DE1224033B - Process for the production of solid, open-cell polyurethane foams - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. Cl .:

C08g

German class: 39 b-22/04

Number: 1 224 033

File number: Stl9825IVc / 39b

Filing date: October 10, 1962

Opening day: September 1, 1966

It is known to produce open cell polyurethane foams. The manufacture of such substances consists essentially in that a polyglycol or an alkyd resin with an organic polyisocyanate is converted, resulting in polymers that are chemically characterized by that they contain crosslinkable urethane bonds of a linear type, the hydrocarbon radicals different Contain carbon content and chain lengths through ester, ether or other stable bonds interrupt. Gas is evolved during or after the formation of the polyurethane polymer, whereby the polymer is foamed. Such foamed polymeric products that are im Generally referred to as polyurethane foams, are found extensively in the relevant literature has been described.

It is also known to be on the surface of. articles made of polyurethane foams forming skin that was previously cut off or rubbed off with a foamy skin cellular structure by shortly after the foam reaches its maximum volume has sprayed on a solvent in extremely fine distribution, for example benzene, ethyl acetate, acetone or glacial acetic acid, and then let the foam harden on the surface at room temperature.

To eliminate the solubility of polyurethane foams it has also already become known that the active substances still present in the foam Hydrogen atoms with further enlargement of the molecule through the addition of polyisocyanates or linear ones or to implement weakly branched polyester isocyanates.

In contrast, the purpose of the invention is to create an extremely light foam with a large volume of open cells and sufficient strength or rigidity and a density below 0.04 g / cm ³ through a. economic process. Such a material is particularly suitable for light packaging, which, however, must be sufficiently rigid to support the packaged object. The material can also be used as a filter material.

The invention relates to au! a process for the production of solid, open-cell polyurethane foams with a density below 0.04 g / cm ³ with post-treatment of the foams with organic, swelling compounds and mechanical processing.

The production of such a foam is achieved by using plasticizers as organic, swelling compounds.
open-cell polyurethane foams

Applicant:

Walker Manufacturing Company,

Racine, Wis. (V. St. A.)

Representative:

Dr. KR Eikenberg, Dipl.-Chem. W. Rücker
and Dipl.-Ing. S. Leine, patent attorneys,
Hanover, Am Klagesmarkt 10

Named as inventor:

Norman H. Stark, Mequon, Wis. (V. St. A.)

Claimed priority:
V. St. v. America December 13, 1961
(159 156)

which and after the aftertreatment is crosslinked with organic polyisocyanates or solutions thereof. In this way a structure is obtained which has uniform properties and is able to to allow a large volume of liquid to pass through. So far, the strength of a foam has been smaller than that of smaller ones Apart from changes that were possible due to the choice of starting materials, only the density depends, d. that is, denser foams are stronger and less dense foams are more flexible. Although the filter properties foamed polyurethanes of various densities by aqueous solutions and organic solvents could be improved to soften the foam, it was not possible; Polyurethane foams low density with open cells, which nevertheless produce a high degree of possess structural strength.

Finally, by means of the invention, the foamed polyurethanes currently available in their Cell structure can be modified so that they have an improved or a certain strength and improved resistance to chemical agents if they are harmful to environmental influences, for example solvents, acids, alkalis or oxygen.

According to another known method, the foam cell walls are coated with a hydrophilic Fabric loosened and treated with it, but the softness

609 658/442

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or the strength of the foam remains untreated. For this reason, the known removal of solid particles from liquids as an extra-process is poorly useful with the present process. Examples of the use of the compare, because both solve different problems, products of the invention are air filters for supply and the resulting products are also internal combustion engines, for air conditioning systems, filters. The known method is based on one for liquid or gaseous fuels or for soft foam and in turn results in air cleaning systems, for example for crank foam with the same strength or soft housing ventilation systems of the automotive industry. Sub. The method according to the invention, on the other hand, assumes strength, as the expression is used here, from a soft foam and transforms the load that is required to compress it into a firmer foam that has a low density of around 50% to compress the foam has, because, as already explained above, it has not been possible, for example, from 2.5 cm to 1.25 cm of its original thickness, a foam lent thickness, and which is at least about 0.005 g / cm ^{3 of} low density with sufficient strength target. Solid foams are therefore those that deliver. 15 have a rigidity or strength that is greater

Although just the less dense foam than the average, commercially available

materials because of their lightness as packaging material untreated polyurethane foams with a

z. For example, if they are highly desirable, their density has been less than about 0.04 g / cm ³ .

nevertheless not to be used because of their strength

was low. This disadvantage is obtained by the invention, a polyurethane foam,

corrected proper procedures. "■ * in one or more areas of the foam

If you want to compare the known method and the previous one that is significantly greater than the existing method, that of the rest of the mass can be used. That can be z. B. achieved in favor of the present method that simply the. The effect of the Polyiso ^ · is that it comprises fewer process steps than the 25 cyanate on a certain area of the poly known process. This initially requires urethane foam that is to be treated, the impregnation of the foam with a solution by masking or the like is limited,
a hydrophilic agent, which is followed by the insolubility. Generally speaking, any organic modification of the hydrophilic agent can be followed. Er- polyisocyanate, which is suitable for production according to the invention, on the other hand, is a stiffened, lighter 30 of polyurethanes. Organic polyfoam is simply obtained by this in that a _r isocyanate used, .are generally lightweight foam with an organic poly diisocyanates of the formula
isoeyanat impregnated. So there is no subsequent _ _ ". _ _ -.
Conversion of agent required. The present, ^. ~~ -C = O,
Process is therefore also because it is easier to carry out cheaper 35 in which R is a hydrocarbon radical, inclusive. ^: *. more aromatic, aliphatic or cycloaliphatic

Further details and advantages result from diisocyanates or combinations of these types!

Examples of these in the following description are as follows: Alkylenediiso-

written examples. cyanate, like. z. B. ■ Propylene-l ^ -diisocyanate or

In general, any conventional polymeric poly- 40 polymethylene diispcyanate, such as. B. Ethylenediiso ^ -

urethane foam can be modified to give it increased cyanate, hexamethylene diisocyanate, tetramethylene

To give strength. It is a feature of the invention-, isoeyanate or decamethylene diisocyanate, cycloalky-

that polyurethane foams of any density, e.g. lendiisoeyanate, such as e.g. B. l ^ -diisocyanatocyclohexane,

in the range of about 0.012 to 0.112 or 0.128 g / aromatic diisocyanate such as e.g. B. m- or. p-pheny-

cm ³ , even higher, can be treated in such a way that 45 lendiisoeyanate, 2,6-toluene diisocyanate, p, p'-diphe-

structures result, the much greater strength nyldiisoeyanat, 1,5-naphthylene diisocyanate, 2,4-toluene

as untreated foam. If ylene diisocyanate or 4-chloro-l, 3-phenylene diisocyanate

Urethane foams _: higher density already an anate, or aliphatic-aromatic diisocyanate, such as

sufficient degree of strength for most commer- cial z. B. ρ, ρ'-diphenylmethane diisocyanate or phenyl

have specific areas of application, it turns out in 50 äthandiisoeyanat.

the invention of which is important because triisocyanates are also suitable, for example

cheaper lower density polyurethane foams, those that have isocyanate groups on a trivalent

z. B. carry in the range of about 0.012 to about hydrocarbon radical, either an ali-

0.040 g / cm ³ can be used. Particularly phatic, aromatic or aliphatic aroma *

Favorable starting materials are the polyether radicals, such as butane-1,2,2-triiso-

foams. -. . cyanate, benzene-l ^ S-triisocyanate, diphenyl-2,4,6-tri-

According to the process, the polyurethane foam isocyanate, toluene-2,4,6-triisocyanate or triphenyl material initially in accordance with the methane 4,4 ', 4 "triisocyanate in the USA patent. Polyisocyanates, which 2,961,710 described method treated by corresponding, substituted hydrocarbon number of the interconnected 60 residues, for example monochlorobenzene ^ Aö-triiso cells or to increase rooms by adding the foam. cyanate, derive, can also be used Fabric is impregnated with an agent that the foam- Preferably, the organic ones used expands to weaken the cell walls, whereupon polyisocyanates arylene diisocyanates, i.e. those at the so weakened foam of a mechanical to which each of the two isocyanate groups directly Processing is subjected. The so treated 65 is bound to an aromatic ring. Such open-cell foam is then made by hand- connections are readily available commercially, stiffened with an organic polyisocyanate. are easy to handle and very responsive Foam bodies, which according to this process can be quickly processed both with polymeric polyester and with

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Polyether polyurethane foams. Compounds plasticizer solution was made of open-celled

such as toluene-i ^ -diisocyanate, toluene-2,6-diisocyanate and samples of a polyether foam, which were previously

or isomeric mixtures of these (TDI) are particularly useful in an aqueous alkaline plasticizer solution

suitable and cheaply available. were mechanically processed, with toluylene diiso-

The organic polyisocyanates can be used in the pure cyanate and a plasticizer in the above-mentioned state, in liquid or vapor form, or in the manner described. All samples were made air-dry with a suitable inert solvent in a then at room temperature for more than a concentration range of about 0.5 to 100 Ge 100 hours, with weight percent concentrations below 0.5 Ge of this time being strength measurements by weight percent of polyisocyanate effective, i ° presses are made at regular intervals but are generally not used when a. The open-cell polyurethane foams, essential stiffening effect is to be achieved. those with the polyisocyanate after swelling after solutions that have been treated with more than 50 percent by weight of poly have proven to be considerably more solid isosyanate, can be more desirable than the untreated samples. It has been shown to give a certain flexible foam, which has to be tested to 15 that the strength of the treated product, a maximum strength, proportional to the concentration of the toluene diisocyanate and are used in particular when a solution is used, ie the amount of very hard product required. Understandably- polyisocyanate in conjunction with the polyurethane mode, such products have a slightly lower foam and amount of pre-applied breaking strength than those treated with a more dilute plasticizer, through which the strength-controlled solution of a polyisocyanate. On will .

the most suitable are solutions with 0.5 to 25 weight strength measurements, expressed in the load,

percent of polyisocyanate for the process. Which is required to reduce a standard sample by 50%

like concentrations are sufficient to compress stiffened ones using

To form foam products containing up to 0.6 weight- 25 sample pieces of about 10 x 10 x 2.5 cm made of poly-

percentage of total organic polyisocyanate per urethane foam and a 10x10 cm

Part by weight of untreated foam contained, metal pressure plate carried, bringing the force

what was measured on the weight of the final washed one that has to be expended to get a

Related product. To achieve 50% compression.

"Inert solvent" should be a suitable 3 ° The above experiments clearly showed that a Solvent to be understood that with the open-cell polyurethane foam with certain organic polyisocyanate itself does not react. So that strength can be established by making a poly-sheet Water, aqueous solutions or urethane foam from the action of a plastic hydrogen as well as those organic compounds for a certain period of time, where active hydrogen atoms sit and the 35 is set so that the foam can swell, on what usually as a chain extender in which the swollen product after exposure to a Manufacture of polyurethanes are used, organic polyisocyanates are dried. In the z. B ethylene glycol, hexamethylene glycol, diethylene - use of equal amounts of plasticizing glycol, Adipic acid, terephthalic acid, adipic acid agents is the maximum strength of the treated amide, 1,2-ethanedithiol, hydroquinone, monoethanol- 40 foams directly proportional to the concentration amine or 4-aminobenzoic acid. On the other hand, the polyisocyanate solution, e.g. according to the any of the plasticizers capable of the above definition 0.88, 1.13, 1.44 and 1.87 kg for foamed polyurethanes in a process according to samples that are 60 hours in TDI solutions with Konzender U.S. Pat. No. 2,961,710, as trations of 5, 10, 15, and 20 percent by weight, respectively Solvents for the organic poly-45 were immersed. Higher concentrations of TDI isocyanate can be used. These organic produce stronger foams, e.g. possessed samples, Liquids include both polar and non- those after 60 hours in TDI solutions of 30 and polar compounds, for example aliphatic carbon 40 percent by weight were measured, strengths hydrogen, such as hexane, heptane or octane, of 2.30 and 2.47 kg. It was found that the chlorinated hydrocarbons, e.g. B. chloroform, Me- 5 ° increased strength without noticeable impairment methyl chloride or carbon tetrachloride, ketones, the ability to let through large volumes of air, such as acetone, methyl ethyl ketone, cyclohexanone or can be obtained. Filter made from such a stiff Diethyl ketone, diethyl ether of ethylene glycol, benzene, foam are much easier to produce and Toluene, nitrobenzene, o-dichlorobenzene, tetrachloro are less easily deformed in use, so that ethane, thiophene, dimethylformamide, tetrahydro- 55 there is hardly any risk that the liquid on the furan, dioxane, methylene chloride, xylene, ethylene flows along the edges of the filter. In addition, Trichlorethylene, propylene dichloride, 2-nitro- is available by choosing certain options propane, methanol, ethanol, or isopropyl alcohol. Layer stiffness of the foam new filter die Selection of the solvent depends on the particular mold to find the one with the filter frame Meaning of course from the solubility of the used 60 better contact result.

Polyisosyanates as well as the availability or tensile strength tests on specimens solidified Economics of the solvent from the curse foam showed that an increase in the concentration due to the removal of residual solvent, tration of the solidifying solution has an increased draw the treated foam and that it gives strength as long as the percentage of polyfree of hygroscopic properties. 65 isocyanate ranges from about 5 to 12.5%

In a swelling test, a set of samples was moved. At higher concentrations the train fails Polyester and polyether urethane foams, strength slowly decreases again to 100% polyester to achieve its lowest value * beforehand by mechanical processing in an isocyanate.

Suitable plasticizers are those that are compatible with the polyisocyanates such as TDI, and plasticizers such as those used for polyester resins, namely cresyldiphenylphosphate, Tricresyl phosphate, dibutyl phthalate, di (2-ethylhexyl) phthalate, diethyl adipate, dibutyl adipate, polypropyl adipate od. The like. In some cases, it may be desirable to use plasticizers that have flame retardant properties.

Polyurethansch'äumstöffe, which with an organic polyisocyanate after plasticization according to the Invention treated proved to be much more resistant to acids and alkali than the untreated fabrics.

Claims (2)

Patent claims: 1. Process for the production of solid, open-celled Polyurethane foams with a density below 0.04 g / cm ³ with aftertreatment of the foams with organic, swelling compounds and mechanical processing, characterized in that plasticizers are used as organic, swelling compounds and crosslinked after the aftertreatment with organic polyisocyanates or solutions thereof. 2. The method according to claim 1, characterized in that that certain areas of the post-treated polyurethane foam with organic Polyisocyanates or solutions thereof are crosslinked. Considered publications: German Patent No. 957 294;
U.S. Patent Nos. 2,900,278; 2,926,398.