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Patented Nov. 5,
' 2,410,623
Seaver A.‘ Ballard and John A. Perona, Oakland,
Calih, assignors to Shell Development Com
pany, San Francisco, Calii'., a corporation of
. No Drawing. Application June 14, 1943,
Serial No. 490,947
'6 Claims. (Cl. 260-42),‘
vThis invention relates tov rubber, particularly
to synthetic rubber and reclaimed rubber, and’
more particularly to tacki?ers and plasticizers
geneous. Preferred higher ketones are unsatu
rated ketones such as life formed by the croton
aldehyde-type condensation of a lower ketone
with a ketone or an aldehyde according to the
In the past decade there have been developed 5 , process disclosed in U. S. Patent 2,309,650. The
synthetic rubbers with many of the. desirable
process is conducted in the presence of a strong
properties of natural rubber without certain limi
. aqueous solution of an acidic or basic, preferably
tations of the latter. Synthetic rubber now avail
basic,cata1yst, the concentration of which is kept
able can be compounded to compositions of ex"
constant by the continucus removal
cellent vulcanizing properties yielding products 10 substantially
of the water formed as av by-product. The
of high tensile strength, elongation, hardness,
. ketones used as starting materials may be either '*
abrasion resistance and tear resistance. As com;
saturated or unsaturated compounds, illustrative
pared to natural rubber, synthetic rubber may
exhibit remarkable resistance to aging and t0 the
physical and chemical action of water, acids, 15
bases, vegetable ‘oils, animal oils, fats, aliphatic
and aromatic hydrocarbons. Despite these many }
points of advantage and superiority, most of the
examples being acetone, methyl ethyl
methyl propyl ketone, diethyl ketone,
butyl ketone, methyl isobutyl ketone,
vinyl ketone, methyl isopropenyl ketone,
oxide, cyclopentanone'and cyclohexanone. These
may be condensed with themselves by employing
synthetic rubbers have in common one serious
only a single reactant in the reaction mixture, or
defect, i. e. lack of tackiness, a property which 20 with ‘other ketones by employing two or more
is of primary importance in manufacturing op
ketones in the reaction mixture. In addition to
v erations involving compounding, building or ply-v
the ketone or_ ketones, the reaction mixture may
ing-up operations, such as tire construction and
contain one or more aldehydes, suitable examples
the manufacture of belting.
of which are acetaldehyde, propionaldehyde,
An object of the invention is the provision of 25 butyraldehyde, isobutyraldehyde, ethyl ,hexalde
tacki?ers and plasticizers for synthetic rubber.
hyde, acrolein, crotonaldehyde, methacrolein and
A further object is to improve the milling char
ethyl propyl acrolein. Of the various ketones
acteristics of synthetic rubber. A further object
and aldehydes which may be reacted, mesityl
is to facilitate the incorporation of compounding , oxide
as a single reactant for the condensation
ingredients into synthetic rubber. Another ob 80 reaction
is a preferred substance. The products‘
iect is to improve the fabricating properties of
are predominantly unsaturated
synthetic rubber. Another object is to provide
cyclic ketones having at least 12 carbon atoms
new synthetic rubber compositions having prop-1
in the molecule of which those having at least 24
erties superior to any which have been hereto
‘carbon atoms‘ in the molecule are preferred.
fore developed. Another object is to improve the 35 Most of the ketones are believed tov be charac
properties of natural rubber. Other objects are
to accomplish these results with reclaimed rub-I
teri'zed by the conjugated relationship in‘ the
molecule of at least one carbon-to-carbon double
bond with the double bond of the carbonyl group.
These compounds may be de?ned as carbocyclic
ketones of at least 12 carbon atoms containing
ber. Still other objects will be apparent from
' the description given hereinafter.
We have now found, and our invention is based
upon the discovery, that the tackiness and work- '
in the-ring the structure
ability of rubber are substantially improved by
incorporating therewith certain selected ketone
resins. Also in accordance with the invention is
the discovery that the tack of rubber compositions
containing said ketone resins can be even fur
ther increased by treatment with certain agents
selected with regard to the particular rubber in
The ketone resins with which this invention
Smaller amounts of unsaturated cyclic‘ ketones
having 12 and more carbon atoms in the molecule
are formed as secondary products in the‘ con
densation of ketones with themselves, with dis
similar ketones or with aldehydes in the presence
50 of relatively dilute solutions of catalyst. _As an
is concerned can be formed by condensing a -
higher ketone containing at least 12 carbon
atoms in the molecule with an aldehyde in the
, presence of a condensing catalyst and a substance.
- '
illustration, when isophorone is prepared by the
crotonaldehyde-type of condensation of acetone
with itself in the presence of an aqueous solution
of an alkali metal hydroxide at 130° C. or above,
capable of rendering the reaction mixture homo-_ 55 there are formed signi?cant ‘quantities of higher
ferred reactant, formaldehyde. In order that the '
reaction between the ketones and aldehydes be
eilected readily, it is desirable that the reaction
mixture be in a homogeneous state, i. e., that the
reactants and catalyst be in a solution compris
ins a single phase, at least at the start and early
molecular weight compounds. The same or re
lated compounds are formed in thepreparation
‘ ‘of homologues of isophorone, as from methyl
ethyl ketone. Thismethod of preparing iso
phorone and its homologues is described and
_ claimed in the co-pending application of Ballard
‘and Haury, Serial Number 474,060, ?led January ' part of the reaction. To this end, a homogeniz-'
ing solvent is employed in, the reaction mixture.
"28, 1943, now U. S. Patent No. 2,399,976. These
In the absence of.’ a homogenizing solvent, the
higher products are preponderantly unsaturated
cyclic ketones of 12, 15 and more carbon atoms 10 yield of resin is very low. Many solvents are suit~ able for this purpose and the choice of a particu- '
per molecule. The residue boiling above about
lar solvent will depend upon the particular re
240° C. at 20 mm. pressure, from the fractional
actants employed, the catalyst used and the pres
distillation oi; the higher unsaturated cyclic
or absence of water in the mixture. The
ketones obtained as secondary products in the
lower aliphatic alcohols are particularly suitable
manufacture of isophorone by the process just
homogenizing ‘solvents. The amount of these
described is a particularly effective tacki?er.
homogenizing solventsemployed will depend upon
'Another method of forming high unsaturated ‘
the character of the reaction mixture. In gen-.
cyclic ketones consists in condensing isophorone
eral, sumcient homogenizing solvent is used so
to crystalline di-isophorone in the presence of an
the reaction mixture is homogeneous at least
alkali metal hydroxide or alkali metal alcoholate 20 that
?rst heated to effect the reaction.
condensation catalyst. The method is described
homogenizing solvent may serve ‘a two
and claimed in the oo-pendingapplication of Bal
fold purpose in the process. Besidesv rendering
lard and Haury, Serial Number 390,744, filed April
the reaction mixture homogeneous, it may also be
28, 1941. The primary product is a bicyclic un
used to regulate the temperature of the reaction
saturated ketol. As secondary products, are
mixture during the heating thereof since ordi
formed other unsaturated ketones or 12. 15 and
narily the reaction is effected at not overly high
more carbon atoms‘ per molecule, which can be
temperatures. By heating the reaction mixture
separated from the remainder of the reaction
in a vessel ?tted with a re?ux condenser, the tem
mixture used in accordance with the invention.
perature may be made to reach and hold the boil
were again, ‘the residue, boiling above about 240°
ing temperature of the mixture and this may
C. at 20 mm. pressure, from the fractional dis
very well be largely dependent upon the re?uxing
tillation of the higher unsaturated cyclic ketones
temperature of the homogenizing solvent espe
obtained as secondary products in the manufac
cially after the reaction has progressed to a con
ture of di-isophorone by the process just de
siderable extent with substantially no other lower
scribed is a particularly eifective product.
boiling constituents remaining in the mixture.
While the unsaturated higher ketones are most
To e?ect the desired reaction temperatures, in
desirable for use in preparing the resins with
general, between about 50° C. and 150° Cxare em-_
which the invention is concerned, the saturated
ketones prepared by hydrogenation with satura
' Upon completion of the resin-forming con
tion of the double bonds in the unsaturated com 40 densation reactions between the ketones and al
pound, or by conversion of the unsaturated ke
dehydes, the resin may be recovered from the re
tones to saturated alcohols followed by dehydro
action mixture by several suitable methods. A
genation of the carbinol group therein to give a
preferred procedure is to wash the mixture with
saturated ketone are also‘ suitable. The resins
a catalyst solvent such as water so that ‘the mix
prepared from the saturated ketones, however, 45 ture will be substantially freed of the condensing ~
are products of somewhat di?erent character
from those derived from the unsaturated com- .
agent. If desired, however, the catalyst may be
destroyed by neutralization with an appropriate
pounds containing more than one carbon-to-car
acidic or basic substance. The mixture may then
bon double bond in the molecule.
be distilled. ?rst at higher pressures such as at
The ketone resins are formed by reacting the 50 mospheric to remove the homogenizing solvent.
higher ketones referred to with aldehydes. Form
aldehyde is the preferred reactant, but other a1
catalyst solvent, unreacted reactants and low
boiling products, and secondly at reduced pres
dehydes can be used, examples of which are
acetaldehyde, propionaldehyde, butyraldehyde,
isobutyraldehyde, acrolein, orotonaldehyde and
sures to remove higher-boiling products from the
ketone resin. By completing the distillation op
eration at very low pressures of l to 10 mm. of.Hg
benzaldehyde, together with their homologues,
and at temperatures between about 150° C. and
analogues and suitable substitution products.
250° C., but below a temperature at which ap
Besides the free, uncombined aldehydes, polymers
preciable thermal decomposition of the resin oc
of the aldehydes, such as para-formaldehyde,
curs, the resin is obtained in a hard, brittle, de
para-aldehyde and meta-aldehyde, can be used. 60 sirable form. Besides the above-outlined scheme
Preferred catalysts for the reaction are the hy
of recovery of the resin, other methods may be
droxides, oxides and alcoholates of the alkali
employed, if desired, such as fractional precipita
metals, and strong organic bases,»such as the . tion, extraction and the like.
quaternary ammonium bases. Other catalytic
bases are the alkaline earth hydroxides and ox 65
ides. Acidic catalysts include sulfuric acid, hy
drochloric acid; phosphoric acid, tellurlc acid,
tungstic acid and the acid salts, such as sodium
Preparation of the resins are illustrated in the .
following examples: _
Example I
About 17a‘ gm. of 12 carbon atom unsaturated
acid sulfate. The catalysts will ordinarily be em
ployed as suspensions or solutions, preferably the .70 ketones obtainedby the condensation of imesityl
oxide was mixed with 81 gm. of 37% aqueous
latter, in an organic medium or water. The
solution. To this mixture was
higher ketones employed as starting materials in
making the'resins are substantially insoluble in ~ added approximately 5 gm. of 30% aqueous so
dium hydroxide solution and about 95 gm. of
water and in aqueous solutions of the aldehydes
such as an aqueous solution of the most pre 75 methanol which rendered the mixture homoge
The mixture was contained .in a ?ask ,
?tted with a re?ux condenser and upon heating
the contents of the ?ask, the temperature of the
mixture remained at about 76° C. owing to the
107 gm. of light-colored, hard, brittle resin hav
ing a color or G on the resin color scale.
Example V
re?uxing of the methanol therein. The mixture 5 ' A mixture containing about 178 gm. of C1: un
remained homogeneous for about 1/2 hour after
saturated ketones from condensation of mesityl
which two liquid phases separated. The heating
oxide. 30 gm. of formaldehyde in the form of_a
was continued over a total period of about 3
737% aqueous solution, 5% of 96% sulfuric acid,
hours. - The mixture was. then cooled, brine added
and su?icient methanol to homogenize the mix
and the resin phase extracted with ether. The 10 ture was heated at re?uxing temperature for ap-_
ether was dried with anhydrous sodium sulphate
proximately three hours. The resin which was ,
and the ether distilled therefrom. The remain
recovered was dark red in color.
ing oil was then distilled in vacuo and after re
Example VI
moval of the distilla-ble material, about 106 gm.
of a reddish, brittle, transparent resin was ob- 15
About 368 gm. of saturatedketones containing '
tained. ' This resin had a color correspondingto
E on the resin color scale and was soluble in alco
12 carbon atoms per molecule obtained by con
content and changed it to a form which was in
heated 'at a re?uxing temperature oi’ about 73° C.
for four hours. During the heating the reaction
densing mesityl oxide and saturating the C1: con
hols, ketones, esters, aromatic hydrocarbons and
densation products with hydrogen were mixed
para?lnic hydrocarbons. A cryoscopic deter
with about 162 gm. of 37 %. aqueous formaldehyde
mination in glacial acetic acid indicated the mo- 20 solution and 400 gm. oi.’ methanol. To this mix
lecular weight was about 530. Exposure of the
ture was added about 9 gm. of 30% aqueous so
resin to the action of air increased its oxygen
dium hydroxide solution. The mixture was then
soluble in para?lnic hydrocarbons.
The presence of the homogenizer in the reac- 25 mixture became , yellowish in color and turbid.
tion mixture is essential to obtaining a practical
About 200 gm. of methanol were distilled from the
rate oi.’ resin formation. With a reaction mix
mixture in the last one and a half hours of heat
ture containing‘ the same amount of identical re
ing. The resin was recovered by distillation in
actants, but in the absence of the homogenizer,
vacuo. Approximately 60 gm. was obtained which
methyl alcohol, which was treated under the same 30 was a red, brittle, tacky solid.
conditions as in the preceding example, the quan
Example ‘VII
tity of resin amounted to less than one, gram.
A mixture was prepared containing ‘about 178
, Example II
gm. of C1: unsaturated ketones from condensation '
A mixture containing about 268 gm. of unsat- 3 5 of mesityl oxide, .200 gm. of methanol, and 5 gm.
urated ketones with 18 carbon atoms per molecule .
of 30% ' aqueous sodium hydroxide solution. To
an aqueous solution was prepared. To this mix
ture was added about 1'70 gm. of methanol to
make it homogeneous and the mixture was then ,
heated for approximately three hours at a tem
perature of 65:5_° C. The resin formed was re- 45
covered in a- similar manner to that described in
Example I and amounted to about 202 gm. The
resin was a light red brittle solid which was
perature at about 15° C. The entire mixture was '
prepared by condensing mesityl oxide, about 83 . this mixture there was added about 44 gm. of
acetaldehyde in 100 gm. of methanol in the
gm. of 36% aqueous formaldehyde solution, and
of 15_ minutes while maintaining the tem
about 0.5% of sodium'yhydroxide in the form of 40
slightly darker in color than that obtalned'ac
cording to the method of Example I.
Example III
Approximately 169
of C24 unsaturated ke
tones from condensation of mesityl oxide, about
then heated for about 3 hours at a re?uxing tem
perature of about 69° C. The product was water
washed and distilled. .The resin obtained
amounted to about 38 gm. and was a dark red,
brittle solid with the following solubility characi
' Hot
P and V thinner. _
"""" "
o ....... _Carbon tetrachloride .... _.
Normal butyl acstatm.
Partl? soluble.--._ Soluble.
1R?' s 1ubla.
s u e--olgubley_ ________ -_ gglgubley. 0
Diethyl ether ________________ _-do __________ _.
42 gm. of 36% aqueous formaldehyde ~solution, 65
and 0.5% sodium hydroxide as aqueous solution
Example VIII
together with about 325 gm. oi.’ methanol were
heated at a temperature of 65i5° C. for three
Approximately 1'78 gm. of C12 unsaturated ke
hours. About 169 gm. of light red brittle resin
’ tones from condensation of mesityl oxide, 106 gm.
was recovered from the reaction mixture which so of benzaldehyde,.4 gm. of 30% aqueous sodium
was slightly darker in color than that described
hydroxide solution, and 150 gm. of methanol were
in Example II.
heated at about 72° C. for 5 hours. The reaction
Example IV
product was washed with water and distilled un
der subatmospheric pressure. The distillable ma
Tetra ethyl ammonium hydroxide was tested as (“'5v terial at about 215° C. under 1 mm. pressure was
a polymerization catalyst by heating a mixture
removed and about 11 gm'. of dark red resin re
consisting of about 178 gm. of the C12 unsaturated
‘mained. This resin was soluble in P and ‘V thin
ketones described in Example I, 61 gm. of 37%
ner, ketones, alcohols higher than methanol and
aqueous formaldehyde solution, 120 gm. of meth
slightly soluble in methanol.
anol, and 20 gm. of 10% aqueous tetraethyl am- 70
The process applies not only to individual ke~
monium hydroxide. The mixture was re?uxed at
tones but also to mixtures of ketones, particular
about 78° C. for three. hours. The product was
1y to the high boiling residues from the manufac
washed with water and distilled in vacuo. After
ture of isophorone and di-isophorone, and to the
removal of unreacted unsaturated ketones‘ and
products of the complete or partial hydrogena
lower-boiling constituents. there remained about 75 tion thereof. Each and all of these products of
the reaction of an aldehyde with cyclic ketones
having at least 12 carbon atoms in the molecule
are capable of signi?cantly increasing the tack of
synthetic and reclaimed rubber.
The ketone resins can; if desired, be subjected
to treatment in any or several di?erent ways.
The properties oi the resins can be modi?ed. for
instance, by oxidation, hydrogenation or halogen
operation hastens the breakdown of the rubber, '
reduces the heat build-up,;and otherwise facili
tates the operation by rendering the stock less
nervy and more plastic. According to the wishes
of the operatorand the idiosyncrasies of the par
ticular composition, the addition may be made at
any time from the commencement to the comple
tion of milling. Where compounding on a roll
mill is followed by re?ning in a special re?ning
The invention applies to substantially'all syn 10 mill, the addition of all or part‘ of the tacki?er
may be made in the second operation. If desired,
thetic rubbers, natural rubber, and reclaimed
mastication and compounding can easily be
rubber. Examples of synthetics are polymers of
e?ected in a Banbury mixer.
butadiene, the pentadienes, the hexadienes, the
The raw synthetic is sometimes supplied in the
heptadienes, the octadienes and the nonadienes,
polychloroprene _(“GR-M”), polyisobutylene, 15 iorm‘of an emulsion in a liquid, usually water. in
which form it closely resembles the latex of natu
polyvinyl chloride, and copolymers of any or all
ral rubber. This form is usually produced by ?rst
ot'these materials with one another and with
emulsifying-the monomeric material and subse
small amounts of other polymerizable compounds,
quently polymerizing, in which casethe tacki?er
as well as to mixtures ‘of the various polymers. _
Examples of said other polymerizable compounds 20 is conveniently added to‘ the emulsion of previ
are acrylonitrile, methacrylonitrile, styrene,
ously prepared polymer. In some cases it may be
methyl methacrylate and methyl vinyl ketone,‘
desirable to add the tacki?er either to the dis
persed phase or to the dispersing phase prior to
An important class consists of co-polymers of bu
or during the course of polymerization. Other
. tadiene and acrylonitrile, as exempli?ed by “Hy-‘
car 0. R.,” "Perbunan” and “Perbunan Extra." 25 methods of incorporating the tacki?er with the
The percentage of acrylonitrile in the co-poly
stock will occur to those skilled in the art.
Other materials in addition to tackl?ers will
mers is ordinarily between about 10% and about
usually be compounded with synthetic rubber and
40% by weight or the total, although not neces
sarily limltedto this range. Also important are
reclaimed rubber. While the tacki?ers of the
butadienewstyrene co-polymers, such as "Buna S," 30 present invention exhibit a plasticizing, as well as .
“Buna SS" and “GR-S.” The tacki?ers of this
invention are of maximum potency when used in
conjunction with butadiene-acrylonitrile co-poly
tackifying, action, it may be desirable also to use
certain additional plasticizers, of which the fol
lowing are common examples: dibutyl phthalate,
mers. Another important co-polymer type is that
dioctyl phthalate, tricresyl phosphate, triacetin,
of isobutylene with a small amount of butadiene, 35 tetralin, soft coal tar, cumar resins, soft factice,
known as "butyl” rubber, or “GR-I.” The inven
wool grease, stearic acid, lauric acid, and waxes.
Not more than very small amounts of the last
tion applies also ,to natural rubber; to composi
tions comprising both synthetic rubber and re
four ingredients should be used.
claimed rubber; to compositions comprising either
One or more anti-oxidants will ordinarily be
synthetic rubber or reclaimed rubber; and to mix 40 present, the most common one being phenyl beta
tures of the three types of rubber, synthetic, re
naphthyl amine. Illustrative of other anti-oxi
claimed and natural.
The invention is not to be considered limited to I
dants useful in synthetic and reclaimed rubber
are p-hydroxy diphenyl, hydroquinone, p-aminoq
the examples of synthetic rubber listed above
phenol, p,p'-diamino-diphehylmethane,' 2,4'-n
since it appears applicable to all synthetic sub 45 toluylene diamine, ' diphenylamine, o-ditolyla
stances having the approximate physical'prop
erties of natural rubber, The term'“synthetic
rubber” as used in this application is substan
tially equivalent to “elastomer,” as suggested by
H. L. Fisher, Ind._Eng. Chem. 31, 941 (1939), or
mine, p-ditolylamine, phenyl a-naphthyl amine,
phenyl B-naphthylnitroso amine, symmetrical di
p-naphthyl-p-phenylene diamine, diphenyl dia
rnino ethane and 2,4-diaminocliphenylamine.
As with natural'rubber, carbon black is made
an ingredient of synthetic rubber compositions
because it acts not only as a ?ller and sti?ener
“rubber’'__ is used in a generic sense to include syn
but also, and. more important, as an agent to in
thetic, reclaimed and natural rubber.
crease the tensile strength. With some syn
The amount of tacki?er used is subject to wide
variation according to the type of synthetic rub 55 thetics, however, notably polychloroprene, no
such increase obtains. The choice of type of
ber or reclaimed rubber involved, the kind and
carbon black will depend upon many factors, amount of other modi?ers, the conditions of mill
principally the nature of the synthetic and the
ing, re?ning, storage and vulcanization, and the
purpose of the composition. : Soft and hard chan
intended use of the product. The usual range is
from about 2 parts to about 25 parts of tacki?er 60 nel black, thermal decomposition black and semi
reinforcing furnace black are common types.
per 100 parts 01’ rubber. With less than the
The properties of the composition may be modi
smaller amount the action is ordinarily insigni?
?ed with other pigments, such as iron oxide, tita- ‘
cant. More than the larger amount may, in some
,nium dioxide, barytes, zinc. oxide, hydrated alu
instances, impair the tensile strength and reduce
the rate of vulcanization. Nevertheless in many 65 mina, lithopone, and whiting.
Most synthetic rubbers can be vulcanized by
cases excellent results are obtained by the use of
procedures similar to those used for natural ‘rub
as high as 50 parts of ketone resins per 100 parts
to “synthetic elastomer.” The unquali?ed term
of rubber.
Raw synthetic rubber is generally supplied in
ber. Among the exceptions are the polymeric
compounds which do not possess unsaturated car
-a massive state, free from other than minor quan 70 bon-to-carbon linkages, e.‘ g. polymers vofisobu
titles 01’ solvents and other diluents. The tacki ' tone and vinyl chloride, and are considered un
vulcanizable. It. has been noted, however, that
?ers will usually be incorporated with the raw
the addition of a substantial amount. usually
material in Banbury mixer or on an open mill,
from about 10% to about 50%, of the higher unusing tight- t, cold rolls. The addition of at
least a portiontoi/t’he tacki?er early in the milling 76 saturated cyclic ketones of the invention to such
polymers 'results in compositions which, when
agents selected with regard to the particular rub
ber involved. Satisfactory tack-increasing agents
are those which exhibit in?nite solubility in the
ketone resin tacki?ers, which boil between about
50° C. and about 200° C. at atmospheric pressure,
subjected- to the‘ usual vulcanization conditions,
undergo certain physical changes resembling
those occurring with vcertain other compositions
on vulcanization. Some of the synthetics can be
vulcanized without the addition of vulcanizing
agents, although with most of these vulcaniza
tion is promoted by their use. Sulfur is the com
mon vulcanizing agent. Other agents used, gen
and which are weak solvents or vigorous swelling
agents for the rubber or synthetic.
For compositions of co-polymers of butadiene
and acrylonitrile containing ketone resin tacki
erally with less success, are sulfur-containing 10 fiers, suitable tack-increasing agents are all
compounds, such as sulfur dioxide, hydrogen sul
phatic, including alicyclic, carbonylic compounds‘
?de and sulfur thiocyanate; oxygen and oxygen
of 3 to about 10 carbon atoms boiling within the
yielding compounds, such as ozone, organic and
stated range. Representative examples are ace
inorganic peroxides; selenium, halogens and hal
tone,- methyl ethyl ketone, methyl n-propyl ke
ogen-containing' compounds, and; nitrogen-con 15 tone, methyl isopropyl ketone, methyl n-butyl
taining compounds, such as the nitrobenzenes.
ketone, methyl isobutyl ketone, methyl t-butyl
With polychloroprene metallic oxides, principally
ketone,- mesityl oxide, diacetyl and isophorone.
magnesium oxide, ‘zinc oxide and litharge, act as
Methyl ethyl ketone is preferred.
vulcanization agents.
For compositions of‘ co-polymers of butadiene '
In addition to vulcanization agents, vulcaniza
tion accelerators are added. Illustrative ‘exam
ples of accelerators are tetramethyl thiuram di
sul?de, zinc dibutyl di-thiocarbamate. I tetra
and styrene containing ketone resin tacki?ers,
the best tack-increasing agents are normally liq
uid aromatic and aliphatic hydrocarbons and
halogenated hydrocarbons boiling between about
methyl thiuram monosuliide. dipentamethylene
50° C. and 200° C. ' Among the suitable com
thiuram tetrasul?de, mercapto benz'o thiazole, 25 pounds are carbon tetrachloride, chloroform, ben
aldehyde - ammonia,
diphenylguanidine, diphenylthiourea. benzo thi
azyl disul?de, piperidinium pentamethylene-di-U -
zene, toluene, monochlorobenzene and mono
chlorotoluene. Benzene and monochlorobenzene
are preferred.
thiocarbamate, di-o-tolylguanidine, triphenyl
The tack-increasing agent can be added to the
guanidine and lead dimethyldithiocarbamate. 80 stock prior to or during compounding, or to the
Some of these are considerably more effective
compounded material prior to shaping. As an
than others. With polychloroprene, sulfur and
example may be mentioned the incorporation of
catechol act as accelerators. Zinc oxide is usu
a tack-increasing agent and volatile solvent with
ally added, its action ‘being that of an inorganic synthetic rubber in such proportions as to form
accelerator or an activator of vulcanization ac 85 ‘an adhesive paste or liquid. In most cases, how
ever, the agent will be used to treat the surfaces
The order of addition of the various ingredi
of a shaped or fabricated structure.
. '
ents may be varied in any way in accordance
The structure can be dipped in undiluted tack
with the wishes of the operator as directed by
increasing agent, removed, freed from excess liq- '
his experience in preparing the compositions. 40 uid and used in the desired manner. In a modi
'The constituents of the compositions, and the
?ed procedure the structure is immersed in a
order and method of compounding are factors
solution of the agent in a solvent therefor which
which do not form a part of the present inven
is inert to, or has a swelling action upon, the
tion, except that synthetic, natural or reclaimed
structure. In another procedure the immersion
rubber and the indicated ketones or derivatives 45 bath comprises a dispersion of the agent in an
thereof are necessarily involved.
organic or inorganic liquid. Another method is
The compounded compositions are subject to
> to lightly wash the surfaces of the solid structure
numerous shaping operations known in the art.
with the agent, allow the ketone to partially or
Sheets can be formed .by calendering on heated
completely evaporate, and'then immediately to
rolls or by casting from solutions. Sheets, rods, 50. bring the surfaces into contact with the surfaces
' tubes and coatings can be formed by continuous
of the same or other material, which latter sur
or discontinuous extrusion.~ Articles of substan
faces, preferably but not necessarily, have been
tially any shape can be made by operations using
also Just previously subjected to treatment with
the agent.
open or closed molds. The compositions can be
applied to ?brous material, such as fabric, by 55. Another'method is to use a mixture of tack
calendering or by impregnation with a suitable
increasing agent, rubber composition, and a sub
emulsion. These shaping operations and many _ stance which is a solvent for both said agent and
others are facilitated by the presence of one or
said composition. The mixture is applied to the
~ more of the tacki?ers of the present invention in
surfaces of the structure, whichv are then pressed
the compositions.
60 against similar or other surfaces, and preferably
Shaped structures of synthetic rubber, and
vulcanized under the in?uence of heat.
structureless material as well, are often required
The tack-increasing agents of the present in
to undergo additional fabrication, a prominent
vention are unique in their action. No other
illustration being the laminating, or plying-up, . agents'which have been tested increase to a com
of tire casings. Here are involved the cohesion 65 parable degree the tack of compositions contain
of the synthetic material to itself and its adhe- ,
ing the higher ketone resins. Conversely, the
sion to different material, in addition to other‘
agents are substantially ineffective when used
factors contributing to workability. Ease of fab
V with compositions which contain no tacki?ers, or
_ rication and the quality of the resulting p’roduct '
which contain one or more of the so-called tacki
are increased by the presence of the tacki?ers 70 ?ers heretofore available.
herein described.
It has been discovered that the tack of rubber
compositions containing the ketone resins with
which the invention is concerned can be even '
The vulcanization of vulcanizable synthetic.
rubber takes place under conditions similar. to
those used with natural rubber. Likewise, the
same equipment can be employed. Polymers
further increased by treatment with certain 75 which do not contain unsaturated carbon-to
carbon bonds are considered unvulcanizable. In
substantially all cases vulcanization of composi
tions containing the requisite componentsoccurs
slowly at room temperature, and is accelerated
by increase in temperature. The upper limit of
the temperature of vulcanization is ordinarily de
termined only by the degradation or decomposi
tion of the material. or by the volatility of one
or more of ‘its constituents.
whereas with the strips containing the ketone
resin tackiness was greatly increased.
Example X
A ketone resin formed by the condensation of
formaldehyde with a Cl: unsaturated ketone
formed by the condensation of mesityl oxide with
itself in accordance with the process disclosed‘in
'U. S. Patent 2,309,650 was compounded with
10 "Buna 8” under the following formula:
“Buna S”
Ketone resin
The synthetic, natural and reclaimed rubber
compositions of the present invention can be used
for all of the purposes to which other such com-_
positions are applied. Examples which come
Phenyl p-naphthylamine _________ __r_____
readily to mind are balloon coverings. umbrellas,
raincoats, table covers, shower curtains and ear 15 Benzothiazyl disul?de______________;..___ 1.25
Zinc oxide
ment bags, for which cloth impregnated with
Stearic acid
synthetic rubber has been found highly suitable;
Channel black. ______________________ __ 50
electrical insulation; friction tape, hose for the
handling of petroleum products and of paints;
lining and exterior coating in self-sealing gaso 20 - The tackiness of the composition was consider
line tanks: gaskets; belts for conveying and for
ably greater than that of otherwise similar ma
the transmission of power; vibration dampeners.
terial containing conventional plasticizers in lieu
for which several synthetics are ideal by virtue of
of the ketone resin. The tackiness of the com
their high absorption of energy; printers rolls,
printers blankets and engraving plates; shoe soles 25
and heels; aprons; gloves; gas masks and cloth
~ing resistant to the penetration of poisonous
gases. ‘The most prominent example is the use
of synthetics in automobile tire tubes and tire
Example IX
position was materially increased by washing with
benzene. whereas the washing was substantially
ineffective on the tackiness of the conventional
Example XI
The following composition was ‘compounded on
cold rolls in the usual manner, the resin used
being the condensation product of formaldehyde
A co-polymer of butadiene and acrylonitrile
with a mixture of C12 and C15 unsaturated ketones
was compounded with a resin formed by after
obtained as a by-product in the manufacture of
hydrogenating the condensation product of form 35 isophorone in accordance with U. S. Patent No.
aldehyde with a mixture of C1: and C15 unsatu
rated ketones obtained as a by-product in the
manufacture of isophorone in accordance with
“Chemigum IV” ______________________ .._ 100
U. S. Patent No. 2,399,976. The following master
Carbon black
40 Ketone resLn
vformula was used:
"Hycar O. R.".._______________-_..__..____ 100
Phenyl s-naphthylamine ______________ __
Benzothiazyl disul?de _________________ __
Zinc oxide
15 parts of the composition were dissolved in
100 parts of a solvent consisting of 90 parts
benzene and 10 parts methyl ethyl ketone. The
Carbon black
surfaces of strips of the composition (not con
Stearic acid
taining said solvent) were painted with the mix
1.25 50 ture. The surfaces were placed in mutual con
tact and subjected to vulcanizing condition under
Compounding was effected on close-set milling ’
pressure. The bond so formed was of such
rolls cooled with water at 10° C. to 20° C. The
strength that the strips could not be separated
stock was ?rst masticated for several minutes,
Ketone resins ________________________ __ .25
zinc nxlde
without tearing.
following which the ingredients were added one '
at a time in the order given. The material was 55
cut and folded on the mill in a standard manner.
After compounding. the material was stored for
several hours under room conditions, and sub
sequently remilled. On calender rolls sheets ap
proximately 0.01" thick were formed.
Strips cut from the sheets were pressed to;
gether. Considerable tackiness was evidenced
when the strips were subsequently separated.
Strips of a similar composition containing di
butyl sebacate in place of the ketone resin were
substantially without tack. The same result was
obtained with compositions containing a num
ber of other common plasticizers, including dii
‘ butyl phthalate, rosin and soft coal tar.
we claim as our invention:
1. A tacky composition of matter comprising
100 parts by weight of a rubber-like polymer of
a diene hydrocarbon having admixed therewith
2 to 50 parts by weight of a resinous product
obtained by condensing a single aldehyde in the
presence of a condensation catalyst with a ‘cro
~tonaldehyde-type of auto-condensation product
of a. lower aliphatic ketone of 3 to 6 carbon atoms,
7 which auto-condensation product contains at
least 12 carbon atoms. '
2. A tacky composition of matter comprising
100 parts by weight of a rubber-like polymer. of
a diene hydrocarbon having admixed therewith
2 to 50 parts by weight of a resinous product
The surfaces of 8.11 the strips were washed 70 obtained by condensing a single aliphatic alde- :
lightly, with methyl ethyl ketone, allowed to dry - hyde in the-presence of a basic condensation
catalyst with a crotonaldehyde-type of auto-con
for about 2 minutes and then again subjected
densation product of acetone, which auto-con
to the tackiness test. In the cases of the com- _
densation product contains at least 12 carbon
positions containing ordinary plasticizers, the in
crease in tacklness was slight or negligible, 75 atoms. ‘
3. A tacky composition of matter comprising ' ' 100 parts by weight of a rubber-like copolymer
100 parts by weight of a rubber-like copolymer
of butadiene‘ and acrylonitrile having admixed
of butadiene and acrylonitrile having admii‘zed
therewith 2 to 25 parts by weight of resinous
therewith 2 to, 50 parts by weight of resinous
product obtained by condensing formaldehyde
product obtained by condensing formaldehyde as
the sole aldehyde in the‘ presence of a condensa
tion catalyst with the crotonaldehyde-type of
‘ auto-condensation product of a lower aliphatic
ketone of 3 to Gcarbon atoms, which auto-con
densation product contains at least 12- carbon 10
as the sole aldehyde in the presence of a con- -
densation catalyst with the crotonaldehyde-type
of auto-condensation product of mesityl oxide,
which auto-condensation product contains 18
carbon atoms.
g‘ I
6. A tacky composition of matter comprising
100 parts by weight of a rubber-like copolymer
of butadiene and styrene having admixed there
with 2 to 50 parts by weight of resinous product
‘g 4. YA tacky composition of matter comprising
100 parts by weight of a rubber-like copolymer
of butadiene- and acrylonitrile having admixed
obtained by condensing formaldehyde as the sole '
therewith 2 to 25 parts by weight or resinous 15 aldehyde in the presence of a condensation cat
product obtained by condensing formaldehyde
alyst with the crotonaldehyde¢type of auto-con
as the sole aldehyde in the presence of a basic
densation product of a lower aliphatic ketone of
condensation catalyst with the crotonaldehyde
3 to 6 carbon atoms, which auto-condensation
type of auto-condensation product of acetone,
product cmtains at least 12 carbon atoms.
which auto-condensation product contains at 20
least 12 carbon atoms.
v5:11 tacky composition of matter comprising
A. A.
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