CN111518460B - Low gloss powder coatings with good flexibility - Google Patents
Low gloss powder coatings with good flexibility Download PDFInfo
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- CN111518460B CN111518460B CN202010396263.4A CN202010396263A CN111518460B CN 111518460 B CN111518460 B CN 111518460B CN 202010396263 A CN202010396263 A CN 202010396263A CN 111518460 B CN111518460 B CN 111518460B
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
- C09D167/00—Coating compositions based on polyesters obtained by reactions forming a carboxylic ester link in the main chain; Coating compositions based on derivatives of such polymers
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
- C09D5/00—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes
- C09D5/03—Powdery paints
- C09D5/032—Powdery paints characterised by a special effect of the produced film, e.g. wrinkle, pearlescence, matt finish
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
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- C09D5/00—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes
- C09D5/03—Powdery paints
- C09D5/033—Powdery paints characterised by the additives
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
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- C08K3/20—Oxides; Hydroxides
- C08K3/22—Oxides; Hydroxides of metals
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- C08K2003/2272—Ferric oxide (Fe2O3)
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Abstract
The invention relates to a low-gloss powder coating with good flexibility, in particular to a thermosetting powder coating composition, which comprises the following components: a. a polyester resin having: (i) a glass transition temperature (Tg) of 62 to 64 ℃; and (ii) an acid number of at least 31 and at most 34mg KOH/g polyester resin and a hydroxyl number of at least 2.6 and at most 3.0mg KOH/g polyester resin; and (iii) a functionality of at least 2.1 and at most 2.3; and (iv) a viscosity of at least 50pa.s and at most 52 pa.s; and (v) a number average molecular weight (M) of at least 3000Da and at most 4000Dan) (ii) a Triglycidyl isocyanurate as curing agent; triphenylethylphosphonium bromide; wherein the amount of component a is from 92.5 to 93.5 wt% relative to the total weight of component a and component b; the amount of component b is 6.5 to 7.5% by weight relative to the total weight of component a and component b; and the amount of component c is 0.069-0.071 wt% relative to the total weight of component a and component b; in addition, the thermosetting powder coating composition further comprises components d-j.
Description
Technical Field
The present invention relates to a thermosetting powder coating composition, articles having the thermosetting powder coating composition applied and cured thereon. The invention also relates to the use in low gloss powder coatings, flexible powder coatings and powder coatings suitable for heat transfer.
Background
In recent years, powder coating compositions that are substantially dry, finely divided, free flowing solid materials at room temperature and atmospheric pressure have achieved considerably higher popularity for several reasons than liquid coating compositions. One reason is that powder coatings are user and environmentally friendly materials because they do not actually contain the harmful volatile organic solvent carriers typically present in liquid coating compositions. Thus, upon curing, the powder coating emits little, if any, volatile substances to the environment. Furthermore, the powder coating composition is essentially 100% recyclable. Furthermore, the powder coating composition is convenient to use, i.e. does not need to be thinned or diluted.
There is an increasing demand for low gloss powder coatings in order to improve the texture of the product appearance. In general, high gloss coatings are more readily available than low gloss coatings; the formulation of low gloss powder coatings presents a number of challenges to the formulator, such as poor mechanical properties (e.g., flexibility) of the powder coatings, and expensive and difficult to control methods for making thermosetting powder coating compositions suitable for low gloss powder coatings.
Thus, there remains a need for thermosetting powder coating compositions that provide low gloss, good flexibility after curing.
Disclosure of Invention
It is therefore an object of the present invention to provide a thermosetting powder coating composition which, after curing, provides a low gloss powder coating with good flexibility.
This object is achieved by a thermosetting powder coating composition as described herein, comprising:
a. a polyester resin having:
(i) a glass transition temperature (Tg) of 62 to 64 ℃, as determined by Differential Scanning Calorimetry (DSC) according to ASTM E1356-08; and
(ii) an acid value of at least 31 and at most 34mg KOH/g polyester resin and a hydroxyl value of at least 2.6 and at most 3.0mg KOH/g polyester resin, said acid value being determined according to ISO 2114-1978 and said hydroxyl value being determined according to ISO 4629-1978; and
(iii) a functionality of at least 2.1 and at most 2.3; and
(iv) a viscosity of at least 50Pa.s and at most 52Pa.s as measured by a CAP-S-05 cone spindle at a speed of 21rpm using a Brookfield CAP 2000+ viscometer at 160 ℃; and
(v) number average molecular weight (M) of at least 3000Da and at most 4000Dan)；
Wherein the polyester resin is prepared from the following components: 6.50-6.70% by weight of isophthalic acid relative to the total amount of monomers used for the preparation of said polyester; 53.80-54.00% by weight of terephthalic acid, relative to the total amount of monomers used to prepare the polyester; 1.78-1.85% by weight of adipic acid, relative to the total amount of monomers used for preparing the polyester; 35.30-35.85% by weight of neopentyl glycol, relative to the total amount of monomers used to prepare the polyester; 1.40-1.50% by weight of 1, 6-hexanediol relative to the total amount of monomers used to prepare the polyester; and 0.67-0.72% by weight of trimethylolpropane, relative to the total amount of monomers used to prepare the polyester;
b. triglycidyl isocyanurate as curing agent; and
c. triphenylethylphosphonium bromide;
wherein the amount of component a is from 92.5 to 93.5 wt% relative to the total weight of component a and component b; the amount of component b is 6.5 to 7.5% by weight relative to the total weight of component a and component b; and the amount of component c is 0.069-0.071 wt% relative to the total weight of component a and component b; and
d. 0.02 to 0.03% by weight of carbon black, relative to the total weight of component a and component b, and
e. 0.42 to 0.44% by weight of red iron oxide, relative to the total weight of component a and component b, and
f. 0.28 to 0.29% by weight of yellow iron oxide, relative to the total weight of component a and component b, and
g. 1.3-1.5 wt.%, relative to the total weight of component a and component b, of a levelling agent GLP588, and
h. 0.42 to 0.44% by weight of benzoin, relative to the total weight of component a and component b, and
i. 42-44% by weight of delustered barium sulfate relative to the total weight of component a and component b, to
j. 6.8 to 7.0% by weight of matting agent, relative to the total weight of component a and component b.
In one embodiment of the present invention, the acid value of the polyester resin of the thermosetting powder coating composition according to the present invention is in the range of 31 to 33mg KOH/g polyester resin.
In another embodiment of the invention, M of the polyester resin of the thermosetting powder coating composition according to the inventionnIn the range of 3400 to 3700 Da.
In another embodiment of the present invention, the polyester resin of the thermosetting powder coating composition according to the present invention has a hydroxyl number of at least 2.7 and at most 2.9mg KOH/g polyester resin.
Preferably, the thermosetting powder coating composition according to the invention consists of components a to j.
In another aspect, the present invention provides a coated article having coated and cured thereon a thermosetting powder coating composition according to the present invention.
In another aspect, the present invention further provides the use of the thermosetting powder coating composition according to the invention in low gloss powder coatings, flexible powder coatings and powder coatings suitable for heat transfer.
The invention is limited to the precise details shown and described in this application.
The inventors of the present invention have surprisingly found that thermosetting powder coating compositions according to the present invention comprising a specific polyester resin according to the present invention in combination with appropriate amounts of triglycidyl isocyanurate (TGIC) as curing agent together with triphenylethyl phosphonium bromide, carbon black, red iron oxide, yellow iron oxide, levelling agent GLP588, benzoin together with delustering barium sulfate (Yuejiang) and matting agent provide after curing low gloss powder coatings with good flexibility.
The details of one or more embodiments of the invention are set forth in the description below.
Definition of
The resin (e.g., polyester resin, having a desired (target) M) is calculated herein according to the following equation EQ1n"functionality (f)" of desired (target) Acid Value (AV) and desired (target) hydroxyl value (OHV):
f＝[Mn*x(AV*+OHV*)]/56110 (EQ1)
if the desired (target) values of AV, OHV are not available, f can be calculated from analytical data on the chemical composition of the resin obtained from analytical techniques known to those skilled in the art (e.g., NMR nuclear magnetic resonance).
“Mn"herein means the theoretical number average molecular weight, which is calculated as M according to the following equation EQ2n：
Mn＝(56110×f)/(AV+OHV) (EQ2)
Wherein:
f: functionality determined according to equation EQ 1;
AV: measured Acid Value (AV) (mg KOH/g polyester resin);
an OHV: measured hydroxyl value (OHV) (mg KOH/g polyester resin).
The desired (target) AV of a resin, such as a polyester resin, is also referred to herein as the "theoretical AV" to distinguish it from the measured AV of the resin. The desired (target) OHV of a resin, such as a polyester resin, is also referred to herein as a "theoretical OHV" to distinguish it from the measured OHV of the resin.
Unless otherwise specified, the terms "acid value" (AV) and "hydroxyl value" (OHV) of a resin, such as a polyester resin, refer to the measured AV and the measured OHV of the resin, respectively. The Acid Value (AV) of the polyester resin (mg KOH/g polyester resin) and the hydroxyl value (OHV) of the polyester resin (mg KOH/g polyester resin) were measured by titration according to ISO 2114-2000 and ISO 4629-1978, respectively. The acid value of a resin, such as a polyester resin, is a measure of the amount of carboxylic acid groups in the polyester resin, while the hydroxyl value of a resin, such as a polyester resin, is a measure of the amount of hydroxyl groups in the polyester resin.
"viscosity" herein means the melt viscosity (in pa.s) at 160 ℃. Viscosity measurements were performed on a Brookfield CAP 2000+ H Viscometer at 160 ℃. The shear rate applied was 21s-1And a cone rotor (spindle) of 19.05mm (cone rotor CAP-S-05(19.05mm,1.8 °)) was used.
By "curing agent" is meant herein a compound capable of reacting with the polyester resin in the thermosetting powder coating composition of the invention, herein triglycidyl isocyanurate (TGIC) is used as curing agent.
“Tg"herein means the glass transition temperature. The glass transition temperature was measured by Differential Scanning Calorimetry (DSC) as described in the test methods section.
By "thermosetting powder coating composition" or "powder" is meant herein: a mixture of components in powder form and said composition having the ability to form an irreversible crosslinked network (a so-called "cured form" or "cured composition") upon curing, preferably by heat and/or radiation curing, more preferably by heat curing. For the sake of clarity, reference to either of the terms "thermosetting powder coating composition" or "powder" should be understood as an uncured thermosetting powder coating composition or equivalent uncured powder.
"curing" means herein: the process of becoming "fixed" to form an irreversible crosslinked network (a so-called "cured form" or "cured composition") in which the material no longer flows, melts or dissolves. The terms "cure" and "crosslinking" are used interchangeably herein. Preferably, the thermosetting powder coating composition of the invention is cured using heat, in which case the curing is referred to as "thermosetting". For clarity, the term "thermally cured" does not include Ultraviolet (UV) or electron beam induced curing. Optionally, a combination of heat and pressure may be used to cure the heat curable thermosetting powder coating compositions of the present invention. In the context of the present invention, the term "thermally curing" does not exclude the application of pressure and/or vacuum together with heat to cure the thermally curable thermosetting powder coating composition of the present invention.
"cured thermosetting powder coating composition" means herein the object obtained after partial or complete curing of the thermosetting powder coating composition; the curing can be effected thermally and/or by radiation, preferably thermally; the object may have any shape, size or form and it may be, for example, a film, a coating; preferably, the cured thermosetting powder coating composition is a powder coating.
By "powder coating" is meant herein a cured thermosetting powder coating composition in the form of a coating. The powder coating is obtained after curing the thermosetting powder coating composition.
By "low gloss" is meant a gloss 60 ° of up to 20 gloss units, wherein the gloss 60 ° is measured as described in the test methods section herein.
By "good flexibility" is meant that the powder coating at least performs well after being left for 4 weeks in a bending test (180 °).
"room temperature" herein means a temperature of 23 ℃.
For all upper and lower limits of any parameter given herein, the boundary values are included in each range for each parameter.
As used herein, the plural form of terms (e.g., polyester resin, curing agent, powder coating composition, component) may be construed to encompass the singular form and vice versa, unless the context clearly dictates otherwise.
In the present invention, the numerical ranges defined by endpoints include all any number within the range, for example, a range of 1 to 5 encompasses the numbers 1, 1.5, 2, 2.75, 3, 3.80, 4, 5, and the like. Moreover, the disclosed numerical ranges include all subranges within the broad range, for example, a range of 1 to 5 includes subranges 1 to 4, 1.5 to 4.5, 1 to 2, etc.
Detailed Description
Thermosetting powder coating composition
According to a first aspect of the present invention, there is provided a thermosetting powder coating composition comprising the following components:
a. a polyester resin having:
(i) a glass transition temperature (Tg) of 62 to 64 ℃, as determined by Differential Scanning Calorimetry (DSC) according to ASTM E1356-08; and
(ii) an Acid Value (AV) of at least 31 and at most 34mg KOH/g polyester resin and a hydroxyl value (OHV) of at least 2.6 and at most 3.0mg KOH/g polyester resin, said acid value being determined according to ISO 2114-1978; and
(iii) a functionality of at least 2.1 and at most 2.3; and
(iv) a viscosity of at least 50Pa.s and at most 52Pa.s as measured by a CAP-S-05 cone spindle at a speed of 21rpm using a Brookfield CAP 2000+ viscometer at 160 ℃; and
(v) a number average molecular weight (Mn) of at least 3000Da and at most 4000 Da;
wherein the polyester resin is prepared from the following components: 6.50-6.70% by weight of isophthalic acid relative to the total amount of monomers used for the preparation of said polyester; 53.80-54.00% by weight of terephthalic acid, relative to the total amount of monomers used to prepare the polyester; 1.78-1.85% by weight of adipic acid, relative to the total amount of monomers used for preparing the polyester; 35.30-35.85% by weight of neopentyl glycol, relative to the total amount of monomers used to prepare the polyester; 1.40-1.50% by weight of 1, 6-hexanediol relative to the total amount of monomers used to prepare the polyester; and 0.67-0.72% by weight of trimethylolpropane, relative to the total amount of monomers used to prepare the polyester;
b. triglycidyl isocyanurate as curing agent; and
c. triphenylethylphosphonium bromide;
wherein the amount of component a is from 92.5 to 93.5 wt% relative to the total weight of component a and component b; the amount of component b is 6.5 to 7.5% by weight relative to the total weight of component a and component b; and the amount of component c is 0.069-0.071 wt% relative to the total weight of component a and component b; and
d. 0.02 to 0.03% by weight of carbon black, relative to the total weight of component a and component b, and
e. 0.42 to 0.44% by weight of red iron oxide, relative to the total weight of component a and component b, and
f. 0.28 to 0.29% by weight of yellow iron oxide, relative to the total weight of component a and component b, and
g. 1.3-1.5 wt.%, relative to the total weight of component a and component b, of a levelling agent GLP588, and
h. 0.42 to 0.44% by weight of benzoin, relative to the total weight of component a and component b, and
i. 42-44% by weight of delustered barium sulfate, relative to the total weight of component a and component b, and
j. 6.8 to 7.0% by weight of matting agent, relative to the total weight of component a and component b.
The polyester resin of the thermosetting powder coating composition according to the invention is a polyester resin having a functionality of at least 2.1 and at most 2.3, preferably 2.2.
The polyester resin of the thermosetting powder coating composition according to the invention is only suitable for thermosetting powder coating compositions comprising TGIC as curing agent. The acid value of the polyester resin in the thermosetting powder coating composition according to the invention is in the range of 31-34mg KOH/g polyester resin, preferably in the range of 31-33mg KOH/g polyester resin, more preferably in the range of 32-33mg KOH/g polyester resin.
The glass transition temperature (Tg) of the polyester resin according to the present invention is in the range of 62 to 64 ℃, preferably in the range of 63 to 64 ℃. The glass transition temperature is measured by differential scanning calorimetry as described in the test methods section.
The hydroxyl value of the polyester resin of the thermosetting powder coating composition according to the invention is in the range of 2.6-3.0mg KOH/g polyester resin, preferably in the range of 2.7-2.9mg KOH/g polyester resin, more preferably 2.8mg KOH/g polyester resin.
The number average molecular weight (M) of the polyester resin of the thermosetting powder coating composition according to the inventionn) In the range of 3000 to 4000g/mol, preferably in the range of 3400 to 3700g/mol, more preferably in the range of 3400 to 3600 g/mol. The number average molecular weight is measured using Gel Permeation Chromatography (GPC).
The polyester resin of the thermosetting powder coating composition according to the invention has a melt viscosity of 50-53pa.s, preferably 50-52pa.s, wherein the melt viscosity is measured with a Brookfield CAP 2000+ H Viscometer at 160 ℃. The shear rate applied was 21s-1And a cone rotor of 19.05mm (cone rotor CAP-S-05(19.05mm,1.8 °)) was used.
Thermosetting powder coating compositions are generally baked at a temperature and for a time sufficient to melt level, crosslink and cure the powder particles to form a uniform coating.
The polyester resins may be prepared by esterification or transesterification according to conventional polycondensation procedures, optionally in the presence of a conventional esterification catalyst (e.g., a tin-based catalyst). In an embodiment, the present application discloses a process for preparing a polyester resin as directed to a thermosetting powder coating composition according to the present invention.
The polyester resin of the thermosetting powder coating composition according to the invention is the reaction product of the following monomers: 6.50-6.70 wt% of isophthalic acid, relative to the total weight of monomers used to prepare the polyester resin; 53.80 to 54.00% by weight of terephthalic acid, relative to the total weight of the monomers used to prepare the polyester resin; 1.78-1.85% by weight of adipic acid, relative to the total weight of the monomers used to prepare the polyester resin; 35.30-35.85% by weight of neopentyl glycol, relative to the total weight of the monomers used to prepare the polyester resin; 1.40-1.50% by weight of 1, 6-hexanediol, relative to the total weight of the monomers used to prepare the polyester resin; and 0.67 to 0.72 wt% of trimethylolpropane with respect to the total weight of monomers used to prepare the polyester resin.
Preferably, the polyester resin of the thermosetting powder coating composition according to the invention has:
(i) a glass transition temperature of 63.2 ℃; and
(ii) an acid value of 32.3mg KOH/g polyester resin and a hydroxyl value of 2.8mg KOH/g polyester resin; and
(iii)2.2 functionality; and
(iv) a viscosity of 51.5 pa.s; and
(v) a number average molecular weight of 3517 Da; and is
Wherein the polyester resin is prepared from the following monomers: 6.56% by weight of isophthalic acid, relative to the total weight of the monomers used to prepare the polyester resin; 53.88% by weight of terephthalic acid, relative to the total weight of the monomers used to prepare the polyester resin; 1.81% by weight of adipic acid, relative to the total weight of the monomers used to prepare the polyester resin; 35.59 weight% of neopentyl glycol relative to the total weight of the monomers used to prepare the polyester resin; 1.47% by weight of 1, 6-hexanediol relative to the total weight of the monomers used to prepare the polyester resin; and 0.69 wt% of trimethylolpropane with respect to the total weight of monomers used to prepare the polyester resin.
Preferably, the polyester resin of the thermosetting powder coating composition according to the invention is resin E as described in the examples.
Preferably, the thermosetting powder coating composition according to the invention consists of components a to j.
In addition, the present invention also provides a process for preparing the powder coating composition as described in the examples.
According to the present invention there is provided a cured thermosetting powder coating composition, as described herein. The cured thermosetting powder coating composition is obtained after curing the thermosetting powder coating composition as described herein.
Coated articles
According to the present invention, there is provided a coated article having coated and cured thereon a thermosetting powder coating composition according to the present invention.
The powder coating composition according to the invention was cured at 200 ℃ for 10 minutes.
The article may comprise, for example, a substrate selected from the group consisting of glass, ceramic, and metal (e.g., aluminum, copper, or steel).
In another aspect of the invention, the invention also relates to the use of the thermosetting powder coating composition in low gloss powder coatings, flexible powder coatings and powder coatings suitable for heat transfer.
In another aspect of the invention, the invention also relates to the use of the coated article according to the invention in low gloss powder coating applications, flexible powder coating applications and heat transfer applications.
Test method
Melt viscosity
Performed on a Brookfield CAP 2000+ H viscometer at 160 ℃. The shear rate applied was 21s-1And a cone rotor of 19.05mm (cone rotor CAP-S-05(19.05mm,1.8 °)) was used.
Acid value and hydroxyl value
The acid value was determined by titration according to ISO 2114-2000 and the hydroxyl value was determined by titration according to ISO 4629-1978.
gGlass transition temperature (T)
The glass transition temperature of the polyester resin is an inflection temperature of a temperature range where glass transition occurs, which is a point on a thermal curve corresponding to a peak of a first derivative (with respect to time) of a master thermal curve. This point corresponds to the inflection point of the parent thermal curve, as in ASTM E1356-08, § 3.2.1.3, is defined in the specification. The glass transition temperature (T) of the polyester resin was measured as followsgIn ° c): 10. + -. 5mg of polyester resin samples were weighed and placed in the DSC chamber. The sample was heated to 150 deg.C (thermogram A) at a heating rate of 40 deg.C/min. Once the sample reached 150 ℃, the temperature was maintained at 150 ℃ for 10 minutes. The sample was then cooled to 0 ℃ at a rate of 30 ℃/min (thermographic plot B); once the sample reached 0 ℃, the temperature was maintained at 0 ℃ for 1 minute. The sample was then heated to 100 deg.C (thermogram C) at a heating rate of 5 deg.C/min. The thermograms A, B and C are processed as the Y-axis of the thermograms showing heat flow with an exothermic rise and an endothermic fall. The thermogram C was used to measure the glass transition temperature (T) of the polyester resing)。
Flexibility
After 4 weeks of coating preparation, the flexibility of the coating will be measured by a 180 ° bending test according to GB/T12754-2019; wherein the thickness of the powder coating is measured according to GBT13452.2-2008 using a BYK-Gardner film thickness tester.
Degree of gloss
The gloss 60 ℃ of the powder coating obtained after curing of the corresponding thermosetting powder coating composition on ALQ-46 panels was determined according to ASTM D523 using a BYK-Gardner GmbH haze-gloss meter. Gloss is reported in gloss units at an angle of 60 ° and is measured at a film thickness of 60 ± 5 μm on an ALQ-46 plate.
Examples
Hereinafter, the present disclosure will be described more specifically by examples.
All parts, percentages, and ratios reported in the following examples are on a weight basis unless otherwise stated, and all reagents used in the examples are commercially available and can be used directly without further treatment.
Material
The materials used are listed in table 1 below.
Table 1: materials used and information relating thereto
| Material | Suppliers of goods |
| Carbon black (Orion Neox 505) | NINGBO SOUTH SEA CHEMICAL Co.,Ltd. |
| Delustering barium sulfate (Yuejiang 400) | NINGBO SOUTH SEA CHEMICAL Co.,Ltd. |
| Flatting agent (Mild mate A9) | NINGBO SOUTH SEA CHEMICAL Co.,Ltd. |
| Flatting agent (GLP588) | NINGBO SOUTH SEA CHEMICAL Co.,Ltd. |
| Triglycidyl isocyanurate (TGIC) | YANGZHOU SANDELI CHEMICAL Co.,Ltd. |
| Triphenylethylphosphonium bromide | NINGBO SOUTH SEA CHEMICAL Co.,Ltd. |
| Iron oxide red | NINGBO SOUTH SEA CHEMICAL Co.,Ltd. |
| Iron oxide yellow | NINGBO SOUTH SEA CHEMICAL Co.,Ltd. |
| Benzoin | Sigma-Aldrich |
| Butyl Stannoic acid | Sigma-Aldrich |
| Pentaerythritol diphosphite | Sigma-Aldrich |
| Trimethylolpropane | Sigma-Aldrich |
Preparation of polyester resin: general procedure
Polyester resins (polyester resins a-F) were prepared according to the following general procedure, with the ingredients and amounts as shown in table 2:
as shown in table 2, a reactor vessel equipped with a thermometer, stirrer, and distillation apparatus was filled with a tin-based catalyst, an antioxidant, and all diols (monomers). The vessel was heated to 150 ℃ until the mixture melted. Terephthalic acid (monomer) was then added and the temperature was gradually raised to 260 ℃ under a nitrogen stream while distilling the reaction water until the acid value of the polyester precursor was below 20mg KOH/g. The reaction mixture was cooled to 240 ℃ and then adipic acid (monomer) and isophthalic acid (monomer) were added in the second stage. The temperature was maintained at 240 ℃ while distilling the water. In the final stage, reduced pressure was applied until the polyester resin reached the desired acid number, about 35mg KOH/g. The vacuum was stopped, the polyester was cooled to 195 ℃, and triphenylethylphosphonium bromide (which is not a reactive entity for the preparation of polyester resins) was added to the resin. Subsequently, the resin was stirred at 195 ℃ for at least 20 minutes and then discharged onto an aluminum foil maintained at room temperature. In this procedure, the acid value and hydroxyl value are measured and corrected to a small extent with isophthalic acid (monomer) or neopentyl glycol (monomer) to obtain the desired product.
Table 2:
| composition (I) | Weight (D) | Resin A | Resin B | Resin C | Resin D | Resin E | Resin F |
| Neopentyl glycol | g | 414.7 | 410.4 | 405.8 | 402.2 | 410.0 | 406 |
| 1, 6-hexanediol | g | 16.9 | 16.9 | 16.9 | 16.9 | 16.9 | 16.9 |
| Trimethylolpropane | g | 0 | 4.0 | 8.0 | 11.2 | 8.0 | 8.0 |
| Adipic acid | g | 20.9 | 20.9 | 20.9 | 20.9 | 20.9 | 20.9 |
| Isophthalic acid | g | 75.6 | 75.6 | 75.6 | 75.6 | 75.6 | 75.6 |
| Terephthalic acid (TPA) | g | 620.1 | 620.5 | 620.5 | 620.9 | 620.7 | 620.8 |
| Tin-based catalyst | g | 0.5 | 0.5 | 0.5 | 0.5 | 0.5 | 0.5 |
| Antioxidant agent | g | 0.85 | 0.85 | 0.85 | 0.85 | 0.85 | 0.85 |
| Triphenylethylphosphonium bromide | g | 1 | 1 | 1 | 1 | 0.75 | 0.5 |
The resulting polyester resin was tested according to the test methods section and the results are shown in table 3:
table 3: properties of polyester resin
Preparation of thermosetting powder coating composition: general procedure
Thermosetting powder coating compositions were prepared according to the ingredients and amounts of table 4 below: the components were mixed in a blender and the resulting mixture was then extruded at 120 ℃ in an Xtretech XTS 19 twin screw. The rotational speed was adjusted to high torque (> 80%) to ensure good mixing. The extruded sheet of material was cooled to room temperature and cut into pieces. The chips were ground in a Retsch ZM100 with a 0.5mm circular screen at 18000rpm and then sieved. The sieves with a particle size of less than 90 μm were collected to provide corresponding powder coating compositions according to the invention and comparative. Subsequently, the thermosetting powder coating compositions according to the invention and of the comparative example were electrostatically sprayed (corona, 60kV) onto 0.8mm thick aluminum chromate Q-plates (ALQ-46 type) in a coating thickness of 65. + -.5 μm and cured at atmospheric pressure in an air circulation oven (Heraeus Instruments UT6120) at 200 ℃ for 10 minutes to give corresponding powder coatings according to the invention and of the comparative example.
The powder coatings were tested for performance according to test methods section and the results are shown in table 4:
table 4: composition and Properties of thermosetting powder coating compositions
From the results of table 4 above, it can be seen that only the thermosetting powder coating composition of example 1 is able to provide a low gloss and flexible powder coating after curing.
The entire disclosures of all patents, patent applications, and publications, as well as electronically available materials, cited herein are hereby incorporated by reference. The invention is limited only to the exact details shown and described.
Claims (10)
1. A thermosetting powder coating composition comprising:
a. a polyester resin having:
a glass transition temperature of 62 to 64 ℃, as determined by Differential Scanning Calorimetry (DSC) according to ASTM E1356-08; and
an acid value of at least 31 and at most 34mg KOH/g and a hydroxyl value of at least 2.6 and at most 3.0mg KOH/g, said acid value being determined according to ISO 2114-2000 and said hydroxyl value being determined according to ISO 4629-1978; and
a functionality of at least 2.1 and at most 2.3; and
a viscosity of at least 50Pa.s and at most 52Pa.s as measured by a CAP-S-05 cone spindle at a speed of 21rpm using a Brookfield CAP 2000+ viscometer at 160 ℃; and
number average molecular weight (M) of at least 3000Da and at most 4000Dan）；
Wherein the polyester resin is prepared from the following monomers: 6.50-6.70 wt% of isophthalic acid, relative to the total weight of monomers used to prepare the polyester resin; 53.80 to 54.00% by weight of terephthalic acid, relative to the total weight of the monomers used to prepare the polyester resin; 1.78-1.85% by weight of adipic acid, relative to the total weight of the monomers used to prepare the polyester resin; 35.30-35.85% by weight of neopentyl glycol, relative to the total weight of the monomers used to prepare the polyester resin; 1.40-1.50% by weight of 1, 6-hexanediol, relative to the total weight of the monomers used to prepare the polyester resin; and 0.67-0.72 wt.% of trimethylolpropane, relative to the total weight of monomers used to prepare the polyester resin;
b. triglycidyl isocyanurate as curing agent; and
c. triphenylethylphosphonium bromide;
wherein the amount of component a is from 92.5 to 93.5 wt% relative to the total weight of component a and component b; the amount of component b is 6.5 to 7.5% by weight relative to the total weight of component a and component b; and the amount of component c is 0.069-0.071 wt% relative to the total weight of component a and component b; and
d. 0.02 to 0.03% by weight of carbon black, relative to the total weight of component a and component b, and
e. 0.42 to 0.44% by weight of red iron oxide, relative to the total weight of component a and component b, and
f. 0.28 to 0.29% by weight of yellow iron oxide, relative to the total weight of component a and component b, and
g. 1.3-1.5 wt.%, relative to the total weight of component a and component b, of a levelling agent GLP588, and
h. 0.42 to 0.44% by weight of benzoin, relative to the total weight of component a and component b, and
i. 42-44% by weight of delustered barium sulfate, relative to the total weight of component a and component b, and
j. 6.8 to 7.0% by weight of matting agent, relative to the total weight of component a and component b.
2. The thermosetting powder coating composition according to claim 1, wherein the acid value is in the range of 31 to 33mg KOH/g.
3. The thermosetting powder coating composition of claim 1, wherein M isnIn the range of 3400 to 3700 Da.
4. The thermosetting powder coating composition according to claim 1, wherein the hydroxyl number is at least 2.7 and at most 2.9mg KOH/g.
5. The thermosetting powder coating composition according to any one of claims 1-4, wherein the polyester resin has:
a glass transition temperature of 63.2 ℃; and
an acid value of 32.3mg KOH/g and a hydroxyl value of 2.8mg KOH/g; and
2.2 functionality; and
a viscosity of 51.5 pa.s; and
a number average molecular weight of 3517 Da; and is
Wherein the polyester resin is prepared from the following monomers: 6.56% by weight of isophthalic acid, relative to the total weight of the monomers used to prepare the polyester resin; 53.88% by weight of terephthalic acid, relative to the total weight of the monomers used to prepare the polyester resin; 1.81% by weight of adipic acid, relative to the total weight of the monomers used to prepare the polyester resin; 35.59 weight% of neopentyl glycol relative to the total weight of the monomers used to prepare the polyester resin; 1.47% by weight of 1, 6-hexanediol relative to the total weight of the monomers used to prepare the polyester resin; and 0.69 wt% of trimethylolpropane with respect to the total weight of monomers used to prepare the polyester resin.
6. The thermosetting powder coating composition according to any one of claims 1-4, wherein the thermosetting powder coating composition consists of components a to j.
7. The thermosetting powder coating composition according to claim 5, wherein the thermosetting powder coating composition consists of components a to j.
8. A coated article having coated and cured thereon the thermosetting powder coating composition of any one of claims 1-7.
9. Use of the thermosetting powder coating composition according to any one of claims 1-7 in low gloss powder coatings, flexible powder coatings and powder coatings suitable for heat transfer.
10. Use of the coated article of claim 8 in low gloss powder coating applications, flexible powder coating applications, and heat transfer applications.
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| US6555226B1 (en) * | 2000-10-26 | 2003-04-29 | Bp Corporation North America Inc. | Polyester resin for powder coating |
| BRPI1009869A2 (en) * | 2009-03-27 | 2016-03-08 | Dsm Ip Assets Bv | powder coating composition comprising a polyester and a beta-hydroxyalkylamide as a crosslinker |
| CN102127212B (en) * | 2010-12-10 | 2013-11-06 | 中国电器科学研究院 | Terminal carboxyl group polyester resin for weather-resistance high-gloss powder coating and preparation method thereof |
| CN103739830B (en) * | 2013-10-21 | 2017-01-11 | 广州擎天材料科技有限公司 | Polyester resin for TGIC cured high-toughness powder coating and preparation method thereof |
| CN104311806B (en) * | 2014-10-20 | 2016-05-11 | 浙江天松新材料股份有限公司 | A kind of mylar and preparation method thereof for high levelling transparent powder paint |
| CN106750207A (en) * | 2016-11-04 | 2017-05-31 | 广州擎天材料科技有限公司 | High acid value amorphous polyester resin and preparation method and the solidifications of the HAA comprising the polyester resin once extrude low brightness paint powder |
| CN108003758A (en) * | 2017-12-01 | 2018-05-08 | 成都信达高分子材料有限公司 | A kind of extra-weather-proof TGIC curing types powdery paints |
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