Carrier tape base paper making method and base paper made thereby

A carrier-tape base paper having surface, intermediate and bottom layers formed through papermaking, the carrier-tape base paper made by a method comprising:

• (1) a beating step comprising mixing and breaking pulping materials for surface, intermediate and bottom layers into surface, intermediate and bottom pulps prior to beating to the degree of between 42 and 45 degrees SR, between 48 and 50 degrees SR and between 38 and 40 degrees SR respectively;
• (2) a pulp conditioning step comprising
• adjusting the concentration of well-beaten pulp to between 0.65% and 0.85% and adding various auxiliary materials;
• wherein weights of paper waterproof agent, paper strength agent and bonding agent are added to the pulping materials for the surface layer to account for between 1% and 3%, between 3% and 5% and between 0.3% and 0.6% of the total respectively, wherein weights of softening agent and thermal-fusion bonding agent as added to the pulping materials for the intermediate layer account for between 0.5% and 1.5% and between 1% and 3% of the total respectively, and wherein weights of crosslinking agent and bonding agent as added to the pulping materials for the bottom layer account for between 0.5% and 1% of the total respectively, and
• subsequently, adjusting the pH to between 6.5 and 7.5 and stir the mixture evenly, then place it at between 25 degrees C. and 30 degrees C. for 30 minutes to obtain the papermaking materials for the surface, intermediate and bottom layers;
• finally, proceed with screening, purification and deslagging prior to degassing;
• (3) a papermaking step comprising:
• proceeding with wire forming with multi-layer papermaking to obtain one or more surface, intermediate and bottom layers, and
• subsequently proceeding with bonding of wet paper in a sequence from surface-intermediate-bottom layers prior to pressing and drying;
• and
• (4) polishing and rolling,
• wherein:
• the pulping material for the surface layer in the beating step comprises between 45% and 65% sulfate softwood pulp and between 35% and 55% sulfate hardwood pulp;
• the pulping material for the intermediate layer comprises between 30% and 50% sulfate softwood pulp and between 55% and 75% sulfate hardwood pulp;
• and
• the pulping material for the bottom comprises between 20% and 40% sulfate softwood pulp and between 65% and 80% sulfate hardwood pulp,
• wherein the carrier-tape base paper comprises a rated 105 to 125 g/m2 surface layer, a rated 200 to 500 g/m2 intermediate layer, and a rated 165 to 185 g/m2 bottom layer;
• wherein, according to the performance requirements of each layer, different paper pulp raw materials are employed for the surface layer, intermediate layer and bottom layer, and different auxiliary materials are added for conditioning the pulp and making the paper;
• wherein the tensile strength, surface strength expressed in critical wax strength grade and water resistance of the surface layer is 6.5 to 8.5 kN/m, 16 A to 18 A and not less than 600 s respectively;
• wherein the softness of the intermediate layer is 100 and 150 mN;
• wherein paper powder generation measured with an experimental method of taper friction loss is below 100 ppm;
• wherein stiffness of the bottom layer is between 25 and 40 mN;
• and
• wherein the interlayer bonding strength measured with a Scott internal bonding strength tester is not less than 150 J/m2.