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TEE EVALUATEON AND PROPERTIES OF AND SACKS Project 2033 Progress Report Fifteen to MULTIWALL SHIPPING SACK PAPER MANUFACTURERS May, 1960 7

THE INSTITUTE OF PAPER CHEMISTRY

Appleton, Wisconsin

BIBLIOGRAPHY

ON

THE EVALUATION AND PROPERTIES OF PAPER BAGS AND SACKS

Project 2033

Progress Report Fifteen

to

MULTIWALL SHIPPING SACK PAPER

MANUFACTURERS

May, 1960 PREFACE

This bibliography is a supplement to Progress Report One on the evaluation and properties of paper bags and sacks. The Abstract Bull- etin of The Institute of Paper Chemistry and Chemical Abstracts have been searched through February, 1960, and Packaging Abstracts through

December, 1959. I p - -

1. Andersson, 0., and Ihrman, C.-B. Behaviour of paper under dynamic loading. 1. Some observations in connection with drop testing of paper bags. Svensk Papperstidn. 62, no. 9:303-7(May 15, 1959); A.B.I.P.C. 30:227.

The strength of paper bags and packages is usually tested by subjecting the package to stresses simulating practical-handling conditions, most frequently to drop tests. Some drop-test parameters were studied, viz., drop height and weight and type of commodity. The average drop number is exponentially related both to the height of the drop and to the weight of the commodity packaged, with insignificant differences between the ex- ponents of the last two parameters. Under the experimental conditions used, i.e., 1-kg. block-bottom bags tested individually without varying any drop parameter, there was an exponential relation (exponent 2.2) between drop number and potential energy expended in the fall of the bag. From this exponential relationship, the characteristic quantity of "limiting energy" can be derived. A drop-testing program can be designed so that this quantity can be determined by dropping each bag only once.

2. Andersson, Olle. Impactlike stressing of paper. Allgem. Papier- Rundschau no. 6:271-2, 274-5(March 20, 1956); B.I.P.C. 27:1258.

Classical paper tests, such as the tensile-strength test, are inadequate for evaluating the behavior of paper on and bag-making machines, in packaging applications, etc. The reasons are twofold: paper is not an ideal elastic material, hence its stress-elongation curve depends on the rate of testing; and the inertia of the material must not be neglected at practical rates of elongation. This discussion deals in a statistical manner with the effect of inertia forces on the stress-strain behavior of paper and thus with the mechanism of impulse or impact processes.

3. Anti-skid paper. Package Eng. 4, no. 5:69(May, 1959); Packaging Abstr. 16:555.

'Gripper-Kraft' is an antiskid paper for the exterior ply of multiwall bags. It is treated with an antiskid chemical while on the machines.

4. Apple, W. W. IPC friction meter. Tappi 41, no. 5:151-2A(May, 1958); Southern Paper Mfr. 21, no. 6:76-7(June, 1958); B.I.P.C. 28: 1649.

The usefulness of the IPC friction meter, particularly for the multi- ply paper manufacturer or converter, is discussed. The kinetic friction measurement is significant in the development of antislip multi-ply bags, since it has been determined that high kinetic friction may be primarily responsible for good performance in handling and stacking of filled units.

5. Army developing paper . Modern Materials Handling 13, no. ll:57(Nov., 1958); Packaging Abstr. 16:108.

A 2

This knitted under development at the U. S. Army Engineer Research &.Development Laboratories, Ft. Belvoir, Va., is reported to stack and handle satisfactorily. The mesh does not lose any significant quantity of fill material except when a very dry fine sand is used. The mesh, however, can be as fine as desired. On the basis of restricted field tests, the bag can be classified as a 60-day bag under the most severe weathering conditions. It can withstand normal weathering effects in excess of six months. The knitted fabric does not ravel when punctured. It resists the stock effects of a close blast, at least as well as jute burlap.

6. Automatic drop tester for multiwall bags. Modern Packaging 31, no. 11:164, 166(July, 1958); Packaging Abstr. 15:737.

This flat-drop tester is operated by setting dials on a control panel to determine the height and pattern of drops in a test series. Drop height can be increased each time in 6-in. increments. The filled multi- wall bag is conveyed automatically to a predetermined height, where it is positioned against the drop gates and dropped onto a concrete block. Re- positioning the bag for second and successive drops is accomplished automati- cally.

7. Baker, W. P. Influence of the ambient medium on the breakdown voltage of sheet insulating materials. Nature 181, no. 4625:1726(June 21, 1958); A.B.I.P.C. 29:395.

The breakdown voltage of cellulose triacetate and tereph- thalate films was measured in air, and that of cellulose triacetate in helium, argon, and nitrogen-air mixture over a range from nearly zero to about 8 atmospheres (i.e., passing through an electric strength valve equal to that of transformer oil). It was found that the breakdown voltage increased with increasing pressure (and electric strength) of the medium. The highest electric strength was recorded when helium was used, the lowest when argon was used.

8. Biesathen, a new packaging material. Verpackungs-Rundschau 10, no. 57280(May, 1959); Packaging Abstr. .16:555.

Biesathen P58 and PJ58 are both bitumen-coated sack additionally coated with polyethylene against the mechanical strains of folding and creas- ing. P58 has as either a smooth or creped papers; PJ58 is a kraft creped paper reinforced with jute. Figures for water-vapor permeability are given.

9. Carey, R. H., and Nutkis, M. S. Tensile impact tests on films. Modern Packaging 32, no. 1:147-52, 207, 209(Sept., 1958); A.B.I.P.C. 29:863.

The method of testing films for tensile impact toughness is outlined, and the results of the test are compared with those using the bag-drop and falling-ball tests. It is concluded that the tensile impact test may be

I 3 used as a satisfactory substitute for the increment-height bag-drop test. By so doing, more precise and accurate impact data may be obtained. The thickness effect--which is not taken into account in the bag-drop test-- may be included in the results of the impact test by a simple conversion. When this is done, a good statistical correlation between the tensile im- pact and the bag-drop tests results. It is recommended that the tensile impact test replace the bag-drop test and that the correlation chart be abandoned after this transformation has been made.

10. Chase designs new type of paper bag with special 'gloss'. Paper, Film and Foil Converter 32, no. 6:46(June, 1958); Packaging Abstr. 15:584.

ChaseGloss paper bags are made of a new with a light reflectance four times as great as that of ordinary bags. Higher gloss printing gives the bags greater consumer appeal.

11. Checkland, P. B., Bull, T. H., and Bakker, E. J. A two-dimensional load-extension tester for fabrics and film. Research J. 28, no. 5: 599-403(May, 1958); A.B.I.P.C. 29:259.

Fabrics in use are rarely subjected to extensions in only one direction, but their load-extension behavior is normally tested in this way. A two- dimensional tester has been constructed with which load-extension curves for both weft and warp directions (or any other- mutually perpendicular directions) are recorded simultaneously. The internal strain without the homogeneously strained portion at the center of the fabric is also recorded. The instrument is.suitable. for making measurements on both knitted and woven fabrics and on films.

12. Debus, E. Packaging films. Fette, Seifen, Anstrichmittel 60: 133-87T958); Packaging Abstr. 15:478.

The article discusses testing methods; characteristics (physicochemical) and properties of important types; and uses.

13. Dowling, Thomas E. Multi-wall bag sewn closures--reviewed and appraised. Paper Trade J. 142, no. 44:38-40(Nov. 3, 1958); A.B.I.P.C. 29: 978.

Experimental data were obtained on moisture-vapor-transmission rates and strength characteristics of multiwall bag sewn closures of five classi- fications: wax-dipped ends, polyethylene-coated tape heat sealed over sewing, asphalt-laminated tape applied over sewing with full latex ad- hesive, creped kraft tape pasted over sewing or adhered with semilatex , and sewn-through creped kraft tape. A comparison based on 100% for the highest value, shows the following values for the five types, in the order listed, 100, 46, 42, 29, and 27% for moisture-vapor transmission; 90, 98, 81, 86, and 100% for strength; and 100, 56, 63, 45, and 45% for cost. Other factors which must be considered are also discussed. 4

14. Fastax film (Hi-speed multiwall shipping tests). A movie. Minneapolis, Minn., Bemis Bro. Bag Co. 350 ft. and white.

15. Fogra investigations. Unpleasant odour from (kraft) paper flour bags. Graph. Woche no. 4:122, 124(Feb., 1958); Packaging Abstr. 15:419.

The causes were investigated. It was found that the paper itself had no unpleasant odor. The flour bags were letterpress printed on . The airing of the three-colored printed papers showed no improvement over those piled directly after printing. Printing on art paper resulted in a conventional odor. The intensity of the odor was due to the drying of the oil medium, depending partly on the concentration of the driers and being affected by their odor. The odor development is due to the reciprocal odor between the and paper. The three other letterpress used for the printing showed no unusually unfavorable properties.

16. Frank, H. Paper bags versus plastic bags?- Allgem. Papier- Rundschau no. 22:1124-5(Nov. 20, 1958); A.B.I.P.Co 29:978.

Reasons are given why plastic paper bags have increased the choice of packaging methods without replacing or competing with the significance of paper bags. Advantages of paper and paper-plastic combination bags are listed.

17. Giersch, G. Experiments on packaging materials made of paper in combination with and aluminum foil. II. Block-bottom bags. Papier u. Druck (Buchbinderei u. Papierverarbeitung) 7, no. 10:144-7(0ct., 1958); A.B.I.P.C. 29:978.

The resistance to water-vapor permeation of block-bottom bags made from various aluminum-paper laminates was tested by weighing bags filled with coffee extract after 0, 3, 6, and 9 weeks of storage at 92% R.H. and 20°C. The water-vapor resistance of bags made of Thermonyl paper was not essentially improved by to aluminum foil, since the laminate cracked during conversion. The type of paper used affected the moisture- proofness of aluminum laminates, imitation paper being superior to thin dense tissue. Aluminum-Thermonyl bags were as vaporproof as were bags of aluminum laminated to thin tissue with wax. and synthetic- resin were not desirable for the lamination-of aluminum-paper bags; starch glue was susceptible to mold growth. Weather-resistant (lac- quered) proved to be difficult to glue at the bag bottom, thus yielding nonhermetic seals.

18. Giersch, Gunter. .Simple investigating methods for the identifi- cation of transparent plastic films produced in East . Papier u. Druck (Buchbinderei u. Papierverarbeitung) 6, no. ll:167-70(Nov., 1957); B.I.P.C. 28:1513.

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Physical and chemical characteristics and identifying analytical methods are given for proprietary plastic films produced in East Germany, including polyvinyl chloride (Ekalon, Decelith A, and hard and soft PVC), polystyrene (Styro.flex), polyamide (Perfol), polyethylene, cellulose triacetate (acetylcellulose), and cellophane (Wilaphan and weather- resistant cellophane).

19. Growers test one-ply stretch paper sacks. Packaging News 6, no. 3:20(March, 1959); Packaging Abstr. 16:354.

The 'Palfsack Extensible' (William Palfrey'.Ltd) has resilience built into the paper by a mechanical stretching of the web during the drying stage of papermaking, and enables the impact shocks to which sacks are subjected to be absorbed without breaking the fibers. The sack is being tried out for ten 5-lb. bags of potatoes and also for bulk-packed roots.

20. Herrmann, Otto. Development and characterization of plastic packaging films. Kunststoffe 48, no. 2:45-51(Feb., 1958); B.I.P.C. 28: 1146.

The properties of plastic films and their modification through uni- lateral and biaxial stretching, multi-ply combinations, and metal evapora- tion are discussed. Methods available and needed to characterize the ser- viceability of plastic films as packaging materials, notably impact strength, cold resistance, and gas and water-vapor permeability, are surveyed.

21. High time for bag standards? Chem. Week 84, no. 8:131-2, 134 (Feb. 21, 1959); A.B.I.P.C. 30:43.

It is estimated that 5-7% of the $150 million/yr. now being paid by chemical manufacturers for multi-ply bags could be saved by standardization of bag sizes. A general survey is made of the scope of the problem, the arguments for and against standardization, and the outlook for the immediate future. It is felt that hope for standardization exists provide the measure can be effected without causing deficiences in package quality or in mer- chandising appeal, and provided the savings effected can be shared by bag maker and bag consumer.

22. Investigation of the weathering characteristics of transparent plastics films in contact with moisture. Plastics Technol. 3, no. 1:25 (Jan. 1957); Packaging Abstr. 14:655.

In the course of an investigation in Florida of solar stills for distilling saline water, it became necessary to obtain additional informa- tion on the permanence of plastics films when exposed to weathering in contact with moisture. Samples of films were tested by being stretched across the tops of drums containing wet sand and exposed for six months at a point about a mile from the sea. During the hours of sunlight moisture evaporated from the sand and condensed on the inner surfaces of the films. Similar samples of dry films were also exposed for the same period. A 6 table is given showing the tensile strengths of the samples (in pounds for strips 1 in. wide) before exposure, after exposure without moisture and after exposure with moisture. The figures quoted for polyethylene, saran and film are 5,0,0; 25,10,10; and 45,0,0 respectively, while samples of three grades of p.v.c. showed considerably greater loss in ten- sile strength after exposure with moisture than without moisture. Samples of black-pigmented polyethylene were unaffected when-exposed with moisture for over a year. It is considered that additional work should be carried out to determine whether or not water-soluble materials have been leached out of films exposed to sunlight and moisture, and whether the mechanism of accelerated degradation is due to the presence of moisture.

23. Johansson, Bengt. Some new methods of packaging liquids and pastelike goods in flexible packages. Verpackungs-Rundschau 9, no. 7: Suppl. 53-6(July, 1958); A.B.I.P.C. 29:206.

Some important considerations in the choice of flexible packaging for liquid and pasty goods are the prospective storage time, the stresses to which the packages might be exposed during shipment and handling, the heat sealability or weldability of the material, and the tightness of the seal or seam. Bags for liquids are of two types--flat bags heat sealed on all four sides and tubular bags with overlapping seams. for frozen and pasty goods include the Hermetet pack, the similar Centrala Kartong, the Eco ice , and the Expresso pack. The Tetra-Pak for the packaging of liquids is also reviewed.

24. Kaltenbach, Josef. A study on the determination of the sizing, effect.according to Cobb. Das Papier 12, no. 15/14:342-50(July, 1958); A.B.I.P.C. 29:250.

Because the Cobb method (I) for determining the degree of sizing of papers is largely unknown in Germany, it was studied to determine its applicability as a mill-control test. Papers of various basis weights made from different furnishes and sized with varying amounts of were evaluated, including rag papers, soda pulps, mechanical pulp mixtures, papers, wrapping and bag papers, machine-glazed papers, waxing stock, offset paper, paper, diazo paper, wall paper, presspahn, etc. Using (I), differences between the top and wire sides of paper sheets were often found to be highly significant. -A comparative evaluation of three different sizes by the usual ink-penetration test showed a better degree of sizing (in the range of 12-18° "Cobb") than did (I). It is concluded that (I) can serve well as a quality-control test for fully and half sized (but not for poorly sized) papers in the basis-weight range of 50-120 g./sq. m. At higher and lower basis weights, the method is less precise. In machine-glazed papers, only the smooth side should be examined by (I). Determinations of the sizing degree of paper samples taken from mill-production runs should be repeated 8-10 times, giving consideration to two-sidedness and to paper properties in general. 7

25. Kayser, K. H. The application of statistical quality control in bag manufacture. Verpackungs-Rundschau 10, no. 6: Suppl. 41-4(June, 1959); A.B.I.P.C. 30:227.

The quality of bags is determined not only by end-use considerations, but also by factors inherent in the bagmaking material and in the construc- tion and operation of the bag machine. The value and application of statistical methods in bag manufacture are discussed, with special emphasis on strength testing in revolving drums.

26. Kenan, R. H. Multiwall bag performance. In Papers presented at the 18th Annual Forum of the Packaging Institute, Sept. 10-12, 1956, Cleve- land, Ohio. New York, The Institute, 1956; Packaging Abstr. 14:648.

27. Krauss, R. A. Characteristics of kraft paper to be used for multi- wall bags and the present status of testing such bags in Germany. Papier, carton et cellulose 4, no. 4:69-72(Sept.-Oct., 1955); B.I.P.C. 26:381.

Essentially the same information as in the previous article (Progress Report One, Project 2033, Abstr. No. 67)'is presented in summarized form. The draft of the specification for establishing minimum strength properties for German kraft bag papers is again included.

28. Krauss, R. A. The evaluation of sack paper. Neue Verpakkung 12, no. 5:319-21; sum.:315(May, 1959); A.B.I.P.C. 30:190.

Differences between European countries and the U.S.A. in the philosophy and practice of paper-sack manufacture and evaluation are discussed. The U. S. emphasizes machine speed at the cost of property fluctuations, the latter being counteracted by a greater safety factor. Thus, the standard American comprises four plies, the two outer ones having area weights of 81.4 g./sq. m. (50 lb.) and the two inner ones having weights of 65 g./sq. m. (40 lb.), whereas the usual German sack consists of three plies of 70-75 g./sq. m. basis weight. The American sack is thus heavier by 75 g./sq. m. Sack paper has been evaluated in Germany since 1955 by static tensile strength; Austria and the Scandinavian countries are contemplating standard testing methods of a dynamic nature. All these methods give an- indication of a sack's serviceability, whereas U. S. testing practices are said to neglect this correlation. The development of Clupak stretchable sack paper, along with divergent opinions on its merits, and related sack- paper developments (notably LK-paper, a German light creped bag paper) are mentioned.

29. Mann, G. The cooling of potatoes packed in hessian and in paper sacks. Eur. Potato J. 1, no. 3:66-8 (Sept., 1958); Packaging Abstr. 16:451.

Details are given of laboratory tests. Potatoes exposed to cold moving air cool down much less rapidly in paper sacks than in hessian sacks. Paper sacks may thus afford some protection against frost damage in transit. 8

30. Multiwall super-barrier. Modern Packaging 32, no. 9:80-1, 166, 168, 170(May, 1959); A.B.I.P.C. 30:190.

The development.of a multi-ply bag that provides the same impervious barrier to WV-and other detrimental external conditions as do metal drums and cans, yet retains the easy handling, filling, and disposal characteris- tics of flexible bulk carriers, has reportedly been achieved in a strong new multilayer paper bag incorporating both aluminum foil and PE. The construction comprises an inner bag of paper laminated with PE to foil and coated with PE, which is heat sealed, and an outer 4-ply paper bag which is sealed with tape. The new bag is closed on a special heat-sealing and taping machine and used to protect hygroscopic materials.(such as resins) under tropical and other high-RH conditions.

31. Myers, A. W., Rogers, C. E., Stannett, V., and Szwarc, M. Studies in the gas and vapor permeability of plastic films and coated papers. V. Effect of crystallinity. Tappi 41, no. ll:716-20(Nov., 1958); A.B.I.P.C. 29:863.

The effect of the degree of crystallinity on the gas and vapor permea- bility of plastic films was studied with special reference to polyethylene. Oxygen, nitrogen, dioxide, and methyl bromide vapor were used in the studies. The permeability was found to decrease steadily with in- creasing crystallinity. A number of explanations for this behavior are advanced, and the relationship between crystallinity and permeability is explored in some detail. The effect of temperature on the gas permeability of polyethylene above and below the crystalline melting point was investi- gated, and the results are discussed.

32. A new alternate bending tester. Polygraph 10, no. 15:643(Aug. 5, 1957); A.B.I.P.C. 29:77.

An improved instrument, manufactured by Karl Frank G.m.b.H. in Wein- heim, Germany, for the determination of alternate bending strength of ma- terials, such as cellophane, plastic films, leather substitutes, paper, board, and , is described. The instrument is equipped with an adjustable drive capable of producing from 110 to 1000 alternate bends/ min. The bending angle can be adjusted within the 0-90 ° range. A load of from 100 to 5000 g. can be used. Upon breaking of the sample, the falling load releases~amechanism which stops the motor. An attached counter records the number of bends.

33. New kraft paper. Food 27, no. 326:430(Nov., 1958); Packaging Abstr. 16:2.

'Extensible' kraft, with a definite, though imperceptible, stretch in both directions, has been developed by William Palfrey Ltd. This stretch makes the paper better resistant to shock and breakages, and therefore particularly suitable for multiwall paper sacks. The use of this paper can, in some cases, reduce the paper weight by 20%. a a WV = water vapor PE = polyethylene 9

34. New special purpose papers for multi-wall paper sacks. Brit. Packer 19, no. 12:795, 798(Dec., 1957); B.I.P.C. 28:978.

Four types of special papers for multi-ply bags have been introduced by William Palfrey, Ltd. These include Nevermold 101, a mold-resistant, nontoxic paper offered in sheet, bulk, or bag form; Scrimtex, a kraft paper reinforced with fiberglass or rayon scrim built in during the manu- facturing process without lamination; a chemically inert paper which has no corrosive effect on metals with which it may come in contact; and a flame-resistant paper.

35. New work for non-skids. Modern Packaging 32, no. 12:102-5, 178 (Aug., 1959); A.B.I.P.C. 30:735.

The use of high-gloss inks and smoother surfaces has improved the sales value of six-packs and other but has reduced their ease of handling. Slithering cases and slippery cartons have increased loading and packaging time and transport and handling damage. Hence, several methods have been adopted to put friction back to work, including antiskid inks, mechanical surface roughening, spot gluing, and nonskid roller and spray . Antiskid inks are economical but tend to reduce gloss and scuff resistance and require application to a large surface area to become effective. Mechanical roughening reduces container strength and printability. Spot gluing to join several cases together involves extra manual labor and damages the appearance of carton flaps. Good results are reported with the application of transparent resin and colloidal silica coatings, e.g., the roll of six-pack beer cartons with a synthetic latex adhesive. Spray coating, e.g., with an aqueous emulsion of PVA, is more effective than roller coating (increasing skid resistance by 50-100% over uncoated shippers), but requires a cold board surface, thus prolonging board-drying time, although some antiskid materials themselves dry within 3-5 seconds. Many antiskid treatments eliminate the need for steel straps on loads of corrugated and -board shippers. A new low-cost antiskid treatment for multi-ply bags which adds a decorative effect in- volves a special embossing process. The embossed surface, produced on the white outer kraft ply of the bag after printing, remains effective even when heavily clogged with dust, does not reduce the Mullen strength of the paper, and increases the bag's resistance to slipping by 400% over untreated bags. Large packers can easily treat their own containers, and smaller packers have a wide choice of nonskid-treated materials which they can order from the converter. Both methods are in use, each having some ad- vantages and some disadvantages.

36. Nierychlewski, T. Evaluation of bag paper by means of strength indices. Przeglad Papierniczy 14, no. 10:289-93(Oct., 1958); A.B.I.P.C. 29:1507.

The evaluation of bag paper by the determination of its rupture , M, and its energy-absorbing capacity, ZZ, is suggested. The index M (intro- duced by the French mill at La Facture-is defined as the square root of 10 the ratio of the product of Mullen burst strength and Elmendorf tearing strength to the basis weight of paper. The energy-absorbing capacity, a term introduced into the German standard DIN 53112, is expressed in kg. mm. and can be calculated from two formulas: ZZ1 = 0.62 X P1 X H1 , and ZZ2 = 0.72 X P2 X R2, for the machine and cross-machine directions, respectively. P1 and P2 are the breaking loads (in kg.) in the machine and cross-machine directions, respectively, H- is the stretchability (in mm.) in the machine direction, R2 the stretchability in the cross-machine direction. M and ZZ were determined for five unbleached kraft pulps beaten to 13-45°S.-R., for handsheets prepared from these pulps, and for 63 bag- paper samples. An analysis of the dependence of M and ZZ on beating degree and of their relation to the conventional strength tests (breaking length, burst, and tear) led to the conclusion that M and ZZ are reliable measures of the essential mechanical strength properties of paper. The following standard requirements for bag paper having a basis weight of about 70 g./sq. m. are suggested: ZZE and ZZ values not less than 22 and 24 kg. mm., respectively, at minimum breaking loads and stretchabilities of 8.4 kg. and .2.3% in the machine direction and 4.2 kg. and 3.8% in the cross-machine direction; an M value above 68 with a burst strength not less than 3.8 kg./sq. cm. and a tear strength not less than 140 g. Determinations of M and ZZ of pulp samples beaten under laboratory conditions (in a Jokro mill) to different S.-R. values can be useful in evaluating the suitabili- ty of pulps for the manufacture of bag paper.

37. Packaging and package standardization brings a $136,000 annual saving. Chem. Processing 21, no. 7:180-1,.183(July, 1958); A.B.I.P.C. 29:548.

A fertilizer manufacturer effected large annual savings by means of a carefully planned program for improvement and standardization of multi- ply bag sizes, styles, construction, and filling and handling equipment.

38. Packaging Institute. Testing the roughness or smoothness of flat kraft paper for multiwall bags. Packaging Inst. Test Proc. PI Paper 32 p-57(proposed); Packaging Abstr. 15:325.

A Gurley S.P.S. Tester No. 4190 is used to measure the time required for 50 cc. of air to pass between the felt side of a sample of paper and a ground optical ring.

9. Park, W. R. R. Semimicro gas permeability apparatus for sheet material. Anal. Chem. 29, no. 12:1897-9(Dec. 1957); Packaging Abstr. 15:97.

An apparatus is described for the relatively rapid (10 to 30 min.) determination of the gas permeability of films up to 10 mils thick with an accuracy of about +5%. It is based on Brubaker's instrument, but uses a specially designed film holder which will take samples as small as 3/4 in. in diameter. I __-

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40. Polyethylene coatings. Paper Bag Maker, March, 1958:146, 170; B.I.P.C. 28:1605.

Paper is coated with polyethylene to impart various properties to the base, such as heat-sealability, chemical resistance, insolubility, and low moisture transmission. The higher molecular weight polyethylene resins are applied to paper by extrusion lamination, as hot melts, or from hot solutions. The lower molecular weight resins are applied as hot melts, either alone or in combination with waxes. In combination with paraffin wax, polyethylene produces coatings having higher blocking temperatures, reduced rub-off, and greater tensile strength, as well as heat-sealed bonds of higher strength. Paper coated with polyethylene is widely used in packaging in such applications as liners for multi-ply bags and fiber drums.

41. Proposed: a block test for films; Standard procedure for deter- the block point of printed flexible film. 3, no. 4: 22-3(July-Aug., 1958); Printing Abstr. 13:779.

Details are given of the equipment required and the procedure for determining the blocking resistance of printed films developed by the Subcommittee on Blocking of the Flexographic Printing Committee of the Packaging Institute. The test was evaluated in a round robin series by three cellulose film manufacturers, and two . The results of these tests under four specific sets of test conditions showed excellent correlation.

42. Protective wax lining for paper bags. Modern Packaging 32, no. 5:1305oan., 1959); Packaging Abstr. 16:285.

Hevi-Kote minimizes wax penetration into paper fibers, thereby ac- cumulating more wax on the surface for better coverage and body. Its lining retards wicking.

43. Roder, Hans-Erich. The mechanical stressing of packaging mate- rials during formation in bag machines. Verpackungs-Rundschau 9, no. 9: Suppl. 6 9-75(Sept., 1958); A.B.I.P.C. 29:522.

Extensive measurements indicated that the formation of bag tubing on present bag-making machines often induces irregular stresses (strains) in the web material which can lead to breaks or undesirable permanent defor- mations. Moreover, machine adjustment is difficult, owing to the many com- plicated devices that partake in the forming of the tube. Theoretical considerations and mathematical analyses, confirmed by practical experiments, indicated that a uniform stress can be achieved by using a tube former which does not disturb the running of the web and does not injure the web material, and by placing the geometric factors determining the tube-forming process (web length and width and the so-called fold-over angle) into a definite trigonometric relationship. A flat-bag machine con- structed according to these principles is described, which produces about 12

800 bags/min., corresponding to a web speed of 200 m./min., without im- pairing the mechanical strength of the material. The construction is applicable to some other bag machines as well.

44. Sabbioni, F. Permeability of plastic films to gas and liquid. Poliplasti 5, no. 22:4-7(1957); Packaging Abstr. 15:258.

Methods are given for determining the liquid and gas permeability of films of plastic materials together with diagrams and of the apparatus used. The permeability of polyethylene to various gases .and liquids is tabulated, both for the high-pressure material and for the low-pressure material.

45. Schmidt, Walter. Sacks and plastics for shipping chemicals. Verpackungs-Rundschau 9, no. 4:275-6(April,.1958); B.I.P.C. 28:1480.

Polyethylene and polyvinyl chloride find increasing use as coating materials for jute and paper bags and sacks and as inner liners for multi- ply paper and jute-crepe paper sacks. Among other plastics, Diofan (modi- fied polyvinylidene chloride) coatings provide excellent moisture pro- tection to paper sacks, whereas polyamide finds only occasional use as sack liner. Plastic-plastic laminates are more suitable for bags than for sacks. Waxes (often in preference to bitumens) find increasing use as barrier and laminating materials for multi-ply jute-paper sacks in the packaging of hygroscopic'chemicals, including foodstuffs. Although syn- thetic fibers are not competitive with jute, certain plastic-coated fibers, such as perlon, may find use as sack material because of their high abra- sion resistance.

46. Schreiber, J. Bursting strength of films. Plaste & Kautschuk 6, no. 2:71-3(1959); Packaging Abstr. 16:559.

A method is given for determining the bursting strength of plastic films. The results are considered and tabulated for the following mate- rials: cellulose acetate, cellulose nitrate, polyamides from caprolactam, polystyrene, polyethylene, rigid polyvinyl chloride and polyvinyl chloride containing varying amounts of plasticizers.

47. Soucek, Milan, and Vocilka, Milos. The relation between air permeability values measured with the Gurley.and Bekk instruments. Sbornik Vyzkumnych Praci z Oboru Celulosy a Papiru 2:215-32(1957); A.B.I.P.C. 30:368.

Air-permeability values of several kraft bag paper samples obtained in a series of parallel measurements with the Gurley and the Bekk testers were analyzed statistically. The two instruments showed a high degree of correlation. A linear conversion equation derived from experimental data is presented. 13

48. Stewart, G. T. Multiwall bag test methods. Packaging Inst. papers 19, part 3:222-8(1957); B.I.P.C. 28:935.

The various types of tests used to predict breakage in multiwall bags include the four-ft. flat, elevator, and rotation drop tests, incline- impact, vibration, tensile, Mullen, slip, tear, and puncture tests. Bag failure results from weaknesses imparted to the bag during manufacture, handling prior to filling, filling and closing, car loading, and in-transit shock. If all factors but in-transit shock could be controlled, test problems would be greatly simplified. Among factors affecting bag strength are the bag paper used, bag structure, end closures, and product contained in the bag.

49. Switch to extensible paper bags slashed breakage up to 85%. Chem. Processing 22, no. 6:55(June, 1959); A.B.I.P.C. 30:770.

A fertilizer packer realized substantial savings in time, labor, and previously lost product by switching from a conventional multi-ply kraft bag to a multi-ply bag formed of extensible paper (Wonderwall bags, made by the Multiwall Bag Division of the West Virginia Pulp and Paper Co.). Besides reducing bag breakage, the new bags provided other benefits in filling, handling, and storing.

50. TAPPI. Smoothness of paper under 3 p.s.i. clamping pressure. Suggested Method T 490 sm-58. 1 sheet.

This method is for the determination of the smoothness of either the top or the wire side of papers under a clamping pressure of 3 p.s.i. It has been shown to be suitable for measuring the smoothness of flat shipping kraft sack paper. Results are expressed as the time required for a given of air to escape laterally between the faces of a compressed sand- wich of the paper.

51. Three-ply greaseproof bag paper. Modern Packaging 32, no. 3: 161(Nov., 1958); Packaging Abstr. 16:88.

This Triplex paper is designed for use by packagers of cookies, cake mixes, coffee, etc. It makes 'semirigid' bags that stand upright without sagging or buckling. It is said to prevent wicking of shortening through seams, creases or folds.

52. Umminger, Otto. An instrument for determining the "adhesion (blocking) value" of plastic packaging films. Verpakkungs-Rundschau 9, no. 7:438-9(July, 1958); A.B.I.P.C. 29:259.

An instrument for determining the blocking value of plastic sheets, comprising essentially a torsion balance and a clamping arrangement, is described. Determinations in lb./sq. cm. can be made with a maximum de- viation of +4%. 1441

53. Uniplast. Resistance to tearing of films of plastics. Materie, plastiche 23, 1957; Rubber Abstr. 35, no. 12:604(Dec., 1957); Packaging Abstr. 15:164.

This specification relates to a pendulum method for determining the required force in grams.

54. Voigt, W. Method for determining the causes of electrostatic charges on plastic films. Verpackungs Rundschau 8, no. 12: Suppl. 89- 92(Dec., 1957); B.I.P.C. 28:1146.

The film to be tested is rotated, in the form of an endless ribbon, over two high-speed rolls, and the static electricity generated is conducted to a globular condenser, similar to the Van de Graaff method, and measured by the voltage of the globe as a function of time. The accuracy of measure- ments depends on the surface of the rolls, the kind of collector used, and the constancy of'R.H. Under identical conditions, the precision of measurements is approximately +5%. It is also possible with this apparatus to differentiate between various causes of charge generation and to deter- mine whether the effectiveness of an antistatic chemical is due to a reduction in.the surface resistance,.arc resistance, or number of contact points between the film and the rolls.

55. Want a non-skid surface? Try pattern embossing of the paper. Paper Trade J. 143, no. 15:43(April 13, 1959); A.B.I.P.C. 30:190.

A new economical nonskid paper surface recently developed by Armour Research Foundation of the Illinois Institute of Technology comprises patterned embossing. The embossed paper bags can be used in packaging and shipping such'products'as livestock feeds, fertilizers, dry chemicals, food products, seeds, cement, plaster, and other building materials.

56. Welsh, Hewitt S. Toughness: new index for paper. Modern 'Packaging 31, no. 9:221-2, 225, 288, 292(May, 1958); A.B.I.P.C. 29:251.

The development of the new extensible type of kraft paper (Clupak) has made it necessary to develop a new method for performance evaluation which extends the test-to-failure standards now commonly used. The use of stress-strain measurement has reached the stage where it soon must be- come an-essential part of paper-control testing. The process for producing Clupak paper represents a means of controlling the energy-absorbing capaci- ty of paper. Accurate measurements of this property must be made not only to maintain quality control, but also to assist in the design of the end products made from the paper.

57. West Virginia brings revolutionary stretchable paper to market. Paper Trade J. 142, no. 6:28-9(Feb. 10, 1958); B.I.P.C. 28:1135.

A stretchable paper of unusual strength has been developed and is being produced commercially by West Virginia Pulp and Paper Co. under a 15 patent held by Cluett, Peabody & Co., Inc. The new paper is being manu- factured on a new $25 million at the company's Charleston, S. C. mill, capable of producing up to 225 tons/day. It is marketed under the trade-mark of Clupak, owned by Clupak Inc. Performance test on multi-ply sacks indicate that Clupak products can withstand two to three times more punishment than comparable sacks made of regular kraft papers.

58. Woodford, Reinold T. Developing a proper paper bag. Package Eng. 4, no. 6:46-7, 49-54(June, 1959); A.B.I.P.C. 30:770.

Factors entering into the development of a proper paper bag for any particular packaging use are discussed, including various important char- acteristics of the product to be packaged, the conditions under which the package is to take place, distribution and use conditions, and package properties or characteristics, such as strength,,ability to preserve contents, and adhesives used. Testing of the package materials and of the complete bag is also described. I

AUTHOR INDEX

Andersson, O., 1-2 IUmminger, 0., 52 Apple, W. W., 4 Vocilka, M., 47 Baker, W. P., 7 Voigt,.W., 54 Bakker, E. J., 11 Bull, T. H., 11 Welsh, H. S., 56 Woodford, R. T., 58 Carey, R. H., 9 Checkland, P. B., 11

Debus, E., 12 Dowling, T. E., 13

Frank, H., 16

Giersch, G., 17-18

Herrmann, 0., 20

Ihrman, C.-B., 1

Johansson, B., 23

Kaltenbach, J., 24 Kayser, K. H., 25 Kenan, R. H., 26 Krauss, R. A., 27-8

Mann, G., 29 IMyers, A. W., 31

Nierychlewski, T., 36 Nutkis, M. S., 9

Packaging Institute, 38 Park, .W. R. R., 39

Roder, H.-E., 43 Rogers, C. E., 31

Sabbioni, F., 44 Schmidt, W., 45 Schreiber, J., 46 Soukek, M., 47 Stannett, V., 31 Stewart, G. T., 48 Szwarc, M., 31

TAPPI, 50 IPST HASELTON

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