JP2008144122A - Modified sulfur and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a modified sulfur material which can be freely controlled with respect to the strength and plasticity, and which is superior in adhesiveness, impact resistance and corrosion resistance, by improving the physical properties of sulfur, and its manufacturing method. <P>SOLUTION: The modified sulfur is obtained by adding a polysulfide polymer to sulfur as a sulfur modifying agent and mutually completely compatibilizing them at a temperature of 120-160°C. Also, the required strength, plasticity and impact resistance of the resultant modified sulfur can be controlled by the kind or a blending ratio of the sulfur modifying agent to be added to the sulfur. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention modifies elemental sulfur to maintain flexibility, plasticity while maintaining strength, corrosion resistance, and abrasion resistance, and as a substitute for plastic, asphalt or cement, paving material, building material, The present invention relates to modified sulfur having properties that can be used for coating materials, waste sealing materials, and the like, and a method for producing the same.

  Sulfur melts at temperatures above 113 ° C, forms a hard solid at room temperature, is insoluble in water and many organic solvents, has low reactivity, and has high corrosion resistance. The use as one of such materials has been tried for a long time. For example, use as a pavement material (Patent Document 1), a binding material for building materials (Patent Document 2) or a binding material for blocking waste (Patent Document 3) is being studied. Such a method of using sulfur is usually in a form in which molten sulfur is used as a binder, and fillers, agglomerates and other substances are hardened and molded. For example, when it is used as a pavement material or a building material, an aggregate of inorganic material such as sand or crushed stone is kneaded with a melt of sulfur as a binder, and then poured into a mold having a desired shape to reach room temperature. It is manufactured by demolding after being left to stand. When used as a binder for waste sealing, the waste is poured into a molten sulfur liquid, poured into a mold, cooled and solidified, and then demolded to completely surround and seal the waste with sulfur. To do.

  However, the use of sulfur as a building material, paving material, or binder has many physical properties issues, especially the high incidence of cavities and cracks on the surface and inside, and the cavities and cracks when subjected to external pressure. It is easy to break along. This is a phenomenon derived from the physical properties of sulfur. When pure sulfur is cooled and solidified from a molten liquid state, there are three types of orthorhombic, monoclinic and amorphous sulfur, and their ratios change depending on the cooling conditions, and the crystal system changes depending on the elapsed time. Since it changes and shrinks, cavities and cracks are likely to occur. Sulfur transitions to orthorhombic sulfur, which is finally the most stable solid state at room temperature, but usually the orthorhombic crystals formed in the process of crystal transition have a large size and shrinkage. Since it exceeds 10%, the strong stress generated at the time of shrinkage causes cracks between the crystals, which lowers the mechanical strength or, in an extreme case, cracks. In addition, the presence of cracks impairs the water impermeability of sulfur, especially when used as a waste sealing binder, water permeates from the cracks on the surface and dissolves the internal waste. The problem of having fallen occurs.

Conventionally, as a technique for improving the defects in the physical properties of sulfur, sulfur is an unsaturated hydrocarbon, mainly cyclopentadiene and its dimer dicyclopentadiene, or one or a mixture of its multimers. By melt-reacting to form modified sulfur, sulfur crystals are suppressed, and flexibility and plasticity are provided. In particular, dicyclopentadiene is known to be inexpensive and excellent in economic efficiency and have a good effect on mechanical strength and the like. (Patent Document 4, Patent Document 5, Patent Document 6)
In addition, examples in which tetrahydroindene, vinyltoluene, dipentene, and other olefin oligomers are added as modifiers to improve the properties of sulfur and are used for paving materials, adhesives, sealing materials, etc. (Patent Document 7, Patent Document 8) are also available. Are known.

U.S. Pat. No. 4,290,816 Japanese Patent Publication No. 55-49024 Japanese Examined Patent Publication No. 62-15274 Japanese Patent Laid-Open No. 53-112922 Japanese Patent Publication No. 2-28529 JP 2003-277108 A Japanese Patent Publication No. 25-25929 JP 2002-60491 A

  However, the reaction of sulfur modifiers such as dicyclopentadiene or tetrahydroindene, vinyltoluene, and dipentene with sulfur is a kind of polymerization reaction. This polymerization reaction is performed in such a manner that the sulfur modifier and sulfur first react and then the sulfur is polymerized by a radical chain reaction. Therefore, the reaction between the sulfur modifier and sulfur causes a rapid temperature increase with a large exotherm, and the viscosity increases rapidly, so that the reaction cannot be controlled, and may be solidified rapidly and cannot be molded. There is. In addition, the modified sulfur obtained by the polymerization reaction has a property that the degree of polymerization increases as the heat polymerization modification reaction time increases, and the viscosity increases accordingly, while maintaining a constant viscosity in the molten state as a binder. It is difficult to mold. On the other hand, all of the above sulfur modifiers are low molecular weight combustible materials, have the property of thermally bonding and dissociating, are easily volatile, flammable, storage facilities, manufacturing facilities and manufacturing There is also a problem in ensuring safety in the process.

  As a result of intensive studies in view of the above circumstances, the present inventor has succeeded in producing a modified sulfur of a type completely different from modified sulfur by adding a polysulfide polymer to sulfur and making them compatible. The sulfur modifier used in the present invention is a high molecular weight polymer material that is stable at room temperature, has no volatility and flammability, and there is no phenomenon in which a rapid temperature rise occurs with a large exotherm in the manufacturing process, There is no change in the modified sulfur viscosity due to fluctuations in the heating reaction time. In other words, compared to conventional modified sulfur, this modified sulfur has more excellent physical properties such as strength, density, impact resistance, flexibility, and plasticity, and also solves manufacturing problems associated with modified sulfur. be able to.

  The sulfur modifier used in the present invention is a polysulfide polymer having a disulfide bond in the main chain and a terminal being a thiol group.

  The modified sulfur of the present invention can be produced by adding the above-described sulfur modifier to sulfur melted by heating and continuing stirring while heating until the sulfur modifier is completely dissolved. Addition of compatibility promoters such as lead dioxide, manganese dioxide, calcium peroxide, zinc peroxide, sodium perborate, etc. in order to promote the compatibility of sulfur modifier with sulfur when heated. By doing so, the heat-compatible time can be shortened.

  In the present invention, a modified sulfur formed by adding a sulfur modifier that becomes a polysulfide polymer to sulfur and dissolving it by heating is dissolved and dispersed in sulfur when cooled and solidified from a molten state. The sulfide polymer interferes with the growth of sulfur crystals, and some sulfur is amorphized and filled between the crystals, so that the solidification shrinkage of sulfur is reduced and a dense crystal can be formed. it can. In addition, cracks formed in the process of shrinkage due to changes in the crystal system after solidification are suppressed in elongation due to the presence of polysulfide polymer, and the modified sulfur has improved strength and plasticity by remaining small. Is something that can be removed. When the solidified and reformed sulfur is subjected to an external impact, it is difficult to form large cracks because the expansion of existing cracks or the formation of new cracks is hindered by the polysulfide polymer dispersed in the sulfur. In addition, due to the presence of polysulfide polymer, the modified sulfur not only has high internal shearing force, but also has high adhesion, strengthens the bond with the filled aggregate and waste, solidification shrinkage, crystal transition Even if a crack occurs in the process or under impact, the phenomenon that sulfur is peeled off from the aggregate and contents hardly occurs. Therefore, the modified sulfur of the present invention has high hardness, certain plasticity, excellent impact resistance, good mechanical strength, and good water barrier properties. The required performance as a construction material can be fully satisfied. Polysulfide polymer as a sulfur modifier is a high-molecular substance, has a high boiling point, is not volatile and flammable, is very stable at room temperature, and has a large exotherm in the manufacturing process. Since there is no phenomenon in which the temperature rises, it is easy to ensure safety in the modified sulfur production facility and production process.

Hereinafter, the present invention will be described in more detail.
The present invention melts and mixes sulfur and a sulfur modifier made of a polysulfide polymer having a disulfide bond in the main chain and a thiol group (-SH group) at the end under specific conditions. It can obtain by cooling from.

  Sulfur used in the present invention is ordinary sulfur, and examples thereof include natural sulfur, sulfur produced by petroleum or natural gas desulfurization. Molten sulfur obtained by heating and melting sulfur at 120 ° C. or higher, preferably 140 to 160 ° C. is used.

The sulfur modifier used in the present invention is a polysulfide polymer having a disulfide bond in the main chain represented by the following structural formula and having a terminal thiol group.
HS- (RSS) _n -R-SH
[R is a linear or branched alkyl group from C ₂ H ₄ to C ₁₂ H _24, or the following structural formula C _x H _2x —O—C _x H _2x
Or _{C x H 2x -O-C y} H 2y -O-C x H 2x
An ether group represented by: x and y are 1 to 3, and n is 1 to 70. ]
The molecular weight of the polysulfide polymer is about 500 to 20000.

The thiol group of the polysulfide polymer as the sulfur modifier of the present invention participates in a binding reaction with sulfur, imparts uniform compatibility with sulfur, and the polysulfide structure has physical properties of sulfur, particularly crystallinity. It is considered that the improved physical properties of the modified sulfur of the present invention are contributed by improving the strength, plasticity, adhesive strength and the like.
The above sulfur modifier is a polysulfide polymer having a molecular weight of 500 to 10,000, a melting point of 100 ° C. or lower, and a decomposition temperature of 250 ° C. or higher from the viewpoint of convenience and safety of work. Is preferred.

The polysulfide polymer as the sulfur modifier of the present invention can be obtained by synthesizing a suitable dimercapto compound by a polymerization reaction. For example, a polyethylene sulfide polymer can be synthesized by polymerizing 1,2-dimercaptoethane in the presence of an appropriate catalyst.
_{nHS-C 2 H 4 -SH -} → HS- (C 2 H 4 -S-S) n-1 -C 2 H 4 -SH
[N is 10-70. ]
This synthesis method is a known method in organic chemistry.

The polysulfide polymer as the sulfur modifier of the present invention can also be obtained commercially. For example, in Japan, Toray Fine Chemical Co., Ltd. sells a polysulfide polymer having the following structural formula under the trade name “Thicol LP”.
HS— (C ₂ H ₄ —O—CH ₂ —O—C ₂ H ₄ —S—S) _n —C ₂ H ₄ —O—CH ₂ —O—C ₂ H ₄ —SH
[N is 5-50. ]
The present invention mainly uses “Thiocol LP” manufactured by Toray Fine Chemical Co., Ltd. as a sulfur modifier.

  The change in the crystal system that occurs when the modified sulfur is cooled and solidified from the molten state is mainly related to the types and blending ratios of sulfur and the sulfur modifier. The effect of the type of sulfur modifier on the modified sulfur is generally that the modification made when R bonded to SS in the main chain of the polysulfide polymer is composed of a linear or branched alkyl group. Sulfur has high hardness and high shearing force, but is slightly inferior in flexibility and adhesive strength. The modified sulfur produced when R is composed of an ether group, on the contrary, has high flexibility and adhesive strength, and is somewhat inferior in hardness and shearing force. In addition, when the molecular weight of the sulfur modifier is small, it is easy to be compatible with sulfur, so that the production time can be shortened, but the shear force of the produced modified sulfur is low. The reverse is true when the molecular weight of the sulfur modifier is high.

In addition, regarding the blending ratio of the sulfur modifier, normally, as the blending ratio of the sulfur modifier increases, the size of the obtained modified sulfur crystals decreases, and amorphous sulfur also increases. When the sulfur modifier is 0.5 parts by weight or less with respect to 100 parts by weight of sulfur, the effect of improving the physical properties of sulfur such as strength and plasticity is hardly seen, and when the sulfur modifier exceeds 30 parts by weight When the obtained modified sulfur is cooled and solidified, the formation of sulfur crystals is completely suppressed, all become amorphous and exhibit rubber-like flexibility. In addition, when the compounding ratio of the sulfur modifier increases, the melt viscosity of the formed modified sulfur increases and the adhesive strength also increases, but the hardness and mechanical strength after solidification decrease. Usually, the blending ratio of the sulfur modifier with respect to 100 parts of sulfur is preferably 0.5 to 30 parts, more preferably 1 to 15 parts, and particularly preferably 1 to 10 parts.
Therefore, by appropriately selecting the type and blending ratio of sulfur modifiers added to sulfur, the required hardness, mechanical strength, plasticity, impact resistance, adhesive strength as materials for civil engineering, construction, etc. It is possible to obtain modified sulfur satisfying the water shielding property.

  In addition, the compatibility between sulfur and the sulfur modifier strongly depends on the heating temperature and time. Orthorhombic sulfur, which is often present in nature, melts at 112.8 ° C, but when the heating temperature is 120 ° C or lower, it takes several tens of hours to completely dissolve sulfur and the sulfur modifier. Take it. When the heating temperature exceeds 160 ° C., the viscosity of the molten sulfur increases rapidly, and although the compatibility with the sulfur modifier does not increase, stirring becomes difficult and work efficiency decreases. In addition, when the heating temperature exceeds the decomposition temperature of the sulfur modifier, the sulfur modifier is decomposed and the sulfur reforming effect cannot be obtained. Therefore, in the process for producing modified sulfur, the temperature at which sulfur and the sulfur modifier are heated and compatible is preferably 120 to 160 ° C, particularly preferably 140 to 160 ° C.

When using a sulfur modifier with a high molecular weight or a high proportion of sulfur modifier in the modified sulfur production process, it takes time to completely dissolve both sulfur and the sulfur modifier. . In this case, in order to promote the compatibility between sulfur and the sulfur modifier, a compatibility accelerator can be added to shorten the heating compatibility time.
Lead dioxide, manganese dioxide, calcium peroxide, zinc peroxide, sodium perborate and the like can be used as a compatibility accelerator. These compatibilizers are a kind of oxidizer, which oxidizes thiol groups (-SH groups) of polysulfide polymers to form sulfur bonds with sulfur molecules, thereby compatibilizing both sulfur and sulfur modifiers. Promote. Moreover, it is also conceivable that a part of the polysulfide polymer is polymerized by the compatibility accelerator through SS bonding to improve the physical properties of the modified sulfur. The addition amount of the compatibility accelerator is 2 to 10 parts per 100 parts of the sulfur modifier.

  Next, the present invention will be described more specifically based on examples, but the present invention is not limited to these examples. In the examples, “parts” means parts by weight.

  1 part of “Thiocol LP33” (Toray Fine Chemical Co., Ltd.) is added to 99 parts of sulfur melted at 150 ° C. and stirred for 5 hours while maintaining at 150 ° C. to form modified sulfur. This modified sulfur has a viscosity at 150 ° C. of 20 millipascal-seconds. The average molecular weight of “Thiocol LP33” is 1000.

  To 95 parts of sulfur melted at 150 ° C., 5 parts of “Thiocol LP33” (Toray Fine Chemical Co., Ltd.) is added and stirred for 8 hours while maintaining at 150 ° C. to form modified sulfur. This modified sulfur has a viscosity at 150 ° C. of 85 millipascal-seconds.

  10 parts of “Thiocol LP32” (Toray Fine Chemical Co., Ltd.) is added to 90 parts of sulfur melted at 150 ° C., and stirring is continued for 10 hours while maintaining the temperature at 150 ° C. to form modified sulfur. This modified sulfur has a viscosity at 150 ° C. of 540 mPa · s. The average molecular weight of “Thiocol LP32” is 4000.

  To 90 parts of sulfur melted at 150 ° C., 10 parts of “Thiocol LP32” (Toray Fine Chemical Co., Ltd.) and 1 part of lead dioxide are added and stirred for 6 hours while maintaining at 150 ° C. to form modified sulfur. This modified sulfur has a viscosity at 150 ° C. of 560 millipascal-seconds.

Comparative example

  Sulfur is melted at 150 ° C., and the viscosity at that time is 9 millipascal-seconds.

For the modified sulfur of Examples 1 to 4 and the sulfur of the comparative example, compression hardness, impact strength, and flexibility were measured as indicators of changes in physical properties before and after the sulfur modification.
The compression hardness test means that the modified sulfur of Examples 1 to 4 and the sulfur of the comparative example are dripped into a water tank (water temperature 25 ° C.) from a nozzle in a molten state at 150 ° C. to produce spherical sulfur particles having a diameter of 2 mm to 3 mm. After solidifying, the sulfur particles are taken out and placed at 25 ° C. for 7 days. After the sulfur crystal system is completely stabilized, 20 particles are arbitrarily selected until the spherical sulfur particles are broken using a Kiyama hardness tester. The applied pressure (kg) is measured.

  In the impact strength test, the modified sulfur of Examples 1 to 4 and the sulfur of the comparative example were poured into a mold in a molten state to produce 10 sulfur disk samples each having a diameter of 35 mm and a thickness of 3 mm. Place it at room temperature for 7 days, and after the sulfur crystal system is completely stabilized, place the disk sample on a horizontal stainless steel table and let the 20g heavy steel ball fall freely vertically from 1m or 2m in height. It is observed whether the plate sample is cracked after being hit with a steel ball.

  With the flexibility test, the modified sulfur of Examples 1 to 4 and the sulfur of the comparative example were poured into a mold in a molten state to produce 10 plate samples each having a length of 200 mm, a width of 20 mm, and a thickness of 3 mm. After solidification, place at 25 ° C for 7 days at room temperature, and after the sulfur crystal system is completely stabilized, place the plate sample in a horizontal state, fix one end, slowly add weight to the other end, until the plate sample breaks The distance from the horizontal to the end is measured as the amount of displacement.

Table 1 shows the results of the compression hardness test, impact strength test, and flexibility test. The compressive hardness and flexible displacement shown in the table are average values of the measurement results.

  Regarding the pressure required for the collapse of the modified sulfur particles due to compression, the comparative example is 0.5 kg, the example 1 is 2.5 kg, the examples 2, 3, and 4 are more than 3 kg. 7 times higher. This indicates that the compression hardness is remarkably improved by the formation of a dense crystal body with few cracks by the modified sulfur.

  As for impact strength, when the drop distance of the steel ball was 1 m, all the samples were cracked in the comparative example, whereas in Examples 1, 2, 3 and 4, the samples were not cracked at all. Even when the drop distance of the steel ball was 2 m, all the samples were cracked in Example 1, but were not cracked in Examples 2, 3, and 4 at all. This indicates that the strength of the polysulfide polymer dissolved and dispersed in the modified sulfur was increased by preventing the formation and expansion of cracks upon impact.

  Regarding the flexibility, in the comparative example, the displacement amount until the sulfur plate sample is broken is only 2 mm, whereas the modified sulfur is 5 mm in Example 1 and is excellent in Examples 2, 3 and 4. It exceeded 10 mm. The amount of displacement increases as the amount of the added sulfur modifier increases. Although not shown in Table 1, modified sulfur obtained by adding 30 parts of sulfur modifier to 70 parts of sulfur is like rubber. It is flexible and cannot be easily folded. This suggested that the polysulfide polymer dissolved and dispersed in the modified sulfur greatly imparted plasticity and flexibility to the sulfur.

  The modified sulfur of the present invention has excellent strength, density, impact resistance, flexibility, plasticity, adhesiveness, corrosion resistance and other physical properties, and is used as a road pavement and construction material as a substitute for plastic, asphalt or cement. It can be used for a wide range of applications such as a bonding material for materials, an adhesive, a bonding seal material, a water-resistant seal material, and a coating material.

Claims (6)

  Modified sulfur obtained by completely compatibilizing sulfur and a sulfur modifier comprising a polysulfide polymer. The sulfur modifier described in claim 1 is a polysulfide polymer having a disulfide bond in the main chain represented by the following structural formula and having a terminal thiol group.
HS- (RSS) _n -R-SH
[R is a linear or branched alkyl group from C ₂ H ₄ to C ₁₂ H _24, or the following structural formula C _x H _2x —O—C _x H _2x
Or _{C x H 2x -O-C y} H 2y -O-C x H 2x
And x and y are 1 to 3, and n is 1 to 50. ]   It is described in Claim 1 obtained by heat-mixing 0.5-30 weight part of sulfur modifiers described in Claim 2 with 99.5-70 weight part of sulfur. Modified sulfur and method for producing the same.   The method for producing reformed sulfur according to claim 3, wherein the heating compatibility temperature of the sulfur modifier and sulfur is in the range of 120C to 160C.   The method for producing modified sulfur according to claim 3, wherein a compatibility accelerator can be added in order to promote the compatibility of the sulfur modifier and sulfur when heated.   The compatibility promoter described in claim 5 is lead dioxide, manganese dioxide, calcium peroxide, zinc peroxide, sodium perborate.