F1ELD OF THE INVENTION

The present invention relates to a reinforced biodegradable composite material. More particularly, the invention relates to a reinforced polylactic acid based composite material with good heat resistance and toughness. The invention further relates to an article comprising said composite material.

BACKGROUND OF THE INVENTION

ln recent years, environmental pollution due to the high impact of plas tic waste in daily use has become a great concern. One of the possible solutions to this problem is to replace the commodity synthetic polymers with biodegradable polymers that are readily susceptible to hydrolysis and microbial action. Polylactic acid (PLA) and polybutylene succinate (PBS) are examples of environmentally- friendly biodegradable polymers which aim to replace commodity synthetic petro leum based polymers.

PLA is a biodegradable thermoplastic aliphatic polyester produced from renewable resources. PLA has good mechanical properties and therefore is a good polymer for various end-use applications. However, other properties of PLA like impact strength, heat deflection temperature (HDT), gas permeability, melt viscos ity for processing, toughness etc. are not good enough in applications like durable goods. Since PLA as a raw material has been quite expensive and the production speed of PLA is quite low, it has not been economically feasible to apply PLA in day- to-day use as a consumable or durable goods material.

The various properties of PLA can be modified by mixing PLA with an other suitable biodegradable polymer which has comparably better temperature resistance, impact strength and melt processability, for example. This method can be ineffective due to incompatibility of the two polymers (which is required to pro duce intermediate properties) and can reduce the renewable content and com- postability of the material. PLA has been blended with polybutylene succinate (PBS) which has high flexibility, moderate impact strength, and thermal and chem ical resistance.

WO 2015/000081 A1 discloses a heat resistant composition comprising polylactic acid, polyfbutylene succinate) and a compostable polyester.

The problem of blending PLA and PBS together is the miscibility of these blends and the extent of miscibility is not entirely clear lt has been reported that the Tg of PLA did not change with addition of PBS, and hence concluded that the blends were immiscible, although they found that rheological results showed com patibility when the PBS content was below 20 weight %. On the other hand, it has been observed that PBS was miscible with PLA up to an addition level of 10 weight %. However, it has also been reported that PBS and PLA are thermodynamically incompatible and the blends exhibited an immiscible phase structure, with a phase inversion point of the blend system at a PLA/PBS ratio of 50/50.

Results reported in the literature for increasing the toughness of PLA on blending with PBS are somewhat disappointing. No improvement in the ductility (strain-to-break) of PLA/PBS blends was observed until the PBS content reached 90 weight %. The tensile strength decreased up to 80 wt% contents of PBS and then slightly increased at more than 80 wt% PBS contents. The same type of behavior was seen in Young’s modulus.

Another way to increase the mechanical properties and heat resistance of PLA is by creating a composite through the addition of fillers which increase the stiffness of the material. However, this method can also reduce the impact re sistance of the material, making it even more brittle and unsuitable in a number of applications. Another method of increasing the HDT of PLA is to increase the crys tallinity, reducing the volume of amorphous material that softens at glass transition temperature, thereby allowing the product to retain its shape at higher tempera tures. lncreasing crystallinity however, often requires increasing the cooling time during molding or downstream after extrusion, which reduces the efficiency of the manufacturing process i.e. production speed. PLA crystallization as neat polymer is slow and requires nucleating agents, high crystallization temperature e.g. high mold temperature to speed up crystallization, even with the aid of nucleating agents the crystallization times are long and production speed too low compared to commodity synthetic petroleum based polymers e.g. PP and ABS. Moreover, such a high mold temperatures are not industry standard and requires investments.

There is still a need for biodegradable and compostable PLA based ma terials that are commercially viable, have high bio-based material content, and ex hibit good mechanical properties, such as good impact resistance, high resistance to deformation, especially at elevated temperatures, good melt flow properties for injection molding and low cost.

BR1EF DESCRIPTION OF THE INVENTION

lt was surprisingly found in the present invention that mechanical prop erties and heat resistance of PLA can be improved by blending PLA with polybutyl ene succinate, i.e. another biodegradable polymer, and by reinforcing the blend with glass fiber regardless of immiscibility of PLA and PBS blends.

Further, it was surprisingly found in the present invention, articles with good physical properties can be produced at low cost from a blend of PLA and PBS by introducing glass fiber to the blend.

Thus, in an aspect, the present invention provides a reinforced compo site material comprising glass fiber and a polymer blend comprising polylactic acid and polybutylene succinate, wherein the composite material comprises about 10 wt-% to about 80 wt-% of glass fibre, and wherein the polymer blend comprises about 20 wt-% to about 60 wt-% of PLA and about 40 wt-% to about 80 wt-% of PBS.

Even if the prior art discloses that >20 wt-% blends of PLA with PBS are miscible, improvement of the above described shortcomings of PLA are not achieved by blending PLA and PBS in the miscible ratios lt was surprisingly found that good mechanical properties, high temperature resistance and toughness can be achieved by incorporating at least 10 wt-% of glass fibers into PLA/PBS blends when the PLA/PBS ratio is between about 20/80 wt-% to about 60/40 wt-%. More over, with these blending ratios together with glass fibers, the material cost and production cost can be kept low, since glass fiber cost is lower than that of PLA and PBS, and the production cycle times are shorter because crystallization of PLA can be avoided. The improvement of mechanical properties and temperature re sistance increase with glass fiber content of at least 10 wt-%. Reduction of material cost is directly proportional to the glass fiber content.

ln another aspect, the invention provides an article comprising the re inforced composite material of the invention. The articles include rigid packages, household good, electronic devices, and car interior parts.

The present invention provides a biodegradable PLA based composite material reinforced with glass fiber with high heat resistance and high mechanical properties.

An advantage the composite material of the invention and the article manufactured from the composite material of the invention is that they are biode gradable and compostable.

A further advantage of the composite material of the invention and the article manufactured from the composite material of the invention is that they have high mechanical properties, good impact resistance, good resistance to defor- mation especially at elevated temperatures and/or under load, and good melt flow properties for injection molding ln addition, the cost of the article manufactured from the composite material is low due to no need of in-process crystallization of PLA for achieving high temperature resistance, i.e. heat distortion temperature, and can be processed with comparable cooling time and cycle time with commodity synthetic petroleum based polymers e.g. PP and ABS and low mold temperature 20-50°C.

DETA1LED DESCRIPTION OF THE INVENTION

ln an aspect, the invention provides a reinforced composite material comprising glass fiber and a polymer blend comprising polylactic acid (PLA) and polybutylene succinate (PBS), wherein the composite material comprises about 10 wt-% to about 80 wt-% of glass fibre, and wherein the polymer blend comprises about 20 wt-% to about 60 wt-% of PLA and about 40 wt-% to about 80 wt-% of PBS.

ln the reinforced composite material, any suitable polylactic acid may be used. The terms "polylactic acid", "polylactide" and "PLA" are used interchange- ably to include homopolymers and copolymers of lactic acid and lactide based on polymer characterization of the polymers being formed from a specific monomer or the polymers being comprised of the smallest repeating monomer units. Polylac tide is a dimeric ester of lactic acid and can be formed to contain small repeating monomer units of lactic acid or be manufactured by polymerization of a lactide monomer, resulting in polylactide being referred to both as a lactic acid residue containing polymer and as a lactide residue containing polymer lt should be un derstood, however, that the terms "polylactic acid", "polylactide", and "PLA" are not necessarily intended to be limiting with respect to the manner in which the poly mer is formed.

Suitable PLAs produced from renewable resources include homopoly mers and copolymers of lactic acid and/or lactide which have a weight average mo lecular weight (M _w ) generally ranging from about 10,000 g/mol to about 800,000 g/mol. ln an embodiment, M _w is in the range from about 30,000 g/mol to about 400,000 g/mol. ln another embodiment, M _w is in the range from about 50,000 g/mol to about 200,000 g/mol.

Commercially available polylactic acid polymers which are suitable in the present invention include a variety of polylactic acids that are available from NATUREWORKS® or Total Corbion. Modified polylactic acid and different stereo configurations thereof may also be used, such as poly D -lactic acid, poly L-lactic acid, poly D, L-lactic acid, and combinations thereof.

Polybutylene succinate (PBS) is a biodegradable aliphatic polyester produced by the polycondensation reaction of 1,4-butanediol with succinic acid. Any suitable PBS or a co-polymer thereof can be used in the invention. PBS or a co polymer thereof can be made from renewable or non-renewable resources. PBS may now be completely biobased depending on the choice of monomers.

PBS has high flexibility and moderate mechanical properties, such as impact strength, and good thermal and chemical resistance. PBS, in the form of films and moulded objects, exhibits significant biodegradation within several months in soil, water with activated sludge, and sea water. A disadvantage of PBS is its high cost.

High brittleness, low temperature resistivity as amorphous state of PLA and low mechanical properties with high cost of PBS are the major issues for their commercialization and many applications. Therefore, various properties of PLA and PBS based materials must be improved and the production cost must be low ered in order to make the PLA and PBS based materials commercially viable.

The reinforced composite material comprises a polymer blend compris ing PLA and PBS. The amount of the polymer blend of the composite material is in the range of about 20 wt-% to about 90 wt-%, based on the weight of the composite material ln an embodiment, the amount is in the range of about 60 wt-% to about 90 wt-%.

ln an embodiment, the amount of PLA of the polymer blend is in the range of about 30 wt-% to about 55 wt-% based on the weight of the polymer blend ln another embodiment, the amount of PLA is in the range of about 40 wt-% to about 50 wt-%. ln a further embodiment, the amount of PLA is about 50 wt-%.

ln an embodiment, the amount of PBS of the polymer blend is in the range of about 45 wt-% to about 70% wt-% based on the weight of the polymer blend ln another embodiment, the amount of PBS is in the range of about 50 wt-% to about 60 wt-%. ln a further embodiment, the amount of PBS is about 50 wt-%.

ln addition to PLA and PBS, the polymer blend can comprise further pol ymer (s). ln an embodiment, the optional further polymers are biodegradable. These include, without limiting the polymers thereto: polylactides (PLA), poly-L- lactide (PLLA), poly-DL-lactide (PDLLA); polyglycolide (PGA); copolymers of gly- colide, glycolide/trimethylene carbonate copolymers (PGA/TMC); other copoly mers of PLA, such as lactide/tetramethylglycolide copolymers, lactide/trimeth- ylene carbonate copolymers, lactide/d-valerolactone copolymers, lactide/e-capro- lactone copolymers, L-lactide/DL-lactide copolymers, glycolide/L-lactide copoly- mers (PGA/PLLA), polylactide-co-glycolide; terpolymers of PLA, such as lac- tide/glycolide/trimethylene carbonate terpolymers, lactide/glycolide/e-caprolac- tone terpolymers, PLA/polyethylene oxide copolymers; polydepsipeptides; un- symmetrically 3,6-substituted poly-l,4-dioxane-2,5-diones; polyhydroxyalka- noates, such as polyhydroxybutyrates (PHB); PHB/b-hydroxyvalerate copolymers (PHB/PHV); poly-b-hydroxypropionate (PHPA); poly-p-dioxanone (PDS); poly-d- valerolactone-poly-e-caprolactone, poly(£-caprolactone-DL-lactide) copolymers; methylmethacrylate-N-vinyl pyrrolidone copolymers; polyesteramides; polyesters of oxalic acid; polyesters or copolymers of succinate acid; polydihydropyrans; pol yalkyl-2-cyanoacrylates; polyurethanes (PU); polyvinylalcohol (PVA); polypep tides; poly-b-malic acid (PMLA); poly-b-alkanoic acids; polycarbonates; polyortho esters; polyphosphates; poly(ester anhydrides); and mixtures thereof; and natural polymers, such as sugars, starch, cellulose and cellulose derivatives, polysaccha rides, collagen, chitosan, fibrin, hyalyronic acid, polypeptides and proteins. Mix- tures of any of the above-mentioned polymers and their various forms may also be used.

ln an embodiment, the polymer blend consists of PLA and PBS. ln an embodiment, the polymer blend contains about 20 wt-% to about 60% wt-% of PLA and about 40 wt-% to about 80% wt-% of PBS, based on the weight of the polymer blend, whereby the total amount PLA and PBS adds up to 100 wt-%. ln another embodiment, the polymer blend contains about 30 wt-% to about 55 wt-% of PLA and about 45 wt-% to about 70 wt-% of PBS, the total amount of PLA and PBS being 100 wt-%. ln a further embodiment, the polymer blend contains about 40 wt-% to about 50 wt-% of PLA and about 50 wt-% to about 60 wt-% of PBS, the total amount of PLA and PBS being 100 wt-%. ln a still further embodiment, the polymer blend consists of about 50 wt-% of PLA and about 50 wt- % of PBS, the total amount of PLA and PBS being 100 wt-%.

ln addition to the polymer blend described above, the reinforced com posite material of the invention comprises glass fiber as a reinforcement. Any suit- able glass fiber may be used in the composite material. Glass fiber can be conven tional non-degradable glass fiber, such as E, S, C, AR, ECR. Glass fiber can also be biocompatible, biodegradable, bioresorbable or biosoluble glass fiber ln an em bodiment, the glass fiber has the following composition: S1O2 60-70 wt-%, Na20 5- 20 wt-%, CaO 5-25 wt-%, MgO 0-10 wt-%, P2O5 0.5-5 wt-%, B2O3 0-15 wt-%, AI2O3 0-5 wt-%, L12O 0-1 wt-%, and less than 0.5 wt-% K. ln another embodiment, the glass fiber has the following composition: S1O2 65-75 wt-%, NazO 12-17 wt-%, CaO 8-11 wt-%, MgO 3-7 wt-%, P2O5 0.5-2.5 wt-%, B2O3 1-4 wt-%, K2O >0.5-4 wt-%, SrO 0-4 wt-%, and at most 0.3 wt-% in total of AI2O3 and Fe203.

The glass fiber can have any suitable length and thickness. Glass fiber of length of 5mm or less is typically defined as short glass fiber (SGF). Glass fiber length of more than 5mm is typically defined as long glass fiber (LGF).

The reinforced composite material of the invention comprises about 10 wt-% to about 80 wt-% of glass fiber ln an embodiment, the amount of glass fiber of the composite material is about 15 wt-% to about 70 wt-%. ln another embodi ment, the amount of glass fiber is about 20 wt-% to about 60 wt-%. ln a further embodiment, the amount of glass fiber is about 20 wt-% to about 50 wt-%. ln a still further embodiment, the amount of glass fiber is about 20 wt-% to about 40 wt-%.

ln an embodiment, the present invention provides a compostable and/or biodegradable reinforced composite material ln this embodiment, the composite material contains biodegradable polymers which break down into harmless, environmentally acceptable chemicals, such as water, carbon dioxide and optionally methane. Decomposition of the composite material may occur, for example, through an anaerobic process under certain compost conditions. The de- composition of polymers under compost conditions is usually achieved in the pres ence of soil, moisture, oxygen and enzymes or microorganisms.

The reinforced composite materials of the invention may comprise a va riety of additional ingredients including non-biobased and non-biodegradable in gredients. ln an embodiment, any added ingredient is compostable and/or biode- gradable.

The reinforced composite material of the invention may comprise im pact modifier(s) without compromising already gained properties. Any suitable impact modifier may be used, including core shell acrylic elastomers. The impact modifier may be selected, for example, from Sukano im633 (Sukano), PARAL01D BPM-520 (DowDuPont). The amount of the impact modifier(s) is typically from about 0.1 wt-% to about 20 wt-%, based on the weight of the reinforced composite material ln an embodiment, the amount of the impact modifier(s) is about 1 wt-% to about 10 wt-%. ln another embodiment, the amount is about 2 wt-% to about 8 wt-%. The reinforced composite material of the invention may comprise plas ticizers) without compromising already gained properties. Any suitable plasti- cizer(s) may be used, including triethyl citrate, tributyl citrate, glycerol, lactic acid (monomer and oligomers). The amount of the plasticizer(s) is typically about 0.01 wt-% to about 20 wt-%, based on the weight of the reinforced composite material ln an embodiment, the amount is about 0.1 wt% to about 10 wt-%. ln another em bodiment, the about is about 0.5 wt-% to about 8 wt-%. ln a further embodiment, the amount is about 0.8 wt-% to about 5 wt-%. ln a still further embodiment, the amount is about 1 wt-% to about 4 wt-%.

The reinforced composite material of the invention may comprise flame retardant(s) without compromising already gained properties. Any suitable flame retardant(s) may be used, including Exolit AP 422 (Clariant), pentaerythritol phos phate (PEPA), melamine phosphate (MP) and polyhedral oligomeric silsesquiox- anes (POSS). The amount of the flame retardant(s) is typically about 0.01 wt-% to about 30 wt-%, based on the weight of the reinforced composite material ln an embodiment, the amount is about 0.1 wt-% to about 20 wt-%. ln another embodi ment, the amount is about 0.5 wt-% to about 15 wt-%. ln a further embodiment, the amount is about 3 wt-% to about 12 wt-%.

The reinforced composite material of the invention may comprise anti oxidants) without compromising already gained properties. Any suitable antioxi dant^) may be used, including lrganox series (BASF), lrgafos series (BASF), Hos- tanox series (Clariant). The amount of antioxidant(s) is typically about 0.01 wt-% to about 20 wt-%, based on the weight of the reinforced composite material ln an embodiment, the amount is about 0.1 wt-% to about 10 wt-%. ln another embodi ment, the amount is about 0.5 wt-% to about 8 wt-%. ln a further embodiment, the amount is about 0.8 wt-% to about 5 wt-%. ln a still further embodiment, the amount is about 1 wt-% to about 4 wt-%.

The reinforced composite material of the invention may comprise UV and light stabilizer(s) without compromising already gained properties. Any suita ble UV and light stabilizer(s) may be used, including Hostavin series (Clariant), Cesa block series (Clariant), OnCap Bio series (Polyone). The amount of the UV and light stabilizer (s) is typically about 0.01 wt-% to about 20 wt-%, based on the weight of the reinforced composite material ln an embodiment, the amount is about 0.1 wt-% to about 10 wt-%. ln another embodiment, the amount is about 0.5 wt-% to about 8 wt-%. ln further embodiment, the amount is about 0.8 wt-% to about 5 wt-%. ln a still further embodiment, the amount is about 1 wt-% to about 4 wt-%.

The reinforced composite material of the invention may comprise col orants) without compromising already gained properties. Any suitable color ant^) may be used, including Renol-natur series (Clariant), OnColor Bio series (Polyone). The amount of the colorant(s) is typically about 0.01 wt-% to about 10 wt-%, based on the weight of the reinforced composite material ln an embodiment, the amount is about 0.1 wt-% to about 7 wt-%. ln another embodiment, the amount is about 0.5 wt-% to about 5 wt-%. ln a further embodiment, the amount is about 0.8 wt-% to about 3 wt-%. ln a still further embodiment, the amount is about 1 wt- % to about 2 wt-%.

The reinforced composite material of the invention may comprise anti hydrolysis agent(s) without compromising already gained properties. Any suitable anti-hydrolysis agent(s) may be used, including Carbodilite series (Nisshinbo chemical), Stabaxol series (Lanxess). The amount of the anti-hydrolysis agent(s) is typically about 0.01 wt-% to about 10 wt-%, based on the weight of the reinforced composite material ln embodiment, the amount is about 0.1 wt-% to about 7 wt- %. ln another embodiment, the amount is about 0.5 wt-% to about 5 wt-%. ln a further embodiment, the amount is about 0.8 wt-% to about 3 wt-%. lna still fur ther embodiment, the amount is 1 wt-% to about 2 wt-%.

Examples of other optional ingredients of the reinforced composite ma terial of the invention include, but are not limited to, gum arabic, bentonite, salts, slip agents, crystallization accelerators or retarders, odor masking agents, cross- linking agents, emulsifiers, surfactants, cyclodextrins, lubricants, other processing aids, optical brighteners, antioxidants, flame retardants, dyes, pigments, fillers, proteins and their alkali salts, waxes, tackifying resins, extenders, chitin, chitosan, and mixtures thereof.

The reinforced composite material of the invention may also comprise filler(s) without compromising already gained properties. Suitable filler(s)s in clude, but are not limited to, clays, silica, mica, wollastonite, calcium hydroxide, cal cium carbonate, sodium carbonate, magnesium carbonate, barium sulfate, magne sium sulfate, kaolin, calcium oxide, magnesium oxide, aluminum hydroxide, talc, titanium dioxide, cellulose fibers, chitin, chitosan powders, organosilicone pow ders, nylon powders, polyester powders, polypropylene powders, starches, and mixtures thereof. The amount of the filler(s) is typically about 0.01 wt-% to about 60 wt-%, based on the weight of the reinforced composite material. The reinforced composite material of the invention comprising at least 10 wt-% of glass fiber and a polymer blend of PLA/PBS in a ratio of about 20/80 wt-% to about 60/40 wt-% provides an economic composite material with good heat resistance and good mechanical properties and toughness. The cost of the PLA/PBS based material can be reduced in the present invention by introducing low-cost glass fiber to the material.

When conventional glass fibers are replaced with bioerodible and bio degradable glass fibers, the invention provides a reinforced composite material that is fully compostable.

ln an aspect, the present invention provides a process for the produc tion of the reinforced composite material of the invention. The process of the in vention comprises the steps of:

- providing polylactic acid (PLA), polybutylene succinate (PBS) and glass fiber,

- optionally providing further polymer(s) and ingredients,

- blending PLA, PBS, optional further polymer(s) and optional ingredi ents together under heat treatment to provide a polymer melt in an extruder,

- adding glass fiber to the polymer melt to provide a reinforced polymer melt,

- extruding the reinforced polymer melt to provide a reinforced compo site material,

- optionally pelletizing the reinforced composite material.

When short glass fiber (SGF) is used as a reinforcement, a twin-screw extruder is typically used to mix PLA, PBS and short glass fiber and optional other additives described above. The resultant mixture is extruded to strands and then pelletized to desired length of pellets. Besides of a strand pelletizer, an underwater or water ring pelletizer may be used.

A typical process for making long glass fiber (LGF) reinforced compo site material of the invention, is to use LFT (long fiber reinforced thermoplastics) line. LFT line is a thermoplastic pultrusion process, where continuous glass fiber strands (direct roving or yarn) are impregnated by polymer melt which is usually provided by a twin-screw extruder to the impregnation die. The PLA/PBS blend together with optional additives are melted and mixed in the twin-screw extruder. The formed continuous glass fiber composite strands are then pelletized to the de sired length and used for manufacturing the final article. The heat deflection temperature (HDT) of the reinforced composite ma terial of the invention was measured according to 1SO 75:2013 Plastics - Determi nation of temperature of deflection under load, method B with 0.455 MPa load in case where SGF was used as a reinforcement in the composite material. The HDT of the article of the invention was measured according to 1SO 75:2013 Plastics - Determination of temperature of deflection under load, method A with 1.82 MPa load in case where LGF was used as a reinforcement in the composite material.

The reinforced composite material of the invention exhibits a heat de flection temperature (HDT) of 85°C or higher, measured according to the 1SO stand ard 75 Method B. ln an embodiment, the HDT is 90°C or higher ln another embod iment, the HDT is 95°C or higher ln a further embodiment, the HDT is 100°C or higher.

The reinforced composite material of the invention exhibits a heat de flection temperature (HDT) of 85°C or higher, measured according to the 1SO stand ard 75 Method A. ln an embodiment, the HDT is 90°C or higher ln another embod iment, the HDT is 95°C or higher ln a further embodiment, the HDT is 100°C or higher.

The reinforced composite material of the invention exhibits an impact resistance (lzod notched impact strength) of 10 kj/m ² or above, measured accord ing to the 1SO 180 method 1A notched sample ln an embodiment, the impact re sistance is 20 kj/m ² or above ln another embodiment, the impact resistance is 30 kj/m ² or above.

ln an aspect, the present invention provides an article comprising the reinforced composite material of the invention ln an embodiment, the article is manufactured from the composite material by molding, such as injection molding, blow molding or compression molding ln another embodiment, the article is man ufactured from the composite material by extrusion to provide for examples pipes, tubes, profiles, cables and films. Molded or extruded articles of the invention can be solid objects, such as toys, electronic appliances, and car parts, or hollow objects, such as bottles, containers, tampon applicators, applicators for insertion of medi cations into bodily orifices, medical equipment for single use and surgical equip ment.

ln an embodiment, the article of the invention has an average wall thick ness of 0.6 mm or above.

The PLA/PBS based glass fiber reinforced composites of the present in vention show advantageous properties, i.e. short cooling time and low downstream or mold temperatures, even if PLA is mainly amorphous. An important factor which influences the productivity in injection molding is so-called "Cycle Time". The term "Cycle Time" means the time period required in an injection molding system to mold a part and return to its original position/state and Cycle is complete, re peating sequence of operations for injection molding a part. As such, the term "Cy cle Time" is generally used in the art and the meaning of the term is known to a skilled person.

Cooling time included in the cycle time is always directly related to ar ticle design and wall thickness ln this context low cooling time is meant compara ble cooling time and cycle time with commodity synthetic petroleum based poly mers e.g. PP and ABS. As used herein, the term "mainly amorphous" refers to com positions showing no or low levels of crystallinity. The present compositions are preferably fully compostable, where traditional glass fibers are replaced with bio- erodible and biodegradable glass fibers.

lt is contemplated that the different parts of the present description may be combined in any suitable manner. For instance, the present examples, methods, aspects, embodiments or the like may be suitably implemented or com bined with any other embodiment, method, example or aspect of the invention. Un less defined otherwise, all technical and scientific terms used herein have the same meaning as is commonly understood by one of ordinary skill in the art to which this invention belongs lf a definition set forth herein is contrary to or otherwise incon sistent with a definition set forth elsewhere, the definition set forth herein prevails over the definition that is set forth elsewhere. Use of examples in the specification, including examples of terms, is for illustrative purposes only and is not intended to limit the scope and meaning of the embodiments of the invention herein.

The following example further illustrates the invention, without limit ing the invention thereto.

Example

PLA polymer, HP2500 grade, from NatureWorks LLC, and PBS polymer, BioPBS FZ71 from PTTMCC, were used in the manufacture of a polymer blend. Two glass fiber grades were supplied by Nippon Electric glass, chopped strands (SGF) grade was ChopVantage HP3730 (fiber length 4.5 mm, diameter 10 microns) and direct roving (LGF) grade was Tufrow 4588 (diameter 17 microns).

The short glass fiber (SGF) reinforced PLA/PBS composites were com pounded with a 25 mm twin-screw extruder (Coperion ZSK 26 MC ¹⁸ ) and pelletized and dried before injection molding to the test samples. The long glass fiber (LGF) reinforced PLA/PBS composites were manu factured by thermoplastic pultrusion process to LFT pellets (long fiber reinforced pellets, fiber length 8 mm) and dried before injection molding to the test samples.

The test sample was formed to comply with 1SO test bar for testing ten- sile, flexural, impact and HDT properties. Test sample had a size of 10x4x80 mm.

lnjection molding was conducted with Engel 200ton injection molding machine. The mold temperature for testing PLA/PBS composites, unreinforced PLA/PBS blends, and pure PBS and pure PLA was 30°C, except that the mold tem perature of 110°C was used in in-process crystallization of PLA with nucleation agent LAK-301 from Takemoto Oil & Fat.

The used PLA/PBS ratios, glass fiber contents and results are presented in Tables 1 and 2. The reinforced composite material described in the Tables con sisted of a polymer blend and glass fiber whereby the total amount of the blend and the glass fiber added up to 100 wt-% of the composite material. The polymer blend in each composite material consisted of PLA and PBS in amounts given in the Ta bles, adding up to 100 wt-% of the polymer blend.

The results of Tables 1 and 2 show that cold molded (at 30°C) PLA ref erence materials have acceptable cycle times, but heat resistance HDT B is only 54°C. When in-process crystallization (i.e. annealing) was used with mold temper- ature of 110°C, HDT B is 122°C and at an acceptable level, but the cycle time of 60 seconds is not. Regardless of mold temperature and cycle time, the impact strength of pure PLA is quite poor. On the other hand, pure PBS has good temperature re sistance and short cycle time but shows poor mechanical properties including im pact strength. PLA/PBS blends without glass fiber reinforcement showed good im- pact resistance, other mechanical properties being well below of pure PLA. Moreo ver, also the temperature resistance is poor (only about 53 to 55°C).

The results further show that the reinforced PLA/PBS blend (50 wt- %/50 wt-%) of the present invention exhibits improved HDT and mechanical prop erties at low mold temperature of 30°C and short cycle time of 20 seconds. The improvement of temperature resistance started to increase from 5 wt-% short glass fiber (SGF) addition. However, the improvement was low (HDT 63°C). When the glass fiber (SGF) reinforcement level rose to 10 wt-%, heat resistance HDT B rose to acceptable level and comparable to oil-based plastics like ABS (HDT B about 88°C). The mechanical properties other than impact strength were lower than those of pure PLA but comparable with ABS. The impact strength was improved against pure PLA by 104% and temperature resistance HDT B by 77%. When using glass fiber reinforcement more than 20 wt-%, all the properties were improved re markably as shown in Table 3.

Long glass fiber reinforced PLA/PBS blend of the invention shows even better improvement in mechanical properties and temperature resistance com- pared with pure PLA (Table 3.) at a mold temperature of 30°C and short cycle time of 20 seconds. As shown in table 2 the properties (flexural and tensile strength and HDT) started to decline when PLA/PBS ratio out of range of present invention.

Table 1

* PLA + 1 wt-% nucleating agent (LAK-301 from Takemoto Oil & Fat)

Table 2

* PLA + 1 wt-% nucleating agent (LAK-301 from Takemoto Oil & Fat)

Table 3. Improvement of composites of the invention against neat amorphous PLA