WO2017135893A1

WO2017135893A1 - Aqueous dendritic amine coatings

Info

Publication number: WO2017135893A1
Application number: PCT/SG2017/050040
Authority: WO
Inventors: Shaofeng Wang; Hairong Li; Swee How SEOW
Original assignee: Nipsea Technologies Pte Ltd
Priority date: 2016-02-05
Filing date: 2017-01-26
Publication date: 2017-08-10

Abstract

The present invention relates to a water-based emulsion coating composition, e.g. paint composition, comprising a hyper- branched or dendritic poly(amido)amine (PAMAM) polymer as a neutralizing agent, at least one isothiazolone biocide, and a binder.

Description

Title of Invention: Aqueous Dendritic Amine Coatings

Technical Field

The present invention relates to a neutralizing agent for use in polymer compositions, preferably emulsion polymer compositions, more particularly, water-based or waterborne emulsion polymer compositions.

Background Art

Neutralizing agents or pH adjusters are commonly employed in polymer compositions, e.g., water-based paint compositions or paint formulations, as pH buffering agents. Such agents are typically amine-based and serve to improve the shelf-life and stability of the polymer compositions. In paint applications, it is generally preferred to provide environmentally friendly, water-based, odorless paints. Conventional neutralizing agents may include amines such as, dimethylethanolamine (DMEA), triethylamine (TEA), ammonia, or 2-amino-2-methyl-lpropanol. However, these known neutralizing agents may be volatile and are prone to escaping in the process of paint manufacturing, storage and the paint coatings after application, resulting in undesirable VOC emissions and unpleasant odors. The emitted vapors may also cause irritation to the skin, mucosa and eyes of humans and animals.

Additionally, it may be desirable for water based latex emulsions to exhibit antimicrobial properties. Biocides are typically added to the finished latex after processing is completed to protect the latex paint, or the surface to which the paint is applied, from microbial attack. Isothiazolone biocides are widely used in a variety of industry for control of microbial growth and biofouling. Commonly used biocides in water based latex paint may include 5-chloro-2-methyl-4-isothiazolin-3-one (CMIT) and 2-methyl-4-isothiazolin-3-one (MIT). Mixtures of CMIT and MIT are also provided, which may have broad spectrum efficacy versus bacterial, algae and fungi. However, the presence of known neutralizing agents has also been observed to destabilize these biocidal components added to paint compositions to achieve anti-microbial effects. These biocides, especially CMIT, are prone to decomposition under basic conditions, in particular via nucleophilic attack by amines. To date, there has been no known, viable substitute for the conventional neutralizing agents, which would address or at least ameliorate some of the disadvantages discussed above.

Accordingly there is a need to provide alternative neutralizing agents that can provide adequate buffering but without increasing the volatile organic content (VOC) of a paint composition.

Additionally, it is also desired to provide alternative neutralizing agents that are compatible for use with paint compositions comprising anti-microbial / biocidal compounds or substances. In addition, the alternative neutralizing agent should ideally not impair the rheological or film-forming properties of the compositions to which it has been added. Hence, it is a non-trivial task to provide a substitute that would meet all of the above requirements. Summary of Invention

In one aspect of the present disclosure, there is provided a water based emulsion coating composition comprising, a) a neutralizing agent comprising a hyperbranched or dendritic poly(amido)amine (PAMAM) having at least four amine functional groups, b) at least one isothiazolone biocide, and c) a binder component comprising polymer particles dispersed in an aqueous phase. In another aspect of the present disclosure, there is provided a method of neutralizing a water based emulsion coating composition comprising at least one isothiazolone biocide, the method comprising adding to said coating composition, a dendritic or hyperbranched PAMAM having at least four amine functional groups, wherein said dendritic or hyperbranched PAMAM is present in said composition in an amount of 0.01 to 0.5 wt. % based on the weight of the coating composition.

In one embodiment, the neutralizing agent is a PAMAM that has been optionally modified with one or more functional groups other than an amino functional group. In other words, the poly(amido)amine may express other reactive functional groups, e.g., hydroxyl, acrylate, carbonyl, carboxyl, or carbamate functional groups, other than amino functional groups. Alternatively, the neutralizing agent may be unmodified PAMAM wherein all the peripheral functional groups are amino functional groups. Additional functional groups or non-amino functional groups may be expressed, present or located at the branching nodes of the poly(amido)amine or at the terminal ends of the poly(amido)amine.

Advantageously, it has been found that the disclosed poly(amido)amine as neutralizing agent provides pH buffering properties to the polymer composition. The pH stability is comparable to paint formulations containing conventional neutralizing agents such as 2-amino-2-methy-l-propanol (marketed as AMP-95), triethanolamine (TEA) or dimethylethanolamine (DMEA).

Further advantageously, it has been found that the provision of the disclosed neutralizing agent leads to substantially reduced VOC emission of the paint formulation. Advantageously, the substantially reduced or negligible VOC emission enables the manufacture of substantially odorless paint formulations. Advantageously, the VOC emission of paint compositions containing the neutralizing agent as disclosed herein is reduced relative to comparable paint compositions using a conventional neutralizing agent such as DMEA or TEA.

Also advantageously, the presence of a hyper-branched or dendritic polymer as the neutralizing agent may also serve a secondary function of acting as rheological additives to provide a thickening effect to paint formulations where desired. This may have the effect of providing low shear viscosity which prevents pigment settling in paint compositions.

Still advantageously, it has been unexpectedly found that when the paint formulations are mixed with antimicrobial agents and/or biocides, the use of the poly(amido)amine neutralizing agent leads to improved stability of the antimicrobial agents and biocides. For instance, it has been found that, where the disclosed poly(amido)amine neutralizing agent is used, the concentration and/or activity of the biocide compounds are not adversely affected or not as adversely affected relative to paint compositions which employ conventional amine buffers such as a DMEA or AMP-95. In other words, it has been observed that biocidal compositions may be more stable when mixed with the disclosed dendritic amine neutralizing agent than compared to conventional amines.

Still advantageously, it has been found that the disclosed hyperbranched or dendritic amine neutralizing agent does not impair the stability or film-forming properties of the paint composition. Brief Description of Figures

Fig. 1 is a chart showing the weight loss of respective amine neutralizing agents after being subjected to heat treatment at 110°C for 1 hour. Definitions

Unless defined otherwise, "alkyl" or "alkylene" as a group or part of a group refers to a straight or branched aliphatic hydrocarbon group, containing from 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, or 12 carbon atoms. In embodiments, an alkyl group may contain a carbon chain length in a range comprising an upper and lower limit from any two integers disclosed above, e.g., Cl-₁₂, C_4-8, C_6-10, etc.

The term "alkylsilane" refers broadly to alkyl(SiH₄), wherein alkyl is as defined above.

The term "alkoxy" refers to an alkyl-O- group in which alkyl is as defined herein.

The term "alkanolamine" refers to an alkyl group as defined herein having at least one amino functional group and at least one hydroxyl functional group.

The term "alkoxysilyl" refers to a -Si(OR)n group, wherein R is an alkyl as defined herein and n is an integer selected from 1, 2, 3, or 4.

The term "biocide" refers to a compound which is inhibitory to degradation activities of a chemical substance or microorganism (e.g. bacteria, algae, fungi) on a product. The term "biocide" when used herein also refers to a compound used in a variety of industry for controlling microbial growth or fouling. The tern "biocide" is also to be interpreted broadly to include preservatives, disinfectants, insecticides and pesticides.

Unless specified otherwise, the terms "comprising" and "comprise", and grammatical variants thereof, are intended to represent "open" or "inclusive" language such that they include recited elements but also permit inclusion of additional, unrecited elements.

As used herein, the term "about", in the context of concentrations of components of the formulations, typically means +10% of the stated value, more typically +7.5% of the stated value, more typically + 5% of the stated value, more typically + 4% of the stated value, more typically + 3% of the stated value, more typically, + 2% of the stated value, even more typically + 1% of the stated value, and even more typically + 0.5% of the stated value. Throughout this disclosure, certain embodiments may be disclosed in a range format. It should be understood that the description in range format is merely for convenience and brevity and should not be construed as an inflexible limitation on the scope of the disclosed ranges. Accordingly, the description of a range should be considered to have specifically disclosed all the possible sub-ranges as well as individual numerical values within that range.

For example, description of a range such as from 1 to 6 should be considered to have specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6 etc., as well as individual numbers within that range, for example, 1, 2, 3, 4, 5, and 6. This applies regardless of the breadth of the range.

Detailed Description

Accordingly, one embodiment of the present invention relates to a water based emulsion coating composition comprising, a) as a neutralizing agent, a hyper-branched or dendritic poly(amido)amine having at least four amine functional groups, b) at least one isothiazolone biocide, and c) a binder component comprising polymer dispersed in an aqueous phase.

Dendritic polymers are generally globular in structure and may include dendrimers which exhibit completely and symmetrically branched molecules. Such dendrimers may be substantially monodisperse. Dendritic polymers may also exhibit imperfect or incomplete branching, and wherein the dendritic polymer molecule may be polydisperse.

The hyper-branched or dendritic polymer may have a pKa (an acid dissociation constant) at 25 °C of at least 9.0. In embodiments, the hyper-branched or dendritic polymer may comprise terminal primary amines having a pKa of at least 9.0, or is selected from about 9.0, 9.1, 9.2, 9.3, 9.4, 9.5, 9.6, 9.7, 9.8, 9.9, 10.0, 10.1, 10.2, 10.3, 10.4, 10.5, 10.6, 10.7, 10.8, 10.9 or 11.0, or is in a range comprising an upper and lower limit selected from any two of the above. In embodiments, the hyper-branched or dendritic polymer may comprise terminal primary amines having a pKa selected from about 9 to 10, or from about 10 to 11.

The hyper-branched or dendritic polymer may be characterized as having a weight loss of less than 6 wt. % at 110 °C after 1 hour. In embodiments, the hyper-branched or dendritic polymer may comprise terminal primary amines and exhibits a weight loss of less than 6 wt. %, less than 5 wt. %, less than 4 wt. % or less than 3 wt. % when exposed to temperature conditions of 110°C for a duration of at least an hour.

In one embodiment, the dendritic PAMAM may, for illustration only, exhibit the following structure for a 1st generation PAMAM:

The amino functional groups of the dendritic PAMAM may be located at the branching nodes or at the terminal ends of the polymer. In embodiments, the poly(amidoamine) may comprise from about 4 to about 4096 amino functional groups, from about 4 to about 8, from about 4 to about 16, from about 4 to about 32, from about 4 to about 64, from about 4 to about 128, from about 4 to about 256, from about 4 to about 512, from about 8 to about 16, from about 8 to about 32, from about 8 to about 64, from about 8 to about 128, from about 8 to about 256, from about 8 to about 512, from about 16 to about 32, from about 16 to about 64, from about 16 to about 128, from about 16 to about 256, from about 16 to about 512, from about 32 to about 64, from about 32 to about 128, from about 32 to about 256, or from about 32 to about 512 amino functional groups. In embodiments, the amino dendritic PAMAM may comprise from 4 to 10, 4 to 20, 4 to 30, 4 to 40, 4 to 50, 4 to 60, 4 to 70, 4 to 80, 4 to 90, or 4 to 100 amino functional groups.

In one embodiment, a generation-zero dendritic or hyperbranched PAMAM may be used (i.e., around 4 peripheral N¾ functional groups per polymer chain/dendritic molecule). In another embodiment, a 1^st generation dendritic PAMAM may be used (approx. 8 functional groups). In yet another embodiment, a 2nd generation dendritic PAMAM may be used (approx. 16 functional groups). In yet another embodiment, a 3 generation dendritic PAMAM may be used (approx. 32 functional groups). In yet another embodiment, a 4^th generation dendritic PAMAM may be used (approx. 64 functional groups). In yet another embodiment, a 5^th generation dendritic PAMAM may be used (approx. 128 functional groups).

The neutralizing agent may comprise a co-polymer that is linear, branched, hyperbranched or dendritic. The co -polymer may be reactive with PAMAM or reactive with one or more non-amino functional groups grafted on a substituted PAMAM. The co-polymer may comprise amino functional groups.

The neutralizing agent may also comprise one or more monomeric amines in admixture with the disclosed hyper-branched or dendritic PAMAM comprising at least four amino functional group. The neutralizing agent may also comprise a mixture/blend of two or more PAMAM or modified PAMAM polymers as disclosed herein. In embodiments, the coating composition may be substantially devoid of other amino -functional additives acting as pH adjusters or neutralizing agents.

Advantageously, the disclosed dendritic PAMAM neutralizing agent may be employed as the sole neutralizing agent in the polymer composition. Advantageously, the polymer composition may be substantially devoid of other amine-functional compounds or amine derivatives having a molecular weight of less than 500 Da. The amino functional groups may be selected from primary amines (-NH₂), secondary amines (-NHR1), tertiary amines (-NR1R2), or cyclic amines, wherein R1 and R2 may be independently selected from the group consisting of. H, alkyl, alkanolamines, alkylamine, alkoxy, alcohol, alkylate, alkylsilane, alkoxysilyl, alkoxysilyl alkylate, amino acid, carbonyl, carboxyl, carboxylate, or esters. Cyclic amines may include heterocycloalkyl ring structures having 3, 4, 5, 6, 7, or 8 ring atoms, wherein at least one heteroatom is N and wherein the ring is saturated or aromatic, and is optionally substituted by one or more function groups selected from alkyl, alkanolamines, alkylamine, alkoxy, alcohol, alkylate, alkylsilane, alkoxysilyl, alkoxysilyl alkylate, amino acid, carbonyl, carboxyl, carboxylate, or esters. The amino functional groups may be amide functional groups wherein R1 is a carbonyl group (-CO-) in secondary amines and wherein either R1 or R2 is a carbonyl group (-CO-) in tertiary amines.

The disclosed neutralizing agent may have a molecular weight of at least 500. The dendritic neutralizing agent may have a molecular weight of from 500 to 8,000 Da, e.g.,, from about 500 to about 600 Da, from about 500 to about 700 Da, from about 500 to about 800 Da, from about 500 to about 900 Da, from about 500 to about 1,000 Da, from about 500 to about 1,200 Da, from about 500 to about 1,400 Da, from about 500 to about 1,600 Da, from about 500 to about 1,800 Da, from about 500 to about 2,000, from about 500 to about 2,200, from about 500 to about 2,500, from about 500 to about 2,700, from about 500 to about 3,000, from about 500 to about 3,250, from about 500 to about 3,500 Da, from about 500 to about 3,750, about 500 to about 4,000 Da, from about 500 to about 4,250, from about 500 to about 4500 Da, or from about 500 to about 4,750, from 500 to 5,000, from 500 to 5,250, from 500 to 5,500, from 500 to 5,750, from 500 to 6,000, from 500 to 6,250, from 500 to 6,500, from 500 to 6,750, from 500 to 7,000, from 500 to 7,250, from 500 to 7,500, from 500 to 7,750, or from 500 to 8,000. The neutralizing agent may be present in the paint formulation or polymer composition (pre-cure) in an amount of from about 0.01 to about 1%, from about 0.01 to about 0.9%, from about 0.01 to about 0.8%, from about 0.01 to about 0.7%, from about 0.01 to about 0.6%, from about 0.01 to about 0.5%, from about 0.01 to about 0.4%, from about 0.01 to about 0.3%, from about 0.01 to about 0.2%, or from about 0.01 to about 0.1% be weight of the paint formulation. Advantageously, a substantially small amount (less than about 1 wt. %) of the neutralizing agent is shown to be capable of achieving the desirable technical effects disclosed herein.

The neutralizing agent may comprise, in addition to amino functional groups, at least one additional, or at least two additional types, or at least three types of distinct functional groups or surface groups. In one embodiment, the neutralizing agent may comprise, in addition to the amino functional groups, at least one hydrophobic or oleophobic functional group. Exemplary additional functional groups may be selected from alkanolamine groups, alkoxysilyl groups, amide groups, or carboxylic acid groups. In embodiments, the additional functional groups may be selected from amidoethanol, amidoethylethanolamine, sodium carboxylate, diamines, alkanolamine, succinamic acid, trimethoxysilyl, or tris (hydroxymethyl) amidomethane group s .

The neutralizing agent may comprise a PAMAM core structure having amino branching nodes, and wherein the PAMAM is optionally substituted with one or more substituents X. In one embodiment, a substituted PAMAM polymer may possess the following general formula:

(NH₂)q-P-(X)r

wherein P is the dendritic poly(amido)amine polymer, and wherein -NH₂, and X represent peripheral functional groups covalently coupled to said dendritic polymer P,

wherein each occurrence of X is independently selected from:

and wherein q+r represents the total number of surface or peripheral functional groups of polymer P. The denotes an attachment point.

Advantageously, suitable surface groups can be advantageously added / combined / selected to confer a specific property or a combination of properties to the dendritic polymer neutralizing agent. For instance, where X is alkanolamine, the incorporation of long hydrocarbon side chains (e.g., a hydrocarbon side chain having 3 - 10, 4-10, 5-10, 6-10, 7-10, or 8-10 carbons) may enable the modified PAMAM to also function as a surfactant, which may be helpful in dispersing pigments contained in the polymer composition. In another example, the presence of siloxane or alkoxysilyl functional groups as peripheral groups may advantageously enable the substituted PAMAM to be used as an adhesion promoter, or to improve cross-linking density. In yet another example, where UV curing is desirable, the dendritic PAMAM may also be suitably grafted with acrylate functional groups.

The neutralizing agent may comprise a ratio of amino functional groups (-NH₂) to other non-amine functional groups (-X) of from about 1:9, 1:8, 1:7, 1:6, 1:5, 1:4, 1:3, 1:2, 1: 1, 2: 1, 3: 1, 4: 1, 5:1, 6: 1, 7: 1, 8: 1 or about 9: 1. The ratio may also be provided in a range selected from any two ratios herein defined. In other embodiments, the ratio of -NH₂ groups to non-NH₂ functional groups may be from about 99: 1 to 1:99.

The dendritic amine neutralizing agent may comprise at least 5% of the functional groups as amino functional groups, at least 10% of the functional groups as amino functional groups, at least 20% of the functional groups as amino functional groups, at least 30% of the functional groups as amino functional groups, at least 40% of the functional groups as amino functional groups, at least 50% of the functional groups as amino functional groups, at least 60% of the functional groups as amino functional groups, at least 70% of the functional groups as amino functional groups, at least 80% of the functional groups as amino functional groups, at least 90% of the functional groups as amino functional groups, at least 95% of the functional groups as amino functional groups, or at least 99% of the functional groups as amino functional groups; and wherein the remaining functional groups are selected from those disclosed herein.

In an embodiment, the water based emulsion coating composition does not contain hyperbranched or dendritic polyethyleneimines (PEI).

The isothiazolone biocide may be independently selected from but not limited to the group 2-methyl-4-isothiazolin-3-one (ΜΓΓ), 5-chloro-2-methyl-4-isothiazolin-3-one (CMIT), benziosthiazolinone (BIT), octylisothiazolinone (OIT), dichlorooctylisothiazolinone (DCOIT), or butylbenziothiazolinone (BBIT). In embodiments, a mixture of two or more distinct isothiazolone biocides may be present in the water based emulsion composition of the present disclosure. In one embodiment, the disclosed composition may comprise only MIT. In another embodiment, the disclosed composition may comprise only CMIT. In another embodiment, the disclosed composition may comprise a mixture of CMIT and MIT. In another embodiment, the mixture of CMIT and MIT prepared in a ratio of 3: 1. Advantageously, as shown in the Examples contained herewith, it has been demonstrated that the biocide levels of a paint formulation according to the present invention show improved stability over paint formulations using other types of amine neutralizing agents. Advantageously, the present disclosure further provides the use of the disclosed dendritic amine neutralizing for stabilizing isothiazolinone-based biocides in paint formulations.

For improving aqueous-dispersibility, the dendritic PAMAM neutralizing agent may comprise one or more peripheral hydrophilic functional groups. The coating composition may be provided as a one-pot mixture or 2-part composition. In one embodiment, the composition is an emulsion paint formulation. In another embodiment, the paint composition is a water-based polyacrylate emulsion or a acrylate copolymer emulsion, wherein the primary resin component is a polyacrylate polymer, styrene-butadiene polymer, vinyl acetate polymer, polyurethane dispersion or co-polymer.

In other embodiments, the binder or the primary resin component may be produced via emulsion polymerization of a monomer mixture, including but not limited to the following monomers, alkylacrylate (e.g., meth(acrylate), methylacrylate, ethylacrylate, butylacrylate), alkylmethacrylate, vinyl alcohol, vinyl acetate, vinyl acetate-ethylene, styrene, acrylonitrile, etc. The binder may be dispersed in water or an aqueous solvent. In one embodiment, the polymer composition as disclosed herein may comprise as a binder, an acrylate-styrene emulsion polymer.

The disclosed coating composition may further comprise at least one or more rheological additives. Suitable rheological additives may be selected from, but are not limited to, hydroxyethycellulose (HEC), hydrophobically modified alkali soluble emulsion (HASE), hydrophobically modified ethylene oxide urethane (HEUR), or mixtures thereof.

The composition may have a pH of 7 or greater, e.g., the pH may be selected from 7- 12, 7-11, 7-10, 7-9 or 7-8, 8-12, 8-11, 8-10, 8-9, 9-12, 9-11, or 9-10.

The dendritic polymer may exhibit low volatility and a weight loss at 110 °C of below 10%, prefer below 8%, more preferably below 6% (according to ASTM testing method D2369-10). By weight loss, it is intended to refer to the mass of the polymer (e.g., the PAMAM) that is lost after a curing / cross-linking procedure as compared to its mass pre- cure.

Another aspect of the present disclosure relates to an aqueous-dispersible coating composition comprising: a neutralizing agent as disclosed herein, and a polymer binder comprising emulsion polymer particles with solid content 40-60 wt%, and wherein the particle size may be from 50 nm - 0.5μιη as determined by electron microscopy. The emulsion polymer particles may possess a particle size (or particle diameter) of around 50 nm, 100 nm, 150 nm, 200 nm, 250 nm, 300 nm, 350 nm, 400 nm, 450 nm, or 500 nm. The emulsion polymer particles may exhibit a size distribution wherein the range of the particle diameters may comprise an upper limit and a lower limit selected from the diameters disclosed above.

There is also provided a method of buffering a water based emulsion coating composition comprising at least one isothiazolone biocide, the method comprising a step of mixing the dendritic PAMAM neutralizing agent as disclosed herein with a polymer binder in an amount of 0.01 to 0.5 wt. % based on the total weight of the polymer composition. There is further provided a paint formulation comprising emulsion polymer particles, and as a sole neutralizing agent, a dendritic polymer having at least one -N¾ functional group or a substituted or non-substituted PAMAM as described hereinabove. There is further provided a paint comprising a coating composition as herein described.

There is further provided a method of improving biocide stability of a water-based polymer composition as described herein, the method comprising the addition of a polyamidoamine dendritic neutralizing agent according to embodiments of the present disclosure to the water-based polymer composition. There is also disclosed a method of reducing emission of volatile organic compounds from a water-based polymer emulsion , the method comprising the addition of a polyamidoamine dendritic neutralizing agent according to embodiments of the present disclosure to the water-based polymer composition. In embodiments of the disclosed methods, the polyamidoamine dendritic neutralizing agent is added as a sole neutralizing agent. In embodiments, the disclosed methods exclude the addition of amino additives having a molecular weight of less than 500 Da, e.g., DMEA, TEA. The disclosed methods may also exclude the addition of PEL In one embodiment, the disclosed dendritic amino polymer may be advantageously added to a latex paint formulation. Such latex paint formulations may comprise, in addition to the disclosed dendritic amino polymer as a neutralizing additive or agent, a binder resin, one or more pigment compounds, and other additives such as surfactants, solvents, corrosion inhibitors, rheology modifiers. In embodiments, the latex paint formulations may not require rheology modifiers due to the thickening effect provided by the dendritic polymer.

Another aspect provides the use of the disclosed PAMAM as a pH adjusting agent in a polymer composition, preferably in a water-dispersible polymer composition, more preferably in a water-dispersible latex paint formulation. The disclosed PAMAM may be used as a sole pH adjusting agent.

Examples

To demonstrate the beneficial technical effects of PAMAM or modified PAMAM neutralizing agents, a number of experiments have been carried out and the following will provide the results and discussion regarding the same.

Raw materials:

1. 95% 2-Amino-2-methyl-l-propanol solution (AMP-95): supplier from Angus Chemie GmbH. 2. Unsubstituted Poly(amidoamine) (PAMAM) dendritic polymer kindly provided by WeiHai CY Dendrimer Technology Co., Ltd, as follows:

Table 1

3. Dendritic hyperbranched polyethyleneimines (PEI) (Loxanol MI-6730 with Mw=750 g/mol and Loxanol MI-6735 with Mw=20000 g/mol) kindly provided by BASF Co., Ltd.

Hyperbranched PEI can be described in the following general formula: -(CH₂-CH₂-NH)_n-; n=10-10⁵. PEI is branched, spherical polyamines with a well-defined ratio of primary, secondary and tertiary amine functions [Lupasl® Product Range: polymeric amine - polyethylenimines, Preliminary Technical Information, BASF, 1996,9]. They may be described in the following partial structural formula:

PEI is for the first time selected as pH adjuster for waterborne latex paint. Due to the high Mw of PEI compared to conventional amine monomer pH adjusters, PAMAMs and PEIs are low volatile and low emission. In the examples below, the presence of different pH adjusters (i.e. PAMAM and PEI) on the storage stability and degradation effect of CMIT biocide is studied. 4. Caprolactone monomer kindly provided by Perstorp.

5. Dimethylethanolamine (DMEA) and Triethanolamine (TEA): Purchased from Sigma- Aldrich.

6. Vinilex Low Odour 5048 White latex paint and Super Weatherbond 00E55 White latex paint: Kindly provided by Nipponpaint Singapore Co., Ltd consisting of the composition as shown in Table 2. The two paint formulations differ in the types and amounts of pH adjuster used.

Table 2

The paint formulations according to Table 2 are prepared by first adding deionized water into a dispersion tank. The mixing speed is controlled at 800-1000 rev/min. Thereafter, raw materials 2 to 7 are sequentially added into the dispersion tank. During addition, an interval of 2 to 3 minutes in between introduction of each raw material is maintained to ensure adequate mixing. The mixing speed is then raised to 1500-1800 rev/min for 15 to 20 minutes, then subsequently reduces to 500-800 rev/min. Raw materials 8 to 12 are then added. During addition, an interval of 2 to 3 minutes in between introduction of each raw material is maintained to ensure adequate mixing. Finally, more water is added, where necessary, to achieve a suitable viscosity. Experimental Results

Example 1:

Determining weight loss at 110 °C for 1 hour according to ASTM D2369-10

Table 3

The graph in Fig. 1 and table 3 show the weight loss results of conventional low molecular weight amine neutralization agents, such as AMP95, DMEA, TEA after heat treatment for 1 hour according to ASTM D2369-10. Notably, each of AMP-95, DMEA and TEA show 100% weight loss at 110 °C for 1 hour. However, PAMAM dendritic polymers, such as CYD-IOOA, CYD-110A, CYD-120A, WU438 experience weight losses of less than 6%wt at 100 °C for 1 hour. These results indicate that PAMAM dendritic is much less volatile compared to conventional amine neutralization agents.

Example 2:

Determining the pH value of the PAMAM compared to AMP-95

The amine-based neutralizing agents being tested by a pH meter in this Example are provided in table 4 below.

Although PAMAM dendritic polymers have much higher Mw compared to conventional amine monomer, such as AMP95, DMEA and TEA, PAMAM dendritic polymers have the highest overall amine (N, NH, N¾) content. The pH values of the respective amines in DI water are provided in Table 5.

Comparable to conventional amine monomer, PAMAM dendritic polymers surprisingly show similar alkali and pH adjustment properties, even when present in very low concentrations in water.

Example 3:

PAMAM as pigment dispersant

50g DI water and lOOg Talc (800 mesh) with 1% and 2% of PAMAM (CYD-120A) based on the weight of Talc was added to a 250ml container. The mixture is mixed at 1000 RPM/min by using a dispermat for 30min. The appearance of the resulting solution is observed and noted in Table 6.

Besides providing alkali properties, it can be seen that PAMAM dendritic polymers also advantageously help to disperse pigment in order to obtain homogenous paste. This may be particularly useful for preparing masterbatch compositions. Example 4:

PAMAM as rheological additives to enhance thickening effect

room temperature.

Compared to conventional amine monomers, such as AMP95 and DMEA, PAMAM dendritic polymers may be able to provide higher viscosity when combined with HEC thickener (Natrosol^® 250). Advantageously, this is beneficial towards dispersing pigments in coating compositions and prevents pigment precipitation.

Example 5:

PAMAM in white latex paint (Super Weatherbond 00E55).

The reduction in pH may cause destabilization of the polymer dispersion. In addition acidic conditions may lead to corrosive environments on the surface of the plant equipment, which may result in structural/chemical damage. So the ability to maintain pH stability is of utmost importance for the water-based paints.

AMP-95 is the most commonly used amine in water based latex paints as neutralizing agent. Compared to AMP-95, it has been found that PAMAM dendritic polymers provide similar or comparable performance, in terms of fineness, pH stability and viscosity stability after storage. In addition, most of PAMAM dendritic polymers also provide higher low shear viscosity for the latex paint, due to its thickening effect by forming strong hydrogen bonding in the latex paint system.

Example 6:

PAMAM in White latex paint (Vinilex Low Odour 5048)

In Vinilex Low Odour 5048 White Latex Paint, compared to monomeric or non-dendritic amine neutralizing agents (e.g., AMP95), it has been found that PAMAM dendritic polymers provide similar or even better performance, in terms of fineness, pH stability and viscosity stability after storage. This is evidenced by the smaller magnitude of pH changes over a period of one month for paint formulations comprising PAMAM when compared to paint formulations comprising AMP-95. Experiment 7:

Effect of using different pH adjusters on CMIT/MIT stability in white latex paint

(Super Weatherbond 00E55)

Water based paints usually contain high water content and high nutrient level, which in turn provides an environment that is conducive for the proliferation and growth of microbes. Microbes and their metabolic byproducts, on top of being harmful or potentially toxic, can also contribute to the breakdown of the polymer dispersion, leading to the degradation of the coating or paint. Many factors are affected by the presence of microbes and their metabolic byproducts. A mixture of 5-chloro-2-methyl-4-isothiazolin-3-one and 2-methyl-4-isothiazolin-3- one (CMIT/MIT) is a commonly used biocide system in water-based paints. However, alkaline solutions and formulations tend to degrade the CMIT molecule, which leads to a reduction in the concentration and effectiveness of the biocide system. It is thus useful to provide pH adjusters which exert reduced or no side-effects to degrade the CMIT.

Experiment 7 shows PAMAM dendritic polymer, except CYD120, has the lowest adverse effect of the concentration of CMIT, especially CYD-IOOA, which almost shows a stable amount of CMIT after 6 days. This is a useful and unexpected technical result.

Experiment 8:

Effect of using dendritic PEI as pH adjusters on CMIT/MIT stability in white latex paint (Super Weatherbond 00E55)

Experiment 8 shows PEI dendritic polyamines having the most adverse effect on the stability of CMIT. After the paint preparation, the initial CMIT concentration is immediately tested and the initial CMIT concentration determined to be only about 1.19 ppm and 1.17 ppm compared to the control (when using AMP95 as pH adjuster) of about 10.22 ppm in Experiment 7. The CMIT could not even be detectable by the HPLC only after 1 day storage at room temperature. This result indicates the high risk of using PEI dendritic polyamine as pH adjuster, which will degrade the biocide CMIT and put the paint at the risk for bacterial attract.

Experiment 9: modification of PAMAM by hydrophobic caprolactone (CYD-llOA-25% Capa)

In a nitrogen atmosphere, 1 mol dendritic PAMAM CYDl lOA and 0.25 mol caprolactone monomer were stirred in an oil batch at 140 °C with vigorous stirring for about 1 to 2 hours under reflux until all caprolactone is consumed, as monitored by Gas Chromatography (GC).

Example 10: Effect of using hydrophobic modified PAMAM (CYD-llOA-25% Capa) as pH adjusters on CMIT/MIT stability in white latex paint

Compared to AMP-95 (in example 5), it has been found that hydrophobic modified PAMAM dendritic polymers CYD-l lOA-25% Capa provides similar or comparable performance, in terms of fineness, pH stability and viscosity stability after storage. Compared to unmodified PAMAM CYD-l lOA (in example 5), it has been found that hydrophobic modified PAMAM dendritic polymers CYD-110A-25%Capa provides better performance, in terms of pH stability and viscosity stability after storage. Industrial Applicability

The disclosed PAMAM neutralizing agent can be used to provide low VOC emissions / VOC-free coatings, in particular for preparing emulsion paint formulations containing biocidal substances.

The suitability of the PAMAM dendritic polymer for this role was unexpected because

PAMAM is typically used in the bio-medical field and is seldom contemplated for coatings or paint formulations. Reasons may include the relatively high cost of the PAMAM material, PAMAM is known to have limited or no solubility in any organic solvent commonly used in coatings, and there is a general prejudice in the field of coatings to favor low molecular- weight amine monomers as pH adjusters, because of the relatively higher amine content (weight for weight) compared to high molecular weight of amine polymers, which is in turn expected to provide superior pH neutralizing effects.

The present application further provides the disclosed PAMAM neutralizing agent for use in water-dispersed, emulsion polymer compositions. The emulsion polymer is stabilized in water due to the balance of steric hindrance effects and electrostatic repulsion. It has been surprisingly found that, despite the highly branched structure of PAMAM, the PAMAM polymer does not adversely affect the stability of the emulsion system.

The industrial applicability of the presently disclosed subject matter therefore lies in the unexpected finding that PAMAM or modified PAMAM polymers can serve as useful pH adjusters in coatings and paint formulations. Due to its higher molecular weight compared to conventional amine monomer, it is less volatile, less odor and provides better PH stability. Specifically, in addition to providing comparable buffering properties to conventional pH adjusters, PAMAM or modified PAMAM polymers provide a number of other useful technical effects that are not found in conventional amines. Compared to conventional linear structure polymer, dendritic polymers provide much lower viscosity at the same molecular weight, which is beneficial for the manufacture of paint. Although the disclosed dendritic amine polymer has much higher molecular weight compared to commonly used amine monomer, it can advantageously provide a similar or higher equivalent content of combined N, NH and NH₂.

Claims

1. A water based emulsion coating composition comprising, a) a neutralizing agent comprising a hyper-branched or dendritic poly(amido)amine (PAMAM) polymer having at least four amine functional groups,

b) at least one isothiazolone biocide, and

c) a binder component comprising polymer particles dispersed in an aqueous phase.

2. The composition according to claim 1, wherein said hyper-branched or dendritic PAMAM has a PKa (an acid dissociation constant) at 25°C of at least 9.0.

3. The composition according to any one of the preceding claims, wherein said PAMAM comprises from about 4 to about 128 amino functional groups.

4. The composition of any one of the preceding claims, wherein said neutralizing agent has a molecular weight of at least 500 Da.

5. The composition of any one of the preceding claims, wherein said neutralizing agent is present in said composition in an amount of from about 0.01 to about 0.5% based on the total weight of the composition.

6. The composition of any one of the preceding claims, wherein said neutralizing agent comprises, in addition to said amino functional group, one or more additional functional groups selected from the group consisting of: amidoethanol, amidoethylethanolamine, sodium carboxylate, diamines, alkanolamine, succinamic acid, trimethoxysilyl, and tris(hydroxymethyl)amidomethane groups .

7. The composition of any one of the preceding claims, wherein said one or more additional functional groups comprises at least one hydrophobic group.

8. The composition of claim 6, wherein said the neutralizing agent comprises a number ratio of said amino functional group to said additional functional group of about from about 1:9 to about 9: 1.

9. The composition of any one of the preceding claims, wherein the water-based coating composition is a polyacrylate or acrylate copolymer emulsion.

10. The composition of any one of the preceding claims, wherein the composition has a pH of 7 or greater.

11. The composition of claim 10, wherein the pH is selected from 7-12, 7-11, 7-10, 7-9 or 7-8, 8-12, 8-11, 8-10, 8-9, 9-12, 9-11, or 9-10.

12. The composition of any one of the preceding claims, wherein the biocide comprises 5- chloro-2-methyl-4-isothiazolin-3-one (CMIT).

13. The composition of any one of the preceding claims, wherein the composition comprises a biocide mixture of 5-chloro-2-methyl-4-isothiazolin-3-one (CMIT) and 2- methyl-4-isothiazolin-3-one (MIT).

14. The composition of claim 3, wherein at least 50% of the functional groups are -N¾ groups.

15. A method of neutralizing a water based emulsion coating composition comprising at least one isothiazolone biocide, the method comprising adding to said coating composition, a dendritic or hyperbranched PAMAM having at least four amine functional group, wherein said dendritic or hyperbranched PAMAM is present in said composition in an amount of 0.01 to 0.5 wt. % based on the weight of the coating composition.