Polymer

Abstract

To provide a polymer capable of yielding a polymer compound that is decomposable under mild conditions.SOLUTION: Provided is a polymer comprising a structural unit represented by the following formula (1), where the polymer has a decomposition rate of 5% or more when undergoing oxidation and subsequent base treatment. (In formula (1), Ra represents a urethane bond, a urea bond, or a thiourethane bond; and R11 to R13 each independently represent hydrogen or a hydrocarbon group having 1 to 10 carbon atoms).SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to polymers. [Background technology]

[0002] In recent years, environmental pollution caused by waste plastics such as non-biodegradable polystyrene, polyurethane, vinyl chloride, polypropylene, etc. has become a problem. From the viewpoint of environmental protection, development of degradable polymers such as biodegradable resins, photodegradable resins, and thermally degradable resins that can be decomposed in the natural environment even after disposal is being carried out.

[0003] However, such degradable polymers are insufficient in physical, mechanical, and chemical properties for many applications in which conventional resins are used, and therefore degradation proceeds even during normal use at room temperature and pressure, resulting in a problem of limited environments in which they can be used.

[0004] On the other hand, as a method for decomposing a polymer such as polyurethane, techniques such as amine decomposition, hydrolysis, alcoholysis, acidolysis, etc. are disclosed. For example, Patent Document 1 discloses a method for decomposing polyurethane into a polyamine compound (amine decomposition method). Patent Document 2 discloses a method for hydrolyzing polyurethane and then decomposing it with supercritical water oxidation (hydrolysis method). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2001-348457 A [Patent Document 2] Japanese Patent Application Publication No. 11-080419 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the technology of Patent Document 1 (amine decomposition method) requires that the decomposition of polyurethane be carried out at high temperatures of 100° C. to 300° C. Meanwhile, the technology of Patent Document 2 (hydrolysis method) requires that the decomposition of polyurethane be carried out in supercritical water at a temperature of 550° C. or higher and a pressure of 22 MPa or higher. Thus, the decomposition of polymers, including the technologies of Patent Documents 1 and 2, requires extremely high energy.

[0007] Therefore, an object of the present invention is to provide a polymer that can be decomposed under mild conditions. [Means for solving the problem]

[0008] The present invention (1) relates to a polymer comprising a structural unit represented by the following formula (1): It is a polymer that has a decomposition rate of 5% or more when treated with a base after oxidation.

[0009] [ka]

[0010] In formula (1), R a is a urethane bond, a urea bond, or a thiourethane bond, and R 11 ~R 13 are each independently either hydrogen or a monovalent organic group. Effect of the Invention

[0011] According to the present invention, it is possible to provide a polymer that can be decomposed under mild conditions. [Brief description of the drawings]

[0012] [Figure 1] FIG. 2 is a diagram showing the mechanism of the decomposition reaction of polyurethane according to the present embodiment. [Diagram 2] 1 is a diagram showing a flow of a polyurethane production method S1 of the present embodiment. [Diagram 3] FIG. 4 is a diagram showing the flow of a polyurethane curing step S30 in this embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, when an upper limit value and a lower limit value are separately described, it is deemed that a numerical range combining any upper limit value and any lower limit value is substantially disclosed.

[0014] In addition, when a compound is described, its isomers are also described.

[0015] In the following, the number average molecular weight is measured by gel permeation chromatography (GPC) (for example, gel permeation chromatography according to ASTM standard test D5296) using polystyrene as a standard polymer.

[0016] In the following, each viscosity is an E-type viscosity measured in accordance with JIS Z8803:2011 "Method of measuring viscosity of liquids." The measurement is performed using a cone-plate type rotational viscometer.

[0017] Unless otherwise specified, various measurements are performed at room temperature (25°C).

[0018] The polymer of this embodiment is a polymer containing a structural unit represented by the following formula (1).

[0019] [ka]

[0020] In formula (1), R a is a urethane bond, a urea bond, or a thiourethane bond, and R 11 ~R 13 are each independently either hydrogen or a monovalent organic group.

[0021] The polymer of the present embodiment preferably contains a plurality of structural units represented by formula (1). In such a case, Ra may be the same bond or different bonds in each structural unit as long as it is any one of a urethane bond, a urea bond, and a thiourethane bond. In addition, the polymer of the present embodiment may be linear or branched.

[0022] The polymer of the present embodiment has a first organic group and a second organic group bonded to the structural unit represented by the above formula (1). The first organic group and the second organic group are not particularly limited, and may be, for example, a hydrocarbon group, or an organic group containing oxygen, fluorine, sulfur, nitrogen, phosphorus, chlorine, or the like. The first organic group and the second organic group may have the same structure or different structures. The number average molecular weight of the first organic group and the second organic group when decomposed (oxidized and then treated with a base) by the decomposition method described below is preferably 1,000 or more, more preferably 1,100 or more, or even more preferably 1,200 or more.

[0023] The polymer of this embodiment is preferably configured by repeating a structural unit represented by the following formula (2).

[0024] [ka]

[0025] In formula (2), R a is a urethane bond, a urea bond, or a thiourethane bond, and R 11 ~R 13 are each independently either hydrogen or a monovalent organic group, and R1 is a divalent organic group.

[0026] In the polymer of this embodiment, among the structural units represented by the above formula (2), R1 has a number average molecular weight of preferably 1,000 to 10,000, more preferably 1,100 to 9,000, and even more preferably 1,200 to 8,000 when decomposed (oxidized and then treated with a base) by the decomposition method described below.

[0027] The polymer of this embodiment is preferably obtained by polymerizing (curing) a prepolymer obtained by reacting an active hydrogen compound having two or more active hydrogen groups, such as a polyol compound, a polyamine compound, or a polythiol compound, with a polyisocyanate compound, and a compound (A) described below. That is, when the prepolymer is obtained by reacting a polyol compound with a polyisocyanate compound, the polyurethane of this embodiment is obtained. When the prepolymer is obtained by reacting a polyamine compound with a polyisocyanate compound, the polyurea of ​​this embodiment is obtained. Furthermore, when the prepolymer is obtained by reacting a polythiol compound with a polyisocyanate compound, the polythiourethane of this embodiment is obtained.

[0028] The polymer of this embodiment thus obtained preferably has a decomposition rate of 5% or more, more preferably 30% or more, and even more preferably 50% or more, when subjected to a decomposition treatment (oxidation followed by base treatment) by the decomposition method described below.

[0029] As described above, the polymer of this embodiment includes polymers such as polyurethane, polyurea, or polythiourethane. Among these polymers, polyurethane will be described as a representative embodiment. That is, the physical properties / characteristics of the polyurethane of this embodiment, the raw material composition of the polyurethane, the method for producing polyurethane using the raw material composition, and applications of the polyurethane will be specifically described. Note that the present invention is not limited to this embodiment (polyurethane). Polyurea or polythiourethane can be produced by changing the polyol compound described below to a polyamine compound or a polythiol compound.

[0030] 1.Physical properties / properties 1-1. Decomposition performance The polyurethane of this embodiment undergoes a decomposition reaction by the decomposition method described below. That is, the polyurethane of this embodiment has decomposition performance under a certain environment. The decomposition performance, i.e., the degree of progress of the decomposition reaction, can be evaluated by the gel fraction / decomposition rate described below. In addition, since the polyurethane of this embodiment does not undergo a decomposition reaction during normal use at room temperature and normal pressure, it is superior in physical properties, mechanical properties, and chemical properties compared to conventional decomposable polymers. In addition, the decomposition method described below is performed under mild conditions and is a simple process, so that high energy is not required for decomposition.

[0031] 1-1-1.Disassembly method Distilled water and an oxidizing agent are added to the polyurethane and stirred at room temperature for 20 hours. The polyurethane is taken out, an aqueous base solution is added, and the mixture is stirred at room temperature for 20 hours.

[0032] 1-1-2.Decomposition mechanism FIG. 1 shows the mechanism of the decomposition reaction of the polyurethane of this embodiment. As shown in FIG. 1, when an oxidizing agent is added to the polyurethane of this embodiment, the sulfur atom of the thioether group is oxidized. Then, when an aqueous base solution is added and a base treatment is performed, the polymer main chain of the polyurethane is cut and the decomposition reaction proceeds. At least a part of the polyurethane after the decomposition reaction dissolves in the aqueous base solution. Here, the decomposition mechanism of the polyurethane of this embodiment is described, but this decomposition mechanism is not limited to the polyurethane of this embodiment. That is, this decomposition mechanism is similarly applied to the cases of polyurea and polythiourethane.

[0033] The oxidizing agent is not particularly limited, and examples thereof include hydrogen peroxide, OXONE (registered trademark) (potassium peroxymonosulfate), peracetic acid, sodium hypochlorite, sodium perborate, etc. The oxidizing agent must be added in an amount of at least one equivalent relative to the thioether group of the polyurethane of this embodiment. The basic aqueous solution is not particularly limited, and examples thereof include strong bases such as an aqueous sodium hydroxide solution and an aqueous potassium carbonate solution, and weak bases such as an aqueous sodium carbonate solution.

[0034] 1-1-3. Gel fraction / decomposition rate Before and after the decomposition reaction by the above-mentioned decomposition method, the mass of the polyurethane is measured by the measurement method described below, and the gel fraction before and after the decomposition reaction is calculated. The decomposition rate is calculated from the gel fraction before and after the decomposition reaction. The degree of progress of the decomposition reaction of the polyurethane, i.e., the decomposition performance, can be evaluated from the values ​​of the gel fraction and the decomposition rate.

[0035] 1-1-3-1.Measurement method The mass of the polyurethane is measured. Tetrahydrofuran (THF) is added to the polyurethane, and the mixture is stirred at room temperature for 20 hours. The polyurethane is removed, heated to 50° C. while applying a vacuum to remove the tetrahydrofuran, and then dried. The mass of the polyurethane after drying is measured.

[0036] 1-1-3-2.Calculation method The mass of the polyurethane obtained by the above-mentioned measurement method is divided by the mass of the polyurethane before measurement to obtain the gel fraction. The gel fraction after decomposition is subtracted from the gel fraction before decomposition and divided by the gel fraction before decomposition to obtain the decomposition rate. The calculation formulas for the gel fraction and the decomposition rate are shown below. (Gel fraction) = (mass after measurement) / (mass before measurement) × 100 (Decomposition rate) = {(gel fraction before decomposition) - (gel fraction after decomposition)} / (gel fraction before decomposition) × 100

[0037] The gel fraction before decomposition is not particularly limited. It is measured to calculate the decomposition rate. The gel fraction after decomposition is preferably 60% or less, 50% or less, 40% or less, 30% or less, 20% or less, or 15% or less. The decomposition rate is preferably 5% or more, 10% or more, 20% or more, 30% or more, 40% or more, or 50% or more. When the gel fraction and decomposition rate are within the above ranges, the decomposition of the polyurethane can be sufficiently promoted.

[0038] The polyurethane of this embodiment is produced by a production method (prepolymer method) described later, so that the number average molecular weight of the decomposition product can be controlled and the gel fraction and decomposition rate can be within the above ranges. The number average molecular weight of the decomposition product is described below.

[0039] 1-2. Number average molecular weight of decomposition products The polyurethane of this embodiment preferably has a number average molecular weight of the decomposition product after the above-mentioned decomposition experiment is 1,000 to 10,000, 1,100 to 9,000, or 1,200 to 8,000. The number average molecular weight of the decomposition product can be equivalent to the number average molecular weight of the urethane prepolymer used in the raw material composition.

[0040] 2. Raw material composition The polyurethane of this embodiment is obtained by polymerizing (curing) a raw material composition containing an isocyanate-terminated urethane prepolymer and a compound (A) having a structure represented by the following formula (2). The raw material composition of the polyurethane of this embodiment may contain other components. The raw material composition of the polyurethane of this embodiment, that is, the urethane prepolymer, the compound (A), and other components, will be described below.

[0041] [ka]

[0042] In formula (3), R A , R B are each independently a hydroxyl group, an amino group, or a thiol group; R 11 ~R 13 are each independently either hydrogen or a monovalent organic group, and R2 is a divalent organic group.

[0043] 2-1. Urethane prepolymer The urethane prepolymer is obtained by a urethane reaction between a polyol compound and a polyisocyanate compound. In other words, the urethane prepolymer is a reaction product between a polyol compound and a polyisocyanate compound. More specifically, the urethane prepolymer is usually produced by a urethane reaction between a polyol compound and a polyisocyanate compound in such a way that the polyisocyanate compound is in excess, and an isocyanate group-terminated urethane prepolymer is synthesized.

[0044] The number average molecular weight of the urethane prepolymer is preferably 1,000 to 10,000, 1,100 to 9,000, or 1,200 to 8,000. The molecular weight (calculated value) of the urethane prepolymer (the calculation method will be described in detail in the Examples) is preferably 1,000 to 5,000, 1,100 to 4,000, or 1,200 to 3,000. When the number average molecular weight and the molecular weight (calculated value) of the urethane prepolymer are within the above ranges, a polyurethane having better decomposition performance can be obtained.

[0045] The viscosity of the urethane prepolymer at 25°C is preferably 2,000 to 30,000 mPa·s, 2,000 to 10,000 mPa·s, 2,500 to 8,000 mPa·s, 3,000 to 7,000 mPa·s, or 3,500 to 6,000 mPa·s. When the viscosity of the urethane prepolymer at 25°C is within the above range, a polyurethane having better decomposition performance can be obtained.

[0046] 2-1-1.Polyol compounds The polyol compound is a compound having two or more hydroxyl groups in one molecule. The polyol compound is not particularly limited. Various polyols may be used alone or in combination of two or more kinds. They can be freely selected in consideration of the desired polyurethane properties.

[0047] The polyol compound preferably contains a copolymer (preferably a random copolymer) of ethylene oxide (EO) and alkylene oxide (AO). Note that the alkylene oxide shown here refers to one other than ethylene oxide.

[0048] Examples of the polyol compound include polyester polyol, polycarbonate polyol, polyether polyol, polyester ether polyol, etc. They can be freely selected in consideration of the desired properties of the polyurethane.

[0049] Examples of polyester polyols include aliphatic dicarboxylic acids such as succinic acid, adipic acid, sebacic acid, and azelaic acid, aromatic dicarboxylic acids such as phthalic acid, terephthalic acid, isophthalic acid, and naphthalenedicarboxylic acid, alicyclic dicarboxylic acids such as hexahydrophthalic acid, hexahydroterephthalic acid, and hexahydroisophthalic acid, and acid esters or acid anhydrides thereof, and ethylene glycol, 1,3-propylene glycol, 1,2-propylene ...3-propylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,3-propylene glycol, 1,3-propylene glycol, 1,3-propylene glycol, 1,3-propylene glycol, Examples of the polyols include polyester polyols such as polypropylene glycol obtained by a dehydration condensation reaction with lactone monomers such as ε-caprolactone and methylvalerolactone; and polyester polyols such as ε-caprolactone and methylvalerolactone obtained by ring-opening polymerization of lactone monomers such as ε-caprolactone and methylvalerolactone.

[0050] Examples of polycarbonate polyols include those obtained by reacting at least one of polyhydric alcohols such as ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, neopentyl glycol, 1,8-octanediol, 1,9-nonanediol, and diethylene glycol with diethylene carbonate, dimethyl carbonate, diethyl carbonate, and the like.

[0051] Examples of polyether polyols include polyethylene glycol, polypropylene glycol, polytetramethylene ether glycol, etc., which are obtained by polymerizing cyclic ethers such as ethylene oxide (EO), propylene oxide, tetrahydrofuran, etc., and copolyethers thereof. Polyether polyols can also be obtained by polymerizing the above-mentioned cyclic ethers using polyhydric alcohols such as glycerin and trimethylolethane.

[0052] Examples of polyester ether polyols include those obtained by a dehydration condensation reaction of aliphatic dicarboxylic acids such as succinic acid, adipic acid, sebacic acid, and azelaic acid; aromatic dicarboxylic acids such as phthalic acid, terephthalic acid, isophthalic acid, and naphthalenedicarboxylic acid; alicyclic dicarboxylic acids such as hexahydrophthalic acid, hexahydroterephthalic acid, and hexahydroisophthalic acid; or acid esters or acid anhydrides of these acids with glycols such as diethylene glycol or propylene oxide adducts, or mixtures thereof.

[0053] The polyol compounds may be used alone or in combination.

[0054] The polyol compound is preferably a diol and / or a triol.

[0055] The polyol compound preferably has a number average molecular weight of 200 to 5,000, 300 to 4,500, or 400 to 4000. When the number average molecular weight of the polyol is within this range, the number average molecular weight of the urethane prepolymer falls within an appropriate range, so that a polyurethane having better decomposition performance can be obtained.

[0056] 2-1-2. Polyisocyanate compounds The polyisocyanate compound is a compound having two or more isocyanate groups in one molecule. It is not particularly limited as long as it is a compound that is usually adopted as a raw material for urethane prepolymer. The polyisocyanate compound may be used alone or in combination of two or more kinds. The polyisocyanate compound may be bifunctional or trifunctional or more. It can be freely selected in consideration of the desired polyurethane properties.

[0057] Examples of bifunctional polyisocyanate compounds include 2,4-toluene diisocyanate (2,4-TDI), 2,6-toluene diisocyanate (2,6-TDI), m-phenylene diisocyanate, p-phenylene diisocyanate, 4,4'-diphenylmethane diisocyanate (4,4'-MDI), 2,4'-diphenylmethane diisocyanate (2,4'-MDI), 2,2'-diphenylmethane diisocyanate (2,2'-MDI), hydrogenated MDI, xylylene diisocyanate, 3,3'-dimethyl-4,4'-biphenylene diisocyanate, 3,3'-dimethoxy-4,4'-biphenylene diisocyanate, Examples of the isocyanate include aromatic isocyanates such as polymethylene polyphenyl polyisocyanate, 1,5-naphthalene diisocyanate, xylylene diisocyanate (XDI), hydrogenated XDI, and tetramethylxylene diisocyanate (TMXDI); alicyclic isocyanates such as cyclohexane-1,4-diisocyanate, isophorone diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, and methylcyclohexane diisocyanate; and alkylene isocyanates such as butane-1,4-diisocyanate, hexamethylene diisocyanate, isopropylene diisocyanate, methylene diisocyanate, and lysine diisocyanate.

[0058] Examples of tri- or higher functional polyisocyanate compounds include 1-methylbenzene-2,4,6-triisocyanate, 1,3,5-trimethylbenzene-2,4,6-triisocyanate, biphenyl-2,4,4'-triisocyanate, diphenylmethane-2,4,4'-triisocyanate, methyldiphenylmethane-4,6,4'-triisocyanate, 4,4'-dimethyldiphenylmethane-2,2',5,5'tetraisocyanate, triphenylmethane-4,4',4"-triisocyanate, polymeric MDI, lysine ester triisocyanate, 1,3,6-hexamethylene triisocyanate, 1,6,11-undecane triisocyanate, bicycloheptane triisocyanate, and 1,8-diisocyanatomethyloctane.

[0059] The polyisocyanate compound may also include modified products and derivatives thereof.

[0060] The polyisocyanate compounds may be used alone or in combination.

[0061] 2-2. Compound (A) Compound (A) has a structure shown in formula (3) below.

[0062] [ka]

[0063] In formula (3), R A , R B are each independently an active hydrogen group (either a hydroxyl group, an amino group, or a thiol group), and R 11 ~R 13 are each independently either hydrogen or a monovalent organic group, and R2 is a divalent organic group.

[0064] As shown in the above formula (3), compound (A) has a molecular chain end (R A , R B ) has an active hydrogen group capable of reacting with an isocyanate group. Compound (A) preferably contains a thioether group.

[0065] The end of the molecular chain (R A , R B Examples of the active hydrogen group at the terminal (R ) include a hydroxyl group, an amino group, and a thiol group. Preferred are a hydroxyl group and an amino group, and more preferred is a hydroxyl group. A , R B ) may be the same type of functional group or a combination of different types of functional groups. The amino group is preferably a primary amino group. Furthermore, the compound (A) has a molecular chain terminal (R A , R B The compound (A) may have an active hydrogen group in a portion other than the above-mentioned portion. That is, the compound (A) may have three or more active hydrogen groups.

[0066] R2 is not particularly limited as long as it is a divalent organic group, and is preferably a hydrocarbon group having 1 to 19 carbon atoms, more preferably 1 to 10 carbon atoms, further preferably 1 to 5 carbon atoms, and most preferably 2 carbon atoms.

[0067] R 11 ~R 13 is not particularly limited as long as it is hydrogen or a monovalent organic group, is preferably hydrogen or a hydrocarbon group having 1 to 5 carbon atoms, and is more preferably hydrogen.

[0068] R in compound (A) A The number of carbon atoms per sulfur atom bonded to --CC-- and R2 is, for example, 2 or more, preferably 3 or more, and 7 or less, preferably 4 or less.

[0069] More specific examples of the compound (A) include compounds containing a hydroxyl-terminated thioether group, compounds containing an amino-terminated thioether group, and compounds containing a thiol-terminated thioether group.

[0070] Hydroxyl-terminated thioether group-containing compounds have a molecular chain end (R A , R B ) and has a thioether group in the middle of the molecular chain. An example of a compound containing a thioether group at the hydroxyl end is 2,2'-thiodiethanol (TDE).

[0071] The amino-terminated thioether group-containing compound has a molecular chain end (R A , R B ) and has a thioether group in the middle of the molecular chain. An example of a compound containing a thioether group at the amino end is bis(2-aminoethyl)sulfide.

[0072] Thiol-terminated thioether-group-containing compounds have a molecular chain end (R A , R B) and has a thioether group in the middle of the molecular chain. An example of a compound containing a thioether group at the thiol group end is bis(2-mercaptoethyl)sulfide (MES).

[0073] The content of compound (A) is preferably 1 mass% or more, 5 mass% or more, 10 mass% or more, and preferably 25 mass% or less, 20 mass% or less, 15 mass% or less, based on the mass of the urethane prepolymer.

[0074] The molecular weight of the compound (A) is, for example, preferably 50 or more, 60 or more, or 100 or more, and is preferably 500 or less, 400 or less, or 300 or less.

[0075] The sulfide concentration in 1 kg of the polyurethane of this embodiment is preferably 0.1 mol / kg or more, 0.2 mol / kg or more, 0.3 mol / kg or more, etc., and preferably 0.9 mol / kg or less, 0.85 mol / kg or less, 0.8 mol / kg or less, etc. A method for calculating the sulfide concentration will be described below.

[0076] (Calculation method for sulfide concentration) The content P of compound (A) in 1 kg of polyurethane is calculated from the number of parts of compound (A) added and the total number of parts of all components of the polyurethane of this embodiment. The content P of compound (A) is divided by the molecular weight Q of compound (A) to calculate the sulfide concentration in 1 kg of polyurethane. The formula for calculating the sulfide concentration is shown below. (Sulfide concentration) = {Content of compound (A) P} / {Molecular weight of compound (A) Q} (mol / kg)

[0077] In the polyurethane raw material composition of this embodiment, as long as the amount of compound (A) and the sulfide concentration are within the above-mentioned ranges, another compound (B) other than compound (A) may be contained. Compound (B) is not particularly limited as long as it is a compound polymerizable with the urethane prepolymer, and examples thereof include diethylene glycol and 1,5-pentanediol.

[0078] 2-3.Other ingredients Examples of other components that may be added as appropriate to the raw material composition of the polyurethane of this embodiment include a defoamer and a catalyst.

[0079] 2-3-1. Defoaming agents As the defoaming agent, for example, fatty acid ester, vaseline, etc. can be used. As the foam stabilizer / defoaming agent, any one of these may be used alone, or two or more of them may be used in combination.

[0080] 2-3-2.Catalyst The catalyst may be a tertiary amine {C6-20, for example, triethylamine, triethylenediamine, bis(dimethylaminoethyl)ether, N-methylmorpholine, dimethylaminomethylphenol, N-methyl-N-dimethylaminoethylpiperazine, pyridine, etc.} and an acid block compound thereof, a metal salt of a carboxylic acid (C2-20) (sodium acetate, lead octoate, zinc octoate, iron octoate, bismuth octoate, zinc neodecanoate, iron naphthenate, cobalt naphthenate, stannous octoate, dibutyltin dilaurate, etc.), an alkali metal or Examples of the catalyst include alkaline earth metal alkoxides or phenoxides (C1-12, e.g., sodium methoxide, sodium phenoxide), quaternary ammonium salts (C4-12, e.g., tetraethylhydroxylammonium), imidazole compounds (C3-12, e.g., imidazole, 2-ethyl-4-methylimidazole), chelate metal salts (C5-20, e.g., zinc acetylacetonate, iron acetylacetonate), and organometallic compounds containing metals such as tin and antimony (C3-30, e.g., tetraphenyltin, tributylantimony oxide). These catalysts can be used alone or in combination.

[0081] 3. Manufacturing method The polyurethane of this embodiment can be produced based on a prepolymer method, which is a method in which a part of each of a polyol compound and a polyisocyanate compound is reacted in advance to obtain a prepolymer having an isocyanate group at its terminal (the above-mentioned urethane prepolymer), and then the compound (A) is reacted with the prepolymer.

[0082] The flow of the polyurethane production method of this embodiment is shown in Figure 2. As shown in Figure 2, the polyurethane production method S1 of this embodiment includes a urethane prepolymer production step S10, a raw material composition preparation step S20, and a curing step S30. Below, the preferred polyurethane production method S1 of this embodiment will be described in detail with each step being explained.

[0083] 3-1. Urethane prepolymer manufacturing process S10 A predetermined amount of polyol compound and, if necessary, a catalyst are dropped into a reaction vessel containing a predetermined amount of polyisocyanate compound. The reaction vessel is then heated and stirred to react the polyisocyanate compound with the polyol compound, producing an isocyanate group-terminated urethane prepolymer. The reaction temperature is not particularly limited, but is usually 50 to 120°C, preferably 60 to 100°C. The reaction time is not particularly limited, but is usually 1 to 15 hours.

[0084] The polyol compound, polyisocyanate compound, etc. are as described above in "2-1-1. Polyol compound" and "2-1-2. Polyisocyanate compound".

[0085] 3-1-1.Catalyst The catalyst may be any known catalyst used in the production of polyurethane, such as an amine catalyst or an organometallic catalyst.

[0086] Examples of the amine catalyst include triethylenediamine, diethanolamine, dimethylaminomorpholine, and N-ethylmorpholine.

[0087] Examples of the organometallic catalyst include bismuth carboxylate, sternazur octoate, dibutyltin dilaurate, lead octenate, and potassium octylate.

[0088] The catalysts may be used alone or in combination.

[0089] 3-2. Raw material composition preparation step S20 In the raw material composition preparation step S20, a raw material composition containing a urethane prepolymer and, for example, 2,2'-thiodiethanol as compound (A) is prepared. The raw material composition may contain other components (catalyst, antifoaming agent, etc.) as necessary. The urethane prepolymer, compound (A), and other components are as described above in "2-1. Urethane prepolymer", "2-2. Compound (A)", and "2-3. Other components".

[0090] 3-3.Curing process S30 Fig. 3 is a diagram showing the flow of the curing step S30. As shown in Fig. 3, the curing step S30 includes mixing and stirring the raw material composition prepared in the raw material composition preparation step S20 (stirring step S31), charging (injecting) the raw material composition into a reaction vessel (mold) (charging step S32), and heating the raw material composition as necessary to complete a polymerization (curing) reaction and produce polyurethane (reaction step S33). Below, the curing step S30 will be described in detail for each step.

[0091] 3-3-1. Mixing step S31 In the stirring step S31, the raw material composition prepared in the raw material composition preparation step S20, the urethane prepolymer, the compound (A), for example, 2,2'-thiodiethanol, and other components such as a catalyst and an antifoamer are placed in a container such as a disposable cup, and the components are stirred so as to be uniformly mixed. The stirring step S31 can be performed using a known stirring means such as a mixer. The stirring conditions in the stirring step S31 may be appropriately selected depending on the viscosity of the raw material composition, the components to be mixed, and the like.

[0092] 3-3-2. Input step S32 In the charging step S32, the raw material composition mixed in the stirring step S31 is charged (injected) into a reaction vessel. When a mold is used as the reaction vessel, the cavity of the mold can be shaped to have the product shape, thereby making it possible to obtain polyurethane in a desired product shape according to the application without performing post-processing.

[0093] 3-3-3. Reaction step S33 In the reaction step S33, the raw material composition introduced into the reaction vessel in the introduction step S32 is heated and cured. The reaction is usually performed at a temperature of 15 to 120° C., preferably 15 to 90° C. The reaction time is usually 60 to 120 minutes.

[0094] The cured product obtained in reaction step S33 may be subjected to a drying step as necessary. The drying step may be, for example, a method of exposing the polyurethane to an environment of 80 to 120° C. using a heating furnace, microwave oven, high-frequency induction heating, hot air drying, etc.

[0095] 4.Applications The polyurethane of this embodiment can be used in a wide range of industrial applications, including sealing materials, vibration-damping materials, shock-absorbing materials, cushioning materials, adhesive materials, bonding agents, and surface protection materials. The polyurethane of this embodiment can also be disassembled under mild conditions. In the production of the polyurethane of this embodiment, a polyurethane foam having cushioning properties and heat insulating properties can be obtained by adding a well-known foaming process. EXAMPLES

[0096] The present invention will be described in more detail below with reference to examples. However, the present invention is not limited to these examples and can be practiced in various forms with various modifications and improvements based on the knowledge of those skilled in the art.

[0097] <<Raw material composition>> <Example 1> Isocyanate-terminated urethane prepolymer {molecular weight (calculated value): 1,559} (number average molecular weight: 4,000) NCO%: 6.2%, EO (ethylene oxide) content: 55.9% by mass, E-type viscosity (25°C): 4300 mPa s

[0098] The molecular weight (calculated value) of the isocyanate-terminated urethane prepolymer was calculated by the following formula. Molecular weight of isocyanate-terminated urethane prepolymer (calculated value) = (42.02 / NCO%) × number of NCO groups (number of functional groups)

[0099] The NCO% value was measured in accordance with Method A (toluene / dibutylamine, hydrochloric acid method) of JIS K1603-1:2007 "Plastics - Polyurethane raw material aromatic isocyanate test method Part 1: Determination of isocyanate group content".

[0100] The average functionality of the urethane prepolymer was calculated from the raw materials.

[0101] Here, when a bifunctional polyisocyanate compound is used as the polyisocyanate compound and three types of polyols, polyol (a), polyol (b), and polyol (c), are used as the polyol compounds, the average number of functional groups of the entire polyols can be calculated by the following formula, which takes into account the number of functional groups of each polyol contained in all the polyols used and the molar fraction of each polyol.

[0102] (Number 1) [Average number of functional groups in urethane prepolymer]= [((Fa×Wa) / Ma)+(Fb×Wb / Mb)+(Fc×Wc / Mc)) / (Wa / Ma+Wb / Mb+Wb / Mb)]

[0103] Fa represents the number of functional groups of polyol (a), Wa represents the part by mass of polyol (a), and Ma represents the number average molecular weight of polyol (a). Fb represents the number of functional groups of polyol (b), Wb represents the part by mass of polyol (b), and Mb represents the number average molecular weight of polyol (b). Fc represents the number of functional groups of polyol (c), Wc represents the part by mass of polyol (c), and Mc represents the number average molecular weight of polyol (c).

[0104] The EO content of the urethane prepolymer was calculated from the raw materials.

[0105] Isocyanate-terminated urethane prepolymer raw material / mixture amount Bifunctional random polyol (number average molecular weight: 1,000, EO content 50% by mass): 21.9 parts by mass Trifunctional random polyol (number average molecular weight: 1,500, EO content 70% by mass): 33.1 parts by mass Polyethylene glycol (PEG) (number average molecular weight: 1,000): 25.8 parts by weight Isocyanate compound (hexamethylene diisocyanate) (HDI): 25.7 parts by mass

[0106] ●Compound (A) 2,2'-Thiodiethanol (molecular weight: 122.18) ●Other ingredients Defoaming agent {Dappo (registered trademark) (manufactured by San Nopco Co., Ltd.)} Catalyst {TIB KAT616 Zn-based (manufactured by TIB Chemical Co.)}

[0107] <Examples 2 to 4> The procedure was the same as in Example 1, except that in addition to the above raw material composition of Example 1, diethylene glycol (molecular weight: 106.1) was further used as compound (B).

[0108] <Comparative Example 1> The raw material composition of Example 1 was the same as that of Example 1, except that diethylene glycol was used as compound (B) instead of compound (A).

[0109] <Comparative Example 2> The procedure was the same as in Example 1, except that an isocyanate compound {hexamethylene diisocyanate (HDI)}, a bifunctional polyol {D-1000 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.)}, and a trifunctional polyol {Polyol 38 (manufactured by Sanyo Chemical Industries, Ltd.)} were used instead of the isocyanate group-terminated urethane prepolymer.

[0110] ≪Curing≫ The raw material composition described above was weighed into a container such as a disposable cup in the amount shown in Tables 1 and 2, and then stirred at room temperature for 1 minute with a propeller stirrer at 600 rpm. Then, the mixture was degassed for 1 minute using a planetary centrifugal mixer (Thinky Mixer, manufactured by Thinky Corp.). The stirred raw material composition was poured (injected) into a mold. The raw material composition poured into the mold was heated at 90°C for 2 hours and cured to form 60 g of polyurethane for each of Examples 1 to 4 and Comparative Examples 1 and 2. The isocyanate index of each polyurethane was 100. The isocyanate index refers to the ratio of the number of moles of isocyanate groups in a polyisocyanate compound to the number of moles of thiodiethanol or diethylene glycol.

[0111] ≪Disassembly≫ To a 20 ml vial containing 0.045 g of polyurethane of each of Examples 1 to 4 and Comparative Example 2, 3 equivalents of an oxidizing agent {OXONE (registered trademark) (potassium peroxymonosulfate)} relative to the thioether group and 9 g of distilled water were added. The mixture was stirred at room temperature for 20 hours with a roller stirrer. All of the oxidized polyurethane was removed and transferred to another vial. Then, 9 g of a 1 mol / L aqueous sodium hydroxide solution was added, and the mixture was stirred at room temperature for 20 hours with a roller stirrer. For Comparative Example 1, the same mass of oxidizing agent as in Example 1 was added, and the same operation was carried out.

[0112] <Measurement> 9 g of tetrahydrofuran (THF) was added to a 20 ml vial containing 0.045 g of polyurethane of each of Examples 1 to 4 and Comparative Examples 1 and 2. The mixture was stirred at room temperature for 20 hours with a roller stirrer. The polyurethane was taken out and heated to 50°C in a vacuum dryer to remove the THF. The mass of the polyurethane residue was measured. The mass of the polyurethane residue was divided by the mass of the polyurethane before the measurement to obtain the gel fraction. The measurement was performed on each of the polyurethanes of Examples 1 to 4 and Comparative Examples 1 and 2 before and after decomposition. The gel fraction before decomposition and the gel fraction after decomposition were calculated, and the decomposition rate was calculated from these values.

[0113] Evaluation For each of the polyurethanes of Examples 1 to 4 and Comparative Examples 1 and 2, the gel fraction before and after decomposition and the decomposition rate were calculated based on the above-mentioned measurement method and calculation method. The sulfide concentration was also calculated based on the above-mentioned calculation method. The formulation of the raw material composition and the evaluation results of each of Examples 1 to 4 and Comparative Examples 1 and 2 are shown in Tables 1 and 2.

[0114] [Table 1]

[0115] [Table 2]

Claims

[Claim 1] A polymer comprising a structural unit represented by the following formula (1): A polymer that has a decomposition rate of 5% or more when treated with a base after oxidation. 【Chemistry 1】 (In formula (1), R ａ is a urethane bond, a urea bond, or a thiourethane bond; R １１ ~R １３ are each independently either hydrogen or a monovalent organic group.

Images