Preparation and Properties of an Internal Mold Release for Rigid Urethane Foam

Transcription

1 BDX Preprtion nd Properties of n Internl Mold Relese for Rigid Urethne Fom By B. G. Prker Published August 1980 Finl Report 3J 4Vr -.1. "DISTRIBUTION STATEMENT Approved for public relese; Distribution Unlimited Prepred for the United Sttes Deprtment of Energy JUJ Under Contrct Number DE-AC04-76-DPq0613.-S' Bendix Knss City Division J ST1C QÜAUn lutmwmd I

2 This report ws prepred s n ccount of work sponsored by the United Sttes Government. Neither the United Sttes nor the United Sttes Deprtment of Energy, nor ny of their employees, nor ny of their contrctors, subcontrctors, or their employees, mkes ny wrrnty, express or implied, or ssumes ny legl libility or responsibility for the ccurcy, completeness or usefulness of ny informtion, pprtus, product or process disclosed, or represents tht its use would not infringe privtely owned rights. Printed in the United Sttes of.americ Avilble From the Ntionl Technicl Informtion Service, U.S. Deprtment of Commerce, 5285 Port Royl Rod, Springfield, Virgini

3 BDX Distribution Ctegory UC-25 PREPARATION AND PROPERTIES OF AN INTERNAL MOLD RELEASE FOR RIGID URETHANE FOAM By B. G. Prker Published August 1980 Finl Report B. G. Prker, Project Leder Technicl Communictions BdldiX^ KilSS City Division

4 PREPARATION AND PROPERTIES OF AN INTERNAL MOLD RELEASE FOR RIGID URETHANE FOAM BDX , Finl Report, Published August 1980 Prepred by B. G. Prker Internl mold releses which cn be dded to urethne fom resin were synthesized nd evluted. The use of this type of relese gent elimintes the repeted clening nd recoting of molds, procedure required with surfce-pplied mold releses. The internl mold releses investigted re the rection products of ftty cid ester, contining n ctive hydrogen, nd monoisocynte. The use of n internl mold relese resulted in urethne fom with good relesbility nd excellent surfce bondbility. Severl properties of rigid urethne fom formulted with the use of n internl mold relese re presented. DC/srg This report ws prepred s n ccount of work sponsored by the United Sttes Government. Neither the United Sttes, nor the United Sttes Deprtment of Energy, nor ny of their employees, nor ny of their contrctors, subcontrctors, or their employees, mkes ny wrrnty, expressed or implied or ssumes ny legl libility or responsibility for the ccurcy, completeness or usefulness of ny informtion, pprtus, product, or process disclosed, or represents tht its use would not infringe privtely owned rights. The Bendix Corportion Knss City Division P. O. Box 1159 Knss City, Missouri A prime contrctor with the United Sttes Deprtment of Energy under Contrct Number DE-AC04-76-DP00613

5 CONTENTS Section SUMMARY DISCUSSION SCOPE AND PURPOSE PRIOR WORK ACTIVITY Preprtion of Internl Relese Agents Fom Smple Preprtion Relese Testing Wter Drop Test Adhesion Testing Comptibility Concerns ACCOMPLISHMENTS FUTURE WORK REFERENCES Pge

6 / ILLUSTRATIONS Figure Pge 1 Cross Section of Relese Test Fixture for Polyurethne Fom H 2 Relesbility of Urethne Fom Contining n Internl Mold Relese 13 3 Wter Drop Test for Urethne Fom Contining n Internl Mold Relese 14 4 Effect of n Internl Mold Relese Concentrtion on Fom Softening Temperture 17 TABLES Number Pge 1 Surfce-Applied Mold Releses 10 Relesbility of Surfce-Applied Mold Releses 12 Surfce Bondbility for Fom Contining n Internl Mold Relese!5 Bonding Screening Tests with BKC Fom System, 1^ Extrctble Levels for Fom Contining n Internl Mold Relese 18

7 SUMMARY Most mold relese gents used in the molding of rigid polyurethne fom re pplied to the internl surfces of the mold. The commonly used mold relese gents include wxes, fluorocrbon mterils, sops, nd silicone oils. These mterils form thin lyer between the surfce of the mold nd the fom, llowing for esy relese of the molded prts. This type of mold relese must be pplied prior to ech molding opertion; nd, fter repeted use, clening of the mold is required. Smll mounts of this mold relese re trnsferred to the molded prt, resulting in prt with poor surfce bondbility chrcteristics. An internl relese gent, which cn be mixed in urethne fom resin ws investigted. Internl mold relese gents were prepred in the lbortory nd evluted. The internl mold relese provided good relesbility nd resulted in urethne fom tht hs excellent surfce bondbility. Thermomechnicl nd solvent extrction dt indicte tht no comptibility problems would be expected from the use of this type of relese gent.

8 DISCUSSION SCOPE AND PURPOSE Most mold relese gents used in the molding of polyurethne fom prts re pplied to the internl surfces of the mold. A portion of this type of relese gent is often trnsferred to the surfce of the fom prt during the molding opertion. The surfces of the resulting prt must be chemiclly clened or plsm etched in order to chieve good bonding surfce prior to further ssembly. The purpose of this project ws to synthesize nd evlute internl mold relese gents which cn be dded directly to urethne fom components prior to molding. Use of this type of mold relese would eliminte plsm etching or chemicl clening of the fom surfce which requires bonding s prt of the next-ssembly opertion. PRIOR WORK In most molding opertions the internl surfces of the mold re coted with mold relese gent to prevent the resulting prt from sticking to the mold when removed. Typicl mold relese gents include wxes, sops, nd silicone oils. These mterils form thin lyer between the surfce of the mold nd the prt, dhering to neither the mold nor the prt, thus llowing for esy removl of the cured fom. There re severl disdvntges ssocited with the use of this type of relese gent. The mold relese must be pplied prior to ech molding opertion, which reduces the mount of time the mold is vilble for production. After repeted use the mold relese builds up, reducing surfce definition nd dimensionl control, thus requiring clening of the mold. In ddition, molded prts become coted with thin film of the relese gent, which reduces surfce bondbility. It ws disclosed in U.S. Ptent 3,726,952 tht the ddition of slt of ftty cid nd n mine to polyurethne fom mixture could eliminte the need for surfce-pplied mold relese. 1 This type of internl mold relese resulted in excellent mold relese properties nd good flow properties in the mold, s well s providing n ntisttic effect on the finished prt. Storge of the fom components contining this internl mold relese, however, resulted in seprtion of the mold relese from the resin. For this reson, dequte stirring of the rection components prior to mixing ws required.

9 In ddition, U.S. Ptent 3,925,527 hs disclosed tht excellent mold relese properties cn lso be obtined by pplying the rection product of ftty cid ester, contining n ctive hydrogen nd monoisocynte, to polyurethne fom mixture._ This internl mold relese remins soluble in the isocynte side of the rection mixture nd does not rect with the prepolymer. ACTIVITY Preprtion of Internl Relese Agents A three-step rection process ws used in the preprtion of internl relese gents. The first step ws to prepre ftty cid ester contining one free hydroxyl group on the molecule. As typicl rection, 846 grms of oleic cid (3 moles), together with 136 grms of penterythritol (1 mole), were plced in 2-liter resin rector nd heted while stirring for 24 hours t 150 C under nitrogen tmosphere. The mixture ws then heted for 8 dditionl hours t 150 C under vcuum. The rection product hd hydroxyl number of 48 nd n cid number of 6, s determined by ASTM D The resulting liquid (Compound I) hd the following generl structure. R.-C-CH o 0H, Compound I 1, 2 R l Ftty Acid Ester, where R l = CH 3 (CH 2 ) (CH) 2 (CH 2 ) C-0-CH 2-0 The second rection step ws the preprtion of monoisocynte. Tolylene diisocynte (TDI) (522 grms), 80/20 isomer rtio, ws plced in 2-liter resin rector nd heted to 60 C while purging with dry nitrogen. The TDI ws stirred with mgnetic stirrer while 642 grms of tetrdecnol ws dded slowly. The ddition rte of tetrdecnol ws djusted in order to mintin rection

10 temperture of 60 ± 5 C. After complete ddition of the tetrdecnol, the rection mixture ws heted for 30 minutes t 60 C, nd then ws llowed to cool to room temperture. The resulting monoisocynte (Compound II) hd the following generl structure. 0 H R 2 _0-C-NYOVCH 3, Compound II ^^^ NCO Monoisocynte, where K) R 2 = CH, The finl step involved the rection of the ftty cid ester with the monoisocynte. Typiclly, 967 grms of rection product (Compound I) nd 388 grms of rection product (Compound II) were plced in 2-liter resin rector nd heted to 60 C while stirring with mgnetic stirrer nd purging with dry nitrogen. The rector temperture ws mintined t 60 ± 5 C until bsence of isocynte ws observed by infrred nlysis; for exmple, loss of bsorption t 2260 cm -1. The resulting mold relese (Compound III) hd the following generl structure. R! OH CH I II i i R 1 -C-CH 2-0-C-N- / J s l > Compound III R l N-C-O-R 2 I II H 0 Internl Mold Relese. Steric cid ws evluted s n lternte ftty cid, used in prepring the ftty cid ester, but this resulted in solid mteril. Further rection of this ftty cid ester with the monoisocynte (Compound II) lso resulted in solid mteril with lower solubility thn the oleic cid ester in the isocynte side of the fom system. Testing of this relese gent ws discontinued.

11 An lternte method for the preprtion of the ftty cid ester contining free hydroxyl group ws lso investigted. Oleic cid (564 grms) nd 760 grms of Epon 828 epoxy were plced in.2-liter resin rector, heted to 150 ± 5 C, nd stirred under nitrogen tmosphere for 8 hours. The resulting ftty cid ester (Compound IV) hd the following generl structure. 0 I H CI?3 Compound IV R 1 -C-CH /ÖY-C ^OV-0-CH 2 -C-CH fo\-c ^ÖYo-CH 2 -CH-CH 2, Epoxy Ftty Acid Ester, where n = 1. CH q 0 H n CH 0,3 /X This ftty cid ester, contining epoxy, ws rected with the monoisocynte (Compound II), s described in the previous procedure. The resulting product ws solid t room temperture. It ws resoned tht incorportion of rective epoxy group into the internl mold relese structure might result in urethne fom hving good bondbility to epoxy dhesives. Fom Smple Preprtion Vrying levels of the internl mold releses were dded to BKC , polyrylisocynte/sucrose-bsed polyether polyol fom system. Fom specimens were molded in luminum molds with new luminum fcepltes to yield fom blocks (152.4 by by 25.4 mm) for dhesion tests nd in luminum cylinders (44.5 mm by 26.8 mm I.D.) for relese tests. The fom test blocks were prepred from BKC , formulted t n isocynte index of 1.2, molded to density of 320 kg/m3 nd cured for 8 hours t 163 C. The relese test specimens were llowed to cool to room temperture slowly, to prevent excessive fom shrinkge which could influence the fom relesbility. The relesing force of some surfce-pplied relese gents ws lso mesured s comprison with the internl mold releses. Tble 1 lists the surfce-pplied relese gents tested, their generl composition, nd the mnufcturers. The surfce-pplied mold releses were coted on the interior of the 44.5-mm by 26.8-mm-I.D, cylinders nd filled with BKC fom system in which no internl mold relese ws dded. CH 3

12 Tble 1. Surfce-Applied Mold Releses Mold Relese Mnufcturer Composition Frekote 11 Frekote 33 MS 136 Cmie 666 Surfk OSR Frekote, Inc. Frekote, Inc. Miller-Stephenson Chemicl Compny, Inc. Cmie Compny Gibrltr, Inc. Chem-Trend, Inc. Silicone Silicone Fluorocrbon Silicone Ftty Acid Ester Hydrocrbon Wx Relese Testing A new test method ws developed for mesuring the relesbility of molded urethne fom smples. A Chtillon model HTCM compression tester ws operted t crosshed speed of 0.31 mm/s when forcing fom plugs from luminum cylinders s shown in Figure 1. The sher force required for relese of the urethne fom smples hving mold surfce re of cm 2 ws determined by mesuring the mximum force required to push the urethne fom plug out of the luminum cylinder. Use of internl mold releses contining epoxy groups resulted in such lrge relese force tht filure of the urethne fom occurred prior to its relese. Additionl testing of internl mold releses contining epoxy groups ws, therefore, discontinued. The results of the relese tests re listed in Tble 2 nd illustrted in Figure 2. Incresing the concentrtion of internl mold relese resulted in decrese in the relese force required (Figure 2). Compring the relese forces of surfce-pplied mold relese (Tble 2) with those of internl mold releses indictes tht the internl mold relese performed s well s, or better thn, surfcepplied mold releses. Wter Drop Test A wter drop test, used s reltive mesure of surfce wetbility, thereby provided wy of predicting reltive bond strengths. Wter drop tests were performed on urethne fom smples by plcing 5-jul drop of wter on molded surfce nd mesuring 10

13 FORCE.U.W....' J V. U o:.-.o?-y-ö\<>o.-.<s:c>- URETHANE FOAM ALUMINUM CYLINDER ^. o/i-p;pv5:o. \ STEEL CYLINDER BASE PLATE Figure 1. Cross Section of Relese Test Fixture for Polyurethne Fom the dimeter of the drop, using n opticl microscope. Generlly, lrge drop dimeter is indictive of high tensile strength in n dhesive-bonded specimen. The results of this testing (Figure 3) show mrked decrese in surfce wetbility when incresing mold relese concentrtion from 2 prts per hundred resin (phr) to 5 phr. A possible reduction in surfce bondbility t concentrtions bove 2 phr is indicted. Adhesion Testing Adhesion properties were determined from 28.7-mm-dimeter fom cylinders, mchined from the by by 25.4-mm fom blocks. Aluminum end dpters were bonded to both molded surfces of fom specimens, using rigid epoxy system mixed in the rtio of 10 prts-by-weight (pbw) Epibond 104 nd 1 pbw Hrdener 951, mnufctured by Furne Plstics, Inc. Tensile properties (Tble 3) indicte tht there is not n pprecible effect of mold relese concentrtion on the tensile strengths mesured even though wter drop tests indicted there might be. 11

14 Tble 2. Relesbility of Surfce-Applied Mold Releses Relese Sher Mold Relese Force (kp) Frekote Frekote * MS Cmie * Surfk 14 OSR 12 Epoxy-Internl (10 phr)** 333* NOTE: Averge of three smples for ech mold relese. *Fom stuck to cylinder wll. **Internl mold relese contining epoxy groups (Compound IV). Test specimens used in plsm-tretment study 3 were prepred in the sme mnner s those just discussed. A comprison of test results from foms prepred with the internl mold relese (Tble 3) nd foms tht were plsm-etched (Tble 4) shows the tensile strengths to be comprble. Comptibility Concerns Internl mold relese gents resulted in urethne fom with good relesbility nd excellent surfce bondbility. However, it ws resoned tht the lrge level of reltively inert highmoleculr-weight mold relese might plsticize the fom nd provide lrge mount of migrtble mteril which could cuse comptibility problems. Softening tempertures (T s ) (Figure 4) of the fom smples were run on Perkin Elmer thermomechnicl nlyzer. These tempertures were mesured, using heting rte of 5 C/minute, with n expnsion probe nd 10-grm weight on the smple. A smll degree of plsticizing occurred t mold relese level of 10 phr (Figure 4). 12

15 - o- CO ih CO z I-» O cd ä fn x: -P S3 l l S3 H: cd 2 o z O u n S i &ß z S3 LU H u S3 cd LU «1 < 0 LU I o Q _i Q 5 ^^ S cd o P4 <D -* Q S3 cd Z Ä 3 +-> o <D. ^i 5 ID -«o o Ö «H CN ^r- o >> p H rh H X2 cd CO cd <D rh 03 CM f-i (odho 3DyOJ W3HS 3SV313y 00 H P<4 13

16 s~\ -C %- z O 0 Cfl CO H PCj o ih 0 s ih cö Ö JH P M ä i bü 2 i z H LU H U CO z -P Ü ä u 0 LU ü 3 LU _l UJ CJ CO 0 fo Q _i O 5 Ö ZÜZ X! 4-> z ID O t=>.? fc O 0 u =H P CQ EH 0 fc Q fn P cö CO (uuuu) yiowvi doy VQLV/\ fcuo H Pn 14

17 Tble 3. Surfce Bondbility for Fom Contining n Internl Mold Relese Tensile Strength (MP) Mold Relese Concentrtion (phr)* X S** 10 2: / NOTE: Averge vlues for four smples ech, Compound III. **Stndrd devition. Solvent extrctions, using toluene nd Soxhlet extrctor, were performed on the fom smples for 24 hours. The results (Tble 5) showed the mount of extrctbles to be very low even t mold relese concentrtion of 10 phr. No comptibility problems were expected with the use of this mold relese. ACCOMPLISHMENTS Internl mold relese gents which cn be dded to urethne fom components prior to molding were synthesized nd evluted. The use of this type of mold relese resulted in urethne fom with very good relesbility nd bondbility, comprble to plsmetched fom surfces. At mold relese concentrtions t or below 5 phr there ws no noticeble effect on the softening temperture of the fom, nd the level of extrctbles ws below 0.2 percent. FUTURE WORK Although there ws only miniml effect t high mold relese concentrtions on the softening point of the foms, compression tests should lso be performed to determine if there re ny losses in lod-bering properties with the use of this mold relese. If n internl mold relese is used in production prts, scle-up to production quntities of this mteril would be required in the Polymer Pilot Plnt. 15

18 Tble 4. Bonding Screening Tests With BKC Fom System Tensile Strength (MP) As Molded Plsm- -Tr eted Relese System X s* X s* OSR Ftty Acid Ester Silicone Oil OSR** Stndrd devition. **BKC fom system. 16

19 Ö H Ö +-> «H O CO S cs O PH O Ö o H cd f-i -P Ü o CO o rh «T3 rh i?h +-> S t-h Ö d U «H 3 0 P cti +-> fn Ü «H s «H H EH O.) s l '3>iniV>QdW31 9NIN3UOS o ^_ ^ U 3 bj3 H PH 17

20 Tble 5. Extrctble Levels for Fom Contining n Internl Mold Relese Mold Relese Concentrtion (phr)* Extrctbles (percent) / NOTE: Averge vlues for two smples ech. *Compound III 18

21 REFERENCES 1 Boden, et l, U.S. Ptent 3,726,952, Kleimnn, et l, U.S. Ptent 3,925,527, 1975, 'S. L. DeGisi nd C. H. Smith, Improved Bondbility of Molded Rigid Urethne Fom by Plsm Tretment (SPE Conference Pper). UNCLASSIFIED. Bendix Knss City: BDX , November, (Avilble From NTIS) 19

22 BDX , PREPARATION AND PROPERTIES OF AN INTERNAL MOLD RELEASE FOR RIGID URETHANE FOAM, B. G. Prker, Finl, August Internl mold releses which cn be dded to urethne fom resin were synthesized nd evluted. The use of this type of relese gent elimintes the repeted clening nd recoting of molds, procedure required with surfcepplied mold releses. The internl mold releses investigted re the rection products of ftty cid ester, contining n ctive hydrogen, nd monoisocynte. The use of n internl mold relese resulted in urethne fom PLASTICS: Mold Releses PREPARATION AND PROPERTIES OF AN INTERNAL MOLD RELEASE FOR RIGID URETHANE FOAM, B. G. Prker Finl, BDX , August Internl mold releses which cn be dded to urethne fom resin were synthesized nd evluted. The use of this type of relese gent elimintes the repeted clening nd recoting of molds, procedure required with surfcepplied mold releses. The internl mold releses investigted re the rection products of ftty cid ester, contining n ctive hydrogen, nd monoisocynte. The use of n internl mold relese resulted in urethne fom PREPARATION AND PROPERTIES OF AN INTERNAL MOLD RELEASE FOR RIGID URETHANE FOAM, B. G. Prker, Finl, BDX , August Internl mold releses which cn be dded to urethne fom resin were synthesized nd evluted. The use of this type of relese gent elimintes the repeted clening nd recoting of molds, procedure required with surfcepplied mold releses. The internl mold releses investigted re the rection products of ftty cid ester, contining n ctive hydrogen, nd monoisocynte. The use of n internl mold relese resulted in urethne fom

23 with good relesbility nd excellent surfce bondbility. Severl properties of rigid urethne fom formulted with the use of n internl mold relese re presented. with good relesbility nd excellent surfce bondbility. Severl properties of rigid urethne fom formulted with the use of n internl mold relese re presented. with good relesbility nd excellent surfce bondbility. Severl properties of rigid urethne fom formulted with.the use of n internl mold relese re presented.