JP7577919B2 - Polyurethane resin-forming composition for membrane sealant, and membrane sealant and membrane module using same - Google Patents

Description

This disclosure relates to a polyurethane resin-forming composition for membrane sealing materials, and to membrane sealing materials and membrane modules using the same.

Among the hollow fiber membranes used in hollow fiber membrane modules, there is a glycerin-containing hollow fiber membrane in which a retention agent (glycerin) is used to maintain the pores of the membrane. However, in the case of the glycerin-containing hollow fiber membrane, when a polyurethane resin-forming composition containing diphenylmethane diisocyanate (hereinafter abbreviated as MDI) is used during casting, it is known that a low molecular weight reaction product between MDI and glycerin is generated, and this reaction product dissolves into the liquid present around the hollow fiber membrane.

Patent Document 1 discloses a polyurethane resin-forming composition for use as a sealant for membrane modules, which contains a polyisocyanate component (base) containing an isocyanate-terminated prepolymer obtained from a reaction product of MDI and castor oil, and a polyol component (curing agent). Patent Document 1 further discloses that the amount of elution of polyurethane resin obtained from such a polyurethane resin-forming composition for use as a sealant is reduced.

In addition, allophanate group-containing polyisocyanate prepolymers derived from MDI and monol have low viscosity, little precipitation of MDI at low temperatures, and are easy to handle, and therefore are useful and widely used in the fields of adhesives and sealing materials.
Patent Document 2 discloses that an allophanate group-containing polyisocyanate prepolymer derived from MDI and a polyether monol has a low viscosity, and that an elastomer obtained from the prepolymer has excellent mechanical properties.

Japanese Patent Application Publication No. 6-25383 JP 2009-030059 A

However, the composition disclosed in Patent Document 1 has a high viscosity of the base agent, and there is a demand for a lower viscosity. Therefore, the composition disclosed in Patent Document 1 has a problem that the initial viscosity of the mixture of the base agent and the curing agent is high, which may cause filling defects during molding.
Furthermore, the composition disclosed in Patent Document 2 has a problem in that a large amount of eluted material is eluted from the urethane resin, and it is desired to reduce the amount of eluted material.
Therefore, one embodiment of the present disclosure is to provide a polyurethane resin-forming composition that contributes to the formation of a urethane resin that has low viscosity and excellent castability, and that reduces the amount of water elution of the low-molecular-weight reaction product of MDI and glycerin and the amount of solvent elution of the molded product, as well as a sealing material and a membrane module that use the forming composition.

The present disclosure includes the following embodiments.
(1): an allophanate group-containing polyisocyanate prepolymer (A);
A polyurethane resin-forming composition for a membrane sealant, comprising:
The polyisocyanate prepolymer (A) is
Diphenylmethane diisocyanate (a1),
and an active hydrogen-containing compound (a2),
The curing agent (B) contains a castor oil polymerized polyol (b1),
The castor oil polymerized polyol (b1) contains a castor oil polymer,
A polyurethane resin-forming composition for a membrane sealant, characterized in that the crosslinking group density is 0.65 mmol/g or more based on the total mass of the polyisocyanate prepolymer (A) and the curing agent (B).
(2): an allophanate group-containing polyisocyanate prepolymer (A);
A polyurethane resin-forming composition for a membrane sealant, comprising:
The polyisocyanate prepolymer (A) is
Diphenylmethane diisocyanate (a1),
and an active hydrogen-containing compound (a2),
The curing agent (B) contains a castor oil polymerized polyol (b1),
The castor oil polymerized polyol (b1) contains a castor oil polymer,
The content of the castor oil polymer in the polyurethane resin-forming composition for a membrane sealing material is 1% by mass or more and 35% by mass or less, based on the total mass of the polyisocyanate prepolymer (A) and the curing agent (B).
(3): A membrane sealant comprising a cured product of the polyurethane resin-forming composition for a membrane sealant according to (1) or (2) above.
(4): A main body portion,
A membrane,
A membrane sealant that seals a gap between the main body and the membrane,
A membrane module, wherein the membrane sealing material is the membrane sealing material described in (3) above.

According to one embodiment of the present disclosure, it is possible to provide a polyurethane resin forming composition that contributes to the formation of a urethane resin that has low viscosity and excellent castability, and in which the amount of water elution of the low-molecular-weight reaction product of diphenylmethane diisocyanate and glycerin and the amount of solvent elution of the molded product are reduced, as well as a sealing material and a membrane module using the forming composition.

FIG. 1 is a conceptual diagram illustrating an example of a configuration of a membrane module according to an embodiment of the present disclosure.

Below, we will explain in detail an exemplary embodiment for implementing the present invention.

[First embodiment of polyurethane resin-forming composition for membrane sealant]
The polyurethane resin-forming composition for a membrane sealant according to one embodiment of the present disclosure comprises:
An allophanate group-containing polyisocyanate prepolymer (A),
A polyurethane resin-forming composition for a membrane sealant, comprising:
The allophanate group-containing polyisocyanate prepolymer (A) is
Diphenylmethane diisocyanate (a1),
and an active hydrogen-containing compound (a2),
The curing agent (B) contains a castor oil polymerized polyol (b1) containing a castor oil polymer,
The crosslinking group density is 0.65 mmol/g or more based on the total mass of the polyisocyanate prepolymer (A) and the curing agent (B).

<Allophanate Group-Containing Polyisocyanate Prepolymer (A)>
The allophanate group-containing polyisocyanate prepolymer (A) contains a reaction product of diphenylmethane diisocyanate (a1) and an active hydrogen-containing compound (a2).

<<Diphenylmethane diisocyanate (a1)>>
As diphenylmethane diisocyanate (a1), any commonly available diphenylmethane diisocyanate (hereinafter also referred to as MDI) monomer can be used. The isomers of the MDI monomer are usually 0% by mass or more and 5% by mass or less of 2,2'-MDI, 0% by mass or more and 95% by mass or less of 2,4'-MDI, and 5% by mass or more and 100% by mass or less of 4,4'-MDI.
As MDI (a1), it is preferable to use the above-mentioned MDI in order to obtain an allophanate group-containing polyisocyanate prepolymer (A) with a lower viscosity. However, if a certain degree of high viscosity of the allophanate group-containing polyisocyanate prepolymer (A) is acceptable, polymethylene polyphenylene polyisocyanate (polymeric MDI) can also be used as MDI (a1). In that case, the content of polymethylene polyphenylene polyisocyanate in the isocyanate component used is preferably 0% by mass or more and 50% by mass or less. If it is 50% by mass or less, the viscosity is sufficiently low and the generation of insoluble matter can be more highly suppressed.

<<Active hydrogen-containing compound (a2)>>
The active hydrogen-containing compound (a2) is not particularly limited as long as it is a compound containing active hydrogen. Examples of the active hydrogen-containing compound (a2) include monoalcohols, castor oil, castor oil-based modified polyols, low molecular weight alcohols, and the like. Examples of the monoalcohol include aliphatic monoalcohols, aromatic monoalcohols, alicyclic monoalcohols, aromatic monoalcohols, and the like. Examples of the alkyl group include aliphatic monoalcohols and polyoxypropylene glycol monoalkyl ethers.

Examples of aliphatic monoalcohols include methanol, ethanol, 1- and 2-propanol, 1- and 2-butanol, 1-pentanol, 1-hexanol, 2-methyl-1-pentanol, 4-methyl-2-pentanol, 2-ethyl-1-butanol, 1-heptanol, 1-octanol, 2-octanol, 2-ethylhexanol, 3,5-dimethyl-1-hexanol, 2,2,4-trimethyl-1-pentanol, 1-nonanol, 2,6 aliphatic monoalcohols such as 1-dimethyl-4-heptanol, 1-decanol, 1-undecanol, 1-dodecanol, 1-tridecanol, 1-tetradecanol, 1-pentadecanol, 1-hexadecanol, 1-heptadecanol, 1-octadecanol, 1-nonadecanol, 1-eicosanol, 1-hexacosanol, 1-heptatricontanol, 1-oleyl alcohol, and 2-octyldodecanol, and mixtures thereof.
The number average molecular weight of the aliphatic monoalcohol is preferably from 32 to 1500, and more preferably from 100 to 1000. When the molecular weight is within this range, the polyurethane resin has even better moldability and adhesive strength.

Examples of aromatic monoalcohols include phenol and cresol.

Examples of alicyclic monoalcohols include cyclohexanol and methylcyclohexanol.

Examples of aromatic aliphatic monoalcohols include benzyl alcohol.

Examples of the polyoxypropylene glycol monoalkyl ether include the reaction products of the above-mentioned aliphatic monoalcohols with polyoxypropylene glycol, such as polyoxypropylene methyl ether, polyoxypropylene ethyl ether, polyoxypropylene butyl ether, polyoxypropylene-2-ethylhexyl ether, polyoxypropylene oleyl ether, polyoxypropylene-2-octyldodecaether, and mixtures thereof.
The number average molecular weight of the polyoxypropylene glycol monoalkyl ether is preferably 90 or more and 1500 or less. From the viewpoint of achieving even better moldability and adhesive strength of the polyurethane resin, the number average molecular weight is more preferably 150 or more and 1000 or less.

The castor oil-based modified polyol includes linear or branched castor oil-based modified polyols obtained by reacting castor oil or castor oil fatty acid with at least one polyol selected from the group consisting of low molecular weight polyols and polyether polyols.Specific examples include diglycerides and monoglycerides of castor oil fatty acid; mono-, di-, and triesters of castor oil fatty acid and trimethylolalkane; mono-, di-, and triesters of castor oil fatty acid and polypropylene glycol; and the like.
The main component of castor oil is triglyceride of ricinoleic acid, and castor oil includes hydrogenated castor oil. The main component of castor oil fatty acid is ricinoleic acid, and castor oil fatty acid includes hydrogenated castor oil fatty acid.

Examples of the trimethylolalkane include trimethylolmethane, trimethylolethane, trimethylolpropane, trimethylolbutane, trimethylolpentane, trimethylolhexane, trimethylolheptane, trimethyloloctane, trimethylolnonane, and trimethyloldecane.

The number average molecular weight of the castor oil-based modified polyol is preferably 400 to 3000, more preferably 500 to 2500. By using a castor oil-based modified polyol with a number average molecular weight of 400 to 3000, it is possible to form a cured resin that has even better physical properties, particularly mechanical properties, required for a membrane sealant.

The average hydroxyl value of castor oil and castor oil-based modified polyol is preferably 20 mgKOH/g or more and 300 mgKOH/g or less, and more preferably 40 mgKOH/g or more and 250 mgKOH/g or less. By using a castor oil-based modified polyol with an average hydroxyl value of 20 mgKOH/g or more and 300 mgKOH/g or less, it is possible to form a cured resin with even better physical properties, particularly mechanical properties, required for a membrane sealing material. Furthermore, it is possible to improve the productivity of the membrane sealing material, and ultimately the productivity of the hollow fiber membrane module.

Examples of low molecular weight polyols include divalent polyols such as ethylene glycol, diethylene glycol, propylene glycol, 1,2-, 1,3- or 1,4-butanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol, 1,10-decanediol, neopentyl glycol, and hydrogenated bisphenol A, and trivalent to octavalent polyols such as glycerin, trimethylolpropane, hexanetriol, pentaerythritol, sorbitol, and sucrose. The number average molecular weight of the low molecular weight polyol is preferably 50 or more and 200 or less.

Examples of polyether-based polyols include alkylene oxide (alkylene oxide having 2 to 8 carbon atoms, such as ethylene oxide, propylene oxide, butylene oxide, etc.) adducts of the above-mentioned low molecular weight polyols, and ring-opening polymers of alkylene oxides, and more specifically, polypropylene glycol, polyethylene glycol, polytetramethylene ether glycol, and copolymers of ethylene oxide and propylene oxide, etc. The number average molecular weight of the polyether-based polyol is preferably 200 to 7,000, and more preferably 500 to 5,000, from the viewpoint of further excellent moldability during the production of the membrane sealant.

The polyester polyol may be, for example, a polyester polyol obtained by condensation polymerization of a polycarboxylic acid and a polyol.
Examples of polycarboxylic acids used in the polyester polyols include adipic acid, azelaic acid, dodecanedioic acid, maleic acid, fumaric acid, itaconic acid, dimerized linoleic acid, phthalic acid, isophthalic acid, terephthalic acid, and other aliphatic saturated and unsaturated polycarboxylic acids, as well as aromatic polycarboxylic acids.
Examples of the polyol used in the polyester polyol include the low molecular weight polyols and polyether polyols described above.

The number average molecular weight of the polyester polyol is preferably 200 to 5,000, more preferably 500 to 3,000. By using a polyester polyol with a number average molecular weight of 200 to 5,000, the molding processability during the formation of the membrane sealant is particularly excellent.

Examples of polylactone-based polyols include polyols obtained by addition polymerization of ε-caprolactone, α-methyl-ε-caprolactone, ε-methyl-ε-caprolactone, β-methyl-δ-valerolactone, etc., to a glycol or triol polymerization initiator in the presence of a catalyst such as an organometallic compound, a metal chelate compound, or a fatty acid metal acyl compound. The number average molecular weight of the polylactone-based polyol is preferably 200 to 5,000, more preferably 500 to 3,000. By using a polylactone-based polyol with a number average molecular weight of 200 to 5,000, the molding processability during the formation of the membrane sealant is particularly excellent.

Examples of polyolefin polyols include polybutadiene polyols in which hydroxyl groups have been introduced at the ends of polybutadiene or copolymers of butadiene and styrene or acrylonitrile. Other examples include polyether ester polyols obtained by addition reaction of alkylene oxides, such as ethylene oxide and propylene oxide, to polyesters having carboxyl and hydroxyl groups at their ends.

Among these, as the active hydrogen-containing compound (a2), taking into consideration compatibility with the curing agent (B), aliphatic alcohols having 10 or more carbon atoms, castor oil, or castor oil-based modified polyols are preferred.

<<Method for Producing Allophanate Group-Containing Polyisocyanate Prepolymer (A)>>
The allophanate group-containing polyisocyanate prepolymer (A) is preferably one obtained, for example, by subjecting diphenylmethane diisocyanate (a1) to a urethanization reaction with an active hydrogen-containing compound (a2), followed by addition of a predetermined amount of a catalyst (a3) to convert the resulting product to an allophanate, and then terminating the reaction with a catalyst poison (a4).

<<Catalyst (a3)>>
Examples of the catalyst (a3) include zinc acetylacetonate; metal carboxylates of zinc, lead, tin, copper, cobalt, or the like with carboxylic acids, and mixtures thereof; tertiary amines, tertiary amino alcohols, quaternary ammonium salts, and mixtures thereof; and the like.
The amount of catalyst (a3) added is preferably in the range of 1 ppm to 500 ppm, more preferably 5 ppm to 300 ppm, based on the total mass of diphenylmethane diisocyanate (a1) and active hydrogen-containing compound (a2). At 1 ppm or more, the reaction becomes more rapid, and at 500 ppm or less, coloration of the prepolymer is more effectively suppressed, which is preferable.

<<Active methylene compounds>>
In the present disclosure, in the allophanation reaction using a tertiary amine or a quaternary ammonium salt, when the reaction is rapid and difficult to control, it is effective to add at least one selected from the group consisting of carboxylic acid amides, sulfonic acid amides, and active methylene compounds represented by formula (1).

In the formula,
R ¹ is any one selected from the group consisting of a hydrogen atom, an alkyl group, an alkenyl group, a cycloalkyl group, an arylalkyl group, and an aryl group;
^R2 and ^R3 are each independently any one selected from the group consisting of a hydroxyl group, an alkyl group, an alkenyl group, a cycloalkyl group, an arylalkyl group, an aryl group, an oxyalkyl group, an oxyalkenyl group, an oxycycloalkyl group, an oxyarylalkyl group, and an oxyaryl group.

Examples of carboxylic acid amides include formamide, acetamide, propionic acid amide, butanoic acid amide, isobutanoic acid amide, hexanoic acid amide, octanoic acid amide, 2-ethylhexanoic acid amide, oleic acid amide, stearic acid amide, benzamide, 2-phenylacetamide, 4-methylbenzamide, 2-aminobenzamide, 3-aminobenzamide, 4-aminobenzamide, and mixtures thereof.

Examples of sulfonamides include methylsulfonamide, butylsulfonamide, t-butylsulfonamide, phenylsulfonamide, benzylsulfonamide, o-tolylsulfonamide, p-tolylsulfonamide, 3-aminophenylsulfonamide, 4-aminophenylsulfonamide, and mixtures thereof.

Specific examples of active methylene compounds represented by formula (1) include acetylacetone, 3-methyl-2,4-pentanedione, 3-ethyl-2,4-pentanedione, 3,5-heptanedione, 3,5-heptanedione, 6-methyl-2,4-heptanedione, methyl acetoacetate, ethyl acetoacetate, methyl 3-oxopentanoate, malonic acid, dimethyl malonate, diethyl malonate, etc. The active methylene compound may be a mixture of two or more of these.

It is also preferable that at least one selected from the group consisting of the above-mentioned carboxylic acid amides, sulfonic acid amides, and active methylene compounds represented by the above-mentioned formula (1) is added between immediately before the addition of the catalyst and 30 minutes after the addition of the catalyst.

The higher the temperature at which allophanate formation is carried out, the higher the proportion of allophanate groups produced and the lower the viscosity, but side reactions such as uretdione formation and carbodiimide formation are more likely to occur. In addition, since a reaction at a low temperature produces a large amount of isocyanurate groups and increases the viscosity, the reaction temperature is preferably 20°C or higher and 200°C or lower, and in order to keep the proportion of isocyanurate groups produced to 20 mol% or less and achieve an even lower viscosity, a temperature of 60°C or higher and 160°C or lower is preferred.

<<Catalyst poison (a4)>>
The catalyst poison (a4) is preferably an acidic substance. Examples of the catalyst poison (a4) include anhydrous hydrogen chloride, sulfuric acid, phosphoric acid, monoalkyl sulfate esters, alkyl sulfonic acids, alkylbenzene sulfonic acids, mono- or dialkyl phosphate esters, chlorides, etc. The amount of the catalyst poison (a4) added is preferably at least one equivalent to the number of moles of the catalyst (a3), and more preferably 1.0 to 1.0 times the number of moles of the catalyst (a3). It is more preferable to add 5 molar equivalents or less.

<<MDI monomer content>>
The content of MDI monomer is preferably 25 mass % or less based on the total amount of the polyurethane resin-forming composition for a membrane sealant in order to further reduce low molecular weight reaction products between MDI and glycerin.

<<Reaction temperature>>
The urethane reaction is preferably carried out until the target NCO content is reached at a temperature in the range of 40° C. to 80° C. At 40° C. or higher, crystal precipitation of the monomer MDI can be more effectively suppressed, and at 80° C. or lower, the generation of by-products can be more effectively suppressed.

The allophanate reaction is preferably carried out at a temperature in the range of 90°C to 130°C until the target NCO content is reached. At temperatures above 90°C, the reaction is more rapid, and at temperatures below 130°C, the production of by-products can be further suppressed.

<<Isocyanate group content>>
The content of isocyanate groups in the polyisocyanate prepolymer (A) is preferably from 13.0% by mass to 21.0% by mass, more preferably from 13.5% by mass to 20.5% by mass, and particularly preferably from 14.0% by mass to 20.0% by mass. Within these ranges, the polyurethane resin is further excellent in moldability and adhesive strength.

<Curing Agent (B)>
The curing agent (B) contains a castor oil polymerized polyol (b1).
The curing agent (B) is
Castor oil polymerized polyol (b1),
and at least one polyol (b2) selected from the group consisting of castor oil and castor oil-based modified polyols.
Furthermore, the curing agent (B) is
Castor oil polymerized polyol (b1),
At least one polyol (b2) selected from the group consisting of castor oil and castor oil-based modified polyols;
and a hydroxyl group-containing amine compound (b3) other than the castor oil polymerized polyol (b1) and the polyol (b2);
It is more preferable that the content of the hydroxyl group-containing amine compound (b3) in the curing agent (B) is 35 mass % or less.

<<Castor oil polymerized polyol (b1)>>
The castor oil polymerized polyol (b1) contains a castor oil polymer. By containing the castor oil polymerized polyol (b1), excellent effects are exhibited in terms of improving processability during molding, suppressing elution, and the like.

The content of the castor oil polymer is preferably 1.0% by mass or more and 35.0% by mass or less, more preferably 2.0% by mass or more and 25.0% by mass or less, and particularly preferably 3.0% by mass or more and 15.0% by mass or less, based on the total mass of the polyisocyanate prepolymer (A) and the curing agent (B). Within these ranges, the polyurethane resin is more excellent in terms of moldability and reduction of the amount of elution.

The castor oil polymerized polyol (b1) may contain castor oil polymers and castor oil (non-polymerized). In this case, the content of castor oil polymers in the castor oil polymerized polyol (b1) can be calculated by, for example, regarding those having a molecular weight of 1500 or more as castor oil polymers as measured by GPC (Gel Permeation Chromatography). However, the method of calculating the content of castor oil polymers is not limited to this, and any method may be used as long as it can accurately distinguish between castor oil polymers and castor oil (non-polymerized).

<<At least one polyol (b2) selected from the group consisting of castor oil and castor oil-based modified polyols>>
The castor oil and the castor oil-based modified polyol (b2) are not particularly limited.
Castor oil is simply castor oil.
Examples of the castor oil-based modified polyol include the same castor oil-based modified polyols as those exemplified as the active hydrogen-containing compound (a2) described above.

<<Hydroxyl-containing amine compound (b3)>>
The hydroxyl-containing amine compound (b3) is a hydroxyl-containing amine compound other than the castor oil polymerized polyol (b1) and at least one polyol (b2) selected from the group consisting of castor oil and castor oil-based modified polyol. That is, the hydroxyl-containing amine compound (b3) is a hydroxyl-containing amine compound that does not fall under either the castor oil polymerized polyol (b1) or the polyol (b2).

Examples of hydroxyl group-containing amine compounds (b3) include alkyldiethanolamines (e.g., linear or branched butyldiethanolamine, hexyldiethanolamine, octyldiethanolamine, lauryldiethanolamine, myristyldiethanolamine, cetyldiethanolamine, stearyldiethanolamine, etc.), low molecular weight polyamines, low molecular weight amino alcohols (e.g., oxyalkylated derivatives of amino compounds such as N,N,N',N'-tetrakis[2-hydroxypropyl]ethylenediamine, N,N,N',N'-tetrakis[2-hydroxyethyl]ethylenediamine, which are adducts of propylene oxide or ethylene oxide to ethylenediamine; mono-, di-, and triethanolamines; N-methyl-N,N'-diethanolamine, etc.), and other amine compounds such as amino alcohol derivatives. Among these, preferred are propylene oxide or ethylene oxide adducts of amino compounds such as ethylenediamine, and most preferred is N,N,N',N'-tetrakis[2-hydroxypropyl]ethylenediamine. The use of N,N,N',N'-tetrakis[2-hydroxypropyl]ethylenediamine provides further benefits, such as improved processability during molding and reduced elution.

In addition, the content of the hydroxyl-containing amine compound (b3) in the curing agent (B) is preferably 35% by mass or less, more preferably 5% by mass or more and 34% by mass or less, and particularly preferably 10% by mass or more and 33% by mass or less. When the content of the hydroxyl-containing amine compound (b3) in the curing agent (B) is 5% by mass or more, the hydroxyl-containing amine compound (b3) exhibits a better function of curing promotion and exerts a further effect. When the ratio of the hydroxyl-containing amine compound (b3) in the curing agent (B) is 35% by mass or less, the reactivity is further suppressed from becoming too high, the workability is further improved, the filling property is ensured, and the hardness of the obtained membrane sealant is further suppressed from becoming too high.

<<Active hydrogen-containing compound (b4)>>
The curing agent (B) contains an active hydrogen-containing compound other than the castor oil polymerized polyol (b1), the polyol (b2), and the hydroxyl group-containing amine compound (b3) (hereinafter referred to as "active hydrogen-containing compound (b4)"). As the active hydrogen-containing compound (b4), the various polyols exemplified as the active hydrogen-containing compound (a2) can be used.

In the curing agent (B), the mass ratio (Mb2)/(Mb4) of the content Mb2 of at least one polyol (b2) selected from the group consisting of castor oil and castor oil-based modified polyols to the content Mb4 of the active hydrogen-containing compound (b4) is preferably 50/50 or more and 100/0 or less, and is particularly preferably 100/0. In other words, it is particularly preferable that the curing agent (B) consists of only castor oil polymerized polyol (b1) and polyol (b2), or only castor oil polymerized polyol (b1), polyol (b2), and hydroxyl group-containing amine compound (b3).

In addition, when the hydroxyl-containing amine compound (b3) is taken into consideration, when the content of the castor oil polymerized polyol (b1) is Mb1 and the content of the hydroxyl-containing amine compound (b3) is Mb3, the mass ratio (Mb3)/{(Mb1)+(Mb2)} is preferably 5/95 or more and 35/65 or less, and from the viewpoint of curing property and filling property, it is more preferably 10/90 or more and 33/67 or less.

The hydroxyl value of the curing agent (B) is preferably 50 mgKOH/g or more and 1000 mgKOH/g or less, and from the viewpoint of easy handling of the curing agent (B), it is more preferable that it is 75 mgKOH/g or more and 750 mgKOH/g or less. From the viewpoint of excellent moldability and adhesive strength of the polyurethane resin, it is most preferable that the hydroxyl value of the curing agent (B) is 100 mgKOH/g or more and 500 mgKOH/g or less.

The viscosity of the curing agent (B) at 25°C is preferably 100 mPa·s or more and 6000 mPa·s or less, and from the viewpoint of easy handling of the curing agent (B), it is more preferable that it is 150 mPa·s or more and 4000 mPa·s or less. From the viewpoint of excellent moldability of the polyurethane resin, it is most preferable that the viscosity of the curing agent (B) at 25°C is 200 mPa·s or more and 2000 mPa·s or less.

<Crosslinking group density>
In order to suppress the amount of dissolution into the solvent, the crosslinking group density of the polyurethane resin-forming composition for membrane sealing material is preferably 0.65 mmol/g or more, more preferably 0.70 mmol/g or more, and particularly preferably 0.75 mmol/g or more and 1.20 or less, based on the total mass of the polyisocyanate prepolymer (A) and the curing agent (B). When the crosslinking group density is 1.20 or less, the molding processability becomes better.

The crosslinking group density means the total content density of groups capable of forming crosslinks and groups which have already formed crosslinks.
Therefore, when taking trifunctional polyol (for example, glycerin) as an example, one hydroxyl group in one molecule forms crosslinking, and the remaining two hydroxyl groups do not contribute to crosslinking, so in this case, the number of crosslinking groups is one. That is, in the case of the polyurethane resin-forming composition for membrane sealant containing trifunctional polyol, the content of the crosslinking group derived from trifunctional polyol is synonymous with the content of trifunctional polyol, since trifunctional polyol has one crosslinking group.

[Second embodiment of polyurethane resin-forming composition for membrane sealant]
Another embodiment of the present invention is a copolymer of an allophanate group-containing polyisocyanate prepolymer (A) and
A polyurethane resin-forming composition for a membrane sealant, comprising:
The polyisocyanate prepolymer (A) is
Diphenylmethane diisocyanate (a1),
and an active hydrogen-containing compound (a2),
The curing agent (B) contains a castor oil polymerized polyol (b1),
The castor oil polymerized polyol (b1) contains a castor oil polymer,
The content of the castor oil polymer is 1% by mass or more and 35% by mass or less based on the total mass of the polyisocyanate prepolymer (A) and the curing agent (B).
It should be noted that each component is similar to that of the first embodiment described above, and therefore a description thereof will be omitted.

According to each embodiment of the present disclosure, it is possible to provide a polyurethane resin forming composition that contributes to the formation of a urethane resin having low viscosity, excellent casting properties, and reduced water elution of the low molecular weight reaction product of diphenylmethane diisocyanate and glycerin, and reduced solvent elution of the molded product, as well as a membrane sealant and a membrane module using the forming composition.

<Membrane sealing material>
A membrane sealant according to one embodiment of the present disclosure includes a cured product of the above-mentioned polyurethane resin-forming composition for a membrane sealant.
The membrane sealant can be suitably formed by reacting and curing the isocyanate component constituting the polyisocyanate prepolymer (A) with the polyol component constituting the curing agent (B) under a temperature condition of 0° C. to 100° C., preferably 20° C. to 80° C., and more preferably 30° C. to 60° C. The gelation time of the membrane sealant can be shortened by molding in a high temperature range, but molding shrinkage is likely to occur, so the reaction temperature can be lowered by adding a catalyst to suppress molding shrinkage.

<Membrane module>
The membrane module according to one embodiment of the present disclosure comprises:
A main body portion,
A membrane,
A membrane sealant that seals a gap between the main body and the membrane,
The membrane sealant is the membrane sealant described above.

Next, a membrane module according to an embodiment of the present disclosure will be described in more detail with reference to the drawings.
FIG. 1 is a conceptual diagram showing an example of the configuration of a membrane module according to an embodiment of the present disclosure.
The membrane module (hollow fiber membrane module) 100 shown in Fig. 1 includes a housing (main body) 11, the inside of which is filled with a plurality of hollow fiber membranes (membranes) 13. For example, in the case of a hollow fiber membrane module used as a dialyzer, several thousand to several tens of thousands of hollow fiber membranes are filled.

The housing 11 has a cylindrical shape. A membrane sealant 19 is provided at each end of the interior of the housing 11 (the left and right ends in FIG. 1). The membrane sealant fills and seals the gaps between the hollow fiber membranes 13 and between the hollow fiber membranes 13 and the inner wall of the housing 11, and also binds multiple hollow fiber membranes 13 together.

In addition, a first fluid inlet 15 and a first fluid outlet 17 are provided on the side of the housing 11, through which a first fluid (gas or liquid) flows in and out of the housing 11. The first fluid that flows in from the first fluid inlet 15 passes through the gaps (outside the hollow fiber membranes) while contacting the multiple hollow fiber membranes 13 filled in the housing 11, and is discharged from the first fluid outlet 17. Since there is no membrane seal material 19 inside the hollow fiber membranes 13, a second fluid (gas or liquid) flows in and out of the hollow fiber membranes 13 through a second inlet (one end side) and a second outlet (other end side) provided in a cap member (not shown). Then, the first fluid and the second fluid come into contact with each other through the hollow fiber membranes 13, and material transfer occurs from one fluid to the other fluid (or from the other fluid to the one fluid). For example, in the case of a hollow fiber membrane type dialyzer, when the dialysis fluid comes into contact with the blood, waste products and excess water in the blood are transferred to the dialysis fluid.

The membrane module 100 shown in FIG. 1 is configured to include multiple hollow fiber membranes 13, with the membrane sealant 19 sealing the gaps at both ends of the membranes, but the membrane module according to this embodiment is not limited to such a configuration. For example, it may be a single or multiple membranes having various shapes such as flat membranes and spiral membranes. In addition, the membrane sealant is not limited to a configuration in which it is provided at both ends of the membrane, but may be provided only on a part of the membrane (one end if the membrane is hollow fiber-shaped), or may be provided on all ends of the membrane, for example, the entire outer edge of the flat membrane. Furthermore, the sealant may be provided on a part of the membrane other than the ends to seal it. In addition, the housing 11 of the membrane module 100 shown in FIG. 1 has a cylindrical shape, but may be any shape other than cylindrical.

The membrane module 100 seals the gaps between the hollow fiber membranes 13 at the end of the bundle of multiple hollow fiber membranes 13 with the polyurethane resin-forming composition for membrane sealing material described above, and hardens the composition to form the membrane sealing material described above (the gaps between the hollow fiber membranes are sealed by the membrane sealing material).

The membrane module according to one embodiment of the present disclosure effectively reduces the amount of elution, and can therefore be suitably used as a medical or water treatment module. Specific examples of membrane modules include plasma separation devices, artificial lungs, artificial kidneys, artificial livers, and household and industrial water treatment devices.

The present invention will be explained in more detail below with reference to examples and comparative examples. However, the present invention should not be interpreted as being limited in any way by these examples. In the following, "%" means "% by mass" unless otherwise specified.

The following components were used in the examples and comparative examples.
[Polyisocyanate prepolymer (A)]
a1-1: 4,4'-MDI (Millionate MT, manufactured by Tosoh Corporation),
Isocyanate group content = 33.6%)
a1-2: A mixture of 2,4'-MDI and 4,4'-MDI (Millionate NM, manufactured by Tosoh Corporation, isocyanate group content = 33.6%)
a1-3: Carbodiimide modified 4,4'-MDI (manufactured by Tosoh Corporation)
Millionate MTL-C, isocyanate group content = 28.6%,
Crosslinking group density = 0.45 mmol/g)
a2-1: Castor oil fatty acid methyl ester (COFA-MD, manufactured by Ito Oil Mills,
OHV=160mgKOH/g)
a2-2: Polypropylene glycol (PP-1000 manufactured by ADEKA Corporation,
OHV=111mgKOH/g)
a2-3: Isotridecanol (KH Neochem, OHV = 275 mg KOH/g)
a2-4: 2-octyldodecanol (Kao Corporation, Kalcol 200GD,
Hydroxyl value = 185 mg KOH / g)
a2-5: Castor oil (URIC H-30, manufactured by Ito Oil Co., Ltd.,
OHV=160mgKOH/g, viscosity (25°C)=690mPa・s,
Content of castor oil polymer having a number average molecular weight of 1500 or more: 1% or less;
Crosslinking group density = 0.74 mmol/g)
a3-1: Zinc acetylacetone (Tokyo Chemical Industry Co., Ltd.)
a3-2: 2-[{2-(dimethylamino)ethyl}methylamino]ethanol (manufactured by Tosoh Corporation, product name TOYOCAT RX5)
Active methylene compound: diethyl malonate (Tokyo Chemical Industry Co., Ltd.)
a4: Benzoyl chloride (Tokyo Chemical Industry Co., Ltd.)

[Curing agent (B)]
b1-1: Castor oil polymer (Polycaster #30 manufactured by Ito Oil Co., Ltd.)
OHV=155mgKOH/g, viscosity (25°C)=4800mPa・s,
Content of castor oil polymer having a number average molecular weight of 1500 or more: about 54%
Crosslinking group density = 1.84 mmol/g)
b2-1: Partially dehydrated castor oil (URIC H-41, manufactured by Ito Oil Mills,
OHV=120mgKOH/g, crosslinking group density=0mmol/g)
b3-1: N,N,N',N'-tetrakis[2-hydroxypropyl]ethylenediamine (ADEKA EDP-300, OHV = 760 mg KOH/g,
Viscosity (25°C) = 50000 mPa・s, crosslinking group density = 2.63 mmol/g)
b3-2: N-lauryldiethanolamine (Amit 102, manufactured by Kao Corporation)
OHV = 394 mg KOH / g, viscosity at 25 ° C = 100 mPa s,
Crosslinking group density = 0 mmol/g)
In the Production Examples, Examples and Comparative Examples, the "predetermined amounts" refer to the amounts of each component shown in Tables 1 and 2.

[Crosslinking group density calculation method]
The crosslinking group densities shown in Tables 1 to 4 were calculated using the following formula from the number of functional groups and hydroxyl value disclosed by each raw material manufacturer, as well as the number average molecular weight obtained by GPC measurement. The measurement was carried out according to <GPC measurement conditions for curing agent>.

[Production Examples 1 to 8]
(Production Example 1: Production of Base Agent (A-1))
A 2-liter four-neck flask was charged with 193 g of a1-1 and 450 g of a1-2, and the temperature was adjusted to 50°C while stirring under a nitrogen stream. Next, 269 g of a2-1 and 88 g of a2-2 were added while stirring, and the temperature was raised to 90°C after the heat generated by the urethane reaction subsided. When the internal temperature was stabilized at 90°C, 0.1 g of catalyst a3-1 was added and reacted at 90°C for 4 hours, and 0.14 g of catalyst poison a4 was added to stop the reaction, thereby obtaining an isocyanate-terminated prepolymer. Hereinafter, this isocyanate-terminated prepolymer is referred to as "main agent (A-1)". In main agent (A-1), the isocyanate group (NCO) content in the obtained isocyanate-terminated prepolymer was 13.5% by mass, and the viscosity at 25°C was 3330 mPa·s.

(Production Examples 2, 4 to 6)
The isocyanate component and polyol component were changed to the compositions shown in Table 1, and prepolymers were synthesized in the same manner as in Production Example 1. All prepolymers were obtained as pale yellow, transparent liquids with low viscosity. Hereinafter, these prepolymers will be referred to as main components (A-2), (A-4) to (A-6). The properties of main components (A-2), (A-4) to (A-6) are shown in Table 1.

[Production Example 3]
(Production Example 3: Production of Base Agent (A-3))
A 2-liter four-neck flask was charged with 231 g of a1-1 and 538 g of a1-2, and the temperature was adjusted to 50° C. while stirring under a nitrogen stream. Next, 231 g of a2-3 was added while stirring, and the temperature was raised to 110° C. after the heat generation of the urethanization reaction subsided. When the internal temperature stabilized at 110° C., a predetermined amount of an active methylene compound and a catalyst a3-2 were added in order, and the allophanate reaction was started. The reaction was followed while sampling the internal liquid and measuring the NCO content, and a predetermined amount of a catalyst poison a4 was added to stop the reaction at the point when the NCO content was predicted to be 16.1%, and a polyisocyanate composition containing an allophanate modified product was obtained. Hereinafter, this polyisocyanate composition is referred to as the main component (A-3). The main component (A-3) was a pale yellow transparent liquid, and had a viscosity of 3630 mPa·s at 25° C.

(Production Example 7: Production of Base Agent (A-7))
300 g of a1-1 and 300 g of a1-2 were added to a 1-liter four-neck flask, and the temperature was adjusted to 50°C while stirring under a nitrogen stream. Next, 400 g of a2-5 was added while stirring, and after the heat generated by the urethane reaction had subsided, the mixture was reacted at 75°C for 3 hours to obtain a prepolymer. Hereinafter, this prepolymer will be referred to as main agent (A-5). The main agent (A-5) was a pale yellow transparent liquid, and had a viscosity of 3750 mPa·s at 25°C. Its properties are shown in Table 1.

[Production Example 8: Production of Base Agent (A-8)]
a1-3 (carbodiimide modified 4,4'-MDI, Millionate MTL-C manufactured by Tosoh Corporation) was used as the main component (A-8). The properties of the main component (A-8) are shown in Table 1.

[Preparation Examples 1 to 12 of Curing Agent (B)]
The raw materials b1, b2, b3, and a2 were charged according to the compounding ratios shown in Table 2, and then stirred and mixed uniformly to obtain curing agents (B-1) to (B-12). The properties of the curing agents (B-1) to (B-12) are shown in Table 2.

[Examples 1 to 10, Comparative Examples 1 to 9]
In Examples 1 to 10 and Comparative Examples 1 to 9, urethane resin compositions having the formulations shown in Tables 3 and 4 were molded.
The values shown in Tables 3 and 4 were calculated from the following test results.

[NCO content measurement]
In the main components (A-1) to (A-8) shown in Table 1, the NCO content was measured in accordance with JIS K1603-1:2007.

[Measurement of MDI Monomer Content]
In the main components (A-1) to (A-8) shown in Table 1, the content (mass%) of MDI monomer was determined by GPC measurement under the following conditions and method.

<GPC Measurement Conditions for Isocyanate Prepolymer>
(1) Measuring device: "HLC-8120 (product name)" (manufactured by Tosoh Corporation)
(2) Column temperature: 40° C.
(3) Detector: RI (refractive index)
(4) Column: Measurements were performed using columns packed with three types of packing materials, TSKgel G3000HXL, TSKgel G2000HXL, and TSKgel G1000HXL (all trade names, manufactured by Tosoh Corporation), connected in series.
(5) Eluent: tetrahydrofuran (THF) (flow rate: 1 mL/min., 40° C.)
(6) Calibration curve: A calibration curve was obtained using the following grades of polystyrene (TSK standard POLYSTYRENE): F-2 (1.81 x 10 ⁴ ), F-1 (1.02 x 10 ⁴ ), A-5000 (5.97 x 10 ³ ), A-2500 (2.63 x 10 ³ ), A-500 (Mw = 6.82 x 10 ² , 5.78 x 10 ² , 4.74 x 10 ² , 3.70 x 10 ² , 2.66 x 10 ² ), toluene (Mw = 92).
(7) Sample: 0.05 g of sample dissolved in 10 mL of THF

<Measurement method>
First, a calibration curve was obtained from a chart obtained by detecting the refractive index difference using polystyrene as a standard substance. Next, for each sample, the mass % of the peak near the peak top molecular weight (number average molecular weight) of 230, which indicates the MDI monomer, was calculated from the chart obtained by detecting the refractive index difference based on the same calibration curve. The obtained value was taken as the content (%) of the MDI monomer.

[Castor oil polymer content measurement]
In the curing agents (B-1) to (B-11) shown in Table 2, the castor oil polymer content (mass%) was determined by GPC measurement under the following conditions and method.

<GPC measurement conditions for curing agent>
(1) Measuring device: "HLC-8120 (product name)" (manufactured by Tosoh Corporation)
(2) Column: Four columns, each packed with two columns of TSKgel G2000HXL and two columns of TSKgel G3000HXL (both trade names, manufactured by Tosoh Corporation), were connected in series.
(3) Column temperature: 40° C.
(4) Detector: RI (refractive index)
(5) Eluent: tetrahydrofuran (THF) (flow rate: 1 mL/min., 40° C.)
(6) Calibration curve: A calibration curve was obtained using the following trifunctional polypropylene polyols (all manufactured by Sanyo Chemical Industries, Ltd.).
- "Sannix GP-250" (number average molecular weight = 250)
- "Sannix GP-400" (number average molecular weight = 400)
- "Sannix GP-600" (number average molecular weight = 600)
- "Sannix GP-1000" (number average molecular weight = 1000)
- "Sannix GP-3000" (number average molecular weight = 3000)
- "Sannix GP-4000" (number average molecular weight = 4000)
- "Sannix GP-5000" (number average molecular weight = 5000)
(7) Sample solution: 0.05 g of sample in 10 mL of THF

<Measurement method>
First, a calibration curve was obtained from a chart obtained by detecting the refractive index difference using polystyrene as a standard substance. Next, for each sample, the mass percentage of the peak near the peak top molecular weight of 1000, which indicates refined castor oil, was calculated from a chart obtained by detecting the refractive index difference based on the same calibration curve. The peaks other than refined castor oil have molecular weights of 1500 or more, and these peaks with molecular weights of 1500 or more were determined as peaks of castor oil polymers. In other words, the mass percentages other than the mass percentage of refined castor oil were calculated as the mass percentages of castor oil polymers.

[Preparation of samples for methanol extraction test]
(Examples 1 to 10, Comparative Examples 1 to 9)
The main agent (A-1) to (A-8) and the curing agent (B-1) to (B-11) were used in the combinations shown in Tables 3 and 4. Under the conditions of a liquid temperature of 25°C or 45°C and an isocyanate group/active hydrogen group ratio of 1.00 or 1.05 (molar ratio), 60g of the main agent and then 40g of the curing agent were quickly weighed into a 500ml polycup. The mixture was mixed with a spatula for 30 seconds and vacuum degassed at 50mmHg for 60 seconds. After degassing, the mixture was spread on a release paper, formed into a sheet of 1mm thickness, and left to stand in a thermostatic chamber at 45°C for 2 days.

[Methanol extraction test]
The values of low molecular weight eluates of the cured resin materials obtained in Examples 1 to 10 and Comparative Examples 1 to 9 were measured by the following method.
First, the methanol extraction measurement samples obtained in each Example and Comparative Example were cut into 10 mm squares. Next, 20 g of the cut sample and 200 g of methanol were placed in a 500 ml sample bottle, which was then sealed and shaken at 25° C. for 24 hours. After shaking, the bottle was further filtered, and the extract was collected in a 300 ml eggplant flask and evaporated to dryness. The methanol extraction rate was then calculated using the following formula.
Methanol extraction rate (%) = {mass of eggplant flask after evaporation to dryness (g) - empty mass of eggplant flask (g)} / sample mass (g) x 100
The methanol extraction rate is preferably less than 1.0%.

[Preparation of samples for low molecular weight dissolution tests]
(Examples 1 to 10, Comparative Examples 1 to 9)
The main agent (A-1) to (A-8) and the curing agent (B-1) to (B-12) were mixed in the combinations shown in Table 3 under the conditions of a liquid temperature of 25°C or 45°C, isocyanate group/active hydrogen group = 1.00 or 1.05 (molar ratio), so that the total mass was 30g, to prepare a mixed liquid. The resulting mixed liquid was then stirred for 15 seconds. Further, 10g of glycerin was added (assuming the glycerin contained in the hollow fiber) and stirred for 15 seconds to obtain a polyurethane resin cured product. This resin cured product was left in a thermostatic chamber for a primary cure condition of 50°C for 10 minutes and a secondary cure condition of 45°C for 2 days.

[Low molecular weight extractables extraction test]
The values of low molecular weight eluates of the cured resin materials obtained in Examples 1 to 10 and Comparative Examples 1 to 9 were measured by the following method.
First, 20 g of each of the samples for measuring low molecular weight elution values obtained in each Example and Comparative Example was cut into a sector shape and weighed, immersed in 100 ml of purified water preheated to 40° C., and left at 40° C. for 2 hours to extract low molecular weight elution products in the purified water. Next, the obtained extract was decanted and placed in a 50 ml measuring flask, and the liquid adjusted to 50 ml with purified water was used as a test liquid. Then, the UV absorbance of the test liquid was measured (Shimadzu Corporation, product name UV-1500). The value of 1/10 of the maximum absorbance at 240 to 245 nm was used as the low molecular weight elution value. The low molecular weight elution value is preferably less than 0.07, more preferably less than 0.065.

[Mixed viscosity/pot life test]
In Examples 1 to 10 and Comparative Examples 1 to 9, the mixing viscosity and pot life when obtaining the resin cured product were determined by the following methods.
The base agent and the curing agent, whose temperature had been adjusted to 25°C or 45°C in advance, were weighed and mixed to obtain a mixture of 50g in total, with a ratio of isocyanate group/active hydrogen group=1.00 (molar ratio) or 1.05 (molar ratio). Then, the viscosity of the mixture was measured using a rotational viscometer (B type, No. 4 rotor) under an atmosphere of 25°C. The viscosity after 60 seconds from the start of mixing the base agent and the curing agent was taken as the mixed viscosity, and the time until the viscosity of the mixture reached 50,000 mPa·s was taken as the pot life (seconds). If the mixed viscosity was 1800 mPa·s or less and the pot life was within 1800 seconds, it was judged that the filling property was good, and if the pot life was within 300 seconds, it was judged that the fast curing property was good.

[Hardness evaluation]
The cured products used for the appearance evaluation were measured for Shore D hardness at 25° C. The results are shown in Tables 3 and 4. The hardness was measured in accordance with JIS K 7312:1996.

[Appearance evaluation]
The polyurethane resin-forming compositions for membrane sealing materials in the combinations shown in Tables 3 and 4 were each degassed under reduced pressure at 10 to 20 kPa for 3 minutes, and then poured into a stainless steel mold (100 mm x 100 mm x 8 mm). This was left to stand and cure for 2 days at 45°C, and then demolded to obtain a cured product. The appearance of the obtained cured product was visually evaluated, with those without turbidity being rated A, those with even slight turbidity or insufficient curing being rated B, and those that were cloudy were rated C.

According to one embodiment of the present disclosure, it is possible to provide a polyurethane resin forming composition that contributes to the formation of a urethane resin that has low viscosity and excellent castability, and that reduces the amount of water elution of the low-molecular-weight reaction product of diphenylmethane diisocyanate and glycerin, and the amount of solvent elution of the molded product, as well as a sealing material and a membrane module using the forming composition. Therefore, the membrane sealing material according to one embodiment of the present disclosure can be suitably used as a membrane sealing material that constitutes medical and industrial separation devices.

REFERENCE SIGNS LIST 11 Housing 13 Hollow fiber membrane 15 First fluid inlet 17 First fluid outlet 19 Membrane seal material 100 Membrane module (hollow fiber membrane module)

Claims (6)

An allophanate group-containing polyisocyanate prepolymer (A),
A polyurethane resin-forming composition for a membrane sealant, comprising:
The polyisocyanate prepolymer (A) is
Diphenylmethane diisocyanate (a1),
and an active hydrogen-containing compound (a2),
The curing agent (B) contains a castor oil polymerized polyol (b1),
The castor oil polymerized polyol (b1) contains a castor oil polymer, which is a homopolymer of castor oil,
The curing agent (B) is
Castor oil polymerized polyol (b1),
At least one polyol (b2) selected from the group consisting of castor oil and castor oil-based modified polyols, and
The present invention comprises a hydroxyl group-containing amine compound (b3) other than the castor oil polymerized polyol (b1) and the polyol (b2),
The content of the hydroxyl group-containing amine compound (b3) in the curing agent (B) is 35 mass% or less,
A polyurethane resin-forming composition for a membrane sealant, having a crosslinking group density of 0.65 mmol/g or more based on the total mass of a polyisocyanate prepolymer (A) and a curing agent (B). The polyurethane resin forming composition for membrane sealing material according to claim 1, wherein the content of the castor oil polymer is 1 mass% or more and 35 mass% or less with respect to the total mass of the polyisocyanate prepolymer (A) and the curing agent (B). An allophanate group-containing polyisocyanate prepolymer (A),
A polyurethane resin-forming composition for a membrane sealant, comprising:
The polyisocyanate prepolymer (A) is
Diphenylmethane diisocyanate (a1),
and an active hydrogen-containing compound (a2),
The curing agent (B) contains a castor oil polymerized polyol (b1),
The castor oil polymerized polyol (b1) contains a castor oil polymer, which is a homopolymer of castor oil ,
the content of the castor oil polymer is 1% by mass or more and 35% by mass or less based on the total mass of the polyisocyanate prepolymer (A) and the curing agent (B);
The curing agent (B) is
Castor oil polymerized polyol (b1),
At least one polyol (b2) selected from the group consisting of castor oil and castor oil-based modified polyols, and
The present invention comprises a hydroxyl group-containing amine compound (b3) other than the castor oil polymerized polyol (b1) and the polyol (b2),
A polyurethane resin-forming composition for a membrane sealant, wherein the content of a hydroxyl group-containing amine compound (b3) in the curing agent (B) is 35 mass% or less . A membrane sealant comprising a cured product of the polyurethane resin-forming composition for membrane sealant according to any one of claims 1 to 3 . A main body portion,
A membrane,
A membrane sealant that seals a gap between the main body and the membrane,
A membrane module, wherein the membrane seal is the membrane seal according to claim 4 . The membrane is a plurality of hollow fiber membranes,
The membrane sealant is
A gap between the main body and at least a portion of the plurality of hollow fiber membranes, and
The membrane module according to claim 5 , wherein at least a part of the gaps between the plurality of hollow fiber membranes is sealed.

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