Method for producing chloroprene and method for producing chloroprene rubber

Abstract

[Problem] To provide: a method for producing waste-derived chloroprene that can be used as a raw material for synthetic rubber, while reducing the environmental burden thereof; and a method for producing chloroprene rubber. [Solution] One aspect of the present invention provides a method for producing chloroprene, said method comprising: a preparation step for preparing a fixed carbon source that contains a waste combustion residue; a generation step for generating a chloroprene precursor from the fixed carbon source; and a conversion step for converting the chloroprene precursor into chloroprene.

Description

Method for producing chloroprene and method for producing chloroprene rubber

[0001] This invention relates to a method for producing chloroprene and a method for producing chloroprene rubber.

[0002] For example, polyethylene and polyvinyl chloride, representative petrochemical products, are consumed in large quantities and then discarded. These waste products are a major contributor to environmental pollution. Furthermore, the mass production of petrochemical products creates a global environmental problem by increasing carbon dioxide in the atmosphere. To solve this problem, if waste that was previously discarded can be converted into chemical products, it will be possible to realize a resource-recycling society that does not rely on petroleum resources. From this perspective, a technology has been disclosed for producing synthesis gas from waste and then producing organic substances from that synthesis gas by fermentation (see Patent Document 1). Currently, there is a demand for the development of waste-derived compounds that can be used as raw materials for synthetic rubber.

[0003] Special Publication No. 2024-531893

[0004] In view of the above circumstances, the present invention aims to provide a method for producing chloroprene derived from waste materials that can be used as a raw material for synthetic rubber, and a method for producing chloroprene rubber, while reducing the burden on the environment.

[0005] According to one aspect of the present invention, a method for producing chloroprene is provided, comprising a preparation step of preparing a fixed carbon source containing combustion residue of waste, a production step of generating a chloroprene precursor from the fixed carbon source, and a conversion step of converting the chloroprene precursor into chloroprene.

[0006] According to this embodiment, it is possible to provide waste-derived chloroprene that can be used as a raw material for synthetic rubber while reducing the burden on the environment.

[0007] Embodiments of methods for producing chloroprene and chloroprene rubber are described below. The various features shown in the embodiments below can be combined with each other. In this specification, the content of Y in X means the proportion of Y in the total X. In this specification, "waste" may include any material to be reused or processed. That is, waste is used as a concept that includes used material, unused material, virgin material, and recycled material. Furthermore, in this specification, "combustion" includes a process in which waste is reacted in the presence of oxygen, but does not necessarily mean complete combustion, and is a concept that includes incomplete combustion or partial oxidation reactions carried out under conditions where the amount of oxygen supply or reaction conditions are limited. The combustion residue obtained by such a process may include solid residue containing fixed carbon. That is, combustion residue is used as a concept that includes residue obtained by a process including carbonization or thermal decomposition.

[0008] <Method for Producing Chloroprene> The method for producing chloroprene (2-chloro-1,3-butadiene) according to this embodiment includes a preparation step of preparing a fixed carbon source containing combustion residue of waste, a production step of generating a chloroprene precursor from the fixed carbon source, and a conversion step of converting the chloroprene precursor into chloroprene. By using the chloroprene obtained by this method, it is possible to manufacture synthetic rubber (chloroprene rubber) while reducing the burden on the environment. Therefore, it can contribute to the realization of a carbon-recycling society. The following describes each step.

[0009] <<Preparation Process>> First, a fixed carbon source containing combustion residue from waste is prepared. After pre-treatment such as crushing and drying of the waste, a carbonized material corresponding to the combustion residue in this specification is obtained by carbonizing it for about one hour at a temperature of approximately 400°C to 1000°C, under a low-oxygen atmosphere (oxygen concentration of approximately 10% by volume or less), or under an inert gas atmosphere such as nitrogen or argon, using a rotary kiln, fluidized bed furnace, or high-temperature vacuum atmosphere furnace. In such treatment under low-oxygen conditions, some components in the waste undergo an oxidation reaction, while a considerable portion of the carbon component remains unoxidized as a solid. Here, it is preferable that the waste contains at least one of waste plastics, waste rubber, and waste carbon fibers. By utilizing such waste, which is a major cause of environmental pollution, it is easier to realize a resource recycling society that does not rely on petroleum resources.

[0010] The waste plastic is preferably at least one selected from the group consisting of, for example, polyethylene, polystyrene, polypropylene, polyvinyl chloride, phenolic resin, polyacetal, polycarbonate, polyamide, modified polyphenylene ether, polyetherether ketone, polyethersulfone, polyetherimide, polyphenylene sulfide, polysulfone, liquid crystal polymer, polyethylene terephthalate, and polybutylene terephthalate.

[0011] The waste rubber is preferably at least one selected from the group consisting of, for example, natural rubber, styrene-butadiene rubber, butadiene rubber, isoprene rubber, butyl rubber, acrylonitrile-butadiene rubber, chloroprene rubber, ethylene-propylene rubber, acrylic rubber, fluororubber, silicone rubber, urethane rubber, and epichlorohydrin rubber. The waste may further include at least one of glass and silica sand.

[0012] Furthermore, if the combustion residue contains metal, it is preferable to separate the metal from the combustion residue by crushing, sieving, or magnetic force. Also, if polyvinyl chloride, chloroprene rubber, etc., are used as waste, the combustion residue may contain unwanted components such as chlorine. In this case, it is preferable to remove the chlorine from the combustion residue by washing the waste with water before and / or after the carbonization treatment. In addition, if necessary, the powdered combustion residue may be granulated to a certain size before use.

[0013] The fixed carbon source may contain carbon atoms derived from the combustion residue of waste, and at least one of phosphorus atoms and sulfur atoms. In this case, it is preferable that the phosphorus atom content is about 1% by mass or less, and the sulfur atom content is about 5% by mass or less. By reducing the phosphorus atom content and sulfur atom content in this way, the amount of phosphine and hydrogen sulfide generated when producing organic substances (acetylene, acetylene derivatives, polymers, etc.) can be reduced. In particular, reducing the sulfur atom content can reduce the amount of sulfur oxide (SOx) generated, which can prevent corrosion of components constituting the organic substance production system and adverse effects on the synthesis catalyst of organic substances (monomer compounds and polymers).

[0014] Here, phosphorus-based substances containing phosphorus atoms in a fixed carbon source include, for example, elemental phosphorus, phosphine, phosphorus oxides, phosphorus-based plasticizers, phosphorus-based flame retardants, and phosphorus pentoxide (P ２ O ５Examples include the following. Furthermore, sulfur-based substances containing sulfur atoms in the fixed carbon source include, for example, elemental sulfur, hydrogen sulfide, sulfur oxides, factis, polysulfurized rubber, naphthenic oil, sulfur-modified chloroprene rubber, and various additives such as vulcanization accelerators containing sulfur atoms in their structure. The phosphorus atom content is preferably about 0.1% by mass or less, more preferably about 0.05% by mass or less, and even more preferably about 0.01% by mass or less. On the other hand, the sulfur atom content is preferably about 0.5% by mass or less, more preferably about 0.05% by mass or less, and even more preferably about 0.005% by mass or less. By setting the phosphorus atom content and sulfur atom content within these ranges, the above effects can be further improved.

[0015] From a safety standpoint, it is preferable that the phosphorus and sulfur atom content in the fixed carbon source be as low as possible. However, by leaving a small amount of phosphorus (phosphorus-based substances) and sulfur (sulfur-based substances) in the fixed carbon source, a small amount of, for example, phosphine and hydrogen sulfide will remain in the acetylene and monomer compounds obtained using the fixed carbon source. For example, the phosphine and hydrogen sulfide contained in the acetylene will react with oxygen, consuming the oxygen, thus suppressing the mixing of acetylene and oxygen, and thus the safety of the acetylene is less likely to be compromised. In addition, because the oxygen content in the acetylene is low, a decrease in the yield of the monomer compound obtained from acetylene, and consequently the yield of the polymer, can be prevented or suppressed. Furthermore, acetylene containing phosphine and hydrogen sulfide will have a slight odor, so even if acetylene leaks, it can be detected, thus providing high safety from this standpoint as well.

[0016] In this case, the phosphorus atom content in the fixed carbon source is preferably about 0.1 ppm (0.00001 mass%) or more, more preferably about 1 ppm (0.0001 mass%) or more, and even more preferably about 10 ppm (0.001 mass%) or more. The phosphorus atom content in the fixed carbon source can be, for example, 0.1 ppm to 1 mass% or less. On the other hand, the sulfur atom content in the fixed carbon source is preferably about 0.1 ppm (0.00001 mass%) or more, more preferably about 1 ppm (0.0001 mass%) or more, and even more preferably about 10 ppm (0.001 mass%) or more. The sulfur atom content in the fixed carbon source can be, for example, 0.1 ppm to 5 mass% or less. By setting the phosphorus atom content and sulfur atom content within these ranges, the above effects can be further improved.

[0017] Furthermore, the nitrogen atom content in the fixed carbon source is preferably about 20% by mass or less, more preferably about 10% by mass or less, and even more preferably about 5% by mass or less. By reducing the nitrogen atom content, the amount of nitrogen oxides generated can be reduced, and corrosion of components constituting the organic substance manufacturing system and adverse effects on the organic substance synthesis catalyst can be prevented. The phosphorus, sulfur, and nitrogen atom content in the fixed carbon source can be measured in accordance with JIS M 8813:2004. In addition, the content of various atoms in the fixed carbon source can be determined, for example, by selecting the type of waste, setting its combination and mixing ratio, and by using phosphorus-based plasticizers, phosphorus-based flame retardants, and phosphorus pentoxide (P). ２ O ５ ), can be adjusted by adding additives containing sulfur atoms in the structure, or additives containing nitrogen atoms in the structure. In other words, the various atoms may be present in the waste or added later.

[0018] Furthermore, it is preferable that the fixed carbon source does not contain ash, or if it does, the amount of ash is small. Here, as ash, for example, silicon dioxide (SiO₂) ２ ), rare earth oxides (R ２ O ３), calcium oxide (CaO), magnesium oxide (MgO), sulfur oxide (SO ３ Examples include the following. When acetylene is produced, for example, these ashes are reduced in the heating furnace, reducing the efficiency and quality of acetylene production. Specifically, when magnesium oxide is reduced in the heating furnace, it becomes elemental magnesium, which volatilizes and rises to the top of the heating furnace, oxidizes back to magnesium oxide when exposed to air, and descends to the bottom of the heating furnace to be reduced again. Because this oxidation and reduction is repeated, electricity is consumed unnecessarily. In addition, carbon is consumed unnecessarily during the reduction of magnesium oxide. Examples of heating furnaces include electric furnaces such as resistance furnaces, induction furnaces, and arc furnaces, as well as combustion furnaces such as gas combustion furnaces, heavy oil combustion furnaces, rotary kilns, shaft furnaces, and muffle furnaces.

[0019] Similarly, silicon dioxide wastes electricity when reduced, as the elemental silicon produced volatilizes and oxidizes. Furthermore, some silicon dioxide reacts with carbon to produce silicon carbide. Silicon carbide is a crystalline form known as carborundum, which has a high melting point and is extremely hard. Therefore, if silicon carbide accumulates in the heating furnace, it can eventually clog the furnace and render it inoperable. To avoid this, the ash content in the fixed carbon source is preferably around 30% by mass or less, more preferably around 20% by mass or less, and even more preferably around 7% by mass or less. The ash content in the fixed carbon source can be measured according to JIS M 8812:2006. The ash content in the fixed carbon source can also be adjusted, for example, by selecting the type of waste, setting its combination and mixing ratio, or by using additives containing one or more of the following atoms in their structure: silicon, rare earth, calcium, magnesium, or sulfur. In other words, ash may be present in the waste or added later.

[0020] The fixed carbon source is preferably such that the crushing strength of a sample molded to a size of 35 mm x 35 mm x 10 mm is 10 kgf or more, more preferably 20 kgf or more, even more preferably 30 kgf or more, and particularly preferably 40 kgf or more, as measured according to JIS Z 8841:1993. The upper limit of the crushing strength of the sample is not particularly limited, but is approximately 60 kgf. The crushing strength of the sample can be, for example, between 10 kgf and 60 kgf. This makes it easier to handle the fixed carbon source when producing organic substances such as acetylene.

[0021] Furthermore, the fixed carbon source preferably has a volatile content of 5% by mass or less, more preferably around 4% by mass or less, and even more preferably around 3% by mass or less, as measured according to JIS M 8812:2006. The lower limit of the volatile content of the fixed carbon source is not particularly limited, but is approximately 0.01% by mass. The volatile content of the fixed carbon source can be, for example, 0.01% by mass or more and 5% by mass or less. This effectively prevents the fixed carbon source from burning during storage, etc.

[0022] The fixed carbon source preferably contains 70% or more carbon atoms derived from the combustion residue of waste, more preferably 80% or more, even more preferably 90% or more, particularly preferably 95% or more, and may even be substantially 100% by mass. By using a fixed carbon source with a high content of carbon atoms derived from the combustion residue of waste in this way, it is easier to produce high-purity organic substances (e.g., acetylene, chloroprene, etc.). Furthermore, by setting the content of carbon atoms derived from the combustion residue of waste in the fixed carbon source within the above range, it becomes easier to realize a resource-recycling society that does not rely on petroleum resources.

[0023] <<Production Process>> Next, a chloroprene precursor is produced from the obtained fixed carbon source. In the production process of the present embodiment, after obtaining metal carbide by heating a fixed carbon source and a metal source in a heating furnace, acetylene is obtained as a chloroprene precursor by reacting the metal carbide with water. By using a fixed carbon source capable of forming a sample having the crushing strength as described above, it is possible to suitably prevent collapse during its charging or in the heating furnace.

[0024] On the other hand, examples of the metal source include oxides of alkaline earth metals, carbonates of alkaline earth metals, hydroxides of alkaline earth metals, sulfates of alkaline earth metals, chlorides of alkaline earth metals, and the like. These metal sources may be used alone or in combination of two or more. The metal source preferably contains an oxide or carbonate of an alkaline earth metal (for example, calcium oxide, barium oxide, or barium carbonate), and more preferably contains calcium oxide. Calcium oxide (CaO) is an unstable substance obtained by, for example, thermally decomposing calcium carbonate (CaCO ３ ) at about 900°C. Therefore, calcium oxide is suitable as a metal source because of its high reactivity. Suitable metal carbides include calcium carbide (calcium carbide), barium carbide (barium carbide), and magnesium carbide (magnesium carbide).

[0025] Next, a mixture of the fixed carbon source and the metal source is placed in a heating furnace and heated. Thereby, the fixed carbon source and the metal source are reacted to obtain metal carbide. The heating temperature is not particularly limited, but is preferably about 1700°C or higher and 2200°C or lower, and more preferably about 1900°C or higher and 2100°C or lower. The heating time is also not particularly limited, but when the above heating temperature is used, it is preferably about 2 minutes or more and 3 hours or less, and more preferably about 30 minutes or more and 1.5 hours or less. By heating under such heating conditions, the reaction between the fixed carbon source and the metal source can proceed sufficiently.

[0026] The heating atmosphere is preferably an inert gas atmosphere such as an argon gas atmosphere. This prevents the rapid combustion (consumption) of the fixed carbon source and the unwanted combustion of carbon monoxide and hydrogen generated during the reaction between the fixed carbon source and the metal source. The amount of the fixed carbon source is preferably 30 to 400 parts by mass, more preferably 50 to 300 parts by mass, and even more preferably 70 to 200 parts by mass, per 100 parts by mass of the metal source. By reacting in such a ratio, the yield of metal carbide can be sufficiently increased. The fixed carbon source and the metal source are preferably in particulate form. This increases the contact area between the fixed carbon source and the metal source, thereby improving their reaction efficiency.

[0027] The average particle diameter of the fixed carbon source is not particularly limited, but is preferably about 8 mm to 50 mm, more preferably about 8 mm to 30 mm, and even more preferably about 8 mm to 10 mm. Similarly, the average particle diameter of the metal source is not particularly limited, but is preferably about 8 mm to 50 mm, more preferably about 8 mm to 30 mm, and even more preferably about 8 mm to 10 mm. In this specification, the average particle diameter refers to the particle diameter (D50) when the cumulative value in the volume-based cumulative particle size distribution obtained by laser diffraction scattering reaches 50%. The laser diffraction scattering method is measured in accordance with the method described in JIS Z 8825:2013 "Particle size analysis - Laser diffraction and scattering method".

[0028] Prior to the main heating described above, preheating may be performed by heating the mixture at a temperature lower than the main heating temperature. By performing such preheating, the amount of fixed carbon source consumed during the main heating can be reduced, and the yield of metal carbide can be further increased. Examples of fuel for preheating include the gas emitted during the main heating (a mixture of carbon monoxide and hydrogen). By using this gas as fuel for preheating, energy can be effectively utilized while effectively preventing air pollution.

[0029] Furthermore, the heating process may include recovering the gas containing at least carbon monoxide and hydrogen generated in the heating furnace. That is, the method for producing chloroprene may further include a recovery step for recovering a gas containing at least one of carbon monoxide and hydrogen. The recovered carbon monoxide and hydrogen may be used, for example, as an energy source when converting calcium carbonate to calcium oxide, or when converting metal carbide to acetylene, and may be used to convert carbon compounds. In the latter case, the method for producing chloroprene may further include a reaction step of reacting at least carbon monoxide and hydrogen to obtain a carbon compound. This makes it possible to effectively utilize the gas generated in the metal carbide manufacturing process. Examples of such carbon compounds include acrylic acid, olefins (jet fuel), and acetylene black.

[0030] Next, the metal carbide is reacted with water. This yields acetylene (chloroprene precursor). The amount of water added is preferably 2 moles to 10 moles per mole of metal carbide, and more preferably 2.5 moles to 5 moles. This allows the reaction between the metal carbide and water to proceed sufficiently. The holding temperature during the reaction between the metal carbide and water is preferably 80°C to 200°C, and more preferably 100°C to 180°C. By maintaining the reaction temperature within this range, the vaporization of water is effectively prevented, allowing the reaction with the metal carbide to proceed sufficiently.

[0031] The metal carbide may be in block form, but it is preferable that it be in particulate form. By using particulate metal carbide, the contact area with water can be increased. As a result, the reaction between the metal carbide and water can proceed without excess or deficiency. In this case, the average particle size of the metal carbide is not particularly limited, but it is preferably between 1 mm and 150 mm, and more preferably between 5 mm and 120 mm. In this case, the above effect can be further improved.

[0032] Furthermore, for the water used, for example, tap water, distilled water, deionized water, pure water, ultrapure water, RO water, etc., can be used. Since the reaction between the metal carbide and water described above is an exothermic reaction, the generated heat may be recovered and used for the reaction between the fixed carbon source and the metal source as described above. In addition, the slaked lime (calcium hydroxide) produced when calcium carbide is used as the metal carbide can be suitably used, for example, as a cement admixture. By going through the above steps, acetylene with sufficiently low phosphine and hydrogen sulfide content can be obtained as described above.

[0033] <<Conversion Step>> Next, acetylene (chloroprene precursor) is converted to chloroprene. In the conversion step of this embodiment, monovinylacetylene (MVA) is obtained by a dimerization reaction of acetylene, and then chloroprene is obtained by a reaction of monovinylacetylene with hydrogen chloride. The dimerization reaction (vinylization reaction) of acetylene is usually carried out by continuously supplying acetylene gas at a predetermined rate to a predetermined amount of Nieuwland catalyst solution (hydrochloric acid aqueous solution of cuprous chloride and ammonium chloride). The reaction temperature is preferably 65°C to 90°C (specifically, about 72°C). Since the reaction rate is 5% or less, after the reaction is complete, monovinylacetylene is separated from acetylene by utilizing the difference in boiling points between monovinylacetylene and acetylene.

[0034] Next, monovinylacetylene is reacted with hydrogen chloride to obtain chloroprene. The chlorination reaction of monovinylacetylene is usually carried out in a toluene / water two-phase system by mixing a toluene solution containing monovinylacetylene with a Nieuwland catalyst solution containing hydrogen chloride. The reaction temperature is preferably between 30°C and 50°C (specifically around 40°C). The reaction time is preferably between 30 minutes and 3 hours (specifically around 1 hour). The reaction pressure is preferably atmospheric pressure.

[0035] <Other methods for producing chloroprene> Chloroprene can also be obtained by generating butadiene (chloroprene precursor) from a fixed carbon source as described above in the production step, and then converting it to chloroprene in the conversion step by chlorination followed by dehydrochlorination of butadiene. Butadiene can be obtained by a combination of known techniques, for example, via alcohols (ethanol, butanol). Butadiene can also be obtained, for example, by adding water to acetylene as described above to synthesize acetaldehyde, dimerizing it by aldol addition to 3-hydroxybutanal, and then 1,3-butylene glycol, followed by dehydration (the so-called BUNA four-step method). Next, butadiene is chlorinated by a reaction of butadiene with chlorine to obtain a mixture containing 1,4-dichloro-2-butene and 3,4-dichloro-1-butene.

[0036] Subsequently, by heating this mixture in the presence of a catalyst, 1,4-dichloro-2-butene is isomerized to 3,4-dichloro-1-butene. Next, chloroprene is obtained by dehydrochlorination of 3,4-dichloro-1-butene in an alkaline solution in the presence of a polymerization inhibitor. The resulting chloroprene is purified, for example, by distillation, to obtain high-purity chloroprene.

[0037] <Method for Manufacturing Chloroprene Rubber> The method for manufacturing chloroprene rubber according to this embodiment comprises a monomer acquisition step of obtaining chloroprene as a monomer compound by the above manufacturing method, and a polymerization step of obtaining chloroprene rubber by polymerizing chloroprene (chloroprene monomer). From chloroprene, chloroprene rubber (chloroprene polymer) is usually obtained by polymerization by radical emulsion polymerization. For example, rosinate soap is used as an emulsifier and persulfate is used as a catalyst in this polymerization. The basic properties of chloroprene rubber can be adjusted by the polymerization temperature and molecular weight adjusting agent. By using chloroprene rubber obtained by such a manufacturing method, it is possible to reduce the burden on the environment and contribute to the realization of a carbon-recycling society.

[0038] Chloroprene rubber may be a homopolymer of chloroprene or a copolymer of chloroprene and a monomer copolymerizable with the chloroprene. Examples of monomers copolymerizable with chloroprene include methacrylic acid or its esters, acrylic acid or its esters, 2,3-dichloro-1,3-butadiene, 1-chloro-1,3-butadiene, isoprene, ethylene, styrene, acrylonitrile, and the like. These monomers may be used alone or in combination of two or more. Further, the chloroprene rubber may be a modified product of the above homopolymer or copolymer. Examples thereof include sulfur-modified chloroprene rubber, mercaptan-modified chloroprene rubber, xanthogen-modified chloroprene rubber, dithiocarbonate-based chloroprene rubber, tricarbonate-based chloroprene rubber, carbamate-based chloroprene rubber, and the like. Furthermore, it may be provided in each of the aspects described below.

[0039] (1) A method for producing chloroprene, comprising a preparation step of preparing a fixed carbon source containing combustion residue of waste, a generation step of generating a chloroprene precursor from the fixed carbon source, and a conversion step of converting the chloroprene precursor into the chloroprene.

[0040] (2) The method for producing chloroprene according to (1) above, wherein in the generation step, after obtaining metal carbide by heating the fixed carbon source and a metal source in a heating furnace, acetylene is obtained as the chloroprene precursor by reacting the metal carbide with water.

[0041] (3) The method for producing chloroprene according to (2) above, wherein in the conversion step, after obtaining monovinylacetylene by dimerization reaction of the acetylene, the chloroprene is obtained by reacting the monovinylacetylene with hydrogen chloride.

[0042] (4) In the method for producing chloroprene according to any one of (1) to (3) above, the fixed carbon source contains carbon atoms derived from the combustion residue of the waste and at least one of a phosphorus atom and a sulfur atom, the content of the phosphorus atom is 1% by mass or less, and the content of the sulfur atom is 5% by mass or less. A method for producing chloroprene.

[0043] (5) In the method for producing chloroprene according to (4) above, the content of the phosphorus atom in the fixed carbon source is 0.1 ppm or more, and the content of the sulfur atom is 0.1 ppm or more. A method for producing chloroprene.

[0044] (6) In the method for producing chloroprene according to (4) or (5) above, the crushing strength measured according to JIS Z 8841:1993 of a sample obtained by shaping the fixed carbon source into a size of 35 mm × 35 mm × 10 mm is 10 kgf or more. A method for producing chloroprene.

[0045] (7) In the method for producing chloroprene according to any one of (4) to (6) above, the fixed carbon source has a volatile content of 5% by mass or less measured according to JIS M 8812:2006. A method for producing chloroprene.

[0046] (8) In the method for producing chloroprene according to any one of (4) to (7) above, the content of the carbon atoms in the fixed carbon source is 70% by mass or more. A method for producing chloroprene.

[0047] (9) In the method for producing chloroprene according to any one of (1) to (8) above, further comprising a recovery step of recovering a gas containing at least one of carbon monoxide and hydrogen. A method for producing chloroprene.

[0048] (10) In the method for producing chloroprene according to (9) above, further comprising a reaction step of reacting at least the carbon monoxide and the hydrogen to obtain a carbon compound. A method for producing chloroprene.

[0049] (11) A method for producing chloroprene rubber, comprising a monomer acquisition step of obtaining chloroprene as a monomer compound by the method for producing chloroprene described in any one of (1) to (10) above, and a polymerization step of obtaining chloroprene rubber by polymerizing the chloroprene. Of course, this is not limited to this method.

[0050] Finally, while various embodiments relating to this disclosure have been described, these are presented as examples only and are not intended to limit the scope of the invention. These novel embodiments can be implemented in a variety of other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims and their equivalents.

[0051] The following describes in more detail the methods for producing chloroprene and chloroprene rubber, using the following examples and comparative examples, but these are not limited to the following examples.

[0052] 1. Preparation of raw materials <Steady carbon sources> <<Steady carbon sources A to M>> First, 1 kg of waste containing at least one of waste plastic and waste rubber (see Table 1 below) was crushed and then pre-treated by drying. After that, carbonization treatment was carried out at approximately 1000°C under a nitrogen atmosphere for 1 hour using a high-temperature vacuum atmosphere furnace (Hirochiku Co., Ltd., "CVF-2030"). This yielded sitid carbon sources A to M containing combustion residue of the waste. The sitid carbon sources A to M were then crushed and separated using a sieve so that the average particle size was approximately 10 mm before use.

[0053] <<Stable Carbon Sources N-P>> First, 1 kg of waste plastic (see Table 1 below) was melted and poured into a 10 cm x 10 cm x 10 cm mold, followed by cooling and drying as a pretreatment. Then, stable carbon sources N-P were obtained by carbonization treatment similar to that of stable carbon sources A-N. Stabilized carbon sources N-P were crushed and separated using a sieve so that the average particle size was approximately 10 mm.

[0054] <<Steady Carbon Source Q>> Coke was prepared as the sitdy carbon source Q. This coke was crushed and separated using a sieve so that the average particle size was about 10 mm. <Calcium Source (Metal Source)> Calcium oxide (manufactured by Denka Co., Ltd.) with an average particle size of 10 mm was prepared.

[0055] 2. Production of calcium carbide (metal carbide), acetylene, monovinylacetylene, and chloroprene monomer (Example 1) First, a mixture was obtained by mixing 100 parts by mass of a fixed carbon source A with 195 parts by mass of calcium oxide as a calcium source. Next, this mixture was placed in a high-temperature vacuum atmosphere furnace (Hirochiku Co., Ltd., "CVF-2030") and heated at 2000°C for 30 minutes while flowing argon at a rate of 7 L / hr. This obtained calcium carbide. The average particle size of the obtained calcium carbide was 10 mm. Subsequently, acetylene was produced by adding 2.5 moles of distilled water to 1 mole of calcium carbide. At this time, the reaction temperature was maintained at 120°C.

[0056] Next, monovinylacetylene was produced and recovered from acetylene by the method described in paragraph 0028 of Japanese Patent No. 4001430. Then, chloroprene monomer was obtained by the method described in Non-Patent Literature: "CHLOROPRENE AND ITS POLYMERS" by Wallace H. Carothers, Ira Williams, Arnold M. Collins, and James E. Kirby (Journal of the American Chemical Society Vol 53 / Issue 11 / P4203), published November 5, 1931.

[0057] (Examples 2-16) Calcium carbide, acetylene, monovinylacetylene, and chloroprene monomer were obtained in the same manner as in Example 1, except that fixed carbon sources B-P were used instead of fixed carbon source A. (Reference Example) Calcium carbide, acetylene, monovinylacetylene, and chloroprene monomer were obtained in the same manner as in Example 1, except that fixed carbon source Q was used instead of fixed carbon source A.

[0058] 3. Measurement and Evaluation 3-1. Measurement of phosphorus and sulfur atom content in fixed carbon source The phosphorus and sulfur atom content in the fixed carbon source was measured in accordance with JIS M 8813:2004. 3-2. Measurement of carbon atom content in fixed carbon source The carbon atom content in the fixed carbon source was measured in accordance with JIS M 8812:2006.

[0059] 3-3. Measurement of crushing strength A sample was obtained by molding a fixed carbon source to a size of 35 mm × 35 mm × 10 mm. The crushing strength of this sample was measured according to JIS Z 8841:1993. 3-4. Measurement of volatile matter The volatile matter of the fixed carbon source was measured according to JIS M 8812:2006.

[0060] 3-5. Measurement of Oxygen, Phosphine, and Hydrogen Sulfide Content in Acetylene The oxygen content in acetylene was measured by gas chromatography-mass spectrometry using an Agilent 7820A GC system (manufactured by Agilent Technologies, Inc.) equipped with a TCD detector. The content (volume fraction) of phosphine and hydrogen sulfide was measured using a UV-1800 (manufactured by Shimadzu Corporation) according to the absorbance spectrophotometric method described in JIS K 1901:2003 5.4.1.

[0061] 3-6. Yield of Chloroprene Monomer The conversion rate and selectivity from acetylene to monovinylacetylene were determined by the method described in paragraph 0029 of Japanese Patent No. 4001430. Unreacted acetylene was recovered and the conversion reaction to monovinylacetylene was carried out again. Therefore, the yield to chloroprene monomer was determined as the selectivity from acetylene to monovinylacetylene × (yield from monovinylacetylene to chloroprene monomer). Note that the yield when converting from monovinylacetylene to chloroprene monomer using the method described in the above non-patent document is 65%, so the yield from monovinylacetylene to chloroprene monomer is always 65%.

[0062] The conversion rate and selectivity from acetylene to monovinylacetylene, and the yield of chloroprene monomer were evaluated according to the following criteria.

[0063] [Conversion rate from acetylene to monovinylacetylene] 1: The conversion rate was less than 15%. 2: The conversion rate was 15% or more but less than 17%. 3: The conversion rate was 17% or more but less than 19%. 4: The conversion rate was 19% or more but less than 21%. 5: The conversion rate was 21% or more.

[0064] [Selectivity from acetylene to monovinylacetylene] 1: Selectivity was less than 70%. 2: Selectivity was 70% or more but less than 75%. 3: Selectivity was 75% or more but less than 80%. 4: Selectivity was 80% or more but less than 85%. 5: Selectivity was 85% or more.

[0065] [Yield of Chloroprene Monomer] 1: Yield was less than 49%. 2: Yield was 49% or more but less than 52%. 3: Yield was 52% or more but less than 55%. 4: Yield was 55% or more but less than 58%. 5: Yield was 58% or more.

[0066] These results are shown in Tables 1 and 2 below.

[0067]

[0068] The abbreviations in Tables 1 and 2 are as follows: PP: Polypropylene PE: Polyethylene PS: Polystyrene PF: Phenolic resin CR: Chloroprene rubber vulcanized product NBR: Nitrile rubber vulcanized product P-rich: Waste containing a large amount of phosphorus atoms SM-CR: Sulfur-modified chloroprene rubber vulcanized product

[0069] As shown in Tables 1 and 2, the oxygen content in the acetylene obtained using a fixed carbon source containing the combustion residue of waste in each example was kept sufficiently low, resulting in a high yield of chloroprene monomer. Furthermore, the yield was comparable to that of chloroprene monomer obtained using coke in the reference example.

Claims

1. A method for producing chloroprene, comprising: a preparation step of preparing a fixed carbon source containing combustion residue of waste; a production step of generating a chloroprene precursor from the fixed carbon source; and a conversion step of converting the chloroprene precursor into chloroprene.

2. A method for producing chloroprene according to claim 1, wherein in the production step, a metal carbide is obtained by heating the fixed carbon source and the metal source in a heating furnace, and then the metal carbide is reacted with water to obtain acetylene as the chloroprene precursor.

3. A method for producing chloroprene according to claim 2, wherein in the conversion step, monovinylacetylene is obtained by a dimerization reaction of acetylene, and then chloroprene is obtained by a reaction of the monovinylacetylene with hydrogen chloride.

4. A method for producing chloroprene according to claim 1, wherein the fixed carbon source contains carbon atoms derived from the combustion residue of the waste and at least one of phosphorus atoms and sulfur atoms, wherein the content of phosphorus atoms is 1% by mass or less and the content of sulfur atoms is 5% by mass or less.

5. A method for producing chloroprene according to claim 4, wherein the content of phosphorus atoms in the fixed carbon source is 0.1 ppm or more, and the content of sulfur atoms is 0.1 ppm or more.

6. A method for producing chloroprene according to claim 4, wherein the crush strength of a sample of the fixed carbon source molded to a size of 35 mm × 35 mm × 10 mm is 10 kgf or more, as measured according to JIS Z 8841:1993.

7. A method for producing chloroprene according to claim 4, wherein the fixed carbon source has a volatile content of 5% by mass or less as measured in accordance with JIS M 8812:2006.

8. A method for producing chloroprene according to claim 4, wherein the content of carbon atoms in the fixed carbon source is 70% by mass or more.

9. A method for producing chloroprene according to claim 1, further comprising a recovery step of recovering a gas containing at least one of carbon monoxide and hydrogen.

10. A method for producing chloroprene according to claim 9, further comprising a reaction step of reacting at least the carbon monoxide with the hydrogen to obtain a carbon compound.

11. A method for producing chloroprene rubber, comprising: a monomer acquisition step of obtaining chloroprene as a monomer compound by the method for producing chloroprene described in any one of claims 1 to 10; and a polymerization step of obtaining chloroprene rubber by polymerizing the chloroprene.

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