Emulsifier composition for aqueous alkyd resin composition

Abstract

The present invention relates to an emulsifier composition comprising at least one anionic emulsifier and at least one nonionic emulsifier. The invention also relates to the use of the emulsifier composition for producing an aqueous alkyd resin composition, to an aqueous alkyd resin composition comprising the emulsifier composition according to the invention and to a method for producing the aqueous alkyd resin composition.

Description

Technical Field

[0001] The present invention relates to an emulsifier composition comprising at least one anionic emulsifier and at least one nonionic emulsifier. The present invention also relates to the use of the emulsifier composition for producing an aqueous alkyd resin composition, an aqueous alkyd resin composition comprising the emulsifier composition of the present invention, and a method for producing the aqueous alkyd resin composition. Background Art

[0002] In the past few decades, coating compositions (also known as paints) have undergone significant changes. In some parts of the world, this change continues. To reduce the amount of organic solvents in coatings, the use of aqueous coating compositions has increased significantly. Alkyd resin coating compositions are well known in the coating industry for their various properties, such as the ability to form hard, glossy, and durable coatings on various surfaces. Historically, alkyd resin coatings have been solvent-based, drying by solvent evaporation and curing by oxidation to form a firm coating. However, alkyd resin coatings are shifting from solvent-based to aqueous. Aqueous alkyd resin coatings combine the advantages of both: the advantages of alkyd resins and the eco-friendliness of aqueous systems.

[0003] However, aqueous alkyd resin coatings also face some challenges. For example, compared to solvent-based coatings, aqueous alkyd resin coatings have a longer drying time. However, in terms of fluidity, leveling, and gloss characteristics, the application effects of aqueous alkyd resin coatings are comparable. It may be difficult to form a firm coating film using aqueous alkyd resin coatings. Appropriate formulation and curing conditions are crucial for ensuring good coating performance. Maintaining a stable viscosity during storage and application is both important and challenging. It is very difficult to find an emulsifier to control the appropriate alkyd resin droplet size, but it is the basis for ensuring the stability of aqueous alkyd resin emulsions. Aqueous alkyd resins generally need to strike a balance between performance (such as hardness, gloss, and durability) and environmental factors. Finding the right compromise can be challenging. Summary of the Invention

[0004] The applicant has found that emulsifiers play a key role in converting alkyd resins into aqueous emulsions, and the applicant has surprisingly discovered a specific emulsifier composition that has the potential to form an aqueous alkyd resin emulsion with an alkyd resin droplet size ensuring long-term stability. This discovery enables formulators to achieve the transition from solvent-based alkyd resin emulsions to aqueous alkyd resin emulsions, and thus contribute to more sustainable and environmentally friendly coatings.

[0005] Accordingly, in a first aspect, the present invention relates to an emulsifier composition for an aqueous alkyd resin composition, wherein the emulsifier composition comprises: at least one anionic emulsifier (i) which is a fatty acid having 16 - 24 carbon atoms and having at least one unsaturation; and at least one nonionic emulsifier (ii) having an HLB (hydrophilic - lipophilic balance) value of 11 - 18.

[0006] Surprisingly, the applicant has indeed found that such an emulsifier composition is capable of forming an aqueous alkyd resin emulsion having long - term stability.

[0007] The coatings industry wishes to produce coating compositions using bio - renewable sources. Nowadays, many components in alkyd resins can be partially or fully derived from bio - renewable materials. Examples that can be mentioned are Voxtar TM , Evyron TM and Neeture TM , tetraols, triols and diols from Perstorp AB and short - oil and long - oil polyol esters for producing alkyd resins. Emulsifiers represent a significant proportion in aqueous coating compositions, and thus it is desirable to formulate emulsifiers from bio - renewable materials as much as possible. The emulsifier composition of the present invention can perfectly meet this requirement, wherein the anionic emulsifier (i) is preferably fully bio - renewable, and the nonionic emulsifier (ii) is advantageously obtained from bio - renewable sources.

[0008] The emulsifier composition of the present invention is also preferably not formed from any amine - terminated emulsifiers, which well addresses the desire in the coatings industry to avoid commonly used amine - terminated emulsifiers, since amine - terminated emulsifiers are associated with issues such as environmental, health and visual properties.

[0009] In another aspect, the present invention also relates to the use of the emulsifier composition of the first aspect for producing an aqueous alkyd resin composition. By applying the emulsifier composition of the present invention, a stable aqueous alkyd resin composition can be produced.

[0010] In another aspect, the present invention also relates to an aqueous alkyd resin composition, wherein the alkyd resin composition comprises: a) an alkyd resin having an acid value of 2 - 20 mg KOH / g; b) the emulsifier composition of the first aspect of the present invention; c) water; and d) a neutralizing agent.

[0011] In yet another aspect, the present invention also relates to a method for producing the aqueous alkyd resin composition of the present invention, comprising the steps of: (A) mixing the alkyd resin with the emulsifier composition, (B) adding the neutralizing agent to the mixture obtained in step A) with continuous stirring until the pH value is 5 - 10, and then (C) adding water with continuous stirring.

[0012] The emulsifier composition of the present invention facilitates the transition of alkyd resins to aqueous emulsions, thus enabling sustainable and long-term stable aqueous alkyd resin coatings.

[0013] The advantages of these other aspects of the present invention have been elaborated for the emulsifier composition of the first aspect of the present invention and will not be repeated here. Detailed Description

[0014] In a first aspect, the present invention relates to an emulsifier composition for an aqueous alkyd resin composition, wherein the emulsifier composition comprises:

[0015] i. at least one anionic emulsifier which is a fatty acid having 16 - 24 carbon atoms and having at least one degree of unsaturation, and

[0016] ii. at least one nonionic emulsifier having an HLB (hydrophilic - lipophilic balance) value of 11 - 18.

[0017] Surprisingly, the applicant has indeed found that such an emulsifier composition is capable of forming an aqueous alkyd resin emulsion having long - term stability.

[0018] In this specification and the claims that follow, unless otherwise indicated, all numbers expressing quantities, parameters, percentages, etc. are to be understood as being preceded in all instances by the term "about". As used herein, the term "about" is understood by those of ordinary skill in the art and varies somewhat depending on the context in which it is used. As used herein, when the term "about" refers to a measurable value (such as an amount, a length of time, etc.), it means a variation of ±20% or ±10% from the specified value, including ±5%, ±1%, and ±0.1%, since such variations are appropriate for carrying out the disclosed methods. Additionally, all ranges of numbers include all possible combinations of the maximum and minimum values and include all possible intermediate ranges, as well as the ranges specifically indicated below.

[0019] Unless otherwise defined, all technical and scientific terms used herein generally have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0020] As used herein, the articles "a" and "an" refer to one or more than one (i.e., at least one) grammatical object. For example, "a fatty acid" refers to one fatty acid or more than one fatty acid.

[0021] The present invention may exhibit one or more of the following features in one or more of the above - mentioned aspects.

[0022] The emulsifier composition of the present invention comprises at least one anionic emulsifier i) (which is a fatty acid having 16 - 24 carbon atoms and having at least one unsaturation) and at least one nonionic emulsifier ii) (having an HLB (hydrophilic - lipophilic balance) value of 11 - 18). The anionic emulsifier i) preferably has at least one side - chain hydroxyl group. In another preferred embodiment of the present invention, the anionic emulsifier i) has at least one branched chain.

[0023] The anionic emulsifier i) is suitably a fatty acid selected from: palmitolinolenic acid, palmitadienoic acid, palmitoleic acid, hydroxyhexadecanoic acid, heptadecanoic acid, heptadecenoic acid, hydroxyheptadecenoic acid, stearidonic acid, oleic acid, ricinoleic acid, isoricinoleic acid, ricinelaidic acid, linoleic acid, α - linolenic acid, elaidic acid, oleic acid, agonandric acid, isocetonic acid, coriolic acid, 12 - hydroxy - 9,15 - octadecadienoic acid, nonadecenoic acid, paullinic acid, cervonic acid, cetostearic acid, hydroxypaullinic acid, heneicosenoic acid, erucic acid, cetoleic acid, eranthic acid, suberic acid, Nebraskanic acid, Wuhanic acid, and combinations thereof. The anionic emulsifier i) is more preferably selected from: palmitoleic acid, oleic acid, ricinoleic acid, and linoleic acid.

[0024] On the other hand, the anionic emulsifier i) can be a di - fatty acid, tri - fatty acid or oligomeric fatty acid.

[0025] The anionic emulsifier i) is preferably obtained from bio - renewable sources such as vegetable oils. The fatty acid composition of vegetable oils generally contains a mixture of monounsaturated fatty acids, polyunsaturated fatty acids and saturated fatty acids. Saturated fatty acids commonly present in vegetable oils are, for example, palmitic acid, stearic acid, nonadecanoic acid, arachidic acid, heneicosanoic acid, docosanoic acid, dihydroxydocosanoic acid, tricosanoic acid and tetracosanoic acid.

[0026] In the emulsifier composition of the present invention, based on the emulsifier composition, the amount of the anionic emulsifier i) is preferably 30 - 70 wt%, more preferably 40 - 60 wt%.

[0027] In a preferred embodiment of the present invention, the non-ionic emulsifier ii) is also obtained from bio-renewable sources. For example, the lipophilic part of the non-ionic emulsifier ii) is preferably selected from fatty acids having 14-20 carbon atoms which can be easily obtained from non-fossil sources. The hydrophilic part of the non-ionic emulsifier ii) suitably comes from alkoxylates, such as polyoxyethylene, oligomeric alkylene oxides, alkylphenoxyethylene or polysorbates. The hydrophilic part preferably contains 5-40 ethylene oxide (EO) units. Ethylene oxide can be easily obtained from bio-renewable sources, and other components of the hydrophilic part of the non-ionic emulsifier ii), such as ethylene glycol, alkylphenols and sorbitan anhydride, can also be obtained from bio-renewable sources to a certain extent.

[0028] On the other hand, the present invention also relates to the use of the emulsifier composition as defined in the first aspect of the present invention for the production of an aqueous alkyd resin composition.

[0029] In yet another aspect, the present invention also relates to an aqueous alkyd resin composition, wherein the alkyd resin composition comprises:

[0030] a) an alkyd resin having an acid value of 2-20 mg KOH / g,

[0031] b) the emulsifier composition of the first aspect of the present invention,

[0032] c) water, and

[0033] d) a neutralizing agent.

[0034] The droplet size of the alkyd resin a) is preferably 100-350 nm.

[0035] An alkyd resin is a polyester containing a drying oil and formed from three basic components: fatty acids, polyols and dibasic acids. Triglycerides (i.e., oils composed of 3 moles of monobasic fatty acids and 1 mole of glycerol) can replace polyols and fatty acids. The choice of polyol affects the degree of branching of the alkyd resin. Suitable polyols for forming the alkyd resin a) in the aqueous alkyd resin composition of the present invention are selected from: glycerol, ethylene glycol, propylene glycol, pentaerythritol, dipentaerythritol, trimethylolpropane and sorbitol.

[0036] The fatty acids or oils used to form the alkyd resin a) have a great influence on the curing and physical properties of the final coating film. The higher the degree of unsaturation of the fatty acids, the shorter the drying time of the coating. Alkyd resins are classified according to the percentage of fatty acids in the resin. Short-oil alkyd resins have a fatty acid content of less than 40%, medium-oil alkyd resins have a fatty acid content of 40-60%, and long-oil alkyd resins have a fatty acid content of more than 60%. Most fatty acids come from vegetable oils, among which soybean oil is the most commonly used.

[0037] The dibasic acids used for preparing alkyd resins are usually aromatic ones such as phthalic anhydride or isophthalic acid, but aliphatic dibasic acids such as succinic acid, adipic acid, azelaic acid, sebacic acid and dimer fatty acid can also be applied. The dibasic acids of the alkyd resins help to increase the elasticity of the coating film.

[0038] The amount of the emulsifier composition b) present is 2-12 wt% of the alkyd resin.

[0039] In a preferred embodiment of the present invention, the neutralizing agent d) is an alkali metal hydroxide and / or ammonium hydroxide. The alkali metal hydroxide can be suitably selected from lithium hydroxide, sodium hydroxide, potassium hydroxide and their combinations. The market price of a particular alkali metal and the required properties are decisive factors when formulating the coating properties (such as but not limited to film-forming properties and gloss). In many cases, a mixture of one or more alkali metal hydroxides and ammonia shows to be a preferred solution.

[0040] On the other hand, the present invention also relates to a production method of the aqueous alkyd resin composition described in the present invention, comprising the following steps:

[0041] A. Mix the alkyd resin with the emulsifier composition,

[0042] B. Add the neutralizing agent to the mixture obtained in step A) under continuous stirring until the pH value is 5-10, and then

[0043] C. Add water under continuous stirring.

[0044] Preferably, water is added dropwise in step C).

[0045] The method is preferably carried out at an emulsification temperature of 50-90 °C, more preferably 55-80 °C.

[0046] The present invention will be further explained below with reference to the attached examples, which should be understood as descriptive and not limiting in any way.

[0047] Examples

[0048] Example 1

[0049] 100 g of TOFA (tall oil fatty acid) long oil alkyd resin with an acid value of 9.2 mg KOH / g and a hydroxyl value of 66.3 mg KOH / g was mixed with 8 g of the emulsifier composition of the present invention, wherein the anionic emulsifier was 4.8 g and the nonionic emulsifier was 3.2 g. Then the alkyd resin-emulsifier composition was mixed for 15 minutes, and then 2.38 g of KOH was added under continuous stirring. Then 89.62 g of distilled water was added at a rate of 1.2 g / minute under continuous stirring. The emulsification temperature was 55 °C.

[0050] It was found that the alkyd resin droplets had a uniform size, between 175 - 225 nm. Then the sample was stored at 50 °C for 30 days to analyze its long-term stability. No separation of the alkyd resin emulsion was detected.

[0051] Example 2

[0052] 100 g of a sunflower fatty acid long-oil alkyd resin with an acid value of 2.8 mg KOH / g and a hydroxyl value of 54 mg KOH / g was mixed with 8 g of the emulsifier composition of the present invention, where the anionic emulsifier was 4 g and the non-ionic emulsifier was 4 g. Then the alkyd resin emulsifier composition was mixed for 15 minutes, and then 2.38 g of KOH was added under continuous stirring. Then 90 g of distilled water was added at a rate of 1.2 g / minute under continuous stirring. The emulsification temperature was 80 °C.

[0053] It was found that the alkyd resin droplets had a uniform size, with an average size of 140 nm. Then the sample was stored at 50 °C for 30 days to analyze its long-term stability. No separation of the alkyd resin emulsion was detected.

[0054] Example 3

[0055] 100 g of a soybean fatty acid long-oil alkyd resin with an acid value of 16.8 mg KOH / g and a hydroxyl value of 74 mg KOH / g was mixed with 8 g of the emulsifier composition of the present invention, where the anionic emulsifier was 4 g and the non-ionic emulsifier was 4 g. Then the alkyd resin emulsifier composition was mixed for 15 minutes, and then 2.38 g of KOH was added under continuous stirring. Then 91 g of distilled water was added at a rate of 1.2 g / minute under continuous stirring. The emulsification temperature was 80 °C.

[0056] It was found that the alkyd resin droplets had a uniform size, with an average size of 220 nm. Then the sample was stored at 50 °C for 30 days to analyze its long-term stability. No separation of the alkyd resin emulsion was detected.

[0057] Example 4

[0058] 100 g of a soybean fatty acid short-oil alkyd resin with an acid value of 9.3 mg KOH / g and a hydroxyl value of 57.4 mg KOH / g was mixed with 8 g of the emulsifier composition of the present invention, where the anionic emulsifier was 4 g and the non-ionic emulsifier was 4 g. Then the alkyd resin emulsifier composition was mixed for 15 minutes, and then 2.38 g of KOH was added under continuous stirring. Then 88 g of distilled water was added at a rate of 0.9 g / minute under continuous stirring. The emulsification temperature was 65 °C.

[0059] It was found that the alkyd resin droplets had a uniform size, with an average size of 300 nm. The sample was then stored at 50 °C for 30 days to analyze its long-term stability. No separation of the alkyd resin emulsion was detected.

Claims

1. An emulsifier composition for an aqueous alkyd resin composition, wherein the emulsifier composition comprises: i. at least one anionic emulsifier which is a fatty acid having 16 - 24 carbon atoms and having at least one degree of unsaturation, and ii. at least one nonionic emulsifier having an HLB (hydrophilic - lipophilic balance) value of 11 - 18.

2. The emulsifier composition according to claim 1, wherein the anionic emulsifier i) has at least one side - chain hydroxyl group.

3. The emulsifier composition according to claim 1 or 2, wherein the anionic emulsifier i) has at least one branched chain.

4. The emulsifier composition according to any one of claims 1 - 3, wherein the amount of the anionic emulsifier i) is 30 - 70 wt% of the emulsifier composition.

5. The emulsifier composition according to claim 4, wherein the amount of the anionic emulsifier i) is 40 - 60 wt% of the emulsifier composition.

6. Use of the emulsifier composition according to any one of claims 1 - 5 for producing an aqueous alkyd resin composition.

7. An aqueous alkyd resin composition, wherein the alkyd resin composition comprises: a) an alkyd resin having an acid value of 2 - 20 mg KOH / g, b) the emulsifier composition according to any one of claims 1 - 5, c) water, and d) a neutralizing agent.

8. The aqueous alkyd resin composition according to claim 7, wherein the droplet particle size of the alkyd resin a) is 100 - 350 nm.

9. The aqueous alkyd resin composition according to claim 7 or 8, wherein the amount of the emulsifier composition b) is 2 - 12 wt% of the alkyd resin.

10. The aqueous alkyd resin composition according to any one of claims 7 - 9, wherein the neutralizing agent d) is an alkali metal hydroxide and / or ammonium hydroxide.

11. The aqueous alkyd resin composition according to claim 10, wherein the alkali metal hydroxide is selected from lithium hydroxide, sodium hydroxide, potassium hydroxide and combinations thereof.

12. A method for producing the aqueous alkyd resin composition according to any one of claims 7 - 11, comprising the following steps: A. Mixing the alkyd resin with the emulsifier composition, B. Adding a neutralizing agent to the mixture obtained in step A) with continuous stirring until the pH value is 5 - 10, and then C. Adding water with continuous stirring.

13. The method according to claim 12, wherein in step C) the water is added dropwise.