WO2021022534A1

WO2021022534A1 - Aqueous polymer dispersion

Info

Publication number: WO2021022534A1
Application number: PCT/CN2019/099717
Authority: WO
Inventors: Xinke Wang; Bin HAO; Xiaohui JIA; Qian Hu; Lingyun Huang
Original assignee: Wacker Chemie Ag
Priority date: 2019-08-08
Filing date: 2019-08-08
Publication date: 2021-02-11

Abstract

Provided is an aqueous dispersion based on ethylene-vinyl ester copolymers. The aqueous polymer dispersion features good long term storage stability, and weakens water mark phenomenon on the coating film when it is used in waterborne architectural coatings. Especially on the film formed from waterborne emulsion paints in the presence of moisture, the dispersion enables reduced number, color and gloss of water marks.

Description

An Aqueous Polymer Dispersion

Field of the Invention

The present invention relates to the technical field of architectural coatings, in particular, for interior walls coatings.

Background of the Invention

US7189461 discloses an ethylene-vinyl acetate copolymer emulsion comprising a nonionic surfactant (particularly nonyl phenol ethoxylate) , an anionic surfactant (particularly sodium lauryl sulfate) and hydroxyethyl cellulose, wherein ethylene is present in an amount of 150 wt%, based on the total weight, as 100 wt%, of vinyl ester monomer. The copolymer emulsion is suited for use in heat seal applications.

US3692723 discloses an ethylene-vinyl acetate copolymer dispersion comprising a nonionic surfactant (particularly nonyl phenol ethoxylate) , an anionic surfactant and monomethyl cellulose, wherein ethylene is present in embodiments therein in an amount of more than 42 wt%, mostly more than 400 wt%, based on the total weight, as 100 wt%, of vinyl ester monomer. The copolymer dispersion is suited for use in heat seal applications.

US6863985 discloses an ethylene-vinyl acetate copolymer dispersion comprising a nonionic surfactant, an anionic surfactant and polyvinyl alcohol (PVOH) , which is suitable for use in coatings with high wet-abrasion resistance and for the strengthening of fibers.

WO2018148929 discloses an ethylene-vinyl acetate copolymer dispersion comprising hydroxyethyl cellulose and PVOH 2588 as protective colloids, as well as a nonionic surfactant and an anionic surfactant, which is suited for interfacial bonding between textile or non-woven materials and substrates.

Summary of the Invention

The present invention discloses an aqueous dispersion based on ethylene-vinyl ester copolymers. The aqueous polymer dispersion features good long term storage stability and weakens water mark phenomenon on the coating film when it is used in waterborne architectural coatings. Especially on the film formed from waterborne emulsion paints which containing the aqueous polymer in the presence of moisture, the number, color and gloss of water marks are reduced.

An aqueous polymer dispersion comprising

Component (a) –one or more kind (s) of ethylene-vinyl ester copolymer (s) ,

Component (b) –one or more kind (s) of protective colloid (s) ,

Component (c) –one or more kind (s) of nonionic surfactant (s) , and

Component (d) –one or more kind (s) of anionic surfactant (s) ,

wherein Component (b) , a protective colloid, is present in an amount of less than or equal to 1.5 wt%, preferably 0.5-1.2 wt%, more preferably 0.7-1.1 wt%, based on the total weight, as 100 wt%, of vinyl ester monomer, and

ethylene monomer is present in Component (a) , an ethylene-vinyl ester copolymer, in an amount of less than or equal to 40 wt%, preferably 5-35 wt%, more preferably 10-30 wt%, even more preferably 18-25 wt%, most preferably 18-22 wt%, based on the total weight, as 100 wt%, of vinyl ester monomer.

The vinyl esters typically include vinyl esters of linear or branched alkyl carboxylic acids having 1 to 15 carbon atoms, such as vinyl acetate, vinyl propionate, vinyl butyrate, vinyl pivalate, vinyl 2-ethylhexanoate, vinyl laurate, or any combination thereof.

In order to extend the properties of Component (a) ethylene-vinyl ester copolymer (s) , in addition to the vinyl ester and ethylene monomers, there can be also included other comonomers, for example, halogenated ethylenes, such as vinyl chloride; olefins such as propylene; ethylenically unsaturated carboxylic acids and derivatives thereof, such as fumaric acid, maleic acid, maleic anhydride, acrylamide, and acrylonitrile; precrosslinking comonomers or postcrosslinking comonomers, such as divinyl adipate, diallyl maleate, allyl methacrylate, triallyl cyanurate, acrylamidoglycolic acid, methacrylamide glycolate methyl ester, N-methylol acrylamide, N-methylol methacrylamide, N-methylolallyl carbamate, isobutoxy ethers or esters of N-methylol acrylamide, isobutoxy ethers or esters of N-methylol methacrylamide, isobutoxy ethers or esters of N-methylolallyl carbamate; epoxy-functional comonomers such as glycidyl methacrylate and glycidyl acrylate; and silicon-functional comonomers such as vinyl trialkoxysilanes, vinyl methyl dialkoxysilanes. The dosage of other comonomers is equal to or lower than 10wt%, preferably equal to or lower than 5wt%, most preferably equal to or lower than 2 wt%, based on the total weight, as 100 wt%, of vinyl ester monomer.

According to the aqueous dispersion mentioned above, the vinyl ester monomer of Component (a) , an ethylene-vinyl ester copolymer, is vinyl acetate.

According to the aqueous dispersion mentioned above, the vinyl ester monomer is present in Component (a) , an ethylene-vinyl ester copolymer, in an amount of greater than or equal to 70 wt%, preferably greater than or equal to 80 wt%, more preferably 80-90 wt%, most preferably 82-88 wt%, based on the total weight, as 100 wt%, of all monomers.

According to the aqueous dispersion mentioned above, Component (a) is an ethylene-vinyl acetate copolymer.

According to the aqueous dispersion mentioned above, Component (b) , a protective colloid, is present in an amount of less than or equal to 1.7 wt%, preferably 0.5-1.7 wt%, more preferably 0.7-1.5 wt%, based on the total weight, as 100 wt%, of all monomers.

According to the aqueous dispersion mentioned above, Component (b) , a protective colloid, is present in an amount of less than or equal to 1.5 wt%, preferably 0.5-1.2 wt%, more preferably 0.7-0.9 wt%, based on the total weight, as 100 wt%, of vinyl ester monomer.

Suitable protective colloids are one or more combination selected from the group containing polyvinyl alcohols, polysaccharides in water-soluble form, such as starches (amylose and amylopectin) , modified starches, such as starch ethers, for example hydroxyalkyl ether starches, dextrins and cyclodextrins, celluloses and carboxymethyl, methyl, hydroxyethyl and hydroxypropyl derivatives thereof, poly (meth) acrylic acid, poly (meth) acrylamide, melamine-formaldehyde sulfonates and naphthalene-formaldehyde sulfonates.

According to the aqueous dispersion mentioned above, Component (c) , a nonionic surfactant, is present in an amount of greater than or equal to 1 wt%, preferably 1.2-3 wt%, more preferably 1.4-2.5 wt%, most preferably 1.2-2 wt%, based on the total weight, as 100 wt%, of vinyl ester monomer.

According to the aqueous dispersion mentioned above, Component (c) , a nonionic surfactant, and Component (b) , a protective colloid, are used in a mass ratio of 1.0-2.5, preferably 1.0-2.0, more preferably 1.5-2.0, most preferably 1.6-1.9.

According to the aqueous dispersion mentioned above, Component (d) , an anionic surfactant, is present in an amount of 0.5-3 wt%, preferably 0.8-2.5 wt%, more preferably 1-1.8 wt%, based on the total weight, as 100 wt%, of vinyl ester monomer.

Anionic surfactants are surfactants containing a negatively charged hydrophilic polar group. Examples of anionic surfactants are ammonium lauryl sulfate, sodium laureth sulfate, sodium lauryl sarcosinate, sodium lauryl sulfate, α olefin sulfonate, and ammonium laureth sulfate.

According to the aqueous dispersion mentioned above, Component (b) , a protective colloid, is selected from cellulose ethers and/or polyvinyl alcohol (PVOH) .

According to the aqueous dispersion mentioned above, Component (b) , a protective colloid containing cellulose ether, the cellulose ether is present in an amount of greater than 50 wt%, preferably greater than or equal to 65 wt%, more preferably greater than or equal to 75 wt%, even more preferably greater than or equal to 85 wt%, most preferably 95 wt%, based on the total weight, as 100 wt%, of Component (b) , a protective colloid.

According to the aqueous dispersion mentioned above, in Component (b) , a protective colloid, a cellulose ether that preferably has a MS value (total molar substitution) of greater than or equal to 2.8 and less than or equal to 3.3.

According to the aqueous dispersion mentioned above, PVOH is present in an amount of less than 0.1 wt%, preferably less than or equal to 0.05 wt%, more preferably less than or equal to 0.01 wt%, based on the total weight, as 100 wt%, of vinyl ester monomer.

According to the aqueous dispersion mentioned above, PVOH has an average alcoholysis degree of 40-99 mol%, preferably 75-95 mol%, more preferably 85-92 mol%, and a viscosity, in 4 wt%aqueous solution, of about 5 mPa·s or about 17 mPa·s or about 25 mPa·s, measured at 20℃ according to DIN 53015, and can be exemplified by typical grades PVOH 0488, PVOH 1788 and PVOH 2588.

The cellulose ether is one, or a combination, of alkyl celluloses, hydroxyalkyl celluloses and carboxyalkyl celluloses, preferably one, or a combination, of hydroxyethyl celluloses, hydroxypropyl celluloses, carboxymethyl celluloses and monomethyl celluloses, more preferably hydroxyethyl celluloses.

hydroxyethylcellulose are one or more selected from the group containing methyl hydroxyethylcellulose, ethyl hydroxyethylcellulose, octyl hydroxyethylcellulose, cetyl hydroxyethylcellullose, cetoxy-2-hydroxypropyl hydroxyethylcellulose, butoxy-2-hydroxypropyl hydroxyethylcellulose, butoxy-2-hydroxypropyl cetyl hydroxyethylcellulose, butoxy-2-hydroxypropyl cetoxy-2-hydroxyethylcellulose, carboxymethyl hydroxyethylcellulose, carboxymethyl ethyl hydroxyethylcellulose, carboxymethyl octyl hydroxyethylcellulose, carboxymethyl cetyl hydroxyethylcellulose, carboxymethyl cetoxy-2-hydroxypropylcellulose, carboxymethyl butoxy-2-hydroxyethylcellulose, sulfoethyl hydroxyethylcellulose, sulfoethyl ethyl hydroxyethylcellulose, sulfoethyl cetyl hydroxyethylcellulose, sulfoethyl cetoxy-2-hydroxypropylcellulose, 2-hydroxypropyltrimethyl ammonium chloride hydroxyethylcellulose, 2- hydroxypropyltrimethylammonium chloride ethyl hydroxyethylcellulose, 2-hydroxypropyltrimethylammonium chloride butoxy-2-hydroxypropyl hydroxyethylcellulose, 2-hydroxypropyltrimethylammonium chloride octyl hydroxyethyl cellulose, 2-hydroxypropyltrimethylammonium chloride cetyl hydroxyethylcellulose, 2-hydroxypropyltrimethylammonium chloride cetoxy-2-hydroxypropyl hydroxyethylcellulose, 2-hydroxypropyllauryldimethylammonium chloride hydroxyethylcellulose, 2-hydroxypropyl trimethylammonium chloride 2-hydroxypropyllauryldimethylammonium chloride hydroxyethyl cellulose, diallyldimethylammonium chloride grafted hydroxyethylcellulose, diallyldimethyl ammonium chloride grafted cetyl hydroxyethylcellulose.

According to the aqueous dispersion mentioned above, the cellulose ether has a weight average molecular weight (Mw) of less than or equal to 500, 000 g/mol, preferably less than or equal to 350, 000 g/mol, more preferably 50, 000-320, 000 g/mol, most preferably 100, 000-320, 000 g/mol.

According to the aqueous dispersion mentioned above, the cellulose ether is a hydroxyethyl cellulose having a viscosity, in 2%aqueous solution, of 250-450 mPa·s measured using a Brookfield viscometer with spindle #2 at 60 rpm.

According to the aqueous dispersion mentioned above, the cellulose ether is hydrophobically modified and has a viscosity, in 1%aqueous solution, of 150-500 cps measured using a Brookfield viscometer at 6 rpm.

According to the aqueous dispersion mentioned above, the cellulose ether is hydrophobically modified and has a viscosity, in 1%aqueous solution, of 700-1000 cps measured using a Brookfield viscometer with spindle #2 at 6 rpm.

According to the aqueous dispersion mentioned above, the hydrophilic hydroxyethyl cellulose is present in an amount of greater than or equal to 50 wt%, preferably greater than or equal to 60 wt%, more preferably greater than or equal to 70 wt%, still more preferably greater than or equal to 80 wt%, even more preferably greater than or equal to 90 wt%, most preferably greater than or equal to 95 wt%, most preferably greater than or equal to 99 wt%, based on the total weight, as 100 wt%, of Component (b) , a protective colloid.

According to the aqueous dispersion mentioned above, the hydrophobically modified cellulose ether has a viscosity, in 1%aqueous solution, of 150-500 cps measured using a Brookfield viscometer at 6 rpm, and is present in an amount of greater than or equal to 50 wt%, preferably greater than or equal to 60 wt%, more preferably greater than or equal to 70 wt%, still more preferably greater than or equal to 80 wt%, even more preferably greater than or equal to 90 wt%, most preferably greater than or equal to 95 wt%, based on the total weight, as 100 wt%, of Component (b) , a protective colloid.

According to the aqueous dispersion mentioned above, the hydrophobically modified cellulose ether has a viscosity, in 1%aqueous solution, of 700-1000 cps measured using a Brookfield viscometer at 6 rpm, and is present in an amount of greater than or equal to 50 wt%, preferably greater than or equal to 60 wt%, more preferably greater than or equal to 70 wt%, still more preferably greater than or equal to 80 wt%, even more preferably greater than or equal to 90 wt%, most preferably greater than or equal to 95 wt%, based on the total weight, as 100 wt%, of Component (b) , a protective colloid.

According to the aqueous dispersion mentioned above, Component (c) , a nonionic surfactant, is selected from among alkyl alcohol polyoxyethylene ethers and/or polyoxyethylene alkyl acid esters, in which the alkyl moieties have carbon atoms of preferably 10-18, more preferably 12-16, and the polyoxyethylene moieties have EO units (-CH ₂CH ₂O-) of preferably 10-32, more preferably 12-16.

According to the aqueous dispersion mentioned above, alkylphenol ethoxylates (APEOs) are present in an amount of less than or equal to 0.1 wt%, preferably less than or equal to 0.05 wt%, more preferably less than or equal to 0.01 wt%, based on the total weight, as 100 wt%, of vinyl ester monomer.

According to the aqueous dispersion mentioned above, the anionic surfactants having a tan and/or brown and/or yellow appearance are present in Component (d) , an anionic surfactant, in an amount of less than 1 wt%, preferably less than 0.1 wt%, based on the total weight, as 100 wt%, of vinyl ester monomer.

Use of the aqueous dispersion mentioned above in architectural coatings, preferably in decorative coatings, more preferably in interior decorative coatings.

Use of the aqueous dispersion mentioned above for weakening water mark, rain mark, water flow mark or snail trail phenomenon on the film formed from waterborne architectural coatings in the presence of moisture.

According to the present invention, architectural coatings refer to waterborne emulsion paints comprising ethylene-vinyl ester copolymer emulsions, pigments, fillers, defoamers, leveling agents, and preservatives. The dosage of ethylene-vinyl ester copolymer emulsions is in an amount of more than 50wt%of the film forming polymers parts in the architectural coatings, preferably equal to or more than 75wt%, more preferably equal to or more than 90wt%, based on the total weight, as 100 wt%, of film forming polymers parts.

According to the present invention, water mark phenomenon including rain mark, water flow mark or snail trail refers to the phenomenon described in the water mark experiment of the invention patent specification.

Detailed Description of the Preferred Embodiments

Cellulose Ether 1: Natrosol HEC 250 G by Ashland, a hydroxyethyl cellulose having a viscosity, in 2%aqueous solution, of 250-450 mPa·s measured using a Brookfield viscometer with spindle #2 at 60 rpm, and a MS value of greater than or equal to 2.8 and less than or equal to 3.3.

Cellulose Ether 2: Natrosol Plus 330 HMHEC by Ashland, a hydrophobically modified cellulose containing both long-chain alkyl and hydroxyethyl and groups as the modifiers, having a viscosity, in 1%aqueous solution, of 150-500 mPa·s measured using a Brookfield viscometer at 6 rpm, and a MS value of greater than or equal to 2.8 and less than or equal to 3.3.

Cellulose Ether 3: Natrosol Plus 550 HMHEC by Ashland, a hydrophobically modified cellulose, having a viscosity, in 1%aqueous solution, of 700-1000 cps measured using a Brookfield viscometer with spindle #2 at 6 rpm, and a MS value of greater than or equal to 2.8 and less than or equal to 3.3.

PVOH 25/88, a polyvinyl alcohol having an alcoholysis degree of 88 mol%, and a viscosity, in 4 wt%aqueous solution, of 25 mPa·s at 20℃ according to DIN 53015, which is prepared into a 10.3 wt%aqueous solution before use.

Nonionic Surfactant:

Genapol 1879 by Clariant, tridecyl alcohol ethoxylate with 15 EO in 40 wt%aqueous solution, having an alkyl chain length of about C13 and an HLB value of 15.

Anionic Surfactant:

Maron A315, a sodium alkylbenzenesulfonate, which is prepared into a 15 wt%aqueous solution before use.

Maron A315, a disodium ethoxylated alcohol half ester of sulfosuccinic acid, which is prepared into a 31 wt%aqueous solution before use.

Disponil OSS 50, a visually yellowish oleic acid sulfonate, in which the alkyl moieties have about 18 carbon atoms

Foamaster 223, a mineral oil-based defoamer, supplied by BASF.

Table 1 Basic Formulation

*The amount of ethylene used in Table 1 refers to the amount of ethylene gas fed in each example.

The raw materials adjusted in Examples 1-3 and Comparative Examples 4-7 are shown in Table 2. The procedures were similar to that of Example 1.

Table 2 Aqueous Dispersions

	Ex. 1	Ex. 2	Ex. 3	C. Ex. 4	C. Ex. 5	C. Ex. 6	C. Ex. 7
Vinyl acetate	100.00	100.00	100.00	100.00	100.00	100.00	100.00
Ethylene	19.55	19.55	19.55	19.55	19.55	18.43	19.55
Cellulose Ether 1	0.90			0.90	1.24	1.80	1.74
Cellulose Ether 2		0.90
Cellulose Ether 3			0.90
PVOH 2588				0.90	0.50
Genapol 1879	1.60	1.60	1.60		0.80	0.80	0.80
Maron A315	0.11	0.11	0.11	0.11	0.10	0.11	0.11
Aerosol A-102	1.17	1.17	1.17	1.63	1.17	/	1.63
Disponil OSS 50					/	1.63

The amounts of protective colloids, nonionic surfactants and anionic surfactants listed in Table 2 refer to those of active substances thereof.

Example 1

DI water, an aqueous cellulose ether solution, anionic surfactants, a nonionic surfactant, and a catalytic amount of an aqueous FAS solution were added as an initial charge to a 5-liter reactor. The initial charge was mixed well, and adjusted to pH 4 before a portion of vinyl acetate was added.

The reactor was heated to 45℃, into which a portion of ethylene gas was introduced until a certain pressure therein was reached. Sodium persulfate and ascorbic acid were slowly and simultaneously added dropwise by a pump to initiate the reaction.

The temperature was raised to 70℃, while sodium persulfate, ascorbic acid and vinyl acetate were slowly and simultaneously added dropwise by a pump, and ethylene was passed in until the reaction was completed. During this process, the pressure in the reactor was maintained below 70 bar.

After reaction for 4 hours, the mixture was transferred to a degassing tank, where the defoamer Foamaster 223 was added, and after degassing for 30 minutes, the aqueous polymer dispersion was obtained.

The pH of resulting aqueous polymer dispersion was between 4.5 and 5, after 14 days storage at room temperature, which means this dispersion is stable.

The aqueous dispersions of the above Examples 1-3, after storage at 50℃ for 2 weeks, remained stable with no demulsification or phase separation, which means the long term storage stability is good.

An architectural coating composition was prepared as follows with the aqueous dispersions of the above examples and comparative examples.

Table 3 Architectural Coating Compositions

Water mark experiment:

The architectural coating composition was brushed on a 14 cm × 36 cm aluminum foil substrate at 25℃ and 50%relative humidity, scraped flat with a 120 μm wire bar applicator, and cured for 12 hours. After the coating film was dried, the coating composition was applied again on the film and scraped flat with an 80 μm wire bar applicator. After the film was formed, it was cured at room temperature (25℃) and 50%relative humidity for one week to obtain a rectangular coated test sample.

A 40-cm-high stainless steel cooling cuboid was arranged at 25℃ and 50%relative humidity, where the upper 1/4 section was filled with an ice-water mixture of about 10 cm in depth, and the rest 3/4 section was hollow. The rectangular test sample and the reference sample were vertically in parallel attached to the same surface of the cooling cuboid, with the coating film outward. How atmospheric moisture was condensed on the film surfaces was observed. When the first condensed water mark flowed to the bottom of the sample, the time was recorded.

These water marks are vertical shiny Streaks. Streaks are generally randomly spaced and follow gravitational direction.

After the sample was removed and air-dried for 24 hours, the number, color and gloss of water marks on the dried film were evaluated and scored according to the rating system as follows.

Table 4 Rating System

Comparative Example 6 is selected as the reference sample in Table 4.

Table 5.1 Improvements of Water Marks

	Ex. 1	Ex. 2	Ex. 3	C. Ex. 4	C. Ex 5	C. Ex 6	C. Ex 7
No. of water marks	3	3	4	3	3	3	3
Color	5	4	5	3	3	3	3
Gloss	3	4	4	3	4	3	4
Total score	11	11	13	9	10	9	10

Table 5.2 Period of time when the first condensed water mark flowed to the bottom of the sample

	Ex. 1	Ex. 2	Ex. 3	C. Ex. 4	C. Ex. 5	C. Ex. 7
Hours	2.90	2.50	2.10	3.20	3.50	3.50

Table 4 and Table 5 when the dosage of protective colloid is low, the total score of water mark is high. The total score of water mark is higher when hydrophobically modified celluloses are used. In Comparative Examples 4-7, when the dosage of protective colloid is high, the total score of water mark is low, the water marks flow for a longer period of time. When protective colloid containing PVOH, sample leading to lower gloss scores.

Claims

An aqueous polymer dispersion comprising

Component (a) –one or more kind (s) of ethylene-vinyl ester copolymer (s) ,

Component (b) –one or more kind (s) of protective colloid (s) ,

Component (c) –one or more kind (s) of nonionic surfactant (s) , and

Component (d) –one or more kind (s) of anionic surfactant (s) ,

wherein Component (b) , a protective colloid, is present in an amount of less than or equal to 1.5 wt%, preferably 0.5-1.2 wt%, more preferably 0.7-1.1 wt%, based on the total weight, as 100 wt%, of vinyl ester monomer, and

ethylene monomer is present in Component (a) , an ethylene-vinyl ester copolymer, in an amount of less than or equal to 40 wt%, preferably 5-35 wt%, more preferably 10-30 wt%, even more preferably 18-25 wt%, most preferably 18-22 wt%, based on the total weight, as 100 wt%, of vinyl ester monomer.
According to the aqueous dispersion mentioned in claim 1, the vinyl ester monomer is present in Component (a) , an ethylene-vinyl ester copolymer, in an amount of greater than or equal to 70 wt%, preferably greater than or equal to 80 wt%, more preferably 80-90 wt%, most preferably 82-88 wt%, based on the total weight, as 100 wt%, of all monomers.
According to the aqueous dispersion mentioned in claim 1 or 2, Component (c) , a nonionic surfactant, is present in an amount of greater than or equal to 1 wt%, preferably 1.2-3 wt%, more preferably 1.4-2.5 wt%, most preferably 1.2-2 wt%, based on the total weight, as 100 wt%, of vinyl ester monomer.
According to the aqueous dispersion mentioned in any of claim 1-3, Component (c) , a nonionic surfactant, and Component (b) , a protective colloid, are used in a mass ratio of 1.0-2.5, preferably 1.0-2.0, more preferably 1.5-2.0, most preferably 1.6-1.9.
According to the aqueous dispersion mentioned in any of claim 1-4, Component (d) , an anionic surfactant, is present in an amount of 0.5-3 wt%, preferably 0.8-2.5 wt%, more preferably 1-1.8 wt%, based on the total weight, as 100 wt%, of vinyl ester monomer.
According to the aqueous dispersion mentioned in any of claim 1-5, Component (b) , a protective colloid containing cellulose ether, the cellulose ether is present in an amount of greater than 50 wt%, preferably greater than or equal to 65 wt%, more preferably greater than or equal to 75 wt%, even more preferably greater than or equal to 85 wt%, most preferably 95 wt%, based on the total weight, as 100 wt%, of Component (b) , a protective colloid.
According to the aqueous dispersion mentioned in claim 6, the cellulose ether is one, or a combination, of alkyl celluloses, hydroxyalkyl celluloses and carboxyalkyl celluloses, preferably one, or a combination, of hydroxyethyl celluloses, hydroxypropyl celluloses, carboxymethyl celluloses and monomethyl celluloses, more preferably hydroxyethyl celluloses.
According to the aqueous dispersion mentioned in claim 6 or 7, the cellulose ether has a weight average molecular weight (Mw) of less than or equal to 500,000 g/mol, preferably less than or equal to 350,000 g/mol, more preferably 50,000-320,000 g/mol, most preferably 100,000-320,000 g/mol.
According to the aqueous dispersion mentioned in any of claim 6-8, the cellulose ether is a hydroxyethyl cellulose having a viscosity, in 2%aqueous solution, of 250-450 mPa·smeasured using a Brookfield viscometer with spindle #2 at 60 rpm.
According to the aqueous dispersion mentioned in any of claim 6-9, the hydrophilic hydroxyethyl cellulose is present in an amount of greater than or equal to 50 wt%, preferably greater than or equal to 60 wt%, more preferably greater than or equal to 70 wt%, still more preferably greater than or equal to 80 wt%, even more preferably greater than or equal to 90 wt%, most preferably greater than or equal to 95 wt%, most preferably greater than or equal to 99 wt%, based on the total weight, as 100 wt%, of Component (b) , a protective colloid.
Use of the aqueous dispersion mentioned in any of Claim 1-10 in architectural coatings, preferably in decorative coatings, more preferably in interior decorative coatings.
Use of the aqueous dispersion mentioned in any of Claim 1-10 for weakening water mark, rain mark, water flow mark or snail trail phenomenon on the film formed from waterborne architectural coatings in the presence of moisture.