Adhesive composition with biodegradable glitter particles

Abstract

The invention relates to an adhesive composition comprising biodegradable glitter particles and at least the following components: a) at least one biodegradable binder; b) at least one biodegradable thickener; c) at least one preservative; and d) water.

Description

[0001] Adhesive composition with biodegradable glitter particles

[0002] The present invention relates to an adhesive composition containing glitter particles.

[0003] So-called glitter glues are adhesives containing glitter particles, usually transparent or at least drying to a transparent state. In addition to adhesive purposes, these adhesives are used for decorating and / or labeling various materials. State-of-the-art glitter glues essentially consist of an aqueous binder system, for example, based on polyacrylate, and glitter particles. These glitter particles are usually made of a metal-coated plastic based on polyethylene terephthalate (PET). Such glitter glues can also contain other additives, such as dyes, preservatives, etc. To prevent the glitter particles from settling or floating, a suitable thickener, such as polyacrylic acid, is often used.

[0004] However, when examining the waste streams of these products or the crafts created from them, it must be noted that the glitter glues known from the state of the art already contain added microplastic particles. The binders themselves often fall under the definition of microplastics. According to the dossier (Restriction Report - Microplastics; Annex XV, Table 17, 2&3) of the European Chemicals Agency (ECHA), tiny plastic particles are clearly declared and defined as microplastics based on their size or dimensions and their lack of biodegradability. The ECHA definition also precisely specifies which biodegradability tests are accepted to determine whether a polymeric material is to be considered a microplastic or not. Permissible test methods are described, for example, in ISO 14851 and ISO 14852.

[0005] In light of the now alarming pollution of the oceans by microplastic particles, particularly plastic waste, and the growing environmental awareness among the population, there is a growing need in society to change this situation. Part of the solution lies in eliminating microplastic particles from end products and, where appropriate, replacing them with more sustainable solutions. All state-of-the-art glitter adhesives contain glitter particles that comprise non-biodegradable plastic particles. These microplastic particles originate partly from the added PET glitter particles themselves, but partly also from the non-biodegradable polymer-based binder systems. The use of sustainable, microplastic-free glitter adhesives based on biodegradable glitters has so far been hampered by a lack of storage stability in aqueous environments and a lack of sufficient biodegradability of the entire binder system.

[0006] The present invention is based on the object of providing an adhesive composition of the type mentioned above that overcomes the disadvantages of the prior art. In particular, the present invention is based on the object of providing an adhesive composition with glitter particles that is entirely biodegradable and free of microparticles while simultaneously maintaining high storage stability.

[0007] This object is achieved according to the invention by an adhesive composition having the features of claim 1. The adhesive composition according to the invention provides, for the first time, an adhesive composition with biodegradable glitter particles as well as biodegradable binders and thickeners.

[0008] In a particularly preferred embodiment of the adhesive composition according to the invention, the glitter particles have a base composed of at least one biodegradable polymer, wherein the base preferably comprises cellulose and / or cellulose derivatives, and wherein the base is coated with metal, preferably aluminum. Cellulose has proven particularly advantageous as a base for the biodegradable glitter particles, since cellulose exhibits a particularly high degradation rate under various conditions (e.g., composting and fresh water).

[0009] Glitters are small particles with a wide variety of shapes. In particular, they have a size, for example a maximum diameter in a main direction of extension of the particle, of 0.02 mm to 7.0 mm, preferably 0.050 mm to 6.0 mm, for example 0.06 mm to 2.0 mm, e.g. 0.1 mm to 0.5 mm. There are no particular restrictions regarding the shape of the glitter particles and they can, for example, be in the form of platelets, needles, cuboids, etc., or can be punched into specific shapes, for example hexagons, squares, circles, ovals, stars, etc. According to certain embodiments, the glitters are flat, for example as platelets with a wide variety of shapes, e.g. hexagonal, rectangular, square, star-shaped, round, oval, etc., wherein the thickness of the platelets is preferably between 4 μm and 50 μm, for example between 5 μm and 45 μm, e.g.between 10 pm and 5 pm, for example between 14 pm and 23 pm, and / or the size, for example a maximum diameter in a main direction of extension of the glitter, can be from 0.02 mm to 7.0 mm, preferably 0.050 mm to 6.0 mm, for example 0.06 mm to 2.0 mm, e.g. 0.1 mm to 0.5 mm.

[0010] Typically, the glitter particles of the adhesive composition according to the invention are produced by comminuting a metal-coated polymer-based film, especially a cellulose-based one. This allows the biodegradable glitter particles to be produced quickly and easily.

[0011] A preferred embodiment of the adhesive composition according to the invention further contains at least one humectant, in particular at least one polyol, wherein the humectant is preferably present in a proportion of approximately 1% by weight to approximately

[0012] 15 wt.% is contained. The adhesive composition according to the invention advantageously contains as a humectant at least one compound from the group of glycerol, sugar alcohol, such as xylitol, polydextrose and 1,2-propylene glycol. These humectants are all biodegradable. These humectants have proven to be particularly advantageous with regard to pull-on behavior, adhesive performance and paper corrugation. In a preferred embodiment of the adhesive composition according to the invention, the biodegradable glitter particles are contained in a proportion of approximately 2 wt.% to approximately 10 wt.%, preferably approximately 4 wt.% to approximately 8 wt.% The biodegradable binder is advantageously contained in a proportion of approximately 1 wt.% to approximately 35 wt.%, preferably approximately 2 wt.% to approximately 20 wt.% The at least one thickener is advantageously contained in a proportion of approximately 0.1 wt.% to approximately 3 wt.%.Advantageously, the at least one preservative is present in a proportion of < 3% by weight. Water is preferably present in a proportion of approximately 55% to approximately 90% by weight.

[0013] Component a) of the adhesive composition according to the invention is advantageously a water-soluble and preferably biodegradable binder according to EN ISO 14851, preferably a natural binder, such as starch and / or starch derivative and / or a synthetic polymer, such as polyvinyl alcohol. These binders, all of which are biodegradable, have also proven particularly advantageous with regard to storage stability.

[0014] Particularly advantageously, component a) is an enzymatically branched starch, preferably maltodextrin and / or an alkaline-digested starch ether, preferably an alkaline-digested propoxylated starch.

[0015] The adhesive composition according to the invention advantageously contains xanthan gum and / or microcellulose and / or microfibrillated cellulose and / or sodium alginate and / or carboxymethylcellulose and / or pectin and / or a modified phyllosilicate as thickeners. These thickeners are all biodegradable and have proven particularly advantageous with regard to pull-off behavior, adhesive performance, and paper corrugation.

[0016] Advantageously, at least one preservative selected from the group consisting of isothiazolinones, sodium pyrithione, bronopol, phenoxyethanol, and iodopropyl carbamate is present. These preservatives have proven particularly advantageous in extending storage stability. A particularly preferred embodiment of the adhesive composition according to the invention has a pH in the range from approximately 5.5 to approximately 8.5, preferably from approximately 6.0 to approximately 8.0. The pH is preferably adjusted using auxiliaries such as pH buffers. It has been found that particularly good storage stability of the adhesive composition according to the invention is achieved in the stated pH range. The subsequent desired biological degradation thus only occurs under typical environmental conditions, such as in sewage treatment plants or in open waters through contact with the bacteria prevalent there or through other microorganisms.

[0017] Advantageously, the adhesive composition according to the invention further comprises fragrances, pigments, antioxidants, light stabilizers, bleaching agents, pH buffers and / or defoamers, the proportion of these additives being a maximum of approximately 5% by weight.

[0018] As a rule, the proportion of natural or renewable raw materials is more than 97% by weight.

[0019] The present invention further relates to a container, in particular a bottle or tube with applicator, containing an adhesive composition according to the invention.

[0020] The present invention further relates to the use of an adhesive composition according to the invention for decorating and crafting with paper, cardboard, wood, felt, cork, glass and / or textile materials.

[0021] Examples

[0022] 1. Preparation of formulations

[0023] The solid binder components according to Table 1 were vacuum-suspended in water and stirred for 1 h. Depending on solubility, this process was carried out at room temperature or at 60°C. The appropriate amount of glycerin and / or other liquid components was then added to the solution. The glitter (PET or bioglitter) was then added while stirring. Finally, excipients, such as preservatives and / or bleaching agents, were added to the formulation while stirring. The resulting adhesive compositions were then filled into application bottles.

[0024] 1) Mowiol ® 18-88 or Mowiol ® 8-88 depending on the desired viscosity

[0025] 2) Enzymatically hyperbranched starch

[0026] 3) Carbomer ® 4) Neutralizing agent

[0027] Table 1 : tested formulations

[0028] 2. Application-related tests

[0029] All application tests were conducted under constant test conditions. The formulations and test materials were held at 23°C / 50% RH for 24 hours prior to testing. Color and appearance were assessed visually. The pH values ​​were determined using a calibrated Mettler-Toldeo pH meter. Viscosities were determined using a Brookfield rotational viscometer with a spindle of 5 and 20 rpm at 20°C. Storage stability:

[0030] To simulate a minimum two-year storage stability, the formulations were stored at 40°C for 6 months and compared with the initial state at the end of the storage period. This method is based on the assumption that chemical aging processes double every 10°C. Thus, storage for 6 months at 40°C corresponds approximately to the same aging at 24 months at 20°C. The color and appearance of the formulations were assessed, particularly the integrity of the glitter particles.

[0031] Biodegradability:

[0032] DIN ISO 14851 specifies a method for determining the degree of aerobic biodegradability of plastics (including those containing formulation additives) by measuring the oxygen demand in a closed respirometer. The formulations from Examples 1-7 were exposed to an inoculum (= seed culture) of activated sludge, compost, or soil in an aqueous medium under laboratory conditions. According to the ECHA Microplastics Restriction Report (Annex XV, Table 3), a degradation of at least >90% within 6 months is required as a criterion for classification as microplastic-free.

[0033] Blood flow:

[0034] A bead was applied to a paper strip (copy paper) measuring 297 x 52.5 mm. The back of the paper strip was qualitatively evaluated after 1 day.

[0035] Paper curl:

[0036] A bead was applied to a paper strip (copy paper) measuring 297 x 52.5 mm. The curl of the paper strip was qualitatively evaluated after 1 day.

[0037] Characteristics:

[0038] 11 after 10 weeks

[0039] 2) Criteria for microplastics according to the ECHA Microplastics restriction report (Annex XV, Table 3)

[0040] Table 2: Test results

[0041] As can be seen from Table 2, the compositions according to the invention (Examples 4 to 7) demonstrate sufficient storage stability compared to the comparative compositions (Examples 1 to 3) and simultaneously meet the biodegradability criteria, meaning they can be considered free of microplastics. It is also interesting to note that a low pH value (e.g., 4.3 as in Example 3) causes the bioglitter to disintegrate. The storage stability at 40°C for Example 3 is only two months, whereas the other examples achieved a storage stability of more than six months.

Claims

Adhesive composition containing biodegradable glitter particles and at least the following components: a) at least one biodegradable binder; b) at least one biodegradable thickener; c) at least one preservative; and d) water. Adhesive composition according to claim 1, characterized in that the glitter particles have a base of at least one biodegradable polymer, wherein the base preferably comprises cellulose and / or cellulose derivatives, and wherein the base is coated with metal, preferably aluminum. Adhesive composition according to claim 1 or 2, characterized in that the glitter particles are produced by comminuting a metal-coated polymer-based film, in particular a cellulose-based film.Adhesive composition according to one of the preceding claims, characterized in that it further contains at least one humectant, in particular at least one polyol, wherein the humectant is preferably present in a proportion of approximately 1 wt.% to approximately 15 wt.%. Adhesive composition according to one of the preceding claims, characterized in that the biodegradable glitter particles are present in a proportion of approximately 2 wt.% to approximately 10 wt.%, preferably approximately 4 wt.% to approximately 8 wt.%, and the biodegradable binder is present in a proportion of approximately 1 wt.% to about 35 wt.%, preferably from about 2 wt.% to about 20 wt.%, which contains at least one thickener with a proportion of about 0.1 wt.% to about 3 wt.%, which contains at least one preservative agent is contained in a proportion of < 3 wt.% and water is contained in a proportion of approximately 55 wt.% to approximately 90 wt.%. Adhesive composition according to one of the preceding claims, characterized in that component a) is a water-soluble and preferably biodegradable binder according to EN ISO 14851, preferably a natural binder, such as starch and / or starch derivative, and / or a synthetic polymer, such as polyvinyl alcohol. Adhesive composition according to claim 6, characterized in that component a) is an enzymatically branched starch, preferably maltodextrin, and / or an alkaline-digested starch ether, preferably an alkaline-digested propoxylated starch.Adhesive composition according to one of the preceding claims, characterized in that it contains at least one compound from the group consisting of glycerol, sugar alcohol, such as xylitol, polydextrose, and 1,2-propylene glycol as a humectant. Adhesive composition according to one of the preceding claims, characterized in that it contains xanthan gum, microcellulose, microfibrillated cellulose, sodium alginate, carboxymethylcellulose, pectin, and a modified layered silicate as a thickener. Adhesive composition according to one of the preceding claims, characterized in that it contains at least one compound from the group consisting of isothiazolinones, sodium pyrithione, bronopol, phenoxyethanol, and iodopropyl carbamate as a preservative. Adhesive composition according to one of the preceding claims, characterized in that it has a pH in the range from approximately 5.5 to approximately 8.5, preferably from approximately6.0 to approx. 8.

0.

12. Adhesive composition according to one of the preceding claims, further comprising fragrances, pigments, antioxidants, light stabilizers, bleaching agents, pH buffers, and / or defoamers, wherein the proportion of these additives is a maximum of approximately 5% by weight.

13. Adhesive composition according to one of the preceding claims, characterized in that the proportion of natural or renewable raw materials is more than 97% by weight.

14. A container, in particular a bottle or tube with an applicator, containing an adhesive composition according to any one of claims 1 to 13.

15. Use of an adhesive composition according to any one of claims 1 to 13 for decorating and crafting with paper, cardboard, wood, felt, cork, glass and / or textile materials.

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