Methods of applying bonding materials onto fibrous webs

A method of applying bonding material onto a dry-formed loose fibrous web, which comprises:

• providing a dry-formed loose fibrous web on a first foraminous carrier surface,
• applying to one side of the loose fibrous web a binder solids-containing emulsion in an amount which adds to the loose fibrous web a minor percentage by weight of the total weight of solids to be included in the fibrous web,
• heating the continuum to at least partly dry the solids in the loose fibrous web to form a once-bonded web,
• transferring the once-bonded web to a second foraminous carrier surface to expose the unbonded side of the web, and
• applying to the unbonded side of the once-bonded web a binder solids-containing emulsion in an amount which adds a major percentage by weight of the total binder solids to be included in the web, said first-applied emulsion having a greater binder solids concentration than said second-applied emulsion.

A method of forming a dry-formed bonded fibrous web product, which comprises:

• dispensing fibrous from a distributor onto a foraminous forming surface to form a loose fibrous web,
• transferring said web from the forming surface to a first foraminous carrier surface,
• applying a water-based latex binder solids-containing emulsion bonding material onto one side of the loose fibrous web to add to it from about 20% to about 40% by weight of the total binder solids to be included in the fibrous web product,
• heating the solids-containing loose fibrous web to at least partly dry it and form a once-bonded web,
• transferring the once-bonded web to a second foraminous carrier surface to expose the other side of the web,
• applying additional water-based latex binder solids containing emulsion bonding material onto the other side of the once-bonded web to add to it the rest of the total binder solids to be included in the fibrous web product, and
• heating the web to thereby form a twice-bonded dry-formed cured fibrous web product, said first-applied emulsion having a binder solids concentration of about 20% by weight and said second-applied emulsion having a binder solids concentration of about 15% by weight, said percents by weight being based on the total weight of the respective emulsions.

A method of forming a dry-formed bonded fibrous web product, which comprises:

• dispensing fibers from a distributor onto a foraminous forming surface to form a loose fibrous web,
• transferring said web from the forming surface to a foraminous carrier surface,
• applying a bonding material selected from the group consisting of binder solids-containing solutions and emulsions onto one side of the loose fibrous web,
• heating the solids-bearing loose fibrous web to at least partly dry it and form a once-bonded web,
• applying a bonding material selected from the group consisting of binder solids-containing solutions and emulsions onto the other side of the once-bonded web to thereby form a twice-bonded dry-formed fibrous web,
• drawing a vacuum through the once-bonded web to draw the second-applied bonding material into the once-bonded web, and
• heating the web to form thereby a twice-bonded dry-formed cured fibrous web product, the resulting twice-bonded fibrous web product having a greater tensile strength than if said vacuum had not been drawn.