JP2005248063A - Method for producing urethane-urea resin - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a urethane-urea resin particularly capable of providing good dispersion of magnetic substances. <P>SOLUTION: A method for producing the urethane-urea resin comprises reacting a urethane prepolymer (a) having terminal isocyanate groups with an epoxy prepolymer (b) having secondary amino groups. The epoxy prepolymer (b) having secondary amino groups is prepared by reacting a compound (c) having epoxy groups with a compound (d) having primary amino groups. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a urethane urea resin. The urethane urea resin can disperse the magnetic material satisfactorily and can be used as a magnetic material-dispersed resin binder for magnetic recording media.

  Conventionally, urethane resins and urethane urea resins are known to be used as binders for magnetic coatings. The binder is required to simultaneously have excellent dispersibility of the magnetic powder, viscosity characteristics of the coating liquid, coating film properties such as blocking resistance and running durability of the coated material, and the like.

  In order to improve the dispersibility of the magnetic substance, it is common practice to introduce polar groups such as sulfonates and carboxylates into the resin. However, if the concentration of these polar groups in the resin is increased too much, the cohesive strength of the resin is increased and the solubility in the solvent during coating is reduced, resulting in a decrease in the viscosity characteristics of the magnetic coating liquid. It was.

  In order to compensate for this, an example has been given in which a long-chain aliphatic polyol is incorporated into the skeleton to improve the stability in the solvent. However, the use of long-chain polyols leads to a decrease in resin Tg and a decrease in coating film properties. (See Patent Document 1).

In addition, it is generally known that in the production of a magnetic recording medium, an isocyanate curing agent is used in combination at the time of coating to crosslink with a hydroxy group in the binder to improve the physical properties of the coating film. However, the higher the concentration of hydroxy groups in the resin, the better the reactivity with the curing agent. However, in the case of urethane resins, it is difficult to incorporate hydroxy groups other than at the end of the resin, so there are limits to improving curability. It was.
Therefore, a method has been described in which, for example, trimethylolpropane is introduced as a polyfunctional alcohol to cause branching, and the terminal hydroxy group is increased. However, the polyfunctional alcohol is used for its use because it causes gelation during resin synthesis. Was limited and the effect was not sufficient (see Patent Document 2).

Moreover, the physical property of the coating film is improved by hardening the resin. In order to harden the urethane resin, it is common practice to increase the ratio of low molecular diols and increase the concentration of urethane bonds or introduce urea bonds. However, increasing the number of these polar bonds increases the cohesive strength of the resin. However, since the solubility in an organic solvent is lowered, the viscosity characteristics of the coating liquid are lowered.
For example, by regulating the concentration of urethane bonds and urea bonds, the physical properties of the coating film and the solubility in the solvent are balanced, but this method does not solve the above-mentioned problem of reactivity with the curing agent. There was a limit to improving the physical properties of the coating film (see Patent Document 3).

In addition, in order to compensate for these drawbacks of the urethane resin, it is considered to make a composite with another resin. However, in the case of a simple blend, the viscosity characteristics of the coating liquid, the smoothness of the coated product, and the like are reduced due to poor compatibility.
Therefore, a method of modifying an acrylic resin with a monoisocyanate compound when a urethane resin is used in combination with an acrylic resin has been mentioned, but even this method has not led to a drastic solution of compatibility (Patent Document 4). reference).
JP 05-298662 A Japanese Patent Laid-Open No. 06-103526 Japanese Patent Laid-Open No. 06-19821 JP-A-10-149530

  An object of the present invention is to provide a urethane urea resin in which the magnetic substance is particularly well dispersed.

  The present invention relates to a method for producing a urethane urea resin, characterized by reacting a urethane prepolymer (a) having a terminal isocyanate group and an epoxy prepolymer (b) having a secondary amino group.

  In the present invention, the epoxy prepolymer (b) having a secondary amino group is obtained by reacting the compound (c) having an epoxy group with the compound (d) having a primary amino group. The present invention relates to a method for producing a urethane urea resin.

  Moreover, this invention relates to the manufacturing method of the said urethane urea resin whose urethane prepolymer (a) has a polar group.

  Moreover, this invention relates to the manufacturing method of the said urethane urea resin whose sum of the urea group equivalent of a urethane urea resin and a urethane group equivalent is 0.5-5 mmol / g.

  Moreover, this invention relates to the urethane urea resin manufactured by the said manufacturing method.

  The present invention also relates to a magnetic material-dispersed resin comprising the urethane urea resin and a magnetic material.

  Moreover, this invention relates to the magnetic coating material containing the said magnetic body dispersion resin.

  The present invention also relates to a magnetic recording medium comprising the magnetic material-dispersed resin.

  According to the present invention, it is possible to provide a urethane urea resin in which the magnetic substance is particularly well dispersed.

  The present invention can be obtained by reacting a urethane prepolymer (a) having a terminal isocyanate group and an epoxy prepolymer (b) having a secondary amino group.

[(A) Urethane prepolymer having terminal isocyanate group]
The urethane prepolymer (a) having a terminal isocyanate group used in the present invention is obtained by polymerizing a polyol with a polyisocyanate. Further, if necessary, the polyol or polyisocyanate has a polar functional group such as SO ₃ M group, COOM group, P═O (OM) ₂ group, (M: hydrogen atom or alkali metal, or ammonium). It is preferable to use what is.

<Polyol>
Examples of the polyol that can be used in the production of the urethane prepolymer (a) include low-molecular diols or polymer diols such as polyester diols, polycarbonate diols, polyester polycarbonate diols, and polyether diols. Polyols having three or more hydroxyl groups can also be used. The urethane prepolymer can be formed using one or more of these polyols.

(Low molecular diol)
Low molecular diols include ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, octanediol, 1,4-butylenediol, dipropylene glycol, cyclohexanedimethanol, bisphenol A, bisphenol F, bisphenol S, hydrogenated bisphenol A, etc. Of saturated or unsaturated low molecular weight diols.

(Polymerdiol)
Polyester diols include the above low molecular diols, alkyl glycidyl ethers such as n-butyl glycidyl ether and 2-ethylhexyl glycidyl ether, monocarboxylic acid glycidyl esters such as versatic acid glycidyl ester, adipic acid, phthalic acid, Dicarboxylic acids such as isophthalic acid, terephthalic acid, maleic acid, fumaric acid, succinic acid, oxalic acid, malonic acid, glutaric acid, pimelic acid, suberic acid, azelaic acid, sebacic acid or the like, and anhydrides and dimer acids thereof. And polyester diols obtained by dehydration condensation or polymerization; polyester diols such as polycaprolactone diol obtained by ring-opening polymerization of a cyclic ester compound. Examples of the polycarbonate diol include polycarbonate diols obtained by reacting a low molecular diol with carbonate. Polyether diols include polyether diols such as polymers or copolymers of ethylene oxide, propylene oxide, tetrahydrofuran, etc .; polybutadiene glycols; addition of ethylene oxide or propylene oxide to bisphenol A, bisphenol F, hydrogenated bisphenol A And glycols obtained by treatment.

<Polyisocyanate>
As the polyisocyanate, various known polyisocyanates that are aromatic, aliphatic, or alicyclic can be used.
For example, 1,5-naphthylene diisocyanate, 4,4′-diphenylmethane diisocyanate, 4,4′-diphenyldimethylmethane diisocyanate, 4,4′-dibenzyl isocyanate, dialkyldiphenylmethane diisocyanate, tetraalkyldiphenylmethane diisocyanate, 1,3- Aromatic polyisocyanates such as phenylene diisocyanate, 1,4-phenylene diisocyanate, tolylene diisocyanate, xylylene diisocyanate, m-tetramethylxylylene diisocyanate, butane-1,4-diisocyanate, hexamethylene diisocyanate, isopropylene diisocyanate, methylene diisocyanate Aliphatic polyisocyanates such as 2,2,4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate , Cyclohexane-1,4-diisocyanate, isophorone diisocyanate, lysine diisocyanate, dicyclohexylmethane-4,4′-diisocyanate, 1,3-bis (isocyanatemethyl) cyclohexane, methylcyclohexane diisocyanate, and the like, dimers Examples include dimerized isocyanate obtained by converting a carboxyl group of an acid into an isocyanate group.
The production of the urethane prepolymer (a) can be carried out by a conventionally known method, and can be carried out at a temperature of 30 to 150 ° C. in the presence or absence of an organic solvent.

(Polar group)
The polyurethane resin of the present invention may contain a polar functional group such as an SO ₃ M group, a COOM group, or a P═O (OM) ₂ group (M: a hydrogen atom, an alkali metal, or ammonium) as necessary.

Examples of the method for introducing the SO ₃ M group include sulfonic acid metal salt-containing glycols such as 2-sodium sulfo-1,4-butanediol and 2-potassium sulfo-1,4-butanediol, 5-sodium sulfoisophthalic acid, 5 -Dicarboxylic acids containing sulfonic acid metal salts such as potassium sulfoisophthalic acid and sodium sulfosuccinic acid, metal salts or quaternary ammonium salts of bishydroxyethyl taurine, etc. are used as the above-mentioned long-chain polyol raw materials and / or as low molecular diols. A method is mentioned.

  COOM group introduction methods include bis (2.2-hydroxymethyl) propionic acid, 2,3-dihydroxypropionic acid, 2,3-dihydroxy-methylpropionic acid, 2,2-dihydroxymethylpropionic acid, 2,3 -Dihydroxy-2- (1-methylethyl) butanoic acid, 3,1 1-dihydroxytetradecanoic acid, 9,10-dihydroxyoctadecanoic acid, 1,2-dihydro-6-hydroxy-2-oxy-4-pyridinecarboxylic acid Examples include a method of using an acid, 2,3-dihydroxybutanedioic acid, 2,3-dihydroxy-2-methylbutanedioic acid, or the like, and a salt thereof as the above-mentioned long-chain polyol raw material and / or as a low-molecular diol. .

(Multifunctional / monofunctional)
For the purpose of improving the cohesive strength of the coating film, a diol such as trimethylolpropane can be used in combination as long as it does not gel during synthesis. In addition, the resin molecular weight may be controlled using a monofunctional alcohol or monofunctional isocyanate in combination.

(catalyst)
In the production of the urethane prepolymer (a), a reaction catalyst can be added as necessary. Examples of such a catalyst include tin octylate, monobutyltin triacetate, monobutyltin monooctylate, and monobutyltin. Organotin compounds such as monoacetate, monobutyltin maleate, dibutyltin diacetate, dibutyltin dioctoate, dibutyltin distearate, dibutyltin dilaurate, dibutyltin maleate; organotitanium such as tetraisopropyl titanate, tetra-n-butyl titanate Compounds; tertiary amines such as triethylamine, N, N-diethylcyclohexylamine, N, N, N ′, N′-tetramethylethylenediamine, triethylenediamine and the like.

(ratio)
The polyol and the polyisocyanate can be combined at an arbitrary ratio, but the isocyanate group equivalent must be larger than the hydroxy group equivalent in order for the isocyanate group to be present at the resin terminal.

[(B) Epoxy prepolymer]
The epoxy prepolymer (b) having a secondary amino group used in the present invention is obtained, for example, by reacting a compound (c) having an epoxy group with a compound (d) having a primary amino group. .

The compound (c) having an epoxy group is preferably a diglycidyl compound,
Epoxy resins such as bisphenol A type, bisphenol F type, bisphenol S type, biphenyl type, glycidyl ester type, bisphenol A, bisphenol F, bisphenol S, biphenyl, hydrogenated bisphenol A, neopentyl glycol, 1,6-hexanediol, Examples thereof include diglycidyl ethers such as polyethylene, polypropylene, polybutadiene, bisphenol fluorene, biscresol fluorene, and bisphenoxyethanol fluorene.

  The compound (d) having a primary amino group is propylamine, isopropylamine, butylamine, amylamine, hexylamine, heptylamine, octylamine, nonylamine, decylamine, undecylamine, dodecylamine, tridecylamine, tetradecylamine , Aliphatic amines such as pentadecylamine and cetylamine, aromatic amines such as benzylamine, aniline, o-toluidine, m-toluidine and p-toluidine, alicyclic amines such as cyclobutylamine, cyclopentylamine and cyclohexylamine, allylamine And unsaturated amines.

(Multifunctional and monofunctional combination)
A phenoxy resin or the like may be used in combination as long as it does not gel during synthesis, or a secondary monoamine such as diethylamine, dipropylamine, or dibutylamine, or a monoglycidyl ether compound may be used in combination for controlling the molecular weight. .

(Ratio and reaction conditions)
When primary amino group equivalent / epoxy group equivalent = 1, both ends of the compound (c) having an epoxy group are in a state of being secondary amino groups. When 0.5 = <primary amino group equivalent / epoxy group equivalent <1, when reacted at a relatively low temperature of 50 ° C. or less for a short time, both ends of the compound (c) having an epoxy group are A mixture of a secondary amino group and an epoxy group at one end is obtained. This residual epoxy group is effective in dispersing the magnetic material (see Japanese Patent Application Laid-Open No. 08-235564). However, since the secondary amino group and the epoxy group are reactive, they are uread quickly and consume the secondary amino group. There is a need to. Further, when this is sufficiently reacted at a high temperature, the secondary amino group further reacts with an epoxy group, and the compound (c) having an epoxy group is bonded with a tertiary amino group, and both ends are in the form of secondary amino groups. It becomes.

[Urealation reaction of (a) and (b)]
By subjecting the isocyanate group of the urethane prepolymer (a) and the secondary amino group of the epoxy prepolymer (b) to urea together with a monoamine or monoisocyanate as necessary, the desired urethane urea resin is obtained.

(Amine / isocyanate ratio)
When considering the reaction between the urethane prepolymer (a) and the epoxy prepolymer (b),
When the isocyanate group equivalent of the urethane prepolymer (a) is less than the secondary amino group equivalent of the epoxy prepolymer (b), the end of the urethane urea resin becomes a secondary amino group. The presence of a large excess of secondary amino groups is preferable because when the acidic polar group is used for dispersing the magnetic substance, the dispersion is inhibited and at the same time the viscosity stability after mixing with the isocyanate curing agent is impaired. Absent.
When the isocyanate group equivalent of the urethane prepolymer (a) is larger than the secondary amino group equivalent of the epoxy prepolymer (b), the end of the urethane urea resin becomes an isocyanate group. In this case, it is preferable to crush residual isocyanate groups with monoamine or monoalcohol in view of the varnish stability over time.

(Weight ratio)
The weight ratio of the urethane prepolymer (a) and the epoxy prepolymer (b) may be any ratio depending on the purpose, but if the ratio of the urethane prepolymer (a) becomes too high, the hydroxyl value of the urethane urea resin is lowered and cured. Reactivity with the agent decreases. On the contrary, when the ratio of the epoxy prepolymer (b) is too high, the dispersibility of the magnetic material is lowered.

(Reaction conditions)
The reaction can be carried out by a conventionally known method, and the urethane prepolymer (a) may be added to the epoxy prepolymer (b) or vice versa. However, the reaction temperature is preferably 60 ° C. or lower in order to avoid the reaction between the isocyanate group and the hydroxyl group of the epoxy prepolymer.

(Sum of urea group equivalent and urethane group equivalent)
The sum of the urea group equivalent and the urethane group equivalent in the urethane urea resin obtained in the present invention is preferably 0.5 mmol / g to 5 mmol / g. More preferably, 1 to 3 mmol / g is preferable. If it exceeds 5 mmol / g, the dispersibility may decrease.

(solvent)
The synthesis of the urethane prepolymer (a), the synthesis of the epoxy prepolymer (b), and the synthesis of the urethane urea resin described above can be performed in the absence of a solvent or an organic solvent. Further, an organic solvent may be added or added after the prepolymer production for the purpose of reducing the viscosity. Examples of the organic solvent that can be used in this case include esters such as ethyl acetate and butyl acetate; ethers such as tetrahydrofuran and dioxane; aromatic hydrocarbons such as toluene and xylene; There is no. Ketones such as acetone, methyl ethyl ketone, and cyclohexanone can be used, but ketimine may be generated during urea formation. In addition, secondary alcohols such as isopropyl alcohol and tertiary alcohols such as t-butyl alcohol are relatively low in reactivity with isocyanates, so that they can be reacted even if they are present during urea formation.

(Stabilizer)
Various stabilizers can be used in the polyurethane urea resin of the present invention as required. Various performances can be remarkably stabilized by adding a stabilizer against ultraviolet rays such as substituted benzotriazoles and a stabilizer against thermal oxidation such as a phenol derivative as a stabilizer.

[Magnetic paint]
As a method for producing a magnetic paint, a magnetic paint binder (binder), a solvent and a magnetic material are mixed in advance by a premixer if necessary, and then mixed and dispersed (ball mill, paint conditioner, sand grinder, sand mill, plast mill, etc.). A method in which a magnetic material is dispersed and filtered is exemplified.
If necessary, the magnetic coating of the present invention includes carbon fine particles as an antistatic agent, nonpolar metal oxide fine particles as an abrasive, and higher fatty acids, fatty acid esters, liquid paraffin as lubricants for reducing the friction coefficient. Lecithin or the like can be added using siloxanes and fluorocarbons as dispersants.

  Further, as the binder component, the urethane urea resin of the present invention is used. If necessary, a commonly used thermoplastic polyurethane resin, vinyl chloride-vinyl acetate copolymer, fiber-based resin, polyvinyl butyral resin, It can also be used to improve the dispersibility of magnetic powder and the smoothness of the magnetic layer surface by using a thermoplastic polyester resin, vinyl chloride-vinyl propionate copolymer, epoxy resin, phenoxy resin, etc. .

(Curing agent)
Furthermore, when a normal polyisocyanate curing agent is added as necessary, high reactivity with the curing agent is obtained due to the high hydroxy group content of the urethane urea resin of the present invention, and a strong coating film is obtained. Examples of the polyisocyanate curing agent include compounds having a molecular end obtained by reacting a low molecular weight polyisocyanate having two or more isocyanate groups with an isocyanate group, such as Coronate L, Coronate 3041, Coronate 2030 manufactured by Nippon Polyurethane Industry. Etc.

[Application of magnetic paint, magnetic recording medium]
This magnetic paint can be applied to a support film for a magnetic recording medium to produce a magnetic recording medium (such as a magnetic tape).
Examples of the support film include films of paper, cellophane, acetate, polyester (PET), reinforced polyester (PEN), polyimide, and the like.
When the magnetic paint is applied to the support film, the coating thickness is usually from several μm to several tens of μm.
Examples of the coating method include a doctor blade method and a transfer printing method (gravure method, reverse roll method, etc.).
The film coated with the magnetic paint is used as a magnetic recording medium after undergoing steps such as orientation, drying, surface processing, cutting and winding. A magnetic recording medium is generally composed of a support film and a magnetic layer (such as a magnetic material and a binder for magnetic paint), but an intermediate layer (undercoat layer) is provided between the support film and the magnetic layer. Those having a magnetic layer on both sides of the support film, those having magnetic layers with different magnetic properties stacked, those having a protective layer on the magnetic layer, those having a back coat layer on the support film, etc. is there.

(Use for intermediate layer and back coat layer)
In addition to the magnetic layer, the urethane urea resin of the present invention is effective even when used for an intermediate layer or a backcoat layer because of its excellent pigment dispersibility and reactivity with a curing agent.

(Other uses and applications)
The urethane urea resin obtained by the present invention is excellent in magnetic substance dispersibility and reactivity with a curing agent, and at the same time, excellent in adhesion to a film or a metal surface, and excellent in bending followability even though it is a tough coating film. Since it has mechanical properties, it can be used in a wide range of applications such as paint binders, adhesives and artificial leather for various substrates.
In addition, the hydroxyl group of the epoxy part can be used for various modifications. For example, glycidyl methacrylate or 2-([1′-methylpropylideneamino] carboxyamino) ethyl methacrylate is reacted after synthesis of the urethane urea resin. Thus, it is possible to incorporate an unsaturated bond into the resin, thereby providing electron beam curability such as EB and UV.

  Hereinafter, the present invention will be described in more detail with reference to examples. In the text, parts and% represent parts by weight and% by weight unless otherwise specified.

Production Example 1A
In a four-necked flask equipped with a thermometer, a stirrer, and a reflux condenser, 24.2 parts of a polyester diol having a hydroxyl value of 110 mg KOH / g, 11.2 parts of 1,6-hexanediol, N, N-bis (hydroxy Ethyl) Ethylsulfonic acid tetraethylammonium salt 1.3 parts and tolylene diisocyanate 23.4 parts were maintained in cyclohexanone 56 parts with 0.02 part tin octylate at 130 ° C. for 2 hours, then 67.2 parts toluene, 30 ethyl acetate Part was added to obtain a urethane prepolymer solution.
Production Example 1B
Using the same apparatus as in Production Example 1A, 442.4 parts of a bisphenol A type epoxy resin having an epoxy equivalent of 931 g / eq was dissolved in 292.8 parts of toluene and 427.2 parts of ethyl acetate, to which 19.2 parts of butylamine, 18.4 parts of dibutylamine was added and maintained at 85 ° C. for 5 hours to obtain an epoxy prepolymer solution (weight average molecular weight 9000).

Example 1
In the same apparatus as in Production Example 1A, 177.5 parts of the urethane prepolymer solution obtained in Production Example 1A (resin solid content: 50 parts) was maintained at 40 ° C. in a stirred state, and the epoxy prepolymer obtained in Production Example 1B. 125 parts of a polymer solution (resin solid content 50 parts), 23.3 parts of isopropyl alcohol, 6.9 parts of toluene, and 0.5 part of ethyl acetate were added dropwise over 20 minutes. After maintaining the temperature at 40 ° C. for 1 hour after completion of the dropping, the temperature was raised to 80 ° C. and maintained for 2 hours to obtain a urethane urea resin (weight average molecular weight 32,000, hydroxyl value was 102 mgKOH / g, urea group equivalent and urethane group equivalent The sum is 2.2 mmol / g).

Production Example 2A
Using the same apparatus as in Production Example 1A, 20.9 parts of a polyester diol having a hydroxyl value of 110 mgKOH / g, 11.8 parts of cyclohexanedimethanol, 1.3 parts of N, N-bis (hydroxyethyl) ethylsulfonic acid tetraethylammonium salt Then, 26.0 parts of isophorone diisocyanate was held at 130 ° C. for 2 hours together with 0.02 part of tin octylate in 56 parts of cyclohexanone, and then 67.2 parts of toluene and 30 parts of ethyl acetate were added to obtain a urethane prepolymer solution.
Example 2
The epoxy prepolymer obtained in Production Example 1B, in which 177.5 parts of urethane prepolymer solution obtained in Production Example 2A (50 parts of resin solid content) is maintained at 40 ° C. in a stirred state in the same apparatus as in Production Example 1A. 125 parts of a solution (resin solid content: 50 parts), 23.3 parts of isopropyl alcohol, 6.9 parts of toluene, and 0.5 part of ethyl acetate were added dropwise over 20 minutes. After maintaining the temperature at 40 ° C. for 1 hour after completion of the dropping, the temperature was raised to 80 ° C. and maintained for 2 hours to obtain a urethane urea resin (weight average molecular weight 30000, hydroxyl value 102 mgKOH / g, urea group equivalent and urethane group equivalent The sum is 1.9 mmol / g).

Production Example 3A
Using the same apparatus as in Production Example 1A, 23.2 parts of polytetramethylene glycol having a hydroxyl value of 110 mg KOH / g, 13.1 parts of cyclohexanedimethanol, tetraethylammonium salt of N, N-bis (hydroxyethyl) ethylsulfonic acid After 3 parts and 22.5 parts of tolylene diisocyanate were held at 130 ° C. for 2 hours together with 0.02 part of tin octylate in 56 parts of cyclohexanone, 67.2 parts of toluene and 30 parts of ethyl acetate were added to obtain a urethane prepolymer solution. .
Example 3
The epoxy prepolymer obtained in Production Example 1B, in which 177.5 parts of urethane prepolymer solution obtained in Production Example 3A (resin solid content: 50 parts) is maintained at 40 ° C. in a stirred state in the same apparatus as in Production Example 1A. 125 parts of a solution (resin solid content: 50 parts), 23.3 parts of isopropyl alcohol, 6.9 parts of toluene, and 0.5 part of ethyl acetate were added dropwise over 20 minutes. After maintaining the temperature at 40 ° C. for 1 hour after completion of the dropping, the temperature was raised to 80 ° C. and maintained for 2 hours to obtain a urethane urea resin (weight average molecular weight 29000, hydroxyl value was 102 mgKOH / g, urea group equivalent and urethane group equivalent The sum is 2.2 mmol / g).

Production Example 4A
Using the same apparatus as in Production Example 1A, 19.7 parts of polycarbonate diol having a hydroxyl value of 113 mgKOH / g, 9.4 parts of 1,6-hexanediol, tetraethylammonium salt of N, N-bis (hydroxyethyl) ethylsulfonic acid 1 3 parts, 29.7 parts of 4,4'-methylenebis (cyclohexyl isocyanate) were held in 130 parts of cyclohexanone with 0.02 parts of tin octylate at 130 ° C for 2 hours, and then 67.2 parts of toluene and 30 parts of ethyl acetate were added. In addition, a urethane prepolymer solution was obtained.
Example 4
The epoxy prepolymer obtained in Production Example 1B, in which 177.5 parts of urethane prepolymer solution obtained in Production Example 4A (50 parts of resin solid content) is maintained at 40 ° C. in a stirred state in the same apparatus as in Production Example 1A. 125 parts of a solution (resin solid content: 50 parts), 23.3 parts of isopropyl alcohol, 6.9 parts of toluene, and 0.5 part of ethyl acetate were added dropwise over 20 minutes. After maintaining the temperature at 40 ° C. for 1 hour after completion of the dropping, the temperature was raised to 80 ° C. and maintained for 2 hours to obtain a urethane urea resin (weight average molecular weight 31000, hydroxyl value was 102 mgKOH / g, urea group equivalent and urethane group equivalent The sum is 1.9 mmol / g).

Production Example 5A
Using the same apparatus as in Production Example 1A, 29.1 parts of polyester diol having a hydroxyl value of 110 mg KOH / g, 13.5 parts of 1,6-hexanediol, tetraethylammonium salt of N, N-bis (hydroxyethyl) ethyl sulfonate 3 parts and 28.1 parts of tolylene diisocyanate were held in 130 parts of cyclohexanone and 0.02 part of tin octylate at 130 ° C. for 2 hours, and then 67.2 parts of toluene and 30 parts of ethyl acetate were added to obtain a urethane prepolymer solution. .
Production Example 5B
Using the same apparatus as in Production Example 1A, dissolved in 46.2 parts of bisphenol A type epoxy resin having an epoxy equivalent of 2514 g / eq, 36.6 parts of toluene, and 53.4 parts of ethyl acetate, 1.8 parts of octylamine were added thereto. And maintained at 85 ° C. for 5 hours to obtain an epoxy prepolymer solution

Example 5
In the same apparatus as in Production Example 1A, 187.7 parts of the urethane prepolymer solution obtained in Production Example 5A (resin solid content: 60 parts) was maintained at 40 ° C. with stirring, and the epoxy prepolymer obtained in Production Example 5B. 115 parts of a polymer solution (resin solid content: 40 parts), 2.6 parts of dibutylamine, 23.3 parts of isopropyl alcohol, 6.9 parts of toluene, and 0.5 part of ethyl acetate were added dropwise over 20 minutes. After maintaining the temperature at 40 ° C. for 1 hour after completion of the dropping, the temperature was raised to 80 ° C. and maintained for 2 hours to obtain a urethane urea resin (weight average molecular weight 61000, hydroxyl value 78 mgKOH / g, urea group equivalent and urethane group equivalent The sum is 2.6 mmol / g).

Production Example 6A
Using the same apparatus as in Production Example 1A, 25.0 parts of polyester diol having a hydroxyl value of 110 mgKOH / g, 11.6 parts of 1,6-hexanediol, and 23.5 parts of tolylene diisocyanate in 56 parts of cyclohexanone tin octylate After holding at 130 ° C. for 2 hours together with 0.02 part, 67.2 parts of toluene and 30 parts of ethyl acetate were added to obtain a urethane prepolymer solution.
Example 6
The epoxy prepolymer obtained in Production Example 1B, in which 177.5 parts of urethane prepolymer solution obtained in Production Example 6A (resin solid content: 50 parts) is maintained at 40 ° C. in a stirred state in the same apparatus as in Production Example 1A. 125 parts of a solution (resin solid content: 50 parts), 23.3 parts of isopropyl alcohol, 6.9 parts of toluene, and 0.5 part of ethyl acetate were added dropwise over 20 minutes. After maintaining the temperature at 40 ° C. for 1 hour after completion of the dropping, the temperature was raised to 80 ° C. and maintained for 2 hours to obtain a urethane urea resin (weight average molecular weight 38000, hydroxyl value was 102 mgKOH / g, urea group equivalent and urethane group equivalent The sum is 2.2 mmol / g).

Comparative production example 1
Using the same apparatus as in Production Example 1A, 52.0 parts of polyester diol having a hydroxyl value of 110 mgKOH / g, 24.1 parts of 1,6-hexanediol, tetraethylammonium salt of N, N-bis (hydroxyethyl) ethylsulfonic acid 2 .8 parts, 41.2 parts of tolylene diisocyanate were held in 130 parts of cyclohexanone and 0.02 part of tin octylate at 130 ° C. for 4 hours, and then 112 parts of toluene, 84 parts of ethyl acetate and 28 parts of isopropyl alcohol were added. (Weight average molecular weight 24000, hydroxyl value 25 mgKOH / g, urea group equivalent 0, urethane group equivalent 4.6 mmol / g).

Examples 7 to 12 (coating)
The following ratios were blended and dispersed for 16 hours with a paint shaker to obtain a magnetic coating solution.
γ-Fe ₂ O ₃ fine powder 100 parts Resin (solid content) 20 parts Toluene 144 parts Ethyl acetate 108 parts Isopropyl alcohol 36 parts Cyclohexanone 72 parts 1 mmφ zirconium 480 parts

Comparative Example 1 (Urethane only)
In the same manner as in Example 7, a magnetic coating liquid was obtained using the urethane resin obtained in Comparative Production Example 1.

Comparative Example 2 (epoxy only)
In the same manner as in Example 7, an attempt was made to obtain a magnetic coating liquid using the epoxy prepolymer obtained in Example 1B, but it was not dispersed at all.

Comparative Example 3 (no urea)
In the same manner as in Example 7, an attempt was made to obtain a magnetic coating liquid using 10 parts of the urethane resin solid content obtained in Comparative Production Example 1 and 10 parts of the epoxy prepolymer solid content obtained in Example 1B. It was unsuitable as a coating solution because it was not fluid.

It added and mixed well with the ratio of 1 part of polyisocyanate type hardening | curing agent (Coronate L by Nippon Polyurethane Industry) with respect to 160 parts of coating liquids obtained in Examples 7-12 and Comparative Examples 1-3, and the following methods evaluated.
Coating liquid viscosity: measured with an ultrasonic viscometer (YAMACO DIGITAL VISCOMATE MODEL VM-100A) at a liquid temperature of 25 ° C.
Application: The coating liquid was applied on PET having a film thickness of 50 μm so as to be 3 μm after drying, air-dried, and aged at 60 ° C. for 20 hours.
Gloss: The 60-degree gloss of the coating film was measured on white paper by a micro TRI gloss manufactured by BYK.
Curability: The surface of the coating film was lightly rubbed with a cotton swab impregnated with methyl ethyl ketone, and the number of reciprocations until the color was transferred to the cotton swab was measured.
×: 5 times or less, Δ: 5 times or more and less than 10 times, ○: 10 times or more The results are shown in Table 1.

  As is apparent from Table 1, a paint satisfying both curability and dispersibility (gloss) was obtained.

Claims (8)

A method for producing a urethane urea resin, comprising reacting a urethane prepolymer (a) having a terminal isocyanate group and an epoxy prepolymer (b) having a secondary amino group. The urethane urea resin according to claim 1, wherein the epoxy prepolymer (b) having a secondary amino group is obtained by reacting the compound (c) having an epoxy group with the compound (d) having a primary amino group. Manufacturing method. The method for producing a urethane urea resin according to claim 1 or 2, wherein the urethane prepolymer (a) has a polar group. The method for producing a urethane urea resin according to any one of claims 1 to 3, wherein the sum of the urea group equivalent and the urethane group equivalent of the urethane urea resin is 0.5 to 5 mmol / g. A urethane urea resin produced by the production method according to claim 1. A magnetic material-dispersed resin comprising the urethane urea resin according to claim 5 and a magnetic material. A magnetic paint comprising the magnetic material-dispersed resin according to claim 6. A magnetic recording medium comprising the magnetic material-dispersed resin according to claim 6.