Amino resin composition with low free-formaldehyde

Abstract

The present invention relates to an amino resin composition comprising: an amino resin; a solvent; a catalyst; urea and an organic acid as free formaldehyde removal agents; and a neutralizing agent; wherein, based on the total weight of the composition, 0.1 to 3 weight% of urea and 0.0001 to 0.01 weight% of an organic acid.

Description

Technology Field

[0001] The present invention relates to an amino resin composition and a paint containing the same, and more specifically, to a low-free-formaldehyde amino resin composition with reduced free-formaldehyde content and a paint containing the same. Background Technology

[0002] Amino resins used for paints, such as urea resin, melamine resin, and benzoguanamine resin, contain a significant amount of free formaldehyde as unreacted components of formaldehyde used as raw materials or as decomposition products of by-products generated during the manufacture of amino resins.

[0003] These glass-formaldehydes are known to have adverse effects on surface hardness and water resistance when used as paints, and have recently been identified as a causative agent of sick building syndrome.

[0004] Korean Patent Publication No. 10-2002-0043678 (Patent Document 1) discloses a method for removing residual formaldehyde from formaldehyde resin. However, when the technology disclosed in Patent Document 1 is applied, ammonium acetate has a free formaldehyde reduction effect but the storage stability of the resin is poor, and ammonium bicarbonate has a free formaldehyde reduction effect.

[0005] Therefore, due to the tightening of regulations on formaldehyde residue levels, ingredient formulation and manufacturing processes are required to reduce free formaldehyde contained in amino resins to 0.4% or less. Prior art literature

[0006] Republic of Korea Published Patent No. 10-2002-0043678 (June 12, 2002) The problem to be solved

[0007] One objective of the present invention is to provide an amino resin composition that can effectively lower the content of free formaldehyde while ensuring the storage stability of the resin. means of solving the problem

[0008] The present invention provides an amino resin composition comprising: an amino resin; a solvent; a catalyst; urea and an organic acid as free formaldehyde removal agents; and a neutralizing agent; wherein the composition comprises 0.1 to 3 weight% of urea and 0.0001 to 0.01 weight% of an organic acid based on the total weight of the composition. Effects of the invention

[0009] The amino resin composition according to the present invention can effectively lower the content of free formaldehyde while ensuring the storage stability of the resin.

[0010] In addition, the topcoat paint prepared by including the amino resin composition according to the present invention has excellent appearance characteristics such as curability (solvent resistance) and gloss. Specific details for implementing the invention

[0011] The present invention will be described in detail below.

[0012] An amino resin composition according to one embodiment of the present invention comprises an amino resin, a solvent, a catalyst, urea and an organic acid as free formaldehyde removal agents, and a neutralizing agent.

[0013] The amino resin used in the present invention is an amino resin formed by polycondensing an amino compound and an aldehyde, and may also be a copolymer formed by using two or more types of amino compounds in combination.

[0014] In the present invention, amino compounds include, for example, melamine, urea, benzoguanamine, acetoguanamin, spiroguanamine, cyclohexanecarboguanamine, cyclohexenecarboguanamine, guanamin benzoate, dicyandiamide, etc. Melamine was used in one embodiment of the present invention.

[0015] Amino compounds are included in the amino resin composition in an amount of 10 to 15 weight% or 12 to 14 weight% based on the total weight of the amino resin composition. If the content of the amino compound is below the above range, the curing speed increases, which may cause a problem of reduced storage stability of the resin, and if it exceeds the above range, the molecular weight distribution increases, which may cause a problem of reduced curing speed.

[0016] In the present invention, as aldehydes, it is sufficient to polycondense with amino compounds, and examples include formaldehyde, paraformaldehyde, acetaldehyde, benzaldehyde, etc. In one embodiment of the present invention, paraformaldehyde was used.

[0017] Aldehydes are included in the amino resin composition in an amount of 15 to 20 weight% or 17 to 19 weight% based on the total weight of the amino resin composition. If the content of aldehydes is below the above range, there is a problem of poor curability, and if it exceeds the above range, the content of unreacted aldehydes increases, which may result in a problem requiring an additional process for aldehyde removal.

[0018] Accordingly, an amino resin formed by polycondensing an amino compound and an aldehyde is included in the amino resin composition in an amount of 25 to 35 weight% or 29 to 33 weight% based on the total weight of the amino resin composition.

[0019] In the present invention, the solvent includes alcohol and aromatic hydrocarbons.

[0020] Alcohol plays a role in controlling the solid content of the amino resin composition. In the present invention, the alcohol may be an alcohol having 1 to 8 carbon atoms, for example, butanol.

[0021] Alcohol is included in the amino resin composition as a solvent in an amount of 41 to 65 weight% or 47 to 58 weight% based on the total weight of the amino resin composition. If the alcohol content is below the above range, there is a problem of accelerated curing, and if it exceeds the above range, there may be a problem of failing to satisfy VOCs due to a decrease in solid content.

[0022] Aromatic hydrocarbons play a role in adjusting the storage stability of the amino resin composition. In the present invention, the aromatic hydrocarbon may be, for example, toluene or xylene.

[0023] As a solvent, aromatic hydrocarbons are included in the amino resin composition in an amount of 10 to 20 weight% or 13 to 17 weight% based on the total weight of the amino resin composition. If the content of aromatic hydrocarbons is below the above range, there may be a problem with reduced compatibility with other resins, and if it exceeds the above range, there may be a problem with the storage stability of the resin.

[0024] In one embodiment, the weight ratio of alcohol to aromatic hydrocarbon as a solvent may be 1:0.1 to 0.5 or 1:0.22 to 0.4. If the weight ratio of aromatic hydrocarbon to alcohol as a solvent is less than the above range, there is a problem with the initial viscosity of the resin increasing, and if it exceeds the above range, there may be a problem with the thermal storage of the resin.

[0025] On the other hand, using alcohol solvents alone may lead to a problem where the initial viscosity of the resin increases. Additionally, when using aromatic hydrocarbon solvents alone, excessive heat must be applied to recover the alcohol to remove it, which may result in abnormal reactions and an increase in molecular weight, potentially causing problems with the resin's thermal storage capacity.

[0026] In the present invention, a catalyst can be used to carry out a condensation reaction between an amino compound and an aldehyde. In the present invention, the catalyst is an acid catalyst, and examples include formic acid, phosphoric acid, phthalic acid, hydrochloric acid, nitric acid, sulfuric acid, etc. In one embodiment of the present invention, phthalic acid was used.

[0027] The acid catalyst is included in the amino resin composition in an amount of 0.01 to 0.05 weight% or 0.01 to 0.03 weight% based on the total weight of the amino resin composition. If the content of the catalyst is below the above range, there is a problem of reduced reactivity, and if it exceeds the above range, there may be a problem of variation in appearance and physical properties as the molecular weight distribution increases.

[0028] In the present invention, the free formaldehyde remover comprises urea and an organic acid.

[0029] In the present invention, urea and organic acids are used as free formaldehyde scavengers after the methylolation and polycondensation reactions of amino compounds and aldehydes.

[0030] In the present invention, urea acts as a formaldehyde removal agent. The reaction of urea acting as a formaldehyde removal agent proceeds as follows.

[0031]

[0032] Urea is included in the amino resin composition in an amount of 0.1 to 3 weight% or 0.2 to 1 weight% based on the total weight of the amino resin composition. If the urea content is below the above range, there is a problem that the aldehyde reduction effect is reduced, and if it exceeds the above range, the aldehyde reduction effect is not improved and there may be a problem with poor storage stability of the resin.

[0033] In the present invention, the organic acid promotes the polycondensation reaction between the aldehyde and the amino compound, thereby having the effect of reducing unreacted aldehyde. The organic acid exhibits a synergistic effect with urea as a free formaldehyde scavenger.

[0034] In the present invention, the organic acid may include one or more selected from the group consisting of methanesulfonic acid, para-toluenesulfonic acid, benzenesulfonic acid, dodecylbenzenesulfonic acid, cyclododecanesulfonic acid, and camphorsulfonic acid. For example, the organic acid may be para-toluenesulfonic acid.

[0035] Organic acid is included in the amino resin composition in an amount of 0.0001 to 0.01 weight% or 0.0002 to 0.005 weight% based on the total weight of the amino resin composition. If the content of organic acid is below the above range, there is a problem with reduced aldehyde reduction effect, and if it exceeds the above range, there may be a problem with recoating adhesion due to improved curing degree.

[0036] In one embodiment, the weight ratio of urea to organic acid may be 100 to 10,000:1 or 500 to 2,000:1. If the weight ratio of urea to organic acid is less than the above range, there may be a problem with the storage stability of the manufactured resin, and if it exceeds the above range, there may be a problem with the aldehyde reduction effect being reduced.

[0037] In the present invention, the neutralizing agent serves to adjust the pH of the amino resin and improve its storage stability. In the present invention, the neutralizing agent may be a tertiary amine compound, and may use, for example, trialkyl amines such as trimethylamine, triethylamine, and tributylamine. In one embodiment of the present invention, triethylamine was used.

[0038] The neutralizing agent is included in the amino resin composition in an amount of 0.0001 to 0.05 weight% or 0.0001 to 0.03 weight% based on the total weight of the amino resin composition. If the content of the neutralizing agent is below the above range, there may be problems with the storage stability of the resin, and if it exceeds the above range, there may be problems with yellowing of the coating film and curability.

[0039] The amino resin composition according to the present invention comprises, based on the total weight of the composition, 25 to 35 weight% of amino resin, 51 to 85 weight% of solvent, 0.01 to 0.05 weight% of catalyst, 0.1 to 3 weight% of urea and 0.0001 to 0.01 weight% of organic acid as free formaldehyde removal agents, and 0.0001 to 0.05 weight% of neutralizing agent.

[0040] In one aspect, the present invention provides a topcoat paint comprising an amino resin composition according to the present invention.

[0041] [Example]

[0042] Preparation of amino resin compositions of examples and comparative examples

[0043] An amino resin composition was prepared by stirring and mixing each component in the amounts presented in Tables 1 and 2 below.

[0044] Examples

[0045] Specifically, n-butanol, para-formaldehyde, melamine, and phthalic anhydride were mixed as solvents, heated to 90°C, and reacted at less than 100°C for 30 minutes to 1 hour.

[0046] After confirming that the mixture had become clear as a result of the reaction, the dehydration process was carried out.

[0047] After a certain amount of dehydrated material was removed, urea and para-toluenesulfonic acid were added as free formaldehyde removers and maintained for 1 to 2 hours to check the amount of dehydrated material, and some of the unreacted solvent was removed through vacuum recovery.

[0048] Afterwards, the solvent n-butanol (secondary) and xylene were added to dilute it, and the solid content was adjusted to about 50%.

[0049] Next, triethylamine was added as a neutralizing agent to neutralize the pH to 6.8–7.0, thereby preparing the final resin composition.

[0050] Comparative example

[0051] A resin composition was prepared in the same manner as in the example, except that maleic anhydride was used as the acid catalyst instead of the phthalic anhydride of the example, and the free formaldehyde remover of the example was not used.

[0052] Ingredients (parts by weight) Example-1 Example-2 Example-3 n-BuOH 650 650 650 para-FA 252 252 252 Melamine 176 176 176 Phthalic andydride 0.2 0.2 0.2 Maleic ahyderide 　 　 　 Urea 7 7 10 PTSA 0.005 0.01 0.015 CH3COONH4 　 　 　 AMP 　 　 　 XL 197 197 197 n-BuOH (secondary) 98 98 98 TEA 0.2 0.2 0.2 Total 1380.405 1380.41 1383.415

[0053] Ingredients (parts by weight) Comparative Example-1 Comparative Example-2 Comparative Example-3 Comparative Example-4 Comparative Example-5 Comparative Example-6 Comparative Example-7 Comparative Example-8 Comparative Example-9 n-BuOH 650 650 650 650 650 650 650 650 650 para-FA 240 240 240 240 240 252 252 252 252 Melamine 165 165 165 165 165 176 176 176 176 Phthalic andydride 　 0.2 　 0.2 0.2 0.2 0.2 0.2 0.2 Maleic ahyderide 0.2 　 　 　 　 　 　 　 　 Urea 　 　 　 　 　 7 　 6 3.5 PTSA 　 　 0.05 　 　 　 7 1 3.5 CH3COONH4 　 　 　 1 0.5 　 　 　 　 AMP 　 　 　 23 23 　 　 　 　 XL 190 190 190 190 190 197 197 197 197 n-BuOH (secondary) 　 　 　 　 　 98 98 98 98 TEA 　 　 　 3 3 0.2 0.2 0.2 0.2 Total 1245.2 1245.2 1245.05 1272.2 1271.7 1380.4 1380.4 1380.4 1380.4

[0054] n-BuOH : n-butanol, para-FA : para-formaldehyde,

[0055] PTSA: para-toluene sulfonic acid,

[0056] AMP: 2-amino-2-methyl-1-propanol,

[0057] XL : xylene,

[0058] TEA: triethylamine

[0059] Test Example: Evaluation of characteristics of the prepared amino resin composition

[0060] The physical properties of the coating film prepared from the amino resin composition prepared in the examples and comparative examples and the topcoat paint composition containing the same were evaluated, and the results are presented in Tables 3 and 4.

[0061] As a topcoat paint composition, based on the total weight of the paint composition, a topcoat paint composition was prepared comprising 31 wt% of oil-soluble acrylic resin, 9 wt% of microgel resin, 25 wt% of the amino resin composition prepared in the examples and comparative examples, 5.5 wt% of polyester resin, 2.5 wt% of blocked isocyanate resin, 14 wt% of colored pigment, 9 wt% of solvents, and 4 wt% of additives (surface modifier, dispersant, UV absorber).

[0062] To evaluate the physical properties of the coating film, an electrodeposition paint (KCC ECO3000-S) was applied to a thickness of 30 to 40 μm, and then, in order to secure the physical properties and appearance of the coating film using the topcoat paint composition without an intermediate coat, the physical properties of the coating film were evaluated as follows.

[0063] (1) Solids

[0064] Take 1 to 1.2 g of the sample and evaporate the solvent in a 105°C oven for 3 hours to measure the solid content (unit: %).

[0065] (2) Viscosity

[0066] Measure at 25°C using a Gardner-Holdt viscometer.

[0067] (3) Free formaldehyde content

[0068] Measure according to the BS EN 1243:2001 method (unit: %).

[0069] (4) Storage viscosity

[0070] After placing the amino resin sample in a 60°C convection oven and storing it for 4 weeks, the change in viscosity is evaluated by measuring the viscosity at 25°C using a Gardner-Hold viscometer.

[0071] (5) Film properties

[0072] After applying an electrodeposition paint (KCC ECO3000-S) to a thickness of 30 to 40 μm, a coating specimen was prepared by applying the topcoat paint composition of the present invention to a thickness of 30 to 40 μm, and the physical properties of the coating film were measured as follows.

[0073] ① Hardening properties (xylene solvent properties)

[0074] Place a gauze soaked in xylene onto a coated specimen and rub it vigorously with a cloth at hourly intervals to measure the time at which the surface is wiped clean.

[0075] ② Appearance (CF): Use a 5-point average value on the coated specimen using Wavescane.

[0076] ③ Gloss (20-degree gloss): Use a gloss meter on the coated specimen and use the 5-point average value.

[0077] Physical properties Example-1 Example-2 Example-3 Physical properties of amino resin composition Solids (%) 50.2 50.1 50.3 Viscosity (25℃) A1-A A1-A A1-A Free formaldehyde (%) 0.38 0.4 0.35 Storage viscosity (60℃ × 4 weeks, 25℃) A A AB Film properties Curing properties (Xylene solvent resistance) 10 minutes 8 minutes 7 minutes Gloss (20-degree gloss) 71 73 72 Exterior (CF) 45 48 45

[0078] Physical properties Comparative Example-1 Comparative Example-2 Comparative Example-3 Comparative Example-4 Comparative Example-5 Comparative Example-6 Comparative Example-7 Comparative Example-8 Comparative Example-9 Physical properties of amino resin composition Solids (%) 50.2 50.1 50.3 50.2 50.1 50.1 50.2 50.1 49.8 Viscosity (25℃) A1-A A1-A A1-A A1-A A1-A A1-A A2 A1-A1 A1 Free formaldehyde (%) 0.75 0.8 0.3 0.48 0.52 0.7 0.4 0.35 0.4 Storage viscosity (60℃ × 4 weeks, 25℃) B BC BC AB AB AB BC BC B Film properties Curing properties (Xylene solvent resistance) 4 minutes 3 minutes 2 minutes 8 minutes 9 minutes 4 minutes 2 minutes 2 minutes 2 minutes Gloss (20-degree gloss) 69 63 68 65 68 63 72 64 62 Exterior (CF) 42 41 36 42 44 40 45 43 41

[0079] Meanwhile, the target properties of the manufactured amino resin composition are as shown in Table 5.

[0080] Physical properties Target figures Physical properties of amino resin composition Solids (%) 48~52% Viscosity (25℃) A~A3 Glass formaldehyde content (%) max.0.4% Storage viscosity (60℃ × 4 weeks, 25℃) A1~B Film properties Curing properties (Xylene solvent resistance) 7 minutes or more Gloss (20-degree gloss) 70 or more Exterior (CF) 45 or more

[0081] As shown in Tables 3 and 4, the amino resin composition of the example and the coating film prepared with the paint containing it satisfied all the target properties, whereas the amino resin composition of the comparative example and the coating film prepared with the paint containing it did not satisfy the target properties.

[0082] Specifically, Comparative Examples 1 and 2, which did not include urea and organic acid as free formaldehyde removers and a neutralizing agent, had very high free formaldehyde content and inferior physical properties of the manufactured coating film. Comparative Example 3, which did not include urea as a free formaldehyde remover but only organic acid and did not include a catalyst and a neutralizing agent, had low free formaldehyde content, but the viscosity increased during heat storage and the curability of the manufactured coating film was inferior. Comparative Examples 4 and 5, which used ammonium salts and amino alcohols as free formaldehyde removers, failed to meet the target level for free formaldehyde removal efficacy. Comparative Example 6, which used only urea as a free formaldehyde remover, had a free formaldehyde content higher than the target level and exhibited inferior physical properties of the manufactured coating film. Comparative Example 7, which did not use urea as a free formaldehyde remover and exceeded the organic acid content limit, had a low free formaldehyde content, but the viscosity increased during thermal storage and the curability of the manufactured coating film was inferior. Additionally, in cases where urea and organic acid were included as free formaldehyde removers but fell outside the content range, the viscosity increased during thermal storage (Comparative Example 8), or the physical properties of the manufactured coating film were inferior (Comparative Examples 8 and 9).

[0083] Various embodiments of the present invention are described below.

[0084] Specific example

[0085] Example 1. An amino resin composition comprising: an amino resin; a solvent; a catalyst; urea and an organic acid as free formaldehyde removal agents; and a neutralizing agent; wherein the amino resin composition comprises 0.1 to 3 weight% of urea and 0.0001 to 0.01 weight% of an organic acid based on the total weight of the composition.

[0086] Example 2. An amino resin composition according to Example 1, wherein the weight ratio of urea to organic acid is 100 to 10,000:1.

[0087] Example 3. The amino resin composition of Example 1, wherein the organic acid comprises one or more selected from the group consisting of methanesulfonic acid, para-toluenesulfonic acid, benzenesulfonic acid, dodecylbenzenesulfonic acid, cyclododecanesulfonic acid, and camphorsulfonic acid.

[0088] Example 4. The amino resin composition of Example 1, wherein the neutralizing agent comprises a tertiary amine compound, and comprises 0.0001 to 0.05 weight% of the tertiary amine compound based on the total weight of the composition.

[0089] Example 5. The amino resin composition of Example 1, wherein the catalyst comprises an acid catalyst, and the acid catalyst comprises 0.01 to 0.05 weight% based on the total weight of the composition.

[0090] Example 6. The amino resin composition of Example 1, comprising, based on the total weight of the composition, 25 to 35 weight% of amino resin, 51 to 85 weight% of solvent, 0.01 to 0.05 weight% of catalyst, 0.1 to 3 weight% of urea and 0.0001 to 0.01 weight% of organic acid as free formaldehyde removal agents, and 0.0001 to 0.05 weight% of neutralizing agent.

[0091] Example 7. A topcoat paint comprising an amino resin composition according to any one of Examples 1 to 6.

Claims

Claim 1 An amino resin composition comprising: an amino resin; a solvent; a catalyst; urea and an organic acid as free formaldehyde removal agents; and a neutralizing agent; wherein the amino resin composition comprises 0.1 to 3 weight% of urea and 0.0001 to 0.01 weight% of an organic acid based on the total weight of the composition. Claim 2 An amino resin composition according to claim 1, wherein the weight ratio of urea to organic acid is 100 to 10,000:

1. Claim 3 An amino resin composition according to claim 1, wherein the organic acid comprises one or more selected from the group consisting of methanesulfonic acid, para-toluenesulfonic acid, benzenesulfonic acid, dodecylbenzenesulfonic acid, cyclododecanesulfonic acid, and camphorsulfonic acid. Claim 4 An amino resin composition according to claim 1, wherein the neutralizing agent comprises a tertiary amine compound, and comprises 0.0001 to 0.05 weight% of the tertiary amine compound based on the total weight of the composition. Claim 5 The amino resin composition of claim 1, wherein the catalyst comprises an acid catalyst, and comprises 0.01 to 0.05 weight% of the acid catalyst based on the total weight of the composition. Claim 6 The amino resin composition of claim 1, comprising, based on the total weight of the composition, 25 to 35 weight% of an amino resin, 51 to 85 weight% of a solvent, 0.01 to 0.05 weight% of a catalyst, 0.1 to 3 weight% of urea and 0.0001 to 0.01 weight% of an organic acid as a free formaldehyde removal agent, and 0.0001 to 0.05 weight% of a neutralizing agent. Claim 7 A topcoat paint comprising an amino resin composition according to any one of claims 1 to 6.

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