all of these systems have the Disadvantage that they have little dimensional stability at elevated temperatures.

The present invention has almost all of the advantages of the thermoplastic foams and shows in that foamed part still has almost all the advantages of chemically crosslinked foams.

It has now been unexpectedly found that new polymer foamed products can be produced by foaming a mixture of an ionic polymer and a polar substance which serves as a plasticizer for the ionic groups present in said ionic polymer. The polar substance can be liquid, gaseous or solid at room temperature and has a dipole moment greater than 0.9 Debye, preferably 1.2 to 5.5 Debye. More specifically, a mixture of an ionic polymer having zwischen.ungefähr 0.2 to about 20 mol $ appended ionic groups, and a polar substance with a blowing agent at a temperature of at least 40 ⁰ C, preferably between 60 and impregnated 3Ö0 ° C and then foamed. The soaking step is therefore carried out at the above temperatures.

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lead, because the blowing agent no is chosen that it is sparingly soluble in egg -.;:;: said ionic polymers. The separating agent has a solubility parameter of

/ Tai \ ^1/2

less than 7 ₃ 9 (- ^ - \ » preferably between approximately

4.5 and 7.7. To make it easier to soak the blowing agent with said polymer at elevated temperatures and pressures and / or shear mixed. When the mixture is liquid under the soaking conditions, shear forces are for relief of familiarization is helpful. The blowing agent is preferably incorporated into said ionic polymer incorporated in the presence of the polar substances described above »The propellant can therefore either simultaneously ground with the polar substance or only mixed in when the polar compound has already been incorporated is. The polar substance is further characterized as being a preferred plasticizer for the pendant ionic groups. The polar substance weakens the physical connections of the ionic polymer and thereby facilitates the flow of the polymer during the foaming process. the The amount of polar substance used should be large enough to destroy the ionic regions of the polymer, but not so great that the excess changes the desired foam properties. In general the amount is in a range of about 0.1 to about 50, preferably about 0.2 to 20 moles Plasticizers per mole of pendant ionic groups. This method is useful for the formation of foams Polymer products in any form known per se and, unlike known foam processes with chemical Crosslinking, the reuse of waste of the foamed polymer. This means that the inventive

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moderate foamed polymers are used again and shrink-wrapped can be.

The re-treatment of waste of the foamed polymer can be carried out in various ways, for example by Dissolving the polymer in a solvent mixture containing a solvent for the polymer backbone and a polar substance, such as an alcohol, for the ionic Areas. This solution can precipitate out to form crude polymer to obtain it, which can then be mixed with suitable propellants and polar substance. the Waste foamed polymer can also be contacted with a suitable volatile polar compound and then treated using thermoplastic processes and then further untreated Polymers are added. The mixtures obtained can contain propellants and other polar ones Substances are added and re-foamed.

Diesel's advantage of reusing waste of the foamed polymer arises from the fact that the inventive foamed products physical crosslinking and not the chemical crosslinking that occurs in the Literature is known. Physical networks result from the interactions of the attached ionic groups. Adding sufficient amounts of a liquid polar substance weakens it Interactions, and the foam flows easily at elevated temperatures and can be used in suitable solvents easily solved. After foaming, the polar substance can if at temperatures below those the ionic polymer settles, is halfway volatile, has been removed and leaves the strong and temperature-resistant physical networking back. In the case of a solid polar substance, part of the polar substance can become after foaming, separate from the polymer by phase separation and

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thereby increasing the strength of the physical cross-links.

This process is extremely suitable for the production of foamed sheets and panels (for example in the extrusion process), foamed pellets and foamed molded articles. You can also use the foamed Plastic products because of their excellent dimensional stability at high temperatures after the foaming process heated and punched or forged into complex foamed objects, simply by one multiple changes between punching and cooling. The cooling of the synthetic foam article below its softening temperature allows the complex shape to be maintained. The blowing agents used in the process of the invention are low-boiling liquids that are converted into their gaseous state by heating.

The low boiling liquids that can be used are those that are sufficiently low Boil temperature to allow foaming. For example, the liquids must be volatile at a temperature at which the polymer flows. When making an artificial foam, the boiling point of the liquids can be particularly important be low and even below room temperature because if it is sufficiently dispersed in the solid plastic polymer they do not readily evaporate until the polymer reaches a temperature at which it flows. Examples of such suitable liquids are alkanes with 4 to 6 carbon atoms, such as butane, Pentane and hexane and fluorocarbons or chlorofluorocarbons with 1 to 2 carbon atoms, such as dichlorodifluoromethane, chlorodifluoromethane, Trifluorochloromethane, 1,1,2-trichlorofluoroethane and the like. Similar substances that are gases at room temperature

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and also carbon dioxide and nitrogen can be used. In any case, that should be low boiling liquids in the ionic polymer be only sparingly soluble.

As discussed above, the propellant should have a solubility parameter of less than 7> 9j, preferably between 4.5 and 7.7. The blowing agent is incorporated into the ionic polymer in the absence of critical amounts of solvents for the polymer backbone that boil at temperatures below the foaming temperature, at elevated temperature and pressure and in the presence of the polar substance. The temperature at which the propellant is incorporated should preferably be above 40 ^° C. and the pressure should be more than 0.4 kg / cm above atmospheric pressure. Preferably the pressure is between 0.98 and 352 kg / cm. The amount of the blowing agent to be incorporated into the ionic polymer is preferably between 3 and 50 parts by weight per 100 parts by weight of the ionic polymer. A sufficient amount of the blowing agent must be used to achieve a foam of suitable density.

Ionic polymers used in the process of the invention are generally plastic polymers. Particular polymers include sulfonated polystyrene, sulfonated tert-butylstyrene, sulfonated polyethylene, sulfonated polypropylene, sulfonated Styrene-acrylonitrile copolymers, sulfonated styrene-methyl methacrylate copolymers, sulfonated block copolymers of styrene and ethylene oxide, acrylic acid copolymers with styrene and copolymers of any of the foregoing. The ionic polymers of the invention also include compositions of the above plasticized backbone polymers. For example, an ionic plastic polymer which,

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if foamed according to the method according to the invention, results in a solid foam, in the backbone in a suitable manner before foaming to be softened to a to yield flexible foam.

The ionic polymers according to the invention preferably contain between approximately 0.2 and 20 mol / s pendants ionic groups. Ionic polymers with approximately 0.5 to 10 mol-? ionic Groups. These ionic groups include carboxyl groups, carboxylate groups, sulfonate groups and phosphonate groups. Sulphonate groups are particularly preferred. Are in accordance with the foregoing some of the most preferred ionic polymers for the production of solid synthetic foams according to the invention sulfonated polystyrenes and polystyrene derivatives, such as, for example, tert-butyl styrene.

The ionic groups contained in the ionic polymers according to the invention are derived from essentially completely neutralized acids or other components. For example, when a sulfonic acid derivative is used as an intermediate agent, enough metal hydroxide is added to neutralize at least 90% of the acid groups. Even this residue of 10 % of non-neutralized acid groups can have a destructive influence on the strength of the physical cross-links resulting from the ionic relationship. For this reason, it is preferred that greater than 98 % of the acidic precursors be neutralized, and it is particularly preferred that all pendant ionic groups be neutralized. It is also possible to add so much basic metal hydroxides or oxides that an over-neutralization occurs, which has no other advantage than to ensure complete neutralization.

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From a practical point of view it is preferred that. this excess of base does not exceed 50 mol the stoichiometric equilibrium of the ionic groups. The neutralizing agents are taken from the group selected from the alkali salts of groups IA, HA, IB and HB of the Periodic Table of the Elements, such as for example sodium hydroxide, potassium hydroxide, calcium hydroxide or magnesium hydroxide or the salts of lead, Tin, antimony and aluminum are made. Ammonia and amines, such as amines with 1 to 30, preferably 1 to 10 carbon atoms, can also be used to neutralize the acidic intermediates for the manufacture of the ionic products are used.

The choice of polar substance is unlimited within the parameters set out above. The polar substance can be a liquid, a gas or a plague at room temperature and should have a dipole moment greater than 0.9 debye, preferably between 1.2 and 5> 5 debye. When the polar substance is a liquid or a solid (in powder form) is at room temperature, it can be mixed with powdered polymers and then elevated temperature and shear (as in compression molding) to uniformly disperse the polar substance in the polymer. The blowing agent is then incorporated into the polymer incorporated at elevated temperature and pressure. However, the polar substance and the propellant can also be used simultaneously be incorporated into the ionic polymer at elevated temperature and pressure.

The polar substance must be sufficiently compatible with the ionic polymer to be in the polymer the influence of elevated temperature and pressure is sufficient

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be uniformly dispersed su. The one to be used Amount of polar substance can vary over a wide range depending on the exact nature of the substance and the degree to which there is a weakening of the physical bonds of the ionic groups of the ionic polymer is desired, fluctuate. In general, however, the amount of the polar substance will be in the range of between 0.1 and 50 moles of the polar substance per mole of the ionic one Groups of the polymer lie.

Preferred polar substances are compounds with hydroxyl, carboxyl, thiol and amino groups. Organic compounds with functional hydroxyl, carboxyl and amino groups with not more than 30 ', preferably not more than 10 carbons per functional group are particularly preferred. Examples of the most preferred polar substances include methanol, ethanol, propanol, butanol, hexanol, decanol, benzyl alcohol, phenylethanol, triphenylmethanol, ethylene glycol, 1,2-pentanediol, glycerin, l, l, l-tris- (hydroxymethyl) -Ä * than, pentaerythritol, acetic acid, laric acid, capric acid, p-toluic acid, oc-phenyl-otoluic acid, 2-bibenzylcarboxylic acid, 3, ^ - dimethylbenzoic acid, adipic acid, sebacic acid, ethylenediamine, 1,6-hexanediamine, 1,2-diaminopropane,!, ^^ »lO-tetrazadecane, tris (2-aminoethyl) amine , iso-hexamethyltriethylenetetraamine and symmetrical cyclotetramethyl-tetraäthylenetetraamine. Polar substances that are solids at room temperature, such as pentaerythritol, capric acid, p-toluic acid, 3, 1-4 -dimethylbenzoic acid, and the like, are also useful for making foams with densities above 0.16 g / cm- ⁵ to near to the bulk density of the polymer. Foams with a higher density (above 0.16 g / cm- *) are desirable for some applications in which the foam has to bear considerable weight, such as in structural applications. If high density foams are desired, of course, in general

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smaller amounts of the blowing agent used than for foams with lower density. Preferably the polar substances have a molecular weight of less than 2000, most preferably less than 1000. As described above, the ionic polymers include the present Invention polymers in which the non-ionic fraction is due to non-liquid solvents for this Portion is plasticized. This type of plasticizer is called a backbone plasticizer because it is that Polymer chain backbone loosens. The purpose of this type of plasticizer is to remove the polymers that normally rigid foams result in changing to foams that are flexible and semi-elastomeric. The use of such Backbone softeners is limited to compounds that dissolve the polymer chain and have a boiling point of at least 150 ° 0 and preferably at least 200 ° C. The backbone softener should also have a boiling point above the temperature of the foaming process, so that it is during of foaming is not lost and should not be at or near the temperature at which the foamed product is should be used, simmer. The backbone plasticizer can influence the cell structure, so that it is necessary is to '"determine the amount of backbone softener, which can be added without resulting in poor cell structure. Special backbone softeners, which can be used for the preferred sulfonated polystyrene polymers include di-n-hexyl adipate, dicapryadipate, Di- (2-ethylhexyl) adipate, dibutoxyethyl adipate, Benzyl octyl adipate, tricyclohexyl citrate, butyl phthalyl butyl glycolate, Butyl laurate, n-propyl oleate, n-butyl palmitate, Dibutyl phthalate, dihexyl phthalate, dioctyl phthalate, Tributyl phosphate, dioctyl sebacic acid esters and mixtures thereof.

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The process according to the invention gives new foamed ones Products. The new foamed products have a density of less than 0.16 g / cm, preferably between 0.02 * ί and 0.12 kg / cirr and include both hard and flexible foams. The new foams produced according to the invention have an average cell volume of less than

_ · Ζ τ.
0.3 x 10 cm, with less than 5 % of the foam volume

—2 ^ 5 cells with a volume greater than 0.5 x 10 cnr having. In general, the foam structure shows closed cells, but foams can also contain open cells.

These foams are new in that, unlike the known crosslinked foams, they can be reused. One re-treatment can easily be done in such a way that the foamed polymer in a suitable Solvent, namely a solution of a low boiling solvent for the backbone and a polar substance, which softens the attached groups, dissolves. The polar substance can be the same as one used in the manufacture of the original product, but it can also be different.

Although the foams of the invention can be re-treated, they have relatively good dimensional stability at temperatures above 100 C, compared with the known polystyrene foams. Compared to polystyrene the foams made from polystyrene with little sulfonation by this process have improved resistance against some common solvents, such as toluene or acetone, and can do with good results be foamed in a temperature range of more than 50 ° C. In addition, the present foams can

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Temperatures between 115 and 150 C without breakdown of the foam can be designed or molded.

In the production of commercially available foams, core-forming agents are very often used as additives, to achieve a very even and small cell structure. These nucleating agents are known to those skilled in the art well known. Very often systems like sodium bicarbonate are used and citric acid or calcium silicate are used. These additives can also be used in those produced according to the invention Foaming can be used. In general, the process of the invention yields without the use of nucleating agents Means foams with low density and uniform cell size.

The preferred ionic copolymers for use in the present invention are sulfonated polystyrenes and their substituted derivatives, can be prepared by the following methods:

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I. ' 0Όρο1γπΐθΓΪ35.υίοη with sulfonate-containing monomers

For example, alkali metal salts of styrene sulfonic acid can be used using free radical initiators with a variety of thermoplastic forming monomers, such as styrene, tert-buty! styrene, chlorostyrene oil and the like, are copolymerized.

II. Direct sulfonation of hoia polymers

Sulfonic acid groups can be converted into aromatic homopolymers. ^: such as polystyrene, polyvinyl, toluene, poly-a-methylstyrene, Poly-tert-butylstyrene oil and the like, can be introduced by direct reaction with a sulfonating agent. Sulphonic acid, such as sulfuric acid and chlorosulphonic acid, can be used. Preferred sulfonic agents are acetyl sulfate, i.e. the mixed anhydrides of acetic acid and sulfuric acid (CH-.COOSO, H) and sulfur trioxide complexes with dioxane, tetrahydrofuran and trialkyl phosphates. Of the trialkyl phosphate complexes, those with a ratio of Trialky! phosphate to SO-, of approximately 1.0 most preferred. The resulting polymer contains sulfonic acid groups that interact with metal oxides, Metal hydroxides or metal salts can be directly neutralized to contain the desired metal sulfonate To obtain polymers. The sulfonic acid containing polymer can also be isolated by precipitation and either in the mass or by redissolving the polymer can be neutralized.

III. Direct sulfonation; the modified polymers

If the desired homopolymers cannot be reacted directly with one another to form the sulfonate-containing substances,

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it is possible to introduce functional groups by copolymerization ₃ which in turn can react with the sulfonating agent. The two particularly desirable functional groups for this purpose are double bonds and aromatic groups, especially phenyl groups. For methods of sulfonating polymers with olefinic unsaturation, see US Pat. No. 3,642,728. The polymers are again neutralized as described above.

A. Copolymers of Aromatic Monomers

Copolymerization of vinyl monomers and relatively minor Fractions of styrene or other vinyl aromatics that react with sulfonating agents result in copolymers with essentially homopolymeric properties suitable for sulfonation. Illustrative examples such copolymers are chlorostyrene ^ styrene, styrene-acrylonitrile, styrene-vinyl acetate and the like. In polymer systems without vinyl groups, an aromatic Group introduced into the polymer through the use of an aromatic containing monomer, such as, for example, phenyl glycidyl ether, copolymerized with propylene oxide. The reactants that suitable for the direct introduction of the sulfonic acid group are the same as above for the direct sulfonation of homopolymers described (II). The polymers are neutralized as described above.

B. Polymers with Unsaturation

Although unsaturation can be introduced into the homopolymers in a number of ways, it generally will to copolymerization with a conjugated diolefin to produce thermoplastic materials fall back with a low level of unsaturation. Suitable comonomers for introducing ^ saturation in vinyl polymers are conjugated diolefins such as butadiene, isoprene, dimethylbutadiene, piperylene

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and non-conjugated diolefins such as allyl styrene. Copolymers könnan ¹ under use of any applicable starting method, such as free radical, cationic, anionic, or coordinated anionic, take place. In polyethers, unsaturation sites can be introduced by copolymerization with unsaturated epoxides such as allyl glycidyl ethers.

The reagents used for the direct introduction of sulfo acid groups in unsaturated thermoplastics are the complexes of SO, with compounds such as Dioxane, tetrahydrofuran, trialkyl phosphates, carboxylic acids, Trialkylamines, pyridine and the like. Particularly Trialkyl phosphate complexes are suitable and the particularly preferred are the complexes of SO- and triethy! phosphate in a ratio of 1: 1. The polymers are neutralized as described above.

IV. Neutralization of sulfur-containing functional groups

Polymers containing sulfinic acid groups can by the air can be easily oxidized to sulfonic acids. Polymers with mercaptan groups can be produced by oxidation of the mercaptan group with a variety of oxidizing agents, such as hydrogen peroxide, potassium permanganate, sodium dichromate, easily converted into sulfonic acid groups.

Ionic polymers according to the invention generally have an average molecular weight greater than 5000, preferably the molecular weight is between 000 and 500,000 and particularly preferably between 000 and 250 000.

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The process of the invention generally comprises the mixture of an ionic polymer with between about 0.2 and 20 mol-? pendant ionic groups with a polar substance, which is a preferred plasticizer for said ionic groups, and a propellant, which has a solubility parameter of less than 7 * 9, the heating of this mixture to a temperature at which the propellant in the gaseous state and cooling to obtain the novel foamed products of the invention. The ionic groups described above are at least 90 %, preferably 98 % and particularly preferably 100 % neutralized. The above mixture contains between 20 and 99% by weight of ionic polymers and 0.1 to 50 moles of volatile polar substance per mole of ionic groups. A low-boiling liquid is used as a blowing agent in a proportion by weight of 1 to 300 % of the ionic polymer. The propellant is incorporated into the mixture in the presence of said polar substance. The mixture is generally heated to a temperature of at least 60 ° C., preferably more than 105 ° C., in order to initiate foaming. The heating of the mixture can be carried out by known methods, such as in a forced draft furnace, in a hot oil bath, or in conventional polymer manufacturing equipment such as a heated extruder. The foaming can be accomplished in a period of about half a second or less to 15 minutes depending on the heating method used. After the propellant has essentially been completely converted into the gaseous state, the foamed product is cooled below its softening temperature to room temperature for subsequent use. The new inventions

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Appropriate foams can be obtained by dissolving them in a mixture a solvent for the non-ionic (backbone) part of the ionic polymer and a polar substance, if necessary, treated again. The solvent can be obtained by heating or by precipitating the Polymers are removed and the ionic polymer is mixed again with a blowing agent and the above Foaming process repeated.

Some particular embodiments of the present invention are presented below. One limitation however, it is not intended that the invention apply to these embodiments.

example 1

A powder of a slightly sulfonated polystyrene with about 3 MoI-? Sulphonation and sodium as the counterion was mixed with phenylethyl alcohol in the proportion of 0.3 ml of alcohol per gram of the polymer. (The sulfonate groups were 100% neutralized.) From this mixture, a 0.132 cm thick cushion was molded at 190 ⁰ C. The pillow was immersed in Preon 12 in a pressure vessel at 58 ° C for one day and at 73 ° C for 6 days. The pad was then removed and foamed by immersing it in silicone oil at 175 ° C for 15 seconds. A good quality cellular structure foam with a density of 0.056 g / cnr was obtained. The mean cell diameter was approximately 15 microns, which is unusually small for polymer foams. For example, 150 microns are typical polystyrene foam diameters; 1000 of the 15 micron diameter cells would fit into a single 150 micron diameter cell. The unusually small cell size and the correspondingly thin cell walls result in a foam that is v / eicher

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and is more flexible than the foams with the same density, that have larger cells and thicker walls. Foams with such a small cell size are beneficial for packaging fragile objects, for thermal insulation and other uses.

Example 2

100 parts of a powder of lightly sulfonated polystyrene with approximately 3 mol% sulfonation with sodium as a counterion was mixed with one part of a fine powder of pentaerythritol (100 % neutralized). A 0.137 cm thick pad was molded from this mixture at 260 ° C. The pillow was immersed in a pressure vessel for one day at 58 ⁰ C and 6 days at 73 ° C in Freon 12th Then the pad was removed and foamed in silicone oil at 217 ° C. A foam with good cell structure of microscopic cell size was obtained which had an average density of 0.03 g / cm3.

Example 3

A 0.102 cm thick pad was formed at 260 ° C. from a powder of a slightly sulfonated polystyrene with about 7 mol / s sulfonate and sodium as the counterion (100 % neutralized). The pad was placed in a pressure vessel in a solution of 0.7 ml of methanol and 10 ml Freon 12 (dichlorodifluoromethane) and heated to 70 ⁰ C. After 5 days, the pillow was removed and foamed in silicone oil at 275 ° C. The foam is hard at room temperature and will not collapse if kept at 125 ° C for half an hour. Unlike conventionally available polystyrene foam, this foam is solvent-resistant.

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While commercially available polystyrene foam at the If the addition of toluene breaks down almost immediately, the foam according to the invention only shrinks slightly. This attempt shows that the foams according to the invention compared to the thermoplastic foams increased heat resistance and Have resistance to solvents, which is due to the: physical crosslinking.

Example 4

100 parts of a lightly sulfonated polystyrene powder with about 3 mole sulfonation and barium as a counterion (100 % neutralized) was mixed with 15 parts of a fine powder of 3,4-dimethylbenzoic acid. A 0.076 cm thick pad was pressed from this mixture at 260 ° C. The pad was immersed in Freon 12 in a pressure vessel at 70 ⁰ C. After 5 days, the pillow was removed and foamed in silicone oil at 250 ° C. A foam with a good cell structure and a density of 0.068 g / cm3 was obtained.

Example 5

Decanol was mixed with 3 MoI-JS sulfonated polystyrene with sodium as counterion (100 % neutralized). The mixture received 0.01 ml of decanol per gram of the polymer. This material was molded into a 0.102 cm thick pad at 180 ° C. The pillow was immersed in a pressure Kessen at 7O ⁰ C in Preon 12th After 2 days, the pillow was removed and foamed in silicone oil at 150 ° C. The foam had a good cell structure and a density of 0.08896 g / cm ³ .

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Example 6

100 parts of a powder of slightly sulfonated polystyrene
with about -3 moles & sulfonation with sodium as the counterion was mixed with 2 parts of a fine powder of pentaerythritol
mixed (the polymer was 100 % neutralized). A
A 0.089 cm thick pad was molded from this mixture at a temperature of 260 ° C. The pillow came in one
Pressure vessel immersed in isopentane at 70 ° C for 2 days. The pillow was then removed and weighed. The weight gain was 13j5 % · The pillow was then in silicone oil
foamed at 245 ⁰ C. The foam had a good cell structure
and an average density of 0.0 * 188 g / cm.

Example 7

A molded 0.0889 cm thick pillow one lightly
Sulphonated polystyrene with approximately 3 mol # sulphonation and sodium as the counterion was immersed in Freon 12 for 3 days in a pressure vessel at 70 ° C (the polymer was 100 % neutralized). Pieces of this cushion were then foamed in silicone oil at 150 ° C and 200 ⁰ C. The foams obtained had densities of over 0.2 g / cm-%. This shows
that the polar substance is required for the production of moderate or low density foams from these sulfonated polystyrene polymers.

Example 8

100 parts of a powder of slightly sulfonated polystyrene
with about 3 mol / S sulfonation and sodium as a counter ion were mixed with 2 parts of a fine powder of pentaerythritol (the polymer was 100 % neutralized). A 0.889 cm thick pad was molded from this mixture at 260 ° C.

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The cushion was immersed in 1,2-dichlorotetrafluoroethane in a pressure vessel ^{at 70 ° C. for 3 days.} The pillow was then removed and weighed. With regard to the propellant, it showed no measurable weight absorption and did not foam noticeably when it was placed in hot silicone oil. This example shows that the blowing agent incorporation conditions must be such that the blowing agent is able to penetrate the polymer mixture. Under the conditions of this experiment, the diffusion rate of this blowing agent into the polymer mixture was too low because of the low solubility and the low diffusion ratios. Higher temperature and pressure should increase both the solubility and the diffusion rate of the 1,2-dichlorotetrafluoroethane into the polymer mixture, so that the uptake of the blowing agent in the polymer mixture should increase and a good quality foam should be possible.

If the temperature is increased to 100 ^° C. and the above experiment is repeated, a foam with a solid core was obtained, which indicates that the penetration rate was too low. It can be seen that at longer times or higher temperatures, 1 ^ -Dichlorotetrafluoroethane can be used as a propellant in the context of the present invention.

Example 9

100 parts powder of slightly sulfonated polystyrene with about 3 MoI-? Sulphonation and sodium as a counter ion were mixed with 2 parts of fine powder of pentaerythritol (the polymer was 100 % neutralized). A 0.889 cm thick pad was molded from this mixture at 260.degree. The pad was immersed in a propellant in a pressure vessel at 70 ° C. After 2 or 3 days the pillow became

409841/0754

_ ₂₅ _ 24U186

removed and foamed in hot silicone oil. The following Results were obtained with the various blowing agents.

Propellant Foaming temperature Density (κ / cnr ⁵ ) butane 245 ° C 0.05 ^ 4 Pentane 200 ⁰ C 0.0864 Chlorodifluoromethane 198 ° C 0.048 1,1,2-trichlorotrene fluoroethane 200 ⁰ C 0.0496 Example 10

Slightly sulfonated polystyrene with about 3 MoI-? Sulphonate groups (compared to the monomeric subunits of polystyrene) with sodium as the counterion were used. (The polymer was 3:00% neutralized.) Pieces of this material was about 1mm thick ml of methanol and 10 ml Freon were placed in a pressure vessel 12 and heated to 70 ⁰ C in 3. After 4 days, the soaked, slightly sulfonated polystyrene was removed from the pressure vessel and exposed to microwave radiation. After placing the material in a drawn 325 watt line in the microwave oven for about half a second, the material foamed. The density in the core of the foam was about 0.1568 g / cm ^, while the piece as a whole had a smooth hard surface which gave the foam an overall density of the foam of about 0.3312 g / cm ^.

Accordingly, the invention can use microwaves as an energy source for foaming a multi-phase one Polymer system in which one phase (the ionic areas) preferably softened by polar means. The polar plasticizers can be the primary microwaves absorbent ingredients, however, additional microwave absorbents can be added to the material be admitted.

409841/0754

Claims (1)

24U186 Patent claims: 1. A process for the production of foamed polymer products with a uniform cell structure, characterized in that a polar substance, a blowing agent and an ionic polymer, the polar substance being a preferred V / calibration * Makers for said ionic polymer and the blowing agent is moderately soluble in said ionic polymer, at an elevated temperature and pressure mixes, whereby the Plasticizers and the polar substance are incorporated into the ionic polymer and the ionic polymer so impregnated foams. 2. The method according to claim 1, characterized in that that the ionic polymer is between about 0.2 and 20 mol # contains pendant ionic groups. 3. The method according to claim 2, characterized in that that the ionic groups are essentially neutralized with a neutralizing agent sulfonate or carboxylate groups derived from acids or other proportions. 4. The method according to claim 3, characterized in that the neutralizing agent (1) ammonia, (2) Amines with 1 to 30 carbon atoms or (3) basic compounds, whose cations belong to groups IA, HA, IB or HB of the Periodic Table of the Elements or lead, Tin, antimony or aluminum can be used. 5- The method according to claim 1 to H, characterized in that the polar substance used is one with a dipole moment of at least 0.9 Debye. 409841/0 7 54 24U186 Is 6. A process according to claim 5> characterized in that as a polar substance, an organic compound having functional hydroxyl, carboxyl, thiol, or amino groups, wherein the organic compound contains no more than 30 carbon atoms per functional group, ^v comparable turns. 7. The method according to claim 2 to 6, characterized in that that the molar ratio of polar substance to pendant ionic groups is between about 0.1 and about 50 amounts to. 8. The method according to claim 2 to 7> characterized in that the pendant ionic groups are neutralized to more than 90%. 9. The method according to claim 1 to 8, characterized in that the ionic polymer between about 20 and 99 wt. of the mixture mentioned. 10. The method of claim 1 to 9 »characterized in that the blowing agent in an amount of about 1 to 300 wt -% .of said ionic polymers is used.. 11. The method according to claim 7 to 10, characterized in that that is the molar ratio of said polar substance to pendant ionic groups between about 0.2 and is about 20. 12. The method according to claim 5 to 11, characterized in that that said polar substance has a dipole moment of 1.2 to 5.5 Debye. 13. The method according to claim 1 to 12, characterized in that the blowing agent is an alkane having H to 6 carbon atoms 409841/0754 2AU186 or fluorocarbons or chlorofluorocarbons with 1 to 2 carbon atoms can be used. I ¹ I. Process according to Claims 1 to 13, characterized in that the ionic polymer is sulfonated polystyrene. 15. The method according to claim 1 to 13, characterized in that that the ionic polymer is a sulfonated styrene-tert-butylstyrene copolymer is. 16. The method according to claim 1 to 15 _3, characterized in that the propellant is a compound with a solubility parameter of less than 7.9. 17. The method according to claim 1 to l6, characterized in that that the polar substance from the group of methanol, decanol, phenylethanol, pentaerythritol, glycerine, Ethanol and 3, ^ - dimethylbenzoic acid is selected. 18. The method according to claim k to 17, characterized in that the neutralizing agent is selected from the group of hydroxides, oxides, carboxylates and alkoxides having 1 to 20 carbon atoms of barium, calcium, magnesium, potassium or sodium. 19. The method according to claim l8, characterized in that the hydroxide or carboxylate as the neutralizing agent of sodium or barium is used. 20. The method according to claim 19, characterized in that that pentaerythritol, decanol, phenylethanol or methanol is used as the polar substance. 409841/0 7 5 4 24U186 21. The method according to claim 1 to 2O _3, characterized in that the mixture contains a nucleating agent 22. The method according to claim 2 to 21, characterized in that that the mixture contains a non-volatile liquid chain plasticizer. 23. The method according to claim 22, characterized in that that a sulfonated polystyrene is used as the ionic polymer and the chain plasticizer is di-n-hexyl adipate, Dicapryadipate, di- (2-ethylhexyl) adipate, dibutoxyethyl adipate, Benzyl octyl adipate, tricyclohexyl citrate, butyl phthalyl butyl glycolate, Butyl laurate, n-propyl oleate, n-butyl palmitate, Dibutyl phthalate, dihexyl phthalate, dioctyl phthalate, tributyl phosphate, dioctyl sebacic acid ester and whose mixtures are selected. 2H. Process according to Claim 23, characterized in that the chain softener used is dioctyl phthalate, dihexyl phthalate or a combination thereof. 25. The method according to claim 22, characterized in that the ionic polymer is a sulfonated copolymer of tert-butyl styrene and styrene and as chain plasticizers a hydrocarbon oil can be used. 26. The method according to claim 25, characterized in that the hydroxide or carboxylate is used as the neutralizing agent of sodium or barium is used. 27. Foamed polymer product with a density of less than 0.16 g / cm, a mean cell volume of 409841/0754 less than 0.3 x 10 - ^ cra and a proportion of cells with a volume greater than 0.5 χ 10 cm ^ of less than 5 % of the foamed volume, containing an ionic polymer with approximately 0.2 to 20 mol SS pendant ionic groups selected from sulfonate, carboxylate and phosphonate groups and at least 90 % neutralized. 28. Product according to claim 27 , characterized in that it has a density of about 0.024 'to 0.12 g / cm ^. 29- Product according to claim 28, characterized in that that it is with (1) ammonia, (2) amines with 1 to 30 carbon atoms or (3) basic compounds of the groups IA, HA, IB or HB of the Periodic Table of the Elements or basic compounds of lead, tin, or antimony Aluminum is neutralized as a neutralizing agent. 30. Product according to claim 27 to 29, characterized in that that the ionic polymer is a sulfonated polymer selected from polystyrenes and copolymers Styrene and tert-butyl styrene. 31 «Product according to claim 27» 28 and 30, characterized in that it contains a neutralizing agent the group of hydroxides, oxides, carboxylates and alkoxides with 1 to 20 carbon atoms of magnesium, barium, Calcium, potassium or sodium is neutralized. 32. Product according to claim 31 »characterized in that it is at least $ 98 neutralized. 33. Product according to claim 32, characterized in that the ionic polymer is sulfonated polystyrene. 409841/0754 34. Product according to claim 27 to 33 _s characterized in that the polar substance has a Dipolrnornent of more than 0.9 Debye and a boiling point of more than 100 ° C. 35- Product according to claim 3 ^, characterized in that that the polar substance in amounts of 0.1 to 50 mol is contained per mole of ionic groups. For: Esso Research and Engineering Company Linden, N.J., V.St.A. Dr. HJ ¹ cm *. Hatchet lawyer 409841 / 0VbA