US2398159A - Composite batting - Google Patents

Description

Patented Apr. 9, 1946 COMPOSITE BATTING Harmon Rich], Boston, Mass assignor to The Pacific Lumber Company; San Francisco, C'alifi, a corporation of Maine No Drawing. Application October 25, 1943, Serial No. 507,633

4 Claims.

This invention relates to resilient padding or batting as used for stlllfing mattresses, pillows, bed comforters, also the padded arms, seats, and backs of chairs, either stuffed solid or overlying the springs or overlying the coarser padding which is placed against the springs, and the invention has for its object. an improvement in such battings which will have the resiliency of good cotton batting yet be of materially reduced cost, while at the same time possess advantages not had in solid cotton batting. A particular object is to providev a mattress stuffing of good resilience and low cost which will be serviceable under heavy humidity conditions, such as prevailin the tropical and semi-tropical parts of the world. where. the Allied armies are now operating.

The present invention is the result of many experiments with various materials heretofore used as resilient padding; and of which cotton of course is the foremost; to determine how to overcome some of the deficiencies of all cotton stuffing for mattresses and the like, particularly its quick drop in resiliency and slow recovery upon and after exposure to high humidity conditions, such as frequently prevail in the South Sea islands and where cotton mattresses and pillows tend to become a soggy mass.

As my experiments were generally confined to such materials as were commercially available as well as of a cost which would make their large scale use practicable, they necessarily had to be kept within rather narrow limits, and in my experiments I found that various grades of the same materials, such for instance as staple cotton vs. I cotton linters, showed a considerable variation, not only in resiliency but also in behavior under various humidity conditions, and I was surprised to discover that in some instances intimate blends of two dissimilar materials, say 50-50 blends, did not divide their properties in the blend but sometimes showed unlocked for combined properties. This fact caused me to look to the shredded bark fiber of the California redwood tree, for tho I well. knew from previous extensive studies of this material that it was highly resilient, I also knew that due to its peculiar spiral form (microscopic) it had a selffelting nature which caused its fibers to twist and knot together into compact hard felts, and which while extremely valuable for felting purposes either alone or with other felting fibers, is directl contrary to what is required in a resilient padding which must always come back after pressure has been applied and not pack down'into a felt.

After numerous experiments with this material; particularly of very short fiber length, generally averaging about {e of an. inch long,. tho aggregating in length from to about inch in length; when blended with cotton in proportions from 20% to finely shredded'barkfiber, I found that about 40% barkfiber gave the best results and not only yielded a. resilient padding suitable for mattresses. pillows, and other uses which was substantially equal to high grade cotton mattresses at a great saving in cost, but that under conditions of high humidity, changes proved far superior in every way.

Accordingly, careful tests were run of. blends of this finely shredded redwood bark fiber and cotton, for the particular purpose of obtaining some positive information as to its resiliency and general behavior under various humidity conditions. These tests were made through a wellknown commercial research laboratory, and a condensed excerpt of the tests is given below as comparedto cotton, also as to a blend of cotton and cotton linters, and taking a 65% relative humidity as average (R.v H.) for these. humidity tests.

The blends were exposed to various R. H; for many hours and b suspension over humidity controlling inorganic salt solutions, and tested for resiliency in a special. compression machine operating under repeated cycles of loading. and unloading. The tabulated results summarized showed that:

At. 20% R. H.-The bark. blendli's best; and. is followed by the linters blend, and. all. staple cotton.

At 65% R. H.Same result as above.

At R. H;-The bark blend is muchv better; linters and cotton. are: about the same but. much inferior.

' Cottonredwood bark Cotton- 2 Cotton v linters Per cent Per. cent. 26. 6 22'. 2 25; 0 10.0. 10.4.

Nome

The actual thickness of the compressed materials at the end of the sixth compression stroke of the machine:

Thus the recovery figures of the bark blend being percentages of a greater minimum thickness, denote a much greater bulk than would the same percentages applied to the cotton or cottonlinters blend, as at 90% R. H. the bark blend has 76% of the recovery which it has at 65% R. H.; cotton has 45% of the recovery which it has at 65% R. 1-1.; and cotton-linters has but 42% of the recovery which it has at 65% R. H.

Tests were then made to determine the time value for loss of resiliency due to sudden increase in humidity and vice versa, or in other words, the comparative time of moisture regain or loss from an assumed average of 65% R. H. at 70 F. to and from a 90% R. H.

Without burdening the description with the voluminous test data and curve plottings of the tests made, it may be stated that in conditioning from 65% to 90% R. H. the bark blend picks up moisture at the slowest rate and is therefore best. The cotton-linters blend is next best, and the all cotton is worst.

In deconditioning from 90% to 65%, redwood bark blend loses moisture almost eight times faster than cotton-linters blend and four times faster than the cotton. Because of its ability to lose its moisture so rapidly, redwood bark blend therefore has the ability to recover its resilience mostrapidly and hence is unquestionably better than any of the other blends discussed. The time required for the redwood bark blend to completely decondition is about 1200 minutes, or hours. The advantages of using such a blend fora mattress filler are striking. A mattress in use (that is, when a'person is sleeping upon it) is exposed to high relative humidity and the temperature due to body warmth and perspiration. If a mattress can come to equilibrium at a lower humidity in such a short period as 20 hours, it will have recovered much of its resilience in the same time period. Hence, if a mattress is used 8 hours per day and allowed to recover for 1'7 hours per day, it will have lost almost all of its moisture and gained most of its resilience that it respectively gained and 10st while in actual use.

It is of course realized that mixtures of various fibers have been used heretofore for mattress and other cushion stuffing purposes, but it is not thought that anyone has heretofore shown that a cotton batting could have about half of its bulk satisfactorily replaced with another fiber of much up and separate the fibers while releasing the resinous matter, cork cells, and broken fibers, which are screened out, preferably with the aid of an air blast to remove all dust, the treatment being repeated until substantially nothing remains but the best or phloem fibers of the bark mostly reduced to individual condition, that is free from clusters.

These purified and screened individual fibers run from about 1% or less to about inch or more in length, but most of them are below a half inch in length. The fibers are of flattened noduated minute crooked ribbon-like form with lower cost and yet retain its original resiliency substantially unimpaired, and at the same time show such an outstanding performance under high humidities as shown by the results of the tests above set out, as is possible with properly prepared fibers of the bark of the redwood tree.

To prepare the redwood bark fiber for the present purpose, slabs of the substantially dry bark, which often runs from six to twelve inches in thickness, have their epidermis layer removed, as well as the cambium layer, and pieces about four to eight inches in size are fed to a gang sawlike shredder and/or to a hammermill to loosen pointed ends and mostly having a corkscrew like twist, and which special characteristics are the main reason why the fibers remain in place in a blend with cotton fiber in the form of a resilient batting. Another reason is that since the fibers tho separated and clean, have not been washed or chemically treated, they are in their natural condition and slightly resinous to the touch so that they have a high coefficient of friction which further tends to keep them from slipping out of place. In fact the prepared fiber feels like dry wool to the hand and forms a brake against sliding on any surface against which it is pressed, and being just the opposite from the oiliness of cotton fiber in natural condition. Still another factor contributing to the holding of these bark fibers in place, is the fact that by reason of their short length they are embedded in and surrounded on all sides and both ends by the longer cotton fiber, and the net result of these contri-buting features yields a resilient batting of great durability under severe load conditions.

Also, though the prepared bast fibers of the redwood bark are freed from physical impurities and which in the natural bark form somewhat over 15 per cent of the total bark, since the fibers are not chemically treated for the removal of lignin or coloring matter, but have only been mechanically treated, they still contain their natural chemical constituents and coloring matter and likewise their water repellant character, as well as being antagonistic to insect infestation and bacterial growth.

The separated bark fibers as above prepared are blended with cotton, generally of low grade, as by running equal quantities (by weight) together through a cotton picker for initial mixing. The roughly mixed material is then sucked up a pipe and passed through a revolving perforated screen from which all powder and dust is removed by suction. The dust free fiber is then fed to the inlet of a willow machine or mixer; where it is willowed and then forced by air through a pipe to the inlet end of a cotton garnett where the many revolving rolls of the machine studded with fine hooks rake out the mixed fibers so that they lie substantially lengthwise to the motion of the material through the machine.

After garnetting, the material comes out a a pair of thin loose webs of uniformly mixed material which are brought together and then folded back and forth upon one another upon a transversely traveling apron in the so-called camel back and through the compression head" under a light compression roll which results in a web of resilient upholstery batting of about one inch to several inches in thickness, dependent on the speed of the apron, and composed of a large number of the layers received from the garnett machine.

Batting'blends of such prepared redwood bark fiber with cotton fiber have been made containing various proportions of the bark fiber running from 15 to 80%, but th maximum proportion of bark fiber which did not materially change the resiliency and softness of plain cotton was found to be about a 50-50 blend of the two materials, and for practical purposes generally a 40% bark fiber content is preferable.

Crusher roll tests of solid fill mattresses made of a 40-60 blend of treated redwood bark fibers as above described and cotton such as low middling grade, or cotton fly, as against an all cotton mattress, showed, after 100,000 passes of a 270 pound octagonal roller that both mattresses had substantially equal resiliency, at about a 65% R. H.

In several independent tests made between the redwood bark cotton batting as against all cotton batting, with this machine, some factors such as resiliency, decrease in thickness under various sustained loads, softness, etc. at different points in the tests, showed sometimes in favor of the one or the other but the average with up to 50-50 blends was substantially even.

The effect of straight compression tests and the remarkable showing of this blend under high humidity changes has already been given.

A feature of importance of this blend when applied to mattresses is, that of two mattresses of the same size, one stuffed with 40-60 redwood bark fiber-cotton batting, and the other with all cotton batting, and both packed to stand the same compression with about th same percentage of diminution of thickness under a sustained weight in a given time, the bark-cotton stuffed mattress would be about 14% thinner, and consequently this much less bulky, an important feature in army mattresses for portability.

Since the demand for solid fill mattresses has increased on account of the manufacture of coil spring mattresses being held up due to war priorities on steel springs, and the use of all cotton in mattress construction is threatened on account of war requirements, the importance of the redwood bark fiber-cotton batting for stufiing purposes where an all cotton batting was heretofore desired, will be readily appreciated.

Having thus described my invention and the manner of carrying it out, what I claim is:

1. A composite resilient batting for mattress and general stufiing purposes comprising cotton fibers and the best fibers of redwood bark, the bark fibers being cleaned and separated and substantially freed from cork cells and free resinous matter and otherwise in their natural state with normal constituents unimpaired, and constituting from about 30% to about of the total fibers, all thoroughly mixed and garnetted in separate layers stacked one over the other and compressed to form a built up batting of the desired thickness.

2. A composite resilient batting for mattress and general stufiing purposes comprising cotton fibers and the best fibers of redwood bark, the bark fiber being cleaned and separated and substantially freed from cork cells and free resinous matter and otherwise in their natural state with normal constituents unimpaired, and constituting from about 30% to about 55% of the total fibers, all thoroughly mixed and garnetted in separate layers stacked one over the other with their garnetted fibers of the various layers extending at crossing angles with one another, and compressed to form a built up batting of the desired thickness.

3. A composite resilient batting for mattress and general stuffing purposes comprising cotton fibers and the bast fibers of redwood bark, the

bark fibers being cleaned and separated and substantially freed from cork cells and free resinous matter and otherwise in their natural state with normal constituents unimpaired, and constituting about 40 per cent of the total fibers, all thoroughly mixed and garnetted in separate layers stacked one over the other and compressed to form a built up batting of the desired thickness, the majority of the redwood bark fibers being less than one-half inch long.

4. A composite resilient battin for mattress and general stuffing purposes comprising cotton fibers and the bast fibers of redwood bark, the bark fibers being cleaned and separated and substantially freed from cork cells and free resinous matter and otherwise in their natural state with normal constituents unimpaired, and constituting from about 35 to about 45 per cent of the total fibers, all in mixed, picked, thoroughly disseminated condition, and compressed into the desired bulk and with the majority of the redwood bark fibers being of such short lengths as to be completely surrounded by the cotton fibers.

HARMON B. RIEHL.