JPH1060073A - Aqueous polyisocyanate and aqueous coating material composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an aqueous polyisocyanate capable of giving an aqueous ambient temperature corsslinking type urethane resin coating material composition and useful for an exterior coating material in a construction by using a specific precursor prepolymer having a high average number of isocyanate functional groups. SOLUTION: This aqueous polyisocynate capable of dissolving or dispersing with water, not containing an ionic group in molecule thereof and having (2/98)-(40/60) molar ratio of a polyether chain/isocyanate group (NCO), 3.5-9.8 average number of isocyanate functional groups (F1 ), 1100-10000 number average molecular weight and 2-19wt.% isocyanate concentration (F2 ), is obtained by reacting (A) an isocyanulate type polyisocyanate having 4.5-10 (F1 ), 5-100Pa.s viscosity at 25 deg.C and 2-20% (F2 ) and obtained by reacting an aliphatic or an alicyclic diisocyanate with a polyhydric alcohol and performing a cyclic trimerization of NCO, with (B) a polyether having an ethyleneoxide unit having an active hydrogen in one of the terminals thereof.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aqueous polyisocyanate obtained from an aliphatic or alicyclic diisocyanate and an aqueous coating composition using the same.

[0002]

2. Description of the Related Art A two-pack type polyurethane resin coating composition has excellent abrasion resistance, chemical resistance, stain resistance, and room temperature curability, and further has an aliphatic diisocyanate, particularly hexamethylene diisocyanate. Polyurethane resin coating compositions containing non-yellowing polyisocyanates derived from alicyclic diisocyanates, in particular isophorone diisocyanate, are more excellent in weather resistance and the demand thereof tends to increase.

[0003] On the other hand, in view of environmental conservation, development of aqueous cold-crosslinkable paints has been active, and there have been many proposals using polyisocyanate as a curing agent. In JP-A-62-41270 and JP-A-2-105879, a hydrophobic polyisocyanate is dispersed in water by utilizing the water-soluble ability of an aqueous polyol as a main ingredient to form an aqueous paint. Further, in order to improve the water dispersibility of the polyisocyanate, Japanese Patent Application Laid-Open No.
In Japanese Patent Application Laid-Open No. 211418, a polyisocyanate having a carboxyl group incorporated in a molecule is disclosed in
No. 50 proposes to incorporate polyethylene glycol, which is a nonionic hydrophilic group, into a polyisocyanate. The average number of isocyanate functional groups in the polyisocyanate used in these is about 3 as in the case of the solvent-based two-pack urethane.

[0004] In an aqueous coating composition using a polyisocyanate as a curing agent, the reaction between water in the medium and isocyanate groups cannot be avoided. Therefore, in the example of JP-A-5-222150, the equivalent ratio of the isocyanate group of the polyisocyanate to the hydroxyl group of the base polyol is set to 1.5: 1, and the excess of the polyisocyanate is used to react with water as a medium. It is compounded in consideration of isocyanate groups to be consumed. However, even if the polyisocyanate is excessively blended and the amount of isocyanate involved in crosslinking is ensured, there have been cases where physical properties cannot be prevented from decreasing due to a decrease in the average number of isocyanate functional groups.

In addition, the average isocyanate functionality is consumed by the polyethylene glycol incorporated to improve the water dispersibility of the polyisocyanate. The physical properties of a coating film obtained from such a polyisocyanate having a low average number of isocyanate functional groups were inferior to those of a conventional organic solvent-based two-liquid urethane resin coating material.

[0006]

DISCLOSURE OF THE INVENTION The present invention relates to an aqueous cold crosslinking urethane resin coating composition capable of obtaining excellent coating film properties from an organic solvent-based cold crosslinking urethane resin coating, and an aqueous solution used for the same. It is intended to provide a polyisocyanate.

[0007]

As a result of intensive studies, the present inventors have found that the above-mentioned problems can be solved by using a specific polyisocyanate having a high average number of isocyanate functional groups, and have completed the present invention. Was. That is, the present invention is as follows. 1. A precursor polyisocyanate A shown in the following (1):
An aqueous polyisocyanate which is a reaction product with a polyether having an ethylene oxide unit having an active hydrogen at one end and which can be dissolved or dispersed in water,
(E) an aqueous polyisocyanate, (1) An average isocyanate function obtained by reacting at least one kind of aliphatic and / or alicyclic diisocyanate with a polyhydric alcohol after or simultaneously with the reaction of the precursor polyisocyanate A with cyclic trimerization of isocyanate groups. Number of groups: 4.5 to 10, viscosity at 25 ° C .; 5,000 to 100,000 mPa · s, isocyanate concentration: 2 to 20% by weight (both in a state substantially free of diisocyanate and solvent) It is an isocyanurate type polyisocyanate. (A) No ionic group in the molecule (b) Polyether chain unit / isocyanate group = 2/9
(C) average number of isocyanate functional groups; 3.5 to 9.8 (d) number average molecular weight; 1,100 to 10,000 (e) isocyanate concentration; 2 to 19% by weight 2. 2. The aqueous polyisocyanate according to the above 1, wherein the polyhydric alcohol is a tri- to di-valent polyester and / or polyether. 3. At least 10 to 200 mg KOH /
An aqueous coating composition comprising g of the polyvalent hydroxyl group-containing compound and the aqueous polyisocyanate of the above 1 or 2.

Hereinafter, the present invention will be described in detail. The diisocyanates used in the present invention are aliphatic and / or cycloaliphatic diisocyanates. As the aliphatic diisocyanate, one having 4 to 30 carbon atoms is preferable, and as the alicyclic diisocyanate, one having 8 to 30 carbon atoms is preferable. For example, 1,4-tetramethylene diisocyanate, 1,5
-Pentamethylene diisocyanate, 1,6-hexamethylene diisocyanate, 2,2,4-trimethyl-
1,6-hexamethylene diisocyanate, lysine diisocyanate, 3-isocyanatomethyl-3,3,5
-Trimethylcyclohexyl isocyanate (isophorone diisocyanate), 1,3-bis (isocyanatomethyl) -cyclohexane, 4,4'-dicyclohexylmethane diisocyanate, and the like. Among them, 1,6-hexamethylene diisocyanate (hereinafter, referred to as HMDI) and isophorone diisocyanate (hereinafter, referred to as IPDI) are preferable from the viewpoint of weather resistance and industrial availability, and they can be used alone or in combination. May be.

[0009] The polyhydric alcohol used in the present invention is preferably a trihydric or higher alcohol, more preferably a trihydric to 20-valent, and particularly preferably a trihydric to 10-hydric. The polyhydric alcohol includes a low molecular weight polyhydric alcohol and a high molecular weight polyhydric alcohol.

[0010] Examples of low molecular weight polyhydric alcohols include trimethylolpropane, glycerin, pentaerythritol and the like. As high molecular weight polyhydric alcohols, aliphatic hydrocarbon polyols, polyether polyols, polyester polyols, epoxy resins,
Examples include fluorine polyols and acrylic polyols.

Specific examples of the aliphatic hydrocarbon polyols include, for example, terminal hydroxylated polybutadiene and hydrogenated products thereof. Examples of the polyether polyols include, for example, polyether polyols and polyether polyols obtained by adding an alkylene oxide alone or a mixture thereof to a polyhydric alcohol such as glycerin or propylene glycol alone or a mixture thereof. Tetramethylene glycols,
Further, polyether polyols obtained by reacting a polyfunctional compound such as ethylenediamine and ethanolamines with alkylene oxide, and obtained by polymerizing acrylamide or the like using these polyethers as a medium,
So-called polymer polyols and the like are included.

Examples of the polyester polyols include succinic acid, adipic acid, sebacic acid, dimer acid,
Maleic anhydride, phthalic anhydride, isophthalic acid, terephthalic acid and other dicarboxylic acids selected from the group of carboxylic acids alone or in combination with ethylene glycol, propylene glycol, diethylene glycol, neopentyl glycol, trimethylolpropane, glycerin, etc. Polyester polyol resins obtained by a condensation reaction with a polyhydric alcohol selected from the group alone or with a mixture, and, for example, polycaprolactone obtained by ring-opening polymerization of ε-caprolactone using a polyhydric alcohol And the like.

Examples of the epoxy resin include novolak type, β-methyl epichloro type, cyclic oxirane type, glycidyl ether type, glycol ether type, epoxy type of aliphatic unsaturated compound, epoxidized fatty acid ester type, and polyvalent carboxylic acid. Ester type, aminoglycidyl type,
Epoxy resins such as halogenated type and resorcinol type are exemplified.

Examples of the acrylic polyol include acrylates having an active hydrogen such as 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, and 2-hydroxybutyl acrylate, and glycerol monoacrylate. Monoester or methacrylic acid monoester, trimethylolpropane acrylic acid monoester or methacrylic acid monoester alone or in mixture with methyl acrylate, ethyl acrylate, isopropyl acrylate, acrylic acid-n
Acrylates such as -butyl, 2-ethylhexyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 2-hydroxybutyl methacrylate, 3-hydroxypropyl methacrylate, methacrylic acid- Methacrylates having active hydrogen such as 4-hydroxybutyl, or methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-hexyl methacrylate, lauryl methacrylate, etc. And a mixture selected from the group consisting of methacrylic acid esters as an essential component, and unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid, and itaconic acid, acrylamide, N-methylolacrylamide, and diacetone acrylic acid. In the presence or absence of unsaturated amides such as amides, and glycidyl methacrylate, styrene, vinyltoluene, vinyl acetate, acrylonitrile, and other polymerizable monomers such as dibutyl fumarate, alone or in combination. And an acrylic polyol resin obtained by polymerization.

Preferred among these polyhydric alcohols are the above-mentioned polyester polyols and polyether polyols, more preferred are polycaprolactone-based polyester polyols and polypropylene-based polyether polyols, and particularly preferred are those having a number average molecular weight of 200 to 200.
2000 polycaprolactone-based polyester polyol and polypropylene-based polyether polyol.
These may be used alone or in combination of two or more.

When the diisocyanate is reacted with the polyhydric alcohol, the equivalent ratio of the isocyanate group of the diisocyanate to the hydroxyl group of the polyhydric alcohol is preferably 2/1 to 30/1. If it is less than 2/1, the viscosity of the reaction solution after the reaction increases, and if it exceeds 30/1, the amount of unreacted diisocyanate recovered is large, and the productivity may decrease. Preferably it is 5/1 to 20/1.

In the reaction, the diisocyanate and the polyhydric alcohol may be charged into the reactor at the same time, or only the diisocyanate may be charged first, and after reaching a predetermined temperature, the polyhydric alcohol may be added all at once or dividedly. At the same time as or after the reaction between the diisocyanate and the polyhydric alcohol, an isocyanuration reaction is performed.

A catalyst is usually used for the isocyanuration reaction. The catalyst used here is generally preferably basic, for example, tetramethylammonium, tetraalkylammonium hydroxide such as tetraethylammonium, and, for example, acetic acid,
Organic weak acid salts such as capric acid, for example, hydroxyalkylammonium hydroxides such as trimethylhydroxypropylammonium, trimethylhydroxyethylammonium, triethylhydroxypropylammonium and triethylhydroxyethylammonium, and organic weak acid salts such as acetic acid and capric acid Alkyl carboxylic acids such as acetic acid, caproic acid, octylic acid, and myristic acid, for example, alkali metal salts such as tin, zinc, and lead; metal alcoholates such as sodium and potassium; and aminosilyl groups such as hexamethyldisilazane Compounds, Mannich bases, tertiary amines in combination with epoxy compounds, for example, phosphorus compounds such as tributylphosphine and the like.

The catalyst concentration is usually 10 ppm to 10% based on all isocyanate compounds including unreacted diisocyanate.
It is selected from a range of 1.0%. The reaction may or may not use a solvent. When a solvent is used, it is preferable to use a solvent inert to isocyanate groups.
The reaction temperature is generally 20 to 160 ° C, preferably 40 to 1 ° C.
30 ° C. The reaction end point varies depending on the polyhydric alcohol used, but the yield is generally about 20% by weight or more and 70% by weight or less.

When the reaction reaches the target yield, the catalyst is deactivated by, for example, sulfonic acid, phosphoric acid, phosphate ester or the like, and the reaction is stopped. By removing the unreacted diisocyanate and the solvent, an isocyanurate-type polyisocyanate having an isocyanurate structure (precursor polyisocyanate A) used in the present invention can be obtained.

The average number of isocyanate functional groups in the polyisocyanate is the number of isocyanate functional groups statistically possessed by one molecule of the polyisocyanate, and can be calculated from the number average molecular weight of the polyisocyanate and the isocyanate concentration by the following general formula (1). Average number of isocyanate functional groups = [(number average molecular weight of polyisocyanate) × (isocyanate concentration)] / [formula weight of isocyanate group (42)] (1) The average isocyanate functional group number of the polyisocyanate is 4.5 to 4.5. 10, preferably 5-8. If the number of functional groups is less than 4.5, a good coating film cannot be obtained. On the other hand, if the number of functional groups exceeds 10, the mechanical properties of the coating film are inferior.

The polyisocyanate has a viscosity at 25 ° C. of 5,000 to 100,000 mPa · s and an isocyanate concentration of 2 to 20% by weight. By adding a polyether compound having an active hydrogen at one end and an ethylene oxide chain (hereinafter referred to as an ethylene oxide adduct) to the precursor polyisocyanate A thus obtained, the present invention Is obtained.

The ethylene oxide adduct is obtained by adding ethylene oxide to a monoalcohol such as methanol, ethanol or butanol. The ethylene oxide content is preferably 50% by weight or more, and the number average molecular weight is 200 to 1, 000. The ethylene oxide adduct may include propylene oxide. The mole number of the ethylene oxide adduct added to the isocyanate group of the precursor polyisocyanate A and the mole number of the isocyanate group after addition of the ethylene oxide adduct (polyether chain unit / isocyanate group) are from 2/98 to 40/6.
0, preferably 2/98 to 30/70.
If it is less than 2/98, the water dispersibility of the polyisocyanate will be low, and if it exceeds 40/60, the physical properties of the coating film will be low.

The reaction between the ethylene oxide adduct and the polyisocyanate can be carried out using a solvent. The solvent used in this case must be inert to the isocyanate. The reaction temperature is 40 to 150C, preferably 60 to 120C. If necessary, a basic compound such as a tin compound such as dibutyltin dilaurate may be used as the reaction catalyst.

The resulting aqueous polyisocyanate may be mixed with a polyisocyanate to which the ethylene oxide adduct has not been added. In this case, the above polyether chain unit / total isocyanate after mixing /
The isocyanate group is preferably from 2/98 to 40/60.
The aqueous polyisocyanate of the present invention thus obtained is
(A) no ionic group in the molecule, (b) polyether chain unit / isocyanate group = 2 / 98-40 / 60
(Mol / mol), (c) average number of isocyanate functional groups;
3.5-9.8, (d) number average molecular weight; 1,100-1
0000, (e) isocyanate concentration; 2 to 19% by weight.

Further, an anionic or cationic surfactant can be added according to the purpose. Specific examples of the surfactant include anionic surfactants such as fatty acid salts, alkyl sulfates, alkylbenzene sulfonates, and alkyl phosphates, and cationic surfactants such as alkylamine salts and alkyl betaines. The aqueous polyisocyanate of the present invention thus obtained constitutes a main component of the aqueous paint together with the compound containing a polyvalent hydroxyl group.

The polyhydric hydroxyl group-containing compound used in the aqueous coating composition of the present invention can be used without any particular limitation as long as it is generally used for aqueous coatings. Anionic, cationic and amphoteric compounds can be used. It may be an ionic type or a non-ionic type. Examples thereof include alkyd-based, polyester-based, epoxy-based, fluorine-based, and acrylic-based ones, which are dissolved or dispersed in a medium containing water as a main component, and include a soluble polyol and a dispersed polyol.

As the soluble polyol, Japanese Patent Application Laid-Open No.
-295680, JP-A-63-175059, JP-A-62-216671, JP-A-2-19
For example, a manufacturing method thereof is disclosed in, for example, US Pat. Dispersion type polyols are disclosed in JP-A-56-157358.
The production method is disclosed in, for example, Japanese Patent Application Publication No. Examples of the fluorine polyol which is a fluorine-containing copolymer having a hydroxyl group include JP-A-57-34107 and JP-A-61-34107.
JP-A-231044 and JP-A-3-37252 disclose the manufacturing method. Examples of the acrylic resin include JP-A-63-295680 and JP-A-63-1.
75059, JP-A-56-157358 and the like.

The hydroxyl value of the resin of the polyvalent hydroxyl group-containing compound is at least 10 to 200 mgKOH / g. When the hydroxyl value of the resin is less than 10 mgKOH / g, the density of urethane crosslinks due to the reaction with the isocyanate component decreases. When the resin hydroxyl value exceeds 200 mgKOH / g, the crosslink density increases and the mechanical properties of the coating film decrease, which is not preferable.

In the aqueous coating composition of the present invention, the equivalent ratio of the isocyanate group of the aqueous polyisocyanate to the hydroxyl group of the polyvalent hydroxyl group-containing compound is usually set to 10: 1 to 1:10. If necessary, an antioxidant, an ultraviolet absorber, a pigment, a metal powder pigment such as aluminum, a cross-linking accelerator such as an organometallic compound such as dibutyltin dilaurate, a leveling agent, and a solvent may be added.

Usually, a compound containing a polyvalent hydroxyl group, a curing agent,
An aqueous paint is obtained by mixing additives and the like, adding a medium containing water as a main component, and adjusting the paint viscosity according to the coating method. The water-based paint adjusted in this way is spray coating,
Roll coating, shower coating, dip coating etc.
It is applied to plastics, building materials, etc., and is also useful as a top coat, undercoat, as an architectural exterior paint, a paint for plastic parts such as bumpers, a paint for automobile repair, a paint for organic coating such as pre-coated metal, and the like.

The aqueous polyisocyanate of the present invention is useful as an ink, an adhesive, an inorganic material such as fibers, films and ceramics, a modifier for paper, wood and resin, or a surface treating agent, in addition to a coating material.

[0033]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the following Examples. In addition, all% were shown by weight%. The evaluation was performed as follows. (1) Measurement of Number Average Molecular Weight The number average molecular weight is a number average molecular weight based on polystyrene by gel permeation chromatography using the following apparatus. [Apparatus] Tosoh Corporation HLC-802A [Column] Tosoh Corporation G1000HXL x 1, G2
000HXL × 1, G3000HXL × 1 [Carrier] tetrahydrofuran [Detection method] Differential refractometer (2) Viscosity measurement The viscosity was measured at 25 ° C. using an Emira type rotational viscometer. (3) Gel fraction The value of the weight of the undissolved portion when the cured coating film was immersed in acetone at 20 ° C. for 24 hours with respect to the weight before immersion was calculated, and was 85
% Is represented by x, and 85% or more is represented by ○. (4) Evaluation of water dispersibility of polyisocyanate Polyisocyanate and pure water were mixed at a weight ratio of 2:10,
The subsequent solution state was visually observed. A state in which the mixture was uniform and free of sediment was evaluated as “good”.

[0034]

[Production Example 1] (Production of polyisocyanate) A four-necked flask equipped with a stirrer, a thermometer, a reflux condenser, a nitrogen blowing pipe, and a dropping funnel was set to a nitrogen atmosphere.
600 parts of HMDI, polycaprolactone-based polyester polyol which is a trihydric alcohol “Placel 30
3 "(trade name of Daicel Chemical Co., molecular weight: 300) was charged, and the temperature in the reactor was kept at 90 ° C. for 1 hour with stirring to carry out a urethanization reaction. Thereafter, the temperature in the reactor was maintained at 60 ° C., tetramethylammonium capryate was added as a catalyst for isocyanuration, and when the yield reached 48%, the reaction was stopped by adding phosphoric acid. After filtering the reaction solution, unreacted HMDI was removed using a thin film evaporator.

The viscosity of the obtained polyisocyanate at 25 ° C. was 9,500 mPa · s, the isocyanate concentration was 19.2%, the number average molecular weight was 1,100, and the average number of isocyanate functional groups was 5.1.

[0036]

Production Examples 2 and 3 (Production of polyisocyanate) The production was carried out in the same manner as in Production Example 1, except that the reaction conditions shown in Table 1 were used. Table 1 shows the physical properties of the obtained polyisocyanate.

[0037]

Comparative Production Example 1 The same procedure as in Production Example 1 was carried out except that the reaction conditions shown in Table 1 were used. Table 1 shows the physical properties of the obtained product.

[0038]

Example 1 (Production of aqueous polyisocyanate) A four-necked flask equipped with a stirrer, a thermometer, a reflux condenser, a nitrogen blower, and a dropping funnel was set to a nitrogen atmosphere.
100 parts of the polyisocyanate obtained in Production Example 1 and 19 parts of methoxypolyethylene glycol having a molecular weight of 400 (trade name of "UNIOX M400" of Nippon Oil & Fats Co., Ltd.) (reacting with 10% of all isocyanate groups of the polyisocyanate) were charged. It was kept at 80 ° C. for 7 hours. Table 2 shows the evaluation of the physical properties and water dispersibility of the obtained aqueous polyisocyanate.

[0039]

Examples 2 to 5 (Production of aqueous polyisocyanate) The same procedures as in Example 1 were carried out except as described in Table 2. Table 2 shows the results.

[0040]

Comparative Example 1 The procedure of Example 1 was repeated, except that the polyisocyanate obtained in Comparative Production Example 1 was used and the conditions shown in Table 2 were used. Table 2 shows the results.

[0041]

Examples 6 to 10 (Preparation of aqueous coating composition) A water-soluble acrylic polyol neutralized with dimethylethanolamine (trade name: Arolon 76, Nippon Shokubai Co., Ltd., resin hydroxyl value: 64 mgKOH / g) The aqueous polyisocyanate obtained in any one of (1) to (5) is
It mixed so that the equivalent ratio of a hydroxyl group might be 1/1. Further, water was added, and the viscosity of the paint was changed to Ford Cup No. 4 was adjusted to 30 seconds. This paint was applied to an applicator and cured at 80 ° C. for 1 hour. Table 3 shows the coating film evaluation results.
Shown in

[0042]

Comparative Example 2 The same procedure as in Example 6 was carried out except that the aqueous polyisocyanate obtained in Comparative Example 1 was used. Table 3 shows the results
Shown in

[0043]

[Table 1]

[0044]

[Table 2]

[0045]

[Table 3]

[0046]

The aqueous coating composition using the aqueous polyisocyanate of the present invention has good curability, excellent coating properties, and is useful as an aqueous cold crosslinking coating.

──────────────────────────────────────────────────続 き Continuation of the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location C09D 175/04 PHV C09D 175/04 PHV

Claims (3)

[Claims] An aqueous polyisocyanate which is a reaction product of a precursor polyisocyanate A shown in the following (1) and a polyether having an ethylene oxide unit having an active hydrogen at one terminal and which can be dissolved or dispersed in water. Aqueous polyisocyanates characterized by the following (a) to (e): (1) An average isocyanate function obtained by reacting at least one kind of aliphatic and / or alicyclic diisocyanate with a polyhydric alcohol after or simultaneously with the reaction of the precursor polyisocyanate A with cyclic trimerization of isocyanate groups. Number of groups: 4.5 to 10, viscosity at 25 ° C .; 5,000 to 100,000 mPa · s, isocyanate concentration: 2 to 20% by weight (both in a state substantially free of diisocyanate and solvent) It is an isocyanurate type polyisocyanate. (A) No ionic group in the molecule (b) Polyether chain unit / isocyanate group = 2/9
8 to 40/60 (mol / mol) (c) Average number of isocyanate functional groups; 3.5 to 9.8 (d) Number average molecular weight; 1,100 to 10,000 (e) Isocyanate concentration; 2 to 19% by weight 2. The aqueous polyisocyanate according to claim 1, wherein the polyhydric alcohol is a tri- to di-valent polyester and / or polyether. 3. A resin hydroxyl group of at least 10 to 200 m.
An aqueous coating composition comprising gKOH / g of a polyhydric hydroxyl group-containing compound and the aqueous polyisocyanate according to claim 1 or 2.