Coating with formaldehyde purification function as well as preparation method and applied leather thereof

Abstract

The invention discloses a coating with a formaldehyde purification function, a preparation method of the coating and leather applying the coating, and relates to the technical field of leather coatings. The coating is prepared from the following raw material components: 10 to 40 parts of nano zinc oxide, 2 to 10 parts of alkylphenol polyoxyethylene ether, 10 to 45 parts of styrene acrylate, 5 to 30 parts of aliphatic isocyanate, 5 to 20 parts of polycarbonate, 5 to 30 parts of acrylate, 10 to 50 parts of paraffin emulsion, 0.5 to 5 parts of pH (Potential of Hydrogen) regulator and deionized water. The mass ratio of the nano zinc oxide to the alkylphenol polyoxyethylene ether to the styrene acrylate to the aliphatic isocyanate to the polycarbonate is 1 to (0.2 to 0.4) to (0.8 to 1.2) to (0.5 to 0.8) to (0.5 to 0.8). According to the coating with the formaldehyde purification function, nano-zinc oxide can be uniformly dispersed in a coating system, flocculation agglomeration and precipitation do not occur after long-term storage (6 months), and the coating can be applied to manufacturing of leather for furniture.

Description

Technical Field

[0001] This invention relates to the field of leather coating technology, and more particularly to a coating with formaldehyde purification function, its preparation method, and its application on leather. Background Technology

[0002] Nano-zinc oxide is a novel, multifunctional inorganic material with particle sizes ranging from approximately 1 to 100 nanometers. Due to the miniaturization of the grains, its surface electronic and crystal structures change, resulting in surface effects, volume effects, quantum size effects, and macroscopic tunneling effects not found in macroscopic objects. It also exhibits high transparency and high dispersibility. Nano-zinc oxide possesses a filled valence band and an empty conduction band. Under photoexcitation, electrons transition from the valence band to the conduction band, generating electron-hole pairs. These pairs catalyze the reaction of oxygen and water in the air, producing reactive oxygen species (ROS) such as hydrogen peroxide (H₂O₂), hydroxyl radicals (·OH), and oxygen anions (·O₂). 2- Hydrogen peroxides (H2O, etc.) and other active oxygen species can oxidize formaldehyde molecules that are difficult to degrade, destroy their molecular structure, and ultimately oxidize them into CO2 and H2O, thus achieving the effect of purifying formaldehyde.

[0003] Leather production and processing involve the use of various chemical substances, such as leather oils. These non-fixed leather oils exist in a free state within protein fibers and are very easy to volatilize, forming small molecule aldehydes, acids, and lipids. These substances diffuse into the air, creating unpleasant odors. Formaldehyde, in particular, is highly harmful to the human body, a fact widely acknowledged by consumers.

[0004] Encapsulating nano-zinc oxide materials in leather coatings allows them to act as catalysts for formaldehyde decomposition without being consumed, thus sustainably achieving long-lasting formaldehyde purification. This technique has been reported in existing technologies. For example, CN112473244A discloses a method for preparing air purifier filter fabric with formaldehyde removal function, which leverages the synergistic catalytic action of zinc oxide and titanium dioxide to purify air and decompose organic matter, giving the filter fabric device or filter bag a long-lasting formaldehyde decomposition and air purification environmental protection function. CN102690593A discloses a nano-aqueous coating composition containing an effective amount of non-photosensitive nanoparticles and a surface modifier composed of a surfactant. The non-photosensitive nanoparticles are selected from inorganic metal oxides, natural clay, artificial clay, and mixtures thereof, and the surfactant is selected from anionic surfactants, cationic surfactants, nonionic surfactants, amphoteric surfactants, amphoteric surfactants, and mixtures thereof.

[0005] However, existing coatings containing nano zinc oxide are prone to flocculation, agglomeration, and precipitation, and generally need to be prepared and used immediately. They cannot be stored for a long time to maintain the stability of the nano zinc oxide dispersion. There is also no research on the long-term stability of coatings containing nano zinc oxide. Therefore, it is necessary to optimize and improve existing coatings containing nano zinc oxide. Summary of the Invention

[0006] One objective of this invention is to develop a water-based coating system containing nano-zinc oxide for use in furniture leather coatings. Through the electronic transitions of the nano-zinc oxide material, it releases highly oxidizing free radicals (such as hydrogen peroxide H₂O₂, hydroxyl radicals ·OH, and oxygen anions ·O₂). 2- The invention eliminates formaldehyde molecules in the air by using substances such as hydrogen peroxide (H2O, etc.). Another important objective of this invention is to treat nano-zinc oxide to disperse it in a specific coating component system, maintaining the stability of the dispersion state and preventing flocculation, agglomeration, and precipitation during long-term storage (6 months).

[0007] The objective of this invention is achieved through the following technical solutions.

[0008] A coating with formaldehyde purification function is provided, comprising the following raw material components in parts by weight: 10-40 parts of nano zinc oxide 2-10 parts of alkylphenol polyoxyethylene ether 10-45 parts of styrene acrylate Aliphatic isocyanates, 5-30 parts 5-20 parts polycarbonate 5-30 parts of acrylate, 10-50 parts of paraffin emulsion pH adjuster 0.5-5 parts, 30-100 parts deionized water; The mass ratio of the nano zinc oxide, alkylphenol polyoxyethylene ether, styrene acrylate, aliphatic isocyanate, and polycarbonate is 1:(0.2-0.4):(0.8-1.2):(0.5-0.8):(0.5-0.8).

[0009] Preferably, the mass ratio of the nano zinc oxide, alkylphenol polyoxyethylene ether, styrene acrylate, aliphatic isocyanate, and polycarbonate is 1:0.3:1.0:0.7:0.6.

[0010] Preferably, the alkylphenol polyoxyethylene ether is selected from at least one of NP-4, NP-6, NP-7, NP-9, NP-10, OP-7, and OP-10; the styrene acrylate is selected from at least one of styrene-acrylate-maleic anhydride copolymer (SAMA), styrene-acrylate sulfonate copolymer, fluorinated styrene acrylate, and silicone-modified styrene acrylate; the aliphatic isocyanate is selected from at least one of hexamethylene diisocyanate (HDI) trimer, 1,4-butanediol diisocyanate elastomer, and cyclohexane diisocyanate (CHDI) elastomer; and the polycarbonate is selected from at least one of polycarbonate diol, polyethylene carbonate, bisphenol A type polycarbonate, and 4,4-dihydroxydiphenylmethane polycarbonate. The polycarbonate diol may be selected from poly(1,6-hexanediol) ester diol (PHMCD) or poly(1,5-pentanediol-1,6-hexanediol) ester diol (PHMPMCD).

[0011] Preferably, the acrylate is selected from at least one of butyl acrylate, methyl methacrylate, hydroxyethyl methacrylate, and glycidyl methacrylate.

[0012] Preferably, the pH adjuster is selected from at least one of sodium acetate, formic acid, and ammonia.

[0013] Furthermore, the coating with formaldehyde purification function also includes 0.5-5 parts of preservative and 1-10 parts of epoxy silicone oil.

[0014] Preferably, the preservative is selected from isothiazolinone and isothiazolinone derivatives; the epoxy-based silicone oil is selected from at least one of epoxypropoxypropyl-terminated polydimethylsiloxane and polyether epoxy co-modified silicone oil. The isothiazolinone derivative may be 4,5-dichloro-N-octyl-4-isothiazolin-3-one (DCOIT).

[0015] Preferably, the optimal addition ratio of the nano zinc oxide is 10% of the coating weight, and the formaldehyde purification efficiency can reach 90% or more. Further increasing the addition ratio will not significantly improve the formaldehyde purification efficiency, and will have a certain impact on the suppleness and feel of the leather.

[0016] The preparation method of the coating with formaldehyde purification function includes the following steps: According to the indicated weight ratio, alkylphenol polyoxyethylene ether and nano zinc oxide are mixed and the nano zinc oxide is wetted; then styrene acrylate, aliphatic isocyanate and polycarbonate are added in sequence and mixed evenly; then other components except pH adjuster are added and mixed evenly; finally, pH adjuster is added to adjust the pH to 7.5-8.5 to obtain a coating with formaldehyde purification function.

[0017] The present invention also provides a leather, the surface of which is coated with the above-mentioned coating with formaldehyde purification function.

[0018] Preferably, the coating with formaldehyde purification function is applied to the leather at a rate of 0.8-22 g / square foot.

[0019] Preferably, the coating is applied using an air spraying method, with the spray gun positioned 0.17-0.33m from the leather surface and the air pump pressure above 0.49MPa.

[0020] In some specific implementations, the entire process of leather finishing is as follows: hanging to dry - re-moisten - settling - softening by tumbling - stretching and drying - spot patching / scraping - roller patching - buffing - dust removal - base coat - embossing / ironing - softening by tumbling - top coat - varnish. Formaldehyde-purifying coatings are applied to the top coat process; after spraying and drying, subsequent operations can proceed. This process can fix nano-zinc oxide within the leather coating without overloading the leather. Through the characteristics of nano-zinc oxide—electron transitions—strong oxidizing free radicals are released, reacting with formaldehyde molecules in the air in an oxidation-reduction reaction, thereby eliminating formaldehyde from the air. Nano-zinc oxide acts as a catalyst in the reaction process, sustainably exerting its properties to achieve a long-lasting formaldehyde purification effect.

[0021] This invention increases the contact area between the nano zinc oxide and air by uniformly dispersing nano zinc oxide in a water-based leather coating and spraying it evenly on the leather surface. This allows the nano zinc oxide to release strong oxidizing free radicals more effectively. After the water-based coating dries and forms a film, the nano zinc oxide material is encapsulated in the resin, thereby significantly increasing the adhesion of the nano zinc oxide material. This enables it to effectively purify formaldehyde and enhance the added value of the leather.

[0022] The uniform dispersion process of nano-zinc oxide consists of three steps: wetting, dispersion, and stabilization. During wetting, the air and water vapor on the surface of the nano-zinc oxide are replaced by alkylphenol polyoxyethylene ether, transforming the solid / gas two-phase (nanoparticles / air) into a solid / liquid two-phase (nanoparticles / resin solution). During dispersion, mechanical energy (impact and shear force) breaks down the agglomerated state of nano-zinc oxide into smaller particles, resulting in a dispersed state (uniform distribution). During stabilization, styrene acrylate and aliphatic isocyanate are used to maintain the stability of the dispersion, prevent flocculation, and promote the stability of the suspension based on the styrene acrylate molecules adsorbed on the surface of the inorganic material. After screening, styrene acrylate showed the best dispersion effect on nano-zinc oxide inorganic materials and played a significant role in its molecular stability compared to conventional anionic dispersants such as sodium oleate, carboxylates, sulfates, and sulfonates.

[0023] The coating with formaldehyde purification function of the present invention can uniformly disperse nano zinc oxide in the coating system and does not flocculate, agglomerate or precipitate during long-term storage (6 months), and can be applied to the field of furniture leather manufacturing. Detailed Implementation

[0024] The coatings of the following examples / comparative examples were prepared as follows: alkylphenol polyoxyethylene ether and nano zinc oxide were mixed according to the indicated weight ratios to wet the nano zinc oxide; then styrene acrylate, aliphatic isocyanate, and polycarbonate were added sequentially and mixed evenly; then other components except the pH adjuster were added and mixed evenly; finally, the pH adjuster was added to adjust the mixture and obtain the coatings of the corresponding examples / comparative examples.

[0025] In the following examples / comparative examples, all raw material components are expressed in parts by weight.

[0026] Examples 1-5 The raw material components of the coatings in Examples 1-5 are shown in Table 1 below.

[0027] Table 1 Raw material components of coatings in Examples 1-5 Example 6 The raw material components of the coating in this embodiment are as follows: 20 parts nano zinc oxide, 6 parts NP-106, 20 parts styrene-acrylate sulfonate copolymer, 14 parts 1,4-butanediol diisocyanate elastomer, 12 parts polyethylene carbonate, 15 parts hydroxyethyl methacrylate, 30 parts paraffin emulsion, 3 parts formic acid, and 80 parts deionized water.

[0028] Example 7 The raw material components of the coating in this embodiment are as follows: 20 parts nano zinc oxide, 6 parts OP-7, 20 parts fluorine-modified styrene acrylate, 14 parts cyclohexane diisocyanate (CHDI) elastomer, 12 parts 4-4-dihydroxydiphenylmethane polycarbonate, 15 parts glycidyl methacrylate, 30 parts paraffin emulsion, 3 parts ammonia, and 80 parts deionized water.

[0029] Example 8 The raw material components of the coating in this embodiment are as follows: 20 parts nano zinc oxide, 6 parts NP-66, 20 parts styrene-acrylate-maleic anhydride copolymer (SAMA), 14 parts hexamethylene diisocyanate (HDI) trimer, 12 parts polycarbonate 1,6-hexanediol diol (PHMCD), 15 parts butyl acrylate, 30 parts paraffin emulsion, 3 parts sodium acetate, 0.5 parts isothiazolinone, 1 part epoxypropoxypropyl-terminated polydimethylsiloxane, and 78.5 parts deionized water.

[0030] Example 9 The raw material components of the coating in this embodiment are as follows: 20 parts nano zinc oxide, 6 parts NP-66 parts, 20 parts styrene-acrylate-maleic anhydride copolymer (SAMA), 14 parts hexamethylene diisocyanate (HDI) trimer, 12 parts polycarbonate 1,6-hexanediol diol (PHMCD), 15 parts butyl acrylate, 30 parts paraffin emulsion, 3 parts sodium acetate, 5 parts DCOIT, 10 parts polyether epoxy co-modified silicone oil, and 65 parts deionized water.

[0031] Example 10 The raw material components of the coating in this embodiment are as follows: 20 parts nano zinc oxide, 6 parts NP-66, 20 parts styrene-acrylate-maleic anhydride copolymer (SAMA), 14 parts hexamethylene diisocyanate (HDI) trimer, 12 parts polycarbonate 1,6-hexanediol diol (PHMCD), 15 parts butyl acrylate, 30 parts paraffin emulsion, 3 parts sodium acetate, 2 parts isothiazolinone, 5 parts epoxypropoxypropyl-terminated polydimethylsiloxane, and 73 parts deionized water.

[0032] In the course of research, based on Example 1 (the mass ratio of nano zinc oxide, alkylphenol polyoxyethylene ether, styrene acrylate, aliphatic isocyanate, and polycarbonate in the raw material components is 1:0.3:1.0:0.7:0.6), the following comparative coatings were prepared.

[0033] Comparative Example 1 The difference between this example and Example 1 is that: in the raw material components, there are 30 parts of nano zinc oxide, and the mass ratio of nano zinc oxide, alkylphenol polyoxyethylene ether, styrene acrylate, aliphatic isocyanate and polycarbonate in the raw material components is 1:0.2:0.67:0.47:0.4; the content of nano zinc oxide is 14%; the rest is the same as in Example 1.

[0034] Comparative Example 2 The difference between this comparative example and Example 1 is that: in the raw material components, there are 10 parts of nano zinc oxide; the mass ratio of nano zinc oxide, alkylphenol polyoxyethylene ether, styrene acrylate, aliphatic isocyanate, and polycarbonate in the raw material components is 1:0.6:2:1.4:1.2; the content of nano zinc oxide is 5.3%; and the rest is the same as in Example 1.

[0035] Comparative Example 3 The difference between this comparative example and Example 1 is that NP-6 is not included in the raw material components; otherwise, they are the same as in Example 1.

[0036] Comparative Example 4 The difference between this comparative example and Example 1 is that the raw material components do not include styrene-acrylate-maleic anhydride copolymer (SAMA); otherwise, they are the same as in Example 1.

[0037] Comparative Example 5 The difference between this comparative example and Example 1 is that the raw material components do not include hexamethylene diisocyanate (HDI) trimer; otherwise, they are the same as in Example 1.

[0038] Comparative Example 6 The difference between this comparative example and Example 1 is that the raw material components do not include poly(1,6-hexanediol carbonate) diol (PHMCD); otherwise, they are the same as in Example 1.

[0039] Comparative Example 7 The difference between this comparative example and Example 1 is that butyl acrylate is not included in the raw material components; otherwise, they are the same as in Example 1.

[0040] Comparative Example 8 The difference between this comparative example and Example 1 is that the raw material components do not include paraffin emulsion; otherwise, they are the same as in Example 1.

[0041] Comparative Example 9 The difference between this comparative example and Example 1 is that NP-6 is replaced with octadecyltrimethylammonium chloride (STAC, a cationic surfactant) in the raw material components; otherwise, it is the same as Example 1.

[0042] Comparative Example 10 The difference between this comparative example and Example 1 is that NP-6 is replaced with dodecyl glucoside (APG 0810, a nonionic surfactant) in the raw material components; otherwise, it is the same as Example 1.

[0043] Comparative Example 11 The difference between this comparative example and Example 1 is that NP-6 is replaced with dodecyl dimethyl betaine (BS-12, an amphoteric surfactant) in the raw material components; otherwise, it is the same as Example 1.

[0044] Comparative Example 12 The difference between this comparative example and Example 1 is that NP-6 is replaced with dodecylaminopropionic acid (an amphoteric surfactant) in the raw material components; otherwise, it is the same as Example 1.

[0045] Comparative Example 13 The difference between this comparative example and Example 1 is that NP-6 is replaced with cis-9-octadecenol in the raw material components; otherwise, it is the same as Example 1.

[0046] Comparative Example 14 The difference between this comparative example and Example 1 is that NP-6 is replaced with alcohol ether carboxylate (AEC) in the raw material components; otherwise, it is the same as Example 1.

[0047] Comparative Example 15 The difference between this comparative example and Example 1 is that NP-6 is replaced with sodium dodecyl sulfate (SDS) in the raw material components; otherwise, they are the same as in Example 1.

[0048] Comparative Example 16 The difference between this comparative example and Example 1 is that NP-6 is replaced with triethanolamine alkylbenzenesulfonate in the raw material components; otherwise, it is the same as Example 1.

[0049] Comparative Example 17 The difference between this comparative example and Example 1 is that the styrene-acrylate-maleic anhydride copolymer (SAMA) is replaced with polyether urethane acrylate (PUA) in the raw material components; otherwise, it is the same as Example 1.

[0050] Comparative Example 18 The difference between this comparative example and Example 1 is that the hexamethylene diisocyanate (HDI) trimer is replaced with an aromatic isocyanate in the raw material components; otherwise, it is the same as Example 1.

[0051] The stability of the coatings prepared in Examples 1-10 and Comparative Examples 1-18 was tested. The test method is as follows: 100 grams of coating sample was placed in a transparent glass container, sealed and left to stand for 7 days, and then the state of the coating was observed.

[0052] The test results of the coatings in Examples 1-10 are shown in Table 2.

[0053] Table 2. Stability test results of coatings in Examples 1-10 The test results of the coatings in Comparative Examples 1-18 are shown in Table 3.

[0054] Table 3. Stability test results of the coatings in Comparative Examples 1-18 As can be seen from the test results in Tables 2 and 3, the coatings of Examples 1-10, which use the raw material components and proportions of the present invention, all passed the stability test. However, among the coatings of Comparative Examples 1-18, only Comparative Example 2 (nano zinc oxide content 5.3%) passed the stability test. This indicates that the components and proportions of the technical solution of the present invention have a combined effect on improving the stability of the coatings. In addition, the low nano zinc oxide content also has a positive effect on improving the stability of the coatings.

[0055] Furthermore, the coatings of Examples 1-10 and Comparative Example 2 were subjected to formaldehyde removal tests, and the test methods were in accordance with "JCT1074-2021 Purification Performance of Indoor Air Purification Functional Coating Materials".

[0056] The test results of Examples 1-10 and Comparative Example 2 are shown in Table 4.

[0057] Table 4 Formaldehyde removal test results of Examples 1-10 and Comparative Example 2 As shown in Table 4, the formaldehyde purification efficiency of the coatings in Examples 1-10 reaches 90% or higher, while the formaldehyde purification efficiency of the coating in Comparative Example 2 is only 65.8%, far lower than that of the coatings in Examples 1-10. Further comparison of the formaldehyde purification efficiency test results of Examples 1-5 shows that increasing the content of nano-zinc oxide does not significantly improve the formaldehyde purification efficiency.

[0058] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A coating with formaldehyde purification function, characterized in that, Includes the following raw material components by weight: 10-40 parts of nano zinc oxide 2-10 parts of alkylphenol polyoxyethylene ether 10-45 parts of styrene acrylate Aliphatic isocyanates, 5-30 parts 5-20 parts polycarbonate 5-30 parts of acrylate, 10-50 parts of paraffin emulsion pH adjuster 0.5-5 parts, 30-100 parts deionized water; The mass ratio of the nano zinc oxide, alkylphenol polyoxyethylene ether, styrene acrylate, aliphatic isocyanate, and polycarbonate is 1:(0.2-0.4):(0.8-1.2):(0.5-0.8):(0.5-0.8).

2. The coating with formaldehyde purification function according to claim 1, characterized in that, The alkylphenol polyoxyethylene ether is selected from at least one of NP-4, NP-6, NP-7, NP-9, NP-10, OP-7, and OP-10; the styrene acrylate is selected from at least one of styrene-acrylate-maleic anhydride copolymer, styrene-acrylate sulfonate copolymer, fluorinated styrene acrylate, and silicone-modified styrene acrylate; the aliphatic isocyanate is selected from at least one of hexamethylene diisocyanate trimer, 1,4-butanediol diisocyanate elastomer, and cyclohexane diisocyanate elastomer; and the polycarbonate is selected from at least one of polycarbonate diol, polyethylene carbonate, bisphenol A type polycarbonate, and 4,4-dihydroxydiphenylmethane polycarbonate.

3. The coating with formaldehyde purification function according to claim 1, characterized in that, The acrylate is selected from at least one of butyl acrylate, methyl methacrylate, hydroxyethyl methacrylate, and glycidyl methacrylate.

4. The coating with formaldehyde purification function according to claim 1, characterized in that, The pH adjuster is selected from at least one of sodium acetate, formic acid, and ammonia.

5. The coating with formaldehyde purification function according to claim 1, characterized in that, It also includes 0.5-5 parts of preservative and 1-10 parts of epoxy silicone oil.

6. The coating with formaldehyde purification function according to claim 5, characterized in that, The preservative is selected from isothiazolinone and its derivatives; the epoxy-based silicone oil is selected from at least one of epoxypropoxypropyl-terminated polydimethylsiloxane and polyether epoxy co-modified silicone oil.

7. The method for preparing the coating with formaldehyde purification function as described in any one of claims 1-6, characterized in that, Includes the following steps: According to the indicated weight ratio, alkylphenol polyoxyethylene ether and nano zinc oxide are mixed and the nano zinc oxide is wetted; then styrene acrylate, aliphatic isocyanate and polycarbonate are added in sequence and mixed evenly; then other components except pH adjuster are added and mixed evenly; finally, pH adjuster is added to adjust the pH to 7.5-8.5 to obtain a coating with formaldehyde purification function.

8. A type of leather, characterized in that, The surface is coated with a coating having formaldehyde purification function as described in any one of claims 1-6.

9. The leather according to claim 8, characterized in that, The coating with formaldehyde purification function is applied at a rate of 0.8-22g / square foot.

10. The leather according to claim 9, characterized in that, The coating is applied using an air spraying method, with the spray gun positioned 0.17-0.33m from the leather surface and the air pump pressure above 0.49MPa.

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