Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
2000-09-12
2002-12-31
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
06500883
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to organosilane- and/or organosiloxane-containing agents for modifying the surface of fillers and includes their use for preparing filled polyamide compounds. The present invention further relates to surface-modified fillers, to polyamides filled therewith and to products produced on this basis.
2. Background of the Invention
It is known that fillers can be incorporated into polymers. One motive for doing this is cost saving. Some of the expensive polymer can be replaced by low cost extending filler. A further reason is the controlled modification of mechanical properties of the polymer. The filler then becomes a functional filler. This method can give a lasting improvement in the mechanical properties, such as tensile strength and flexural strength, of filled polyamide compounds, for example (referred to below as PA compounds).
Use has long been made of aminosilanes, e.g. DYNASYLAN® AMEO, to obtain relatively high filler levels (U.S. Pat. No. 3,843,591, EP 0136 540 B1). The disadvantage is the poor toughness of PA compounds prepared using aminopropyltrialkoxysilane. A typical PA compound comprises two completely different base components: an inorganic mineral and an organic polymer. The inorganic mineral is generally hydrophilic and has an ionic structure. The organic polymer is usually rather hydrophobic and has a covalent structure. The two base components have different coefficients of expansion, surface tensions, flexural strengths, etc. The greatest incompatibility is found at the interface between the inorganic and organic components. This is usually the point of weakness in a filled PA compound. Modifying the interface with aminoalkoxysilanes gives rise to a bonding bridge and thus to an increase in the strength of the PA compound. Although the aminosilane improves many mechanical properties, this does not apply to impact resistance properties.
Water-based compositions for specific amino-functional silicon compounds, inter alia those known as “bisaminosilanes” are disclosed in German Patent Application 199 08 636.2, and these can be used, for example, for modifying the surfaces of glass fibers or mineral fibers, and also for the surface modification or treatment of pigments.
EP 0 518 057 B1 discloses mixtures of vinyl-/alkyl-/alkoxy-containing siloxanes, used as crosslinking agents for thermoplastic polyolefins. Mixtures of aminopropyl-/alkoxy-/alkyl-functional siloxane oligomers are disclosed in German Patent Application 198 49 308.8, where the mixtures are used, inter alia, as coupling agents in filled thermoplastic compounds, in the coating of glass fibers, or else for silanizing fillers or pigments.
Water-based organopolysiloxane-containing compositions are disclosed in European Patent Applications EP 0 716 127 A2, EP 0 716 128 A2 and EP 0 832 911 A1, and these are essentially obtainable by mixing water-soluble aminoalkylalkoxysilanes and, if desired, glycidic-ether- or else methacryloxy-alkylalkoxysilanes with non-water-soluble alkylsilanes followed by acid catalyzed hydrolysis or, respectively, cocondensation with removal of the alcohol of hydrolysis. Compositions of this type, too, can be used for coating glass fibers, or else for silanizing fillers or pigments.
German Patent Application 198 18 923.0 relates to stable compositions of water-soluble amino- and alkenyl-functional organosiloxanes, and to the preparation of these and their use for modifying the properties of pigments or fillers, such as aluminum oxide, magnesium oxide, silica, chalk, gypsum, borites, glass fibers, glass beads, carbon black, wollastonite, kaolin, mica or talc—to name just a few examples.
German Patent Application 198 18 924.9 moreover teaches a process for preparing surface-modified fillers by way of treatment with an organosiloxane-containing composition, where, besides OH groups, the organosiloxane has at least one amino-functional group and, if desired, other functional groups selected from the group consisting of alkyl, haloalkyl, alkenyl, glycidyl ether alkyl, acryloxyalkyl and methacryloxyalkyl. Fillers of this type are used in adhesives, sealing compounds, polymer compounds, paints and surface coatings.
German Patent Application 198 30 128.6 relates to flame retardants whose surface has been modified by treatment with organosilanes and, respectively, with organosiloxanes. Flame retardants of this type are used, inter alia, in polyamides.
DE 199 29 021.0 describes the use of functional organyloranyloxysilanes or cocondensates of these on carriers in cable compounds.
SUMMARY OF THE INVENTION
An object of the present invention is to provide another way of preparing polyamides which are filled, strong and impact-resistant.
It has been found that in particular fillers which have been treated with an agent A, B or C, these being specified in greater detail below, give good strength properties together with good impact resistance properties in filled, and in particular kaolin-filled, PA compounds.
In a manner which is surprising and advantageous, good or improved impact resistance in the filled polyamide can be brought about with substantial retention of good strength properties by simultaneous modification of the interface between filler and polyamide (PA) with a component having adhesion-promoting properties, for example an aminosilane, and with a component having lubricant properties, for example an alkylsilane or a polyethersilane or a wax based on polyethylene (PE), polypropylene or silicone.
Agglomerate-free dispersion of the filler in the PA polymer matrix is essential, and this is achieved in a highly satisfactory manner by the use of fillers which are treated with one of the above agents.
Said PA compounds moreover have improved rheology and are therefore easier to compound. This implies further cost savings for the compounder.
DETAILED DESCRIPTION OF THE INVENTION AND PREFERRED EMBODIMENTS THEREOF
The present invention provides organosilane- and/or organosiloxane-containing agents A, B and/or C for modifying the surface of fillers which are used in preparing filled polyamide.
Agent A comprises at least one amino-functional silicon compound of the general formula I
R—NH—(CH
2
)
3
—Si(CH
3
)
x
(Z)
3−x
(I)
in which the groups Z are identical or different and Z is an alkoxy group having from 1 to 3 carbon atoms or a hydroxyl group or a chlorine atom, x is 0 or 1 and R is a linear or branched alkyl group having from 1 to 20 carbon atoms, a cycloalkyl group having from 5 to 12 carbon atoms or an aryl group having from 6 to 12 carbon atoms, preferably 3-[N-butylamino]propyltrimethoxysilane, 3-[N-butylamino]propyltriethoxysilane, 3-[N-cyclohexylamino]propyltrimethoxy-silane, or at least one compound known as a “bisaminosilane”, preferably “Bis-AMEO”: [(H
5
C
2
O)
3
Si(CH
2
)
3
NH(CH
2
)
3
Si(OC
2
H
5
)
3
] or “Bis-AMMO”: [(H
3
CO)
3
Si(CH
2
)
3
NH(CH
2
)
3
Si(OCH
3
)
3
], or at least one tertiary aminosilane, such as “Tris-AMEO”: [(H
3
CO)
3
Si(CH
2
)
3
]
3
N, or a mixture made from primary and secondary and/or tertiary aminosilanes and/or aminosiloxanes which are obtainable by hydrolysis, condensation or cocondensation of primary, secondary and/or tertiary aminosilanes, where the average degree of oligomerization of the aminosiloxanes is from 2 to 20.
Agent B comprises i) at least one amino-functional silicon compound of the general formula II
R—Si(CH
3
)
x
(Z)
3−x
(II)
in which the groups Z are identical or different and Z is an alkoxy group having from 1 to 3 carbon atoms or a hydroxyl group or a chlorine atom, x is 0 or 1 and R is an amino group of the formula H
2
N—[(CH
2
)
2
NH]
y
(CH
2
)
3
, where y is 0, 1 or 2, preferably 3-aminopropyltrimethoxysilane (AMMO):[H
2
N(CH
2
)
3
Si(OCH
3
)
3
], 3-aminopropyltriethoxysilane (AMEO):[H
2
N(CH
2
)
3
Si(OC
2
H
5
)
3
], N-aminoethyl-3-aminopropyltrimethoxysilane (DAMO): [H
2
N(CH
2
)
2
NH(CH
2
)
3
Si(OCH
3
)
3
], or N
Barfurth Dieter
Edelmann Roland
Frings Alber-Johannes
Horn Michael
Jenkner Peter
Degussa - AG
Michl Paul R.
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