GB2169909A - Hydrocarbon resins - Google Patents

Abstract

Petroleum Resins particularly effective for use as tackifiers for hot melt and solvent-based pressure sensitive adhesives are prepared by a process wherein (1) a C8- and/or C9 aromatic unsaturated hydrocarbon-containing feed and (2) a C5-unsaturated aliphatic hydrocarbon-containing feed are separately polymerised and thereafter the reactor effluents from polymerisations (1) and (2) are mixed and the resin is obtained by stripping the combined effluents.

Description

SPECIFICATION Hydrocarbon resins This invention relates two a process for preparing petroleum resins derived from unsaturated aliphatic and aromatic hydrocarbons.

More particularly this invention relates to resins comprising block copolymers which are particulary effective when combined with elastomer block copo lymers astackifiersfor hot melt pressure sensitive adhesives.

US 3950453 describes a process for preparing petroleum resins said to be compatible with ethylenevinyl acetate copolymers for use in hot melt adhesives. This process involved first polymerising C4/C5 conjugated diolefins with at least one C4to C10 monolefinic unsaturated hydrocarbon as a first feed portion and secondly polymerising said conjugated diolefins as a second fed portion, the first and second polymerisation being conducted in the presence of a Friedel-Crafts catalyst. The proportion of monolefins in the first feed portion should not be higherthan 80 wt.%.

US 2317857 discloses a process for preparing a resin suitable for moulding or coating by polymerising styrene with isoprenewhich has been previously partially polymerised catalytically with the aid of an acid-acting metallic halide catalyst such as BF3-ethyl ether complex. US 2317858 and 2317859 relate to copolymers similarly prepared but using respectively butadiene and piperylene instead of isoprene.

in accordance with this invention resins particularly effective for use in tackifiers for hot melt pressure sensitive adhesives and in tackifiers for solvent-based pressure sensitive adhesives are prepared by a process wherein (1) a C8 and/or C aromatic unsatu- rated hydrocarbon-containing feed and (2) a C8- unsaturated aliphatic hydrocarbon-containing feed are separately polymerised and thereafter the reactor effluents from polymerisation (1) and (2) are mixed andthe resin is obtained by stripping the combined effluents.

The C8 and/orCg aromatic unsaturated hydrocarbon-containing feed (hereinafter referred to as Feed A) can be for example styrene, styrene derivatives, petroleum distillates of 100 C to 200"C boiling points which include more than 20 wt. % of styrene and/or derivatives.

One commercially available feed containing C8 and Cg aromatic unsaturated hydrocarbons comprises about 10 wt.% styrene, about 1.3 wt.% alpha-methyl styrene, about 11 wt.% meta vinyl toluene, about4 wt. % para vinyl toluene, about 13 wt. % indene, about 1 wt.% di-methyl styrene about 0.5 wt.% 1 -methyl indene, the remainder being mainly non-olefinic aromatic hydrocarbons.

The C5-aliphatic unsaturated hydrocarbon-containing feed (hereinafter referred to as Feed B) is typically a C8 distillate of 200 to 100 C boiling points excluding cyclopentadienes, e.g. piperylene, isoprene, buta diene, hexadiene etc.

If desired, to feed A can be added up to 50 wt.%, e.g.

2 to 50 wt.% based on the weight of feed A, of aliphatic monomers, suitably monomers similarto those described with reference to feed B. It is found that the resulting reactor effluent is more compatible with the feed B reactor effluent. Also the final product is more compatible with elastomeric block copolymers when making hot melt pressure sensitive adhesives.

Each feed is preferably dissolved in a diluent and such diluents may be for example aromatic hydrocarbonssuch as bepzene,xylene,toluene; aliphatic hydrocarbons such as heptane, pentane, hexane; naphtha distillates: or halogenated hydrocarbons such aschlorobenzene.

The amount of diluent is preferably 20 to 1000 parts by weight per 100 parts byweightof monomer. More preferably 50 to 500 parts by weight per 100 parts by weight of monomer.

The polymerisations should take place in the presence of a Friedel-Crafts catalyst.

Suitable Friedel-Crafts catalysts include aluminium chloride, aluminium bromide, aluminium chloride/ hydrochloric acid/aromatic hydrocarbon complex or aluminium chloride/alkyl halide/aromatic hydrocarbon complex. In the former complex the aromatic hydrocarbon is preferably an al kylated hydrocarbon, e.g. 0-xylene, mesitylene, ethyl benzene or isoproyl benzene and in the latter complex the alkyl chain ofthe alkyl halide can be linear or branched and can vary from 1 to 30 carbon atoms.

Othersuitable Friedel-Craftscatalysts are acid liquid AlCl3sludges obtained as by-products during the alkylation of benzene or any other substituted aromatics (e.g. toluene orxylene) with branched chain olefins.

Apartfrom aluminium trichloride, the preferred Friedel-Crafts catalyst is boron fluoride gas or a complexof BFswith aromatic compounds such as phenol.

Generally, from 0.1 to 5wt.%, 0.2 to 1.5wt.% of Friedel-Crafts catalyst based on the total weight of monomers is used.

For the polymerisation of both Feed Aand Feed B the reaction temperature should preferably be between 0" and 100 C, more preferably 20 to 90"C. The reaction pressure may be atmospheric, or higher or lowerthan atmospheric. The reaction time may be from several minutes to 12 hours, preferably 0.2 to 3 hours.

When Feeds A and B have been polymerised the reactor effluents are mixed. Usually they are mixed so that the total aromatic content in the mixed polymers is 3 to 70 wt.%, preferably 5 to 50 wt.%. The effluents are preferably mixed at ambienttemperature for a time ranging from a couple of minutes to 40 to 50 minutes.

The mixture is thereafter stripped, preferably at a temperature from ambient temperature to 250"C under an inert gas such as nitrogen, at atmospheric pressure. The resin of the invention can then be obtained by steam distillation,for example at 250"C.

The resin which is obtained usually has an average molecularweight(GPCmethod) of 500 two 2000 and a softening point (JIS K-2531) of 70 to 1 20"C.

The resins obtained can be used in many applica tionswhich require low viscosity, good flexibility and elongation beforeorespeciallyafterchemical mod ificationwith polar compounds such as phenols, unsaturated anhydrides such as maleic anhydride or unsaturated acids (e.g. fumaric acid). The resins are designed for a wide range of end uses and applications. They can be applied to paper, metal, thermoplastic films, Cellophane (Registered Trade Mark), polyester, PVC, woven or non woven fabrics, glass etc.

and for bonding such materials together. Typical applications are hot melts, carpet backing, coating with drying oil formulations, book binding, paper sizing or in any applications involving natural or synthetic and/or rubbers such as caulks, sealants or rubbertackification.

More especiallythey may be used as tackifiers with natural rubber or synthetic rubbers such as polyisoprene, EPDM, butyl, chlorobutyl, bromobutyl, neoprene and block copolymers for example styrene/ isoprene rubber (Shell Cariflex (Registered Trade MarkTR1 107) and mixtures of such rubbers.

Other applications involving such resin properties are pressure sensitive adhesives, hot melt adhesives, hot melt pressure sensitive adhesives, lowtemperatu re adhesives, label adhesives, latex adhesives, surgical tapes and masking tapes where they may be blended with polymers such as ethylene/vinyl acetate copolymers and optionally with wax.

According to this invention one can use as a component in an adhesive formulation the resin prepared by the above described process.

Thus the present invention can also provide a hot melt adhesive comprising (i) an ethylene vinyl acetate copolymer, preferably 20to30wt.% (ii) wax, preferably 40 to 60wt.% and (iii) a resin, preferably in a proportion of 20 to 30 wt.%,said resin being prepared bytheabove described process.

In the Figure the process of reacting the two monomers in the two reactors, followed by mixing in the receiverwherethe catalyst is inhibited is schemati cally shown.

Thus FeedA(aromaticcomponents) are fed into the first reactor and are continuously polymerised. The reactor effluent is then sentto a stripper on a continuous basis. If desired a copolymerofaromatic/ aliphatic components can, alternatively be prepared by adding aliphatic monomers.

Forthe polymerisation of aliphatic components (Feed B)aliphaticcomponentsarecontinuously polymerised in the second reactorbyfeeding into it aliphatic monomers and catalyst. The reactor effluent is then sentto the stripper on a continuous basis.

Both the above reactor effluents, one from the reactorfor aromatic components and another from the reactor for aliphatic components, are mixed in the neutralization section where the catalysts are kilied and eliminated. Afterthat,the mixture is stripped and the resin of the invention is obtained.

Example In this Example the reactions were performed in the manner shown in the Figure as as described above.

The specific reaction conditions etc. were as indicated below: (i) for the polymerisation of aromatic monomers (Feed A) Reactor size : 11 Raw material components styrene 35wt.% piperylene-rich-C5 distillates 10wt.% steam cracked naphtha 55wt.% Catalyst :AICI3 0.7 wt.% per total feeds Reaction temperature : 500C Average residence time at reactor : 60 minutes (ii) Forthe polymerization of aliphatic monomers Reactor size : 1 1 Raw material components : piperylene-rich-C5 distillates (piperylene content 34%) Catalyst : 0.7 wt.% per total feeds Reaction temperature : 70"C Average residence timeatreactor : 60 minutes (iii) The reactor effluents (i) and (ii) were mixed at ambienttemperature for several minutes (iv) The catalystwas decomposed in aqueous ammonia. The catalyst residues were eliminated by a centrifugal separation method. Afterwards the mixture was stripped at room temperature around 250"C under nitrogen gas. The resin ofthe invention was obtained by steam-distillation.

The procedure described above (run 1) was repeated in three other runs with different feeds and/or blend ratios and the results are shown in Table 1.

The pressure-sensitive adhesive (PSA) properties ofthe resins obtained in Runs 1,2,3 and 4were determined and the results shown in Table 2 which also camparesthem with priorartresins.

Details of the tests were as follows: PSA Performance Measurement SIS elastomer : Cariflex TR-1107 (Shell Chemicals) Plasticizer : Esso process oil 765N (aromatic 9%; naphthalene 33% remainder paraffin) Esso process oil L2 (aromatic 20%, naphthalene 33% remainder paraffin) Resins compared : Aliphatic type: Escorez 1310 Aromatic type: Cg resin Tape preparation : Adhesives consisting of SIS (100)/resin (100)/oil (20) are coated on to Kraft paper.

It can be seen that in general the resins prepared by the process of the invention (Tests 1 to 7) had propertiessuperiorto those of prior art resins (Tests 7,8 and 9).

Table 1 1 2 3 4 Feed Components C8/C9 C5 Cg/Cg C5 C8/C9 C5 Ca/Cg C5 C5 Piperylene-rich C5 10 60 10 60 7 60 7 60 styrene 35 - 35 - 37 - 37 ocll(1) 55 40 55 40 56 40 56 40 Reaction Temperature ( C) 50 70 50 70 50 70 50 70 Blend ratio 24 76 36 64 20 80 31 69 Resin Properties Sp.Gr (25/4-C) 0.99 0.99 0.98 1.00 Softening Point ( C) 90.9 91.9 91.0 90.00 Colour, Gardner 5.5 5.5 5.5 5.5 WCP (40/20/40)(2) 70(-) 70)-) 70)-) 70)-) Styrene content 24 33 22 31 on 636 628 675 626 9w 1495 1419 1613 1490 1 Steam cracked naphtha 2 Wax cloud point of a blend of 40 wt.% wax, 20 wt.% resin asd 40 wt.% of ethylene vinyl acetate copolymer Table 2 PSA Performance Tests Comparison Tests 1 2 3 4 5 6 7 8 9 Run 1 Resin 100 Run 2 Resin 100 100 Run 3 Resin 100 Run 4 Resin 100 100 C5 Resin (Escorez E1310) 100 50 Cg Resin 100 50 Cariflex - 1107 100 100 100 100 100 100 100 100 100 Plasticiser (Oil) Naphthenic oil 20 20 20 20 20 Aromatic oil 20 20 20 20 PSA Performance 180- Peel Strength (1/25 min)(1) 1410 1290 1380 1350 1440 1440 1520 1290 1200 J Dow Ball Tack (No) (2) 27 27 27 27 27 28 27 16 20 Cohesion (min) 280 250 > 360 > 360 275 > 360 105 0 20 Shear Adhesion (min) 130 360 > 360 320 330 > 360 90 350 270 (1) PDTC-1 (2) J Dow method (Proc. Inst. Pub; Ind., L, 205(1954)) Comparative Example To compare the properties ofthe resins prepared bythe process ofthis invention, i.e. separate polymerisations, with resins prepared by one step polymerisation a feed of C6 distillates and styrene in which the styrene content was 44wt.% was polyme rized using an AICI3 catalyst.

The PSA properties obtained were as follows: 180"C Peel Strength at 25 Cf1) 1300 g/25 mm J Dow Ball Tack No at 25 Cf2) 20 Cohesion at 250C(3) 18 min Shear adhesion at 400C(4) 52 min (1) Peel Strength - PSTC No 1 (2) BallTack - J Dow method (3) Cohesion - PSTC method - (Stainless Steel panel, Kraft paper specimen 25 mm x 25 mm, at room temperature weight 1 Kg) (4) Shear adhesion at40 C - similar to PSTC cohesion method but use K-liner cardboard as test panels.

Test specimen is Kraft 1 Kg. Measuretime until specimens fall down at 40"C.

It can be readily seen that the resins produced by the process of the invention have superior properties compared with those of a similar resin but prepared in a one step polymerisation process.

Claims (7)

1. A process for preparing a resin wherein (1) Feed A (as herebefore defined) and (2) Feed B (as hereinbefore defined) are separately polymerised and thereafter the reactor effluents from polymerisation (1) and J2) are mixed and the resin is obtained by stripping the combined effluents.

2. A process according to claim 1 wherein up to 50 wt.% based on the weightof Feed A, of aliphatic monomers are added to Feed A.

3. A process according to claim 2 wherein 2 to 50 wt.% of aliphatic monomers are added said monomers having the composition of Feed B.

4. A process according to any one ofthe preceding claims which is conducted in the presence of a Friedel-Crafts catalyst.

5. A process according to any one ofthe preceding claims wherein the total aromatic content in the mixed polymers is 5 to 50wit.%.

6. A process according to claim 1 substantially as hereinbefore described with reference to the Example.

7. A resin whenever prepared by the process according to any of the preceding claims.