Anti-blocking additive for coating formulations

Abstract

An aqueous composition includes a binder; and a C4 to C15 alkyl phosphate ester having a mono-ester content of 85% by weight or more of the total alkyl phosphate ester, and a weight percentage (wt%) of the binder in a range of 0.1 to 2.0 wt%. A method includes applying an aqueous composition to a substrate, the aqueous composition including a binder and a C4 to C15 alkyl phosphate ester having a mono-ester content of 85% by weight or more of the total alkyl phosphate ester; and curing the aqueous composition, thereby forming a cured coating.

Description

Technical Field

[0001] The implementation plan relates to anti-blocking additives for coating formulations, their preparation methods, and their applications. Background Technology

[0002] Paint and coating adhesion refers to the undesirable adhesion that occurs when two painted surfaces are pressed together. While this problem is not prominent in architectural wall paint due to the low likelihood of adhesion, it is a real issue for windows and doors, as the painted surfaces may stick together when the newly painted window or door is closed. When the window or door is later opened, the adhesion may expose bare patches of the substrate. Another area where adhesion problems exist is printing inks, such as packaging inks. When printed packaging is stacked face-to-face, the surfaces may stick together, causing the coating to peel off when separated.

[0003] As paint and ink formulations transition from solvent-based and high-VOC waterborne coatings to low-VOC or even zero-VOC coatings, adhesion problems in waterborne coatings are increasing. During this transition, the use of co-solvents and coalescing agents that generate VOCs has been reduced or eliminated. To help polymer binders (primarily acrylic latex emulsions) coalesce into a uniform film at or below room temperature, relatively soft (low T) binders are typically used. g The latex and / or low-VOC (high-boiling-point) coalescing agents are used. However, one drawback is that these components can create a sticky coating, leading to adhesion problems. Other issues associated with low-VOC or zero-VOC waterborne coatings include high surface tension, poor substrate wetting, and blistering.

[0004] Various chemicals have been used as anti-blocking additives in paint and ink formulations, including perfluorinated alkyl substances (PFAS), such as fluorinated surfactants, siloxanes, and waxes. While fluorinated surfactants provide effective anti-blocking properties, these chemicals can have significant negative impacts on the environment and human health, and are subject to increasing regulatory scrutiny. Siloxanes and waxes are often proposed as alternatives to fluorinated surfactants, but these additives tend to be less effective at preventing caking at high temperatures and / or may negatively affect the gloss of the coating. Summary of the Invention

[0005] In one aspect, the embodiments disclosed herein relate to an aqueous composition comprising a binder; and a C4 to C15 alkyl phosphate, wherein the monoester content of the C4 to C15 alkyl phosphate is 85% by weight or more of the total alkyl phosphate and in the range of 0.1% by weight to 2.0% by weight of the binder.

[0006] In another aspect, the embodiments relate to a method comprising applying an aqueous composition to a substrate, the aqueous composition comprising a binder and C4 to C15 alkyl phosphates, the monoester content of the C4 to C15 alkyl phosphates being 85% by weight or more of the total alkyl phosphates; and curing the aqueous composition to form a cured coating. Detailed Implementation

[0007] The embodiments relate to anti-blocking additives (such as those used in the formulation of coatings) for use in water-based compositions, methods for preparing water-based compositions, and applications utilizing them. Anti-blocking additives include alkyl phosphates having a high concentration of monoesters (e.g., >85% by weight of total alkyl phosphates), which exhibit high water solubility and reduced phase separation in aqueous solutions. Water-based coating compositions can also be formulated to produce cured coatings on a variety of substrates.

[0008] In coating applications, alkyl phosphates containing high concentrations of alkyl phosphate diesters (e.g., >15% by weight) are more hydrophobic and have lower surface activity than their corresponding alkyl phosphate monoesters. This results in lower water solubility of antiblocking additives (leading to phase separation and turbidity in aqueous solutions) and slower migration to the interface. Antiblocking additives with high concentrations of alkyl phosphate monoesters (and monoester blends) were prepared by synthesis and separation-based methods. Waterborne compositions and coating compositions with good antiblocking properties, low foaming, good color acceptance, and improved gloss properties were prepared using these antiblocking additives.

[0009] In some cases, the aqueous compositions disclosed herein can be formulated as coating compositions, coatings, or coated articles for use in architectural, industrial, and wood coatings for indoor and outdoor applications. The aqueous compositions disclosed herein may comprise coating formulations containing water, pigments, binders, anti-blocking additives, and other functional additives such as surfactants and dispersants. As a general guideline, aqueous compositions formulated for coatings may contain the following components in amounts:

[0010]

[0011] The waterborne coating compositions disclosed herein may have a pigment volume concentration percentage (PVC%) ranging from 0% to 80% or from 0.1% to 70% by weight. The terms "pigment volume concentration percentage" or "PVC%" refer to the amount calculated by the following formula: PVC% = (volume of pigment plus any fillers and extenders (if used)) divided by the total dry volume of the paint * 100

[0012] The types of pigments suitable for formulating water-based compositions are not particularly limited and can be selected from inorganic pigments, including one or more metal oxides such as titanium dioxide, iron oxide, zinc oxide, etc. Fillers may also be added, which may include calcium carbonate, clay, talc, mica, etc.

[0013] The aqueous compositions disclosed herein may comprise binder solids in the form of an aqueous dispersion (i.e., latex) of polymer and / or copolymer particles. The types of binders suitable for use in this invention are not particularly limited and may include homopolymers and / or copolymers, as well as blends of polymer systems. The binder solids may be prepared from polymer systems including acrylic acid, styrene-acrylic acid, vinyl ester-acrylic acid, vinyl ester-ethylene, silicone, polyurethane, vinylidene halide, and other vinylidene polymers. Other polymer types may include epoxy resins, polyurethanes, polyamides, polyimides, halogenated polymers, polysiloxanes, polyesters, alkyd resins, polyolefins, (meth)acrylic resins, combinations thereof, etc.

[0014] Examples of binder solids include polymers and copolymers prepared from monomers such as acrylic acid, methacrylic acid, acrylates and methacrylates such as methyl acrylate, ethyl acrylate, butyl acrylate, tert-butyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, decyl acrylate, lauryl acrylate, isodecyl methacrylate, lauryl methacrylate and butyl methacrylate; substituted acrylates and methacrylates such as hydroxyethyl acrylate, perfluorooctyl acrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate and hydroxyethyl methacrylate. Suitable polymers can also be prepared from monomers including vinyl halides such as vinyl chloride, vinylidene chloride, and chloroprene; maleic anhydride; vinyl esters such as vinyl acetate and vinyl butyrate; vinyl pyrrolidone; conjugated dienes such as butadiene and isoprene; vinyl aromatic compounds such as styrene and divinylbenzene; vinyl monomers such as ethylene; acrylonitrile and methacrylonitrile; acrylamide, methacrylamide, and N-hydroxymethylacrylamide; and monocarboxylic acid vinyl esters having up to 10 carbon atoms. Aqueous dispersions and their derived coating compositions may comprise one or more binder compositions such as acrylic latex, vinyl acrylic latex, styrene acrylic latex, vinyl acetate vinyl latex, polyurethane dispersions, alkyd resin dispersions, epoxy resin dispersions, polyolefin dispersions, and combinations thereof.

[0015] The aqueous composition may contain binder solids ranging from 5% to 75% by weight or from 10% to 40% by weight, in weight percentages (wt%).

[0016] Aqueous compositions may contain one or more alkyl phosphate anti-blocking additives, including organophosphates resulting from the esterification of phosphoric acid with one or more equivalents of straight-chain or branched alkyl alcohols. Alkyl phosphates may include monoesters of C4 to C15 alkyl phosphates. As used herein, "monoester alkyl phosphate" means an alkyl phosphate in which the monoester content constitutes 85% or more, 90% or more, or substantially all of the total alkyl phosphate content by weight (wt%). In some cases, the anti-blocking additive may contain a mixture of two or more C4 to C15 alkyl phosphate monoesters, wherein the molar ratio of the two monoesters is in the range of 4:1 to 1:4. In one example, the anti-blocking additive may contain an approximately 1:1 ratio of n-octyl phosphate to n-decyl phosphate. Alkyl phosphate anti-blocking additives may be added to the aqueous composition in acid form or as potassium, sodium, or amine salts.

[0017] Methods for synthesizing monoester-rich alkyl phosphates may include reacting a straight-chain or branched C4 to C15 alcohol with an excess of a phosphorylating agent (such as phosphorus pentoxide, phosphoric acid, polyphosphoric acid, etc.). To increase the monoester to diester ratio, the reactivity of the phosphorylating agent can be controlled by any suitable method, including the concentration relative to the alkyl alcohol, temperature, or type of phosphorylating agent (e.g., polyphosphoric acid). Monoester alkyl phosphates can also be obtained by physically separating a mixture of monoesters and diesters into multiple fractions.

[0018] The aqueous compositions disclosed herein may contain one or more alkyl phosphate monoester anti-blocking additives in a weight percentage (wt%) ranging from 0.05 wt% to 2.5 wt% or from 0.1 wt% to 2.0 wt% based on the weight of the binder solids.

[0019] The disclosed aqueous compositions may contain a number of additional materials, including solvents; pigments, such as unencapsulated or partially or fully encapsulated TiO2; fillers; defoamers; surfactants; dispersants; thickeners; coalescing agents; colorants; preservatives; flow agents; leveling agents; neutralizers; additional antiblocking agents, etc.

[0020] Although the formulation components have been disclosed individually, it is envisioned that any of the above concentration ranges and nested subranges therein may be used to include, exclude or combine component elements in any manner or sub-combination.

[0021] The preparation of the aqueous coating compositions disclosed herein is not particularly limited and well-known techniques can be used. The preparation technique for the aqueous compositions for coating applications may include two general steps: i) pigment dispersion (so-called “grinding”) and ii) thinning. During the grinding step, pigment clusters are ground to obtain a fine-particle pigment dispersion. This operation can be carried out in a high-speed disperser, bead mill, or similar equipment until the desired particle size (e.g., 0.3 μm to 5 μm as measured by laser diffraction) is achieved. During the thinning step, the pigment dispersion is combined with an aqueous dispersion of binder and surfactant, as well as any other optional components mentioned above, using suitable methods (e.g., static mixing, dynamic mixing, dynamic and static mixing, high-speed mixing, low-pressure mixing, overhead mixing with an impeller or paint mixer, impact mixing, etc.). The final viscosity of the resulting composition can be adjusted by adding additional water or a rheology modifier. The specific order of addition and selection of individual components can be readily determined through routine experiments.

[0022] The process of using an aqueous composition may include applying the aqueous composition (e.g., as a coating composition) to a substrate by any suitable method (such as brushing, dipping, rolling, spraying, etc.). In some cases, spraying techniques include air atomization spraying, air spraying, airless spraying, high-volume low-pressure spraying, and electrostatic spraying, such as electrostatic clock application, including manual or automated methods. After coating the substrate with the aqueous composition, the coating composition may be dried (or dried by a suitable manner) to form a cured coating at a suitable temperature such as room temperature (20°C to 25°C) or high temperature (>25°C to 60°C).

[0023] Example

[0024] The following examples are provided to illustrate embodiments of the invention, but are not intended to limit the scope of the invention. Table 2 provides the materials used in the following examples.

[0025]

[0026] Example 1: Preparation of monoester alkyl phosphate samples

[0027] An anti-blocking additive containing n-octyl phosphate (IE-AP8) with a high monoester concentration was prepared by loading octanol (1.0 mol equivalent) into a three-necked reaction vessel (fixed within a heating mantle and equipped with a condenser and a top stirrer with an adapter). Polyphosphoric acid (PPA, 1.2 to 1.6 mol phosphorus equivalent) was loaded into a feeding funnel and placed on the remaining neck of the reaction vessel. The system was purged with nitrogen and heated to 50 to 60 °C. PPA was added over 1 to 2 hours to control the exothermic reaction, and the mixture gradually thickened and changed from clear to pale yellow-orange with each addition. After the addition was complete, the reaction mixture was heated at 90 to 95 °C for several hours. The product mixture was cooled to room temperature, then transferred to a storage container and sampled further. Samples of n-hexyl phosphate (IE-AP6) and a mixture of n-octyl phosphate / n-decyl phosphate (50:50 ratio) (IE-AP810) were prepared using the same method.

[0028] To prepare the alkyl phosphate product in potassium salt form, the alkyl phosphate sample was neutralized with 45% by weight of KOH, added slowly with stirring to minimize the heat released during the neutralization reaction. Unless otherwise specified, deionized water was added to adjust the active ingredient content (based on alkyl phosphate) to 30% by weight. The final pH was adjusted to 7 to 8.

[0029] For samples IE-AP8F1 and CE-AP8F2 prepared by separation, monoester and diester alkyl phosphate fractions were generated from a commercially available mixture using a solid-phase adsorbent. Separation was performed as follows: 4 g of STEPCOTE W-877 (CE-AP8); 25 g of octadecyl-functionalized silica gel, 22% to 24% carbon loading, Sigma-Aldrich #553506; and 100 g of 85:15 water:acetonitrile (solvent A) were mixed in an 8 oz container. The container was then shaken and placed on a horizontal roller for 2 hours. The container was removed from the roller and allowed to stand. To extract the monoester alkyl phosphate, the liquid phase was collected by pipette and filtered under vacuum through 0.45 μm filter paper. Another equal part of solvent A was added, and the container was rolled again for 2 hours. The removal of the liquid phase and application of the solvent fraction were repeated, and the three liquid fractions were combined into the monoester alkyl phosphate fraction "IE-AP8F1". Acetonitrile was used as a solvent to repeat the extraction process to collect the diester alkyl phosphate fraction "CE-AP8F2".

[0030] The ratio of monoesters to diesters in mixtures of alkyl phosphate products was determined using nuclear magnetic resonance (NMR) spectroscopy. NMR samples were prepared by dissolving 100 to 200 mg of material in 600 to 800 μL of dimethyl sulfoxide-d6 (DMSO-d6) and then transferring the solution to a 5 mm NMR tube. NMR spectra were obtained on a Bruker Advance-III 400 spectrometer (FT 400 MHz, 1H; 101 MHz, 13C; 162 MHz, 31P). Quantification of 31P was achieved using a zgig30 pulse sequence with a relaxation delay of 38 seconds. The results are shown in Table 3.

[0031]

[0032] Example 2: Solubilizing properties

[0033] In this embodiment, an aqueous composition containing alkyl phosphate was prepared, and its solubilizing properties were characterized. The alkyl phosphate was neutralized with KOH and diluted to 30 wt% (based on the active ingredient content), and its appearance (including phase separation), foaming properties, and turbidity (cloudiness) were analyzed. To quantify turbidity, 20 mL of the 30 wt% alkyl phosphate solution was measured three times using a Hach ratio turbidimeter. The turbidimeter's measurable range was 0 to 200. For samples outside this range, the turbidity was recorded as >200. The results are shown in Table 4.

[0034]

[0035] The physical appearance of formulations containing comparative alkyl phosphates and alkyl phosphates of the present invention differs significantly. For hexanol alkyl phosphates (IE-AP6 and CE-AP6), both samples were clear and transparent at 30% active ingredient content. However, for CE-AP8 and CE-AP810, which contain a higher proportion of diester, the comparative samples showed severe turbidity and phase separation, while the corresponding examples of the present invention (IE-AP8 and IE-AP810) were clear and transparent. The comparative examples contain high levels of diester, which is more hydrophobic and less water-soluble than its monoester counterparts, which may increase turbidity and drive phase separation.

[0036] Example 3: Bubble Characterization

[0037] Foaming is an important aspect of surfactant design and can affect the compositions used in manufacturing and application processes. For example, applications such as coatings and inks often utilize low-foaming surfactants. For foam testing, the surfactant was diluted to 0.1% by weight in DI water. Foam testing was performed using a DFA100 dynamic foam analyzer equipped with an air bubbling module manufactured by Kruss GmbH. Specifically, 45 mL of surfactant solution was loaded into the sample column for foam testing. The test was conducted at room temperature (25°C). At the start of the test, air bubbling was performed at a flow rate of 200 mL / min for 180 seconds (IE-AP6 and CE-AP6) or 30 seconds to observe foam generation. After stopping air bubbling, foam decay was recorded for 180 seconds or until the foam completely collapsed. The results are shown in Table 5.

[0038]

[0039] Example 4: Coating Formulation

[0040] In this embodiment, the effect of the monoester:diester ratio (effective monoester weight %) of alkyl phosphates on anti-adhesion was analyzed for the high monoester fraction (IE-AP8F1) and low monoester fraction (CE-AP8F2) of commercially available n-octyl phosphate. Capstone FS-63 (CE-FS) (which is a comparative sample for anti-adhesion performance) was used as a positive control, while the sample without anti-adhesion additives was used as a negative control. Coating formulations were prepared using the sample with anti-adhesion additives as part of the thinner at concentrations of 0 wt%, 0.1 wt%, 0.4 wt%, and 0.8 wt% of binder solids. Sample formulations are shown in Table 6.

[0041]

[0042] Anti-blocking properties were tested according to ASTM D4946-89. Paint was applied using a 3-milk bird applicator. The film was dried for 1 day and 7 days, then cut into 1.5" × 1.5" squares and placed face-to-face. An 8-gauge rubber stopper and a 1kg weight were placed on the squares and kept in contact and under pressure for a specified time under specified conditions. The squares were then pulled apart and evaluated under the following conditions: (1) 30 minutes at room temperature; (2) 30 minutes at 120℉ (50℃); and (3) 16 hours at room temperature. Qualitative anti-blocking properties were graded according to Table 7.

[0043]

[0044] The adhesion test results in Table 8 show that the low monoester fraction exhibited low efficacy in anti-adhesion, while the high monoester fraction performed comparably to fluorinated surfactants. At the same usage level, organic surfactants are generally less effective than fluorinated surfactants, and the tested samples contained 0.1% of the active ingredient of a fluorinated surfactant (based on dry binder dosage level) and 0.8% of the active ingredient of an organic surfactant.

[0045]

[0046] The adhesion of the synthetic and comparative samples was also measured, as shown in Tables 9 and 10. At the same dosage of 0.8%, the samples of the present invention and the comparative samples did not show any difference in anti-adhesion performance. However, the samples of the present invention, especially octyl phosphate (IE-AP8), showed the same level of anti-adhesion even when the dosage level was reduced from 0.8% to 0.4%.

[0047]

[0048]

[0049] Anti-sticking properties were also replicated for n-octyl phosphate samples IE-AP8 and CE-AP8 using a stepwise study. In this example, coatings were prepared at three dosage levels of 0.2 wt%, 0.4 wt%, and 0.8 wt% for each anti-sticking additive, and anti-sticking properties were tested at 50°C on day 1 and day 7. The IE-AP8 sample of the present invention maintained robust anti-sticking properties even at 0.2 wt%, while the comparative formulation CE-AP8 showed a decrease in anti-sticking properties as the concentration of the anti-sticking additive decreased. The results are shown in Table 11.

[0050]

[0051] Example 5: Gloss properties of coating formulations

[0052] To characterize the gloss of the cured coating, paint films were prepared on Leneta WB test cards using a 3-milbird applicator and dried for 24 hours. Gloss was measured using a BYK-Gardner 4563 miniature triangular gloss meter. The results are shown in Tables 12 and 13.

[0053]

[0054]

[0055] As shown in Tables 12 and 13, increased concentrations of alkyl phosphate monoesters exhibited a significant effect on paint gloss. While a decrease in gloss was observed with the use of fluorinated surfactants (CE-FS), alkyl phosphates generally have a positive effect on gloss. In particular, the samples of this invention containing a high proportion of monoesters all showed significantly higher gloss than their comparative counterparts, exceeding it by 2.3 to 4.5 gloss units at the same dosage of 0.8% by weight.

[0056] While the foregoing relates to exemplary embodiments, other and additional embodiments may be devised without departing from the basic scope of the invention, the scope of which is defined by the appended claims.

Claims

1. An aqueous composition comprising: Adhesives; and C4 to C15 alkyl phosphates, wherein the monoester content of the C4 to C15 alkyl phosphates is 85% or more by weight of the total alkyl phosphates and the monoester content of the binder is in the range of 0.1% to 2.0% by weight.

2. The composition according to claim 1, wherein the binder is selected from the group consisting of acrylic acid, styrene-acrylic acid, vinyl ester-acrylic acid, and vinyl ester-ethylene polymers.

3. The composition according to claim 1, wherein the C4 to C15 alkyl phosphate comprises 90% by weight or more of a monoester content.

4. The composition according to claim 1, wherein the C4 to C15 alkyl phosphate is added to the aqueous composition in acid form or in the form of potassium salt, sodium salt, or amine salt.

5. The composition according to claim 1, wherein the anti-adhesion additive has a ratio of n-octyl phosphate to n-decyl phosphate in the range of 4:1 to 1:

4.

6. The composition according to claim 1, wherein the anti-adhesion additive comprises n-octyl phosphate.

7. A method, the method comprising: An aqueous composition is applied to a substrate, the aqueous composition comprising: Adhesive, and C4 to C15 alkyl phosphates, wherein the monoester content of the C4 to C15 alkyl phosphates accounts for 85% or more of the total alkyl phosphates by weight (wt%). The aqueous composition is cured to form a cured coating.

8. The method of claim 7, wherein the C4 to C15 alkyl phosphate is present in a weight percentage ranging from 0.1 to 1.0% by weight of the adhesive.

9. The method of claim 7, wherein the anti-blocking rating of the cured coating is in the range of 5 to 10 according to ASTM D4946-89.

10. The method of claim 7, wherein the anti-blocking rating is improved by at least 2 units relative to a comparative composition without the anti-blocking additive.

11. The method of claim 7, wherein, relative to a comparative composition without the anti-blocking additive, the cured coating exhibits an increase in gloss of at least 2 units at 60°, as measured by a gloss meter.

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