Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Patent
1995-01-09
1996-11-05
Cain, Edward J.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
C08L 900
Patent
active
055718671
DESCRIPTION:
BRIEF SUMMARY
FIELD OF INVENTION
The invention relates to hydrocarbon resins, processes for their manufacture and to adhesive compositions containing such resins.
In particular, the invention relates to low-colour hydrocarbon resins with good compatibility with styrenic block copolymers, such as SIS and SBS, and to resin/block copolymer blends having good properties as an adhesive composition. These compositions may be used in adhesive label or sanitary (diaper) applications.
BACKGROUND OF INVENTION
Mixed olefinic/aromatic tackifier resins have been prepared from a wide variety of feedstocks including main component and C.sub.5 olefins are a minor component. 1,2 and cyclopentene. Steam cracker olefins is predominantly mono-olefinic. components but also containing styrenics such as styrene and alpha-methylstyrene. Some styrenics have a lowering effect on softening point. molecular weight distribution and tend to increase the softening point.
Specific disclosures include:
Tack/fiefs for SBS with relatively low molecular weights prepared by using a Friedel-Crafts catalyst and polymensing a mixture of C.sub.5/ C.sub.6 (di)olefins and C.sub.8 /C.sub.10 aromatics are disclosed in U.S. Pat. No. 4,078,132 (Lepert) and EP-A-23456 (Evans). The softening points are low in EP-A-23456 (Evans).
In Lepert Example 12 molecular weights and aromaticity are high. However the material does not tackify SBS satisfactorily. Ball tack is 4 to 30 cm and so is too high.
In Evans such high amounts of chain transfer agent (mono-olefins) are used that the softening point is very low. The product will not provide a good adhesive/cohesive performance in SBS blends. The liquid resin serves to substitute the oil in hot melt adhesive (HMA) but cohesive performance is reduced. U.S. Pat. No. 3,784,530 (Goodyear) describes a hydrocarbon resin tackifier having a softening point of from 60.degree. to 110.degree. C. prepared by polymerizing piperylene, 2-methyl-2-butene, dicyclopentadiene and alpha-methyl styrene. The polymerization uses Friedel-Crafts catalyst systems. At least 15% of 2-methyl-2-butene is used in the feed stream which also contains appreciable amounts of piperylene and dicyclopentadiene components and an aromatic component in the form of the alpha-methyl styrene.
The resulting resin is not hydrogenated. It is said to be suitable for track/lying natural and synthetic rubbers including butadiene-styrene copolymers. There is no specific disclosure of block-copolymers. The amounts of 2-methyl-2-butene used are high (above 15 wt %) and this adds to the cost of the resin. At least 15 wt % must also be used of a costly alpha-methylstyrene component to provide the desired aromaticity. The amounts of aromatic component added are minor but the feed components have to be fairly pure (hence the use of alpha-methylstyrene) if a low Gardner colour, rubber-compatible tackifier resin is to be obtained.
U.S. Pat. No. 3,846,352 is a divisional application from U.S. Pat. No. 3,784,530 with almost identical disclosure. U.S. Pat. No. 4,037,016 discloses a resin prepared by Friedel-Crafts polymerisation which is used in an adhesive composition including block copolymers,-with end-blocks forming from 10 to 50 wt % of the copolymer. The tackifying resin has carbon to carbon unsaturation and therefore must be essentially non-hydrogenated. The softening point is low from 60.degree. C. to 80.degree. C.
The feed stream appears to have a similar composition to that described previously but uses higher levels of costly alpha-methyl styrene (over 40 wt %). Other branched chain mono-olefins are described other than 2-methyl-2-butene although 2-methyl-2-butene still seems preferred.
U.S. Pat. No. 4,046,838 describes a block copolymer blend with a resin. The block copolymer may be an SBS. The resin has a softening point of a range of 60 to 110.degree. C. The composition of the resin feed stream appears identical to that of earlier Goodyear documents referred to. The adhesive compositions may be used as a pressure sensitive adhesive.
U.S. Pat. No. 4,104,327 discloses an a
REFERENCES:
patent: 3784530 (1974-01-01), Osborn et al.
patent: 3846352 (1974-11-01), Bullard et al.
patent: 4037016 (1977-07-01), Habeck et al.
patent: 4046838 (1977-09-01), Feeney
patent: 4078132 (1978-03-01), Lepert
patent: 4104327 (1978-08-01), Inoue et al.
patent: 4952639 (1990-08-01), Minonimya et al.
Luvinh Quoc
Macedo Anne V.
Rydzkowski Richard J. F.
Cain Edward J.
Exxon Chemical Patents Inc.
Muller William G.
Reid Frank E.
Schneider John E.
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