DE1594127A1 - Pressure-sensitive adhesive tape for insulating purposes with a carrier based on polyvinyl chloride acetate copolymers - Google Patents

Description

Pressure sensitive adhesive tape for insulating purposes with a backing Based on polyvinyl chloride acetate copolymers The invention relates to an adhesive tape for the insulation and protection of electrical conductors with one Carrier based on a vinyl chloride acetate copolymer, which is within a wide temperature range, including temperatures below freezing point belong, and yet can also be used for purposes for which it exposed to high temperatures.

Non-vulcanized rubber-based insulating strips and friction strips are displaced by electrical insulation sheaths made from vinyl resin insulation strips by pressure sensitive adhesive strips with backing films made of plasticized Vinyl chloride homopolymers and copolymers. At normal usage temperatures, the Vinyl resin insulation strips well-balanced bending, stretching and restoring properties, so that irregular surfaces, such as wire ends, are wrapped tightly can and good electrical insulation can be achieved against weathering and chemical effects has excellent resistance. However, the previously commercially available adhesive tapes have at temperatures some inexpedient properties below freezing. When acting At lower temperatures, either the vinyl resin underlay or the pressure-sensitive one became brittle Adhesive coating lost its adhesive properties or the strip peeled off when unwinding from a roll.

Albeit plasticizers that reduce the flexibility of the vinyl polymer film cold weather improvement, and pressure sensitive adhesives have been proposed which led to streaks when applied to various other substrates, which could also be used at very low temperatures, so was a suitable one Combination of a plasticized vinyl resin underlay and a pressure-sensitive one Adhesive coating not yet known.

Because the effect of a certain plasticizer on a certain pressure-sensitive Adhesives cannot be predicted, consumers are from the manufacturers have been instructed to heat the vinyl resin insulation strip during use Do not expose below freezing point, except for a short time. Stripes, which are brittle at low temperatures, tear even after application, when they are used in their original state.

Have the vinyl resin strips proposed according to the invention in addition to the other useful properties - the well-known insulating strips Property of being exposed to temperatures down to -200 C for a long time and still at This low temperature can be unwound from a roll without a Stripping or detachment of the adhesive takes place, so that with them irregular Surfaces can be evenly enveloped0 The innovative adhesive tape has at these low temperatures sufficient elasticity, flexibility and adhesive strength, so that it stays tight and snug and provides effective electrical insulation around splices and wires at a temperature range of at least -20 to 870 C forms. These valuable and unique properties can be used according to the invention by means of a novel combination of a certain type of a plasticized one Vinyl polymer film backing and a certain type of pressure sensitive Adhesive coating can be achieved, this combination according to the invention for achieving these properties is essential.

The film base consists essentially of a stable, homogeneous one Mixture of 100 parts by weight of a vinyl chloride polymer and up to about 10 ß Vinyl acetate with 45 - 75 parts of a plasticizer, the main component of which is a is acylated polyester from glycol and a dibasic carboxylic acid. At least 90 mol% of the glycol content of the acylated polyester consist of at least such a glycol, the 1,2-propylene glycol, 1,4-butanediol or 1,6-hexanediol can, but not greater than 65 mole percent of the glycol, 1,2-propylene glycol are. There is at least 90 mole percent of the dibasic acid of the acylated polyester of at least one saturated aliphatic acid, the alkylene chains with 3-8 Has carbon atoms. The end groups of the polyester vsidn acyl groups, the Contain 2 - 18 carbon atoms and an average of at least 8 carbon atoms, while the average molecular weight of the polyester is between 2250 and 7000 lies. The total plasticizer of the film base has a block viscosity of 3000-20,000 centipoise at 250 C and an acid number no greater than about 3. A normally tacky and pressure sensitive adhesive cover comes with a surface of the film base united and firmly connected. The adhesive coating consists of a homogeneous mixture of (a) 40-60 parts of natural rubber, (b) accordingly 60-40 parts of butadiene-styrene synthetic rubber, (c) 80-115 parts of a pure thermoplastic terpene resin having a low acid number and a melting point of at least 600 C and (d) 3-16 parts of a comparable, oil-soluble, heat-convertible Phenol-aldehyde resin.

In order to increase the adhesion of the adhesive coating when the The strip is unwound from a roll, the surface of the film base should on which the adhesive coating is applied, initially with a primer coating be coated.

The vinyl polymer of the film base preferably consists of one Copolymer consisting of about 5 - 5% vinyl acetate and 97-95% Vinyl chloride. In practicing the present invention, this provides Vinyl chloride homopolymer products practically equivalent, but it is more difficult to process and absorbs the polyester plasticizer less easily. Mixed polymers Those made from more than about 10% vinyl acetate also have lower softening points and provide adhesive tapes with a lower heat resistance.

The film base must have at least about 45 parts plasticizer per 100 Parts of the vinyl polymer contain, if good flexibility and elasticity Temperatures below freezing point should be achieved. If more than 75 Parts of the plasticizer are used, the compatibility is reduced and If the film underlay loses numerous properties, such as strength, elasticity, Resistance to high temperatures and resistance to impact of solvents.

Up to about a third of the plasticizer can be made from almost a polyester equimolar proportions of 1,2-propylene glycol and a dibasic carboxylic acid of which at least 90 moles of at least one saturated aliphatic dibasic Acids with allyylene chains of 3-8 carbon atoms exist, while the polyester has an average molecular weight above 7,000. Another 5 - 10% of the plasticizer can consist of any other plasticizer, which the vinyl chloride copolymers, used as a backing film for pressure-sensitive adhesive tapes are effective softens and at temperatures up to about 870 C good electrical Has insulating properties.

The remainder of the plasticizer and preferably the only plasticizer the film base is the acylated polyester specified above, which is either a single polyester or a mixture of acylated polyesters. Preferably about 40 mol% of the glycol content of the polyester consists of 1,2-propylene glycol, which is much cheaper than any other glycol. If increased proportions of 1,2-propylene glycol are used, the proportions of total plasticizer must be used to be increased to vinyl polymer, so that the flexibility and elasticity at deep Temperatures are maintained, and if more than about 65 moles-1,2-propylene glycol are used, a sufficient amount of plasticizer cannot be used, without losing other properties.

Up to about 10 moles of other glycols, such as 1,5-butylene glycol, can be present in the acylated polyester without affecting the advantageous properties the pressure-sensitive adhesive strips proposed according to the invention are essential be affected.

Accordingly, up to about 10 mol% of the dibasic carboxylic acid can be used of the acylated polyester an aromatic, an unsaturated aliphatic or a cycloaliphatic acid.

The backbone of the acylated polyester is preferably through a saturated aliphatic monocarboxylic acid with about 12 carbon atoms limited. However, many other known monocarboxylic acids or d-erexi anhydrides can also can be used provided that the acyl groups average at least Containing 8 carbon atoms, vinyl films plasticized with an acylated polyester have, on average, a lower number of carbon atoms in which contains terminal acyl groups at high temperatures and humidities a lower resistance, so that the plasticizer to an inexpedient extent migrates into the adhesive coating of the pressure sensitive adhesive strip. The effect However, such a migration can only occur when used at temperatures below of the freezing point appear.

When the acylated polyester has an average molecular weight below 2250, it can be used in the pressure-sensitive adhesive coating in one must immigrate to such an extent that the strip is unwound from a roll can decoat at temperatures below freezing point, although the extent the hike is so small that at higher temperatures there is no difficulty appear. The same difficulty arises when the total plasticizer the film base had a block viscosity significantly below 3,000 centipoises at 25 ° C.

On the other hand, when the acylated polyester has an average molecular weight substantially above 7,000 or if the total plasticizer of the film base has a block viscosity substantially above 20,000 at 250 ° C., is the plasticized one Vinyl resin underlay somewhat inflexible and brittle, so that when Unwind of pressure-sensitive adhesive tape from a roll at very low temperatures Difficulties arise. If the total plasticizer of the film base has an acid number substantially above 3 are the electrical insulating properties of the strip defective and possesses the strip under high temperature and humidity conditions a lower resistance.

The preferred thickness of the backing film used is 0.076 51 mm. A thickness of about 0.25 mm is usually most useful.

Not just the components of the film base of the novel pressure-sensitive Adhesive insulation strips must be used to ensure flexibility and elasticity at temperatures below freezing point and the other useful properties are selected according to the principles of the invention, but also the constituents The pressure sensitive adhesive coating must be carefully selected. If, for example, the proportions of natural rubber or of bubadiene-styrene synthetic rubber in the pressure sensitive adhesive coating from the total rubber content of 40 - 60 ffi deviate significantly, the resistance strength will be significantly reduced against the migration of the plasticizer. This will make the adhesive cover soft and less sticky and especially at temperatures below freezing point a lower bond strength on steel.

The terpene resin of the pressure-sensitive adhesive coating is preferred present in an amount of at least 80 parts per 100 parts of rubber, otherwise the adhesive has poor adhesive strength. About 90-100 parts of the resin provide an optimal bond strength, while with more than 115 parts per 100 parts Rubber often have difficulty unwinding the strip from a roll, without this leading to a delamination. Good results are with terpene resin have been achieved which have melting points between about 85 and 1150 C.

Higher or lower melting resins can also be used. An example of this is a terpene resin that melts at 600 C and is known as "Piccolite S-60 "is on the market.

The pressure-sensitive adhesive should contain at least 100 parts of rubber Contain 5 parts of an oil-soluble, heat-reactive phenol-aldehyde resin. In the case of smaller quantities, it will come off a roll when it is unwound at temperatures below this the freezing point adhesive from the strip. If more than about 16 parts of the Phenol-aldehyde resin can be used, the adhesive can significantly affect adhesive strength lose if the strip is exposed to high temperatures for a long period of time.

The adhesives should also contain an accelerator such as zinc oxide, and a rubber antioxidant and may also contain minor amounts other adhesive resin, plasticizers or reinforcing fillers, such as carbon black, calcium carbonate, Sound or Contain silica. In a known way, by the The presence of modifiers affects the proportion of the terpene resin will.

Polyester A moles of adipic acid 2.12 1,2-propylene glycol 1.10 1,4-butanediol 1.52 Lauric acid 1.00 Acetic anhydride 0.50 The substances given above, acetic anhydride except, were under nitrogen in a vessel for 2 - 3 hours at one temperature heated by 2200 C, with part of the condensation water and 1,2-propylene glycol were continuously returned to the vessel. With continuous heating the condensation water was then distilled off at 2000 C for a period of 8-10 hours, whereupon the pressure was reduced to 10 mm Hg for about 1 hour until the acid number had fallen below 5. After releasing the vacuum and lowering the acetic anhydride was added to the temperature at 1600.degree.

The temperature then rose to 2000 for 1 hour under nitrogen C held, whereupon the pressure decreased to 10 mm Hg and an additional hour on this value was held until the acid number reached a value of about 2 - 3, The molecular weight of the acylated polyester product was determined from the intrinsic viscosity in methyl ethyl ketone and was 5900. That with a Brookfield viscometer measured block viscosity was 9,000 centipoises at 250 C.

Example 1 parts of a copolymer of 97 parts of vinyl chloride and 3 Parts of vinyl acetate (commercially available as "VYNW" 100 Polyester A 60 Epoxidized Soybean Oil as a stabilizing agent (commercially available as "Ferro 900") 1 organic inhibitor (im Trade as "Ferro 903") 1 Co-precipitated barium / cadmium soap of lauric acid (in trade as "Ferro 1820") 1 carbon black 1.5 5 tearic acid 0.5 The substances given above were mixed in a Sprout-Waldron ribbon blender for 50 minutes. The mixture was then melted in a Banbury mixer and there until reaching one Heated to a temperature of 1500 C and then placed in a 4-roll calender device, the rollers of which were kept at 1500 C, and there formed a film with a thickness calendered from 0.15 mm.

The film was first coated with a synthetic rubber resin primer, which had been dissolved in toluene and methyl ethyl ketone, primed. Almost 80% of the Primer consisted of a rubber-like butadiene-acrylonitrile copolymer. Almost 10 ffi consisted of a glycerol ester that was insoluble in light gasoline resinous extract from pine wood. About the same amount of p-tert-butylphenol-formaldehyde resin was also present.

The remainder consisted essentially of zinc oxide and salicylic acid.

The following was applied to this primer coat by means of a blade pressure sensitive adhesive composition up to a dry coating thickness of 0.0025 cm applied, whereupon the tape separated to a thickness of 1.9 cm and the obtained Strips have been wound into a roll.

Adhesive composition parts Smoked raw rubber heads 50 Rubber-like butadiene-styrene copolymer ("GRS-1004") 50 polymerized Terpene Resin (commercially as "Piccolite S-115") 90 Phenol-Aldehyde Resin (commercially as "Bakelite-14634") 12 zinc oxide 10 di-tert-amylhydrochnon (commercially as "Santovar A ") 2 carbon black 10 calcium carbonate 50 hexane 500 The adhesive was through homogeneous mixing of the rubber components and the powdery materials produced in a cold 2-roll rubber mill. The terpene resin became the matrix added in a Baker-Perkins multiple mixer with heating, followed by upon reaching a temperature of 1500 C the phenol-aldehyde resin was added. After erratic As the power consumption of the multiple mixer increased, the adhesive was cooled and added the hexane.

The Bakelite BR-14654 "used in the adhesive was a p-tert . -Butylphenol-formaldehyde resin that has an alkaline catalyst and more than 1 mole, between 1.5 and 2.0 moles of formaldehyde per mole of substituted phenol, had been made. The "Piccolite 5-115" is a polymerized ß-pinene resin with a melting point of 1150 C and an acid number of 0.

"GRS-1004" is a copolymer of 75 parts of butadiene and 25 parts Share styrene.

Roll the strip made by the procedure of this example after this had been kept at a temperature of -23 ° C overnight were easily unwound without the adhesive coming off, whereby the Adhesive tape will leave adequate adhesive strength at this temperature and firmly adhered to smooth surfaces. The adhesive strength at a temperature of 180 C was tested by placing the test strip on a polished steel plate was pressed on, both the strip and the plate prior to this attempt above Had been kept at this temperature overnight. To pull off of the 1.9 cm wide strip from the plate was at an angle of practical 1800 requires a force of about 620 g, with the plate moving in relation to the free end of the strip at a constant speed of 228 cm each Minute moved. The adhesive strength of the strip on steel was at normal room temperature 1240 g each 1.9 cm wide. Both values were excellent.

The strip was then folded in half around a copper wire 16 twisted, which has been shaped into a braided hair at a length of 3.8 cm was. After 60 days in a full-flow air circulation oven at a temperature of 900 C. and after cooling to room temperature, the splice was still completely flexible. The strip had thus been subjected to the "Weston Splice Test'1 which is often used is about the suitability of an insulating strip at high temperature, namely here at 87o C to examine.

The electrical dissipation factor (product of the scatter factor and dielectric cons aunt) was tested with a "General Radio" capacitance bridge according to the ASTM test method at a temperature of 900 C, a relative humidity of 50 ffi and at 60 vibrations per second determined, whereby a value of 0.67 was found. This low value is indicative of good electrical insulation properties.

When examining the strip with an Instron tensile tester at a speed of 30.5 cm per minute, the strip was at one temperature of 23 ° C and an elongation of 50% a tensile strength of 396 kg per 6.45 cm2. at at a temperature of -18 ° C and an elongation of 50%, the tensile strength was 1855 kg 6.45 cm each. Example 2 The film base used in this example had the the same composition as that described in Example 1, only its polyester plasticizer a combination of acylated polyesters made according to that described for polyester A. Process had been established. The polyester plasticizer of this example had the following composition: balance of: mole percent adipic acid 35.3 isophthalic acid 2.0 1,2-propylene glycol 21.2 1,4-butanediol 25.2 lauric acid 16.3 This film base, which had been calendered to a thickness of 0.15 mm was first primed and then with the primer and pressure-sensitive adhesive of Example 1 coated. Roll out these strips, which are kept overnight at a temperature of -23 ° C, could easily be rolled up at this temperature be without the stripe stripped. During the examination according to the method described in Example 1, it was found that the adhesive strength on steel at room temperature 1240 g each 1.9 cm wide and at a temperature of 180 C was 950 g. At a temperature of 900 C the loss factor was 0.424. The strip was also passed the "Weston Splice Test" at 900 C with good results subject.

Example 3 parts of polyvinyl chloride 100 polyester A 45 non-acylated Polyester (commercially available as Paraplex G-25 ") 10 di-2 -ethylhexylphthala t 5 dibasic Lead phthalate 2 stearic acid 0.5 carbon black 1 These substances were made according to the example in 1 method described homogeneously mixed and up to a thickness of 0.015 cm calendered, whereupon the film with the primer described in Example 1 and pressure sensitive adhesive coated and formed into strips 1.9 wide cm, which were then wound into a roll.

"Paraplex G-25n is a polyester made from practically equimolar proportions 1,2-propylene glycol and sebacic acid. The average Molecular weight, determined from the intrinsic viscosity in methyl ethyl ketone, is about 8,000.

Due to the presence of the monomeric plasticizer, namely di-2-ethylhexyl phtahlate, the advantages achieved according to the invention are not achieved in small proportions impaired, which is when the tests described in Example 1 are carried out results. After the strip is stored overnight at a temperature of -23 ° C it could easily be unwound from the roll without the The adhesive strength on steel was at a temperature of -18 ° C 374 g per 1.9 cm width. At 23 ° C. this value was 900 g. The loss factor at 900 G was 0.454. The strip also passed the Weston Splice Test on one Subjected to temperature of 90 ° C with good results.

The proposed according to the invention, pressure-sensitive adhesive strip can be used not only for electrical insulation purposes but also for other purposes will. This strip is e.B. an effective substitute for lacquer and wax coatings on the running surfaces of snowshoes and tobogganing. Since the invention the proposed strips remain pliable and elastic even at low temperatures, they resist to a much higher degree than the known vinyl resin insulating strips tearing open or tearing off.

Unless otherwise stated, the parts given here are proportions and percentages units of weight.

- patent claims -

Claims (2)

Claims: 1. Electrical insulating tape with a film-like plasticizer-containing carrier, which consists of (1) 100 parts of a polymer of monomers, which have at least 90% vinyl chloride and (2) 45-75 parts by weight of a plasticizer from a condensation product that is formed by reacting an aliphatic glycol produced with a dicarboxylic acid with the addition of an aliphatic monocarboxylic acid has been made, and that with a water-insoluble pressure-sensitive Resin-rubber adhesive layer is provided, characterized in that the The main component of the plasticizer is an acylated polyester made from a glycol and is a dioarboxylic acid, at least 90 mol4 of the glycol being at least one of Compounds are 1,2-propylene glycol, 1,4-butanediol or 1,4-hexanediol, but not more than 65 mole percent of the glycol consists of 1,2-propylene glycol, and at least 90 Mol% of the dicarboxylic acid from a saturated aliphatic dibasic carboxylic acid with an alkylene chain of 5-8 carbon atoms; that the polyester Acyl end groups with 2-18 carbon atoms and an average of at least 8 carbon atoms and an average molecular weight of 2250 7 QOO, and that the plasticizer has a blocking viscosity of 3,000-20,000 cp at 250 ° C and has an acid number of not more than 3. 2. Pressure-sensitive adhesive tape according to claim 1, having a bond strength promoting primer layer between the film backing and the adhesive coating, characterized in that the pressure-sensitive adhesive coating consists of a homogeneous mixture of (a) 40-60 parts by weight of natural rubber, (b) accordingly 60-40 parts of a synthetic butadiene-styrene rubber, (c) 80-115 parts a pure thermoplastic terpene hydrocarbon resin with a low acid number and a melting point of at least 600 ° C and (d) 3-16 parts of a compatible oil-soluble thermally reactive phenol aldehyde resin.