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Патент USA US2406742

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Sept. 3, 1 946;
D. P. I COOPER, JR
2,406,742
MOLD FOR USE IN THE MANUFACTURE OF OPTICAL ELEMENTS
'
Filed Sept. 2, 1942- ‘
2,405,?!22
Patented Sept, 3, i946
? 'UNITED STATES PATENT omega
‘
2,406,742
MOLD FOR USEZIN THE MANUFACTURE 0
OPTICAL ELEMENTS
>
V
.
Dexter P. Cooper, Jr., Cambridge, Mass, assignor
to Polaroid Corporation, Cambridge, Mass, a
corporation of Delaware
Application September 2, 1942, Serial No. 457,032
13 Claims.
(Cl. 18—34)
2
1
This invention relates to an improved mold for
use in the manufacture of optical elements formed
of polymerized synthetic plastics, resins and like
materials.
An object of the invention is to provide a mold
of the character described comprising a plurality
‘of elements having optically smooth molding sur
faces and a relatively low melting-point cement
for sealing the joints between said molding ele
ments and holding them ?xedly in position during 10
the molding process.
1
faces, which can be repeatedly re-used, and these
elements should preferably be bonded together
and maintained in proper position by an adhesive
or a cement which may be readily applied, easily
removed, and which will stand the temperatures
to which the molds are subjected during the poly
merization‘ of the plastic material therein. With
plastic materials of the class heretofore described
polymerization temperatures are preferably main
tained not greatly in excess of 90 degrees C.
This invention contemplates the use of a fusible V
cement, and preferably one having a relatively low
Another object of the invention is the provi
melting point as the material employed in sealing
sion of a fusible cement which remains hard at
and bonding together the mold walls. The mold
temperatures at which the polymerization process
takes place_
15 may be assembled by placing the glass wall ele
Other objects of the invention will in part
merits in a suitable jig, and while'they are held
be obvious and will in part appear hereinafter.
imposition in the jig, for example by leaf Springs
The invention accordingly comprises the prod01’ other means, they are Sealed along their adje
uct possessing the features, properties, and relaCent edges and Cemented together by applying
tion of elements which will be exempli?ed in the 20 thereto the preferred adhesive or cement in 11101
following detailed disclosure and the scope of the
ten condition The Cement may then be Cooled
application of which will be indicated in the
claims,
'
and it quickly sets and hardens.
The drawing illustrates in perspective a portion
For a fuller understanding of the invention ML
of a mold for use in the manufacture of prisms.
erence should be had to the following detailed de- 25 The mold walls ill are shown as made of glass,
scription taken in connection with the accomthe preferred material, and they are bonded to
panying drawing, which represents partially in
perspective and partially in sectioncone embodi-
gether and held in position by the fusible cement
12- A bottom Plate '4 is also held in position by
ment of the invention.‘
the cement l2.
'
There is today a pressing demand for large 30
A preferred material for use as the bonding
quantities of optical elements, such as prisms,
material in the present invention is a relatively
lenses and the like. This invention is concerned
10W melting-Point ‘alloy, Such as the alloy known
with the provision of molds adapted for use in the
as Weed’S metal, or the alloy known as Rose’s
production of such elements from synthetic plasmetal. Any other fusible cement may be em
tic or resinous materials which are introduced 35 plcyed provided it fuses at a temperature above,
into the mold in a partially polymerized or monobut not greatly above, the temperatures employed
meric state and then polymerized substantially
completely and until they form hard, transparent
optical elements. Materials which have been
in effecting substantial polymerization of the
molded plastic. A fusible cement having a melt
ing point not greatly'in excess of 90 degrees C
found particularly useful in the production of 4,0 is preferred-
Slleh a cement may be poured
such molded plastic optical elements are cycloaround the mold joints Without injury to the
hexyl methacrylate, styrene, methyl methacrylate
glass mold walls and it may be readily removed
and similar materials,
from the mold, melted and re-used, the removal
A considerable percentage of the cost of the
being accomplished at a temperature which does
molded optical element resides in the cost of the 45 not injure the molded plastic.
mold. The light-transmitting surfaces of the eleSince certain changes may be made in the above
ment are preferably molded in contact with glass
product and different embodiments of the inven
elements having optically smooth surfaces, and
tion could be made without departing from its
these are expensive. It will be apparent that in
scope, it is intended that all matter contained in
the production of large quantities of molded op- 50 the above description or shown in the accompany
tical elements it is highly desirable that the mold
ing drawing shall be interpreted as illustrative
may be readily and rapidly assembled and that it
‘ should be easily removed from the ?nished ar-
and not in a limiting sense.
It is also to be understood that the following
ticle. It should comprise elements, and particuclaims are intended to cover all the generic and
larly those elements having optically smooth sur- 55 speci?c features of the invention herein described,
2,406,742
3
4
and all statements of the scope of the invention
stantially optically smooth, and a cement bond
which, as a matter of language, might be said to
ing said walls together and comprising Wood’s
fall therebetween.
metal.
,
What is claimed is:
1. A mold for use in the formation of an optical
8. A mold for use in the formation of an op
greatly in excess of '90, degrees C.
'5. A mold for use in the formation of an op~
members, at least one of said members being
formed of glass and ‘having an optically smooth
surface adapted to define a light-transmitting
tical element of polymerized synthetic plastic
element of polymerized synthetic plastic material
material or the like, comprising, in combination,
or the like, comprising, in combination, a plu
‘a plurality of glass mold vWalls having molding
rality of ‘mold Walls having molding surfaces sub
surfaces substantially optically smooth, and a
stantially optically smooth, and a cement bonding
cement bonding said walls together and compris
said walls together and comprising Wood’s metal. 10 ing Rose’s metal.
2. A mold for use in the formation of an optical
9. A mold for use in the formation of an op
element of polymerized synthetic plastic material
tical prism of polymerized synthetic plastic ma&
or the like, comprising, in combination, a plural
terial or the like, comprising, in combination,
ity of mold walls having molding surfaces sub
a plurality of substantially ?at glass mold walls
stantially optically smooth, anda cement ‘bonding
having molding surfaces substantially optically
said walls together and comprising Rose’s metal.
smooth and forming a prismatic molding cavity,
3. A mold for use in the formation of an optical
and a cement bonding said walls together and
element of polymerized synthetic plastic material
comprising ‘Wood’s' metal.
or the like, comprising, in combination, a plu
1c. A mold for use in the formation of an op
rality of mold walls having molding surfaces £10 tical prism of polymerized synthetic plastic ma
substantially opticallysmooth and de?ning the
terial or the like, comp-rising, in combination, a
‘outer surfaces of the mold cavity, and a cement
plurality of substantially ?at glass-mold walls
bonding said'walls together vand comprising ‘an
having molding surfaces substantially optically
‘alloy havinga melting point not greatly in excess
smooth and ‘forming a prismatic molding cavity,
of 90 degrees 'C.
and a cement bonding said ‘Walls together and
'4. A \mold'for‘use in the formation of an optical
comprising Rose’s metal.
element of polymerized synthetic plastic material
11. A mold for use in the formation of an op
‘or‘the like, comprising, in combination, a plurality
tical element of polymerized synthetic plastic or
of ‘substantially ?at, glass mold Walls having
the like, which formation is effected at a tem
molding surfaces substantially optically smooth,
perature not exceeding a ‘predetermined temper
and‘a cement ‘bonding said walls together and
ature, said mold comprising a plurality of mold
‘comprising'an ‘alloy having a melting point not
tical element ‘of polymerized synthetic plastic
surface of said element, and a fusible vcement
material or the .‘like which formation is effected
‘at ‘a temperature not exceeding apredetermined
bonding said members together, said cement
temperature, said mold comprising, in combi
nation, a plurality of substantially flat, glass
mold walls having molding surfaces substantially
optically smooth, and a fusible, cement bonding
sadi Walls'together, said cement having a melt
said predetermined temperature.
ing point not greatly in excess of said predeter
minedtemperature.
‘6. A mold ‘for use in the formation of an opti
‘cal element of polymerized synthetic plastic ma
terial orithe like which formation is effected at
'a ‘temperature not exceeding a predetermined
temperature, said mold comprising, in combina
tion, a plurality of mold walls having molding /
surfaces ‘substantially optically smooth and de
?ning the outer surfaces of the mold cavity, and
a fusible cement bonding said walls together, said
cement having a melting point not greatly in ex
cess of said predetermined temperature.
'7. A mold for use in the formation of an op
'tical element of polymerized synthetic plastic or
the like, comprising, in combination, a plurality
of glass mold walls havingmolding surfaces sub
having a melting pointnot greatly in excess of
40
12. A mold for use in the formation of an op
tical element, of polymerized synthetic plastic
material or the like, comprising, in combination,
a plurality of mold members, ‘at least one of
said members being formed of glass and having
an optically smooth surface adapted to define a
light-transmitting surface of said element, and
a cement bonding said members together and
comprising a metallic alloy havinga melting
point not greatly in excess vof 90° C.
13. A mold for use in the formation of anrop
tical element of polymerized synthetic plastic
material or the like, comprising, in combination,
a plurality of glass mold walls having molding
surfaces substantially optically smooth and de
?ning a prismatic molding ‘cavity, and a cement
bonding said walls together and comprising a
metallic alloy having a melting pointnot greatly
in excess of 90° C.
DEXTER ‘P. COOPER, JR.
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