Interlayer filler material for touch panels, and laminate

A method of producing a laminate comprising,

• a touch panel;
• and
• an interlayer filling material for the touch panel comprising a polyvinyl butyral, a plasticizer, and an organic acid,
• the method comprising:
• 1) filling at least one interlayer space selected from the group consisting of an interlayer space between a surface protection panel and the touch panel, an interlayer space between the touch panel and a polarizing film, and an interlayer space between transparent conductive films included in the touch panel with the interlayer filling material to produce a stack,
• 2) performing preliminary heat-bonding of the stack at about 70° C.,
• 3) followed by an autoclave treatment of the stack at 70° C. to 85° C. and 0.5 MPa or more for 30 minutes,
• 4) then decompressing the stack after cooling to 30° C. or lower to produce the laminate,
• wherein:
• the plasticizer is at least one selected from the group consisting of triethylene glycol-di-2-ethylhexanoate, tetraethylene glycol-di-2-ethylhexanoate, triethylene glycol-di-pivalate, and di-(2-butoxyethyl)adipate,
• the organic acid is at least one selected from the group consisting of 2-ethylhexanoic acid, adipic acid, and phthalic acid,
• an amount of the plasticizer in the interlayer filling material for the touch panel is 5 to 45 parts by weight relative to 100 parts by weight of the polyvinyl butyral,
• an amount of the organic acid in the interlayer filling material for the touch panel is 0.01 to 5 parts by weight relative to 100 parts by weight of the polyvinyl butyral, and
• the polyvinyl butyral contains 16 to 45 mol % hydroxy groups, a degree of acetylation of 0.1 to 30 mol %, and a degree of butyralization of 50 to 85 mol %.