US3513574A - Fabric pressing pad assembly - Google Patents

Description

May 26, 1970 T J, HQBE ET AL 3,513,574

FABRIC PRESSING PAD ASSEMBLY Filed D86. 30, 1966 INVENTOR. 72500025.] #055 HflPR/s A? /]//C/1EA United States Patent 3,513,574 FABRIC PRESSING PAD ASSEMBLY Theodore J. Hobe, Bloomsburg, Pa., and Harris R.

Kiecker, Overland Park, Kans., assiguors to Minnesota Mining and Manufacturing Company, St.

Paul, Minn., a corporation of Delaware Filed Dec. 30, 1966, Ser. No. 618,561 Int. Cl. D06f 71/36 US. Cl. 38--66 1 Claim ABSTRACT OF THE DISCLOSURE A non-woven lofty open porous mat formed of relatively coarse synthetic polymeric fibers bonded with adhesive at points of contact to define a three-dimensionally extending network of interconnected voids is used as one of the layers in a padded support for either steam or dry fabric pressing operations. The rnat readily compresses and promptly returns to substantially its original thickness upon removal of the pressure. Moisture is promptly eX- hausted through the mat which remains firm and dry.

This invention relates to the field of fabric and garment pressing and is particularly concerned with improving one of the elements in a pressing assembly.

Ironing or pressing operations are carried out by such diverse persons as garment and fabric manufacturers, dry cleaners, launderers, and housewives. Although the time, temperature, pressure, work-contacting surfaces, presence or absence of steam, and other operating conditions vary from installation to installation, all pressing procedures have much in common. In every case, the garment or other item to be pressed is sandwiched between a heated metal surface (which may be covered with fabric) and an unheated porous, compressible support. In steam pressing, the heated metal is perforated and provided with a supply of steam, which passes through the item to be pressed and into the padded support, at the base of which a vacuum may be provided to exhaust the steam.

Nearly forty years ago, it was proposed to use steel wool shavings as part of the padding or cushioning in a pressing buck, or semi-automatic pressing machine. Numerous other patents disclose refinements of this concept, suggesting the use of various shapes of stainless steel or other metal wool, mats, or knitted meshes. Metal fiber products generally have excellent steam transmission but inherently suffer from drawbacks which have discouraged prospective uses. Steel wool rusts and slivers, ofter discoloring, snagging, and injuring the item being pressed. It also has both a low modulus of compression and low degree of resilience; hence the normal pressures used in garment pressing tend to force it so nearly fiat that buttons and zippers are broken, injured or pressed into a concavity in the garment to which they are attached. Seams, which are likewise subjected to higher pressure than single thicknesses of fabric, tend to develop a shine. As a result, steel wool is used in only an extremely small number of installations today.

It has also been proposed to use glass wool as one of the components in a pressing pad assembly; see e.g., US. Pat. 2,198,620. Glass wool, which has a modulus of compression nearly as low as steel wool, suffers from some of the same disadvantages. In addition, its elastic recovery 'when subjected to pressing while wet is quite poor. The extremly fine glass fibers tend to absorb moisture during the steam pressing operation, to dry out slowly thereafter, and to break and powder in use.

Sponges formed from rubber and other materials have also been tried, but have been found to transmit steam poorly, to absorb moisture, and to dry out slowly. Many 3,513,574 Patented May 26, 1970 such materials, although initially resilient, harden and embrittle in the presence of heat and moisture.

Faced with the defects inherent in many of the previous materials used for press pads, the industry today has gone largely to combinations of felts and needled or stitched batts (or quilts) of cotton fibers. These ma terials transmit steam less effectively than steel wool, and their water retention is extremely high, resulting in a soggy pad and damp steam-pressed garments. Further, the fine fibers tend to clog the vacuum ports through which steam is removed, causing irregular drying and increased pressing time. Additionally, heat tends to degrade cellulose, destroying its desirable characteristics. The needled or stitched areas often form hard spots in use, causing pressed frabric to lack uniformity of appearance. Nevertheless, the compressibility, modulus, and resilience of these materialswhether wet or dryhave overshadowed their defects and resulted in their use in most press pads.

To overcome some of the disadvantages inherent in cotton fibers 'while retaining the advantages, non-woven quilts have been formed from fine denier nylon, e.g., 3 denier, or less. Although nylon quilts outlast cotton quilts, they still compress easily, transmit steam poorly, absorb moisture, dry out slowly, develop local hard spots, and clog vacuum ports.

It has now been discovered that certain types of resilient non-woven wholly synthetic lofty open porous mats, formed from relatively coarse fibers and having a relatively high modulus of compression, offer all the advantages of the best previously known pads with virtually none of the disadvantages. The invention employs press pads which have excellent steam transmission rates, high modulus of compressibility, low water absorption, high drying rate, and outstanding wet or dry resilience. As a result, ironing boards and pressing bucks which include layers of this type can be used for long periods of time, e.g., several months, with no significant change in either the quality of the items being pressed or the length of the pressing cycle. Since steam is readily transmitted through the pad, rather than absorbed therein, steampressed garments are dry, crisp, and retentive of their press. Although readily compressible, pads made in accordance with this invention compress no more than about /2 to V3 their original thickness when subjected to a pressure of 5 p.s.i.; accordingly, sufficient resilience and compressibility remains that buttons are neither broken nor forced into concavities in the item being pressed. The mat does not sliver or powder in use, and neither the operator nor the garment being pressed is harmed thereby.

The unique combination of physical characteristics possessed by the low density coarse denier synthetic pads makes them useful in almost all pressing and ironing operations, but they find particular utility in steam pressing. The fact that steam does not remain in the low density pads results in a far drier work surface than is customarily available. Steam pressing is carried out in two basic ways, viz, with a hand steam iron and with a steam buck machine. Although basically similar, these procedures differ to some degree, and the manner in which the low density fibrous pad is employed will vary with the type of pressing.

Understanding of the invention will be further facilitated by reference to the attached drawing, in which:

FIG. 1 is a perspective view of a conventional pressing buck, and

FIG. 2 is a lateral cross-sectional view of the pressing buck of FIG. 1, taken along section line 2-2 and looking in the direction of the arrows.

The main components of pressing buck 10 are padded table 11 and heated pressing head 12, between which an item to be pressed is sandwiched. Table 11 comprises base plate 20, containing vacuum ports 21, vacuum chamber 22 being located therebeneath. In accordance with the invention, press pad 19, a coarse denier lofty open fibrous mat, is positioned above base plate and optionally covered with thin porous felt 18 to smooth out surface irregularities. Cover 13, typically made of duck, overlies felt 18 and provides the surface which contacts and supports one side of an item to be pressed. After positioning the item, hollow head 12 is lowered so that press plate 14, containing holes 15, contacts the upper surface of the item typically under a total force to perhaps 7 or 8 p.s.i. Steam is supplied through line 16 into diffusion chamber 17 of pressing head 12, forced through the item to be pressed and into the covering of table 11. The extremely open nature of press pad 19 allows the steam to flow readily, a vacuum being applied to chamber 22, exhausting the steam from the pressing assembly.

In conventional steam buck setups, a fine denier quilted or felted layer is ordinarily in contact with base plate 20. A problem which commonly has existed is that the fine denier fibers tend to clog the holes, thereby reducing the vacuum and causing irregular drying, since the steam is withdrawn more rapidly in some areas of the pad than in others. When the conventional padding is replaced with coarse denier lofty open press pad 19, the amount of vacuum and rate of steam exhaust often doubles, thereby increasing the rate at which steampressed articles dry. To insure that steam is exhausted through the vacuum ports, rather than having air drawn in through the edges of low density coarse denier fibrous press pad 19, it is sometimes desirable with this arrangement either to compress the edge of press pad 19 tightly against base plate 20 or to seal the edge, e.g., by wrapping it with a strip of tape.

In accordance with the invention, press pad 19 is formed of fibers having a diameter of at least microns corresponding to nylon of 5 to 150 denier per filament. Preferably the diameter of the fibers ranges between 25 and 250 microns, and, for greatest versatility, between about 40 and 100 microns. The void volume of press pad 19 should be high both initially and under operating conditions, e.g., on the order of 90% or more initially and 80% or more when subjected to a force of 5 p.s.i. Thickness should be on the order of 5 to 25 mm. to provide for adequate conformability. As will be explained in greater detail hereinafter, the specific physical characteristics of the press pad will be selected on the basis of the ultimate use intended, and although pads having certain characteristics of an intermediate nature have the widest range of use, considerable deviation is permissible for specific installations.

One product which may be used as a press pad in the practice of this invention is sold by Minnesota Mining and Manufacturing Company under the trade designation Scotchbrite low density abrasive material. Products of this type are disclosed and claimed in US. Pat. 2,958,593, the manufacturing procedures from which are incorporated herein by reference. A hardened adhesive material bonds randomly disposed fibers together at points where they cross and contact each other and also binds abrasive granules thereto. The abrasive granules contribute to the stiffness of the product and minimize any slippage of other layers which they contact, thereby reducing wrinkling and puckering, but their presence is not absolutely essential to the effective performance of the coarse denier lofty open press pad.

A particularly suitable press pad may be formed from one or more layers of Grade A Medium Scotchbrite material, a product in which crimped 50 denier nylon fibers are randomly disposed in open, lofty three-dimensional arrangement and bonded at points where the fibers cross and contact each other by means of somewhat more than twice their weight of phenolformaldehyde resin; an

amount of Grade 100-150 aluminum oxide granules roughly equal to the weight of the resin is also bonded to the fibers. This product is typically about /2 inch thick, with a void volume of 93%. After being subjected to a pressure of 5 p.s.i., thickness is decreased to about A inch, void volume becoming When the compressive force is removed, thickness and void volume return substantially to their original values. When subjected to 10 cycles at 30 p.s.i., using a 200 F. platen and 2-3 seconds dwell time, the product retains approximately /2 its original thickness. When the material is soaked in Water, pressed at 30 p.s.i. and 200 F. for 23 seconds, removed, and dried at 250 F., its thickness is approximately A; less than its original value. (30 p.s.i. represents a pressure far greater than even a seam or button would encounter in existing equipment.)

In hand steam ironing, a conventional ironing board or table is provided with one or two layers of resilient compressible padding material, which in turn is provided with an ironing board cover. The operator lays the garment to be pressed on the ironing board and presses it with a steam iron. In commercial operations a boiler typically supplies steam to the hand iron with a flexible hose, while in home operations the steam iron boils its own water. In any event, where conventional padding is employed, it gradually absorbs water. The greater the moisture content of the pad, the longer it takes to press any given item. Some garments require pressing on both sides; in such cases the operator presses one side and turns it over to press the other, the pressed surface then coming in contact with the damp cover and tending to cancel out the press previously imparted. When a low density coarse denier fibrous pad is positioned directly below the ironing board cover, however, quality of the press remains constant, even after several hours of use. The pressed items are crisp, dry, and retain their press. There is no uneven compression of the ironing pad and the subsequent rippling which often causes uneveness of press and necessitates great care by the operator. Steam from the iron passes through the item being pressed, through the cover, and through the fibrous pad. In order to prevent water from collecting on the support surface of the ironing board, it is frequently desirable to place a conventional cotton quilt beneath the low density pad, thereby providing a means to collect and confine the moisture while still keeping the ironing board cover relatively dry.

In hand operations of the type just described, the thickness and specific nature of the coarse denier low density fibrous pad will vary somewhat with the type of operation being performed. If the operator is a housewife, the pad or pads is preferably on the order of A to ,5 inch thick and formed from fibers having an average diameter on the order of 25 to microns. A satisfactory product is marketed by Minnesota Mining and Manufacturing Company under the trade designation Scotchbrite, Grade A Very Fine, in which 15 denier nylon fiber is formed into a randomly disposed lofty three-dimensional mat, the intertwined fibers being bonded at points where they cross and contact with approximately twice their weight of phenol-formaldehyde resin. The resin itself typically bonds several times its own weight of Grade 280-600 aluminum oxide granules to the fibers. This product is typically about 6 inch thick, having a void volume of 94%. After being subjected to a pressure of 5 p.s.i., thickness is reduced 56%, void volume being lowered to 86%. When subjected to 10 cycles at 30 p.s.i., using a 200 F. platen and 2-3 seconds dwell time, the product retains slightly more than /2 its original thick ness. When the material is soaked in water, pressed at 30 p.s.i. and 200 F. for 2-3 seconds, removed, and dried at 250 F., its thickness is approximately less than its original value. Upon removal of the compressive force, thickness and void volume return to substantially their initial values. Although significantly coarser denier fibers can be used, the housewife is inclined to apply less pressure than industrial steam pressers, and hence is attracted by the degree of compressibility of such a product.

In industrial hand steam pressing operations, a somewhat thicker and less compressible low density coarse denier fibrous pad is considered desirable. Thus, for ex-- ample, the pad or pads may have a thickness up to one inch or perhaps even more, and the diameter of the fibers may range from perhaps 50 to 125 microns.

In discussing the various types of ironing arrangements, it is not intended to thereby limit the scope of this invention, since many variations are possible without departing from the spirit thereof. For example, in specific situations it may be desirable to cover the head of a pressing buck with a low density fibrous material, thereby obviating the need for the present expensive resin coatings provided thereover. Likewise, in certain operations it may be desirable to augment the low density coarse denier fibrous abrasive pad with additional layers of felt, sponge, foam rubber, and the like. A smoother surface may be provided for the pad by needling or otherwise attaching a layer of finer denier fibers on a porous fabric such as scrim cloth to one surface; in some instances the product so formed may function as a combined press pad and board cover. In all such arrangements, however, a significant and essential part of the arrangement is the coarse denier low density fibrous pad, as described hereinabove.

It will similarly be appreciated that other synthetic polymeric fibers and binders may be used to manufacture low density coarse denier press pads as taught herein. The previously mentioned US. Pat. 2,958,593 discusses the prior art and specifies various material which are suitable, bearing the desired utility in mind. It will be recognized that many resilient fibers which are heatand waterresistant will be suitable; fibers having such characteristics may be formed from polyamides, polyesters, polycarbonates, polysul-fones, and polyphenylene oxide. Likewise, adhesives used to bond the fibers and hold them in open, lofty three-dimensional con-figuration may be selected from a number of classes, e.g., phenol-aldehyde resins, heat-resistant epoxy resins, melamine-formalde- 6 hyde resins, polyesterurethanes, polycarbonates, etc. Rigid adhesives are generally preferred, although heat-resistant elastomers may be used.

We claim:

1. In an assembly for steam pressing fabric and the like, wherein a rigid support means is covered with a porous flexible support means essentially comprising at least one compressible porous layer and items to be pressed are sandwiched between said flexible support and a perforated heated surface provided with a supply of steam, the improvement which consists in using as at least one of said compressible porous layers a lofty open resilient mat about 5 to about 25 mm. thick, said mat being formed from randomly disposed nylon fibers on the order of 25 to 125 microns in diameter bonded with phenolaldehyde resin at points of contact to define a threedimensionally extending network of interconnected voids occupying at least about of said mats volume, said phenol-aldehyde resin binding abrasive granules to said fibers, said mat compressing no more than about /3 of its orignial thickness when subjected to a pressure of 5 psi. and promptly returning to substantially its original thickness upon the removal of said pressure, whereby moisture is promptly exhausted through said porous layer so that garments steam pressed while being supported by said flexible support means feel firm and dry and retain their press even after said assembly has been used for a period of several hours or more.

References Cited UNITED STATES PATENTS 1,826,395 10/1931 Galvin 38-66 2,958,593 11/1960 Hodver et a1. 51-295 3,321,853 5/1967 Schultz et al. 38-66 2,473,085 6/1949 Winters 38-66 3,105,313 10/1963 Johnson 38-66 3,323,237 6/ 1967 Eckart 38-66 PATRICK D. LAWSON, Primary Examiner

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