Pre-polymer with isocyanate terminal group and a flexible polyurethane foam material prepared therefrom

right

Isocyanate-terminated prepolymer prepared from a polyisocyanate containing 4,4'-methylenediphenyl diiocyanate. and a polyol with an average functionality of 2-4, with a hydroxyl equivalent weight of 2200 to 3500- and containing! oxyethylene residues in an amount of 40 to 68% by weight. It is suitable for the production of flexible polyurethane foam.

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Isocyanate-terminated prepolymer, and other polyurethane foam prepared therefrom

I Field of technology

Λ

The present invention relates to an isocyanate-terminated prepolymer and its use in the manufacture of polyurethane products, in particular pure polyurethane foams.

Prior art

Polyurethane foam tactile. they generally prepare, by intimate mixing under reaction conditions, substances containing isocyanate groups with a substance containing groups having hydrogen atoms capable of reacting with isocyanate groups. The isocyanate-reactive hydrogen-containing substances are generally polyols and can be polyether polyols, polyester polyols or, in particular, customary amine- or imine-terminated polyether polyols. The isocyanate is generally an organic polyisocyanate, in particular an aromatic polyisocyanate, such as toluene diisocyanate, or a (poly) methylene-bridged polyisocyanate, such as methylene diphenyl diisocyanate (MDI).

In the preparation of a suitable open-cell polyurethane foam, it is advantageous to use polyisocyanates or poly. isocyanate compositions which contain a significant amount of diisocyanate, thereby reducing crosslinking in the polymer network and thus producing desirable physical properties such as ductility. For the physical properties of the final foam, it is particularly desirable to use 4,4'-methylenediphenyl diisocyanate for the production of the foam.

j When. The use of a methylene-bridged diisocyanate, such as methylene diphenyl diisocyanate (MDX), especially its 4,4 'isomers, can lead to manufacturing difficulties in preparing the foam. The 4,4 * -isomer is a solid at room temperature and therefore, when used in a relatively pure state, it is necessary to produce the foam at elevated temperatures. In order not to have to use elevated temperatures, it is known in the art to work with mixtures of poly and / or diisocyanates containing 4,4' / FI, as disclosed in U.S. Pat. No. 4,256,449. Alternatively, these manufacturing inconveniences are avoided by preparing an isocyanate-terminated prepolymer from 4,4 * -MDI. reduces the tendency to solidify at room temperature or at. low temperatures.

The isocyanate-terminated prepolymer is generally prepared by reacting a large molar excess of a suitable isocyanate with an active hydrogen-containing compound. Such active hydrogen-containing compounds are generally difunctional or trifunctional compounds of different molecular weights. and especially polyether polyols. The choice of active hydrogen compound is made with regard to the desired physical properties of the polyurethane foam. For example, in the preparation of a flexible polyurethane foam known as a cold-cure foam, the use of a polyether polyol containing oxyethylene moieties is desirable. Foams are referred to as “cold-cure”, as it is no longer necessary to remove them from the mold! heating the foam to accelerate its curing. Such cold-cure foams are suitable for handling in a relatively short time without significant risk of deformation.

European Patent Specification No. 22617 describes a process for the production of cold-cure polyurethane compositions; reacts organic! . polyisocyanate compositions comprising a prepolymer prepared by reacting methylene diphenyl diisocyanate with a polyoxyalkylene lendiol or polyoxyalkylene triol containing at least 50 randomly distributed oxyethylene residues and having a hydroxyl equivalent weight of 1000 to 2000. Although such a prepolymer substantially avoids the manufacturing problems associated with 4,4 * -MDI and provides foam-acceptable physical properties, it is desirable to further improve the properties of the foam. ^at}y met more industrial requirements. In particular, it is desirable to improve ductility while maintaining generally acceptable phasical properties, such as the rate of open cells in the matrix.

To this end, the preparation of isocyanate-terminated prepolymers from alternative polyoxyalkylene polyols and their subsequent use in the production of polyurethane foams are investigated; ······ ....... ------- .......... ·. AND

Surprisingly, it has now been found that in order to obtain a foamed substance with improved properties, in particular with improved ductility, it is important to choose a polyoxyalkylene polyol as regards its .. .........

The hydroxyl-equivalent-1-ene-mass-weight is thus reduced to its oxyethylene content.

SUMMARY OF THE INVENTION

™^x;^^ Póďát ^ tčAf ^ ýňáležů⁼is "therefore" isocyanate-terminated_ata prepolymer-containing prepolymer, which can be prepared by reacting a polyisocyanate containing 4,4 * -methylenedigenyl diisocyanate in an amount but no. .... 40% by weight with polyoxyalkylene glycol, the polyol having a mean functionality of 2 to 4 and a hydroxyl equivalent weight of 2200 to 3500 and containing oxyethylene residues in an amount of 40 to 68% by weight.

The invention also relates to. relates to a process for the preparation of a polyurethane foam by intimate mixing under the reaction conditions of the following components;

(A) polyisocyanate compositions comprising an isocyanate-terminated prepolymer, obtainable by reacting a polyisocyanate containing 4,4'-methylenediphenyl diisocyanate in an amount of at least 40% by weight of a polyoxyalkylene polyol, the polyol having a mean functionality of 2 to 48 'hydroxyl equivalent weight nq.q.-b - ?? nfi_Rž_35Q0 and contains oxyethylene residues in the amount = /^ofB / sl cuč 2 niny = o bs ahu j ící -akt i vní ₌(1) a high equivalent weight isocyanate reactive material, (2) a blowing agent and (3) a catalyst to promote the formation of urethane groups.

wherein component (A) is contained in an amount to form 0.6 to

1,3 isocyanate groups active^- hydrogen atom-ve-sl-ožc-e - / 3A

The invention also relates to a polyurethane foam with an average density of 10 to 250 kg / m 2, prepared as described above.

The isocyanate-terminated prepolymer can be characterized by an isocyanate content of 5 to 31% by weight, preferably 10% and especially 15%, more preferably 25% and especially 28 to 31%.

The isocyanate-terminated prepolymer of the invention is prepared by contacting a polyisocyanate with a polyoxyalkylene polyol under reaction conditions. The polyoxyalkylene polyol used in the preparation of the prepolymer has a mean functionality of 2 to 4, preferably 2 to 3, and most preferably a mean functionality of 3. "Medium functionality". means the number of reactive isocyanate sites. per molecule in the case of polyols, hydroxyl groups capable of reacting with isocyanate groups.

The polyoxyalkylene glycol is further characterized in that it has a hydroxyl equivalent weight of 2200 to 3500% and contains oxyethylene residues in an amount of 40 to 68% by weight.

Preferably, the equivalent weight is polyol. 2300, especially 2400 to. 3200 and especially 2800.

The oxyethylene residue content of the polyol is preferably 58% by weight and in particular 60 to 65% and most preferably 64 oxyethylene content. in a polyol outside the stated range, if incorporated into the polyurethane foam, does not lead to the desired characteristics of the obtained foam.

The distribution of the oxyethylene residues in the polyol may be such that one or more oxyethylene blocks are. inside or at the end of the polyoxyalkylene chain, or are statistically arranged, along the entire length, of the polyoxyalkylene chain of the polyol or are located in combination.

The remainder of the polyoxyalkylene chain that does not form oxyalkylene moieties includes oxypropylene moieties, oxybutylene moieties, or mixtures thereof, but especially oxypropylene moieties. ¹Such residues can be obtained by reacting alkylene oxides, propylene oxide or butylene oxide. a common and advantageous source

- 5 oxyethylene residues is ethylene oxide. Residues of other oxides may also be present.

Processes for the preparation of the polyoxyalkylene polyols described above are well known in the art and generally involve basically Z-catalysedicene-α-yl-ene oxide or alkylene oxides, especially ethylene oxide and propylene oxide, to difunctional. , trifunctional or tetra --- - functional initiator for the above^-temperature^-Examples of suitable initiators are difunctional compounds

such as water, ethylene glycol, propylene glycol and their higher axyalkylene adducts, bis- (4-hydroxyphenyl) -2,2-propane and glycol adducts of phthalic anhydride are trifunctional compounds, such as trimethylolpropane, hexanetriol and especially glycerol; and tetra-functional. compounds.;,. as; ethylenediamine α-pentaerythritol-tol.

Preferred initiators for their availability and processability are water, ethyl glycol, propylene glycol, glycerin and their higher oxyalkylene adducts, with glycerol being particularly preferred. . The polyisocyanate used to prepare the polymer comprises essentially methylene diphenyl diisocyanate and polymethylene polyphenyl polyisolyanate and mixtures thereof, wherein the polyisocyanate contains at least 40% by weight of the isomer, 4,4-methylene diphenyl diisocyanate (MDI). Preferably, the polyisocyanate contains by weight. 45, especially 52 and especially 60 to: 98 and most preferably up to 90% 4,4'-MDI. . ·. ......_? If 4,4 * -MDI is not present, the remainder may be polyisocyanate_rHThe prepolymer of the prepolymer may contain: ~ QQu-ž-i-.v.fl.nah-pr-ir-eakc.l_pr-o_D.řlo.ravu prepolymer^{r ==}274^of-MDÍŤ272 '^ MDI ^⁼Polymethyl-enpolyphenylpoly-γ-isoisanolates or mixtures thereof. Optionally, and preferably, the 2,4'-MD1 present does not constitute more than 50% by weight of the isocyanate used for the preparation of. of prepolymer and polymethylene polyphenyl polyisocyanate not more than 50% by weight

According to a preferred embodiment of the invention, the p-oxyoxyalkylphospholyl is preferably reacted, preferably with a triol polyisocyanate, consisting essentially of 4 , 4&gt; ®I_r 2,4 * = MDI and from polymethylene polyphenyl polyisocyanate, the percentage by weight being 4_r4^/-MDI to 2,4 * -MDI, based on the total weight of polyisocyanates contained, is 40:40 to 90: 2, preferably 50; 30 to 75:10 and in particular 50:25 to 65:12, the remainder being polymethylene polyphenyl polyisocyanate

Examples of such preferred polyisocyanates used for the preparation of the prepolymer are mixtures of 4,4'-MDI and 2,4'-MDI in a weight ratio of 70:30. a crude methylene diphenyl diisocyanate composition, such as VORANATE M220 from The Dow Chemical Company and containing polymethylene polyphenyl polyisocyanate / about 57% by weight of_t5 % /, 4 »4 * -MDI / 40% / a 2_r4 * -MDI / 2.51 /. Combining 70; 30

4.4 * -MDI / 2.4^/-MDI with VQRANAT M22Q. in a weight ratio of, for example, 60:40, a polyisocyanate suitable for use in the preparation of a prepolymer containing essentially 4.4 * -MDI (58% by weight), 2.4 * -MDI (19%) and polymethylene polyphenyl polyisocyanate (23%) is obtained. Such a prepolymer, obtained from the preferred polyisocyanate, is also suitable for immediate use in the preparation of a flexible polyurethane foam without, for example, subsequent mixing with other polyisocyanates.

In a less preferred embodiment, the polyoxyalkylene polyol can be reacted with a polyisocyanate consisting essentially of 4,4'-MLI and 2,4'-MDI to form a prepolymer which, if desired, can be blended with other isocyanates, including crude methylene diphenyl diisocyanate. »

In preparing the prepolymer, the amount of polyoxyalkylene glycol relative to the polyisocyanate is such that the resulting prepolymer having the above isocyanate content is prepared. with isocyanate end group. When used in combination with other conventional isocyanate-reactive substances, said polyoxyalkylene glycol is present in an amount by weight; Preferably, the isocyanate-reactive mixture used in the preparation of the isocyanate-terminated prepolymer is preferably present in an amount of at least 10% by weight, preferably at least 20%, by weight of the polyoxyalkylene monol.

Examples of such conventional substances are ethylene glycol. :

propylene glycol and higher molecular weight adducts which _}

are obtained, for example, by reacting an alkylene oxide having 2 to 4 carbon atoms and do not fall into the above-mentioned polyoxyalkylene polyols. Examples of such higher molecular weight adducts are adducts with a molecular weight of 134 to 2000, for example: referred to as VGRANOL P400, VORANOL P101 and VORANOL P2000. always to The Dow Chemical Compahy. As another common. isocyanate. The reactive substances are oxyalkylene,_;~ yé- adducts-- ofigators, jak__; s.hora ^ .uved.eno ^. for β-glyoxyalkylene- ____ glycol.

The prepolymer can be. .prepared ·, for. According to the state of the art, for such methods of preparation. Generally, the prepolymer can be prepared by controlled dosing of the polyol into the isocyanate with stirring. The rate of addition of the polyol to the isocyanate is preferably such that the reaction temperature is maintained, optionally under cooling or heating. 45 to 90 ° C, preferably. 60-80 ° C. .......... .......... ......

The invention also relates to a process for preparing a polyurethane foam by intimately mixing under reaction conditions the following components (A) of the prepolymer described above, optionally as part of a polyisocyanate composition and (B) of an active hydrogen-containing compound comprising (1) with an isocyanate-reactant. k-tivní-ma-t.er-iál_sjzy_s_QkoiL_ekyiyalentoyou_hmot -__ ^ _ ^{— _}^r 'ňos tiy ^^ Z ^ ňadůů vadlů “a ~ /' 3 / —ka tai y-zátor -pro -pro mo.-to vání - yy ^ = ± ^ .- :.

forming urethane groups, component (A) being present in an amount providing 0.6 to

1,3 isocyanate groups on the active hydrogen atoms contained in component (B).

Isocyanate-reactive material of high equivalent density contained in the isocyanate (B), 3 to 8, preferably 2 to 8, preferably 2 to 8, preferably 2 to 4 isocyanate-reactive hydrogen atoms, per molecule and having a mean equivalent weight

3,500 to 3,000 and preferably 8 ° C to 2,500. Typical, isocyanate-reactive, high equivalent weight materials include polyamines, polyester polyols and especially polyether polyols. The polyether polyol may be polyoxypropylene or poly / oxypropylene oxyethylene / polyol or a mixture thereof, such polyether polyols are well known in the art and many are commercially available. available * Poly / oxypropylene-oxyethylene / polyol includes oxyethylene capped / polyoxypropylene polyols and other statistical or block products, obtained by reacting ethylene oxide and propylene oxide with initiators containing active hydrogen atoms.

A suitable, isocyanate-reactive, high equivalent weight material for the preparation of polyurethane foams includes polyether polyols generally diols and triols having a mean hydroxyl equivalent weight of 500 to 3000 and preferably 800 to 2500. Examples of such polyether polyols are the products of The Dow Chemical Company shop ----------- trade name -VGRANOL, for example-VORANOL 4711, VCRANOL 600T

VORANOL. 3322 and VORAHOL 1421. Other suitable polyols include copolymeric polyols of the PHD, PIPA and SAN types, for example VORANOL CP-8020,

The blowing agent contained in component (B) is present in the amount required to form a polyurethane foam with a total density of 10 to 250 kg / m 2, preferably 15 to 25 and especially 30 and especially up to 100 and most preferably 80 kg. · ^.

According to a preferred embodiment of the invention, it comprises a blowing agent. Water reacts with the iocyanate moieties, leading to the evolution of carbon dioxide, with nascent carbon dioxide acting as a blowing agent to form the cellulosic structure of the polyurethane

As a rule, the amount of water contained creates a sufficient blowing capacity to form a foam of the desired density; this amount is 1.0 to 7 parts by weight per 100 parts by weight of component (3), based on the total weight of all the components contained in component (E). Preferably, this amount of water is 2.5, in particular 3.5 and up to &amp; apos; in particular up to 5.5 parts by weight.

The swelling required to form a foam of the desired density can be performed fully using water. However, to achieve a back density. in addition to water 'it can also contain small ..... amount of physical blowing agents. As examples of such physical-blowing agents. reagents.,. which may be included include methylene chloride, trichlorofluoromethyl, dichloro-trifluoro-trifluoromethyl, chlorodifluoro-th; hydrocarbons such as pentar and hexane; and introduced gases such as air, nitrogen and oxide. carbon dioxide.

Suitable catalysts which can be used in the process according to the invention to promote the formation of urethane groups include the tertiary amines of the 8-organometallic compound, in particular the tin compound. Examples of suitable catalysts are used^,n-i-aiia^;new-compounds. · .. -like 4 Λ, N £ điměthýlcy klo- .; ... hexylamine, N, N-dimethylbenzylamine,,, Ν-dimethanolamine, bis (dimethylaminoethyl) ether and 1,4-diazobicyclo [2.2.2] octane; and tin compounds comprising stannous octanoate and dibutyltin dilaurate. Mixtures of amine compounds and / or tin compounds can be used as catalysts in the process.

In the process of the invention, component (A) is present in an amount sufficient to form 0.6 to 1.3 isocyanate groups on the isocyanate-reactive hydrogen content of component (B).

And preferably, the amount of the component (A) is such that it produces 0.8 to. In particular, 1.05 isocyanate groups per active hydrogen atom. The amount of isocyanate contained can also be expressed as an isocyanate reaction index. In this case, the isocyanate group on the hydrogen atom of the reactant is isolated from the reaction group of the isocyanate group. "S ^ -isky an-á-t em -.- ^ = .- ^ == 'jl · nými = common ^ 5ložk5miΐ-which ^ mQhou.bý.bý₁However, surfactants such as siloxanoxyalkylene copolymers, for example the products of the trade name Tegostab of Th. Golschmidt, including B-4113 and B-4690, are preferably present in the process; chain extenders 7 such as ethylene glycol-4-butanediol, diethanolamine, diisopropanolamine and polyamine; fillers; a flame retardant such as melsmin; pigments and bsrvivs.

IQ

The components of the foam-forming mixture may be mixed with each other in any conventional manner, for example using a mixing device known in the art for such purposes. Optionally, non-reactive components may be premixed so as to reduce the number of component streams required for tight mixing.

It is generally preferred to use two-stream systems, with one stream of the stream comprising the prepolymer and optionally any additional isocyanate, while the other stream generally comprises the other components of the reaction mixture not substantially interacting prior to mixing with the isocyanate-containing stream.

The process according to the invention and the isocyanate-terminated prepolymer are particularly suitable for the preparation of polyurethane foams, in particular cold-cure foams.¹*/. ^ANDac foams are suitable for many fields of application, including upholstery, sound and vibration damping and cushioning.

The use of the prepolymer according to the invention in the preparation of polyurethane foams leads to foams which have an increased ductility in comparison with foams obtained using prepolymers known from the prior art.

The following examples illustrate the invention but do not limit it in any way. All parts and percentages are by weight unless otherwise indicated.

Examples of embodiments of the invention _of » .

FFedpolymer is prepared as described below and evaluated by preparing a pliable polyurethane foam using the following polyol formulations. The polyurethane composition is prepared by tightly mixing the isocyanate, before

polymer :, s; polyol using a high pressure foaming machine to obtain a foam.

Polyol formulation

100.00 parts. glycerin-initiated polyoxypropyleneoxyethylene (15 polyethylene) polyol; molecular weight 6000

J y [7 'UXJ-.Li YVKAJ,

0.80 parts of triethylenediamine (33% in dipropylene glycol)

1

0.15 parts of NIAX-A1 catalyst from Union Carbide Co.

0.80 parts of Tegostab B41T3 surfactant from Th Goldschidt Ag

Physical properties of the foam produced, obtained by mixing the reaction masses under conditions of high pressure and introducing the reaction mass into a mold maintained at a temperature. * 5'0 ° C, are listed below. The procedures used for measuring the physical properties are described in the following standards: strength and ductility DIN 53571, deflection and load / CLD / DIN 53577; deflection at indentation / indentation ship ”/ load / ILD / 'DIN 535767 —e- Before polymer .1, ____, ..._____... ^ _______j .. -.

Isocyanate-terminated Fred polymer having iso; The cyanate content by weight, 29% by weight, is by reaction,. 1-1 - ,. 1., -.

parts of polyoxyethylene oxypropylene triol / hydroxyl equivalent weight 2463; oxyethylene content 61%, statistical distribution (with 100 parts of an isocyanate mixture containing 4.4 * -MDI (58%), 2.4 * -MDI (19%) and polymethylene polyphenyl polyisocyanate (23%)).

The polyol is added to the isocyanate mixture with continuous stirring at such a rate as to maintain the reaction temperature! 65-70 ° C. Once all of the polyol has been added, the reaction mixture is stirred at the same temperature for another hour to ensure that the reaction is complete.

The properties of the foam obtained by reacting the prepared prepolymer with said polyol are as follows.

isocyanate reaction index - i - ** - * 4- m .λ _ η 4 = _ wa 3 nX mj_n o Λ ίΛΙ Ί17 ά 1 * 1 I1JLAO W VO ~ UX X ~ w * »* '» * «1 density at pressing / kgm / elongation /% / tensile strength / kPa / CLD / kPa / new

-1— mass ₂-₃

TOČ

ΊΤ0 '

<td> .36,</td><td> 36.</td><td> /_</td>

<td> 44,4’·</td><td> 44,9</td><td> 45,2</td>

<td> 143</td><td> 133 .</td><td> 119</td>

<td> 11.7</td><td> 13.8</td><td> . 181</td>

<td> 3,56</td><td> 4,44</td><td> 6,43</td>

<td> .150-</td><td> -..1.95-</td><td>26j0 ^</td>

- 12 Prepolymer 2

The isocyanate-terminated prepolymer having an isocyanate content of 29% by weight is prepared in the same manner as described in the prepolymer I section by reacting 11.0 parts of polyoxyethylene oxypropylene triol / hydroxyl equivalent weight of 2270; oxyethylene content 59%, statistical, distribution / se. 100 parts of an isocyanate mixture consisting of 4.4^OF-MDI (58%), 2,4 -MDI (19%) and polymethylene polyphenyl polyisocyanate (23%).

The properties of the foam obtained by reacting the prepolymer thus prepared with the identified polyol are as follows:

<td rowspan="2"></td><td colspan="2">Foam</td><td rowspan="2">hmo ta 6</td>

<td>and</td><td> 5</td>

<td>isocyanate reaction index</td><td> 90</td><td>Í00</td><td> 110</td>

<td>pressing density / kg / nrV</td><td> 44,7</td><td> 4.4,4</td><td> 44,5</td>

<td>ductility, /% /</td><td> 130</td><td> 125</td><td> 118'</td>

<td>Tensile strength / k, Pa /</td><td> 134</td><td> 152</td><td> 180</td>

<td>DUJ./kPa/</td><td> 4,34</td><td> 5,41</td><td> 6,44</td>

Comparative prepolymer A

A comparative prepolymer having an isocyanate content of 29% by weight was prepared in the same manner as prepolymer I by reacting 10.8 parts of polyoxyethylene cyclopropylenethoxyl / hydroxyl. equivalent weight 1670; oxyethylene content 72%, statistically divided (with 100 parts of isocyanate mixture, consisting of 4.4 * -MDI (58%), 2.4 * -MDI (19%) and polymethylene polyphenyl polyisocyanate (23%)).

<td rowspan="2">P</td><td colspan="3">ěnová h. m o. ia</td>

<td>AND⁺</td><td>B⁺</td><td>C⁺</td>

<td>isocyanate reaction index</td><td> 90</td><td> 100</td><td> 110</td>

<td>density at free swelling</td><td>/ kg / no. / 38</td><td> /</td><td> / .</td>

<td>density during pressing / kg / nP /</td><td> 45,7</td><td> 45,6</td><td> . 45,5</td>

<td>ductility /% /</td><td> 120</td><td> 115</td><td> 99</td>

<td>tensile strength / kPa /</td><td> 122</td><td> 140</td><td> 159</td>

<td>rt “/ι / 1-Ti— /</td><td>Ί 0 4-</td><td>Λ 11</td><td>C ĎO</td>

<td>/ IX * O / -— ·</td><td>JJ * l</td><td>rj,,</td><td></td>

<td>ILD / N /</td><td> 150</td><td> 190</td><td> 240</td>

+ these are not materials according to the invention

- 13 Comparative prepolymer B

Comparative prepolymer B has an isocyanate content of 29% by weight and is prepared in the same manner as prepolymer 1 by reacting 11%, 1 parts of polyethylene / propylene tricyl / hydroxyl equivalent weight of 2670, oxyethylene. 70.%, Statistically differentiated by -11 - from -4 -, - 4 - = - MDI (58%), 2.4 * -MDI (19 V) and polymethylene polyphenyl polyisocyanate (23%).

<td rowspan="2">^at 'Foam</td><td colspan="2">^r á matter</td>

<td>D⁺</td><td>- . with</td>

<td>⁷ is ocyanate o -rea kč ni- index = - - = ==</td><td> ==-90-=</td><td> ^100--=</td>

<td>density during pressing / kg / m ^ /</td><td> 47,8</td><td> 46,8</td>

<td>-extension /%/.:.-.,. ... ..</td><td>- Íi7_ ...</td><td> . .. .103-. .</td>

<td>limit. tensile strength / kPa /</td><td> 118</td><td> 143</td>

<td>C1D '/ kPa</td><td> 4,12</td><td> “ 5,08</td>

<td>⁺ they are not compositions according to the invention</td><td></td><td></td>

Foams 1 to 6 show improved ductility, which can be achieved with the prepolymers according to the invention in comparison with the compositions based on comparative prepolymers.

Prepolymer 3

An isocyanate-terminated prepolymer having an isocyanate content of 29% by weight is prepared as prepolymer 1, but 11.1 parts of polyoxyethyleneoxy-alkyl n-trio-1-u-t-hydroxy are used. The ethylene content of 61% is evenly distributed as an internal triethylene block as a terminal oxyethylene block which is reacted with the same polyisocyanate mixture. .

Comparative prepolymer C.

The comparative prepolymer having an isocyanate content of 29 is prepared in the same way as prepolymer 1 by reacting 10.9 parts of polyoxyethylene oxypropylene triol (hydroxyl equivalent weight 1954, oxyethylene content 64%, statistical distribution) with 100 parts of an isocyanate mixture consisting of 4.4 * -MDI „/ 58% /, 2,4 -MDI. (19%) and from polymethylene polyphenyl polyisocyanates herein. /23% / »

The following table shows the phase properties of the foams obtained by reacting prepolymers 1, 3 and C with the above-mentioned polyol formulations. In this case, the foams are prepared using a low-pressure mixing and dosing unit,

It is clear from the values ​​that advantageous ductility characteristics are achieved using the prepolymers according to the invention. Prepolymer ΐ 3 C⁺ isocyanate reaction

<td>index</td><td> 90</td><td> 100</td><td> 110</td><td> 90</td><td> 100</td><td> 110</td><td> 90</td><td> 100</td><td> 110</td>

<td>free-flowing density / kg / m^J/</td><td> 36</td><td> 37</td><td> 36</td><td> 36</td><td> 37</td><td> 36</td><td> 37</td><td> 37</td><td> 39</td>

<td>density at pressing. / kg / iiH</td><td> 48</td><td> 48</td><td> 48</td><td> 47</td><td> 49</td><td> 48</td><td> 49</td><td> 49</td><td> 49</td>

<td>tensile strength / kPa /</td><td> 130</td><td> 178</td><td> 200</td><td> 150</td><td> 188</td><td> 206</td><td> 146</td><td> 174</td><td> 227</td>

<td>tažnoat /% /</td><td> 138</td><td> 145</td><td> 118</td><td> 147</td><td> 142</td><td> 132</td><td> 126</td><td> 119</td><td> 108</td>

⁺ it is not a composition according to the invention

Prepolymer 4

Isocyanate-terminated prepolymer / containing isocyanate. 27.5% is prepared as a prepolymer_rAccording to this example, 11.1 parts of a polyol mixture containing 24% of polyoxyethyleneoxyalkylenetriol (hydroxyl equivalent weight 2463, oxyethylene content of 61%, statistical distribution) and 76 parts of polyoxypropyl polyol having a molecular weight of 1-10 are reacted with 89 parts of polyisocyanate mixture. consists of 4,4-MDI (61%), 2,4-MDI (9%) and polymethylene polyphenyl polyisocyanate (30%),

Industrial applicability

..Ingredients. and a process for the preparation of an isocyanate-terminated prepolymer which is suitable for the preparation of polyurethane and the preparation of high-performance polymers.^-; -'— jssírnkát

<img file="CS9103428A3_D0003.tif" />

CLAIMS