DE2047096A1 - Foamable plastic - Google Patents

Description

Rohm & Haas

Darmstadt · .- ■ <■% «-» / - »

Pac.Dr.Hh / Os ■

Foamable plastic

Rigid foams based on polyacrylimide or polymethacrylamide are known from British patents 1045229, 1085960 and 1141764. Their excellent properties are described in a detailed presentation by P. Bauer (Kunststoffrundscnau, Volume 17, p.165; 1970). They werdera from copolymers of acrylic or methacrylic acid with the nitriles or amides of these acids and '. optionally further monomers using urea or N, N * -dimethylnarnea produced as a propellant. Carboxyl groups to the copolymer with neighboring nitrile or amide groups to imide | when heated to 150 set to 25O ⁰ C, the look. At the same time, the urea decomposes and the gases formed in the process expand the polymer to form a foam. The resulting in the decomposition of the urea, ammonia reacts in part with such carboxyl groups of the copolymer that are i not been converted by reaction with adjacent amide or '''Mtrilgruppen to imide groups. In addition to or instead of urea, other propellants can also be used which decompose with the formation of ammonia or primary amines, such as N, N ^! -Dimethylurea, poraamide or monomethylformamide.

The resistance of the foams obtained to water, aqueous corrosive agents or high humidity is not satisfactory in all cases.

2098U / 1326

The foams are scnrurapferi or they serve or absorb new amounts of water in fiery air, what are the physical properties, such as e.g. the thermal conductivity, or the meonanic Deteriorate resistance properties. It is of course it has now been shown that these undesirable properties iramar occur when the amount of ammonia or ammonia formed during the decomposition of the propellant primary amines clearly deviates from that amount which allows complete conversion of the reactive amines Injection of acrylic or methacrylic compounds required in acrylic or tert-methacrylimide groups is. If the required amount is undershot, then the announced hydroponicity applies to one genome free carboxyl or anhydride groups in the polymer. An excess of ammonia or primary amines leads to hydrolysis of imide groups when exposed to water to form one amide and one ammonium carboxylate Group that are also nydropnil. The amount of propellant used depends however, primarily according to the desired end service or the volume required for it of decomposition gases.

It was then the task to solve the foam joint density To make it variable within advertise limits, but with the polymer composition and the No changes should be made to skimming conditions for a variety of technical reasons. This gave rise to the further task of finding a propellant which, in the event of thermal decomposition, in each Einselfall Eowonl i / or.ade the desired i-ionge

20981 kl 1 326

BAD ORiGINAt

Propellant gas, as well as the stHiiiometrically required ! • .mount of ammonia or primary amines supplies that can be added to the monomer mixture without affecting the course of the polymerization, in which foamable plastic is present in a homogeneous distribution and in the temperature range in which the plastic achieved and in a polymer containing imide groups passes over, disintegrates, but exerts a softening effect until disintegration, not corrosive or plasticizing decay products and after all, easily available and cheap. Bs was found to be a mixture of formic acid

and formamide or homoethy, formamide or urea a

or Ii, K ^f - dimethyl urine meets these requirements.

It is from the French patent specification 1 433 O73 known that one for the production of a z.3. from acrylic or methacrylic acid and an amide of one of these acids built up foamable plastic as Propellant can also be used as urea and formic acid as an additional auxiliary agent. It sets up however, the amount of urea alone according to de / m desired Propellant volume and instead of formic acid can be a A large number of other acids that do not evolve gases,

mainly sulfuric acid, are used »The selection \

the combination of urea and formic acid from the large number of propellants and auxiliaries listed or the use of the combination just as necessary according to the teaching of the present invention Quantity is not suggested or suggested by anything in the French patent specification.

20981 Ul 1326

The invention relates to a schäumharen plastic, which when heated to I50 · to: 250 ⁰ C passes built up from units of acrylic or Methacrylimids rigid foam in a very Odei "for the most part consisting of

1. a homopolymer of acrylic o ^ cter methacrylic acid or a copolymer of these Acids with one another or with the lower alkyl esters, nitriles and / or amides of the aeryl and / or methacrylic acid and optionally other unsaturated, free-radical polymerizable monomers in subordinate quantities,

2. 1 to 20% by weight, based on the homo- or mixed polymer, a propellant,

5. if necessary, further additives, such as dyes, Pigments, fillers, flame retardants or "the like".

According to the invention, the propellant consists of formic acid and, if necessary, so much formamide, monomethylformamide, urea or Ν, Ν ¹ -dimethylurea that the foamable plastic contains about as much amide-bound nitrogen in total that it contains half the sum of the equivalents

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a * polymerisatgetoundenen carboxyl groups, which in the Excess over polymer-bound nitrile groups

"b- polymer ± string-bonded lower allyl ester groups, intends to implement them in imide groups

JLiilägruppen

bound sticks to ff "is one hand that in the acrylamide and ufethftcrylamide units of the MisdipolyDierisates, on the other hand that in formamide, "

itonoßiethylfonaaniidj Hajmstoff (KohlBnsäurediaäaid) or NjN ^f -Dimethyl3aarnstoffhalteit means nitrogen * Polymer-bound carboxyl, nitrile, lower alkyl ester and Araid groups are primarily the functional groups of the monomer units of the acrylic or methacrylic acid and the nitriles, lower alkyl esters Acids included in the homo- or

Copolymer are incorporated. Furthermore, these

Groups also to polymerized units of other έ

unsaturated carboxylic acids, such as the ilalein, ita bait Fumaric acid.

The homopolymerization or copolymerization of the monomers mentioned is advantageously used for bulk polymerization in the usual way, i.e. in a form of glass plates and a sealing cord led around the edge • formed Fiachkammer or in a bag, for example

2096U / 1328

made of cellulose regenerate film or polyethylene terephthalate film, using common initiators such as benzoyl peroxide, Oil auryl peroxide, t-butyl perpivalate, aaobisisobutyronitrile, in the case of the tenipers used for this purpose and polymerization sites carried out.

Upon heating of the foamable plastic to I50 to 25O ⁰ C run simultaneously with the Scnäumvorgang cjno;:. Ical reactions of polymer with the formation of acrylic or I »iethacryr * micieinheiten the formula.

where each R «H or CK-. can be ^ ab. units of this formula result from the reaction of two neighboring monomer units with

a) a carboxyl and a nitrile group

b) a carboxyl and an amide group under Splitting off of water

c) a lower alkyl ester and an amide group with elimination of a lower alcohol.

d) one amide group each with elimination of ammonia

e) one carboxyl or lower alkyl ester group each with simultaneous exposure to ammonia or

i'ietnylai.iin with elimination of water or one .; lower alcohol. 2096U / 132S

BATH ORIGINAL

The in doijUea'ctJori (e) verbuuento ammonia can partly from -] er reaction (d) and partly from the Zo rf all ae. ¹ nitrogen fnaltijen Tr eibr.iiij te! Components originate. As a result of the crfindunjsgemässen limitation of the aiiiaai-tij bound nitrogen, a complete conversion of all carboxyl groups, as long as they do not react according to reaction (a) with Hitler group, as well as all lower allyl ester and aniide groups in the sense of reactions (b) to (e) Inid ^ 'groups mo ^ LICn dai3 onne a Übersenaß of Au: remains noniak or primary Auinen, Vin remainder free NitrilGruppeii the "uasseraufnaiirnefähijkeit or Korrosionsanfälli ^ is Fuei ¹ - kei'G onne importance wesnalb ^a *' groups itril ^ present in beträchtlicnem Überscnuß l can.

The additional properties that occur with an over- or under-watering of air If the foam is calculated up to about 5% by weight, when the foam is formed, it is present as free acid groups or anhydride groups, or if the foam is up to 2% by weight, calculated on the weight of the polymer, of ammonia or ammonia -'lai. ": in removes. A deviation from the exact stoichiometric ratio is particularly harmless for the substance properties if the

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BAD ORfGJNAL

foamable plastic partly made of lower alkyl ester units is constructed, such as those of methyl, ethyl, propyl or butyl acrylate or methacrylate. These units become amide-like due to the blowing agent components or monomer units with Bound nitrogen converted to the corresponding imides, but affect unreacted Aljcylestergruppen thanks to their lack of hydrophilicity that Corrosion behavior and water absorption capacity are not. One can, therefore, in giving an idea of what is required Amide-like nitrogen content is the lower Alkyl ester units at least partially as iner & e monomers not to be converted into the corresponding imide watch.

In proportions of more than 10% by weight , calculated on the finished foam, the stated alkyl esters of acrylic or methacrylic acid significantly reduce the thermal stability of degochromic foam. If high temperature-resistant foams are to be produced, the proportion of unchanged alkyl ester groups is therefore generally kept below 10% by weight. Other monomers that cannot or only with great difficulty convert into aoryl or methacrylic imide units also have a comparable effect on the heat resistance, such as higher esters of acrylic or methacrylic acid, styrene and its homologues, maleic anhydride, vinyl esters and the like,

209814/1326

which is therefore also only in minor amounts, preferably in proportions of not less than 20% by weight of the monomer mixture.

The preferred foamable plastics of the invention do not contain any other monomers in the polymer portion as acrylic and / or methacrylic acid and the nitriles and / or amides of these acids, the proportion of acids can be lOOjJ. In this case the total amount the nitrogen required for imide formation is provided by the propellant. The necessary Propellant amounts are then depending on the content of amide-like bonded nitrogen at amounts between 20 and 40 parts by weight to 100 parts by weight of the monomers. The proportion of formic acid can be quite low.

The need for nitrogen-containing propellant components decreases to the same extent as nitrogen-containing propellant components Monomers are incorporated into the copolymer. The foamable plastics according to the invention contain Amide-like bonded nitrogen only for that part of the carboxyl groups which cannot be reacted with the equivalent amount of nitrile groups in Imidgruppon can übergenen. Preferably do the units of acrylic and / or methacrylic acid more at 50 basic mol; o, based on the polymer ^ from.

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Even if the remaining part of the monomer units is made up exclusively of acrylonitrile or methacrylonitrile or Acrylamide or methacrylamide is formed, an excess of carboxyl groups remains in the copolymer, which is converted into the imide by the nitrogen-containing propellant components.

However, if the carboxyl group-containing monomers make up less than 50 basic moles of the polymer, not all of the remaining ISeXl must be made up of amide-containing monomers, because otherwise there would be an excess of amide-like nitrogen.On the other hand, acrylonitrile or methacrylonitrile can make up the entire remaining portion of the polymer . If the nitrile groups of the polymer are in excess over the carboxyl groups, at least one equivalent of ester groups must be present for each equivalent of amide groups bonded to the polymer. If the content of nitrile groups and amide-bound nitrogen in the polymer is sufficient for complete imidization, the blowing agent no longer contains any nitrogen-containing components, ie only formic acid is used. If, however, the polymer still has lower alkyne ester groups which are intended to be converted into imide groups, half an equivalent of amide-bonded nitrogen per equivalent of ester groups should be provided even if there is an excess of nitrogen.

209814/1320

The blowing agent can already be distributed in the ionoinerene semiscn during the polymerization and thereby causes the formation of a very homogeneously structured substance polymer. However, the blowing agent can also be introduced naturally into the polymer by mixing it with the blowing agent or a suspension or solution of the blowing agent in a suitable liquid, as shown on page 3. Gasoline-containing hydrogen, can swell. In contrast, SiCN form Scnicnten "different Schäunifänijkeit easily in the mass in the absence of the blowing agent. The total amount of blowing agent depends on the desired density of the foam to be produced. Because these jedoen by the Polymerisataufbau and the foam process is concomitantly influenced, this can be the dependence of the foam density of the amount of propellant is not given in a generally applicable manner.

Foamable plastics according to the invention with a high proportion of acrylonitrile and / or methacrylonitrile have the surprising peculiarity that they allow the production of non-combustible foams. For this purpose, the foamable plastic is produced in quantities of at least 2 wt. , Preferably 5 to 25 wt.

BATH ORIGINAL

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acid esters and / or phosphoric acid or pyrophosphoric acid added. The halogen content is preferably between 1 and 10% by weight and can also be, for example, in the form a nuclear halogenated styrene, such as mono- or tribromostyrene, or a halophenyl ester of the acrylic or methacrylic acid in the foamable plastic be introduced. It is advantageous for the properties of the foams obtainable in this way if the Nitrogen used to form the methacrylimide groups wholly or for the most part from units of acrylic or methacrylonitrile and amide-like bonded Nitrogen is used in the smallest possible amount. This can be said of the flame-retardant Reaching foams all the more easily than surprisingly a comparatively large excess, up to 10 basic mol- ^ j of the monomer units can go to free, i.e. not converted into imide groups, carboxyl groups without: noteworthy May contain impairment of corrosion resistance. The flame-retardant according to the invention Foams contain with particular advantage in amounts of 0.5 to 15 wt .- ^ based on the copolymer, .Male insaureanhydrid "

For conversion to the Sharon toff sohäumbaren the plastics to a temperature of I50 are heated to 250 ⁰ C. The foam reaches its final volume within an hour and then hardens for a further hour at this temperature. 20981 4/1 326

The foamable plastic ^ can be in the form of large blocks or plates or in the form of granules, if necessary, be foamed in two steps. It should not go unmentioned that the Foam materials available in the specified manner can not only be used directly as a material, but also pulverize them and dissolve them in a solvent such as dimethylformamide and can process the solution into fibers or foils. The structure of the foam allows the shredding very relieved into a soluble powder.

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Example 1 and 2

The amounts of formic acid and formamide given in Table 1 are added to a mixture of 5 parts by weight of methacrylate, initi-il, 65 parts by weight of methacrylic acid and 10 parts by weight of methyl methacrylate. IJacn addition of 0.1 parts by weight of t-butyl perpivalate, and 0.05 parts by weight of dibenzoyl peroxide is this GCRR-isan in a Flacnkammer in 20 hours at about 5G ⁰ CJ and 'j Stuncen. converted at 100 ⁰ C in a clear pole ^ merlsatplatte, when the two-hour heating in a Wärrnesenrank at 200 ⁰ C in a gleicnmäfiigen, colorless, fine-pored foam About Gent.

Table 1 example

Propellant (parts by weight) formic acid formamide

G .naumdi.cnte

1
2

2
6th

5.2 5.2

51 27

Example 3 and 4

In a mixture of 55 parts by weight of methacrylonitrile, 45 parts by weight of methacrylic acid and 5 parts by weight of formic acid, after adding 0 or 10 parts by weight of methyl methacrylate, 0.1 part by weight of t-butyl perpivalate and 0.05 part by weight of dibenzoyl peroxide dissolved. This mixture is in 70 hours at 50 to 60 ° C and 3 hours at 100 ⁰ C in a yellow polymer and by two hours at 200 C in a xirnitzen leicnt gelblicnen foam over (Table 2).

Table 2
example Me tnylme tnacrylate amount
Parts by weight Show dancers
kg / rrP . '■> »
4th 0
10 96
89

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- 15 -

example ^! j ■

We shall have :: 7> 2 parts by weight of methacrylamide, 0.1 parts by weight of t-butyl porpivalate and 0.05 parts by weight of dibenzcyl peroxide in a mixture of 5 parts by weight of metnaccyl nitrile, 65 parts by weight of methacrylic acid, 5 parts by weight Methylmetnacrylat, y, h wt. to ilen formamide and this solution country dissolved 5 wt. parts of formic acid for 20 hours by heating to 50 ⁰ C and ^ -stündiges annealing at 100 ⁰ C in a yellowish polymer of about ο mm thickness placed. This polymer sheet foams on two-hour heating at 200 ⁰ J au a colorless, finely porous mass with a density of 47 kg / ir'auf ·

Example ο

A mixture of 25 parts by weight of methacrylonitrile, 10 parts by weight of acrylonitrile, 65 parts by weight of methacrylic acid, 10 parts by weight of methylene etheroxide, 4.4 parts by weight of formamide and 2 parts by weight of formic acid is possible after adding 0.1 parts by weight. parts of t-butyl perpivalate and 0.05 parts by weight of dibenzoyl peroxide at 5O ⁰ C in 20 hours in a Flacnkammer in a yellowish polymer. This is heated at 100 ° C. for 3 hours and foamed at 200 ° C. for 2 hours. The yellowish uchaum has a diene of 26 kg / m

Example 7 to 10

The parts by weight of phosphoric acid and tris (2, ^ - dibromopropyl) phosphate given in Table J are in a mixture of 40 parts by weight of methacrylonitrile, 6 parts by weight of methacrylic acid, 10 parts by weight of ethyl methacrylate, 5 parts by weight. Parts of maleic anhydride! Dissolved, X 0.1 parts by weight of t-ButylperpivaJ ^ t, C, 05 Ge ;;. Parts of dibenzoyl peroxide and 0.05 wt. Parts of pentaerythritol tetrathioglycolate added and polymerized, the ^ se solution in 45 to 43 hours at ^^ FCI ° C and in 5 to 5 hours at 55 to 65 ⁰ C to give a clear polymer sheet about 20 mm thick.

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BATH ORIGINAL

Heating the sheets obtained in this way in a heating oven at 195 ° C. for two hours leads to brownish foams with reduced Flammability and the rough weights given in table j5.

Table 2 phosphoric acid
Parts by weight Dibromopropyl
phosphate
Parts by weight Volume weight
kg / nr * example 10
10
5
5 10
5
5
2.5 57
66
66
45 7th
8th
9
10

2098U / 1326

Claims (1)

Claims 1. Scnäumbarer plastic which when lirnitzen on i.50 üinneiten to 250 ⁰ C in a gan2 or for the most part from the acrylic and / or Metnacr "lirnids constructed Hartscnaurastoff About Gent, bestenend from 1. a homopoly of Acr; 1- or Metnacr: 1-acid or from a Misonpol ;; merisat this Acids with one another or with the lower ones Alkyl esters, nitriles and / or amides of Acr, 1- and / or methacrylic acid and optionally further unsaturated, free-radically polymerizable Monomers in minor amounts, 2. 1 to 20 wt., -; <3, based on the wt Homopolymer or Miscnpolymerisats, a blowing agent, 2, if necessary further additives, such as dyes, Pigments, fillers, flame retardants]! or similar, marked by this, that the propellant consists of formic acid and possibly so much formamide, monomethylformamide, urea or N, N ^f - dimetn ^ lnarnstoff that the foamable plastic is about 2098U / 1326 remove as much arnid-like stalk toff, uaß to this half of the sum of the equivalents a. polymer-bonded carboxyl groups, the 1; .. Surplus via polymer-bound nitrile groups exist, b. polymer-bound lower alkyl ester groups, if your implementation in Imicigruppen is authorized 1st, C constitutes polymer-bound amide groups. 2. Foamable plastic according to claims 1, characterized cadurcn, that the copolymer contains at least the units of acrylic and / or ketnacrylic acid has an equivalent amount of acrylic or methacrylonitrile units, and that the expandable plastic as a further constituent at least 2% by weight, preferably 5 to 25% by weight, of a phosphoric acid or Contains phosphonic acid esters and / or phosphoric or pyrophosphoric acid. ^. Foamable plastic according to claim 2 characterized by that the copolymer continues to contain 0.5 to 15% by weight of maleic anhydride. 4. Foamable plastic according to claims 2 and 3, characterized in that it contains in amounts of j5 to lü wt. -Fo halogen, preferably bromine. 209814/1326 BATH ORIGINAL