SAFETY RAZORS

RASOIRS DE SURETE

English Abstract

A safety razor having one or more blades (14) seated
between a cap (11) and guard (12), said guard cap and guard
having a comb configuration in which a comb like moulding
(18) of a mixture of polyethylene oxide and a structural
polymer, such as polystyrene is positioned between the teeth (13) of
the comb-like cap portion, the teeth (19) of the polyethylene
oxide-containing moulding being narrower than the space
between the teeth of the cap portion so that the blade unit can
flex concavely.

French Abstract

Rasoir de sûreté comprenant une ou plusieurs lames (14) placées entre un couvercle (11) et un dispositif de protection (12). Ces deux derniers éléments ont la forme d'un peigne dans lequel une moulure en forme de peigne (18) composée d'un mélange de poly(éthylène oxyde) et de polymère de structure, comme du polystyrène, est placée entre les dents (13) du couvercle en forme de peigne. Les dents (19) de la moulure contenant du poly(éthylène oxyde) sont moins espacées que celles du couvercle, ce qui permet à la lame de fléchir de façon concave.

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY OR
PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A safety razor which comprises a razor blade unit
having at least one generally planar blade with a cutting edge,
which blade unit is readily flexible about an axis or axes
parallel with the plane of said at least one blade and extending
substantially perpendicular to the cutting edge thereof;
a handle; and
connecting means disposed cooperatively on said blade
unit and said handle for connecting the blade unit to the handle
which means permits flexing of the blade unit, the blade unit
comprising:
a molded plastic housing including:
a guard portion having spaced apart teeth interconnected
by a thin, flexible web;
a cap portion having spaced apart teeth interconnected by
a thin, flexible web;
said at least one blade being clamped between said cap
portion and said guard portion;
said blade unit further comprising a molding having
spaced apart teeth interconnected by a thin, flexible web, said
molding including a mixture of polyethylene oxide and a structural
polymer, the teeth of said molding positioned between the teeth of
said cap portion, the teeth of the polyethylene oxide-containing
molding being narrower than the space between the teeth of the cap
portion so that the blade unit can flex concavely.
2. A razor according to claim 1, in which the teeth of
the polyethylene oxide-containing moulding are level with or
project above the teeth of the cap portion.

Description

W092/~827 2 0 9 2 ~ 3 2 PCT/US91/07468

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Safety Razors
This invention is col.ceL,.ed with safety razors
which comprise a flexible razor blade unit secured to a
handle by com)e~Ling means arranged to permit flexure of
the unit when the razor is used.
The blade unit is flexible in the sense that
it is readily flexible, in ~U~Jl~ce to forces
encuul.Lered during no -1 use, about an axis or axes
parallel with the plane of the blade unit and exten~i ng
substantially perpendicular to the cutting edge(s) of
the blade(s). Safety razors of this kind are described
: for example, in British Specifications 1589591 and
2119690.
: . one form of blade unit for such a safety razor
comprises a flexible blade or tandem flexible blades
with a flexible spacer the .beL~een, which blade or
hla~e and sp~cer are mounted in a moulded plastics
hou~sing providing a comb-like guard portion and a comb-
like cap portion, the teeth of the two comb-like
portions being inte~con-.e~ed by a web which is
sufficiently thin to be flexible. The blade unit is
con-~c~Led to a razor handle by connDcting means which
penmit flexing of the;blade~unit in.use. .. .,.~.
~ ~ We have now.developed an;improvement..of such a
safety razor.in which..a comb-like mo~ ing of a mixture
of polyethylene oxide and.a~structural..polymer,~such as
poly ~y ene, is positioned~.beL~e.Ln.the teeth.of the
1, $~ ,73 r ~

W O 92t06827 ' P ~ /~S91/07468

2 o92~32 2 ~'
comb-like cap portion, the teeth of the polyethylene
oxide-containing moulding being narrower than the space
between the teeth of the cap portion so that the blade
unit can flex concavely.
According to the present invention, there is
provided a safety razor which comprises a razor blade
unit which is readily flexible, in response forces
enco~lntered during normal use, about an axis or axes
parallel with the plane of the blade or blades and
10 exten~ i ng substantially perpendicular to the cutting
edge(s) thereof, a handle, and co~necting means
co,.ne~Ling the blade unit to the handle which means
permit flexing of the blade unit, the blade unit
comprising a moulded plastics housing providing a comb-
like guard portion and a comb-like cap portion between
which the blade or tandem blades with a spacer
therebetween is/are clamped, the teeth of the two comb-
like portions being interconnected by a web which is
sufficiently thin to be flexible, and the blade unit
further comprising a comb-like moulding of a mixture of
polyethylene oxide and a structural polymer, positioned
between'the teeth of the comb-like cap portion, the
teeth o~ the polyethylene oxi~e cGn~;ning moulding
being narrowèr than the space between the teeth of the
cap portion so that the blade unit can flex concavely.
The teeth of the polyethylene'oxide-cont~in;ng
moulding are preferably level with or projèct above the
teeth ofithe càp portion.' ' '~ ' ''
.. . .. . .. .. .... . . .. . . .... . .
f '~~ ' The use of inserts formed of a mixture of
polyethylene'oxide and a structùral polymér', such as
' -- poly~yLene,'in the cap and/or the guard portions of
razors and blade-units to improveishaving perf ~ -nce is
~~ known and-has'been described,'for example,~in'British
Smëcification''2024082. "Such inserts typicalIv contain
- 35 by weight, 80% of polyethylene oxide and 20% of
structural polymer. The present invention provides a
particularly col.~el,ient way of inco-~oL~ting

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W092/06827 PCT/US91/07468
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polyethylene oxide co~ ining inserts in a flexible
blade unit of the kind described.
A ~uL~enLly preferred . ~o~i -nt of the
invention will now be described, by way of example, with
reference to the i~-c ,-nying ~rawings, in which:
Figure 1 is a perspective exploded view of the
razor, and
Figure 2 is a similar view of the assembled
razor.
The illustrated razor comprises a flexible
blade unit 10 which comprises a moulded plastics housing
11 (made, for example, from poly~Ly.~r.e) which has a
comb-like guard portion 12 and a comb-like cap portion
13 between which a combination of tandem single edged
razor blades 14 with a sp~c~r 15 therebetween is.
., clamped. The blades 14 and spacer 15 are retained in
the coLL~L position by ~LUL~clon~i (not shown) in the
housing and ~luLL~sions (not shown) on the spacer 15
which ~S~gi~ge in slots 16 in the bl ~A~S . Slots are used
so as to allow relative muv~ - L of the blades and
. spAcer during flexing. The teeth-of the comb-like
,.. portions 12,and.13 are:inteLco~ DcLed by a web 17 which
-, is sufficiently thin~for the blade unit 10 to be
:~ ~flexible. . .:., - ' . ~. ,
. The blade unit further comprises a comb-like
; polyethylene oxide _i~n~i~in;nq l~ing 18,-the teeth 19
of which are posit;nn~ beLs~een the teeth of the cap
., .portion,13,r~,theiwidth of~the teeth l9~being less than
.the space beLs~_e.. the teeth of the,cap portion (when the
30 .~blade unit-is ~nfl~y~ so that the.blade unit can flex
CO~s~ aVely ~ ~ i - - 5
The:teeth.l9 of.-the polyethylene oxide-
r.~-con~ ning mo~ ng 18~are int~Lco~ D~Led by a~web 20
~ which is~adhesively,;se~.ad.to the back'of the~web 17.
; 3S ~ As can be seen-from.Figure''2,r~ in the as'sembled~f ''
,condition,'.-the teeth~lg of~the polyethylene oxide-
', .,cont~ining moulding 18 are level-with the teeth 13 of

W092/06827 PCT/US91/07468
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the cap portion.
Figures 1 and 2 further illustrate a preferred
-nn~r of ACS~ ~ling the blade unit, that is the
polyethylene oxide-cont~;ning moulding 18 is not
separated from the sprue 21 with which it is moulded
until the l~ng 18 has been ho~Ae~ to the housing 11;
the sprue 21 is then cut away (see Figure 2).
The blade unit 10 is co~n~cted to a handle 22
by means of three posts 23,24 ~p~;ng integrally from
the underside of the housing 11 which slidably engage in
co~lC~G~ing slots 25,26 in the head of the handle.
The posts 23,24 extend perp~n~ic~ rly to the parallel
planes of the h~a~es and are positioned directly
underneath the blade edges, i.e. passing through a
region bordered by the blade edges. The central post 24
is guided for rect;l;n~r sliding .~ -nt within the
slot 26: this post therefore centr~lices the unit
longit~A;n~lly, without interfering with its flexure.
The outer posts 23 each have a pivot pin 27 projecting
through them, parallel with the axis or axes of flexure
of the blade unit, and these pins 27 are received in and
guided by elongate slots 28 formed in the walls of the
slots 26, so that they accommodate flexure of the blade
unit, which is accompanied by movement of the ends of
25; the unit towards and away from each other. The pins 27
also ~L~V~ withd,~ 1 of the blade unit from the
handle.
- ~ The posts 23 are set in from the ends of the
: unit 80 as to permit the blade unit to flex convexly if
-one or both ends cnco~ter larger forces during shaving
than the medial portion of the unit. ;
-~ In order to protect the blade unit from damage
.J ;due to -~ce~sive flexure in both cun~ve and CGIlveX
~modes it has been found .~c~ess~ry to limit deflection
both at the c~nLLa and at~the ends of the cartridge.
~ : In the-concave mode, deflection from the
unflexed plane is limited by abutment of the underside




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W092/06827 2 ~ ~ 2 5 3 2 PCT/US91/07468
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of the platform with the cenLle of the head of the
handle. In the convex mode, deflection of the outer
portions of the blade unit is limited by abutment of the
underside of the outer portions of the platform with
outer portions of the handle head.
In a particular embodiment the concave
deflection is limited to 2.5 mm at the ce,.~,e, and the
convex deflection is limited to 3 mm at the ends, of the
blade unit. The ~p~cinq of the outer posts 23 is
preferably 2/3 of the overall length of the blade unit.
The main forces en-oun~ered during shaving are
directed perp~nAic~ r to the plane of the hlA~Pc (or
blade) and passing through a region bordered by the
cutting edges of a tAn~ blade unit. Since the posts
23,24 are aligned with those forces, they do not
~nCou~Ler any substantial b~n~;nq moment which would
otherwise tend to tilt them and create a tQndency for
the pins 27 to bind in the guide slots 28.
Whilst we have de6cribed an . ~ ment in
which the polyethylene oxide .~o~Ain;nq moulding is made
separately from the housing 11 and is adhesively hon~ed
to the latter, the polyethylene oxide COII~ ~;n;ng
moulding can be made in ~i~ by a two stage moulding
plocess, namely a y~oce88 in which different materials
are moulded into a single component by moulding one
material first and then ll~;nq the seco~ n situ.
This y uaess can be used to mould the housing and the
polyethylene oYi~e ~ollLA;ninq mo~ ;ng as a single
component (fipAc;nq pieces being inserted into the mould
before the injection of the polyethylene oxide-
cont~;n~nq mixture to provide the de6ired gaps between
the cap teeth and the teeth of the polyethylene oxide-
cont~ininq moulding. This eliminates the need for
A~he6;Ve ho~ing and the ~du~ion in the flexibility of
the unit which might arise from the use of an adhesive.

Representative Drawing