Note: Descriptions are shown in the official language in which they were submitted.
2 ~ 7 ~
Herberts Gesellschaft mit beschrankter Haftung
AN AQUEOUS COATING AGENT AND AQUEOUS EMULSION~
PROCESS FOR THE PREPARATION AND USE THEREOF.
The invention refers to aqueous coating agents on the basis of polyols
which can be crosslinked with polyisocyanates and which contain
chlorinated polyolefines as adhesion mediators. The invention relates
also to the preparation of the aqueous coating agents from the aqueous
emulsions containing chlorinated polyolefines; it refers also to the use
of the coating agents especially for coating plastic materials.
Aqueous two-component systems on the basis of epoxide resins and amino
resins have been described in DE-A-41 23 860. This reference refers to
specific dispersions from epoxide resins, amino resins and polyurethanes
which are used together with pigments and adjuvants for the preparation
of primers for the automotive industry. EP-A-0 358 979 describes aqueous
two-component coating agents consisting of an acrylate component and a
polyisocyanate component. Such coating agents can be used for metal
substrates; however, if they are used for coating plastic materials,
especially polyolefines, the adhesion to the substrate is not sufficient.
This is demonstrated by a low resistance against water of the coated
substrates. Further it is not possible to prepare thick layers with such
coating agents. Preparing thicker layers furnishes defects such as small
blisters and pin holes. DE-A-39 10 901 and the corresponding ~0 90/12056
describe coating compositions for plastic materials containing water, a
film-forming binder system, chlorinated polyolefines (CP0), as well as
optional pigments and adjuvants. The film-forming binders are acrylate
resins or polyurethane resins in an aqueous emulsion. After application
of such coating agents the systems dry physically. For the preparation
of such coating agents it is necessary to use specific emulsifiers as
well as a melt process for the chlorinated polyolefines; further it is
necessary to carry out an azeotropic destillation of all organic solvent
components. This is very costly.
..
DE-A-41 31 127 describes adhesion primers on the basis of chlorinated
polyolefines, organic solvents, water, emulsifiers as well as pigments
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2 210 ~
and an optional film-forming binder which can be used for coating plastic
materials. The systems dry physically, i.e. no chemical react;on occurs
in the coated film. If such primer layers are coated with coating agents
containing organic solvents, the risk of re-dissolving of the primer
layer has to be taken into consideration. Otherwise defects of the coated
surfaces can occur.
EP-A-O 466 136 describes specific a~ueous coating agents for coating
plastic substrates, containing a combination of olefine resins, urethane
resins and epoxide resins. An example for an olefine is chlorinated
polypropylene.
It is the object of the present invention to provide aqueous coating
agents which can be used for coating plastic moldings, especially in the
automotive industry and which furnish coatings having a good impact
resistance even when cold, having a smooth surface free of defects even
if thick layers are applied.
It has been found that this object can be achieved by an aqueous coating
agent on the basis of one or more polyols having ionic groups or groups
convertible into ionic groups, which can contain pigments, fillers and/or
conventional lacquer adjuvants, comprising:
A) 10 to 40 wt.-% of one or more polyols having a number average
molecular weight (Mn) of 500 to 200000, an OH-number of 15 to 300
and a content of ionic groups and/or groups convertible into ionic
groups of 5 to 400 meq/100 g solid resin, which are at least partly
neutralized, the ionic groups being preferably anionic groups,
B) 0.5 to 10 wt.-% of one of more chlorinated polyolefines having a
chlorine content of 15 to 35 wt.-%,
C) 5 to 40 wt.-% of one or more organic solvents having a boiling range
from 100 to 1~0C,
D) 25 to 75 wt.-% of water,
E) O to 30 wt.-% of one or more further water dilutable binders which
are free from groups reactive with NCO,
the percentages by weight oF components A) to E) adding up to 100 wt.-%
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21(~a~71
and
F) one or more polyisocyanates having on average at least two free
isocyanate groups per molecule, in such an amount that the ratio of
the number of reactive isocyanate groups to the OH-groups of the
polyols is 0.5 : 1 to 5 : 1,
the coating agent being a two-component system, one component containing
the polyols and the other component containing the polyisocyanates.
It has been found that the coating agents of the invention can be
prepared from aqueous emulsions of one or more chlorinated polyolefines
having a chlorination degree of 15 to 35 wt.-%. They can be prepared
essentially or totally free from emulsifiers if they are disperged
together with polyols; the polyols are such which can be used in the
aqueous coating agents of the invention. However, it is also possible to
prepare the coating agents of the present invention in any other way. For
example, the chlorinated polyolefines can be used together with an
emulsifier.
The coating agents of the present invention are especially two-component
systems, one component containing the polyols and the other containing
the polyisocyanates. The polyol component is diluted with water; the
polyiscocyanate component can be disperged together with the polyol
component in water. The chlorinated polyolefines, as well as the optional
pigments, fillers and conventional lacquer adjuvants can be contained in
one or both components. It is clear that any substances which are
dispersed in the polyol component A) should be compatible with water in
order to achieve a good storage stability. Additives which are used with
the polyisocyanate-crosslink component should not be reactive with the
polyisocyanates. Generally it is convenient to disperse organophilic
substances in the polyisocyanate component.
The polyol component A) which can be used in accordance with the present
invention is especially based on binders on the basis of radically
polymerisable monomers containg OH-groups, OH-group containing polyesters
and/or OH-group containing polyurethanes. The number-average molecular
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weight is 500 to 200000, the OH-number is 15 to 300 mg KOH/g solid resin.
The dispersability ;n water is achieved by polar groups, e.g. OH-groups,
ether groups, urethane groups, ionic groups or groups which are
convertible into ionic groups. It is possible to use kationic groups or
groups which are convertible into kationic groups, e.g. amino groups;
however, anionic groups or substituents t:onvertible into anionic groups,
e.g. carboxyl groups, phosphoric acid groups and sulfonic acid groups are
especially convenient. Polymers having carboxyl groups are preferred. The
content of ionic groups is 5 - 400 meq/100 9 solid resin. The polyol
component is provided in the form of an aqueous dispersion having a
viscosity of 100 - 10000 mPas at 23 C. The pH is 5 - 10.
Examples for suitable COOH- and OH-groups containing polymers on the
basis of olefinically unsaturated monomers are described in EP-A-0358979.
These are aqueous dispersions on the basis of olefinically unsaturated
monomers. Such monomers can be free from functional groups, examples are
styrene, (meth)acrylic acid alkylesters having C, - C8 in the side chain,
vinyl acetate or (meth)acrylonitrile. Further, at least parts of the
monomers can have functional groups, e.g. hydroxyl groups, such as
hydroxyalkyl ester of (meth)acrylic acid, for example 2-hydroxyethyl
acrylate or 2-hydroxypropyl acrylate. Further it is possible to insert
other reactive groups, e.g. epoxide groups or amido groups, using
monomers such as, e.g. glycidyl(meth)acrylate or N-methoxymethyl~meth)-
acrylamide. The ionic groups can be inserted using olefinically
unsaturated monomers, containing functional groups which can be converted
into ionic groups, e.g. olefinically unsaturated mono- or dicarboxylic
acids having a molecular weight of 72 - 207, such as, e.g. acrylic acid,
maleic acid, itaconic acid and the halfesters thereof or using compounds
such as 2-acrylamide-2-methylpropane-sulfonic acid.
The preparation of the polymerisates is carried out in accordance with
usual processes, e.g. as polymerisation in solution. It is possible to
use continuous and discontinuous processes. The copolymerisation is
generally carried out using initiators and optional regulating compounds
at temperatures of 50 to 160 C. It is carried out in a liquid wherein
monomers or polymers are both soluble. Preferred solvents are organic
solvents which are not detremental to the coating agents to be
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21~327 ~
formulated. The solvents are preferable organic solvents which are at
least partly miscible with water. Generally the initiators are used in
amounts of 0.1 to 3 wt.-%, relating to the amount of monomers; examples
are peroxides and/or azocompounds and/or peresters. Specific examples are
benzoyl peroxide, cumol hydroperoxide, tert.-butyl peroctoate or 2.2-azo-
bis(2-cyanopropane).
It is possible to reduce the molecular weight by the use o~ regulating
compounds. Preferred regulating compounds ar~ mercaptanes, halogene
containing compounds or other substances transferring radicals. Specif;c
examples are n-dodecyl mercaptane, butan-1-ol or dimeric ~-methyl
styrene.
Examples for solvents for the polymerisation are aromatic solvents suchas toluene, xylene; esters, such as ethyl acetate, butyl acetate, ethyl
glycol acetate; ethers such as butylglycol or ethylglycol ether; ketones
such as acetone or methylethyl ketone. I F desired the solvents can be
removed by destillation, preferably in vacuum from the polymerisates
before or after dilution with water.
The number average molecular weight (Mn) of the binders on the basis ofradically polimerisable monomers is preferably 500 to 50000, particularly
preferred from 1000 to 10000. The OH-number is 15 - 300, preferably 30 -
170 mg KOH/g solid resin. The content of polar, e.g. anionic, groups is5 - 400 meq, preferably 25 to 280 meq per 100 9 solid resin.
Examples for acidic water dispersable polyurethane resins are describedin DE-A-41 24 453 and DE-A-40 00 889. Examples are polyurethane resins
prepared by the reaction of two valent or multivalent saturated linear
or branched aliphatic or cycloaliphatic polyalcohols with linear or
branched aliphatic, cycloaliphatic or aromatic polyisocyanates, e.g.
diisocyanates, and optional linear or branched aliphatic or
cycloaliphatic monoalcohols. In order to insert ionic groups, it is, e.g.
possible, to insert by reaction low molecular dialcohols having an
anionic group or a group convertible into an anionic group, preferably
a carboxyl group.
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The reaction is carried out at temperatures from 20 to 150 C, optionally
using catalysts. The reaction can be carried out by melting or in
solution in inert dry solvents. A stepwise reaction is also possible.
Linear or branched molecules are formed in accordance with the amount of
multivalent polyols. If an a excess of alcohols is used, terminal hydroxy
groups are formed at the end of the chains.
The polyols based on polyurethanes have preferably an OH-number of 20 to
200. The ac;d number is preferably 10 to 200, especially perferred 25 to
150. The number average molecular weight (Mn) is preferably 3000 to
2~0000. In accordance with a preferred embodiment the water dispersable
polyurethane resins for component A) have an number-average molecular
weight of 3000 to 50000, an OH-number of 30 to 150 and an acid number of
to 70. Particularly preferred are carboxyl groups as groups
convertible into anionic groups.
Examples for polyols which can be used in accordance with the present
invention are hydroxy groups containing polyesters having anionic groups
as described in DE-A-32 13 160, DE-A-28 24 418 and US-A-3 053 783. In
accordance with the present invention it is possible to use linear or
branched oil-free polyesters on the basis of two valent or multi-valent
linear or branched aliphatic or cycloaliphatic saturated polyalcohols and
linear or branched al;phatic, cycloaliphatic or aromatic two valent or
multi-valent carboxylic acids which can be polycondensed with linear or
branched aliphatic monoalcohols.
Preferably the alcohols contain 2 to 21 C-atoms; the two valent or multi-
valent carboxylic acids contain preferably 5 to 10 C-atoms. Examples for
polyalcohols are diols, such 2.6-hexanediol, neopentilglycol, 2.2.4-
trimethylpentanediol-1.3 or 1.4-bis-(hydroxymethl)cyclohexane. Examples
for dicarboxylic acids are isophthalic acid, terephthalic acid, 1.3-
cyclohexanedicarboxylic acid or butylisophthalic acid. It is also
possible to use small amount of tricarboxylic acids or trialcohols or
polyalcohols in order to achieve branched structures. It is, e.g.,
possible to insert anionic groups additionally by reaction with a low
molecular dialcohol containing an acid group which can be transformed
into an anion, e.g. sulfonic acld groups, phosphoric acid groups or
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carboxyl groups. Particularly preferred are carboxyl groups, which, e.g.,
can be inserted by the use of dimethylolpropionic acid.
It is also possible to enhance the molecular weight of the polyesters by
reaction with diisocyanates. Further, it is possible to modify them via
reactive groups, e.g. OH-groups.
The polyesters which can be used in accordance with the present invention
have preferably a number-average molecular weight (Mn) from 1500 - 15000,
particularly preferred from 2000 - 6000. The OH-number is preferably 20
to 200, particularly preferred 40 to 150. The acid number is preferably
20 to 150.
The preparation of the polyesters can be carried out in accordance with
known processes. It is preferred to work stepwise. They can, e.g., be
prepared azeotropic or in a melt. The reaction temperature is, e.g., 150
to 240 C. After achieving of the desired parameters, it is optionally
possible to dilute the polyester with solvents in order to achieve a good
working viscosity.
The qualities of the polyesters can be inf`luenced by the used
dicarboxylic acids or polyalcohols. Thus, long chain aliphatic alcohols
enhance the flexibility of the polyesters; aromatic dicarboxylic acids
reduce the elasticity. The branching degree can be influenced by the
amount of used tricarboxylic acids. The water dispersability of the
binders is influenced by the amount of polar groups, e.g. OH-groups,
ether groups, urethane groups or ionic groups.
The polyols A) which can be used as binders in accordance with the
invention, can be transformed into the aqueous phase after neutralisation
of at least a part of the present ionic groups, without addition of
emulsifiers. The obtained aqueous systems can be real solutions, colloid
disperse systems or dispersions. It is possible that they still conta;n
small amounts of organic solvents from their preparation; however, such
organic solvents can also be added in order to improve specific qualities
such as flow or dispersability. It is possible to assist the
transformation into the aqueous phase by, e.g., enhancing the
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temperature. However, it is also possible to remove the organic solvents
by destillation from the aqueous dispersion.
The crosslinking component F) used in accordance with the invention
contains polyisocyanates which, on average, contain at least two free
isocyanate groups per molecule. Examples for such polyisocyanates are
described in EP-A-O 358 979. They are organic polyisocyanates, e.g.
diisocyanates, with aliphatic, cycloaliphatic and/or aromatic bound free
;socyanate groups, which are liquid at room temperature, which can also
be achieved by the addition of solvents.
The ready polyisocyanate component has a viscosity of 50 - 10000,
perferably 50 - 1000 mPas at 23 C. If necessary, it is possible to mix
different polyisocyanates. Further, it is also possible to add inert
solvents in order to reduce the viscosity to a desired degree. In order
to achieve this it is preferred to use solvents which are partly mixable
with water.
Examples of usable polyisocyanates are the known conventional lacquer
polyisocyanates such as, e.g., hexamethylene diisocyanate (HDI),
isophorone diisocyanate (IPDI), toluylene diisocyanate (TDI) and
tetramethyl xylylene diisocyanate (TMXDI). Such diisocyanates can be
transformed by known processes into oligomers, which, e.g. contain biuret
groups, urethane groups, uretdione groups or isocyanurate groups. It is
also possible to react them with lower alcohols, e.g. trimethylolpropane.
Polyisocyanates containing biuret groups on the basis of HDI as well as
the corresponding cyclic trimerisates of HDI are preferred. The use of
oligomers on the basis of TMXDI is also preferred. The isocyanates can
be used as such or in the form of mixtures. The average functionality is
2 or more.
The chlorinated polyolefines (CPO) which can be used as component B) in
accordance with the invention, are commercial products. They are, e.g.,
chlorinated polyethylene, chlorinated polypropylene or chlorinated
polyethylene/polypropylene copolymers or mixtures thereof. The
chlorinated polyolefines have a chlorination degree (a chlorine content)
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21~7 1
g
of 15 - 45 wt.-%. Generally they are dissolved in organic solvents.
However, it is also possible to use them in the form of an aqueous
dispersion.
A further object of the present invention are aqueous emulsions of
chlorinated polyolefines, which, e.g., can be prepared from a solvent-
containing form of the chlorinated polyolefine B) together with the water
dilutable polyol component A) (totally or partial) and optional water
and/or aromatic solvents. In this case the polyol component A) can be in
the form of a binder and can be disperged with the further components
with water, or it is possible to use an aqueous dispersion of the polyol.
This can be achieved by mixing the components with known disperging
apparatus; if desired it is possible to prepare a pre-emulsion which can
further be treated with disperging apparatus, e.g. rotor-stator-mixers,
impellers, such as propellers, ultrasonic mixers or high-pressure
homogenisators. Working in this way it is possible to omit emulsifiers.
It is also possible to start with CP0-powders without solvents and to add
the necessary amounts of aromatic solvents together with the water.
Examples for solvents are organic solvents having a boiling range of 100
to 160 C, especially aromatic solvents, such as toluene, xylene or
mixtures thereof.
Preferably the emulsions of the present invention have a content of 10
to 100 wt.-% of one or more aromatic solvents having a boiling range from
100 to 160 C, as exemplified above. The amount of CP0 is, e.g., 5 to 70
wt.-%, relating in each case to the polyol component. The emulsions of
the present invention are storage-stable products; no phase separation
occurs. It is possible to use them directly for the preparation of the
coating agents of the invention~ e.g. by direct addition to the coating
agents or to one or both components thereof.
The emulsion prepared in accordance with the invention can be used
directly for the preparation of the coating agents of the invention.
However, it is also possible to use other dispersions of chlorinated
polyolefines in the coating agents. Examples for usable dispersions of
chlorinated polyolefines (CP0) are described in DE-A-41 31 127. They are
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aqueous CPO-dispersions containing aromatic solvents and an anionic
emulsifier. Examples for the aromatic solvents are specified above. The
content of aromatic solvents is, e.g., 15 to 50 wt.-%. The described
aqueous solvent containing CPO-dispersions are prepared by disperging the
CPO in the form of a powder, slurry or an organic solution using an
emulsifier in water at an elevated temperature.
During the preparation of the polyol-containing emulsion of the presentinvention as well as during the preparation of the described emulsion
which is free from binders, it is possible to start with the preparation
of a pre-emulsion which is optionally added with water, further organic
solvents or adjuvants in order to achieve a suitable solids content and
which is further homogenized. The obtained dispersions have a good
distribution of the particle size in the aqueous phase. It is possible
to directly add the dispersions to the coating agent or to one or both
components thereof.
It is possible that the coating agents of the invention contain
additional water dilutable binders E) which essentially do not contain
any groups which can be crosslinked with the isocyanates under curing
conditions, e.g. water dilutable polyurethane resins or acrylate resins
or polyester resins. They are preferably aqueous polymer dispersions
which are admixed to the polyol of component A). The maximum amount of
such binders is 75 wt.-% relating to the reactive film-forming polyol.
Further, the coat;ng agents of the invention can contain conventional
lacquer additives such as defoaming agents, wetting agents, thickening
agents, anti cratering agents, flowing agents, light protective agents
or catalysts. The added substances shall be compatible with the component
to be admixed or they shall form a storage-stable form. If the necessary
amount of solvents cannot be inserted by the CPO-emulsion or by the
binders it is also possible to add further organic solvents to the
coating agents. They can be conventional lacquer solvents, especially
aromatic solvents which are known to the person skilled in the art. The
total amount is 5 to 40 wt.-%.
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The coating agents of the invention can also contain organic and/or
inorganic pigments or fillers. Examples are organic and inorganic
coloured pigments, effect pigments SUCil as metallic pigments, mica,
alluminium silicate, titanium dioxide, barium sulfate, high disperse
silica and corrosion protective pigments. It is also possible to add
crosslinked organic polymer particles as fillers. The pigments and/or
fillers have a preferred particle size of 15 ~m and less. This can be
achieved by grinding the pigments in auxiliary substances, e.g. paste
resins or wetting resins. The processes for disperging pigments are
described in the literature and are known to the person skilled in the
art.
In order to prepare the coating agents, the film-forming resins are
transformed in the aqueous phase. They can be totally or partially
neutralized before or after transformation into the aqueous phase, in
order to achieve a stable aqueous emulsion. The solvent-containing CPO-
composition is contained in the binder component as an aqueous solvent
containing a dispersion or as an emulsified organic solution; further
non- reactive aqueous binders can also be contained. This component can
contain optional adjuvants or pigments and fillers. If the pigments are
directly disperged into the aqueous binder composition, it is necessary
to take into consideration that the stability of the dispersion is not
impaired by the binding process. On the other hand, it is also possible
to add ground aqueous pigment compositions, e.g. so-called pigment
pastes, to the dispersion of binders.
The coating agents of the invention are two-component systems (2K-
systems).
The second component contains the polyisocyanate F). Other adjuvants,
e.g. defoaming agents, to achieve good lacquer effects, as well as
pigments, can also be contained in this component. It is also possible
to insert into this component at least a part of the CPO. Only such
components should be added to the polyisocyanates which are not reactive
with the isocyanate groups. It is possible to adjust the viscosity oF
this component by the addition of inert solvents.
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12
The coating agent is obtained ready for use by dispersing the poly-
isocyanate component into the aqueous dispersion of the binder component.
The amounts are chosen in such a way that the ratio of the amount o~
reactive NCO-groups to the amount of OH-groups is 0.5 : 1 to 5 : 1,
preferably 0.8 : 1 to 2 : 1. It is necessary to mix those components
well.
A preferred embodiment of the coating agents of the invention comprises
- 40 wt.-% of binder and crosslinking agent
0.5- 7 wt.-% of CPO
- 30 wt.-% of aromatic solvents
0 - 25 wt.-% of pigments and/or fillers
O - 15 wt.-% of further binders and
- 75 wt.-% of water.
Depending on the kind of application the coating agent can be adjusted
with water to a desired viscosity. The kind and amount of pigments and
fillers are chosen in accordance with the desired use. For primer
coatings the pigment content is high. For the use as a top coat the
pigment content is mostly within the lower range of amounts and the
pigments are coloured or effect pigments. Clear coats do not contain
pigments, however transparent colouring agents can be used.
The coating agents of the invention can be used on substrates such as
metals and plastic materials. Plastic substrates are especially
preferred. Examples are modified or non-modified polyolefines, especially
polyethylene or polypropylene, polycarbonate, polyamide, ABS-polymers,
polyurethanes or polyesters. Polyolefine substrates are preferred. It is
possible to use known processes for the application of the coating
agents, such as painting, rolling, spraying or dipping. The coating
agents can be applied directly to the purified substrate; it is not
necessary to use an adhesive primer. Preferably the thickness of the
layers is 5 - 75 ~m. However, surprisingly it has been found that even
with thick layers a smooth surface without blisters or pinholds is
achieved.
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21~'71
13
Crosslinking of the coating agents is achieved at temperatures of, e.g.
10 to 120^C, preferably 40 to 100 C. The crosslinking speed can be
influenced by addition of usual catalysts. If desired it is possible to
insert an aeration phase at low temperatures after application before
crosslinking by heating. The crosslinking temperature can be chosen in
accordance with the temperature sensibility of the substrate.
Homogenously coated substrates are achieved after crosslinking, e.g.
plastic substrates having a good adhesion between film and substrate. The
surface is smooth and free from defects even when preparing thick layers.
Also the adhesion to further coating layers is good. It is possible to
achieve thick layers without defects of the surface of the films by
blisters or sagging. The mechanical qualities of the coated material,
e.g. the impact resistance is not impaired, even when cold. ~he coating
agents are especially useful for the preparation of base-coat layers in
multi-layer systems. It is possible to apply one or more further
coatings, e.g. transparent coatings, stonechip-resistant coatings or base
coats/top coats to the thus obtained coatings. The achieved multi-layer
coating shall have a good adhesion at the substrate and a good elasticity
even when cold. They can be used without additional adhesion primer. A
further preferred embodiment comprises the use as a one-component top
coat. The coating agents of the invention are especially useful for
coating plastic pieces in the automotive industry or the industry
furnishing the automotive industry. However, they can also be used for
coating of other substrates, especially temperature sensitive plastic.
The following examples explain the invention. Percentages relate to the
weight unless stated otherwise.
ExamDle 1
29 wt.-% of a 25 % solution of a chlorinated polypropylene having a
chlorine content of 18 % in xylene are added to 66 % of a 26.5 %
dispersion of an acrylate resin (in accordance with example G of EP-A-0
358 979) and 5 % water. The mixture is homogenized thoroughly using a
propeller at 9O00 rpm at 23 C and using an eccentric geometry of
~ agitation. It has to be ensured that no unagitated zones remain in the
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14
material to be disperged. The CPO-solution is added slowly. (Solids
content ca. 25 %).
Example 2
50 wt.-% of an aqueous polyurethane dispersion (in accordance with DE-OS-
40 00 889 solids content 35 %) are added with 14 % water and slowly
mixed with 26 % of a 25 % solution of a chlorinated polypropylene having
a chlorine content of 18 % in xylene. The mixture is thorougly
homogenized with a propeller at ca. 9000 rpm at 23 C using an eccentric
geometry of agitation. The ex;stance of unagitated zones in the material
to be dispersed is to be avoided (solids content ca. 24 %). The obtained
aqueous solvent containing emulsions are storage-stable and they can be
used for the preparation of coating agents.
Preparation example 3
34.5 % of an aqueous acrylate resin (in accordance with example F) of
EP-A-O 358 979, solids content ca. 28 %) are mixed with 4.0 %
demineralized water and a premixture of 0.15 % of a commercial acrylate
thickener (Acrysol RM 8) and with 0.95 % water. 0.15 % of a commercial
ionic emulsifier and 0.15 % of a defoaming agent are added and
homogenized. 17.4 % titanium dioxidef 3.8 % talc and 0.05 % carbon black
are added successively into this mixture. The viscosity is adjusted with
ca. 1.75 % water and the mixture is grouned on a bead mill for 30
minutes.
This mixture is added slowly with a stable emulsion (in accordance withDE-A-41 31 127) from 9.65 % of a commercial CPO (solids content 25 % in
xylene), 0.65 % of an emulsifier on the basis of alkyl sulfonate and 9.0
% demineralized water. A storage-stable aqueous CPO/xylene containing
component is obtained.
Preparation example 4
32.35 % of an aqueous acrylate resin (in accordance with example F) of
EP-A-O 358 979, solid content ca. 28 %) are mixed with 3.9 %
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demineralized water and a premixture of 0.15 % of a commercial acrylate
thickener with 0.95 % water. 0.15 % of a commercial emulsifier and 0.15
% of a defoaming agent are added and homogenized. 16.3 % titanium
dioxide, 3.6 % talc and 0.05 % carbon black are successively disperged
into this mixture. The viscosity is adjusted with ca. 1.6 % water and the
mixture is ground in a bead mill for 30 minutes.
A stable emulsion of 15.1 % of a commercial CP0 (solids content 25 %
xylene), 1.0 % of an emulsifier on the basis of alkylsulfonate and 14.1
% demineralized water is slowly added to this mixture. A storage-stable
aqueous CP0/xylene-containing component is achieved.
preparation example 5
55.0 % of an emulsion according to example 1 are mixed with a premixture
of 0.15 % of a commercial acrylate thickener with 0.95 % water. 0.1 % of
a commercial ionic emulsifier, 0.2 % of a defoaming agent and 1.8 % water
are added and homogenized. 17.0 % titanium dioxide, 3.8 % talc and 0.05
% carbon black are successively disperged into this mixture. The
viscosity is adjusted with ca. 1.5 % water and the mixture is ground in
a bead mill for 30 minutes.
Example 6
82.2 % of the component of example 3 are mixed with 11.2 % of a solution
of 4.65 % of a mixture of aliphatic hydrocarbons and 6.65 % of a mixture
of oligomer biuret and isocyanurate-group containing HDI-condensation
products having a NC0-content of 22 %; the resultant mixture is
homogenously agitated. An application viscosity is achieved by adjusti~g
with 6.6 % water.
Example 7
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89.4 % of the component according to example 4 are mixed with 9.3 % of
a solution of 3.0 % of a mixture of aliphatic hydrocarbons and 6.3 % of
a mixture of oligomeric biuret and isocyanurate group containing HDI-
condensation products having a NC0-content of 22 % and the mixture is
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homogenously stirred. 1.3 % so~vent are adm;xed in order to adjust
application viscosity.
Example 8
80.4 % of the component of examp~e 5 are added with 5.9 % of a mixture
of oligomeric biuret and isyocyanurate group containing HDI-condensation
products having a NC0-content of 22 %; the obtained mixture is
homogenously stirred. 13.65 % water are added in order to adjust
application viscosity.
Adhesion primer tests:
The resultant primer coatings are sprayed onto a plastic substrate
(Hostalen PPX 653 of Hoechst AG) which had been degreased, in order to
achieve a dry film thickness of ca. 25 ~m. The film is aerated for 15
minutes and then dried for 15 minutes at 80 C. Then a further
conventional coating system is applied.
Multilayer system: 25 ~m 2K-primer according to examples 6 to 8
15 ~m commerical water base coat (Diamantsilber 65
120 of Herberts GmbH)
35 ~m commercial two-component polyurethane clear
lacquer (47 891 of Herberts GmbH)
The tests of humidity resistance (DIN 50017, condensed water test
climate, adhesion to the following layers) and the elasticity at a
flexural test even at -20 C (DIN 53152 or IS0 6860, adhesion to the
substrate) demonstrate good results.
A comparative test was carried out in analogy with example 4, however
omitting the CP0-polymer in the coating agent. This test demonstrated an
essentially worse result of the adhesion test.
` Example 9
36.9 % of an aqueous acrylate dispersion (Bayhydrol VPLS 2940, solids
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content 30 %) are mixed under agitation with 7.4 % demineralized water,
1.3 % of a commercial acrylate thickener, 0.15 % of a commercial
emulsifier and 0.25 % of a commercial defoaming agent, whereafter the
mixture is mixed with 22.2 % titanium dioxide. This mixture is
homogenously stirred and ground in a bead mill. 25.2 % of a commercial
CP0 (20 % in xylene) are added to this mixture and homogenized.
The thus obtained binder mixture is mixed with 6.6 % of a commercial
mixture of oligomeric HDI-condensation product having a NC0-content of
22 % and the obtained composition is homogenously mixed. The viscosity
for application is achieved by the addition of a low amount of water.
The thus obtained topcoat agent is sprayed onto a degreased plastic
substrate in order to achieve a dry-film thickness of ca. 40 ~m. The film
is aerated for 15 minutes and then dried for 15 minutes at 80 C.
The elasticity is tested by a flexural test (IS0 6860 or DIN 53152).
The adhesion to the substrate is good.
The adhesion to the substrate is clearly better than with a comparative
test being carried out without the CP0-solution.
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