CA1066829A - Molding particulate solids and sacrificial binders therefor - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
Improvements in molded articles from sinterable particulate solids, improvements in method for making such articles, and novel sacrificial binders for use in making such articles are disclosed. The sacrificial binders used in this invention comprise block polymers having the structural formula AB ?AB?n A
wherein "n" is 0 or a positive integer, "A" is a linear or branched polymer that is glassy or crystalline at room temperature and has its softening point in the range of about 80°C to about 250°C and "B" is a polymer different from A that behaves as an elastomer at processing tempera-tures, a plasticizer which may be oil, wax, or oil and wax, and optionally other components.

Description

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This invention relates to improved m~lded articles from sintered particulate solids and to methods and materials for producing articles from particulate materials which exhibit unusual physical integri~y in the green body stage and unusual dimensional precision as final products, i.e., after "burn-out" and sintering~ ln particular, this invention is concerned with articles produced by mixing particulate solids with a thermoplastic, sacrificial-binder - material, molding the article into its green body configura-tion, burning out the sacrificial-binder material and sinter-ing ~he particulate solids into a single solid mass, with methods for making such articles and to uni~ue sacrificial binders for use in making such articles. This invention is applicable to all particulate solids which are sinterable, as that term is hereinater de~ined.

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1 The sacrificial binders of this invention are thermo-

2 plastic a~d contain as the principal binder xesin a thermo-

3 plastic, rubber-related, klock polymer having the physical

4 properties hereinafter delineated, and the stxuctural formula AB ~AB~n A, wherein " n" is o or a positive integer, "A" is . .
6 a linear or branched polymer that is glassy ox crystal~ine 7 at room temperature and has its softening point in the range 8 of about 80~C. to about 250C. and "B~ i5 a polymer different in 9 chemical composition ~rom A that behaves as an elastomer at processing tempexatures. A detailed description of block polymers, 11 ~heir preparation, composition and physical properties are to be 12 found in "Synthe~is o~ Block Polymers by Homogeneous Anionic 13 Polymerization" by L. J. Fetters, Institute of Polymex Sciencet 14 The University of Akron, Akron, Ohio published in the Journal of Polymer Science, Part C, Mo. 26, pages 1-35 (1969) and 16 "Rubber-R~lated Polymers, I. Thermoplastic Elastomers'~ by 17 W. R~ ~endricks and R. J. Enders, Elasto~ers Technic~l Center, 18 Shell Development Company, Torxance, Cali~oxnia, publi~hed 19 in Rub~er Technology, Second Edition, Chapter 20, pages 515-533, by Van Nostrand Reinhold Company, New York, 21 Cincinnati, Toronto, London and Melbourne (1973), which 22 are incorporated herein by reference. For the details of 23 vacuum apparatus and method or performing anionic initiated 24 polymerizations which can be used to produce block polymers, see "Procedures for ~omogeneous Anionic Polymeriza~io~" by 26 Lewis J~ Fetters, ~ournal of Research of the National 27 Burèau of Standards, Vol. 70A, No. 5, September-Oct~ber 1966, 28 pages 4~1-433 and nThe Association of Polystyryllithiu~, -~6~8~:~

1 Polyisoprenyllithium, and Poly~utadienyllithium in ~ydrocarbon 2 Solvents," by ~aurice ~lorton, Lewis J. Fetters, R, A. Pett, and 3 J. F. Meier, Institute of Polymer Science, published in 4 Macromolecules, Vol. 3, pages 327~332, by the American Chemical Society (1970) which are herein incorporated ~y 6 xeference.
7 ~asically, the concept here involved provides or 8 makin~ sintered articles fro~ particulate solids employing g sacrificial binders which behave as thermoplastics during the processing, i.e., mixing and molding, in that they flow 11 readily at the temperatures used for these operations and 12 yet behave in the nature of thermosets during storage of the 13 green body at room temperature and during firing un-til the 14 sintered body has taken permanent form. This is achieved with the block polymer elastomers hereinbefore and 16 hereinafter more ~ully described and the oil or wax or 17 oil and wax used as plasticizer. The oil serves to aid 18 in processing by reducing the viscosity of t~e elastomer 19 which is of particular importance during the application of shear forces at mixing and molding temperatures. Thus, 21 when the tempçrature o~ the material is xaised above the 22 gla~s transition temperature of the block polymer 23 elastomer, l.e., the glas~ transition temperature of the 24 "A" segments of the block polymer, and shear forces are applied, the material becomes le~s ~iscous and flows like 2Ç a thermoplasticO When the system is cooled to room temperature ~27 after forming, the "A" se~ments, e.g., polystyrene, tend to 28 agglomerate to form "domains" and provide a structure similar ~6~g ;:
in physical behavior to a crosslinked polymer. Subsequent firing at a higher temperature drives off the oil and/or wax.
As no applied shear forces are presen-t during firing, the "A"
segmen-ts domains remain in their agglomerated form, thus maintaining the shape of the green body through burn-out and such shape is maintained through sintering by the integri~y of the structure of the residual particulate solids.
A. The Principal Binder Resin The principal binder resin is a thermoplastic block polymer having the structural formula AB ~ABt~ A
wherein "~" is 0 or a positive integer and "A" and "B" are different polymers. This block polymer advantageously comprises in excess of 50 wt. % of polymeric material in the binder excluding the oil and/or wax of the plasticizer. For purposes of simplicity, these polymers will be primarily discussed with ~ -reference to their most simple form wherein "~" is 0, i.e., a block polymer of the structural formula A-B-~. It is to be understood that the statements made about khese txiblock polymers apply equally to those block polymers wherein "~" LS one (1) or greater even though certain of the "A" segments will not be terminal and certain of the "B" segments will not be center segments.
The "A" se~ments of these block p~lymers are non-crosslinked, linear or branched polymers which are glassy or crystalline a~ room temperature and have their softening .
point in the range of about 80C. to about ~50C. When the D lded article is in the green body stage, i~e.~ after : .
~ormation and prior to burn-out of the sacrificial binder, and at ro~m t~ature, i.eO ~ 20-25C:., the "Ai' segments e~hibi~ a mK~us grea~er ~han 100 dynes~cm2 Whexe the block polymers are prepared b~ anlonic poly~leri-zati~n-, suitable

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1 materials for the "A" seg~ents include, but not by way of 2 limitation as one skillecl in the art will recognize 3 from the physical and chemical characteristics of these 4 and similar polymers, polystyrelle, poly(acrylonitrile), poly (p-bromostyrene), poly~methyl methacrylate), poly(alpha-

6 methylstyrene), poly(2-methyl-5-vinylpyridine~ and poly(4-

7 vinylpyridine). Other ~lock polymers ~3uitable ~or use

8 in this invention are advantag~ously prepared by other

9 synthesis routes, i.e., polycondensation, ree radical initiated polymerization and cationic polymerization using 11 techniques known to the art. When these other syntheses are 12 employed, ~uitable materials for the "A" segments include, 13 but not by way of limitation as one skilled in the art will 14 recognize from the physi~al and chemical characteristics of these and similar polymers, polytvinyl acetate~, polyesters, 16 . polyamides, polyurethanes, poly~vinyl chloride), 17 . polypropylene, polysulfone , poly(phenylene sulfide), poly (4-18 methyl pentene-l~ an~ poly(vinyl alcohol).
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lg . The "Bn~ ~egment of these ArB-A pol~mers are either rubbery, flexible t glassy or crystalline 21 polymers, as those terms are hereinafter defined~ and 22 behave as elastomers at processing ~emperatures~ The 23 "B" segment may be linear or branched and in some embodiments 24 is chemically crosslinkable. In such embodiments, a cross-linking agent therefor is added ~uring mixing and reacted on 26 molding. When the molded article is in the green body 27 s-tage and at room temperatuxe, it exhi~its a modulus of ~8 about 106 - 5 x 107 dynes/cm~ when the "B" segment is a : ` - 6 -.

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1 rubbery polymer. Where the "B" segment is a flexible 2 polymer,at room ten~perature, this modulus will be in the 3 range of about 107 - 109 dynes/cm2. W~ere the "B" segment 4 i5 a glassy or crystalline pol~ner at room temperature, this modulus will be above about 109 dynes/cm2. Where the block 6 polymers are prepared by anionic polymerization, suitable 7 materials for ~he "B" segments include, but not by way of 8 limitation as one skilled in the art will recognize from the 9 physical and chemical characteristics of these and si~ilar polymers, polybutadiene, polyisoprene, polydimethylbutadiene, 11 poly~ethylene oxide~, poly(isopropyl acrylate), poly(octamethyl- -12 cyclotetrasiloxane), and poly (tetrahydrofuran). As afore-13 mentioned, block polymers suitable for use in this invention 14 are advantageously prepared by other synthesis routes, i.e., pGlycondensation, free radical initiated polymerization 1~ and cationic polymeriza~ion. When these other synthese~ are 17 employed, suitable materials for the "B" segments include, 18 but not by way of limitation as one ~killed in the art will 19 recognize from the physical and chemical characteristic~ of these and similar polymers, polyisobutylene, ethylene propylene 21 rubber, ethylene propylene diene terpolymers, butyl rubber, 22 chlorobutyl rubber, bromobutyl rubber, chlorosulfonated 23 polyethylene, epichlorohydrin rubber, fluorocarbon rubbers, 24 sllicone elastomers, e.g., polydimethylsiloxane, polyurethane 2S elastomers and polypropylene oxide elastomers.
26 The molecular weight~ of the "A~ segmentæ and 27 the ~'B'1 seg~ents of tha block poly~ers suitable for use 28 with this in~ention will vsry with the polymer segLent - ~066~
1 involved as will be obvious to one skilled in ~he ar~ in 2 that physical characteristics must be ~et as hereinbeore 3 recited. For instance, where the block polymer has polystyrene 4 "A" blocks and polybutadiene "B" blocks, the polystyrene segments advantageously have molecular weights below about 6 20,000 and at least two of such segments have molecular 7 weights above about 10,000 whereas the polybutadiene 8 segment or segments advantageously hav~ molecular weight 9 or weights below about B0,Q00 and at least one such segment has molecular weight above about 40,00~. The lower 11 limit of molecular weight for the two "A'/ blocks is g~verned 12 by the minimum "A" block chain length required to insure 13 the formation of a heterogeneous phase while the upper 14 limit of "A" blocks is set by the viscosity of both "A" and "B" blocks when such viscosity begins to hamper 16 domain formation or processing.
17 To mix the block polymer with either of the other 18 component~ of the sacrificial binder or wi~h the particulate 19 solids~ the block polymer must be heated to the softening point of the "A" segments or above. On~e the blGck polymer 21 has been mixed with the other components o the sacrificial 22 binder, the oil and/or wax can ser~e as a pl~tici~er and 23 permit subsequent working, e.g., mQlding, etc., at a 24 temperature below the softening point sf the "A" segmentsO
~25 The lower temperature limitations for such working wiLl 26 depend upon the chemical composition o~ the "A" segments, the 27 degree to which they are plasticized and the plasticization 28 ~qualities of the plasticizerr In all cases, however9 the 29 lower limit ~f the working temp ratures for such bi~ders will be a~ove the temperature at which the 'IB" segments of the : ' : .

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l block polymers cease to behave as elastomers. In general, 2 the mixing temperature is advantageously in the range 3 between about 15C. below the softeniIIg point of the "A"
4 segments o~ block polymer use~ and about 70C. above such S sotening point, except where mixing iLs carried out in 6 the absence of gaseous oxygen in which case the temperature 7 may be increased to about 100C. above such softening point.
8 Thus, the forming te~.peratures which may be used with the 9 various suitable block polymers wi~l ~ary between about 65C. and about 32~C. or 350C. in the absence of air 11 or other gaseous oxygen. Forming, other than embossing, 12 is carried out at temperatures above the softening point of 13 the "A~ segments. Embossing can be carried out at the 14 same temperatures or even below the softening point of ~he "A" segments.
16 In the thermoplastic block polymers having the 17 A-B-A struc~ure, the end segmen~s, "~", which are rigid at 18 room temperature associate with each other to give ~arge I9 aggre~ates which are referred to in the literature as "domains" 4 At normal handling temperature ~or the molded article after 21 final forming of the green body sta~e, e.g., room temperature 22 or slightly above, these domains are hard and im~.obilize the 23 ends of the ~B" segments. This end segment immobilization in 24 conjunction with chain entanglements creates physical crosslinks which helps to protect the green body from dis-26 ~iguration as the result of handling. At hi~her temperatures, 27 the terminal, "A" se~ments soften and may be disrupted 28 by applied stress, allowing the polymer to flowO The latter ~ _ g _ i, ~al66~312~
1 cor.dition makes possi~le the mixing, molding, etc. which 2 are necessary o.r optional steps in preparing the green body.
3 Cooling will then provide a green bo~y having unusual ~ resistance to physical change pri.or to the heating associated with burn-out and sintering.

6 B. The Plasticiæer 7 The ~acrificial binder also includes a plasticizer 8 which is either an oil or a wax or both. The oils and waxes 9 used for this purpose are naphthenic, paraffinic or a mixture

10 . of paraffinic and naphtherlic co~stituen~s. They are sufficiently

11 volati~e to be removed easily and rapidly in the ~urn-out

12 process but insuficiently volatile to be substantially removed

13 during mixing and/or molding. ~he loss due to volatilization

14 during mixing and/or molding is advantageously below 20 and preferably below lO weight percent.
16 Functionally, the oil.s and/or waxes must be 17 compatible with the rubbery phase of the principal binder 18 resin when it becomes ru~bery on plasticization at a 19 temp~rature ~omewhat below the ~oftening point of the "A"
segments of th0 principal rQsin. This gives the binder a 2~ capability of accepting high filler loadings while remaining 22 strong and flexible.
23 At least 75~ ~y weight of the oils used as 24 plasticizers boil in the range o~ about 550~F.
to about 1038~.~ prefexably in the range of ab~ut 55GF.
26 to about 86$F. They have viscosit e~ at 210F. in the ~7 : range of about 30 to abou~ 22G Saykol~ Uni~ersal S~conds, 28 herainafter ref~rred to as S~ advantageously in the ~9 rang~of about 35 to about 155 S~U.S., and preferahly :

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in the range of about 35 to about 80 S.U.S. These ~ oils have their Aniline Point in the range o~ about 17~F.
3 to about 255~F. The oils may be a product of petroleum 4 refinin~ operations or ve~etable or a.nimal oils and they may include or be low molecular weiht synthetic polymers 6 such as polystyrene, poly(alpha-methyl styrene), or a 7 polyolefin.
8 The waxes used have melting points in the range g of about 130F. to about 170F. At lleast about 75~ by weight of such wax boils at temperatures in the range of about 600 GF.
11 to about 900F. These may be a product of petroleum 12 refining operations, vegetable or animal waxes or synthetic 13 polymers such as low molecular weight polyolefins.

14 C. Optional Constituents The sacrificial binders of this invention ~ay 16 and in c~rtain embodiments aavantageousl~ do contain additional 17 materials such as supplementary resins, supplementary 18 elastomers and antioxidants.
19 Supplementary resins are use~ul in em~odiments where there is a desire to increase the stiffness of the green 21 ~dy while still providing fluidity at processing temperatures.
22 Suitable secondary xesins include any o the aforementioned 23 polymers suitable for use as l'A" segments in block polymers, 24 resirs similar to resins suitable for use as "A" segments and having affinity for the "A" segments of the block polymer ~6 used, e.g., cumarone-indene resins and polyindene with block 27 ~polymer having polystyr~ne "A" blocks, and resins which 2~ have a~ af~inity for the "B" seyment or segments in the 29 block polymers, e.g., polyterpenes with polybutadi~ne nBI' blocks. It is to be understood that resins having an affinity .

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1 for the "A" or "B" segment~ of the block polymer may also 2 be polymers suitable for use as "~" or "B" respectively in other embodiments when they meet the limitations set 4 forth herein for "A" or "B'~.
Supple~entary elastomers are useful in embodiments 6 where there is a desire to improve tear strength in the ~reen 7 body~ Suitable secondary elasto~.ers inclu~e natural rubber 8 and synthetic slastom~ers , e . g ., polybutad iene , polyisoprene , 9 etc.
Antioxidants are useful to retard oxidative degrada-11 tion of the block polymer during mixing thus minimizin~ loss 12 of strength in the green body. The antioxidant also 13 allows more rapid removal of binder during burn-off by 14 minimizin~ surface oxidation which may tend to seal off the surface. Suitahle antioxid2nts include, but not by 16 way of li~ltation, 2,6-ditert-butyl-ph~nol, a polymerized 17 1,2-dihydro-2,2,4-trimethyl ~uinoline, 2-mercapto~,enzimidaæole~
18 tetrakis~methylene-3-t3',5'-ditert-butyl-4'-hydroxyphenyl~
19 propionate] methane, etc~
. Process aids which are conventional tc molding 21 and forming operations with polymeric matexials are likewise 22 u~e~ul in the practise of this invention to improve the 23 relea~e characteristic~ of the green body from any type o 24 moiding or forming ap~,aratus with which the green body comes in contac~ and to improve the flow charac~eristics of ~he ~inder-26 ~iller mix~ure during such operations as ex~rusion molding, 27 ~ injection molding, transfer molding, e~c. Process aids which 28 may be of assistance include methylacetylricinoleate r stearic 9 acid~ poIyethylene, polyethyle~e wax, mi~tures of ~atural ~30 ~axes and wax deri~atives~ ve~etable fats~ partiaIly oxidized 31 polyethylene, etc.

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1 D. Paxticulate Material 2 This inventio~ is applicable to all particulate 3 material that i~ "sinterable;' as that term is hereinafter 4 defined. Specific examples .include9 ceramic powders such as cordierite powders, alumina, B-spodumene, crystalline 6 or fused silica, mullite, k~anite, æirconia, beryllia, masne~iar 7 titania, chromium oxide~ iron oxide and complex oxides B comprising two or more of these oxide~, metal powders suc~
~ as iron, iron alloys, cop~er, copper alloys, aluminum, alumin~ alloys, silicon, silicon alloys, nickel ba~e super 11 alloys, cobalt ba~e super alloys and stainless steals t 12 inter~etallics such as nickel aluminides and molybdenum 13 silicide, carbides such as silicon carbide, tungsten car~ide, 14 and iron carbide, nitrides uch as silicon nitride and boron nitride, and co~posites of metal-ceramic~, metal carbides 16 and metal nitriæes.
17 One o the advantages of these binders is that 18 they are amenable to high flllings of p~rticulate solids.
19 The molding mixture advantageously comprises about 30 to :20 about 70, preferably about 50 to about 65, volume percent 21 particulat~ solid~ with the balance being made up of the 22 sacrlficial binders.

Z~ ~. Propor~ions of Binder Constituents .
24 The proportions of:the principal binder resin or ~lastomex, i.e., the block polymer, and the pla~ticizer, ;2~ i.e~., the oil~ wax or Qil and wax, may vary widely. In ~ 27: ::a binder consisting 501ely of the block pol~mer and plastici.zer~
;~ 28 the block pol~mer will comprise between 10 and 90, pxeferably 2~ : ~etween about 30 and about ~5, and most preferably be~ween :
about 45 and about 65~ weight percent of th~ ~otal b.inder 31 with the plasticize.r co~prising the balance~ i.e., .

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~L~66~32~3 :
between 90 and 10, preferably between about 70 and _ about 15, and. most preferably between about 55 and about 35 3 weight percent, provided, however, that the wax constitue~lt 4 ~hen used, advanta~eously does not exceed a~out 70 weight percent of the binde.r.
6 It will be understood that one may replace any 7 fraction less than 50 weight percent, :i.e., a to between 8 49 and 50, more commonly between about 0.1 and about 30r g weight percent of the block polymer aforedefined ~-ith an e~uivalent amount by weight of another polymer that 11 is within the limitatio.ns of "A" in the aforementioned 12 formula.
13 It will also be understood that one may replace 14 any fraction less than S0 weight percent, i.e., 0 to between 49 and 50, more commonly between about 0.1 and akout 3n, 16 weight percent of the aforedefine~ block polymer with an 17 equivale~t amount by weight of another polymer that i~
18 within the limitations of "E'l in the a~orementioned formula.
1~ It will be ~urther understood that one may repla~e any fraction less than 50 weight percent, i.e., 0 to between 21 45 and 50, more commonly between about ~.1 and about 40 2Z weight percent o~ the block polymer aforede~ined with an 23 equivalent amount by weight of a block pol~.er havin~
24 the structural formula X ~B (~B) n A] n ~ wherein "X" is a multiunctional halogen functional linking agent, A or B
26 :~ "n" is 0 or a positive integer, "n~' is a positive integer greater 27 ~ than 2 and A and B have the same limitations as A and 28 in t~e hereinbafor~ described block polymer haviny the ~29 ~ structural formula AB ~AB~n A. The linking ag~nt, when the ~ block polymer has a linking ~gent, is a multi~unctional ~:31 ~ ~2) ~ompound consisting essentially of elements selected ., ~ : ~
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1 from the ~roup consisting of car~on, hydrogen, oxy~en, 2 halogens, nitrogen, silicon, phosphorous and sulfur.
3 When anionic polymerization is used, this iS a halogen functional 4 coupling species. The following are illustrative S but not exhaustive: silicon tetrachloride, 1,2,4-tri 6 (chloromethyl)benzene, 1,2y4,5-tetra(chloromethyl) benzene, 7 Bis(trichlorosilyl)ethane, cyclic trimer of phosphonitrilic 8 chloride, ben~ene, chloromethylated polystyrene, 9 trichloromethylsilane, and silicon tetrachloride.
The use of these linking agents is discussed in the aore-11 mentioned article ~Synthesis of Block Polymers by Homogeneous 12 Anionic Polymerizationn by L. J. Fetters. When the block 13 polymers are prepared by other synthesis routes as aforementioned, 14 one would use other linking agents. In the case of ~ree radical polymerization, one may us~ a multifunctional co~pound 16 that will initiate polymerization of the "B" block, as when 17 the "B'l block is poly(ethyl acrylate~, and react with ~he 18 "B" block~ e.g., a branched azonitrile such as one pxepared 19 by reacting tri~lathylolpropane with a diisocyanate such a~ toluene diisocyanate and a glycol suoh as poly(oxypropylene 21 glycol~ In the case of polycondensationt one may use a 22 multifunctional compound tha~ will react with the ~B" block, 2~ e.g., ~rimelliti~ anhydride. In the case of c:ationic polyn~.eri-24 zation, one may react poly(vinyl cbloxide) with trimethyl aluminum which will initiate polymeri~ation of the "B"
26 blo~k, as when the "B'~ block is polyisobutylene, and reaot 27 ~ with the "B" bIock. A~ afoxementioned, '~X" may be polymer 2E~ 91p~ polymer "B" or a linking agent. For purposes o:E this ~ lnvention and the use of such block polymers in sacrificial binders for a ~olding mixture, the subs~i~ution of a linking . .

15 -~66~3Z9 1 agent for polymer "A" or polymer "s" as the "x'1 component 2 does no~ materially a~fect the physical prnperties of the 3 block polymer. Linking agents are conventionally u~ed in 4 such klock polymers and are well known to those skilled in the art as shown in the hereinbefore citecl literature.
6 With such teachings, selection of a specific lin~ing agent 7 for a specific block polymer is quite within the skill o 8 those skilled in the artO
9 In combination the substitutions of such "~ ype polymers, such "B" type polymers and such other type of 11 block polymers should constitute less than 50 weight percent 12 o the principal bind~r resin, block polymer previously 13 described.
14 In the following table there is set forth advantageous ranges for cons~ituents when optional ma~erials are

16 included.

17 Sacri~icial ~i-dtr- With ~tional Constituents : 18 Material Range, W*.~ Preferred Range 2~Iost Preferred I9 ~ o Binders Wto % of Binder_ Ran~e, Wt.% o~
- Binaer _ _ .
21 block polymer10-90 30-g5 45-65 22 plasticizer Y0-10 70-15 35-55 23 oil 0 90 0 70 0 55 24 wax 0-70 0-30 0-10 secondary resin 0-40 0-25 Q-15 26 secondary 27 ela~tomer 0-40 0-15 0~10 ~::28 antioxidants 0-7 ~: 0-5 0-3 29 proce3s aids 0 15 0~10 . 0-7 :
F. Definitions ,.
31 The term "sintering" is used herein to mean 32 the coalescence by heat o~ crystalline or amorphous particles , .

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~L~66~Z9 1 into a solid mass.
2 The term "moldin~" is used herein to mean any 3 of the methods of forming known in the art as extrusion 4 molding, inieetion molding, compression molding, laminating which includes compression molding, tr,ansfer molding~
6 pressure molding, displacement molding, blo~ molding, 7 calendering, and e~,bossingq 8 ~he term l'processing" is used herein to mean 9 mixing, forming, and mixing and forming.
The term "green body" is used herein to mean 11 a molded arti~le comprising an intin~ate mixture of 3interable 12 particulate solids and a thermoplastic, organic binder.
13 The term "molecular weight" is used herein 14 to mean average molecular weight (Mn)~
The term "room temperature" is used herein 16 to mean a temperature in the range of 2C-25C.
17 ~he term "softening point" is used herein to

18 mean the gl~s~ transition temperature when used with

19 reRpect to glassy polymers and the crystalline melting poin~ when used with respect to crystalline polymers.
21 The term "glass transition temperaturel' is 22 signified herein by the sym~ol IITg" and is used herein 23 to mean that temperature below which a non-crystallizing polymer becomes a supercooled liquid~ i~e., a gla~s.
The term "crystalline melting point" is 26 ~ig~ified herein by the symbol l'Tml' and is used herein 27 to mean that temperatuxe at which a crystalline polymer 28 melts and becomes non-cry~talline.
2g Both "~lass transition temperature" and 'lcrystalline mel~ing pointl' represent areas of transition :

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~C~66~Z~31 ` but are practical terms ~hich are sufficiently de~initive 2 and exact for ~he full and complete practice of this 3 invention by one skilled in the art without experimentation 4 beyond normal routine.
The term "glassy polymer" is used herein to mean 6 a non-crystalliziny polymer which at room temperature 7 i9 below its glas~ transition temperatureO
8 The term "rubbery polymer" is used herein to g mean a non-crystalline polymer that is akove its Tg at room temperature.
11 ~he term l'cystalline polymer~ is used herein 12 to mean a crystallizins polymer which is below its Tm 13 at xoom temperature.
14 ~he term "flexi~le polymer" is used herein to mean a polymer which at room temperature is in 16 transition from glass or crystalline material to an 17 ela~tomeric state, i3e~ ~ to a ru~ber.
lB It will be understood by those sk.illed in 13 the axt that it is possible for portions o~ a particular poly~.eri~ mas~ to exist in more than one state at room 21 temperature and not be in a state of transition from one 22 to the other, e.g., a polymeric mass in which one 23 portion is a "rubbery polymer" as defined above 24 and a ~econd portion is a "crystalline polymer" as ~25 defined above. Thus~ ~he defined term concerned shall 26 be understood to mean that the largest fraction of such 27 polymeric ma~s meets the li~i~ations of ~he term used.

28 The following are illustrative examples 29 : wherein, unl~ss otherwise specified, the materials used are within the limitations hereinbeforP set forth 31 or su~h materials in the practice of this invention.

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l An A-B-A block polymer elastomer, hereinafter 2 called "khe elastomer", is prepared by an anionic initiated 3 polymerization using the ~asic high vacuum apparatus and 4 general procedures for anionic poly~eri~ation described in section 2 ~Experimental Techniques~ of the aorecited 6 artiele "Procedures for Homogeneous Anionic Polymerization", 7 by L~ J. Fetters. In addition, all attachments of 8 the ve~sels to the vacuum line are accomplished through g a grease trap as shown in the aforecited article "The lo Association of Polystyryllithium, Polyisoprenyllithium, 11 and Polybutadienyllithium in ~ydrocarbon Solvents" by M.
12 Morton et al.
13 The reactor is first flamed while under vacuum.
14 The reactor is cooled, sealed off from the vacuum line, and then rinsed ~ith a solution of ethyllithium in n-hexane 16 to reaGt with any residual materials that could terminate 17 the growin~ polymer chains. The monomers and solvent~ to be 18 . used in praparing the elastomer are purified according to 19 the article by L. J. Fetters last mentioned above.
~o The reactor is reattached to the vacuum line~
21 A solu~ion containing O . 036 grams of ethyllithium in 3 ml .
22 benzene is added to the reactor. To the reactor is charged 23 370 ml. of ~enzene. Styrene monomer in the amount of 15 24 gramæ is distilled into the reactor throu~h a breakseal ~25 ~ onto the top of the benzene. ~he contents are cooled to :
26 dry-ice/alcoh~l t~mperatures e.g., ~65~. to -7~ac. The :
27: reactor i9 ~ealed of~ from the vacuum llne and the contents allowed to warm-up from a dry/ice alcohol temperature.
2:9 A~ SOOD as the contents have ~hawed 0.65 gram~ of anisole : : 30 in 4 ml. of benzene is added and shaken wi~h ~he benzene 31 and styrene in the reactorO The polymerization of the styrene ;
:

. - l .

is allowed to proceed for 4 hours at 30C. The reactor 2 i.s then reattached to the vacuum line and 60 ~rams of 3 butadiene is distilled in~ ~fter the contents have keen 4 cooled with liquid nitrogen, the reactor is sealed off from the vacuum line. The mixture is allowed to tha~ and after 6 ~tirring the polymerization of butadiene is allowed to proceed 7 at 30C. for 16 hours. The mixtuxe is cooled to a 8 dry-ice/alcohol temperature and 15 gram~ of styrene are 9 distilled in after the reactor has been attached to the vacuum lineO ~he reactor is once again sealed off from the 11 ~acuum line, the contents thawed and mixed, and polymeri-12 zation of the styrene allowed to continue for 4 hours at 13 30C. The elastomer in the reactor is then coagulated ~y 14 slowly pouring the benzene solution into methanol containing a small amount of phenylbetanaphthylamine to stabilize 16 the elastomer. The elastomer is dried and is then ready for :
17 use as the principal binder resin.
18 This polystyrene-polybutadiene-polystyrene 19 elastomer containing about 33.3 wt. ~ poly~tyrene in the amount of 14.5 grams is banded on a tight mill which has 21 been preheated ~o 300F. About 10 grams, of 100 total grams, 22 of ~lassy cordierite frit are then added on the mill to 23 stabili~e the band. The oil, 12.5 grams of a commercially 24 available, paraffinic petroleum oilS Flexon 845 a tradename ~f Exxon Company, ~S.A. is ætirred with 50 gx~ms of the 26 : cordierite ~rit. ~his oil has the following properties:
27 speci~ic gravity (6~/~0~.) o~ 0.8~49-0.8811; colox ~ASTM~
28 ~of 1-4; vi~cosity (210F~) of 43~4-61.5 S.U.~; aniline 29: point of 219-2409F~ and silica gel aromatics o~ 14.9-16.1 wt. %O About half of the oil/cordierite mixture is added 31 to the mill and mixed in~ As the viscosity of the mixture 32 decr2ases~ the mill temperature is reduced to 290F~ to 33 minimize volatilization of the oil. The remainder of the

- 20 2~1 ~? dry cordierite and the remainder of the cordierite/oil 2 mixture are mixed by alternately adding a few grams of 3 one and then of ~he other to the materi.al on the mill.
4 When the mixing is complete in about 20-30 minutes, the composition is sheeted from the mill and allowed to cool.
6 Ri~bed sheets of the mixture are prepared by 7 compression molding. The sheet obtainled from the above recited 8 mixing is banded on a 2gOF. mill and the nip width is decreased 9 so that a sheet 0.030 inch thick is obtained. A preform 3 1/2 inch square is cut from the 0.03lD inch thick sheet, 11 the same providing an excess o~ material for the ribbed mold 12 being used. A pres~ with a 3 5/8 inch diameter ram and th~
13 bottom half of the mold are preheated to 250F. The preform 14 is then placed on the preheated bottom half of the mold for -lS 15 seconds. The unheated top half of the mold is then placed 16 upon the preform and the bottom hal~. Both halves of the 17 mold are coated with polytetrafluoroethylene. The press 18 i~ closed and a pressure of 2,000 psiy is applied, Th;.s 19 pres3ure is maintained ~or 15 seconds. The pressure is then released and the ribbed sheet removed from the mol

21 The ribbed sheet i5 then heated in accordance : ,

22 with the following cyc}e:

23 Table I
: 24 ~ _re, F. Time, Hrs.
:25 1 :160 4 , .
. 26 2 260 ~-27 3 400O~50 4 28 The~resulting~body is then fired in accordance :~ :2g with the following cycle:

::; :
: ~ - 21 -~ Table I:[
__ 2 S~Rate of Temp~rature Temperature Range 3 Ri.se/=_F ~ F. ~ ___ 4 1 600-$00 room 2200 6 This result~ in a strong, densat cordierite 7 ri~bed she~t.

8 The procedures of Example 1 are repeated with 9 the single difference that the block polymer elastomer used is a commer~ially-available triblock (ABA) polymer ll having a polybutadiene center block and polystyrene end 12 blocks. This ~lock polymer contains 30 weight pexcent 13 polystyrene, i.e., Kraton 1101. Kraton is a tradename 14 of Shell Oil Company. This block polymer has specific gravity of about 0.95 ~nd intrinsic viscosity of a~out 16 1.00 dl/g ~30C. in toluene).
17 This results in a strong, dense, cordierite ri~bed l8 sheet ; ~ . . ' ~, The procedures of Example 2 are repeated except ~ or the difference that the elastomer, the oil and the frit are 21 ~irst ~tirred together and then mixed in a Banbury mixer which ~ 22 is prehe~ted to 310 to 320F. for 15 minutes. The resulting : ~ 23: : mixture is then banded on a two roll:mill which has been Z4 preheated: to 290F. After tw~ to five minute~ o~ mill mixing, .
~he composition is ~heeted and allowed to cool. It is now ~26 ~ ready for compression molding and is molded in accordance 27 :: with the previous examples. This results in a strong, dense~
28 cordiexlte sheet.

:
' .

3~668~:~

Exampl~ 4 l The procedures of Example 3 are repeat~d except 2 for the following differences: twenty-nine (29,0) parts 3 by weight of the polystyrene-polybutadiene-polystyrene 4 triblock polymer elastomer are mixed with 27.3 parts S by weight of parafin wax (m.p. 130F,), and 200 parts by 6 wei~ht of glassy cordierite fri~. This xesults in a 7 strong, dense, cordierite sheet. The paraf~in wax ac~s 8 as a process aid and plasticiæer and provides smoother 9 extrusions. It also increases the stiffness of t~e green body.

Exxmple 5 11 The procedures of Example 3 are repeated 12 except for the following differences: test bars are 13 molded using a ram type injection molding machine.
: 14: The barrel and nozzle of the injection molding machine are preheated and controLled to 320F. A mold for molding 16 ~wo ~es~t bars is preheuted to 100F. und clamped with a ;~; 17 prassure of 15,000 psi. Twenty ~20) grams of pieces eut : 18 from the above sheet are introduced into the barrel and ~19 allowed to heat ~0 5 minutes~ The material is then in-jec~ed into the mold with ~he ram pressure (800 psi) being : ~ 21 maintained for one m~nute. Ram pressure is released followed 22~ ~ ~: by selease of clump pres~ure from the mold and the test bars :23~ ~ are removed ~rom the mold. T~e test bars are first heated ~24 : ~ and then fired using the same cycles used ~or the sheet ~5~ material in the preceding examples. This results in strong, 26~: dense, cor~ierite ~ars.

'::
.
- 23 - .

, .

~L~6~2g 1 The procedures of ~xample 2 are repeated except 2 for the following differences: A flat sheet is prepared by 3 use of a screw type extruder havina a 2-inch bore. The 4 binder cordierite mixture is pelletiæed and the pellets are fed into the hopper of the e~truder. It is then 6 conveyed through the extruder and passed through a thin slit 7 die ~0.020 inch thick, 4 inches wide~, The temperature 8 settings on the extruder are: ~eed section 175F~, g tran~ition ~ection 250F., and die ~ec~ion 300F8 The 5heet is then cooled to room temperature and stored. ~he 11 cooled sheet is flexible and suitable for subsequent handling 12 such as ~litting, rewinding and e~bos~in~ and when ~ired 13 yields a stron~, dense, cordierite sheet.

.
Ex~ le 7 .
14 The procedure~ of Example 2 are repeated with the exception that a different, commercially available, 16 polystyrene-~olybutadiene-polystyrene, triblock polymer 17 is used a~ the elastomer, i.e., ~rato~ 1102. This ;~ ~18 elastomer contains about 28% by weight polystyrene and has 19 a lower viscosit~, i.e.~ intrinsic viscosity of 0.84, dl/g (30QC~ in toluene), than the one pre~iously exemplified 21 and identified by containing 30~ by weight polystyrene.
~2 : As a result Q~ the lower viscosity of: he elas~omer, the .
:3 :~ ~inder composition has a lower viscosity and is moxe ea ily :.

24 processed. The product obtained is not as ~tiff in the :
~25 : ~ green state but still resul~s in a StrOD~, dense, co~dierite 26 ribbed sheet when firedO

. :
:: .
~ 4 -. .

6~329 Example 8 __ 1 The procedures o~ Example 2 are repeated with 2 the single difference ~hat a com~ercial:Ly-available, polystyrene-3 polyisoprene-polystyrene triblock polymer elastomer, i.e., 4 Kraton 1107 containing about 14 wei~ht percen~ polystyrene : 5 is used as the elastomer. When mixed w:ith oil and frit, 6 this elastomer yields a composition of ]Lower modulus but 7 of inferior strength in the green body state to those of the preceding examples. It still yields, however, a strong, g dense, cordierite ribbed sheet after fixing.

The procedures of Example 2 are repeated 11 except for the differences: ~ commercially-available, 12 triblock polymer ela~tomer having polystyrene end blocks 13 and a poly ~ethylene-butylene) rubber center and 14 contalning 12-14 weight percent polystyrene, i.e., Kraton GX-7820, is used as the elastomer and a paraffinic oil, i.e., 16 Shellflex 790, is ~ubstituted for the oil used in ~xample 2 17 Shellflex is a tradename of Shell Chemical Company. This 18 change of oils is made to reduce the volatilization which 19 would otherwise occur because of the higher mill temperatures be9t suited to work this plasticized ela~tomer, i.e., 21 about 350UF. The green body is stiffer than that o~ Example : 22 2 and a poorer dispersion of filler is obtained. The ribbed sheet obtained after firing is less dense and of lesser ~24 streng~h than those produced in ~he preceding examples.

25 : Th~ procedures of Example 2 are repeated ex~ept

26 for the difference that the parts ~y weight of th~ elastomer, , ~ :

~L~6~9 - oil and cordierite frit are as follows: elastomer 2.75, ~ oil 22.77 and frit 100.00. This example illustrates 3 approaching toward minimum elastomer and maximum oil content 4 in the binder. The green body is soft and lacking in strength and integrity. The rib~ed sheet obtained after 6 firing is less dense and of lesser strength than those 7 produced in the preceding examples.

8 The procedures of Example 2 are repeated except 9 for the difference that the parts by wei~ht of the elastomer, oil and cordierite frit are as follows: elastomer 24.78, 11 oil 2.53 and frit 100.00. This example illustrates approaching 12 toward maximum elastomer and minimum oil content in 13 the binder. This composition is stiffer and more difficul~
14 to process than those produced in the preceding examples.

15 ~ The procedures of Examp}e 2 are repeated except 1~ for the difference that para~fin wax (m.p. 130F.) i9 17 substituted fo~ the oil in the binder and the parts by weight o 18 the elastomer, wax and ~rit are as ~ollows: elastomer 8~26, 19 wax 19.07, and frit 100Ø This compo~ition results in a sti~fer ~reen body with les tendency to crack during 21 burn-ou~ and firing.

22 A commercially-available polystyrene in 23~ the amount of 12.17 grams is banded on a tight mill 24 ~ which has been preheated to 320F. ~his polystyrene has ~5 specific gravity o about 1.05, a Vicat softening point ::: ;: :
: ':
~ - 26 -:~ :

~L~61~ 9 of about 97C., and a melt flow of about 3.5 grams~lO
2 minutes (ASTM-D1~3 8 condition G). The polystyrene-3 polybutadiene-polystyrene elastomer of Example 2 in the ~ amount of 12.39 grams (30 weight percent polystyrene) is then combined on the mill with the polystyrene 6 a~er the temperature is reduced to 310F. for the 7 remainder of the mixing. Two grams. of the lO0 grams of 8 glassy cordierite frit to be used, are then added on the 9 mill to stabilize the band. The paraffinic petrolaum oil of Example 2 in the amount of 3.80 gram~ is stixred with sn grams ll o the cordierite frit. About hal~ of the oil~cordierite 12 mixture is added to the mill and mixed in. T~e remainder 13 of the dry cordierite and the cordierite/oil mixture 14 are mixed in by a~ternating a ~ew grams of one and then the other. When mixing i~ complete in about 20 to 25 16 minutes, the composition iS sheeted from th~ mill and 17 allowed to cool. The remainder of the processing is 18 - the same as in ~xample 2. Thi~ also results in a stiff l9 green body but with improved green strength and better re~ention of shape during burn-out. The proces~ability 21 of the mix improved as mixing proceeded.

~ . .
22 Natural rubber ~#l rib~ed smoke sheet~ in the 23 amount of 10.67 gra~s is banded on a tight mill which has been ~24 preheated to 30GF. It is ~hen removed from the mill and set .
aside7 The ela~tomer of Example 2 in the amount o 13.77 26 grams is then banded on the 300F. mill. Half of the natural

27 rubber is then added to the mixture on the mill. ~he remainder

28 of the dry cordierlte and the natural rubber axe then mixed in ~ .

:~L0668~9 1 by alternating a few grams of one and then of the other.
2 When mixing is complete in abou~ 20-25 minutes, the 3 composition is sheeted from the mill ancl allowed to cool.
A The remainder of the proce~sing is the C;ame as that o Example 2. The use of tlle natuxal rubber gives Lmproved 6 tear strength in the green body and gives a modulus 7 lower than that in Example 2.

~ ,.
8 The procedures of Example 2 are repeated wi.th the 9 following changes: all of the cordierite is added in the first addition and none is mixed separately with the oil.
11 In addition,. the parts by weight of elastomer, oil and 12 cordierite are as follows: elastomer 27.54, oil 25.30 13 and frit 2.72. This provides an extremely soft 14 co~position with a tendency to provide a porous ceramic I5 par~. .
.

~ . ~ .
16 The procedures of Example 2 ar2 repeated with 17 the following changes: the parts by weight of elastomer, 18 oil and frit are elastomer 12.39, oil 13092 and frit 123.81.
19 At this high loading of ~rit, the green hody is very stiff bu~ very weak a~d difficult to process.

::

:
21 The proaedure of Example 2 is repeated with the 22 ~ollowing changes: the parts ~y weight of elast~mer, oil :23 and frit are elastomer 13.77, oil 12.53 and fri~ 100.00 : ~ :

~ - 28 w ~ .

il29 ` In addition, the mixture also contains 0.14 parts by 2 weight of an antioxidant, i.e., 4,4' methylene bis(2,6-di-3 tert-butyl-phenol). ~se of the antio~iclant results ~n 4 ~etter retention of stren~th durin~ mixing and improved resistance to slumping durin~ binder burn-off.

Example 18 6 The procedure of Example 2 is repeated 7 with the following changes: the proportions by weight 8 of the binder inyredients and frit are elastomer 13.77, 9 oil 11.39, fri~ 100.00 and methylacetylricinoleate, a prvcess aid, 1.36. Use of the process aid results in 11 better processability during calendering and extrusion.

~ .
12 Sintered, modified, beta-alumina tubes are 13 produced by extrusion molding using the elastomer and oil of 14 Example 2, wax~ an antioxidant and particulate beta~-alumlna.
The composition mixed for molding is as follows:

16 ; Ta~le I
17 Material P~ y~ ght 18 ~ Ela~tomer o~ Example 2 4.7 19 ~ Oil of Example 2 3~2 ~ Para~fic wax ~m.p. 135Fo) 3~5 ~ :: , 21 ~n~ioxidant, poly 1,2 dihydro-~22 ~ ;2~24-trime~hylquinoline 0.5 23 Powder li~hium-modified beta~
24 alumina (9.0~ Na, 0.8% Li 0 ~25 ~ and 90.2% A12Q3~ 2 50.0 ~ .

~ 29 ' ~
.
, ., The above-listed materials are mixed at 310F.
2 (154C.) on a two roll mill After bain~ extruded into 3 tube shape using a 310F. (154C.) nozzle temperature 4 with a barrel tenperature of 340~. (171C.), the tubes are then burned-out and sintered using ~he following 6 schedule:
7 Tahle II
8 Step Rate of Temp. Rise Temperature r ~; C.~Hr. Ran~, C~

11 2 Hold for 15 hrs. 700 12 3 Cool to room temperature 13 over 3 hours 14 Each such tube is placed in a platinum tu~e which is mechanically sealed. The sealed sample is then 1~ placed in a furnace. The ~urnace is heated to 1100C.
17 over 15 hours. From 1100C., the furnace is heated to 18 1570C~ over 4 hours and 45 minutes where it is held lg for 15 minutes and then cooled to 1~20C. over 15 minutes.
The sample is held at 1420C. for 8 hours and then cooled 21 to 360(:., over 7 hours at which point the sample is allowed 22 to cool to ambient emperature in air.
, 23 The procedures of the previous examples are 24 repeated with the single difference that particulate alumina :25 : is substituted ~or the cordierite and sintering is carried 26~ out at temperatures of 1600 - 1700C.

:

~ 30 --: ~ :

~66~

1 The procedures of the previcus exa~ples are 2 repeated with the single difference that particulate 3 silicon carbiae is substituted for the cordierite, and 4 sintering is carried out at te~peratures of 2000 - 2200C.

The procedures of the previous examples are 6 repeated except that particulate aluminum is substituted 7 for the cordierite and sintering is carried out at 8 temperatures of 550 - 650C.

Example 23 9 The procedures of the previous examples are lC repeated except that particulate tainless steel is 11 substituted for the cordierite and sintering is carried 12 out at temperatures of 1400 - 1500Co .
13 . The foregoing ~xamples are merely illustrati~e 14 of the practice o~ thi~ in~ention and those skilled in the art will readily recognize that modifications and 16 variations may be made in these examples without departing 17 from the scnpe o~ this lnvention as set forth in the 18 ~ appended claims.

9 . _ :
'~

: ~ .

~ 31 -~ .
. . .

Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

An intimate mixture of about 10 to about 90 parts by weight of resinous material and about 90 to about 10 parts by weight of a plasticizer for said resinous material wherein:
(1) said resinous material is a block polymer having the structural formula AB ?AB?? A wherein "? " is 0 or a positive integer, "A" is a linear or branched polymer that is glassy or crystalline at 20°-25°C., has its softening point in the range of about 80° to about 250°C., and "B" is a polymer of different chemical composition from A that behaves as an elastomer at temperatures between about 15°C. below the softening point of A and about 100°C. above the softening point of A, and (2) said plasticizer is selected from the group consisting of (a) an oil at least 75 percent by weight of which boils in the range of about 550°F. to about 1038°F., has viscosity at 210°F. in the range of about 30 to about 220 Saybolt Universal Seconds and an aniline point in the range of about 170°F. to about 255°F. and (b) a wax melting at a temperature in the range of about 130°F. to about 170°F.
at least 75 percent by weight of which boils at temperatures in the range of about 600°F. to about 900°F., and - 1 - cont.
(c) an oil in accordance with (a) and a wax in accordance with (b).

An intimate mixture in accordance with Claim 1 wherein said block polymer is a polymer wherein "?" is 0, "A" is polystyrene and "B" is an elastomer selected from the group consisting of polybutadiene and polyisoprene.

An intimate mixture in accordance with Claim 1 wherein said oil is an oil selected from the group consisting of paraffinic oils and naphthenic oils and boils in the range of about 550°F. to about 865°F.

An intimate mixture in accordance with Claim 1 wherein said intimate mixture is an intimate mixture of about 30 to about 85 parts by weight of said resinous material and about 70 to about 15 parts by weight of said plasticizer and "B" is a polymer that behaves as an elastomer at temperatures between about 15°C below the softening point of "A" and about 70°C above the softening point of "A".

An intimate mixture in accordance with Claim 1 wherein said intimate mixture is an intimate mixture of about 45 to about 65 parts by weight of said resinous material and about 55 to about 35 parts by weight of said plasticizer.

6. An intimate mixture in accordance with Claim 1 wherein said resinous material comprises in excess of 50 weight percent of said mixture.
7. An intimate mixture in accordance with Claim 1 wherein said resinous material comprises in excess of 50 weight percent of said mixture and said mixture contains a second polymer that is within the limitations of polymer "A"
8. An intimate mixture in accordance with Claim 1 wherein said resinous material comprises in excess of 50 weight percent of said mixture and said mixture contains a second polymer that is within the limitations of polymer "B".
9. An intimate mixture in accordance with Claim 1 wherein said mixture contains an antioxidant.
10. In a moldable mixture for preparing sintered articles which consists essentially of about 30 to about 70 volume percent of sinterable particulate solids and about 70 to about 30 volume percent of an organic sacrificial binder, the improvement wherein said organic sacrificial binder consists essentially of an intimate mixture of about - 10 - cont.
10 to about 90 parts by weight of resinous material and about 90 to about 10 parts by weight of a plasticizer for said resinous material wherein (1) said resinous material is a block polymer having the structural formula AB ?AB?? A, wherein "n" is o or a positive integer, "A" is al linear or branched polymer that is glassy or crystalline at 20°-25°C., has its softening point in the range of about 80° to about 250°C.
and "B" is a polymer of different chemical composition from A that behaves as an elastomer at temperatures between about 15°C. below the softening point of A and about 100°C. above the softening point of A, and (2) said plasticizer is selected from the group consisting of (a) an oil at least 75 percent by weight of which boils in the range of about 550°F.
to about 1038°F., as viscosity at 210°F.
in the range of about 30 to about 220 Saybolt Universal Seconds and an aniline point in the range of about 170°F. to about 255°F.
(b) a wax melting at a temperature in the range of about 130°F. to about 170°F. at least 75 percent by weight of which boils at temperatures in the range of about 600°F.
to about 900°F., and (c) an oil in accordance with (a) and a wax in accordance with (b) - 10 - cont.
and wherein 0 to between 49 and 50 weight percent of said block polymer is replaced by a polymer meeting the limitations of polymer "A" in said structural formula, and 0 to between 49 and 50 weight percent of said block polymer is replaced with a polymer meeting the limitations of polymer "B" in said structural formula, the sum of said replacements of said block polymer comprising in combination less than 50 weight percent of said block polymer.

A moldable mixture in accordance with Claim 10 wherein "B" of said block polymer behaves as an elastomer at temperatures between about 15°C. below the softening point of "A" and about 70°C. above the softening point of "A".

In a moldable mixture for preparing sintered articles which consists essentially of about 30 to about 70 volume percent of sinterable particulate solids and about 70 to about 30 volume percent of an organic sacrificial binder consists essentially of an intimate mixture of about 10 to about 90 parts by weight of resinous material and about 90 to about 10 parts by weight of a plasticizer for said resinous material wherein (1) said resinous material is a block polymer having the structural formula AB ?AB?? A, wherein "?" is 0 or a positive integer, "A" is a linear or branched polymer that is glassy or crystalline at 20°-25°C., has its softening point in the range - 12 - cont.
of about 80° to about 250°C. and "B" is a polymer of different chemical composition from A that behaves as an elastomer at temperatures between about 15°C. below the softening joint of A and about 100°C. above the softening point of A, and (2) said plasticizer is selected from the group consisting of (a) an oil at least 75 percent by weight of which boils in the range of about 550°F. to about 1038°F., has viscosity at 210°F. in the range of about 30 to about 220 Saybolt Universal Seconds and an aniline point in the range of about 130°F. to about 170°F. at least 75 percent by weight of which boils at temperatures in the range of about 600°F.
to about 900°F., and (c) an oil in accordance with (a) and a wax in accordance with (b) and wherein 0 to between 49 and 50 weight percent of said block polymer is replaced by a polymer meeting the limitations of polymer "A" in said structural formula, and 0 to between 49 and 53 weight percent of said block polymer is replaced with a polymer meeting the limitations of polymer "B" in said structural formula, and 0 to between 49 and 50 welght percent of said block polymer is replaced with an elastomer polymer having the structural formula X ? B (AB)? A??' wherein "?" is 0 or a positive integer, "?'" is a positive integer greater than 2, "A" and "B" have the same limitations as A and B of - 12 - cont.
said block polymer except that "B" of said elastomer polymer behaves as an elastomer at temperatures between about 5°C.
below the softening point of "A" of said block polymer and about 90°C. above the softening point of "A" of said block polymer, the sum of said replacements of said block polymer comprising less than 50 weight percent of said block polymer.

A moldable mixture in accordance with Claim 12 wherein said organic sacrificial linider consists essentially of an intimate mixture of about 30 to about 85 parts by weight of said resinous material and about 70 to about 15 parts by weight of said plasticizer.

A moldable mixture in accordance with Claim 12 wherein said organic sacrificial lanider consists essentially of an intimate mixture of about 45 to about 65 parts by weight of said resinous material and about 55 to about 35 parts by weight of said plasticizer.

The method of making a sinterable molding of particulate sinterable particles which comprises mixing about 30 to about 70 volume percent of sinterable particulate solids with about 70 to about 30 volume percent of an organic sacri-ficial binder which comprises an intimate mixture of about 10 to about 90 parts by weight of resinous material and about 90 - 15 - cont.
to about 10 parts by weight of a plasticizer for said resinous material wherein (1) said resinous material is a block Polymer having the structural formula AB ?AB?? A, wherein "?" is 0 or a positive integer, "A" is a linear or branched polymer that is glassy or crystalline at 20°-25°C., has its softening point in the range of about 80° to about 250°C. and "B" is a polymer different from A that behaves as an elastomer at temperatures between about 15°C.
below the softening point of A and about 100°C, above the softening point of A, and (2) said plasticizer is selected from the group consisting of (a) an oil at least 75 percent by weight of which boils in the range of about 550°F.
to about 1038°F., has viscosity at 210°F.
in the range of about 30 to about 220 Saybolt Universal Seconds and an aniline point in the range of about 170°F. to about 255°F.
(b) a wax melting at a temperature in the range of about 130°F. to about 170°F. at least 75 percent by weight of which boils at temperatures in the range of about 600°F. to about 900°F., and (a) an oil in accordance with (a) and a wax in accordance with (b) and wherein 0 to between 49 and 50 weight percent of said block polymer is replaced by an elastomer polymer meeting the limitations of polymer "A" in said structural formula, and - 15 - cont.
and 0 to between 49 and 50 weight percent of said block polymer is replaced with a polymer meeting the limitations of polymer "B" in said structural formula, except that "B" of said elastomer polymer behaves as an elastoner at temperatures between about 5°C. below the softening point of "A" of said block polymer and about 90°C. above the softening point of "A" of said block polymer, the sum of said replacements of said block polymer comprising less than 50 weight percent of said block polymer, molding the resultant mixture, driving off said sacrificial binder from said mixture with heat and sintering said particulate solids of said mixture.

A method in accordance with Claim 16 wherein "B"
of said block polymer behaves as an elastomer at temperatures between about 15°C. below the softening point of "A" of said block polymer and about 70°C. above the softening point of "A" of said block polymer.

The method of making a sinterable molding of particulate sinterable particles which comprises mixing about 30 to about 70 volume percent of sinterable particulate solids with about 70 to about 30 volume percent of an organic sacri-ficial binder which comprises an intimate mixture of about 10 to about 90 parts by weight of resinous material and about 90 to about 10 parts by weight of a plasticizer for said resinous material wherein - 17 - cont.
(1) said resinous material is a block polymer having the structural formula AB ?AB?? A, wherein "?" is o or a positive integer, "A" is a linear or branched polymer that is glassy or crystalline at 20°-25°C., has its softening joint in the range of about 80° to about 250°C. and "B"
is a polymer different from A that behaves as an elastomer at temperatures between about 15°C.
below the softening point of A and about 100°C.
above the softening point of A, and (2) said plasticizer is selected from the group consisting of (a) an oil at least 75 percent by weight of which boils in the range of about 550°F, to about 1038°F., has viscosity at 210°F. in the range of about 30 to about 220 Saybolt Universal Seconds and an aniline point in the range of about 170°F. to about 255°F. (b) a wax melting at a temperature in the range of about 130°F. to about 170°F. at least 75 percent by weight of which boils at temperatures in the range of about 600°F. to about 900°F., and (c) an oil in accordance with a) and a wax in accordance with (b) and wherein 0 to between 49 and 50 weight percent of said block polymer is replaced by a polymer meeting the limitations of polymer "A: in said structural formula, 0 to between 49 and 50 weight percent of said block polymer is replaced with a polymer meeting the limitations of polymer "B: in said structural - 17 - cont.
formula, and 0 to between 49 and 50 weight percent of said block polymer is replaced with an elastomer polymer having the structural formula X ? B (AB)? A??', wherein "n" is 0 or a positive integer, "?'" is a positive integer greater than 2, "A" and "B" have the same limitations as A and B of said block polymer except that "B" of said elastomer polymer behaves as an elastomer at temperatures between about 5°C.
below the softening point of "A" of said block polymer and about 90°C. above the softening point of "A" of said block polymer, the sum of said replacements of said block polymer comprising less than 50 weight percent of said block polymer, molding the resultant mixture, driving off said sacrificial binder with heat and sintering said particulate solids of said mixture.

A method in accordance with Claim 17 wherein "B" of said block polymer behaves as an elastomer at temperatures between about 15°C. below the softening point of "A" of said block polymer and about 70°C. above the softening point of "A" of said block polymer and "B" of said elastomer polymer behaves as an elastomer at temperatures between about 5°C.
below the softening point of "A" of said block polymer and about 70°C. above the softening point of said block polymer.

A method in accordance with Claim 17 wherein 0.1 to 30 weight percent of said block polymer is replaced with an equivalent amount of said polymer meeting the limitations of polymer "A".

A method in accordance with Claim 17 wherein 0.1 to 30 weight percent of said block polymer is replaced with an equivalent amount of said polymer meeting the limitations of polymer "B".

A method in accordance with Claim 17 wherein 0.1 to 40.0 weight percent of said block polymer is replaced with an equivalent amount of said polymer having the formula X ? B (AB)?A?'.