Wood product protective coating and preparation method thereof

Abstract

The present invention is a coating for protecting wood products containing approximately 10% glass beads. Applicants have discovered that optimal performance is achieved when the glass beads are present in the coating at a concentration between 5% and 10% by weight. A polyether-based dispersant and a synthetic layered silicate are first combined to create a shelf-stable paste, which is then mixed with a binder to form the coating. Preferably, the glass bead concentration in the paste ranges from 60% to 80% by weight, the polyether-based dispersant concentration ranges from 20% to 25% by weight, and the synthetic layered silicate concentration ranges from 1% to 3% by weight.

Description

Background of the Invention

[0001] Field of the Invention

[0002] The present invention relates to the field of coatings, in particular to the field of wood product protective coatings.

[0003] Related technical background

[0004] Wood products, especially furniture and paneling, are often coated to provide resistance to wear, scratches, and stains. These coatings are designed to minimize discoloration and provide a generally smooth feel. Typical coatings include adhesives, waxes, matting agents, defoamers, and solvents.

[0005] Some wood coatings use plastic particles as fillers. Because the plastic particles have a similar density to the rest of the coating, they remain suspended. However, the abrasion, scratch, and stain resistance of these coatings are not as strong as expected. There is a need for improved wood coatings that offer enhanced abrasion, scratch, and stain resistance.

[0006] There has been interest in using glass beads, also known as solid glass microspheres, in wood coatings. These beads offer the potential to provide abrasion and scratch resistance. However, because they are much denser than the rest of the coating, they cannot remain in solution over a normal shelf life. Instead, they separate from the solution and settle to the bottom of the container. To successfully use glass beads in wood coatings, they must remain in solution over the normal shelf life.

[0007] Industry desires to use glass beads in wood coatings, but to date such coatings have not been successfully implemented.

[0008] The present invention is directed to solving one or more of the above problems. Summary of the Invention

[0009] There is considerable interest in providing glass beads in wood coatings. However, due to the density difference between the glass beads and the rest of the coating ingredients, the beads tend to sink and separate, settling to the bottom of the container, making the composition unsuitable for sale or use. Therefore, in order to utilize glass beads in wood coatings, it is necessary to improve the suspension stability of the coating formulation.

[0010] The present inventors have found that glass beads and a binder can form a wood coating. Preferably, the coating comprises between 5 wt% and 15 wt% glass beads, and more preferably comprises 10 wt% glass beads.

[0011] The present inventors have also discovered that a shaped finished product can be formed from a wood product and a coating formed from glass beads and a binder.

[0012] The present inventors have also discovered a slurry useful for producing wood coatings, the slurry comprising glass beads, a polyether-based dispersant, and a synthetic layered silicate. Preferably, the slurry comprises 60-80 wt% glass beads, 20-25 wt% polyether-based dispersant, and 1-3 wt% synthetic layered silicate. The slurry may further comprise an anti-foaming agent.

[0013] The present inventors have also discovered a method for forming a wood coating wherein a paste is formed from glass beads, a polyether-based dispersant, and a synthetic layered silicate, and the paste is mixed with a binder to form the coating.

[0014] Applicants have discovered that to maintain storage stability of the coating, the glass beads should be pre-dispersed in a paste or slurry so that the beads remain in solution and do not settle. In a preferred method of the present invention, a paste is formed containing the glass beads, a polyether-based dispersant, and a synthetic layered silicate. Preferably, the glass bead concentration ranges from 60 wt% to 80 wt%, the polyether-based dispersant concentration ranges from 20 wt% to 25 wt%, and the synthetic layered silicate concentration ranges from 1 wt% to 3 wt%. Applicants have discovered that when the paste is combined with a binder to form the coating, the paste prevents the glass beads from settling out of solution.

[0015] The paste can be mixed with a suitable binder to form a coating. The relative proportions of paste and binder should be calculated to provide a resulting coating having approximately 10 wt% glass beads. Applicants have found that such a coating provides a desirable level of scratch and stain resistance.

[0016] Applicants have discovered that providing between 5 wt% and 15 wt% of glass beads in a coating composition provides the coating with optimal scratch, abrasion, and stain resistance. Applicants have discovered that when the glass beads are below 5 wt%, there is little improvement in scratch, abrasion, and stain resistance. When the glass beads exceed 15 wt%, there is no further change in performance.

[0017] Further features, aspects, objects, advantages and possible applications of the present invention will become more apparent from a study of the exemplary embodiments and examples described below, taken in conjunction with the accompanying drawings and appended claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The patent or application file contains at least one drawing in color. Copies of this patent or patent application publication with color drawing(s) will be provided by the Office upon request and payment of the necessary fee.

[0019] The above and other objects, aspects, features, advantages and possible applications of the present invention will become more apparent from the following more detailed description presented in conjunction with the following drawings, in which:

[0020] Figure 1The bar graphs show the effect of gloss reduction @ 60° and gloss reduction @ 85° when spherical glass beads are added to wood coatings.

[0021] Figure 2 The bar graph shows the effect on clarity when spherical glass beads are added to wood coatings.

[0022] Figure 3 The graph shows the effect of adding spherical glass beads to wood coatings on the shear viscosity of the coating.

[0023] Figure 4 The graph shows the matting efficiency of various glass bead pastes on a coating card.

[0024] Figure 5 The graph shows the ΔE transparency of various glass bead pastes on the coating card.

[0025] Figure 6 The graph shows the matting efficiency of various glass bead pastes on wood products.

[0026] Figure 7 The graph shows the ΔE transparency of various glass bead pastes on the coating card.

[0027] Figure 8 The figures show the colors of various glass bead pastes on the paint card (a, b).

[0028] Figure 9 The figures show the colors of various glass bead pastes on the paint card (a, b).

[0029] Figure 10 The graph shows the Brookfield viscosity of various glass bead pastes.

[0030] Figure 11 The graph shows the DIN 4, DIN 6 and cone and plate viscosities of various glass bead pastes.

[0031] Figure 12 The graph shows the scratch / mar resistance performance of various glass bead pastes on wood panels.

[0032] Figure 13 The graph shows the scrubbing wear of various glass bead pastes.

[0033] Figure 14 The graph shows the water stain resistance of various glass bead pastes.

[0034] Figure 15 is a series of photos showing the settling of various glass bead pastes. Detailed Description of the Invention

[0035] The following description is a currently desired embodiment for implementing the present invention. This description should not be understood as limiting, but is merely for the purpose of describing the general principles and features of the present invention. The scope of the present invention should be determined by the claims.

[0036] The present invention is a coating particularly suitable for wood products, which can provide a desired level of scratch resistance, abrasion resistance and stain resistance. The coating includes a binder and contains 5wt% to 15wt% of glass beads or solid glass microspheres, preferably 10wt% of glass beads or solid glass microspheres.

[0037] Glass beads or solid glass microspheres are generally smaller than 5 microns (Dv50). Suitable glass beads include or Glass beads sold under the trademark.

[0038] Suitable binders include those commonly used in wood coatings, such as acrylic resins, amino resins, alkyl resins, epoxy resins, polyurethane resins, nitrocellulose, and UV-curable acrylate resins.

[0039] The use of glass beads in wood coatings offers many benefits. The addition of glass beads has measurable matting efficiency. Adding glass beads provides 60° gloss and 85° gloss reduction, thereby enhancing the matting effect.

[0040] Example 1

[0041] like Figure 1 As shown, the paint sample without added glass beads (sample WBR1) exhibited higher gloss than the samples with up to 10 wt% glass beads added (samples WB1-A-10, WB1-B-10, and WB1-C-10).

[0042] Adding glass beads has minimal effect on the clarity of the coating. Figure 2 Results from tests measuring the film clarity, L*, of coatings with and without glass beads (samples WB1-A-10, WB1-B-10, and WB1-C-10) are shown. Samples with lower L* values ​​have higher film clarity. While the addition of glass beads increases the L* value of the coating, the effect is minimal, and the underlying wood can still be seen through coatings containing up to 10 wt% glass beads.

[0043] Adding glass beads to wood coating compositions does not change the low shear viscosity of the coating. Figure 3As shown, all wood coating formulations containing glass beads (samples WB2-A-10, WB2-B-10, and WB2-C-10) or without glass beads (sample WBR2) exhibited the same shear-thinning behavior at higher rotational speeds. Initial coating viscosities typically ranged from 2000 to 2400 cps at 10 rpm, decreasing to 1700 to 1900 cps at 100 rpm.

[0044] The addition of glass beads has been found to improve the wear resistance of coated wood products. When glass beads replace the plastic beads and wax traditionally used to improve wear resistance, the coatings exhibit similar or higher wear resistance than achieved with the plastic beads and wax. Furthermore, in mar and scratch resistance tests, the weight required to create a scratch on the coating containing glass microspheres is equal to or greater than that of the coating without microspheres. Based on the Taber abrasion test (ASTM 460), the addition of glass beads to the coating improves the three-dimensional structure of the film coating, resulting in reduced wear.

[0045] The addition of glass beads improves the paint's resistance to water staining. After 24 hours of exposure to water, the color delta E is less than 1, below the level of visible color. Paints containing glass microspheres have good resistance to water staining.

[0046] Applicants have determined that coatings containing 5-15 wt% glass beads provide comparable scratch and stain resistance to conventional wood coatings. These properties are optimal for coatings having a glass bead content of approximately 10 wt%.

[0047] To provide a coating that is shelf stable, the applicants have discovered that the glass beads or solid glass microspheres must first be pre-dispersed in a slurry and then added to the coating. The applicants have discovered that this approach limits the amount of sedimentation of the glass beads or solid glass microspheres in the finished coating composition.

[0048] A shelf-stable paste is first prepared by combining a polyether-based dispersant with a synthetic layered silicate. This paste is then mixed with a binder to form a coating. Preferably, the concentration of the glass beads in the paste is in the range of 60 wt% to 80 wt%, the concentration of the polyether-based dispersant is in the range of 20 wt% to 25 wt%, and the concentration of the synthetic layered silicate is in the range of 1 wt% to 3 wt%.

[0049] In an exemplary embodiment, a formulation with a high glass bead loading (76.5 wt%) was prepared that had a slurry consistency and was able to keep the glass beads in suspension. The glass beads or solid glass microspheres were dispersed in a polyether-based dispersant such as GLASS® from BYK. No other dispersant has been found to provide such good results, although other dispersants remain to be tested.

[0050] By synthesizing layered magnesium silicate (such as RD or MS 10) can be combined with a polyether-based dispersant to add viscosity to the paste mixture, forming a high-concentration mixture. Alternatively, other synthetic layered silicates such as sodium silicate can also be used.

[0051] If desired, a defoaming compound can be added to the paste composition. Suitable defoaming compounds include BYK 1724 and SCHWEGO 6325. Other defoamers can also be used if their pH activity range matches the pH of the glass beads, which is between 8 and 11.

[0052] Table 1 below lists the results of various formulations that the applicant has found to provide suitable pastes. These formulations provide pastes that are stable over shelf life. All of these formulations can keep the glass beads suspended for extended periods of time without causing the paste to clumping into a solid mass.

[0053] Table 1

[0054]

[0055] End users (customers) mix the paste containing pre-dispersed glass beads or solid glass microspheres into their formulations with a binder and other paint components (such as solvent or water, defoamers, leveling agents, coagulants, rheological additives and hardeners) to obtain a finished paint with a 10% glass bead loading. This glass bead loading provides suspension stability for the glass beads and improves the paint's abrasion and scratch resistance.

[0056] The performance of the conventional coating was compared with the polyurethane wood coating prepared according to the above method with glass bead contents of 5 wt%, 10 wt% and 15 wt% and is shown in Table 2 below.

[0057] Table 2

[0058] Glass bead content Scratch resistance wear resistance Antifouling Tradition 1800g 0.002 ΔE 0.75 5% glass beads 1400g 0.0019 ΔE 0.55 10% glass beads 2400g 0.0055 ΔE 0.60 15% glass beads 2000g 0.00103 ΔE 0.37

[0059] As shown in Table 2, the coatings prepared according to the present invention provide comparable scratch resistance, abrasion resistance, and stain resistance to wood products as conventional coatings.

[0060] In an effort to determine the optimal glass bead paste formulation and loading, glass bead paste samples containing NP3 glass microspheres were prepared and coded as glass bead pastes NP3 2.9, NP3 2.10, NP3 2.11, NP3 2.12, and NP3 2.13. The formulations of these pastes are listed in Table 3 below.

[0061] Table 3

[0062]

[0063] The glass bead paste formulations differed in the amount of NP3 glass microspheres in each formulation. The loading weights of the glass beads in each sample are listed in Table 4 below.

[0064] Table 4

[0065] NP3 2.9 NP3 2.10 NP3 2.11 NP3 2.12 NP3 2.13 NP3 glass beads weight percentage 68.0 66.0 68.0 66.0 64.5

[0066] The glass bead paste was added to a water-based acrylic 1K formulation based on Alberdingk AC2514 resin to give a 10% glass bead loading. The amount of glass bead paste required for a 10% glass bead loading is listed in Table 5 below.

[0067] Table 5

[0068]

[0069] The formulations were prepared using a dispersing mixer equipped with a bullnose blade. One of the glass bead pastes was added using different mixing conditions (different speeds and times) to determine the optimal mixing conditions for preparing the formulations.

[0070] The formulations were applied at 100 μm wet film thickness onto leneta card and wood board using a wire harness k-bar rod and allowed to dry overnight.

[0071] Gloss at 60° and 80° (gloss) and L*, a*, b* were measured using a three-angle micro-gloss meter and an X-Rite spectrophotometer, respectively.

[0072] After 7 days, scrub abrasion resistance and water stain resistance were measured on the coated charts, and scratch / mar resistance was measured on the wood panels.

[0073] The effect of mixing conditions on coating quality was investigated under selected mixing conditions. As shown in Table 6, increasing mixing time and / or speed had no significant benefit on coating quality.

[0074] Table 6

[0075]

[0076] The coating quality was investigated. As shown in Table 7 below, bead pastes NP3 2.9, NP3 2.10, and NP3 2.12 produced very tough coatings. Bead paste NP3 2.12 provided the best coating, being slightly tough. Bead paste NP3 2.11 produced a slightly tough coating.

[0077] Table 7

[0078] base No silica NP3 2.9 NP3 2.10 NP3 2.11 NP3 2.12 NP3 2.13 card OK Very tough Very tough Slightly tough Slightly tough Very tough Wood OK Very tough Very tough Slightly tough Slightly tough Very tough

[0079] like Figure 10 and11 As shown in Figure 2, the addition of glass bead paste leads to a significant decrease in Brookfield viscosity (low shear) and cup viscosity. Figure 8 This can be seen in the high-shear cone and plate viscosities of the glass bead pastes, although this was slightly less affected by the addition of the glass bead paste. Glass bead pastes NP3 2.11 and NP3 2.12 gave the highest (best) viscosities, showing the lowest viscosity drop when added to the Alberdingk acrylate binder. Similarly, lower viscosities were measured for all other glass bead pastes.

[0080] All samples containing glass bead paste showed sedimentation. Figure 15 This is particularly evident for glass bead paste NP3 2.10 as shown in Figure 2. The pellets for all samples were loose and easily redispersed.

[0081] Adding glass bead paste to the formulation resulted in a reduction in the gloss of the paint cards. Figure 4 As shown in Figure 2, the best matting efficiency comes from glass bead paste NP3 2.12, while NP3 2.9 and NP3 2.13 show the lowest gloss reduction. Figure 5 As shown, Glass Bead Paste NP3 2.13 exhibits the best clarity, but also has a higher gloss. Among the cards with lower gloss, Glass Bead Paste NP3 2.11 has the best clarity.

[0082] like Figure 8 As shown, the addition of glass paste increased the red and blue colors of the paint cards. Glass paste NP3 2.10 produced the greenest cards, and glass paste NP3 2.11 produced the bluest cards.

[0083] Adding glass bead paste to the formulation resulted in a decrease in the gloss of the painted panels. Figure 6 As shown in the figure, the gloss reduction of glass bead paste NP32.9 is the best. It can be seen from glass bead paste NP3 2.13 that the extinction efficiency is the worst. Figure 7 As shown, glass bead pastes NP3 2.9 and NP32.12 exhibit the best transparency / low gloss combination. Figure 9 As shown, the addition of glass bead paste increased the red and yellow colors of the painted panels. Glass bead paste NP3 2.10 produced the most red and yellow panels.

[0084] It was found that adding glass bead paste to the formulation had a detrimental effect on the scratch / mar resistance at weights below 500 grams. Figure 12As shown, no noticeable scratches or mars were observed at 100 g weight in any panel, and only very slight scratches were observed with NP32.12 at 200 g using the glass bead paste. The best scratch / mar resistance was seen with NP3 2.10, which produced the thinnest scratches at higher weights, followed closely by NP3 2.12. The remaining three formulations exhibited significantly worse scratch / mar resistance, with noticeably thicker scratches. NP3 2.13 exhibited the worst overall scratch / mar resistance.

[0085] The addition of glass bead paste had a positive effect on scrub wear, as determined by the change in 60° gloss, with all panels containing glass bead paste showing less change after abrasion than panels without glass bead paste. Figure 13 As shown, bead paste NP3 2.13 exhibited the greatest change in gloss at 60°, while NP3 2.11 and 2.12 were least affected. Adding bead paste altered the effect of scrubbing abrasion on gloss at 85°, with panels containing bead paste showing a polishing effect (positive Δ gloss) rather than the abrasion results (negative Δ gloss) seen in panels without bead paste. Bead paste NP3 2.13 exhibited the smallest change in gloss at 85°.

[0086] like Figure 13 As shown, the addition of glass bead paste has a negative impact on the scrub abrasion resistance, as determined by ΔE, with panels containing glass bead paste exhibiting a greater color change after abrasion. As measured by ΔE, glass bead paste NP3 2.13 has the lowest scrub abrasion resistance, while NP3 2.10, NP3 2.11, and NP3 2.12 provide the best scrub abrasion resistance.

[0087] like Figure 14 As shown, all coated panels containing glass bead paste exhibited visible water staining; significantly worse water staining was seen in the cards containing glass bead paste NP3 2.10. The best water stain resistance came from glass bead paste NP3 2.11 ( Figure 11 ).

[0088] Based on the above tests, glass bead paste NP3 2.12 is the best overall formula

[0089] It will be apparent to those skilled in the art that, based on the above teachings of this disclosure, various modifications and variations of the described embodiments and embodiments are possible. The disclosed embodiments and embodiments are presented for illustrative purposes only. Other alternative embodiments may include some or all of the features disclosed herein. Therefore, our intention is to cover all such modifications and alternative embodiments that may fall within the true scope of the present invention's given full width. In addition, the disclosed numerical range is each numerical value disclosed within the scope, including endpoints.

Claims

1. A method for forming a wear-resistant coating for wood products, comprising the following steps: a) forming a slurry comprising glass beads, a polyether-based dispersant, and synthetic layered magnesium silicate; and b) mixing the paste with a binder to form the wear-resistant coating, The polyether-based dispersant is a Disperbyk polyether-based dispersant, and the concentration range of the glass beads in the slurry is 60wt%-79wt%, the concentration range of the polyether-based dispersant in the slurry is 20wt%-25wt%, and the concentration range of the synthetic layered magnesium silicate in the slurry is 1wt%-3wt%, provided that the total concentration does not exceed 100wt%.

2. The method of claim 1, wherein the wear-resistant coating comprises between 5 wt% and 15 wt% glass beads.

3. The method of claim 2, wherein the wear resistant coating comprises 10 wt% glass beads.

4. A paste for producing a wear-resistant coating for wood products, the paste comprising: A) Glass beads B) a polyether-based dispersant; and C) synthetic layered magnesium silicate, The polyether-based dispersant is a Disperbyk polyether-based dispersant, and the concentration range of the glass beads in the slurry is 60wt%-79wt%, the concentration range of the polyether-based dispersant in the slurry is 20wt%-25wt%, and the concentration range of the synthetic layered magnesium silicate in the slurry is 1wt%-3wt%, provided that the total concentration does not exceed 100wt%.

5. The slurry of claim 4, further comprising a defoaming agent.

6. A wear-resistant coating for wood products, comprising the paste according to claim 4 and a binder.

7. The wear resistant coating of claim 6, wherein the wear resistant coating comprises between 5 wt% and 15 wt% of glass beads.

8. The wear-resistant coating of claim 7, wherein the wear-resistant coating comprises 10 wt% of glass beads.

9. A finished wood product comprising: a) wood products; and b) The wear-resistant coating according to claim 6.

10. The finished wood product of claim 9, wherein the abrasion resistant coating comprises 5 wt% to 15 wt% glass beads.

11. The finished wood product of claim 10, wherein the abrasion resistant coating comprises 10 wt% glass beads.

12. A method for forming a wear-resistant coating for a wood product, comprising the steps of: a) forming a paste premix comprising a polyether-based dispersant and a synthetic layered magnesium silicate; b) dispersing glass beads in the paste premix to form a shelf-stable paste; and c) mixing the shelf-stable paste with a binder to form the wear-resistant coating, The polyether-based dispersant is a Disperbyk polyether-based dispersant, and the concentration of glass beads in the shelf-stable slurry is in the range of 60 wt % to 79 wt %, the concentration of polyether-based dispersant in the shelf-stable slurry is in the range of 20 wt % to 25 wt %, and the concentration of synthetic layered magnesium silicate in the shelf-stable slurry is in the range of 1 wt % to 3 wt %.

13. The method of claim 12, wherein the wear-resistant coating contains 5 wt% to 15 wt% glass beads.

14. The method of claim 13, wherein the wear-resistant coating contains 10 wt% glass beads.

15. A method of forming a shelf-stable slurry for a wear-resistant coating for wood products, comprising the steps of mixing glass beads, a polyether-based dispersant, and a synthetic layered magnesium silicate to form a shelf-stable slurry, wherein the polyether-based dispersant is a Disperbyk polyether-based dispersant, and wherein the concentration of the glass beads in the shelf-stable slurry is in the range of 60 wt % to 79 wt %, the concentration of the polyether-based dispersant in the shelf-stable slurry is in the range of 20 wt % to 25 wt %, and the concentration of the synthetic layered magnesium silicate in the shelf-stable slurry is in the range of 1 wt % to 3 wt %.

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