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EP-4735686-A1 - AQUEOUS COATING AGENT

EP4735686A1EP 4735686 A1EP4735686 A1EP 4735686A1EP-4735686-A1

Abstract

Disclosed is an aqueous coating agent comprising: (A) a copolymer of ethylene with a carboxylic acid derivative having an ethylenic double bond; (B) a basic material; and (C) particules having melting point of 100 o C or more, and is further a paper substrate coated with the aqueous coating agent.

Inventors

  • Sakoda, Chiho
  • YOSHIDA, YOSHIO

Assignees

  • Henkel AG & Co. KGaA

Dates

Publication Date
20260506
Application Date
20240628

Claims (10)

  1. An aqueous coating agent comprising: (A) a copolymer of ethylene with a carboxylic acid derivative having an ethylenic double bond; (B) a basic material; and (C) particles having a melting point of 100°C or more.
  2. The aqueous coating agent according to claim 1, wherein the component (C) is comprised in an amount of 1 to 20 parts by mass based on 100 parts by mass of the total of the components (A), (B), and (C).
  3. The aqueous coating agent according to claim 1 or 2, wherein (A) the copolymer of ethylene with a carboxylic acid derivative having an ethylenic double bond comprises a copolymer of ethylene with (meth)acrylic acid.
  4. The aqueous coating agent according to any one of claims 1 to 3, wherein (C) the particles having a melting point of 100°C or more comprise an aqueous dispersion of a paraffin-based resin.
  5. The aqueous coating agent according to any one of claims 1 to 3, wherein (C) the particles having a melting point of 100°C or more comprise a starch.
  6. The aqueous coating agent according to claim 5, wherein the starch comprises tapioca.
  7. The aqueous coating agent according to any one of claims 1 to 6, wherein the aqueous coating agent further comprises (D) a polyvinyl alcohol derivative.
  8. The aqueous coating agent according to any one of claims 1 to 7, wherein (D) the polyvinyl alcohol derivative comprises at least one selected from polyvinyl alcohols and ethylene-modified polyvinyl alcohols.
  9. A paper substrate which is coated with the aqueous coating agent according to any one of claims 1 to 8.
  10. A paper product comprising the paper substrate according to claim 9.

Description

AQUEOUS COATING AGENT The present invention relates to an aqueous coating agent with which a paper substrate is coated. A reduction of plastic products is recommended throughout the world in consideration of environmental problems. Such plastic products are incapable of naturally decomposing, and it is difficult to dispose of the plastic products. Moreover, burning of plastics may result in generation of dioxine and may cause air pollution. Further, in recent years, possibilities that plastic refuse is discarded in the sea and decomposes into microlevels to form small pieces of debris, fish in the sea eat the debris, and humans eat the fish have been perceived as problems. Given such a backdrop, the replacement of plastics with paper substrates has been examined, and particularly in a food field, paper substrates have been processed and made into containers. Conventionally, laminated paper has been used as one form of a paper substrate. The laminated paper is subjected to treatment to prevent the strength of the paper from decreasing and a hand from being dirty due to bleeding an oil component derived from food, or the like. In laminated paper, a polyethylene film or the like is commonly laminated on a paper substrate. In recent years, the recycling of laminated paper has been required due to the raising of environmental awareness. However, such a film has been a stumbling block, and a special device has been thus required for efficiently recycling laminated paper. Patent Literatures 1 and 2 disclose that an aqueous dispersion of an ethylene-based resin is applied to paper. Patent Literature 1 describes that an aqueous dispersion of an ethylene/acrylic acid copolymer, neutralized with ammonia or an amine is useful as a heat sealant for paper or aluminum foil (see [Claims], [0025], [0028], [0029], and [0044]). Patent Literature 2 describes that an aqueous dispersion comprising an ethylene/ethyl acrylate copolymer subjected to acid modification and wax can be applied to a paper substrate (see [Claims], [0046], Table 1 in [0056], and Table 3 in [0068]). The aqueous coating agent (also simply referred to as "coating agent") of the present invention comprises: (A) a copolymer of ethylene with a carboxylic acid derivative having an ethylenic double bond (also referred to as "component (A)" or "(A) copolymer"); (B) a basic material (also referred to as "component (B)"); and (C) particles having a melting point of 100°C or more (also referred to as "(C) particles"). Herein, the "aqueous coating agent" refers to a coating agent in which polymer particles and/or the like can be dispersed or dissolved in an aqueous medium, and is preferably an emulsion in which polymer particles and/or the like are dispersed in an aqueous medium. The "aqueous medium" refers to common water such as city water, distilled water, or ion-exchanged water, may comprise an organic solvent that is soluble or dispersible in water and has poor reactivity with a raw material of resin related to the present invention such as a monomer, for example, acetone, ethyl acetate, or the like, may further comprise a monomer, oligomer, prepolymer, resin, and/or the like soluble or dispersible in water, and may comprise an emulsifier, polymerizable emulsifier, polymerization reaction initiator, chain extender, various additives, and/or the like commonly used when an aqueous resin or water-soluble resin is produced, as described later. The aqueous coating agent of the present embodiment is excellent in water-resistance, a heat-sealing property, heat-resistance, and storage-stability. Each component is described below. <(A) Copolymer of Ethylene with Carboxylic Acid Derivative Having Ethylenic Double Bond> In an embodiment of the present invention, the "(A) copolymer of ethylene with a carboxylic acid derivative having an ethylenic double bond" (hereinafter also referred to as the "(A) copolymer" or "component (A)") is a copolymer of ethylene with a carboxylic acid derivative having an ethylenic double bond, and the copolymer is not particularly limited as long as the aqueous coating agent to which the present invention is directed can be obtained. The aqueous coating agent of the present invention comprises the component (A), whereby the aqueous coating agent of the embodiment of the present invention becomes excellent in water-resistance, a heat-sealing property, and storage-stability (dispersion-stability). Herein, the "carboxylic acid derivative having an ethylenic double bond" refers to a carboxylic acid derivative (comprising carboxylic acid) having a double bond between carbon atoms that enables addition polymerization with ethylene, and specifically refers to a "carboxylic acid having an ethylenic double bond", a "carboxylic acid anhydride having an ethylenic double bond", a "carboxylate ester having an ethylenic double bond", a "carboxylate salt having an ethylenic double bond", or the like. The