Note: Descriptions are shown in the official language in which they were submitted.
BACI~GI~OUND OF THI~ INVENTION
In general, ease bonded solicl propellQnt grains possess g1eaier strenE,-th
beeause of the additional support given by tlleir adherenee to the rocket motor
CaSillg i21 WhiCIl tlley are eontainecl. To insure the lMa~imum strength ancl to
prevcnt separation of the propellant grain Lrom tlle motor walls wl-ieh woulcl
create voids alld therefore a potential for uneven burning, it is clesir,ll~le that
- the propellant graill be bonded to the motor casing uniformly and firmly.
This is usually aecomplished by very careful cleaning ~uld clescaling Or
the inside surrace of the metal motor casing, îollowecl by eoating tlle insicle
surl`ace with a liner, normally the binder used for tlie propellant graill, then
casting tlle propellant grain in plaee and euring. Tlle liner serves as a bonclil-g
ag,CIlt l)CtWCCII Ll~c C.'lSillg alld tlle propellallli: graill, as all inhibito3 prcvclltillg
burllillg dowll tlle outer surfaee Or the grain and as an ins-llator, proteetillg tlle
casing from the hcat alld gases of combusLion when burning has progresse(l to
tlle point at ~vhicll thc c~sin~ ~voulcl other~visc be ~xpo~;etl.
Tlle prest nt inventioll relates to case lincrs contailling ~ziricline
compounds metllods for their formulatioll and use. The liners are formulatecl
from hydroxy terminated polybutadiene based polyurethalle binders.
U. S. Patent 3, ~7~L,131 issued August 10 197(;, is rt?late(l to thc usc
of vnrious acrylated aziridinyl mol~omers ancl polyniers and their use as n(lllesivt?
promoters in vinyl rormulations. The compounds contemplated for use in lhis
invention are intended for use in enhancing the adhesivelless of polyurethnnes.
SUl\ll\lAI~ OF TIII~ INVENTION
The invention provides a composition of matter ~vhich comprises a
liquid llydroxy terminated polybutadiene and an a%iridine.
The tangil~le embodunents of this composition aspect o~ the invt ntioll
posscss the inhorellt.appliecl use characteristic of bcing curable with diisoc~an.l~c
curing agents to produce solids which are suitable for use as casing liners in
case bonded solid fuel rocket motors. t ' ' ` '
Particularly preferred embodiments of this composition aspect of tlle
invention are those wherein the aziridine is selected from:
- Trimesoyl-1- (2 - ethyl -aziridine)
Bis-,isophtllaloyl-1-(2-1nethyl)-aziridine,
Bis-isosebacoyl-1-(2-etllyl)-aziridine,
Bis-isosebacoyl-l-azlri(line,
Tri- [-1- (2-methyl)-aziridillyl] -Phosphine oxide
Bis-L1-(2-methyl)-aziridinyl]-ethyl sulfone, or
polyfunctiollal aziridines PFAZ300 or PFAZ301-suppliecl by Iollac Chemical
.
Comp:llly I3irmingllam New Jersey.
The invention also provides a process for case bonding a hyclro~;y
tormillntctl polybutnclielle basecl polyuretllant bound solicl propellnllt grain to
a rocl;cl l~otor casin~ wllicl~ comprises:
n) linillg a rochel motor casing to wl~icll it is desired to cnsc
bolld saicl propellallt grnill witll a cured lincr comprising all a%iriclin(? ancl a
f~
,. !. .
llyclro~iy tcr~ laLetl polyb~ltnclicno cul~ccl ~vitl- a polyisocynllnte CUl'illg ~ Ilt
and;
b) CaStilig said hyclrox5~ terminatetl polybutacliene based propellant
grnin in nn ullcured form in tlle clesiled configulation into said linecl rocl~ct
motor; ancl
c) curing said propellant grain.
The in~clltion also provides all improved ease bonded solid propellnnt
rocket n~otor containing a hydro~-y termillated polybutadiene b~sed polyuretllane
bo~uld propellallt g1ain wllerein tlle improvement comprises the incolporntioll Or
an aziricline into tlle casing liller of saicl rocket motor. :
D~SCI~lPTION OF ~rlll~ PRI~F1~,~RI~:D EMBODII\IE::~TS
.
'1`1le practice Or tlle invention vill llOW be illustratQd ~vitll ref~lc-~llccl to a
speciric embodin~ellt tllereof, namely a rocket motor casing liner comprisillg
the hydro~y terminated polybutadiene based polyuretllane l)inder having thc
trade designatioll R-45M and the aziridinc, trimesoyl-1-(2-etllyl)-aziriclillc.
Tlle llydro~y terminatcd polybutadiellc polymer 1~ 5~I is sold by Arco
Cllemicnl Colllpnlly alld its structure may be representecl as:
/ C~I=CII\
I-IO--~CI12 C112) o 2 ~CIl2-fM) (cH2-cH=cll-cll2) 0 ~ --OI[
2 0 C H=C II2
The R-~5M is blcnded ~Vitll tlle trimesoyl-1-(2-ethyl)-aziridille, a
eonventional diisoeynnate euring agent, convenielltly DDI, a C3G licluid alipll;llic
diisocymlatc sold by General Mills, and, if desired, ol1e or more fillers SUCII
as carboll black. Tlle l)lended compositioll is vàci~um degassecl and cast ns n lincr
into a previously desealecl and degreased steel rocl;et motor CaSin ancl curccl ~t
c~]cvntc(l lcml)c~ o :Erom (il~ollt 1~l5F t.o al~out 200F. After CU~C or p.lltinl Cll1C
i.s colnplclc a llyclro~y tcr~ lntcd polybutndiellc basccl propellIlnt g,rnill~ S-IC~ s, IOr
c~;amplc, a propcllant consisling of ~ 5~ ns a binclcl rnnging from 81/2 lo al)o~lt
2-1-% l~y wciollt nnd incluclillg SUCII COnVelltiOIlnl COnlpOUlldillg ingredielltS .lS diocly
:~o adipatc as a plasticizer, a polyisocyanate curing agent sucll as isopllorolle
93~7';~
~iisocy.lllate or the al)o~c mentiollcd DI:~I up to abollt 2(ii, l)y wci~,rht, al) o~idi~Ac
sllcll as, ammolli~lm pcrclllolate u~ to 75 to 90'~,. b~ ciL~I~l, if dcsilc(l, ~ oriio
of metallic fuel such as aluuninum metal, and othel conventiollal coml~ustion
stabili; ers, ilanle coolants alld tl~e like may be cast nncl c~recl in l~lacc ill tllc
lined motor in conventional fashion.
In addition to the R-45M l~inder specifically illustrated herein, it ~\!ill bc
obvious to one skilled in the art that any liquid hydroxy terminated polybutadicl1e
polymer lulown to be uscful for propellant grain bindin~ will bc applic.lblc in lhe
invention. Illustrati~re of these polymers are, for example, those sold under thc -:
trade desienations R-45HT, R-15M, CS-15, by Arco Chemical Company, and
Butarez HTS by Phillips Petroleum Company. It will similarly be eYklellt to
one skilled in the art that in addition to the DDI illustrated herein any poly-
isocyanate may bc used to effect cure of the binder. Illustrati-~e of other suitnblc
polyisocyanates are, Eor example, isophorone diisocyanate, hexamethylenc
diisocyanate, PAPI polymeric diisocyanates sold by the l~pjolm Company and
Desmodule N-100 a polyisocyanate sold by I. G. Farben Industries, and also
such isocyanates as: 1-methoxyphenyl-2, 4-diisocyanate, 1 methyl-4-metllo.~y-
phenyl-2,5-diisocyanate, 1-ethoxyphenyl-2,1-diisocyanate, 1,3-dimethoxypllenyl-
4,~-diisocy~late, 1,4-dimethoxyphenyl-2,5-diisocyallate, 1-propoxyphenyl-2,4-
20 diisocyanate, 1-isobutoxy-2, 4-diisocyanate, 1, 4-diethoxyphenyl-2, 5-diisocyallntc,
toluene-2,4-diisocyanate, toluene-2,G-diisocy~ulate, diphenyletller-2?4-diisocy ~ atc,
naphthalellc-1,4-diisocyanate, 1,1'-dinaplltllalcne-2,2'-diisocyanate, bipllcnyl-2,4-
diisocyanate, 3,3'-dimethylbipllenyl-~,4'-diisocyanate, 3,3'-dimethoAybipllellyl-~,4'-
diisocy~nate, cliphenylmetllalle-4,4'-diisocyanate, diphenylmethane-2,d~'-diisocyanate,
dipllellylmetllane-2, 2 ' -diisocyanate, 3, 3 ' -dimetho~y diphenylmethane-4, ~ ' -
diisocyanate, ben~ophenolle-3,3'-diisocyanate, ethylene diisocyanate, propylene
diisocyanate, b~ rlcne diisocy~nate, pelltylellc diisocyannte, metllyll~-ltylcnc di-
isocyanntc, tctr,llllctllylelle diisocyallate, pentametllylcne ùiisocyan;ltc, dil~ropyl
diisocymlntc ethcr, hel)t~llletllylene diisocyallate, 2,2-dimctllylpelltylene di-.
isocyanatc9 3-methoxy-llcxametllylene diisocyanate, octamethylcnè diisocyanatc,
. ,. *.,".
L~'19~74
2"2, l~ imctlly1pentylenc cliisocy.~ lc, 3~ loxylle~ mctllylelle ~li;socynll.lte,
1,3-din ctllylbc~ .cne diisocynllnlc, l,~,!-dimet,!lyl ben%elle cliisocyanatcl, 1"'-
dim etllyleyelohexnlle diisoeynnate, l,4-dim etllyleyclolle~.me dlisoey.lllnte,
1,~L-dim etl~ylbellzene cliisoeyanate, 1,4-dim ctllylnaphtllnlelle diisocyannte,
1,5-dim et]lylnaplltllalene diisocyanate, eyelohexane-1,3-diisoeyanate, eyelo-
he~Ynne-l, ~-i-cliisooyanate, I.-methylcycloh(3xane-2, 4-diisocyallnte, l-methyl- .':
eyelo1lexane,-2,2-tliisoeyal^~ate, 1-etllyleyelollexane-2,4-diisoeyanate, dieyelo-
hexylm ethane-~-L,~ diisoeyanate, dieyelohexylm ethylm et,hnne-4,~,!-cliisocyallate,
dicyclollexyldimetllylllletllalle-4, 41-diisocyanate, 2, 2-climethyldicyolollexyl-
m ethane-4,4'-~iisoeyanate, 3,3',5,5'-tetramethyldieyelollexylm elhalle-4~4~-
diisoeyanate, 4,4'-m ethylenebis (eyelohexylisoeyanate), ethyli(lelle cliisoeynnnte,
4,~,!'-dipllollyl diisoeyannte, clianisidine diisoeyanate, 1,5-nalphtllalene diisoeynna~c,
m -pllenylelle cliisoeyanate, isopropylidene bis (pllenyl or eyelohexyl isoeyallnte),
1,3-eyelopentylelle diisoeyanate, 1,2-eyelohexylene diisoeyanate 1,4-eyclo-
hexylelle diisocyanate, 4,4',4" triphenylm ethane triisoeyanate, 1-,3,5-tri-
isocynnate benzene, phenyletllylene diisocyanate, and the lilce.
It will also be apparentto one slcilled in tlle art thatin addiLiollto
trim esoyl-1-(2-etllyl) aziridine illustrated herein otller aæiridines will be full
ecluivalents for tile purposes of this invention. Illustrative ofthese are, lor
exmnple, tris-2,4,~-(1-nziridillyl)-1,3,5-triazine, bis-isopllthnloyl-1-
(2-etllyl)-nziridille, bis isosc-.~bncoyl-1-a%iridille, tl~i-[1-(2-m ethyl)-nzilidillo~
pllosplline oxide, bis-[1-(2-m etllyl)-aziridinyl] etllyl s-llfone, polyIunctiollal
a%iridines sold under the trade desigllations P F~%300, PFA Z301 by lonnc
Chemical Com pany, and the like. It will also be apparentthatill addition to
the earb,on ~laclcillust1ated herein as being optionally em ploye(l as a filler
otller m aterials will be suitable ,for ~Ise as fillers alld m ay also optionally be
em ployecl sin~rly or in eombination witll enell other Ol witll cnrbon blaclc.
Illustr.ltive oftllese nre: titanium dioxide, silicon dioxide, silicn, alumin-un
oxicle, milled ~rlass, and al~mlino silicate clays.
The azilidilles ofthe inventioll m ay be incorporatecl at frolll a~o~lt 1 tt`~
10r,o by weigllt ofthe total wei~lt oEthe liner mix. Rreferahly they m ay he
f
illC()l ~ tc(~ 10111 ;ll~ollt ~ to 8 J~" collvo;licl-tly .~ t (; ~1 I)y ~ci,~ll( Or
total.
rrhe following cx.unple ~urtller illustrates the best mo(le conte]nplntctl by
the inventors Ior the pr~ctic~ of their inveDtion. ..
, ': '
'
, ;, "
EXAMPL~
T]le ro]lowing l~ mple ill-lstrates the pre,~ ration Or a typic~l ~iner
eomposition Usillg tlle aclhesion enll.alleers Or the invention.
To R-45M' (~L1. 85 weigllt %) is adclecl VDI (12.15 wei~,rllt %) trimesoyl-l-
(2-el;llyl)-aziridine (G. 0 weigllt %) ancl earbon blael; (40. 0 weigllt qO)~ tlle a~iritlille,
I)ein~ moltocl prior to adcliLion and tlle el~tire mi~cture l~londecl C~r ai~out 45 millulcs ,:
and then degassed by eonvenlional teehniques sucll as vaeuum mi~;ing Ol` slit
deaeration. The mix is then east by standard proeedures and curecl at 170F for
9G to lG8 hours~ Tlle normal tlliekuess obtained in one applieation to a motor
10 easing is from L/32 to 1/lCi ineh.
Typie.al pllysieal properties obtainetl from e~lrecl samples of tlle mi~; are
as follo~vs:
Tensile Strengtll (~STM D 412)
Test Temp. (F)
0 77 150 ~ 200
Stress,, Ultimate ~psi) 1,0~13 543 331 258
Strain, Ultimate ~0) 4G4 431 324 282
Stress-100~'0 Strail1 (psi) --- 118 --- ___
Stross-300~/0 Strairl (psi~ --- 379 --- ---
20 Stress-500~/o Straill (psi) ' --- 509 --- ---
Tear Stren~,tll, pli --- 111 --- ---
I-lardness (Sllore A at Aml)ient Temperature) 52
,, Agein~ Properties (Test at 77F)
A~,eing Tempelatllre 130F Ag,eill~ Temperaturo 1~0F
~gcin~r Time (~Vcehs) Ult. Stress Ult. Stlàin IJlt. Stress Ult. Strai
0 501 389 50L 389
2 ,513 325 7~l -l~l (;
~l 548 33D 847 l21
8 (i30 2G7 878 13(;
3012 589 :L~;I 8(;1 l~
9~74
rl'yl~icQl 130~ Prol)cl lics
S~mplt s of tl~e above mix ~vcre curod o~l stet~l SUl f lct s ~ it l)l lsk cl ~ncl
vapor dc~re~scd or were cured nncl typical propellQnt nncl insul ~lion m~tt3ri.ll
formulaliolls curctl on tlle liner surfacc. Ternsile ndllesioll nlld r~eel strtmgtlls
~vere tllell determilled Witll tl~e results sho~ vl~icl~ mny be colnpart3cl to (i~') pli
pcel slrellgth, witll tllin co~t of propcllmll; fnilurc ror tlle bond ~t nmbient
temperaturc (77F) betwee- n similar propellant and liner formulntions ~itllout
aziridine where tlle liner is not fully cured prior to cure of propt31lnnts nll(l . -
3-G pli ~vllcre t]le liner is fully curcd prior to propellant additioll. -
Adjace-ntIcst Te~llp. Tensile~ Peel (pli)
'
Tyl:~o Or
I\Interi~l (I~) Loadlype of I~nil~roInitial ~crngo I nil~
Stecl -(;5 1 333 2-Liner 7197.3 --- 3-rl`~b
1-Plnte 13ent Brol;e
77 2~i9. 3 3-Liner 43.0 35.7 3-T]lin Conl
Liner
lG5 18L.7 3-Thin Coat13.8 lG.0 3-11lill Coat
Liner Liner
200 170.7 3-T]lill Coat2 7. 3 15.7 3-T]liil Cont
Liner Liner
250 lG0.0 3-Liner 25.5 14.5 2-Linc r Pulled
,~ from Shim
1-Tllin Coat
Liner
300 117. 7 3-Liner 17. G 10. (; 3-Lincl I'ullcd
rrolll Slli
Asbestos filled -G5 1 58G 2-Thin Coat of 75.5 105. 0 2-insul.-1tit)ll
1'olyisoplenc Liner l-Tllill Cont
l~ul)l)t l- l3nscd l-insulntioll of Lillc
Illsul~tioll
77 lG3. 0 3-Tllin Coat ` 1~l.0 lG.1 5-Boncl
of Liner ` ~ ~
lG5 103.0 3-Thill Coat 4. 0 9.1 3-Tllill Cont
of Liner of Lincr
20() l07.5 2-TIlin Conl iL.;I 7.~ .3-rll~in Cont
of Lincr of lincr
250 12G.3 3-T]lin Coat 12.4 l2.~i 2- Illin Conts of
of Line1 Lincr-1 -rl l~in Co l t
Or l,inc!r, nlltl l,incr
~ullcd frolll Sllim
r ~ ~
ljaccllt 'l'cst 'lclllp. 'l'cllsilc Adlls~sioll (pli) :Peol (pli~ __
I yl!c of
~sbcstos filled 300 :L29. 0 2-'1'hill Coat of 12. 7 11,1 2-'rllin Co;tt Or
Pt)lyisoprcllc ' Liner-l-Liner I.inc
] ~ )cl ~3~ Sctl I - L;
Ills-tl ttion rl`O~ Sllilll
. .
1~5M 13;1sccl -(;5 808 2-'l'llin Coat 75. 0 ~9. 7 :3-'~'llin Co,ll
~llllllOlli~llll Propcll.allt . . Propell~llt
Pcrchloratc l-Thill Coat
Oxidizer Propellant &
Isopllorone Liner
diisocy;lnate
c~lred pro-
pellallt ** . . .
77 17G 3-Propellant 2~}. 5 ~}G. 1 :3~Lincr
1.~)5 ll~ 3-Propell.ant 25. ~ 27. 7 2-Lillcr
1~1 ol)(~ll,t
l-Lincr
** Linc~r precurccl 2~ ours ;It 1~5F.
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