Method for producing resin solution

Abstract

To provide: a dissolution method of resin capable of dissolving resin other than specific resin from waste plastic being a mixture containing a plurality of resins without dissolving the specific resin; and a manufacturing method of resin solution.SOLUTION: In a dissolving method of resin for dissolving resin other than specific resin from a mixture containing a plurality of kinds of resin without dissolving the specific resin, a solvent in which a relative energy difference based on a Hansen solubility parameter with respect to the specific resin exceeds one and a relative energy difference based on a Hansen solubility parameter with respect to the resin other than the specific resin is one or below is selected, and the mixture is subjected to a contact treatment with the solvent to dissolve the resin other than the specific resin.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a method for producing a resin solution.

Background Art

[0002] The development of recycling technologies for waste plastics has become one of the important issues in recent years from the viewpoints of increasing waste and effective use of limited resources. Recycling methods for waste plastics are roughly classified into three types: material recycling in which waste plastics are reused as they are, chemical recycling in which waste plastics are chemically decomposed to recover basic chemical raw materials such as monomers, and thermal recycling in which thermal energy is recovered from waste plastics.

[0003] Among these, material recycling and chemical recycling are desirable from the viewpoint of reducing environmental load, such as suppressing consumption of limited natural resources and reducing the amount of landfill treatment, because waste plastics can be converted into raw materials for products and reused.

[0004] In material recycling, after waste plastics are made into raw materials such as flakes and pellets, they are melted and molded, and then reused as a resin material for the same product or another plastic product. In order to meet the quality standards as a resin material, it is necessary to remove foreign substances and dirt and basically use the same type of plastic. In material recycling, if different types of waste plastics are mixed in the collected waste plastics, the characteristics of the recycled plastics will deteriorate, so a technology for separating the collected waste plastics with high precision is required.

[0005] In chemical recycling, waste plastics are thermally decomposed at a high temperature to produce chemical raw materials such as synthesis gas and cracked oil, or chemically decomposed to produce monomers, etc., and then converted into other chemical substances and reused. Compared with material recycling, it is often recyclable even if different types of plastics are mixed or there are foreign substances and dirt. On the other hand, when different types of plastics are mixed, there may be problems in the process.

[0006] Therefore, at present, waste plastics that are not suitable for material recycling and chemical recycling are being processed by thermal recycling, and there is a strong demand for separation technologies to obtain waste plastics suitable for material recycling and chemical recycling.

[0007] As a separation technology for waste plastics, Patent Document 1 discloses a method for sorting waste plastics for selecting recyclable plastics from waste plastics containing multiple types of materials, the method comprising: a material sorting step of sorting the recyclable plastics based on the difference in absorbance of wavelengths by materials; and a centrifugation step of increasing the purity of the recyclable plastics based on the difference in specific gravity by materials, wherein at least one type of the recyclable plastics is sorted as a recyclable plastic of a specific type by the material sorting step and the centrifugation step.

Prior Art Document

Patent Document

[0008]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0009] However, the method described in Patent Document 1 requires two steps, namely, a material sorting step and a centrifugation step, and is not efficient.

[0010] The present invention has been made in view of the above circumstances, and an object thereof is to provide a method for dissolving a resin that can dissolve resins other than a specific resin without dissolving the specific resin, and a method for producing a resin solution, from waste plastics that are a mixture containing a plurality of resins. That is, an object of the present invention is to provide a method for efficiently separating a specific resin as a solid and resins other than the specific resin as a resin solution from waste plastics that are a mixture containing a plurality of resins. [Means for Solving the Problems]

[0011] In order to solve the above problems, the present invention has the following aspects. [1] A method for dissolving a resin, which dissolves resins other than a specific resin without dissolving the specific resin from a mixture containing a plurality of types of resins, the method comprising selecting a solvent in which the relative energy difference based on the Hansen solubility parameter for the specific resin is greater than 1 and the relative energy difference based on the Hansen solubility parameter for resins other than the specific resin is 1 or less, and bringing the mixture into contact with the solvent to dissolve the resins other than the specific resin. [2] The method for dissolving a resin according to [1], wherein the specific resin contains a chlorine element. [3] The method for dissolving a resin according to [1] or [2], wherein the mixture contains at least one resin selected from the group consisting of polyethylene, polypropylene, polystyrene, and polyvinyl chloride. [4] The method for dissolving a resin according to any one of [1] to [3], wherein the solvent contains two or more solvents. [5] A method for producing a resin solution, which has the method for dissolving a resin according to any one of [1] to [4] as a resin dissolution step. [Advantages of the Invention]

[0012] According to the present invention, it is possible to provide a method for dissolving a resin that can dissolve resins other than a specific resin without dissolving the specific resin from waste plastic, which is a mixture containing a plurality of resins. In addition, it is possible to provide a method for producing a resin solution, which has the method for dissolving a resin as a resin dissolution step. [Brief Description of the Drawings]

[0013]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Mode for Carrying Out the Invention

[0014] Hereinafter, embodiments of the present invention will be described in detail. However, the following description is an example of an embodiment of the present invention, and the present invention is not limited to these contents and can be implemented with modifications within the scope of the gist.

[0015] The method for dissolving the resin of the present embodiment is a method for dissolving a resin in a mixture containing a plurality of types of resins without dissolving a specific resin and dissolving resins other than the specific resin. Specifically, a solvent is selected in which the relative energy difference based on the Hansen solubility parameter with respect to the specific resin exceeds 1 and the relative energy difference based on the Hansen solubility parameter with respect to resins other than the specific resin is 1 or less, and the mixture is brought into contact with the solvent to dissolve resins other than the specific resin. Hereinafter, the method for obtaining the Hansen solubility parameter and the relative energy difference will be described.

[0016] <Hansen Solubility Parameter> The Hansen solubility parameter (hereinafter also simply referred to as "HSP") is based on the idea that two substances with similar intermolecular interactions are likely to dissolve in each other. The HSP consists of the energy derived from intermolecular dispersion forces (δd), the energy derived from intermolecular dipole-dipole interactions (δp), and the energy derived from intermolecular hydrogen bonds (δh). These three parameters can be regarded as coordinates in a three-dimensional space (Hansen space).

[0017] The HSP value of an evaluation sample with an unknown HSP value can be calculated by the following method. HSP value (δd m , δp m , δh m ) In the Hansen solubility parameter space identified by plotting in three-dimensional space, a plurality of pure substances (substances composed of one kind of compound) with known HPS values are plotted, and a Hansen sphere is identified based on the solubility of the evaluation sample in the above pure substances, and the HSP value of the evaluation sample can be calculated by obtaining the central value of the Hansen sphere (Hansen sphere method). In addition, the HSP value of the evaluation sample can also be calculated using the group contribution method from the information of the average molecular structure. In both the case of the Hansen sphere method and the case of the group contribution method, when calculating the HSP value of the evaluation sample, for example, it can be calculated using computer software Hansen Solubility Parameters in Practice (HSPiP). In the case of the Hansen sphere method, the evaluation sample may be a pure substance or a mixture.

[0018] The method for obtaining the central value of the above Hansen sphere, that is, the HSP value (δd m , δp m , δh m ) will be described with reference to FIG. 1. First, plot the HSP values of about 15 to 30 pure substances having known HSP values in a three-dimensional space (with the dispersion force term δd, the dipole-dipole force term δp, and the hydrogen bonding force term δh as the coordinate axes) as exemplified in FIG. 1. At this time, as shown in FIG. 1, for example, a pure substance showing solubility in the evaluation sample is marked with a ○, and a pure substance not showing solubility in the evaluation sample is marked with a ×. Next, based on the solubility of the plotted evaluation samples, among the virtual spheres that include the pure substances showing solubility (indicated by ○ in FIG. 1) and do not include the pure substances not showing solubility (indicated by × in FIG. 1), the one with the minimum radius is determined as the Hansen sphere S (shown spherically in FIG. 1). The radius (the above minimum radius) forming the above Hansen sphere S is the interaction radius R at which the pure substance indicated by ○ in the figure dissolves and shows compatibility. 0 And the central values (δd m , δp m , δh m ) of the obtained Hansen sphere S become the HSP values of the evaluation sample. As the HSP values of the above pure substances used to obtain the Hansen sphere, for example, the dispersion force term δd is about 10 to 25 MPa. 1 / 2 The dipole-dipole force term δp is about 0 to 20 MPa. 1 / 2 The hydrogen bonding force term δh is about 0 to 20 MPa. 1 / 2 Also, since solubility depends on temperature, when obtaining the above Hansen sphere, it is preferable to conduct a solubility test at the temperature at which the resin is actually dissolved.

[0019] Next, FIG. 2 is a schematic diagram showing the distance between the solubility parameters of two substances, substance 1 and substance 2. First, the Hansen spheres of substance 1 and substance 2 are obtained by the above method. When the HSP value of substance 1 is (δd 1 , δp 1 , δh 1 ) and the HSP value of substance 2 is (δd 2 , δp 2 , δh 2 ), the distance of the HSP values between the two substances (hereinafter, also simply referred to as "Ra") can be calculated by the following formula 1. Ra = {4 × (δd 1 - δd 2 )​2 +(δp 1 -δp 2 ) 2 +(δh 1 -δh 2 ) 2} 0.5 Formula 1

[0020] The relative energy difference based on the Hansen solubility parameter of Substance 1 with respect to Substance 2 (hereinafter, also simply referred to as "RED") can be calculated by the following Formula 2 when the interaction radius of Substance 2 is R 0 as follows. RED = Ra / R 0 Formula 2

[0021] Figure 3 is a schematic diagram showing the case where the RED based on the Hansen solubility parameter of Substance 1 with respect to Substance 2 is within 1. In this case, as shown in Figure 3, the HSP values (δd 1 , δp 1 , δh 1 ) of Substance 1 are located inside (including the surface of the sphere) the Hansen sphere S2 of Substance 2.

[0022] Figure 4 is a schematic diagram showing the case where the RED based on the Hansen solubility parameter of Substance 1 with respect to Substance 2 exceeds 1. In this case, as shown in Figure 4, the HSP values (δd 1 , δp 1 , δh 1 ) of Substance 1 are located outside (excluding the surface of the sphere) the Hansen sphere S2 of Substance 2.

[0023] The method for dissolving the resin according to this embodiment is a method for dissolving a resin that dissolves resins other than a specific resin from a mixture containing a plurality of types of resins. Specifically, a solvent is selected in which the relative energy difference based on the Hansen solubility parameter with respect to the specific resin exceeds 1 and the relative energy difference based on the Hansen solubility parameter with respect to resins other than the specific resin is 1 or less, and the mixture is brought into contact with the solvent to dissolve the resins other than the specific resin. The specific resin may be one kind or a plurality of kinds. The resin other than the specific resin may be one kind or a plurality of kinds. Hereinafter, the specific resin is referred to as "resin A", and the resin other than the specific resin is referred to as "resin B". In this embodiment, only resin B is dissolved from a mixture containing resin A and resin B.

[0024] <Solvent selection method> Resin A consists of resin P A1 ~P Ax and resin B consists of resin P B1 ~P By x represents the number of types of resins constituting resin A and is an integer of 1 or more. y represents the number of types of resins constituting resin B and is an integer of 1 or more. The value of x is not particularly limited, but from the viewpoint of facilitating the selection of the solvent, it is preferably 1 to 3, more preferably 1 to 2. The value of y is not particularly limited, but from the viewpoint of facilitating the selection of the solvent, it is preferably 1 to 5, more preferably 1 to 3. The value of x + y is not particularly limited, but from the viewpoint of facilitating the selection of the solvent, it is preferably 2 to 8, more preferably 2 to 5.

[0025] By the above method, the Hansen spheres S(P A1 )~S(P Ax ) of P A1 ~P Ax are obtained respectively. Then, from the obtained Hansen spheres S(P A1 )~S(P Ax ), the HSP values [δd(P A1 )~δd(P Ax ), δp(P A1 )~δp(P A1 ), δh(P A1 )~δh(P Ax )] and the interaction radius R Ax (P Ax )~R 0 (P A1 )~R 0 (P Ax ) are obtained respectively. Similarly, P B1 ~P ByHansen spheres S(P B1 ) to S(P By ) are determined respectively. Then, from the obtained Hansen spheres S(P B1 ) to S(P By ), the HSP values of resin P B1 to P By , [δd(P B1 ), δp(P B1 ), δh(P B1 )] to [δd(P By ), δp(P By ), δh(P By )] and the interaction radius R 0 (P B1 ) to R 0 (P By ) are determined respectively.

[0026] Assume the HSP value of the selected solvent L as the provisional values [δd(L), δp(L), δh(L)]. The HSP values of resin P A1 to P Ax , [δd(P A1 ), δp(P A1 ), δh(P A1 )] to [δd(P Ax ), δp(P Ax ), δh(P Ax )] are respectively substituted into (δd 2 , δp 2 , δh 2 ) of Formula 1, and the HSP value of solvent L, [δd(L), δp(L), δh(L)] is substituted into (δd 1 , δp 1 , δh 1 ) of Formula 1 to determine Ra(P A1 ) to Ra(P Ax ) respectively. The obtained Ra(P A1 ) to Ra(P Ax ) are functions of δd(L), δp(L), and δh(L). And the interaction radius R A1 to P Ax , R 0 (P A1 ) to R 0 (P Ax ) and the obtained Ra(P A1 ) to Ra(P Ax) are each substituted into the above formula 2, and RED(P A1 )~RED(P Ax ) is obtained. The obtained RED(P A1 )~RED(P Ax ) becomes a function of δd(L), δp(L), and δh(L).

[0027] Similarly, the HSP values of resin P B1 ~P By ) [δd(P B1 ), δp(P B1 ), δh(P B1 )]~[δd(P By ), δp(P By ), δh(P By )] are each substituted into (δd 2 , δp 2 , δh 2 ) of the above formula 1, and the HSP values of solvent L [δd(L), δp(L), δh(L)] are substituted into (δd 1 , δp 1 , δh 1 ) of the above formula 1, and Ra(P B1 )~Ra(P By ) are each obtained. The obtained Ra(P B1 )~Ra(P By ) becomes a function of δd(L), δp(L), and δh(L). And the interaction radius R B1 ~P By of P 0 (P B1 )~R 0 (P By ) and the obtained Ra(P B1 )~Ra(P By ) are each substituted into the above formula 2, and RED(P B1 )~RED(P By ) is obtained. The obtained RED(P B1 )~RED(P By ) becomes a function of δd(L), δp(L), and δh(L).

[0028] In this embodiment, all of RED(P A1 )~RED(P Ax ) are greater than 1, and RED(P B1 )~RED(P BySelect a solvent L having HSP values [δd(L), δp(L), δh(L)] such that all of them are 1 or less. Fig. 5 shows the HSP values of the solvent L when x is 2 and y is 2, and the resin P A1 , P A2 's Hansen sphere S(P A1 ), S(P A2 ), and the resin P B1 , P B2 's Hansen sphere S(P B1 ), S(P B2 ). As shown in Fig. 5, the HSP values [δd(L), δp(L), δh(L)] of the solvent L are located outside (excluding the surface of the sphere) the Hansen spheres S(P A1 ), P A2 ), S(P A1 ), S(P A2 ) of the resin P, and are located inside (including the surface of the sphere) the Hansen spheres S(P B1 ), P B2 ), S(P B1 ), S(P B2 ) of the resin P.

[0029] In this embodiment, all of RED(P A1 ) to RED(P Ax ) are greater than 1, preferably 2.5 or more, and more preferably 3 or more. When all of RED(P A1 ) to RED(P Ax ) are greater than the lower limit value (or more), the dissolution of the resin P A1 to P Ax constituting the resin A by the solvent L is suppressed. The upper limit value of RED(P A1 ) to RED(P Ax ) is not particularly limited, but is, for example, 10 or less.

[0030] In this embodiment, all of RED(P B1 ) to RED(P By ) are 1 or less, preferably 0.9 or less, and more preferably 0.8 or less. When all of RED(P B1 ) to RED(P By ) are less than or equal to the upper limit value, the resin P B1 to P ByDissolution by the solvent L is promoted. RED(P B1 )~RED(P By ) The lower limit is not particularly limited, but is, for example, 0.1 or more.

[0031] The HSP value of the solvent L and the resin P A1 ~P Ax The distance of the respective HSP values, Ra(P A1 )~Ra(P Ax ) is not particularly limited as long as all of RED(P A1 )~RED(P Ax ) are greater than 1, but is preferably, for example, 5 MPa 1 / 2 or more, and more preferably 10 MPa 1 / 2 or more.

[0032] The HSP value of the solvent L and the resin P B1 ~P By The distance of the respective HSP values, Ra(P B1 )~Ra(P By ) is not particularly limited as long as all of RED(P B1 )~RED(P By ) are less than or equal to 1, but is preferably, for example, 8 MPa 1 / 2 or less, and more preferably 5 MPa 1 / 2 or less.

[0033] RED(P B1 )~RED(P By ) To select a solvent L having HSP values [δd(L), δp(L), δh(L)] such that all of them are less than or equal to 1, when y is 2 or more, the Hansen spheres S(P B1 ~P By ) of the resins P B1 )~S(P By ) all mean having an overlapping part. That is, when resins P Bc , P Bd for which y = c and y = d are randomly selected from the resin B, the HSP values [δd(P Bc )], δp(P Bc )], δh(P Bc )] of P Bc ) and the HSP values [δd(P Bd )] of PBd ) δp(P Bd ) δh(P Bd )] are substituted into (δd 1 , δp 1 , δh 1 ) and (δd 2 , δp 2 , δh 2 ) of Formula 1 respectively to obtain Ra(P Bc - P Bd ), and the relationship between the interaction radius R Bc (P 0 ) of P Bc ) and the interaction radius R Bd (P 0 ) of P Bd ) satisfies the following Formula 3. {R 0 (P Bc ) + R 0 (P Bd )} ≥ Ra(P Bc - P Bd ) Formula 3

[0034] When there is a combination of resins P B1 to P By that does not satisfy Formula 3, the resin of Resin B can be appropriately reselected. That is, any resin is removed from P B1 to P By that constitutes Resin B so as to satisfy Formula 3. In this case, the removed resin will constitute Resin A.

[0035] <Resin> The types of resins contained in the mixture of this embodiment are not particularly limited. For example, polyolefin resins such as polyethylene, polypropylene, polybutadiene, and polymethylpentene; vinyl resins such as polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, ethylene-vinyl acetate copolymer, and ethylene-vinyl alcohol copolymer; polystyrene resins such as polystyrene, acrylonitrile-styrene resin, and acrylonitrile-butadiene-styrene resin; polyester resins such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, and polytrimethylene terephthalate; cellulose triacetate; polycarbonate; urethane resins such as polyurethane and acrylic-modified polyurethane; polymethylpentene; polysulfone resins such as polyethersulfone, polyphenylsulfone, and polysulfone; polyetheretherketone such as polyetherketone, polyetheretherketone, and polyetherketoneketone; polyphenylene sulfide; polyimide resins such as polyetherimide and polyimide; polyamide resins such as polyamide 6, polyamide 66, and polyamide 11; acrylic resins; fluorine-based resins; phenolic resins; epoxy resins; melamine resins; urea resins; unsaturated polyester resins; alkyd resins, etc. can be mentioned. The mass average molecular weight of the resin contained in the mixture of this embodiment is not particularly limited as long as the effects of the present invention can be obtained. For example, it may be 10,000 to 100,000, or it may be 100,000 to 1,000,000.

[0036] Also, the resin of this embodiment is solid at 30°C or lower. The form of the resin is not particularly limited as long as the effects of the present invention can be obtained. Examples include molded bodies formed into packages such as PET bottles, pellets, flakes, etc. The size of the resin is not particularly limited as long as the effects of the present invention can be obtained, but its major axis is about 1 to 100 mm. From such resins, resin A and resin B can be arbitrarily selected according to the uses described later.

[0037] <Solvent> As the solvent of this embodiment, RED(P A1)~RED(P Ax ) are all greater than 1, and RED(P B1 )~RED(P ByAs long as the HSP value is 1 or less for all of them, it is not particularly limited. Examples of the solvent include esters such as methyl formate, ethyl formate, propyl formate, pentyl formate, methyl acetate, ethyl acetate, pentyl acetate, benzyl acetate, benzyl benzoate, ethyl benzoate, butyl benzoate, etc., ketones such as acetone, diisobutyl ketone, ethyl methyl ketone, cyclopentanone, cyclohexanone, methylcyclohexanone, γ-butyrolactone, N-methyl-2-pyrrolidone, etc., ethers such as diethyl ether, methyl-tert-butyl ether, diisopropyl ether, dimethoxymethane, dimethoxyethane, 1,4-dioxane, 1,3-dioxolane, 4-methyldioxolane, tetrahydrofuran, methyltetrahydrofuran, anisole, phenetole, 2-methoxytetrahydropyran, etc., alcohols such as methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, tert-butanol, 1-pentanol, 2-methyl-2-butanol, methoxypropanol, diacetone alcohol, cyclohexanol, 2-fluoroethanol, 2,2,2-trifluoroethanol, 2,2,3,3-tetrafluoro-1-propanol, etc., glycol ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol monoethyl ether acetate, triethylene glycol dimethyl ether, etc., organic solvents having an amide group such as N,N-dimethylformamide, acetamide, N,N-dimethylacetamide, etc., organic solvents having a nitrile group such as acetonitrile, isobutyronitrile, propionitrile, methoxyacetonitrile, etc., organic solvents having a carbonate group such as ethylene carbonate, propylene carbonate, 1,2-glycerol carbonate, etc., halogenated hydrocarbons such as methylene chloride, chloroform, tetrachloroethane, chlorobenzene, etc., hydrocarbons such as n-pentane, cyclohexane, n-hexane, 1-octadecene, benzene, toluene, xylene, 2,2,4-trimethylpentane, cyclohexene, ethylbenzene, d-limonene, l-limonene, etc.

[0038] The solvent may be used alone or in combination of two or more kinds. That is, the solvent of the present embodiment may be a mixture of two or more solvents (hereinafter, also referred to as "mixed solvent"). Examples of the mixed solvent include mixtures of two or more solvents listed above.

[0039] Other mixed solvents include petroleum fractions obtained in the refining process of crude oil such as atmospheric residue, vacuum gas oil, vacuum residue, desulfurized atmospheric residue, desulfurized vacuum gas oil, light cracked gas oil, and heavy cracked gas oil; vegetable oils such as soybean oil, rapeseed oil, sunflower oil, corn oil, cottonseed oil, peanut oil, olive oil, palm oil, sesame oil, rice bran oil, and orange oil, and waste oils thereof may also be used. Further, the above-mentioned solvents may be mixed with these mixed solvents.

[0040] When the mixed solvent is used as the solvent of the present embodiment, the HSP value of the mixed solvent may be determined by the above method, or may be determined by weighted averaging the HSP values of the solvents constituting the mixed solvent as follows. The mixed solvent L consists of solvents L 1 ~L z and the volume ratios of solvents L 1 ~L z to the total volume of all solvents before mixing of the mixed solvent are respectively V(L 1 )~V(L z ). Let the HSP values of solvents L 1 ~L z be [δd(L 1 ), δp(L 1 ), δh(L 1 )]~[δd(L z ), δp(L z ), δh(L z )]. Then, the HSP value [δd(L), δp(L), δh(L)] of the mixed solvent can be determined by the following formulas 4 to 6.

[0041]

Equation

[0042]

Equation

[0043]

Number

[0044] In this embodiment, the HSP value of the mixed solvent is preferably determined by the above formulas 4 to 6.

[0045] The boiling point of the solvent of this embodiment is not particularly limited as long as the effects of the present invention can be obtained. For example, it may be 80 to 700 ° C, 150 to 500 ° C, or 200 to 400 ° C. The density of the solvent of this embodiment is not particularly limited as long as the effects of the present invention can be obtained. For example, it may be 0.70 to 1.5 g / cm 3 or 0.80 to 1.2 g / cm 3 or 0.85 to 1.2 g / cm 3 is also acceptable.

[0046] <Combination of Resin A, Resin B and Solvent L> In this embodiment, Resin A preferably contains a chlorine element. Further, in this embodiment, Resin B and Solvent L preferably do not contain a chlorine element. When the solution obtained by the resin dissolution method and the resin solution production method of this embodiment is used as a raw material for the following chemical recycling, if the resin solution contains a chlorine element, hydrogen chloride may be generated during the chemical recycling process, which may corrode the equipment used for chemical recycling. Since Resin A contains a chlorine element and Resin B and Solvent L do not contain a chlorine element, the resulting solution does not contain a chlorine element, and it becomes possible to prevent corrosion of the said apparatus. Moreover, as the resin contained in the mixture of this embodiment, it is preferable that it is at least 1 sort (s) of resin chosen from the group which consists of polyethylene, polypropylene, polystyrene, and polyvinyl chloride.

[0047] When the resins constituting resin A are polystyrene and polyvinyl chloride, and the resins constituting resin B are polyethylene and polypropylene, solvents for which the relative energy difference based on the Hansen solubility parameter with respect to resin A is greater than 1 and the relative energy difference based on the Hansen solubility parameter with respect to resin B is 1 or less include benzene, cyclohexane, and ethylbenzene as examples.

[0048] When the resins constituting resin A are polypropylene and polyvinyl chloride, and the resins constituting resin B are polyethylene and polystyrene, solvents for which the relative energy difference based on the Hansen solubility parameter with respect to resin A is greater than 1 and the relative energy difference based on the Hansen solubility parameter with respect to resin B is 1 or less include butyl benzoate, benzyl acetate, and orange oil as examples.

[0049] When the resins constituting resin A are polyethylene and polyvinyl chloride, and the resins constituting resin B are polypropylene and polystyrene, solvents for which the relative energy difference based on the Hansen solubility parameter with respect to resin A is greater than 1 and the relative energy difference based on the Hansen solubility parameter with respect to resin B is 1 or less include chlorobenzene and the like as examples.

[0050] When the resins constituting resin A are polyethylene and polypropylene, and the resins constituting resin B are polystyrene and polyvinyl chloride, solvents for which the relative energy difference based on the Hansen solubility parameter with respect to resin A is greater than 1 and the relative energy difference based on the Hansen solubility parameter with respect to resin B is 1 or less include N-methylpyrrolidone, N,N-dimethylacetamide and the like as examples.

[0051] When the resin constituting resin A is polypropylene and the resins constituting resin B are polyethylene, polystyrene, and polyvinyl chloride, solvents with a relative energy difference based on the Hansen solubility parameter for resin A exceeding 1 and a relative energy difference based on the Hansen solubility parameter for resin B being 1 or less include ethyl benzoate, 2-methoxytetrahydropyran, a mixed solvent of 81% by mass of d-limonene and 19% by mass of 1,2-glycerol carbonate, a mixed solvent of 64% by mass of d-limonene and 36% by mass of dimethylformamide, a mixed solvent of 58% by mass of tetrahydrofuran and 42% by mass of cyclohexanone, a mixed solvent of 62% by mass of ethyl acetate and 38% by mass of benzyl benzoate, a mixed solvent of 58% by mass of methyl ethyl ketone and 42% by mass of benzyl benzoate, etc. as examples.

[0052] When the resin constituting resin A is polyvinyl chloride and the resins constituting resin B are polyethylene, polypropylene, and polystyrene, solvents with a relative energy difference based on the Hansen solubility parameter for resin A exceeding 1 and a relative energy difference based on the Hansen solubility parameter for resin B being 1 or less include 1,1,1,2-tetrachloroethane, d-limonene, o-xylene, toluene, etc. as examples.

[0053] (Resin dissolution conditions) In the method for dissolving the resin of this embodiment, the ratio of the mixture to the total mass of the solvent is not particularly limited as long as resin B can be dissolved. For example, it may be 1 to 50% by mass, 1 to 40% by mass, or 1 to 30% by mass. In the method for dissolving the resin of this embodiment, the ratio of resin B to the total mass of the solvent is not particularly limited as long as resin B can be dissolved. For example, it may be 1 to 20% by mass, 1 to 18% by mass, or 1 to 15% by mass. The temperature for dissolving resin B is not particularly limited as long as resin B can be dissolved. If the temperature is such that resin A does not soften or melt, it may be 15 to 100°C, 20 to 90°C, or 30 to 80°C. When dissolving Resin B, it is preferable to perform stirring, ultrasonic treatment, etc.

[0054] In the method for dissolving the resin of the present embodiment, it is preferable that all of Resin B is dissolved, but 80 to 100% by mass, or 90 to 100% by mass, of the total mass of Resin B may be dissolved. In the method for dissolving the resin of the present embodiment, it is preferable that Resin A is not dissolved, but 0% by mass or more and less than 1% by mass, or 0 to 0.5% by mass, of the total mass of Resin A may be dissolved.

[0055] The amount of dissolved resin can be confirmed, for example, by measuring the content of heteroatoms in the dissolution solution in the case of a resin containing heteroatoms such as halogen elements. The amount of dissolved resin of a resin not containing heteroatoms can be measured by a conventionally known analysis method. Examples of such an analysis method include infrared spectroscopy, gas chromatography-mass spectrometry, and gel filtration permeation chromatography.

[0056] <Method for Producing Resin Dissolution Solution> The method for producing the resin dissolution solution of the present embodiment has the above-described method for dissolving the resin as a resin dissolution step. As the resin dissolution solution, a dissolution solution in which Resin A is not dissolved and only Resin B is dissolved can be obtained.

[0057] <Uses of the Method for Dissolving Resin and the Method for Producing Resin Dissolution Solution> The uses of the method for dissolving the resin and the method for producing the resin dissolution solution of the present embodiment are roughly classified into two types: a method of using Resin A and a method of using Resin B.

[0058] (Method of Using Resin A) As a method of using the undissolved Resin A by the method for dissolving the resin of the present embodiment, material recycling is cited as an example. In this specification, "material recycling" means a recycling method of regenerating waste plastic made of one type of resin into a plastic product using the plastic raw material.

[0059] When recycling resin A as a material, first, resin A is separated by solid-liquid separation of the resin solution obtained by the resin dissolution method of the present embodiment. The obtained resin A is washed and dried to obtain resin A as a solid. The obtained resin A can be processed by a material recycling method known in the art. In material recycling, it is preferable that resin A is of one type. As resin A used in material recycling, polyethylene, polypropylene, polystyrene, polyvinyl chloride, acrylonitrile-butadiene-styrene resin, acrylic resin, etc. are preferable.

[0060] (Method of using resin B) As a method of using resin B dissolved by the resin dissolution method of the present embodiment, chemical recycling can be cited as an example. In this specification, "chemical recycling" means a recycling method in which waste plastic, which is a mixture containing a plurality of types of resins, is chemically converted (decomposed, etc.) to be recycled into chemical raw materials. Examples of chemical recycling include raw material / monomerization in which waste plastic is chemically decomposed and returned to plastic or monomers, blast furnace raw materialization in which waste plastic is used as a reducing agent in a steelworks, coke oven chemical raw materialization in which waste plastic is decomposed in a coke oven to obtain hydrocarbon oil, coke, and coke oven gas, gasification in which waste plastic is decomposed by heat to obtain synthesis gas, and gasification in which waste plastic is decomposed by heat to obtain synthesis gas.

[0061] When chemically recycling resin B, first, resin A is separated by solid-liquid separation of the resin solution containing solid resin A obtained by the resin dissolution method of the present embodiment, and a solution in which resin B is dissolved in solvent L is obtained. Then, it is preferable to use the obtained solution as a raw material for chemical recycling.

[0062] In this embodiment, among chemical recycling, it is preferable to use the above-mentioned dissolution liquid for the raw material / monomerization reaction that chemically decomposes waste plastics and returns them to plastics or monomers. When performing the raw material / monomerization reaction, as the mixture containing a plurality of types of resins in this embodiment, it is preferable to use resins composed of polyethylene, polypropylene, polystyrene, and polyvinyl chloride. As resin A, it is preferable to select polyvinyl chloride, and as resin B, it is preferable to select polyethylene, polypropylene, and polystyrene.

Example

[0063] Hereinafter, the present invention will be described more specifically by way of examples, but the present invention is not limited to the following examples. Note that Example 3 is a reference example.

[0064] <Resin> As the resin to be dissolved, the following resins were used. · Polyvinyl chloride (Product name: KVC 933J-N, manufactured by Showa Chemical Industry Co., Ltd., density: 1.325 g / cm 3 ) · Polystyrene (Product name: Toyo Styrene GP G201C, manufactured by Toyo Styrene Co., Ltd., density: 1.040 g / cm 3 ) · Low-density polyethylene (Product name: Novatec LD LJ802, manufactured by Japan Polyethylene Corporation, density: 0.918 g / cm 3 ) Hereinafter, polyvinyl chloride is represented as PVC, polystyrene as PS, and low-density polyethylene as LDPE (the same applies in Tables 1 and 3). Since PVC, PS, and LDPE differ in shape and color, in the examples described later, it is possible to visually determine which resin has dissolved.

[0065] <Solvent> As the solvent for dissolving the resin, the following solvents were used. · Light cracked gas oil · Orange oil (manufactured by Fujifilm Wako Pure Chemical Corporation, boiling point: 177 °C, density: 0.845 g / cm 3 ) · Light aromatic solvent (Product name: Swazol 1000, manufactured by Maruzen Petrochemical Co., Ltd., boiling point range: 160 - 180 °C, density: 0.875 g / cm 3 ) Light cracked gas oil is a light fraction among the gas oil fractions obtained by fluid catalytic cracking reaction (boiling point range: 175 - 365 °C). Hereinafter, light cracked gas oil is represented as LCO (the same applies in Tables 2 and 3).

[0066] <HPS value, R 0 etc. calculation> Regarding the above resin, using HSPiP, Hansen spheres were determined by the Hansen sphere method, and the HSP value and R 0 were obtained. The HSP value and R 0 of the resin are shown in Table 1. Similarly, regarding the above solvent, using HSPiP, Hansen spheres were determined by the Hansen sphere method, and the HSP value was obtained. The HSP value of the solvent is shown in Table 2. Note that the determination of solubility when obtaining Hansen spheres was based on 25 °C.

[0067] <Measurement of chlorine content> The chlorine concentration in the solutions obtained in Examples 1 - 4 and Comparative Examples 1 and 2 described below was measured using a trace chlorine - sulfur apparatus (TCL - 2100V, manufactured by Mitsubishi Chemical Analytic Co., Ltd.).

[0068]

Table 1

[0069]

Table 2

[0070] [Example 1] PVC was selected as resin A1, PS was selected as resin B1, and LCO was selected as the solvent. The HSP value of PVC and the HSP value of LCO were respectively calculated according to (δd 2 , δp 2 , δh 2 ) and (δd 1 , δp 1 , δh 1) was substituted into it to obtain the HSP value distance (Ra(A1)) between PVC and LCO. Furthermore, the relative energy difference RED(A1) based on the Hansen solubility parameter of LCO with respect to PVC was obtained from R of PVC and Ra(A1). Similarly, the HSP value of PS and the HSP value of LCO were respectively substituted into (δd 0 of Equation 1 above, δp 2 , δh 2 ) and (δd 2 , δp 1 , δh 1 ) to obtain the HSP value distance (Ra(B1)) between PS and LCO. Furthermore, the relative energy difference RED(B1) based on the Hansen solubility parameter of LCO with respect to PS was obtained from R of PS and Ra(B1). Ra(A1), RED(A1), Ra(B1), and RED(B1) are shown in Table 3. 1 ) to obtain the HSP value distance (Ra(B1)) between PS and LCO. Furthermore, the relative energy difference RED(B1) based on the Hansen solubility parameter of LCO with respect to PS was obtained from R of PS and Ra(B1). Ra(A1), RED(A1), Ra(B1), and RED(B1) are shown in Table 3. 0 and Ra(B1) to obtain the relative energy difference RED(B1) based on the Hansen solubility parameter of LCO with respect to PS. Ra(A1), RED(A1), Ra(B1), and RED(B1) are shown in Table 3. To 5 g of a mixture of PVC and 5 g of PS, 90 g of LCO was added, and stirring treatment was carried out at 25 °C for 60 minutes. When the dissolution state was visually observed, PS was completely dissolved, and solid PVC was confirmed. The amount of chlorine in the solution is shown in Table 3.

[0071] [Example 2] PVC was selected as resin A1, PS was selected as resin B1, and orange oil was selected as the solvent. The HSP value of PVC and the HSP value of orange oil were respectively substituted into (δd 2 , δp 2 , δh 2 ) and (δd 1 , δp 1 , δh 1 ) of Equation 1 above to obtain the HSP value distance (Ra(A1)) between PVC and orange oil. Furthermore, the relative energy difference RED(A1) based on the Hansen solubility parameter of orange oil with respect to PVC was obtained from R of PVC and Ra(A1). Similarly, the HSP value of PS and the HSP value of orange oil were respectively substituted into (δd 0 , δp 2 , δh 2 ) and (δd 2 , δp 1 , δh 1 , δh 1) was substituted into the formula, and the HSP value distance (Ra(B1)) between PS and orange oil was determined. Furthermore, RED(B1), which is the relative energy difference based on the Hansen solubility parameters of orange oil with respect to PS, was determined from R 0 and Ra(B1). Ra(A1), RED(A1), Ra(B1), and RED(B1) are shown in Table 3. To a mixture of 5 g of PVC and 5 g of PS, 90 g of orange oil was added, and the mixture was stirred at 25 °C for 60 minutes. When the dissolution state was visually observed, PS was completely dissolved in orange oil, and solid PVC was confirmed. The amount of chlorine in the solution is shown in Table 3.

[0072] [Example 3] PVC was selected as resin A1, LDPE was selected as resin B2, and orange oil was selected as the solvent. The HSP values of PVC and orange oil were respectively substituted into (δd 2 , δp 2 , δh 2 ) and (δd 1 , δp 1 , δh 1 ) of Equation 1 above to determine the HSP value distance (Ra(A1)) between PVC and orange oil. Furthermore, RED(A1), which is the relative energy difference based on the Hansen solubility parameters of orange oil with respect to PVC, was determined from the R 0 and Ra(A1) of PVC. Similarly, the HSP values of LDPE and orange oil were respectively substituted into (δd 2 , δp 2 , δh 2 ) and (δd 1 , δp 1 , δh 1 ) of Equation 1 above to determine the HSP value distance (Ra(B2)) between LDPE and orange oil. Furthermore, RED(B2), which is the relative energy difference based on the Hansen solubility parameters of orange oil with respect to LDPE, was determined from the R 0 and Ra(B2) of LDPE. Ra(A1), RED(A1), Ra(B2), and RED(B2) are shown in Table 3. To 5 g of a mixture of PVC and 5 g of LDPE, 90 g of orange oil was added, and stirring treatment was carried out at 25 °C for 60 minutes. When the dissolution state was visually observed, LDPE was completely dissolved, and solid PVC was confirmed. The chlorine amount in the solution is shown in Table 3.

[0073] [Example 4] PVC was selected as resin A1, PS was selected as resin B1, LDPE was selected as resin B2, and orange oil was selected as the solvent. The HSP values of PVC and orange oil were respectively substituted into (δd 2 , δp 2 , δh 2 ) and (δd 1 , δp 1 , δh 1 ) of Formula 1 above to obtain the HSP value distance (Ra(A1)) between PVC and orange oil. Furthermore, RED(A1), which is the relative energy difference based on the Hansen solubility parameter of orange oil with respect to PVC, was obtained from the R 0 and Ra(A1) of PVC. Similarly, the HSP values of PS and orange oil were respectively substituted into (δd 2 , δp 2 , δh 2 ) and (δd 1 , δp 1 , δh 1 ) of Formula 1 above to obtain the HSP value distance (Ra(B1)) between PS and orange oil. Furthermore, RED(B1), which is the relative energy difference based on the Hansen solubility parameter of orange oil with respect to PS, was obtained from the R 0 and Ra(B1) of PS. Furthermore, the HSP values of LDPE and orange oil were respectively substituted into (δd 2 , δp 2 , δh 2 ) and (δd 1 , δp 1 , δh 1 ) of Formula 1 above to obtain the HSP value distance (Ra(B2)) between LDPE and orange oil. Furthermore, the R 0And the relative energy difference RED(B2) based on the Hansen solubility parameter of orange oil with respect to PS was determined from Ra(B2). Ra(A1), RED(A1), Ra(B1), RED(B1), Ra(B2), and RED(B2) are shown in Table 3. To a mixture of 5 g of PVC, 5 g of PS, and 5 g of LDPE, 85 g of orange oil was added, and stirring treatment was carried out at 25 °C for 60 minutes. When the dissolution state was visually observed, PS and LDPE were completely dissolved, and solid PVC was confirmed. The chlorine amount in the solution is shown in Table 3.

[0074] [Comparative Example 1] PVC was selected as resin A1, LDPE was selected as resin B2, and LCO was selected as the solvent. The HSP values of PVC and LCO were respectively substituted into (δd 2 , δp 2 , δh 2 ) and (δd 1 , δp 1 , δh 1 ) of Formula 1 to obtain the HSP value distance (Ra(A1)) between PVC and LCO. Further, RED(A1), which is the relative energy difference based on the Hansen solubility parameter of LCO with respect to PVC from the R 0 and Ra(A1) of PVC, was determined. Similarly, the HSP values of LDPE and LCO were respectively substituted into (δd 2 , δp 2 , δh 2 ) and (δd 1 , δp 1 , δh 1 ) of Formula 1 to obtain the HSP value distance (Ra(B2)) between LDPE and LCO. Further, RED(B2), which is the relative energy difference based on the Hansen solubility parameter of LCO with respect to LDPE from the R 0 and Ra(B2) of LDPE, was determined. Ra(A1), RED(A1), Ra(B2), and RED(B2) are shown in Table 3. To a mixture of 5 g of PVC and 5 g of LDPE, 90 g of LCO was added, and stirring treatment was carried out at 25 °C for 60 minutes. When the dissolution state was visually observed, solid PVC and LDPE were confirmed. The chlorine amount in the solution is shown in Table 3.

[0075] [Comparative Example 2] PVC was selected as Resin A1, LDPE was selected as Resin B2, and Swazol 1000 was selected as the solvent. The HSP values of PVC and Swazol 1000 were respectively substituted into (δd 2 , δp 2 , δh 2 ) and (δd 1 , δp 1 , δh 1 ) of Formula 1 above to obtain the HSP value distance (Ra(A1)) between PVC and Swazol 1000. Furthermore, RED(A1), which is the relative energy difference based on the Hansen solubility parameter of Swazol 1000 with respect to PVC, was obtained from the R 0 and Ra(A1) of PVC. Similarly, the HSP values of LDPE and Swazol 1000 were respectively substituted into (δd 2 , δp 2 , δh 2 ) and (δd 1 , δp 1 , δh 1 ) of Formula 1 above to obtain the HSP value distance (Ra(B2)) between LDPE and Swazol 1000. Furthermore, RED(B2), which is the relative energy difference based on the Hansen solubility parameter of Swazol 1000 with respect to LDPE, was obtained from the R 0 and Ra(B2) of LDPE. Ra(A1), RED(A1), Ra(B2), and RED(B2) are shown in Table 3. To a mixture of 5 g of PVC and 5 g of LDPE, 90 g of Swazol 1000 was added, and the mixture was stirred at 25°C for 60 minutes. When the dissolution state was visually observed, solid PVC and LDPE were confirmed. The amount of chlorine in the solution is shown in Table 3.

[0076]

Table 3

[0077] In Examples 1 to 4 in which a solvent was selected such that the RED based on the Hansen solubility parameter for Resin A1 was greater than 1 and the RED based on the Hansen solubility parameter for Resin B1 and / or Resin B2 was 1 or less, Resin A1 could not be dissolved, but only Resin B1 and / or Resin B2 could be dissolved. On the other hand, in Comparative Examples 1 and 2 in which a solvent was selected such that the RED based on the Hansen solubility parameter for Resin A1 was greater than 1 and the RED based on the Hansen solubility parameter for Resin B2 was greater than 1, although Resin A1 was not dissolved, Resin B2 could not be dissolved either.

Claims

1. A method for dissolving resins, which comprises selecting a solvent (excluding a solvent consisting only of xylene) that does not dissolve a specific resin but dissolves resins other than the specific resin from a mixture containing a plurality of types of resins, wherein the relative energy difference based on the Hansen solubility parameter for the specific resin is greater than 1, and the relative energy difference based on the Hansen solubility parameter for resins other than the specific resin is 1 or less, and bringing the mixture into contact with the solvent to dissolve the resins other than the specific resin. The method is for producing a resin dissolution solution used for chemical recycling, wherein the solvent contains two or more solvents, and the resins other than the specific resin include polypropylene or polystyrene.

2. The method for producing a resin dissolution solution according to claim 1, wherein the specific resin contains a chlorine element.

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