JPH02194800

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DESCRIPTION JPH02194800
[0001]
The present invention relates to an edge for a speaker provided with a foamable coating layer
formed using thermally expandable microspheres, and a method of manufacturing the same.
<Prior Art> As an edge of a speaker, (a) a cloth such as a cotton cloth impregnated with a
molding resin, for example, coated with a non-foam resin of rubber type and molded into a
predetermined shape; It has been conventionally known that a polyurethane or rubber sheet is
heated and compressed to form a predetermined shape. Further, for example, Japanese Patent
Application Laid-Open No. 55-114098 proposes that a fibrous substrate impregnated with a
molding resin is coated with a mechanically foamed elastomer and heat-formed into a
predetermined shape. Problems to be Solved by the Invention Generally speaking, although the
above-mentioned prior art (A) is easy to manufacture and inexpensive, the acoustic
characteristics as an edge are generally not good. In the above (0), although the acoustic
characteristics are good, the material cost is relatively high, and since the time required for
molding is long, the molding cost is high and the price is high. In addition, it is common to
purchase foam sheets produced by material manufacturers and apply processing to this, but
since the foaming state varies depending on the lot, or even in one sheet, depending on the
location, a uniform product with little variation Is generally difficult to obtain. In the case of
foamed polyurethane, there is also a problem that it is easily deteriorated due to temperature,
humidity, ultraviolet light and the like, and the life is short. Furthermore, it is generally not easy
to cause air bubbles to be uniformly generated by mixing air into the elastomer by mechanical
foaming such as stirring, so that the control described in the manufacturing conditions is
troublesome, or variations in products occur. It is expected that there is a problem that it is easy
to occur and the cost is high. The present invention has been made to solve these points and to
obtain a speaker edge with good characteristics without variation and at low cost. In order to
achieve the objects mentioned above, in order to achieve the above object, the speaker edge of
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the present invention is a microsphere, or a microsphere referred to as microsphere etc.,
particularly a shell made of a thermoplastic resin. A expandable coating formed by using
innumerable hollow microspheres obtained by expanding the thermally expandable
microspheres, focusing on the thermally expandable microspheres in which the thermally
expandable material is enclosed. The layer is provided on a fibrous substrate. Such a speaker
edge is manufactured, for example, as follows. First, a fibrous substrate impregnated with a
molding resin is coated with a coating material in which thermally expandable microspheres not
yet expanded are mixed.
Next, this is heat-formed into a predetermined shape required as an edge for a speaker, and the
thermally expandable microspheres are expanded during this thermoforming to form a foamable
coating layer on the formed fibrous substrate. is there. If there is a large difference between the
curing temperature of the molding resin and the expansion temperature of the thermally
expandable microspheres, molding and expansion may be performed in separate steps depending
on the conditions. The above-mentioned coating material is obtained by mixing unexpanded
thermally expandable microspheres at a desired ratio into, for example, synthetic resins such as
acrylic resins and urethane resins, and synthetic rubber latexes such as SBR and NBR. The
coating thickness is selected to be at least a thickness that can eliminate the breathability of the
substrate. The thermally expandable microspheres used in the present invention may be
prepared by thermally expanding, for example, low boiling point hydrocarbon compounds such
as isobutane and inpentane in a shell made of a thermoplastic resin such as vinylidene chloride /
acrylonitrile copolymer. Those enclosed as materials, which are commercially available from
material manufacturers (for example, Micro Pearl manufactured by Matsumoto Yushi
Seiyaku Co., Ltd., Expancel (registered trademark) manufactured by Nippon Fillite Co., Ltd.),
etc. Is available. Such thermally expandable microspheres vary depending on the grade and
grade, but the diameter before expansion is approximately 5 to 50 μm, the volume ratio before
and after expansion is 20 to 100 times, and the softening start temperature of shell material is
100 to 120 ° The maximum expansion temperature is generally around 1.10 to 170 ° C., and a
suitable one is selected and used. なお。 The mixing ratio of the thermally expandable
microspheres in the coating material is selected so that the above-mentioned synthetic resin,
synthetic rubber latex and the like act as a binder for the microspheres, and a foam having a
desired density can be obtained by expansion. Further, since thermally expandable microspheres
include expanded hollow microspheres which have been thermally expanded by a material maker
in advance, they can also be used. That is, a fibrous substrate impregnated with a molding resin
is coated with a coating material in which expanded hollow microspheres of heat-expandable
microspheres are mixed, and then it is foamed on a fibrous substrate molded by heat forming
into a predetermined shape. To form a metallic covering layer. Although it is desirable to coat the
coating material in each of the above methods on both sides of the fibrous substrate from the
viewpoint of obtaining good characteristics as an edge, depending on the case, only one side may
be used. Effect> The expandable covering layer formed by using innumerable hollow
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microspheres obtained by expanding thermally expandable microspheres has a touch, the
appearance of which is almost the same as that of the foamed polyurethane.
Also, the individual thermally expandable microspheres used are identical in shell and material
for thermal expansion if they are the same product, and there is no variation in thermal
characteristics, and if they are ordinary processing steps, differences in heating temperatures
occur Unlike in chemical foaming and mechanical foaming, it is easy to make the foaming state
uniform, and a foamable coating layer with little variation in characteristics and finish state can
be obtained. For this reason, the characteristics as an edge are also comparable to those made of
foamed polyurethane due to the prevention of air permeability by the foamable coating layer and
the appropriate internal loss in addition to the appropriate rigidity and internal loss of the
fibrous substrate. As a result, it is possible to obtain a long-lived edge, since it is not necessary to
use a polyurethane having a problem of weather resistance. Further, in the case of a
manufacturing method in which a coating material mixed with unexpanded thermally expandable
microspheres is coated and thermoformed, innumerable thermally expandable microspheres
expand by heating to form hollow microspheres, which are coated. A foamable coating layer is
formed in a state in which the materials are interconnected as a binder. In addition, when a
coating material mixed with expanded hollow microspheres is coated and thermoformed, a
foamable coating layer is formed in which numerous hollow microspheres are connected to each
other by using the coating material as a binder. With any of these methods, as described above,
the resulting foamable coating layer has the same feel as the edge made of foamed polyurethane
as described above, and is excellent in weather resistance and has less variation. The integral
coating layer and the fibrous substrate together make it possible to obtain an edge which is
comparable to that of the foamed polyurethane. It should be noted that the expanded hollow
microspheres have the function of a filler for the coating material, and the air permeability of the
fibrous substrate can be eliminated by a small amount as compared with the case of expanding
later using unexpanded microspheres. It is possible to obtain a thin and light foamable covering
layer. There are also heat-expandable microspheres using an inorganic material as a shell
material, and if this is used, a foamable coating layer in which the shell is slightly harder than
that made of a plastic resin can be obtained. Next, the illustrated embodiment will be described.
FIG. 1 is a process explanatory view of the manufacturing method in the case of using the nonexpanded thermally expandable microspheres, and is an enlarged view of the thickness direction.
First, a hole 2 is provided in the fibrous substrate 1 impregnated with a molding resin as in (a),
and a coating in which thermally expandable microspheres are mixed in a certain range from the
edge of the hole 2 as in (b) The material is applied to form the coating layer 3 on both sides.
The above-mentioned fibrous substrate 1 may be made of various fiber materials conventionally
used as a base fabric of the edge, and a cloth such as cotton or silk, non-woven fabric, paper or
the like can be used. The molding resin to be impregnated into the fibrous substrate 1 is for
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heating and molding the substrate 1 into a predetermined shape, for example, a roll edge shape,
and various kinds of conventionally used phenolic resins, melamine resins and the like are used.
Thermosetting resins can be used. Further, it is desirable that the thermally expandable
microspheres have the same expansion temperature as the curing temperature of the molding
resin in order to be expanded simultaneously during the thermoforming. In this example, among
the "micropearls" described above, one having a grade of F-80, which has a highest expansion
temperature of about 170 ° C, was used. Next, as shown in (C), heat molding is performed with
the molding dies 4 and 5 heated to the curing temperature of the molding resin from both sides.
Each mold 4 and 5 is provided with an annular recess 4a and a projection 5a corresponding to
the shape of the roll edge, and annular small projections 4b and 5b on both sides thereof, and a
small projection between the two molds 4 and 5 The clearances required for the thermally
expandable microspheres to expand are secured by 4b and 5b. As shown in (d), the roll portion 6
is formed on the fibrous substrate 1 by this heat molding, and the thermally expandable
microspheres expand in the portion of the coating layer 3 sandwiched by the molds 4 and 5. A
foamable covering layer 7 is formed on both sides of the substrate 1. In order to obtain the
foamable covering layer 7 having a uniform thickness, it is desirable that the gap between the
two molds 4 and 5 be sized to limit the free expansion of the thermally expandable microspheres
to some extent. The time required for this molding is about several seconds, which is significantly
reduced as compared with the molding time of, for example, about 30 seconds to 1 minute,
which is required in the case of the edge of the polyurethane foam. Thereafter, unnecessary
portions such as portions which can not expand due to the small projections 4b and 5b are cut
off to form a roll edge 8 as shown in (e). FIG. 2 is an enlarged sectional view of an essential part
of the roll edge 8. The expandable covering layer 7 is a foamed body in a state in which
innumerable thermally expandable microspheres 11 which are expanded and become hollow are
mutually connected with the coating material 12 as a binder, and filled with innumerable hollow
microspheres. Thus, it was possible to obtain a roll edge similar to the foamed polyurethanes in
touch, appearance and characteristics. ちなみに。 The thickness of the fibrous substrate 1 is 0.2
to 0.3 in the case of cotton cloth, and the thickness of the foamable covering layer 7 can be
changed quite freely depending on the amount of heat expandable microspheres, but usually the
expansion is used as a mold It is about 0.3 to 0.7 m in a state of being somewhat restricted.
FIG. 3 is a process explanatory view of a manufacturing method in the case of using a coating
material in which expanded hollow microspheres are mixed, and only points different from FIG. 1
will be described. 13 in (b) is a coating layer coated with a coating material mixed with expanded
hollow microspheres, 14.15 is an annular recess 14a and a projection 15a corresponding to the
shape of the roll edge, and an annular small protrusion on both sides thereof It is a molding die
provided with 14b and 15b, and at the time of molding, small protrusions 14b and 15b secure a
gap between the two dies 14 and 15 so that the coating layer 13 is not crushed more than
necessary. Then, the roll portion 16 is formed as shown in (d) by heating and molding with a
molding die 14.15, and the coating [13 is directly formed into the foamable coating layer 17, and
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the small projections 14b and 15b hit it. The roll edge 18 as shown in (e) can be obtained by
cutting off the unnecessary portion such as the tail portion. The foamable wave i layer 17 thus
obtained also becomes a foam in a state in which innumerable expanded hollow microspheres as
shown in FIG. 2 are interconnected using the coating material as a binder, and the abovementioned unexpanded thermal expansion It is possible to obtain an edge similar to that using
the sexing microspheres. In the case of this embodiment, the thermally expandable microspheres
are thermally expanded in advance, and the coating layer 13 having such a thickness that the air
permeability of the fibrous substrate 1 can be eliminated can be used as it is as a foamable
covering layer. Since the result is 17, the foamable covering layer 17 has a relatively smaller
amount of binder than when unexpanded microspheres are used. It can be a thin and light edge.
The speaker edge of the present invention is, for example. It is also possible to produce by a
method other than the above, such as producing a sheet of foamable coating layer having
innumerable hollow microspheres obtained by expanding thermally expandable microspheres in
a separate step and laminating it on a fibrous substrate. is there. <Effects of the Invention> As is
apparent from the above-described embodiments, the speaker edge of the present invention is a
fibrous expandable foam layer formed using innumerable hollow microspheres obtained by
expanding thermally expandable microspheres. It has a touch, appearance and characteristics
that are almost the same as foamed polyurethanes and the like that are often used for high-end
speakers because they are provided on a substrate and are expensive, and have longer life and
variation than foamed polyurethanes. Less expensive and less expensive edges. Further, in the
method of manufacturing the speaker edge according to the present invention, the fibrous
substrate impregnated with the molding resin is coated with a coating material mixed with
thermally expandable microspheres which has not been expanded yet, and this is heat-molded as
well as thermally molded. The expandable microspheres are expanded to form a foamable
coating layer.
In addition, a coating material mixed with expanded hollow microspheres obtained by heating
and expanding thermally expandable microspheres in advance is coated on a fibrous substrate,
and it is formed by heating to form a foamable coating layer. . Therefore, according to these
production methods, it is possible to produce an edge which has the same feel, appearance and
properties as foamed polyurethanes and the like, and which has a longer life than foamed
polyurethanes, at a lower cost, and Unlike in the case of foaming or mechanical foaming, it
becomes easy to manufacture an edge having no variation in characteristics or finish.
Furthermore, unlike the case where foam sheets are purchased and processed, coloring and
small-quantity production are easy, and it is also possible to meet various demands from the
market. When thermally expanded hollow microspheres are used, the foamable coating layer is
thin and it is easy to obtain a light edge.
[0002]
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Brief description of the drawings
[0003]
FIG. 1 is a process explanatory view of an embodiment according to the first manufacturing
method of the present invention, FIG. 2 is an enlarged sectional view of the obtained speaker
edge, and FIG. 3 is a sectional view according to the second manufacturing method of the present
invention. It is process explanatory drawing of an Example.
] ··· Fibrous substrate, 3, 13 · · · Coating calendar, 4.5, 14.15 · · · Mold, 6, 16 · · · Roll portion, 7, · · ·
· · · · foamable coating layer 8, 18 ... roll edge, 11 ... thermally expandable microspheres. Patent
Applicant Sanon Corporation
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