CA2196858A1 - Blocked and chain-extended diisocyanate adducts, a process for preparing them and their use - Google Patents
Blocked and chain-extended diisocyanate adducts, a process for preparing them and their useInfo
- Publication number
- CA2196858A1 CA2196858A1 CA002196858A CA2196858A CA2196858A1 CA 2196858 A1 CA2196858 A1 CA 2196858A1 CA 002196858 A CA002196858 A CA 002196858A CA 2196858 A CA2196858 A CA 2196858A CA 2196858 A1 CA2196858 A1 CA 2196858A1
- Authority
- CA
- Canada
- Prior art keywords
- diisocyanate
- weight
- aliphatic
- caprolactam
- blocked
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G18/00—Polymeric products of isocyanates or isothiocyanates
- C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
- C08G18/70—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the isocyanates or isothiocyanates used
- C08G18/72—Polyisocyanates or polyisothiocyanates
- C08G18/80—Masked polyisocyanates
- C08G18/8061—Masked polyisocyanates masked with compounds having only one group containing active hydrogen
- C08G18/807—Masked polyisocyanates masked with compounds having only one group containing active hydrogen with nitrogen containing compounds
- C08G18/8074—Lactams
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G18/00—Polymeric products of isocyanates or isothiocyanates
- C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
- C08G18/70—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the isocyanates or isothiocyanates used
- C08G18/72—Polyisocyanates or polyisothiocyanates
- C08G18/80—Masked polyisocyanates
- C08G18/8003—Masked polyisocyanates masked with compounds having at least two groups containing active hydrogen
- C08G18/8006—Masked polyisocyanates masked with compounds having at least two groups containing active hydrogen with compounds of C08G18/32
- C08G18/8038—Masked polyisocyanates masked with compounds having at least two groups containing active hydrogen with compounds of C08G18/32 with compounds of C08G18/3225
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G2150/00—Compositions for coatings
- C08G2150/20—Compositions for powder coatings
Landscapes
- Chemical & Material Sciences (AREA)
- Health & Medical Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Organic Chemistry (AREA)
- Polyurethanes Or Polyureas (AREA)
- Paints Or Removers (AREA)
Abstract
Completely or partially .epsilon.-caprolactam-blocked aliphatic diisocyanate adducts which are chain-extended with aliphatic and/or cycloaliphatic diamines, a process for preparing them and their use.
Description
21 968~38 Blocked and Chain-extended Diisocyanate Adducts, a Process for Preparing them and Their Use The present invention relates to completely or partially ~-caprolactam-blocked aliphatic diisocyanate adducts which are chain-extended with aliphatic and/or cyclGaliphatic diamines, to a process for preparing them and to their use.
From among the large number of polyisocyanates, it is almost exclusively only the ~-caprolactam-blocked adducts of isophorone diisocyanate (IPDI) which are suitable for preparing weather-resistant polyurethane coatings (see German Patent Publication DE-A 35 36 017, page 2, lines 13 to 27).
The preparation of polyurethane (PU) powders based on ~-caprolactam-blocked aliphatic diisocyanates and/or their adducts containing isocyanurate groups, biuret groups and urethane groups was not hitherto possible~ since these compounds are either not solid, and therefore cannot be milled, or are solid - as is the case with ~-caprolactam-blocked hexamethylene diisocyanate - but become solid again, following homogenization with the hydroxyl-containing polyester in a kneading apparatus at about 100~C, only with a considerable delay.
Such hardeners constitute a welcome enrichment of existing PU powder hardeners, since they would enable, simply, the flexibility of PU powders to be tailored.
It is therefore an object of the present invention to provide novel blocked aliphatic diisocyanate adducts which make it possible to prepare PU powders.
O.Z. 5014 2 t 96858 Surprisingly, it has been found pcssible to produce PU powder hardeners of this kind based on aliphatic diisGcyanates by completely or partially reacting aliphatic diisocyanates, prior to chain extension with diamines, with ~-caprolactam and then subjecting them to chain extension with diamines.
Broadly speaking, the present invention accord-ingly provides ccmpletely or partially ~-caprolactam-blocked aliphatic diisocyanate adducts which are chain-extended with aliphatic and/or cycloaliphatic diamines and are Gbtainable by reacting the diisocyanates with ~-caprolactam and then with the diamines. Preferably, such adducts have the following formula:
~ N
B - C- N- R- N- C- N -R'- N- C- N - - C - B~ (I) O H H O H H O H ~H O
wherein R is CH -fH-(CH~)3-, -CH2-fH (CH2)2 , 2 6 2 f 2 f CH2 CH2 ~ -CH2-7H-cH2-f-cH2-cH2- or -cH2-cH2-cH2-cH2-fH-cH2-cH2-cH2-cH2-;
R' is an alkylene or cycloalkylene radical of 2 - 16 carbon atoms;
21 9685~
B is the residue of ~-caprolactam of the formula ~0;
n is a number of 1 - 3; and x is a number of 0 - 0.5.
The diisocyanate adducts according to the invention preferably have a molecular weight which varies in a range from 600 - 1,400. The melting point is preferably between 60 and 160~C. The content of urea groups is in general between 2 and 4 mmol/g. The content of NCO groups which are blocked by ~-caprolactam is usually 7 - 15% by weight, preferably 8 - 12% by weight, while the content of free NCO
groups is preferably between 0.1 and 5% by weight.
The diisocyanate adducts described are suitable as hardeners for epoxy resins based on bisphenol A and for all compounds containing Zerewitinoff active hydrogen atoms.
Curing takes place above 160~C, preferably at 170 - 200~C.
The present invention additionally provides a process for preparing the compounds according to the invention.
According to this process, the compounds according to the invention are prepared in two stages, the 1st stage comprising the reaction of the aliphatic diisocyanate of the formula OCN-R-NCO with ~-caprolactam at 80 - 150~C and, after the end of reaction, the addition in portions of the diamine of the formula H2N-R'-NH2. After the diamine has been added, which is associated with a high level of heat being given off, 2i 96858 the reaction product is heated further in the melt in order to complete the reaction, e.g. for about 1 hour.
In the process according to the invention it is absolutely necessary to carry out the reaction in the stated sequence: ~-caprolactam blocking of the diisocyanate followed by a reaction with the diamine.
Examples of the aliphatic diisocyanates OCN-R-NCO
include hexamethylene diisocyanate (HDI), 2-methylpenta-methylene diisocyanate (DI 51), which may contain up to 10%
by weight of 2-ethyltetramethylene diisocyanate, and also 2,2,4 (or 2,4,4)-trimethylhexamethylene diisocyanate and 5-methylnonamethylene diisocyanate.
The diamines H2N-R'-NH2 which can be employed in accordance with the invention are of nonaromatic type. They contain 2 - 16 carbon atoms and two primary aminG groups.
Examples are ethylenediamine, trimethylenediamine, tetra-methylenediamine, hexamethylenediamine, octamethylenediamine, 2-methylpentamethylenediamine, 2,2,4 (or 2,4,4)-trimethyl-hexamethylenediamine, 1,4-diaminocyclohexane, 2,4-diamino-1-methylcyclohexane, 4,4'-diaminodicyclohexylmethane (HMDA), 4,4'-diamino-3,3'-dimethyldicyclohexylmethane (e.g., Laromin C 260) and isophoronediamine (IPD).
The present invention provides, furthermore, for the use of the compounds according to the invention in combination with OH-containing polymers as binders for light-stable polyurethane powder coatings.
Trade-mark 21 9685~
The heat-curable pulverulent composition in which the blocked diisocyanate adduct according to the invention is employed comprises:
A) 100 parts by weight (pbw) of an OH-containing polymer with more than two OH groups, B) 15 - 60 pbw of the blocked diisocyanate adduct according to the invention, C) 0 - 160 pbw of a pigment, D) 0 - 200 pbw of a customary filler, E) 0 - 5 pbw of a catalyst, and F) 0.5 - 5 pbw of a leveling agent.
Constituent A can in principle be any polymer containing more than two OH groups and having a melting point of at least 70~C. Such compounds may be polyesterpolyols, polyetherpolyols, polyesteramidepolyols, polyurethanepolyols, hydroxylated acrylic resins, etc., whose OH groups are intended for crosslinking with the blocked aliphatic diisocyanate adducts according to the invention. Among the numerous possibilities for hydroxyl-containing polymers in the context of the invention, particular preference is given to polyester-polyols. Such polyesterpolyols generally have a molecular weight of between 700 and 3,000, preferably 1,500 - 2,500, an OH number of 25 - 240 mg of KOH/g, and an OH functionality of more than 2. The preparation of such polyesterpolyols is described, for example, in German Patent Publications(DE-A) 19 57 483, 25 42 191, 30 04 876 and 31 43 060.
4a 2i 96858 In order to raise the gelling rate of the heat-curable compositions, it is possible to add catalysts.
Catalysts commonly used are organotin compounds such as dibutyltin dilaurate, tin(II) octoate, dibutyltin maleate, etc. The amount of catalyst added is 0.1 - 5% by weight of the hydroxyl-containing polymer.
To prepare PU powder coatings, the isocyanate component is mixed with the appropriate hydroxyl-containing polymer 4b O.~. 5014 and, if desired, catalysts and also pigments and customary auxiliaries such as fillers and leveling agents, for example silicone oil, acrylate resins, and the mixture is homogenized in the melt. This can be carried out in appropriate equipment such as, for example, heatable kneading apparatus, but preferably by extrusion, in which case upper temperature limits of 130 to 140~C should not be exceeded. After cooling to room temperature and appropriate comminution, the extruded mass is ground to form the ready-to-spray powder. This powder can be applied to appropriate substrates by the known methods, for example by electrostatic powder spraying or (electrostatic) fluidized-bed sintering.
Following the application of the powder, the coated workpieces are cured by heating them at a temperature of 150 to 220~C for from 60 to 4 minutes, preferably at 160 - 200~C for 30 - 6 minutes.
The coatings prepared in accordance with the invention are distinguished by outstanding weather resistance and very good color stability. Furthermore, it is possible with the powders according to the invention to produce coatings ranging from silky matt to highly glossy.
A General preparation ~lch~ re for the co~ound~
according to the invention The aliphatic diisocyanate is introduced into the reaction vessel at 100~C, and portions of e-caprolactam are added such that the temperature of the reaction mixture does not exceed 120~C. After the e-caprolactam has been added, heating is continued until one NCO
equivalent is consumed per mol of e-caprolactam.
Thereafter, the diamine is added in portions at 120 -150~C although in some cases - in particular when the melting point of the reaction product is high - it can be expedient to work at temperatures above 150~C. In order to complete the reaction, the addition of the diamine is followed by heating in the melt for about 0.5 h more. The compounds listed in Table 1 were prepared in accordance 2 1 q6858 6 O. ~ . 5014 with this procedure.
7 O.Z. 5014 T~hle 1: Blocked aliphatic polyi~ocyanate adduct~ contAi n i ng urea groups Example A Composition in mol Chemicsl and physical ' ~cs Diis~ - Caprolactam Di~ine NCO content Mclting Glass [% by wt range l" i~
DI 51 HDI f~wtotal [~C] t~ c rocl 2 - I.S IPD (1.25) 0.3 8.5 118-120 48-67 2 - 1.75 I.S IPD (1) 0.4 9.7 96-98 38-60 3 - 1.85 1.5 HMDA (1) 1.610.2 107-109 40~0 4 1.85 - 1.5 HMDA (1) 1.610.2 106-109 41-61 - 2 2 L~romin C 260 (1) 0.4 10.3 77-79 31-57 6 - 2 2 HMDA (1) 0.310,7 128-130 69-85 7 - 1.85 I.S IPD (1) 1.410.8 92-9S 41~0 8 2 - 2 IPD (I) O.S11.2 75-78 39-48 9 - 2 2 IPD (1) 0.511.0 72-74 33-60 O~
- 2 1.5 ~D (1) 3.012.0 96-99 39-57 8 O.Z. 5014 TAhle 1: Blocked aliphatic polyisocyanate adducts containing urea ~lolr~ contin-le~
Example A Composition in mol Chemical and physical _ Di;i~ - Caprola- Diamine NCO cont~nt Melting Glass ctam [% by wt~ r~nge 1l ~n DI 51 HDI free tot l [~C] t~,.. ~,~,., rocl I l - 2 5 2 HMDA (1 5) 0.5 12.8 144-147 97-110 12 2 - 2 Laromin C 260 (1) 0.3 10 3 103-107 38-59 13 2 1 5 IPD (1) 3 5 11.9 94-101 42-61 14 2 - 2 HMDA (1) 0 4 10 5 121-127 62-79 9 O.Z. 5014 B polyol component General preparation procedure The starting components - terephthalic acid (TA), dimethyl terephthalate (DMT), 1,6-hexanediol (HD), neopentylglycol (NPG), 1,4-dimethylolcyclohexane (DMC) and trimethylolpropane (TMP) - are placed in a reactor and heated with the aid of an oil bath. After the substances have predominantly melted, 0.5 % by weight of di-n-butyltin oxide as catalyst is added at a temperature of 160~C. Initial elimination of methanol occurs at a temperature of about 170~C. The temperature is raised to 220 - 230~C over the course of from 6 to 8 hours, and the reaction is brought to an end within a further 12 to 15 hours. The polyester i8 cooled to 200~C and substantially lS freed from volatile constituents by applying a vacuum (1.33 mbar) over the course of from 30 to 45 minutes.
Throughout the reaction period the bottom product is stirred and a gentle stream of N2 is passed through the reaction mixture.
Table 2 shows commercial polyesters and polyester compositions with the corresponding physical and chemical characteristics.
0. Z . 5014 TAhl e 2: Polye~ters Example Startingc~ Chemical and~ ic l~' _ B TA DMT HD NPG DMC TMP OH Acid M.p. DTA Viscosity [mol] [mol] [moll [mol][mol] [mol] number number [~C] [~C] at 160~C
[mg of [mg of [mPa-s]
KOH/gl KoH/Rl 6.25 10.5 2 2.9 SS-60 3~ about 75 about 50 z 25,000 2 CRYLCOAr280UCB/Bel~ium z 50 < 10 100 ~ 8 SS ~ 8 3 9 ¦ 9 ¦ 3 ¦ 13 ¦ 3 l l 50-56 3-4 about70 aboutS0 z 10,000 4 ALFTALAT~ AN 739 Hoechst/Italy SS-60 2-4 82-90 > 50 24-29,000 11 O.Z. 5014 C Polyurethane powder coati ng8 General preparation procedure The comminuted products - blocked isocyanate adducts (crosslinking agents), polyesters, leveling agent masterbatch and, if used, catalyst masterbatch - are intimately mixed, optionally with the white pigment, in an edge runner mill and the mixture is subsequently homogenized in an extruder at a temperature of not more than 130~C. After cooling, the extrudate is fractionated and ground with a pinned-disk mill to a particle size of < 100 ~m. The resulting powder is applied using an electrostatic powder s~aying unit at 60 kV to degreased, optionally pretreated iron panels which are baked at temperatures between 160 and 200~C in a convection oven.
lS Leveling a~ent masterbatch 10 % by weight of the leveling agent - a commercially available copolymer of butyl acrylate and 2-ethylhexyl acrylate - is homogenized in the melt in the corresponding polyester, and the solidified melt is comminuted.
Catalyst masterbatch 5 % by weight of the catalyst - DBTL - is homogenized in the melt in the corresponding polyester and the solidified melt is comminuted.
The abbreviations in the Tables below have the following meanings:
CT = Coat thickness in ~m EI = Erichsen indentation in mm (DIN 53 156) CH = Cross-hatch test (DIN 53 151) 30 GG 60~~ = Gardner gloss measurement in scale divisions (ASTM-D 5233) mp. rev. = Impact reverse in g-m ~ ~ ~ -- 1-- ~ ~ ~ O O ~
e~ ~
~ _ ~ g l ~ o o ~
O ~ ~ , ~ o ~ ~i O o o~ ,, o ~ ~ ~ o Q~
o o ~ o ~
--~ 3 ~ x ~ o - ~o ~ ~ x 3 X ~ ~ ~ o ~ o ~ ~
D Q~
~ ~ 5 ~ co ~ ~ ~ 8 O a~ x 1- ~ ' I_ , X A ~
~, ~, X X oo o o '~
'~ o _ ~ ~ ~
~' 8 9 8 8 t -~ 5 o 2 U~ o U~
13 O. Z . 5014 2 ~ -n1-~A ~ows~r C~ ir~g~ With A rQ~ C~ ,e of ~108 Ahle 4 ExampleC 13 14 15 16 17 18 19 20 21 22 23 24 Fr ' C.~ ~ ~ ine 31.29 30.22 28.73 29.530.01 29.03 27.60 28.32 26.91 26.23 28.56 27.07 sgentacc. toA (2) (3) (3) (3) (5) (7) (7) (7) (10) (lo) (12) (13) Example () Polyester acc. to 68.71 69.78 - 69.99 70.97 - - 73.09 - - 72.93 B I
Polyester acc. to - - 71.27 - - - 72.40 - - - 71.44 Polyester acc. to - - - 70.S - - - 71.68 - 73.77 Notes All f ' contain 40 % by wei~ht of TiO, (white pi~mcnt) and 0,S % by wei~ht each of bveUnK agont and benzoin; the OH/NCO ratio is 1: 1 Co~tings data ~:;(} 60~ <1: 42 37 33 41 58 48 40 Sl 44 53 63 49 EI 4.S/S.3 9.0 6.2/7.08.519.2 > 10 8.1/83 7.617.88.719.27.S17.98.1/8.5> 10 80/8.3 Imp. rev. 115.2 >944.6 576 806.4 >944.6 806.4 806.4 ~944.6 691.2 691.2 >944.6 576 Notes T' . e ~ ~ 200~C/8 to 15 minutes, 180~C/15 to 25 minute~ O~
C~
< r~
From among the large number of polyisocyanates, it is almost exclusively only the ~-caprolactam-blocked adducts of isophorone diisocyanate (IPDI) which are suitable for preparing weather-resistant polyurethane coatings (see German Patent Publication DE-A 35 36 017, page 2, lines 13 to 27).
The preparation of polyurethane (PU) powders based on ~-caprolactam-blocked aliphatic diisocyanates and/or their adducts containing isocyanurate groups, biuret groups and urethane groups was not hitherto possible~ since these compounds are either not solid, and therefore cannot be milled, or are solid - as is the case with ~-caprolactam-blocked hexamethylene diisocyanate - but become solid again, following homogenization with the hydroxyl-containing polyester in a kneading apparatus at about 100~C, only with a considerable delay.
Such hardeners constitute a welcome enrichment of existing PU powder hardeners, since they would enable, simply, the flexibility of PU powders to be tailored.
It is therefore an object of the present invention to provide novel blocked aliphatic diisocyanate adducts which make it possible to prepare PU powders.
O.Z. 5014 2 t 96858 Surprisingly, it has been found pcssible to produce PU powder hardeners of this kind based on aliphatic diisGcyanates by completely or partially reacting aliphatic diisocyanates, prior to chain extension with diamines, with ~-caprolactam and then subjecting them to chain extension with diamines.
Broadly speaking, the present invention accord-ingly provides ccmpletely or partially ~-caprolactam-blocked aliphatic diisocyanate adducts which are chain-extended with aliphatic and/or cycloaliphatic diamines and are Gbtainable by reacting the diisocyanates with ~-caprolactam and then with the diamines. Preferably, such adducts have the following formula:
~ N
B - C- N- R- N- C- N -R'- N- C- N - - C - B~ (I) O H H O H H O H ~H O
wherein R is CH -fH-(CH~)3-, -CH2-fH (CH2)2 , 2 6 2 f 2 f CH2 CH2 ~ -CH2-7H-cH2-f-cH2-cH2- or -cH2-cH2-cH2-cH2-fH-cH2-cH2-cH2-cH2-;
R' is an alkylene or cycloalkylene radical of 2 - 16 carbon atoms;
21 9685~
B is the residue of ~-caprolactam of the formula ~0;
n is a number of 1 - 3; and x is a number of 0 - 0.5.
The diisocyanate adducts according to the invention preferably have a molecular weight which varies in a range from 600 - 1,400. The melting point is preferably between 60 and 160~C. The content of urea groups is in general between 2 and 4 mmol/g. The content of NCO groups which are blocked by ~-caprolactam is usually 7 - 15% by weight, preferably 8 - 12% by weight, while the content of free NCO
groups is preferably between 0.1 and 5% by weight.
The diisocyanate adducts described are suitable as hardeners for epoxy resins based on bisphenol A and for all compounds containing Zerewitinoff active hydrogen atoms.
Curing takes place above 160~C, preferably at 170 - 200~C.
The present invention additionally provides a process for preparing the compounds according to the invention.
According to this process, the compounds according to the invention are prepared in two stages, the 1st stage comprising the reaction of the aliphatic diisocyanate of the formula OCN-R-NCO with ~-caprolactam at 80 - 150~C and, after the end of reaction, the addition in portions of the diamine of the formula H2N-R'-NH2. After the diamine has been added, which is associated with a high level of heat being given off, 2i 96858 the reaction product is heated further in the melt in order to complete the reaction, e.g. for about 1 hour.
In the process according to the invention it is absolutely necessary to carry out the reaction in the stated sequence: ~-caprolactam blocking of the diisocyanate followed by a reaction with the diamine.
Examples of the aliphatic diisocyanates OCN-R-NCO
include hexamethylene diisocyanate (HDI), 2-methylpenta-methylene diisocyanate (DI 51), which may contain up to 10%
by weight of 2-ethyltetramethylene diisocyanate, and also 2,2,4 (or 2,4,4)-trimethylhexamethylene diisocyanate and 5-methylnonamethylene diisocyanate.
The diamines H2N-R'-NH2 which can be employed in accordance with the invention are of nonaromatic type. They contain 2 - 16 carbon atoms and two primary aminG groups.
Examples are ethylenediamine, trimethylenediamine, tetra-methylenediamine, hexamethylenediamine, octamethylenediamine, 2-methylpentamethylenediamine, 2,2,4 (or 2,4,4)-trimethyl-hexamethylenediamine, 1,4-diaminocyclohexane, 2,4-diamino-1-methylcyclohexane, 4,4'-diaminodicyclohexylmethane (HMDA), 4,4'-diamino-3,3'-dimethyldicyclohexylmethane (e.g., Laromin C 260) and isophoronediamine (IPD).
The present invention provides, furthermore, for the use of the compounds according to the invention in combination with OH-containing polymers as binders for light-stable polyurethane powder coatings.
Trade-mark 21 9685~
The heat-curable pulverulent composition in which the blocked diisocyanate adduct according to the invention is employed comprises:
A) 100 parts by weight (pbw) of an OH-containing polymer with more than two OH groups, B) 15 - 60 pbw of the blocked diisocyanate adduct according to the invention, C) 0 - 160 pbw of a pigment, D) 0 - 200 pbw of a customary filler, E) 0 - 5 pbw of a catalyst, and F) 0.5 - 5 pbw of a leveling agent.
Constituent A can in principle be any polymer containing more than two OH groups and having a melting point of at least 70~C. Such compounds may be polyesterpolyols, polyetherpolyols, polyesteramidepolyols, polyurethanepolyols, hydroxylated acrylic resins, etc., whose OH groups are intended for crosslinking with the blocked aliphatic diisocyanate adducts according to the invention. Among the numerous possibilities for hydroxyl-containing polymers in the context of the invention, particular preference is given to polyester-polyols. Such polyesterpolyols generally have a molecular weight of between 700 and 3,000, preferably 1,500 - 2,500, an OH number of 25 - 240 mg of KOH/g, and an OH functionality of more than 2. The preparation of such polyesterpolyols is described, for example, in German Patent Publications(DE-A) 19 57 483, 25 42 191, 30 04 876 and 31 43 060.
4a 2i 96858 In order to raise the gelling rate of the heat-curable compositions, it is possible to add catalysts.
Catalysts commonly used are organotin compounds such as dibutyltin dilaurate, tin(II) octoate, dibutyltin maleate, etc. The amount of catalyst added is 0.1 - 5% by weight of the hydroxyl-containing polymer.
To prepare PU powder coatings, the isocyanate component is mixed with the appropriate hydroxyl-containing polymer 4b O.~. 5014 and, if desired, catalysts and also pigments and customary auxiliaries such as fillers and leveling agents, for example silicone oil, acrylate resins, and the mixture is homogenized in the melt. This can be carried out in appropriate equipment such as, for example, heatable kneading apparatus, but preferably by extrusion, in which case upper temperature limits of 130 to 140~C should not be exceeded. After cooling to room temperature and appropriate comminution, the extruded mass is ground to form the ready-to-spray powder. This powder can be applied to appropriate substrates by the known methods, for example by electrostatic powder spraying or (electrostatic) fluidized-bed sintering.
Following the application of the powder, the coated workpieces are cured by heating them at a temperature of 150 to 220~C for from 60 to 4 minutes, preferably at 160 - 200~C for 30 - 6 minutes.
The coatings prepared in accordance with the invention are distinguished by outstanding weather resistance and very good color stability. Furthermore, it is possible with the powders according to the invention to produce coatings ranging from silky matt to highly glossy.
A General preparation ~lch~ re for the co~ound~
according to the invention The aliphatic diisocyanate is introduced into the reaction vessel at 100~C, and portions of e-caprolactam are added such that the temperature of the reaction mixture does not exceed 120~C. After the e-caprolactam has been added, heating is continued until one NCO
equivalent is consumed per mol of e-caprolactam.
Thereafter, the diamine is added in portions at 120 -150~C although in some cases - in particular when the melting point of the reaction product is high - it can be expedient to work at temperatures above 150~C. In order to complete the reaction, the addition of the diamine is followed by heating in the melt for about 0.5 h more. The compounds listed in Table 1 were prepared in accordance 2 1 q6858 6 O. ~ . 5014 with this procedure.
7 O.Z. 5014 T~hle 1: Blocked aliphatic polyi~ocyanate adduct~ contAi n i ng urea groups Example A Composition in mol Chemicsl and physical ' ~cs Diis~ - Caprolactam Di~ine NCO content Mclting Glass [% by wt range l" i~
DI 51 HDI f~wtotal [~C] t~ c rocl 2 - I.S IPD (1.25) 0.3 8.5 118-120 48-67 2 - 1.75 I.S IPD (1) 0.4 9.7 96-98 38-60 3 - 1.85 1.5 HMDA (1) 1.610.2 107-109 40~0 4 1.85 - 1.5 HMDA (1) 1.610.2 106-109 41-61 - 2 2 L~romin C 260 (1) 0.4 10.3 77-79 31-57 6 - 2 2 HMDA (1) 0.310,7 128-130 69-85 7 - 1.85 I.S IPD (1) 1.410.8 92-9S 41~0 8 2 - 2 IPD (I) O.S11.2 75-78 39-48 9 - 2 2 IPD (1) 0.511.0 72-74 33-60 O~
- 2 1.5 ~D (1) 3.012.0 96-99 39-57 8 O.Z. 5014 TAhle 1: Blocked aliphatic polyisocyanate adducts containing urea ~lolr~ contin-le~
Example A Composition in mol Chemical and physical _ Di;i~ - Caprola- Diamine NCO cont~nt Melting Glass ctam [% by wt~ r~nge 1l ~n DI 51 HDI free tot l [~C] t~,.. ~,~,., rocl I l - 2 5 2 HMDA (1 5) 0.5 12.8 144-147 97-110 12 2 - 2 Laromin C 260 (1) 0.3 10 3 103-107 38-59 13 2 1 5 IPD (1) 3 5 11.9 94-101 42-61 14 2 - 2 HMDA (1) 0 4 10 5 121-127 62-79 9 O.Z. 5014 B polyol component General preparation procedure The starting components - terephthalic acid (TA), dimethyl terephthalate (DMT), 1,6-hexanediol (HD), neopentylglycol (NPG), 1,4-dimethylolcyclohexane (DMC) and trimethylolpropane (TMP) - are placed in a reactor and heated with the aid of an oil bath. After the substances have predominantly melted, 0.5 % by weight of di-n-butyltin oxide as catalyst is added at a temperature of 160~C. Initial elimination of methanol occurs at a temperature of about 170~C. The temperature is raised to 220 - 230~C over the course of from 6 to 8 hours, and the reaction is brought to an end within a further 12 to 15 hours. The polyester i8 cooled to 200~C and substantially lS freed from volatile constituents by applying a vacuum (1.33 mbar) over the course of from 30 to 45 minutes.
Throughout the reaction period the bottom product is stirred and a gentle stream of N2 is passed through the reaction mixture.
Table 2 shows commercial polyesters and polyester compositions with the corresponding physical and chemical characteristics.
0. Z . 5014 TAhl e 2: Polye~ters Example Startingc~ Chemical and~ ic l~' _ B TA DMT HD NPG DMC TMP OH Acid M.p. DTA Viscosity [mol] [mol] [moll [mol][mol] [mol] number number [~C] [~C] at 160~C
[mg of [mg of [mPa-s]
KOH/gl KoH/Rl 6.25 10.5 2 2.9 SS-60 3~ about 75 about 50 z 25,000 2 CRYLCOAr280UCB/Bel~ium z 50 < 10 100 ~ 8 SS ~ 8 3 9 ¦ 9 ¦ 3 ¦ 13 ¦ 3 l l 50-56 3-4 about70 aboutS0 z 10,000 4 ALFTALAT~ AN 739 Hoechst/Italy SS-60 2-4 82-90 > 50 24-29,000 11 O.Z. 5014 C Polyurethane powder coati ng8 General preparation procedure The comminuted products - blocked isocyanate adducts (crosslinking agents), polyesters, leveling agent masterbatch and, if used, catalyst masterbatch - are intimately mixed, optionally with the white pigment, in an edge runner mill and the mixture is subsequently homogenized in an extruder at a temperature of not more than 130~C. After cooling, the extrudate is fractionated and ground with a pinned-disk mill to a particle size of < 100 ~m. The resulting powder is applied using an electrostatic powder s~aying unit at 60 kV to degreased, optionally pretreated iron panels which are baked at temperatures between 160 and 200~C in a convection oven.
lS Leveling a~ent masterbatch 10 % by weight of the leveling agent - a commercially available copolymer of butyl acrylate and 2-ethylhexyl acrylate - is homogenized in the melt in the corresponding polyester, and the solidified melt is comminuted.
Catalyst masterbatch 5 % by weight of the catalyst - DBTL - is homogenized in the melt in the corresponding polyester and the solidified melt is comminuted.
The abbreviations in the Tables below have the following meanings:
CT = Coat thickness in ~m EI = Erichsen indentation in mm (DIN 53 156) CH = Cross-hatch test (DIN 53 151) 30 GG 60~~ = Gardner gloss measurement in scale divisions (ASTM-D 5233) mp. rev. = Impact reverse in g-m ~ ~ ~ -- 1-- ~ ~ ~ O O ~
e~ ~
~ _ ~ g l ~ o o ~
O ~ ~ , ~ o ~ ~i O o o~ ,, o ~ ~ ~ o Q~
o o ~ o ~
--~ 3 ~ x ~ o - ~o ~ ~ x 3 X ~ ~ ~ o ~ o ~ ~
D Q~
~ ~ 5 ~ co ~ ~ ~ 8 O a~ x 1- ~ ' I_ , X A ~
~, ~, X X oo o o '~
'~ o _ ~ ~ ~
~' 8 9 8 8 t -~ 5 o 2 U~ o U~
13 O. Z . 5014 2 ~ -n1-~A ~ows~r C~ ir~g~ With A rQ~ C~ ,e of ~108 Ahle 4 ExampleC 13 14 15 16 17 18 19 20 21 22 23 24 Fr ' C.~ ~ ~ ine 31.29 30.22 28.73 29.530.01 29.03 27.60 28.32 26.91 26.23 28.56 27.07 sgentacc. toA (2) (3) (3) (3) (5) (7) (7) (7) (10) (lo) (12) (13) Example () Polyester acc. to 68.71 69.78 - 69.99 70.97 - - 73.09 - - 72.93 B I
Polyester acc. to - - 71.27 - - - 72.40 - - - 71.44 Polyester acc. to - - - 70.S - - - 71.68 - 73.77 Notes All f ' contain 40 % by wei~ht of TiO, (white pi~mcnt) and 0,S % by wei~ht each of bveUnK agont and benzoin; the OH/NCO ratio is 1: 1 Co~tings data ~:;(} 60~ <1: 42 37 33 41 58 48 40 Sl 44 53 63 49 EI 4.S/S.3 9.0 6.2/7.08.519.2 > 10 8.1/83 7.617.88.719.27.S17.98.1/8.5> 10 80/8.3 Imp. rev. 115.2 >944.6 576 806.4 >944.6 806.4 806.4 ~944.6 691.2 691.2 >944.6 576 Notes T' . e ~ ~ 200~C/8 to 15 minutes, 180~C/15 to 25 minute~ O~
C~
< r~
Claims (10)
1. A completely or partially .epsilon.-caprolactam-blocked aliphatic diisocyanate adduct which is chain-extended with an aliphatic or cycloaliphatic diamine and has the following formula:
(I) wherein:
R is a group derived from the aliphatic diisocyanate OCN-R-NCO and is , , -(CH2)6- , , or ;
R' is a group derived from the diamine H2N-R'-NH2 and is an alkylene or cycloalkylene radical of 2 - 16 carbon atoms;
B is the residue of .epsilon.-caprolactam of the formula ;
n is a number of 1 - 3; and x is a number of 0 - 0.5.
(I) wherein:
R is a group derived from the aliphatic diisocyanate OCN-R-NCO and is , , -(CH2)6- , , or ;
R' is a group derived from the diamine H2N-R'-NH2 and is an alkylene or cycloalkylene radical of 2 - 16 carbon atoms;
B is the residue of .epsilon.-caprolactam of the formula ;
n is a number of 1 - 3; and x is a number of 0 - 0.5.
2. A diisocyanate adduct as claimed in claim 1, wherein which has a molecular weight of from 600 to 1,400, a melting point of from 60 to 160°C, a content of urea groups of 2 - 4 mmol/g, a blocked NCO content of 7 - 15% by weight and a free NCO content of 0.1 - 5% by weight.
3. A diisocyanate adduct as claimed in claim 1 or 2, wherein the aliphatic diisocyanate employed is selected from the group consisting of hexamethylene diisocyanate (HDI), 2-methylpentamethylene diisocyanate (DI 51) which may contain up to 10% by weight of 2-ethyltetramethylene diisocyanate, 2,2,4 (or 2,4,4)-trimethylhexamethylene diisocyanate and 5-methylnonamethylene diisocyanate.
4. A diisocyanate adduct as claimed in any one of claims 1 to 3, wherein the aliphatic or cycloaliphatic diamine is a member selected from the group consisting of ethylenediamine, trimethylenediamine, tetramethylenediamine, hexamethylenediamine, octamethylenediamine, 2-methylpentamethylenediamine, 2,2,4 (or 2,4,4)-trimethylhexamethylenediamine, 1,4-diaminocyclohexane, 2,4-diamino-1-methylcyclohexane, 4,4'-diaminodicyclohexylmethane (HMDA), 4,4'-diamino-3,3'-dimethyldicyclohexylmethane and isophoronediamine (IPD).
5. A process for preparing a compound as claimed in any one of claims 1 to 4, which comprises first reacting the aliphatic diisocyanate of the formula OCN-R-NCO with .epsilon.-caprolactam at 80 - 150°C and then adding the diamine of the formula H2N-R'-NH2 in portions.
6. A heat-curable pulverulent composition, comprising:
a) 100 parts by weight of an OH-containing polymer with more than two OH groups, b) 15 - 60 parts by weight of the blocked diisocyanate adduce according to any one of claims 1 to 4, c) 0 - 160 parts by weight of a pigment, d) 0 - 200 parts by weight of a filler, e) 0 - 5 parts by weight of a catalyst, and f) 0.5 - 5 parts by weight of a leveling agent.
a) 100 parts by weight of an OH-containing polymer with more than two OH groups, b) 15 - 60 parts by weight of the blocked diisocyanate adduce according to any one of claims 1 to 4, c) 0 - 160 parts by weight of a pigment, d) 0 - 200 parts by weight of a filler, e) 0 - 5 parts by weight of a catalyst, and f) 0.5 - 5 parts by weight of a leveling agent.
7. A heat-curable pulverulent composition as claimed in claim 6, which comprises as the OH-containing polymer, a polyesterpolyol having a molecular weight of between 700 and 3,000, an OH number of 25 to 240 mg of KOH/g, and an OH
functionality of greater than 2.
functionality of greater than 2.
8. A heat-curable pulverulent composition as claimed in claim 6 or 7, which comprises more than 0 part of a catalyst.
9. A heat-curable pulverulent composition as claimed in claim 8, which comprises as the catalyst, dibutyltin dilaurate, tin(II) octoate, or dibutyltin maleate.
10. A completely or partially .epsilon.-caprolactam-blocked aliphatic diisocyanate adduct which is chain-extended with an aliphatic or cycloaliphatic diamine and is obtainable by reacting the diisocyanate with .epsilon.-caprolactam and then with the diamine.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE1996104326 DE19604326A1 (en) | 1996-02-07 | 1996-02-07 | Blocked and chain-extended diisocyanate adducts, a process for their preparation and their use |
| DE19604326.3 | 1996-02-07 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2196858A1 true CA2196858A1 (en) | 1997-08-08 |
Family
ID=7784685
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002196858A Abandoned CA2196858A1 (en) | 1996-02-07 | 1997-02-05 | Blocked and chain-extended diisocyanate adducts, a process for preparing them and their use |
Country Status (4)
| Country | Link |
|---|---|
| EP (1) | EP0789044A1 (en) |
| JP (1) | JPH09221535A (en) |
| CA (1) | CA2196858A1 (en) |
| DE (1) | DE19604326A1 (en) |
Family Cites Families (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| BE758924A (en) | 1969-11-15 | 1971-05-13 | Bayer Ag | PULVERULENT COATING AGENTS |
| US3857818A (en) * | 1972-09-18 | 1974-12-31 | Cook Paint & Varnish Co | Blocked polyurethane powder coating compositions |
| GB1465286A (en) | 1974-09-23 | 1977-02-23 | Ucb Sa | High reactivity masked diisocyanates and thermosetting pulverulent compositions containing them |
| DE2945113A1 (en) * | 1979-11-08 | 1981-05-14 | Chemische Werke Hüls AG, 4370 Marl | Thermosetting lacquer mixt. - contg. epoxy! resin and isophorone di:isocyanate adduct contg. blocked urea, biuret carbodiimide, urethane and/or isocyanurate gps. |
| DE3004876A1 (en) | 1980-02-09 | 1981-08-20 | Chemische Werke Hüls AG, 4370 Marl | Reactive blocked poly:isocyanate(s) - comprise reaction prod. of caprolactam with adduct of poly:ol and isophorone di:isocyanate esp. used for polyurethane powder coatings |
| DE3143060A1 (en) | 1981-10-30 | 1983-05-11 | Chemische Werke Hüls AG, 4370 Marl | Powder coatings based on blocked isophorone diisocyanate adducts |
| US4410678A (en) * | 1981-12-28 | 1983-10-18 | Ford Motor Company | Coating composition comprising chain-extendable crosslinkable polyol and diblocked diisocyanate diurea oligomer |
| DE3536017A1 (en) | 1985-10-09 | 1987-04-09 | Huels Chemische Werke Ag | TRANS-CYCLOHEXANE-1,4-DIISOCYANATE BLOCKED ALL OR PARTLY WITH EPSILON-CAPROLACTAM, THEIR PRODUCTION AND USE |
| DE3739479A1 (en) * | 1987-11-21 | 1989-06-01 | Huels Chemische Werke Ag | PUR POWDER COATINGS FOR MATS |
| DE3739480A1 (en) * | 1987-11-21 | 1989-06-01 | Huels Chemische Werke Ag | METHOD FOR PRODUCING BLOCKED UREA GROUP-CONTAINING POLYISOCYANATES AND THE PRODUCTS MANAGED THEREFROM |
-
1996
- 1996-02-07 DE DE1996104326 patent/DE19604326A1/en not_active Withdrawn
- 1996-12-13 EP EP96120042A patent/EP0789044A1/en not_active Withdrawn
-
1997
- 1997-02-04 JP JP9021171A patent/JPH09221535A/en active Pending
- 1997-02-05 CA CA002196858A patent/CA2196858A1/en not_active Abandoned
Also Published As
| Publication number | Publication date |
|---|---|
| JPH09221535A (en) | 1997-08-26 |
| DE19604326A1 (en) | 1997-08-14 |
| EP0789044A1 (en) | 1997-08-13 |
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