SIPCO

Glossary


Abrasion resistance: means the resistance of a printed surface to abrasion stress that results from two surfaces being in contact and slipped against each other.

Adhesive foils: or household folis; they  consist of polyolefins on the basis of LDPE, LLDPE and EVA-Copolymers.

Adhesive strength / Tesatest:  The adhesive strength of printers is their resistibility to forces that arise in case of tearing off a roll of adhesive tape from a printing surface. As, according to type and make of the adhesive tape, different values have been ascertained, this method can only be deemed as an orienting pretest. Tesatest-Schering method of testing: test medium = transparent, adhesive tape of 15 mm width; assessment: very good – no colour comes off; good – colour specks come off occasionally; conditional – larger parts come off; poor – the printing colour comes off completely.

Artwork: in the reproduction technology, it means the object that is to be reproduced – predominantly a photograph or a drawing.

Background printing colour: is a preprinted ground colour over which normally other colours are printed. It is also used as a decorative colour.

Backing-up: term for printing the second page of a plate cylinder (perfecting). It is the reverse of the first form.

Batches: also called "master batches". They are granulated materials inked with pigments. Batches are used in case of extrusions for manufacturing inked plastic films.

Blocking: is an unwanted adhering of the surfaces of films: the removing or blotting of the printing ink can have such a strong effect that the material lengths cannot be separated any longer when being uncoiled. The coils stick together to a "block", they are blocking. Caused by residual solvents, blocking in the coil comes up to about 30 per cent of all the complaints in the packaging printing. Causes are, among others: too low drying of the printing ink, wrong or missing binding agent, wrong climatic storing, too high coiling pressure, in case of alcohol colors, too high humidity, too high preparatory treatment of PE and PP films, blocking of finished bags by migrating lubricants.

BOPP: bi axially oriented polypropylene  films.

Cellophane films: characteristics are: very high water absorption, very low gas permeability (in dry condition), very good flavor density, very high tensile strength, very high stiffness (very good machine running), very good transparency, high gloss, high resistance to aging. Cellophane films are manufactured exclusively under the casting method by pouring in a precipitation bath. As a rule, cellophane films are further processed by coating or varnishing.

Co extrusion: films are manufactured by ejecting granulate material which is heated up to its melting point through sheet or tabular dies. When two or several films are ejected out of two or several dies at the same time and put together shortly after that, this procedure is called co extrusion.

Color additive: is the summarizing expression for all the progressive negatives or printing plates which are manufactured for color printing according to a colored art work and which belong together.

Color film: is a thin layer of printing colors by which the printing form in the printing machine is rolled down. / Film in the color photography

Colour separation: for the production of printing forms for mechanical color printing, the polychrome artwork is optically dispersed by means of the reproduction photography in the primary colors of the subtractive coloring machine.

Compound films: the purpose of film combination or the combination of plastic films with other materials is to obtain characteristics that cannot be realized with single films. In very many cases, the combination is used to achieve a low gas or water vapor permeability, in others heat sealing is possible or improved. Manufacturing method: laminating, stretching, varnishing, coating, co extruding, metabolizing.

COP: "coated oriented polypropylene". Polypropylene films coated and oriented by extending.

Corona-preparatory treatment: before they are printed or coated, the non-polar polyolefin films have to be changed in a way that their surface tension is heightened, and the corona preparatory treatment is the method used for doing so. In such a process, a corona discharging takes place between an electrode or an electrode system and a counter electrode built as a roller by a high-frequency high-voltage. There are numerous reports on the theory of corona discharging procedures in the specialist literature. But so far, a theory which comprises all the procedures responsible for changing polyolefin films and which is generally accepted has not been put forward.

Cromalin: is simulating the halftone dots with binding colors.

Deep freezing stability: means the resistible of frozen food packages to the conditions arising in deep freezers. It includes the resistance to condensation water, sufficient adhesion of printing colors films when separating frozen packages as well as no removing dents when defrosting.

Deep-drawing packaging: in the field of packaging, deep-drawing means the manufacture of hollow pieces with smooth surfaces as for instance bowls, cans, caps etc. One differentiates between cold and warm molding. In case of rigid portion packaging’s, polyvinyl chloride (PVC), polystyrene (PS), polyethylene of high density  (HDPE) and polypropylene (PP) are predominantly used. For thin-walled, not dimensionally stable packaging (mainly vacuum packaging’s), compound films of poly amide/polyethylene or polyester/polyethylene are normally used.

Delamination: means separating laminating compounds on the basis of faulty compound values.

EAN: European Article Number. EAN is based on the experience of UPC (Universal Product Code) for the US and Canada and can be exchanged with the north American one.

Electrostatic charge: when touching (friction, flowing) of electrically uncharged media with different dielectric permittivity, electrons migrate from one medium to the other. The emerging charge transfer is conserved when both media are separated  rapidly and may lead to the development of high electrostatic potentials. This can be eliminated by earthing, driving into conduction with metal fibers, ionization of the surrounding air or by using antistatic agents.

Erucic acid amide: is a lubricant; thermally more stable than oleic acid amide; of neutral odour and color; suitable for use in laminating films; migrates slowly.

Extruding: Latin extrudere = to drive/push out. This constant procedure is used for manufacturing semi-finished products i.e. films, sheets, pipes, profiles, coatings which have to be subsequently processed to finally get an article for use. Pulverized or granulated thermoplastic polymers are used as molding materials.

Film: is a transparent, thin plastic foil. The film used in photography has, in addition, an optically sensitive layer.

Fin seal: is the term of a folding seam in the packaging technology when manufacturing bags of plastic films and means that the inner side is sealed or welded against the inner side. In contrast to that, there is the lap seam, when the outer side is sealed or welded against the inner side.

First form printing: is – in contrast to perfecting or second printing – the first page of the plate cylinder.

Flexographic press prove: to be able to assess whether the color is correct, whether the intensity of the color is sufficient or whether the color has to be blended, you normally use various press proves.

Flexographic printing: (confer also > site). It is a rotary printing technnology used for packaging papers and films in which flexible artworks of rubber or plastic are used. High pressure process. The printing form is either a rubber stereo fixed at the printing cylinder or a gravured rubber cylinder. Flexographic printing is carried out on rotary machines so that high numbers of copies are attained in a short time. Today, special water and spirit soluble printing colors are used instead of aniline dyes in former days.

Foils: Latin folium = thin, tabular, flexible, windable lengths of metal (thinnest sheetings, e.g. foliated gold and aluminium, tin foil) or plastics (for instance cellulose acetate, PVC, polyethylene). You get metal foils by rolling or beating, plastic films by moulding, calendering or extruding. According to DIN 55405, a foil is a tabular, flexible metal or plastic packaging material. The minimum or maximum gauge depends on the material. Plastic films have a gauge of 1,5 mm. Foils of a higher gauge are mostly called plates.

Frontal printing: description of front printing a packaging film. In case of transparent films, very often opaque background colours or zinc white are used before a multicolour-screen printing is carried out in the following order: yellow, red, blue, black.

G.S.M.: g/m2; grammes per square metre.

Gas chromatography: gas chromatography facilitates the analysis of fabrics and the identification of residual solvents. The apparatus consists of so-called fractionating columns of high-grade steel. With a carrier gas which is pressed into the injection bottles prepared, possibly existing residual solvents are scavenged. In the process, the components contained in the test specimen are separated on the basis of their different distribution and absorptive characteristics. The components coming out of the fractionating column one after the other are ascertained by a detector the signals of which are registered by means of a potentiometric recorder. This graph is called chromatogram. Finally, the single peaks are compared with the ones of pure solvents (DIN 51401).

Gas permeability: is the permeability of an insulating layer for gaseous substances. The gas flow requires a difference of pressure and is characterized by the permeability coefficient (DIN 53380, DIN 535536, ISO 1399).

Gliding friction coefficient: the gliding friction coefficient µ is the ratio of  the resulting frictional force and loading.

Gloss: DIN 67530 – During this measuring, a reflector meter value is determined showing the gloss ability which a surface has due to its reflecting characteristics. For a better differentiation of the measured values, different irradiation angles are used according to the surface characteristics of the test specimen. In case of high-gloss surfaces, e.g. usually in  LDPE and PP films, a 20°-irradiation angle should be used with high measured values meaning high-gloss surfaces.

Haze: ASTM 1003. It is the method for measuring the transparency of films in which the haze of the transmitted light is ascertained. Thus low haze values show high transparency. Haze gives information regarding not only the quality of the surface but also the homogeneity of a film. Additives as for instance anti-blocking agents can increase the haze of films.

HDPE  = high density polyethylene; it is, according to DIN 7728, part 1, January 1988, polyethylene of high density manufactured under low pressure.

Heat seal resistance:  in case of films being printed by lateral reversing also in the sealing area, the colours have to resist the seal temperature. They must not stick to the sealing tools.

Heat sealability: in case of films being printed by lateral reversing also in the sealing area, the colours must be sealable. They must not be detrimental to the seam strength. That means, thermoplastic colours, which soften at sealing temperature and become solid again after having cooled down, have to be used. In contrast to this:  "heat seal resistance".

High-pressure polyethylene: is manufactured according to the high-pressure process (pressures up to 280 MPa and temperatures up to 275° C). PE-LD has a lower density of 0.9 – 0.928 g/cm3.

Hot Tack:  is the internationally used short term for the solidity of a seam which has been sealed hot and is still in hot condition. The solidity of the sealing seam in cold condition is in the range of 20 to 100 N measured at rolls of 15 mm width. Nevertheless, directly after the sealing process, i.e. still in hot condition, the solidity is at 1 to 10 N/ 15 mm which  means that limits are set to the working speed. This value can be hightened by special recipes.

Hygroscopacity: it is the ability to absorp water (see also water vapour permeability).

In line: says that several operations are carried out one after the other, i.e. without any interruption. An example for this is the manufacture of compound folis in case of which a foil is first printed by lateral reversing and after that laminated with a second foil.

Intaglio printing:  the printing technique in which the printing part of the printing form lies deepened is called inaglio printing. The printing colour is pressed into the depression whereas the surface remains without colour.

"J": - no entry.

Laminating: is the term for putting together two or more layers of similar or different materials by means of appropriate laminating agents. Laminating can be used with papers, fabrics, plastics, metals and further materials.

Layout:  means the draft for paginating (in letterpress printing) or mounting (in intaglio and offset printing). In case of simple printed matters, a draft is sufficient.

LDPE: is the letter symbol according to DIN 728, Tl. January 1st, 1988 for low density polyethylene manufactured under high pressure.

Legend: description of explaining texts in case of illustrations (drawings, photos), drafts, tables and maps.

Lithographic printing: it is a printing technology with printing plates which are approximately on the same level with the non-printing ones. Printing techniques: lithography, zinc plate printing, offset gravure.

LLDPE: is the letter symbol for linear low density polyethylene.

Lubricant: additive that improves the sliding behaviour of thermo plastics, mostly films. Additives are: oleic acid amide = short-time effect, erucis acid amide = long-term effect. Function: basically, lubricants are incompatible with the polymer used and therefore migrate to the surface of the film where they form a glideable layer. An overdosis can be detrimental to the characteristics both in printing and welding the film. The contents of the additive is limited by the BgVV [ = Bundesinstitut für gesundheitlichen Verbraucherschutz und Veterinärmedizin = Federal Institute for Consumer's Health Protection and Veterinary Medicine] formerly BGA [ = Bundesgesundheitsamt = Federal Health Administration] and the US Federal Drug Administration.

Metallizing: metal coat on metals, plastics etc. by thermal vacuum vapourizing.

Metallocene catalysts: are metal complexes from titanium to nickel. They are of growing importance in the manufacture of foils. These foils are ethylene copolymers with α-olefins which are produced by using metallocene catalysts. Characteristics are: very high resistance to thermal shocks, very good optical properties, low welding and sealing temperatures.

Migration: Latin migrare. The migration out of packaging materials into drugs and the one out of food wrappings into foodstuffs are of special importance. The total quantity or concentration of single substances, residual monomers, stabilizing agents  and other additives as well as softeners at plastic films is limited by orders or recommendations of the BgVV.

"N": – no entries.

Offset printing: indirect mechanized planographic printing method according to a rotational system which operates with a transmission roller.

Oleic amide: lubricant, thermally not very stable; rapid exudation in case of storing the granulates in the warmth; rapid migration. It is not very suitable for the manufacture of laminating foils.

OPA: oriented polyamide film.

Opacity: means the optical density. By means of a densitometer (device for scanning-testing optical densities of materials) the light intensity that falls through an optical layer is compared with the one of the light irradiated.

Opaque: Latin opacus = shady, dark; term for non-transparent, blurred.

OPP met.: metallized oriented polypropylene film

OPP: oriented polypropylene film.

 Orienting: thermoplastic films can be oriented in one direction (monoaxially) or in both directions (biaxially). With that you can achieve the intended film thickness, lower the gravity per square meter, improve the mechanical characteristics, highten the transparency, improve the low temperature stability and lower the gas permeability of films. Orienting is mainly used with polypropylene, polyester and polyamide films.

Overlapping seam: see fin seal.

PE: polyethylene

Permeability: Latin permeare = to go through, to pass; term for the permeability of possibly porous solids, thin partition in particular, for ceratin substances (e.g. gases, liquids, dissolved molecules, ions or atoms). Plastic films can be more or less  permeable for water vapour, O2 or flavouring agents, a fact which is important for food packaging for instance.

PET met.: metallized polyesterterephtalate foil.

PET: polyesterterephtalate.

PETx: here the x stands for pvdc (polyvinyl-alcohol/polyvinylidene chloride) layer.

Picture depth: description of the dark spots (shadow sectors) on a picture in contrast to the "lights" (light spots).

Pinholes: granulate or additive particles which have not dissolved in the melting bath.

plastics: the term "plastics" in the broadest sense of the word includes organic materials that are constructed as macromolecules and produced by converting natural products or by the synthesis of primary substances of crude oil, natural gas or coal.

Polyamide films: characteristics are: high water absorption, very good flavour and fat density, very good resistability to organic chemicals, very good high and low temperature stability. Oriented polyamide films have the highest tensile strength of all plastics, very high toughness, very low cold flow, the highest abrasion resistance of all plastics, very small range of welding temperature, excellent deep-drawing property and ductility, high transparency. Polyamide films are manufactured on chill-roll-plants or as Coex films blow-moulded. Polyamide flims can be oriented monoaxially or biaxially.

Polycarbonate films: characteristics are: very good high and low temperature stability, low extension, high stiffness, very good light resistance and ageing stability. Polycarbonate films are gaining in importance in the packaging industry.

Polyester films: characteristics are: good density values, very good chemical resistance, very good high and low temperature stability, very high mechanical stability and stiffness; polyester films that cannot be welded are mostly manufactured on chill-roll plants, a very high percentage biaxially oriented and laminated with a pvdc (polyvinylidene chloride) layer.

Polyethylene films: characteristics are: very low water absorption, very low water vapour permeability, very high gas permeability, high shock resistance, poor flavour density, very good weldability, low stiffness, low ageing stability.

Polypropylene films: characteristics are: very low water absorption, very low water vapour permeability, high gas permeability, poor low temperature stability of folis not oriented, high abrasion resistance, very low cold flow, sometimes very high ductility, very high transparency.

Polystyrene films: characteristics are: very high gas permeability, very low notched bar test toughness and extensibility, very high transparency, very high stiffness. Due to its very low flexibility, polystyrene film is almost exclusively used as deep-drawing material.

Polyvinyl alcohol films / ethylene-vinyl-alcohol films (PVA/EVAL): polyvinyl alcohol is water-soluble; it has very high tear propagation resistance and extensibiliy in wet condition, very high resistance to organic chemicals, very high fat and flavour density, very good light resistance and ageing stability. PVOH or EVAL films, which are known as insulating layers, are gaining more and more in importance for the packaging of food. They are predominantly manufactured under the coextrusion method.

PP cast: cast polypropylene film; OPP / PP cast compounds are used because of their good cost-effectiveness. Characteristics are, compared to OPP: lower tear propagation and puncture resistance as well as lower transparency.

Preparatory treatment: cf. corona preparatory treatment

Primary colors: it is the group of colors which can not be obtained by mixing colors. Almost all other colors (secondary colors) can be produced by the three primary ones. Primary colors are divided in red, blue and yellow and this division corresponds with the functioning of the human eye which perceives these colors separately and experiences light and dark particularly.

Printing carrier: it is the material (paper, plastic, sheet metal etc.) that is to be printed.

Printing form: it is the printing plate of which an imprint is made on the printing carrier. The printing form can be assembled of many separate parts. (letterpress printing) metal cylinder = intaglio printing, glass plate = phototype printing, rubber plate = flexographic printing, limestone = lithographic printing, tissue = screen printing.

Printing plate: the blocks for the reproduction of photographs in high-pressure are called printing plates.

PVC hard foils: characteristics are: low water vapour and gas permeability, very good fat and flavour density, low heat resistance, low UV permeability, very high stiffness. They are almost exclusively used in the field of deep-drawing.

PVC soft foils: characteristics are: very high tear propagation resistance and high notched bar test toughness, very low heat resistance, sometimes very high transparency. They are manufactured on calenders; their stiffness can be varied by the plasticizer contents according to special applications. On the basis of a legislation of the year 1987, the use of plasticized PVC foils on the food sector is limited.

PvdC films (polyvinylidene chloride): characteristics are: very low water vapour and gas permeability, very good flavour and fat density, relatively high UV impermeability, very low yield (high specific gravity 1,58-1,68 g/cm3). PvdC is predominantly applied to as a coating on carrier lines such as polyester or polypropylene.

Pyrolysis: thermal decomposition of organic substances. The pyrolysis is used for the reutilization of plastic waste materials.

"Q": – no entries.

Registration: means the registration of the precise condition of all the colours on the sheet or on the plate cylinder in case of multicolour printing. This is done by means of – among other things – register marks which are printed on the margin and have to be in all colours one on top of the other precisely.

Reproduction: means the reproduction of a draft or an original by manual techniques (reproduction graphics, wood engraving) or by means of photography.

Retouching: means the correction of drafts or negatives by means of opaques, matte lacquer, pencil etc. Among others, especially such drafts are retouched the reproduction of which high requirements are made on.

Rotation printing: Latin rota. Industrial printing process which is based on the rotation principle. The printing form is cylindrical and prints against a body that is cylindrical too.

Sandwich printing: term to describe laterally reversed printing on transparent films which are later laminated against a second length. Nevertheless, a paper or an aluminium foil can also be printed frontally in right reading and a transparent foil printed on it. In both cases, the printing lies between two substrates.

Scanner: facilities for electronical colour separation production for all printing methods. In contrast to the photo mechanical reproduction, in which the whole area of the photograph is exposed at the same time, the scanner scans and reproduces by the element.

Screen process printing: is a printing process by means of a fine-meshed net (screen) and a screen printing stencil, particularly for large sized leaves (posters). The simple printing principle of screen process printing lies in the fact that thick flowing colour is poured on the screen and spread by means of a sqeegee.

Screen: glass panes or foils with dots or lines in regular spacings (cross screens, line gratings) for the decomposition of a photograph in screen dots, e.g. for coarse newspaper printing 25-30 lines per centimeter; for smooth art paper or acetate films 60-80 lines are used. Therefore, a 60er screen would result in 60 x 60 = 3,600 dots per cm2. Today, flexographic printing uses 48 to 54er screens.

Setting-up: the setting-up time includes all the preparations regarding moulding material, processing machines and tools that are needed before the actual manufacturing process can start; it is important for calculation reasons.

Stretch films : are predominantly manufactured of PE-LLD. They are higly extensible and mostly transparent. The film thickness varies between 15 and 25 µ. They are used for wrapping up goods in the technical field and for transport securing by "stretching in" pallets. It is an alternative to a shrink film.

Tactile marks: are recurring marks in similar gaps on the packing length of film. In general, they are rectangles printed on to trigger off electrical impulses for the processing steps in the packaging machine. The gap between the tactile marks corresponds to the repeat length.

Telescoping: it is – in case of film rolls – the running off side of rolled reels due to very smooth films or very low reeling tension.

Tension test: DIN 53455/ISO 527 – Tearing resistance (N/mm2) and elongation at tear (in per cent) are ascertained by slow loading the test specimen at a constant test speed of 100 to 500 mm/min. Thereby, the tearing resistance shows the tear strength applied to the original cross-sectional area of the specimen. The elongation ascertained is the alternation of length applied to the free clamping length. The values are measured in extrusion direction of the film and transversely to it.

Thread counters: are sand magnifying glasses mostly magnifying five times. They are used to check screen lines, etchings (halftone etchings) and the register mark on the plate cylinder.

Titanium dioxide: chemical formula: TiO2. It is used as a well opaque white pigment in the manufacture of printing inks as well as in white-batching for the manufacture of  inked plastic films. There are two versions:(i) rutile-type – it is weathering resistant; (ii) anatase-type – in case of atmospheric influences, it has a tendency to chalking.

Transparency: is the term for measuring the optical permeability of paper, films, printing inks and other layers. Definition according to DIN 16544: it is measured as the ratio of transmitted to incident light. Code = opacity.

Two- (or more) length printing: the number of copies which can be cut out of one larger sheet of printing film or printing carrier.

UV absorber: it is a chemical which reduces the destroying effect of the ultraviolett portion of the sunlight.

Viscosity: means in the physical sense the inner friction of a liquid which arises either when pouring it out of a narrow pipe or from moving a solid in a liquid. Based on the consideration that the faster a liquid flows out of a vessel with a discharge the thinner the liquid is, flow cups are used for measuring the viscosity of low-viscosity inks. Therefore, the efflux time is considered as a parameter for its viscoelasticity and, in the narrow sense, a measure for its viscosity (DIN 53211).

Water vapour impermeability: for its determination the water vapor permeability is measured and the result is regarded as the measure for the impermeability of packaging materials. According to DIN 53211, water vapor permeability WVP is characterized by the quantity of water vapor in g which diffuses under fixed conditions through a test area of 1 square meter in 24 hours. The method of testing is used for ascertaining the water vapor permeability of platform things according to the gravimeter method, i.e. by using a vessel closed with wax. It is used in plastic films, papers, cardboards or textiles.

Welding: at an appropriate temperature, polyethylenes and polypropylenes are, like thermoplastic polymers, well weldable. In all welding techniques, the three influencing variables temperature, pressure and time are decisive for the quality of the weld seam and in a certain relation to each other. The following techniques are used: heat impulse, heat contact, undoing seam, ultra sound and high frequency. Corona preparatory treatment as well as too high inking and additive portions can impair the weld seam stability.

"X, Y,Z": – no entries.

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