DE1098708B - Process for the production of foams containing urethane groups - Google Patents

Description

GERMAN

It is known from polyoxy compounds, polyisocyanates and water, optionally with use of additives influencing the foam structure, such as activators and emulsifiers, urethane groups to produce foams containing. Polyalkylene glycol ethers are also already used as polyoxy compounds used as they are e.g. B. are accessible by polymerization of alkylene oxides. Preferred a pre-adduct is first made from the polyalkylene glycol ether with an excess of diisocyanates produced free NCO groups, which then at a later point in time with water and optionally the named additives is foamed.

The present invention now relates to an improved method for making urethane groups containing foams by reacting the reaction product containing free NCO groups Polyethers containing hydroxyl groups, a compound with more than two functional groups and Polyisocyanates with water, which is characterized in that initially more than 1 mol and less than 2 moles of a diisocyanate with 1 mole of a polyalkylene glycol ether reacts in the presence of a compound with menials two functional groups, the reaction product is mixed with so much diisocyanate that a total of at least 2 moles of diisocyanate per mole of polyalkylene glycol ether have been used, and the reaction product in a manner known per se with water, if appropriate with the addition of further diisocyanate, foamed.

The polyalkylene glycol ethers suitable for the process include the condensation products of Propylene oxide, butylene oxide or the mixed condensation products of propylene oxide and ethylene oxide or Butylene oxide and ethylene oxide. The mixed condensates can be produced in such a way that at the chain ends a precondensed propylene oxide or butylene oxide is condensed on ethylene oxide. It can also be about Mixed condensates with more or less alternating ethylene and propylene or butylene glycol residues Act. The preferred polyalkylene glycol ethers fall under the general formula

HO (C ₂ H ₄ O) « (C _x HyO) _n (C ₂ H ₄ O) _m H.

in which m is an integer including 0, η is an integer, χ and y = 3 and 6 or 4 and 8. The (C ₂ H ₄ O) groups should not make up more than 10 to 20% of the molecular weight of the polyalkylene glycol ether. The molecular weight of the polyalkylene glycol ether will usually be between 500 and 4000 and more, preferably between 1800 and 2200. The hydroxyl number of the polyalkylene glycol ether is advantageously between 30 and about 225.

Method of manufacture

of urethane groups

Foams

Applicant:

Paint factories Bayer Aktiengesellschaft, Leverkusen-Bayerwerk

Claimed priority:
V. St. v. America 17 July 1957

Dr. Günther Loew, Cologne,
has been named as the inventor

The following diisocyanates should be mentioned as examples of diisocyanates: ethylene diisocyanate, ethylene diisocyanate, 1,2-propylene diisocyanate, 1,3-butylene diisocyanate, 1,6-hexylene diisocyanate, 1,2-cyclohexylene diisocyanate, m-phenylene diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 3,3'-dimethyl-4,4'-diphenylene diisocyanate, 3,3'-dimethoxy-4,4'-diphenylene diisocyanate, S ^ '- DiphenyM ^' - diphenylene diisocyanate, 4,4'-diphenylene diisocyanate, 3,3'-dichloro-4,4'-diphenylene diisocyanate and 1. S-naphthylene diisocyanate.

The modification of the polyalkylene glycol ether with the diisocyanate is carried out in the presence of a compound which has more than two functional groups which can react with at least one of the other two reaction components. As functional groups here are those in question, ^r have reactive W asserstoffatome, thereby allowing reaction with the diisocyanate, but also isocyanate groups as functional groups through which a reaction is possible with the polyalkylenglycol ether.

Examples of polyvalent isocyanates are triphenylmethane triisocyanate and the reaction product of 1 mole of a trihydric alcohol with 3 moles of a diisocyanate called. Compounds with several reactive hydrogen atoms are trivalent and polyvalent Alcohols, amines, amino alcohols and the like. Preference will be given to using alcohols with three hydroxyl groups, z. B. trimethylolpropane or glycerine.

First, more than 1 mole and less than 2 moles of a diisocyanate are used with 1 mole of the polyalkylene glycol ether in the presence of connection with more than

109 508/411

two functional groups and then mixes so much more diisocyanate with the reaction product that a total of at least 2 moles of diisocyanate and 1 mole of polyalkylene glycol ether have been used. The reaction is conveniently carried out at elevated temperatures, at about 100 ⁰ C, until a viscosity in the range 1200 to 1400 cP / 73 ° C is reached. The content of free NCO groups is then / ₀ lying in the range 1 ° to 5 ° and is advantageously about / be 2 ° _0th It has proven to be most advantageous to use a ratio of polyalkylene glycol ether to diisocyanate such as 1: 1.4. Further diisocyanate is then added until the total amount is at least 2 moles per mole of polyalkylene glycol ether. The amount of compounds with more than two functional groups depends on the molecular weight and the number of functional groups in the compound and also depends on the desired physical properties of the foam obtainable from the isocyanate-modified polyalkylene glycol ether by adding water. If trimethylolpropane or glycerol is used, 1 to 5%, calculated on polyalkylene glycol ether, will be sufficient. If more highly functional compounds of higher molecular weight are used, then a larger proportion of polyvalent compounds will have to be used. Conversely, if compounds with a larger number of functional groups are used, the amount added is less than 1%. can even go much lower. The isocyanate-modified polyalkylene glycol ether is prepared under essentially anhydrous conditions. The reaction mixture should expediently contain no more than 0.1% water.

The production of foams from the isocyanate-modified polyalkylene glycol ethers is carried out simply Mixing the same with water, accelerators, emulsifiers and auxiliaries according to known methods, possibly with the help of mechanical equipment, where the foaming can optionally also take place at an elevated temperature. Depending on the amount of water is, the higher "will be the density of the resulting foam. Usually, 0.5 to 10% Use water to foam the isocyanate-modified polyalkylene glycol ether. For very dense Foams will still use less than 0.5% water. In addition, depends on the density of the formed Foam naturally also depends on the NCO group content of the isocyanate-modified polyalkylene glycol ether. In order to be able to coordinate the reaction processes during foaming, preference is given to catalysts especially tertiary amines. DimethylhexahydfoaniHn, Diethylhexahydroanüin, N-methylmorpholine, N-ethyhnorpholine, ester groups containing amines and the reaction product of Ν, Ν'-diethylaminoethanol and phenylisoeyanate. Particularly favorable results are obtained when using tertiary amines of the general formula

uses where R ₁ and R _{2 are} lower alkyl radicals and R _{3 is} an alkyl radical of a higher fatty acid, especially those having 10 to 18 carbon atoms. Dimethylstearylamine, dimethylcetylamine and dimethylsojaamine may be mentioned. At the same time you can still use emulsifiers such. B.- Alkylarylpolyäthersulfonate, use in the foaming.

Compared to the foams commonly used up to now, made from purely linear "pre-adducts", the Process products have less permanent preforming - and better elasticity properties. One has now also the reproducibility of a desired density better than before in the hand. Compared to the off by using a compound with more than two functional groups up to a certain level Foams made with branched "pre-adducts" show the new process products made from "Pre-adducts" are obtained, during the preparation of which the diisocyanate is added in the specified stages , a significantly better permanent set and a significantly reduced decrease in tensile strength and elongation at break with aging in a humid atmosphere, as can be seen from the following table, in the natural only the same density in each case can be compared.

Volume weight, kg / m ³ IA IB 2 A 2 B at Permanent deformation
(DIN 53572),% Decrease in tensile strength
in storage (16 days,
70 ⁰ C, 95% humidity
speed) ° / " 40 28 40 28 30 Decrease in elongation at break
in storage (16 days,
70 ⁰ C, 95% humidity
speed),% 14th 35 2 18th -65 -28 -55 -20

The foam 1 A is made by foaming with water and the usual additives of a "pre-adduct" from 100 parts by weight of linear polypropylene glycol (molecular weight 2000), 36 parts by weight of tolylene diisocyanate and 3 parts by weight of trimethylol

get propane. The molar ratio of polyether to diisocyanate is 1: 4.

The foam 2 A is obtained from the same components and in the same proportions, where but initially only 1.5 mol of töluylene diisocyanate with 1 mol of polypropylene glycol in the preparation of the "pre-adduct" are reacted and only then the remaining 2.5 moles, so that a total of 4 moles result.

The foam 1 B is obtained as 1 A, except that instead of 36 parts by weight of töluylene diisocyanate, 45 parts by weight are obtained Töluylene diisocyanate reacted at once with 100 parts by weight of the polyether, corresponding to a molar ratio from 1: 5.

The foam 2 B is obtained in the same way as 2 A, but using a total of 5 mol of töluylene diisocyanate (like 1 B). The reaction of the polyether with the diisocyanate takes place in two stages, initially 1.5 mol per Mol polyether and then the remaining 3.5 mol are reacted.

example 1

A polyalkylene glycol ether is prepared by condensing propylene oxide and further condensing the polypropylene oxide obtained with so much ethylene oxide that the resulting polyalkylene glycol ether has about 10% (C ₂ H ₄ O) groups and a molecular weight of about 1,800.

100 parts by weight of this Polyälkylenglykoläthers are mixed with 3 parts by weight of trimethylolpropane and 0.02 parts by weight of benzoyl chloride. The mixture is heated to 60 ° C. Then 20 parts by weight

added to an 80:20 mixture of 2,4-tolylene diisocyanate and 2,6-tolylene diisocyanate. The temperature is then increased, and to 90 to 100 ⁰ C the reaction mixture maintained at this temperature until a viscosity of about 1200 / is reached to 1400 cP 73 ° C. Finally, 16 parts by weight of the toluylene diisocyanate mixture mentioned are added.

To produce the foam, 1.5 parts by weight of water and 0.5 to 8 parts by weight of dimethylcetylamm (molecular weight 271) are injected into the continuously flowing stream of the “pre-adduct” for every 100 parts by weight of the “pre-adduct”. The foamable reaction mixture is poured into a mold, resulting in ^{a foam with a density of 0.048 g / cm 3.}

Example 2

2.5 parts by weight of water, 2 to 4 parts by weight of ethyl morpholine and 5 to 7 parts by weight of the technical mixture of tolylene diisocyanate mentioned are added to 100 parts by weight of the isocyanate-modified polyalkylene glycol ether prepared according to Example 1 (called "pre-adduct" there). After thorough mixing, the rescation material is poured into a mold. A foam with a density of 0.032 g / cm ^{3 is formed} .

Example 3

To 100 parts by weight of the isocyanate-modified polyalkylene glycol ether prepared according to Example 1 (called "pre-adduct" there) 3.5 parts by weight of water, 2 to 3 parts by weight of dimethylcetylammon (molecular weight 271) and 10 to 13 parts by weight of the technical mixture of tolylene diisocyanate described in Example 1 are added. The result is a foam with a density of 0.024 g / cm ³ .

Example 4

100 parts by weight of a polypropylene glycol ether (molecular weight 2000) are mixed with 3 parts by weight of trimethylolpropane and 0.02 parts by weight of benzoyl chloride. After warming the mixture to 6O ⁰ C are employed 20 parts by weight of the mixture referred to in Example 1 of tolylene diisocyanate. The mixture is heated further to 90 to 100 ⁰ C and held at this temperature until a viscosity of about 1200 to 1400 cP / 73 ° C is reached. Finally, 16 parts by weight of said mixture of 2,4- and 2,6-tolylene diisocyanate are mixed in.

1.5 parts by weight of water and 2 to 4 parts by weight of dimethylcetylamine are injected into the continuously flowing stream of the "pre-adduct" for every 100 parts by weight. After thorough mixing, the foamable mass is poured into molds. A foam with a density of about 0.05 g / cm ^{3 is obtained} .

Example 5

2.5 parts by weight of water, 2 to 4 parts by weight of ethyl morpholine and 5 to 7 parts by weight of the tolylene diisocyanate mixture specified in Example 1 are added to 100 parts by weight of the "pre-adduct" prepared according to Example 1. After thorough mixing, the reaction mixture is poured into molds. A foam with a density of about 0.03 g / cm ^{3 is obtained} .

Example 6

To 100 parts by weight of the isocyanate-modified polypropylene glycol ether according to Example 4, 3.5 parts by weight of water, 2 to 3 parts by weight of ethyl morpholine and a further 10 to 13 parts by weight of the technical mixture of tolylene diisocyanate mentioned are added. The result is a foam with a density of about 0.025 g / cm ³ .

Example 7

100 parts by weight of polybutylene ether glycol (molecular weight 2000) are mixed with 3 parts by weight of trimethylolpropane and 0.02 parts by weight of benzoyl chloride. The mixture is heated to 60 ° C. and 20 parts by weight of an 80:20 mixture of 2,4-tolylene diisocyanate and 2,6-tolylene diisocyanate are added. The heating is continued until the temperature has risen to 90 to 100 ⁰ C. This temperature range is maintained until the viscosity of the mixture has reached about 1000 to 2000 cP / 73 ° C. At the same time, 16 parts by weight of the tolylene diisocyanate mixture mentioned are added.

1.5 parts by weight of water and 2 to 4 parts by weight of dimethylcetylamm are injected into the continuously flowing stream of the "pre-adduct" for every 100 parts by weight. After thorough mixing, the foamable reaction mixture is poured into molds. A foam with a density of about 0.046 g / cm ^{3 is obtained} .

Claims (1)

PATENT CLAIM: A process for the production of foams containing urethane groups by reacting the reaction product containing free NCO groups from polyethers containing hydroxyl groups, a compound with more than two functional groups and polyisocyanates with water, characterized in that initially more than 1 mol and less than 2 mol a diisocyanate is reacted with 1 mol of a polyalkylene glycol ether in the presence of a compound having more than two functional groups, the reaction product is then mixed with so much diisocyanate that a total of at least 2 mol of diisocyanate have been used for 1 mol of polyalkylene glycol ether, and the reaction product in a manner known per se with water, optionally with the addition of further diisocyanate, foamed. Considered publications:
German Patent No. 954,376;
British Patent No. 769 091. © 109 508/411 1.61