CA2105102A1 - Pressure-sensitive contact adhesive and manually-tearable contact adhesive tapes produced therefrom for the embroidery and textile industries - Google Patents

Abstract

Abstract Pressure-sensitive contact adhesive which is characterized in that it comprises a mixture of A) 0 to 90 wt.% acrylic acid ester-vinyl acetate-acrylic acid copolymer with 2 to 8 carbon atoms in the alcohol component of the acrylic acid ester and, relative to the copolymer, 10 to 60 wt.% vinyl acetate and 1 to 10 wt.% acrylic acid (K value according to Fikentscher in the range 50 to 110 - measured according to DIN 51562 in tetrahydrofuran), B) 10 to 80 wt.% acrylic acid ester-acrylic acid-N-methylol methacrylamide copolymer with 4 to 8 carbon atoms in tyhe alcohol component of the acrylic acid ester and, relative to the copolymer, 1 to 10 wt.%
acrylic acid and 1 to 10 wt.% self-crosslinking N-methylol methacrylamide (K value according to Fikentscher in the range 70 to 130 - according to DIN
51562 in tetrahydrofuran), C) 0 to 90 wt.% acrylic acid ester-ethyl acrylate-N-methylol methacrylamide-acrylic acid copolymer with 4 to 8 carbon atoms in the alcohol component of the acrylic acid ester and, relative to the copolymer, 1 to 10 wt.% acrylic acid and 1 to 10 wt.% self-cross-linking N-methylol methacrylamide and 20 to 80 wt.%
ethyl acrylate (K value according to Fikentscher in the range 80 to 130 - measured according to DIN 51562 in tetrahydrofuran), D) 0 to 25 wt.% phthalic acid ester with 2 to 12 carbon atoms in the alcohol component of the ester.

It is suitable for the production of manually-tearable contact adhesive tapes for the embroidery and textile industries.

Description

21~102 _ 1 --The invention relates to pressure sensitive contact adhesives and manually-tearable contact adhesive tapes produced therefrom which can be used in the embroidery and textile industries for the purpose of fixing textiles to be embroidered onto operating machines. In connection with the present invention, the term contact adhesive tapes is to refer not only to tapes but also to other areal products, for example sheets or leaves.

Embroiderers stitch motifs onto textiles by means of computer-controlled embroidery machines ~hich are fitted with a different number of embroidery heads according to type and size, each emb~oidery head being e~uipped with several needles for differently coloured yarns. The textile to be embroidered is fi~ed on a fleece paper or another manually-tearable material.

The fixing ~upport is glued into a bordering frame which moves according to ~he computer program in such a way that the needle produces the desired embroidered motif with up to 700 stitches per minute.

Suitable areal materials are fibre fleeces, particularly fleece paper a~d long-fibred special papers, fibre fleeces are textile webs made from textile fibres, the coherence of which is provided by the~inherent adhesion of the fibres. Fibre fleeces which are pxoduced by the strengthening of spun fibres ars called spun fleece~.

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- 2 ~ ~ `2 In general, one understands by a fleece a textile product in which the fibres are evenly distributed. They may or may not be orientated. In contrast to woven textile materials, the fibres are processed not to yarns and to woven fabric, but laid together by mixing and distributing. The binding together of the fibres is carried out by mechanical, chemical and/or physical means.

The fleece products can be very different in their construction ranging form unconnected to tightly bound, supple to stiff, compact to highly voluminous. The weaker the fibre orientation, the better the material can be cut, with the result that cutting wastage only occurs to a very slight degree. Decisive for the properties of the fibre fleeces by fibre type, fibre guage, staple length and density of the fibres as well as the binding agents used.

Used as fibres for fleeces are plant fibres based on cellulose, animal wool fibres based on protein, semi-synthetic viscose and acetate cellulose fibres and synthetic fibres based on polyamides, polyacrylonitrile, polyvinyl derivatives, polyesters and polyole~ins. The fleece papers based on cellulose therefore also come under the generic term fibre fleece in the broader sense, although they are often regarded as a special material cla3s.

It is a prerequisite for the use of fibre fleeces, special papers or other areal materials as fixing supports of textiles in embroidery operations that the materials are compact and supple so that they lie well against the material to be embroidered and improve the plasticity of the embroidered motif. Further, they must be able to be manually torn away easily without problem outside the motif edges after the stiching.

In the past, embroiderers have sprayed ~leece materials with a spray adhesive which consists o~ polyvinyl ester copolymers such as for ex~mple polyacrylic acid copolymers and is dissolved i.n .. . . . : . - : . . . . - :: ~ - . . .

2i~ 2 chlorofluorocarbons. Aerosols based on chlorofluorocarbons are used as propellants for such spray adhesives. During the spraying and drying of the adhesive, environmentally polluting gases form.
In addition to the undesired gas formation, the spray adhesives display crucial disadvantages above all in use: It is so greasy that adhesive residues adhere in the needle channel after a short embroidery time and prevent a proper guiding of the thread. The adherence of the material to be embroidered on the spray adhesive fleece is often too weak. If the textile material moves during the embroidery process, the embroidery sample develops faults and becomes unusable. Furthermore, the spray adhesive lakes after a short time and loses its adhesive properties.

It is also a disadvantage that the spray adhesive presoaks traditional fleece papers, as it cannot be measured exactly, and therefore leaves the support material unstable in the case of extensive coating.

It was therefore necessary, in order to be able process woven and machine goods in the field of embroidery, to coat the support material fleece by means of a textile adhesive spray in order to then fix the product to be embroidered. The term "fixing" is to be understood as a stabilising of the stitches or woven fabric of the material to be embroidered. On spraying larger areas, uneven coatings occur through a manually-carried out activity which a) can lead to detachment of the product to be embroidered and b) since no exact dosage is possible, causes spots to form in the case of sensitive materials, ~chiffon, silk, ~ersey etc.).

Furthermore, the fleece is presoaked if the spraying is too strong, resulting in instability. In this case, the embroidered product becomes deformed in its thread length and thereby unclean.

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Further, with too strong a spraying the thread as well as the thread channel of the needle is affected, which means that loop formation is not clean or the thread sticks in the thread channel of the needle with the result that, upon taking up o~ the loop of the double rotary shuttle, there is no timing s~nchronization and this leads to thread tears, lost stitches and therefore to lost machine time.

An alternative was the use of thermofleece. Thermofleeces are spun or stitched fleeces which are coated by means of a heat-soluble adhesive.

Thermofleeces are used to fix the fibres for extremely stretchable knitted products, these fleeces also having to be removed at certain parts of a textile after embroidering. In the tricot material field of use the handling of the above fleece is to be considered very difficult since, a) at too high a temperature a discoloration of the embroidery material occurs and, furthermore, the fleece can be cleanly removed only with difficulty, if at all without distorting the embroidery image (a further unpleasant characteristic are the residues (adhe~ive particles) on the embroidered product) and b) in order to be able to use thermofleece in the best possible way, costly additional machine expenditure (fixing press, through-run fixing units or irons) is required.

When irons are used, a regular bond does not result here either, since the surface heating and cooling cannot be controlled linearly. This results in an uncontrolled detachment o~ the material in the case of a longer embroidery process. The use of a thermofleece in the first run for a larger production range is ruled out since the fixed material can only be stored on a flat plane and is therefore very cost intensive.
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'' , .' ' , ' '; ' ' ' ' , ', ' ~', '' ~ ' ~ . ' . ' _ 5 _ The question now arises of whether a fleece material fitted in a self-adhesive manner is better suited to this application than a spray adhesive fleece. Pressure sensitive self-adhesive compositions or contact adhesives have been used everywhere for some time in the form of contact adhesives in industry, craftwork and homes. Known from the patent literature are numerous examples for the production of rubber and polyacrylic acid ester contact adhesives based on organic solvents and aqueous dispersions.
Described in DE-OS 36 43 987, DE-OS 38 43 421 and EP 0 141 504 are copolymers of acrylic acid esters, acrylic acid and other monomers. Described in DE-OS 30 18 131 are contact adhesives comprising polyacrylic acid esters and polyisocya~ates based on solvents. Emulsion contact adhesive polymers of n-butyl acrylate, 2-ethyl hexyl acrylate, acrylic acid, acrylonitrile, vinyl acetate, methyl methacrylate and other monomers are for example described in patent specifications EP 0 130 080, EP 0 193 295, EP ~ 258 753, DE 31 47 007, DE 33 13 922, DE 35 31 601, DE 38 29 077, DE 37 01 757 and DE 38 08 706.

In terms of their use for self-adhesive fleece materials in textile embroidery, all the described contact adhesives based on polyacrylic acid ester display shortcomings which prevent or considerably limit their use possibilities. technical services studies have ~hown that either the contact adhesives very quickly block or stick the needle channel or adhere unsatisfactorily to the f leece material so that, upon removal of the textile materials, they wind around the latter. Other contact adhesives are well anchored on f leece materials but leave behind adhesive residues on the textiles. Nany contact adhesives partially migrate into the f leece materials and into the textiles. On ironing, washing or cleaning, sewn-in fleece pieces can spoil the textile materials in the embroidery area through low-molecular weight adhesive components with formation of spots.

It is the object of the invention to develop a pressure-sensitive contact adhesive for fleece materials in embroidery ~hich does o~02 not display the disadvantages described above and which can be used problem-free on fleece material as fixing adhesive for textiles to be embroidered. Even at high embroidering speeds the adhesive is not to block needle channels over a relatively long period.

The ob~ect is achieved by a pressure-sensitive contact adhesive which consists of a mixture of the following components and optionally usual auxiliaries:

A) 0 to ~0 wt.%, particularly 0 to 86 wt.% acrylic acid ester-vinyl acetate-acrylic acid copolymer with 2 to 8 carbon atoms in the alcohol component of the acrylic acid ester and, relative to the copolymer, 10 to 60 wt.%, particularly 15 to 55 wt.% vinyl acetate and 1 to 10 wt.%, ~articularly 2 to 8 wt.% acrylic acid (K value according to Fikentscher in the range 50 to 110 (measured according to DIN 51562 in tetrahydrofuran)), B) 10 to 80 wt.%, particularly 10 to 75 wt.%, preferably 10 to 67 wt.~ and specifically 10 to 60 wt.% acrylic acid ester-acrylic acid-N-methylol methacrylamide copolymer with 4 to 8 carbon atoms in the alcohol component of the acrylic acid ester and, relative to the copolymer, 1 to 10 wt.%, parti-cularly 2 to 8 wt~% acrylic acid and 1 to 10 wt.%, parti-cularly 2 to 8 wt.% self-crosslinking N-methylol methacryl-amide (K value according to Fikentscher in the range 70 to 130 (according to DIN 51562 in tetrahydrofuran)), .. . .
C) O to 90 wt.%, particularly 0 to 85 wt.% acrylic acid ester-ethyl acrylate - N-methylol-methacrylamide - acrylic acid copolymer with 4 to 8 carbon atoms in the alcohol component of the acrylic acid ester and, relative to the copolymer, 1 to 10 wt.~, particularly 2 to 8 wt.% acrylic acid and 1 , to 10 wt.%, particularly 2 to 8 wt.% self-crosslinking N-mathylol methacrylamide and 20 to 80 wt.%, particularly 20 .
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- 7 - '~10~ ~2 to 60 wt.%, preferably 25 to 55 wt.% ethyl acrylate (K
value according to Fikentscher in the range 80 to 130 (measured according to DIN 51562 in tetrahydrofuran))~

D) 0 to 25 wt.%, particularly 0 to 20 wt.% phthalic acid ester with 2 to 12 carbon atoms in the alcohol component of the ester.

The amount of components A) and/or C) which are present in addi-tion to Component B~ is preferably at least 0.1 wt.%, more pre-fered at least 1.0 wt.% and specifically at least 5 wt.%. In case component A) is present it is preferably present in an amount of 5 to 86 wt.%, more prefered 13 to 86 wt.% and specifically 10 to 50 wt.%. In case component C) is present it is preferably present in an amount of 5 to 90 wt.%, more prefered 10 to 90 wt.% and specifically 20 to 90 wt.~. In case component D~ is present it is preferably present in an amount of 5 to 20 wt~ and more pre-fered 10 to 20 w~.%.

The contact adhesive components are produced according to the usual processes in the patent literature.

Component A preferably has a K value of 60 to 100, component B
a ~ value of 80 to 120 and component C a K value of 90 to 120.
' Small quantities of other monomers such as e.g. methacrylic acid sster, methacrylic acid, methacrylonitrile and styrene can be polymerized into the copolymers of the mixture components A) to C). The monomers can be contained in quantities of 0.5 to 25, more prefered 0.5 to 20 wt.~, particularly 1 to 15 wt.% in the copolymers, based on the weight of the copolymers. The acrylic acid ester components in-the copolymers are preferably n-butyl acrylate and/or 2-ethyl hexyl acrylate.

The mixture according to the invention is preferably present as ~t an aqueous dispersion, the pH value of which is set at 7 to 8, ,i:
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2lo5~2 preferably 7 to 7.5 with ammonia water. It is coated onto support materials in quantities of 5 to 50 g/m2, particularly 10 to 45 g/m2, dried to a self-adhesive film and covered with an adhesive separating material.

The aqueous copolymer dispersions contain the anionic emulsifiers usual in the literature, such as are e.g. described in the book "Methoden der organischen Chemie" by Houben-Weyl, Volume 14/1, Makromolekulare Stoffe, Georg-Thieme-Verlag, Stuttgart 1972, pages 192 to 208.

In order to achieve an even coating and a good film formation, additives such as thickeners, wetting agents and foam inhibitors are added in usual quantities (0.5 to 5.0 wt.%, particularly 0.1 to 2.0 wt.%) to the dispersion.

The invention further relates to the use of the pressure sensitive contact adhesive according to the invention, which can be used when cold, for the coating of support materials such as fibre fleeces, fleece papers and long-fibred special papers in the range 15 to 100 g/m2, preferably 20 to 40 g/m2.

A areal, thin and transparent separating material such as siliconized paper or siliconized films are coated with the aqueous dispersion. On drying the dispersion, a pressure-sensitive contact adhesive film results with coating strengths of 5 to 50 g/m2 and particularly 10 to 45 g/m2 which is coated onto support materials. Particularly suitable as support material are fibre fleeces and fleece papers based on cellulose.

The substrates coated in this way, which are manually tearable, serve as fixing adhesive tapes in textile embroidery. Light textiles such as e.~. light cotton, Jersey and silk and heavy textiles such as e.g. working clothes made from heavy cotton or -wool, terry towelling and jeans adhere well at slight pressure on coated fleece papers.

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The textiles fixed on self-adhesive fleece paper were embroidered at a speed of ca. 700 needle stitches per minute. After 10 minutes' stitching time, the needle eye and needle channel remained free from adhesive residues. Slipping of the textiles was not observed during the stitching process. The fleece paper outside the embroidered motif edges was then able to be torn off easily and free from any adhesive residues.

If the embroidered textile is sewn onto a textile material it is usual not to remo~e the self-adhesive fleece paper on the embroidered back of the textile, but to sew it in as a plasticizing insert. Ironing, washing and cleaning operations have shown that the contact adhesive and the fleece paper do not impair the quality of the textile.

The newly developed material is to be categorized as a material gentle to textiles and as a material simple to handle. Neither gases nor fumes are released on its processing. Furthermore, it is po~sible to fix it onto the embroidered material by slight contact pressure (cold fixing) which is kind to knitted, stitched i and woven-fabric materials. Since the material to be processed can be coated, deformation of the basic material is avoided. The use in border or individual stitch frames has the advantage that the material to be embroidered no longer has to be clamped, but is held by the film coated onto it.

Since the contact adhesive according to the invention neither cloud~ nor softens, the whole mechanics and electronics of a computer-controlled embroidering machine is spared. Since the contact film formed can be so adjusted that neither the needle nor the gripper are affected by adhesive, a considerably higher utilization of the machines is possible. Furthermore, the maintenance intervals are extended. The adhesive also does not cause different types of yaxn to connect. The embroidery image 1 is improved li~ewise by the simultaneous adhesion.
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I' . , . , ~ ' . " , ., ~ ' .' . ' .'' '.' '' ' ~ . ' ' . . .' ' ' ' ' A strip measuring 3.20 m x 0.45 m is connected to the embroidery frame using mechanical clamps in the case of a border frame. The silicone paper is then removed and the product to be embroidered is connected by contact pressure with the adhesive tape. A
stabilisation of the embroidered product results because of this, so that the stitches can no longer be deformed. Since thermal heat (ironing) is not used either, the fibre is no longer heated unevenly or overheated prior to the embroidery process, meaning that the material to be embroidered is spared. This process also applies to the use of single ~rames which are used e.g. with finished parts.

The bordering frame or single frame is moved by means of stepped motors according to the prepared program (transport). The needle maintains its position and performs an upwards and downwards movement during the stitching process. It is important that the embroidering machine's speed is determined according to the type of stitch, length of stitch and position of the stitch. The material produced according to the invention offers an immense advantage here, a linear surface adherence.

The invention is explained in more detail in the following with reference to examples.

E~AmDles 1 to 5 Given in Table 1 are various formulations for the contact adhesive according to the invention in the form of aqueous di~persions. The weight percentages of the formulations are relat~d to 100 % ~olids, i.e. water proportions are not included.
The dispersions were coated on papers siliconized on one side (67 g/m2) such that, after drying, adhesive films wi~h ca. 10 g/m2 adhesive formed. The adhe ive coatings were coated on fleece paper (Fa 30 g/m2)-~ . - - . :

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- 11 2lo51o2 Table 1 Acrylic acid ester-vinyl acetate acrylic acid copolymer 24 13 - 86 25 Acrylic acid ester-acrylic acid N-methylol methacrylamide copolymer 41 67 10 14 45 Acrylic acid ester-ethyl acrylate N-methylol methacrylamide acrylic acid copoly~er 35 - 90 - 20 Phthalic acid ester - 20 - - 10 Adhesive power measurements were carried out as per Afera standard 4001 (immediate measurement) on the self-adhesive fleece papers produced with the adhesive formulations 1 to 5, but not on steel, since the fleece paper frequently plucks or splits, but, on various textiles appropriate to the application. The measured results are given in the following Table 2.

Tabl~ 2 Adhesive power fleec~

paper against cotton N/cm 0.07 0.05 0.08 0.17 0.10 Nylon lycra (synthetlc) n O .10 0.07 0.09 0.21 0.12 Polyester wool n 0.45 0.41 0.43 0.39 0.44 Chiffon silk n 0.18 0.15 0.16 0.26 0.18 Linen ~ 0.26 0.38 0.22 0.41 0.39 Mixed fabric made of synthetics and cotton n O .18 0.24 0.14 0.37 0.27 Fleece paper sample strips with the contact adhesive formulatîons 1 to 5 were stored for 6 weeks at 70C and the adhesive power determined on various textiles. A reduction in adhesive power was not observed.

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Claims (10)

1. Pressure-sensitive contact adhesive characterized in that it comprises a mixture of A) 0 to 90 wt.% acrylic acid ester-vinyl acetate-acrylic acid copolymer with 2 to 8 carbon atoms in the alcohol component of the acrylic acid ester and, relative to the copolymer, 10 to 60 wt.% vinyl acetate and 1 to 10 wt.% acrylic acid (K value according to Fikentscher in the range 50 to 110 - measured according to DIN 51562 in tetrahydrofuran), B) 10 to 80 wt.% acrylic acid ester-acrylic acid-N-methylol methacrylamide copolymer with 4 to 8 carbon atoms in the alcohol component of the acrylic acid ester and, relative to the copolymer, 1 to 10 wt.%
acrylic acid and 1 to 10 wt.% self-crosslinking N-methylol methacrylamide (K value according to Fikentscher in the range 70 to 130 - measured according to DIN 51562 in tetrahydrofuran), C) 0 to 90 wt.% acrylic acid ester - ethyl acrylate - N-methylolmethacrylamide -acrylic acid copolymer with 4 to 8 carbon atoms in the alcohol component of the acrylic acid ester and, relative to the copolymer, 1 to 10 wt.% acrylic acid and 1 to 10 wt.%, self-cross-linking N-methylol methacrylamide and 20 to 80 wt.%

ethyl acrylate (K value according to Fikentscher in the range 80 to 130 - measured according to DIN 51562 in tetrahydrofuran), D) 0 to 25 wt.% phthalic acid ester with 2 to 12 carbon atoms in the alcohol component of the ester.

2. Pressure sensitive contact adhesive according to claim 1, characterized in that the acrylic acid ester components in the copolymers contain n-butyl acrylate and/or 2-ethyl hexyl acrylate.

3. Pressure sensitive contact adhesive according to claim 1 or 2, characterized in that further monomers, preferably methacrylic acid ester, methacrylonitrile, methacrylic acid, acrylonitrile, hydroxyethyl acrylate and styrene are polymerized into the copolymers.

4. Pressure-sensitive contact adhesive according to one of claims 1 to 3, characterized in that the further monomers are polymerized into the copolymers in quantities of 0.25 to 25 wt.%.

5. Pressure-sensitive contact adhesive according to one of claims 1 to 4, characterized in that it is present as an aqueous dispersion.

6. Pressure sensitive contact adhesive according to one of claims 1 to 5, characterized in that the pH value of the aqueous dispersion is set at about 7 to 8 with ammonia water.

7. Use of the pressure sensitive contact adhesive according to one of claims 1 to 6 for the production of self-adhesive areal substrates coated on one or both sides.

8. Use according to claim 7, characterized in that the areal substrates are fibre fleece.

9. Use according to claim 6 or 7, characterized in that the areal substrates are fleece papers or long-fibred special papers with weights of 15 to 100 g/m2.

10. Contact adhesive tape, characterized in that it includes an adhesive according to one of claims 1 to 6.