CA1209750A - Alkali metal borohydride concentrate - Google Patents
Alkali metal borohydride concentrateInfo
- Publication number
- CA1209750A CA1209750A CA000453523A CA453523A CA1209750A CA 1209750 A CA1209750 A CA 1209750A CA 000453523 A CA000453523 A CA 000453523A CA 453523 A CA453523 A CA 453523A CA 1209750 A CA1209750 A CA 1209750A
- Authority
- CA
- Canada
- Prior art keywords
- alkali metal
- metal borohydride
- borohydride
- concentrate
- resinous polymer
- 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.)
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Abstract
TITLE: ALKALI METAL BOROHYDRIDE CONCENTRATE
ABSTRACT OF THE DISCLOSURE
Alkali metal borohydride concentrates are prepared by dry blending alkali metal borohydride powder with a dry non-reactive plastic resin, melting and extruding the blended mixture to form an encapsulated alkali metal borohydride concentrate, and then chopping the extrusion into pellets. The pellet concentrate may then be blended into other materials.
ABSTRACT OF THE DISCLOSURE
Alkali metal borohydride concentrates are prepared by dry blending alkali metal borohydride powder with a dry non-reactive plastic resin, melting and extruding the blended mixture to form an encapsulated alkali metal borohydride concentrate, and then chopping the extrusion into pellets. The pellet concentrate may then be blended into other materials.
Description
~2~97~$~
TITLE: ALKALI METAL BOROHYDRIDE CONCENTRATE
BACK&ROUND OF THE INVENTION
The use of alkali metal borohydrides such as sodium borohydride and potassium borohydride as blowing agents in connection with the production of cellular articles is well known. For example, United States Patellt Number
TITLE: ALKALI METAL BOROHYDRIDE CONCENTRATE
BACK&ROUND OF THE INVENTION
The use of alkali metal borohydrides such as sodium borohydride and potassium borohydride as blowing agents in connection with the production of cellular articles is well known. For example, United States Patellt Number
2,951,819 utilizes an alkali metal borohydride in connec-tion with the manufacture of cellular articles. United States Patent No. 3,167,520 relates to cellular articles prepared from polystyrene by extruding polystyrene resin containing an alkali metal borohydride which decomposes during extrusion to form a cellular article. The inven-tion of this application is directed to an improvement to the technique of aforesaid United States Patent No.
3,167,520.
SUMMA~Y OF T~E INVENTION
The invention involves the use of alkali metal borohydrides such as sodium and potassium borohydride as blowing agents useful in connection with the production of articles having a foamed or cellular structure. One particularly advantageous embodiment of the invention .in-volves the use of a stable borohydride concentrate mixture containing from about 0.5% to 20% by weight of an alkali metal borohydride with a dry inert resinous polymer. The ~r~
., ~21;9~
concentrate should contain no more than about 0.1% ad-sorbed water or the borohydride will hydrolyze. Such water may be adsorbed on.the surface of the borohydride and/or on the surface of the resinous polymer.
The concentrates of the invention may be made by dry blending from 0.5% to 20% by weight of powdered alkali metal borohydride with a dry inert resinous polymer to form a mixture containing less than about 0.1% by weight wa-ter; heating the mixture to a temperature above that of the melting point o~ the resin to form a molten mixture; extrudin~ the molten mixture and then cooling the e~trusion to form a solid, stable concentrate; and then forming the cooled extrusioned concentrate into pel-lets by conventional techniques such as chopping, grinding and the like.
Another aspect of the invention comprises a method for making cellular articles by contacting a mixture of alkali metal borohydride and a resinous polymer with a high surface area silica activating agent having a proton source adsorbed on its surface so as to cause said alkali metal borohydride to hydrolyze thereby causing said resinous polymer to have a foamed cellular structure. The alkali metal borohydride may be in the form of the con-centrate described above or as neat powdered alkali metal borohydride.
DETAILED DESC~IPTION OF THE IN~ENTION
The concentrates of the invention may be used to incorporate low levels of alkali metal borohydride i.nto the same or different resins with the object of using the incorporated borohydride to foam -the resin where an additional protonic activator such as wa.ter, alcohol or acid is also added to the resin to react with the boro-hydride to produce hydrogen.
.
.3_ When used as a blowing agent for ~hermoplastic resins, up to 0.5% NaBH4 may be incorporated into the resin ~rom the concentrate. The preferred range is up to 0.25%.
The use of concentrates to incorporate low levels oi borohydride into resins has several advantages. First of all, the concentrates protect the borohydride irom adventitious hydrolysis during ha~dling and may be stored for peri.ods on the order of a year without the occurrence of signi~icant hydrolysis. Secondly, it is much easier to incorporate the borohydride at very low levels such as less than 1 wt.% into the resin by using the concentrates.
Thirdly, overall handling such as weighing and making uniform mixtures is much easier using the concen~rates than using neat borohydrid~. Because such highly reactive material has been concentrated and rendered substantially inert, employee safety is enhanced. In addition, very uniform dispersions of borohydride in the resin are ob-tained using the concentrates.
The s-table borohydride concentrate of the invention comprises from about 0.5% to 20% by ~eight of an alkali metal borohydride, less than about 0.1~ adsorbed water, balance essentially being dry inert resinous polymer. The 0.5% lower limit for borohydrides was selected primarily because lower concentrations would necessarily involve the use o~ excessive amounts of the concentrate and the 20%
upper limit was selected because higher levels would re-quire excessively small amounts of the concentrate and thereby hamper the attainment of uniform dispersion in the thermoplastic polymer to be foamed. It is preferred to include the alkali metal borohydride in amounts be-tween 2 and 10% because such range permits let-down ratios on the order o~ about 20:1 as are normally desired in the industry. Sodium and potassium borohydrides are contem-~lated for use in connection with the invention. The 9?75~
concentrate should contain no more than about 0.1% by weight o~ adsorbed water, preferably not more than about 0.01%, in order to prevent hydrolysis of the borohydride. Thus, the borohydride and resin must be very dry when mixed to ~orm the concentrate and moisture pick-up should be avoided during such mixing.
The inert resinous polymer component o~ the con-centrate compriæes resi~s in which reactive pxotonic hydrogen atoms are substantially absent. Such resins include polyolefins, polydienes, polystyrene, polyphenylene-oxide-styrene,polyacrylates, polyvinylchloride, polyvinyl-acetate and the like.
The alkali metal borohydride concentrates of the illvention are prepared by dry blending from about 0.5%
to 2070 by wei~ht o~ the borohydride with the inert resinous polymer to ~orm a dry mi~ture thereof. The mixture should contain less than about 0.1% o~ adsorbed water. The mix-ture is then treated to a temperature in excess of the melting point o the re~in, extruded, cooled, and ormed i~to pellets.
As mentioned previously, the alkali metal boro-hydride has utility as a blowing agent in connection with the manufacture of cellular or ~oamed resinous articles.
Typical res,inous polymers that may be foamed wi$h use of the concentrate include but are not limited to polyolefins, polydienes, po]ystyrene, polyphenyleneoxide-styrene,poly-acryletes, polyvinylchloride, polyvinylacetate and the like.
Cellular articles may be manufactured by mixing ~he alkali metal borohydride concentrate mentioned above with a resinous polymer and an e~-fective amount o an activating agent capable of donating an acidic proton to the alka].i metal borohydride so as to hydrolyze substantially all of the alkali metal borohydride while the resinous polymer is molten and thus ~orm a cellular article. The activating agent may comprise a fi~ely , ~.
divided high surface area solid having a proton source adsorbed on its surface. A preferred activating agent is finely divided high surface area silica.
An example of a form of silica suitable for use in the invention is that manufactured by Cabot Corporation under the designation "CAB-O-SIL'~ Such type of silica is manufactured by fumin~. It is pre~erred to utilize silica having a surface pH of less than 7 because acidic mater:ials aid in the decomposition of alkali metal boro-hydrides. It is especially preferred to have a pH in the range of 4 or lower. Finely divided, high surface area activating agents function to provide nucleation sites for foam to form. These materials have a very high capacity for adsorbing liquids such as water and yet remain a free-~lowing solid so as to thereby aid in the promotion of uniformity during the blending or mixing stage of the process.
Suitable proton sources include water, mineral acids, carboxylic acids, alcohols,sulfonic acids, poly-acrylic acid~ polystyrene sulfo~ic acid and li~e materials.
Water is preferred due to its relative cost, availability, and low corrosivity.
It has also been discovered that the silica acti-vators described above may also be used in combination with alkali metal borohydride materials other than the concentrate described above. ~or example, powdered alkali metal borohydrides may be utilized in combination with the silica activators to produce foamed polymers.
As in the case of the concentrate additions, the alkali metal borohydride and a resinous polymer are contacted with a sufficient amount of activating agent to cause substantially all of the borohydrides to hydrolyze.
The following examples further illustrate the practice o~ the invention.
Example 1 Sodium borohydride was concentrated in polypropylene by the following procedure. Ninety parts by weight of pre-viously dried, powdered, unstabilized polypropylene resin (melt index 12) and 10 parts by weight of NaBH4 that was previously dried 24 hrs at 100~C, were thoroughly mixed in a dry blender. The resultant mixture was extruded through a 1/8 inch diameter die at about 450F. The extruded rod was pelle~ized in line with the extruder. The extruded con-centrate was examined with a low power microscope and an ex-tremely uniform dispersion of minute borohydride particles was found. Virtually no gas bubbles were observed in the resin pellets.
Example 2 Sodium borohydride was concentrated in NORYL resins in the following manner. Ninety parts by weight of dry NORYL~3 r~sin FN 215, a proprietary General Electric Co. blend of poly-phenylene oxide and po~ystyrene in pellet form, was mixed with 0.1 part ~y weight of mineral oil and 10 parts by weight of NaBH4 powder, that was previously dried at 100C for 8 hrs.
The resultant dry blended mixture was then extruded at about 450F and pelletized as described in the previous example.
The concentrate pellets were e~uivalent to the pellets of Example 1.
Example 3 Sodium borohydride was concentrated in polystyrene with use of the following procedure. Ninety parts by weight of pre-viously dried high impact polystyrene pellets was blended with 0.1 part of mineral oil and 10 parts by weight of dry NaBH4 powder. The resultant mixture was then extruded at about 450F
and pelletized as described in Example 1. As in Example 1, an excellent dispersion of minute particles o~ NaBH4 in the resin was produced with virtually no gas bubbles observed.
Example_ An activating agent concentrate was prepared by-the ~ollowing procedure. 2806 parts by weight of CAB-O-SIL fumed silica was intensively mixed with 71 parts by weight of a solution (65% solids) of polyacrylic acid in water for five minutes with use of a Henschel mixer. The resultant mixture was a "dry" free flowing powder.
Example 5 The procedure described in Example 4 was also used to prepare an activator concentrate containing 71.4 parts by weight of water. The water was added slowly to 28.6 parts by weight of CAB-O-SIL fumed silica while mixing. The con-centrate handled as a "dry" powderO
Example 6 Polypropylene foamed fibers were prepared as follows. The series of blends of polypropylene resin powder, sodium boro-hydride, and CAB-O-SIL whose compositions are shown in Table I were prepared. The polypropylene powder was not dried prior to blending, but rather was blended in the "as-received"
condition.
TABLE I
Polypropylene 99.89 99.75 99.5 99.95 99.92 NaBH4 0.1 0.25 0.5 0.05 0.075 CAB-O-SIL 0.001 0.0025 0.005 0.005 0.00075 These mixtures of Table I were extruded through a 3/4 inch diameter die at 430-440F to form filaments with varying amounts of oriented foamed cells. A 3 1/2:1 compression ratio was em-ployed. The moisture present on ~he NaBH~ and the resin was sufficient to activate the release of hydrogen to foam the fibres as they passed thrcugh the melt phase in the extruder.
, ~
-8- ~2~
Example 7 Foamed polypropylene structural parts were prepared by the following procedure. Blends of undried polypropylene resin powder, sodium borohydride, powdered stearic acid and CAB-O-SII. were prepared in a Henschel Mixer. Stearic acid func-tioned as the activator and CAB-O-SIL as the nucleating agent for bubble formation in this system. This system was limited to 1~ stearic acid activator due to the limited solubility of the acid in the solid resin and because the lubricity in the barrel of the extruder provided by $he molten stearic acid causes slippage of the screw Although good foams were pre-pared with good density reduction, stearic acid and other fatty acids are less than ideal activators because of the above mentioned factors. In any e~ent, structural foam parts of good quality were produced on a reciprocating screw L/D 16:1, 100 ton, 5 oz. injection molding machine equipped with a cut off nozzle. The compositions shown in Table II were so pro-duced. All percentages are based on the weight of polypropylene resin.
TAB~E II
SBH Fumed Silica Stearic Acid % Wt. Reduction % % ~ of Part Due to Foam -0.06 0.1 1.0 20.2 0.13 0.1 1.0 27.3 0.25 0.1 1.0 34.4 ~.~ 0.1 1.0 37.3 1.0 0.1 1.0 33.7 Example 8 Foamed polystyrene structural parts were prepared by the following procedure. Polystyrene resin powder, the sodium borohydride concentrate prepared in Example 3, and either the activatox of Example 4 or Example 5 were blended in the pro-portion shown in Table III. All percentages are based upon the weight of the resin.
. .
g ~ ~5@~
TABLE III
~ Conc. of % Conc. of E~le 3 % Conc. of Example 4 NaBH4 Chemical E~le 5 Polyacrylic % Part Blowlng Agent H20 Activator Acid Ackivator Wt. Reduction 1 0.56 16 1 0.28 15.1 2 0.28 18.4
SUMMA~Y OF T~E INVENTION
The invention involves the use of alkali metal borohydrides such as sodium and potassium borohydride as blowing agents useful in connection with the production of articles having a foamed or cellular structure. One particularly advantageous embodiment of the invention .in-volves the use of a stable borohydride concentrate mixture containing from about 0.5% to 20% by weight of an alkali metal borohydride with a dry inert resinous polymer. The ~r~
., ~21;9~
concentrate should contain no more than about 0.1% ad-sorbed water or the borohydride will hydrolyze. Such water may be adsorbed on.the surface of the borohydride and/or on the surface of the resinous polymer.
The concentrates of the invention may be made by dry blending from 0.5% to 20% by weight of powdered alkali metal borohydride with a dry inert resinous polymer to form a mixture containing less than about 0.1% by weight wa-ter; heating the mixture to a temperature above that of the melting point o~ the resin to form a molten mixture; extrudin~ the molten mixture and then cooling the e~trusion to form a solid, stable concentrate; and then forming the cooled extrusioned concentrate into pel-lets by conventional techniques such as chopping, grinding and the like.
Another aspect of the invention comprises a method for making cellular articles by contacting a mixture of alkali metal borohydride and a resinous polymer with a high surface area silica activating agent having a proton source adsorbed on its surface so as to cause said alkali metal borohydride to hydrolyze thereby causing said resinous polymer to have a foamed cellular structure. The alkali metal borohydride may be in the form of the con-centrate described above or as neat powdered alkali metal borohydride.
DETAILED DESC~IPTION OF THE IN~ENTION
The concentrates of the invention may be used to incorporate low levels of alkali metal borohydride i.nto the same or different resins with the object of using the incorporated borohydride to foam -the resin where an additional protonic activator such as wa.ter, alcohol or acid is also added to the resin to react with the boro-hydride to produce hydrogen.
.
.3_ When used as a blowing agent for ~hermoplastic resins, up to 0.5% NaBH4 may be incorporated into the resin ~rom the concentrate. The preferred range is up to 0.25%.
The use of concentrates to incorporate low levels oi borohydride into resins has several advantages. First of all, the concentrates protect the borohydride irom adventitious hydrolysis during ha~dling and may be stored for peri.ods on the order of a year without the occurrence of signi~icant hydrolysis. Secondly, it is much easier to incorporate the borohydride at very low levels such as less than 1 wt.% into the resin by using the concentrates.
Thirdly, overall handling such as weighing and making uniform mixtures is much easier using the concen~rates than using neat borohydrid~. Because such highly reactive material has been concentrated and rendered substantially inert, employee safety is enhanced. In addition, very uniform dispersions of borohydride in the resin are ob-tained using the concentrates.
The s-table borohydride concentrate of the invention comprises from about 0.5% to 20% by ~eight of an alkali metal borohydride, less than about 0.1~ adsorbed water, balance essentially being dry inert resinous polymer. The 0.5% lower limit for borohydrides was selected primarily because lower concentrations would necessarily involve the use o~ excessive amounts of the concentrate and the 20%
upper limit was selected because higher levels would re-quire excessively small amounts of the concentrate and thereby hamper the attainment of uniform dispersion in the thermoplastic polymer to be foamed. It is preferred to include the alkali metal borohydride in amounts be-tween 2 and 10% because such range permits let-down ratios on the order o~ about 20:1 as are normally desired in the industry. Sodium and potassium borohydrides are contem-~lated for use in connection with the invention. The 9?75~
concentrate should contain no more than about 0.1% by weight o~ adsorbed water, preferably not more than about 0.01%, in order to prevent hydrolysis of the borohydride. Thus, the borohydride and resin must be very dry when mixed to ~orm the concentrate and moisture pick-up should be avoided during such mixing.
The inert resinous polymer component o~ the con-centrate compriæes resi~s in which reactive pxotonic hydrogen atoms are substantially absent. Such resins include polyolefins, polydienes, polystyrene, polyphenylene-oxide-styrene,polyacrylates, polyvinylchloride, polyvinyl-acetate and the like.
The alkali metal borohydride concentrates of the illvention are prepared by dry blending from about 0.5%
to 2070 by wei~ht o~ the borohydride with the inert resinous polymer to ~orm a dry mi~ture thereof. The mixture should contain less than about 0.1% o~ adsorbed water. The mix-ture is then treated to a temperature in excess of the melting point o the re~in, extruded, cooled, and ormed i~to pellets.
As mentioned previously, the alkali metal boro-hydride has utility as a blowing agent in connection with the manufacture of cellular or ~oamed resinous articles.
Typical res,inous polymers that may be foamed wi$h use of the concentrate include but are not limited to polyolefins, polydienes, po]ystyrene, polyphenyleneoxide-styrene,poly-acryletes, polyvinylchloride, polyvinylacetate and the like.
Cellular articles may be manufactured by mixing ~he alkali metal borohydride concentrate mentioned above with a resinous polymer and an e~-fective amount o an activating agent capable of donating an acidic proton to the alka].i metal borohydride so as to hydrolyze substantially all of the alkali metal borohydride while the resinous polymer is molten and thus ~orm a cellular article. The activating agent may comprise a fi~ely , ~.
divided high surface area solid having a proton source adsorbed on its surface. A preferred activating agent is finely divided high surface area silica.
An example of a form of silica suitable for use in the invention is that manufactured by Cabot Corporation under the designation "CAB-O-SIL'~ Such type of silica is manufactured by fumin~. It is pre~erred to utilize silica having a surface pH of less than 7 because acidic mater:ials aid in the decomposition of alkali metal boro-hydrides. It is especially preferred to have a pH in the range of 4 or lower. Finely divided, high surface area activating agents function to provide nucleation sites for foam to form. These materials have a very high capacity for adsorbing liquids such as water and yet remain a free-~lowing solid so as to thereby aid in the promotion of uniformity during the blending or mixing stage of the process.
Suitable proton sources include water, mineral acids, carboxylic acids, alcohols,sulfonic acids, poly-acrylic acid~ polystyrene sulfo~ic acid and li~e materials.
Water is preferred due to its relative cost, availability, and low corrosivity.
It has also been discovered that the silica acti-vators described above may also be used in combination with alkali metal borohydride materials other than the concentrate described above. ~or example, powdered alkali metal borohydrides may be utilized in combination with the silica activators to produce foamed polymers.
As in the case of the concentrate additions, the alkali metal borohydride and a resinous polymer are contacted with a sufficient amount of activating agent to cause substantially all of the borohydrides to hydrolyze.
The following examples further illustrate the practice o~ the invention.
Example 1 Sodium borohydride was concentrated in polypropylene by the following procedure. Ninety parts by weight of pre-viously dried, powdered, unstabilized polypropylene resin (melt index 12) and 10 parts by weight of NaBH4 that was previously dried 24 hrs at 100~C, were thoroughly mixed in a dry blender. The resultant mixture was extruded through a 1/8 inch diameter die at about 450F. The extruded rod was pelle~ized in line with the extruder. The extruded con-centrate was examined with a low power microscope and an ex-tremely uniform dispersion of minute borohydride particles was found. Virtually no gas bubbles were observed in the resin pellets.
Example 2 Sodium borohydride was concentrated in NORYL resins in the following manner. Ninety parts by weight of dry NORYL~3 r~sin FN 215, a proprietary General Electric Co. blend of poly-phenylene oxide and po~ystyrene in pellet form, was mixed with 0.1 part ~y weight of mineral oil and 10 parts by weight of NaBH4 powder, that was previously dried at 100C for 8 hrs.
The resultant dry blended mixture was then extruded at about 450F and pelletized as described in the previous example.
The concentrate pellets were e~uivalent to the pellets of Example 1.
Example 3 Sodium borohydride was concentrated in polystyrene with use of the following procedure. Ninety parts by weight of pre-viously dried high impact polystyrene pellets was blended with 0.1 part of mineral oil and 10 parts by weight of dry NaBH4 powder. The resultant mixture was then extruded at about 450F
and pelletized as described in Example 1. As in Example 1, an excellent dispersion of minute particles o~ NaBH4 in the resin was produced with virtually no gas bubbles observed.
Example_ An activating agent concentrate was prepared by-the ~ollowing procedure. 2806 parts by weight of CAB-O-SIL fumed silica was intensively mixed with 71 parts by weight of a solution (65% solids) of polyacrylic acid in water for five minutes with use of a Henschel mixer. The resultant mixture was a "dry" free flowing powder.
Example 5 The procedure described in Example 4 was also used to prepare an activator concentrate containing 71.4 parts by weight of water. The water was added slowly to 28.6 parts by weight of CAB-O-SIL fumed silica while mixing. The con-centrate handled as a "dry" powderO
Example 6 Polypropylene foamed fibers were prepared as follows. The series of blends of polypropylene resin powder, sodium boro-hydride, and CAB-O-SIL whose compositions are shown in Table I were prepared. The polypropylene powder was not dried prior to blending, but rather was blended in the "as-received"
condition.
TABLE I
Polypropylene 99.89 99.75 99.5 99.95 99.92 NaBH4 0.1 0.25 0.5 0.05 0.075 CAB-O-SIL 0.001 0.0025 0.005 0.005 0.00075 These mixtures of Table I were extruded through a 3/4 inch diameter die at 430-440F to form filaments with varying amounts of oriented foamed cells. A 3 1/2:1 compression ratio was em-ployed. The moisture present on ~he NaBH~ and the resin was sufficient to activate the release of hydrogen to foam the fibres as they passed thrcugh the melt phase in the extruder.
, ~
-8- ~2~
Example 7 Foamed polypropylene structural parts were prepared by the following procedure. Blends of undried polypropylene resin powder, sodium borohydride, powdered stearic acid and CAB-O-SII. were prepared in a Henschel Mixer. Stearic acid func-tioned as the activator and CAB-O-SIL as the nucleating agent for bubble formation in this system. This system was limited to 1~ stearic acid activator due to the limited solubility of the acid in the solid resin and because the lubricity in the barrel of the extruder provided by $he molten stearic acid causes slippage of the screw Although good foams were pre-pared with good density reduction, stearic acid and other fatty acids are less than ideal activators because of the above mentioned factors. In any e~ent, structural foam parts of good quality were produced on a reciprocating screw L/D 16:1, 100 ton, 5 oz. injection molding machine equipped with a cut off nozzle. The compositions shown in Table II were so pro-duced. All percentages are based on the weight of polypropylene resin.
TAB~E II
SBH Fumed Silica Stearic Acid % Wt. Reduction % % ~ of Part Due to Foam -0.06 0.1 1.0 20.2 0.13 0.1 1.0 27.3 0.25 0.1 1.0 34.4 ~.~ 0.1 1.0 37.3 1.0 0.1 1.0 33.7 Example 8 Foamed polystyrene structural parts were prepared by the following procedure. Polystyrene resin powder, the sodium borohydride concentrate prepared in Example 3, and either the activatox of Example 4 or Example 5 were blended in the pro-portion shown in Table III. All percentages are based upon the weight of the resin.
. .
g ~ ~5@~
TABLE III
~ Conc. of % Conc. of E~le 3 % Conc. of Example 4 NaBH4 Chemical E~le 5 Polyacrylic % Part Blowlng Agent H20 Activator Acid Ackivator Wt. Reduction 1 0.56 16 1 0.28 15.1 2 0.28 18.4
4 2.24 26.8 8 2.24 25.5 ~15 140 1 0.14 12 ~ 0.56 23.3 0.7 2~.6 Excellent quality foams having very fine uniform pore size w~re produced with use of a structural foam injection machine.
Density reductions of about 25% using only 49~ of the blowing agent concentrate (0.4% NaBF~4) and 2.24~6 of the silica/water activator concentrate are unusually high and very desirable for this type of structural foam. Normally, with nitrogen in-jection to provide cells, density reductions of less than 20%
are achieved. Moreover, the borohydride blown foam was unusu-ally white, whereas the nitrogen blown foams have a slightly yellow cast. These Activator concentrates such as water, organic acids, alcohols, etc. adsorbed on colloidal silica serve as ideal activators and nucleating agents for these sys-tems because the activators can be premixed with blowing agent concentrates in the desired ratio with no reaction occurriny.
This mixture can then be blended with the resin to be foamed in the desired ratio and fed into the foaming machine to pro-duce the foamed article.
,,.~
-10~
~ Example 9 Extruded foamed sheets of NORYL resin were manufactured by the following technique. NORYL resin was blended with the sodium borohydride blowing agent concentrate of Example 3 and an organic acid according to the percentages listed in Table IV. All percentages are based on the weight of NORYL resin.
These mixtures were extruded with a 3~4 inch~diameter extruder.
TABLE I'~
Chemical% Chemical Acid/Sodium Blowing Blcwing AcidBorohydride A~ent Agent Activator Mole Ratio De~ree of Foam E~le 3 1.0 Oleic 4/1 Highly foamed E~le 3 1.0 Octanoic4/1 Highly foamed Neat NaBH4 0~1 Octanoic4/1 Highly foamed E~ple 3 ~1.0 Stearic 4/1 Highly foamed mple 3 1.0 - - Very slight It can be observed from this example that practically no foaming occurs where the chemical blowing agent is used in the absence of an activator. Furthermore, the NaBH4 concentrates are just as efficient as an equivalent amount of Neat NaBH~ for blowing.
Neat NaBH4 suffers many other deficiencies previously described which ar~ overcome by th~ concentrates of the invention~
Density reductions of about 25% using only 49~ of the blowing agent concentrate (0.4% NaBF~4) and 2.24~6 of the silica/water activator concentrate are unusually high and very desirable for this type of structural foam. Normally, with nitrogen in-jection to provide cells, density reductions of less than 20%
are achieved. Moreover, the borohydride blown foam was unusu-ally white, whereas the nitrogen blown foams have a slightly yellow cast. These Activator concentrates such as water, organic acids, alcohols, etc. adsorbed on colloidal silica serve as ideal activators and nucleating agents for these sys-tems because the activators can be premixed with blowing agent concentrates in the desired ratio with no reaction occurriny.
This mixture can then be blended with the resin to be foamed in the desired ratio and fed into the foaming machine to pro-duce the foamed article.
,,.~
-10~
~ Example 9 Extruded foamed sheets of NORYL resin were manufactured by the following technique. NORYL resin was blended with the sodium borohydride blowing agent concentrate of Example 3 and an organic acid according to the percentages listed in Table IV. All percentages are based on the weight of NORYL resin.
These mixtures were extruded with a 3~4 inch~diameter extruder.
TABLE I'~
Chemical% Chemical Acid/Sodium Blowing Blcwing AcidBorohydride A~ent Agent Activator Mole Ratio De~ree of Foam E~le 3 1.0 Oleic 4/1 Highly foamed E~le 3 1.0 Octanoic4/1 Highly foamed Neat NaBH4 0~1 Octanoic4/1 Highly foamed E~ple 3 ~1.0 Stearic 4/1 Highly foamed mple 3 1.0 - - Very slight It can be observed from this example that practically no foaming occurs where the chemical blowing agent is used in the absence of an activator. Furthermore, the NaBH4 concentrates are just as efficient as an equivalent amount of Neat NaBH~ for blowing.
Neat NaBH4 suffers many other deficiencies previously described which ar~ overcome by th~ concentrates of the invention~
Claims (7)
1. A method for making a cellular resinous article comprising: contacting alkali metal borohydride and a res-inous polymer with an effective amount of a finely divided high surface area silica activating agent having a proton source absorbed on its surface so as to cause said alkali metal borohydride to hydrolyze, thereby creating foam and thereby causing said resinous polymer to have a cellular structure, said hydrolyzing occurring while the resinous polymer is in the molten condition.
2. A method for making a cellular resinous article comprising:
contacting alkali metal borohydride and a resinous polymer with an effective amount of a finely di-vided high surface area silica activating agent having a surface pH of less than 7 and having a proton source adsorbed on its surface so as to cause said alkali metal borohydride to hydrolyze, thereby creating foam and thereby causing said resinous polymer to have a cellular structure, said hydrolyzing occurring while the resinous polymer is in the molten condition.
contacting alkali metal borohydride and a resinous polymer with an effective amount of a finely di-vided high surface area silica activating agent having a surface pH of less than 7 and having a proton source adsorbed on its surface so as to cause said alkali metal borohydride to hydrolyze, thereby creating foam and thereby causing said resinous polymer to have a cellular structure, said hydrolyzing occurring while the resinous polymer is in the molten condition.
3. The method of claims 1 or 2 wherein:
said alkali metal borohydride is a member selected from the group consisting of sodium borohydride or potassium borohydride.
said alkali metal borohydride is a member selected from the group consisting of sodium borohydride or potassium borohydride.
4. The method of claims 1 or 2 wherein.
said alkali metal borohydride is in a powdered form.
said alkali metal borohydride is in a powdered form.
5. The method of claim 1 wherein:
said alkali metal borohydride is in the form of a concentrate consisting essentially of from about 0.5% to 20% by weight of alkali metal borohydride, less than about 0.1% absorbed water, balance essentially inert resinous polymer.
said alkali metal borohydride is in the form of a concentrate consisting essentially of from about 0.5% to 20% by weight of alkali metal borohydride, less than about 0.1% absorbed water, balance essentially inert resinous polymer.
6. The method of claims 1 or 2 wherein:
said proton source is selected from a member of the group consisting of water, mineral acid, carboxylic acids, alcohol, sulfonic acids, or polystyrene sulfonic acid.
said proton source is selected from a member of the group consisting of water, mineral acid, carboxylic acids, alcohol, sulfonic acids, or polystyrene sulfonic acid.
7. The method of claims 1 or 2 wherein:
said alkali metal borohydride is sodium borohydride.
said alkali metal borohydride is sodium borohydride.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000453523A CA1209750A (en) | 1981-06-12 | 1984-05-03 | Alkali metal borohydride concentrate |
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US27286781A | 1981-06-12 | 1981-06-12 | |
| US272,867 | 1981-06-12 | ||
| CA000398721A CA1190729A (en) | 1981-06-12 | 1982-03-18 | Alkali metal borohydride concentrate |
| CA000453523A CA1209750A (en) | 1981-06-12 | 1984-05-03 | Alkali metal borohydride concentrate |
Related Parent Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000398721A Division CA1190729A (en) | 1981-06-12 | 1982-03-18 | Alkali metal borohydride concentrate |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1209750A true CA1209750A (en) | 1986-08-12 |
Family
ID=25669621
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000453523A Expired CA1209750A (en) | 1981-06-12 | 1984-05-03 | Alkali metal borohydride concentrate |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1209750A (en) |
-
1984
- 1984-05-03 CA CA000453523A patent/CA1209750A/en not_active Expired
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