Process for production of internally bonded sewing threads
First Claim
Patent Images
1. A process for the preparation of internally bonded sewing thread comprising:
- providing a plied thread having three multifilament yarns wrapped helically about a low melting point core yarn;
winding said plied thread onto a heating drum at a uniform tension in the range of between about 50 and about 500 grams;
heating said drum comprising said wound plied thread in a closed autoclave with superheated steam at a temperature above the melting point of said core yarn and for a time sufficient to soften said core yarn throughout the length of the plied thread wound on said drum to thereby provide said internally bonded sewing thread; and
thereafter wet processing said internally bonded sewing thread at a temperature above the melting point of said low melting point core yarn.
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Abstract
The invention relates to internally bonded sewing threads and to processes for the production of the internally bonding sewing threads. The internally bonding sewing threads of the invention include three multifilament yarns wrapped helically about a thermoplastic bonding core yarn. Processes of the invention include an improved process for preparing a precursor plied thread which is thereafter thermally treated to provide the internally bonded sewing thread. In addition, the invention provides batch and continuous processes for converting the precursor plied thread into internally bonded sewing thread.
35 Citations
22 Claims
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1. A process for the preparation of internally bonded sewing thread comprising:
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providing a plied thread having three multifilament yarns wrapped helically about a low melting point core yarn; winding said plied thread onto a heating drum at a uniform tension in the range of between about 50 and about 500 grams; heating said drum comprising said wound plied thread in a closed autoclave with superheated steam at a temperature above the melting point of said core yarn and for a time sufficient to soften said core yarn throughout the length of the plied thread wound on said drum to thereby provide said internally bonded sewing thread; and thereafter wet processing said internally bonded sewing thread at a temperature above the melting point of said low melting point core yarn. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A continuous thermal treating process for the preparation of an internally bonded sewing thread comprising:
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providing a plied thread having three multifilament yarns wrapped helically about a low melting point core yarn; passing said plied thread continuously through a stretch heating zone wherein said plied thread is stretched and heated while in said stretched condition to a temperature sufficient to soften said low melting point core yarn, bond the exterior multifilament yarns together and confine the low melting point yarn to the interior of the bonded thread; and continuously withdrawing internally bonded plied thread from said stretch heating zone. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16)
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17. A continuous thermal treatment process for the preparation of an internally bonded sewing thread comprising:
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providing a plied thread having three multifilament yarns wrapped helically about a low melting point core yarn; continuously passing said plied thread to a first draw roll rotating at a first predetermined peripheral speed and wrapping said plied thread a plurality of turns about said first draw roll; directing said plied thread from said first draw roll at said first predetermined speed to a second draw roll driven at a second predetermined peripheral speed which is at least 2% greater than said first predetermined peripheral speed, said second draw roll being heated to a temperature greater than the melting temperature of said low melting point core yarn, and wrapping said plied thread a plurality of turns about said second draw roll whereby said plied thread is heated sufficiently to soften said low melting point core yarn; directing said plied thread from said second draw roll at said second predetermined speed to a third draw roll rotating at a third predetermined peripheral speed which is less than said second predetermined peripheral speed, said third draw roll being heated to a temperature above the melting point of said low melting point core yarn and wrapping said plied thread a plurality of turns about said third draw roll; and continuously withdrawing said plied thread from said third draw roll at said third predetermined speed and winding said plied thread onto a wet processing package. - View Dependent Claims (18, 19, 20, 21, 22)
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Specification