CA1082850A - Manufacture of foamed sulfur - Google Patents
Manufacture of foamed sulfurInfo
- Publication number
- CA1082850A CA1082850A CA251,834A CA251834A CA1082850A CA 1082850 A CA1082850 A CA 1082850A CA 251834 A CA251834 A CA 251834A CA 1082850 A CA1082850 A CA 1082850A
- Authority
- CA
- Canada
- Prior art keywords
- sulfur
- foamed
- dicyclopentadiene
- mixture
- interaction
- 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
Links
Classifications
-
- 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
- C08G75/00—Macromolecular compounds obtained by reactions forming a linkage containing sulfur with or without nitrogen, oxygen, or carbon in the main chain of the macromolecule
- C08G75/14—Polysulfides
- C08G75/16—Polysulfides by polycondensation of organic compounds with inorganic polysulfides
Landscapes
- Chemical & Material Sciences (AREA)
- Inorganic Chemistry (AREA)
- Health & Medical Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Organic Chemistry (AREA)
- Manufacture Of Porous Articles, And Recovery And Treatment Of Waste Products (AREA)
- Compositions Of Macromolecular Compounds (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE: Foamed sulfur is prepared by blend-ing molten sulfur with dicyclopentadiene at temperatures of from 120 to 160°C, the period of action of the dicyolopentadiene being held between specific limits. The molten sulfur is then foamed by means of a blowing agent and solidified by cooling to temperatures below the melting point or sulfur.
Description
10 ~ ~ O.Z. 31,453 MANUFACTURE OF FOAMED SULFUR
It is known that foamed sulfur, which may be used, for exam~e, as insulating material in the building industry, may be prepared by melting elementary sulfur and then blendlng the molten sulfur with a stabillzing agent and a viscosity increaser. Bubbles are then formed in the melt, for example by the passage of a gas there-through, evaporation of a solvent or by means of a blowing agent, whereupon the mixture is cooled to below the melting point of sul-fur (U.S. Patent 3,3~7,355). Examples of agents used for increasing the viscosity of the molten sulfur are phosphorus and arsenic or sul~ides thereof, styrene and elastlc, rubbery and thermoplasti¢
plastlcs materlals of the alkyl polysulfide group such as those which are known under the tradename of Thiokol and whlch are ob-tained by the action of alkall metal polysulfides on alkyl dihalldes and subsequent partlal ellmlnation of sulfur or by the reaction of dlchlorodlethyl formal with sodium polysulfide. The stabilizing agents used to stabilize the foams formed are partlculate inert substances of plate-like form, for example mica, alumina, talc, aluminum oxlde and slllcic acid, or organlc substances such as the coupling product between diazotized p-nitroaniline and acetoacet-anilide. Examples of blowing agents which can be used are carbonate/acld systems, for example CaCO~-H3P04, or sulfide/acid systems or compounds giving off, say, nitrogen on heating, such as N,N'-di-methyl-N,N'-dinitrosoterephthalamide, N,N'-dinitrosopentamethylene-tetramine and diphenylsulfone-3,~'-disulfohydrazide, or physical blowing agents such as chlorinated and fluorinated methanes or ethanes~
German Published Application 2,324,185 describes a process for the manufacture of foamed sulfurs, in which aromatic polysulfides -1- ,~
: .
lOt~Z8SO
are Eoamed an~ cross-linked. In this process the viscosity increasers ad~ed to the molten sulfur are aromatic hydroxyl-containing compounds which forrn aromatic polysulfides with slll rur . 13ubl)1es a~e formed in thc molten matcrial by the addi-ti~n of proton donors, e.g. water or organic acids, and with isocyanates or polyisocyanates.
Finally, German Published Application 2,340,927 des-cribes a method of preparing foamed sulfur in 2 stages which, however, does not differ from the aforementioned process as regards the additives used.
However, the manufacture of foamed sulfur still gives rise to considerable problems. If, as proposed in U.S.
Patent 3,337,355, the viscosity increasers used are inorganic substances such as phosphorus and arsenic and/or their sulfides and if acids are used as part of the expanding system, large alllounts of poisonous hydrogen sulEide are formed. If the vis-cosity is incre~ased by the use of styrenc, the said Thiokol poly-sulfides or even phenols in conjunction with the described isocyanate additives, evil-smelling products are again formed by reaction with the molten sulfur, and the aliphatic and aromatic compounds increase the cost of the foamed sulfur con-siderably. For example, the foamed sulfurs described in German Published Application 2,324,175 mostly contain from 20 to 30% by weight of organic compounds.
It is an object of the present invention to avoid the above drawbacks in the manufacture of foamed sulfurs and to filld a viscosiLy-increasilly <ubstallce wl-icll makes it possible to avoid the occurrence of unpleasant odors and poisonous gases.
We have found that this object is achieved in a process for the manufacture o~ foamed sulfur by blending molten sulfur with viscosity-increasillg and stabilizing compounds, foaming
It is known that foamed sulfur, which may be used, for exam~e, as insulating material in the building industry, may be prepared by melting elementary sulfur and then blendlng the molten sulfur with a stabillzing agent and a viscosity increaser. Bubbles are then formed in the melt, for example by the passage of a gas there-through, evaporation of a solvent or by means of a blowing agent, whereupon the mixture is cooled to below the melting point of sul-fur (U.S. Patent 3,3~7,355). Examples of agents used for increasing the viscosity of the molten sulfur are phosphorus and arsenic or sul~ides thereof, styrene and elastlc, rubbery and thermoplasti¢
plastlcs materlals of the alkyl polysulfide group such as those which are known under the tradename of Thiokol and whlch are ob-tained by the action of alkall metal polysulfides on alkyl dihalldes and subsequent partlal ellmlnation of sulfur or by the reaction of dlchlorodlethyl formal with sodium polysulfide. The stabilizing agents used to stabilize the foams formed are partlculate inert substances of plate-like form, for example mica, alumina, talc, aluminum oxlde and slllcic acid, or organlc substances such as the coupling product between diazotized p-nitroaniline and acetoacet-anilide. Examples of blowing agents which can be used are carbonate/acld systems, for example CaCO~-H3P04, or sulfide/acid systems or compounds giving off, say, nitrogen on heating, such as N,N'-di-methyl-N,N'-dinitrosoterephthalamide, N,N'-dinitrosopentamethylene-tetramine and diphenylsulfone-3,~'-disulfohydrazide, or physical blowing agents such as chlorinated and fluorinated methanes or ethanes~
German Published Application 2,324,185 describes a process for the manufacture of foamed sulfurs, in which aromatic polysulfides -1- ,~
: .
lOt~Z8SO
are Eoamed an~ cross-linked. In this process the viscosity increasers ad~ed to the molten sulfur are aromatic hydroxyl-containing compounds which forrn aromatic polysulfides with slll rur . 13ubl)1es a~e formed in thc molten matcrial by the addi-ti~n of proton donors, e.g. water or organic acids, and with isocyanates or polyisocyanates.
Finally, German Published Application 2,340,927 des-cribes a method of preparing foamed sulfur in 2 stages which, however, does not differ from the aforementioned process as regards the additives used.
However, the manufacture of foamed sulfur still gives rise to considerable problems. If, as proposed in U.S.
Patent 3,337,355, the viscosity increasers used are inorganic substances such as phosphorus and arsenic and/or their sulfides and if acids are used as part of the expanding system, large alllounts of poisonous hydrogen sulEide are formed. If the vis-cosity is incre~ased by the use of styrenc, the said Thiokol poly-sulfides or even phenols in conjunction with the described isocyanate additives, evil-smelling products are again formed by reaction with the molten sulfur, and the aliphatic and aromatic compounds increase the cost of the foamed sulfur con-siderably. For example, the foamed sulfurs described in German Published Application 2,324,175 mostly contain from 20 to 30% by weight of organic compounds.
It is an object of the present invention to avoid the above drawbacks in the manufacture of foamed sulfurs and to filld a viscosiLy-increasilly <ubstallce wl-icll makes it possible to avoid the occurrence of unpleasant odors and poisonous gases.
We have found that this object is achieved in a process for the manufacture o~ foamed sulfur by blending molten sulfur with viscosity-increasillg and stabilizing compounds, foaming
2-108~
the molten mixture by means of a blowing agent and solidifying the foamed mixture by cooling thereof to temperatures below the melting point of sulfur, wherein dicyclopentadiene is added to the molten sulfur in an amount of 2 to 8~ at tempera-tures of from 120 to 160C as viscosity increaser, the period ' .
:. :
:. ~ . .
. . ~ ' .
lV~2850 o.z. 31,453 of lnteraction between the sulfur and dicyclopentadiene at the tem-perature used being restricted by the values of the ordinates in the accompanying figure at the points of intersection between the curves A and D and a straight line parallel to the ordinate axis and lnter-sectlng the abscissa axis at the temperature used.
The process of the inventlon may be carried out ln a variety of ways. For example, the molten sulfur may be blended with from 2 to 8% and preferably rrOm 4 to 6%, by weight, of dicyclopenta-diene, whereupon these two substances are allowed to interreact for the relevant total reaction tlme depending on the temperature used and given by the accompanying flgure and adding the other ingre-dients, i.e. the stabilizer and blowing agent, during said reaction tlme and immediately cooling the molten mlxture to temperatures below the solidifying point at the end of said reaction period.
The time of commencement of foamlng must be selected such that foamlng ls oomplete at the end of the total reactlon tlme, slnce the foamed melt ls then cooled to below the melting point.
Accordlng to a particularly preferred embodiment of the pro-cess of the invention, a mixture of sulfur and dicyclopentadiene is prepared and these components are allowed to interact for only from 80 to 99% of the time required at the temperature used. In this first stage it is preferred to use higher temperatures, for example tem-peratures of from 130 to 145C, in order to accelerate the reaction between sulfur and dicyclopentadiene. In the second stage, which may be separated from the first stage in space and time, lower tem-peratures of from 120 to 130C are preferred, since ~ust a small dif-~erence in temperature between the liquid and solidifying melt gives greater uniformity in the size of the foam pores formed. In this second stage, the stabilizing agent, iOe. talcg and the blowing agent, e.g. calcite, are stirred into the melt and finally the foam is produced by stirring in concentrated phosphoric acid, these ope-rations being carried out in the remainder of the reaction time as determined by the different temperature used.
~oez~
o,Z. ~1,453 The Table 1 below llsts some points on the curves A and D and on curves B and C determining the pre~erred interaction times.
Temperature (C) Total reactlon tlme (hours) A B C D
120 ll,oo 15.00 23.0~ 29.00 125 4.70 6s60 11.50 14.00 130 2.35 ~.~0 6.oo 8.oo 135 1.25 1 r 80 ~.40 4.70 140 7 1O05 2015 2.90 145 0.4~ 0067 1.40 l.90 150 0027 0.44 o.g5 1-35 155 0.18 0.31 0.67 1.00 160 0.12 0.22 0.50 0.75 The process o~ the lnvention ls preferably carried out at tem-peratures Or from 120 to 145C.
As ln the prlor art processes, suitable stabilizers are fine-ly powdered substances havlng particles of plate-like structure and inert to the molten sulfur and other additives, examples bein8 mica, alumina, aluminium oxide and talc. The stablllzers are added to the melt ln amounts of froml 0 to 50~ by weight, based on the sulfur.
Particularly suitable blowing agents are, again as in the prior art processes, carbonate-containing substances such as cal-clte, sodium carbonate and sodium bicarbonate in con~unction with aclds such as phosphoric acid and sul~urlc acid. It wlll be appre-ciated that any other blowing agent known to be suitable for thls purpose may be used, for example the said nitrogen-eliminating blowing agents or physical blowing agents based on chlorinated and fluorinated hydrocarbons, e.g. monofluorotrlchloromethane, difluoro-dlchloromethane, trifluoromonochloromethane, difluoromonochloro-methane, tri~luorotrichloroethane, tetrafluorodlchloroethane, octa-- 1082~S0 o,z. 31,453 fluorocyclobutane, and trlfluoromonobromomethane.
The amounts of blowing agent used depend on the desired densi-ty of the foamed sulfur to be manufactured and on the blowing agent ltselr .
EXAMPLE
(a) 648 parts by welght of sulfur are blended wlth 32 parts by welght of dicyclopentadiene at a temperature of 135C and the mlx-ture ls held at this temperature for 135 mlnutes (90% of the average total reactlon tlme requlred at thls temperature). The temperature is reduced to 125C and 257 parts by weight of talc and 36 parts by weight of F-calcite are stirred into the mixture and stirring is continued for a total of 54 minutes (10% of the average total re-action time required at this temperature). At the end of this re-actlon period, the melt is blended with 27 parts by weight of con-centrated phosphoric acid (93% H3P04), whereupon the mixture foams.
It ls then poured into molds to set.
The ~oamed sulfur prepared ln thls manner has the followlng propertles:
density (g/cm3) o,30 compressive strength (kg/cm3) 12.0 flexural strength (kg/cm3) 7.6 heat conductivlty ( kcal ) 0.09 mhr C
water absorption after 28 days 13.5/48.4 coefficient of impermeability to water520 vapor/u proportion of closed cells (~) 46.
The above combination of properties makes this foamed sulfur a rigid foam which may be used, for example, as an antifreeze ma-terlal for road constructlon.
(b) This test is commenced as in Example (a), but the mixture of sulfur and dlcyclopentadiene ls held at 135C for 360 minutes.
The melt ls so viscous that neither talc nor blowing agent can be incorporated.
1082~50 o.z. ~1,45 (c) This test is commenced as in Example (a), but the mixture is held at 1~5C for, say, only 40 minutes. When the test ls then continued as ln Example (a), a foam is obtalned whlch forms volds prlor to solldirication and usually collapses completely.
the molten mixture by means of a blowing agent and solidifying the foamed mixture by cooling thereof to temperatures below the melting point of sulfur, wherein dicyclopentadiene is added to the molten sulfur in an amount of 2 to 8~ at tempera-tures of from 120 to 160C as viscosity increaser, the period ' .
:. :
:. ~ . .
. . ~ ' .
lV~2850 o.z. 31,453 of lnteraction between the sulfur and dicyclopentadiene at the tem-perature used being restricted by the values of the ordinates in the accompanying figure at the points of intersection between the curves A and D and a straight line parallel to the ordinate axis and lnter-sectlng the abscissa axis at the temperature used.
The process of the inventlon may be carried out ln a variety of ways. For example, the molten sulfur may be blended with from 2 to 8% and preferably rrOm 4 to 6%, by weight, of dicyclopenta-diene, whereupon these two substances are allowed to interreact for the relevant total reaction tlme depending on the temperature used and given by the accompanying flgure and adding the other ingre-dients, i.e. the stabilizer and blowing agent, during said reaction tlme and immediately cooling the molten mlxture to temperatures below the solidifying point at the end of said reaction period.
The time of commencement of foamlng must be selected such that foamlng ls oomplete at the end of the total reactlon tlme, slnce the foamed melt ls then cooled to below the melting point.
Accordlng to a particularly preferred embodiment of the pro-cess of the invention, a mixture of sulfur and dicyclopentadiene is prepared and these components are allowed to interact for only from 80 to 99% of the time required at the temperature used. In this first stage it is preferred to use higher temperatures, for example tem-peratures of from 130 to 145C, in order to accelerate the reaction between sulfur and dicyclopentadiene. In the second stage, which may be separated from the first stage in space and time, lower tem-peratures of from 120 to 130C are preferred, since ~ust a small dif-~erence in temperature between the liquid and solidifying melt gives greater uniformity in the size of the foam pores formed. In this second stage, the stabilizing agent, iOe. talcg and the blowing agent, e.g. calcite, are stirred into the melt and finally the foam is produced by stirring in concentrated phosphoric acid, these ope-rations being carried out in the remainder of the reaction time as determined by the different temperature used.
~oez~
o,Z. ~1,453 The Table 1 below llsts some points on the curves A and D and on curves B and C determining the pre~erred interaction times.
Temperature (C) Total reactlon tlme (hours) A B C D
120 ll,oo 15.00 23.0~ 29.00 125 4.70 6s60 11.50 14.00 130 2.35 ~.~0 6.oo 8.oo 135 1.25 1 r 80 ~.40 4.70 140 7 1O05 2015 2.90 145 0.4~ 0067 1.40 l.90 150 0027 0.44 o.g5 1-35 155 0.18 0.31 0.67 1.00 160 0.12 0.22 0.50 0.75 The process o~ the lnvention ls preferably carried out at tem-peratures Or from 120 to 145C.
As ln the prlor art processes, suitable stabilizers are fine-ly powdered substances havlng particles of plate-like structure and inert to the molten sulfur and other additives, examples bein8 mica, alumina, aluminium oxide and talc. The stablllzers are added to the melt ln amounts of froml 0 to 50~ by weight, based on the sulfur.
Particularly suitable blowing agents are, again as in the prior art processes, carbonate-containing substances such as cal-clte, sodium carbonate and sodium bicarbonate in con~unction with aclds such as phosphoric acid and sul~urlc acid. It wlll be appre-ciated that any other blowing agent known to be suitable for thls purpose may be used, for example the said nitrogen-eliminating blowing agents or physical blowing agents based on chlorinated and fluorinated hydrocarbons, e.g. monofluorotrlchloromethane, difluoro-dlchloromethane, trifluoromonochloromethane, difluoromonochloro-methane, tri~luorotrichloroethane, tetrafluorodlchloroethane, octa-- 1082~S0 o,z. 31,453 fluorocyclobutane, and trlfluoromonobromomethane.
The amounts of blowing agent used depend on the desired densi-ty of the foamed sulfur to be manufactured and on the blowing agent ltselr .
EXAMPLE
(a) 648 parts by welght of sulfur are blended wlth 32 parts by welght of dicyclopentadiene at a temperature of 135C and the mlx-ture ls held at this temperature for 135 mlnutes (90% of the average total reactlon tlme requlred at thls temperature). The temperature is reduced to 125C and 257 parts by weight of talc and 36 parts by weight of F-calcite are stirred into the mixture and stirring is continued for a total of 54 minutes (10% of the average total re-action time required at this temperature). At the end of this re-actlon period, the melt is blended with 27 parts by weight of con-centrated phosphoric acid (93% H3P04), whereupon the mixture foams.
It ls then poured into molds to set.
The ~oamed sulfur prepared ln thls manner has the followlng propertles:
density (g/cm3) o,30 compressive strength (kg/cm3) 12.0 flexural strength (kg/cm3) 7.6 heat conductivlty ( kcal ) 0.09 mhr C
water absorption after 28 days 13.5/48.4 coefficient of impermeability to water520 vapor/u proportion of closed cells (~) 46.
The above combination of properties makes this foamed sulfur a rigid foam which may be used, for example, as an antifreeze ma-terlal for road constructlon.
(b) This test is commenced as in Example (a), but the mixture of sulfur and dlcyclopentadiene ls held at 135C for 360 minutes.
The melt ls so viscous that neither talc nor blowing agent can be incorporated.
1082~50 o.z. ~1,45 (c) This test is commenced as in Example (a), but the mixture is held at 1~5C for, say, only 40 minutes. When the test ls then continued as ln Example (a), a foam is obtalned whlch forms volds prlor to solldirication and usually collapses completely.
Claims (5)
1. A process for the manufacture of foamed sulfur by blending molten sulfur with viscosity-increasing and sta-bilizing compounds, foaming the molten mixture by means of a blowing agent and solidifying the foamed mixture by cooling thereof to temperatures below the melting point of sulfur, wherein dicyclopentadiene is added to the molten sulfur in an amount of 2 to 8% at temperatures of from 120 to 160°C as viscosity increaser, the period of interaction between the sulfur and dicyclopentadiene at the temperature used being restricted by the values of the ordinates in the accompanying figure at the points of intersection between the curves A and D and a straight line parallel to the ordinate axis and inter-secting the abscissa axis at the temperature used.
2. A process as claimed in claim 1, wherein the period of interaction is determined by the points of inter-section between the straight lines and the curves B and C.
3. A process as claimed in claim 1, wherein the mixture contains from 4 to 6% of dicyclopentadiene, by weight of the sulfur.
4. A process as claimed in claim 1, wherein, in a first stage, dicyclopentadiene is added to the molten sulfur and interaction is allowed to continue for a period of at least 80% of the interaction time required at the temperature used and, in a second stage, the stabilizer is added to the resulting mixture and the mixture is foamed within the remainder of the required period of interaction.
5. A process as claimed in claim 4, wherein the first stage is carried out at temperatures of from 130 to 145°C
and the second stage at temperatures of from 120 to 130°C.
and the second stage at temperatures of from 120 to 130°C.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19752534602 DE2534602A1 (en) | 1975-08-02 | 1975-08-02 | Foamed sulphur compsns. as insulants - by foaming in presence of dicyclopentadiene as viscosity-increasing agent |
| DEP2534602.5 | 1975-08-02 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1082850A true CA1082850A (en) | 1980-07-29 |
Family
ID=5953086
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA251,834A Expired CA1082850A (en) | 1975-08-02 | 1976-05-05 | Manufacture of foamed sulfur |
Country Status (2)
| Country | Link |
|---|---|
| CA (1) | CA1082850A (en) |
| DE (1) | DE2534602A1 (en) |
-
1975
- 1975-08-02 DE DE19752534602 patent/DE2534602A1/en not_active Withdrawn
-
1976
- 1976-05-05 CA CA251,834A patent/CA1082850A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| DE2534602A1 (en) | 1977-02-17 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |