Search

CN-121991312-A - Modified blocked polyisocyanate, coating composition, coating film and method for forming coating film

CN121991312ACN 121991312 ACN121991312 ACN 121991312ACN-121991312-A

Abstract

Modified blocked polyisocyanate, coating composition, coating film and method for forming coating film. A modified blocked polyisocyanate modified with a hydroxyl-containing quaternary ammonium salt (I) represented by the following formula (I).

Inventors

  • Noguchi chikahito
  • YASUDA YOSHIHIRO

Assignees

  • 东曹株式会社

Dates

Publication Date
20260508
Application Date
20251028
Priority Date
20241101

Claims (10)

  1. 1. A modified blocked polyisocyanate modified with a hydroxyl-containing quaternary ammonium salt (I) represented by the following formula (I), In the formula (I), R 1 and R 2 each independently represent a C1-8C 1 hydrocarbon group, R 3 represents a C1-16C 1 hydrocarbon group optionally having an ether group, a thioether group or a tertiary amino group, 2 or 3 of R 1 ~R 3 are optionally bonded to each other to form a ring, R 4 represents a hydrogen atom or a C1-8C 1 hydrocarbon group, R 5 represents a C1-16C 2 hydrocarbon group, and X - represents a C1 anionic group.
  2. 2. The modified blocked polyisocyanate of claim 1 wherein each of R 1 , R 2 and R 3 is independently a 1-valent hydrocarbon group of 1 to 3 carbon atoms.
  3. 3. The modified blocked polyisocyanate according to claim 1 or 2, wherein the anionic group is a fatty acid group having 1 to 12 carbon atoms, a monoalkylcarbonate group having an alkyl group having 1 to 8 carbon atoms, or a hydroxyl group.
  4. 4. The modified blocked polyisocyanate according to any one of claims 1 to 3, which comprises a structure derived from an aliphatic polyisocyanate having an aliphatic hydrocarbon group having 4 to 6 carbon atoms or a derivative thereof.
  5. 5. The modified blocked polyisocyanate according to any one of claims 1 to 4, which has at least one group selected from the group consisting of an isocyanate group blocked with an oxime-type blocking agent, an isocyanate group blocked with a pyrazole-type blocking agent and an isocyanate group blocked with an imidazole-type blocking agent.
  6. 6. The modified blocked polyisocyanate according to any one of claims 1 to 5, which is a reaction product of a blocked polyisocyanate having a free isocyanate group and the hydroxyl-containing quaternary ammonium salt (I) or a derivative thereof.
  7. 7. A process for producing the modified blocked polyisocyanate of any one of claims 1 to 5, which comprises a step of reacting a blocked polyisocyanate having a free isocyanate group with the hydroxyl-containing quaternary ammonium salt (I).
  8. 8. A coating composition comprising a main agent and a curing agent, The curing agent comprises the modified blocked polyisocyanate according to any one of claims 1 to 6.
  9. 9. A coating film formed from the coating composition of claim 8.
  10. 10. A method for forming a coating film, comprising the step of applying the coating composition according to claim 8 to an object and curing the object by heating at 100 to 140 ℃.

Description

Modified blocked polyisocyanate, coating composition, coating film and method for forming coating film Cross-reference to related applications The present application claims the benefit of priority from japanese patent application No. 2024-193117, filed on 1 at 11 at 2024, the entire contents of which are incorporated herein by reference. Technical Field The present invention relates to a modified blocked polyisocyanate, a coating composition, a coating film, and a method for forming a coating film. Background Conventionally, polyisocyanates have been known as curing agents used for paints and the like. For example, polyurethane resin coatings obtained by combining a polyol and a polyisocyanate are known to have very excellent abrasion resistance, chemical resistance, and stain resistance. Coatings with polyisocyanates as curing agents are generally two-component compositions comprising a main component (e.g. a polyol) and a polyisocyanate. In the two-component type composition, the main component and the polyisocyanate are stored separately and used after mixing at the time of coating. However, the paint after mixing is cured in a short time, and therefore has a short pot life and a problem in workability at the time of coating. In addition, since the polyisocyanate reacts with water easily, it is impossible to use the polyisocyanate in an aqueous coating such as an electrodeposition coating. As a method for solving these problems, a method of inactivating a polyisocyanate by reacting it with a blocking agent is known. The blocked polyisocyanate obtained by this method does not react with a main agent such as polyol at ordinary temperature, but after heating, the blocked agent is dissociated to regenerate isocyanate groups, and reacts with the main agent to form crosslinks. Therefore, according to the above method, the main agent and the curing agent can be mixed in advance to prepare a paint, and the polyisocyanate can be applied to the aqueous paint, without limiting the application time. In a coating material containing a blocked polyisocyanate as a curing agent, a catalyst such as a quaternary ammonium salt (blocking agent dissociation catalyst) may be used in order to reduce the heat energy required for dissociation of the blocking agent (japanese patent application laid-open No. 2014-084426). Disclosure of Invention In recent years, it has been demanded to cure a coating film at a lower temperature (for example, at a temperature of 140 ℃ or lower) than the conventional one for the purposes of cost reduction, reduction of carbon dioxide emissions, suppression of degradation of a coating object due to heat, and the like at the time of baking coating, while baking of the coating material is performed at a high temperature of 150 ℃ or higher. Therefore, it is also important that the coating composition has good curability, i.e., that it is capable of forming a coating film having good hardness and gel fraction when baked at a lower temperature than before. In this regard, according to the quaternary ammonium salt, the curability of the coating composition containing the blocked polyisocyanate can be improved, and the coating film can be cured even at a temperature of 140 ℃ or less. On the other hand, a method for obtaining a coating composition having excellent curability without adding a blocking agent dissociation catalyst such as a quaternary ammonium salt has not been sufficiently clarified. The present invention has for its object to provide a novel coating composition excellent in curability and a modified blocked polyisocyanate used in the coating composition. The results of the studies by the present inventors show that by using a blocked polyisocyanate modified with a hydroxyl-containing quaternary ammonium salt (modified blocked polyisocyanate), a coating composition having excellent curability can be obtained even without the addition of a blocking agent dissociation catalyst. The present invention has been completed based on the findings of the inventors described above. The present invention provides at least the following [1] to [10]. [1] A modified blocked polyisocyanate modified with a hydroxyl-containing quaternary ammonium salt (I) represented by the following formula (I), In the formula (I), R 1 and R 2 each independently represent a C1-8C 1 hydrocarbon group, R 3 represents a C1-16C 1 hydrocarbon group optionally having an ether group, a thioether group or a tertiary amino group, 2 or 3 of R 1~R3 are optionally bonded to each other to form a ring, R 4 represents a hydrogen atom or a C1-8C 1 hydrocarbon group, R 5 represents a C1-16C 2 hydrocarbon group, and X - represents a C1 anionic group. [2] The modified blocked polyisocyanate according to [1], wherein R 1, R 2 and R 3 are each independently a C1-3 hydrocarbon group of 1 to 3. [3] The modified blocked polyisocyanate according to [1] or [2], wherein the anionic group is a fatty acid group having 1 to 12 carbon atoms, a monoalkylcar