WO2010140566A1

WO2010140566A1 - Polyurethane polymer solution and method for manufacturing the same

Info

Publication number: WO2010140566A1
Application number: PCT/JP2010/059202
Authority: WO
Inventors: 昌彦渡部; 学高橋; 真弥滝川
Original assignee: 宇部興産株式会社
Priority date: 2009-06-02
Filing date: 2010-05-31
Publication date: 2010-12-09
Also published as: JP5751169B2; JPWO2010140566A1

Abstract

Disclosed is a polyurethane polymer solution containing a polyurethane polymer and an organic solvent, and a method for manufacturing the same. The polyurethane polymer is obtained by reacting at least a polyisocyanate compound (c) and a polycarbonate polyol (a) that contains a repeating unit represented by general formula (1) and has hydroxyl groups at both terminals. (In the formula, Z1 and Z2 independently represent an optionally-substituted bivalent aliphatic hydrocarbon group having 1 to 10 carbon atoms.)

Description

Polyurethane polymer solution and method for producing the same

The present invention relates to a polyurethane polymer solution and a method for producing the same.

The polycarbonate polyol is useful as a raw material for producing a polyurethane polymer by reacting with a polyisocyanate compound, as well as a polyester polyol and a polyether polyol, and a raw material for engineer plastics, adhesives, paints and the like.
Here, since the polyester polyol has an ester bond, the polyurethane polymer produced using the polyester polyol has a disadvantage that it is inferior in hydrolysis resistance. Moreover, since a polyether polyol has an ether bond, a polyurethane polymer produced using the polyether polyol has a disadvantage that it is inferior in weather resistance and heat resistance.
On the other hand, the polycarbonate polyol having a repeating unit represented by — [O—R—O (CO)] — (wherein R represents a divalent hydrocarbon group) does not have the above-described drawbacks, The polyurethane polymer produced using this polycarbonate polyol has the advantage that it is excellent in hydrolysis resistance, weather resistance, heat resistance and the like and is easy to produce industrially.

For example, Patent Document 1 discloses a polyurethane coating agent made from a polycarbonate polyol using an aliphatic polyol as a raw material, and the polyurethane resin used in this coating agent exhibits good adhesion to a plastic film, and after coating the film. It is described that it is excellent in blocking resistance after winding, wear resistance when used as a building material, solvent resistance, weather resistance and the like.

JP 2001-123112 A

However, when the polyurethane described in Patent Document 1 is used, the hardness of the obtained coating film is sufficient in the field of paints and coating agents such as outer panels of aircraft and automobiles, outer wall surfaces and flooring of houses, and the like. There is a problem that is not.
The present invention provides a polyurethane polymer solution excellent in dispersibility in an organic solvent, and having a coating film obtained by applying, drying, and baking as required, and a method for producing the same. Let it be an issue.

The present inventors have found that the above problem can be solved by using a polyurethane polymer obtained using a polycarbonate polyol containing a specific repeating unit.
That is, the present invention provides the following [1] and [2].
[1] A polyurethane polymer obtained by reacting at least a repeating unit represented by the following formula (1) and having a hydroxyl group at both ends and a polyisocyanate compound (c) and an organic solvent: Containing polyurethane polymer solution.

(In the formula, Z ¹ and Z ² each independently represent a divalent aliphatic hydrocarbon group having 1 to 10 carbon atoms which may have a substituent.)

[2] A polyurethane polymer is produced by reacting a polycarbonate polyol (a) containing at least a repeating unit represented by the formula (1) and having hydroxyl groups at both ends with a polyisocyanate compound (c) in an organic solvent. The process for producing a polyurethane polymer solution according to the above [1], comprising a step of obtaining.

The polyurethane polymer solution of the present invention is excellent in dispersibility in an organic solvent, and particularly excellent in the strength of a coating film obtained by coating and drying, and has hydrolysis resistance, durability, heat resistance, and abrasion resistance. It has sex.
According to the production method of the present invention, a polyurethane polymer solution having the above characteristics can be produced efficiently.

[Polyurethane polymer solution]
The polyurethane polymer solution of the present invention is characterized by being synthesized from a polycarbonate polyol (a) containing at least a repeating unit represented by the above formula (1) as a raw material.
The polyurethane polymer solution of the present invention contains a polyurethane polymer comprising a polycarbonate polyol unit (a) and a polyisocyanate unit (c), and the polycarbonate polyol unit (a) is represented by at least the formula (1). Containing repeating units. The polyurethane polymer is a polyurethane prepolymer obtained by reacting the polycarbonate polyol (a) containing the repeating unit represented by the above formula (1) with the polyisocyanate compound (c). A polyurethane polymer obtained by reacting the agent (B) may also be used.
Hereinafter, each component used for the polyurethane polymer solution of the present invention will be described.

<Polycarbonate polyol (a)>
In the present invention, a polycarbonate polyol (a) having at least a repeating unit represented by the following formula (1) and having both ends being hydroxyl groups is used.
As the polycarbonate polyol (a), (i) a polycarbonate polyol (a-1) having a repeating unit represented by the following formula (1) as a main component and both ends being hydroxyl groups, and (ii) the following formula ( Preferable examples include polycarbonate polyol (a-2) having a repeating unit represented by 1) and a repeating unit represented by the following formula (3) and having both ends being hydroxyl groups.
In this specification, the polycarbonate polyol (a-1) and the polycarbonate polyol (a-2) are collectively referred to as “polycarbonate polyol (a)” or “component (a)”.

(In the formula, Z ¹ and Z ² are each independently a divalent aliphatic hydrocarbon group having 1 to 10 carbon atoms which may have a substituent. R ³ represents a substituent. A divalent hydrocarbon group having 3 to 20 carbon atoms which may have

The polycarbonate polyol (a) preferably has the following physical properties.
Based on JIS K 1557, the Hazen unit color number (APHA) defined in JIS K 0071-1 is preferably 200 or less, more preferably 100 or less, still more preferably 70 or less, and particularly preferably 1 to 60.
The hydroxyl value is preferably 35 to 600 mgKOH / g, more preferably 50 to 400 mgKOH / g, still more preferably 100 to 150 mgKOH / g, and particularly preferably 110 to 130 mgKOH / g.
The acid value is preferably 1 mgKOH / g or less, more preferably 0.1 mgKOH / g or less, and still more preferably 0.01 to 0.05 mgKOH / g.
The melting point is preferably −100 to + 250 ° C., more preferably −80 to + 200 ° C., still more preferably −20 to + 170 ° C., and particularly preferably 0 to 160 ° C.
The glass transition point is preferably −80 to + 50 ° C., more preferably −60 to + 20 ° C., and further preferably −55 to −20 ° C.
The viscosity is preferably 0.01 to 10 Pa · s (75 ° C.), more preferably 0.05 to 5 Pa · s (75 ° C.), and still more preferably 0.1 to 1.5 Pa · s (75 ° C.). .
The methods for measuring the Hazen unit color number (APHA), hydroxyl value, acid value, melting point, glass transition point, and viscosity are as described in the Examples.

(Polycarbonate polyol (a-1))
The polycarbonate polyol (a-1) is a polyol having a repeating unit represented by the formula (1) and having hydroxyl groups at both ends.
Z ¹ and Z ² in formula (1) are divalent aliphatic hydrocarbon groups having 1 to 10 carbon atoms which may have a substituent, but the substituent does not participate in the urethanization reaction. A group is preferable, and the carbon chain may contain a hetero atom or an ester bond, and may contain an alicyclic structure, an ether bond, or the like.
Specific examples of the divalent aliphatic hydrocarbon group having 1 to 10 carbon atoms which may have a substituent include a methylene group, an ethylene group, a trimethylene group, a propane-1,2-diyl group, and a tetramethylene group. , Butane-1,3-diyl group, tetramethylene group, butane-1,3-diyl group, pentamethylene group, hexamethylene group, heptamethylene group, octamethylene group, decamethylene group, 1-octamethylene group, etc. It is done. Of these, a linear or branched alkanediyl group having 1 to 4 carbon atoms is preferable.
Further, the bonding position of Z ¹ and Z ^{2 with} respect to the benzene ring is preferably 1,4-bond (para form) or 1,3-bond (meta form), and more preferably 1,4-bond (para form).
Particularly preferred polycarbonate polyol (a-1) is a polyol having a repeating unit represented by the following formula (2) and having both ends being hydroxyl groups.

The number, content, number average molecular weight and the like of the repeating unit represented by the formula (1) or (2) of the polycarbonate polyol (a-1) are from the viewpoint of mechanical performance, hydrolysis resistance, heat resistance, and weather resistance. From the viewpoint of applicability in various fields, it is as follows.
The number of repeating units represented by the formula (1) or (2) is preferably 1 to 18, more preferably 2 to 13.
The content of the repeating unit represented by the formula (1) or (2) is preferably 80 to 100 mol%, more preferably 90 to 100 mol% in the polycarbonate polyol (a-1).
The number average molecular weight of the polycarbonate polyol (a-1) is preferably 200 to 3,000, more preferably 300 to 2,000, and still more preferably 400 to 1,000. If the number average molecular weight is too high, the melting point becomes high and handling may be difficult. On the other hand, if the number average molecular weight is too low, the number of carbonate bonds decreases, and the properties as polycarbonate polyol (a-1) may be difficult to express. In addition, the measuring method of a number average molecular weight is as describing in an Example.

The polycarbonate polyol (a-1) can be produced by reacting an aromatic diol compound with carbonate ester, phosgene or the like by a known method such as a carbonate method or a phosgene method. Of these, the carbonate method is preferred.
As a carbonate method, the following manufacturing method A is mentioned preferably, for example.
In the production method A, as shown in the following reaction formula, an aromatic dihydroxyl compound (a-1-1) and a carbonate ester (a-1-2) are transesterified in the presence or absence of a catalyst. In this method, polycarbonate polyol (a′-1) is obtained by reaction.
In production method A, a reaction example in which 1,4-benzenedimethanol is used as the aromatic dihydroxyl compound (a-1-1) is shown, but the same can be done when other aromatic dihydroxyl compounds are used. Can do.

In the above formula relating to production method A, R ¹ and R ² each independently represent a hydrocarbon group which may have a substituent. The hydrocarbon group is preferably a hydrocarbon group having 1 to 6 carbon atoms. n represents the number of repeating units, preferably 1 to 18, more preferably 2 to 13.
In the above production method A, alcohols (R ¹ OH, R ² OH, etc.) derived from the carbonate ester (a-1-2) are by-produced during the transesterification reaction. It is preferable to proceed. In the production method A, an alkylene carbonate such as ethylene carbonate can be used instead of the carbonate ester (a-1-2), but in this case, glycols derived from the alkylene carbonate are by-produced. It is preferable to proceed the reaction while extracting this by distillation or the like.
The details of the aromatic dihydroxyl compound (a-1-1), the carbonate ester (a-1-2), and the transesterification will be described later.

(Polycarbonate polyol (a-2))
The polycarbonate polyol (a-2) is a polycarbonate polyol copolymer having a repeating unit represented by the following formula (1) and a repeating unit represented by the following formula (3), and both terminals are hydroxyl groups. A polycarbonate diol copolymer is preferred.

In formula (1), Z ¹ and Z ² are the same as described above.
In formula (3), R ³ represents an optionally substituted divalent hydrocarbon group having 3 to 20 carbon atoms, and the substituent is preferably a group that does not participate in the urethanization reaction, The carbon chain may contain a hetero atom or an ester bond, and may contain an alicyclic structure, an ether bond, or the like.
Specific examples of R ³ include trimethylene group, propane-1,2-diyl group, tetramethylene group, butane-1,3-diyl group, pentamethylene group, hexamethylene group, 3-methylpentane-1,5- Examples include diyl group, octamethylene group, decamethylene group, dodecamethylene group, tetradecamethylene group, hexadecamethylene group, octadecamethylene group, cyclohexane group, and 1,4-cyclohexanedimethano group. Of these, a linear or branched alkanediyl group having 3 to 14 carbon atoms, preferably 3 to 6 carbon atoms is preferable.
In the polycarbonate polyol (a-2), the molar ratio of [(repeating unit represented by formula (1)) / (repeating unit represented by formula (3))] is preferably 1/9 to 9/1. 1/5 to 5/1 is more preferable, and 1/3 to 3/1 is still more preferable. When the ratio of the repeating unit represented by the formula (1) is high, the viscosity of the polycarbonate polyol (a-2) increases, and therefore, the handling of the polycarbonate polyol (a-2) during the urethanization reaction tends to be difficult. . When the ratio of the repeating unit represented by formula (1) is low, the hardness of the coating film obtained using the polyurethane polymer solution of the present invention tends to be low.

The number, content, number average molecular weight and the like of the repeating unit represented by the formulas (1) and (3) of the polycarbonate polyol (a-2) are from the viewpoint of mechanical performance, hydrolysis resistance, heat resistance, and weather resistance. From the viewpoint of applicability in various fields, it is as follows.
The repeating unit represented by the formula (1) and the repeating unit represented by the formula (3) may be block copolymerized or randomly copolymerized.
The number of repeating units represented by the formula (1) is preferably 1 to 20, more preferably 2 to 15, and the content of the repeating units is preferably in the polycarbonate polyol (a-2). It is 10 to 90 mol%, more preferably 25 to 75 mol%.
The number of the repeating unit represented by the formula (3) is preferably 1 to 30, more preferably 2 to 20, and the content of the repeating unit is preferably in the polycarbonate polyol (a-2). It is 10 to 90 mol%, more preferably 25 to 75 mol%.
The number average molecular weight of the polycarbonate polyol (a-2) is preferably 200 to 3,000, more preferably 300 to 2,000, and still more preferably 900 to 1,500. In addition, the measuring method of a number average molecular weight is as describing in an Example.

Examples of the method for producing the polycarbonate polyol (a-2) include a method of reacting an aromatic polyol compound, a dihydroxyl compound, carbonate ester, phosgene and the like by a known method such as a carbonate ester method and a phosgene method. Of these, the carbonate method is preferred.
As a carbonate method, the following manufacturing method B is mentioned preferably, for example.
In the production method B, as shown in the following reaction formula, an aromatic dihydroxyl compound (a-1-1), a carbonate (a-1-2), and a dihydroxyl compound (a-1-3) In this method, a polycarbonate polyol (a′-2) is obtained by an ester exchange reaction in the presence or absence of a catalyst.

In the production method B, a reaction example using 1,4-benzenedimethanol as the aromatic dihydroxyl compound is shown, but the same can be performed when other aromatic dihydroxyl compound is used.
In addition, in the reaction formula of the following production method B, there is a structural unit derived from the aromatic dihydroxyl compound (a-1-1) at both ends as polycarbonate polyol (a′-2) in order to express the reaction formula simply. Only the case is described. However, the terminal is not limited to the structural unit derived from the aromatic dihydroxyl compound (a-1-1).

In the above formula relating to production method B, R ¹ and R ² each independently represent a hydrocarbon group which may have a substituent, and preferably has 1 to 6 carbon atoms. R ³ represents a divalent hydrocarbon group having 3 to 20 carbon atoms which may have a substituent as described above. p represents the number of repeating units, and is preferably 1 to 20, more preferably 2 to 15. q represents the number of repeating units, and is preferably 1 to 30, more preferably 2 to 20.
In the above production method B, alcohols (R ¹ OH, R ² OH, etc.) derived from the carbonate ester (a-1-2) are by-produced during the transesterification reaction. It is preferable to proceed. In the above production method B, an alkylene carbonate such as ethylene carbonate can be used instead of the carbonate ester (a-1-2). In this case, glycols derived from the alkylene carbonate are by-produced. It is preferable to proceed the reaction while extracting this by distillation or the like.

(Aromatic dihydroxyl compound (a-1-1))
The aromatic dihydroxyl compound (a-1-1) that can be used in the production methods A and B is represented by the following formula (4).

In the formula, Z ¹ and Z ² each independently represent a divalent aliphatic hydrocarbon group having 1 to 10 carbon atoms which may have a substituent, and specific examples and preferred examples thereof are as described above. And a linear or branched divalent aliphatic hydrocarbon group having 1 to 4 carbon atoms is preferred.
Z ¹ and Z ² are preferably 1,4-bond (para-form) or 1,3-bond (meta-form), and more preferably 1,4-bond (para-form).
Particularly preferred aromatic dihydroxyl compounds (a-1-1) include 1,4-benzenedimethanol, 1,4-benzenediethanol, 1,4-benzenedipropanol, 1,4-benzenedibutanol, , 3-benzenedimethanol, 1,3-benzenediethanol, 1,3-benzenedipropanol, 1,3-benzenedibutanol, 4- (4-hydroxymethylphenyl) butanol, 3- [4- (2-hydroxy And compounds having a linear or branched divalent aliphatic hydrocarbon group having 1 to 4 carbon atoms, such as ethyl) phenyl] propanol.

(Carbonate ester (a-1-2))
The carbonic acid ester (a-1-2) that can be used in the production methods A and B is not particularly limited, but it is desirable to appropriately select one that can efficiently extract by-product alcohols derived from the carbonic acid ester. Examples thereof include dialkyl carbonate, diaryl carbonate, and alkylene carbonate.
The dialkyl carbonate is preferably a dialkyl carbonate having an alkyl group having 1 to 6 carbon atoms, preferably 1 to 4 carbon atoms. Specific examples include dimethyl carbonate and diethyl carbonate.
Examples of the diaryl carbonate include diphenyl carbonate.
The alkylene carbonate is preferably an alkylene carbonate having an alkanediyl group having 2 to 4 carbon atoms, and specific examples thereof include ethylene carbonate, propylene carbonate, butylene carbonate and the like. Among these, from the viewpoint of easy extraction of by-product alcohols, dialkyl carbonates having an alkyl group having 1 to 4 carbon atoms are preferred, dimethyl carbonate or diethyl carbonate is particularly preferred, and dimethyl carbonate is most preferred.

(Dihydroxyl compound (a-1-3))
The dihydroxyl compound (a-1-3) that can be used in the production method B is not particularly limited. For example, an alkanediol having 3 to 20 carbon atoms (when R ³ is a divalent aliphatic hydrocarbon group having 3 to 20 carbon atoms), a branched carbon chain of the alkylene group portion of the alkanediol, Examples include those in which the carbon chain of the alkylene group portion of the alkanediol contains an alicyclic structure or an ether bond.
Examples of the alkanediol having 3 to 20 carbon atoms, preferably 3 to 14 carbon atoms include 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7 -Pentanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,12-dodecanediol and the like.
Examples of the compound having a branched carbon chain of the alkylene group include 1,3-butanediol, 3-methylpentane-1,5-diol, 2-ethylhexane-1,6-diol, neopentyl glycol, 2 -Methyl-1,8-octanediol and the like.

Examples of the compound in which the carbon chain of the alkylene group part includes an alicyclic structure include 1,3-cyclohexanediol, 1,4-cyclohexanediol, 2,2′-bis (4-hydroxycyclohexyl) propane, 1,4- And cyclohexanedimethanol.
Examples of the compound in which the carbon chain of the alkylene group part includes an ether bond include diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, dipropylene glycol, polypropylene glycol, and polytetramethylene glycol.
Among the above, from the viewpoint of easy handling and availability, the dihydroxyl compound (a-1-3) may be carbon such as 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, etc. Diols having an alicyclic structure having 5 to 8 carbon atoms such as alkanediol having 4 to 8 carbon atoms, particularly 4 to 6 carbon atoms, 1,4-cyclohexanedimethanol are more preferable.

(catalyst)
Examples of the catalyst that can be used in the reaction in the production methods A and B include a catalyst (transesterification catalyst) used in a normal transesterification reaction. For example, preferred are alkali metal compounds, alkaline earth metal compounds, aluminum compounds, zinc compounds, manganese compounds, nickel compounds, antimony compounds, zirconium compounds, titanium compounds, and organic tin compounds.
Examples of alkali metal compounds include alkali metal hydroxides (lithium hydroxide, sodium hydroxide, potassium hydroxide, etc.), alkali metal carbonates (lithium carbonate, sodium carbonate, potassium carbonate, etc.), and alkali metal carboxylates. (Lithium acetate, sodium acetate, potassium acetate, etc.), alkali metal alkoxides (lithium methoxide, netrium methoxide, potassium t-butoxide, etc.) and the like. Alkaline earth metal compounds include alkaline earth metal water. Examples thereof include oxides (magnesium hydroxide and the like), alkaline earth metal alkoxides (magnesium methoxide and the like), and the like.

Examples of the aluminum compound include aluminum alkoxide (aluminum ethoxide, aluminum isopropoxide, aluminum sec-butoxide, etc.), aluminum compounds such as aluminum acetylacetonate, and the like.
Examples of zinc compounds include zinc carboxylates (such as zinc acetate) and zinc acetylacetonate. Examples of manganese compounds include manganese carboxylates (such as manganese acetate) and manganese acetylacetonate. Examples of nickel compounds include nickel carboxylates (such as nickel acetate) and nickel acetylacetonate.
Examples of antimony compounds include antimony carboxylates (such as antimony acetate) and antimony alkoxides. Examples of zirconium compounds include zirconium alkoxides (zirconium propoxide, zirconium butoxide, etc.), zirconium acetylacetonate, and the like.

Titanium compounds include titanium alkoxide (titanium tetraethoxide, titanium tetrapropoxide, titanium tetrabutoxide, tetracyclohexyl titanate, tetrabenzyl titanate, etc.), titanium acylate (tributoxy titanium stearate, isopropoxy systemate, etc.), titanium Chelates (diisopropoxytitanium bisacetylacetonate, dihydroxy bislactotitanium, etc.) and the like.
Examples of the organic tin compound include dibutyltin oxide, dibutyltin diacetate, and dibutyltin dilaurate.
Each carboxylate preferably has 2 to 30 carbon atoms, more preferably 2 to 18 carbon atoms, and each alkoxide preferably has 1 to 30 carbon atoms in the alkoxy group. 18 is more preferable.
In said catalyst, a titanium compound and an organotin compound are preferable, a titanium compound is more preferable, and a titanium alkoxide is still more preferable. Among the titanium alkoxides, titanium tetraethoxide, titanium tetrapropoxide, and titanium tetrabutoxide are more preferable, and titanium tetrabutoxide is particularly preferable.
The above aromatic dihydroxyl compound (a-1-1), carbonate ester (a-1-2), dihydroxyl compound (a-1-3), and catalyst may be used alone or in combination of two or more. Can be used in combination.

(Additive)
Various additives can be added to the polyurethane polymer solution of the present invention as necessary.
Examples of the additive include various resin components, resin particles, inorganic particles, fillers, pigments, dyes, light stabilizers, antioxidants, ultraviolet absorbers, antistatic agents, and the like. be able to.

(Transesterification reaction)
The transesterification reaction in the production methods A and B can be performed in the presence or absence of a catalyst, but is preferably performed in the presence of a catalyst from the viewpoint of reaction efficiency.
The reaction temperature and reaction pressure in the transesterification reaction vary depending on the types of carbonic acid ester (a-1-2) and dihydroxyl compound (a-1-3) to be used. In the case of production method A, 1,4-benzenedimethanol In the case of production method B, the aromatic dihydroxyl compound (a-1-1) and the dihydroxyl compound (a-1-3) are not substantially distilled. It is preferable to use conditions. The reaction temperature is preferably 90 to 230 ° C., and the reaction pressure is preferably reduced from normal pressure to 30 to 500 mmHg. The reaction can be performed in an atmosphere of air, carbon dioxide gas, or an inert gas (nitrogen, argon, helium, or the like) or in an air stream, but is preferably performed in an inert gas atmosphere or an air stream.
Furthermore, the amount used in the case of using a catalyst is, in terms of reactivity, in the case of production method A, the aromatic dihydroxyl compound (a-1-1) and the carbonate ester (a-1-2) at the start of the reaction. In the case of production method B with respect to the total charged amount, aromatic dihydroxyl compound (a-1-1), carbonic acid ester (a-1-2) and dihydroxyl compound (a-1-3) at the start of the reaction ) Based on the mass of the catalyst, preferably 1 to 20,000 ppm, more preferably 10 to 5,000 ppm, and even more preferably 100 to 4,000 ppm.

Further, a high molecular weight polycarbonate polyol obtained by reacting a dihydroxyl compound (a-1-3) with a carbonate ester (a-1-2), and an aromatic dihydroxyl compound such as 1,4-benzenedimethanol The polycarbonate polyol (a-2) can also be obtained by subjecting (a-1-1) to a transesterification reaction in the presence or absence of a catalyst.
Further, a polycarbonate polyol having a high molecular weight obtained by reacting an aromatic dihydroxyl compound (a-1-1) such as 1,4-benzenedimethanol with a carbonate ester (a-1-2), and a dihydroxyl compound A polycarbonate polyol (a-2) can also be obtained by subjecting (a-1-3) to a transesterification reaction in the presence or absence.

The average molecular weights of the polycarbonate polyols (a-1) and (a-2) used in the present invention are the aromatic dihydroxyl compound (a-1-1), carbonate (a-1-2), and dihydroxy used. It can be prepared by changing the reaction molar ratio of the compound (a-1-3).
When the average molecular weight of the produced polycarbonate polyol (a-1) or (a-2) is smaller than the target average molecular weight, the aromatic dihydroxyl compound (a-1-1) and When dihydroxy compound (a-1-3) is distilled and the average molecular weight is larger than the target average molecular weight, aromatic dihydroxyl compound (a-1-1) and / or dihydroxyl The compound (a-1-3) can be added and further subjected to a transesterification to obtain a polycarbonate polyol (a-1) or (a-2) having a target average molecular weight.
In addition, the constituent molar ratio of the repeating unit of the polycarbonate polyol (a-2) of the present invention is a change in the molar ratio of the aromatic dihydroxyl compound (a-1-1) and the dihydroxyl compound (a-1-3). Etc. can be prepared.

<Polyol (b) other than component (a)>
In the present invention, as the polyol (b) other than the component (a) (hereinafter also simply referred to as “polyol (b)”), for example, a high molecular weight diol or a low molecular weight diol can be further used.
The high molecular weight diol that can be used is not particularly limited, and examples thereof include polycarbonate diol, polyester diol, polyether diol, acrylic diol, and polyether polyester polyol having an ether bond and an ester bond.
Examples of the polycarbonate diol include polytetramethylene carbonate diol and polyhexamethylene carbonate diol.
Examples of the polyester diol include polyethylene adipate diol, polybutylene adipate diol, polyethylene butylene adipate diol, polyhexamethylene isophthalate adipate diol, polyethylene succinate diol, polybutylene succinate diol, polyethylene sebacate diol, polybutylene sebacate And diol, poly-ε-caprolactone diol, poly (3-methyl-1,5-pentylene adipate) diol, polycondensate of 1,6-hexanediol and dimer acid, and the like.
Examples of the polyether diol include polyethylene glycol, polypropylene glycol, polytetramethylene glycol, ethylene oxide and propylene oxide, ethylene oxide and butylene oxide random copolymers, and block copolymers.

The low molecular weight diol that can be used is not particularly limited, and examples thereof include ethylene glycol, 1,3-propanediol, 2-methyl-1,3-propanediol, 2,2-dimethyl-1,3-propanediol, 2-butyl-2-ethyl-1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, 1,9 -Aliphatic diols having 2 to 9 carbon atoms such as nonanediol, 2-methyl-1,8-octanediol, diethylene glycol, triethylene glycol, tetraethylene glycol; 1,4-cyclohexanedimethanol, 1,3-cyclohexanedi Methanol, 1,4-cyclohexanediol, 1,4-bis (hydroxyethyl) cyclohex Diols having 6-12 carbon atoms, such as 2,7-norbornanediol, tetrahydrofuran dimethanol, 2,5-bis (hydroxymethyl) -1,4-dioxane, trimethylolpropane, pentaerythritol And low molecular weight polyhydric alcohols such as sorbitol.
The said polyol (b) can be used individually by 1 type or in combination of 2 or more types.

In the present invention, the total number of hydroxyl equivalents of the polycarbonate polyol (a) and the polyol (b) is preferably 70 to 270. If the number of hydroxyl equivalents is less than 70, it may be difficult to produce a polyurethane polymer solution substantially. If it exceeds 270, the hardness of the coating film obtained by applying the obtained polyurethane polymer solution is low. It may become too much.
The number of hydroxyl equivalents is preferably 130 to 270, more preferably 160 to 265, and particularly preferably 180 to 260, from the viewpoint of the hardness of the coating film obtained by applying the polyurethane polymer solution obtained.
The number of hydroxyl equivalents can be calculated by the following formula.
Number of hydroxyl equivalents of each polyol = molecular weight of each polyol / number of OH groups of each polyol Total number of hydroxyl equivalents = M / total number of moles of polyol In the above formula, M is the number of hydroxyl equivalents of [polycarbonate polyol (a). X number of moles of polycarbonate polyol (a)] + [number of hydroxyl equivalents of polyol (b) x number of moles of polyol (b))].

<Polyisocyanate compound (c)>
The polyisocyanate compound (c) used in the present invention is not particularly limited. Specific examples thereof include 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, 2,4-tolylene diisocyanate (TDI), 2,6-tolylene diisocyanate, 4,4′-diphenylenemethane diisocyanate (MDI). ), 2,4-diphenylmethane diisocyanate, 4,4′-diisocyanatobiphenyl, 3,3′-dimethyl-4,4′-diisocyanatobiphenyl, 3,3′-dimethyl-4,4′-diisocyanate Aromatic polyisocyanate compounds such as natodiphenylmethane, 1,5-naphthylene diisocyanate, 4,4 ′, 4 ″ -triphenylmethane triisocyanate, m-isocyanatophenylsulfonyl isocyanate, p-isocyanatophenylsulfonyl isocyanate; ethylene diisocyanate , Tet Ramethylene diisocyanate, hexamethylene diisocyanate (HDI), dodecane methylene diisocyanate, 1,6,11-undecane triisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, lysine diisocyanate, 2,6-diisocyanatomethylcaproate, Aliphatic polyisocyanate compounds such as bis (2-isocyanatoethyl) fumarate, bis (2-isocyanatoethyl) carbonate, 2-isocyanatoethyl-2,6-diisocyanatohexanoate; isophorone diisocyanate (IPDI), 4,4'-dicyclohexylmethane diisocyanate (hydrogenated MDI), cyclohexylene diisocyanate, methylcyclohexylene diisocyanate (hydrogenated TDI), bis (2-isocyana Toyl) -4-dichlorohexene-1,2-dicarboxylate, 2,5-norbornane diisocyanate, 2,6-norbornane diisocyanate, and the like.
The number of isocyanate groups per molecule of the polyisocyanate compound is usually 2, but a polyisocyanate compound having 3 or more isocyanate groups such as triphenylmethane triisocyanate is also within the range where the resulting polyurethane polymer does not gel. Can be used.
Among these compounds, 4,4′-diphenylenemethane diisocyanate (MDI), isophorone diisocyanate (IPDI), 4,4′-dicyclohexylmethane diisocyanate (hydrogenated) from the viewpoint of controlling reactivity and imparting elastic modulus. MDI) is preferred.
A polyisocyanate compound (c) can be used individually by 1 type or in combination of 2 or more types.

<Chain extender (B)>
In the present invention, a chain extender (B) having reactivity with the isocyanate group of the polyurethane prepolymer (A) can be used. Examples of chain extenders include ethylenediamine, 1,4-tetramethylenediamine, 2-methyl-1,5-pentanediamine, 1,4-butanediamine, 1,6-hexamethylenediamine, 1,4-hexamethylene. Amine compounds such as diamine, 3-aminomethyl-3,5,5-trimethylcyclohexylamine, 1,3-bis (aminomethyl) cyclohexane, xylylenediamine, piperazine, 2,5-dimethylpiperazine, diethylenetriamine, triethylenetetramine Diol compounds such as ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, polyalkylene glycols typified by polyethylene glycol, water, etc., among which primary diamine compounds are preferred. .
A chain extender (B) can be used individually by 1 type or in combination of 2 or more types.
By using a chain extender, it becomes easy to improve the molecular weight of the polyurethane polymer, and the hardness of the coating film obtained using the polyurethane polymer solution tends to increase.

[Polyurethane polymer]
The polyurethane polymer used in the present invention can be obtained by any of the following methods.
(I) A method of reacting the polycarbonate polyol (a) and the polyisocyanate compound (c).
(Ii) A method of reacting the polycarbonate polyol (a), the polyol (b) and the polyisocyanate compound (c).
(Iii) A method of reacting the polycarbonate polyol (a), the polyisocyanate compound (c) and the chain extender (B).
(Iv) A method of reacting the polycarbonate polyol (a), the polyol (b), the polyisocyanate compound (c), and the chain extender (B).
The reaction temperature between the polyol component and the polyisocyanate compound (c) is preferably 40 to 150 ° C., more preferably 60 to 120 ° C. The reaction temperature between the polyol (a) and the chain extender (B) is usually It is 0 to 80 ° C, preferably 0 to 60 ° C.
Details of the reaction conditions and the like will be described in the section of [Method for producing polyurethane polymer solution] described later.

The organic solvent is not particularly limited as long as each component can be dissolved. For example, aliphatic hydrocarbons such as n-hexane, n-heptane and n-octane, aromatic hydrocarbons such as benzene, toluene and xylene, halogenated hydrocarbons such as chloroform and carbon tetrachloride, dibutyl ether, Ethers such as tetrahydrofuran and 1,4-dioxane, ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone, esters such as ethyl acetate, n-propyl acetate and n-butyl acetate, amides such as N, N-dimethylacetamide And the like. These solvents may be used alone or in combination of two or more. The blending method of each component, the luster pigment, the color pigment, the organic solvent, various additives, and the resin addition method are not particularly limited and can be performed by various methods, and the mixing order and the addition order are various. Can be done in order.
The proportion of the polyurethane polymer in the polyurethane polymer solution is preferably 5 to 60% by mass, more preferably 20 to 50% by mass.

[Method for producing polyurethane polymer solution]
Although the manufacturing method of the polyurethane polymer solution of this invention is not specifically limited, According to the method of including the following process (1) and the process (2) as needed, it can manufacture efficiently.
Step (1): Polyurethane obtained by reacting a polycarbonate polyol (a) having at least a repeating unit represented by the following formula (1) and having both ends being hydroxyl groups and a polyisocyanate compound (c) in an organic solvent. Step of obtaining prepolymer (A)

(In the formula, Z ¹ and Z ² are as defined above.)

Step (2): A step of obtaining a polyurethane polymer solution by reacting a polyurethane prepolymer (A) with a chain extender (B) having reactivity with an isocyanate group of the polyurethane prepolymer (A) in an organic solvent. Hereafter, each process in the manufacturing method of this invention is demonstrated.

<Step (1)>
The step (1) includes at least a repeating unit represented by the formula (1), a polycarbonate polyol (a) having both ends of a hydroxyl group, a polyisocyanate compound (c), and, if necessary, a polyol ( In this step, b) is reacted to obtain a polyurethane prepolymer (A).
Step (1) can be carried out in the presence or absence of a catalyst. Examples of the catalyst include salts of metals and organic acids or inorganic acids such as tin catalysts (trimethyltin laurate, dibutyltin dilaurate, etc.) and lead catalysts (lead octylate, etc.), organometallic derivatives, amine catalysts (triethylamine). N-ethylmorpholine, triethylenediamine, etc.), diazabicycloundecene catalysts and the like. Among these, dibutyltin dilaurate is preferable from the viewpoint of reactivity.
The reaction in the step (1) can be performed in the absence of a solvent or in the presence of an organic solvent. Examples of the organic solvent include acetone, methyl ethyl ketone, methyl isobutyl ketone, tetrahydrofuran, dioxane, dimethylformamide, dimethyl sulfoxide, N-methylpyrrolidone, N-ethylpyrrolidone, and ethyl acetate. N-methylpyrrolidone and N-ethylpyrrolidone are preferable because they function as a film-forming aid when forming a coating film of the obtained polyurethane polymer solution.
Step (1) may be performed in an inert gas atmosphere or in an air atmosphere.
The reaction temperature is preferably 40 to 150 ° C, more preferably 60 to 120 ° C. If the reaction temperature is less than 40 ° C., the raw material may not be dissolved, or the resulting urethane prepolymer (A) may have a high viscosity and cannot be sufficiently stirred. If the reaction temperature exceeds 150 ° C., side reactions may occur. May occur.

The ratio of each component in the step (1) is as follows when the total amount of the polycarbonate polyol (a) and the polyol (b) is 100 parts by mass.
The proportion of the polycarbonate polyol (a) is preferably 60 to 95 parts by mass, more preferably 65 to 90 parts by mass, and still more preferably 75 to 90 parts by mass. If this ratio is less than 60 parts by mass, the hardness of the coating film obtained by applying the resulting polyurethane polymer solution tends to be low, and if it exceeds 95 parts by mass, the coating film may become too hard.
The proportion of the polyol (b) is preferably 0 to 30 parts by mass, more preferably 0 to 10 parts by mass, and still more preferably 0 to 5 parts by mass. When the proportion of the polyol (b) exceeds 30 parts by mass, the proportion of the polycarbonate polyol (a) in all the polyol components becomes too small, so that the hardness of the coating film is lowered or the solubility of the polyurethane polymer is deteriorated. There is a case.

The ratio of the number of moles of isocyanate groups in the polyisocyanate compound (c) to the number of moles of all hydroxyl groups in the polyol component comprising the polycarbonate polyol (a) and polyol (b) is preferably 0.8 to 2.0.
If the number of moles of hydroxyl groups in the polyol component is too large, the molecular weight becomes too small, and the resulting coating film may not be sufficiently stretched. If the number of moles of hydroxyl groups in the polyol component is too small, a large amount of the unreacted polyisocyanate compound (c) remains in the reaction system and may react with the chain extender or react with water. In order to cause molecular elongation, the coating film obtained by applying the polyurethane polymer solution of the present invention may be uneven.
In the case of obtaining the urethane prepolymer (A), the reaction between the polyol component consisting of the polycarbonate polyol (a) and the polyol (b) and the polyisocyanate compound (c) is performed in any order between the components (a) and (b) ( You may make it react with c) component and may make it react with (c) component, after mixing 2 or more types of components previously.

Examples of the organic solvent include those described above.
There is no restriction | limiting in particular in the method to disperse | distribute a polyurethane prepolymer (A) in the organic solvent. For example, (i) a method of adding a urethane prepolymer or a urethane prepolymer solution while stirring an organic solvent with a homomixer or a homogenizer, and (ii) an organic solvent while stirring the urethane prepolymer with a homomixer or a homogenizer And the like.

<Step (2)>
Step (2) is a step of obtaining a polyurethane polymer solution by reacting a polyurethane prepolymer (A) in an organic solvent with a chain extender (B) having reactivity with an isocyanate group of the polyurethane prepolymer (A). It is.
The reaction temperature in step (2) is usually 0 to 80 ° C., preferably 0 to 60 ° C. The reaction may be performed slowly under cooling, or in some cases, the reaction may be promoted under heating conditions of 60 ° C. or lower.
The addition amount of the chain extender (B) is preferably equal to or less than the equivalent of the isocyanate group that is the starting point of chain extension in the urethane prepolymer to be obtained, and is preferably 0.7 to 0.99 equivalent of the isocyanate group. More preferred. When the chain extender (B) is added in excess of the equivalent of isocyanate groups, the molecular weight of the chain-extended urethane polymer may decrease, and the coating film obtained by applying the obtained polyurethane polymer solution The strength may decrease.
The polyurethane polymer solution obtained by the production method of the present invention is particularly excellent in the strength of a coating film obtained by coating and drying, and has hydrolysis resistance, durability, heat resistance, and abrasion resistance. .

The polyurethane polymer solution of the present invention can be preferably applied to uses such as coating agents, paints, primers, urethane films, synthetic leather / artificial leather, glass fiber sizing agents and the like.
For example, when used in paint, a color pigment or extender can be used. Examples of the color pigment include organic pigments such as azo lake pigments, phthalocyanine pigments, indigo pigments, perinone pigments, perylene pigments, quinophthalone pigments, dioxazine pigments, quinacridone pigments, yellow lead, yellow iron oxide, Examples thereof include inorganic pigments such as bengara and titanium dioxide. Examples of extender pigments include kaolin and talc.
In addition, as an additive, a plasticizer, a stabilizer, an inorganic filler, a catalyst, or the like may optionally be included. Examples of the plasticizer include dibutyl phthalate and dioctyl phthalate. Examples of the stabilizer include an antioxidant and an ultraviolet absorber. Examples of the inorganic filler include calcium carbonate, titanium oxide, calcium oxide, calcium oxide, talc, clay, aluminum sulfate, vinyl chloride paste resin, and the like. These can be used singly or in combination of one or more, and those subjected to surface treatment can also be used as appropriate.

Next, the present invention will be described in more detail with reference to examples and comparative examples.
In addition, the measurement of the physical property of polycarbonate polyol and the measurement of the hardness of a polyurethane film were performed with the following method.
(1) Number average molecular weight The number average molecular weight in terms of polystyrene was measured by gel permeation chromatography (GPC).
(2) Hydroxyl value: Measured in accordance with method B of JIS K 1557.
(3) Acid value: Measured according to the indicator titration method of JIS K 1557.
(4) Moisture: Measured by a coulometric titration method using a Karl Fischer moisture meter.
(5) Melting point, glass transition temperature: measured by differential scanning calorimetry (measurement temperature range: −100 to 200 ° C.) (6) Viscosity: measured at 75 ° C. using an E-type viscometer.

(7) Measurement of Hazen unit color number (APHA): Based on JIS K 1557, the Hazen unit color number was measured in accordance with JIS K 0071-1 as follows.
(Preparation of standard solution)
A solution in which 1.245 g of potassium chloroplatinate, 1.000 g of cobalt chloride hexahydrate, 500 ml of water and 100 ml of hydrochloric acid are placed in a 1 L measuring flask and completely dissolved and then water is added up to the marked line is prepared. This solution is APHA standard solution no. No. 500 and various standard solutions are No. Prepare a 500 standard solution by diluting with water. For example, APHA standard solution No. 100 is No. 100. Prepare 20.0 ml of 500 standard solution by diluting with 80.0 ml of water.
(Measuring method)
A colorless and transparent flat-bottom glass tube with the same diameter and the same diameter, with the same wall thickness of about 23mm. The colorimetric tube has a marked line at the same height from the bottom so that the liquid volume is about 100ml. Add the sample to the marked line, taking care to avoid bubbles. Next, a suitable standard solution of APHA is placed on a white plate and compared from above, and a standard solution having a concentration closest to the sample is obtained. Is the Hazen unit color number.

(8) Measurement of hardness of polyurethane film A coating film sample was placed on a sample stage, and the amplitude decay time was measured with a pen drum hardness tester (manufactured by BYK-Gardner GmbH, pen drum hardness tester).
The longer the amplitude decay time, the higher the hardness.

Production Example 1
[Production of polycarbonate diol (A)]
In a 500 ml glass round bottom flask equipped with a rectifying column, a stirrer, a thermometer and a nitrogen introduction tube, 199.3 g (2.21 mol) of dimethyl carbonate and 65.2 g (0.47 mol) of 1,4-benzenedimethanol ), 167.2 g (1.41 mol) of 1,6-hexanediol and 0.03 g of titanium tetrabutoxide, while distilling off a mixture of methanol and dimethyl carbonate in a nitrogen stream under normal pressure and stirring. The transesterification reaction was carried out for 5 hours. During this time, the reaction temperature was gradually raised from 95 ° C. to 200 ° C., and the composition of the distillate was adjusted to be the azeotropic composition of methanol and dimethyl carbonate or in the vicinity thereof.
Thereafter, the pressure was gradually reduced to 100 mmHg, and a transesterification reaction was further carried out at 195 ° C. for 4 hours while distilling off a mixture of methanol and dimethyl carbonate with stirring. After completion of the reaction (after completion of distillation of methanol and dimethyl carbonate), the reaction solution was cooled to room temperature to obtain 280 g of polycarbonate diol (A).
The obtained polycarbonate diol (A) has a number average molecular weight of 950, a hydroxyl value of 118 mgKOH / g, an acid value of 0.02 mgKOH / g, a water content of 32 ppm, a melting point of 33 ° C., and a glass transition point of −50.9 ° C. The viscosity was 0.6 Pa · s (75 ° C.) and the Hazen unit color number was 40.

Production Example 2
[Production of polycarbonate diol (B)]
170.2 g (1.89 mol) of dimethyl carbonate, 109.9 g (0.80 mol) of 1,4-benzenedimethanol, 94.0 g (0.80 mol) of 1,6-hexanediol, and 0.02 g of titanium tetrabutoxide Except that it was charged, 230 g of polycarbonate diol copolymer was obtained in the same manner as in Production Example 1.
To the obtained polycarbonate diol copolymer, 2.78 g (0.021 mol) of 1,4-benzenedimethanol and 2.38 g (0.020 mol) of 1,6-hexanediol were further added, and 200 mmHg, 180 ° C. The ester exchange reaction was carried out to obtain 235 g of polycarbonate diol (B).
The obtained polycarbonate diol (B) has a number average molecular weight of 999, a hydroxyl value of 112 mgKOH / g, an acid value of 0.02 mgKOH / g, a water content of 26 ppm, a melting point of 120 ° C., and a glass transition point of −38.3 ° C. The Hazen unit color number was 50.

Example 1
(1) Production of polyurethane polymer solution (I) Into a glass separable flask having an internal volume of 300 ml equipped with a stirrer and a thermometer, 30.46 g of polycarbonate diol (A) obtained in Production Example 1 and 1,4- 5.55 g of butanediol and 235.23 g of dimethylacetamide were added, and the mixture was stirred at a bath temperature of 85 ° C. (internal temperature: 75 to 85 ° C.). After 30 minutes, 24.03 g of 4,4′-diphenylmethane diisocyanate was added and stirred at the same temperature. After 90 minutes, the isocyanate group content was quantified, and the isocyanate group content was 0.10% or less. Therefore, the reaction was terminated, and a colorless and transparent polyurethane polymer solution (I) was obtained.
(2) Production of polyurethane film (I) The polyurethane polymer solution (I) obtained in (1) above was applied to a glass substrate and allowed to stand overnight at room temperature, then at 60 ° C for 1 hour, at 120 ° C for 3 hours. The polyurethane film (I) was obtained by heat curing for a period of time. The hardness of the obtained polyurethane film (I) was 230 seconds in terms of amplitude decay time.

Example 2
A polyurethane polymer solution (II) was produced in the same manner as in Example 1 except that the polycarbonate diol (A) was changed to the polycarbonate diol (B). Further, in the same manner as in Example 1, a polyurethane film (II) was produced from the polyurethane polymer solution (II). The hardness of the obtained polyurethane film (II) was 317 seconds in terms of amplitude decay time.

Comparative Example 1
(1) Production of polyurethane polymer solution (III) A 1-liter glass separable flask equipped with a stirrer and a thermometer was placed in an ETERNACOLL (registered trademark) “UH-100” (1, 6) manufactured by Ube Industries, Ltd. -Polycarbonate diol produced using hexanediol and carbonate ester as raw materials, molar mass: 1000 g / mol, hydroxyl value: 112.2 mg KOH / g) 30.30 g, 1,4-butanediol 5.50 g, dimethylacetamide 235.30 g And stirred at a bath temperature of 85 ° C. (inner temperature 75 ° C. to 85 ° C.). After 30 minutes, 24.60 g of 4,4′-diphenylmethane diisocyanate was added and stirred at the same temperature. After 90 minutes, the isocyanate group content was quantified to find that the isocyanate group content was 0.10% or less, so the reaction was terminated to obtain a colorless and transparent polyurethane polymer solution (III).
(2) Production of polyurethane film (III) Using the polyurethane polymer solution (III) obtained in (1) above, a polyurethane film (III) was obtained in the same manner as in Example 1. The hardness of the obtained polyurethane film (III) was 126 seconds in terms of amplitude decay time.

The polyurethane polymer solution of the present invention is excellent in the strength of a coating film obtained by coating and drying. In addition, it has hydrolysis resistance, durability, heat resistance, and abrasion resistance, and is particularly excellent in hardness, so that it is useful as a raw material for coating agents, paint compositions and the like.
Moreover, according to the manufacturing method of this invention, the polyurethane polymer solution which has the said characteristic can be manufactured efficiently.

Claims

A polyurethane polymer obtained by reacting at least a repeating unit represented by the following formula (1) and having a hydroxyl group at both ends and a polyisocyanate compound (c) and an organic solvent. Polyurethane polymer solution.

(In the formula, Z 1 and Z 2 each independently represent a divalent aliphatic hydrocarbon group having 1 to 10 carbon atoms which may have a substituent.)
The polyurethane polymer solution according to claim 1, wherein the number average molecular weight of the polycarbonate polyol (a) is 200 to 3,000.
The polyurethane polymer solution according to claim 1 or 2, wherein the repeating unit represented by the formula (1) of the polycarbonate polyol (a) is represented by the following formula (2).
The polyurethane polymer solution according to any one of claims 1 to 3, wherein the polycarbonate polyol (a) has a repeating unit represented by the following formula (1) and a repeating unit represented by the following formula (3).

(In the formula, Z 1 and Z 2 are the same as described above, and R 3 represents an optionally substituted divalent hydrocarbon group having 3 to 20 carbon atoms.)
The polyurethane according to claim 4, wherein a molar ratio of [(repeating unit represented by the formula (1)) / (repeating unit represented by the formula (3))] is 1/9 to 9/1. Polymer solution.
A step of obtaining a polyurethane polymer by reacting a polycarbonate polyol (a) containing at least a repeating unit represented by the following formula (1) and having both ends being hydroxyl groups and a polyisocyanate compound (c) in an organic solvent. The method for producing a polyurethane polymer solution according to any one of claims 1 to 5, further comprising:

(In the formula, Z 1 and Z 2 each independently represent a divalent aliphatic hydrocarbon group having 1 to 10 carbon atoms which may have a substituent.)
The method for producing a polyurethane polymer solution according to claim 6, wherein the polycarbonate polyol (a) has a repeating unit represented by the following formula (1) and a repeating unit represented by the following formula (3).

(In the formula, Z 1 and Z 2 are the same as described above, and R 3 represents an optionally substituted divalent hydrocarbon group having 3 to 20 carbon atoms.)
A coating composition containing the polyurethane polymer solution according to any one of claims 1 to 5.