CA1255700A - Thermally stable polyoxyalkylene heat transfer fluids - Google Patents
Thermally stable polyoxyalkylene heat transfer fluidsInfo
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- CA1255700A CA1255700A CA000506715A CA506715A CA1255700A CA 1255700 A CA1255700 A CA 1255700A CA 000506715 A CA000506715 A CA 000506715A CA 506715 A CA506715 A CA 506715A CA 1255700 A CA1255700 A CA 1255700A
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G65/00—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule
- C08G65/02—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule from cyclic ethers by opening of the heterocyclic ring
- C08G65/26—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule from cyclic ethers by opening of the heterocyclic ring from cyclic ethers and other compounds
- C08G65/2639—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule from cyclic ethers by opening of the heterocyclic ring from cyclic ethers and other compounds the other compounds containing elements other than oxygen, nitrogen or sulfur
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L71/00—Compositions of polyethers obtained by reactions forming an ether link in the main chain; Compositions of derivatives of such polymers
- C08L71/02—Polyalkylene oxides
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Abstract
THERMALLY STABLE POLYOXYALKYLENE HEAT TRANSFER FLUIDS
Abstract of the Disclosure Thermally stable polyoxyethylene polyethers prepared by oxyethylating aromatic initiators having at least two reactive hydrogens derived from amino or hydroxyl functional groups located para to each other are dis-closed. These polyethers are especially suitable as solder bath oils, solder reflow oils, and heat transfer fluids for high temperature applications.
Abstract of the Disclosure Thermally stable polyoxyethylene polyethers prepared by oxyethylating aromatic initiators having at least two reactive hydrogens derived from amino or hydroxyl functional groups located para to each other are dis-closed. These polyethers are especially suitable as solder bath oils, solder reflow oils, and heat transfer fluids for high temperature applications.
Description
THERMALLY STABLE POLYOXYALKYL~NE HEAT TRANSFER FLUIDS
Background of the Invention 1. Field of the Invention The subject invention relates to polyoxyethylene polyethers which are thermally stable at high tempera-tures. These polyethers find special utility as heat transfer fluids and soldering auxiliaries.
Background of the Invention 1. Field of the Invention The subject invention relates to polyoxyethylene polyethers which are thermally stable at high tempera-tures. These polyethers find special utility as heat transfer fluids and soldering auxiliaries.
2. Description of the Related Art In the past few decades the printed circuit board has evolved from a rare and expensive commodity to a virtually ubiquitous and inexpensive method of constructing electronic circuits. The development of tlle transistor, the accompanying miniaturization of other electronic components, and the increasing complexity of the circuits themselves has resulted in electronic circuits of high component density.
Due to the high component density and the need for rapid, mass-production techniques, the technique of hand soldering components has largely been superseded by more modern and efficient soldering methods.
In the solder pot method, for example, the circuit board, with components mounted thereon, is partially immersed into a pot of molten solder, bonding the component leads to the foil conductors on the surface of the board.
One o~ the disadvantages of the solder pot technique is the trapping of gas bubbles or debris under the surface oE the ~' o~
board preventing the adherence of ~older at these loca-tion~. A further disadvantage is the formation of an oxide coating, or dross, on the surface of the solder bath as a result of oxidation of the hot molten solder by atmospheric oxygen. ~he dross interferes with uniform ~oldering resulting in a high rejection rate of the finished boards.
In U.S. 2,740,193, an improvement to the pot soldering technique is disclosed wherein the previously soldered board is immersed into a second solder bath which is covered with a liquid layer of organophosphorus com-pound. This liquid, acting as a heat tran~fer fluid causes the solder to remelt. Agitation of the board in the heat transfer fluid and in the underlying solder bath enables the elimination of solder bridges between foil conductors.
However, this procedure is less than satisfactory due to the high cost of the organophosphoru~ compound.
U.S. Patent 3,054,174 describes the use of a high boiling fluid to bond leads to semi conductor devices by immersing the devices with pre-positioned leads into the fluid. Suggested fluids are anhydrou~ lanolin, silicones, glycerine, ethylene glycol and polyethylene glycol. U.S.
Patent 3,214,827 discloses a process for soldering stacked printed circuit boards by immersion of the assembled, solder-coated components into a hot bath of fluid where solder reflow takes place. Corn oil is suggested as a suitable fluid.
~S;7~
U.S. Patent 3,690,943 discloses the use of a stationary wave of heat transfer fluid to alloy two or more metals on a printed circuit board. The hot fluid, which may be selected from paraffins, fats, and mineral and vegetable oils, i~ pumped smoothly through a long but narrow orifice thereby forming a uniform wave of fluid. The previously met~llized circuit board is passed through the wave at a speed appropriate to raise the temperature to a sufficient level so as to alloy the metals coated thereon.
The wave soldering technique has become quite important commercially. In wave soldering, a stationary wave of solder is formed in much the same manner as the wave of heat transfer fluid described in U.S. Patent 3,690,943.
The circuit board and mounted components are passed at a predetermined speed through the stationary wave of solder.
The dross formed on the solder may be skimmed off as the solder is recirculated but nevertheless causes higher than desirable reject rates. To minimize dross and to decrease the number of unsoldered areas and solder bridges, thermally ~table oils may be added to the wave soldering apparatus either in bulk or in c~ntinuously metered amounts. In addition to minimizing dross formation, these oils also have the advantage that they lower the surface ten~ion of ~he solder, promoting more even solder coating.
7~
All of the processes described above utilize a high temperature liquid, generally termed an "oil" irrespec-tive of its actual composition. Regardless of the partic-ular application, the oil must fulfill several, often conflicting requirements. First and foremost, it must have superior thermal properties. Among the thermal properties most desirable are high boiling point (and correspondingly low volatility), high smoke point, and in particular, high thermal stability with regard to common high temperature chemical reactions such as pyrolysis and oxidation.
Further, it should not deposit appreciable amounts of resinous residue upon the circuit boards, or produce large amounts of such residue, or sludge, upon long-term use.
In addition to the thermal properties just mentioned, the oil should be non-reactive with the solder, the circuit board composition, and the electronic compo-nents. Finally, it is most desirable that the oil be easily and virtually completely removable by washing with inexpen-sive solvents, most preferably, water.
Polyoxyalkylene polyethers have been proposed for these uses. For example, pclyoxyethylene glycols were proposed for use in U.S. Patent 3,054,174, discu~sed previously. However, despite being relatively inexpensive and water rinseable, these polyethers ~uffer from low thermal stability and therefore have not been used to any 7~
appreciable extent. Alkylphenol oxyethylates have been utilized by the industry, but still do not have thermal stability of the degree desired. An oil of improved thermal stability was disclosed in U.S. Patent 4,360,144. These improved oils are heteric polyoxyalkylene polyethers initiated with bisphenol A, containing a 1:3 ratio of oxy-ethylene and oxypropylene residues in the polyoxyalkylene chains. Although these materials constituted a considerable advance over oils previously available in terms of thermal stability, further improvement is desirable. Furthermore, the bisphenol A initiated polyethers had less than the optimal degree of rinseability.
Summary of the Invention It is therefore an object of the subject invention to provide a polyoxyalkylene polyether with superior thermal properties including high boiling point, high flashpoint and excellent thermal stability, combined with superior rinse-ability. Such a product is suitable for a variety of uses including, but not limited to, heat transfer fluids, solder reflow fluids, and wave soldering oils.
These and other objects were met by the prepara-tion and use of polyoxyethylene polyethers initiated with an aromatic initiator molecule having two or more reactive hydrogens, wherein the active hydrogens are bonded to oxygen or nitrogen atoms located para to each other on the aromatic nucleus of the initiator molecule. These polyoxyalkylene polyethers possesi excellent thermal properties and at the same time show excellent rinseability.
Descripti n of the Preferred Embodiments The thermally stable ccgeneric polyoxyethylene polyethers of the ~ubject invention have the formula R R
X~X
R R
wherein each R radical is individually selected from the group consisting of hydrogen, fluoro, chloro, and lower alkyl having 1 to 4 carbon ato~s, and wherein each X is individually ~elected from the group consisting of a) 2 2 n / (CH2CH20-)~H
b) -N \
( 2 2 )m wherein n and m are integers greater than 2 such that the molecular weight of said polyether is from about 500 Daltons to about 10,000 Daltons.
These polyoxyalkylene polyether~ are prepared by the r;ng-opening conden~ation polymerization of ethylene oxide onto a suitable initiator molecule~ ~his process, generally refe~red to a~ oxyethylation, i~ generally accomplished through the use of cataly~ts. Lewi~ acid catalysts such as boron trifluoride etherate and aluminum chloride may be utilized as catalyst~. Preferably, however, ba~ic catalysts such as sodium or potassium hydroxides, or ~odium or potasqium lower alkoxide~ are utilized, in amounts of from about .01 to 10 percent by weight based on the initiator weight.
The oxyethylation i9 generally conducted at pre~sure~ greater than atmospheric and at temperature~ of from 70C to 150C, generally at about 105 to 135C. The ethylene oxide may be added all at once, but it i~ prefer-able, for safety reasons, to add it gradually, or intermit-tently as previously added oxide reacts. It is po~sible to conduct the oxyethylation in the presence of minor amount~
of higher alkylene oxides such a3 propylene oxide or butylene oxide to prepare a heteric copolymer polyether polyol. However, the thermal qtability decrease~ with increasing content of the higher alkylene oxide, and thus it i~ desirable to minimize the amount of ~uch higher alkylene oxide. Generally, more than 5 percent by weight signifi-cantly lowers the thermal ~tability. Preferably, the amount of higher alkylene oxide i~ 3 percent or less. Most preferably, no higher alkylene oxide is present.
The finished polyether, after discharging ~rom the reactor, may be treated or neutralized to remove the residual cataly~t. For example, the preferred basic catalysts may be removed by treatment with magnesium silicate, or they may be neutralized with inorganic acids such as phosphoric acid, or with organic acids such a~
acetic acid and salicylic acid.
Suitable initiators which may be used to prepare the polyoxyethylene polyethers of the subject invention are substituted and unsubstituted benzenoid hydrocarbons having hydroxyl and/or amino functional groups located para to each other on the aromatic ring. Suitable initiators, for example, are substituted or unsubstituted hydroquinones, p-phenylenediamines, and p-aminophenols. Particularly preferred are hydroquinone, p-phenylenediamine and p-amino-phenol.
The initiators are oxyethylated until the average molecular weight is between 500 and 10,000 Daltons and preferably between 500 and 5000 Daltons. The most preferred polyoxyethylene polyethers of the subject invention have molecular weights between 600 and 2000 Daltons. Polyethers o~ the subject invention in the lower molecular weight range possess greater thermal stability than their higher molec-ular weight analogues. However the volatility of the lower molecular weight products is greater as well. For the~e ~2~i~7~3 reasons, polyethers having molecular ~eights of about 1000 Daltons are especially preferred.
In their use as heat transfer fluids, the poly-ethers of the subject invention may be used alone, in the form of mixtures, or in conjunction with other oils and additives. For example, the addition of nonylphenol oxyethylates to the subject polyoxyethylene polyethers allows the formulation of a less expensive product at some sacrifice of thermal stability and volatility. In general, it is not desirable to add more than 10 percent to 20 percent by weight of these less thermally stable polyethers to the polyoxyethylene polyethers of the subject invention.
Oxidation inhibitors such as phenothiazine may also be added to the subject polyoxyethylene polyethers to further enhance thermal stability. In general, from 0.1 percent to 1 percent by weight of inhibitor is added when such additional stabilization is desired. Soldering additives, especially those which promote the even flow of solder and/or chemically clean the metallic surface may also be used. Long chain alkanoic acids are frequently added for this purpose, for example, stearic acid and oleic acid.
Oleic acid is preferred. The organic acid is added in relatively small quantities, generally les3 than 10 percent by weight, and preferably less than 7 percent by weight.
Improved stability may also be achieved generally by _ g _ neutralizing the alkaline oxyethyl~tion catalyst with organic acids such as ace~ic acid and allowing the resulting carboxylic acid salts to remain in the finished product.
When desirable, inorganic salts or rosin acids may also be added. The addition of these more active cleaning agents is especially desirable if the polyoxyethylene polyethers of the subject invention are to be utilized in solder fluxes, particularly in automatic, continuous ~luxing operations.
In the examples which follow, three polyoxy-ethylene polyethers of the subject invention, polyethers 1, 2, and 3, were synthesi~ed and their properties compared to other polyoxyalkylene polyethers used in high temperature operations.
Polyethers 1 and 2 are cogeneric polyoxyethylene polyethers having average molecular weights of about 1400 and 800, respectively. These polyethers were prepared by oxyethylating bis(2-hydroxyethyl)hydroquinone with 30 and 14 moles of ethylene oxide in the presence of potassium hydroxide catalyst. The requisite amount of ethylene oxide was added at less than 90 psig at a temperature of 140C.
The finished polyethers were discharged, treated with magnesium silicate, filtered, and stripped for one hour at 125C and 10 torr. Polyether 2P differs from polyether 2 in containing 0.5 percent by weight of phenothia~ine. Poly-ether 3 is an 800 average molecular weight cogenericpolyoxyethylene polyether prepared by oxyethylating p--phenylenediamine with 16 moles of ethylene oxide in the presence of potassium hydroxide catalyst. The method of preparation was similar to that u~ilized above.
Polyethers C-l and C-lP, for comparison purposes, are commercially available solder bath oils which are nonyl-phenol oxyethylates prepared by oxyethylating nonylphenol with 10 moles of ethylene oxide in the presence of potassium hydroxide catalyst. Polyether C-lP differs from C-l in being stabilized with 0.5 percent phenothiazine. Polyethers C-2 and C-2P, for comparison purposes, are commercially available polyethers which are butyl alcohol initiated heteric polyoxyethylene-polyoxypropylene copolymers having an average molecular weight of 4600 Daltons. Polyether C-2P
differs from polyether C-2 in being stabilized with 0.5 percent phenothiazine. Polyether C-3 is a 1500 molecular weight polyoxyethylene polyether initiated with bis-phenol A. Polyether C-4 is a 2000 molecular weight hydro-quinone initiated heteric copolymer polyether containing 20percent by weight of oxypropylene groups. Polyether C-5 is an 800 molecular weight polyoxyethylene polyether initiated with p-methylphenol.
TABLE I
Polyether Smoke Point, C
Due to the high component density and the need for rapid, mass-production techniques, the technique of hand soldering components has largely been superseded by more modern and efficient soldering methods.
In the solder pot method, for example, the circuit board, with components mounted thereon, is partially immersed into a pot of molten solder, bonding the component leads to the foil conductors on the surface of the board.
One o~ the disadvantages of the solder pot technique is the trapping of gas bubbles or debris under the surface oE the ~' o~
board preventing the adherence of ~older at these loca-tion~. A further disadvantage is the formation of an oxide coating, or dross, on the surface of the solder bath as a result of oxidation of the hot molten solder by atmospheric oxygen. ~he dross interferes with uniform ~oldering resulting in a high rejection rate of the finished boards.
In U.S. 2,740,193, an improvement to the pot soldering technique is disclosed wherein the previously soldered board is immersed into a second solder bath which is covered with a liquid layer of organophosphorus com-pound. This liquid, acting as a heat tran~fer fluid causes the solder to remelt. Agitation of the board in the heat transfer fluid and in the underlying solder bath enables the elimination of solder bridges between foil conductors.
However, this procedure is less than satisfactory due to the high cost of the organophosphoru~ compound.
U.S. Patent 3,054,174 describes the use of a high boiling fluid to bond leads to semi conductor devices by immersing the devices with pre-positioned leads into the fluid. Suggested fluids are anhydrou~ lanolin, silicones, glycerine, ethylene glycol and polyethylene glycol. U.S.
Patent 3,214,827 discloses a process for soldering stacked printed circuit boards by immersion of the assembled, solder-coated components into a hot bath of fluid where solder reflow takes place. Corn oil is suggested as a suitable fluid.
~S;7~
U.S. Patent 3,690,943 discloses the use of a stationary wave of heat transfer fluid to alloy two or more metals on a printed circuit board. The hot fluid, which may be selected from paraffins, fats, and mineral and vegetable oils, i~ pumped smoothly through a long but narrow orifice thereby forming a uniform wave of fluid. The previously met~llized circuit board is passed through the wave at a speed appropriate to raise the temperature to a sufficient level so as to alloy the metals coated thereon.
The wave soldering technique has become quite important commercially. In wave soldering, a stationary wave of solder is formed in much the same manner as the wave of heat transfer fluid described in U.S. Patent 3,690,943.
The circuit board and mounted components are passed at a predetermined speed through the stationary wave of solder.
The dross formed on the solder may be skimmed off as the solder is recirculated but nevertheless causes higher than desirable reject rates. To minimize dross and to decrease the number of unsoldered areas and solder bridges, thermally ~table oils may be added to the wave soldering apparatus either in bulk or in c~ntinuously metered amounts. In addition to minimizing dross formation, these oils also have the advantage that they lower the surface ten~ion of ~he solder, promoting more even solder coating.
7~
All of the processes described above utilize a high temperature liquid, generally termed an "oil" irrespec-tive of its actual composition. Regardless of the partic-ular application, the oil must fulfill several, often conflicting requirements. First and foremost, it must have superior thermal properties. Among the thermal properties most desirable are high boiling point (and correspondingly low volatility), high smoke point, and in particular, high thermal stability with regard to common high temperature chemical reactions such as pyrolysis and oxidation.
Further, it should not deposit appreciable amounts of resinous residue upon the circuit boards, or produce large amounts of such residue, or sludge, upon long-term use.
In addition to the thermal properties just mentioned, the oil should be non-reactive with the solder, the circuit board composition, and the electronic compo-nents. Finally, it is most desirable that the oil be easily and virtually completely removable by washing with inexpen-sive solvents, most preferably, water.
Polyoxyalkylene polyethers have been proposed for these uses. For example, pclyoxyethylene glycols were proposed for use in U.S. Patent 3,054,174, discu~sed previously. However, despite being relatively inexpensive and water rinseable, these polyethers ~uffer from low thermal stability and therefore have not been used to any 7~
appreciable extent. Alkylphenol oxyethylates have been utilized by the industry, but still do not have thermal stability of the degree desired. An oil of improved thermal stability was disclosed in U.S. Patent 4,360,144. These improved oils are heteric polyoxyalkylene polyethers initiated with bisphenol A, containing a 1:3 ratio of oxy-ethylene and oxypropylene residues in the polyoxyalkylene chains. Although these materials constituted a considerable advance over oils previously available in terms of thermal stability, further improvement is desirable. Furthermore, the bisphenol A initiated polyethers had less than the optimal degree of rinseability.
Summary of the Invention It is therefore an object of the subject invention to provide a polyoxyalkylene polyether with superior thermal properties including high boiling point, high flashpoint and excellent thermal stability, combined with superior rinse-ability. Such a product is suitable for a variety of uses including, but not limited to, heat transfer fluids, solder reflow fluids, and wave soldering oils.
These and other objects were met by the prepara-tion and use of polyoxyethylene polyethers initiated with an aromatic initiator molecule having two or more reactive hydrogens, wherein the active hydrogens are bonded to oxygen or nitrogen atoms located para to each other on the aromatic nucleus of the initiator molecule. These polyoxyalkylene polyethers possesi excellent thermal properties and at the same time show excellent rinseability.
Descripti n of the Preferred Embodiments The thermally stable ccgeneric polyoxyethylene polyethers of the ~ubject invention have the formula R R
X~X
R R
wherein each R radical is individually selected from the group consisting of hydrogen, fluoro, chloro, and lower alkyl having 1 to 4 carbon ato~s, and wherein each X is individually ~elected from the group consisting of a) 2 2 n / (CH2CH20-)~H
b) -N \
( 2 2 )m wherein n and m are integers greater than 2 such that the molecular weight of said polyether is from about 500 Daltons to about 10,000 Daltons.
These polyoxyalkylene polyether~ are prepared by the r;ng-opening conden~ation polymerization of ethylene oxide onto a suitable initiator molecule~ ~his process, generally refe~red to a~ oxyethylation, i~ generally accomplished through the use of cataly~ts. Lewi~ acid catalysts such as boron trifluoride etherate and aluminum chloride may be utilized as catalyst~. Preferably, however, ba~ic catalysts such as sodium or potassium hydroxides, or ~odium or potasqium lower alkoxide~ are utilized, in amounts of from about .01 to 10 percent by weight based on the initiator weight.
The oxyethylation i9 generally conducted at pre~sure~ greater than atmospheric and at temperature~ of from 70C to 150C, generally at about 105 to 135C. The ethylene oxide may be added all at once, but it i~ prefer-able, for safety reasons, to add it gradually, or intermit-tently as previously added oxide reacts. It is po~sible to conduct the oxyethylation in the presence of minor amount~
of higher alkylene oxides such a3 propylene oxide or butylene oxide to prepare a heteric copolymer polyether polyol. However, the thermal qtability decrease~ with increasing content of the higher alkylene oxide, and thus it i~ desirable to minimize the amount of ~uch higher alkylene oxide. Generally, more than 5 percent by weight signifi-cantly lowers the thermal ~tability. Preferably, the amount of higher alkylene oxide i~ 3 percent or less. Most preferably, no higher alkylene oxide is present.
The finished polyether, after discharging ~rom the reactor, may be treated or neutralized to remove the residual cataly~t. For example, the preferred basic catalysts may be removed by treatment with magnesium silicate, or they may be neutralized with inorganic acids such as phosphoric acid, or with organic acids such a~
acetic acid and salicylic acid.
Suitable initiators which may be used to prepare the polyoxyethylene polyethers of the subject invention are substituted and unsubstituted benzenoid hydrocarbons having hydroxyl and/or amino functional groups located para to each other on the aromatic ring. Suitable initiators, for example, are substituted or unsubstituted hydroquinones, p-phenylenediamines, and p-aminophenols. Particularly preferred are hydroquinone, p-phenylenediamine and p-amino-phenol.
The initiators are oxyethylated until the average molecular weight is between 500 and 10,000 Daltons and preferably between 500 and 5000 Daltons. The most preferred polyoxyethylene polyethers of the subject invention have molecular weights between 600 and 2000 Daltons. Polyethers o~ the subject invention in the lower molecular weight range possess greater thermal stability than their higher molec-ular weight analogues. However the volatility of the lower molecular weight products is greater as well. For the~e ~2~i~7~3 reasons, polyethers having molecular ~eights of about 1000 Daltons are especially preferred.
In their use as heat transfer fluids, the poly-ethers of the subject invention may be used alone, in the form of mixtures, or in conjunction with other oils and additives. For example, the addition of nonylphenol oxyethylates to the subject polyoxyethylene polyethers allows the formulation of a less expensive product at some sacrifice of thermal stability and volatility. In general, it is not desirable to add more than 10 percent to 20 percent by weight of these less thermally stable polyethers to the polyoxyethylene polyethers of the subject invention.
Oxidation inhibitors such as phenothiazine may also be added to the subject polyoxyethylene polyethers to further enhance thermal stability. In general, from 0.1 percent to 1 percent by weight of inhibitor is added when such additional stabilization is desired. Soldering additives, especially those which promote the even flow of solder and/or chemically clean the metallic surface may also be used. Long chain alkanoic acids are frequently added for this purpose, for example, stearic acid and oleic acid.
Oleic acid is preferred. The organic acid is added in relatively small quantities, generally les3 than 10 percent by weight, and preferably less than 7 percent by weight.
Improved stability may also be achieved generally by _ g _ neutralizing the alkaline oxyethyl~tion catalyst with organic acids such as ace~ic acid and allowing the resulting carboxylic acid salts to remain in the finished product.
When desirable, inorganic salts or rosin acids may also be added. The addition of these more active cleaning agents is especially desirable if the polyoxyethylene polyethers of the subject invention are to be utilized in solder fluxes, particularly in automatic, continuous ~luxing operations.
In the examples which follow, three polyoxy-ethylene polyethers of the subject invention, polyethers 1, 2, and 3, were synthesi~ed and their properties compared to other polyoxyalkylene polyethers used in high temperature operations.
Polyethers 1 and 2 are cogeneric polyoxyethylene polyethers having average molecular weights of about 1400 and 800, respectively. These polyethers were prepared by oxyethylating bis(2-hydroxyethyl)hydroquinone with 30 and 14 moles of ethylene oxide in the presence of potassium hydroxide catalyst. The requisite amount of ethylene oxide was added at less than 90 psig at a temperature of 140C.
The finished polyethers were discharged, treated with magnesium silicate, filtered, and stripped for one hour at 125C and 10 torr. Polyether 2P differs from polyether 2 in containing 0.5 percent by weight of phenothia~ine. Poly-ether 3 is an 800 average molecular weight cogenericpolyoxyethylene polyether prepared by oxyethylating p--phenylenediamine with 16 moles of ethylene oxide in the presence of potassium hydroxide catalyst. The method of preparation was similar to that u~ilized above.
Polyethers C-l and C-lP, for comparison purposes, are commercially available solder bath oils which are nonyl-phenol oxyethylates prepared by oxyethylating nonylphenol with 10 moles of ethylene oxide in the presence of potassium hydroxide catalyst. Polyether C-lP differs from C-l in being stabilized with 0.5 percent phenothiazine. Polyethers C-2 and C-2P, for comparison purposes, are commercially available polyethers which are butyl alcohol initiated heteric polyoxyethylene-polyoxypropylene copolymers having an average molecular weight of 4600 Daltons. Polyether C-2P
differs from polyether C-2 in being stabilized with 0.5 percent phenothiazine. Polyether C-3 is a 1500 molecular weight polyoxyethylene polyether initiated with bis-phenol A. Polyether C-4 is a 2000 molecular weight hydro-quinone initiated heteric copolymer polyether containing 20percent by weight of oxypropylene groups. Polyether C-5 is an 800 molecular weight polyoxyethylene polyether initiated with p-methylphenol.
TABLE I
Polyether Smoke Point, C
3 226 C-l 207 Table I shows that the polyethers of the subject invention have smoke points which are considerably higher than comparable, commercially availsble polyethers.
The thermal stability of various polyoxyalkylene polyethers is presented in Table II. For short-term thermal stability testing, 3 grams of each polyether was added to a petri dish and maintained in a circulating air oven at 232C
for three hours. For 24-hour tests, ~he same quantities of polyethers were added to metal pans and maintained in the circulating air oven at 240C for 24 hours. In each case the pan or dish was reweighed and the amount of polyether remaining expressed as a percentage of the initial amount.
The thermal stability is proportional to the amount of polyether remaining.
~ ~5~
An additional thermal stability test was devised to more closely simulate behavior in bulk, as would occur in a solder bath or heat transfer fluid application. In this test, the so-called beaker test, a 40 gram sample was introduced into a beaker and maintained in a circulating air oven at 232C for 86 hours. The polyether remaining i~
expressed as a percentage of that originally introduced.
TABLE II
% Residue for % Residue ~ Residue Bulk Sample after 3 hrs.after 24 hrs. after 86 hrs.
Polyether@ 232C @ 240C @ 232C
C-l 93 2.5 53 C-lP - 5.0 61 C-2 99 2.0 27 C-2P - 2.0 22 C-4 _ 13.0 Table II shows convincingly that the polyoxy-thylene polyethers of the subject invention have ~ignifi-cantly improved thermal stability over prior art commercial products such as comparative polyether C--l and the all ;7~
polyoxyethylene analog of the polyether of U.S. Patent
The thermal stability of various polyoxyalkylene polyethers is presented in Table II. For short-term thermal stability testing, 3 grams of each polyether was added to a petri dish and maintained in a circulating air oven at 232C
for three hours. For 24-hour tests, ~he same quantities of polyethers were added to metal pans and maintained in the circulating air oven at 240C for 24 hours. In each case the pan or dish was reweighed and the amount of polyether remaining expressed as a percentage of the initial amount.
The thermal stability is proportional to the amount of polyether remaining.
~ ~5~
An additional thermal stability test was devised to more closely simulate behavior in bulk, as would occur in a solder bath or heat transfer fluid application. In this test, the so-called beaker test, a 40 gram sample was introduced into a beaker and maintained in a circulating air oven at 232C for 86 hours. The polyether remaining i~
expressed as a percentage of that originally introduced.
TABLE II
% Residue for % Residue ~ Residue Bulk Sample after 3 hrs.after 24 hrs. after 86 hrs.
Polyether@ 232C @ 240C @ 232C
C-l 93 2.5 53 C-lP - 5.0 61 C-2 99 2.0 27 C-2P - 2.0 22 C-4 _ 13.0 Table II shows convincingly that the polyoxy-thylene polyethers of the subject invention have ~ignifi-cantly improved thermal stability over prior art commercial products such as comparative polyether C--l and the all ;7~
polyoxyethylene analog of the polyether of U.S. Patent
4,360,144.
Rinseability of various polyoxyalkylene polyethers is presented in Table III. To determine rinseability, a microscope slide was dipped into the liquid polyether, then dipped into water. The rinseability was measured by counting the number of seconds taken until clear upon visual inspection.
TABLE III
Rinseability, Polyether seconds C-l 13 *best rinseability of all candida~es tested.
Table III shows that products of the subject invention have superior rinseability as compared to prior art and com-mercial products.
Rinseability of various polyoxyalkylene polyethers is presented in Table III. To determine rinseability, a microscope slide was dipped into the liquid polyether, then dipped into water. The rinseability was measured by counting the number of seconds taken until clear upon visual inspection.
TABLE III
Rinseability, Polyether seconds C-l 13 *best rinseability of all candida~es tested.
Table III shows that products of the subject invention have superior rinseability as compared to prior art and com-mercial products.
Claims (24)
1. A thermally stable cogeneric polyoxyethylene polyether having the formula wherein each R radical is individually selected from the group consisting of hydrogen, fluoro, chloro, and lower alkyl having 1 to 4 carbon atoms, and wherein each X is individually selected from the group consisting of a) b) wherein n and m are integers greater than 2 such that the molecular weight of said polyether is from about 500 Daltons to about 10,000 Daltons.
2. The polyether of claim 1 wherein each R is hydrogen.
3. The polyether of claim 1 wherein the molecular weight is from about 500 Daltons to 5000 Daltons.
4. The polyether of claim 2 wherein the molecular weight is from about 500 Daltons to 5000 Daltons.
5. The polyether of claim 1 wherein the molecular weight is from 600 to 2000 Daltons.
6. The polyether of claim 2 wherein the molecular weight is from 600 to 2000 Daltons.
7. In a process far transferring heat by means of a fluid, the improvement comprising employing as a heat transfer fluid a polyoxyethylene polyether having the formula wherein each R radical is individually selected from the group consisting of hydrogen, fluoro, chloro, and lower alkyl having 1 to 4 carbon atoms, and wherein each X is individually selected from the group consisting of a) b) wherein n and m are integers greater than 2 such that the molecular weight of said polyether is from about 500 Daltons to about 10,000 Daltons.
8. The process of claim 7 wherein each R is hydrogen.
9. The process of claim 7 wherein said molecular weight is from 500 Daltons to 5000 Daltons.
10. The process of claim 8 wherein said molecular weight is from 500 Daltons to 5000 Daltons.
11. The process of claim 7 wherein said molecular weiyht is from 600 Daltons to 2000 Daltons.
12. The process of claim 8 wherein said molecular weight is from 600 Daltons to 2000 Daltons.
13. In a process for wave soldering printed circuit boards wherein an oil is added to the molten solder, the improvement comprising employing as an oil, a polyoxy-ethylene polyether having the formula wherein each R radical is individually selected from the group consisting of hydrogen, fluoro, chloro, and lower alkyl having 1 to 4 carbon atoms, and wherein each X is individually selected from the group consisting of a) b) wherein n and m are integers greater than 2 such that the molecular weight of said polyether is from about 500 Daltons to about 10,000 Daltons.
14. The process of claim 13 wherein each R is hydrogen.
15. The process of claim 13 wherein said polyether has a molecular weight of from 500 to 5000 Daltons.
16. The process of claim 13 wherein said polyether has a molecular weight of from 600 to 2000 Daltons.
17. In a process for soldering printed circuit boards utilizing solder reflow wherein solder coated circuit boards having mounted thereon components to be soldered thereto are immersed in a heat transfer fluid whereupon the solder melts and flows, bonding said components to the board or to each other, the improvement comprising employing as the solder reflow heat transfer fluid, a polyoxyethylene polyether having the formula wherein each R radical is individually selected from the group consisting of hydrogen, fluoro, chloro, and lower alkyl having 1 to 4 carbon atoms, and wherein each X is individually selected from the group consisting of a) b) wherein n and m are integers greater than 2 such that the molecular weight of said polyether is from about 500 Daltons to about 10,000 Daltons.
18. The process of claim 17 wherein each R is H.
19. The process of claim 17 wherein said molecular weight is from about 500 Dalton to 5000 Daltons.
20. The process of claim 17 wherein said molecular weight is from about 600 Daltons to 2000 Daltons.
21. In a solder flux utilizing one or more inorganic or organic cleaning agents, the improvement comprising utilizing as one component, a polyoxyethylene polyether having the formula wherein each R radical is individually selected from the group consisting of hydrogen, fluoro, chloro, and lower alkyl having 1 to 4 carbon atoms, and wherein each X is individually selected from the group consisting of a) b) wherein n and m are integers greater than 2 such that the molecular weight of said polyether is from about 500 Daltons to about 10,000 Daltons.
22. The flux of claim 21 wherein each R is H.
23. The flux of claim 21 wherein said molecular weight is from 500 to 5000 Daltons.
24. The flux of claim 21 wherein said molecular weight is from 600 to 2000.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US73240485A | 1985-05-09 | 1985-05-09 | |
| US732,404 | 1985-05-09 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1255700A true CA1255700A (en) | 1989-06-13 |
Family
ID=24943397
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000506715A Expired CA1255700A (en) | 1985-05-09 | 1986-04-15 | Thermally stable polyoxyalkylene heat transfer fluids |
Country Status (3)
| Country | Link |
|---|---|
| JP (1) | JPS6230120A (en) |
| CA (1) | CA1255700A (en) |
| DE (1) | DE3615092A1 (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4830263A (en) * | 1985-05-09 | 1989-05-16 | Basf Corporation | Thermally stable polyoxyalkylene heat transfer fluids |
| GB8923088D0 (en) * | 1989-10-13 | 1989-11-29 | Ici Plc | Heat transfer and fluids therefor |
-
1986
- 1986-04-15 CA CA000506715A patent/CA1255700A/en not_active Expired
- 1986-05-03 DE DE19863615092 patent/DE3615092A1/en not_active Withdrawn
- 1986-05-07 JP JP10323386A patent/JPS6230120A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| DE3615092A1 (en) | 1986-11-13 |
| JPS6230120A (en) | 1987-02-09 |
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