Packaging element

The invention relates to inhibition of the splitting / fibrillation of packaging elements in the form of a tape, in particular strapping tapes or strings for bundles in the form of a polyester-based plastic tape, wherein the polyester is mixed with at least one styrene-based polymer as an inhibiting agent. fibrillation.

[0002] Wrapping tapes are usually made of polyesters or polyolefins by extrusion followed by stretching. Due to the orientation of the particles in the stretching process, they tend to fibrillate, i.e. to form cracks in the direction of the tape. Due to the brittleness of the plastics at low temperatures, in particular below 5 ° C, this fibrillation tendency is even more pronounced. In order to reduce the fibrillation tendency, splitting / fibrillation inhibiting agents are usually added when making mixtures for making strapping tapes. However, agents previously used to inhibit fibrillation have not sufficiently prevented brittleness at low temperatures.

[0003] From US 2005/238897 A1, a packaging tape is known which consists of more than 92 wt. polyester and a total of less than 8 wt. polyolefin based additive and further additives, the polyolefin addition being less than 3 wt. As further additives, among others, elastomers based on polystyrene with a proportion of 0.5% by weight are mentioned. and 2 wt. By the addition of polyolefin, the tendency to split along should be reduced. Also styrene elastomers should contribute to reducing the tendency to fission.

[0004] The use of styrene-butadiene rubber in a proportion of up to 25 wt. in polyethylene tape is also known from DE 20 37 398 A1, although the purpose of the additive is not stated in this document. [0005] DE 27 27 356 A1 describes a binding tape that is formed of a thermosetting and thermoplastic resin, whereby the resins are derived from the same monomers such that both resins have affinity for each other and wherein the thermosetting resin is an unsaturated polyester resin cross-linked with styrene. The thermoplastic resin may be an acrylonitrile-butadienstyrene copolymer or an acrylonitrile-styrene copolymer. With this tie tape, a tie tape of sufficient strength comparable to a steel tape should be available, which has a high tensile strength and low elongation and a low tendency to creep and can be easily and strongly joined at the ends. In addition, the thermoplastic resin forms the outer layer of the binding tape, and the thermosetting resin forms its core.

[0006] The object of the present invention is to provide the packaging element in the form of a tape which also exhibits reduced fission / fibrillation ability at low temperatures. [0007] This task is solved on the one hand by the method mentioned at the beginning, whereby a thermoplastic styrene-based thermoplastic polymer is added as the cleavage inhibiting agent and mixing is carried out at a temperature between 250 ° C and 310 ° C so that the cleavage inhibiting agent ( anti-fibrillation) is found in unbound plastic tape and, regardless of this, by using a polymer based on styrene, as an anti-splitting agent in strapping tapes or polyester-based strings.

[0008] It has surprisingly been found that by using thermoplastic styrene polymers, and thus non-elastomeric polymers, as a fragility-inhibiting agent to reduce the tendency to

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V11186EN00 / TS fibrillation of packaging tapes, in particular strapping tapes or strings for bundles, not only this property is reduced, but also its use at lower application temperatures is improved by reducing the tendency to fragile cracking of the packaging element in the form of a tape. The term "lower application temperatures" is understood to mean temperatures below 5 ° C, whereupon the limit is naturally set at lower temperatures, depending on the material.

Polymers or copolymers, which are selected from the group consisting of or consisting of a polystyrene homopolymer, a styrene-butadiene (SB) copolymer, an acrylonitrile-butadiene-styrene (ABS) copolymer, have therefore proved to be particularly suitable as a clearing inhibiting agent. methyl methacrylate-acrylonitrile-butadiene-styrene (MABS) copolymer, styrene-acrylonitrile (SAN) copolymer, acrylonitrile styrene-acrylate copolymer (ASA), styrene-maleic anhydride copolymer (SMA), acrylonitrileethylene-styrene copolymer (AES), acrylonitrile-chlorinated polyethylene-styrene (ACS), methyl-butadiene-styrene (MBS) methacrylate, styrene-a-methylstyrene (SAM) copolymer and mixtures thereof. The basis for their particular suitability could not yet be verified solely on the basis of experience. Explanations on the molecular plane have not yet been presented.

[0010] The proportion of styrene-based polymer in the plastic tape is preferably selected from a range having a lower limit of 0.2 wt. and an upper limit of 20% by weight, in particular 5% by weight Less than 0.2 wt. the reduction in fission is too small. Above 20% by weight the proportion of the base polymer decreases so much that the packaging tape has poorer properties in terms of tensile strength.

[0011] Preferably, the polyester is a thermoplastic polyester, in particular saturated polyester, wherein according to one embodiment the polyester is selected from the group consisting of or consisting of polyethylene terephthalate (PET), poly butylene terephthalate (PBT), polycarbonate ( PC), poly (ethylene naphthenate) (PEN) and mixtures thereof. In particular, these polyesters have very positive mechanical properties, e.g. rigidity, hardness, abrasion resistance, dynamic and thermal load, and therefore properties that are valuable from the point of view of packaging tapes. In addition, positive interaction is observed with polymers based on styrene.

[0012] According to one embodiment of the method, it is envisaged that it contains absolutely no polyolefins or contains less than 0.2 wt. of polyolefin (s). This also avoids reducing the tensile strength and hardness of plastic tapes.

[0013] It may also be provided that the packaging element, in addition to the styrene-based cleavage inhibiting agent, comprises in the plastic tape at least one further cleavage inhibiting agent, different from it, which in particular is selected from the group consisting of or consisting of olefin-acrylate copolymers, thermoplastic polymers (TPE), low density polyethylene (LDPE), linear LDPE (LLDPE), polyethylene, polypropylene, butadiene rubber (BR) and mixtures thereof. It is thus possible to better and more accurately match the properties profile of the packaging element to the respective field of application.

[0014] It has proved to be advantageous here if the further cleavage inhibiting agent is included in a proportion such that the ratio of the styrene-based cleavage inhibiting agent to the further cleavage inhibiting agent is selected in the range from 80: 20 to 20: 80, in particular from 60: 40 to 40: 60. This minimizes the effect of the splitting-inhibiting agent with great certainty

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V11186PL00 / TS based on styrene, which is particularly important from the point of view of how the packaging element is finished in the form of a tape and changing production conditions.

[0015] From the viewpoint of reducing brittle cracking, the styrene-based polymer is in an unbonded plastic belt, in particular forming domains, it being preferred that these domains are formed as stretched in at least one spatial direction, showing in particular in at least one spatial direction of at least approximately an elliptical cross-section. In particular, according to one embodiment, the binding forces between the domains and the surrounding matrix are weaker than the binding forces within the matrix and within the domains. By avoiding the chemical cross-linking of the basic polymer with the cleavage inhibiting molecules, whereby they are unbound within the meaning of the invention, changes in tensile strength are avoided, where the domain design acts as an area in which the cracks "quench". The stretched, in particular at least approximately elliptical shape of the domains, works positively from the point of view of maintaining the anisotropic properties of the plastic tape. In this context, the term "domain" means a separate delimited area in a plastic strip.

[0016] For a better understanding of the invention, it will be explained in more detail in the following figures.

[0017] They show:

Fig. 1 scanning cross-section microscope photo through a polyester based banding tape containing 2 wt. polystyrene;

Fig. 2 a scanning cross-sectional microscope photo through a polyester based banding tape without the addition of the thermoplastic styrene polymer according to the invention;

Fig. 3 graphical representation of the split / fibrillation propensity of various strapping belts at -5 ° C;

Fig. 4 graphical representation of the split / fibrillation propensity of various strapping belts at -15 ° C;

[0018] At the outset, it should be noted that the individual features or combinations of features of the various embodiments described can, as such, constitute independent solutions according to the invention.

[0019] The packaging element in the form of a web according to the invention is a plastic tape, in particular a strapping tape or a string for ties.

[0020] The packaging element is preferably made on the basis of polyesters. By a term based on polyesters within the meaning of the invention it is meant that a banding tape or string for bundles, or the packaging element consists of at least one polyester as the basic material or matrix material, i.e. polyester or the polyester mixture is contained in the packaging element as a basic component with a quantity of at least 50% by weight. Preferably the packaging element in the form of a tape contains a polyester content of at least 75% by weight, in particular at least 85% by weight, or at least 90 wt.

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V11186EN00 / TS [0021] The polyester used is preferably saturated or thermoplastic polyester. The polyester preferably used is a polymer which is selected from the group consisting of or consisting of polyethylene terephthalate (PET), poly (butylene terephthalate) (PBT), polycarbonate (PC), polyethylene naphthenate (PEN) and their of mixtures, In addition to the polyester-based material, the packaging element may contain further additives, e.g., dyes, as are known in the art, and / or inorganic fillers, e.g., talc or chalk. In a preferred embodiment of the invention, the polyester-based packaging element, in addition to polyester, a styrene-based thermoplastic polymer and a dye, contains no further ingredient or supplement.

[0023] Preferably the packaging element in the form of a tape made of polyester-based material does not contain any polyolefin.

[0024] In both variants of the packaging element in the form of a tape, as a banding tape or ties for bundles, each base material contains at least one thermoplastic styrene-based polymer as a split inhibiting agent. A styrene-based polymer is understood to mean a polymer which is either a homopolymer or copolymer or a mixed polymer, with styrene monomer being used in each case.

Preferably, as a styrene-based polymer, a polymer is used which is selected from the group consisting of or consisting of a polystyrene homopolymer, a styrene-butadiene (SB) copolymer, an acrylonitrile-butadiene-styrene (ABS) copolymer, a methyl methacrylonitrile methacrylate copolymer -butadiene-styrene (MABS), styrene-acrylonitrile copolymer (SAN), acrylonitrile-styrene-acrylate copolymer (ASA), styrene-maleic anhydride copolymer (SMA), acrylonitrile-ethylene-styrene copolymer (AES), acrylonitrile-chlorinated polyethylene-styrene (ACS), methyl-methadrylate-styrene (MBS), styrene-α-methylstyrene (SAM) copolymer and mixtures thereof.

[0026] As with polyesters and polyolefins and further contained components of the packaging element, these are conventional market products. The proportion of polymer based on styrene in plastic tape is selected from the range with a lower limit of 0.2% by weight, preferably 0.5% by weight. and an upper limit of 20% by weight, preferably 15% by weight, in particular 3.5% by weight

[0027] The proportion of this styrene-based polymer can, however, also be replaced by up to 80 wt. inclusive, in particular 50% by weight, preferably 20% by weight by further fission inhibiting agents, usually used as a fission inhibiting agent in packaging elements in the form of a tape of this type, different from a fission inhibiting agent based on styrene. In particular, this further cleavage inhibiting agent is selected from the group consisting of or consisting of olefinacrylate copolymers, thermoplastic polymers (TPE), low density polyethylene (LDPE), linear LDPE (LLDPE), polyethylene, polypropylene, butadiene rubber (BR) and mixtures thereof . Preferably, this further cleavage inhibiting agent is included in a proportion such that the ratio of the styrene-based cleavage inhibiting agent to the further cleavage inhibiting agent is selected from 80: 20 to 20: 80, in particular from 60: 40 to 40: 60.

[0028] For experiments, the following compositions were processed by extrusion into belts or strips. strings, the straps having a band width from 9 mm to 19 mm, and the strings showed a length standard with a specific weight of 400 m / kg. Since the method of producing this type of packaging elements in the form of a tape is per se known in the art, specialists are referred to the relevant literature for this purpose.

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V11186PL00 / TS [0029] Designations in the tables:

SP ... styrene polymer,

Std.-Additiv ... a suitable additive, usual for the state of the art, as cited at the beginning, [%] .... wt.

<td>Experience</td><td>dimensions [Mm]</td><td>Addition of styrene polymer SP</td><td>SP share [%]</td><td>Standard supplement / Std.Additiv [%]</td>

<td>Tape</td><td>9x0,55</td><td>PS</td><td> 2,5</td><td> 0</td>

<td>Tape</td><td>15x0,55</td><td>PS</td><td> 0,5</td><td> 0</td>

<td>Tape</td><td>15x1</td><td>POS</td><td> 0,01</td><td> 0</td>

<td>Tape</td><td>15x1</td><td>PS</td><td> 0,02</td><td> 0</td>

<td>Tape</td><td>15x1</td><td>PS</td><td> 0,04</td><td> 0</td>

<td>Tape</td><td>15x1</td><td>PS</td><td> 1</td><td> 0</td>

<td>Tape</td><td>15x1</td><td>PS</td><td> 2</td><td> 0</td>

<td>Tape</td><td>16x0,9</td><td>PS</td><td> 2</td><td> 0</td>

<td>Tape</td><td>16x1,0</td><td>PS</td><td> 2</td><td> 0</td>

<td>Tape</td><td>16x1,0</td><td>ABS</td><td> 0,5</td><td> 0</td>

<td>Tape</td><td>16x1,0</td><td>ABS</td><td> 1</td><td> 0</td>

<td>Tape</td><td>16x1,0</td><td>ABS</td><td> 1,5</td><td> 0</td>

<td>Tape</td><td>16x1,0</td><td>ABS</td><td> 2</td><td> 0</td>

<td>Tape</td><td>16x1,0</td><td>ABS</td><td> 2,5</td><td> 0</td>

<td>Tape</td><td>16x1,0</td><td>SAN</td><td> 0,5</td><td> 0</td>

<td>Tape</td><td>16x1,0</td><td>SAN</td><td> 1</td><td> 0</td>

<td>Tape</td><td>16x1,0</td><td>SAN</td><td> 1,5</td><td> 0</td>

<td>Tape</td><td>16x1,0</td><td>SAN</td><td> 2</td><td> 0</td>

<td>Tape</td><td>16x1,0</td><td>SAN</td><td> 2,5</td><td> 0</td>

<td>Tape</td><td>19x1,0</td><td>PS</td><td> 0,5</td><td> 0</td>

<td>Tape</td><td>19x1,0</td><td>PS</td><td> 2</td><td> 0</td>

<td>Tape</td><td>19x1,27</td><td>PS</td><td> 1</td><td> 0</td>

<td>Tape</td><td>19x1,27</td><td>PS</td><td> 2</td><td> 0</td>

<td>Tape</td><td>19x1,27</td><td>PS</td><td> 3,5</td><td> 0</td>

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V11186PL00 / TS

<td>Experience</td><td>dimensions [Mm]</td><td>Addition of styrene polymer SP</td><td>SP share [%]</td><td>Standard supplement / Std.Additiv [%]</td>

<td>Tape</td><td>19x1,27</td><td>PS</td><td> 1</td><td> 1</td>

<td>Tape</td><td>19x1,27</td><td>PS</td><td> 1,5</td><td> 0,5</td>

<td>Tape</td><td>19x1,27</td><td>PS</td><td> 2,25</td><td> 0,75</td>

<td>Experience</td><td>Titer [m / kg]</td><td>SP supplement</td><td>SP share [%]</td>

<td>Twine</td><td> 400</td><td>PS</td><td> 1</td>

<td>Twine</td><td> 400</td><td>PS</td><td> 2</td>

<td>Twine</td><td> 400</td><td>PS</td><td> 5</td>

[0030] The proportion of at least 90%, in particular 95%, preferably 99% of the total amount of styrene-based cleavage inhibiting agent, preferably at least approximately 100%, is in the plastic band in an unbound state and according to one embodiment in forms of domains, as can be seen from Fig. 1, which shows a banding tape having a composition of 98 wt. PET and 2 wt. PS. This is obtained by treatment when preparing a compound for producing a packaging element at a temperature between 250 ° C and 310 ° C, in particular between 270 ° C and 300 ° C.

In contrast, Fig. 2 shows a scanning microscope photo of a PET tape without the addition of a styrene-based thermoplastic fission inhibiting agent. This shows the difference with respect to the packaging element according to the invention. It can be seen that, in this case, domains (white spots) are also formed, which, however, relate to partially crystalline PET regions.

[0032] In particular, it is preferred that the domains are formed as stretched in a certain direction, as can be seen from Fig. 1. Stretching in at least one spatial direction of the domains has been obtained by stretching using stretching tools and a stretching furnace. The stretching of the domains in the spatial direction preferably takes place to at least approximately an elliptical cross-section.

[0033] To show the state of Figs. 3 and 4, on various polyester-based strapping tapes with different proportions of polystyrene or without this type of splitting agent or with market standard additives (data below the bars on the abscissa should be understood again as wt.%, where the abbreviation "Std" means market, standard additive and "Sty" means polystyrene), by mechanical loading perpendicular to the direction of stretching fission / fibrillation was provoked -5 ° C (Fig. 3), or - 15 ° C (Fig. 4). The test was performed many times on each tape (40-60 times). The contribution of each loading case in which actual splitting occurred was rated as "bad".

[0034] In Fig. 3, in addition to pure type additives, combinations of conventional commercial cleavage inhibitors and PS were also added, in Fig. 4 only pure type additives.

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V11186EN00 / TS [0035] As can be seen from Fig. 3, the addition of 1% PS results in a much better prevention against splitting than the addition of 2% by weight. prior art cleavage agents. In belts with a combination of the prior art additive and PS, the splitting strength increases under these ambient conditions with an increasing proportion of PS.

[0036] Fig. 4 indicates that at very low temperatures for this application of -15 ° C, with a content of 2% PS, the splitting tendency can be significantly reduced. In contrast, the prior art additive does not show any active action under these conditions.