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Knowledge Adhesion-abc

In our glossary you will find helpful information and everything worth knowing about the subject of adhesive tape.

Adhesion

This term is identical to adhesive force. It refers to the force that is required to remove a tape again from the surface to which it had been adhered. To archieve comparable results it is tested according to set standards in laboratory testing: A 25mm wide strip of adhesive tape is adhered to a polished steel plate, which is then and peeled off at a constant, fixed speed at an angle of 180°. The force required is measured in kp or N.

Acrylic-adhesive

Polymerized acrylic ester monomers are the chemical basis of acrylic adhesives. Usually synthetic resins are also added. These adhesives can be either dissolved in solvents or in aqueous dispersions. The outstanding properties of acrylic adhesives are resistance to ageing and high temperatures. For the most part they are also resistant to UV radiation and oxidation.

Resistance to ageing

All tapes age, i.e. they change their characteristics to a greater extent the longer they are stored. These chemical and physical changes do not necessarily reduce the usefulness of the tape. For some adhesives higher cohesion values may appear after ageing . No measurable change in the properties of the tape should occur within the first 6 months after production. If, after 12 months, no negative change of the properties is measured, it is referred to as a good resistance to ageing. Most of our tapes meet these criteria and fully serve their purpose, even after several years of storage.

Initial tack

Some adhesives, especially those based on butyl and acrylic, only reach their highest bond strength after hours or even days. However, since often the initial bond needs to be very high, other adhesives are used (hot melt, solvent based, natural rubber, synthetic rubber, silicone adhesive).

Butyl - Adhesive

This adhesive consists of a mixture of natural rubber and isobutylene embedded with soot particles. A high degree of cross linking of our tapes is archieved by hot calendaring. Thus, the highest durability and suitability for long-term outdoor use is given. Special advantages of our butyl adhesives are also high resistance to UV radiation and oxidation as well as the unique properties of cold welding. ==> cold welding

Density

=> volume weight. The quantity of material in relation to a volume unit. The density is expressed in weight of a cubic meter (= volume weight). For adhesive tapes only the density of foam backings is of relevance."

Tightness

This refers to the property of a material to offer resistance against the passing through of foreign substances and energies. Of great importance in the field of tapes is the tightness of the backings agains chemicals, moisture and gases.

Dispersion

This refers to the fine dispersion of very small solid bodies in water. In the field of tapes adhesives consisting of acrylic and acrylate dispersions are of great importance.

Breakdown Voltage

The resistance an insulating material offers to electric current until breakdown. The breakdown voltage is measured in volts.

Electrolytic corrosion factor

This is the effect of a possible corrosion a tape has on another material. To measure the factor of corrosion, the adhesive tape is adhered to copper foil. Should no corrosion occur, the electrolytic corrosion factor of the tape is designated 1. At the slightest corrosion the corrosion factor is reduced below 1.0. The value is decreased the further the magnitude of the corrosion increases.

Non-Woven

Non-Woven fabric consists of natural oder synthetic fibers lying only in the longitudinal direction. Through adhesion or heat and mechanical pressing a composite is created. (e.g. paper handkerchiefs)

Flat Crepe Paper

Is required for masking during painting, for bundling, marking, etc. Crepe paper consists of paper, which is usually impragnated or surface coated. These tapes are usually not thicker than 0.2mm max. Crepe paper can be expanded up to 15% of its original length to its breaking point.

Primer

Due to their chemical and physical properties the adhesive anchoring on many backing materials is inadequate. Therefore in a lot of cases a primer will be applied before the adhesive coating.

Hotmelt-Adhesive

These adhesives consist of dry, non-adhesive synthetic resins. Once melted at high temperatures from 130 ° C to 180 ° C, they keep a high degree of tack and adhesion after cooling. Benefits of Hot-Melt-adhesives are their very high bond strength at normal temperatures. Their disadvantages lie in their sensitivity to temperatures above 40 ° C and UV radiation, as well as their lack of resistance to plasticizers and low ageing resistance. Through additives, these negative characteristics are reduced. For example, this allows for hot-melt adhesives to be largely resistant to plasticizers.

High Crepe Paper

This refers to a paper tape, usually with a thick layer of adhesive and no coating on the surface,that can be expanded at least by 40% of its original length until its breaking point is reached.

Insulating Classes

Tapes in the electrical sector are classified in temperature classes from 'Y' to 'H' according to their longterm continuous heat resistance. The individual classes are as follows: - Class Y is a continuous temperature of 95°C\n - Class E is a continuous temperature of 120°C\n - Class B is a continuous temperature of 130°C\n - Class F is a continuous temperature of 155°C\n - Class H is a continuous temperature of 180°C\n Conclusions to other technical properties of the tapes cannot be made from the insulating class alone.

Insulation

This refers to the partial or complete shielding of an object from external influences such as humidity, heat, cold, noise, dust and electricity.

Calender

Machine with heavy, usually heated cylinders arranged in succession or one above the other, with which surfaces of backing materials are smoothed and the adhesive layer is rolled out to the desired, precise thickness. Also films with the highest tensile strength are produced on calanders by stretching, often biaxially. (e.g. strapping tape.)

Cold Welding

Butyl adhesives possess the property to adhere to both to themselves, as well as nearly to any other surface immediately and are absolutely not removable.This is called a cold weld. Even with slightly dirty and slightly damp surfaces a good bond is still possible. On siliconized surfaces however cold-welding is not possible.

Rubber - Adhesive

These consist of natural rubber, which is ground and then mixed with a solvent such as gasoline. It will dissolve the rubber and a tough adhesive is created. High adhesion and good shear strength characterize this adhesive. Disadvantages: Average temperature and ageing resistance as well as a lack of resistance to UV radiation and sensitivity to low (below 10°C) and elevated (above 50°C) temperatures.

Adhesive Force

This term is identical to adhesive force. It refers to the force that is required to remove a tape again from the surface to which it has been adhered. To archieve comparable results it is tested according to set standards in laboratory testing: A 25mm wide strip of adhesive tape is adhered to a polished steel plate and then it is peeled off at a constant, fixed speed at an angle of 180°. The force required is measured in kp or N.

Stickiness

Usually a material very "sticky" to the touch has no inner stability, I. e. words no cohesion. Honey is a good example for this. Nevertheless, very often for rough, uneven and dusty surfaces a very sticky material is needed. The stickiness is measured by the ball test.=> ball test

Cohesion

=> shear strength. Force needed to split the layer of adhesive. Adhesives with low cohesion leave residue when detached from the substrate. Particularly undesirable in masking tapes."

Corrosion

Starts on the surface of the substrate and eventually leads to the complete destruction of solid materials due to the exposure to gases, acids and alkalis.

kp

Abbreviation for kilopond. 1kp is the equal to the magnitude of the force exerted on one kilogramm of mass.

Ball Test

To determine the stickiness / tackiness of an adhesive a steel ball is rolled from an inclined plane onto the adhesive side of the tape. The shorter the distance until the ball stops rolling, the more sticky the adhesive is. The ball test is measured in cm. The test is very controversial, because no accurate data can be collected.

Storage

Attention needs to be paid, that the tapes are stored in a dark environment (no direct exposure to sunlight) at a temperature of approximately 18 ° C. Most tapes have good resistance to ageing, so this factor plays a lesser role.

Laminate

=> composite material.

µ

Letter of the Greek alphabet, referring to a unit of measurement, playing a role especially in the field of thin backing films this. (μ = one thousandth of a millimeter/ 0.001mm)

N (Newton)

Abbreviation for Newton. One Newton is the force that accelerates a mass of one kilogram by one m per one second².

Opaque

Meaning not translucent or transparent. Especially important with UV resistant tapes.

PE (Polyethylene)

Abbreviation for polyethylene, used as backing film for tapes. PE plastic films are soft and extremely elastic, posses a high density, but only a low tensile strength. Polyethylene is very sensitive to UV radiation. Exposed to daylight, polyethylene rots without leaving residues. Therefore, this material is classified as environmentally friendly. PE films are resistant to solvents. In the field of tapes, they are important for the production of surface protection films with low adhesion, for underground pipe insulation, as well as screen printing.

PET-Foil

Polyester (PET) film is characterized by very high tensile and tear strength. Even thin films of only 0.025mm for example, are hard to tear. In addition, the material is very resistant to high temperatures, alkalis, acids, oils and many solvents. Therefore, PET films play a very important role in the tape sector, especially for screen printing and electrical applications.

Polyimidefilm

Polyimide-film is of brown-translucent color. It is highly heat resistant and extremely durable. Polyimidtapes find frequent application in the electrical industry.

PP-film

PP-films are used in a large scale to produce packaging tapes. PP tapes are resistant to alkalis, acids and solvents. They are very tear resistant and furthermore exceptionally cheap. Since PP films are very sensitive to UV radiation, these films rot outdoors without leaving a trace. For this reason, PP film tapes are considered very environmentally friendly. Aluminized PP foil tapes are used for mounting insulating materials.

PU (Polyurethane)

PU is short for polyurethane plastic. As backing material in the form of PU foam it plays a major role. Moreover, PU films and foils of extreme extensibility and tear resistance are produced. PU foam is used as carrier for double-sided mirror mounting tape.

PVC-film

PVC films are often used as backing for adhesive tapes. In the packaging industry rigid (hard) PVC films are used while sof PVC is being used for insulation purposes. Rigid PVC films are highly tear-resistant and easily printable. Basically PVC films have good UV stability. Tapes with PVC backing are therefore used frequently in outdoor applications.

volume weight

=> volume weight. The quantity of material in relation to a volume unit. The density is expressed in weight of a cubic meter (= volume weight). For adhesive tapes only the density of foam backings is of relevance."

Tear Strength

In general, the tensile strength is determined by a tensile testing machine. Therefore both ends of a 25 mm wide tape are firmly clamped, after which one of the ends is slowly drawn away with a standardized speed, until the tape breaks. The force which is needed for that, is measured in Newton (N). The adhesive does not matter in this test. Large variations occur often however, as irregularities due to fabrication may occur. For this reason, as a rule, an average of at least 20 measurements of tensile strength is taken.

Resilience

This refers to the tendency of a flexible backing to shrink back to its original length after extension. This is especially the case with PP film backings.

Shear Strength

The term of the shear strength of an adhesive is almost identical with cohesion: Shear strength is the adhesiveness or the bond strength of the tape when put unter load, usually at elevated temperatures. Thus, the shear strength can be measured and defined by units of weight time. The procedure is as follows: An adhesive tape portion is bonded with one of its ends to a rigid, fixed and polished steel plate. Subsequently, on the other free end of the tape is a weight attached. By changing and increasing the weights it can now be determined, up to which maximum weight the adhesive sticks on the steel plate without the adhesive tape being drawn down by the weight, slowly slipping down, "shearing" and finally dropping. The same experiment at different temperatures gives information about the behavior (resistance) of the adhesive at different temperature effects.

Siliconizing

Silicone is a non-metallic compound, the second most common on earth after oxygen, even if only in combination with other substances. Silicone compounds are dissolved in solvents as well as dispersions. Dissolved they are applied to paper and films, then cross linked under high pressure. Siliconized surfaces are very smooth and slippery. Common adhesive do not stick on silicone. For this purpose a silicone adhesive is required.

Silicon-Adhesive

Silicone adhesives consist of synthetic polymers with rubber-like properties (elastomers), which together with an adhesive organic silicone compounds form an adhesive with resistance to high temperatures as well as extreme cold. Silicone adhesive is the only adhesive which adhers to siliconized film and paper.

Splicing

Common in the film-, paper- and cardboard industry, splices are used in these industries to make paper- or film webs endless. For this, various splicing tapes are used.

Telescoping

Caused by strong internal pressure, the tape funnels out sideways, telescopically, as the upper layers of tape and the core below block the way of the lower layers. This deformation does not affect the adhesive properties. It is caused by too tight winding during the production of the tape or by a subsequent swelling when exposed to high humidity unprotected.

Temperature Range

With rising temperatures, the tack increases and reduces the adhesive strength of tapes (except thermosetting adhesive). While falling temperatures reduce the tack, the adhesive strength increases only in medium temperatures from 18°C to 25°C. If tapes are kept in cold storage, they must be returned to room temperature of approximately 20°C before processing.

Backing

The term backing (or carrier) defines the material on which the adhesive is applied, typically films, fabrics or paper.

liner

Liner are usually films or smooth papers, which have been siliconized one- or double-sided and thus repell adhesives. A liner must be used, if the adhesive is very aggressive, e. g. on butyl adhesive used for cold welding tapes. For double-sided adhesive tapes, the release liner must be siliconized on both sides.

UV - radiation

UV rays are contained in sunlight. In rubber and hot melt adhesives they cause a chemical reaction that can destroy the molecular structure within a short period - in extreme cases within minutes. Tapes with these adhesives must therefore always be stored in the dark. Direct sunlight or outdoor exposure must be avoided. Acrylic and butyl tapes have an extensive resistance to UV radiation.

Composite material

Different carriers are joined inseparably (laminated), the addition of the respective features results in an optimal composite material.

Cross linking

Refers to the chemical modification of the molecular chains of substances linking the originalmolecular chains into a three-dimensional network. The goal of cross linking adhesives is to control the adhesion and cohesion of the adhesive and to increase the resistance to chemical and thermal influences.

Thermosetting

This is the special property of an adhesive to increase hardness and adhesion under the influence of heat. Applications for thermosetting tapes lie in electrical engineering, the production of capacitors, and coil winding.

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