Binding agents modified with nanoparticles, for coatings,...

Details Binding agents modified with nanoparticles, for coatings,... Binding agents modified with nanoparticles, for coatings,...

2002-01-15

2004-06-15

Dawson, Robert (Department: 1712)

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

Synthetic resins

Processes of preparing a desired or intentional composition...

C523S201000, C523S209000, C525S327200, C525S360000, C525S374000, C525S386000

Reexamination Certificate

active

06750270

ABSTRACT:

This invention relates to nanoparticle-modified binders for lacquer systems, to coating compositions containing said binders and to the use thereof.
Lacquer systems containing nanoparticles are prior art. The nanoparticles impart an improved overall range of properties to the lacquer system, for example with regard to scratch resistance and resistance to solvents and chemicals. EP-A-0 832 947, for example, describes scratch-resistant clear lacquers based on a binder/crosslinking agent system and nanoparticles comprising reactive groups on the particle surface. EP-A-0 872 500 furthermore describes scratch-resistant coating compositions based on a combination of hydroxy-functional binders with nanoparticles comprising blocked isocyanate groups on the particle surface. When coating layers applied from these coating compositions are cured, the nanoparticles are chemically bonded into the coating layer.
U.S. Pat. Application No. 10/009,382 describes nanoparticle-modified binders, which are produced by reacting carboxy-functional nanoparticles with epoxy-functional binders.
Compatibility problems may arise when incorporating nanoparticles into lacquer systems. For example, prior art lacquer systems containing nanoparticles sometimes give rise to a non-homogeneous distribution of the nanoparticles in the coating layers applied from these coating compositions or achieving a homogeneous distribution of the nanoparticles in the coating compositions themselves is difficult, if not entirely impossible, from the outset.
The object arises of eliminating or largely avoiding such compatibility problems in lacquer systems containing nanoparticles.
The object may be achieved by reacting nanoparticles provided with a reactive functionality with binders which comprise a reactive functionality complementary to the reactive functionality of the nanoparticles, to give rise to nanoparticle-modified lacquer binders, wherein the binders are produced in the presence of the nanoparticles and wherein the combination of carboxyl groups as the reactive functionality of the nanoparticles and epoxy groups as the complementarily reactive functionality of the binders is excluded.
The invention accordingly provides nanoparticle-modified binders which are produced by producing binders in the presence of nanoparticles provided with a reactive functionality, which binders have a reactive functionality complementary to the reactive functionality of the nanoparticles and reacting said latter binders to give rise to nanoparticle-modified lacquer binders, wherein the combination of carboxyl groups as the reactive functionality of the nanoparticles and epoxy groups as the complementarily reactive functionality of the binders is excluded.
The invention also provides a process for the production of nanoparticle-modified binders, wherein binders are produced in the presence of nanoparticles provided with a reactive functionality, which binders have a reactive functionality complementary to the reactive functionality of the nanoparticles and said latter binders are reacted to give rise to nanoparticle-modified lacquer binders, wherein the combination of carboxyl groups as the reactive functionality of the nanoparticles and epoxy groups as the complementarily reactive functionality of the binders is excluded.
Both here and below, the reactive functionality of the nanoparticles will be designated as functional groups (A) and the reactive functionality of the binders complementary to the reactive functionality of the nanoparticles will be designated as functional groups(B).
The functional groups (A) and (B) exhibit mutually complementary reactivity, i.e. they are capable of reacting together to form a covalent bond.
The functional groups (A) and functional groups (B) comprise functional groups which are capable of reacting together by free-radical polymerisation and/or entering into addition and/or condensation reactions. Examples of addition reactions between (A) and (B) groups are ring-opening addition of an epoxy group on a carboxyl group with formation of an ester and a hydroxyl group, the addition of a hydroxyl and/or primary and/or secondary amino group onto an isocyanate group with formation of a urethane and/or urea group, the addition of a primary and/or secondary amino group and/or CH-acidic group onto an alpha,beta-unsaturated carbonyl group, in particular (meth)acryloyl group, the addition of a primary and/or secondary amino group onto an epoxy group. Examples of condensation reactions between (A) and (B) groups are the reaction of a hydroxyl and/or primary and/or secondary amino group with a blocked isocyanate group with formation of a urethane and/or urea group and elimination of the blocking agent, the reaction of a hydroxyl group with an N-methylol group with elimination of water, the reaction of a hydroxyl group with an N-methylol ether group with elimination of the etherification alcohol, the transesterification reaction of a hydroxyl group with an ester group with elimination of the esterification alcohol, the transurethanisation reaction of a hydroxyl group with a carbamate group with elimination of alcohol, the reaction of a carbamate group with an N-methylol ether group with elimination of the etherification alcohol. Examples of functional groups (A) and (B), which are capable of reacting together by free-radical polymerisation, are olefinically unsaturated groups, for example vinyl groups, allyl groups, in particular (meth)acryloyl groups.
The nanoparticles comprise conventional particles of the “nanometer” size range known to the person skilled in the art, for example with an average particle size of 5 to 200 nm, preferably of 10 to 100 nm, which contain functional groups (A) in particular on the particle surface. The nanoparticles may be of a single phase structure or a core/shell structure. Nanoparticles of a single phase structure contain functional groups (A), in particular on the particle surface. In the case of nanoparticles of a core/shell structure, the functional groups (A) are a constituent of the shell and optionally additionally of the core. The (A) equivalent weight of the nanoparticles is, for example, 250 to 3000.
The nanoparticles of a single phase structure are of an inorganic nature and are modified with functional groups (A) and optionally further organic residues. The material comprises, for example, element/oxygen networks with elements from the range aluminium, boron, titanium, zirconium and/or silicon, preferably silicon.
The nanoparticles of a single phase structure preferably comprise particulate organoaluminium, organoboron, organotitanium, organozirconium and/or organo-silicon, particularly preferably organosilicon, polymers (Ia) of the formula (R
3
SiO
1/2
)
w
(R
2
SiO
2/2
)
x
(RSiO
3/2
)
y
(SiO
4/2
)
z
, wherein y=10 to 100 mol % and the sum of w, x, y and z should amount to 100 mol %. The identical or different residues R may comprise functional groups (A) or groups convertible into functional groups (A) per se or preferably residues which bear the functional groups (A) or the groups convertible into functional groups (A). In addition to these groups, the residues may also comprise C1-C6 alkyl residues, in particular methyl residues, aryl residues, such as for example phenyl residues. Non-limiting examples of functional groups (A), which are preferably attached to silicon via a residue, are epoxy groups, carboxyl groups, hydroxyl groups, amino groups, blocked isocyanate groups, olefinically unsaturated groups, alkoxysilane groups. Functional groups (A), for example carboxyl groups, hydroxyl groups or amino groups may optionally also be present in blocked form. Examples of residues which bear functional groups (A) or groups convertible into functional groups (A) are appropriately substituted hydrocarbon residues, in particular substituted alkyl residues, for example alkenyl residues, such as for example the vinyl or allyl residue, or mercaptoalkyl, cyanoalkyl, aminoalkyl, acyloxyalkyl, such as 3-(meth)acryloyloxypropyl, glycidyl residues and hydroxyalkyl residues.
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