Process for making conformable thermoplastic marking sheet

A process 22 for making a conformable marking sheet comprising the steps of:

• A. providing a casting roller, having a cool rotating casting surface and an accompanying rubber nip roller forming a nip with the casting surface;
• B. feeding a carrier web through the nip;
• C. melt extruding a layer of conformant composite material comprising 50-85 volume percent thermoplastic polymer selected from the group consisting of polyethylene, polypropylene, polybutylene, ethylene copolymers, ethylene-propylene-diene terpolymers, polyvinylidene fluoride, polytetrafluoroethylene, polyvinyl-containing polymers, polyamides, and polyurethanes;
• and 15-50 volume percent inorganic particulate filler having a mean particle size of at least 1 micrometer onto the carrier web ahead of the nip so as to laminate the conformant composite material to the carrier web;
• D. melt extruding a flexible thermoplastic polymer selected from the group consisting of ethylene acrylic acid (EAA) copolymers, ethylene methacrylic acid (EMAA) copolymers, polyethylene (PE), ethylene copolymers, polypropylene (PP), ethylene-propylene-diene terpolymers (EPDM), polybutylene, ionically cross-linked ethylene methacrylic acid copolymer, ethylene n-butyl acrylate (EnBA), ethylene vinyl acetate (EVA), ethylene ethyl acrylate (EEA) copolymer, and ethylene methyl acrylate (EMA) copolymer as a top layer onto the previously formed conformant composite/carrier web laminate from step C. ahead of a nip to form a bonded laminate;
• E. heating the bonded laminate product from step D. to a temperature sufficient to soften the thermoplastic top layer;
• F. applying particles to the softened thermoplastic top layer surface;
• and
• G. laminating a pressure sensitive adhesive to the laminate.

A process for making a conformable marking sheet comprising co-extruding a sheet comprising:

• a first conformant layer of composite material comprising:
• 50 to 85 volume percent of a ductile thermoplastic polymer selected from the group consisting of polyethylene, polypropylene, polybutylene, ethylene copolymers, ethylene-propylene-diene terpolymers, polyvinylidene fluoride, polytetrafluoroethylene, polyvinyl-containing polymers, polyamides, and polyurethanes;
• and
• 15 to 50 volume percent of nonreinforcing mineral particulate having a mean particle size of at least 1 micrometer and wherein the conformant layer exhibits, when tested at 25.degree. C. using standard tensile strength apparatus, not more than 35 NT force per cm width to deform a sample to 115% of original sample length when tested at a strain rate of 0.05 sec.sup.-1 ;
• and
• a second layer, useful as a marking indicium, comprising a thermoplastic polymer chosen from the group consisting of:
• ethylene acrylic acid (EAA) copolymers, ethylene methacrylic acid (EMAA) copolymers, polyethylene (PE), ethylene copolymers, polypropylene (PP), ethylene-propylene-diene terpolymers (EPDM), polybutylene, ionically cross-linked ethylene methacrylic acid copolymer, ethylene n-butyl acrylate (EnBA), ethylene vinyl acetate (EVA), ethylene ethyl acrylate (EEA) copolymer, and ethylene methyl acrylate (EMA) copolymer.

A process for partially embedding particles in a surface of a pavement marking sheet comprising the steps of:

• providing a thermoplastic sheet having an exposed surface and selected from the group consisting of ethylene acrylic acid (EAA) copolymers, ethylene methacrylic acid (EMAA) copolymers, polyethylene (PE), ethylene copolymers, polypropylene (PP), ethylene-propylene-diene terpolymers (EPDM), polybutylene, ionically cross-linked ethylene methacrylic acid copolymer, ethylene n-butyl acrylate (EnBA) ethylene vinyl acetate (EVA), ethylene ethyl acrylate (EEA) copolymer, and ethylene methyl acrylate (EMA) copolymer;
• heating the sheet to a temperature sufficient to soften the thermoplastic of the sheet;
• applying particles, selected from the group consisting of transparent microspheres and skid resistant particles, to be embedded to an upward directed surface of the softened thermoplastic sheet;
• maintaining the sheet in a softened condition for a period of time sufficient to achieve a desired level of embedment of the particles into the surface of the softened sheet;
• and
• cooling the sheet to a temperature below the softening temperature of the thermoplastic of the sheet.