Methods for preparing aqueous latex emulsions for use in pressure-sensitive adhesives

The international publication W000/61670A1 discloses a method for the preparation of aqueous latex emulsions for pressure-sensitive adhesives that, in addition to having improved resistance to water whitening, maintain adhesion in hot water environments.

The method consists of preparing a water-containing latex emulsion from a monomer mixture consisting essentially of the following components: At least one alkyl acrylate having at least 4 carbon atoms in an alkyl chain, at least one unsaturated carboxylic acid of the genus alone and at least one 5-styrene monomer, the polymerization is carried out in the presence of at least one anionic surfactant and an oxidation-reducing free-group initiation system.

Aqueous latex emulsions prepared in accordance with the W000/61670 method have polymer particles with an average particle size less than or equal to approximately 100m in diameter, according to the disclosure. None of the patents/publications above disclose the preparation of pressure-sensitive adhesives using polymerizable surfactants, Us patents 5,928,783 and 6,239,240 disclose a method for preparing aqueous emulsion polymers that can be used in pressure-sensitive adhesives.

Polymers are prepared by reacting at least one unsaturated monohydrate and polymerizable surfactants with an unterminated allylamine component. The preparation of pressure-sensitive adhesives with improved water and whitening resistance is not disclosed in the patent. The international publication W001/85867A1 discloses water-resistant pressure-sensitive adhesives.

It is made of a water-containing latex emulsion with an average particle size essentially not exceeding approximately 100nm and is emulsified in the presence of a reactive emulsifier consisting essentially of the following substances: Alkyl, alkenyl, or aryl-substituted base compounds having at least one allyl substituent, and proxy alkyl sulfonate substitutes, as described in US Patent 5,332,854.

The aqueous latex emulsion is prepared from a monomer mixture consisting of basically 20 of the following components: Approximately 50 to approximately 90 percent by weight of at least one propionic ester with at least four carbon atoms in the alkyl chain, approximately 5 to approximately 10 percent by weight of at least one unsaturated carboxylic acid or its corresponding anhydride, and approximately 15 to approximately 40 percent by weight of at least one styrene monomer, some or all of which can be replaced with hard monomers. That is, the monomer whose Tg is higher than 30℃, such as methyl methacrylate, isobornyl acrylate, 25 ethyl acid, and so on.