THREAD LOCK

FREIN SUR FILETAGES

English Abstract

ABSTRACT OF THE DISCLOSURE
The method of making self-activating thread lock
structures which comprises depositing a fluid material
including an uncured fluid resin in the thread grooves
of a threaded member; immediately thereafter, while the
material is still in fluid condition, applying a thin fluid
film-forming cover coat over the fluid material; and im-
mediately thereafter transforming the cover coat into a
thin, solid, dry, non-tacky, rupturable film by brief
exposure to -radiation, such as ultra-violet radiation.
As previously noted excellent results have been
obtained using ultra-violet lamps as the source of radiation
to effect substantially immediate cure of the film-forming
material, but other sources are comtemplated, such as electron
beam radiation.

Claims

CLAIMS
1. The method of producing an externally threaded
article provided with thread locking means adapted to oppose
separation from a mating threaded article, which comprises
depositing a fluid lock-forming material on a threaded
surface of the article to cause the fluid material to
be received in thread grooves and to fill the bottoms
of the thread grooves, the fluid material comprising an
uncured fluid resin capable of polymerization to a solid
state acting between confronting thread surfaces of a
threadedly engaged mating article, applying a light coating
of a fluid radiation-curable film-forming material over
the deposit and subjecting the coating to radiation for
a few seconds to cure the coating to a thin, dry, solid,
non-tacky protective film over the still-fluid deposit to
permit random association of the article with like articles
without sticking together.
2. The method of mass-producing articles by the
method defined in claim 1, which comprises advancing a series
of articles horizontally continuously in closely spaced
relation through closely adjacent stations for depositing
the fluid lock-forming material, applying the film-forming
coating, and exposing the coating to U-V radiation, after
which the completed articles are immediately suitable for
random accumulation.
3. The method as defined in claim 1, which comprises
depositing the fluid material on the threaded surface and
applying the film-forming material over the fluid deposit
with all at temperatures within normal room temperature
range.
4. The method as defined in claim 1, which comprises
exposing the fluid film forming material to U-V radiation of
an intensity and for a duration sufficient to cure the film-
forming material to a thin, solid, dry, non-tacky protective
film.
22 -

5. The method of mass-producing articles by the
method defined in claim 4, which comprises continuously
advancing a series of articles through a deposit station
and depositing the fluid lock-forming material on the
threaded surfaces as the articles advance, applying the
coating of film-forming material at an applicator station
adjacent the deposit station as the articles continue to
advance, and subjecting the coated articles to U-V radiation
at a radiation station adjacent the applicator station as
they continue to advance.
6. The method of mass-producing articles by the
method defined in claim 5, which comprises applying the
film-forming coating by spray application.
7. The method of mass-producing articles by the
method defined in claim 5, which comprises collecting the
finished articles at random directly after exposure to the
U-V radiation.
8. The method as defined in claim 1, in which
the film-forming material comprises a mixture by weight
of 15-50% of an oligomeric resin, 50-80% of a monomer,
and 3-12% of a photoinitiator system.
9. The method as defined in claim 7, in which
the film-forming material has the composition, with com-
ponents given in parts by weight:
<IMG>
where the photo blend is composed of equal parts by weight
23

of chloroalkyl aryl ketone, amyl p-dimethylaminobenzoate,
and vinyl versatate.
10. The method of making a friction locking bolt
of the type having in the thread grooves thereof circumfer-
entially adjacent deposits of an uncured fluid resin and a
fluid curing agent therefor and a thin, non-tacky, rupturable
solid protective film overlying said deposits which comprises
depositing in the thread grooves of the bolt of
circumferentially spaced locations a fluid resin and a fluid
curing agent therefor, applying a very thin fluid coating
of an ultra-violet settable film-forming material over both
of said deposits,
and thereafter initiating a brief high-intensity
ultra-violet radiation of the fluid coating to transform
the fluid coating into a thin, continuous, solid, non-tacky
protective film which covers the still-fluid deposits in
the thread grooves of the bolt.
11. The method as defined in claim 10, which
comprises supporting the bolt with its axis vertical during
deposition of the fluid resin and, curing agent, application
of the fluid coating and radiation thereof; in which the
fluid resin has a viscosity at ambient temperatures not
exceeding 100° F which permits flow of the resin along
the thread grooves into contact with the curing agent while
preventing substantial flow longitudinally of the bolt;
and in which the deposition of the resin and curing agent,
application of the film-forming material, and initiation
of the ultra-violet radiation all take place at temperatures
not exceeding 100° F.
12. The method as defined in claim 11, in which
the resin is an epoxy resin, and the deposit of resin and
curing agent and application of the film-forming material
are accomplished at about 90° F.
24

13. The method as defined in claim 11, which
comprises applying particulate material to the surface
of the fluid resin before the application of the film-
forming material thereto.
14. The method as defined in claim 12, which
comprises applying particulate material to the surface
of the fluid resin before the application of the film-
forming material thereto.
15. The method as defined in claim 13, in which
the particulate material comprises one or more selected
from group consisting of nylon powder, powdered glass,
metal powders, powdered graphite, crystals of table salt,
and powdered color-imparting material.
16. The method as defined in claim 14, in which
the particulate matter comprises one or more selected from
group consisting of nylon powder, powdered glass, metal
powders, powdered graphite, crystals of table salt, and
powdered color-imparting material.
17. The method as defined in claim 10, in which
the film-forming material comprises a mixture by weight of
15-50% of an oligomeric resin, 50-80% of a monomer, and
3-12% of a photoinitiator system.
18. The method as defined in claim 17, in which
the film-forming material has the composition, with components
given in parts by weight:
<IMG>
where the photo blend is composed of equal parts by weight

of chloroalkyl aryl ketone, amyl ?-dimethylaminobenzoate,
and vinyl versatate.
19. The method as defined in claim 11, in which
the film-forming material comprises a mixture by weight
of 15-50% of an oligomeric resin, 50-80% of a monomer,
and 3-12% of a photoinitiator system.
20. The method as defined in claim 19, in which
the film-forming material has the composition, with components
given in parts by weight:
<IMG>
where the photo blend is composed of equal parts by weight
of chloroalkyl aryl ketone, amyl ?-dimethylaminobenzoate,
and vinyl versatate.
21. The method as defined in claim 11, which
comprises suspending a series of separate bolts from an
advancing conveyor, causing the bolts to traverse stations
at which the resin and curing agent deposits are made,
the film-forming material applied, and the ultra-violet
radiation accomplished, and then removing the finished
bolts serially from the conveyor.
22. The method as defined in claim 21, which
comprises depositing the finished bolts at random in con-
tainers as they are removed from the conveyor.
26

23. The method of making friction locking bolts
which comprises suspending a series of bolts from an ad-
vancing conveyor, depositing a fluid resin at one side of
the bolts as they advance and depositing a fluid curing
agent on the opposite side of the bolts as they advance,
applying an ultra-violet curable fluid film-forming material
over the deposits as the bolts further advances and subjecting
the film-forming material to intense ultra-violet radiation
as the bolts further advance to form thin, continuous,
solid, non-tacky protective films over the still-fluid
deposits thereon.
24. The method as defined in claim 23, in which
the fluid resin is an epoxy resin having a viscosity suitable
for deposition in the threads of bolts having their axes
vertically disposed only at temperatures between ambient
temperature and about 100° F, and which comprises main-
taining the bolts at the aforesaid range of temperatures
during deposition of the fluid resin and curing agents,
application of the film-forming agent, and initiation of
the ultra-violet radiation.
25. The method of producing externally threaded
articles provided with thread locking means adapted to
oppose separation from a mating threaded article which
comprises depositing a fluid lock-forming material on
the thread surface of the articles to be received in the
thread grooves and to fill the bottoms of the thread grooves,
the fluid material comprising a mixture of micro-encapsulated
uncured fluid resin capable of polymerization to a solid
state acting between confronting thread surfaces of a
threadedly engaged mating article and a fluid binder,
applying a light coating of a fluid radiation-curable,
27

film-forming material over the deposit, exposing the coating
for a few seconds to radiation to cure the coating to a
thin, dry, solid, non-tacky protective film over the still
fluid deposit to permit random association of the articles
without sticking together.
26. The method as defined in claim 25, in which
the uncured resin is in a fluid anaerobic mixture, and in
which the material of the capsules, and the protective film
are air-permeable to prevent polymerization of the resin
until escape from ruptured capsules upon threaded engagement
with mating articles and resultant exclusion of air from
fluid resin between confronting thread surfaces.
27. The method as defined in claim 25, in which
the fluid resin is curable by a curing agent, which comprises
incorporating the curing agent in the fluid binder.
28. The method as defined in claim 5, in which
the fluid resin is curable by a curing agent, and in which
the curing agent is a fluid which is also micro-encapsulated
and which mixes with the fluid uncured resin upon rupture
of some of the micro-capsules.
29. The method as defined in claim 25, in which
the fluid binder contains a volatile fluid component and
is adapted to solidify upon evaporation of the fluid com-
ponent.
30. The method as defined in claim 25, in which
the fluid binder remains fluid and protected by the said
film.
31. The method as defined in claim 1, in which
the uncured fluid resin is applied in fluid condition
directly to the threaded surface.
28

32. The method as defined in claim 1, in which
the uncured fluid resin is micro-encapsulated and incorporated
in a fluid binder to form a fluid mixture which is applied
to the threaded surface.
29

Description

- ~ 16~22
- sackground and Summary f the Invention
The present invention represents a substantial
improvement in quantity production of previously known
friction or adhesive thread lock devices of quite different
characteristics, and more specifically relates to improvements
in mass production techniques adapted thereto.
The improvements reside primarily in substantial
elimination of drying time required to protect fluid deposits
on thread area, eit~er permanently, or temporarily as will
later appear.
Briefly stated, the present invention is a method
of producing an externally threaded article provided with
thread locking means adapted to oppose separation from a mating
threaded article, which comprises depositing a fluid lock-
forming material on a threaded surface of the article to
cause the fluid material to be received in thread grooves
and to fill the bottoms of the thread grooves, the fluid
material comprising an uncured fluid resin capable of
polymerization to a solid state acting between confronting
thread surfaces of a threadedly engaged mating article,
applying a light coating of a fluid radiation-curable film-
i'ormlng materlal over the deposit and subjecting the
coatlng to radiation for a few seconds to cure the coating
to a thin, dry, solid, non-tacky protective film over the
stlll-fluid deposit to permit random association of the article
; with llke articles without sticking together.
According to one aspect of the present invention,
adjacent fluid deposits of a two-part adhesive, such as an
uncured epoxy resin and a polymerizing agent therefor are
permanently protected by a thin, dry, solid, non-tacky
cover film applied immediately after deposit of the resin and
actlvator. Accordlng to another aspect of the present
lnventlon, a fluid resln ls micro-encapsulated, or the
resin and an activator therefor are both separately micro-
encapsulated, the capsules mixed into a fluid binder, and
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~ 1~5722
the fluid binder mixture is deposited on the threads. The
fluid binder is temporarily or permanently protec-ted by a
thin, dry, solid, non-tacky cover film, through which, if
desired, a fluid binder component such as toluene may sub-
sequently be eliminated by evaporation.
Reference is made to prior patents 3,489,599,
3,746,068 and 3,814,156, of interest herein.
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~ 165722
irst Aspect (Two part, not capsuled)
In its first aspect, the present invention is an
improvement over my prior invention disclosed in my patents
numbered 4,059,136, issued Nove~ber 22, 1977, and 4,081,012
issued March 28, 1978.
In these prior inventions, particularly as it was
carried out in commercial production, a series of threaded
articles, typically bolts, was advanced while the bolts
were suspended on a horizontally moving conveyor with the
axes of the bolts vertical. The bolts were heated as they
advanced to about 110 F at which ~me an uncured fluid
resin, such as epoxy, was deposited on one side of the
bolt and a fluid activator or hardener was deposited on
the opposite side, and the two fluid deposits allowed to
flow together. Where the two deposits met, there was
an interaction resulting in curing a thin barrier film
of the resin which prevented further mixing of the resin
and hardener.
The next step was to apply in fluid form a cover
coat of a fluid material adapted to transform into a thin
rupturable protective film to protect the still-fluid deposits.
The film forming fluid covering used in commercial practice
was polyvinyl alcohol in a water solution. Since this covering
material was required to dry suf f iciently to permit removal
of the bolts from the conveyor and to deposit them on a
horizontally advancing belt, it was found necessary to raise
the temperature of the bolts to about 135 F before applying
the film forming material. Thereafter the temperature of
the bolts was raised further as they continued to advance
on the conveyor while maintained with their axes vertical
until they attained a temperature of about 160 F. At this
time the PVA was sufficiently dried to permit the bolts to
be deposited serially out of contact with each other on a flat
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horizontally moving belt and thereafter the bolts were
maintained at a temperature of about 100 F, to complete
drying of the fluid cover material to a thin, solid, dry,
non-tacky protective cover film. The finished bGlts could
then be stored or packaged in bulk without damage.
It was further found that when the unaured resin
was a clear or unfilled epoxy resin, it was too fluid if
deposited at 110~ or brought to this temperature after
deposit, so it was necessary to increase its viscosity
by adding a filler, such as nylon powder, or the like.
In practice the conveyor which advanced the bolts
with their axes vertical past stations where the uncured
resin and hardener and the protective cover material were
applied was about twenty five feet long, and the horizontal
belt on which the bolts were deposited and advanced with
their axes horizontal required a length of about one hundred
feet. t~,~ Qs~c~ ~f
In accordance with/the present invention, much
lower temperatures are permissible with very substantial
savings in energy, and in addition the space requirements
o~ the equipment are greatly reduced. Where, as preferred,
the uncured resin is epoxy, it may be applied clear at
temperatures at or not much above a typical room temperature.
For example, it and the hardener may be applied at 90 F,
and at this temperature a suitable clear or unfilled epoxy
resin has a viscosity which allows flow around the thread
grooves of the bolt from one side thereof into contact with
the fluid hardener at the other side of the bolt, but is
not sufficiently fluid to flow downwardly across the threads
away from the point of deposit to leave an insufficient
~uantity of material at the point of deposit.
~ his permits the addition of one or a mixture
of powdered filler materials to the surface of the fluid
; resin deposit at a subsequent station where the powder
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i 165722
is seen to be in effect drawn into the fluid resin rather
than remaining as a surface deposit thereon. A fuxther
important advantage is that in this case the filler material
may comprise a mixture of two or more different materials
such as nylon powder, powdered glass, metal powders such
as zinc, powdered graphite, table salt, and particulate
material selected for imparting a desired color to the
final deposit. It is difficult if not impossible to provide
different particulate material to the fluid resin before
deposit of the resin and to retain uniform dispersion of
the particulate material through the resin, and maintain
the desired proportions thereof. However, when the powders
are mixed prior to application to the surface of the individual
resin deposits, the powder proportions remain constant and
lS the resin-powder proportions may be consistently controlled.
~ he addition of colored powder to previously
deposited clear fluid resin, particularly epoxy resin,
i to impart a desired color to the resin deposit results
in a substantial improvement in appearance and color control
over the prior practice where the coloring agent was incor-
porated into the fluid resin, alone or with one or more
particulate filler materials prior to deposit of the resin
on the bolts.
In the prior practice, where the protective cover
coat was polyvinyl alcohol in an aqueous solution, the final
film thickness over the resin was less than that over the
hardener curing agent, because of the affinity of the curing
agent for water, and the water rejection of the resin.
Accordingly, the application of the fluid cover coat required
the use of a material whose viscosity, which controls the
thickness of the deposited cover coat, catered to the worst
condition. Accordingly, the protective cover film over the
c~ring agent produced a gel as a result of invasion of water
of the fluid cover solution into the curing agent.
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~ 165722
In accordance wi-th this aspect of the present
invention, a protective cover film is providecl by applying
in fluid phase a material which is transformed rapidly into
a thin, dry, solid, non-tacky protective film on exposure to
ultra-violet radiation for a few seconds. In a preferred
form this is initiated while the belt and resin and curing
agent deposits are at sufficiently low temperatures to
permit the deposit of clear or unfilled fluid resin at a first
station, the addition of a particulate material or a mixture
of different particulate materials at a second station,
followed by the application of a fluid cover coat at a third
station, all while the temperature of the components remains
below 100 F, as for example! 90 F.
Immediately after the application of the fluid
cover coat, the bolts are subjected to ultra-violet radiation
for a few seconds, which cures the cover coat into a thin,
dry, solid, non-tacky film, while the fluid resin and curing
agent therefor remain separated and fluid. Since the film-
forming fluid material is transformed in a few seconds to
the solid protective film, this film is of substantially
uniform thickness over the resin and curing agent.
In a particular successful operation, the resin
employed was clear or unfilled epoxy, the curing agent
was a fluid aliphatic amine, and the protective material
was an alcohol solution of an ultra-violet sensitive, film-
forming material to be described below.
Accordingly, this aspect of the invention is a
method of making a friction locking bolt of the type having
ln the thread grooves thereof circumferentially adjacent
deposits of an uncured fluid resin and a fluid curing agent
therefor and a thin, non-tacky, rupturable solid protective
film overlying the deposits which comprises: depositing in
the thread grooves of the bolt of circumferentially spaced
locations a fluid resin and a fluid curing agent therefor,
applying a very thin fluid coating of an ultra-violet
settable film-forming material over both of the deposits,
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~ 1~S722
and thereafter initiating a brief high-intensity ul-tra-
violet radiation of the fluid coating to transform the
fluid coating into a thin, continuous, solid, non-tacky
protective film which covers the still-fluid deposits in
the thread grooves of the bolt.
Second Aspect (capsulesj
According to the second aspect of the present
invention, the friction or adhesive locking material is a
micro-encapsulated, uncured fluid resin and is adapted to
be polymerized to form a solid which provides the thread
locking action when the capsules are ruptured by threading
the article with a mating article.
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I 165~22
In one embodiment of this aspect of the invention,
the locking material is an uncured resin contained in afluid
anaerobic mixture and the resin is maintained in its fluid
unpolymerized condition so long as the mixture is exposed
to oxygen as present in ambient atmosphere. Micro-capsules
containing the mixture are air-permeable so that the mixture
remains fluid in the capsules. The capsules are positioned
on a thread surface in such a way that a plurality of micro-
capsules are ruptured when the article having a thread surface
bearing the micro-capsules is threadedly engaged with a mating
threaded article. The anaerobic fluid locking mixture is at
least partly retained between mating thread surfaces in such
a way that air is excluded, with the result that the resin
polymerizés and opposes disengagement between the threaded
articles.
A known practice has been to apply this anaerobic
fluid directly to a threaded area at the time of use. The
I requirement for applying the fluid material to individual
threaded articles at the time of assembly with mating articles
has prevented substantial commercial acceptance of this
procedure in large scale commercial production application.
As an alternative to app~ication of the fluid
material on individual threaded articles at the time of
assembly, it has been proposed to mix the micro-capsules
containing the anaerobic mixture with a tempo,rarily fluid
binder to produce a fluid material suitable for deposition
on a thread area, in which the material will be received
mainly in the thread grooves. The binder contains a fluid
' or liquid solvent which evaporates slowly to convert the
binder to a dry, solid, non-tacky material which retains
the micro-capsules in position on the thread area, while
, allowing adequate exposure of the capsules to air to prevent
polymerization of the resin.
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1 165722
In a second embodiment of this aspect of the
invention, a locking material is provided in the form of
a fluid uncured resin adapted to solidify or polymerize
when mixed with a hardener.
In this case the uncured resin is micro-encapsulated.
The hardener may be separately micro-encapsulated, or it
may be mixed directly into a temporarily fluid binder. The
capsules containing the uncured resin and the hardener (if
encapsulated) are mixed into the binder, and this ~ixture
applied to a threaded area.
The binder is then dried, as by evaporation of
a fluid or liquid component, typically toluene, and becomes
a dry, solid, non-tacky material which supports the capsules
on the thread area until use.
When the article containing the capsules is threadedly
engaged with a mating threaded member, some of the capsules
containing the fluid resin are ruptured. This fluid resin
is thus exposed to hardener provided in the solidified binder
or in separate micro-capsules, and is caused to polymerize
to form a solid resin between opposed thread surfaces which
establishes abond or frictionally opposes relative movement
therebetween.
; Mass production of these threaded articles in which
at least the uncu~ed resin is contained in micro-capsules,
requires that the treated articles be prevented from sticking
together until the binder has dried. In practice the articles,
such as bolts, are advanced on horizontally moving conveyors
past an applicator station at which the fluid binder mixture
containing the capsules is applied. Thereafter, before the
articles are in condition for random agglomeration, it is
I necessary to dry the binder. This in the past hag required
lengthening the conveyor system andproviding heaters to ac-
celerate the evaporation of the fluid component of the binder.
~ ' '
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1 165722
The present invention as it relates to both
embodiments where the uncured resin is deposited in fluid
condition on the threads, or is micro-encapsulatéd, comprises
the application of a thin layer of a film-forming fluid
material by spray heads at an adjacent station, the material
being adapted when exposed to ultra-violet radiation to form
a thin, solid, dry, non-tacky protective film over the fluid
tacky binder. This material is applied immediately after
deposit of the fluid mixture, and is immediately thereafter
exposed briefly to radiation, such as U-V radiation, which
results in a few seconds in the formation of the non-tacky
protective film.
While this film is capable of providing essentially
permanent protection, it is noted that where a fluid binder
is fluid because of inclusion of a fluid or liquid component
subject to evaporation, the protective film permits evaporation
of this component and escape of the resulting vapor through
the film. A typical component, toluene, will normally
evaporate at room temperature over a period of one or two
days, leaving the binder in a solid state.
Brief Description of the Drawings
Figure i is a side elevation of the twin belt
conveyor.
Figure 2 is a fragmentary sectional view on the
line 2-2, Figure 1.
Figure 3 is a diagrammatical plan view of the
apparatus.
Figure 4 is an enlarged fragmentary view of a
pGrtion of a bolt showing the deposited material and the
protective film thereover.
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DETAILED DESC~IPTIO~
The drawing i~lustrates a procedure applicabie
to both aspects of the invention.
First Aspect
Reference is first made to the drawing ~s il-
lustrative of a procedure in accordance with the first
aspect of the invention, where the uncured resin remains
; fluid, and is protected until use only by the protective
film.
In the drawing a series of bolts 10 are applied
to a conveyor system comprising a pair of belts i2, between
which the bolts are suspended by their heads, as best seen
in Figure 2. The complete system is diagrammatically shown
in Pigure 3. The conveyor belts 10 are moving in the di-
rection of the arrow, and the individual bolts are supplied
at a loading station A. At this loading station the bolts
are at ambient temperature, which may be assumed to be
i about 70 F. In practice, the bolts may be supparted with
~ their heads in contact.
- 20 Preferably the temperature of the bolts is raised
- between stations A and B to about ,90. This may be accom-
plished by electric heaters as indicated at 18.
At B applicators 14 and 16 are provided at opposite
sides of the advancing array of belts,for depositing con-
trolled amounts of the uncured fluid epoxy resin and a fluid
aliphatic amine curing agent. Applicators 14 and 16 may
be of any suitable known type, and may for example be of
the type disclosed in my prior above identified patents.
The fluid resin and curing agent have a viscosity such that
they flow along the thread grooves into contact with each
other, but remain essentially at the axially located zone
of deposition, which may extend for two or three threads
along the bolt.
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~ 165722
The bolts advance from station B to stations
C and D without substantial change in temperature, which
may be maintained if required by additional heaters (not
shown). At station C any desired additives are applied,
such as nylon particles, color particles, graphite or
glass powder, crystals of ordinary table salt, powdered
metals, particularly zinc, or mixtures of any of these
in selected amounts. The particles are applied to the
surfaces of the resin deposits by applicators 2~, and if
desired may also be applied to the surfaces of the deposits
of curing agents. As before noted, the particles appear
to be drawn into the fluid deposits, and leave the surfaces
thereof smooth and concaveLy curved as shown in Figure 4
at 22.
Immediately after deposition of the particulate
matter, if such is desired, the bolts advance to station
D, where a thin application of fluid film-forming material
is made, as for example by spraying from heads 24, located
at both sides of the twin belts 12, shaped to direct the
spray substantially uniformly over the resin and curing
agents deposits. The thin film formed thereby is illustrated
at 24 in Figure 4. ,
The film-forming material is immediately exposed
to strong ultra-violet radiation at station E. The source
of radiation is elongated UV radiating tubes 26, backed by
re~lectors, and positioned at both sides of the array of
bolts 10, and below the twin belts 12. The ultra-violet
light sources used are 8-12" tubes rated at 200 watts per
inch. The rate of advance of the belts is such that the
individual bolts are exposed to the radiation for only a
few seconds, which is sufficient to convert the surface
coatings to extremely thin, solid, dry, non-tacky, protective
cover films.
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i 1¢5722
Reference in the foregoing has been to ultra-
violet radiation as the radiation which converts the thin
liquid film to a solid, dry, non-tacky protective film
in the few seconds which the film-forming material is
subjected to the radiation. While at present ultra-violet
radiation is preferred because of convenience, ready
availability, and economy, other types of radiation ~ay
be employed, such for example as electron beam radiation.
The films 24 are produced by ultra-violet radiation
on extremely thin (0.0005 - 0.0015 inches) coatings of film
forming material.
In general, UV curing-coating compositions are
initiated by a photochemical reaction. In general they
are made up from an oligomeric resin (A), one or more
monomers (B) and a photoinitiator system (C). In some
coatings other types of coatings additives may also be
included such as flow modifiers or surfactants, pigments,
i flame retardants, adhesion aids, stabilizers, gloss en-
hancers, flatting agents or others.
2G The oligomeric resins (A) which can be used are
frequently liquids or readily liquefiable. They include
alkyd resins, unsaturated polyester resins, unsaturated
polyether resins, vinyl ester resins, vinyl ether resins,
acrylic ester resins, acrylic ether resins, epoxy acrylate
resins, curable epoxy resins, curable phenolic resins,
urethane acrylic resins or mixtures of the above.
The monomers (B) are materials which dilute or
thin the coating and are also reactive to W light to form
a solid plastic. They also act as cross-linking agents.
These include chemical compounds which can be classified
as acrylic esters, methacrylic esters, vinyl esters, vinyl
ethers, acrylic ethers, allyl esters, allyl ethers, epoxides,
styrene and substituted styrenes, vinyl pyrrolidone, acryl-
amide and substituted acrylamides, acrylonitrile, dienes.
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i 1~5722
12
The photoinitiators (C) can include aromatic ketones,
halogenated aromatic ketones, benzoin ethers, alkyl aryl
ketones, benzil ketals, o~ime esters, halogenated thio-
xanthones, Onium salts, fluoborates, peroxides, azo free
radical generators, and promotors like tertiary amine
accelerators, organometallic complexes and mixtures of
the above.
The low viscosity W curable coatings preferably
have compositions in the ranges: (A) 15-50%
tB) 80-s0%
. ~C) 3-12%
Some examples of coatings formulations which are
practical:
Chemical Description of Component Parts by Weight
1. Vinyl polyesters of bisphenal A
fumarate . .25 (A)
Styrene . 15 (B)
Hydroxethyl methacrylate 29 (B)
Ethylene glycol dimethacrylate 15 (B)
Dimethylaminomethacrylate 10 (B)
Benzophenone 6 (C)
2. Acrylated glycidyl ether of
bisphenal A 20.(A)
Hexanediol diacrylate ~ 45 ~B)
Trimethylolpropane triacrylate 10 (B)
Vinyl acetate 5 ~B)
Vinyl pyrrolidone 10 ~B)
Diethoxyacetophenone S (C)
Triethanolamine 5 (C~
3. Acrylate polyurethane 15 (A)
Acrylated aliphatic glycidyl ether5 (A)
Tripropylene glycol diacrylate20 ~B)
Trimethylolpropane triacrylate10 (B)
Vinyl pyrrolidone 15 ~B)
Vinyl versatate 25 ~B)
Chloroalkyl aryl ketone 5 ~C)
Amyl ~-dimethylaminobenzoate 5 (C)
Excellent results have been achieved using the
following compoaition for the W curable cover film:
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Urethane Acrylate 600 (A)
Acrylated aliphatic glycidal ether 200 (A)
Tetra ethylene glycol diacrylate 700 ~B)
Trimethylolpropane triacrylate ~50 ~B)
Vinyl pyrrolidone 600 tB)
Vinyl versatate 750 (B)
Photo blend 300 (C)
Vinyl acetate 5~ ~B~
where the photo blend is composed of equal parts by weight
of chloroal~yl aryl ~etone, amyl ~-dimethylaminobenzoate,
and vinyl versatate.
In the foregoing the capital letters in parentheses
following each component represents the appropriate category
as described in ~e material preceding the tabulations.
Described in more general terms the invention
comprises the steps of depositing in the thread grooves
of a bolt at circumferentially spaced stations a fluid resin
and a fluid curing agent therefor, applying a ~ery thin
fluid coating of an ultra-violet settable film-forming material
over both of said deposits, and thereafter initiating a
brief high-intensity radiation of the fluid coating to
transform into a thin continuous solid non-tacky, preferably
transparent, protective film which covers the still-fluid
deposits in the thréad grooves of the bolt. Preferably
the above described steps are taken while the bolt is
supported with its axis vertical. The fluid resin which
is preferably an epoxy resin, has a viscosity at room
temperature and up to about 100 F such that the deposit
wi~l flow circumferentially along the thread grooves but
will not flow downwardly across threads in any substantial
quantity. Accordingly the resin will remain in the axially
located zone of deposition and the fluid resin deposit will
~low circumferentially into contact with the circumferentially
adjacent deposit of the fluid curing agent. Any filler or
other additives desired in the finished product are applied
in powder foxm to the surface of the fluid resin deposit
and in some cases to the deposit of the fluid curing agent.
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The temperature of the bolt and deposits is maintained
between room temperature and 100F.
Up to the initiation of the exposure to radiation,
preferably the temperature of the bolt is brought to about
90F at the time of the deposition of the resin and curing
agent.
The duration of the ultra-violet radiation is a
very few seconds as for example less than ten seconds and
preferàbly between two and five seconds.
Where substantial amounts of particulate material
have been incorporated into the resin, its viscosity is
increased so that even without the protective film, no
undesirable migration of the deposit would take place.
Second Aspect
In the foregoing, a specific exercise of the
present invention has been described, in which an uncured
fluid resin and a fluid activator effective to initiate
polymerization of the resin are deposited on a thread zone
in side by side relation, and protective film-forming fluid
cover material applied over the deposits.
However, the invention is applicable to mass
production of threaded articles on which micro-encapsulated
uncured resin is carried.
It has heretofore been suggested that thread locks
be formed by suitably supporting a liquid or fluid locking
material in microscopic pressure-rupturable capsules located
in the thread grooves of a threaded article. The capsules
are mixed into a fluid binder to produce a fluid mixture
suitable for application to the threads. When the binder
has dried, thé threaded members may be stored without stick-
ing together.
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In prior patent 3,489,599, the capsules contain
an anaerobically pol~merizable composition and the m~terial
of the capsules is air permeable, so that the composition
including the polymerizable monomer, remains fluid. However,
when the threaded article is threaded to a companion threaded
article, some of the capsules rupture and the fluid monomer
is captured in air-excluding relationship between adjacent
thread surfaces. This monomer polymerizes into a solid
material which pro~ides an adhesive or friction bond between
the thread surfaces.
This locking operation is successful but requires
either that the fluid mixture be applied in fluid form to
the threaded member at the point of use just prior to assembly
of mating threaded parts, or encapsulated in microscopic
capsules formed of air-permeable material, which are secured
to the thread surfaces by ". . . suitable means such as
solvent adhesion, a separate coating of adhesive, electro-
static attraction, etc."
In accordance with the present invention the
encapsulated monomer may be mixed with a fluid binder,
such for example as a mixture including a volatile fluid
adapted to dry to a solid non-tacky condition in which
the threaded articles may be stored in bulk at random
without sticking together. This however requires expedi-
tious elimination of the volatile fluid from the binder.
In mass production, it is a practical re~uirementthat the treated articles be continuously advanced on
suitable conveyor means which holds them separated. Con-
veniently this may be accomplished by advancing bolts,
for example, between parallel bslts as illustrated at 12
in Figs, 2 and 3, and applying the fluid mixture of capsules
and fluid binder by brushes or the like. Before the treated
articles are in condition for random agglomeration, the
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16
binder must be dried, and this has in the past required
heating the treated articles as they continue to advance,
and a greatly increased conveyor length~ The former is
wasteful of the energy required to heat the articles,
and the latter is wasteful of space.
In accordance with the present invention, the
fluid mixture of micro-capsules and a fluid binder containing
a volatile liquid, such as toluene, is applied serially
to the articles as they pass an applicator station. This
may be the Station B in Figure 3, where the mixture may
be applied at one side of the articles 10, or at both sides.
In the later case, the fluid mixture may flow around the
thread grooves to form a 360 ring. The fluidity however
is preferably such as to prevent substantial flow axially
downwardly across thread grooves.
Substantially immediately after application of
the fluid mixture, a thin liquid coating of the radiation-
i sensitive film-for~ing material disclosed herein is applied
as in the form of a spray, covering the still-fluid mixture.
This applicationtakes place at station D in Figure 3.
Immediately after the application of the radiation-
sensitive film-forming material, the articles traverse
radiation station E, where the film-forming material is
8ubjected to a very brief radiation treatment by ultra-
violet lamps 26. This has the effect of setting the film-
forming material into a dry, non-tacky film.
The film thus produced is air-permeable, so that
oxygen continues to reach the micro-capsules to prevent
polymerization of the encapsulated anaerobic monomer.
The film covers the deposit on the thread, so
that it is non-tacky. Immediately after treatment by the
ultra-violet radiation, the articles may be discharged
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from conveyor 12 and randomly agglomerated and collected
in containers on belt 28 without sticking together. A
further advantage is that the air-permeable film penmits
escape of the volatile component of the binder. Where
this component is toluene it is found that it will have
been eliminated in a day or two, at room temperature.
The minor heating effect of the U-V lamps has the further
useful effect of acceleration evaporation of the Yolatile
binder component.
By the practice of the foregoing, it has been
found that the equipment may be a 15 foot conveyor run
at 38'/min as compared to a 100 foot conveyor run at 14'/min
required in the past.
In prior patent 3,746,068 there is suggested micro-
encapsulation of an unpolymerized resin, such as 1, 2-epoxy
resins and mixing these capsules into a fluid binder or
adhesive to produce a fluid mixture suitable for application
! to the threads of a threaded article. The binder includes
a curing agent for the resin, and various amines are dis-
closed as suitable. The binders disclosed in this patent
all include fluids or liquids capable of being eliminated
by evaporation. In general, toluene is the preferred
liquid, and this material is volatile and evaporates,
but a protracted drying period usually with concurrent
heating is required.
In accordance with the present invention, the
fluid deposit including the micro-capsules is provided
with a spray coating of film-forming, radiation-sensitive
material, and immediately thereafter is subjected to the
radiation from U-V lamps 26. The film forms substantially
immediately and the treated articles may be placed at random
in containers. Again, the volatile component of the binder
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I 165722
18
escapes through the film, and the binder'thus m~y solidify
over a period of one or more days. However, no special
additional hanaling of the treatea articles is necessary
after exposure to the U-V radiation.
Patent 3,814,156 relates to friction locks on
threaded articles, and suggests micro-encapsulation of
an anaerobic monomer as the preferred adhesive of friction
producing material, substantially as disclosed in Patent
3,746,068, described above. It also discloses the use
of a mixture of separately micro-encapsulated two part
' adhesives, such as an epoxy resin and an epoxy hardener,
applied in fluid condition in a fluid binder, which may
contain a water solution of polyvinyl alcohol, or toluene.
In any case, the binder is said to "form a unified coating
on the threaded fastening member after evaporation of the
solvent." The invention claimed in this patent is the
addition of special torque-tension control agents, but
the disclosure is of micro-encapsulated materials in a
fluid binder which of course requires protracted drying
before the threaded products can be randomly mixed.
~ Thus it will be apparent that the present invention
has the result of effecting major~economies in energy, space,
and time in large scale mass production of threaded articles
provided with a patch or area of friction-producing material
applied in fluid form and substantially immediately protected
by a dry, solid, non-tacky film which permits correspondingly
immediate random agglomeration of the articles. The locking
material, or a component thereof, may remain in liquid or
fluid condition and be protected only by the protective
film. Alternatively, the locking material or a component
thereof, may be micro-encapsulated and the capsules retained
on the threads by a binder which itself is applied in fluid
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7~
19
condition and protected by the film, either permanently,
or until a liquid component of the binder has escaped
by evaporation.
While a general description and examples of the
ultra-violet sensitive film-forming material is set forth,
it will of course be understood that any composition having
the required physical properties and behavior as described
herein may be employed.
Reference is made herein to the temperatures at
which the deposition of lock-forming material is made, and
the temperatures at which the coating of film-forming material
is provided.
These temperatures are broadly defined as within
normal room-temperature ranges or manual handling tempera-
tures, to differentiate sharply from depositions at highly
elevated temperatures, such as the deposition of nylon powder
on thread surfaces above the melting temperature of nylon,
or subsequent heating of powder deposits on thread surfaces
to a temperature sufficient to melt the powder.
Specifically reference has been made to tempera-
tures of less than 100 F, as for example 90 F prevailing
at the time of deposit of the lock-forming material on the
; threads, which are considered to be within a normal room
temperature range.
The station B is referred to herein as the deposit
station, station C as the filler station, station D as the
applicator station, and station E as the radiation station.
It will be understood that where the present
invention requires the use of a fluid binder, the binder
material may be any of those disclosed in the prior patents
3,489,599, 3,Z46,068 or 3,814,156.
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I 185722
Advanta~esi of Both Aspects
In the foregoing two separate aspects of the
invention have been discussed. In one the polymerizable
resin is applied in fluid form directly to the threads
and a second fluid deposit of a curing agent is also
provided adjacent the resin and directly on the threads.
These fluid deposits are covered and protected with the
radiation-curable film discussed in the foregoing.
In the second aspect of the invention, the poly-
merizable resin is provided in micro-encapsulated form and
may be an anaerobic resin or it may be a resin which requires
a curing agent to polymerize. In either case the micro-
encapsulated material is applied in a fluid binder and it
is this fluid binder which is protected, either temporarily
or permanently, by the protective film.
Thus in both cases the protective film is applied
over a fluid material, and is rapidly cured to provide a
! thin, dry, non-tacky protective film which permits the
threaded bolts to be randomly accumulated immediately after
the cure of the protective film.
In mass production of the articles, an essential
feature is the continuous movement of a succession of
articles through closely adjacent station to apply the
fluid deposit, to apply the film~forming coating, and to
expose the coating to U-V radiation, at which time the
articles are completed, all without the necessity of and
substantial time delay between stations, or after the U-V
exposure. In a commercial practice of the invention, the
overall length of the conveyor line was only fifteen feet
long, and the conveyor was run at 38'/minute. Adjacent
articles on the conve~or may have heads in contact so that
if bolt heads are l/2", the line capacity will approach
l,000 pieces per minute.
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165722
21
The present invention in commercial production
results in a saving in overall power consumption of about
60~. In addition, the process a~oids the high temperatures
reguired in some prior methods. The present method permits
-5 a better control of addition of additi~es to the resin,
and an impro~ement in the appearance of the final product.
A very important ad~antage of the present process is that
it requires a conveyor whose length is only a small fraction
of that required for conYeyorS and belts in prior production
equipment.
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