Claims
- 1. A fibrous batt, the individual fibers of which are bonded at their intersection by melted and refrozen particles of a copolymer of vinyl chloride and a diester of vinyl unsaturated dicarboxylic acid wherein the diester is maleic acid dibutyl ester.
- 2. A fiberous batt of high compressive strength, the individual fibers of which are bonded at their intersection by melted and refrozen particles of a copolymer of vinyl chloride and a diester of vinyl unsaturated dicarboxylic acid;
- wherein the fibers have a fiber denier from 1 to 22; and
- wherein the weight ratio of vinyl unsaturated dicarboxylic acid to vinyl chloride is 3:97 to 20:80; and
- wherein the weight ratio of the copolymer to the fibers is 3:97 to 35:65; and
- wherein the copolymer particles have a size range of 6 to 25 microns; and
- wherein the copolymer has a melting point of 135.degree. to 190.degree. C.; and
- wherein the diester is dibutyl maleate.
Parent Case Info
This application is a divisional application of application Ser. No. 339,627, filed Jan. 15, 1982, which is now U.S. Pat. No. 4,457,793.
Some years ago a method was developed for producing a fiberous batt by contacting a thin web of fibers with a bonding agent based on copolymers of vinylidene chloride and vinyl chloride (PVDC-PVC). The process is described in U.S. Pat. Nos. 3,993,518, 4,047,991, 4,050,977, 4,051,294, 4,053,673, and 4,053,674 naming BUCK et al as inventors.
The prior PVDC-PVC copolymer is employed in dry, particulate form, thus avoiding the packing and matting that is caused by using polymers in solution, suspension, or emulsion form, and at the same time eliminating the cost of removing a solvent or aqueous carrier with heat. In this prior process the batt is formed by lapping the thin polymer-containing web upon itself on a moving conveyor until the desired weight of batt is obtained, and thereafter bonding the fiberous batt by subjecting it to heating at a temperature above the melting point of the copolymer and subsequently cooling and forming the batt into the desiredd thickness The resultant batt, in which fibers are typically bonded to each other at points of contact, possess properties of loft, light-weight, and resilience which are distinctly superior to those of batts made by other processes.
The PVDC-PVC copolymer used in the prior process has adhesive and melt-flow properties which make it superior to all other resins known at the time of the referenced invention. In addition, the particle size of the copolymer, its method of application to the fiberous web, and the subsequent heating and cooling of the batt all contributed to the strength, resilience, and durability of the batt.
While the PVDC-PVC copolymer has the important advantages cited above, it has also some disadvantages. The chemical reactions through which this copolymer is formed require longer reaction times than are necessary to produce some other polymers and copolymers. The efficiency of the reaction at the desired ratios of polyvinylidene chloride to polyvinyl chloride is lower than in many other polymer syntheses and the recovery and separation of unreacted monomer adds to the cost. Also, vinylidene chloride, the major component of this prior copolymer is more expensive than vinyl chloride and certain other monomers.
In the prior process the prior copolymer tends to decompose relatively rapidly at temperatures above 204.degree. C. (400.degree. F.), yielding as one decomposition product hydrochloric acid which causes rust in ovens, cooling chambers, duct work, and even building structures. The prior copolymer produces small amounts of hydrochloric acid even at ambient temperatures, causing rusting of certain metallic surfaces.
Since it is difficult or impossible to avoid temperatures above 204.degree. C. (400.degree. F.) in the commercial production of batts by the prior process, some decomposition of the prior copolymer always occurs. In addition to the problems caused by the release of hydrochloric acid, the prior copolymer itself is discolored by partial decomposition, becoming successively amber colored, brown, and finally black. This makes it impossible to maintain a fully white color in processing certain white fibers into a white end product.
Accordingly, it is an object of the present invention to provide an improved process which utilizes a copolymer having a reduced tendency to decompose under heat and to discolor and to release hydrochloric acid.
It is a further object to utilize a resin or polymer which can be produced more efficiently from less expensive monomers.
It is a still further object to equal or improve on the excellent fiber bonding properties of the prior copolymer.
Yet another object of the present invention is to produce batts which have improved strength, resilience, resistance to compression, and durability.
Another objective is to provide a copolymer which has improved flow properties relative to the prior copolymer and which is available from the reactor in the desired particle-size range, thus eliminating both the cost of grinding or milling the copolymer and eliminating the small, respirable particles which are present in a ground or milled resin.
US Referenced Citations (3)
Divisions (1)
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Number |
Date |
Country |
| Parent |
339627 |
Jan 1982 |
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Patent Grant
4550050
