Coating employed with laminated head of plastic sheet material and a synthetic fabric material

A head for a drum or similar musical instrument including a synthetic plastic sheet material laminated to a synthetic fabric material having a plurality of layers of randomly orientated individual fibers. An epoxy resin is applied to the synthetic fabric material for coating and sealing the surface, impregnating the layers of fibers and encapsulating each of the individual fibers to preclude delamination of the fibers when the head is subjected to the constant pounding of a drumstick or sweeping motion of a drum brush upon its striking surface.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates generally to the area of drumhead 
construction and, more particularly, to a head for a drum that includes a 
synthetic plastic sheet material, a fabric material laminated thereto and 
an epoxy compound applied to seal and impregnate the fabric material and 
encapsulate the individual randomly orientated fibers therein to preclude 
delamination. 
2. Description of the Prior Art 
Drumheads of various types are well known in the prior art. Hartry, U.S. 
Pat. No. 4,308,782 contains an informative discussion in this area. 
The objective of Hartry is to provide a laminated head comprised of bonded 
sheets of synthetic fabric and plastic materials. The plastic sheet 
material remains the primary tension load carrier while the fabric 
material acts to distribute the load. This combination reduces the 
tendency of the plastic sheet material to dent as well as dampen 
undesirable overtones, and provides an improved brush surface. The 
synthetic fabric material preferred by Hartry includes the category of 
spunbonded olefins, such as polyethylene. In the prior art, polyethylene 
fibers have usually been the material of choice for drumhead construction. 
The material is extremely versatile for use in a wide variety of 
applications and, due to its strength, light weight, smooth finish and 
close simulation to an actual animal skin, has been adapted for use in the 
manufacture of drumheads and similar products. However, polyethylene has a 
serious drawback in its tendency to delaminate when subjected to the 
constant pounding of a drumstick or the sweeping motion of a brush. Thus, 
for example, as the brush sweeps the surface of the head, the individual 
fiber components in the polyethylene tend to come apart and separate 
forming elevated hairlike filaments in which the wire or nylon bristles of 
the drum brush become entangled. 
As a solution to this problem, Remo, U.S. Pat. No. 5,091,248, provides an 
improved drumhead construction involving a laminate of a synthetic fabric 
material comprised of polyester and a synthetic plastic sheet material 
bonded together. The drumhead is coated by a vinylidene chloride 
copolymer, which acts to seal the head surface and impregnate the fabric 
sufficiently to preclude delamination of the randomly orientated fibers in 
the polyester upper layer. Although one major problem appeared to be 
resolved with the substitution of the polyester fabric material in place 
of the polethylene and the use of the vinylidene chloride coating, other 
problems seemed to persist. With the exception of the delamination 
tendency, polyethylene is still generally recognized as a more durable 
material than polyester with a much greater life span. Polyethylene also 
has superior tonal and tactile characteristics compared to polyester 
providing a greater warmth of sound and a more authentic or natural animal 
skin appearance. The Remo drumhead with the polyester upper layer, and 
despite the improvement, is still subject to a certain degree of 
delamination when the head is exposed to rain as so often occurs when the 
head is used with a drum carried in a marching band. Thus, even the Remo 
device is not able to fully address and solve the problems in the prior 
art that continue to plague these drumheads. 
The present invention solves the foregoing problems in the prior art by 
utilizing a combination of elements, including a laminate of a 
polyethylene fabric material and a synthetic plastic sheet material, and 
an epoxy resin coating. The epoxy seals the surface of the fabric 
material, acts to impregnate the layers of the randomly nonorientated 
fibers in the polyethylene and fully encapsulates each of the individual 
fibers eventually mixing with the adhesive contained between the sheet 
materials to enhance the strength of the bond between them. These combined 
elements, which were previously unknown and unexplored in the drumhead 
technology, when working in concert, succeed in improving both the 
integrity of the laminated drumhead, by precluding delamination under even 
the most adverse weather conditions, and the tonal, tactile and visual 
characteristics of the head. 
SUMMARY OF THE INVENTION 
The present invention provides for a head for a drum or similar musical 
instrument comprising a synthetic plastic sheet material laminated to a 
synthetic fabric material having a plurality of layers of randomly 
orientated individual fibers. An epoxy resin is applied to the synthetic 
fabric material for sealing the fabric, impregnating the layers of fibers 
therein and encapsulating each of the individual fibers to preclude 
delamination of the fibers when the head is subjected to the constant 
pounding of a drumstick or sweeping motion of a drum brush upon its 
striking surface. 
The preferred combination of elements that constitute the present invention 
includes a fabric layer comprised essentially of a sheet of polyethylene 
material, which includes several layers of randomly orientated individual 
fibers, laminated to a synthetic plastic sheet material using any 
conventional adhesive, such as an elastomeric high density polyolefin, to 
bond the two together. Applied to the surface of the fabric layer is an 
epoxy resin, which impregnates the various layers of the nonorientated 
fibers, encapsulates each of the individual fibers and ultimately mixes 
with the adhesive to enhance the strength of the bond. When fully cured, 
the epoxy resin acts to seal the surface of the fabric material and the 
area immediately around each of the fibers making the drumhead 
substantially impervious to water and gas infiltration. The resin achieves 
this in large part by creating a bond among the various layers of fibers 
and encapsulating the individual fibers. The resin also mixes with the 
adhesive to enhance its bonding strength. The end result is to preclude 
delamination and to improve overall the tonal, tactile and visual 
characteristics of the head. 
Accordingly, an object of the present invention is to provide a laminated 
head of a drum or similar musical instrument comprising a synthetic fabric 
material having several layers of nonorientated individual fibers and a 
synthetic plastic material that precludes delamination of the synthetic 
fabric material by application of a chemical compound that seals the 
fabric surface, impregnates the various layers of fibers and fully 
encapsulates the individual fibers therein. 
Still another object of the present invention is to provide a laminated 
head of a drum or similar musical instrument that includes a chemical 
compound which coats and seals the drumhead surface and eventually 
penetrates the adhesive that bonds the lamination together to enhance the 
strength of the bond. 
Still another object of the present invention is to provide a laminated 
head of a drum or similar musical instrument that precludes delamination 
of the nonorientated individual fibers in the synthetic fabric material. 
Still another object of the present invention is to provide a laminated 
head of a drum or similar musical instrument which improves the tonal, 
tactile and visual qualities of the drumhead. 
Still another object of the present invention is to provide a laminated 
head of a drum or similar musical instrument that is easily and 
efficiently manufactured. 
Other objects and advantages of the present invention will become apparent 
in the following specifications when considered in light of the attached 
drawings wherein the preferred embodiment of the invention is illustrated.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring more particularly to the drawings, FIG. 1 is a perspective view 
of the present invention depicting a hoop 3 for mounting a laminated head 
2 of a drum or similar musical instrument comprising a top synthetic 
fabric layer 4 made of polyethylene, a bottom plastic layer 6, an epoxy 
resin compound 8, which is applied to the surface 4a of the fabric layer 
4. The epoxy resin 8 acts in several respects. It coats (and later seals) 
the surface 4a, continues into the fabric layer 4 to impregnate the layers 
10 of the nonorientated fibers 12, and then encapsulates each of the 
nonorientated individual fibers 12. Eventually, epoxy resin 8 penetrates 
into the adhesive 14, which bonds the layers 4 and 6 together, to enhance 
the strength of that bond. 
The fabric layer 4 contains filament polyethylene fibers 12 that are 
randomly arranged and highly dispersed. One such spunbonded olefin fabric 
is produced and sold under the trademark TYVEK.RTM.. TYVEK.RTM. provides a 
playing surface very similar to that of natural skins and contains many 
outstanding features, including high tensile strength, high elongation to 
break, excellent tear strength and a high resistance to water, gas and 
certain chemicals. 
A preferred synthetic plastic sheet material is the biaxially orientated 
film of the condensation polymer of ethylene glycol and terephthalic acid, 
which is produced and sold under the trademark MYLAR.RTM.. MYLAR.RTM. is 
not susceptible to moisture and changes in the weather, and has good 
flexibility, durability and tensile strength. However, other synthetic 
plastic sheet materials may also be utilized in the practice of the 
present invention. As an alternative to the plastic, a polyester film may 
also be utilized in place of the plastic sheet material as the primary 
tension load carrier. 
The epoxy resin 8 comprises a compound made from a conventional epoxy, such 
as Ciba-Geigy's GY95-13, an amine hardener and a solvent, such as 
N-methylpyrrolidone. The amine hardener is actually a blend of a 
cycloaliphatic amine and an aliphatic amine. The cycloaliphatic amine is 
provided for its ability to cure effectively under the most adverse 
conditions and to resist moisture. The aliphatic amine is provided to 
contribute color stability to the epoxy compound. The preferred blend for 
the amine hardener is 50/50, though variations, such as a 55/45 or a 60/40 
blend, can be effective for the intended purpose. The preferred proportion 
of the solvent is 5%. Portions at 21/2% and less do not allow for the 
effective penetration of the fabric by the epoxy. Portions increasingly 
above 5% gradually allow for the epoxy to become excessively wet, which 
will undermine the benefits otherwise derived from the compound. 
In practice then, the epoxy resin 8 is formed by first combining the epoxy 
with the solvent and then adding the amine hardener. The preferred 
proportions are 2 parts epoxy solution to 1 part hardener. With the 
lamination of layers 4 and 6 already complete, the epoxy compound is then 
applied to the surface 4a of the fabric layer 4 using any conventional 
means for this purpose, such as a sponge, brush, roller or squeegee 
device. Upon application, the epoxy resin begins to penetrate the surface 
4a into the layers 10 of the nonorientated polyethylene fibers 12 and 
encapsulate each of the individual fibers 12 in the process. The epoxy 
resin 8 continues to penetrate the fabric layer 4 and eventually 
impregnates the adhesive 14, which it mixes with to enhance the bond 
between the fabric layer 4 and the bottom plastic layer 6. The epoxy 
coated laminate is then cured overnight at room temperature or, if an 
accelerated curing is desired, the laminate is placed in an oven for an 
hour or two at 100.degree.-150.degree. F. 
The present invention is a vast improvement over the prior art. The coated 
laminate, as described heretofore, not only provides a drumhead that 
better simulates the appearance of a natural skin than anything before it 
in the prior art, it also provides a product that has greater durability, 
given its resistance to the fraying of the fibers, an improved warmth of 
sound and a more authentic and natural feel. 
While the invention will be described in connection with a certain 
preferred embodiment, it is to be understood that it is not intended to 
limit the invention to that particular embodiment. Rather, it is intended 
to cover all alternatives, modifications and equivalents as may be 
included within the spirit and scope of the invention as defined by the 
appended claims.