CA2114874A1

CA2114874A1 - Rigid hydrophobic polyurethanes

Info

Publication number: CA2114874A1
Application number: CA002114874A
Authority: CA
Inventors: Hanns-Peter Muller; Manfred Kapps; Kirkor Sirinyan; Thomas Scholl; Richard Weider; Rolf Dhein
Original assignee: Bayer AG
Current assignee: Bayer AG
Priority date: 1993-02-08
Filing date: 1994-02-03
Publication date: 1994-08-09
Also published as: DE4303556C1; JPH06256453A; EP0610714A2; EP0610714A3

Abstract

RIGID HYDROPHOBIC POLYURETHANES

ABSTRACT OF THE DISCLOSURE
Rigid polyurethanes are prepared by reacting polyisocyanates with, a polyol mixture consisting of a) an OH functional polyesters with molecular weights of 260 - 2000 derived from C9-C22 fatty acids, b) an OH functional, oligomeric polyolefins with molecular weights of 700 - 6000 and optionally c) an at least difunctional polyol with a molecular weight of 62 - 8000, which is different from components 2a) and 2b).

Description

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Mo-4001 LeA 29,502 - us RIGID HYDROPHOBIC POLYURETHANES
BACKGROUND OF THE INVENTION
The present invention relates to novel hydrophobic, rigid polyurethanes ("PUR"), particularly polyure~hane rigid foams.
Materials based on polyurethanes have been known for a long time (see, for example, G. Oertel, ~'Polyurethane", Kunststoff-Handbuch, Georg Thieme Verlag Stuttgart - New York (1~87)). PUR
.
casting resin, PUR plasticized and rigid foams are typical. PUR
foams are generally cross-linked polyurethanes. Rigid foams are generally closed-cell while plasticized foams are mainly open-cell materials. Rigid foams are generally produced by the addition of a liquid, low-boiling blowing agent, especially fluorotrichloromethane (see, G. Oertel, "Polyurethane" Kunststoff-Handbuch, Georg Thieme Verlag Stuttgart - New York (1987)). Fluorochlorohydrocarbons, ;~ however, are regarded as being harmful to the environment. For this . reason, an effort is being made to replace this class of compounds by low-boiling hydrocarbons such as n-pentane or n-hexanc (see, G.
Heilig, Kunststoff, 81, p. 622 (1991)). It is known that low-boiling hydrocarbons are readily innarnmable liquids. Working with low-~i boiling hydrocarbons, therefore, often requires additional and costly `, anti-explosive measures.
PUR malrices are hydrophilic systems wi~hin certain limits.
According to data in the literature, -NH-CO-O- and -NH-CO-NH-- bonds enter into a relatively strong, physical interaction with water - -` ~ molecules and therefore facilitate diffusion of water into the interior of ,I the PUR matrix (,see, for example, V. Gajewski, Proceedings of the .I 25 SPI 33rd Annual TechnicallMarketing Conference, p. 506, Technomic Publishing Co. Inc., Pennsylvania ~1990~).

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The ~generally undesired~ diffusion of water into the PUR
matrix may lead to: i) a reduction in resistance to hydrolysis, ii) a reduction in thermal and electrical insuiating properties, iii) an impairment of the mechanical properties, particularly dimensional 5 stability and shrinkage behavior, and iv) an increase in gas permeability, e.g of C2 and 2 DESCRIPTION OF THE INVENTION
- The present invention is based on the object of developing especially hydrophobic rigid polyurethanes and in particular PUR rigid 10 foams which are characterized by a lack of shrinkage, good dimensional stability, good resistance to hydrolysis, outstanding long-;;` term behavior and very good insulating properties. The PUR rigid ,;
foams are intended to be obtained by the addition of water as blowing ~' ~, agent, be closed-cell structures and have the advantageous properties mentioned above.
Surprisingly, these objects are achieved by reacting 5 ` polyisocyanates with a special polyol mixture comprising a) specified Ol l-functional polyesters, b~ specified OH-functional, oligomericpolyolefins and . 20 optionally ~ c) specified additional polyols.
: It was extremely surprisin~ that strongly hydrophobic poly-urethanes were obtained by using the blends of polyols according to the invention, although their matrices are still characterized by thz -25 ~ormation of polar-NH-CO-O- and -NH-CO-NH- bonds.
The present invention provides rigid polyurethanes which are obtainable by teacting 1) polyisocyanates with Mo4001 . .

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2) a polyol mixture consisting of ) OH-functional polyesters with molecular weights of from 260 to 2000, derived from on Cg-C22 fatty acids 5 b) OH-functional, oligomeric polyolefins with molecular weights of from 700 to 6000 and - optionalty c) at least difunctional polyols with molecular weights of from 62 to 8000, preferably of 62 to :4 10 400, which are different from components 2)a) - ' and 2~b), 3) optionally in the presence of water as blowing agent and 4) optionally in the presence of auxiliary substances and ~`,! additives known in Pl)~ chemistry.
According to the invention, it is preferred that component 2)b3 be present in an amount of from 5 to 80% by wei~ht based upon the - total weight of the polyol mixture and be selected from the group , consisting of polyisobutenes, polybutadienes, and polyisoprenes. il is ;i also preferred that OH-functional triglycerides of naturally occurring fatty acids or sorbitan esters be used as componeni 2a), and that component 2)a) be present in an amount of from 1 to 80% by weight l based upon the total weight of the polyol mixture. Finally, it is preferred that component 2)c) be present in an amount of from 0 to 80% by weight based upon the total wei~ht of the polyol mixture.
According to ~he invention, rigid hydrophobic polyurethana foams are preferred.
y The foams of the invention are useful as insulating materials in low-temperature technology and in the building, automobile, ship-building and/or electrical fields.

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The starting materials used for preparation of the rigid, hydrophobic polyurethanes of the present invention are generally ~- known n the PUR art. Useful isocyanates include aliphatic, cycloaliphatic, araliphatic, aromatic and heterocyclic polyisocyanates, ~'',.''``'A,`~ 5 such as are described, for example, in Justus Liebigs Annalen der ~i Chemie, 562, pages 75 to 136. Such isocyanates are, for example those of the formula ,. ~ ~
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~`- wherein n = 2-4, preferably 2 and 3, and Q represents an aiiphatic 10 hydrocarbon group with 2-18, preferably ~-10 carbon atoms, a ~`, cycloaliphatic hydrocarbon group with 4-15, preferably 5-10 carbon '~ atoms, an aromatic hydrocarbon group with 6-15, preferably 6-13 . , carbon atoms or an araliphatic hydrocarbon group with 8-15, preferably 8-13 carbon atoms. Such isocyanates are described in German Offenlegeschrift 2,832,253, pages 10-11. Particularly ;,$ preferred are readily available polyisocyanates, e.g. 2,4- and 2,6-~,}~ tolylene diisocyanate, and any mix~urc of these isomers ("TDI");
polyphenylpolymethylene polyisocyanates, such as are produced by ~;~' anilinelformaldehyde condensation and subsequent phosgenation 20 ("crude MDI"); and polyisocyanates which have carbodiimide groups, .. ~ urethane groups, allophanate groups, isocyanurate groups, urea ', groups or biuret groups ("modified polyisocyanates"), particularly -~hose modified polyisocyanates which are derived from 2,4- andlor 2,6-tolylene diisocyanate or from 4,4'- andlor 2,4'-diphenylmethane 25 diisocyanate.
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- ~ The polyol mixture of the present invention consists of . . a) OH-functional polyesters with molecular weights of from 260 to 2000 derived from C9-C22 fatty acids;
~, b) OH-functional, oligomeric polyolefins having molecular weights of from 700 to 6000, and.
c) optionally, at least dihyroxyl polyols different from components a) and b) and having molecular weights of from 62 to 8000.
The OH-functional polyesters a) are compounds known per se, 10 wherein preferably those based on renewable raw materials are considered. The definition of "renewable raw materials" can be ~-: obtained from the literature, for instance, ~Nachwachsende Rohstoffe , und ihre Verwendung" AIO (Auswertungs- und Informationsdienst fur ` ~ Ernahrung, Landwirtschaft und Forsten (AIO) 5300 Bonn (1992)). In 15 this connection the following may be referred to, by way of example:
the sorbitan esters of aliphatic long-chain, organic acids; the ~ - :
~i~ polyesters of mono or polyhydric alcohols and dodecanoic, lauric, hexadecanoic and palmitic acids; the polyesters of mono or polyunsaturated fatty acids with a rhain length of C9-C22.
,~ 20 Polyesters based on OH-functional triglycerides of naturally occurring fatty acids and sorbitan esters are preferred. It is known ~ that triglycerides of unsaturated fatty acids can be epoxidized by the ;~, in situ performic acid process and can be provided with OH groups by subsequent reaction with alcohols or acids (see, B. Gruber et al., Fett 25 Wissenschaft Technologie, 89, 147 (1~87) and R. Hofe, Phanomen Farbe, 4, p. 55 (1992~).
According to the invention, OH-functional triglycerides of 9-hexadecenoic acid (palmitic acid), 9-octadecenoic acid (oleic acid), 9,12-octadecadienoic acid (linoleic acid), 9,12,15-octadecatrienoic ~ii Mo4001 ~ - ~ , . . .

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acid (linolenic acid), 9,12,13-octadecatrienoic acid (tung oil) and also , ^ 12-hydroxy-9-octadecenoic acid (ricinoleic acid) or mixtures of these j with each other are preferably used.
-` The amount in the polyol mixture is generally from 1 to 80% by 5 weight. The OH values (see, Hydroxyzahl, H. Kittel, Farben- Lack-und Kunststoff-Lexicon, Wiss. Verlagsgesellschaft M.B.H. Stuttgart (1952)) of these polyesters are generally in the range of from 50 to 600.0bviously, blends of the polyols mentioned may also be used.
The OH-functional, oligomeric polyolefins with molecular 10 weights of from 700 to 6000 are also compounds known per se.
- They can be prepared either by polymerization and subsequent chain - termination or by selective subsequent degradation of polymer molecules ~see, for instance, German Offenlegeschrift 2,147,874, .; Canadian Patents 792.805 and 931.299, G.A. Verdol et al., Rubber .~-;3 15 Agc 98, p. 67 (1966) and Company document BF Goodrich AB-211 1 "Routes to Polyurethane Modification with Hycar Hydroxyl-Termina~ed Reactive Liquid Polymers", BF Goodrich, 9911 Cleveland). Their OH
~-, values are generally from 20 to 300, and are preferably between 20 . .
and 120. The amount of these polyols (with reference to the polyol ,1 20 mixture) is generally between 5 and 80% by weight.
Basically all OH-functional polyolefins based on, for example, butadiene, isoprene and isobutene may be used, and those based on butadiene and isoprene are particularly preferred with those based on , isobutene being most preferred.
In some cases the OH groups may be replaced by other j reactive groups such as amino or acid groups. In this connection,,j partially or completely amino-terminated oligomeric polyisobutenes may be used.

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'3: - 7 -,~ The optional at least difunctional polyols with molecular weights of from 62 to 8000 are different from components 2a) and 2b) and are preferably polyetherpolyols or lower polyols with molecular weights of - ~ from 62 to 400 such as glycerol or butanediol. Also useful are the .i , 5 higher functional alkylene oxide adducts, mainly those with starting materials based on naturally occurring substances such as sorbitol, saccharose, glucose and glycerol (see, for example, German ' Offenlegungschriften 2,639,û83, 2,639,084, 2,714,084, 2,714,104, 2,721,186, 2~721,093, 2,732,077, 2,738,154, 2,738,512, 2,756,270, 10 2,808,228 and 2 831,659 and U.S. Patent 2,990,376).
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i ~ The principal epoxides to be considered for building up the polyetherpolyols are propylene oxide and/or ethylene oxide. Since ~ :~
. ~ propylene oxide supplies secondary OH groups during alkali catalyzed polyaddition, whereas ethylene oxide supplies prima~ OH groups, ~'odi 15 and the latter are more reactive towards isocyanate groups, the t, ~
activity of the polyether can be predetermined via the type of epoxide.
~` Segments made from one or other epoxide can be deliberately incorporated at specific points in the chains by the stepwise . polyaddition of propylene and ethylene oxide. Thus, the properties of ~'!' 20 the polyol, induding activity, viscosity, hydrophilicity and compatibility ! ` with the OH functional polyesters (component 2)a)) and oligomeric .~ polyolefins (component 2)b)) can be controlled in a desired manner.
The amount of polyol 2)c) in the polyol mixture is generally from 0 to 80% by weight (with reference to the total polyol mixture).
~1 25 The OH groups in the polyols 2)c) may also be replaced, ~, partially or completely, by amino groups. It is known that the starting - `
materials u ied for preparing polyethers include aliphatic amines, such j as e.g. ethylenediamine, and aromatic amines, e.g. diaminotoluene or ,`$ diaminodiphenylmethane. Aminoalcohols are also used forthis ~ I Mo4001 ., :

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f~, purpose. This type of nitrogen-containing polyol is of~en used in rigid ~; foam formulations due to its high activity (see, G. Oertel, "Polyurethane~. Kunststoff-Handbuch, p. 18, Georg Thieme Verlag Stuttgart - New York (1987)).
. 5 Water is preferably used as the blowing agent.
Auxiliary substances and additives can also be used. Such materials include:
. . i) very volatile organic substances as additional blowing .
;~ agents, 10 ii) known catalysts in amounts of up to 10% by weight, based upon the total weight of component 2), iii) surface active additives, such as emulsifiers and foam stabilizers, ,~ iv) reaction inhibitors, e.g. acid substances such as hydrochloric acid or organic acid halides, also cell -`~, controllers of a per se known type such as paraffins or fatty alcohols or dimethyl-polysiloxanes as well as j pigments or dyes and fireproofing agents of a per se i known type, e.g. tricresyl phosphate, also stabilizers against the effects of ageing and weathering, plasticizers , and anti-fungus and anti-bacterial substances as well as fillers such as barium sulphate, kieselguhr, carbon black or whiting.
These optionally used auxiliary substances and additives are 25 described, for example, in German Offenlegeschrift 2,732,292, pages 21-24.
Further examples of surface active additives and foam stabilizers as well as cell controllers, reaction inhibitors, stabilizers, flame-retardant substances, plasticizers, dyes and fillers as well as i Mo4001 ; ~ ~ . . . . . .

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anti-fungus and anti-bacterial agents to be used according ts) the invention, and details on the use and mode of action of these additives are described in Kunststoff-Handbuch, vol. Vll, pubiished by Vieweg und Hochtlen, Carl-Hanser-Verlag, Munich, 1966, e.g. on ~, 5 pages 103-113.
The rigid PUR foams are prepared in ways known in the art.
The reaction components can be prepared for reaction by thc known one-step processes, the known prepolymer processes or the known ~' semi-prepolymer processes, wherein mechanical devices are often : :31 10 used, e.g. those described in U.S. Patent 2,764,565. Details on processing devices which are also suitable according to the invention, ;~ are described in Kunststoff-Handbuch, vol. Vll, published by Vieweg und HochUen, Carl-Hanser-Verlag, Munich, 1966, e.g. on pages 121 .. to 205.
~; 15 The foams can be prepared e.g. by slab foaming or by twin .. ~ conveyer belt methods.
; ` By hydrophobic PUR foams are to be understood those which, after their preparation (see working examples), have a water absorption to achieve saturation (constant mass), in a 100% water-` 1l 20 saturated atmosphere at 30C, of c 3.5%, preferably ~ 3.25% and most preferably < 2.9%.
Without restricUng the scope of the invention, it may b~ pointed out that the PUR rigid foams according to the invention should have a bulk density of 25-85 kglm3, wherein in some cases these limits may be varied either upwards or downwards. -The polyol mixtures used according to ~he invention are particularly suitable for the preparation of water-blown, non-shrink, ~I closed-cell, PUR rigid foams which are relatively impermeable to C2 and 2- : :

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~ ~ foams thus obtained may be used in the struc~ural and civil j~ engineering, automobile, packaging, house- and ship-building and electrical sectors and in low-~emperature technology. Furthermore, they are outstandingly suitable for the production of insulating sheets, PUR structural foams and sandwich elemenls. They may be used with no problems for the cladding of internal spaces and for expanding into cavities. Basically the production of hydrophobic rigid and semi-rigid foams is possible. Processing to give solid materials by the known casting processes, optionally under pressure, is also possible, as is processing using the known RIM and RRIM
technology. Subsequent thermoforming is also possible using the polyurethanes according to the invention.
The present invention is explained in more detail using the ~ ~1 15 following working examples. All percentages represent % by weight.
: EXAMPLES
Example 1 A PUR reaction mixture consisting of ., . . -48.0 parts by wt. OH-functionalized, oligomeric polyisobutene with a molecular weight of about 4000 and an OH value of 2R, . 48.0 parts by wt fatty chemical polyol based on glycerol and soy oil with an OH value of 250, 14.0 parts by wt. glycerol, ;~ 6.0 parts by wt. water, 25 3.6 parts by wt. Desmorapid~) DB, a PUR activator (Bayer AG), ;~ 1.5 parts by wt. Silicone stabilizer PU 1866 (Bayer AG); and 204.0 parts by wt. Desmodur~) 44 V 20, a crude MDI (Bayer AG) (NCO content 30,5 % b.w.) Mo4001 ~,r ~.~
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still not visibly foaming mixture is placed in a paper box with the dimensions 25 x 13 x 13 cm and allowed to expand.
:~ The rising time of the PUR mixture is about 60 seconds. After a further 120 seconds, the foam achieves an adequate degree of rigidity and can be handled without any problems.
-~ The resultant rigid foam has a slab height of about 21 cm and a bulk density of 43 kg/m3. It is hydrophobio, dimensionally stable and, af~er storing for several weeks, does not shrink. Its water absorption is about 2.6%. To determine the watet absorption, the sample was roughened with a file, compressed into a compact block ~ under 300 bar pressure and dried for 16 hours over blue silica gel.
'~' Then the water absorption until a constant mass is reached (ca. 6 hours), in a 100% water-saturated atmosphere at 30C, was determined gravimetrically using a microanalytical balance.
!`~ Come~rison ExamPle 1a ` A PUR reaction mixture consisting of48.0 parts by wt. polyisobutene as in Example 1;
48.0 parts by wt. Desmophen~ 4012, a polyol based on trimethylolpropane and propylene oxide (Bayer AG), OH value 380;
14.4 parts by wt. glycerol;
6.0 parts by wt. water, 3.6 parts by wt Desmorapid~ DB and 1.5 parts by wt. silicone stabilizer as in Example 1 !;~3 was stirred as in Example 1. A highly viscous polyol mixture is produced. This mixture was not miscible with the polyisocyanate component (Desmodur 44 V 20) and could not be processed to give a PUR rigid foam.

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~, Comparison ExamPle 1b , A PUR reaction mixture as in Example 1, consisting of ~: ~ 100.0 parts by wt. Desmophen~ 4012 R, a polyetherpolyol made from s trimethylolpropane and propylene oxide (Bayer AG), OH value ~; 5 380;
6.0 parts by wt. water 3.6 parts by wt.Desmorapid~ DB
1.6 parts by wt.silicone stabilizer as in Example 1 and 197.8 parts by wt. Desmodur~ 44 V 20 is expanded as in Example 1. A closed-cell PUR rigid foam with a rise time of 60 seconds and a block height of about. 21 cm is obtained. It has a bulk density of 41 kg/m3. It is relatively hydrophilic --` and its water absorption is 4.2%.
`~ Example 2 A PUR mixture oonsisting of 40.0 parts by weight OH functional, commercial, oligomeric polybutadiene with a molecular weight of about 2500 and an : OH value of about 4640;
,~ 40.0 parts by weight of fatty polyol as in Example 1;
~, 20 11.7 parts by weight glycerol;
.' 5.0 parts by weight water;
1.3 parts by weight silicone stabilizer as in Example 1;
$y', 3.0 parts by weight Desmorapid~ DB; and 170 parts by weight Desmodur~ 44 V 20 is expanded as in Example 1.
A shrink-free, hydrophobic PUR rigid foam is obtained. Its bulk density is about. 43.6 kg/m3 and its water absorption is 2.8%.
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. Although the invention has been described in detail in the ~ foregoing for the purpose of illustration, it is to be understood that : ~ such detail is solely for that purpose and that variations can be made therein by those skilled in the art without departing from the spirit and ~: i, 5 scope of the invention except as it may be limited by the claims.
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Claims

1. A rigid polyurethane prepared by reacting 1) one or more polyisocyanates with,

2) a polyol mixture consisting of a) an OH functional polyester with a molecular weight of from 260 to 2000 derived from a C9-C22 fatty acid, b) an OH functional, oligomeric polyolefin with a molecular weight of from 700 to 6000, and c) optionally, one or more at least difunctional polyols with a molecular weight of from 62 to 8000, which is different from components 2a) and 2b),

3) optionally in the presence of water as blowing agent.
2. The rigid polyurethane of Claim 1, wherein component 2b) is a polyisobutene.
3. The rigid polyurethane of Claim 1, wherein component 2b) is a polybutadiene.

4. The rigid polyurethane of Claim 1, wherein component 2b) is a polyisoprene.

5. The rigid polyurethane of Claim 1, wherein OH functional triglycerides of naturally occurring fatty acids or sorbitan esters are used as component 2a).

6. The rigid polyurethane of Claim 1, wherein component 2a) is contained in an amount of 1 - 80% by weight in polyol mixture 2) (wherein the sum of components 2a), 2b) and 2c) is 100% by weight).

7. The rigid, hydrophobic polyurethane of Claim 1, wherein component 2b) is present in an amount of 5 - 80% by weight in polyol mixture 2) (wherein the sum of components 2a), 2b) and 2c) is 100%
by weight).

8. The rigid polyurethane of Claim 1, wherein component 2c) is contained in an amount of 0 - 80% by weight in the polyol mixture (wherein the sum of components 2a), 2b) and 2c) is 100% by weight).