CA1061941A

CA1061941A - Hydrocarbon tackifying resin

Info

Publication number: CA1061941A
Application number: CA243,783A
Authority: CA
Inventors: Robert A. Osborn; Herbert L. Bullard
Original assignee: Goodyear Tire and Rubber Co
Current assignee: Goodyear Tire and Rubber Co
Priority date: 1975-02-24
Filing date: 1976-01-19
Publication date: 1979-09-04
Also published as: JPS51109989A; FR2301543A1; ZA76321B; FR2301543B1; BR7600938A; ES444777A1

Abstract

Abstract of the Disclosure A hydrocarbon-derived, tack enhancing, diolefin/
olefin backboned resin prepared by reacting, in the presence of an aliphatic solvent and selected catalyst, a monomer mixture comprised of about 60 to about 75 weight percent of a diolefin/olefin mixture, of the piperylene/olefin type, and, correspondingly, about 40 to about 25 weight percent .alpha.-methyl styrene.
Said resin has a particular utility for tackifying rubbery elastomers derived form the aqueous, free radical, emulsion polymerized butadiene/styrene monomers.

Description

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This invention relates to synthetic hydrocarbon-derived resins and to their preparation. This invention especially relates to tacki.fying resins suitable for use in admixture with 1,3 butadiene/styrene copolymers derived .~rom a manipulative combination of diolefins~ olefins and a-methyl styrene.
Valuable reslns can be preparecL by polymerizing a diolefin/olefin mixture characterized by a principal backbbne of piperylene and 2-methyl-2-butene. Such resins, when polymerized with aluminum chloride, can be especially valuable for use in adding tack to various rubbers for adhesive purposes.
However, such resins are substantially i-nadequate for effectively enhancing the tack of 1,3-butadiene/styrene aqueous emulsion copolymerized elastomers for many purposes. Although the mechanism is not thoroughly understood, such backboned resins, apparently require a balance of compatability with the butadiene/styrene copol~mers to achieve ma~imum tack enhancement Simply increasing the 2-methyl-2-butene, or decreasing the piperylene~ content of the backbone has been found to be insufficiently effective.
Therefore, it is an object of this invention-to provide an improved hydrocarbon-derived resin having a primary diolefin/olefin backbone for tack enhancement of 1,3-butadiene/styrene emulsion copol~mer elastomers~
In accordance with this invention, a hydrocarbon-derived tackifying resin is prepared by the method which comprises reacting in the presence of an aliphatic -1- ~

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hydrocarbon solvent and a catalyst selected from aluminum chloride and ethyl aluminum dichloride~ a monomer mixture comprised of 60 to about 75 weight percent of a diolefin/olefin mixture of a weight ratio in the range of about 0.6/1 to about :L.4/1 and, correspondingly, about 40 to about 25 weight percent a-methyl styrene, where said diolefin comprises at least about 95 weight percent piperylene and up to about 5 weight percent isoprene based on the diolefin, and where said olefin comprises at least one olefin selected from

2-methyl-2-butene~ 2-methyl-1-butene, 2-methyl-2-pentene, and 2-methyl-1-pentene~ preferably at least about 90 weight percent 2-methyl-2-butene or 2-methyl-2-pentene based on the olefin. A 650C to 800C softening point is typical.
In the practice of this invention~ it is preferred that the diolefin is essentially piperylene and that the olefin is essentially 2-methyl-2-butene.
In further practice of thls invention, in order to provide effective enhancement of the ta¢k by the a-methyl styrene, it is required in the resin that, as the amount of a-methyl styrene increases~ the diolefin/
olefin ratio increases. Thus, for example, as a-methyl styrene increases from 25 to 40 percent, the diolefin/
olefin ratio should correspondingly increase about 0.6/1 to about 1.~/1. In this regard, it is preferred that the amount of a-methyl styrene ranges from about 30 to about 37 weight percent and the diolefin/olefin ratio correspondingly ranges from about 1.1/1 to about 1.3/1.

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The resins of this invention are prepared b~
reacting the manipulated monomers in the presence of an aliphatic solvent, and aluminum chloride or ethyl aluminum dichloride~ at a temperature in the range of about 0C to about 100C~ pre~erably in the range o~
about 10C to about 50oC. The reaction can be conducted batch-wise or as a continuous process. The reaction can be conducted at atm~spheric pressure or above or below atmospheric pressure. Generally, the autogen~us pressure developed by the reaction can be used.
Representative of various aliphatic solvents are saturated hydrocarbons containing 3 to 8 carbon atoms, representative of which are n-butane, isobutane, n-pentane, isopentane, n-hexane, isohexane, n-heptane, and isoheptane Hexane and heptane are preferred. It ; is understood that unreacte~ hydrocarbons in the polymerization mixture can also act as a solvent.
Generally sufficient solvent is used to provide a solution containing 70 weight percent monomers or resin, although higher or lower concentrations can usually be used.
Generally the reaction can be conducted over a period o~ time in the range of about 30 to about 120 minutes, although shorter or longer times can be used.
The resin is generally recovered by deactivating the catalyst with a material selected fro~ water, alcohol such as methanol, isopropanol and butanol and/or lime, filtering the product and steam stripping the filtrate to remove volatiles. Then the resin can be mixed with ~o~

various rubbers, particularly 1,3-butadiene/styrene aqueous emulsion copolymerized elastomers, as tackifying enhancers.
The resin of this invention has been found to be particularly useful for mixing with and enhancing the tack of elastomers prepared by free radical, a~ueous emulsion copolymerizing a mixture of 1,3-butadiene and styrene. Particularly representative of such copolymers are those containing about 60 to about 95 weight percent units derived from 1,3-butadiene, and, correspondingly about 40 to about 5 weight percent units derived from styrene.
The elastomers can conveniently be prepared by conventional emulsion copolymerization, followed by coagulation and drying.
Generally the tackifying resin is mixed with the elastomer in an amount of about 30 to about 250 weight percent taokifying resin, based on the mixture of resin and elastomer. If desired, the mixture can conveniently be formed by dry mixing the tackifying resin and elastomer on a mixing mill or banbury or by mixing ln the presence of a volatile organic hydroca~bon solvent such as toluene ? benzene, hexane, heptane and octane.
The practice of this invention is more fully illustrated by reference to the following example which is intended to be representative rather than limiting of the scope of the invention. Unless otherwise indicated~
all parts and percentages are by weight.

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EXAMPLE I
A series o~ experiments were conducted, identi~ied herein as Experiments A to H and HH. In these experiments, various amounts of piperylene ~PIP) and 2-methyl-2-butene t2MB2), along with heptane, were charged to reactors. Additionally, various amounts of -methyl styrene along with aluminum trichloride were also charged to the reactors. The polymerization reactions were conducted at temperatures in the range of about 25C
to about 30C for about 120 minutes. After this time, the catalyst was neutralized, or deactivated, wlth methanol and lime. The resin was simply recovered by filtering the product and steam distilling the filtrate to remove volatiles.
The results of Experiments A to H7 including tack analysis with butadiene/styrene rubber using 50parts per resin per 50 parts free radical, aqueous emulsion-co-polymerized butadiene/styrene elastomer are more clearly shown in the following Table 1. Note that the resin made with similar pip/2MB2 ratios with no a-methyl styrene impart no effective tack to SBR~ as is more clearly demonstrated in Experiment HH.

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TABLE l Resin Monomer ~o alpha- Softening Tack Ratio methyl Point 2 (Rolling ~ styrenel (C) Ball) A 0.8 28 74 1.9 ~3 1.2 ~8 79 ~ 25 c o.6 33 69 1.2 D ~l.0 35 . 70 2.1 E l.0 35 72.5 1.4 F l.~ 3~ 78 6.5 G 0.8 ~ 72 1.8 H 1~2 40 76 2.2 HH 1.O 0 99 No tack 1 - Based on the total of piperylene, 2-methyl-2-butene and a-methyl styrene 2 - Sof~ening point of resin according to ASTM E 28-58 T.

It should be pointed out that the polymerization mixture did contaln some few additional hydrocarbons, in addition to the basic piperylene/2-methyl-2-butene/
a-methy~ styrene, as is more clearly shown in Table 2.

(Piperylene/2-methyl-2-butene ratio = 1.3) ~ Percent (bY wei~ht) t-2-pentene 9.78 c-2-pentene 12.00 2-methyl-2-butene 20~16 isoprene .8 cyclopentene 3.~6 1-t-3-pentadiene 20.51 l-c-3-pentadiene 5.82 a-methyl styrene 26.00 other Cs's and C6's 1.~3 Experiments I-P are presented in Table 3 to more clearly show the effect of varying the amount o~
a-methyl styrene for specific piperylene/2-methyl-2-butene ratios. The resin/rubber mi~tures were prepared as for Table 1. These experiments generally indicate that~ as the amount of a-methyl styrene is increased, the enhancement of tack for butadiene/styrene type, free radical, aqueous emulsion copolymerized~ rubber is substantially enhanced.
TA~LE 3 Tack Monomer % (Rollin~
Ratio a-methyl Ball) PIP/2MB2 sty~ene inches I 1.~ 33 ~ 13 J 1.~ 26 8.73 K l.L~ 38 6.28 L 1.4 ~0 ~.08 M 1.3 31 ~13 N 1.3 33 8.63 0 1.3 36 5.68 P 1.3 38 3.75 It is a particular advantage of this invention that the resin is required to be prepared in the presence of an aliphatic solvent, preferably selected from hexane or heptane, to the substantial or essential exclusion of aromati~ hydrocarbons. Not only is such a solvent required for the preparation of the advantageous resin of this invention~ but this requirement uniquely obviates the requirement of aromatic hydrocarbon recovery systems in commercial applications. Indeed, this .a particular polymerization diluent or solvent advantage is of sufficient magnitude that ik should be considered as an enhancing feature of the invention.
So long as the basic piperylene/said ole~in backbone is maintained, the polymerization monomer mixture can be modified by containing up to about 15 weight percent, preferabiy only up to about 10 weight percent, piperylene dimers, piperylene trimers or other unsaturated hydrocarbons containing 5 to 6 carbon atoms. Representatlvè of such hydrocarbons, which may take place in the polymerlzatlon reaction, include those, in addition to the 2-methyl-2-butene, selected from 2-methyl-1-butene, 2~3-dimethyl l-butene~
2~3-dimethyl-2-butene~ 2-methyl-1-pentene~ 2-methyl-2-pentene, cyclopentene and 1,3-cyclopentadiene. It is understood that o~her hydrocarbons containing 4 to 6, more generally 5 to 6, carbon atoms can be present which act more as diluents than reactants. Representative of typical hydrocarbons which have been found to be present are 3,3-dimethyl-1-butene~ l-pentene, 2-pentene,

3-methyl-2-pentene, 4-meth~l-1-pentene, 2-hexene and cyclohexene.
While certain representative embodiments and details have been shown for the purpose of illustrating the invention, it will be apparent to those having skill in this art that various changes and modifications may be made therein without departing from the spirit or scope of the invention.

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Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A hydrocarbon-derived, tack enhancing, diolefin/olefin backboned resin prepared by the method which comprises reacting in the presence of an aliphatic hydrocarbon solvent and a catalyst selected from aluminum chloride and ethyl aluminum dichloride, a monomer mixture comprised of 60 to about 75 weight percent of a diolefin/olefin mixture of a weight ratio in the range of about 0.6/1 to about 1.4/1 and, correspondingly, about 40 to about 25 weight percent .alpha.-methyl styrene, where said diolefin comprises at least about 95 weight percent piperylene and up to about 5 weight percent isoprene based on the diolefin, and where said olefin comprises at least one olefin selected from 2-methyl-2-butene, 2-methyl-1-butene, 2-methyl-2-pentene and 2-methyl-1-pentene.

2. The resin of claim 1 where the diolefin/olefin weight ratio increases in accordance with any increase in the amount of .alpha.-methyl styrene.

3. The resin of claim 2, characterized by having a softening point in the range of about 65°C to about 80°C where said olefin is comprised of at least about 90 weight percent 2-methyl-2-butene, where said resin is recovered from the polymerization mixture by first neutralizing the catalyst with a material selected from lime, water, and an alcohol selected from methanol, isopropanol and butanol, followed by steam stripping the filtrate to remove volatiles.

4. The resin of claim 3 where said piperylene/2-methyl-2-butene/.alpha.-methyl styrene backboned monomers are modified by containing up to about 15 weight percent other unsaturated hydrocarbons containing 5 to 6 carbons.

5. The resin of claim 4 where said solvent is selected from hexane, heptane and unreacted hydrocarbons, and t;he polymerization is conducted at a temperature in the range of about 10°C to about 50°C.