Note: Descriptions are shown in the official language in which they were submitted.
1774
~ ia in~rention relates to a ~qritable hdhe~i~re
tape.
Curr~rltly knor~ a:re adhe~ive tap~s which
compri~3e a ~ub~trate~ mo8tl;y form~d ~rom a ~lexible
pla~tic material, hav~ng on o~e ~ide a coati~g or layer
o~ an adhe~i~e wh~ch, in u~a, adhe~ whs~ applied ~ith
a ~light pressure, i.e~, an adhe~iYe la~er~ a~d ~ the
oppo~lte ~ide a~ a~ti-~ldhesi.ve coati~g or layer whi~h
ia al~o ~uited ~o be written or printed u?orl (the
10 term "writE~blen ~,nill be u~ed herei~after ~or brevity)
by means o~ arur ordinary writing or pr~nting mean~,
In fact, that coa~ing~w~ioh ha~ in such tapes the
function o~ a ~ritabl~ layer i9 ~ IBO required to per~orm
a~ ~ti-adhe3~:ve or '~elsa~e~ function ~relea~e coati~g)9
15 ThiEI becaul3e ad~esi~e tapes are mostly sold in the
~orm of rolls w~erein the tack~ side
contaet~, owi~g to the rol~ing up~ the juxtaposed
writabl8 0id~ .
order ~or the tape to be ea8ily us~olled
2~ without dams,~e to the tape it9eL~, it i~l ~ace~ary to
pre~ent ~h~ writable ~id~ ~aoing the . adheaive
"la~rer" from 8'tiC3~i~ to the latter, i~,e. to ma~e ~t
adhesion-pr~r~ti~gO
~ Sever~ able sel~-~ti.o}~l~g (adhe~i~re )tap~ ve b~
25 sugg~3ted in the pa~t~ ~rhich dif~er from one another by
the ~a~ure of the compo~ent~ which m~:e up the
su~trate9 adhe~i~e la~er9 ~d a~ti~esi~e layer9 a~
~vell as bg the ~ature of tha m~a~& utilisGed to mal~
th~ ~ti-adhe~ er ~a~Le,, Tn general~ th0 a;nti~adh~
30 d~ la~er i~ made ~ita~Le ~r rou~g or matting
77
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it by mechanical mean~ or by incorporating therein
some ~illere, e.g. mineral fillers.
~ apes have been ~ugge9ted ~or example, wherein
the anti-adhe~i~e wribable layer i~cluded a polyuretha~e
resin a~ a gilm-generating re~in, and an an~i~sdhesi~e and
matting agent (~ee US Patent No. 4138527). ~aid patent
mentions polyvinylchloride as a pre~erred sub~trate
for ~he ~uggested ~el~-stiok~n~ tape,
although it also discloses ~ome other aUl~b~ ~.~bstrates,
such as polypropylene.
However, ~e have experimentally
ascertained that, on a polypropylene substrate, the release
or an~i-adhesive layer taught by the aforementioned
US patent was inadequately sec~, and ~he risk exi~ted
that9 upon unr`o~ng the tape, ~aid anti~Qdhesive layer might
be stripped o~ the sub~trate, thus making the tape
unusable.
Briti~h Patent Application~ ~o. 2103513 discloses
a writable adhesi~e tape, wherein, on 2 polyprop~lene
ZO sub~trate9 a ~ritable layer is applied which again
comprises polypropylene incorporating ~ine particl0s
of an inorganic filler. In thi~ particular in~tanca,
therefore, a secure bond between the writable l ayer
and polypropylene substrate ~as achieved b~ u~in~ the poly-
propylene itself as a ~ilm-generating resin in the
writable layer as well.
Further sel~-sticking tape~ have been ~ugge3ted
comprising, as ths anti-adhe~i~e coatin~ suited to
: be marked a~ by writing or printing, a ~ilm generating
;
~ 26 ~7~
resin~ in particular a polyester reain, a polyketone
re~in meant to imp~rt print~bility~ and conventional
anti-adhesive agents (US Patent No. 4070523)o
The self-sticking coatings reco~mended
hereto~ore for writable self-~ticking tape~,
ha~e the di~advantage of being dif~icult to use with
olefinic polymer substrates which haYe not been
previou~ly coated, on the back side intended to reoeive
the anti-adhes1ve agent, with a bonding or primer
layer, or ha~e not been subjected, on that same side,
to a sur~ace treatment of the chemical or electronic
type ~corona effect, flame treatment, etc.). This hold~
particularly true for polypropylene substrate tape~ OW~Dg
to the inadequate bonding that can be obtai~ed bet~een
known compositions for the anti-~dhe~i~e writable coating
and polypropyleneO
It is a primary object of this invention to
provide a sol~-~ticki~g tape that can be e~sily written
upon and unrolled, while economically advantageous.
In particular~ it is an object of the in~ention
to pro~ide a ~elf-sticki~g tape having an anti-~dhe~ive
wri~able layer that can be very well secured
to an economically adva~ ~ polyolefinic substrate.
A ~urther object of thiR invention i~ to provide
a sel~-stic~ing tape o~ the ~pe mentio~ed ~bove 9
which requires no addition&l p~ing layers, nor any
~urface treatment of the chemical~ electronic~ or
flame type to ensure integrity o~ its structure.
These and oth~r object~, such as will be apparent
, .
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~ 7 7 ~
hereinaf~er, are achieved by a self-sticking tape .
according to the invention, which eomprises a flexible
plastic material ~ub~trate~ a ~el~-sticking coating
on one ~ide thereo~, a~d an anti-adhe~ive writable
coating on the opposite side, characterized
in that said ~ub~trate i~ ~elected ~rom oriented and
non-oriented films of slpha-olefine polymers and
copolymers, and said anti-adhe~ive ~ritable coating
comprises at lea t one chlorinated polyole~ine and a
polyaldehyde resin as the film ~orming and the adhe~ive
promoters to the sub~trate~ along with at least one anti-
adhesive agent and at lea~t one matt~ a~ent~
It has, in ~actS been ~ound that the simultaneou~
presence, ~n the antl-adbesi~e la~er o~ the in~ren~re tape,
15 of the chlorinated polyolefine and polyaldehydic
re~in, con~ers to ~aid layer optimum film~orming
and bonding properties toward the polyolefinic
~ub~trate~ ~uch a8 not to jeopardize the t~pe integrlty
whe~ unrol~ing even in ths absence of any further
20 bonding layer or treatment. Furthermore, the anti-aahe~ re
layer of the inventi~o tape, incorporati~g the
aforesaid anti-adhe~ re and~ mattlng agent~9 gho7~3 a hi~h
degree of ~ifor~ity both in appe~rance and writabillty
or printability, which remains u~altered after the
tape has been ~ound and unwound in use.
It has al90 been ~ound that the tape of this
in~ention ~ psr~ ly ad~antageous a~so wnth helio-
graphic printing techniques, where it affords a hi~h
quality printing. ~oreo~er, the tape pro~ed to ha~e
3 profitable easy tear properties in the tr~sver~al
.. ~
774~
direction, which greatly facilitates its use in practical
usual applications.
The chlorinated polyolefine which may be used in the
tape of this invention, may be any homopolymer or copolymer
polyolefine having a chlorine content in the 15% to 65%
range, or mixtures thereof, and a suitable molecular weight
for film formation, a Brookfield viscosity preferably in the
to 180 centipoises range and a specific gravity at
25/25C preferably in the 0.850 to 0.950 range, for 25%
solutions in xylene. By way of example, chlorinated
polyolefines may be used which are available commercially
under the trademark CP 343, produced by Eastman Kodak,
U.S.A., or trademark HARDLEN, produced by Toyo Kasey Kogyo,
Japan, under the trademark TRAPYLEN, produced by Rowa,
Germany. The chlorinated polyolefine varies in amount from
25% to 55%, preferably 35% to 40~ by weight relative to the
overall weight (dry) of the anti-adhesive layer componen-ts
in the final product.
A usable polyaldehyde resin may be any polyaldehyde
resin obtained by reaction of a 4-to-8 carbon atoms, linear
or branched chain aliphatic aldehyde such as
isobutylaldehyde with urea. Among the ~uitable polyaldehydes
is the one available from BASF under the trademark LAROPAL
8652. The u~able amount of polyaldheyde ranges from 20% to
50%, preferably 30% to 40% by dry weight.
In addition to the two film-forming resins used in the
anti-adhesive writable layer of the tape of this invention,
the layer may include, according to
tï
.
.. . .
;
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:.
~6~77
~ 6
alternatiYe embodiments of the invention, further re3in
componentis.
~us~ ~ccording to ~nother embodiment of the
anti-adhesive ~!vritable layer, tl~is comprises 25y to
59~ju of said chlorinated polyole~ine7 15~ to 30p of
~sid polyaldehgde, together with 5~ to 20~ o:E a linear
elastomeric polyuretha~e as film~:I'oxmir~
resins~ in addition to said anti-adhesi~e agent ~nd
~aid mattlng ager~t.
~referably, for the film-form~g and bonding
resins, the follo~ing proportions are used in this
embodimelt: 35,~ to 406jo chaorinated polyole$i~, 20jo to
; 2550 pol~aldehyde, and 10C/~ to 1570 polyurethane.
The usable polyurethane i~ a linear elastomeric
', 15 polyurethane ha~ing preferably a high crystallinity.
I As an example, a polyurethane ob~ained by reacting a
i polyester having end hydroxyl group~ as deri~ed from
a dicarboxylic acid o~ 4 to 10 carbon atoms and a
diol of 4 to 10 carbon~i, with æn aliphatic or
2a aromatic di-isocyanate, ma~ be u~ed. Also a polyester
obtained by the reaction of adipic acid with hexanediol
and then cross-linked with toluene-di-isocyan~te,
may be u~ed.
By way of exemiple9 c.~iable polyurethane i~ the one
available from BASF under the trademark of lUsi~E;~
142~.
: ~he anti-3dhe~1~e ~unctio~ ia proYided by lncorporat-
ing,q~to the anti-~dhesi~e l~yer ~ the inventive tape, ~n
~: anti-adhe~i~e or rel~aQe agent ~elected from thoRe
3 con~en~ionally utili~ed ~or t~e ~ame pu~po~e. Among
,"., .
lZ60774
such agents may be mentioned the polyvinylalkylcarbamates,
e.g. polyvinyloctadecylcarbammate, the alkyilurethane of
polyvivylalcohols, and the amides of fatty acids and
polyethyleneimine. The anti-adhesive agent is used in
amounts ranging from 5~ to 2Q%, preferably 10~ to 15% by
weight of the overall weight of the components in the anti-
adhe~ive layer.
The anti-adhesive layer is made writable by the
incorporation of a matting agent, in accordance with
conventional techniques. As the matting agent, an inorganic
material may be used in the form of finely divided
particles, such as talc, silica, calcium carbonate, etc., a
high purity silica being preferredfor instance the high
purity ~ilica available under the trademark SYLOYD from
W.R.Grace, U.S.A.. The dulling filler should be used in
amounts ranging from 5% to 25, preferably 10% to 15~, by
weight of the overall dry weight of the anti-adhesive layer
components.
The substrate to be used in the tape according to the
invention is an olefinic homopolymer or copolymer,such a~
polyethylene, polypropylene, or copolymers thereof. The
invention has shown to be specially advantageous with
polypropylene substrates. The substrate may be uni-oriented,
bi-oriented, or unoriented.
When cutting the final product into small rolls, the
tape edges are made easy to cut in the transversal
direction,both manually and through automatic or manual
dispensers, by creating micro-indentations which facilitate
starting of the crosswise cut. The micro-indentations are
formed, in
,
~ ~6~7~
conformity with con~entional techniques, by mean~ of
cutting blades, usually termed l'score cutting".
~ he adhesive layer of the tape of this invention
is ~ormed with adhe~i~e products conventionally
employed with such tapeR, like an adhesive material
includi~g acrylic, polyuretha~e, or polyester
copolymers, or natural or synthe~ic rubbers and na~unal
or ~ynthetlc resins adhesives.
The tape of this invention is prepared by applying
to the polyolefinic substrate the anti adhe~ve layer and
adhesive layer, respectively, preferably in the form
of a solution or disper~ion in ~ui~able solve~t~7
according to conventional techniques, ~nd then
remoYing the solvents by evaporation. ~he a~ti-adhesive
layer of this invention may be applied, ~or example,
in the ~orm of a solution or dispersion in a hgdro-
carbon solvent, such as toluene, by mixing 95q' to 70~ja
pre~erably 85/o to 75a/o, ~f said solvent together with
5~/o to 30a/o~ preferably 15a/~ to 25/o~ o~ the mixture o~ the
anti-adhesive layer component~ 9 with the u~e
of such coating arrang~ents as rotogravure, wire
bar (~eyer bar~, roto~ilkscreening, etc~ The thicknesses
o~ the substrate ~nd of the adhesive and anti_adhesive
writable ~ ayers are uncritical in the inventive tape ,.
25 U~;ually, thiclmes3e~ prefera~ly in the 25 to 40 11m
ra~ge ar~ used ~o~ the ~u~ra~e7 in the
0.4 to 10 1~m ra;~ge for the anti-~dhesive la;srer, arld
in the .. 18 to 32 ~m range for the adhesive
layer.
The re~ulting adhesi~e ~ape ig easil~ ~nwou~d,
, - ' . .
~ ~6 ~7
adheres perfectly to di~ferént surfaces~ become~
perf~ctly transparent on application, may be photo-
copied, i6 specially suitable for heliograp~ic
duplication a~ practiced in the workrooms of engineering
draftsmen, i8 unalterab}e with time, and iB writQble
by ~11 ordinary writing methods, and in particular,
with all types of pencils.
~ he Example which follows iB gi~en by ~ay of ~llu~tra-
tion, so as to make the in~ention more clearly understood~
and i~ ~pt to be con~trued as l~mitlng the scopeo~ ~he ~nventlon.
Exam~
The following compone~ts are mixed together in
a fast mixer of the blade type7 according to known
techniques~ in toluene a3 a sol~ent~ While heating gradu-
ally to 50C, 11 parts by wei.ght (dry) of 25~ polyvi~ylocta-
decylcarbama~e are added to the toluane. O~ce
the product has been homogeni~ed, 35 parts ~y weight
(dry) ~aropal 8652 are added; the mixture is aga~n
homoge~ized, and 40 part3 b~ weight (dry) E~s~man
CP343 and 14 parts by weight (dry) Syloid 276 are slowly
added .
The re~ulting suspe~ion has a solid~ content o~.20%
and c~n be stored a~ roo~ temperature.
The mixture is then coated~, while maintaining it
25 at about 400~ using a coating metl~od of the wire bar
type, to a thick~ess of 12 g/m~ wet, over the untreated
side of a bi-oriented polypropyle~e film having a
thickness of 35 ~ d dried for 20 secon~ at 80~C
on an indu9trial-type coating machine.
3~) The other side o~ the substrate i~ then co~ted
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~iO'774~
-- ~0 --
~ith a sol~ent adhesive compri~ing a butylacryla~e-
acrylonitrile-acrylic acid copolymer in an he~a~e-toluene
sol~ent, the coat i~ dried ~or 50 ~econds at 8DC, and
finally, the product is wound into rolls about Z~000
m long. ~he material can be stored wound ~n a
roll ~or long periods, and is then conYerted into
smaller rolls for consumer's u~e. The tape thus
obtained is easily unwound i8 free of surface ~laws,
can be applied either manually or with auto~atic
s~stems, and retains its properties unaltered with
time.
Specifically~ the tape can receive on it~ back any
type of mar~ing ~ both in i~k and especiall~ pencil~ ~he
marking is stable with time and of the same
inten~ity as on usual writing paper. ~he tape i9
particularly transparent on application, and invisible
on photocopies and, in particular, on blueprints.
