Environment-friendly bio-based hot melt adhesive

Abstract

The invention discloses an environment-friendly hot melt adhesive based on renewable raw materials. The hot melt adhesive preparation is prepared from bio-based polyester, specifically a combination of polylactic acid and poly (butylene succinate), resin, a plasticizer and a stabilizer. Other additives, such as waxes, fumed silica, lime or tinting pigments, may optionally be added. The used raw materials are sustainable, biodegradable and harmless to the nature. The adhesives exhibit very good adhesion to wood, paper, paperboard and some predominantly non-polar plastics such as PMMA, ABS, PC, PLA or PET, and can be applied to common systems.

Description

Technical Field

[0001] The present invention describes an environmentally friendly hot melt adhesive based on renewable raw materials. Background Art

[0002] The use of renewable raw materials as materials is becoming increasingly important. The driving forces for this development include climate change and the need to use resources that are not dependent on oil. The present invention describes an environmentally friendly hot melt adhesive based on the bio-based polyester polylactic acid (PLA) and the bio-based polyester polybutylene succinate (PBS).

[0003] Adhesive tapes based on renewable raw materials are known from DE202006001693U1. They contain a film consisting of a mixture of polylactic acid (PLA) and at least one aliphatic-aromatic copolyester. Coated on the film is a layer of a pumpable aqueous adhesive compound. The layer is then dried. Specifically disclosed is a pressure-sensitive adhesive, which contains polylactic acid, epoxy soybean oil, polybutylene succinate and citric acid and is fluidized before application. In contrast, hot melt adhesives are solvent-free and water-free adhesives based on thermoplastic polymers. These polymers are solid at room temperature and soften to form a viscous fluid when heated, so they can be used as a melt. When cooled to room temperature, they undergo reversible curing while forming adhesive strength. Other components of conventional hot melt adhesives are resins, waxes, plasticizers, stabilizers and fillers. The most common application areas of conventional hot melt adhesives are the packaging industry, the hygiene industry, the bookbinding industry, the wood and furniture industry and the DIY industry.

[0004] Currently commercially available semi-bio-based hot melt adhesives have a high percentage of bio-based resins and bio-based waxes. The use of bio-based resins and bio-based waxes has been the state of the art for decades. However, the base polymers used are completely petroleum-based.

[0005] Intercol BV sells bio-based hot melt adhesives consisting of 70% natural raw materials.

[0006] Jowat SE GROW sells a bio-based hot melt adhesive consisting of 50% natural raw materials under the trade name.

[0007] Henkel Supra ECO is a bio-based hot melt adhesive marketed under the trade name Supra ECO. Despite the high proportion of renewable raw materials, the base polymer is synthetic.

[0008] Patent WO2015153226A1 describes a bio-based hot melt adhesive. Its base polymer is PLA. In addition, no other bio-based polymers, bio-based rosin resins or bio-based terpene resins are used as tackifiers or bio-based plasticizers.

[0009] Patent WO2013162058A1 describes environmentally friendly hot melt adhesives. In addition to bio-based raw materials, petroleum-based raw materials are also described.

[0010] Patent WO2002053376A2 describes a biodegradable and compostable hot melt adhesive based on PLA. Apart from this, no other bio-based polymers, bio-based rosin resins or bio-based terpene resins are used as tackifiers.

[0011] Patent US9428645B2 describes an environmentally friendly hot melt adhesive based on bio-based raw materials and petroleum-based raw materials.

[0012] US2014 / 0329065A1 relates to a biodegradable film having a print layer, a resin layer, an adhesive layer and an optional carrier layer. The carrier layer is preferably composed of paper, cotton fabric or fiber web. Polylactic acid (PLA) is a part of the resin layer and / or the adhesive layer. It can be mixed with a variety of natural polymers or synthetic polymers including polybutylene succinate (PBS). In addition, a plasticizer may also be present, such as citric acid, citric acid esters, epoxidized vegetable oils, fatty acid esters, polyethylene glycol or glycerides. The adhesive layer forms the outside of the biodegradable film.

[0013] Bio-based polyesters such as PLA or PBS often lack sufficient compatibility with commercially used resins. In addition, bio-polyesters are brittle and highly viscous compared to commonly used polymers such as EVA or PO, which means that the development of commercial hot melt adhesives based on bio-based polyesters has not been successful until now.

[0014] PLA and PBS are not currently used to formulate hot melt adhesives and pressure-sensitive hot melt adhesives. The only base polymers used are ethylene vinyl acetate (EVA), certain polyolefins (PO) and styrene butadiene copolymers (SBC). These polymers have been optimized for hot melt adhesives in recent decades.

[0015] PLA and PBS are currently used mainly for injection molded parts and flexible packaging. Compared with the number of commercially available types of these polymers, only a few different types of PBS and a few types of PLA are available. Compared with conventional polymers, PLA and PBS have the problems of insufficient flexibility, high melting point and high melt viscosity, which are very important for hot melt adhesives. In addition, compatibility with other ingredients (resins, waxes) is another issue. Compatibility with polymers must be considered, as well as the related effects on the solidification characteristics, flow characteristics and curing characteristics and the interaction with polymer components at phase boundaries. These factors have an important influence on the morphology that occurs during production. The number, size and form of the phases present and their interactions exert authoritative control on the macroscopic properties. Only formulations with good compatibility, i.e. without phase separation or phase stratification of the individual components, are suitable for use as hot melt adhesives.

[0016] Furthermore, bio-based polyesters are susceptible to hydrolytic chain degradation, especially at relatively high temperatures over relatively long periods of time. Summary of the invention

[0017] The object of the present invention is to produce a hot melt adhesive based on PLA and PBS which overcomes the disadvantages described in the prior art such as low flexibility and high melting point and which will also be fully biodegradable.

[0018] The object of the present invention is to use a combination of PLA and PBS as a base polymer for a hot melt adhesive, and process it with a corresponding matching resin, a plasticizer and a stabilizer to obtain a fully bio-based hot melt adhesive. Other fillers such as wax, fumed silica, lime or coloring pigments can be optionally added.

[0019] The subject of the present invention is therefore a hot-melt adhesive formulation comprising:

[0020] At least one polylactic acid (polylactide) having a glass transition temperature higher than 50°C, a melt flow index higher than 25 g / 10 min measured at a temperature of 210°C and a load of 2.16 kg, a weight average molecular weight M of 120,000 g / mol to 280,000 g / mol w 、19.2(J / cm 3 ) 0.5 to 21.1(J / cm 3 ) 0.5 The at least one polylactic acid has a Hansen solubility parameter of 5 to 45 wt % based on the total weight of the hot melt adhesive formulation;

[0021] At least one polybutylene succinate having a melt flow index of 3 g / 10 min to 26 g / 10 min measured at a temperature of 190° C. and under a load of 2.16 kg, a weight average molecular weight Mw of 60,000 g / mol to 190,000 g / mol, a thermal conductivity of 20.1 (J / cm 3 ) 0.5 to 21.2(J / cm 3 ) 0.5 The at least one polybutylene succinate is present in an amount of 10% to 55% by weight based on the total weight of the hot melt adhesive formulation;

[0022] At least one naturally occurring resin having a melting temperature of 60°C to 150°C, a melt viscosity of 80 mPa·s to 24000 mPa·s at 140°C, a viscosity of 16.0 (J / cm 3 ) 0.5 to 21(J / cm 3 ) 0.5 The at least one naturally occurring resin is present in an amount of 30% to 55% by weight based on the total weight of the hot melt adhesive formulation;

[0023] at least one tri(C2-C8)alkyl citrate or tri(C2-C8)alkyl acetyl citrate as a plasticizer, in a proportion of 5 to 15% by weight, based on the total weight of the hot melt adhesive formulation; and

[0024] At least one epoxidized vegetable oil as a stabilizer in a proportion of 0.5 to 1.5 wt %, based on the total weight of the hot melt adhesive formulation.

[0025] Unless otherwise stated, all percentage figures in this patent are weight percentages based on the total mass of the corresponding preparation. DETAILED DESCRIPTION

[0026] The most important thing about hot melt adhesive formulations based on PLA and ABS is its compatibility with the other adhesive components. Compatibility can be determined by the Hansen Solubility Parameters. This is based on the basic idea that like dissolves like and is expressed in (J / cm 3 ) 0.5 Therefore, the selected raw materials are preferably those with the same or similar solubility parameters. The premise for two components to be fully miscible with each other even at high temperatures is that the difference in their solubility parameters is no more than 1.0 (J / cm 3 ) 0.5 .

[0027] In practice, compatibility is assessed by visual inspection in the melt and in the solid. If the materials undergo visibly phase separation, the mixture is rated as incompatible.

[0028] The base polymer of the hot melt adhesive formulation defines the basic properties of the hot melt adhesive, such as processing temperature, adhesion, chemical and hydrolytic stability, softening range and curing mechanism. The combination of PLA and PBS is used as the base polymer of the adhesive formulation of the present invention. Through this combination, the performance of the two polymers is combined together, thereby overcoming the shortcomings of the individual polymers and strengthening the advantages. The use ratio of the base polymer is 40% to 65%.

[0029] Polylactic acid (PLA) is a semi-crystalline to fully amorphous, bio-based and biodegradable polymer. Commercially available PLA has a glass transition temperature of 53°C to 64°C, a melting range of 150°C to 100°C, and a melt flow rate (MFR) of 6 g / 10 min to 80 g / 10 min [210°C / 2.16 kg]. The Hansen solubility parameter is 19.2 (J / cm 3 ) 0.5 to 21.1(J / cm 3 ) 0.5 PLA suitable for the present invention has a very high glass transition temperature, preferably >50°C, and a very high MFR, preferably >25 g / 10 min [210°C / 2.16 kg]. For the present invention, it has been shown that the average molecular weight M w PLA with a weight of 120,000 to 200,000 g / mol is particularly suitable.

[0030] Polybutylene succinate (PBS) is a crystalline, bio-based and biodegradable plastic. The glass transition temperature of PBS is -40°C to -31°C, the melting range is 85°C to 115°C, and the MFR is 3g / 10min to 26g / 10min [190°C / 2.16kg]. The Hansen solubility parameter is 20.9 (J / cm 3 ) 0.5 For the present invention, the weight average molar mass M of PBS is w Preferably it is 60000 g / mol to 190000 g / mol.

[0031] Hot melt adhesives based on PBS have high thermal stability, but poor bonding performance. On the contrary, hot melt adhesives based on PLA have good bonding performance, but low heat distortion temperature. According to the present invention, by combining these two polymers, a hot melt adhesive can be produced that not only has high shape stability when heated, but also has excellent bonding performance.

[0032] The combination of 50% to 75% of low melting point PBS (85°C) and 25% to 50% of high melting point PBS (115°C) has proven to be particularly advantageous. In this case, the high thermal stability of the high melting point PBS can be optimally combined with the better adhesive properties of the low melting point PBS.

[0033] For adhesive formulations, use resins specifically adapted for PLA and PBS. These bio-based resins are added to improve tack, adhesion, and thermal stability, and to reduce processing viscosity. Rosin- and terpene-based resins have proven to be particularly suitable.

[0034] Rosin is a product obtained from resin. Due to its amorphous structure, rosin does not have a definite melting point and is very brittle. In the range from liquid resin to solid resin, it has an average melting temperature of 60°C to 150°C and a viscosity of 80mPa·s to 24000mPa·s at 140°C. The solubility parameter of commercial rosin is usually 17.0(J / cm 3 ) 0.5 to 19.5(J / cm 3 ) 0.5 However, for the present invention, using a 3 ) 0.5 , preferably 19.2 (J / cm 3 ) 0.5 to 21.1(J / cm 3 ) 0.5 The resin is formulated with specific solubility parameters to ensure good compatibility with biopolyesters. In addition, for most applications, the resin contributes to the flexibility of the adhesive formulation. This is achieved through a softening point of about 25°C to 35°C, at which point the resin has a particularly flexible structure, thus optimizing the overall formulation for applications in this temperature range.

[0035] Terpenes are hydrocarbon compounds which occur almost exclusively as minor components in plants. The most important terpene representatives for hot melt adhesive resins are α-pinene, β-pinene and D-limonene. Polyterpenes or terpene resins consist of multiple isoprene units (C5H8) n Terpene resins are amorphous and have a melting range of 60°C to 170°C. The solubility parameter of commercial terpene resins is 16.2 (J / cm 3 ) 0.5 to 20.9(J / cm 3 ) 0.5 The preferred terpene resin of the present invention has a Hansen solubility parameter of >20.0 (J / cm 3 ) 0.5 .

[0036] For the present invention, a resin that is solid at room temperature is preferred, the resin having a melting temperature below 120°C and a melt viscosity below 1000 mPa·s at 160°C. The resin is preferably designed to exhibit high impact toughness and relatively high flexibility at room temperature. In addition, the preferred resin is characterized by excellent hot tack, so that high thermal stability can be achieved despite the low softening temperature. In the adhesive formulation of the present invention, the bio-based resin accounts for 30% to 65% of the total mass, preferably 40% to 55% of the total mass.

[0037] Use appropriate plasticizers to soften biopolyesters. They are used to soften the adhesive and reduce the processing temperature. Plasticizers can be mixed with PLA and PBS first or added directly during the production of hot melt adhesives.

[0038] Bio-based plasticizers suitable for the present invention are certain citrate esters. These citrate esters include triethyl citrate; relatively long-chain citrate esters such as acetyl tributyl citrate and tributyl citrate are particularly suitable, and the plasticizer is preferably mixed with PLA in advance. Based on the proportion of PLA in the adhesive formulation, a plasticizer proportion of 10% to 25% is particularly effective. By adding plasticizers, the elastic modulus, tensile strength and Shore hardness can be reduced, so that the modified PLA reaches the mechanical properties of commercially available EVA. In particular, the tensile elongation is greatly increased. This leads to sufficient softening of very hard hot melt adhesives with polylactic acid as a component.

[0039] The addition of plasticizers to PBS leads to a deterioration of the adhesive and cohesive properties without significant flexibilization. However, surprisingly, the combination of a PLA / plasticizer mixture and PBS does not lead to a deterioration of the properties; on the contrary, the advantages of the plasticized PLA are retained and further improved by the properties of PBS. As a result, the formulation is strongly flexibilized, with a corresponding increase in impact toughness and a simultaneous decrease in viscosity, so that it can actually be used for processing adhesives in the planned application areas.

[0040] In order to stabilize against hydrolytic decomposition, epoxidized vegetable oils are used. Particularly suitable are epoxidized linseed oil or epoxidized soybean oil, which are added in a proportion of less than 1.5% and can be used as plasticizers, stabilizers or to prevent hydrolysis. The present invention preferably uses epoxidized vegetable oils with an epoxide content of 0.5% to 9.5%, an acid value of 0.1 [mg KOH / g] to 1.0 [mg KOH / g] and a viscosity of about 500 mPa·s to 1500 mPa·s at 25°C. In industrial operations, hot melt adhesives are often exposed to relatively high temperatures for relatively long periods of time. In the processing of hot melt adhesives, stable viscosity is an important characteristic. By adding stabilizers, the viscosity reduction is up to 50% at a temperature load of 160°C for more than 24 hours.

[0041] To formulate hot melt adhesives with PLA and PBS, plasticizers, resins, and stabilizers must be compatible with each other to avoid phase separation. In addition, the adhesive properties and heat distortion temperature must not be reduced due to adjuvants, and ideally, they should be further improved.

[0042] The hot melt adhesive formulation of the present invention is composed of 5% to 45% of PLA, 10% to 55% of PBS, 30% to 55% of resin, a maximum of 15% of plasticizer, and 0.5% to 1.5% of stabilizer.

[0043] Hot melt adhesives are usually produced in stirred reactors in batch processes. Here, extrusion takes place only in special cases. However, in stirred reactors, relatively long residence times are required, which means that the temperature load of the raw materials used should be relatively long. The biopolymers used are more susceptible to thermal decomposition processes under prolonged temperature load, which means that extrusion processes are suitable when formulating hot melt bioadhesives. This process allows firstly a considerable reduction in residence times and secondly lower temperatures to be used. For hot melt adhesives, underwater pelletization poses additional challenges. Their stickiness can lead to problems in producing uniformly shaped pellets at room temperature (RT). Therefore, in this process, the water bath is additionally cooled to 5°C to 10°C by an external heat exchanger. In the production of the adhesive formulation, PLA and PBS are metered in the form of pellets in the feed zone at 20°C to 30°C. The resins are fed in molten form into the compression zone at temperatures of about 140°C to about 170°C. After further liquid metering, a mixture of plasticizers and stabilizers is introduced into the compression zone. Alternatively, PLA may be first mixed with a plasticizer and pelletized at 140°C to 160°C in a first step.

[0044] The formulation of the present invention comprises 5% to 45% PLA, 10% to 55% PBS, 30% to 55% resin, 0.5% to 1.5% epoxidized vegetable oil and up to 5% to 15% plasticizer. Additives may optionally be added to reduce costs and / or color. These additives may be up to 20% by weight based on the overall formulation. Additives are, for example, fillers, lime, coloring pigments or fumed silica. Additives are preferably particles with an equivalent spherical diameter of no more than 150 μm, more preferably 0.1 μm to 100 μm, and especially 1 μm to 25 μm.

[0045] To further improve the properties of the hot melt adhesive, bio-based waxes can optionally be added. They are primarily used to reduce viscosity and to reduce open and set times. Carnauba wax, candelilla wax and stearin wax have proven to be particularly suitable.

[0046] Carnauba wax is a wax obtained from the leaves of the carnauba palm tree. Carnauba wax is light yellow to green in color and is the hardest natural wax. Its melting point is high for a wax, at 80°C to 87°C.

[0047] Candelilla wax is a wax obtained from the leaves and stems of the Candelilla shrub. It is hard, brittle, yellow-brown, opaque to translucent, with a melting point of 67°C to 79°C.

[0048] Stearin is a mixture of stearic acid and palmitic acid, obtained from the corresponding triglycerides after saponification and acidification of soap solution. The melting range of stearin depends on the ingredients and is between 55°C and 70°C.

[0049] For the present invention, waxes that are solid at room temperature are preferred, the waxes having a softening temperature below 90° C. and a melt viscosity below 1000 mPa·s at 100° C. Preferred waxes having these characteristics are carnauba wax, candelilla wax or stearic wax. In the adhesive formulation of the present invention, the bio-based wax accounts for 0% to 20% of the total mass.

[0050] Hot melt adhesives can be used in the form of granules or blocks or sticks. For fast operations in the packaging industry or the hygiene industry, hot melt adhesives with low viscosity properties and fast setting properties are particularly preferred. Therefore, formulations with relatively low ratios (<50%) of PLA and PBS and relatively high ratios (>50%) of resin and plasticizer are suitable. Tailing also plays a special role here. Tailing should be as low as possible to facilitate precise application and minimize contamination of the system. Extremely low tailing can be achieved by combining PLA and PBS in a ratio of 2:8 to 8:2.

[0051] In these applications, adhesive properties and thermal stability play a secondary role, since the products produced with them usually have a short lifespan. Here, formulations with a relatively high plasticizer content (>10%) and a relatively high PLA content (>40%) are preferred. A high proportion of PLA ensures a shorter setting time compared to PBS and, due to the high plasticizer content, a low viscosity can be achieved.

[0052] Thermal stability and strength play an important role in edge gluing in the bookbinding sector or in the wood and furniture industry. Low viscosity is not essential. Therefore, for this application, only small amounts of plasticizers (<5%) and high proportions of polymers (>55%) and resins (>40%) are used. In the DIY sector as well, for example, viscosity plays a minor role in glue sticks. Here, a low melting point and good adhesive properties are important to ensure good handling.

[0053] The following examples serve to illustrate the present invention.

[0054] Raw materials used

[0055] (A1) Base polymer: polylactic acid, CAS No.: 26100-51-6, "Ingeo 4060D" from Natureworks LLC, melting point: 160°C, MFR (210°C / 2.16 kg)

[0056] (A2) Base polymer: polybutylene succinate, CAS No.: 25777-14-4, "Bio-PBS FZ91PM" from Mitsubishi Chemical, melting point: 115°C, MFR (190°C / 2.16kg)

[0057] (A3) Base polymer: polybutylene succinate, CAS No.: 25777-14-4, "Bio-PBS FD92PM" from Mitsubishi Chemical, melting point: 84°C, MFR (190°C / 2.16 kg)

[0058] (A4) Base polymer: polyhydroxyalkanoate PHACT a1000p from Helian Polymers BV; melt flow index (MFI) at 160° C. and a load of 5 kg: 5 g / 10 min; amorphous poly[(R)-3-hydroxybutyrate-co-4-hydroxybutyrate] (P3HB4HB)

[0059] (B1) Tackifier: Rosin, from Robert Kraemer's PP 1181", softening range: 60℃ to 80℃

[0060] (B2) Tackifier: Rosin, from Robert Kraemer's PP 1017", softening range: 80℃ to 100℃

[0061] (B3) Tackifier: terpene resin, from DRT's " H150", softening range: 80℃ to 120℃

[0062] (B4) Tackifier: terpene resin, from Kraton's " TP 300", 100°C to 130°C

[0063] (B5) Tackifier: terpene resin, from Kraton's " TP 2040", 110°C to 140°C

[0064] (B6) Tackifier: Rosin, from Robert Kraemer RK 8133; liquid at room temperature, viscosity: about 9000mPa·s at 60℃

[0065] (B7) Tackifier: Rosin, from Robert Kraemer RK 6898; solid at room temperature, melting point: 80°C, viscosity (160°C): less than 500mPa·s

[0066] (C1) Plasticizer: Tributyl acetyl citrate, CAS No.: 77-90-7

[0067] (C2) Plasticizer: tributyl citrate, CAS No.: 77-94-1

[0068] (D1) Wax: Carnauba wax, CAS No. 8015-86-9, "Carnaubawachs LT124" from TH.C.TROMM, solidification point: 80°C to 87°C

[0069] (D2) Wax: Candelilla wax, CAS No. 8006-44-8, "Candelillawachs LT201BI" from TH.C.TROMM, solidification point: 65°C to 73°C

[0070] (D3) Wax: stearic wax, CAS No.: 22610-63-5, "TeCe-Stearin I" from TH.C.TROMM, solidification point: 55°C to 59°C

[0071] (E1) Stabilizer: Epoxidized linseed oil, from Hobum Oleochemicals ELO", CAS No.: 8016-11-3, viscosity: 700mPa·s to 1300mPa·s at 25°C

[0072] (E2) Stabilizer: Epoxidized soybean oil, “Merginat ESBO” from Hobum Oleochemicals, CAS No.: 8013-07-08, viscosity: 400 mPa·s to 600 mPa·s at 20°C

[0073] method

[0074] (M1) Tensile shear strength [MPa] according to DIN EN 1465: Two steel plates are glued together with an overlap area of ​​12.5 mm x 25 mm and pulled apart using a tensile testing machine. The determined tensile shear strength describes the bonding strength (adhesion, cohesion) of the adhesive.

[0075] (M2) Determination of Shear Adhesion Failure Temperature (SAFT) [°C] according to ASTM D4498: Two steel plates are bonded together with an overlap area of ​​25 mm x 25 mm. The bonded plates are suspended and loaded with a weight of 200 g. They are then heated in a drying cabinet at 2°C / min. The temperature at which the bond separates is called SAFT. It provides information about the thermal stability of the adhesive.

[0076] (M3) Melting point [° C.] in accordance with DIN EN ISO 11357: The melting point is determined by DSC (differential scanning calorimetry). The measuring range is −50° C. to 200° C. The heating rate is 20 K / min.

[0077] (M4) Viscosity [mPa·s] at 160 °C according to DIN EN ISO 3219: The viscosity is determined by plate / plate rheometer. It provides information about the deformation and flow properties of the adhesive at a specific temperature. During the measurement, the sample is sheared between a rotating or oscillating part and a stationary part of the device. The shear rate is the product of the geometry of the measuring device and the speed of the moving parts. The torque required to maintain the movement is measured and can then be used to determine the shear stress and thus the viscosity and other rheological parameters.

[0078] (M5) Open time [s]: The open time is defined as the time after which the adhesive is no longer tacky. At fixed intervals, a wooden pick is pressed against the adhesive bead (applied at 160°C) and pulled off. Once the pick sticks (cohesive fracture), the hot melt adhesive is rated as "open". When the pick no longer sticks to the hot melt adhesive bead, the hot melt adhesive is no longer open.

[0079] (M6) Setting time [s]: The setting time describes the time that passes before the adhesive develops significant cohesion. Apply a little adhesive to the end of a wooden skewer. Immediately press the same skewer at a 90° angle to create an overlapping and bonded area. At the same time, start measuring the time. At regular intervals, try to twist the skewer manually (not too hard) and determine the time until the skewer can no longer be moved.

[0080] Embodiment 1:

[0081] For typical hot melt adhesives, PLA was first dried at 45°C, and both types of PBS were dried at 60°C for 4 hours. Mixing was carried out in a Leistritz ZSE 27MAXX twin-screw extruder with a screw length of 1.12m, a screw diameter of 28mm, a temperature of 125°C to 160°C, a total output of 8kg / h to 10kg / h, a screw speed of 80rpm to 150rpm, and a set point pressure of 5 bar.

[0082] The two types of PBS were premixed in a pellet mixer, after which PLA and the two types of PBS were metered separately in the feed zone at 20°C to 30°C by a single screw feeder of the type DS28 from Brabender. The resin was supplied at 150°C in the compression zone by a heated liquid feeder. The plasticizer was metered at room temperature in the compression zone by a liquid feeder of the type FDDW-MP from Brabender. The melt was discharged by an underwater pelletizer with an outlet temperature of 120°C to 130°C, a cutting blade speed of 500 rpm to 1500 rpm and a water temperature of 5°C to 20°C. Formulations R1 to R4, as well as R13 and R14 were produced in this way. Due to their high adhesion and high thermal stability, these formulations are particularly suitable for the textile industry, the footwear industry and the automotive industry.

[0083] Example 2

[0084] The preparations were produced very similarly to Example 1. To achieve a relatively low melting point, the relatively high melting point PBS FZ91 was removed. Therefore, no premixing was required as in Example 1. In addition, in preparations R7 and R8, a terpene resin was used to improve adhesion on the specified substrate. The resin was supplied at 170° C. in the compression zone by a heated liquid feeder. Preparations R5 to R8 were produced in this way. Due to the relatively low melting point, these preparations are particularly suitable for glue sticks.

[0085] Example 3

[0086] The preparation was produced very similarly to Example 1. To achieve a relatively high thermal stability, the low melting point PBS FD92 was removed. Therefore, no premixing was required as in Example 1.

[0087] The rosin in R9 was supplied at 150°C in the compression zone by a heated liquid feeder, and the terpene resins in R9 to R11 were supplied at 170°C in the compression zone by a heated liquid feeder. Formulations R9 to R12 were produced in this way. Due to their high thermal stability and high viscosity, these formulations are particularly suitable for edge gluing in the wood and furniture industry.

[0088] Example 4

[0089] The production of the formulations is very similar to Example 1. In addition, various waxes are metered in the feed zone at 20° C. to 30° C. by a twin screw feeder of the type DDSR20 from Brabender. The resin is supplied in the compression zone at 150° C. by a heated liquid feeder. Formulations R15 to R20 are produced in this way. The use of waxes reduces the viscosity and processing time of the adhesive system. Therefore, these formulations are particularly suitable for the fast operations common in the packaging industry.

[0090]

[0091]

[0092]

[0093]

[0094]

[0095]

[0096]

[0097]

[0098]

[0099]

[0100]

[0101]

[0102]

[0103] A1: Ingeo 4060D type PLA

[0104] A2: FZ91PM Bio-PBS

[0105] A3: FZ92PM Bio-PBS

[0106] A4: Amorphous poly[(R)-3-hydroxybutyrate-co-4-hydroxybutyrate] (PHACT)

[0107] B1: PP 1181 Rosin

[0108] B2: Bremar PP 1017 rosin

[0109] B3: H150 terpene resin

[0110] B4: TP 300 terpene resin

[0111] B5: Sylvares TP 2040 terpene resin

[0112] B6: Bremar RK 8133 rosin

[0113] B7: Rokrapol RK 6898 rosin

[0114] C1: Acetyl tributyl citrate (ATBC)

[0115] C2: Tributyl citrate

[0116] D1: Carnaubawachs LT 124 type carnauba wax

[0117] D2: Candelillawachs LT 281BI Candelilla wax

[0118] D3: Stearinwachs TeCe-Stearin I stearic wax

[0119] E1: ELO Epoxidized Linseed Oil

[0120] E2: Merginat ESBO type epoxidized soybean oil

[0121] M1: Tensile shear strength [MPa]

[0122] M2: Thermal stability [℃]

[0123] M3: Melting point [℃]

[0124] M4: Viscosity [mPa·s]

[0125] M5: Opening time [s]

[0126] M6: Solidification time [s]

[0127] Comparative Example:

[0128] According to the detailed information of the layer identified as "resin layer" in the examples of US2014 / 0329065A1, the following formulations were studied:

[0129]

[0130] All components except calcium carbonate were mixed in an anchor stirrer at 180°C for about 120 minutes. After the addition of calcium carbonate, the formulation showed very high viscosity. Stearic wax is incompatible with polylactic acid, resulting in separation.

[0131] Due to the poor homogeneity and compatibility of these components, no studies could be performed to characterize the mixture. In the absence of adhesion promoters, the adhesion properties were insufficient.

Claims

1. A hot melt adhesive preparation comprising: At least one polylactic acid having a glass transition temperature higher than 50° C., a melt flow index higher than 25 g / 10 min measured at a temperature of 210° C. and under a load of 2.16 kg, a weight average molecular weight M of 120,000 g / mol to 280,000 g / mol w and 19.2(J / cm 3 ) 0.5 to 21.1(J / cm 3 ) 0.5 The at least one polylactic acid has a Hansen solubility parameter of 5 to 45 wt % based on the total weight of the hot melt adhesive formulation; At least one polybutylene succinate having a melt flow index of 3 g / 10 min to 26 g / 10 min measured at 190° C. and under a load of 2.16 kg, a weight average molecular weight M of 60,000 g / mol to 190,000 g / mol w and 20.1(J / cm 3 ) 0.5 to 21.2(J / cm 3 ) 0.5 The at least one polybutylene succinate is present in an amount of 10% to 55% by weight based on the total weight of the hot melt adhesive formulation; At least one naturally occurring resin having a melting temperature of 60°C to 150°C, a melt viscosity of 80 mPa·s to 24000 mPa·s at 140°C, and a viscosity of 16.0 (J / cm 3 ) 0.5 to 21(J / cm 3 ) 0.5 The at least one naturally occurring resin is present in an amount of 30% to 55% by weight based on the total weight of the hot melt adhesive formulation; at least one tri(C2-C8)alkyl citrate or tri(C2-C8)alkyl acetyl citrate as a plasticizer, in a proportion of 5 to 15% by weight, based on the total weight of the hot melt adhesive formulation; and At least one epoxidized vegetable oil as a stabilizer in a proportion of 0.5 to 1.5 wt %, based on the total weight of the hot melt adhesive formulation.

2. The hot melt adhesive formulation according to claim 1, comprising up to 20% by weight of one or more additives, based on the total weight of the hot melt adhesive formulation, the additives are preferably fillers, lime, color pigments or fumed silica, the additives are preferably particles with an equivalent spherical diameter of not more than 150 μm, more preferably 0.1 μm to 100 μm, and especially 1 μm to 25 μm.

3. The hot melt adhesive formulation according to claim 2, wherein the additive is a bio-based wax having a softening temperature below 90°C and a melt viscosity below 1000 mPa·s at 100°C, and the bio-based wax is preferably carnauba wax, candelilla wax or stearic wax.

4. The hot-melt adhesive formulation according to claim 1 , wherein the epoxidized vegetable oil is epoxidized linseed oil or epoxidized soybean oil, in each case having an epoxide content of 8.5 to 9.5% by weight, an acid number of 0.1 to 1.0 mg KOH / g, and a viscosity at 25° C. of 500 to 1500 mPa·s.

5. The hot melt adhesive formulation according to one or more of claims 1 to 4, wherein the citrate ester is triethyl citrate, tributyl citrate or acetyltributyl citrate.

6. The hot melt adhesive formulation according to one or more of claims 1 to 5, comprising a combination of 50% to 75% by weight of polybutylene succinate having a melting point or melting range of 60° C. to 90° C. and 50% to 25% by weight of polybutylene succinate having a melting point or melting range of 110° C. to 125° C.

7. The hot melt adhesive formulation according to one or more of claims 1 to 6, wherein the naturally occurring resin is a rosin or terpene-based resin having a Hansen solubility parameter in each case above 20 (J / cm 3 ) 0.5 .

8. The hot melt adhesive formulation according to one or more of claims 1 to 7, wherein: The Hansen solubility parameters of the components defined in claim 1 differ from each other by no more than 1.0 (J / cm 3 ) 0.5 , preferably not higher than 0.5 (J / cm 3 ) 0.5 .

9. Use of the hot-melt adhesive preparation according to one or more of claims 1 to 8 as bookbinding glue, furniture glue or for bonding paper, cardboard or non-polar plastics such as PMMA, ABS, PC or PET.

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