Elastomer composition and magnetic ferrite coated with the same

Abstract

Provided are an elastomer composition including epoxy resin, acrylate resin, an organic filler, an inorganic filler, a cross linking agent, a hardener, an initiator and a solvent, and a magnetic ferrite for a wireless power transmitting and receiving device, the magnetic ferrite being coated with the elastomater composition having an elastic restoring force not to be damaged by a physical impact applied from the outside. According to embodiments of the present invention, the magnetic ferrite having improved impact resistance can be provided by being coating with the elastomer composition having the elastic restoring force, and thus an existing problem such as a reduction in magnetic property caused by damage to the ferrite resulting from an external impact can be solved.

Claims

1. An elastomer composition, comprising: 3 to 5 parts by weight of an epoxy resin; 12 to 15 parts by weight of an acrylate resin; 20.5 to 21.5 parts by weight of an organic filler; 3 to 25 parts by weight of an inorganic filler; 10 to 30 parts by weight of a cross linking agent; 1 to 5 parts by weight of a hardener; 1 to 5 parts by weight of an initiator; and 20 to 24 parts by weight of a solvent, wherein the solvent includes 4 to 10 parts by weight of a reactive solvent based on 100 parts by weight of a total amount of the elastomer composition, wherein a weight ratio of a solid state to a liquid state of the epoxy resin is 1:1 to 3:1, and wherein the acrylate resin is polymerized into a resin by small molecules of one selected from a group consisting of tripropylene glycol diacrylate, dipropylene glycol diacrylate, cyclododecyl acrylate and 1,6-hexanediol diacrylate, or a mixture thereof.

2. The elastomer composition of claim 1, wherein the epoxy resin is one selected from a group consisting of bisphenol A, bisphenol F, bisphenol S, cresol novolac, and phenoxy-based epoxy, or a mixture thereof.

3. The elastomer composition of claim 1, wherein the acrylate resin is polymerized into a resin by small molecules from a mixture of tripropylene glycol diacrylate and dipropylene glycol diacrylate.

4. The elastomer composition of claim 1, wherein the organic filler is one selected from a group consisting of liquid polybutadiene, acrylonitrile butadiene, glycidyl acrylate and styrene butadiene, or a mixture thereof.

5. The elastomer composition of claim 1, wherein the cross linking agent is one selected from a group consisting of epoxy-terminated butadieneacrylonitrile rubber and carboxy-terminated butadieneacrylonitrile rubber, or a mixture thereof.

6. The elastomer composition of claim 1, wherein the hardener is one selected from a group consisting of peroxide, hydroperoxide, peroxidicarbonate and peroxiiester-based hardener, or a mixture thereof.

7. The elastomer composition of claim 1, further comprising one hardening accelerator or two or more hardening accelerators selected from a group consisting of an amine-based hardening accelerator, a peroxide-based hardening accelerator, and a phenol-based hardening accelerator.

8. A magnetic ferrite coated with an elastomer composition according to claim 1.

9. The magnetic ferrite of claim 8, wherein the elastomer composition is coated on at least one or more surface selected from an upper surface, a lower surface and both sides of the magnetic ferrite.

10. The magnetic ferrite of claim 8, wherein the magnetic ferrite is coated with the elastomer composition in an elastic film form.

11. The magnetic ferrite of claim 10, wherein the elastic film is porous.

12. A wireless power transmitting and receiving device comprising a magnetic ferrite according to claim 8.

Description

DESCRIPTION OF DRAWINGS

(1) The accompanying drawings are included to provide a further understanding of the present invention, and are incorporated in and constitute a part of this specification. The drawings illustrate exemplary embodiments of the present invention and, together with the description, serve to explain principles of the present invention. In the drawings:

(2) FIG. 1 is a cross-sectional view showing a magnetic ferrite, an upper surface of which is coated with an elastic elastomer film according to an embodiment of the present invention;

(3) FIG. 2 is a cross-sectional view showing a magnetic ferrite, an upper surface and a lower surface of which are coated with the elastic elastomeric film according to the embodiment of the present invention;

(4) FIG. 3 is a cross-sectional view showing a magnetic ferrite coated in a side seal form with the elastic elastomer film according to the embodiment of the present invention;

(5) FIG. 4 is a cross-sectional view showing a magnetic ferrite, an upper surface of which is coated with a porous elastic elastomer film according to other embodiment of the present invention;

(6) FIG. 5 a cross-sectional view showing a magnetic ferrite, an upper surface and a lower surface of which are coated with the porous elastic elastomer film according to the other embodiment of the present invention; and

(7) FIG. 6 is a cross-sectional view showing a magnetic ferrite coated in a side seal form with the porous elastic elastomer film according to the other embodiment of the present invention.

BEST MODE

(8) Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings. The present invention may, however, be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the present invention to those skilled in the art.

(9) An elastomer composition (for coating a magnetic ferrite) according to an embodiment of the present invention includes epoxy resin; acrylate resin; an organic filler; an inorganic filler; a cross linking agent; a hardener; an initiator; and a solvent, more specifically, (based on 100 parts by weight of the total amount of the composition), 3 to 5 parts by weight of an epoxy resin, 12 to 15 parts by weight of an acrylate resin, 20.5 to 21.5 parts by weight of an organic filler, 3 to 25 parts by weight of an inorganic filler, 10 to 30 parts by weight of a cross linking agent, 1 to 5 parts by weight of a hardener, 1 to 5 parts by weight of an initiator, and 20 to 24 parts by weight of a solvent.

(10) The epoxy resin may be one selected from the group consisting of bisphenol A, bisphenol F, bisphenol S, cresol novolac, and phenoxy-based epoxy, or a mixture thereof. Also, the epoxy resin may use a mixture of general solid epoxy resin and liquid epoxy resin. As the solid epoxy resin having crystallizability is applied, ductility, stiffness, filling, an adhesive property, and a process capability, which are appropriate to a necessary temperature condition, could be implemented. As a result, a difference in coefficient of expansion between a magnetic ferrite coated with the elastomer composition including the epoxy resin and a different kind of substrate may be compensated, and a gap-filling property may be improved because a thermal history becomes excellent, thereby improving reliability of the magnetic ferrite for wireless charging, coated with the elastomer composition. In light of adjusting a tack property for a handling property, a ratio between the solid and liquid states of the epoxy resin may be 1:1 to 3:1. Also, it may be preferable that an amount of the epoxy resin ranges from 3 to 5 parts by weight based on 100 parts by weight of the total amount of the composition in light of an adhesive property and the like.

(11) The acrylate resin may be one selected from the group consisting of TPGDA (tripropylene glycol diacrylate), DPGDA (dipropylene glycol diacrylate), TMPTA (trimethylolpropane triacrylate), CDA (cyclododecyl acrylate) and HDD (1,6-hexandiol diacrylate), or a mixture thereof. It would be preferable that the acrylate resin is used in an amount of 12 to 15 parts by weight based on 100 parts by weight of the total amount of the composition in light of an adhesive property.

(12) The organic filler (having 50,000 or more molecular weight) may be one selected from the group consisting of liquid polybutadien, acrylonitrile butadiene, grycidyl acrylate and styrene butadiene, or a mixture thereof. It would be preferable that the organic filler is used in an amount of 20.5 to 21.5 parts by weight based on 100 parts by weight of the total amount of the composition in light of ductility, a modulus and tensile strength.

(13) The inorganic filler may be one selected from the group consisting of silica and TiO.sub.2, or a mixture thereof. The inorganic filler may be used in an amount of 1 to 25 parts by weight based on 100 parts by weight of the total amount of the composition. When the amount is less than 1 parts by weight, there is concern about reducing reliability and a gap-filling property as the magnetic material for wireless charging because heat conduction quality is lacking. When the amount exceeds 25 parts by weight, a process capability and reliability may be reduced due to an excessive thermal history.

(14) The cross linking agent may be one selected from the group consisting of epoxy-terminated butadieneacrylonitrile (ETBN) rubber and carboxy-terminated butadieneacrylonitrile (CTBN) rubber, or a mixture thereof. The cross linking agent may be used in an amount of from 10 to 30 parts by weight based on 100 parts by weight of the total amount of the composition. The cross linking agent functions to improve the commercialization of a rubber ingredient and epoxy which are organic fillers. When the amount is less than 10 parts by weight, the cross linking agent may have difficulty in performing such a function. When the amount exceeds 30 parts by weight, there may be concern about reducing reliability for a moisture resistance test (MRT).

(15) The hardener may be one selected from the group consisting of peroxide, hydroperoxide, peroxidicarbonate and a peroxiester-based hardener, or a mixture thereof. The hardener may be used in an amount of 1 to 5 parts by weight based on 100 parts by weight of the total amount of the composition. When the amount is less than 1 parts by weight, a desired hardening rate may not be obtained. When the amount exceeds 5 parts by weight, a deterioration in storage property and a reduction in molecular weight may be caused. Also, except for the hardener, one hardening accelerator or two or more hardening accelerators selected from the group consisting of an amine-based hardening accelerator, a peroxide-based hardening accelerator, and a phenol-based hardening accelerator may be additionally included.

(16) The initiator may be one selected from the group consisting of a photoinitiator and a thermal initiator, or a mixture thereof. The photoinitiator is one selected from the group consisting of a long wavelength-band photoinitiator (for example, Irgacure 369, irgacure 651, irgacure 379 or the like) and a short wavelength-band photoinitiator (for example, Irgacure 254, irgacure 184 or the like), or a mixture thereof. Furthermore, the thermal initiator may be one selected from the group consisting of a peroxide-based initiator, a hydroperoxide-based initiator, a peroxidicarbonates-based initiator, and a peroxiester-based initiator, or a mixture thereof. Specifically, a thermal initiator having a half life of 30 to 60 minutes based on 90 to 130 C. may be used. The initiator may be used in an amount of 1 to 5 parts by weight based on 100 parts by weight of the total amount of the composition.

(17) The solvent functions to adjust a B-staging rate and viscosity and the like, and is composed of a reactive solvent and a dilution solvent. It would be preferable that the solvent is used in an amount of 20 to 24 parts by weight based on 100 parts by weight of the total amount of the composition in light of a process capability, an adhesive property, and the like. The reactive solvent may be one or more solvent selected from the group consisting of methyl carbitol, ethoxytriglycol, methyl propasol, propyl dipropasol and butyl carbitol. The reactive solvent may be used in an amount of 4 to 10 parts by weight based on 100 parts by weight of the total amount of the composition.

(18) On the other hand, another embodiment of the present invention provides a magnetic ferrite coated with the elastomer composition, and a wireless power transmitting and receiving device including the magnetic ferrite.

(19) The elastomer composition may be coated on at least one or more surfaces selected from an upper surface, a lower surface and both sides of the magnetic ferrite. Specifically, FIG. 1 illustrates a case in which an elastomer composition 20a is coated on the upper surface of a magnetic ferrite 10, FIG. 2 illustrates a case in which the elastomer composition 20a is coated on the upper surface and a lower surface of the magnetic ferrite 10, and FIG. 3 illustrates a case in which the upper and lower surfaces and both sides of the magnetic ferrite 10 are coated in a side seal form.

(20) Also, the elastomer composition may be coated on the magnetic ferrite in an elastic film form. The elastic film may be porous. Specifically, FIG. 4 to FIG. 6 illustrate cases in which the elastomer composition is each coated on the upper surface of the magnetic ferrite 10, the upper surface and the lower surface of the magnetic ferrite 10, and the upper surface and the lower surface and both sides of the magnetic ferrite 10.

(21) Hereinafter, the present embodiment of the present invention will be more specifically described based on Examples.

EXAMPLE AND COMPARATIVE EXAMPLE

(22) Elastomer compositions according to Examples 1, 2 and Comparative Example 1 to 4 were prepared based on each ingredient and amount described Table 1 below.

(23) Specifically, each elastomer composition was prepared by primarily mixing liquid polybutadiene, a mixture of ETBN and CTBN, a mixture of TPGDA and DPGDA, a mixture of BPA and BPS in reactor using methylethylketone (MEK) at 300 rpm for about 8 to 10 hours in a water bath of 50 C., and then, adding toluene, peroxide, methyl carbitol, a UV initiator (Irgacure 369, irgacure 651, irgacure 379, Irgacure 254, irgacure 184 or the like), a thermal initiator (a peroxide-based initiator, a hydroperoxide-based initiator, a peroxidicarbonates-based initiator, a peroxyester-based initiator or the like), an organic filler (acrylonitrile butadiene, glycidyl acrylate, styrene butadiene or the like), and an inorganic filler (silica, TiO.sub.2 or the like), and mixing at 5002000 rpm for about four hours at room temperature.

(24) Evaluation Method

(25) After an upper surface and a lower surface of the magnetic ferrite have been coated with each elastomer composition prepared according to the examples and comparative examples using a lamination method under the conditions of a feeding speed of 50 mm/sec, a roll temperature of 50 C. and a lamination pressure of 500 gf/cm.sup.2, in a film state, a modulus (MPa), peeling strength (gf/cm), and an elongation rate (%) were measured, and an acceleration test was measured at 85 C./85% for 24 hours. Based on this, evaluation results of impact resistance, the occurrence or non-occurrence of a delamination phenomenon, and a process capability are described in Table 1 below.

(26) TABLE-US-00001 TABLE 1 Comparative Comparative Comparative Comparative Division Example 1 Example 2 Example 1 Example 2 Example 3 Example 4 Liquid Polybutadiene 11 11 10 10 12 12 ETBN + CTBN 10 12 10 12 8 10 TPGDA + DPGDA 14 15 12 15 10 11 BPA + BPS 3 3 3 5 3 3 Peroxide 2 3 4 4 2 3 Methyl Carbitol 6 6 7 8 4 5 Solvent 18 14 18 10 25 20 (MEK/Toluene) UV initiator 2 2 2 2 2 2 Thermal initiator 2 2 2 2 2 2 Organic filler 10 10 10 10 10 10 Inorganic filler 22 22 22 22 22 22 Total 100 100 100 100 100 100 Evaluation Modulus 5.2 4.3 4.3 3.3 2.3 1.3 items [MPa] Peel strength 329 188 253 169 229 235 [gf/cm] Elongation [%] 679 854 253 169 756 774 85 C./85% Pass Pass Pass Pass Fail Fail 24 hr test Impact Pass Pass Fail Fail Pass Pass resistance Delamination No No No No Occurrence Occurrence phenomenon occurrence occurrence occurrence occurrence Process Pass Pass Pass Pass Fail Fail capability (unit: parts by weight)

(27) As shown in Table 1 above, in a case where the magnetic ferrite is coated with the elastomer composition prepared according to the examples of the present invention, various physical properties such as the impact resistance, the process capability and the like are excellent, no delamination phenomenon between the magnetic ferrite and the elastomer film also occurs. On the contrary, in a case where the magnetic ferrite is coated with the elastomer composition according to the comparative examples, these effects are not shown.

(28) As previously described, in the detailed description of the invention, having described the detailed exemplary embodiments of the invention, it should be apparent that modifications and variations can be made by persons skilled without deviating from the spirit or scope of the invention. Therefore, it is to be understood that the foregoing is illustrative of the present invention and is not to be construed as limited to the specific embodiments disclosed, and that modifications to the disclosed embodiments, as well as other embodiments, are intended to be included within the scope of the appended claims and their equivalents.