IMPROVEMENT CONCERNING OF THE ADHESIVE COMPOSITIONS SENSITIVE TO THE PRESSURE

the present invention relates to the compositions perfectiornements noerrant adiré vas and if more particulièrément to the pressure-sensitive adhesive compositions comprising a mixture of rubber compounds and an aromatic hydrocarbon resin.

Typically, the pressure-sensitive adhesive compositions, are considered as satisfactory, when they have a own balance between the stickiness, for the the adhé3ive , a bonding strength and weather resistance, the resinous materials which serve as tackifying compounds and the stickiness rubbers must be compatible with and soluble in solvents.

It has proposed for this purpose the compositions adbéeives pressure sensitive, which are usually used as coating adhesive on the tapes, the paper sheets, tissues and other reinforcing materials, which are blends of natural rubber and/or synthetic rubber with a terpene resistance does. The resin is a ct-pinene, or an E-pinene taken mixtures thereof, are present and dar. the. e s refined pine resin. Oes natural substances, , however, are limited as to source, and their resources are increasingly rare, leading to significant fluctuations in price.

Are also known as a tackifier for compositiens pressure-sensitive adhesive, rosin esters, of aliphatic hydrecarbures coumaroneixidène and resins. These resins, however other 3ont lower. terpene resins with respect to the balance of forces of cohesion, the force of adhesion, the stickiness and other important properties, and further 3ont little compatible with rubbers, or hardly soluble in solvents.

the present invention can provides â. the pressure sensitive adhesive compositions containing the synthetic and natural rubbers in combination with aromatic hydrocarbon resins, which is less expensive, available in larger quantities, qualities and have comparable or even better than the terpene resins.

the present invention provides a 'pressure-sensitive adhesive composition, which comprises a rubber compound including ccpclymères or styrene-butadiene rubber mixtures essentially comprising copolymers of styrene and butadiene, combinaisonavec in a resin compound consisting of an aromatic hydrocarbon resin, resulting' the polymerization of a petroleum fraction heat-treated at temperatures between -30°C +60°C and, in the presence of a catalyst of Rriedel - Grafts added in amounts of 0.01 to 5 % by weight to this fraction, said fraction having a boiling point of between 140 and 220° G, and having a content of conjugated diolefin of 0.7 C/O by weight or less, a ratio by diolefin content, conjugated 3 % or less, a total content of indene or its alkylated derivatives of 2% by weight or less and a content ratio d¹ indene of 8% or less..

The holding rubber compound, as used according to the present invention includes styrene butadiene copolymer rubber and commonly called SBR rubber mixtures, consisting essentially of SBR. Illustrative compounds of these rubbers are cold SBR type rubbers, rubbers or hot SBR type, préparésjar a polymerisation method by emulsification, and copolymers of statistical type rubbers or blocks of the SBR type prepared by a solution polymerization. SBR The various polymers, may be mixed with other types of rubber, such as for example natural rubber, isoprene rubber, butyl rubber, polyisobutylene, butadiene, ethylene-propylene rubber, rubber. type ethylene propylene diene, ccoutchouc of the chloroprene type, nitrile rubber, etc ϋ ℮ ε preferred rubbers from those mentioned, are natural rubber and isoprene rubber.

They can be used in an amount of 0 to 100% parts by weight, and preferably between 0 and 80 parts by weight and more preferably between 0 and 60 parts by weight per 100 parts by weight of SBR.

The term resin compound, includes aromatic hydrocarbon resins resulting from the polymerization of a fraction, heat treated oil having a boiling point of between 140 and 220° G.

Typically, petroleum hydrocarbon resins are prepared by polymerization of oil fractions oil normally liquid thermally cracked, and have boiling points nntr ? 20® and 280 0, antrum 2Q and 170 °C between 140 and 280 and^e C. when the petroleum fraction boiling in the range of between 20° and 140 °C G is used for the polymerization, the resulting resin is non-aromatic that is àdirè will comprise no aromatic ring. Because such fractions contain large amounts of conjugated diolefins, and of non-conjugated diolefins, the resin has a high degree of unsaturation, and thereby, strength is very low weather. With the use of fractiorPpétrolières with a boiling point range between 140 and 280° G, the resulting resin, is aromatic, but not yet- sufdsamment stable in terms of weather resistance.

Much work of the different characteristic properties of the different compounds, cuts of starting, has been used to indicate that it is possible to obtain a resin to provide stickiness satisfying, er by an accurate separation of certain composed selected from the starting oil.

The resin compound in the pressure-sensitive adhesive composition according to the present invention, is an aromatic hydrocarbon resin, prepared from petroleum fractions stock from which the boiling point is between 140 and 220° 0, and containing unsaturated compounds which are substantially the styrene and its derivatives, and indene and its derivatives. The initial material is set so as to satisfy a condition such that the content of conjugated diolefins, is equal to or less than 0.7 % by weight, that the content ratio of conjugated diolefins is equal to or smaller than 3 % by weight, that the total content indene, and alkyl derivatives thereof or 2 % by weight or less and that the indene rate content is equal to or less than 8 % by weight. The starting material is subjected to a polymerizable by the presence of a Friedel-Crafts catalyst. The catalyst is removed, and the unreacted petroleum fractions and low molecular weight polymers, are removed by evaporation or distillation, resulting in a hydrocarbon aromatic résinq having the desired properties.

The starting material to the resins used according to

the present invention, is a heat-treated oil fxaction with a boiling point range between 140 e " 220 °C, which is present in the intermediate product obtained when preparing ethylene, propylene, butene, and butadiene.

thermal cracking such as for example to the jar cracking Bath of petroleum fractions such as naphtha, and naphtha fractions of light oil.

The results of 1' analysis chromatograph! that performed on the petroleum fractions whose boiling point is in the range mentioned above, as shown in Table I according to.

TABLE 1

COMPOSED IN The OIL GRADUEE LA FRACTION 140-220°C in

A Compound

Illuminating point-

bullition

(760 mm Hg

abs.)

Styrene-

Allylbenzène -15-

dc-methyl styrene

S-Methylstyrene

p-vinyl toluene--■ ■--

m-vinyltoluene

o-vinyltoluene---

Indene

Homologs of the -16-methylindene

Homologs diméthylindène of the and

ethylindene--the

Xylene (isomers-o-, m-, and p-),

Ethylbenzène Isopropylbenzene -

Ethyltoluène (isomers o-, m-, and p-) n-propylbenzene--.

Trimethylbenzene (1, 3, 5-, 1, 2, 4-,

isomers.

and/1, 2, 3-; r

Indane. -

Homologs methylindan of the

Homologs dimethyl and ethyl-

indane-

Naphtalene-~

Dicyclopentadiene (1)--

Non-detected A compound (2)

Content (% by weight)

Note (1); a portion had the entire dicyclopentacLiène in cae cerrains can be depolymerized in cyclopentadiene.

v. 2): a portion of the non-detected, contains co-dimeric cyoiopentadiène -meq thylcyclopentadiène , and of the dimers méthylcyclopeniadiène , Some or all thereof, can be depolymerized in some cases, to heat, in cyclopentadiene and methylcyclopentadiene. It is possible to analyze these monomers, by chromatography.

gas phase.

all of the styrene and its derivatives, a derivative thereof, is considered as the polymerizable compound.

In the case wherein there is produced the cyclopentadiene and methylcyclopentadiene, by heating, contained in the starting oil as described in the notes (1) and (2) of Table I, these monomers are also believed polymerizable compounds.

In order to produce a hydrocarbon resin, suitable for the purposes of the present invention, it is essential that a fraction of petroleum oil heat-treated with a boiling point range between 140 and 220° distilled G is accurately, particular to obtain a fraction that satisfies the following conditions, the first fraction is called a conventional manner, as "oil c; starting aquée " and the last fraction is "the starting fraction".

(a) total content of cyclopentadiene The eet in methylcyclopentadiene, i.e. the diolefin content conjuguéedans the starting fractions separated from the cracked oil starting, is adjusted to 0.7 % by weight and the content ratio of conjugated diolefin defined by the following equation (1) is adjusted to be equal to or less than 5 % • Rate conjugated diolefin content (% )

Content conjugated diolefin in the er.

jn starting fraction weight)

Sand in j The polymer compound._has fraction

starting (% by weight)

x 100^r 1)

" V'¹

! .a total content of indene and alkyl derivatives thereof in the starting fraction is adjusted to be equal to a value of 2% by weight or less and the content ratio of indene defined by the following equation (2), is adjusted to be equal to or less than 8 %,

Indene Rate content (%)

Indene content and alkyl derivatives thereof in the starting fraction (% by weight)-100-x (2) polymerizable Compounds in the fraction of

starting (% by weight)

Each compound of the cracked oil starting, of the starting fraction, is analyzed by gas chromatography under the following conditions:

(1) styrene, the ailylbenzène , the 1, 3, 5- triméthyIbenzène

and O- ëthyltoluène , are analyzed 100 °C with a flow of helium ^ of 60 cm/min, using a colony of 3 meters long, filled with the "Celite" (prepared by Johns-Manville Corp) containing 20 % by weight fat " Apiezon L" prepared by Associated Electrical Industries Ltd.).

(2) Other compounds, than those indicated in the no. 1, are analyzed to 125 °C with a stream of helium at a rate of 60^ crn /min using a column like, filled with "Celite" containing 20% by weight of polyethylene glycol 4000.

All styrene and alkylated derivatives thereof ., in indene, and alkyl derivatives thereof, in " yciopentadiène methylcyclopentadiene and analyzed as above is considered as the polymerizable component.

In order to sever the starting fraction, from the cracked oil starting, is conventional, and may use any suitable method such as, for example, distillation at atmospheric pressure, the vacuum distillarion and the extractive distillation.

. As described above, one of the conditions required in, the preparation of the starting fraction from ' zero starting cracked, is that the total content of cyclopentadiene and méttiylcyclcpentadiène , and in particular the concentration of conjugated diolefin, be maintained at a value equal to or less than 0.7 % by weight and that the ratio by conjugated diolefin content is equal to or less than 3%. This condition can be reached conveniently, using a distillate :: be of 1' cracked oil start or the fraction which contains the total te ntracto recuise in indene is in indene alkylated, . or the ratio taring. :-: i^: nv; it-the isiumf at sisters the method selectively the conjugated diolefins. This is facilitated by the fact that the boiling points of the cyclopentadiene and methyl cyclopentadiene are respectively 42 °C and 70 °C, which are lower, the boiling point of initial starting cracked oil.

If ΐ ℮ β conjugated diolefins, are in the form of dimers Diels- Àlder , starting in the cracked oil, can be used commonly, distillation at atmospheric pressure to obtain values snugly fitting-containing indene and the total content ratio of indene, distillation in which, the dimers of conjugated diolefins can be depolymerized into conjugated diolefins, which may be removed then, starting from the fractions by distillation.

However, if such dimers of conjugated diolefins, are only present in small amounts in the feed fraction, it is not always necessary, removing, because these dimers, compared to conjugated diolefins, are much less harmful to the resulting resins, in strength to weather and heat.

In order to satisfy the second requirement, i.e. that the total content of indene and alkyl indene, is equal to or less than 2% by weight and that the content ratio of indene is 8% or less, the cracked oil can be distilled conveniently, to remove the diolefins

-conjugated, the distillate is subjected to a subsequent accurate fractionation. Because. .ue O-vinyltoluene and indene have a boiling point at 1? 1^e C and 182.2^e C respectively, makes it possible to utilize this difference the boiling point, so that the starting fraction responsive to the. conditions of the resin according to the invention and " can be maintained at the top of the column.

In the technique petroleum resins, that is of a completely new concept, of selecting a compound selected, ■ in a petroleum oil, thermally cracked, and subjecting the living being to accurate fractionation, to obtain a

" Fraction having very defined characteristics. In advantage\

particular, as disclosed in the present application, this concept is oriented, in order to define the ratio of conjugated diolefin content ex indenes, at certain values as indicated above. Oette operation can usually be reached by the distillation columns known, but requires a fractionation column at atmospheric pressure or under vacuum having'

with a larger number of trays.

Is added, to the starting fraction prepared as described above, 0.01 to 5 # by weight of a catalyst type Rriedel -Crafts as boron trifluoride, aluminum chloride, boron trifluoride complex and phenol, preferably boron trifluoride, boron trifluoride etherate, and the boron trifluoride phenolate. The méiange resulting cured at a temperature of between + 60 °C °-30 G and for a period of 10 minutes to 15 hours '. The catalyst is then decomposed and removed with alkali agents such as caustic soda and sodium carbonate. If necessary, the reaction product thus treated is washed with water and the unreacted oil and the low molecular weight polymers, are separated from the reaction product by evaporation or distillation.

The resulting product is an aromatic hydrocarbon resin having a softening point of 60 to 120 °C bromine and a value equal to or less than 15. It has excellent weather resistance and heat, the preferred resins, have a softening point between 80° and 100 °C.

Maintaining It has been discovered, that if any of such important criteria in respect of the starting fraction, i.e. especially i) 0.7 i" content weight diolefin, ii) 3 i" for the content ratio conjugated diolefins, iii) 2 fo in these indene or alkylated derivatives (iiü) jS and 8 for the content ratio indene, is neglected, the hydrocarbon resin resulting from the polymerization of such a starting fraction defective will have a very low resistance to weather and heat, will yellow when used in the pressure-sensitive adhesive compositions, will be very good in weather resistance, resistance to the cohesion, the sealing strength, the stickiness and the life of the stickiness.

The pressure-sensitive adhesive composition according to

the present invention is prepared by mixing the resin hy-

drocarbonée aforementioned aromatic, with a styrene-butadiene rubber (SBR) or rubber mixtures consisting essentially of SBR type rubber. the ratio of the mixture can vary da. rsv large proportions. Typically the. resin is present in proportions of between and 14G 20 parts by weight and preferably between 30 and 120 parts by weight per 100 parts by weight of rubber. If desired, optional supplementary different additives including, for example, 0 to 60 parts of a softening agent, 0 to 60 parts of a plasticizer, 0 to 100 parts of a load and 0 to 50 parts of an aging inhibitor. Ges different amounts depend on the rubber compound used, but are usually included in a range of 0 to 100 parts per 100 parts of rubber.

the invention will be described in more detail by reference to the following examples, for illustrating the invention however the 3ans limit.

EXAMPLE 1

The resin compound, used in the pressure-sensitive adhesive compositions of the present invention, is prepared as follows.

Starting Cracked oil as defined above is a intermediate product of the steam cracking of naphtha having a boiling point of between 140 and 220 °C. It has been analyzed, by gas chromatography and has the following composition:

Compounds polymérisabies (fi by weight)-----49.0 total Content cyclopentadiene and

methylcyclopentadiene. (% by weight)-¹ -1.6 Content iadène and its total

alkyiés derivatives (fi by weight) content -8.4 cycicpentadiène (fi by weight)-■ 0.4 content of conjugated dioiéfine Ratio (fi) -■. 4.0 content (%)------18 Ratio indene, 5

Starting Cracked oil identified above, has been introduced by a heating device in a first fractionation codonne A-1, and in a second column ' fractionation £-1, the two fractionating columns are defined in the table below.

Fractionation Columns-

Tray Type

Many tray

Load tray (from the bottom)

Supply temperature (°C)--

Pressure bottom (mm. Hg. abs.)-

Températuren bottom (°C)

Column head temperature (°C)

Pressure column head (mm Hg. abs.)-

Hangover time is at the bottom of the column (h)

Reflux Rate

Screen (1)

(2) to barbo Cover age.

the operational conditions of the fractioning column A-1, were chosen in such a way that the fractions at the top of the column, of the fractionation column, contain a " total indene, and its alkylated derivatives, equal to 2% by weight or less and a content ratio of indene of 8 ^c o/ or less. The product tubing head cetee first fractionation column A-1, is then introduced into the second fractionator B-1, that also operates under the conditions specified in the table-, such that the desired starting fractions, at the bottom of the fractionation column B-1, wherein the total content of cyclopentadiene and methy ' l cyclopentadiene, is equal to U, 7 by weight or less and the ratio aioléfines content is equal to or less than > Q 3. The conjugated diolefins, have:

then been removed from the head of the fractionation column H • (. This produces ' 58 portions of the fractions for 100 parts of oil starting cracked. Traction resulting There starting has substantially the following composition:

Compounds polymerizable by weight) 42.60

Total Content cyclopentadiene and

methyl cyclopentadiene (c/o by weight) 0.40 total Content indene and its derivatives

alkylated (% by weight) 1.00 Ratio content of conjugated diolefins Ratio(%)0.84 content d¹ indene (c/O) 2.51 To this starting fraction attenuated, is added 0.5% by weight of a phenol complex boron trifluoride ti be catalyst and the polymerization is carried out for 3 hours at 2Q°C. The product is washed with an aqueous solution of sodium hydroxide to remove catalyst and is then washed with water. Unreacted The oil and lower the polymers are removed from the product by distillation.

The resulting resin has a softening point and Ball Doughnut of 95 °C, a value of bromine 7 (according to ASTM® D-1158-57) and a Gardner color of 1" (according to ASTM D1544-58T). The resin has been mixed in amounts of 30 parts, portions 50, 80 parts respectively and 100 parts by weight by 100 parts by weight of styrene-butadiene rubber of commerce, the mixture is dissolved in the toluene to reaching a concentration of 20 parts by weight.

EXAMPLE 2

At parts by weight of the resin prepared in the example 1, mixture is 70 parts by weight of SLR and 30 parts by weight of natural rubber and the assembly has been dissolved in 600 parts by weight of toluene.

Comparative Examples 1 and 2

Cracked oil is subjected to polymerization under the same conditions as in the example 1. A similar process has also been carried out with the cracked oil starting, but at a polymerization temperature of 60 °C. This produced, two different resins having a softening point of 120 °C a value of bromine 12 and color of 2 and the other a softening point of 80 °C, a value of bromine 25 and a color of 5 · Ges resins have been mixed in an amount of 30, 50, 80 and 100 parts by weight per 100 parts by weight of SBR.

Examples 3 and 4 comparative

It has followed the method of comparative examples 1, except, that is used following resins:

Comparative Example 3: Picolite A (softening point 115 °C) terpene resin, prepared by Esso Chemical Co.

Comparative Example 4:1150 PX YS resin (softening point 115 °C, terpene resin prepared by Yasuhara Industries Ltd.) Comparative Examples 5 to 8

The process of example 2 was followed with the exception that 50 parts by weight of each of the resins used in the comparative examples 1 to 4 were mixed with rubber compounds.

The different pressure-sensitive adhesive compositions, obtained in the previous examples comparative examples, have been subjected to the following tests and the results of these assays, include in tables III and IV.

■1. Fssai stickiness

Each of the various adhesives, obtained as above, has been applied to a polyester film (having a thickness of 38 microns) with a thickness of 30 microns. The coated film, has then to. to placed during 25 hours at room temperature of 23 ± 1 °C, in the form of an adhesive strip. The stickiness was tested, by the method^,! J. Dow Bal Rolling Method ", in which the steel balls having a diameter of C 81,18/81.18 cm iJj *. ' J2/32 1/32 inch to inch), have been rolled up on a band auhésive inclined at an angle of 30 °, with a stroke of 10 cm. approach The ball having the largest diameter, has been halted, on an adhesive surface 10 cm of this measurement is considered to be a measure of stickiness, of the different adhesive compositions. More the number of the ball is large, more the tackiness is high as shown by ' tables III and IV.

It has been performed according to the recommendations of the Japanese Industrial Standards (Z-1523) (JIS). The adhesive tapes, prepared as described above, have been cut tapes a magnitude of 25 mm, and adhered to a stainless steel panel polished with polishing paper impermeable. Was measured

the force required, to remove bands ° peel 1.80 at a rate of 300 mm/min.

'). Cohesive strength assay "

This assay has been performed according to the method ' described in JIS Barrens Z-1524 the adhesive tapes mes r-mt 25 cm by 25 cm, are attached to a stainless steel panel, the measurement of the distance of travel of the web the test, under the influence of a load of 1 kg applied, on a portion of the film of the ribbon after 24 hours.

Test strips 1 subjected to the test above, have then been. left 1 ambient temperature of + 25_r i °C, for a period of 7 day ' consecutive, and then further tested by the test method 1.

Tested Each adhesive has been applied to the cellophane paper to a thickness of 30 microns and left at an ambient temperature of 23+1^C C for 24 hours, na cellophane adhesive thus prepared, is coated with a white paper and is then irradiated with a lamp for sterilizing V located 15 to 30 cm.

The color changes adhesive compositions after a period of 15 hours, have been observed with the naked eye. The potential^-1 color ration is indicated in the following table III by the markings:

Excellent essentially colorless transparent

O...-low yellow

X .-bad extremely yellow.

Thus it has been found that the pressure-sensitive adhesive compositions according to the present invention, exhibit an excellent balance of forcesadhésives , cohesive the stickiness and weather resistance compared to the different comparative examples.

III

forceest that the too low to be able to determine