JPH0326209B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to polyester-based polyurethane resins, and more particularly to polyester-based polyurethane resins that have double bonds at least at both ends of the molecule and are cured by electron beam irradiation. Conventionally, various types of resins have been synthesized that have double bonds in their molecules and can be cleaved by electron beam irradiation to form crosslinked network structures. Also,
Polyester polyurethane has a hydrophilic sulfonic acid group in its molecule but no double bonds.
It was found that when used in a magnetic paint, the dispersibility was good, and when applied to a magnetic tape, the abrasion resistance was good, but favorable results were not obtained in terms of solvent resistance. Therefore, the present inventors particularly aimed to maintain the good dispersibility of conventional polyester polyurethane resins into which sulfonic acid groups have been introduced, as well as excellent abrasion resistance when applied to magnetic tapes, as well as to maintain solvent resistance. As a result of intensive research into electron beam curable resins with excellent properties, we discovered that the chain was extended using a diisocyanate compound based on a copolyester having a sulfonic acid metal base in the molecule and at least hydroxyl groups at both ends. By reacting the polyester-based polyurethane with an acrylic or methacrylic monomer that has a hydroxyl group and a double bond at the end of the molecule, double bonds are introduced into both ends of the polyester-based polyurethane. Therefore, when applied to magnetic paints that are cured with electron beams and used especially for magnetic tapes, etc.
In addition to the good dispersibility and abrasion resistance of conventional electron beam curable resins, it was found that electron beam curable resins with excellent solvent resistance could be obtained, leading to the completion of the present invention. . The carboxylic acid component of the polyester resin used in the present invention includes aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, orthophthalic acid, and 1,5-naphthalic acid, succinic acid, adipic acid, azelaic acid, sebacic acid, and dodecane acid. Dicarboxylic acids such as aliphatic dicarboxylic acids such as dicarboxylic acids, aromatic oxycarboxylic acids such as p-oxybenzoic acid, p-(2-hydroxyethoxy)benzoic acid, tricarboxylic acids such as trimellitic acid, trimesic acid, pyromellitic acid, and Examples include tetracarboxylic acid. Particularly preferred carboxylic acids include terephthalic acid, isophthalic acid, adipic acid, and sebacic acid. The polyhydric alcohol component, which is another component of the polyester resin used in the present invention, includes ethylene glycol, propylene glycol, 1,
3-propanediol, 1,4-butanediol, 1,5-pentanediol, neopentyl glycol, 1,6-hexanediol, 2,2,
Aliphatic diols such as 4-trimethyl-1,3-pentanediol or substituted derivatives thereof, 1,4
- Alicyclic diols such as cyclohexanedimethanol, diols such as polyalkylene glycols such as diethylene glycol, dipropylene glycol, polyethylene glycol, polypropylene glycol, and polytetramethylene glycol, ethylene oxide adducts or propylene oxide adducts of bisphenol A , oxides such as alkylene oxide adducts of aromatic diols such as ethylene oxide adducts or propylene oxide adducts of hydrogenated bisphenol A, and the like. Further, polyhydric alcohols such as triols or tetraols such as trimethylolethane, trimethylolpropane, glycerin, and pentaerythritol can also be used, but these polyhydric alcohols are preferably used in combination with diols. Examples of the polycarboxylic acid having a sulfonic acid metal group, which is another component of the copolymerized polyester resin used in the present invention, include 2-sodium sulfoterephthalic acid, 2-potassium sulfoterephthalic acid, 5-sodium sulfoisophthalic acid, −
Preferred examples include aromatic dicarboxylic acids containing an alkali metal sulfonate base such as potassium sulfoisophthalic acid; Any of these can be used. As the sulfonic acid metal base it is preferred to use an alkali metal base.
The content of the carboxylic acid component containing these sulfonic acid metal bases is preferably about 0.2 mol% to 30 mol% based on the total carboxylic acid component.
Preferably, it is about 0.5 mol% to 10 mol%.
If the carboxylic acid component having such a sulfonic acid metal base is too small, an electron beam curable resin with excellent dispersibility cannot be obtained, and if the carboxylic acid component is too large, the solubility in general-purpose solvents will be poor. Good paint cannot be obtained. In the present invention, at least the hydroxyl groups and isocyanate groups at both ends of the copolymerized polyester resin as described above are bonded to each other to obtain a chain-extended polyester polyurethane. The diisocyanate compounds used for this chain extension include aliphatic diisocyanates such as tetramethylene diisocyanate and hexamethylene diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate, 2,4-tolylene diisocyanate, 2,6- Tolylene diisocyanate, m-xylylene diisocyanate, p-xylylene diisocyanate, diphenylmethane diisocyanate, 3,3'-dimethoxy-4,4'-biphenylene diisocyanate, 3,3'-dimethyl-4,4'- Biphenylene diisocyanate, 4,
4'-diisocyanate diphenyl ether, 1,
Aromatic diisocyanates such as 5-naphthalene diisocyanate and 2,4-naphthalene diisocyanate, cycloaliphatic diisocyanates such as 1,3-diisocyanatemethylcyclohexane, 1,4-diisocyanatemethylcyclohexane, 4,4'-diisocyanate dicyclohexylmethane, and isophorone diisocyanate. Examples include. The compound used to introduce a double bond into at least both ends of the polyester polyurethane mentioned above is an acrylic or methacrylic monomer having a hydroxyl group and a double bond at the molecular end. is used. Such monomers have the general formula: (In the formula, R ₁ means a hydrogen atom or a methyl group, and R ₂ means an unsubstituted or substituted alkylene group.) In the general formula, the alkylene group is a linear or branched divalent saturated hydrocarbon residue,
It has 1 to 12 carbon atoms. This alkylene group also includes a halogen atom, an alkyloxy group having 1 to 4 carbon atoms optionally substituted with 1 to 3 halogen atoms, an alkenyloxy group having 2 to 4 carbon atoms, and an alkenyloxy group having 2 to 4 carbon atoms. may be substituted with 2 to 4 substituents such as alkenylcarbonyloxy groups. Preferred examples of the compounds represented by the above general formula include 2-hydroxyethyl ester, 2-hydroxypropyl ester, 2-hydroxybutyl ester, 2-hydroxyoctyl ester, and 2-hydroxypropyl ester of acrylic acid or methacrylic acid.
-Hydroxydodecyl ester, 2-hydroxy-3-chloropropyl ester, 2-hydroxy-3-acryloxypropyl ester, 2-hydroxy-3-methacryloxypropyl ester, 2-hydroxy-3-acetoxypropyl ester, 2-hydroxy -3-chloroacetoxypropyl ester, 2-hydroxy-3-dichloroacetoxypropyl ester, 2-hydroxy-3-trichloroacetoxypropyl ester,
Examples include 2-hydroxy-3-crotonyloxypropyl ester and 2-hydroxy-3-allyloxy ester. In addition to these preferred compounds, any monomer having an active hydrogen that reacts with the isocyanate group of the polyester polyurethane and an acrylic or methacrylic double bond can be applied to the present invention. The polyester polyurethane resin according to the present invention having the above-mentioned structure has double bonds introduced at both ends of the polyester polyurethane main chain, and has a total molecular weight of about 10,000 to about 10,000.
50,000, and the carboxylic acid component further having a sulfonic acid metal group is about 0.2 to 30 mol %, preferably about 0.5 to 10 mol %, based on the total carboxylic acid component.
It is contained in mol%. The electron beam curable resin according to the present invention can be produced according to a conventional method. For example, using the aforementioned carboxylic acids, carboxylic acids containing sulfonic acid metal bases, and polyhydric alcohols,
For example, a copolyester resin having a molecular weight of preferably about 1,000 to 3,000 is first produced according to a conventional method, and then a diisocyanate compound is reacted with the copolyester resin to form a hydroxyl group on at least both ends of the copolyester resin and the isocyanate. After the above-mentioned copolymerized polyester resin is chain-extended via the urethane bond, the isocyanate groups at both ends are reacted with the above-mentioned acrylic or methacrylic monomer, and the isocyanate groups at both ends are reacted. A polyester polyurethane resin can be produced by introducing an acrylic or methacrylic double bond. In this case, the copolymerized polyester resin is chain-extended via the terminal diisocyanate so as to have an appropriate molecular weight, and free isocyanate groups are present at both of the chain-extended ends. A monomer having an acrylic or methacrylic double bond is reacted with the isocyanate group portion. The electron beam curable resin according to the present invention produced in this manner can be used particularly as a binder for magnetic recording media such as magnetic tapes. This resin has an extremely hydrophilic sulfonic acid metal base in its molecule, so it is an inorganic powder with hydrophilic groups on the surface that is used for the magnetic layer formed by coating it on a non-magnetic support. It has excellent dispersibility when used as a binder for magnetic particles such as γ-Fe ₂ O ₃ . Therefore, a magnetic layer obtained by using such a resin as a binder and curing it by irradiating it with an electron beam has excellent surface properties, so a magnetic recording medium with excellent surface properties can be obtained. It will be done. Furthermore, since the resin according to the present invention has acrylic or methacrylic double bonds at both end portions that can be cleaved by electron beam irradiation to form a crosslinked structure, the polyester polyurethane resin molecules can be cleaved by electron beam irradiation. Since a crosslinked structure is formed between or within molecules to form a network structure, the resulting magnetic layer has wear resistance and good durability. Furthermore, in the electron beam curable resin according to the present invention, the double bonds at both ends of the molecule form a crosslinked structure by electron beam irradiation, so the coating film has excellent mechanical strength and solvent resistance. A magnetic recording medium with good quality can be obtained. When the electron beam curable resin according to the present invention is used as a binder for a magnetic recording medium, any conventional elements constituting the magnetic recording medium can be used. Therefore, usable magnetic powders include γ-Fe ₂ O ₃ , Fe ₃ O ₄ , γ
- Iron oxide, Co, in an oxidation state intermediate between Fe ₂ O ₃ and Fe ₃ O ₄
Containing γ-Fe ₂ O ₃ , Co-containing Fe ₃ O ₄ , Co-containing γ-
Iron oxide in an oxidation state intermediate between Fe ₂ O ₃ and Fe ₃ O ₄ , iron oxide containing one or more metal elements (especially transition metal elements), iron oxide containing Co oxide or hydroxide CrO 2 , oxide-based magnetic powders such as those with a coating layer mainly composed of CrO ₂ , Cr ₂ O ₃ layers formed by reducing the surface of CrO ₂ , or Fe;
Metals such as Co, Ni or Fe-Co alloy, Fe-Ni
Alloy, Fe-Co-Ni alloy, Co-Ni-P alloy, Co
-Ni-Fe-B alloy, Fe-Ni-Zn alloy, Fe-Mn
Examples include ferromagnetic fine powders such as alloys such as -Zn alloy and Fe-Co-Ni-P alloy. In addition, the magnetic paint made of the electron beam curable resin and magnetic powder according to the present invention includes aluminum oxide as an abrasive,
Antistatic agents such as chromium oxide and silicon oxide include carbon black, and lubricants such as molybdenum disulfide, graphite, and silicone oil.
Olive oil etc. can be added. Furthermore,
In the present invention, binders conventionally used as binders for magnetic recording media may also be used in combination.
Examples include vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-vinyl alcohol copolymer, vinyl chloride-vinyl acetate-maleic acid copolymer, vinyl chloride-vinylidene chloride copolymer, vinyl chloride-vinylidene chloride copolymer, Acrylonitrile copolymer, acrylic ester-acrylonitrile copolymer,
Acrylic acid ester-vinylidene chloride copolymer,
Methacrylic acid ester-vinylidene chloride copolymer, methacrylic acid ester-styrene copolymer,
Thermoplastic polyurethane resin, phenoxy resin, polyvinyl fluoride, vinylidene chloride-acrylonitrile copolymer, butadiene-acrylonitrile copolymer, acrylonitrile-butadiene-acrylic acid copolymer, acrylonitrile-butadiene-methacrylic acid copolymer, polyvinyl butyral , cellulose derivatives, styrene-butadiene copolymers, polyester resins, phenolic resins, epoxy resins, thermosetting polyurethane resins, urea resins,
Examples include melamine resins, alkyd resins, urea-formaldehyde resins, and mixtures thereof. Solvents that can be used to prepare magnetic paints include ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; alcohols such as methanol; methyl acetate,
Esters such as ethyl acetate, butyl acetate, and ethyl butyrate; Glycol ethers such as ethylene glycol dimethyl ether, ethylene glycol monoethyl ether, and dioxane; Aromatic hydrocarbons such as benzene, toluene, and xylene; Hexane,
Examples include aliphatic hydrocarbons such as heptane or mixtures thereof. Furthermore, usable materials for the non-magnetic support include, for example, polyesters such as polyethylene terephthalate, polyolefins such as polypropylene, cellulose derivatives such as cellulose triacetate and cellulose diacetate, polycarbonate, polyvinyl chloride, polyimide, aluminum and copper. Examples include non-magnetic materials such as metal and paper. It is preferable to apply a magnetic paint having the above-mentioned structure onto a non-magnetic support by a conventional method and dry it, then calender the coating film and then irradiate it with an electron beam. You can also. As the electron beam to be irradiated, in addition to electron beams, ionizing radiation such as neutron beams and gamma rays can be used, and electron beams are preferable from an industrial perspective. The irradiation amount is preferably about 1 to 10 Mrad, more preferably about 2 to 7 Mrad. When using an electron beam accelerator for irradiation, the irradiation energy (acceleration voltage) is preferably about 100 KeV or more. In addition, the electron beam curable resin according to the present invention can be applied to magnetic recording media as described above, and can also be used as a binder for forming coating films that require the above-mentioned physical properties in any field. can also be used. The present invention will be explained below using examples. In addition,
All units in Examples and Comparative Examples are parts by weight. Example: In a reaction vessel equipped with a thermometer, stirrer and partial reflux condenser, dimethyl terephthalate was added.
119.2 parts, dimethyl isophthalate 89.4 parts, 5-
136.5 parts of sodium dimethyl sulfoisophthalate,
148.2 parts of ethylene glycol, 203.4 parts of neopentyl glycol and zinc acetate as catalyst
Prepare 0.025 part and 0.003 part of sodium acetate,
The transesterification reaction was carried out at 180°C to 220°C for 3 hours. Then, 376.2 parts of sebacic acid was added to give 200
After reacting for 2 hours at ℃~240℃, the reaction system was
The pressure was reduced to 10 mmHg over 30 minutes. This reaction system was further subjected to a polycondensation reaction at a temperature of 250° C. for 2 hours under a pressure of 3 to 10 mmHg. The polyester resin thus obtained had a reduced viscosity ηsp/c=0.156 (methyl ethyl ketone:toluene=1:1, 30° C.) and a hydroxyl number of 42. As a result of analyzing this polyester resin by nuclear magnetic resonance NMR analysis, etc., its composition was as follows. Terephthalic acid 20 mol%, Isophthalic acid 15 mol%, Sodium 5-sulfoisophthalate 5 mol%, Sebacic acid 60 mol%, Ethylene glycol 50
mol% and neopentyl glycol 50 mol%. Next, in a reaction vessel equipped with a thermometer, a stirrer, and a reflux condenser, 50 parts of the polyester resin obtained above, 73 parts of methyl ethyl ketone, and toluene were added.
73 parts, 7.0 parts of diphenylmethane diisocyanate and 0.005 parts of dibutyltin dilaurate,
The reaction was carried out at 70°C to 90°C for 3 hours. The thus obtained polyester polyurethane resin having -NCO groups at both ends contains 3.90 mmol/g of -NCO groups, and its reduced viscosity ηsp/
c=0.193. When 9.54 parts of β-hydroxyethyl methacrylate was added to the polyester polyurethane resin having -NCO groups at both ends obtained above and reacted for 3 hours, the reduced viscosity η sp/c = 0.210 (methyl ethyl ketone: toluene = 1: A polyester-based polyurethane resin with a temperature of 1.30°C was obtained. Comparative Example 1: Synthesis of a polyester polyurethane resin containing double bonds but no sulfonic acid metal bases Dimethyl terephthalate 119.2
parts, dimethyl isophthalate 119.2 parts, ethylene glycol 148.2 parts, neopentyl glycol 203.4 parts
and 0.025 part of zinc acetate and 0.003 part of sodium acetate as catalysts, and transesterification reaction was carried out at 180°C to 220°C for 3 hours. Next, 376.2 parts of sebacic acid was added and the mixture was heated at 200°C to 240°C.
After reacting for some time, the reaction system was heated to 10 mm for 30 minutes.
The pressure was reduced to Hg. This reaction system was further heated for 3 to 10
The polycondensation reaction was carried out at a temperature of 250° C. for 2 hours under a pressure of mmHg. The OH group concentration of the polyester resin thus obtained was 41 mmol/g.
Furthermore, the ratio of carboxylic acid components of this resin is 20 mol% dimethyl terephthalate, 20 mol% dimethyl isophthalate, and 60 mol% sebacic acid,
In addition, the ratio of its glycol components, ethylene glycol and neopentyl glycol, is
It was 50 mol%. Furthermore, this polyester resin was reacted with diphenylmethane diisocyanate in the same manner as in Examples, and then with β-hydroxyethyl methacrylate to obtain an oligopolyester urethane resin into which double bonds were introduced. ηsp/c = 0.173 (methyl ethyl ketone: toluene = 1:1, 30°C) Comparative example 2: Polyester resin containing sulfonic acid metal base without double bonds Introducing double bonds into the polyester resin obtained in the example A substance that did not undergo any reaction was used. ηsp/c=
0.156 (methyl ethyl ketone: toluene = 1:1,
30℃). The composition of this resin is 20 mol% dimethyl terephthalate, 15 mol% dimethyl isophthalate, 5 mol% sodium dimethyl 5-sulfoisophthalate, and 60 mol% sebacic acid, and its glycol component ethylene glycol. The ratio of each to the neopentyl glycol component was 50 mol%. Comparative Example 3: Polyester resin containing no double bond and sulfonic acid metal base The polyester obtained in Comparative Example 1 was used without undergoing a reaction to introduce double bonds. ηsp/c=
0.136 (methyl ethyl ketone: toluene = 1:1,
30℃). The composition of this resin is 20 mol% dimethyl terephthalate, 20 mol% dimethyl isophthalate, and 60 mol% sebacic acid, and the ratio of its glycol components ethylene glycol and neopentyl glycol is 50 mol each. %
It was hot. Various properties of the resins obtained in the Examples and Comparative Examples described above were measured. 1 Dispersibility Test To evaluate the dispersibility of the resins obtained in Examples and Comparative Examples, a sedimentation test was conducted using γ-Fe ₂ O ₃ as a pigment. γ-Fe ₂ O ₃ 1.0 in a 50 ml graduated cylinder with a stopper
g and 0.25 g of resin and mixed solvent (methyl isobutyl ketone/toluene/cyclohexanone =
2/2/1 (weight ratio)) 50.0 ml was added. After shaking this solution 100 times, let it stand for 24 hours, and then
Shake 100 times. This was allowed to stand and the sedimentation behavior was observed. The sedimentation volume was the final sedimentation volume at which equilibrium was reached, expressed as volume %. At the same time, the sedimentation rate and sedimentation state under these conditions were observed. The results are shown in Table 1.

[Table] 2 Tensile property test The resins of Example and Comparative Example 1 were tested at 90°C.
After drying at 25 mmHg for 3 days to form a film of approximately 100 μm, the film was irradiated with an electron beam of 5 Mrad at an accelerating voltage of 200 KeV to form a cured film. A tanzak shape with a width of 0.625 cm and a length of 10 cm was cut from this cured film and measured using a universal tension tester. Note that the resin of Comparative Example 2 was similarly measured without electron beam irradiation. The results are shown in Table 2.

[Table] 3 Solvent Resistance Test The membrane dried under vacuum at 60°C was cut into 1 cm square pieces and immersed in methyl ethyl ketone, toluene and cyclohexanone to observe whether or not they dissolved. The resins used in Examples and Comparative Example 1 were cured by electron beam irradiation at 200 KeV, and the resins used in Comparative Examples 2 and 3 were not irradiated with electron beams. The results are shown in Table 3.

[Table] From Table 1, regarding the dispersibility, the resins of Examples and Comparative Example 2 containing sulfonic acid metal salts:
Although no difference was observed regardless of the presence or absence of double bonds, it is clear that the dispersibility was better than that of the resins of Comparative Examples 1 and 3, which did not contain a sulfonic acid metal base. Table 2 shows that when irradiated with an electron beam, there is no difference in tensile properties depending on the presence or absence of a sulfonic acid metal base, but the tensile properties are higher than that of the polyester resin of Comparative Example 2, which was not cured by an electron beam. It is recognized that the characteristics are significantly improved. Regarding solvent resistance, Table 3 shows that the resins of Example and Comparative Example 1, which were cross-linked by electron beam irradiation, are insoluble in general-purpose solvents, whereas the resins of Comparative Example 2 and Comparative Example 1, which were not cross-linked, are insoluble in general-purpose solvents. The difference is obvious because resin No. 3 is soluble in general-purpose solvents. From the above results, it was found that the polyester polyurethane resin, which is an electron beam curable resin containing a sulfonic acid metal base according to the present invention, has good dispersibility, tensile properties, and solvent resistance without containing a sulfonic acid group and does not undergo crosslinking reaction by electron beam. It can be seen that it is superior to polyester, which does not cause Magnetic tapes were produced in the following manner using the resins obtained in the Examples and Comparative Examples described above. A mixture of 10 parts of γ-Fe ₂ O ₃ magnetic particles, 5 parts of methyl ethyl ketone, and 7.5 parts of toluene was kneaded for 3 hours using a Pall mill. To this mixture were added 2.5 parts of the resin of the example prepared separately and 5 parts of methyl ethyl ketone.
A mixed solution of 1 part and 7.5 parts of toluene was added and kneaded again for 24 hours using a ball mill. After defoaming the resulting mixture, it was coated onto a polyethylene terephthalate film with a thickness of 16 μm using a doctor blade with a gap of 25 μm, and then placed in a parallel magnetic field of 900 Oe for about 1 second. Then, it was left in a hot air dryer at 90° C. for about 30 minutes to remove the solvent, and the thickness of the magnetizable layer was reduced to 8.0 μm. This Rs (Br/Bm)
was 0.87. Separately, a magnetizable layer was formed on a polyethylene terephthalate film using the resins of Comparative Examples 1, 2, and 3 in the same manner. Among the tapes obtained as described above, the tapes of Example and Comparative Example 1, which have double bonds that are active against electron beams, were exposed to electron beams at an accelerating voltage of 200 KeV.
It was irradiated with 5 Mrad to form a cured film. The various properties of the magnetic tapes thus obtained were investigated as follows. 1. Tensile strength test A 0.625 cm wide and 10 cm long strip was cut from the cured magnetic tapes of Examples and Comparative Example 1 and measured using a universal tensile strength tester. 2 Solvent Resistance Test The magnetic layer was rubbed with gauze containing methyl ethyl ketone, and the number of times the layer was rubbed was expressed as the number of times the layer was rubbed until the layer disappeared. 3. Powder drop test When the tape was actually run, the amount of powder adhering to the pinch roller, capstan, guide head, etc. was scored from 0 to -5 using a subtraction method. Test results for each tape are shown in Table 4.

[Table] From the above results, the examples containing sulfonic acid metal base and cured by electron beam have Rs, Young's modulus Eλ,
It also far exceeds Comparative Example 3 in terms of solvent resistance and powder shedding. Furthermore, in comparison with Comparative Example 1, although no significant changes were observed in Rs, dispersibility, and orientation, there was a considerable difference in powder shedding. On the other hand, in terms of durability, it can be seen that Comparative Example 2 is far inferior to the Examples that were cured by electron beams. Similar trends also apply to Comparative Examples 1 and 3. Taking all the above into account, it can be seen that the effect of dispersion by the sulfonic acid metal base and the improvement in durability by electron beam in the resin according to the present invention are clear.

Claims (1)

[Claims] 1 A polyester polyurethane resin in which the polyester molecular portion is chain-extended via urethane bonds, and the molecular weight of the resin is approximately 10,000 to 10,000.
50,000, double bonds are present at both ends of the molecule of the resin, and the carboxylic acid component having a sulfonic acid metal group in the molecule of the resin is about 0.2 to 30 mol% based on the total carboxylic acid component. An electron beam curable resin characterized by containing: