CA1175994A

CA1175994A - Process for the preparation of polyurethanes having a particular combination of polyols and extender

Info

Publication number: CA1175994A
Application number: CA000427959A
Authority: CA
Inventors: Louis M. Alberino; Robert J. Lockwood
Original assignee: Upjohn Co
Current assignee: Pharmacia and Upjohn Co
Priority date: 1982-06-07
Filing date: 1983-05-11
Publication date: 1984-10-09
Also published as: ATE18913T1; EP0096231B1; EP0096231A1; US4385133A; JPH0488B2; JPS591523A; DE3362759D1

Abstract

ABSTRACT OF THE DISCLOSURE
Polyurethanes having a two phase morphology and characterized by high impact strength and, optionally, high modulus are obtained by reaction of 4,4'-methylenebis(phenyl isocyante) and modified forms thereof with an aliphatic glycol extender and a blend of at least two polyoxypropylene-polyoxyethylene polyols, both of which have average functionalities in the range of 2 to 4, one of which has a molecular weight in the range of about 3,000 to 10,000 and contains at least 23%
by weight of ethylene oxide residues and the other has a molecular weight in the range of about 750 to about 2,000 and contains at least 45% by weight of ethylene oxide. The two or more such polyols are employed in proportions such that the aliphatic glycol extender is completely miscible with said polyols if blended together.

Description

~ 1 - 4004 DESCRIPTION

BACKGROUND OF INVENTION
__ _ _ Field of the Invention This invention relates to the preparation of polyurethanes and to polyurethanes so prepared and is more particularly concerned with polyurethanes prepared from an organic polyisocyanate, an a1iphatic glycol extender and a particulan mixture of two or more polyether polyol s.
Description of the Prior Art .
The preparation of polyurethanes by reaction of an organic poly-isocyanate, a polyether polyol and a low molecular weight extender such as an aliphatic glycol is commonplace in the art. The use of copolymers of ethylene oxide and propylene oxide, having varying func-tionality depending upon the functionality of the initiator used in the copolymerization, has been found to confer particularly useful structural strength properties on such polyurethanes both in cellular and non-cellular fonms. Illus~ratively~ U.S. Patent 3,857,880 shows the preparation of polyurethane foams wi~h a reduced tendenc.y to shrink by use of a combination af two polyols, one of whlch can be an ethylene oxide-capped polyoxypropylene polyol having a molecular weight of 3,000 to 6,000 and a primary hydroxyl content of 20% to 70%
and the other of which can be an ethylene oxide-propylene oxide co-polymer having a molecular weight of 500 to 2,000 and an ethylene oxide content of 20% to 80% by we1~ht. No aliphatic glycol extender is employed in preparing the foams disclosed in this reference.
U.S. Patent 3,945,937 discloses a probleD which exists in the preparation of polyurethanes by reaction of an organic polyisocyanate with an ethylene oxide capped polyoxypropylene polyol using ethylene glycol and like low-molecula~ weight glycols as the extender. The low molecular weight glycol is inccmpat~ble with the polyol in the propor-tions employed and the reference shows that colloidal silica or cer-ta~n clays could be utilized to assist in ~orming a stable disperslon of the glycol in the polyol prior to reaction.
U.S. Patent 4,273,884 describes substantially the same problem and overcones it by fonming an emulsion of the polyol and the low mo-lecular we~ght glycol prior to react~on with the polyisocyanate.
U.S. Patent 39798,200 describes the preparation o~ polyurethanes . , ~7~

-2- 4004 having improved cut growth and flex-crack resistance by reacting an organic polyisocyanate with a mixture of two different polyether poly-ols and any of a wide varie~y of active-hydrogen containing extenders which can include low molecular weight glycols. The two polyether polyols were chosen fr~m a wide variety of such polyols, the criti-cality being said to lie in ~hat one of the two had a peak in the high end of the molecular weight distribution curve and the other had its peak in the lower end of ~he range but the average molecular weight of the mixture of the two polyols was in the range of 4,500 to 20,000.
U.S. Patent 3,963~68l discloses a closely related development in the same area but calls for the average molecular weight of the mixture of the two polyols to be in the range of 1,000 to 4,500.
U.S. 4,065,410 describes a method of increasing the green strength of polyurethane elastomers having a compact skin and a cellu-lar core by using as the extender a mixture of ethylene glycol and up to 30% by weight, based on total weight of extender, of a polyol having a molecular weight of less than 1,800. A wide variety of the latter polyols is disclosed. Compa~ibility of the ethylene glycol with the polyol component is no~ discussed.
We have now found that, not only can the problem of compatibil-iz~ng a low molecular weigh~ glycol extender in a polyether polyol be solved in a highly satisfac~ory manner, but certain properties of the polyurethanes produced from the compatibilized components are greatly enhanced as a direct consequence of the compatibiliza~ion. The latter can be achieved, as described below, by the use of a combination of at least two carefully chosen groups of polyoxyethylene polyoxypropylene polyols in propor~ions such that the aliphatic glycol extender is com-patible kherewlth in the range of proportions in which it is required to be used ~n preparing the polyurethane.
SUMMARY OF THE IN~ENTION
This invention compr~ses an improved process for the preparat~on of polyurethanes by reaction o~ an organic polylsocyana~e, a polyol and a low molecular weight aliphat~c glycol extender wherein the im-provement comprises employing as the polyol component a mlxture which comprises:
(a) a polyoxypropylene polyoxyethylene polyol having an average functionality from 2 to 4, a molecular weight in the range o~ about 3,000 to about 10,000 '~' ~3- 4004 and containing at least 23% by weight of ethyl-ene oxide residues; and (b) a polyoxypropylene polyoxyethylene polyol having an average functionality from 2 ~o 4, a molecu1ar weight in the range of about 750 to about 2,000 and containing at least 45% by weight of ethylene oxide;
th~ proportions by weight of ~he camponents (a) and (b) being a~usted so that the aliphatic glycol extender is completely miscible with said mixture of components (a) and (b~.
The invention also comprises the polyure~hanes prepared in accor-dance with the process. The invention is particularly concerned with the use of the process set forth above to prepare polyurethanes (cell-ular, microcellular and non-cellular) using reaction injection molding (RIM) technology and with ~he polyurethane prepared.
DETAILED DESCRIPTION OF THE INYENTION
The improved process of the invention can be carried out using any of the conventional techniques employed in the art of making poly-urethane. The novelty of the process lies in the use of a par~icular ccmbination of polyols and extender. The impr w ed process of the in-Yentlon is especially adapted for use in reaction injection moldingtechniques but can also be applied to a variety of other situations such as sprayl pour-in-place and casting applications. The use of the process of the invention has a nu~ber of advantages. It gives rise to polyurethanes which have exceptionally high impact strength as well as excellent overall physical properties. Further, the use of the par-ticular combination of polyols and extender allows one to prepare a blend of polyols and extender which is a homogeneous single phase liqu~d. This contrasts with the two phase polyol components which have hitherto been encountered in using low molecular we~ght aliphatic glycol extenders in combination with polyether polyols; see the art cited supra. The reactants necessary to prepare polyurethanes of the type under consideration here are normally supplied to the end user by the manufacturer in the form of a two component sys~em. One componen~
(commonly known as the "A slde") comprises the organic polyisocyanate and cer~ain addltives which are not reactive with the ~socyanate. The other component (commonly known as the "B slde") comprises the poly-ol(s) and extender. If the components of the B side are not compat-ible, as in the case of the prior art systems discussed above, heroic ~L~L7~

measures have to be taken to seek ~o stabilize the B side and render it homogeneous. This problem does not exist in respect of the B side which is provided in accordance with ~he present invention since the components thereof are freely miscible one with another.
This finding greatly facil;tates the actual use of the A and B
sldes in accordance with the presen~ invention. Since the components of the B side are miscible one with ano~her, no special precautions have to be taken to maintain homogeneity during storage or in dispen-sing through equipment such as the high pressure heads and auxiliary equipment routinely employed in RIM processing. Additional advantages which flow from the use of a B side which is homogeneous, as in the case of the present invention, will be apparent to one skilled in the art.
As set forth above, the improvement in both processing capability and product properties provided by this invention lies in ~he use of a par~icular combination of two different polyoxyethylene polyoxypropyl-ene polyols (a) and (b) as defined hereinabove. As will be seen frcm the definitions, the two types of polyol differ in molecular weight and ethylene oxide content and can also differ in functionality. Both types of polyol and methods for their preparation are well known in the art; see, for example, Saunders and Frisch, Polyurethanes, Chemis-try and Technology~ Part I, Interscience, New York, 1962~ pp. 36-37.
The polyether polyols ~a) and (b) employed in accordance with the in-vention are inclusive of both block and random copolymers of propylene oxide and ethylene oxide using initiators such as water, ethylene gly-col, propylene glycol, glycerol, trimethylolpropane, pentaerythritol and the like.
Although any of the glycols, triols and ~etrols meet~ng the para meters defined in (a) and (b) above can be used in co~bination, it is preferred to use a combination of a triol meet1ng ~he parameters set forth under (a) and a diol meeting the parameters set forth under (b).
Further, lt is preferred to use a combination of a triol meeting the parameters set forth under (a) but hav~ng a molecular weight in the range of about 4,000 to about 7,000 w~th a diol meet~ng the parameters set forth under (b) but having a molecula~ weight in the range of about 1,000 ~o 1,500.
The proportions in which the two different polyether polyols (a) and (b) are used in accordance with the invention are a function of ~7~

the particular polyol~ to be employed in the combination and, more particularly, of the identity and amount of the low molecular weight aliphatic glycol which is to be incorporated into the combination. It is generally desirable that the a~ount of polyol (b) which is present in the combina~ion be kep~ to as low a level as possible consonant with the requirenent that the low molecular weigh~ aliphatic g1ycol be completely miscible with the combination of polyols (a) and (b) Thus it is found that the use of larger proportions of polyol (b) than are necessary to achieve the above stated result tend to detract from the highly advantageous physical properties, particularly in regard to impact strength, of the polyurethanes prepared in accordance with the invention.
The proportions to be employed in any particular combination of the polyols (a) and (b) and any particular aliphatic extender in order to achieve the above stated results can be determined readily by a process of trial and error. To illustrate the methodology to be em=
ployed and some of the fac~ors which are involved, reference is made to FIGURE 1. The lat~er shows a plot of solubility of ethylene glycol (a typical low molecular weight aliphatic glycol extender) in a combi-na~ion of a polyol (b) which is a polyoxyethylene polyoxypropylene diol of molecular weight l,000 and having a content of ethylene oxide residues of 47~ by weight, and a polyol ta) which is represented by each of three polyoxyethylene polyoxypropylene triols all of which have a molecular weight 6,500 but differ in ethylene oxide residue content, one being 25.5% w/w, another 27% w/w and the third being 29.4% w/w. The abscissa of the graph of FIGURE 1 shows the proportton of polyol (b) in parts by weight per 100 parts by weight of the blend of pslyols (a) and (b). The ordinate shows the amount of ethylene glycol in parts by weight per 100 parts by welght of the blend of polyols ~a) and tb). Each of the three curves shows, at any given point on the curve, the max~mum amount of ethylene glyccl which is completely misclble with the blend of polyols (a) and ~b) hav~ng the conpos~tion represented by the point on the abscissa vert~cally below the point in ques~ion on ~the curve. For any given curve the area above the curve represents the relative proportions ~n which the polyols (a) and (b) and ethylene glycol, when brought together, would not be co~pletely m~sclble. The area below any given curve represents the relative proportions in which the three components9 when brought ~l~L~ D9 ~

together, would be completely miscible.
It will also be seen from FIGURE 1 that the proportion of ethyl-ene oxide residues in the polyol (a) plays a significant role in the amount of polyol (b~ which is necessary to achieve complete misci-b;lity of the three components at any g;ven level of ethylene glycol.
The dotted line shows the respective level of the two polyols (a) and (b) for each of the three different levels of ethylene oxide res~dues in the polyol (a) necessary to achieve co~plete miscibility where the ethylene glycol is employed at a level of 4~ parts per 100 parts of the polyol combina~ion. It will be seen that the level of polyol (b) necessary to achieve miscibility decreases as the proportion of ethyl-ene oxide residues in polyol (a) increases.
A graph corresponding to that illustrated in FIGURE 1 can be gen-erated by routine experimentation for each and every possible combi-nation of polyol ~a) and (b) with ethylene glycol or any of the other low molecular weight polyols in accordance with ~he invention. The particular polyols employed in genera~ing the data for FIGURE 1 were chosen as typical of those wh;ch can be employed in accordance with the invention. Ethylene glycol as also employed simply for purposes of illustration and any low ~0l2cular weight glycol can be employed in accordance with the process of the invention provided all the other parameters are met. Illustra~ive of such low molecular weight ali-phatic glycols, in addition to ethylene glycol, are 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, diethylene glycol, triethylene glycol, tetraethylene glycol, neopentyl glycol, cyclohexanedimethanol, and the llke.
In general, the proport~on in which the aliphatic glycol extender can be introduced ~nto the m~xture of polyols (a) and (b) and still produce a completely ~iscible blend lies within the range of about 10 to 100 parts by weight, per 100 parts by we~ght of said blend of poly-ols (a) and (b) depend~ng upon the proportions in which the latter two ~7~g~

polyols are present in the blend. A more preferred range is from about 15 to about 50 parts by weight of aliphatic glycol extender per lO0 parts by weight of the blend of polyols ~a) and (b), again depend-ing upon the proportions in which the latter two polyols are present in order to achieve miscibility. In order to achieve the desired mis-cibility in the above proportions, ~he proportion in which polyol (a) is employed can vary from about 0.1 to 4 parts by weight per part of polyol (b). The appropriate proportion to use in any given instance is readily deter~ined by trail and error.
Any of the organic polyisocyanates commonly employed in the art of preparing polyurethanes of the type set forth herein can be eD-ployed in carry;ng out the process of the invention. Illustrative of such polyisocyanates are 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 4,4'-methylenebis(phenyl isocyanate), dianisidine diisocyanate, tolidine diisocyanate, hexamethylene diisocyanate, 4,4'-methylenebis(cyclohexyl isocyanate), m-xylylene diisocyanate, 1,5-naphthalene diisocyana~e, 1,4-diethylbenzene~ diisocyanate and the like, including mixtures of two or more of said isocyanates.
The polyisocyanates employed in the process of the invention also in-clude 1iquefied fonms of 4,4'-methylenebis(phenyl isocyanate) and of mixtures of the latter with the corresponding 2,4'-is~mer. These liquef1ed forms of said diisocyanates are a well-recognized class which comprise stable liquids at temperatures of about 15C or higher.
Such compositions Include the carbod1imide-containing products having isocyanate equivalents from about 130 to about 180 prepared, for ex-ample, by heating the original dilsocyanate with a carbodilmide cata-lyst to convert a portlon of sa~d ~socyanate to carbod~lmide in accor-dance, for example, with the procedure described in U.S. Patent

3,384,653. The liquefied fonm of said diisocyanates also includes methylenebis(phenyl isocyanates) which have been reacted with minor amounts (from about 0.04 to 0.3 equivalents per equivalent of isocy-anate) of low molecular weight glycols as described, for example, in .

;g~4 ~_ 400 U.S. Patents 3,394,164, 3,644,457, 3,883,571 and 4,031,026.

4,4'-Methylenebis(phenyl isocyanate), admixtures of this isocy-anate with minor amounts of the corresponding 2,4'-isomer, and lique-fied fonms of these isocyanates are the preferred polyisocyanates for 5use in accordance with the invention.
As will be apparent to one skilled in the art the process of the present invention is particularly well suited for operation in accor-dance with a one-shot procedure but can also be applied to a prepoly-mer process in which event the prepolymer is preferably made using a portion of the polyol (a) and thereby reducing the amount of polyol (b) which is necessary to compatibilize the low molecular weight ali-phatic glycol extender with the remainder of the polyol component.
Whichever method of operation is employed, be it one-shot or pre-polymer, the process of the invention is carried out ;n accordance with procedures, and using mixing and dispensing equipment, which are so well known in the art as not to require recitation herein; see, for example9 U.S. 4,306,052 for a detailed account of such procedures. A
particularly advantageous manner in which to carry out the process is by use of reaction injection molding ~echnology, a detailecl descrip-20tion of which is given, for example, in U.S. 4,218,543.
In carrying out the process of the ~nvention the proportions in which the various reactants are enployed are such that the overall ratio of equivalents of isocyanate to total equivalents of active-hydrogen containing material are in the range of about 0.9:1.0 to 25about 1.15:1.0, and preferably in the range of about 0.95:1.0 to about 1.05:1Ø The proportions of equivalents of aliphatic glycol extender to total polyols (a) and (b) can vary over a wide range of about 5:~.0 to about 15:1Ø Preferably the proportions of equivalents of said extender to total polyols (a) and (b) are in the range of about 7:1.0 30to about 12:1Ø In general the higher the proportion of aliphatic extender the h~gher the flexural modulus.
The process of the invention is generally carried out in the presence o~ a catalyst ~or the reaction between hydroxyl groups and isocyanate groups. Any of the catalysts conventionally employed in 35the art to catalyze the reaction of an isocyanate with a reactive hydrogen containing co~pound can be employed for this purpose; see, for exa~ple, Saunders et al., Polyurethanes, Chemistry and Technology, Part I, Intersclence, New York, 1963, pp. 228-232; see also, Britain " ;
.

~L~L7 S~3~

et al., J. Applied Polymer Science, 4, pp. 207-211, 1960. Such cata-lysts include organic and inorganic acid salts of, and organometallic derivatives of, bismuth, lead, tin, iron, antimony, uranium, cadmiuma cobalt9 thorium, aluminum, mercury, zinc, nickel, cerium, ~olybdenum, vanadium, copper, manganese and zirconium, as well as phosphines and tertiary organic amines. Representative organotin catalysts are stannous octoate, stannous oleate, dibutyltin diace~ate, dibutyltin dioc~oate, dibutyltin diluarate, d~butyltin mal2ate, dibutylti-n mercaptopropiona~e, dibutyltin didodecylmercaptide, dibutyltin bis (isoctylthioglycolate), and the like. Representative tertiary organic amine catalysts are triethylamlne, triethylenediamine, N,N,N',N'-tetramethylethylenediamine, N,N,NI,N'-tetraethylethylenediamine, N-methylmorpholine, N-ethylmorpholine, N,N,N',N'-tetramethylguanidine, N,N,N',N'-tetramethyl-1,3-butanediamine, N,N dimethylethanolamine, N,N-diethylethanolamine, N,N-dimethylcyclohexylamine, and the like, and mixtures of the abave in any combination.
The preferred catalysts are the organo metallic compounds and particularly the d~alkyl tin salts such as the dibutyltin compounds noted above.
The amount of catalyst employed in any given situation will de pend upon the nature of the other components of the mixture and the desired reaction times. Generally speaking, the catalyst is employed w~th~n a range of about 0.01% by weight to about 5g by weight and preferably from about 0.02 to about 3% by weight based on total weight of the reaction mixture.
In addition to the various reaction components discussed above ,,;

.

. . . :
.
. :

9~

and used in the process of the invention there can also be introduced into the reaction mixture other optional addi~ives such as dispersing agents, surfactants, flame retardants, pigments, reinforcing agents, fibers and the like in accordance wi~h procedures well known in the art.
In an optional embodiment of the invention it ls found that minor amounts ~up to about 1 equivalent per equivalents of the mixture of polyols (a) and (b)] of a low molecular weight cross-linking agent such as trime~hylolpropane, alkoxylated trimethylolpropane such as the adducts of trimethylolpropane with ethylene oxide, propylene oxide and the like, pentaerythritol and adduc~s thereof with ethylene oxide, propylene oxide and the like, can be included in the reaction mixture employed in preparation of the polyurethanes of the invention. The trihydric cross-linking agents are preferred. Senerally speaking, the cross-linking agent is introduced into the reaction mixture in the fonm of a blend with the other polyol components.
The process of the invention is of particular application in the preparation of non-cellular polyurethanes and, more particularly~ non-cellular polyurethanes having thermoplastic-like properties. However, i~ is also possible to utilize the process of the invention to prepare microcellular and cellular moldings by the incorporation of blowing agents into the reaction mixture. The blowing agent may be incorpor-ated into the reaction mixture in appropriate amsunts depending on the required density of the resulting molding. Any of the blowing agents known in the art can be employed lncludlng water and volatile inert organic liquids, preferably those having boiling points in the range of about 22C to about 35C. Illustrat~ve of such liquids are butane 9 hexane, heptane, methylene chloride, chloroForm, monofluorotrichloromethane, chlorodifluoromethane, dichlorodi~luoromethane, and the like. The blowing agents employed may also ~nclude compounds which decompose at temperatures above room temperature to liberate a gas such as nitrogen. Examples of such compounds are azo compounds .~ ;

~ -11- 4004 such as azoisobutyr~c acid ni~rile and the like.
The polyurethanes which are prepared in accordance with ~he in-vention have, for the most part, a two_phase morphology and are char-acterized by a mark~dly higher level of impact strength than has been achieved using single polyols of type (a) discussed above. In addi-tion, the polyurethanes prepared in accordance with the lnvent~on re-tain all the good structural s~rength properties prevlously associated with polyurethanes derived from single polyols of type ~a) even with-out postcure. The green strength of the material at demold is also good. These properties of the polyurethanes produced in accord~nce with the invention are highly advantageous and supplement the benefits already discussed above in regard to the ability to operate with a polyol-extender component which is completely miscible.
The following examples des~ribe the manner and process of making and using the invention and set forth the best mode contem-plated by the inventors o~ carrying out the invention but are not to be construed as limiting.
Example 1 A series of non-cellular polyurethanes was prepared using an Ad~iral Equipment Company 2000 HP RIM machine and employing two re-actant streams. Stream A in all cases was a liquid form of 4,4'-~methylenebis(phenyl isocyanate) in which a portion of ~he lsocyanate had been converted to carbodiimide (isocyanate equivalent = 143: pre-pared as described in U.S. Patent 3,384,653). Stream B was a com-pletely miscible blend of ethylene glycol, a polyoxyethylene polyoxy-propylene triol ~Polyol (a)] having molecular weight of 6,500 and ethylene ox~de content of 27% w/w (Thanol~ SF-6503: Texaco) and a polyoxyethylene polyoxypropylene diol ~Polyol ~b)] having a molecular welght of 1,000 and ethylene oxlde content of 47X w/w (Poly~ G55-112:
Olin). The proportlons (all parts by we~ght) of the three components in Stream B were varied and are recorded in TABLE I below. Stream B
also contained 0.15 parts~ per 100 par~s, of dibutylt1n dilaurate catalyst (M and T: T-12). Streams A and B were brought together and mixed in the appropr~ate proport~ons to achieve the NC0/OH ~ndices shown in TABLE I.
Stream A was ma~ntained at 27C and Stream B at 49C. The mold (16 ~nches x 60 Inches x 0.150 ~nches) was preheated to 66C. The demold time was 1.5 minutes in all cases and samples of the demolded .,.; .

, ~.~

~75~

materials were submitted to physical testing. Additional samples of the same materials were postcured at 121C for 1 hour and then sub-mitted to physical testing. The properties determined on the mater-ials which were not postcured are shown in TABLE I and those of the postcured samples are shown in TABLE IA.

~:~7~

TABLE I

o ,~ o L') ~ a~ L'') L ~ a_, _, !~ z L'i~ r~ . 1-- 0 r I (~1 --~ r l O
~_1 O .-1 0 0 e~ O ~
. ~ ~ ~ ~ O
.-1 ul O o o o ~ ~ o~ O E~ O~
_I L~ ) 1` ~ . . . 11'1 ' N
L'l~r1''1 ' ~ N ~ ~D o ~`1 _ _ L ~ O ~ _~ ~ . . .L') ~ L') ~, ~ L ~ o O ~D O O OCS~ O t~lL'l 1-- L'~
r` ~.:1. 0 --I C'` ~, "` ~L'l C~ ~ ~7 .

r ~ ~r L _I O L') O C~ t'q r~ N O~ CO
L~ ~~`I o ~, L" O ~9 0 2 0 L'7 - - ~

i~Nri ~ r~ r-l O
_~ r~ ~ O

1~ ~ N O ~ O O 10 r t O ~ C~
r~ N r~ ~r1 7 N ~ N ~ N O

CO ~ L~ Ln N ~ N a:l __ _ N r~ r~
c c a .rl L~ V 1 ~ r~ CO ~ Ul O U~ U~

.rl U V rl :~ J r~ = I ~I rl 3 0 o ~â ~ G~ u ~ a ~ (a ~ ~ ~ J ~ C ~
U _ _~ ~ Ul U~~ ~ C ~ O N C Cl ~ Cl r ~ ~ C ~ ~ u~ ~ o oP ~ ~ s_~
8 ,~ C o ~ ~ ~ O ~ ~ _ V O O
O O ~ ~ ~ ul ~I,q VC .1.~ ~e 1` X .~J U ~ ~ ~J O
~ ~ P Ll o ~ c~ u aJ~ a v ~ u r ~a u~
U~ ¦ Z P~ C~ 4 Z ~ ~U) cO I

... . . . - ; ' : :

:
.
.

-14- 4no4 TABLE IA

S Inu~ o In ` r~ ~ _( O E~
O . r~ N I n ~ N a ) Z O
_~
O
7o_( ~O _I
~n ~r r,. ' r~ U ~ N N 1` t'' ~ ZO
. u~ r~ o ,o In er ~'o u~ D O N O E I ~
o~ ~ ~ ~ _~ ~n ~ Z O

o r~ ~ ~O~ OU~U~ O C~ O
~D ~ N . ~ N N~ .D N O
_1~
a) o o .4 1~ ~1 ~r O ~ o (~1 1~ ~ N O _I O ~ _~
o ~ ~'7 ~ . ~ ~ N ~ ~ ~ ~ N '.9 N O
~1 U7 O
r r~ ~~ N O O O CO N O N
O I~ O
__ _ _ o 7 a~ .-1 N ~'7 11~ ~ N ~ e ~ O O N
N~1. ~ . N Lt~ ~
O
oell O O ~U ~ 1 0 N ~1 I` N ~~ ~ co N ~ cr N O
N ~t r-~
~r o o o ~_rr)xO ~ o co InO ~ O N O O ~D
r-- N--I ' ~ 1` ~ ~9 0 N _ _ -- --O
_I ~ O J~ U~
~7 ~ a 5 ~ N ~ .0 3 0 3 . ~v~ x ~ o Q~ h U~ 17 a~ ~ U~ ~ `U7Ll ~ U~ o ~~ C
C C C) V`V~ ~ O OP 4 rl 1-~ .r1 E l 1;: - 5 ~L7 O O -J JJ ''~ 3 ~7 ~ 7 a~ ~
e ~ ~ ~ r7 ~ o~ o ~
a~C4 ~ 7 0 O C ~ C '~ o ,~ ~Ç O X ~ O
U~ Z~: G "~ N ~E~ æ ~ ~ a) ~ N

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5~9~
-15- 40n4 Footnotes to TABLE I and TABLE IA
_ _ _ _ _ 1: ASTM D-792 2: ASTM D-2240 3: ASTM D-412 4: ASTM D-790 5: ASTM D-256 ~: ASTM D-624 7: ASTM D-1938 8: Test CTZ006A: General Motors, Chevrolet Division Example _ The procedure described in Example 1 was repeated with the same Stream A but a Stream B (completely miscible) which had the following components in the proportions shown in TABLE II below (all parts by weight).
Polyol (a) = polyoxyethylene polyoxypropylene triol having a molesular weight of 6,500 and an ethylene oxide content of 29.4% w/w.
Polyol (b) = polyoxyethylene polyoxypropylene triol having a molecular weight of 1,000 and an ethylene oxide content of 49% w/w.
Stream A was maintained at 24C, Stream B at 27C. Mold temper ature was 80-82CC. Demold time and postcure conditions were the same as in Example 1. Streams A and B were mixed in the appropriate pro-portions to achieve the NCO/OH indices noted in TABLE II.
There was thus obtained a series of non-cellular polyurethanes having high impact strength and high flexural modulus as evidenced by the physical properties shown in TABLE II where the properties of the postcured samples (250F/1 hr.) are shown.

,., -16- ~7~ 4no4 TABLE II
Stream B Composition . _ _ Polyol (a) % EO 29.4 50 50 50 Polyol (b) ~0 EO 49 50 50 50 Ethylene glycol 45 45 45 T-12 0.15 n.15 0.15 NCO/OH index 0.99 1,03 1.05 Density g./cc. 1.13 1.11 1.11 Hardness, Shore D 78 80 79 Tensile strength: psi5~420 5,390 5,530 Elongation at break: %120 100 80 Flexural modulus: psi ~75F 216,100 212,500 216,400 20F N.T. 362,100 N.T.
+158F N.T. 80,020 N,T.
Ratio modulus -20F/158FN.T, 4,5 N.T.
Notched Izod impact:
ft. lb,~in.: 75F 15.~ 7.0 5.9 Heat sag: inches 4" overhang: 250F/1 hr. 0.17 0.06 0,04 Example 3 The experiments described in Example 2 were repeated exactly as described with the 501e exception that 3 parts by weight, per 100 parts of Stream B, of a cross-linker (adduct of propylene oxide and glycerin; equiv. wt, = 89) were added to one series and 6 parts by weight, per 100 parts of Stream B, of the same cross-linker were added in the second series. The physical properties of the postcured sa~-ples (non-postcured properties in parentheses) of the polyurethanes so obtained are set forth in TA8LE III below.

, ~

. ~ ' ~L~75~
-17- 4()O4 TABLE III

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o fi ~ x ~ o ~ v o ~,7~it3~4 ~ 4004 Example _ Using exactly the procedure described in Example 2 and employing the same Stream A but replacing Stream B by a completely miscible stream of the following composition (all parts by weight) (the amount 5 or polyol (b) employed was just sufficient to achieve complete ~isci-bility of Stream B):
Polyol (a) (same as Example 1) : 61 Polyol (b) (polyoxyethylene polyoxypropylene glycol M.W. = 1,000: Ethylene oxide content 52X w/w: Formrez EPD-112:
Witco) : 39 Ethylene glycol : 32 T-12 : 0Oo75 there was obtained a non-cellular polyurethane having the properties shown as Run 4-1 in TABLE IV. The two streams were employed in the proportion of 173 parts oF Stream A per 132 parts of Stream B for an NC0 index of 1.05. For purposes of comparison the above experiment was repeated but replacing the above polyol (b) by two other polyols, one of which was on the upper limit of the definition of polyol (b) 20 which can be employed in accordance with the invention, and the other of which is outside the limit of parameters of polyol (b3 which can be employed in the process of the invention. Both polyols were employed in proportions such that the ethylene glycol employed was just mlsci-ble in the Stream B. The composition of Stream B in these two com-25 parison runs was as follows.
Run No. 4-2 -Polyol (a) (same as Example 1) : 28 Polyol tb) (polyoxyethylene polyoxypropylene glycol: M.W. = 2,000: EØ content 3~ = 49.6% wlw) : 72 Ethylene glycol : 32 Run No. 4_3 _ __ _ Polyol ta) (same as Example 1) : 47 Polyol (b) (polyoxyethylene polyoxypropylene glycol: M.W. = 512: EØ content - 47.2% w/w) : 53 Ethylene glycol : 32 ; The properties of the samples prepared from the above Streams B are ~S~g4L

also shown in TABLE IV. It will be seen that those of Run 4-2 are somewhat lower in tensile strength properties and significantly lower in flexural modulus while those of Run 4-3 are significantly lower in both tensile strength and flexural modulus.
TABLE IV
Run 4-1 4-2 4-3 Density g./cc. : 0.89 0.99 0,86 Hardness, Shore D : 73 70 77 Tensile Strength: psi : 2,475 2,250 1,275 Elongation at break: 7O : llS 60 <5 Flexural modulus: psi : 115,830 68,476 90,313 Heat sag: inches 4" overhang: 250F/1 hr.: 0.08 0.05 ---Example 5 U5i ng the same procedure and reactants as set forth in Example 1 but varying the proportions of polyols (a) and (b) (same materials as used in Example 1) there was prepared a series of non-cellular poly-urethanes, all at an NC0 index of 1.01. The various proportions of 20 reactants (all parts by weight) and the physical properties of the polyurethanes so obtained are set forth in TABLE V below. It will be noted that in all cases the ethylene glycol extender was miscible with the polyol component. However, in the case in which the polyol (b) was employed alone, i.e., in the absence of any polyol (a) the impact 25 strength of the polyurethane, as shown by the Notched Izod value was dramatically less than that of the polyurethanes in which polyol ~a) was employed. It was also noted that the polyurethane in which the higher content of polyol (a) was employed was possessed of ~he higher impact strength.

-20~ 3~ 4004 TABLE V
Polyol (a) 0 25 40 Polyol (b) 100 75 60 Ethylene glycol 42.32 42.32 42.32 Density g./cc l.097 0.983 l.027 Hardness, Shore D 80 78 76 Flexural modulus (70F): psi 339.2 2ll.3 1~2.2 Flexural strength: psill,190 7,640 7,080 Tensile strength: psi 5,380 4,390 4,560 Elongation at break % 80 140 170 Tensile set % 40 N.T. N.T.
Notched Izod Impact lb/in.: 75F 0.89 3.72 5.61 Heat sag: inches 4" overhang: 250F/1 hr. 0.19 0.185 0.18 Example 6 It was found that by using a blend of 76.5 parts by weight of the polyol (a) employed in Example 1 and 23.5 parts by weight of the poly-ol (b) employed in Example 1 but having a content of 45% w/w of ethyl-ene oxide, it was possible to incorporate a maximum of 19.0 parts by weight of ethylene glycol and still obtain a completely miscible mix-ture. The blend of polyols (a) and (b) employed had an average ethyl-ene oxide content of 31.3% w/w~ Accordingly, a single polyoxyethylene polyoxypropylene polyol having the same ethylene oxide content (3103Yo w/w) was tested for ability to form a miscible blend with ethylene glycol. It was found that only 10 parts by weight of ethylene glycol could be blended with this polyol before the mixture separated into two phases.

.

.

Claims

1. In a process for the preparation of a polyurethane by reaction of an organic polyisocyanate, a polyol and low molecular weight aliphatic glycol extender, the improvement which comprises employing as the polyol component a mixture which comprises:
(a) a polyoxypropylene polyoxyethylene polyol having an average functionality from 2 to 4, a molecular weight in the range of about 3,000 to about 10,000 and con-taining at least 23% by weight of ethylene oxide residues; and (b) a polyoxypropylene polyoxyethylene polyol having an average functionality from 2 to 4, a molecular weight in the range of about 750 to about 2,0no and containing at least 45% by weight of ethylene oxide;
the proportions by weight of the components (a) and (b) being adjusted so that the aliphatic glycol extender is completely miscible with said mixture of components (a) and (b).

2. A process in accordance with Claim 1 wherein the aliphatic glycol extender is ethylene glycol.

3. A process in accordance with Claim 2 wherein the components (a) and (b) are employed in a ratio by weight of from 0.10 to 4.0 parts of the component (b) per part of the component (a).

4. A process according to Claim 1 which is carried out using a re-action injection molding technique and employing as the polyol com-ponent a blend of a low molecular weight aliphatic glycol extender and a mixture which comprises:
(a) a polyoxypropylene polyoxyethylene triol having a molecular weight in the range of about 3,000 to about 10,000 containing at least 23% by weight of ethylene oxide residues, and (b) a polyoxypropylene polyoxyethylene diol having a molecular weight in the range of about 750 to about 2,000 and containing at least 45% by weight of ethylene oxide;

the proportions by weight of the components (a) and (b) being adjusted so that the aliphatic glycol extender is completely miscible with said mixture of components (a) and (b).

5. A process in accordance with any of claims 1 to 3 wherein the organic polyisocyanate is 4,4'-methylenebis-(phenyl isocyanate).

6. A process in accordance with claim 4 wherein the organic polyisocyanate is 4,4'-methylenebis(phenyl isocyanate).

7. A process in accordance with any of claims 1 to 3 wherein the organic polyisocyanate is 4,4'-methylenebis-(phenyl isocyanate), in a form which is a liquid at 15°C.

8. A process in accordance with claim 4 wherein the organic polyisocyanate is 4,4'-methylenebis(phenyl isocyanate), in a form which is a liquid at 15°C.

9. A process in accordance with claim 4 wherein component (a) has a molecular weight of about 6,500 and contains approxi-mately 27% by weight of ethylene oxide residues and component (b) has a molecular weight of about 1,000 and contains approximately 50% by weight of ethylene oxide residues.

10. A process according to claim 4 wherein the polyol component contains from 5 to 50 parts by weight of aliphatic glycol extender.

11. A process according to claim 4 wherein the polyol component contains from 7.5 to 25 parts by weight of aliphatic glycol extender.

12. A process according to claims 4, 10 or 11 wherein the aliphatic glycol extender is ethylene glycol.