DE1063452B - Process for the production of carrier material from paper impregnated with elastic polymers for pressure-sensitive adhesive strips and plasters - Google Patents

Description

Pressure sensitive adhesive strips are used extensively in the art, for example for Covering of body parts that have been given a new coat of paint or have their coat of paint touched up shall be. Such pressure-sensitive adhesive strips should have a high degree of elongation, good elasticity, high Edge strength, good tensile strength in wet and dry condition and great splitting resistance exhibit. They should also be able to be laid around curved surfaces without tearing. Often with a Paint to be provided body after covering wet sanded with sandpaper, and therefore In particular, the pressure-sensitive adhesive tapes must have high wet strength. Later need the pressure sensitive adhesive tapes Let it peel off from the backing without splitting the carrier for the pressure-sensitive adhesive.

It is already known to use paper backing for pressure-sensitive adhesive strips with aqueous latices made from elastic copolymers, such as butadiene-styrene or butadiene-acrylonitrile, to be impregnated and thereby compressed and to solidify. If a paper is treated with such an aqueous latex, the edge strength suffers The elongation and flexibility of the paper, albeit an increase in the resistance to splitting is achieved.

It is also already known to increase the strength of papers by adding phenolic resin-rubber combinations to improve the paper stock in the Dutch. The paper stock can, however, in the Dutch only relatively small amounts of such combinations are added to achieve a high Wet strength and increased splitting resistance, as required for pressure-sensitive adhesive tapes, are not sufficient. '

According to the invention, a carrier material made of paper impregnated with elastic polymers for pressure-sensitive adhesive strips and plasters with high wet strength and increased splitting resistance is obtained by using a fiber fabric with an aqueous dispersion containing a larger amount of an elastomeric copolymer of butadiene or another conjugated butadiene with a phenol-reactive N-containing monomer copolymerizable with the diene, such as an unsaturated nitrile or acrylamide or vinyl pyridine, and a small amount of not more than 7%. based on the solids of the impregnating agent, a thermosetting, water-dispersible or soluble phenol-aldehyde resin are impregnated and then dried.

It has been found that when a small amount of a phenol-aldehyde resin is added, from about 0.5 to 7 percent by weight, based on the solids of the impregnating agent, to the latex of an elastomeric copolymer an impregnating agent is obtained which corresponds to the

procedure
for the production of carrier material
made with elastic polymers
impregnated paper for pressure-sensitive adhesive strips and plasters

Applicant:

Charles Bartell,
Arlington, Mass. (V. StA.)

Representative:

Dr.-Ing. A. v. Kreisler, Dr.-Ing. K. Schönwald,
Dipl.-Chem. Dr. phü. H. Siebeneicher
and Dr.-Ing. Th. Meyer, patent attorneys,
Cologne 1, Deichmannhaus

BeflTisprudite priority:
V. St. v. America May 26, 1955

Charles Bartell, Arlington, Mass. (V. St. A.),
has been named as the inventor

so impregnated and then dried paper has an unexpectedly large elongation, a imparts high flexibility and edge strength, great wet strength and high resistance to splitting. The tensile strength of the paper in the wet state is up to 700% and the splitting resistance is whole significantly increased without sacrificing elongation, flexibility and edge strength. If significantly larger amounts of phenol-formaldehyde resin, for example from 10 to 20 percent by weight, used, the wet strength and the splitting resistance are increased, but at the same time they decrease Elongation, edge strength and flexibility in undesirable ways.

In order to demonstrate the increased wet strength, paper strips which were produced according to the invention were used were compared with paper strips that - with a comparable latex dispersion, but without the addition of phenolic resin, have been impregnated. These paper strips were provided with a pressure-sensitive adhesive layer on one side and wound into rolls. Then the samples were stored for 3 days at 65 ° C and 100% relative humidity. It

909 607ßß

It was practically impossible to use the strips made with the impregnation agent without the addition of phenolic resin without splitting or tearing off. On the other hand, the stripes whose base was treated with the impregnating agent containing phenolic resin, easily and without any Handle the split.

The paper strips provided with a pressure-sensitive adhesive layer were glued to a base and then Wet sanded next to and on the edge of the pressure-sensitive adhesive tapes, so did those with a phenolic resin-free impregnation treated tapes absorbed water, softened, and tore to pieces when peeled from the backing. The strips produced according to the invention (impregnating agent with phenolic resin addition) could be used easily and completely peel off from the surface.

Porous and absorbent paper made of wood, rag or rope fibers or other natural materials is used as the carrier material or synthetic fiber material (e.g. Kraft paper) is used. The paper can be smooth or creped, be curled, embossed or otherwise treated so that bumps or undulations result through which increases the stretchability of the underlay film.

The elastic copolymer suitable for use in accordance with the invention must contain nitrogen. It preferably contains a nitrile group and is a copolymer of butadiene or another conjugated diene and an unsaturated polymerizable nitrile, e.g. B. acrylonitrile, α-methacrylonitrile, α-ethacrylonitrile, α-isopropacrylonitrile, etc. The unsaturated nitriles can be replaced in whole or in part by nitrogen-containing monomers that react with phenolic resin, such as acrylamide or vinylpyridine. The nitrogen-containing monomer, preferably acrylonitrile, should make up at least 5% and preferably not more than 50% of the copolymer in order to ensure a rubber-like polymer. Other elastic, ie rubber-like polymers or copolymers such as butadiene-styrene, natural rubber, vinyl chloride, copolymers of vinyl chloride with other monomers such as vinyl acetate, vinylidene chloride, etc., chloroprene and similar elastic polymers can be mixed with the nitrile copolymer and the reactive phenolic resin without disturbing the desired interaction. The acrylonitrile copolymer and the reactive phenolic resin lead, depending on the amount in which they are contained in the impregnating agent, to an improvement in the properties; if not at least 10 ° / ₀ of the elastomeric component of the impregnant are made from acrylonitrile copolymer, only a small advantage is obtained.

Considerable amounts of the acrylonitrile copolymer are preferably used in the composition, d. that is, at least about half of the elastic component of the impregnation agent should consist of it. Optionally, polymers with more than two monomers, one of which is a nitrogen-containing polymerizable Monomer is to be used in equal amounts.

The phenol-aldehyde resin, the impregnating agent in the above-mentioned, small amounts is added, must be reactive when heated or when activated by catalysts, it must be soluble or easily dispersible in water at a neutral pa value or above and must be stable if it is mixed with the latices to produce the impregnation agent. Such reactive phenolic resins are for example by alkaline condensation of formaldehyde and phenol in the ratio of 1.1 to 2.25 moles of formaldehyde per mole of phenol obtained,

the reaction being terminated before the reaction is complete. Substituted phenols, such as resorcinol or cresol, and aldehydes other than formaldehyde, such as acetaldehyde, can also be used. The _pH value of such resins is usually 7 to 11, the resins may be self thermosetting or may need to cure conventional catalysts. Phenolic resins which require special treatment or the presence of other ingredients in order to become thermally active, such as novolaks, can also be used as long as a resin is formed in the impregnant which e.g. B. by adding further formaldehyde from hexamethylenediamine is water-soluble or water-dispersible and heat-active. Such resins are also referred to by the term "heat-active phenol-aldehyde resins".

Other ingredients commonly used in latex waterproofing agents can be found in the Impregnation mixture according to the invention can also be used. These are, for example, common antioxidants, such as hydroquinone monobenzyl ether, to stabilize the polymers during curing and aging, pigments, dyes and the like.

According to the invention, the paper is impregnated with a sufficient amount of latex so that about 30 to 150 weight percent dry solids of the impregnation agent, based on dry, unimpregnated No paper. After the impregnation, the saturated paper is preferably heated in order to Cure resin and achieve at least partial polymerization. Either long curing times at low temperatures or short ones at high temperatures can be used Apply temperature.

Wet strength can be used as a measure of cure; as the desired degree of hardness, curing is considered to be sufficient to provide an at least 25 ° / ₀ sodium increasing the wet strength of the substrate after curing as compared with the tensile strength prior to curing to cause. The substrates are preferably cured for 10 to 60 seconds at temperatures of 121 to 204 ° C. Such hardening usually leads to an increase in the wet strength of the substrate by a few 100% of the initial tensile strength. In the case of only slight curing during production, the curing can be completed by using the pressure-sensitive adhesive tape at higher temperatures. This in-use hardening property is often very desirable.

The examples illustrate the production according to the invention of impregnated substrates for pressure-sensitive adhesive strips and plaster explained. The invention is not limited to these examples. Be for comparison examples of products made by known processes are also given. Unless otherwise stated, are all parts and percentages parts and percentages by weight.

example 1

The following samples were prepared to allow comparison between backings made in accordance with the invention were manufactured and therefore only contain small amounts of phenolic resin, and underlays with impregnating agents made without phenolic resin.

Sample A

13.6 kg of absorbent crepe paper were made with 80 percent by weight (based on the dry weight) of a latex mixture from 60 parts (based on the dry weight) of a copolymer of 75% butadiene and 25% acrylonitrile with a Mooney viscosity of about 40.40 parts of a copolymer of 50% butadiene and 50% styrene with a Mooney viscosity of about 40 and 1 part hydroquinone monobenzyl ether as an antioxidant

saturated. The impregnation was carried out with conventional nip rollers and the wet plate in one Feston-type air circulation oven dried.

Sample B

13.6 kg of absorbent crepe paper was made with an equal weight of a latex mixture of 70 parts a copolymer of 75% butadiene and 25% acrylonitrile with a Mooney viscosity of 40, 30 parts of a Copolymer of 10% butadiene and 90% styrene (a brittle copolymer) and 1 part of the same antioxidant saturated as in sample A. The base was dried in an air circulating oven.

Sample C

13.6 kg of absorbent crepe paper with 80 weight percent of a latex mixture of 60 parts of a Copolymer of 75% butadiene and 25% acrylonitrile with a Mooney viscosity of 40.37 parts of a copolymer of 50% butadiene and 50% styrene with a Mooney viscosity of 40.3 parts of a thermoset Phenol-formaldehyde resin (made by reacting 2 moles of formaldehyde with 1.0 mole of phenol under alkaline conditions and termination of the reaction in a polymerized, but still water-soluble state) saturated. Impregnation and drying were carried out in the same manner as for sample A. It was in one cured separate air circulation oven for 1 minute at 190.5 ° C.

The samples were then treated in the usual way with a normally tacky and pressure-sensitive adhesive the end

Raw rubber 100 parts

Dehydrated resin 90 parts

Aluminum hydrate 90 parts

Mineral oil 30 parts

Antioxidant 2 parts

ίο Coated and rolled into rolls of pressure sensitive adhesive tape.

The table below compares the properties of the products thus obtained. To check the Resistance to splitting off, a roll of strip was placed on an unwinding device to control the tear-off force measures. The unwinding speed of the device was then accelerated until the Strip pad takes place, and then read the tear-off force at a standstill. Resistance to secession in the dry state is obtained after aging the samples for 6 days at 65 ° C and 35% relative humidity was. The wet splitting resistance was read after 3 days of the samples aged at 65 ° C and 100% relative humidity.

Strips which, when tested for resistance to splitting off in the dry state, have an adhesion to the Those with a backing of 124g / mm are as excellent, those with 102 g / mm as good, those with 79 g / mm as medium and to regard those who split off at lower values as bad.

Table I.

Example no. Acrylonitrile
salary
Vo Resin content
7o tensile strenght
wet
kg / cm Abspaltw
dry status
wet edge
wear and tear
kg stiffness
mg / mm A.
B.
C. 60
70
60 0
0
3 0.380
0.380
2.53 middle
very good
very good bad
bad
very good 1.7
0.86
1.5 1.28
2.0
1.28

Example 2

The following tests were carried out to make a comparison between strips made according to the invention different types and amounts of elastic polymers and from different types and amounts of phenol-aldehyde resins were made to allow and a comparison between strips made according to the invention and those with similar impregnants with much higher phenol-aldehyde resin content.

Sample A

nitrile with a Mooney viscosity of 40, 18 parts of a copolymer of 50% butadiene and 50% styrene a Mooney viscosity of 75.2 parts of phenol-formaldehyde resin (produced by reacting 2.1 mol Formaldehyde with 1.0 mol of phenol under alkaline conditions and termination of the reaction in water-soluble State) and 1 part antioxidant. The dried plate was% minute at 188 ° C hardened.

Sample C

13.6 kg of absorbent crepe paper were saturated with the same amount by weight of a latex mixture composed of 99 parts of a copolymer of 75% butadiene and 25% acrylonitrile with a Mooney viscosity of 40 and 1 part of a water-soluble phenol-formaldehyde resin (produced by reaction of 1.5 mol of formaldehyde with 1 ₁ 0 mol of phenol under alkaline conditions), 0.1 part of hexamethylene tetrarm and 1 part of antioxidant. The dried plate was then cured in an air circulation oven at 188 ° C. for 1 minute.

Sample B

65

13.6 kg of absorbent crepe paper was saturated with 90 percent by weight latex mixture consisting of 80 parts a copolymer of 75% butadiene and 25% acrylic - 13.6 kg of absorbent crepe paper were 75 percent by weight a latex mixture saturated, which consists of 75 parts of a copolymer of 75% butadiene and 25% acrylonitrile with a Mooney viscosity of 40.23 parts of a copolymer of 50% butadiene and 50% styrene with a Mooney viscosity of 75.2 parts of a phenol-formaldehyde resin (manufactured by the Reaction of 1.9 mol of formaldehyde with 1.0 mol of phenol under alkaline conditions and termination of the reaction in a still soluble state) and 1 part antioxidant. The dried plate was Cured at 198 ° C for 1 minute.

Sample D

13.6 kg of absorbent crepe paper was saturated with 75 percent by weight of a latex mixture made from 60 parts of a copolymer of 75% butadiene and 25% acrylonitrile with a Mooney viscosity of 40,

37 parts of a copolymer of 50% butadiene and 50% styrene with a Mooney viscosity of 75.3 parts Resorcinol formaldehyde resin (produced by reacting 0.8 mol of formaldehyde with 1.0 mol of resorcinol) acidic conditions), 0.3 part of hexamethylenetetramine and 1 part of antioxidant. The underlay was cured at 94 ° C for 1 minute.

Sample E.

13.6 kg of absorbent crepe paper were saturated with an equal weight of a latex mixture, that of 10 parts of a copolymer of 60% butadiene and 40% acrylonitrile with a Mooney viscosity of 50.87 parts of a copolymer of 50% butadiene and 50% styrene with a Mooney viscosity of 75.3 parts Phenol-formaldehyde resin (produced by reacting 2.0 moles of formaldehyde with 1.0 mole of phenol under alkaline conditions and termination of the reaction while still water-soluble) and 1 part of antioxidant duration. The dried base was cured at 215 ° C. for 15 seconds.

Sample F.

13.6 kg of absorbent crepe paper was saturated with 80 percent by weight of a latex mixture made from 40 parts of a copolymer of 75% butadiene and 25% acrylonitrile with a Mooney viscosity of 40,

55 parts of a copolymer of 50% butadiene and 50% styrene with a Mooney viscosity of 50.5 parts of phenol-formaldehyde resin (produced by reacting 2.0 mol of formaldehyde with 1.0 mol of phenol under alkaline conditions and terminating the reaction in a still water-soluble state) and 1 part antioxidant. The dried substrate was ^{cured at 191 °} C. for 1 minute.

Sample G

13.6 kg of absorbent crepe paper was saturated with 80 percent by weight of a latex mixture made from 70 parts of a copolymer of 75% butadiene and 25% acrylonitrile with a Mooney viscosity of 40, 20 parts of a copolymer of 50% butadiene and 50% styrene with a Mooney viscosity of 50, 10 parts of phenol-formaldehyde resin (produced by reacting 2.0 moles of formaldehyde with 1.0 mole of phenol under alkaline conditions and termination of the reaction in the still soluble state) and 1 part of antioxidant duration. The dried plate was cured at 190 ° C. for 1 minute.

Normally tacky and pressure-sensitive adhesive tapes were made from the samples as described in Example 1, manufactured. The table below compares the data relating to the properties of the strips that were produced with the documents thus obtained.

Table II

Example no. Crepe paper
kg Acrylonitrile
Copolymer
salary
Vo Resin content
° / o tensile strenght
wet
kg / cm Splitting-off
dry jrstand
wet edge
wear and tear
kg A. 13.6 99 1 1.8 very good very good 1.72 B. 13.6 80 2 1.4 very good very good 1.76 C. 13.6 75 2 3.2 very good very good 1.44 D. 13.6 60 3 2.7 very good very good 1.54 E. 13.6 10 3 1.8 very good very good 1.35 F. 13.6 40 5 2.1 very good very good 1.49 G 13.6 70 10 2.9 very good very good 0.95

As can be seen from the table, samples A to F produced according to the invention show those for adhesive tape backings desirable properties. Sample G has good tensile strength when wet and good resistance to splitting, but poor edge wear in the treatment described makes the document suitable for its intended use

inferior. _. . , "

Example 3

The following experiments explain the method according to

of the invention in treating plain paper in lieu of that used in the previous examples

Crepe paper. ,
^r sample A

14.5 kg of smooth, absorbent paper was saturated with 80 percent by weight of a latex mixture made from 60 parts of a copolymer of 75% butadiene and 25% acrylonitrile and with a Mooney viscosity of 40.40 parts of a copolymer of 50% butadiene and 50% styrene with a Mooney viscosity of 50 and 1 part antioxidant consisted. The documents were dried in a Feston oven.

Sample B

14.5 kg of smooth paper was saturated with 80 percent by weight of a latex mixture consisting of 60 parts of a Copolymer of 75% butadiene and 25% acrylonitrile with a Mooney viscosity of 40.37 parts of a copolymer of 50% butadiene and 50% styrene with a Mooney viscosity of 50.3 parts of phenol-formaldehyde resin (produced by reacting 2.2 mol of formaldehyde with 1.0 mol of phenol under alkaline conditions Conditions and termination of the reaction in the still soluble state) and 1 part of antioxidant duration. The dried base was cured at 193 ° C. for 1 minute.

Sample C

14.5 kg of smooth paper was saturated with 80 percent by weight of a latex mixture consisting of 70 parts of a Copolymer of 75% butadiene and 25% acrylonitrile with a Mooney viscosity of 40.17 parts of a copolymer of 50% butadiene and 50% styrene with a Mooney viscosity of 50.13 parts of phenol-formaldehyde resin (produced by reacting 2.2 moles of formaldehyde with 1.0 mole of phenol under alkaline conditions and termination of the reaction in the still water-soluble state) and 1 part of antioxidant. The dried support was dried at 188 ° C. for 1 minute. Patches were made as in Example 1 manufactured and showed the following properties when tested:

Claims (5)

Table III 10 Example No. Flat paper kg Acrylonitrile copolymer content% Resin content% Tensile strength humid kg / cm split-off virgin dry [first wet elongation ° / o edge wear kg A B C14.5 14.5 14.560 60 700 3 130.380 3.80 3.80 medium very good very good bad very good very good12.8 12.6 6.22.21 1.99 0.95 The data in the table above clearly show that the product prepared according to the invention, sample B, has good properties in all essential points. Sample A, which was produced without phenolic resin, has good elongation and low edge wear, but only medium resistance to splitting in the dry state and relatively poor resistance in the wet state. Sample C, the mixture of which contained a higher phenol-aldehyde resin content than is used in accordance with the invention, has good resistance to splitting and good tensile strength in the wet state, but poor elongation and great edge wear and is generally inferior as a base. Claims: 25 1. A process for the production of carrier material from paper impregnated with elastic polymers for pressure-sensitive adhesive strips and plasters with high wet strength and increased splitting resistance, characterized in that a nonwoven fabric with an aqueous dispersion containing predominantly an elastomeric copolymer of butadiene or another conjugated diene reacting with a phenol, N-containing, copolymerizable with the diene monomers such as an unsaturated nitrile, or acrylamide or vinyl pyridine, and a small amount of not more than 7 ° / _0, based on the solids of the impregnating agent, a thermosetting, in Impregnated with water-dispersible or soluble phenol-aldehyde resin and then dried. 2. The method according to claim 1, characterized in that a mixed polymer of butadiene and Aciyl nitrile is used. 3. The method according to claim 1, characterized in that a mixture of copolymers, containing a butadiene-acrylonitrile and a butadiene-styrene copolymer is used. 4. The method according to claim 1 to 3, characterized in that the thermosetting phenol-aldehyde resin an alkaline condensation product of 1.1 to 2.25 moles of formaldehyde and 1 mole of phenol is used will. 5. Pressure-sensitive pressure-sensitive adhesive tape, consisting of one according to the method of claims 1 to 4 impregnated paper backing and a layer of a pressure-sensitive adhesive known per se. Considered publications:
U.S. Patent Nos. 2,601,597, 2,723,207;
American Dyestuff Reporter, 44/1955, pp. 262-264; Tappi 37, Oct. 1954, pp. 455 to 459. © 909 607/342 8.59