| 摘要 |
787,900. Felt. DU PONT DE NEMOURS & CO., E.I. July 13, 1954, No. 20487/54. Class 42(2). Non-woven felt-like material consists of superimposed layers of filamentary material with a minor proportion oriented in the thickness direction of the material, the whole or a major part of the material being composed of retractable synthetic filaments and the number and disposition of the filaments oriented in the thickness direction being such that the material is held together. The material may be modified by retraction of the retractable filaments to produce a compacted material. " Retractable " filaments are those which will shrink and/or crimp when treated with heat or with a swelling agent. The term " filaments " covers staple fibres and continuous filaments. As shown, cards 12 deposit layers of fibre on to a belt 10 to form a batt 16 which is needled at 18 and then passes through an oven 22 or a liquid bath or spray wherein the fibres are retracted; the compacted material may then be pressed by cool rolls 26. Alternatively, the batt may be formed by depositing staple fibres and/or continuous filaments by means of fluid jets. The retractable fibres may be of polyethylene terephthalate and be caused to crimp by heating in boiling water or in hot air at 95-200‹ C., or they may be of regenerated cellulose and be treated with a swelling agent such as an aqueous alkaline solution or anhydrous liquid ammonia. Other materials specified are polyamides, polyesters, polyesteramides, polyvinyl and polyvinylidene polymers, polymerized hydrocarbons, proteinaceous polymers and cellulose esters and ethers. A mixture of regenerated cellulose and polyethylene terephthalate filaments may be used, the batt being treated with aqueous sodium hydroxide to retract the former and then with boiling water to retract the latter. A non- retractable layer may be sandwiched between two retractable layers, or vice versa, the three layers being needled together and the retractable layers then retracted. Specification 603,827, [Group IV (a)], is referred to. |
