Organophilic phyllosilicates

Details Organophilic phyllosilicates Organophilic phyllosilicates

1999-02-11

2001-03-06

Michl, Paul R. (Department: 1714)

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

Processes of preparing a desired or intentional composition...

Reexamination Certificate

active

06197849

ABSTRACT:

The present invention relates to novel organophilic phyllosilicates, their preparation, and also their use in shapable moulding materials and in finished mouldings or composite materials, in particular in nanocomposites, which preferably comprise the novel organophilic phyllosilicates in exfoliated form.
It is known that organophilic phyllosilicates prepared, for example, by ion exchange, can be used as fillers for thermoplastic materials and also for thermosets, giving nanocomposites. When suitable organophilic phyllosilicates are used as fillers, the physical and mechanical properties of the mouldings thus produced are considerably improved. A particular interesting feature is the increase in stiffness with no decrease in toughness. Nanocomposites which comprise the phyllosilicate in exfoliated form have particularly good properties.
U.S. Pat. No. 4,810,734 has disclosed that phyllosilicates can be treated with a quaternary or other ammonium salt of a primary, secondary or tertiary linear organic amine in the presence of a dispersing medium. During this there is ion exchange or cation exchange, where the cation of the ammonium salt becomes embedded into the space between the layers of the phyllosilicate. The organic radical of the absorbed amine makes phyllosilicates modified in this way organophilic. When this organic radical comprises functional groups the organophilic phyllosilicate is able to enter into chemical bonding with a suitable monomer or polymer. However, the use of the linear amines mentioned in U.S. Pat. No. 4,810,734 has the disadvantage that they decompose thermally at the high temperatures of up to 300° C. usually used for thermoplastics processing and can discolour the product. The formation of decomposition products can lead to emissions and to impairment of mechanical properties, for example impact strength.
Surprisingly, it has now been found that organophilic phyllosilicates which have been prepared by treating phyllosilicates, i.e. using cation exchange with salts of quaternary or other cyclic amidine compounds, have greater thermal stability during processing combined with excellent dispersing effect and interfacial adhesion. When the amidinium compounds according to the invention are used in thermosets there is no change in the stoichiometry of the reactive components, in contrast to the use of linear ammonium salts, and this allows addition to the thermosetting materials of an increased proportion of tillers. If the cyclic amidines used contain reactive groups the organophilic phyllosilicates prepared therewith and used as fillers can be covalently linked to the matrix by grafting. Amidinium ions derived, for example, from hydroxystearic acid or hydroxyoleic acid have surprisingly good layer separation combined with excellent adhesion to a wide variety of polymers and fillers. In contrast to the prior art alkyl groups with nonterminal hydroxyl groups in particular are useful, as well as alkyl substituents with terminal hydroxyl groups. The hydroxyl groups in the alkyl side chain may easily be derivatized in order to tailor a system-specific property spectrum. The compounds also create excellent dispersing effect and interfacial adhesion. It is also surprising that, despite their bulk, the heterocyclic amidine salts according to the invention, with long substituted or unsubstituted alkyl radicals, exchange cations efficiently within the spaces between the layers of the phyllosilicates.
The process therefore allows the cyclic amidine compound in quaternized or, if desired, protonated form to be embedded into the phyllosilicate by cation exchange, and this then to be incorporated as a filler into the thermosetting material, if desired of a thermosetting epoxy resin material, or an addition product to be made from the cyclic amidine compound and a part of an epoxy component of the thermosetting material and the resultant product to be embedded into the phyllosilicate and this material to be processed with the remaining part of the epoxy component to give a moulded material.
The present invention is defined in the patent claims and relates in particular to organophilic phyllosilicates which have been prepared by treating a naturally occurring or synthetic phyllosilicate, or a mixture of such silicates, with a salt of a quaternary or other cyclic amidine compound, or with a mixture of such salts.
The present invention further relates to the preparation of the novel organophilic phyllosilicates, and also to their use in shapable moulding materials and in finished mouldings or composite materials, in particular in the preparation of nanocomposites, which preferably comprise the novel organophilic phyllosilicates in exfoliated form.
The present invention further relates to shapable moulding materials and finished mouldings in the form of composite materials, in particular in the form of nanocomposites, which comprise the novel organophilic phyllosilicates, preferably in exfoliated form.
The present invention further relates to the use of the novel shapable moulding materials for producing coating materials, adhesives, casting resins, coatings, flame retardants, agents with thixotropic effect and/or reinforcing agents.
The present invention further relates to coating materials, adhesives, casting resins, coatings, flame retardants, agents with thixotropic effect and/or reinforcing agents which comprise a novel organophilic phyllosilicate.
The present invention also relates to the use of the amidine compounds of the formula (I) given below for preparing organophilic phyllosilicates.
Phyllosilicates which may be used for preparing organophilic phyllosilicates are in particular naturally occurring or synthetic smectite clay minerals, in particular montmorillonite, saponite, beidelite, nontronite, hectorite, sauconite and stevensite, and also bentonite, vermiculite and halloysite. Preference is given to montmorillonite and hectorite. Preferred phyllosilicates are in particular those in which the distance between layers is from about 0.7 to 1.2 nm (nanometer) and which in the form of the novel organophilic phyllosilicates have a distance of at least 1.2 nm between the layers. The phyllosilicates used preferably have a cation exchange capacity in the range from 50-200 meq/100 g (milliequivalents per 100 grams). Examples of phyllosilicates of this type which may be used are described, for example, in A. D. Wilson, H. T. Posser, Developments in Ionic Polymers, London, Applied Science Publishers, Chapter 2, 1986. Synthetic phylosilicates are obtained, for example, by reacting naturally occurring phyllosilicates with sodium hexafluorosilicate. Synthetic phyllosilicates are obtainable commercially, for example, from CO-OP Chemical Company, Ltd., Tokyo, Japan, and have also been described by that company.
The phyllosilicate montmorillonite, for example, generally has the formula:
Al
2
[(OH)
2
/Si
4
O
10
]. nH
2
O
where some of the aluminium may have been exchanged for magnesium. The composition varies depending on the deposit from which the silicate has been obtained. A preferred composition of the phyllosilicate has the formula: (Al
3.15
Mg
0.85
)Si
8.00
O
20
(OH)
4
X
11.8
. nH
2
O where X is an exchangeable cation, generally sodium or potassium. The hydroxyl groups given may be exchanged for, for example, fluoride ions. Exchange of hydroxyl groups for fluoride ions gives, for example, the synthetic phyllosilicates.
Preferred organophilic phyllosilicates are those which have been prepared using a cyclic amidine compound of the formula (I):
or using a mixture of such compounds, in which
R
1
is a linear or branched aliphatic radical having from 1 to 20 C atoms and may contain one or more unsaturated bonds and/or one or more functional groups;
R
2
is hydrogen or a linear or branched aliphatic radical having from 1 to 20 C atoms which contains one or more unsaturated bonds and/or one or more functional groups and, if desired, has interruption by one or more —NH— groups or by one or more oxygen atoms;
R
3
is hydrogen or a linear or branched aliphatic radical

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