U.S. patent application number 13/140338 was filed with the patent office on 2011-11-17 for powder coating compositions for low temperature curing and high flow.
Invention is credited to Damiano Beccaria, Imir Bejko, Andrea Capra, Alessandro Munari, Irene Panero.
Application Number | 20110281972 13/140338 |
Document ID | / |
Family ID | 40599959 |
Filed Date | 2011-11-17 |
United States Patent
Application |
20110281972 |
Kind Code |
A1 |
Beccaria; Damiano ; et
al. |
November 17, 2011 |
POWDER COATING COMPOSITIONS FOR LOW TEMPERATURE CURING AND HIGH
FLOW
Abstract
The present invention relates to powder coating compositions and
to components and ingredients for incorporation therein, suitable
for low temperature curing schedule and with excellent resistance
to outside aging. The powder coating composition can be cured at a
temperature from 140.degree. C. to lead to a coating with excellent
flow and high gloss.
Inventors: |
Beccaria; Damiano; (Bene
Vagienna, IT) ; Bejko; Imir; (Stura, IT) ;
Capra; Andrea; (Stura, IT) ; Panero; Irene;
(Stura, IT) ; Munari; Alessandro; (Stura,
IT) |
Family ID: |
40599959 |
Appl. No.: |
13/140338 |
Filed: |
December 14, 2009 |
PCT Filed: |
December 14, 2009 |
PCT NO: |
PCT/EP2009/008928 |
371 Date: |
July 29, 2011 |
Current U.S.
Class: |
523/400 ;
524/589; 524/605 |
Current CPC
Class: |
C08G 63/48 20130101;
C09D 167/08 20130101; C09D 167/02 20130101 |
Class at
Publication: |
523/400 ;
524/605; 524/589 |
International
Class: |
C09D 163/00 20060101
C09D163/00; C09D 163/04 20060101 C09D163/04; C09D 175/00 20060101
C09D175/00; C09D 167/03 20060101 C09D167/03 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 19, 2008 |
EP |
08075956.6 |
Claims
1. A powder coating composition comprising a polyester resin which
comprises (1) Polyols, (2) Diacids, (3) Fatty acids. and from 4 to
65 weight percent of a curative and additives, wherein the weight
percent is based on the total weight of the polyester resin and
curative.
2. The powder coating composition of claim 1 wherein the polyester
resin comprises (1) 0.1 to 60 weight percent of mono or
poly-functional saturated or unsaturated fatty acids or mixtures
thereof, (2) 30 to 60 weight percent of an aromatic diacid or
cycloalkyl diacids or anhydrides thereof, (3) 20 to 30 weight
percent of aliphatic diol, (4) 0 to 6 weight percent of aliphatic
triol, (5) 0 to 10 weight percent of isosorbide and isomers or
cycloalkyl diol, (6) 0 to 10 weight percent of C.sub.3-C.sub.12
aliphatic diacid, and with total weight percent of the monomers
equal to 100.
3. The powder coating composition of claim 1 wherein an
acid/alcohol mole ratio is higher than 1 and with an acid value of
higher than 15 mg KOH/g.
4. The powder coating composition of claim 3 wherein the
acid/alcohol mole ratio in lower that 1 and with a hydroxyl value
of higher than 25 mg KOH/g.
5. The powder coating composition of claim 1 wherein the polyester
resin comprises: (1) 0.5 to 30 weight percent of mono or
poly-functional saturated or unsaturated fatty acids of mixtures of
them, (2) 30 to 60 weight percent of an aromatic diacid or
cycloalkyl diacid or anhydride, (3) 20 to 30 weight percent of
aliphatic diol, (4) 0 to 6 weight percent of aliphatic triol, (5) 0
to 10 weight percent of isosorbide and isomers or cycloalkyl diol,
(6) 0 to 10 weight percent of C.sub.3-C.sub.12 aliphatic diacid,
and with total weight percent of the monomers equal to 100.
6. The powder coating composition of claim 2 wherein the aromatic
diacid, cycloalkyl diacid or anhydride thereof is selected from the
group consisting of isophthalic acid (IPA), terephthalic acid
(TPA), phthalic anhydride (PA), trimellitic anhydride (TMA),
furandicarboxylic acid (FDCA), cyclohexandicarboxilic acid (CHDA),
hexahydrophtalic anhydride (HHPA) and combinations thereof.
7. The powder coating composition of claim 1 wherein the melt
viscosity (ICI) at 200.degree. C. of the polyester resin is from
1500 to 12000 mPas and a Tg of above 44.degree. C. but lower than
70.degree. C.
8. The powder coating composition of claim 3 wherein the curative
is selected from a non-isocyanurate polyepoxide or
beta-hydroxyalkylamide or triglycidyl-isocyanurate or epoxy resins
(glycidyl ethers of Bisphenol A & F or epoxy novolac resins,
glycidyl esters and mixtures thereof) in a weight percent (on total
polyester resin and curative) of 2.5-50.
9. The powder coating composition of claim 4 wherein the curative
is selected from trimer of isophorone diisocyanate, trimer of
hexamethylene diisocyanate, caprolactam-blocked polyisocyanate or
self blocked uretdiones in a weight percent (on total polyester
resin and curative) of 10 to 65.
10. The powder coating composition of claim 7 wherein the cure
temperature is lower than 180.degree. C. and higher than
100.degree. C.
11. A coated article comprising the polymeric composition of claim
10 in a cured film.
Description
[0001] This application claims the benefit of PCT Application
PCT/EP2009/008928 with International Filing Date of Dec. 14, 2009,
published as WO 2010/069531 A1, which further claims priority to
European Patent Application No. 08075956.6 filed Dec. 19, 2008, the
entire contents of both are hereby incorporated by reference.
[0002] The present invention relates to powder coating compositions
and to components and ingredients for incorporation therein,
suitable for low temperature curing schedule, with excellent flow
of the coating, good flexibility, no blooming phenomenon and
resistance to outside aging.
[0003] Powder coating technology is generally a well-known and well
defined art and has significant advantages over "wet" technologies
for painting and spraying. The principle behind thermoset powder
coating decoration is that the powder coating is formulated by
dispersing coloring agents or pigments within a matrix of
cross-linkable material, grinding the material to a powder,
applying the powder to a surface to be coated and then heating or
baking to cause the powder particles to coalesce to form a layer on
the surface to be decorated and thereafter causing or allowing
curing or crosslinking to take place to form a thermoset layer.
Based on these principles the skilled artisan is always searching
the best compromise between cure/production cost and appearance of
the thermoset coating. Recently, the industry has showed an
interest in lower curing temperature for environmental and
economical reasons.
[0004] A major challenge in the development of powder coatings, for
this purpose, is the need to satisfy a number of seemingly
conflicting requirements. One of the essential requirements of a
powder coating is that it should be curable/cross-linkable. In the
majority of cases this means the incorporation of a cross-linking
agent and the increase of the melt viscosity over the bake period.
It is desirable that the baking should be as efficient as possible
to minimize energy costs. The flow of the coating is determined by
the viscosity build-up of the thermosetting composition during the
curing, if the increase of viscosity occurs at a too early stage in
the baking process, it will have as result that the powder
particles will not have fully coalesced and "leveled". This will
result in the production of an article with an unacceptable finish,
usually characterized by "orange peel".
[0005] A thermosetting powder coating with outstanding properties
for exterior end applications is typically based on a polyester
resin. Polyester powder coatings are typically formulated with
polyepoxide or beta hydroxyalkyl amide type cross-linking
compounds. The technology surrounding these materials is generally
well known and has been discussed and considered in a number of
articles and prior patent specifications.
[0006] Attempts have thus been made to design polyester resins
bearing carboxyl groups with a reduced initial melt viscosity
and/or the reactivity of the thermoset composition or by the use of
additives.
[0007] Patent EP 0 322 834, for example, describes thermosetting
powder compositions essentially containing a polyester bearing
carboxyl groups and a beta-hydroxyalkylamide, which is applied to a
substrate and is then crosslinked at a temperature of 160 to
200.degree. C. Despite the presence of benzoin as additive in these
compositions, which is added as degassing agent, the bubbles of
water and air remain trapped in the hardened coating after it has
melted and crosslinked, especially if the coating is relatively
thick. In addition, the flow of the powder when it melts is not
optimal.
[0008] Patent application WO 91/14745 describes thermosetting
powder compositions containing an amorphous polyester containing
carboxyl groups, a semi-crystalline polyester containing carboxyl
groups and a crosslinking agent. 10 to 40% by weight of the
semi-crystalline polyester is preferably used relative to the
polyesters as a whole, and the crosslinking agent can be a
beta-hydroxyalkylamide. The presence of the semi-crystalline
polyester in these compositions improves the mechanical properties
of the coatings they provide. However, the presence of these
semi-crystalline polyesters also increases the rate of hardening of
these compositions, which could be a factor which disfavors the
satisfactory flowing and degassing of these compositions when they
melt, leading to surface defects in the coatings.
[0009] Patent application EP 0 668 895 also describes thermosetting
powder compositions containing a polyester bearing carboxyl groups
and a beta-hydroxyalkylamide. The polyesters of that patent
application have a functionality of carboxyl groups of less than 2,
obtained by adding monofunctional acids or alcohols during the
synthesis of the polyester. By virtue of this reduced
functionality, the polyester is less reactive, which makes the
powder flow better when it melts and allows the bubbles of air and
of water vapor to escape from the coating before it hardens, unlike
the compositions in patent applications EP 0 322 834 and WO
91/14745. However, since the polyester contains chain ends which do
not bear a reactive group, these ends do not participate in the
formation of the three-dimensional network during the crosslinking
of the powder, thus reducing the resistance to solvents and the
flexibility of the coatings thus obtained.
[0010] The EP 1 054 917 claims to solve the above drawbacks of
using a beta-hydroxyalkylamide as crosslinker by incorporation of
tertiary carboxyl groups as reactive groups in the polyester
resins. The said compositions provide coatings with excellent
surface appearance, good flexibility and good resistance to poor
weather conditions due to the lower reactivity and which induces a
longer cure schedule.
[0011] As can be appreciated, it is not easy to find a
thermosetting powder composition which by itself combines all the
qualities which it would be desired to find therein, such as good
stability in storage, good flowing when melting in order to give it
a smooth, and glossy appearance which has no orange-peel skin or
bubbles, good flexibility, at the same time as good resistance to
solvents, to aggressive weather exposure and all of this at a low
temperature curing.
[0012] The present invention seeks to provide powder coating
compositions exhibiting low temperature curing but which fulfill
the quality requirement of coating such as flow, flexibility and
HSE legislations.
[0013] We have found, surprisingly, that low temperature cure and
good flow could be achieved, provided that the polyester resin
composition comprises: [0014] (1) Polyols, [0015] (2) Diacids,
[0016] (3) Fatty acids.
[0017] According to one aspect of the present invention there is
provided a polymeric composition suitable for use as a vehicle for
a powder coating composition which comprises: a composition in that
the acid/alcohol mole ratio is higher than 1 and with an acid value
of higher than 15 mg KOH/g.
[0018] According to another aspect of the present invention there
is provided a polymeric composition suitable for use as a vehicle
for a powder coating composition which comprises: a composition of
in that the acid/alcohol mole ratio is lower that 1 and with a
hydroxyl value of higher than 25 mg KOH/g.
[0019] A preferable composition in that polyester resin comprises:
[0020] (1) 0.1 to 60 weight percent of mono or poly-functional
satured or unsatured fatty acids of mixtures of them, [0021] (2) 30
to 60 weight percent of an aromatic diacid or cycloalkyl diacids or
anhydride, [0022] (3) 20 to 30 weight percent of aliphatic diol,
[0023] (4) 0 to 6 weight percent of aliphatic triol, [0024] (5) 0
to 10 weight percent of isosorbide and isomers or cycloalkyl diol,
[0025] (6) 0 to 10 weight percent of C.sub.3-C.sub.12 aliphatic
diacid, and [0026] with total weight percent of the monomers equal
to 100.
[0027] A more preferred composition in that polyester resin
comprises [0028] (1) 0.5 to 30 weight percent of mono or
poly-functional satured or unsatured fatty acids of mixtures of
them, [0029] (2) 30 to 60 weight percent of an aromatic diacid or
cycloalkyl diacid or anhydride, [0030] (3) 20 to 30 weight percent
of aliphatic diol, [0031] (4) 0 to 6 weight percent of aliphatic
triol, [0032] (5) 0 to 10 weight percent of isosorbide and isomers
or cycloalkyl diol, [0033] (6) 0 to 10 weight percent of
C.sub.3-C.sub.12 aliphatic diacid, and [0034] with total weight
percent of the monomers equal to 100.
[0035] The above composition with the aromatic diacid, cycloalkyl
diacid or anhydride selected from the group consisting of
isophthalic acid (IPA), terephthalic acid (TPA), phthalic anhydride
(PA), trimellitic anhydride (TMA), furandicarboxylic acid (FDCA),
cyclohexandicarboxilic acid (CHDA), hexahydrophtalic anhydride
(HHPA).
[0036] The melt viscosity (ICI) at 200.degree. C. of the polyester
resin is from 1500 to 12000 mPas and a Tg of above 35.degree. C.
but lower than 70.degree. C.
[0037] The powder formulation based on the above acid functional
polyester resin is then combined with a curative selected from a
non-isocyanurate polyepoxide or beta-hydroxyalkylamide or
triglycidyl-isocyanurate or epoxy resins (glycidyl ethers of
Bisphenol A & F or epoxy novolac resins, glycidyl esters and
mixtures thereof) in a weight percent (on total polyester resin and
curative) of 2.5 to 50.
[0038] Another aspect of the invention is that when the polyester
resin has an hydroxyl functionality the curative is selected from
trimer of isophorone diisocyanate, trimer of hexamethylene
diisocyanate, caprolactam-blocked polyisocyanate or self blocked
uretdiones in a weight percent (on total polyester resin and
curative) of 8 to 65.
[0039] Slight variations above and below the stated ranges can be
used to achieve substantially the same results as values within the
ranges. Also, the disclosure of the ranges is intended as a
continuous range including every value between the minimum and
maximum values.
[0040] In the tables 1, 2, 3 and 4 below, we compared the polyester
recipes and final resin physical and chemical properties for
different curative systems.
[0041] In table 5 below, we listed the powder coating formulations
in Primid (93/7 and 95/5 ratios) and TGIC systems.
[0042] In the tables 6, 7 and 8 the application performances of the
previous powder coatings in three different curing conditions: 10'
@ 180.degree. C., 10' @ 160.degree. C. and 30'@ 140.degree. C. are
given.
[0043] In the application tests at 10'@160.degree. C. curing
condition (table 7) we disclosed worse results for 95/5 than for
93/7 Primid system, particularly in flexibility and for TGIC system
for coating appearance and toxicological labeling.
[0044] In table 8, we compared some 93/7 Primid system powder
coatings in the most demanding curing condition: 30'@140.degree. C.
Comparative examples I, L, M are conventional resins and examples
1, 2, 3, 4, 5 are formulations with fatty acids to prove better low
temperature cure performance results.
[0045] The polymeric vehicle of the invention is formulated to
provide a coating binder with desirable hardness, flexibility,
solvent resistance, corrosion resistance, weatherability and gloss.
The enhancement of these properties depends on the optimization and
balancing of factors including monomer composition, T.sub.g of the
resin, type and amount of crosslinking agent, curing conditions,
curing catalysts, and type and amount of pigments, fillers and
additives. The reactivity is increased without sacrificing chemical
storage stability or causing poor flow of the film.
[0046] The coatings compositions of this invention exhibit
remarkable storage stability, smooth surface appearance, high
gloss, and excellent mechanical properties which are maintained
over time. It will be appreciated by skilled people in the powder
coating industry, that an excellent balance among stability and the
flow of the cured film and weather-ability and mechanical
properties imparted by the use of compositions in accordance with
the invention are important factors of commercial importance.
[0047] The powder coating compositions of the invention are cured
at a temperature lower than 180.degree. C. and higher than
100.degree. C. and preferably between 160.degree. C. and
140.degree. C.
[0048] As used herein "coating binder" is the polymeric portion of
a coating film after baking and after crosslinking.
[0049] "Polymeric vehicle" means all polymeric and resinous
components including crosslinking agents in the formulated coating;
i.e. before film formation. Pigments and additives may be mixed
with the polymeric vehicle to provide a formulated powder coating
composition.
[0050] "Diol" is a compound with two hydroxyl groups. "Polyol" is a
compound with two or more hydroxyl groups.
[0051] "Diacid" is a compound with two carboxyl groups. "Polyacid"
is a compound with two or more carboxyl groups.
[0052] As used in this application, "polymer" means a polymer with
repeating monomeric units as defined herein.
[0053] A "film" is formed by application of the formulated coating
composition to a base or substrate, and crosslinked.
[0054] Acid number or acid value means the number of milligrams of
potassium hydroxide required for neutralization of free acids
present in 1 g of resin. Hydroxyl number of value that is also
called acetyl value is a number that indicates the extent to which
a substance may be acetylated; it is the number of milligrams of
potassium hydroxide required for neutralization of the acetic acid
liberated on saponifying 1 g of acetylated sample.
[0055] The polyesters useful in the practice of the invention are
thermosettable carboxyl terminated polymers, suitable for
formulation of thermosetting powder coatings with epoxide bearing
compounds or beta-hydroxyalkylamide. This implies that the
polyesters have a sufficiently high glass transition temperature to
resist sintering when in powder form and subjected to normally
encountered field conditions. The polyester of the present
invention has a glass transition temperature T.sub.g greater than
or equal to 44.degree. C., when determined by differential scanning
calorimetry employing a heat-up rate of 10.degree. C. per minute in
a nitrogen atmosphere; the value is taken at the second run.
[0056] As the number average molecular weight of the carboxylated
polyester and the hydroxyl value of the hydroxyl terminated
polyester vary, the number of equivalents of diacid necessary to
react with the hydroxyl terminated polyester also will vary. The
resulting carboxyl terminated polyester has an acid value in the
range of from 14 to 60, and a number average molecular weight in
the range of from 2000 to 15000.
[0057] For the preparation of the thermosetting powder compositions
of the invention, the polyester and the curing compound and various
auxiliary substances conventionally used for the manufacture of
powder paints and varnishes are mixed homogeneously. This
homogenization is carried out for example by melting the polyester,
the polyepoxide compound and the various auxiliary substances at a
temperature within the range of from 90 to 100.degree. C.,
preferably in an extruder, for example a Buss-Ko-Kneader extruder
or a twin-screw extruder of the Werner-Pfleiderer or Baker Perkins
type. The extrudate is then allowed to cool, and is ground and
sieved to obtain a powder, having a particle size of 10 to 120
micrometers.
[0058] The auxiliary substances which can be added to the
thermosetting compositions according to the invention include
ultraviolet light absorbing compounds such as Tinuvin 928 (from
CIBA--Specialties Chemicals), light stabilizers based on sterically
hindered amines (for example Tinuvin 144 from CIBA--Specialties
Chemicals), phenolic antioxidants (for example Irganox 1010 from
CIBA--Specialties Chemicals) and stabilizers of the phosphonite or
phosphite type (for example Irgafos 168 or P-EPQ from
CIBA--Specialties Chemicals) (Tinuvin, Irganox, Irgafos are
Trademarks). A variety of pigments may also be added to the
thermosetting compositions according to the invention. Examples of
pigments that may be employed in the invention are metal oxides
such as titanium dioxide, iron oxide, zinc oxide and the like,
metal hydroxides, metal powders, sulfides, sulfates, carbonates,
silicates such as aluminum silicate, carbon black, talc, china
clays, barytes, iron blues, lead blues, organic reds, organic
maroons and the like. Auxiliary substances may also include flow
control agents such as Fluidep F 630 (from COMIEL) Resiflow PV88
(from WORLEE), Modaflow (from Cytec), Acronal 4F (from BASF)
(Fluidep, Resiflow, Modaflow, Acronal are trademarks) plasticizers
such as dicyclohexyl phthalate, triphenyl phosphate, grinding aids,
degassing agents such as benzoin and fillers. These auxiliary
substances are added in conventional amounts, it being understood
that if the thermosetting compositions of the inventions are used
as clear coatings, opacifying auxiliary substances should be
omitted.
[0059] The ground powder paint composition may be applied to the
substrate by any of the known means of application. After coating,
the deposited layer is cured by heating in an oven. While typically
curing is effected at a temperature of 180.degree. C. in order to
obtain sufficient crosslinking to provide the required coating
properties, the compositions of the invention may be cured at lower
temperature, for example by maintaining a temperature 160.degree.
C. or even 140.degree. C. The decrease of curing temperature is
economically and technically advantageous since it permits to save
energy costs and it offers the possibility to work with substrate
that are less thermal resistant than steel.
[0060] Another advantage of the invention is that the coatings
prepared from the compositions containing the polyesters according
to the invention have a combination of outstanding properties.
Improving the appearance of coatings applied as powders to be
equivalent to the quality liquid coating finishes is an important
consideration, and the present invention provides coatings with
excellent appearance. While conventional coatings can be applied as
relatively low viscosity liquids to give smooth films after removal
of water and/or solvents, applied powder particles must melt, flow,
wet the substrate, and coalesce and level to form a continuous
film. The polymeric vehicle of the present invention is effective
for providing a stable melt viscosity and flow.
[0061] While solvent/water based coatings can utilize polymer
systems with a T.sub.g even below room temperature, the T.sub.g of
a coating powder resin must be above 45.degree. C. in order to
possess acceptable non sintering characteristics. If the T.sub.g of
the coating is high enough, sintering can be avoided. However,
coalescing and leveling at the lowest possible temperature are
promoted by reducing T.sub.g. If the stability of the formulated
composition is to be maintained in storage without partial curing,
then the T.sub.g must be maintained at a sufficient level, i.e.
greater than 44.degree. C. The present invention optimizes T.sub.g
in combination with other factors to provide good coalescence and
leveling of the coating prior to cure, whilst not sacrificing
storage stability of the formulated powder coating.
[0062] The following examples should be understood to be
illustrative of the scope of the invention, which is defined in the
appended claims.
[0063] The present invention is further defined in the following
examples. It should be understood that these examples are given by
way of illustration only. From the above discussion and these
examples, one skilled in the art can ascertain the essential
characteristics of this invention, and without departing from the
spirit and scope thereof, can make various changes and
modifications of the invention to adapt it to various uses and
conditions. As a result, the present invention is not limited by
the illustrative examples set forth herein below, but rather is
defined by the claims contained herein below.
GENERAL PREPARATION PROCEDURE
Example a (Composition According to the Invention)
Single-Stage Synthesis of Carboxyl and Hydroxyl Resin:
[0064] First stage 27.0 parts of D-Isosorbide are placed in a flask
under nitrogen and with stirring with 11.4 parts of neopentilglycol
90%, 7.3 parts of terephthalic acid, 30.9 parts of isophtalic acid,
3.4 parts of adipic acid, 19.9 parts of satured 80/20 dimer/trimer
fatty acid and 0.1 part of MBTO as catalyst and heated to
245.degree. C. The reaction is continued at 245.degree. C. until
the distillation under atmospheric pressure stops then the content
of the flask is placed under vacuum (residual pressure 50 mmHg)
until the polyester obtained has the following characteristics:
Acid number 34.2 mg KOH/g, ICI viscosity at 200.degree. C. 3280
mPas, Tg (DSC; 10.degree. C./min) 53.degree. C., Mw 11348 and
Gardner Holdt color as a 50 wt. % solution in
N-methyl-2-pyrrolidone is 3.
[0065] Accordingly to the procedure as described for the example a,
the polyesters of examples b, c, d, e, f, g and h are prepared
(compositions and properties are given in Tables 1 and 2).
Example I
Two-Stage Synthesis of Carboxyl Resin:
[0066] First stage 36.6 parts of neopentilglycol 90% are placed in
a flask under nitrogen and with stirring with 1.9 parts of
Trimethylolpropane, 42.6 parts of terephthalic acid, 5.4 parts of
isophtalic acid, 0.1 part of MBTO as catalyst and heated to
245.degree. C. The reaction is continued at atmospheric pressure
until a prepolymer containing hydroxyl groups is thus obtained
which has the following characteristics: acid number mg KOH/g, ICI
viscosity at 200.degree. C. 605 mPas. Second stage 4.8 parts of
adipic acid, 8.4 parts of isophthalic and 0.2 parts of
trimethylolpropane are added at 220.degree. C. to the prepolymer
obtained in the first stage. The reaction is continued at
245.degree. C. until the distillation under atmospheric pressure
stops then the content of the flask is placed under vacuum
(residual pressure 50 mmHg) until the polyester obtained has the
following characteristics: Acid number 49.4 mg KOH/g, ICI viscosity
at 200.degree. C. 4020 mPas, Tg (DSC; 10.degree. C./min) 58.degree.
C., Mw 13673 and Gardner Holdt color as a 50 wt. % solution in
N-methyl-2-pyrrolidone of less than 1.
[0067] Accordingly the procedure as described in the example I, the
polyesters of examples L, M, 1, 2, 3, 4 and 5 are prepared
(compositions and properties are given in Tables 3 and 4). The
examples I, L, M are compositions according the prior art and the
examples 1 to 5 are compositions according to the invention.
TABLE-US-00001 TABLE 1 Resin composition of examples a, b, c, d, e,
f, g and h according to the invention a b c d e f g h D-isosorbide
27.0 37.2 37.2 28.6 18.7 18.7 18.7 26.3 MEG 0 0.0 0.0 5.9 9.6 9.6
9.6 0 Trimethylolpropane 0.0 0.0 0.0 0.7 0.8 0.8 0.8 4.7
neopenthylglycol 90% 11.4 0.0 0.0 0.0 0.0 0.0 0.0 10.6 terephthalic
acid 7.3 0.0 0.0 40.5 38.6 38.6 38.6 7.1 isophthalic acid 30.9 0.0
0.0 0.0 0.0 0.0 0.0 29.4 CHDA 0.0 43.3 43.3 0.0 0.0 0.0 0.0 0
Lauric Acid 0.0 0.0 0.0 7.5 0.0 0.0 0.0 0 Unsatured dimer fatty 0
19.1 19.1 13.2 0.0 0.0 0.0 0 acid Satured dimer/trimer 19.9 0.0 0.0
0.0 0.0 0.0 27.6 19.2 fatty acid Unsatured dimer/trimer 0.0 0.0 0.0
0.0 0.0 27.6 0.0 0 fatty acid Satured dimer fatty 0.0 0.0 0.0 0.0
27.6 0.0 0.0 0 acid Adipic acid 3.4 0.0 0.0 0.0 0.0 0.0 0.0 2.6 TNH
0.0 0.4 0.4 0.0 0.0 0.0 0.0 0 MBTO 0.1 0 0 0.1 0.1 0.1 0.1 0.1 N.A.
(mgKOH/g) * 34.2 33.2 33.2 27.4 20.1 24.5 24.9 8.7 NOH(mgKOH/g) **
12.5 9.5 9.5 n.a 4.5 3.5 5.4 61.4 ICI Vix at 200.degree. C. 3280
12000 12000 6000 4350 4380 4260 7300 (mPa s) * acid value; **
Hydroxyl value
TABLE-US-00002 TABLE 2 Properties of the examples a, b, c, d, e, f,
g and h Appearance clear clear clear clear clear clear clear clear
Colour 50% DMF 3 9 9 8 3 7/8 3 2/3 Gel Time 180.degree. C. * 2'29''
n.a n.a 3'00'' 2'50'' 2'50'' 1'53'' 5'50'' Primid Epoxy Epoxy Epoxy
Epoxy NCO 95/5 60/40 60/40 60/40 60/40 Tg (DSC) midpoint (.degree.
C.) 53.4 51 51 56.5 45.9 51.5 51.6 44.3 Mw 11348 13108 13108 9316
17606 18196 17680 90421 * gel time from blend resin/curative. Epoxy
= solid Bisphenol A epoxy resin, NCO = blocked isocyanate
TABLE-US-00003 TABLE 3 Resin composition of comparative examples I,
L, M, and examples 1-5 according to the invention. Comparatives
Invention Polyester resin I L M 1 2 3 4 5 1.sup.st stage CHDM 0 0 0
0 0 6.1 0.0 0 D-isosorbide 0 0 0 5 5.7 0 0.0 0 Trimethylolpropane
1.9 1.9 1.1 0.9 0.8 0.9 0.5 0.5 neopenthylglycol 90% 36.6 36.7 38
30.3 30.7 29.5 36.9 37.4 terephthalic acid 42.6 36.7 34.6 34.9 35.7
38.4 37.6 38 isophthalic acid 5.4 11.1 19.5 11 9 8.1 7.9 8.0 MBTO
0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 N.A. (mgKOH/g) 10 10 8.6 9.1 9.3
9.6 6.5 7.3 ICI Vix at 200.degree. C. 650 650 360 1260 730 880 1000
800 (mPa s) 2.sup.nd stage adipic acid 4.8 4.8 6.7 2.1 0 0 0.0 0
isophthalic acid 8.4 8.4 0 7.2 9.6 12.3 12.0 12.3 Satured
dimer/trimer 0 0 0 8.5 8.4 4.4 4.3 0 fatty acid Lauric acid 0 0 0 0
0 0 0 3 Trimethylolpropane 0.2 0.3 0 0 0 0.2 0.7 0.7 CHDM:
cyclohexane dimethanol CHDA: cyclohexane diacid
TABLE-US-00004 TABLE 4 Properties of the comparative examples I, L,
M, examples 1-5 and examples a, b and c according to the invention
PRIMID 93/7 PRIMID 93/7 PRIMID 95/5 TGIC Comparatives Invention
Invention Inv. Polyester resin I L M 1 2 3 4 5 a b c Appearance
clear clear clear clear clear clear clear clear clear clear clear
Colour 50% DMF <1 <1 <1 4/5 4 4 2 2 3 9 9 Acid value 49.4
50.7 51.1 49.8 53.2 51.6 50.7 50.2 34.2 33.2 33.2 Viscosity C&P
4020 4000 1820 2430 2850 3330 2600 2360 3280 12000 12000
200.degree. C. (mPa s) Gel Time 180.degree. C. * 1'34'' 1'20''
2'26'' 1'40'' 1'29'' 2'20'' 1'55'' 2'40'' 2'29'' n.a n.a Tg (DSC)
midpoint 58 54 51.3 52.4 58.1 62 58.6 53.1 53.4 51 51 (.degree. C.)
Mw 13673 14900 n.d. 11137 9914 10128 12294 10893 11348 13108 13108
* gel time from blend resin/curative
TABLE-US-00005 TABLE 5 Powder formulations Comparatives Invention
Polyester resin I L M 1 2 3 4 5 a b c Polyester resin weight 302.2
302.2 302.2 302.2 302.2 302.2 302.2 302.2 308.7 451.2 398.0 Primid
XL 552 22.8 22.8 22.8 22.8 22.8 22.8 22.8 22.8 16.3 23.8 0.0 TGIC
33.0 Masterbatch TEP 0.0 44.0 Resiflow PV 88 5.0 5.0 5.0 5.0 5.0
5.0 5.0 5.0 5.0 7.3 7.3 Benzoin 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0
2.0 2.0 Kronos 2160 168 168 168 168 168 168 168 168 168 1.7 1.7
Hostaperm yellow H3G 9.2 9.2 Hostaperm Green GNX 1.4 1.4 Colortherm
10 3.4 3.4 Total Weight 500 500 500 500 500 500 500 500 500 500 500
Polyester/Crosslinker 93:7 93:7 93:7 93:7 93:7 93:7 93:7 93:7 95:5
95:5 93:7 Pigment/Binder 35:65 35:65 35:65 35:65 35:65 35:65 35:65
35:65 35:65 5:95 5:95 Stability 24 h at 40.degree. C. good- good-
bad good--- good good+ good good- good- good-- good--
TABLE-US-00006 TABLE 6 Coating properties cured 10 min at
180.degree. C. Comparatives Invention Polyester Resin I L M 1 2 3 4
5 a b c Thickness .mu. 70/80 70/80 60/70 80/90 65/75 70/80 70/80
70/80 60/70 70/80 80/90 Appearance good good good good good good
good good good good orange peel Flow PCI 5/6 5/6 5/6 7 6 6- 6- 6-
6/7 7- 1 Gloss 60.degree./20.degree. 96/83 94/78 94/72 94/84 94/84
95/84 96/81 94/80 94/85 92/83 90/50 MEK (0-5) 5 is the best 5- 4/5
5- 5 4/5 5- 5 4/5 4 3+ 5- Yellowing b value 5.08 5.68 4.27 6.59
5.77 5.83 4.71 4.5 3.8 n.a n.a Impact QD- 36 Dir. 200 200 140 200
200 200 200 140 160 160 160 Rev. 200 160 140 200 200 200 200 140
160 160 160
TABLE-US-00007 TABLE 7 Coating properties cured 10 min at
160.degree. C. Comparatives Invention Polyester Resin I L M 1 2 3 4
5 a b c Thickness .mu. 70/80 70/80 70/80 80/90 70/80 70/80 70/80
70/80 65/75 75/85 80/90 Appearance good good good good good good
good good good good orange peel Flow PCI 5/6 5/6 5/6 7 6 6- 6- 6-
6/7 7 1 Gloss 60.degree./20.degree. 94/81 96/84 95/78 95/86 95/86
96/87 97/83 95/85 93/86 92/84 79/30 MEK (0-5) 5 is the best (3)/4
.sup. 3/4 4+ 5 4- 4- (4)-5 4- 3+ 0 5- Yellowing b value 4.19 4.61
3.11 5.70 5.00 4.62 3.68 3.35 3.4 n.a n.a Impact QD-36 Dir. 20 20
160 200 120 200 100 40 10 0 160 Rev. 10 10 120 180 50 160 120 20 0
0 140
TABLE-US-00008 TABLE 8 Coating properties cured 30 min at
140.degree. C. PRIMID 93/7 Comparatives PRIMID 93/7 Invention
Polyester resins I L M 1 2 3 4 5 Thickness .mu. 70/80 70/80 60/70
80/90 70/80 70/80 70/80 70/80 Appearance good good good good good
good good good Flow PCI 5/6 5/6 5/6 7 6 6- 6- 6- Gloss
60.degree./20.degree. 80/70 90/80 93/78 95/88 95/85 95/86 94/85
94/80 MEK (0-5) 5 is the best 3/4 3/4 3+ 4- (3)/4 .sup. 3/4 (3)-4
3+ Yellowing b value 2.96 3.28 3.04 4.89 4.07 3.37 3.36 3.25 Impact
QD- 36 Dir. 50 10 20 80 80 160 20 40 Rev. 30 10 0 80 80 200 10 20
Impact resistance evaluated according ASTM D 2794
[0068] These results clearly show that the thermosetting powder
compositions in according with the invention have advantageous
characteristics compared to those obtained from compositions of the
prior art (Comparative examples I, L and M).
* * * * *