Claims
- 1. A method for making a resin-bonded magnet which comprises providing composite granules obtained from a mixture of magnetically isotropic, fine pieces of a melt-quenched Fe-B-R intermetallic compound or alloy, in which R is at least one element selected from Nd and Pr, and a resin composition comprising at least one film-forming polymer having a functional group reactive with an isocyanate group and a blocked isocyanate, wherein said composite granules are formed by dissolving or dispersing a resin composition in a solvent and the resultant solution or dispersion is applied to said magnetically isotropic, fine pieces of the melt-quenched Fe-B-R intermetallic compound or alloy, said composite granules comprising from 1 to 3 weight percent of the resin composition, compressing the composite granules to obtain a green compact of a desired form, and heating the green compact at temperatures sufficient to soften or melt the resin composition and to allow reaction between the at least one film-forming polymer and an isocyanate formed by dissociation of blocking groups of the blocked isocyanate, thereby obtaining a resin-bonded magnet.
- 2. A method according to claim 1, wherein the pieces have a thickness not smaller than 15 micrometers.
- 3. A method according to claim 1, wherein said resin composition further comprises at least one polymer which is not reactive with isocyanate groups.
- 4. A method according to claim 1, wherein said resin composition further comprises a thermosetting resin or oligomer having a functional group reactive with the isocyanate.
- 5. A method according to claim 1, wherein said granules have a size not larger than 400 micrometers.
- 6. A method according to claim 1, wherein at least 50 wt % of said granules have a size not smaller than 75 micrometers.
- 7. A method according to claim 1, wherein said granules have an apparent density of from 2.0 to 3.0 g/cm.sup.3.
- 8. A method according to claim 1, wherein a predetermined amount of said granules are charged into a cavity for molding and compressed at a predetermined compression ratio of 1.8 to 3.0:1, thereby obtaining the green compact having a density of from 5.3 to 6.0 g/cm.sup.3.
- 9. A method according to claim 1, wherein said green compact is thermally treated in a mold for inhibiting the thermal expansion of said green compact.
- 10. A method according to claim 9, wherein the thermal treatment is effected at a temperature of from 140.degree. to 200.degree. C.
- 11. A method according to claim 1, wherein the composite granules are obtained by continuously forming a melt of the alloy into a quenched ribbon, breaking the ribbon into flaky pieces, and mixing the pieces with the resin composition.
- 12. A method according to claim 11, wherein the composite granules obtained by the mixing are classified to have a controlled size.
Priority Claims (1)
Number |
Date |
Country |
Kind |
62-26671 |
Feb 1987 |
JPX |
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Parent Case Info
This application is a continuation application of application Ser. No. 07/152,415, filed Feb. 4, 1988 now abandoned.
US Referenced Citations (13)
Foreign Referenced Citations (2)
Number |
Date |
Country |
0155082 |
Sep 1985 |
EPX |
57-170501 |
Oct 1982 |
JPX |
Non-Patent Literature Citations (1)
Entry |
Kunststoff-Taschenbuch, 22nd edition, Carl-Hanser Verlag, Munich 1983, pp. 379-388. |
Continuations (1)
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Number |
Date |
Country |
Parent |
152415 |
Feb 1988 |
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