CA1068199A - Stripping composition for thermoset resins - Google Patents
Stripping composition for thermoset resinsInfo
- Publication number
- CA1068199A CA1068199A CA252,228A CA252228A CA1068199A CA 1068199 A CA1068199 A CA 1068199A CA 252228 A CA252228 A CA 252228A CA 1068199 A CA1068199 A CA 1068199A
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- CA
- Canada
- Prior art keywords
- compound
- aromatic
- composition
- boiling point
- point over
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
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- Manufacture Of Motors, Generators (AREA)
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- Paints Or Removers (AREA)
Abstract
STRIPPING COMPOSITION FOR THERMOSET RESINS
AND METHOD OF REPAIRING ELECTRICAL APPARATUS
ABSTRACT OF THE DISCLOSURE
A stripper composition for thermoset resins is disclosed which comprises about 1 to about 99% of an aro-matic compound which has a boiling point over 180°C and is a phenol or a primary or secondary amine, and about 1 to about 99% of a carboxylic acid compound which has a boiling point over 180°C and is a rosin acid or a mono- or di-carboxylic fatty acid or an ester thereof. The composition also pre-ferably includes sufficient hydrogen bonding compound to react with any acid present in the composition plus about 20 to about 50% in excess of that amount. A swelling agent is also preferably included.
AND METHOD OF REPAIRING ELECTRICAL APPARATUS
ABSTRACT OF THE DISCLOSURE
A stripper composition for thermoset resins is disclosed which comprises about 1 to about 99% of an aro-matic compound which has a boiling point over 180°C and is a phenol or a primary or secondary amine, and about 1 to about 99% of a carboxylic acid compound which has a boiling point over 180°C and is a rosin acid or a mono- or di-carboxylic fatty acid or an ester thereof. The composition also pre-ferably includes sufficient hydrogen bonding compound to react with any acid present in the composition plus about 20 to about 50% in excess of that amount. A swelling agent is also preferably included.
Description
.
BACKGROUND OF THE INVENTION
Defective-motors are repaired by removing the con-ductor coils frPm the magnetic iron core and re-windlng'the core. The coils are, of course, insulated, and are usually held in place by varnish lmpregnant, wedges, and end bloc'.~s.
This material, which conslsts largely of thermoset reslns, must be removed or destroyed in order'to remove the coils.
The usual practice is to burn out the thermoset resins.
~urning, however, produces pollutants, uses energy, and leaves a char which is difficult to remove.
An alternative procedure is to immerse the motor in a stripper composition. Commercial strippers, however, swell the resin wlthout destroying it, and a swelled resln may be no easier to remove than an unswelled resin. More-over, most strippers attack only one or only a few types of resins. Motors which are turned over to repair shops, ., .
., .
., .
' .:
!
'' '" ` ' ', ' ' ;' ', ' : ' . ' ,: . . . ' '. , : . ' . ~- ; . . ' ' ' ' . ' " ' , . ' ~', " " ' '' ' .~ ' . ' '' ~ ' , .' , : . ', ' .. ' : . . ' . ' ' , .
. ;` ,' '. ' . ~' ' ' ' ' ' . ' , . 1 '' `I ', . '. ., ' 1 ', '' ' ' , ., ' ' , ~ , ' 1~199 .
however, may contain many different resins. The motor owner - may not know what resins are in the motor nor can this information be readlly ascertained. Therefore, there is no way of knowing which stripper composition, if any, wlll be efrective on a given motor.
PRIOR ART
, U.S. Patent 3,669,740 dlscloses a compositlon for cleaning polyamide comprising at least 25% carboxylic acid such as olelc acid and a diluent such as polyethylene glycol.
U.S. Patent 3,681,250 discloses a paint stripper comprising an alkaline material, ethylene glycol monophenyl ether, and a phenol such as B-naphthol.
U.S. Patent 3,563,900 discloses a paint stripper comprlslng an aqueous disperslon of B-naphthol.
SUMMARY O~ THE INVENTION
We have found a stripper composition which will destroy most thermoset resins, including epoxies, polyesters, phenollcs, melamine, ureas, silicones~ and acrylics.~ The only the.rmoset resins we have found whlch are not readily attacked by the stripper are diphenyl oxlde polymers and aromatic polyimides and polyamide imides.
The stripper does not merely swell the resln, although a swelllng agent is preferably included in the com-position to render the resin more accessible to attack, but ;~ rather it attacks the resin by breaking the polymers into smaller molecules which are soluble, whereas the polymer is not.
The stripper produces very little pollution since vapors are condensed and returned. It is apparently of low :'' ' ~ ' ' At~ ' - - . . , : -, , , : .
10~81'19 :-- . .
toxlclty and does not attack common metals such as iron, copper, and aluminum, nor does lt attack glass or ce]lulose. ~-.. .: ' Also, it has no apparent erfect on the interlaminar insula- ;
'! tlon of electrical equipment. It works rapidlyj ln most .
cases requiring only a few hours to strlp a motor stator or rotor, and uses less energy than does burning the insulatlon.
Also~ although a batch of the strlpper will last for some time, it can be renewed by the addltion of ingredients used ;
up ln the stripplng reactlon or otherwise lost.
; 10 ~ESCRIPTION OF THE INVENTION
; Flgure 1 is a cross-sectional view of a motor stator immersed ln a composltlon accordlng to thls lnven-tlo~.
; Flgure 2 ls a flow chart of the process of thls lnventlon.
The composltlon of thls lnvention comprises a reactive component of about l to about 99% (all percentages hereln are by welght based on the reactive component) of an aromatic compound and about l to about 99% of a carb.oxyllc ;20 acid compound. Preferably, for a more reactlve composltion, i . . .` the amount of aromatic compound ls about lO to about 50% and the amount o~ carboxylic acid compound is about 50 to about 90%- ' ' ... . .
, The aromatlc compound is a phenol or a primary or -i secondary amine whlch has a boillng polnt over 180C, and preferably over 250C. The amine or hydroxy group must be ;
~on an aromatic rlng slnce allphatlc compounds such as urea ~ -;~and guanldlne do not work on a wlde range of thermoset resins. In the secondary amine group, -NHR, the R group may ~ 30 be alkyl to C4. Primary amlnes are preferred to secondary ; -3-.,. :
. , ' '.
amines because primary amines are mo~e active and less expensive. Phenols, however, are preferred to amines be-cause amlnes are more expensive and more toxlc. Examples of suitable aromatic compounds include ~-naphthol, ~-naphthol, m-phenylene diamine, aniline, resorcinol, hydroquinine, cresol, catechol, and p-phenyl phenol. Resorcinol and ~-naphthol are preferred because they are among the most actlve compounds in attacking resins. Mixtures of aromatlc compounds are also contemplated.
The carboxylic acid compound is a carboxylic acid which has a boiling point over lôOC and preferably over 250C. Esters of the acids may also be used. The car-boxylic acid can be aliphatic, alicyclic, or aromatic.
Rosin acids and fatty acids are preferred because they have low volatility and are readily available at a low cost.
Mono-carboxyllc fatty aclds are preferred to dicarboxylic fatty acids because they are less expensive. Saturated or mono-unsaturated fatty acids are preferred to di- or poly-unsaturated fatty acids because the latter may oxidize.
20 . ~xamples of suitable carboxylic acid compounds include llnseed fatty acid, tall oil, and tall pltch; Tall pitch is preferred because it ls less expensive and more active because it contains swelling agents. Tall pitch is a by-product of tall oil refining and is commonly a complex mixture of about 20 to about 50% fatty acids~ principally oleic acid, about 20 to about 50% rosin acids, principally abletic acid, and about 20 to about 50% neutral unsaponi-flable compounds. Tall oil is a by-product of paper manu-facture and is simllar in composition to tall pitch but has less neutral unsaponifiable material and more rosln and . 101;81~
:
; fatty acids. Mlxtures of fatty aclds and rosln acids mayalso be used. - ~
The compositlon al60 preferably includes enough of ~:
a hydrogen bonding compound to react with any acid whlc~ may be present plus an excess of about 20 to about 50 phr (parts by welght per 100 parts of the reactlve component). The ~. .
purposes of the hydrogen bonding compound are to retard the evaporatlon of the aromatic compound and attack resins beIng strlpped. The hydrogen bondlng compound has at least one ; 10 unshared electron pair capable of entering into a hydrogen . bond wlth the amine or hydroxyl group of the aromatic -compound. The hydrogen bonding compound has a bolling point ove~ 180C and preferably over 250C. Qulnollne and its derlvatlves may be used, but hydroxyl compounds are pre-ferred because they are le~s expensive. The hydroxyl com-pound should hav~ non-vicinal hydroxyl groups as compounds with vlcinal hydroxyl groups, such as glycerol, do not work as well. Examples of suitable hydrogen bonding compounds lnclude triethylene glycol (TEG), polypropylene glycol, quinoline, and polyethylene glycol, TEG or a mixture of high bolllng glycols ls preferred as they are the most effective . ..................................................................... :
~ Mlxtures of hydrogen bondlng compounds are also contem-;j plated.
.: . .
The composition preferably includes up to about 50 phr of a swelling agent. The preferred amount of swélling ;
agent wh~ch gives the most effective results is about 5 to about 30 phr. The function of the swelling agent is to ~;~ loosen the structure of the resins so that they can be more readily chemically attacked. The swelling agent is a solvent for the resin under attack in the resin's un-cross-, ~ 99 linked state. A compound which dlssolves an un-crossllnked resln wlll swell a crosslinXed resln. The swelllng agent has a boillng polnt over about 180C and preferably over 250C.- Examples lnclude plne oll and terpenold compounds.
The preferred swelllng agents, however, are the neutral unsaponifiable components of tall oll and tall pitch. Thus, the use of tall oll or tall pitch will automatically lnclude a swelllng agent. Mlxtures of swelllng agents are also ! contemplated.
: 10 The compositlon ls prepared by simply mixing the ~f~
lngredlents ln the proper proportions. The composltlon is then heated to about 180C to about 250C. At temperatures lower than about 180C the stripplng action requlres too much time, although thin coatings such as paints can be stripped ln a reasonable tlme at temperatures as low as . .
150C. At temperatures over 250C evaporation becomes a problem. At all temperatures the vapors from the composl-tlon are passed through a condenser and the condensate ls .. ,~ , .
returned to mlnlmiæe losses and reduce air pOllUtiOff,: :
The obJect to be strlpped is lmmersed into the composltion untll it has been observed to be stripped. Ir the obJect is a motor stator or rotor, it ls first prepared ,. .
~ by sawlng off the ends of the colls. If the rotating ~.,, ~ . . .....
i apparatus is form wound lt may not be necessary to cut the ~ ~
. ,, . . - .
i ends, but mush wound apparatus must be cut at at least one '~ end. -.. , . ~ . .
In Flgure 1 coils 1 of stator 2 have been cut at 3. The other end Qf the colls 4 has not been cut to provlde ;-.. . ..
~`something to grasp whlle pulling the colls from lamlnated 30 core 5. The stator ls lmmersed ln stripplng composltlon 6 ;
-6- ~ ~
~:
t ~0t~81~9 held in tank 7. About 1 to about 6 hours ls usually re-~uired to strip a motor coil.
The stripped ob~ect is removed, drained, cooled, and washed with a solvent such as toluene, trichloroethy-lene, or perchloroethylene. For coils vapor degreasing is usually not adequate to remove all of the stripping com- -posltion from between the laminations, and leaching in a solvent ls used as a supplemental cleaning step. Figure 2 shows the steps involved in removing coils f~om a motor, stator or rotor using the process of this invention. In Figure 2 steps 3 and ~ can be reversed.
While the composition was especially designed for strippi~g motors, it can also be used to strip generators, transformers, and other electrical conductors insulated wlth thermoset resins. The stripper can also be used on lamin-ates to determine khe amount of filler they contain, to clean ob~ects contaminated w1th resins, or for other pur-poses.
Losses of the composition can occur due to en-trainment on the ob~ect stripped, evaporation, oxidation,and reaction of the components with the resins. Therefore, ~ from time to time the composition is renewed by replacing '! those components which have been lost or used up.
', ' ' ' ;
.. ' '` ' ' .
.
,. ' ' :
, . . .
,''' ~ .
~(~;81~
EXAMPLE L
.
. StrIpper composfti'ons were prepared~and tested.-The following table gives the compositions and the results of testing ,them on various thermoset lamlnates after 6 hours at 250C. ~, ~ . . ~ . . , .
: , .. - Lamlnate . ..... .
.
High temperature Epoxy cured . , .
polyester with Polyester Phenolic Stripper Dlcyandiamlde : llnseed oil fatty Surface attack Lamlnate des- Laminate ,No attack , acid (LOFA) but no delami- troyed destroyed .
,. .; . natlon 100 pbb LOFA . No AttackLamlnate des-. Sllght . Sllght 50 pbw ~-napthol troyed attack attack 100 pbw LOFA Surface attack Laminate des- Laminate Laminate 50 pbw~g-napthol but no delami- , troy0d destroyed destroyed : 50 pbw triethy- nation . . . .
: _ lene glycol lOO pbw tall oll LaminateLamlnate des- Laminate Lamlnate . 50 pbw ~-napthol destroyed , - troyed destroyed destroyed 50 pbw triethy- . . :. ....... .
. ~ene glycol ..
.
. lOO pbw linseed, No attack . : Lamlnate,des- Lamlnate Lamlnate oll . troyed destroyed destroyed.
,. -.5C.pbw~ -napthol 50 pbw triethy- . . ........... . . . .
_lene glycol . . . ~ , 100 pbw tall Laminate Lamlnate des- Lamlnate Laminate ' .-,! pitch~ destroyed troyed destroyed destroyed : :
50 pbw resor- . . , . ~ , --clnol - . . .
50 pbw triethy- , , - - , . .
~ lene glycol 100 pbw benzoic Lamlnate Lamlnate des- Lamlnate Lamlnate ,: , acld destroyed troyed destroyed destroyed :
50 pbw ~-napthol .
50 pbw triethy-~" lene glycol _ . . . ,,~ ..
Sold by Unlon Camp under the trademark "Unltol DP" the composltlon of which is glven as 45~ fatty aclds and esterlfled aclds, ~0% rosln aclds, and 35~ unsaponiflables . ,.
. . '', ~
: ~ .
.
::
The above table shows that whlle all of the strip~
pers were able to destroy some o~ the laminates, only the ; fourth, sixth, and seven~h composltions were able to destroy all of the laminates.
Based on the results of Example 1, a composltion was prepared of 100 pbw tall oil, 50 pbw ~-naphthol, and 50 pbw triethylene glycol. A number of different insulating materials were placed in this stripper at different tempera-; 10 tures and for different lengths of time. The ~ollowing table gives the results:
Material Result lO mil resin treated destroyed in 10 min. at glass cloth 175C
15 mll mica board resin dlssolved wlthin 6 hours at 250C
! ' black varnish-treated resln dissolved within 1 i asbestos hour at 250C
varnished flexible mica resin dissolved within 2 hours at 250C
sllicone-varnished resin dissolved within 1 sleeving hour at 250C
polyester glass resin dissolved within 4 bonding hours at 250C
melamine laminate destroyed within 6 hours : at 250C
. polyethylene tere- dissolved within 4 hours phthalate mat at 250C
; 30 The end turns of four stators having frame sizes 140 and one having frame size 215 were sawed off, and the : stators were immersed in a composition at 250C of 25%
~-naphthol, 25% triethylene glycol, and 50% tall pitch.
Both stators used No. 61212 KA wire (polyester enamel with a , _g_ .-~ .
~ . ~
nylon overcoat), a Nomex~wedge and slot cell (an aromatic tl~
polyamlde-imide paper sold by DuPont), and a Dacron/Mylar/
- r~
Dacron phase (polyethylene terephthalate/polyimlde/polyethy-lene terephthalate). The insulation systems o~ these stators was more complicated and resistant to solvent penetration than most commerclal stators of thls slze. The followln~
table gives the results.
- Frame Required Sample Slze Other Insulation Treatment Tlme (hrs) , 1 140 One dlp and bake ln Westinghouse 1.5 ~ 32102 AJ varnish (a phenolic-alkyd); end tu~ns brush coated with Epoxylite' No. 213 (an epoxy) . .
BACKGROUND OF THE INVENTION
Defective-motors are repaired by removing the con-ductor coils frPm the magnetic iron core and re-windlng'the core. The coils are, of course, insulated, and are usually held in place by varnish lmpregnant, wedges, and end bloc'.~s.
This material, which conslsts largely of thermoset reslns, must be removed or destroyed in order'to remove the coils.
The usual practice is to burn out the thermoset resins.
~urning, however, produces pollutants, uses energy, and leaves a char which is difficult to remove.
An alternative procedure is to immerse the motor in a stripper composition. Commercial strippers, however, swell the resin wlthout destroying it, and a swelled resln may be no easier to remove than an unswelled resin. More-over, most strippers attack only one or only a few types of resins. Motors which are turned over to repair shops, ., .
., .
., .
' .:
!
'' '" ` ' ', ' ' ;' ', ' : ' . ' ,: . . . ' '. , : . ' . ~- ; . . ' ' ' ' . ' " ' , . ' ~', " " ' '' ' .~ ' . ' '' ~ ' , .' , : . ', ' .. ' : . . ' . ' ' , .
. ;` ,' '. ' . ~' ' ' ' ' ' . ' , . 1 '' `I ', . '. ., ' 1 ', '' ' ' , ., ' ' , ~ , ' 1~199 .
however, may contain many different resins. The motor owner - may not know what resins are in the motor nor can this information be readlly ascertained. Therefore, there is no way of knowing which stripper composition, if any, wlll be efrective on a given motor.
PRIOR ART
, U.S. Patent 3,669,740 dlscloses a compositlon for cleaning polyamide comprising at least 25% carboxylic acid such as olelc acid and a diluent such as polyethylene glycol.
U.S. Patent 3,681,250 discloses a paint stripper comprising an alkaline material, ethylene glycol monophenyl ether, and a phenol such as B-naphthol.
U.S. Patent 3,563,900 discloses a paint stripper comprlslng an aqueous disperslon of B-naphthol.
SUMMARY O~ THE INVENTION
We have found a stripper composition which will destroy most thermoset resins, including epoxies, polyesters, phenollcs, melamine, ureas, silicones~ and acrylics.~ The only the.rmoset resins we have found whlch are not readily attacked by the stripper are diphenyl oxlde polymers and aromatic polyimides and polyamide imides.
The stripper does not merely swell the resln, although a swelllng agent is preferably included in the com-position to render the resin more accessible to attack, but ;~ rather it attacks the resin by breaking the polymers into smaller molecules which are soluble, whereas the polymer is not.
The stripper produces very little pollution since vapors are condensed and returned. It is apparently of low :'' ' ~ ' ' At~ ' - - . . , : -, , , : .
10~81'19 :-- . .
toxlclty and does not attack common metals such as iron, copper, and aluminum, nor does lt attack glass or ce]lulose. ~-.. .: ' Also, it has no apparent erfect on the interlaminar insula- ;
'! tlon of electrical equipment. It works rapidlyj ln most .
cases requiring only a few hours to strlp a motor stator or rotor, and uses less energy than does burning the insulatlon.
Also~ although a batch of the strlpper will last for some time, it can be renewed by the addltion of ingredients used ;
up ln the stripplng reactlon or otherwise lost.
; 10 ~ESCRIPTION OF THE INVENTION
; Flgure 1 is a cross-sectional view of a motor stator immersed ln a composltlon accordlng to thls lnven-tlo~.
; Flgure 2 ls a flow chart of the process of thls lnventlon.
The composltlon of thls lnvention comprises a reactive component of about l to about 99% (all percentages hereln are by welght based on the reactive component) of an aromatic compound and about l to about 99% of a carb.oxyllc ;20 acid compound. Preferably, for a more reactlve composltion, i . . .` the amount of aromatic compound ls about lO to about 50% and the amount o~ carboxylic acid compound is about 50 to about 90%- ' ' ... . .
, The aromatlc compound is a phenol or a primary or -i secondary amine whlch has a boillng polnt over 180C, and preferably over 250C. The amine or hydroxy group must be ;
~on an aromatic rlng slnce allphatlc compounds such as urea ~ -;~and guanldlne do not work on a wlde range of thermoset resins. In the secondary amine group, -NHR, the R group may ~ 30 be alkyl to C4. Primary amlnes are preferred to secondary ; -3-.,. :
. , ' '.
amines because primary amines are mo~e active and less expensive. Phenols, however, are preferred to amines be-cause amlnes are more expensive and more toxlc. Examples of suitable aromatic compounds include ~-naphthol, ~-naphthol, m-phenylene diamine, aniline, resorcinol, hydroquinine, cresol, catechol, and p-phenyl phenol. Resorcinol and ~-naphthol are preferred because they are among the most actlve compounds in attacking resins. Mixtures of aromatlc compounds are also contemplated.
The carboxylic acid compound is a carboxylic acid which has a boiling point over lôOC and preferably over 250C. Esters of the acids may also be used. The car-boxylic acid can be aliphatic, alicyclic, or aromatic.
Rosin acids and fatty acids are preferred because they have low volatility and are readily available at a low cost.
Mono-carboxyllc fatty aclds are preferred to dicarboxylic fatty acids because they are less expensive. Saturated or mono-unsaturated fatty acids are preferred to di- or poly-unsaturated fatty acids because the latter may oxidize.
20 . ~xamples of suitable carboxylic acid compounds include llnseed fatty acid, tall oil, and tall pltch; Tall pitch is preferred because it ls less expensive and more active because it contains swelling agents. Tall pitch is a by-product of tall oil refining and is commonly a complex mixture of about 20 to about 50% fatty acids~ principally oleic acid, about 20 to about 50% rosin acids, principally abletic acid, and about 20 to about 50% neutral unsaponi-flable compounds. Tall oil is a by-product of paper manu-facture and is simllar in composition to tall pitch but has less neutral unsaponifiable material and more rosln and . 101;81~
:
; fatty acids. Mlxtures of fatty aclds and rosln acids mayalso be used. - ~
The compositlon al60 preferably includes enough of ~:
a hydrogen bonding compound to react with any acid whlc~ may be present plus an excess of about 20 to about 50 phr (parts by welght per 100 parts of the reactlve component). The ~. .
purposes of the hydrogen bonding compound are to retard the evaporatlon of the aromatic compound and attack resins beIng strlpped. The hydrogen bondlng compound has at least one ; 10 unshared electron pair capable of entering into a hydrogen . bond wlth the amine or hydroxyl group of the aromatic -compound. The hydrogen bonding compound has a bolling point ove~ 180C and preferably over 250C. Qulnollne and its derlvatlves may be used, but hydroxyl compounds are pre-ferred because they are le~s expensive. The hydroxyl com-pound should hav~ non-vicinal hydroxyl groups as compounds with vlcinal hydroxyl groups, such as glycerol, do not work as well. Examples of suitable hydrogen bonding compounds lnclude triethylene glycol (TEG), polypropylene glycol, quinoline, and polyethylene glycol, TEG or a mixture of high bolllng glycols ls preferred as they are the most effective . ..................................................................... :
~ Mlxtures of hydrogen bondlng compounds are also contem-;j plated.
.: . .
The composition preferably includes up to about 50 phr of a swelling agent. The preferred amount of swélling ;
agent wh~ch gives the most effective results is about 5 to about 30 phr. The function of the swelling agent is to ~;~ loosen the structure of the resins so that they can be more readily chemically attacked. The swelling agent is a solvent for the resin under attack in the resin's un-cross-, ~ 99 linked state. A compound which dlssolves an un-crossllnked resln wlll swell a crosslinXed resln. The swelllng agent has a boillng polnt over about 180C and preferably over 250C.- Examples lnclude plne oll and terpenold compounds.
The preferred swelllng agents, however, are the neutral unsaponifiable components of tall oll and tall pitch. Thus, the use of tall oll or tall pitch will automatically lnclude a swelllng agent. Mlxtures of swelllng agents are also ! contemplated.
: 10 The compositlon ls prepared by simply mixing the ~f~
lngredlents ln the proper proportions. The composltlon is then heated to about 180C to about 250C. At temperatures lower than about 180C the stripplng action requlres too much time, although thin coatings such as paints can be stripped ln a reasonable tlme at temperatures as low as . .
150C. At temperatures over 250C evaporation becomes a problem. At all temperatures the vapors from the composl-tlon are passed through a condenser and the condensate ls .. ,~ , .
returned to mlnlmiæe losses and reduce air pOllUtiOff,: :
The obJect to be strlpped is lmmersed into the composltion untll it has been observed to be stripped. Ir the obJect is a motor stator or rotor, it ls first prepared ,. .
~ by sawlng off the ends of the colls. If the rotating ~.,, ~ . . .....
i apparatus is form wound lt may not be necessary to cut the ~ ~
. ,, . . - .
i ends, but mush wound apparatus must be cut at at least one '~ end. -.. , . ~ . .
In Flgure 1 coils 1 of stator 2 have been cut at 3. The other end Qf the colls 4 has not been cut to provlde ;-.. . ..
~`something to grasp whlle pulling the colls from lamlnated 30 core 5. The stator ls lmmersed ln stripplng composltlon 6 ;
-6- ~ ~
~:
t ~0t~81~9 held in tank 7. About 1 to about 6 hours ls usually re-~uired to strip a motor coil.
The stripped ob~ect is removed, drained, cooled, and washed with a solvent such as toluene, trichloroethy-lene, or perchloroethylene. For coils vapor degreasing is usually not adequate to remove all of the stripping com- -posltion from between the laminations, and leaching in a solvent ls used as a supplemental cleaning step. Figure 2 shows the steps involved in removing coils f~om a motor, stator or rotor using the process of this invention. In Figure 2 steps 3 and ~ can be reversed.
While the composition was especially designed for strippi~g motors, it can also be used to strip generators, transformers, and other electrical conductors insulated wlth thermoset resins. The stripper can also be used on lamin-ates to determine khe amount of filler they contain, to clean ob~ects contaminated w1th resins, or for other pur-poses.
Losses of the composition can occur due to en-trainment on the ob~ect stripped, evaporation, oxidation,and reaction of the components with the resins. Therefore, ~ from time to time the composition is renewed by replacing '! those components which have been lost or used up.
', ' ' ' ;
.. ' '` ' ' .
.
,. ' ' :
, . . .
,''' ~ .
~(~;81~
EXAMPLE L
.
. StrIpper composfti'ons were prepared~and tested.-The following table gives the compositions and the results of testing ,them on various thermoset lamlnates after 6 hours at 250C. ~, ~ . . ~ . . , .
: , .. - Lamlnate . ..... .
.
High temperature Epoxy cured . , .
polyester with Polyester Phenolic Stripper Dlcyandiamlde : llnseed oil fatty Surface attack Lamlnate des- Laminate ,No attack , acid (LOFA) but no delami- troyed destroyed .
,. .; . natlon 100 pbb LOFA . No AttackLamlnate des-. Sllght . Sllght 50 pbw ~-napthol troyed attack attack 100 pbw LOFA Surface attack Laminate des- Laminate Laminate 50 pbw~g-napthol but no delami- , troy0d destroyed destroyed : 50 pbw triethy- nation . . . .
: _ lene glycol lOO pbw tall oll LaminateLamlnate des- Laminate Lamlnate . 50 pbw ~-napthol destroyed , - troyed destroyed destroyed 50 pbw triethy- . . :. ....... .
. ~ene glycol ..
.
. lOO pbw linseed, No attack . : Lamlnate,des- Lamlnate Lamlnate oll . troyed destroyed destroyed.
,. -.5C.pbw~ -napthol 50 pbw triethy- . . ........... . . . .
_lene glycol . . . ~ , 100 pbw tall Laminate Lamlnate des- Lamlnate Laminate ' .-,! pitch~ destroyed troyed destroyed destroyed : :
50 pbw resor- . . , . ~ , --clnol - . . .
50 pbw triethy- , , - - , . .
~ lene glycol 100 pbw benzoic Lamlnate Lamlnate des- Lamlnate Lamlnate ,: , acld destroyed troyed destroyed destroyed :
50 pbw ~-napthol .
50 pbw triethy-~" lene glycol _ . . . ,,~ ..
Sold by Unlon Camp under the trademark "Unltol DP" the composltlon of which is glven as 45~ fatty aclds and esterlfled aclds, ~0% rosln aclds, and 35~ unsaponiflables . ,.
. . '', ~
: ~ .
.
::
The above table shows that whlle all of the strip~
pers were able to destroy some o~ the laminates, only the ; fourth, sixth, and seven~h composltions were able to destroy all of the laminates.
Based on the results of Example 1, a composltion was prepared of 100 pbw tall oil, 50 pbw ~-naphthol, and 50 pbw triethylene glycol. A number of different insulating materials were placed in this stripper at different tempera-; 10 tures and for different lengths of time. The ~ollowing table gives the results:
Material Result lO mil resin treated destroyed in 10 min. at glass cloth 175C
15 mll mica board resin dlssolved wlthin 6 hours at 250C
! ' black varnish-treated resln dissolved within 1 i asbestos hour at 250C
varnished flexible mica resin dissolved within 2 hours at 250C
sllicone-varnished resin dissolved within 1 sleeving hour at 250C
polyester glass resin dissolved within 4 bonding hours at 250C
melamine laminate destroyed within 6 hours : at 250C
. polyethylene tere- dissolved within 4 hours phthalate mat at 250C
; 30 The end turns of four stators having frame sizes 140 and one having frame size 215 were sawed off, and the : stators were immersed in a composition at 250C of 25%
~-naphthol, 25% triethylene glycol, and 50% tall pitch.
Both stators used No. 61212 KA wire (polyester enamel with a , _g_ .-~ .
~ . ~
nylon overcoat), a Nomex~wedge and slot cell (an aromatic tl~
polyamlde-imide paper sold by DuPont), and a Dacron/Mylar/
- r~
Dacron phase (polyethylene terephthalate/polyimlde/polyethy-lene terephthalate). The insulation systems o~ these stators was more complicated and resistant to solvent penetration than most commerclal stators of thls slze. The followln~
table gives the results.
- Frame Required Sample Slze Other Insulation Treatment Tlme (hrs) , 1 140 One dlp and bake ln Westinghouse 1.5 ~ 32102 AJ varnish (a phenolic-alkyd); end tu~ns brush coated with Epoxylite' No. 213 (an epoxy) . .
2 140 Two dlps and bake in Westlng- 1.5 ~, house 32102 AJ varnish
3 140 One dlp and bake ln Westlnghouse ,~ 32102 AJ varnlsh; ends and base ' sprayed wlth DuPont #825-8031 Zn-" 20 chromate primer plus Cu-8; 1.5 ends brushed with 32101 FA air dry varnlsh (an oil-modified phenollc resln) , . . . .
4 140 Trickle treated, Epoxyllte 3 ~ -~ No. 234 (~ 150g epoxy resin) .'; ' ", 215 Three times vacuum-pressure 3 lmpregnated ln GE 74011 solventless epoxy; end over-coated wlth Westlnghouse 32102 AJ varnish; one coil per slot `; glass tape served -;': ' , , .
The stators were removed from the stripping com-position and the wires of the coils were easily removed mechanically. The laminated cores were cleaned ln chloro-,. rorm.
' .
:... ~ .:, .~. .
.. , - ~ , . .. , ..... , .- , -, . .
The stators were removed from the stripping com-position and the wires of the coils were easily removed mechanically. The laminated cores were cleaned ln chloro-,. rorm.
' .
:... ~ .:, .~. .
.. , - ~ , . .. , ..... , .- , -, . .
Claims (25)
1. A composition consisting essentially of:
(A) about 1 to about 99% of an aromatic compound which has a boiling point over 180°C selected from the group consisting of aromatic phenols, aromatic primary amines, aromatic secondary amines, and mixtures thereof;
(B) about 1 to about 99% of a carboxylic acid compound selected from the group consisting of carboxylic acids, esters of carboxylic acids, and mixtures thereof, which has a boiling point over 180°C, said composition being a liquid at 150°C; and (C) sufficient hydrogen bonding compound to react with any fatty acid present in said composition plus about 20 to about 50 phr (parts by weight per 100 parts of said aromatic compound plus said carboxylic acid compound) in excess of that amount, said hydrogen bonding compound having a boiling point over 180°C and having at least one pair of unshared electrons capable of forming a hydrogen bond with said aromatic compound.
(A) about 1 to about 99% of an aromatic compound which has a boiling point over 180°C selected from the group consisting of aromatic phenols, aromatic primary amines, aromatic secondary amines, and mixtures thereof;
(B) about 1 to about 99% of a carboxylic acid compound selected from the group consisting of carboxylic acids, esters of carboxylic acids, and mixtures thereof, which has a boiling point over 180°C, said composition being a liquid at 150°C; and (C) sufficient hydrogen bonding compound to react with any fatty acid present in said composition plus about 20 to about 50 phr (parts by weight per 100 parts of said aromatic compound plus said carboxylic acid compound) in excess of that amount, said hydrogen bonding compound having a boiling point over 180°C and having at least one pair of unshared electrons capable of forming a hydrogen bond with said aromatic compound.
2. A composition according to Claim 1 wherein said carboxylic acid compound is selected from the group consisting of rosin acids, fatty acids, esters thereof, and mixtures thereof.
3. A composition according to Claim 1 wherein said aromatic compound, said carboxylic acid compound, and said composition each have a boiling point over 250°C.
4. A composition according to Claim 1 wherein said carboxylic acid compound is tall pitch.
5. A composition according to Claim 1 wherein said aromatic compound is a phenol.
6. A composition according to Claim 5 wherein said phenol is selected from the group consisting of resorcinol, .beta.-naphthol, and mixtures thereof.
7. A composition according to Claim 1 wherein the concentration of said aromatic compound is about 10 to about 50% and the concentration of said carboxylic acid compound is about 50 to about 90%.
8. A composition according to Claim 1 wherein said hydrogen bonding compound has a boiling point over 250°C and has non-vicinal hydroxyl groups.
9. A composition according to Claim 8 wherein said hydrogen bonding compound is triethylene glycol.
10. A composition according to Claim 1 which includes up to about 50 phr of a swelling agent which has a boiling point over 180°C.
11. A composition according to Claim 10 wherein the concentration of said swelling agent is about 5 to about 30 phr.
12. A method of removing thermoset resins from an article comprising immersing the object in a composition heated between about 150 and about 250°C which consists essentially of:
(A) about 1 to about 99% of an aromatic compound which has a boiling point over 180° selected from the group consisting of aromatic phenols, aromatic primary amines, aromatic secondary amines, and mixtures thereof;
(B) about 1 to about 99% of a carboxylic acid compound selected from the group consisting of carboxylic acids, esters of carboxylic acids, and mixtures thereof, which has a boiling point over 180°C, said composition being a liquid at 150°C; and (C) sufficient hydrogen bonding compound to react with any fatty acid present in said composition plus about 20 to about 50 phr (parts by weight per 100 parts of said aromatic compound plus said carboxylic acid compound) in excess of that amount, said hydrogen bonding compound having a boiling point over 180°C and having at least one pair of unshared electrons capable of forming a hydrogen bond with said aromatic compound.
(A) about 1 to about 99% of an aromatic compound which has a boiling point over 180° selected from the group consisting of aromatic phenols, aromatic primary amines, aromatic secondary amines, and mixtures thereof;
(B) about 1 to about 99% of a carboxylic acid compound selected from the group consisting of carboxylic acids, esters of carboxylic acids, and mixtures thereof, which has a boiling point over 180°C, said composition being a liquid at 150°C; and (C) sufficient hydrogen bonding compound to react with any fatty acid present in said composition plus about 20 to about 50 phr (parts by weight per 100 parts of said aromatic compound plus said carboxylic acid compound) in excess of that amount, said hydrogen bonding compound having a boiling point over 180°C and having at least one pair of unshared electrons capable of forming a hydrogen bond with said aromatic compound.
13. A method according to Claim 12 wherein said article is an electric motor.
14. A method of removing the coils from an electri-cal apparatus having coils of insulated wire embedded in a laminated core comprising:
(1) first, severing at least one end of said coils;
(2) second, immersing said apparatus in a composi-tion heated between about 150 and about 250°C which consists essentially of:
(A) about 1 to about 99% of an aromatic compound which has a boiling point over 180°C selected from the group consisting of aromatic phenols, aromatic primary amines, aromatic secondary amines, and mixtures thereof;
(B) about 1 to about 99% of a carboxylic acid compound selected from the group consisting of carboxylic acids, esters of carboxylic acids, and mixtures thereof, which has a boiling point over 180°C, said composition being a liquid at 150°C; and (C) sufficient hydrogen bonding compound to react with any fatty acid present in said composition plus about 20 to about 50 phr (parts by weight per 100 parts of said aromatic compound plus said carboxylic acid compound) in excess of that amount, said hydrogen bonding compound having a boiling point over 180°C and having at least one pair of unshared electrons capable of forming a hydrogen bond with said aromatic compound;
(3) removing said laminated core from said com-position after the insulation of said coils has been destroyed and removing the wire of said coils from said laminated core in either order; and (4) cleaning said laminated core.
(1) first, severing at least one end of said coils;
(2) second, immersing said apparatus in a composi-tion heated between about 150 and about 250°C which consists essentially of:
(A) about 1 to about 99% of an aromatic compound which has a boiling point over 180°C selected from the group consisting of aromatic phenols, aromatic primary amines, aromatic secondary amines, and mixtures thereof;
(B) about 1 to about 99% of a carboxylic acid compound selected from the group consisting of carboxylic acids, esters of carboxylic acids, and mixtures thereof, which has a boiling point over 180°C, said composition being a liquid at 150°C; and (C) sufficient hydrogen bonding compound to react with any fatty acid present in said composition plus about 20 to about 50 phr (parts by weight per 100 parts of said aromatic compound plus said carboxylic acid compound) in excess of that amount, said hydrogen bonding compound having a boiling point over 180°C and having at least one pair of unshared electrons capable of forming a hydrogen bond with said aromatic compound;
(3) removing said laminated core from said com-position after the insulation of said coils has been destroyed and removing the wire of said coils from said laminated core in either order; and (4) cleaning said laminated core.
15. A method according to Claim 14 wherein said cleaning step comprises vapor degreasing followed by solvent leaching.
16. A method according to Claim 14 wherein said carboxylic acid compound is selected from the group consist-ing of rosin acids, fatty acids, esters thereof, and mixtures thereof.
17. A method according to Claim 14 wherein said aromatic compound, said carboxylic acid compound, and said composition each have a boiling point over 250°C.
18. A method according to Claim 14 wherein said carboxylic acid compound is tall pitch.
19. A method according to Claim 14 wherein said aromatic compound is a phenol.
20. A method according to Claim 19 wherein said phenol is selected from the group consisting of resorcinol, .beta.-naphthol, and mixtures thereof.
21. A method according to Claim 14 wherein the concentration of said aromatic compound is about 10 to about 50% and the concentration of said carboxylic acid compound is about 50 to about 90%.
22. A method according to Claim 14 wherein said hydrogen bonding compound has a boiling point over 250°C
and has nonvicinal hydroxyl groups.
and has nonvicinal hydroxyl groups.
23. A method according to Claim 22 wherein said hydrogen bonding compound is triethylene glycol.
24. A method according to Claim 14 which includes up to about 50 phr of a swelling agent which has a boiling point over 180°C.
25. A method according to Claim 24 wherein the concentration of said swelling agent is about 5 to about 30 phr.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US58573375A | 1975-06-10 | 1975-06-10 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1068199A true CA1068199A (en) | 1979-12-18 |
Family
ID=24342729
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA252,228A Expired CA1068199A (en) | 1975-06-10 | 1976-05-11 | Stripping composition for thermoset resins |
Country Status (2)
| Country | Link |
|---|---|
| JP (1) | JPS52787A (en) |
| CA (1) | CA1068199A (en) |
-
1976
- 1976-05-11 CA CA252,228A patent/CA1068199A/en not_active Expired
- 1976-06-10 JP JP51067190A patent/JPS52787A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| JPS52787A (en) | 1977-01-06 |
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