JPS6411232B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a chipping-resistant coating composition. [Conventional technology] Conventionally, one-component urethane paints that can be used as chipping-resistant paints include alkylene oxide adducts of alkylene diamines and blocks.
There is one made of NCO urethane prepolymer (for example, JP-A-57-168957). However, this product did not have sufficient adhesion to the cationic electrodeposited surface and chipping resistance. [Problems to be Solved by the Invention] The present inventors have conducted intensive studies on chipping-resistant paint compositions that have improved adhesion and chipping resistance to electrostatically coated surfaces, particularly cationic electrodeposition coated surfaces, and have developed the present invention. reached. [Means for Solving the Problem] The present invention provides a chipping-resistant coating composition characterized by containing a blocked NCO urethane prepolymer and an oxyalkylene ether of a polyalkylene polyamine having five or more active hydrogen atoms. It is. In the oxyalkylene ether of a polyalkylene polyamine having 5 or more active hydrogens used in the present invention, when the polyalkylene polyamine has less than 5 active hydrogens, it has good adhesion and chipping resistance to electrostatically coated surfaces, especially cationic electrodeposition coated surfaces. is not enough. As a polyalkylene polyamine having 5 or more active hydrogens, the general formula (In the formula, R ₁ is an alkylene group having 2 or more carbon atoms, n1
is an integer of 1 or more). In general formula (1), R ₁ usually has 2 carbon atoms.
~10 preferably 2 to 6 alkylene groups, e.g.
Examples include ethylene group, propylene group, butylene group, and hexamethylene group. n1 is usually 1 to 20,
Preferably it is 1-10. If n1 is O, the chipping resistance will be insufficient, and if it exceeds 20, the adhesion to electrostatically coated surfaces, especially cationic electrodeposition coated surfaces, will decrease. Some of the 5 or more active hydrogen atoms in the compound represented by the general formula (1) are linear or branched alkyl groups (methyl,
Ethyl, n- or i-propyl, n-, i-,
(s- or t-butyl, hexyl, nonyl group, etc.) or alkenyl group (vinyl, octenyl group, etc.) (however, the compound after substitution should have 5 or more active hydrogen atoms). Specific examples of polyalkylene polyamines represented by general formula (1) include polyethylene polyamines (diethylenetriamine, triethylenetetramine,
Tetraethylene pentamine, pentaethylene hexamine, decaethylene undecamine, etc.), polypropylene polyamine (dipropylene triamine, tripropylene tetramine, nonapropylene deca amine, etc.), polybutylene polyamine (dibutylene triamine, etc.), poly(pentamethylene) Polyamines [bis(pentamethylene)triamine, etc.], poly(hexamethylene)polyamines [bis(hexamethylene)triamine, etc.]; and N-alkyl substituted products of these polyalkylene polyamines, [N-hexyl-, N-(2 -ethylhexyl)-, and N-nonyl-tetraethylenepentamine]. Preferred among these are polyethylene polyamine and polypropylene polyamine,
Particularly preferred are diethylenetriamine,
These are triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine and dipropylenetriamine. Two or more of these polyalkylene polyamines may be used in combination. Examples of oxyalkylene ethers of alkylene polyamines having five or more active hydrogen atoms include alkylene oxide adducts of these polyalkylene polyamines. Examples of alkylene oxides include alkylene oxides having 2 to 4 carbon atoms or substituted products thereof (phenyl, halogen substituted products, etc.), such as ethylene oxide, propylene oxide (hereinafter abbreviated as EO and PO, respectively), 1,2-, 1,3 ―
Alternatively, 2,3-propylene oxide, tetrahydrofuran, styrene oxide, epichlorohydrin, etc. may be mentioned. The alkylene oxides may be used alone or in combination of two or more, and in the latter case, block addition, random addition, or a mixture of both may be used. Among the alkylene oxides, preferred are PO, EO, and a combination of PO and EO.
Addition of alkylene oxide can be carried out in a conventional manner, and is carried out without a catalyst or in the presence of a catalyst (alkali catalyst) under normal pressure or increased pressure. Polyalkylene polyamines can be used neat or in a suitable medium [inert liquid (xylene, toluene, etc.),
The alkylene oxide can be added in the presence of an active hydrogen atom-containing liquid (water, polyhydric alcohol such as ethylene glycol, glycerin, etc.) or a polyoxyalkylene ether of a polyalkylene polyamine prepared in advance. The number of moles of alkylene oxide added is usually per active hydrogen atom of polyalkylene polyamine.
The amount is 0.1 mol or more, preferably 0.4 to 15 mol. The total number of moles added of alkylene oxide is usually 0.5~
100 mol, preferably 2.0 to 75 mol. The molecular weight per hydroxyl group of the oxyalkylene ether of this polyalkylene polyamine is usually 30 or more, preferably 50 to 800, particularly preferably 60 to 500. The above polyoxyalkylene ether has the general formula Y-(GH) _l (2) (where Y is a residue of a polyalkylene polyamine having active hydrogen, G is a polyalkylene chain, and l is 5
(is an integer greater than or equal to). Specific examples of oxyalkylene ethers of polyalkylene polyamines having 5 or more active hydrogen atoms include a 0.5 to 10 mole PO adduct of diethylenetriamine and a 0.5 to 10 mole EO adduct of dipropylene triamine. In blocked NCO urethane prepolymer, NCO urethane prepolymer (before blocking)
As an example, an NCO urethane prepolymer made of a polyol having an average functional group number of 2.01 or more consisting of a high-molecular polyol and, if necessary, a low-molecular polyol, and an organic polyisocyanate compound can be mentioned. The average number of functional groups of the above polyol is usually 2.01~
4.5 preferably 2.1 to 3.0. The average number of functional groups is
If it is less than 2.01, adhesion to electrostatically coated surfaces, especially cationic electrodeposition coated surfaces, will be insufficient. Examples of the polymer polyol include polyether polyols, polyester polyols, polymer polyols, and mixtures of two or more of these. Examples of polyether polyols include polytetramethylene ether glycol, which can be obtained by ring-opening polymerization of tetrahydrofuran, low-molecular glycols (ethylene glycol, propylene glycol, 1,4-butanediol, etc.), and low-molecular triols (glycerin, trimethylolpropane, etc.).
hexanetriol, etc.), tetrafunctional or higher-functional low-molecular polyols (pentaerythritol, sorbitol, seuucrose, etc.), or alkylene oxides (alkylene oxides with 2 to 4 carbon atoms, such as EO) of amines (alkanolamines, aliphatic polyamines, etc.). , PO, butylene oxide) adducts, such as polyethylene glycol and polypropylene glycol.
Regarding polytetramethylene glycol, please refer to JP-A-Sho.
It is described in Publication No. 58-11518. Polyester polyols include polycarboxylic acids (aliphatic polycarboxylic acids such as adipic acid,
Maleic acid, dimerized linoleic acid: aromatic polycarboxylic acids such as phthalic acid and low-molecular-weight polyols or polyether polyols containing terminal hydroxyl group-containing polyester polyols, polycaprolactone polyols such as initiators [glycols (ethylene glycol, etc.), triols, etc.] Based on (substituted) caprolactone (ε-
Examples include polyols obtained by addition polymerizing caprolactone, α-methyl-ε-caprolactone, etc.) in the presence of a catalyst (organometallic compound, etc.). As the polymer polyol, those described in JP-A-55-118948 can be used. Among the polymeric polyols, preferred are polytetramethylene ether glycol, polyoxypropylene triol, and polyester polyol (especially polyethylene adipate diol and polycaprolactone polyol). When the polymer polyol is a diol, its hydroxyl group 1
The molecular weight per piece is usually 250 to 2500, preferably 300
~2000, and in the case of trifunctional or higher functional polyols,
The molecular weight per hydroxyl group is usually 180-1800, preferably 200-1500. Diol hydroxyl group 1
When the molecular weight per hydroxyl group is less than 250, and when the molecular weight per hydroxyl group of trifunctional or higher functional polyol is 200
If the molecular weight per hydroxyl group of the diol is greater than 2,500, or if the molecular weight per hydroxyl group of the trifunctional or higher functional polyol is greater than 2,000, the underlying electrodeposition coating surface will be damaged. Adhesion to the surface is insufficient. Examples of low-molecular polyols include low-molecular triols having a molecular weight per hydroxyl group of usually 30 to 150, preferably 40 to 100, and low-molecular diols having a molecular weight per hydroxyl group of 30 to 200, preferably 45 to 200. These are similar to the low-molecular-weight triols and low-molecular diols described in the section on polyether polyols, and their alkylene oxides (EO,
(PO and/or butylene oxide) low molar adducts can be used. Among these low-molecular triols, preferred are trimethylolpropane and glycerin with low mole (1 to 10 moles) adducts of EO and/or PO, and among low-molecular diols, preferred are 1,4-butanediol, low-molecular (Mw200-400) Polypropylene glycol. Examples of polyols with an average number of functional groups of 2.01 or more include (a) bifunctional hydroxyl group-containing polymer polyols with a molecular weight per hydroxyl group of 250 to 2,500, low molecular weight triols with a molecular weight per hydroxyl group of 30 to 150, and if necessary, per hydroxyl group. A polyol consisting of a low molecular weight diol having a molecular weight of 30 to 200, and a trifunctional polymer polyol having a molecular weight per (b) hydroxyl group of 180 to 1800,
Low molecular weight diol with a molecular weight of 30 to 200 per hydroxyl group and, if necessary, a molecular weight of 30 to 150 per hydroxyl group
Examples include polyols consisting of low molecular weight triols. The amount of bifunctional polymer polyol in the polyol (a) is usually 5 to 75 equivalent%, preferably 5 to 50 equivalent%
It is. If the amount of the difunctional polymeric polyol is less than 5 equivalent %, the chipping resistance will be insufficient, and if it exceeds 75 equivalent %, the adhesion to the electrostatically coated surface, especially the cationic electrodeposition coated surface will be insufficient. The amount of low molecular weight triol is usually 10 to 90 equivalent %, preferably 10 to 50 equivalent %. If the amount of low-molecular-weight triol is less than 10% by equivalent, adhesion to electrostatically coated surfaces, especially cationic electrodeposited surfaces, will be insufficient;
If the amount exceeds the equivalent %, chipping resistance will be insufficient. The amount of low molecular weight diol is usually 0 to 85 equivalent %, preferably 15 to 70 equivalent %. If the amount of low molecular weight diol exceeds 85 equivalent %, chipping resistance will be insufficient. The amount of trifunctional polymeric polyol in the polyol (b) is usually 5 to 75% by weight, preferably 5 to 50% by weight. If the amount of trifunctional polymer polyol is less than 5 equivalent%, chipping resistance will be insufficient, and if the amount of trifunctional polymer polyol is less than 5 equivalent%, chipping resistance will be insufficient.
If it exceeds this, the adhesion to electrostatically coated surfaces, especially cationic electrodeposition coated surfaces, decreases. The amount of low molecular weight diol is usually 10 to 90 equivalent %, preferably 15 to 80 equivalent %. 10 low molecular weight diols
If the amount is less than 90% by equivalent, the adhesion to the electrostatically coated surface, especially the cationic electrodeposited surface, will be poor, and if it exceeds 90% by equivalent, the chipping resistance will be poor. Moreover, the amount of low molecular weight triol is usually 0 to 75 equivalent %, preferably 0 to 50 equivalent %. If the amount of low molecular weight triol exceeds 75 equivalent %, chipping resistance will be poor. In the present invention, the organic polyisocyanates include aromatic diisocyanates such as tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), naphthylene diisocyanate, and xylylene diisocyanate, and aliphatic diisocyanates such as aliphatic diisocyanates (hexamethylene diisocyanate, hexamethylene diisocyanate, etc.). lysine diisocyanate, etc.), alicyclic diisocyanates [hydrogenated diphenylmethane diisocyanate (hydrogenated MDI), isophorone diisocyanate (IPDI),
hydrogenated tolylene diisocyanate, etc.], aromatic polyisocyanates such as triphenylmethane triisocyanate, trimethylolpropane, etc.
Examples include 3-mole adducts of TDI, aliphatic polyisocyanates such as hexamethylene diisocyanate trimers and IPDI trimers, and mixtures of two or more thereof. Among these, preferred are aromatic diisocyanates, particularly preferred are TDI and
It is MDI. Blocking agents used to obtain blocked NCO urethane prepolymers include oxime compounds [acetoxime, ketoxime, such as methyl ethyl ketoxime (MEK oxime), methyl isobutyl ketoxime (MIBK oxime), etc.], lactams [ε - caprolactam, etc.], active methylene compounds [malonate diesters (diethyl malonate, etc.), acetylacetone, acetoacetate (ethyl acetoacetate, etc.), etc.], phenols (phenol, m-cresol, etc.), alcohols (methanol, ethanol, etc.) , n-butanol, etc.), hydroxyl group-containing ethers (methyl cellosolve, butyl cellosolve, etc.), hydroxyl group-containing esters (methyl lactate, amyl lactate, etc.), mercaptans (butyl mercaptan, hexyl mercaptan, etc.), acid amides (acetanilide, acrylamide, etc.) dimer acid amide, etc.), imidazoles (imidazole,
2-ethylimidazole, etc.), acid imides (succinimide, phthalic imide, etc.), and mixtures of two or more of these. Among these, oxime compounds and lactams are preferred, and particularly preferred are oxime compounds and lactams.
MEK oxime and ε-caprolactam. Blocking agents such as oxime compounds and lactams have a relatively low dissociation temperature (100 to 140°C), so they can be sufficiently cured even when the baking temperature at which chipping-resistant paint is applied is relatively low. progresses. When obtaining a urethane prepolymer, the molar ratio of isocyanate groups to hydroxyl groups is usually 1.05 to 1.0.
3.0, preferably 1.3-2.2. In addition, the NCO% of the prepolymer is usually 1 to 20%, preferably 2 to 20%.
It is 15%. Urethane prepolymers can be obtained by conventional methods. When performing the urethane prepolymer production reaction, the reaction temperature is usually 40 to 140°C, preferably 60 to 120°C. In carrying out the urethane prepolymer production reaction, known catalysts for urethane polymerization are used to promote the reaction, such as organometallic compounds such as dibutyltin dilaurate, stannous octoate, stannous octoate, triethylenediamine, triethylamine, 1,8 -diazabicyclo[5,4,0]undecene-8 such as 7
It is also possible to use grade amine compounds. The blocking agent can be added at any stage of the above reaction and reacted to obtain a blocked urethane prepolymer. Possible methods of addition include adding at the end of a predetermined polymerization, adding at the beginning of the polymerization, or adding a portion at the beginning of the polymerization and adding the remainder at the end of the polymerization.
Preferably, it is added at the end of polymerization. When added at the end of polymerization, the amount added is usually 1 equivalent or more and less than 2 equivalents, preferably 1.05 equivalents or more, based on the free isocyanate group of the NCO prepolymer.
It is 1.5 equivalents. When adding a blocking agent during the process, it is preferable to use an amount approximately equivalent to the NCO equivalent of the raw polyisocyanate minus the equivalent of the polyol. If blocking takes a long time with just one type of blocking agent, add the blocking agent in two stages, for example, add a blocking agent that blocks relatively slowly (such as lactams) at the end of polymerization. However, after most of the blocking has been carried out, a blocking agent that blocks more rapidly (for example, ketoxime) can be added to efficiently complete the blocking. In the present invention, the latent NCO:active hydrogen ratio of the blocked NCO urethane prepolymer and the curing agent (oxyalkylene ether of polyalkylene polyamine having 5 or more active hydrogen atoms) is usually 1:0.05 to 3 in equivalent ratio, preferably 1:0.5~2
It is. If the active hydrogen ratio is less than 0.05 or greater than 3, curing will be insufficient and chipping resistance will be insufficient. Catalysts (usually used to promote the dissociation of blocked urethane prepolymers) are used to promote the reaction between the prepolymer and the curing agent during heating, thereby lowering the heat treatment temperature or shortening the time during coating application. It is also possible to use organic metal compounds such as zinc octylate and tin octylate, tertiary amine compounds such as triethylenediamine and triethylamine, etc.). The composition of the present invention may also contain cellulose derivatives, petroleum resins, phenolic resins, ketone resins,
Synthetic rubber, unsaturated polyester resin, epoxy resin, melamine resin, urea resin, rosin resin and other natural or synthetic resins, leveling agents, anti-sagging agents, antifoaming agents, surfactants, curing accelerators, anti-cissing agents, Various auxiliary agents such as pigment dispersants and antistatic agents can be used. An example of the formulation of the composition of the present invention is as follows. (Percentages are by weight of the composition.)

[Table] The composition of the present invention can be produced by a known method. For example, the above components may be mixed into a paint using a conventional mixing device (disper, three-roll mill, ball mill, steel mill, pepple mill, attritor, sand mill, sand grinder, row mill, pot mill, high-speed stirrer with blades, etc.). It is obtained by The composition of the present invention can be applied directly to an untreated iron plate surface or a chemically treated iron plate surface, directly to a galvanized iron plate surface, or an electrostatically coated surface such as an anionic electrodeposition coated surface or a cationic electrodeposition coated surface. Painted by any method on electrocoated surfaces. Coating can be performed using an air spray coating machine, an airless spray coating machine, a hot air spray coating machine, or the like. It is preferable to use an airless spray coating machine because it usually takes time to obtain the required film thickness using an air spray coating machine. However, it may be preferable to use an air spray coating machine for soft chipping resistant applications where the film thickness is relatively thin. In the case of an airless spray paint machine, depending on the stroke speed, it is usually possible to obtain the required film thickness in one or two strokes. Brush application, roller application, spatula application, etc. can be used for repairing or applying to complex areas. The baking temperature of the composition of the present invention is usually 90°C or higher, preferably 100 to 170°C, particularly preferably 110 to 150°C.
It is ℃. The baking time is usually within 120 minutes, preferably 10 to 60 minutes. The dry film thickness formed by the composition of the present invention is usually 15-500μ, preferably 30-400μ. If the film thickness is less than 15μ, the chipping resistance is insufficient.
On the other hand, if the thickness exceeds 500μ, problems such as wrinkles and sagging are likely to occur, and the effect of improving chipping resistance due to an increase in film thickness is not so large, resulting in a decrease in economic efficiency. An intermediate coat is usually applied on top of the film formed by the composition of the present invention, and a top coat is further applied. In some cases, the intermediate paint may be omitted. The intermediate coating can be applied wet-on-wet even when the composition of the present invention is not dried, or it can be applied even after it has hardened and dried (dry-on-wet). method). The intermediate coat can be used to improve the gloss of the top coat and the smoothness of the coated film surface, and epoxy resin paints, melamine alkyd resin paints, etc. are usually used. Examples of the coating method include a spray paint method and an electrostatic coating method. Furthermore, the top coat can be used for aesthetic purposes, and typically includes melamine alkyd resin paint, thermosetting acrylic resin paint, etc., and is applied in the same manner as the intermediate coat. After a conventional intermediate coating is applied wet-on-wet as described above, it can be cured and dried at a conventional baking temperature of about 110 DEG to 170 DEG C. without any preliminary drying. The composition of the present invention can be used in any process, such as on a cured film of a base coat, a cured intermediate coat, or a cured topcoat. Furthermore, the composition of the present invention can be painted and baked to form a coating film, or can be further coated with a conventional intermediate coating, top coating, etc. and baked to form a coating. Alternatively, it is also possible to further apply a normal intermediate coat, top coat, etc., and bake it to form a coating film. [Example] The present invention will be explained below with reference to Examples, but the present invention is not limited thereto. Parts in Examples indicate parts by weight. Example 1 Polytetramethylene glycol (MW1000) 1
mole, trimethylolpropane 0.5 mole, 1,4
-React 500 parts of a mixture of 0.5 mol of butanediol and 4.8 mol of TDI with 500 parts of toluene at 75°C for 10 hours in a four-necked flask equipped with a stirrer, thermometer, inert gas introduction tube, and cooling tube. Let, NCO%
A 5.25% urethane prepolymer solution was obtained. To 800 parts of this urethane prepolymer solution, 120 parts of ε-caprolactam and 80 parts of xylene were added, and 90 parts of
C. for 1 hour to obtain a blocked NCO urethane prepolymer solution. A chipping-resistant paint composition was prepared using this blocked NCO urethane prepolymer solution at the following blending ratio. Blocked NCO urethane prepolymer solution 100 parts PO adduct of diethylenetriamine (MW450)
10 parts calcium carbonate 80 parts titanium white 8 parts carbon black 2 parts aromatic petroleum naphtha (boiling range 100-200℃)
100 parts Next, the above-mentioned chipping-resistant paint composition was applied to a steel plate on which a rust-proofing undercoat film was formed by electrodepositing an epoxy-based cationic electrodeposition paint and baking hardening it to a film thickness of 250 μm after drying with an airless paint machine. Paint it so that it looks like
Bake hardening was performed at 130°C for 30 minutes. Example 2 The same procedure as in Example 1 was carried out except that polytetramethylene glycol (MW1000) in Example 1 was replaced with polycaprolactone polyol (MW1000), and a blocked urethane prepolymer solution and a chipping-resistant paint composition were obtained. . This chipping-resistant paint was cured by baking in the same manner as in Example 1. Example 3 The procedure of Example 1 was repeated except that polytetramethylene glycol in Example 1 was replaced with glycerin PO adduct (MW1000) and trimethylolpropane was replaced with neopentyl glycol, and a blocked urethane prepolymer solution and A chipping-resistant paint composition was obtained. This chipping-resistant coating composition was baked and cured in the same manner as in Example 1. Comparative Example 1 A chipping-resistant paint composition was obtained in the same manner as in Example 1, except that 10 parts of ethylenediamine PO adduct (Mw 300) was used in place of the diethylenetriamine PO adduct (Mw 450) in Example 1. . This chipping-resistant coating composition was baked and cured under the same conditions as in Example 1. Test Example 1 Table 1 shows the evaluation results of the adhesion and chipping resistance of the baked coatings of the chipping-resistant paint compositions obtained in Examples 1 to 3 and Comparative Example 1. Paint film test method Adhesion (burlap test) A chipping-resistant paint composition was coated and baked on a 100 x 100 x 0.8 mm electrodeposition coated plate with a thickness of 250μ (after drying) at 2 mm intervals vertically and horizontally. Ten cuts were inserted into each sample with a knife until they reached the metal surface, and after storage under specified conditions, cellophane tape was applied to the cut portion and then peeled off.The presence or absence of peeling of the coating film was examined and expressed as a percentage of 100. For hot water deterioration, the test was conducted after 14 days of immersion in 50°C hot water. Chipping resistance test A sample of a 100 x 100 x 0.8 mm electrodeposited plate coated with a chipping resistant paint composition at a thickness of 250μ (after drying) and baked was tested with a type 3 M-4 shaped iron hexagon as specified in JIS B-1181. A nut is dropped from a height of 2 m through a tube with a diameter of 20 mm onto each sample plate at an angle of 45° with respect to the direction in which the nut falls. are shown in Table-1.

[Table] [Effects of the Invention] The chipping-resistant coating composition of the present invention has superior adhesion to the underlying electrodeposition coating and chipping resistance compared to conventional binders. Therefore, excellent chipping resistance can be expected with a relatively thin film, and when applied to vehicles, etc., it exhibits excellent rust prevention, reduces the weight of the coating, and is economical. Because of the above effects, the chipping-resistant paint of the present invention is particularly useful as a rust-preventing paint for automobiles and the like.

Claims (1)

[Scope of Claims] 1. A chipping-resistant coating composition characterized by containing a blocked NCO urethane prepolymer and an oxyalkylene ether of a polyalkylene polyamine having 5 or more active hydrogen atoms. 2. The composition according to claim 1, wherein the blocked NCO urethane prepolymer is an NCO urethane prepolymer blocked with an oxime compound and/or a lactam. 3. Claim 1, wherein the blocked NCO urethane prepolymer is an NCO urethane prepolymer made of a polyol having an average functional group number of 2.01 or more, which is composed of a high molecular polyol and optionally a low molecular polyol, and an organic polyisocyanate compound. The composition according to item 1 or 2. 4. The composition according to claim 3, wherein the organic polyisocyanate is an aromatic diisocyanate. 5 The polyol has a molecular weight per hydroxyl group of 250~
2500 difunctional hydroxyl group-containing polymeric polyol, low molecular weight triol with a molecular weight per hydroxyl group of 30 to 150, and optionally a molecular weight per hydroxyl group of 30 to 200.
The composition according to claim 3 or 4, which is a polyol consisting of a low molecular weight diol. 6 The polyol has a molecular weight per hydroxyl group of 180~
Claim 3: A polyol consisting of a trifunctional hydroxyl group-containing polymer polyol of 1800, a low-molecular diol with a molecular weight per hydroxyl group of 30 to 200, and optionally a low-molecular triol with a molecular weight per hydroxyl group of 30 to 150. Or the composition according to item 4.