Polymers and use of these as dispersants

Abstract

A polymer comprises at least one functional group of the formula (I) bound to one of the termini and/or to the backbone of the polymer, or a salt thereof. # indicates the point of attachment to the terminus and/or to the polymer backbone; A is a chemical bond or a divalent moiety selected from the group consisting of C.sub.1-C.sub.6 alkylene, O(C.sub.2-C.sub.6 alkylene), C(O)O(C.sub.2-C.sub.6 alkylene), NR.sup.3(C.sub.2-C.sub.6 alkylene) and C(O)NR.sup.3(C.sub.2-C.sub.6 alkylene), where the C.sub.2-C.sub.6 alkylene part is attached to Q; Q is a divalent moiety selected from the group consisting of O, NH and S; and X is a divalent moiety selected from the group consisting of linear C.sub.1-C.sub.10 alkylene, linear C.sub.2-C.sub.6 alkenylene, C.sub.4-C.sub.7 cycloalkylene, arylene and alkarylene, wherein the linear C.sub.1-C.sub.10 alkylene, the linear C.sub.2-C.sub.6 alkenylene, the C.sub.4-C.sub.7 cycloalkylene, the arylene and the alkarylene may be substituted. ##STR00001##

Claims

1. A polymer P comprising at least one functional group of the formula (I): ##STR00016## bound to one of the termini and/or to the backbone of the polymer, or a salt thereof, wherein: # indicates the point of attachment to the terminus and/or to the polymer backbone; k is 0, 1, 2, 3 or 4; m is 0, 1, 2, 3, 4, 5, 6, 7, 8 or 9; A is a chemical bond or a divalent moiety selected from the group consisting of C.sub.1-C.sub.6 alkylene, O(C.sub.2-C.sub.6 alkylene), C(O)O(C.sub.2-C.sub.6 alkylene), NR.sup.3(C.sub.2-C.sub.6 alkylene) and C(O)NR.sup.3(C.sub.2-C.sub.6 alkylene), where the C.sub.2-C.sub.6 alkylene part is attached to Q; Q is a divalent moiety selected from the group consisting of O, NH and S; R.sup.1 is independently selected from the group consisting of OH, COOH, COOCH.sub.3, NH(C.sub.1-C.sub.6 alkyl), N(C.sub.1-C.sub.6 alkyl).sub.2, NO.sub.2, S(O).sub.2R.sup.4, C.sub.1-C.sub.20 alkyl, C.sub.1-C.sub.4 alkoxy, halogen, aryloxy, aryl, heteroaryl, where aryl, hetaryl and aryloxy are unsubstituted or substituted by 1, 2, 3 or 4 radicals selected from the group consisting of OH, COOH, COOCH.sub.3, NH.sub.2, NH(C.sub.1-C.sub.6 alkyl), N(C.sub.1-C.sub.6 alkyl).sub.2, NO.sub.2, S(O).sub.2R.sup.4, C.sub.1-C.sub.4 alkyl, C.sub.1-C.sub.4 alkoxy and halogen; R.sup.2 is selected from the group consisting of hydrogen, S(O).sub.2R.sup.4, C.sub.1-C.sub.20 alkyl, C.sub.3-C.sub.10 cycloalkyl, aryl, heteroaryl, aryl-C.sub.1-C.sub.4-alkyl and heteroaryl-C.sub.1-C.sub.4-alkyl, where aryl and hetaryl in the four last mentioned radicals are unsubstituted or substituted by 1, 2, 3 or 4 radicals selected from the group consisting of OH, COOH, COOCH.sub.3, NH.sub.2, NH(C.sub.1-C.sub.6 alkyl), N(C.sub.1-C.sub.6 alkyl).sub.2, NO.sub.2, S(O).sub.2R.sup.4, C.sub.1-C.sub.4 alkyl, C.sub.1-C.sub.4 alkoxy and halogen; X is a divalent moiety selected from the group consisting of linear C.sub.1-C.sub.10 alkylene, linear C.sub.2-C.sub.6 alkenylene, C.sub.4-C.sub.7 cycloalkylene, arylene and alkarylene, where the linear C.sub.1-C.sub.10 alkylene, linear C.sub.2-C.sub.6 alkenylene and C.sub.4-C.sub.7 cycloalkylene are unsubstituted or substituted by 1, 2, 3 or 4 radicals selected from the group consisting of C.sub.1-C.sub.18 alkyl or C.sub.1-C.sub.18 alkenyl, and where arylene and alkarylene are unsubstituted or substituted by 1, 2, 3 or 4 radicals selected from the group consisting of C.sub.1-C.sub.4 alkyl, C.sub.1-C.sub.4 haloalkyl, aryl, COOH, COOCH.sub.3, NO.sub.2 or halogen; R.sup.3 is selected from the group consisting of hydrogen, S(O).sub.2R.sup.4, C.sub.1-C.sub.20 alkyl, C.sub.3-C.sub.10 cycloalkyl, aryl and heteroaryl, where aryl and hetaryl are unsubstituted or substituted by 1, 2, 3 or 4 radicals selected from the group consisting of OH, COOH, COOCH.sub.3, NH.sub.2, NH(C.sub.1-C.sub.6 alkyl), N(C.sub.1-C.sub.6 alkyl).sub.2, NO.sub.2, S(O).sub.2R.sup.4, C.sub.1-C.sub.4 alkyl, C.sub.1-C.sub.4 alkoxy and halogen; R.sup.4 is selected from the group consisting of OH, NH.sub.2, NH(C.sub.1-C.sub.6 alkyl), N(C.sub.1-C.sub.6 alkyl).sub.2, C.sub.1-C.sub.4 alkyl, C.sub.1-C.sub.4 alkoxy, aryl and heteroaryl, where aryl and hetaryl are unsubstituted or substituted by 1, 2, 3 or 4 radicals selected from the group consisting of C.sub.1-C.sub.4 alkyl, C.sub.1-C.sub.4 alkoxy and halogen; Y is selected from OH or a moiety of the general formula (I.2): ##STR00017## where * indicates the point of attachment to the carbonyl group and #, k, m, A, Q, R.sup.1 and R.sup.2 are as defined above; and the polymer P is selected from the group consisting of a polyester, a polyether, a polyetherester, a polycarbonate and a polymer having a CC-backbone, in which the polymer having a CC-backbone comprises repeating units M1 selected from the group consisting of a polymerized C.sub.1-C.sub.10-alkyl (meth)acrylate, a polymerized C.sub.1-C.sub.10-alkyl-(poly-C.sub.2-C.sub.4-alkyleneglycol) (meth)acrylate and a polymerized vinylaromatic hydrocarbon compound.

2. The polymer P of claim 1, wherein: k is 0 or 1; m is 0 or 1; A is a chemical bond or a divalent moiety selected from the group consisting of C(O)O(C.sub.2-C.sub.4 alkylene) and C(O)NH(C.sub.2-C.sub.4 alkylene), where the alkylene part is attached to Q; Q is a divalent moiety selected from the group consisting of O and NH; R.sup.1 is independently selected from the group consisting of OH, COOH, COOCH.sub.3, NH.sub.2, NH(C.sub.1-C.sub.6 alkyl), N(C.sub.1-C.sub.6 alkyl).sub.2, NO.sub.2, S(O).sub.2R.sup.4, C.sub.1-C.sub.4 alkyl, C.sub.1-C.sub.4 alkoxy, halogen, phenyl and pyridyl; R.sup.2 is selected from the group consisting of hydrogen, C.sub.1-C.sub.4 alkyl and phenyl; X is selected from the group consisting of linear C.sub.2-C.sub.6 alkylene, C.sub.2-alkenylene and 1,2-phenylene, where C.sub.2-C.sub.6 alkylene and C.sub.2-alkenylene are unsubstituted or carry a C.sub.1-C.sub.18 alkyl or C.sub.1-C.sub.18 alkenyl radical and 1,2-phenylene is unsubstituted or substituted by 1 or 2 radicals selected from the group consisting of C.sub.1-C.sub.3 alkyl, COOH or halogen; R.sup.4 is selected from the group consisting of NH.sub.2, NH(C.sub.1-C.sub.6 alkyl), N(C.sub.1-C.sub.6 alkyl).sub.2 and C.sub.1-C.sub.4 alkyl; and Y is selected from OH.

3. The polymer P of claim 2, wherein: k and m are both 0; R.sup.2 is hydrogen; and X is C.sub.2-C.sub.4 alkylene.

4. The polymer P of claim 1, which is a poly-(C.sub.2-C.sub.4-alkylene oxide).

5. The polymer P of claim 1, which is an aliphatic polyester.

6. The polymer P of claim 1, which is an aliphatic polyether-ester.

7. The polymer P of claim 1, which is an aliphatic polycarbonate.

8. The polymer P of claim 1, which has a CC-backbone comprising repeating units M1 selected from a polymerized C.sub.1-C.sub.10-alkyl (meth)acrylate, a polymerized C.sub.1-C.sub.10-alkyl-(poly-C.sub.2-C.sub.4-alkyleneglycol) (meth)acrylate and a polymerized vinylaromatic hydrocarbon compound, wherein the repeating units M1 make up from 10 to 90% by weight of the polymer P.

9. The polymer P of claim 1, which has a number average weight in the range from 500 to 100,000 Dalton.

10. The polymer P of claim 1, which has an acid number in the range of from 3 to 500 mg KOH/g.

11. A process for manufacturing the polymer P of claim 1, the process comprising reacting a polymer P.1 comprising at least one radical of formula (I.1): ##STR00018## bound to one of the termini and/or backbone of the polymer; and reacting the polymer P.1 with an acid anhydride of formula (IV): ##STR00019## wherein X is a divalent moiety selected from the group consisting of linear C.sub.1-C.sub.10 alkylene, linear C.sub.2-C.sub.6 alkenylene, C.sub.4-C.sub.7 cycloalkylene, arylene and alkarylene, where the linear C.sub.1-C.sub.10 alkylene, linear C.sub.2-C.sub.6 alkenylene and C.sub.4-C.sub.7 cycloalkylene are unsubstituted or substituted by 1, 2, 3 or 4 radicals selected from the group consisting of C.sub.1-C.sub.18 alkyl or C.sub.1-C.sub.18 alkenyl, and where arylene and alkarylene are unsubstituted or substituted by 1, 2, 3 or 4 radicals selected from the group consisting of C.sub.1-C.sub.4 alkyl, C.sub.1-C.sub.4 haloalkyl, aryl, COOH, COOCH.sub.3, NO.sub.2 or halogen, such that if X carries 2, 3 or 4 COOH groups, two COOH groups optionally form an anhydride group.

12. The process of claim 11, comprising reacting a polymer P comprising at least one functional moiety of the formula A-Q-H attached to one of the termini and/or to the backbone of the polymer P with a compound of the formulae (II), (II) or (III): ##STR00020## wherein: R.sup.L is hydrogen or a hydrocarbon radical having 1 to 8 carbon atoms; and the polymer P does not have a functional group of the formula (I.1).

13. A liquid composition in the form of a dispersion comprising: a fine particulate solid material selected from the group consisting of a pigment and a filler; and a liquid diluent; and the polymer P of claim 1 or salt thereof, wherein the fine particulate solid material is dispersed in the liquid diluent.

14. The liquid composition of claim 13, wherein a weight ratio of fine particulate solid material to the polymer P is in the range from 100:1 to 1:50.

15. The liquid composition of claim 13, comprising i) 1 to 70% by weight, based on the total weight of the liquid composition, of at least one of the fine particulate solid material; ii) 0.5 to 50% by weight, based on the total weight of the liquid composition, of at least one of the polymer P optionally in the form of a salt; and iii) 10 to 98.5% by weight, based on the total weight of the liquid composition, of at least one of the liquid diluent.

16. The liquid composition of claim 13, which is in the form of a millbase.

17. The liquid composition of claim 13, which is in the form of a coating composition.

18. The liquid composition of claim 13, which is in the form of an ink.

19. A dispersant comprising the polymer P of claim 1 or salt thereof, said dispersant adapted to function as a dispersant for fine particulate solid material selected from the group consisting of a pigment and a filler.

20. The dispersant of claim 19, which is in a liquid composition selected from the group consisting of a coating composition, a millbase and an ink.

21. A composition comprising the polymer P of claim 1 or salt thereof, said composition selected from the group consisting of a crosslinking agent, a rheology modifier, an impact modifier, a chain extender, and a building block for preparation of block- or graft-copolymers.

22. The polymer P of claim 1, wherein the polymer P is selected from the group consisting of a polyester, a polyether, a polyetherester, a polycarbonate and a polymerized vinylaromatic hydrocarbon compound.

23. The polymer P of claim 1, wherein the at least one functional group is bound to one of the termini of the polymer.

24. The polymer P of claim 1, wherein the at least one functional group is bound to the backbone of the polymer.

Description

PREPARATION EXAMPLES

Abbreviations

(1) EO ethylene oxide

(2) PO propylene oxide

(3) CL epsilon-caprolactone

(4) VL delta-valerolactone

(5) n-BA n-butyl acrylate

(6) DBTL dibutyltin dilaurate

(7) HEA 2-hydroxyl ethyl acrylate

(8) IA isatoic anhydride

(9) MPEG methoxy polyethylene glycol

(10) bis-MPA 2,2-dimethylolpropionic acid

(11) 2-ODSA 2-octadecenylsuccinic anhydride

(12) BTCA 1,2,4-benzenetricarboxylic anhydride

(13) AMP 2-amino-2-methyl-1-propanol

(14) TABLE-US-00001 TABLE 1 Commercially available Polymers P used: Name of Polymer P Supplier Acryflow P-120 (Acrylic polyol, OH number: 120 mg KOH/g) LyondellBasell Boltorn H20 (dentritic polymer based on bis-MPA, 16 terminal Perstorp hydroxyl groups, molecular mass approx. 2100 g/mol) Acryflow P-120 (Acrylic polyol, OH number: 120 mg KOH/g) LyondellBasell Oxymer M112, polyethylene carbonate diol, molecular mass approx. Perstorp 1000 g/mol) Jeffamine M2070 (polyether monoamine, molecular mass approx. Huntmann 2000 g/mol) Jeffamine ED2003 (polyether diamines, molecular mass approx. Huntmann 2000 g/mol) Pluriol A350 E (Methyl polyethylene glycol, molecular mass approx. BASF 350 g/mol) Pluriol A500 E (Methyl polyethylene glycol, molecular mass approx. BASF 500 g/mol) Lutensol ON 110 (C.sub.10-Oxo alcohol ethoxylate with 11 EO units) BASF Lutensol AT 11 (C.sub.16-18-fatty alcohol ethoxylate with 11 EO units) BASF

(15) The following polymers P1 to P6 were prepared as starting materials for polymers P.

(16) Polymer P1: OH-Terminated Polyetherester (MPEG350-4CL-VL-OH)

(17) A mixture of 35 g (0.1 mol) of methyl polyethylene glycol (M.sub.W of 350 g/mol), 45.6 g (0.4 mol) of epsilon-caprolactone and 10.0 g (0.1 mol) of delta-valerolactone was treated with 0.1 g of dibutyltin dilaurate under inert gas and heated to 160 C. until a solids content of 97% had been reached. The polyetherester was obtained as a yellow/colorless liquid with an OH number of 65 mg KOH/g.

(18) Polymer P2: Polyester of Stearyl Alcohol and -Caprolactone

(19) A mixture of 27 g (0.1 mol) of stearyl alcohol and 80.0 g (0.7 mol) of epsilon-caprolactone was treated with 0.2 g of dibutyltin dilaurate (DBTL) under inert gas and heated to 160 C. until an SC (solids content) of 97% has been reached. The product was obtained as a white solid with an OH number of 54 mg KOH/g.

(20) Polymer P3: Hyperbranched Polyester of Boltorn H20, -Valerolactone and -Caprolactone

(21) A mixture of 10 g of Boltorn H20, 50.0 g (0.44 mol) of epsilon-caprolactone and 44.0 g (0.44 mol) of delta-valerolactone was treated with 0.07 g of DBTL under inert gas and heated to 160 C. until a solid content of 97% was reached. The product was obtained as a yellow clear liquid with an OH number of 50 mg KOH/g.

(22) Polymer P4: Poly(nBA60-b-PolyHEA10)

(23) ##STR00013##

(24) A mixture of 78 g (0.01 mol) of living linear polymer poly(BA) (prepared according to example 1 of US 2011/0224375) and 23.2 g (0.2 mol) of 2-hydroxyl ethyl acrylate was stirred under nitrogen at room temperature for 30 min. Then the mixture was heated at 120 C. until a SC of 88% was reached. Residual 2-hydroxyl ethyl acrylate monomer was removed under 5 mbar vacuum (at 130 C. for 2 hours). A viscous yellowish title compound Poly(nBA60-b-PolyHEA10) was obtained (SC of 98%) with an OH number of 65 mg KOH/g.

(25) Polymer P5: Poly(nBA30) End Functionalized with OH Group: PnBA30-OH

(26) ##STR00014##

(27) The title compound was prepared according to example 1 of WO 2011/120947.

(28) Polymer P6: OH Telechelic Poly(nBA35): HO-PnBA35-OH

(29) ##STR00015##

(30) The title compound was prepared according to example 3 of WO2011/120947.

Example 1

(31) A mixture of 50.0 g (0.1 mol OH) of Pluriol A500 E, 16.3 g (0.1 mol) of isatoic anhydride (IA) and 0.2 g (0.3 wt.-%) of 4-dimethylaminopyridine were heated at 80140 C. until no more carbon dioxide was evolved. Then, 10.0 g (0.1 mol) succinic anhydride (SSA) was added and the reaction mixture was heated at 80 C. for additional 3 hours. The obtained product was a yellowish liquid with an acid number of 75 mg KOH/g.

Examples 2-19

(32) Examples 2-19 were prepared in a similar manner as Example 1, except that the type of OH or amine functionalized polymer, the type of cyclic anhydride (CA) and the ratio of OH (amine) group to isatoic anhydride (IA) and the cyclic anhydride (CA), respectively, were varied as detailed in Table 2 below.

(33) TABLE-US-00002 TABLE 2 OH/amine functionalized polymer Cyclic Molar ratio.sup.2) OH/NH.sub.2 No..sup.1) Anhydride OH/NH.sub.2 to IA Acid No..sup.3) Example (mg KOH/g) (CA) to CA (mg KOH/g) 2 LutensolAT11 ca. 75 SAA 1:1:1 60 3 Polymer P1 65 SAA 1:1:1 51 4 Polymer P2 54 SAA 1:1:1 44 5 Boltorn H20 ca. 510 SAA 0.25:1:1 265 6 Polymer P3 50 SAA 1:1:1 40 7 Polymer P4 65 SAA 1:1:1 50 8 Polymer P5 17 SAA 1:1:1 10 9 Polymer P6 23 SAA 1:1:1 21 10 Acryflow P-120 120 SAA 1:1:1 81 11 Jeffamine 30 SAA 1:1:1 24 M2070 12 Jeffamine 50 SAA 1:1:1 43 ED2003 13 Oxymer M112 110 SAA 1:1:1 76 14 Plurio A350E 160 Glutaric anhydride 1:1:1 94 15 LutensolON110 90 Maleic anhydride 1:1:1 65 16 Polymer P1 65 2-ODSA.sup.4) 1:1:1 38 17 Polymer P2 54 Phthalic anhydride 1:1:1 41 18 LutensolAT11 75 BTCA.sup.5) 1:1:1.sup.6) 98 19 Pluriol A500E 110 Pyromellitic 1:1:0.5 74 dianhydride .sup.1)OH or amine number of the polymer P .sup.2)molar ratio of OH or amine groups to compounds II or III .sup.3)acid number of the resulting polymer P .sup.4)2-ODSA: 2-octadecenylsuccinic anhydride .sup.5)BTCA: 1,2,4-benzenetricarboxylic anhydride .sup.6)stirred at 130 C. after anhydride addition

(34) Performance Testing

(35) In order to test the dispersion effect of the obtained samples, Resin Free Pigment Concentrates (mill-base) were prepared according to the following Formulations F1, F2 and NF2. The mill-base was dispersed in Scandex Shaker for 1 h with the help of glass beads. Afterwards the mill base was filtered and stored at room temperature overnight.

(36) Preparation of Mill-base Formulations F1 and F2, the 2-amino-2-methyl-1-propanol (AMP) neutralized Mill-base Formulation NF2 and the comparative Mill-base Examples C1 and C2:

(37) TABLE-US-00003 Mill-base No. Ingredients F1 C1 F2 NF2 C2 1) Polymer P (100% solid) [g] 0.8 0.3 0.3 2) Palatinol P 10 [g] 12.7 13.5 3) Water [g] 9.7 9.63 10.0 4) AMP, 70% active [g] 0.07 5) Pigment Kronos 2310 [g] 26.5 26.5 30.0 30.0 30.0 6) 2.0 mm glass beads [g] 40.0 40.0 40.0 40.0 40.0 Total (g) 80.0 80.0 80.0 80.0 80.0 Palatinol P 10 (plasticizer di-2-propylheptylphthalat, BASF) Pigment Kronos 2310 (Kronos Inc.)

(38) In addition, competitive dispersants were synthesized according to EP0417490A. The performance of these dispersants was tested according to Formulations 1 and 2. Results showed that example 17 (tripropylenglycolmonomethylether--caprolactone-phosporic aicd), performs better than the others, which was then taken as a comparison dispersant C3.

(39) The performance of the polymers P of examples 1 to 19 was tested by determining the rheological behaviour of the Millbase Formulations F1, F2, and NF2, including the specified amount of polymer P. The rheological behavior of the millbases was measured at 23 C. with a Thermo-Haake RheoStress 600 rheometer under CR-mode with rotation speed of 60 sec.sup.1, respectively, using a cone-plate sensor. The millbases containing the polymers P flowed well and their viscosities were comparable or lower than the product of the comparative example. Results are summarized in table 3:

(40) TABLE-US-00004 TABLE 3 The dispersion effect in clear coat paint system (millbases containing the polymers P) Viscosity of millbases based on F1, F2 and NF2 (mPas).sup.2) Example F1 F2 NF2 C1 2450 C2 6350 C3.sup.1) 5800 4250 1650 1 450 3300 2 530 >10000 450 3 7800 >10000 450 4 2700 7 2500 8 3750 11 1050 850 18 750 >10000 450 19 850 500 .sup.1)Comparative Example C3: example 17 of EP0417490A .sup.2)measured at constant rotation speed of 90 sec.sup.1

(41) The performance of Polymers P was also tested in clear coating systems with respect to gloss and anti-cratering effect. First, let-down formulations (formulations F3 and F4) based on a clear coating system were prepared.

(42) TABLE-US-00005 Formulation F3. Organic solvent based clear-coating system Ingredient % b.w. in Formulation Resin 1 24.7% Resin 2 23.1% Resin 3 11.5% Plasticizer 2.9% Butyl Acetate 18.9% Xylene 18.9% Total 100% Resin 1: Saturated polyester resin in Solvent naphtha/Methoxy propanol/Xylene (Setal 173 VS-60) from Nuplex; Resin 2: Mixture of 64.8 g of a first cellulose acetate butyrate (CAB 381.2) and 25.2 g of a second cellulose acetate butyrate (CAB 381.20) in 255 g butyl acetate and 255 g of xylene, commercially available from Eastman Chemical; Resin 3: Maprenal MF 650: highly reactive isobutylated melamine-formaldehyde resin, commercially available from Ineos; Plasticizer: Resamine HF 480: Polyurea plasticizer, Carbamic resin based on butylurethane and formaldehyde, commercially available from Cytec.

(43) TABLE-US-00006 Formulations F4. Water based clear-coating system Ingredient % b.w. in Formulation Resin 4 99.9% Levelling agent 0.1% Total 100% Resin 4: NeoCryl XK-90: 100% acrylic emulsion polymer from DSM; Levelling agent: EFKA-3570: Levelling and anti-cratering agent for aqueous coatings, neutralized fluorocarbon-modified polyacrylate, commercialy available from BASF.

(44) Then, the following paint compositions were prepared by mixing 1.0 g of the respective millbases F1, F2 and NF2 with 9.0 g of the clear coating systems F3 and F4, respectively, for 5 minutes at 2000 rpm:

(45) TABLE-US-00007 Mill-base Clear coating formulations systems Paint compositions F1 F2 NF2 F3 F4 P1 1.0 g 9.0 g P2 1.0 g 9.0 g P3 1.0 g 9.0 g

(46) The paint was applied on polyester film with a 150 m film thickness.

(47) The gloss of the obtained coatings at 20 angle was determined according to DIN 67530 using a commercial reflectometer (Micro-Tri-Gloss reflectometer from BYK Gardner). The performance was generally very good with satisfactory results, e.g. high gloss in let-down tests. The results are summarized in table 5.

(48) TABLE-US-00008 TABLE 5 Gloss (20) and crater ranking of paint compositions P1, P2 and P3 Based on Gloss (20)/crater ranking.sup.1) Example P1.sup.2) P2.sup.2) P3.sup.2) C1 70.2/3 C2 62.1/3 C3.sup.3) 72.6/2 67.2/2 68.2/2 1 70.2/1 69.1/2 2 74.8/1 60.1/2 71.5/1 3 73.6/2 65.1/2 70.2/1 4 74.5/1 7 75.0/1 8 74.3/2 11 71.3/1 68.5/1 18 75.1/1 63.5/3 69.4/1 19 69.7/1 70.1/1 .sup.1)1 means no crater and 5 means many craters .sup.2)let down films .sup.3)Comparative Example C3: example 17 of EP0417490A