Protective sheet

A method for producing a glass unit, the method comprising:

• a step (A) of obtaining a Low-E glass plate that comprises a glass substrate and a Low-E layer placed on the glass substrate;
• a step (B) of applying a protective sheet to a surface of the Low-E layer of the Low-E glass plate;
• an optional step (C) of subjecting the Low-E glass plate with the protective sheet applied thereon to at least one process selected from the group consisting of transportation, storage, processing, washing and handling;
• a step (D) of removing the protective sheet from the Low-E glass plate;
• and
• a step (E) of assembling a glass unit using the Low-E glass plate;
• wherein, the protective sheet has a pressure-sensitive adhesive layer,
• the pressure-sensitive adhesive layer is formed from a water-dispersed pressure-sensitive adhesive composition,
• the pressure-sensitive adhesive layer comprises an acrylic polymer as a base polymer in an amount of 95% by weight or greater, and a rust inhibitor in an amount of 0.01% by weight or greater and less than 5% by weight
• the acrylic polymer comprises, as a monomer unit, an alkyl (meth)acrylate in an amount of 60% by weight or greater,
• the alkyl (meth)acrylate has a chemical structure of CH2═C(R1)COOR2, wherein R1 is a hydrogen atom or a methyl group, R2 is an alkyl group having 1 to 20 carbon atoms, and
• the protective sheet contains a chloride ion in an amount of 50 μg or greater and less than 300 μg per gram of pressure-sensitive adhesive layer, determined by hot water extraction.