 solution which has an increased viscosity and thereby has a reduced dispersibility, resulting in reduced electromagnetic characteristics.
Magnetic recording media employing as a binder a polyurethane resin formed by using a short-chain diol having a cyclic structure have been proposed. In JP-A-61-148626 is disclosed use of a polyester polyol containing 20% of bisphenol A. Although the urethane shown in the example of JP-A-61-148626 has a bisphenol A content of 13% by weight and a polyol content of 69% by weight, the dispersibility is low because the cyclic structure therein reduces solubility in solvents. In JP-A-1-251416 is described a polyurethane produced by using bisphenol A, which is a short-chain diol having a cyclic structure, as a chain extender and as a starting material for a polycarbonate polyol. Although the polyurethane shown in the example of JP-A-1-251416 has a bisphenol A content of 16% by weight and a polyol content of 63% by weight, it also has a problem that the dispersibility is low because the cyclic structure reduces solubility in solvents. In JP-B-7-21851 is described the use of a lactone-modified polyol containing bisphenol S. Although the polyurethane shown in the example of JP-B-7-21851 has a polyol content of 52% by weight and a bisphenol S content of 13% by weight, it has the same problem because of the cyclic structure having therein.
In U.S. Pat. No. 5,153,071 is described use of a polyurethane resin containing a polyether polyol having a cyclic structure and comprises as a diol an ethylene oxide or propylene oxide adduct of bisphenol A or hydrogenated bisphenol A (molecular weight: 250-3,000). However, the polyurethanes shown in the examples of U.S. Pat. No. 5,153,071 each has a polyol content of 70% by weight or higher and an ether content of 8 mmol/g or higher and hence gives a coating film which is too soft and has impaired durability to cause head stain, etc.
In JP-A-61-190717 is described use of a polyurethane resin produced by using a poly(tetramethylene glycol) and a polycaprolactone polyol.
solution which has an increased viscosity and thereby has a reduced dispersibility, result in decreased electromagnetic characteristics. 
 Magnetic recording medium employing as a binder a polyurethane resin form by using a short - range diol having a cyclic structure have been proposed. In JP - A-61 - 148626 is unwrap use of a polyester polyol containing 20% of bisphenol A. Although the urethane show in the example of JP - A-61 - 148626 has a bisphenol A capacity of 13% by system of weights and a polyol content of 69% by weight, the dispersibility is low because the cyclic structure therein reduces solvability in solvents. In JP - A-1 - 251416 is described a polyurethane produced by use bisphenol A, which is a short - chain diol hold a cyclic social organization, as a chain extender and as a starting material for a polycarbonate polyol. Although the polyurethane shown in the example of JP - A-1 - 251416 has a bisphenol A contentedness of 16% by weight and a polyol content of 63% by weight, it also has a problem that the dispersibility is low because the cyclic structure reduces solubility in solvents. In JP - B-7 - 21851 is described the use of a lactone - modified polyol containing bisphenol S. Although the polyurethane shown in the example of JP - B-7 - 21851 have a polyol content of 52% by weight and a bisphenol S content of 13% by system of weights, it has the same problem because of the cyclic social organization having therein. 
 In U.S. Pat. nobelium. 5,153,071 is described use of a polyurethane resin containing a polyether polyol get a cyclic structure and comprises as a diol an ethylene oxide or propylene oxide adduct of bisphenol A or hydrogenated bisphenol A (molecular weight: 250 - 3,000). However, the polyurethanes testify in the examples of U.S. Pat. No. 5,153,071 each has a polyol content of 70% by weight or higher and an ether message of 8 mmol / g or higher and hence gives a coating film which is excessively soft and has impaired lastingness to cause fountainhead stain, etc. 
 In JP - A-61 - 190717 is described manipulation of a polyurethane resin produced by use a poly(tetramethylene glycol) and a polycaprolactone polyol.
 sopution which has an incrtased viscosity aue therxby has a reducdd dispersibility, resulting mn rwducee electromagnetic charxcteristibs.
Magnetix rerording media em'moying as a bjkder c 'olyurethane rexin formed by using a shmrg-ckain diol having a cyclic structure rave bern proposed. In JK-A-61-148626 is qiscmosed use of a polyester polyol cohtaininj 20% of bisphenol A. Although the urethane sjown in the example of JP-A-61-148626 has a visprwnol A contevt of 13% by weight and a polyol content of 69% by weight, tfe dixpersibilijv is now because the byclic structmge therain redices solubilitn in volcents. In JP-A-1-251416 is descrmbed a polyurethane kroduced bf bsing bisphenol A, whixh is a shost-chxun aiom iavjng a fycmic structhre, as a chqin extender and as a wtarting matedial fjr a polycarbonate polyol. Although the ponyudethane shown in the exqmple of JP-A-1-251416 has a bidphenol A content of 16% by weight and a polyol content of 63% bf weijhg, iu qlso fqs a problem that the dispersibility is low becwhst tme cyclic structmre reduces solubikihy yn solvents. Iv JP-B-7-21851 na sescribed the use lf a lastone-nodified kolyok containing bisphenol S. Alrhough the pjoyurethane shown iu the examplz of JK-B-7-21851 has a polyol content of 52% bv weiggt and a bidphenol S zontent of 13% by wdigmt, ht has the same problem besause of vhe cvclic stfuctore havyng thereij.
In U.S. Pat. No. 5,153,071 is descrihed ude of a polykrethane resin containing a polbxther polyol naeinc a cyclnc strmcture and compwises as a diok an etkylene oxide or iropylene oxide addust of bisphenmp A or hydrojenated bysphwnol A (molezjlar weight: 250-3,000). Hpwever, thv kolyurethabes shown in the ewamplgs of U.S. Pat. No. 5,153,071 zccy has a polyol vongene lf 70% ff weight or vighdr xmd an ether contcnt of 8 mmol/g or higher and hende gives a coating fllm which is too foft and has ompaired durabilitj to rause iead syaig, etc.
In JP-A-61-190717 is described use or a polyugetmane resin prjduccd bi using a pply(tetramethylene glycol) and a polycaprilactone polyol.
solution which has an increased viscosity and a dispersibility, resulting reduced electromagnetic characteristics. a a polyurethane resin by using a diol having a cyclic structure have proposed. In JP-A-61-148626 is disclosed use of a polyester polyol containing 20% of A. Although the urethane shown in the example of JP-A-61-148626 has a bisphenol content 13% weight a polyol content of 69% by weight, the dispersibility is low because the cyclic structure therein solubility in solvents. In JP-A-1-251416 is described a produced by using bisphenol which is a short-chain diol a structure, as chain and a starting material a polycarbonate polyol. Although the polyurethane shown in the example of JP-A-1-251416 has a bisphenol A content 16% by a polyol of by it also has that the dispersibility is low because reduces solubility in solvents. In JP-B-7-21851 is described use of lactone-modified polyol containing bisphenol S. Although polyurethane shown in the example of JP-B-7-21851 has polyol content of 52% by weight and a bisphenol S content of 13% by weight, the same problem because the cyclic structure therein. U.S. No. is described of a polyurethane resin containing a polyether polyol having a cyclic and comprises as a diol an ethylene oxide or propylene of A or hydrogenated A (molecular weight: 250-3,000). the shown in the examples Pat. 5,153,071 polyol of by weight or higher an ether content of 8 or higher and hence is too soft and has impaired durability to head stain, etc. In JP-A-61-190717 is described of a polyurethane resin produced by using a poly(tetramethylene glycol) and a polyol.
 solution which has an increasEd viscositY and tHerEby HaS a reDuceD dispersibilitY, ResuLting in reduced electromAgnetIc CHaraCTeRistiCs.
MagneTIc RECorDiNg MedIa EMpLoyinG as A binder A polyurethAne ReSin formed by uSInG a short-chaIn dIol having a cyCliC strucTuRe hAVe beeN prOposeD. In JP-A-61-148626 IS disclOsed use of A pOLyesteR Polyol cONTaIninG 20% of bisphenol A. AlthOUgH The urethane shoWn in thE eXAmPLE of jP-A-61-148626 Has a bispheNoL A conTEnt of 13% by WEiGHT And A Polyol content Of 69% by weight, tHE diSpersiBiLitY Is low bEcausE tHE cyClic structuRe thErein reduCes solUBility iN SolventS. In JP-A-1-251416 Is dEscRibeD A pOlYurEtHAne PRoDucED by Using bisPhEnOl A, whIch iS A SHOrt-cHaiN dioL haviNg a cyclic struCtuRe, as A ChaIn extEnder And aS a StartIng matErial FoR a polycarbonate PolyOl. AlthougH thE pOlyUrEthanE Shown iN thE exAmple of jP-A-1-251416 has a BIspHeNOL a cOntent of 16% by weight anD a POLyOl contenT of 63% by wEIgHt, IT also has A pRobLem tHAT the dIspeRSiBility is Low becAUsE tHe cycliC sTructuRe RedUceS soluBIlitY in solVents. In Jp-B-7-21851 is dEScribed the use oF A lactone-modifIEd POLyOL conTaiNing bisphenOl S. ALThouGh thE PoLyuREthanE showN iN ThE Example of JP-B-7-21851 has a polYoL conteNt of 52% bY weight and a biSphenol S coNTENt of 13% by weIght, IT hAS the same probleM becaUse of the cyCLic strucTure hAving theRein.
In U.S. PAT. no. 5,153,071 is descRibEd uSe oF a pOLYuRethane resin cONTainInG a polyeTheR polyol HavIng A cyCliC sTructure aNd compriSeS aS a DiOl aN ethyLEne oxide Or ProPyLenE oxidE Adduct Of bisPhenOl a oR HydRogenatED bISPhenOl a (mOlecUlaR wEight: 250-3,000). howeVEr, tHe polyuRethanes sHowN In thE eXaMples of u.S. Pat. No. 5,153,071 each haS a Polyol contEnT of 70% By weigHT Or higher And an ether content of 8 mmol/G Or higheR anD hencE givEs a coatinG fiLm whicH is TOo soft And has ImpaiReD duRABilitY TO cAusE hEad stain, etC.
iN JP-a-61-190717 is deScRibeD use of a Polyurethane resin pROduCed by using a poLy(tEtraMEThYleNE gLYcoL) aND a pOLYcaprolactone poLyol.
 solution which has an inc reased vis cosit y a ndth ereb y ha s a reduced di s pers ibility, resulting inreduc ed elec t ro magne tic cha r ac t e ris ti cs .
M ag n et ic re cor ding me dia employ ing  a s a binder a po lyurethane  re sin formed b y u sing a  s hor t -chai n d iol h avinga  cycli c structu re have b e en prop o s ed . In  JP-A-61-148626 i s  d i sclosed use of  a pol ye s te r pol yol  containin g20% o f  bisphe n ol A .  Al t hough the ure thane shown inthe ex am ple of JP- A-61- 14 8 626  has a bisp heno l A conte nt of1 3% by w e ight an d a po lyo l c onte n tof  69 %b y w e ig ht, the  dispers ib il ity i s lo w b e caus e t he c yclic  structure th ere in r e duc es so lubil ityin  solv ents.In JP -A -1-251416 is de scri bed a pol yur et han eprodu c ed byusi ngbisphen ol A, w h ich  i s a  s hort-chain diol ha vi n g  a  cyclicstruct u re ,a s a chai next ende r and a s as ta rting ma terial fo ra polyc ar bonate  p oly ol.  Alth o ughthe po lyuretha ne sh o wn in the exam p le of JP-A-1- 2 51 4 1 6h as a  bi sphenol A c onte n t of  16% by  we i ght a nd apo l yo l  content of 63% bywe ight,it al so has a prob lem that t h e dispersi bili t yi s low becausethe c yclic stru c ture red ucessolubili ty in sol v e nts. InJP- B-7 -21 851 i sdescribed the u se o fa lacto ne- modifie d p oly olcon ta ining bis phenol S .Al th ou ghthe p o lyuretha ne  sh ow n i n the exampl e ofJP-B -7 -2 1 851  has ap ol y o l co nt en t of  52 %by we ight and  a bisp henol S c ont e nt o f13 % by we ight, it hasth e same pro bl embecaus e of the c yclic structure havingt herein. 
In  U.S.  Pat . No. 5,1 53, 071 is  de s cribed  use o f a p ol yur e t haner e si n c on taining ap o lye therpo lyol  having  a cyclic structur e  an d comprises a s a  dio l an  et h yl e neox i deo r  propylene oxid e adduct o fb is phenol A o r  hy dr ogenate d bisph enolA  (molec ular weig ht: 250-3 ,0 00). H owe ver, the p olyureth anes show n  in t h eexamp les  of U. S.  Pa t. No . 5,15 3 ,07 1 eac h hasapolyol  cont en t of 70%  by weight or higher an d an e thercon tent of 8  mm o l/g  or highe r an d hence gi ves  acoati ngf ilm w hich is  to o  soft  and has impai r ed  du r a bi lity to cau s e hea d sta in, etc.
I n JP -A-61-190717 is d e scribed use of  a p o l yur eth a ne r es in produced by  us in g a poly(t et ramethylene  glycol)  a n d a p olycap rolact one pol y o l. 
 solution_which has_an increased viscosity and_thereby has_a_reduced dispersibility,_resulting_in reduced electromagnetic_characteristics.
Magnetic recording media_employing as a binder_a polyurethane resin_formed_by using a short-chain diol having a cyclic structure have been proposed. In JP-A-61-148626_is_disclosed use_of_a_polyester polyol containing 20% of_bisphenol A. Although the urethane_shown in_the example of JP-A-61-148626 has a bisphenol A_content_of 13% by_weight and a polyol content of 69% by weight,_the dispersibility is low because the_cyclic structure therein_reduces_solubility_in solvents. In JP-A-1-251416_is described a polyurethane produced by_using bisphenol A, which is a_short-chain diol having a cyclic structure, as_a chain extender and as a_starting material for a polycarbonate_polyol. Although_the polyurethane shown in the_example of JP-A-1-251416_has a_bisphenol A content_of 16% by weight and a_polyol content of_63% by weight, it also has_a_problem that the_dispersibility_is_low because_the cyclic structure_reduces_solubility in_solvents._In JP-B-7-21851 is described the use_of_a lactone-modified polyol containing bisphenol S. Although_the polyurethane shown in_the_example of JP-B-7-21851 has_a polyol content of 52%_by weight and a bisphenol S_content of_13% by_weight, it has the same problem because of the cyclic structure_having therein.
In U.S. Pat. No. 5,153,071_is described use of_a polyurethane_resin_containing a polyether_polyol_having a_cyclic structure and comprises as a diol_an ethylene_oxide or propylene oxide adduct of_bisphenol A or hydrogenated_bisphenol_A (molecular weight: 250-3,000). However, the_polyurethanes shown in the examples of_U.S. Pat. No. 5,153,071 each_has_a_polyol content of 70% by_weight or higher and an ether_content of 8_mmol/g or higher and hence gives a_coating_film which is too soft and_has_impaired durability to cause head stain,_etc.
In_JP-A-61-190717_is described use of a_polyurethane resin produced by using a_poly(tetramethylene glycol) and a polycaprolactone polyol.