Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Reexamination Certificate
2000-09-01
2003-07-01
Wilson, D. R. (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymers from only ethylenic monomers or processes of...
C526S135000, C526S137000, C526S142000, C526S144000, C526S157000, C526S158000, C526S124200, C526S124300, C526S124700, C526S348000, C526S348400, C526S348500, C526S348600, C526S123100, C502S120000, C502S127000, C502S128000, C502S119000
Reexamination Certificate
active
06586543
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a process for the preparation of substantially amorphous poly-&agr;-olefins with improved space-time yield under controlled reaction conditions.
2. Discussion of the Background
In the adhesives industry, a large number of substantially amorphous poly-&agr;-olefins have for many years been used as adhesive raw materials for a very wide range of applications. Here, the applications range from the hygiene sector and lamination through the packaging sector to structural adhesive bonds and the furniture industry. In most of these applications, these adhesive raw materials are distinguished by high adhesion to a very wide range of substrates, strong cohesion and good resistance to chemicals in combination with an excellent price/performance ratio.
Increasingly in demand on the market in the case of modern hotmelt adhesives are the properties of good sprayability, outstanding bonding properties immediately after application and as far as possible little formulation effort. Particularly suitable for these requirements are low viscosity products having a viscosity of 400-15,000 mPas at 190° C. and a needle penetration of from 18 to 90×0.1 mm at 25° C.
The preparation of products in this viscosity range is described in EP-A-0 023 249. However, with the TiCl
3
catalysts used there, only comparatively hard products having a needle penetration of up to not more than 25×0.1 mm at 25° C. can be prepared. For precise adjustment of the bonding properties, such products must be formulated with further adhesive raw materials, such as resins and waxes. Owing to the required additional cost for the adhesive producer, this constitutes a considerable cost disadvantage.
A process for the preparation of such soft and low-viscosity products is described in EP-A-0 335 484. In this process, a magnesium chloride support is milled with aluminum trichloride to produce a supported catalyst, and the product is further milled with titanium tetrachloride; the mixture is then activated with a trialkylaluminum cocatalyst. However, the process disclosed there is only of very limited use in industry since polymerization can be effected only in a very narrow temperature range, which in practice gives rise to considerable measurement and regulation effort. This is particularly complicated by the nonuniform activity behavior of the catalyst described there over the reaction time; at the beginning of the reaction, the polymerization takes place very rapidly with considerable heat evolution, but the catalyst activity declines rapidly and then falls relatively rapidly to a level which is too low for an industrial process. The nonuniform activity behavior is problematic not only in the case of batchwise polymerization but also in a continuous process where in particular the rapid decline in the activity is a problem and leads to an unsatisfactory space-time yield. In addition, the reaction is intended to take place at comparatively low temperatures; owing to the heat removal required, this is disadvantageous in terms of energy and further increases the control effort.
SUMMARY OF THE INVENTION
Surprisingly, it is now possible to avoid the above-mentioned disadvantages and prepare a substantially amorphous poly-&agr;-olefin with a substantially improved space-time yield in a wide temperature range and with a more uniform course of reaction. This and other objects of the present invention may be achieved by a process for preparing a substantially amorphous poly-&agr;-olefin, which includes:
a) preforming a solid catalyst and, optionally, a first amount of a trialkylaluminum cocatalyst, by contacting the catalyst and optionally the cocatalyst with at least one selected from the group including oxygen and a compound which includes active oxygen, to form a preformed catalyst,
wherein the solid catalyst includes magnesium, aluminum and titanium, and
wherein said trialkylaluminum cocatalyst includes 1 to 9 carbon atoms in each alkyl group;
b) contacting the preformed catalyst with a second amount of the cocatalyst, wherein a molar ratio of trialkylaluminum to the titanium ranges from 40:1 to 700:1, to form a catalyst mixture;
c) polymerizing, in the liquid phase, with the catalyst mixture, an olefin or an olefin mixture at a temperature between 30 and 160° C., to produce the poly-&agr;-olefin.
Another embodiment of the invention relates to a preformed catalyst for preparing a substantially amorphous poly-&agr;-olefin, which is prepared by a process including:
a) preforming a solid catalyst and, optionally, a first amount of a trialkylaluminum cocatalyst, by contacting the catalyst and optionally the cocatalyst with at least one selected from the group including oxygen and a compound which includes active oxygen, to form a preformed catalyst,
wherein the solid catalyst includes magnesium, aluminum and titanium, and
wherein the trialkylaluminum cocatalyst includes 1 to 9 carbon atoms in each alkyl group.
DETAILED DESCRIPTION OF THE INVENTION
Various other objects, features and attendant advantages of the present invention will be more fully appreciated as the same becomes better understood from the following detailed description of the preferred embodiments of the invention.
Preferably, the present invention provides a process for producing a substantially amorphous poly-&agr;-olefin, which includes
a) a solid catalyst which is prepared from magnesium halide, aluminum trihalide and titanium tetrahalide is used,
b) a trialkylaluminum which has from 1 to 9 carbon atoms in each alkyl group is added as a cocatalyst, so that the molar ratio of trialkylaluminum to titanium is in the range from 40:1 to 700:1,
c) the olefin or olefin mixture is polymerized in the liquid phase and at a temperature between 30 and 160° C., and
d) the poly-&agr;-olefin formed is isolated, which includes preforming the solid catalyst before the addition of the cocatalyst by addition of a further component which is selected from oxygen and compounds which contain active oxygen.
In general, based on 10 mol of magnesium halide, from 0.5 to 4 mol of aluminum trihalide and from 0.4 to 2 mol of titanium tetrahalide are used here.
The solid catalyst can be prepared, for example, by the process which is disclosed in EP-A-0 335 484, which is hereby expressly incorporated by reference. The halide used is preferably chloride. In addition to magnesium halide, aluminum trihalide and titanium tetrahalide, according to the prior art modifying substances may also be added, in not more than about twice the stoichiometric amount, based on the titanium content of the catalyst, such as, for example, alkylaluminum halides, ethylene oxide, propylene oxide, alkyl halides, dry hydrogen chloride gas and/or aluminoxanes. Preferably no electron donor over and above said substances is added.
Here, a solid catalyst which as a rule contains magnesium, aluminum and titanium in the following amounts is obtained:
from 10 to 25% by weight, preferably from 14 to 22.5% by weight and particularly preferably from 16 to 21% by weight of magnesium, from 1 to 5% by weight, preferably from 1.5 to 4% by weight and particularly preferably from 2 to 3% by weight of aluminum and
from 1 to 5% by weight, preferably from 1.5 to 4% by weight and particularly preferably from 2 to 3% by weight of titanium.
For the preforming, the solid catalyst is treated, before the addition of the cocatalyst, by the addition of a further component which is selected from oxygen and compounds which contain active oxygen.
Oxygen may be used either in pure form or as a mixture with other gases, such as, for example, nitrogen or argon. Compounds which contain active oxygen are, for example, organic peroxides, such as, for example, dicumyl peroxide, cumyl hydroperoxide, tert-butyl cumyl peroxide, di-tert-butyl peroxide, tert-butyl hydroperoxide, dibenzoyl peroxide or benzoyl tert-butyl peroxide or hydrogen peroxide.
The absence of an otherwise usual dark coloration of the catalyst suspension on subsequent contact with trialkylaluminum prefer
Schlueter Norbert
Wey Hans Guenther
Degussa - AG
Lee Rip A.
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