Granules for granule dishwasher

Abstract

The invention relates to granule for a granule dishwasher, wherein the granule comprises a polymer composition comprising (A) a polyhydroxyalkanoate, (B) an inorganic filler and (C) a lubricant, wherein the amount of (B) the inorganic filler with respect to the total weight of the polymer composition is at least 15 wt.%.

Description

[0001] The present invention relates to granules for a granule dishwasher. The present invention further relates to use of such granules for a granule dishwasher and process for making such granules.

[0002] Granule dishwashers utilize granules for cleaning of tableware and kitchen utensils such as dishes, pots and pans, trays and cutleries. Granules are introduced to the dishwasher together with water and blasted onto dirty items in the granule dishwashers to mechanically remove food residues.

[0003] Use of biodegradable materials for such granules is known. Biodegradable granules are advantageous for reducing the energy associated with handling waste.

[0004] SE501640C2 discloses particulate blasting agents of composite materials adapted for use in particular washing and dishwashers. The blast agents comprise polyhydroxybutyrate and / or saccharides.

[0005] SE1950489A1 discloses biodegradable granules for a granule dishwasher comprising a mixture of a biodegradable polymer and a mineral filler, characterized in that the biodegradable polymer is 3-Hydroxybutyrate 3-Hydroxyhexanoate in an amount of 55-85% by weight. SE1950489A1 describes clogging problem of the fluid distributing system of the dishwasher. While the dishwasher machine is used, the plastic granules are exposed to wear and small pieces wear off. The small pieces tend to clog the fluid distributing system of the dishwasher.

[0006] It is an objective of the present invention to provide biodegradable granules for a granule dishwasher which allow smooth operation of the dishwasher.

[0007] Accordingly, the present invention provides a granule for a granule dishwasher, wherein the granule comprises a polymer composition comprising (A) a polyhydroxyalkanoate, (B) an inorganic filler and (C) a lubricant, wherein the amount of the inorganic filler (B) with respect to the total weight of the polymer composition is at least 15 wt.%.

[0008] It was observed according to the invention that clogging can occur when granules are ejected through the ejection nozzle of a granule dishwasher. This problem prevents a smooth operation of the dishwasher and can occur even without breaking down of the granules. According to the invention, it was surprisingly found that the clogging problem in the ejection nozzle is reduced by the use of a lubricant in the composition of the granules. Although not wishing to be bound by any theory, the presence of the lubricant in the composition is believed to positively influence the surface properties of the granules made from the composition to reduce the clogging problem.(A) polyhydroxyalkanoate

[0009] The granule according to the invention comprises polyhydroxyalkanoate (A) (herein sometimes referred as PHA). PHA is marine degradable and thus its use in the granule leads to an advantage of reducing waste and solving problems associated with microplastics in ocean. The polyhydroxyalkanoate (A) used in the present invention is selected from microorganism-derived polyhydroxyalkanoates produced by microorganisms. One type of such PHA may be present in the composition or two or more types of such PHAs may be may be present in the composition.

[0010] In the present invention, the PHA (A) is aliphatic polyester resin including a repeating unit represented by a general formula: [-CHR-CH 2 -CO-O-] (where R is an alkyl group represented by C n H 2n+1 and n is an integer of 1 or more and 15 or less).

[0011] The microorganisms that produce the microorganism-derived PHA (A) are not particularly limited as long as they have the ability to produce PHAs. For example, Bacillus megaterium is a poly(3-hydroxybutyrate) (hereinafter, may be abbreviated as "PHB")-producing microorganism first discovered in 1925, and natural microorganisms such as Cupriavidus necator (formerly classified as Alcaligenes eutrophus, Ralstonia eutropha) and Alcaligenes latus are known as other PHB-producing microorganisms. These microorganisms accumulate PHB in their cells.

[0012] Further, known microorganisms that produce copolymers of hydroxybutyrate and another hydroxyalkanoate are, for example, Aeromonas caviae that produces poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (hereinafter, may be abbreviated as "PHBV") and poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (hereinafter, may be abbreviated as "PHBH") and Alcaligenes eutrophus that produces poly(3-hydroxybutyrate-co-4-hydroxybutyrate). Particularly, a preferred PHBH-producing microorganism is, for example, Alcaligenes eutrophus AC32, FERM BP-6038 (T. Fukui, Y. Doi, J. Bateriol., 179, p. 4821-4830 (1997)) produced by introducing a PHA synthase gene to improve PHBH productivity. These microorganisms are cultured under appropriate conditions, and the thus obtained cells having PHBH accumulated therein are used. Other than the above microorganisms, genetically-modified microorganisms may also be used which are produced by introducing various PHA synthesis-related genes depending on the desired type of PHA (A) to be produced. In this case, culture conditions including the type of a substrate may be optimized.

[0013] The molecular weight of the microorganism-derived PHA used in the present invention is not particularly limited as long as the microorganism-derived PHA virtually sufficiently exhibits its mechanical properties for the intended use. If the molecular weight is too low, the granule made using such PHA has low strength. On the other hand, if the molecular weight is too high, processability is reduced and therefore forming into granule becomes difficult. In consideration of such facts, the weight-average molecular weight of the microorganism-derived PHA (A) used in the present invention is preferably in the range of 50,000 to 3,000,000, more preferably in the range of 100,000 to 1,500,000.

[0014] The weight-average molecular weight can be determined as a molecular weight in terms of polystyrene by gel permeation chromatography (GPC) ("Shodex GPC-101" manufactured by Showa Denko K.K.) using a polystyrene gel column ("Shodex K-804" manufactured by Showa Denko K.K.) and chloroform as a mobile phase. In this case, a calibration curve is prepared using polystyrenes having weight-average molecular weights of 31,400, 197,000, 668,000, and 1,920,000. In the GPC, a column appropriate for measuring the above-mentioned molecular weight may be used.

[0015] Examples of the microorganism-derived PHA (A) used in the present invention include: PHB (poly(3-hydroxybutyrate), poly(3-hydroxybutyric acid)); PHBH (poly(3-hydroxybutyrate-co-3-hydroxyhexanoate), poly(3-hydroxybutyric acid-co-3-hydroxyhexanoic acid)); PHBV (poly(3-hydroxybutyrate-co-3-hydroxyvalerate), poly(3-hydroxybutyric acid-co-3-hydroxyvaleric acid)); P3HB3HV3HH (poly(3-hydroxybutyrate-co-3-hydroxyvalerate-co-3-hydroxyhexanoate), poly(3-hydroxybutyric acid-co-3-hydroxyvaleric acid-co-3-hydroxyhexanoic acid)); P3HB4HB (poly(3-hydroxybutyrate-co-4-hydroxybutyrate), poly(3-hydroxybutyric acid-co-4-hydroxybutyric acid)); poly(3-hydroxybutyrate-co-3-hydroxyoctanoate); poly(3-hydroxybutyrate-co-3-hydroxyoctadecanoate). Among these, PHB, PHBH, PHBV, P3HB3HV3HH, P3HB4HB are preferable since they are industrially easily produced.

[0016] Preferably, the amount of repeating units derived from 3-hydroxybutyrate (3HB) in the PHA (A) is 80 mol% to 99 mol%, more preferably 85 mol% to 97 mol%, from the viewpoint of balance between flexibility and strength. If the amount of repeating units derived from 3-hydroxybutyrate (3HB) is less than 80 mol%, stiffness tends to be poor, and if the amount of repeating units derived from 3-hydroxybutyrate (3HB) is more than 99 mol%, the granule may become too brittle.

[0017] The amounts of different types of repeating units in a PHA (A) copolymer resin can be measured by gas chromatography in the following manner. Two milliliters of a sulfuric acid / methanol mixed solution (15 / 85 (weight ratio)) and 2 mL of chloroform are added to about 20 mg of dried PHA, and the mixture is hermetically sealed and heated at 100°C for 140 minutes to obtain a methyl ester as a PHA degradation product. After cooling, the methyl ester is neutralized by adding 1.5 g of sodium hydrogen carbonate little by little, and the mixture is allowed to stand until the generation of carbon dioxide is stopped. Four milliliters of diisopropyl ether is added to and well mixed with the mixture, and then the monomer unit composition of the PHA degradation product in the supernatant is analyzed by capillary gas chromatography. In this way, the amounts of different types of repeating units in the copolymer resin is determined.

[0018] A gas chromatograph and a capillary column used in the capillary gas chromatography are "GC-17A" manufactured by SHIMADZU CORPORATION and "NEUTRA BOND-1" manufactured by GL Sciences Inc. (column length: 25 m, column inner diameter: 0.25 mm, liquid membrane thickness: 0.4 µm), respectively. A carrier gas used is He, the pressure at column inlet is 100 kPa, and the amount of a sample injected is 1 µL. The capillary gas chromatography is performed under conditions where the temperature is increased from an initial temperature of 100°C to 200°C at a rate of 8°C / min and further increased from 200°C to 290°C at a rate of 30°C / min.

[0019] Preferably, the amount of the polyhydroxyalkanoate (A) with respect to the total weight of the polymer composition is at least 20 wt.% and less than 85 wt.%, preferably 30 to 83 wt.%, more preferably 40 to 80 wt.%, more preferably 50 to 77 wt.%, more preferably 55 to 75 wt.%, more preferably 60 to 70 wt.%.

[0020] The polymer composition may optionally comprise further polymers other than the polyhydroxyalkanoate (A), for example polyoxymethylene (POM). Other types of polymers that have been approved for use in connection with food may also be used. Further polymers that can be present in the polymer composition include known biodegradable polymers such as polylactic acid (PLA), polybutylene succinate, polybutylene succinate adipate (PBSA) and polybutylene adipate terephthalate (PBAT). Preferably, the total amount of the polyhydroxyalkanoate (A) and POM, PLA, PBSA and PBAT combined with respect to the polymer composition is at least 20 wt.% and less than 85 wt.%, preferably 30 to 83 wt.%, more preferably 40 to 80 wt.%, more preferably 50 to 77 wt.%, more preferably 55 to 75 wt.%, more preferably 60 to 70 wt.%.

[0021] Preferably, the total amount of the polyhydroxyalkanoate (A), POM, PLA, PBSA and PBAT combined with respect to the total weight of polymers in the polymer composition is at least 50 wt.%, at least 60 wt.%, at least 70 wt.%, at least 80 wt.%, at least 90 wt.%, at least 95 wt.%, at least 99 wt.% or 100 wt.%.

[0022] The polyhydroxyalkanoate (A) is preferably the main polymer in the polymer composition. Preferably, the amount of the polyhydroxyalkanoate (A) with respect to the total weight of polymers in the polymer composition is at least 50 wt.%, at least 60 wt.%, at least 70 wt.%, at least 80 wt.%, at least 90 wt.%, at least 95 wt.%, at least 99 wt.% or 100 wt.%.

[0023] In preferred embodiments, the total amount of the polyhydroxyalkanoate (A) and POM, PLA, PBSA and PBAT combined with respect to the polymer composition is at least 50 wt% and the amount of the polyhydroxyalkanoate (A) with respect to the total weight of polymers in the polymer composition is at least 50 wt.%.(B) inorganic filler

[0024] The presence of the inorganic filler (B) in the composition of the invention leads to a higher density of the granule and thus increases the blasting effect of the granule. The amount of the inorganic filler (B) with respect to the total weight of the polymer composition is at least 15 wt.%, preferably 15 to 49 wt.%, more preferably 20 to 45 wt.%, more preferably 25 to 43 wt.%, more preferably 30 to 40 wt.%, with respect to the total weight of the polymer composition.

[0025] Preferably, the total amount of the polyhydroxyalkanoate (A) and the inorganic filler (B) combined with respect to the total weight of the polymer composition is at least 50 wt.%, at least 60 wt.%, at least 70 wt.%, at least 80 wt.%, at least 90 wt.%, at least 95 wt.%, preferably at least 97 wt.%, more preferably at least 98 wt.%.

[0026] One type of inorganic filler may be present in the composition, or two or more types of inorganic fillers present in the composition. When a combination of different types of inorganic fillers is used, the ratio can suitably be selected depending on the type of the polyhydroxyalkanoate and a target effect, in particular blasting effect.

[0027] Preferably, the inorganic filler used in the present invention has a moisture amount of 0.01 to 10 wt.%, more preferably 0.01 to 5 wt.%, more preferably 0.01 to 1 wt.%. If the amount of moisture in the inorganic filler is less than 0.01 wt.%, a utility cost for reducing the moisture from the inorganic filler may become too high. If the amount of moisture of the inorganic filler exceeds 10 wt.%, the molecular weight tends to decrease by promotion of hydrolysis of the polyhydroxyalkanoate (A). The amount of moisture may be measured according to JIS-K5101.

[0028] Preferably, the inorganic filler used in the present invention has an average particle diameter of 0.1 to 100 µm, preferably 0.1 to 50 µm. If the average particle diameter is less than 0.1 µm, the handleability tends to deteriorate. If the average particle diameter exceeds 100 µm, the impact resistance of the granule tends to decrease. The average particle diameter may be measured using a laser diffraction / scattering device such as "Microtrac MT3100II" produced by Nikkiso Co., Ltd..

[0029] Preferably, the inorganic filler is selected from the group consisting of silicate, carbonate, sulfate, phosphate, oxide, hydroxide, nitride and carbon black and combinations thereof. These are high in versatility, high in the effect of improving the mechanical strength, and small in particle diameter distribution and has a low tendency to inhibit the surface smoothness of the granule.

[0030] Examples of silicate include: clay minerals such as talc, mica, kaolinite, and sericite; pyrophyllite; wollastonite; calcium silicate; magnesium silicate; and sodium silicate.

[0031] Examples of carbonate include: calcium carbonate; magnesium basic carbonate; sodium carbonate; barium carbonate; zinc carbonate; and ferric carbonate.

[0032] Examples of sulfate include: barium sulfate; calcium sulfate; and strontium sulphate.

[0033] Examples of phosphate include: calcium phosphate; zirconium phosphate; and aluminum phosphate.

[0034] Examples of oxide include: silicon dioxide; titanium oxide; aluminum oxide; zinc oxide; magnesium oxide; calcium oxide; zirconium oxide; antimony oxide; and iron oxide.

[0035] Examples of hydroxide include aluminum hydroxide and magnesium hydroxide.

[0036] Examples of nitride include boron nitride, silicon nitride, and aluminum nitride.

[0037] Preferably, the inorganic filler is selected from the group consisting of talc, mica, kaolinite, calcium carbonate, barium sulfate, titanium oxide, boron nitride, and carbon black and combinations thereof from the viewpoint of the availability and the effects.

[0038] Examples of talc used as the inorganic filler include general-purpose talc and surface treatment talc. Specific examples of talc include: "Micro Ace" (trademark) produced by Nippon Talc Co., Ltd.; "Talcum Powder" (trademark) produced by Hayashi-Kasei Co., Ltd.; talc produced by Takehara Kagaku Kogyo Co., Ltd.; and talc produced by Maruo Calcium Co., Ltd.

[0039] Examples of mica used as the inorganic filler include wet-pulverized mica and dry-pulverized mica. Specific examples of mica include mica produced by Yamaguchi Mica Co., Ltd. and mica produced by Keiwa Rozai Co., Ltd.

[0040] Examples of kaolinite used as the inorganic filler include dry kaolin, calcined kaolin, and wet kaolin. Specific examples of kaolinite include "TRANSLINK" (trademark), "ASP" (trademark), "SANTINTONE" (trademark), and "ULTREX" (trademark) produced by Hayashi-Kasei Co., Ltd. and kaolinite produced by Keiwa Rozai Co., Ltd.

[0041] Examples of calcium carbonate used as the inorganic filler include heavy calcium carbonate and soft calcium carbonate. Specific examples of calcium carbonate include "Sunlight" (trademark) and "White Seal" (trademark) produced by Takehara Kagaku Kogyo Co., Ltd., calcium carbonate produced by Maruo Calcium Co., Ltd., and calcium carbonate produced by Shiraishi Calcium Kaisha, Ltd.

[0042] Examples of barium sulfate used as the inorganic filler include precipitated barium sulfate and pulverized barium sulfate. Specific examples of barium sulfate include barium sulfate produced by Takehara Kagaku Kogyo Co., Ltd. and barium sulfate produced by Sakai Chemical Industry Co., Ltd.

[0043] Examples of titanium oxide used as the inorganic filler include rutile type titanium oxide and anatase type titanium oxide. Specific examples of titanium oxide include titanium oxide produced by Ishihara Sangyo Kaisha, Ltd, titanium oxide produced by Sakai Chemical Industry Co., Ltd., and titanium oxide produced by Fuji Titanium Industry Co., Ltd.

[0044] Examples of boron nitride used as the inorganic filler include hexagonal boron nitride and cubic boron nitride. Specific examples of boron nitride include "SHOBN" (trademark) produced by Showa Denko K.K., boron nitride produced by Denki Kagaku Kogyo Kabushiki Kaisha, boron nitride produced by ESK Ceramics, and boron nitride produced by MOMENTIVE.

[0045] Examples of carbon black used as the inorganic filler include furnace black, channel black, acetylene black, and thermal black. Specific examples of carbon black include carbon blacks produced by Asahi Carbon Co., Ltd., Mitsubishi Carbon Black Co., Ltd., Tokai Carbon Co., Ltd., Shinnikka Carbon Co., Ltd., and Cabot Japan K.K.

[0046] Particularly preferably, the inorganic filler is barium sulfate in view of the large blasting effect due to the high density of barium sulfate.(C) lubricant

[0047] The composition according to the invention comprises (C) a lubricant.

[0048] Lubricant is an additive for increasing the fluidity of the resin to improve the polymer compounding process. Lubricants can be divided into external lubricants and internal lubricants. Those lubricants that are used to enable the polymer melt to smoothly leave the hot metal surface of the processing machine are generally called external lubricants, and those lubricants that are used to improve the slippage between the polymer molecules are generally called internal lubricants. Depending on the type of the polymer to which the lubricant is added, the lubricant acts as an external lubricant or an internal lubricant. For polyhydroxyalkanoate, erucamide acts as an external lubricant and behenamide acts as an internal lubricant.

[0049] Preferably, the amount of the lubricant (C) is 0.01 to 5 parts by weight, more preferably from 0.05 to 3 parts by weight, and even more preferably from 0.1 to 1.5 parts by weight, per 100 parts by weight of the polyhydroxyalkanoate (A). One type of lubricant may be present in the composition, or two or more lubricants may be present in the composition.

[0050] The lubricant used according to the invention may be an internal lubricant, an external lubricant or a combination of an internal lubricant and an external lubricant, preferably an external lubricant or a combination of an internal lubricant and an external lubricant, more preferably a combination of an internal lubricant and an external lubricant.

[0051] Suitable examples of the lubricant include behenamide, oleamide, erucamide, stearamide, palmitamide, N-stearyl behenamide, N-stearyl erucamide, ethylenebisstearamide, ethylenebisoleamide, ethylenebiserucamide, ethylenebislauramide, ethylenebiscapramide, p-phenylenebisstearamide, and a polycondensation product of ethylenediamine, stearic acid, and sebacic acid, and combinations thereof. Preferably, the lubricant is erucamide and / or behenamide.External lubricant

[0052] Herein, "external lubricant" may mean a lubricant which is considered to have a mold releasing ability according to the method described below and which has a solidification time of at least 160 seconds according to the method described below. Herein, "internal lubricant" may mean a lubricant which is not determined as an external lubricant according to these methods. An example of an external lubricant is erucamide.Internal lubricant

[0053] An example of an internal lubricant is behenamide.Mold releasing ability

[0054] 1 wt part of a sample material is mixed with 100 wt part of PHBH (manufactured by Kaneka Corporation) [poly (3-hydroxybutyrate-co-3-hydroxyhexanoate) having a weight average molecular weight of 380,000 in terms of standard polystyrene measured by GPC; having 94.2 mol% of 3-hydroxybutyrate and 5.8 mol% of 3-hydroxyhexanoate] to obtain a powder premix.

[0055] A 60 cc chamber is attached to a laboratory plast mill manufactured by Toyo Seiki Co., Ltd. The chamber temperature is set to 150 °C. The powder premix is fed to the chamber and kneaded at a rotor rotation speed of 50 rpm for 3 minutes. After 3 minutes, the chamber is immediately disassembled. When the melt comes off from the rotor without sticking, the sample is considered to have a mold releasing ability.Solidification time

[0056] 1 wt part of a sample is mixed with 100 wt part of PHBH (manufactured by Kaneka Corporation) [poly (3-hydroxybutyrate-co-3-hydroxyhexanoate) having a weight average molecular weight of 380,000 in terms of standard polystyrene measured by GPC; having 94.2 mol% of 3-hydroxybutyrate and 5.8 mol% of 3-hydroxyhexanoate] to obtain a powder premix.

[0057] A small kneader Xprole 5 manufactured by Xprole Instruments is provided. The barrel temperature is set to 180 °C. The powder premix is fed to the barrel and kneaded by Co-rotation at a screw rotation of 100 rpm. A strand of the kneaded mixture is discharged from a die and immersed in a water bath having a temperature of 55 °C. the strand is poked by a metal rod having a flat tip every 5 seconds to determine whether the surface of the strand deforms. The time point from immersing in the water bath until the time point at which the surface of the strand stops deforming is defined as the solidification time.

[0058] Preferably, the total amount of the polyhydroxyalkanoate (A) the inorganic filler (B) and the lubricant (C) with respect to the total weight of the polymer composition is at least 50 wt.%, at least 60 wt.%, at least 70 wt.%, at least 80 wt.%, at least 90 wt.%, at least 95 wt.%, preferably at least 97 wt.%, more preferably at least 98 wt.%, for example at least 99 wt.%, at least 99.5 wt.%, at least 99.8 wt.%, at least 99.9 wt.% or 100 wt.%.(D) nucleating agent

[0059] The composition of the present invention may further comprise (D) a nucleating agent. A nucleating agent can increase the solidification rate of the polyhydroxyalkanoate and improve the granule formation process.

[0060] Preferably, the amount of the nucleating agent (D) is 0.05 to 20 parts by weight, more preferably 0.1 to 10 parts by weight, even more preferably 0.3 to 5 parts by weight, per 100 parts by weight of the polyhydroxyalkanoate (A). If the amount of the nucleating agent (D) is too small, the effect of the nucleating agent (D) cannot be obtained, and if the amount of the nucleating agent (D) is too large, viscosity during melt-processing may be reduced and prevent easy processing.

[0061] Preferably, the nucleating agent in the present invention has a solidification time of at most 50 seconds measured by the method as described in the description of the lubricant.

[0062] Preferably, the nucleating agent is selected from the group consisting of pentaerythritol, orotic acid, aspartame, cyanuric acid, glycine, zinc phenylphosphonate and boron nitride and combinations thereof.

[0063] Particularly preferably, the nucleating agent is or comprises pentaerythritol. Pentaerythritol has an excellent effect of accelerating the solidification rate.

[0064] One type of nucleating agent may be used, or two or more types of nucleating agents may be used in combination. When a combination of different types of nucleating agents is used, the ratio can suitably be selected depending e.g. on the type of the polyhydroxyalkanoate and the target effect.

[0065] In some embodiments, the composition of the present invention does not comprise a nucleating agent or comprises a nucleating agent in an amount of less than 0.05 parts by weight with respect to 100 parts by weight of the polyhydroxyalkanoate (A).

[0066] In some embodiments, the composition of the present invention does not comprise pentaerythritol or comprises pentaerythritol in an amount of less than 0.05 parts by weight with respect to 100 parts by weight of the polyhydroxyalkanoate (A).

[0067] Pentaerythritol is a polyhydric alcohol represented by Formula below and has a melting point of 260.5°C.

[0068] Pentaerythritol is classified as a sugar alcohol. It not derived from a natural product but can be synthesized by condensation of acetaldehyde and formaldehyde under basic conditions.

[0069] Pentaerythritol is commonly available as a reagent or an industrial product. Examples of the reagent include, but are not limited to, those manufactured by Wako Pure Chemical Industries, Ltd., Sigma-Aldrich, Tokyo Chemical Industries Co., Ltd., and Merck. Examples of the industrial product include, but are not limited to, those manufactured by Mitsubishi Chemical Corporation (trade name: Neulizer P), those manufactured by manufactured by Perstorp (trade name: Holtac M) and those manufactured by TOYO CHEMICALS CO., LTD.

[0070] Some commercially-available reagents and products contain, as impurities, oligomers generated by dehydration condensation of pentaerythritol, such as dipentaerythritol and tripentaerythritol. These oligomers are do not have substantial effect on the crystallization effect and therefore the pentaerythritol used in the present invention may contain such oligomers.

[0071] Preferably, the total amount of the polyhydroxyalkanoate (A), the inorganic filler (B), the lubricant (C) and the nucleating agent (D) with respect to the total weight of the polymer composition is at least 50 wt.%, at least 60 wt.%, at least 70 wt.%, at least 80 wt.%, at least 90 wt.%, at least 95 wt.%, preferably at least 97 wt.%, more preferably at least 98 wt.%, for example at least 99 wt.%, at least 99.5 wt.%, at least 99.8 wt.%, at least 99.9 wt.% or 100 wt.%.(E) Further additives

[0072] The composition according to the present invention may further comprise additives such as plasticizer; antioxidant; ultraviolet absorber; colorant such as dye or pigment; and / or antistatic agent.

[0073] Preferably, the total amount of the polyhydroxyalkanoate (A), the inorganic filler (B), the lubricant (C), the nucleating agent (D) and the further additives (E) with respect to the total weight of the polymer composition is 100 wt.%.

[0074] Examples of the plasticizer include glycerin ester compounds, citric ester compounds, sebacic ester compounds, adipic ester compounds, polyether ester compounds, benzoic ester compounds, phthalic ester compounds, isosorbide ester compounds, polycaprolactone compounds, and dibasic ester compounds. Among these, glycerin ester compounds, citric ester compounds, sebacic ester compounds, and dibasic ester compounds are preferred because they are particularly superior in the plasticizing effect on the poly(3-hydroxyalkanoate) resin component. Examples of the glycerin ester compounds include glycerin diacetomonolaurate. Examples of the citric ester compounds include tributyl acetyl citrate. Examples of the sebacic ester compounds include dibutyl sebacate. Examples of the dibasic ester compounds include benzyl methyl diethylene glycol adipate.Granule properties

[0075] Preferably, the amount of the polymer composition in the granule is at least 95 wt.%, preferably at least 97 wt.%, more preferably at least 98 wt.%, more preferably at least 99 wt.% or the granule consists of the polymer composition.

[0076] Preferably, the composition has a density of 1.30 to 1.65 g / cm 3< , preferably 1.32 to 1.60 1.65 g / cm 3< , more preferably 1.35 to 1.55 g / cm 3< . Such density range gives suitable blasting effect. The density is herein meant apparent density.

[0077] Preferably, the granule has a spherical shape or a cylindrical shape in particular a circular cylindrical shape. A spherical shape herein includes a sphere and shapes defined by curves. A cylindrical shape is bounded by a cylindrical surface and two parallel planes. The cylindrical surface may be straight between the parallel planes or may have a waist, preferably straight. A spherical shape of the granule is particularly advantageous for reducing the clogging problem.

[0078] Preferably, the granule has a size of 2.0 to 5.0 mm, preferably 2.8 to 4.5 mm, more preferably 3.0 to 4.0 mm, more preferably 3.2 to 3.8 mm, wherein the size of the granule is defined as the largest dimension of the granule. For a circular granule, the size of the granule is the diameter. For a cylindrical granule, the size of the granule is the diameter of the base or the height of the column. The cylindrical granule may have an aspect ratio between the diameter of the base and the height of the column of e.g. 0.7 to 1.3.

[0079] The invention further provides use of the granule according to the invention for cleaning tableware and kitchen utensils such as dishes, pots and pans, trays and cutleries in a granule dishwasher.

[0080] The invention further provides use of a lubricant in a granule for a granule dishwasher for reducing clogging of the granule in an ejection nozzle of a granule dishwasher, wherein the granule comprises a polymer composition comprising (A) a polyhydroxyalkanoate, (B) an inorganic filler and (C) the lubricant, wherein the amount of the inorganic filler (B) with respect to the total weight of the polymer composition is at least 15 wt.%.

[0081] The invention further provides a process for making the granule according to the invention, comprising i) melt mixing (A), (B) and (C) and optionally (D) and / or (E) to obtain a melt mixture ii) extruding the melt mixture for solidification in air or water and iii) cutting the solidified product obtained by step ii) to obtain the granule.

[0082] Steps ii) and iii) may involve extruding the melt mixture into air to form strands, cooling the strands and cutting the strands into the granules according to the invention, also known as the strand cut method. This method can result in cylindrical granules. Alternatively, step ii) may involve extruding the melt mixture into water to solidify and cutting the solidified product to form the granules according to the invention, also known as the underwater cut method. This method results can result in spherical granules. It will be appreciated that melt mixing herein means that (A) is in a molten state during mixing and not all components are not melted, such as (B). Preferably, the granules according to the invention is obtained directly after the cutting step, e.g. no coating step takes place after the cutting step.

[0083] It is noted that the invention relates to the subject-matter defined in the independent claims alone or in combination with any possible combinations of features described herein, preferred in particular are those combinations of features that are present in the claims. It will therefore be appreciated that all combinations of features relating to the composition according to the invention; all combinations of features relating to the process according to the invention and all combinations of features relating to the composition according to the invention and features relating to the process according to the invention are described herein.

[0084] It is further noted that the term 'comprising' does not exclude the presence of other elements. However, it is also to be understood that a description on a product / composition comprising certain components also discloses a product / composition consisting of these components. The product / composition consisting of these components may be advantageous in that it offers a simpler, more economical process for the preparation of the product / composition. Similarly, it is also to be understood that a description on a process comprising certain steps also discloses a process consisting of these steps. The process consisting of these steps may be advantageous in that it offers a simpler, more economical process.

[0085] When values are mentioned for a lower limit and an upper limit for a parameter, ranges made by the combinations of the values of the lower limit and the values of the upper limit are also understood to be disclosed.

[0086] The invention is now elucidated by way of the following examples, without however being limited thereto.

[0087] Components as shown in Table 1 were fed to a co-rotating intermeshing twin screw extruder (Maag: ZE28 Blue Power) and melt mixed at a temperature of 150°C and a screw rotation speed of 90 rpm, extruded into a strand, cooled in air and cut into granules having a cylindrical shape having an average diameter of 3 mm and an average length of 3.3 mm.

[0088] A-1: Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (P3HB3HH) comprising 5.4 mol% of 3HH and a weight average molecular weight of 620,000 as measured by GPC, obtained according to the method described in WO2008 / 010296.

[0089] B-1: barium sulfate, Microspreme 20 from RBH C-1: behenamide, CRODAMIDE BR from CRODA C-2: erucamide, CRODAMIDE ER from CRODA D-1: pentaerythritol, Holtac M from Perstorp

[0090] The clogging property was determined by the following method: A SUS304 conical funnel (cone inlet inner diameter φ197mm, total length 235mm, cylindrical section length 100mm, cylindrical section inner diameter 19mm) was fixed horizontally. 150g of granules were introduced to the funnel with the bottom of the cylindrical section blocked. The blocked bottom was released and it was observed whether the granules would flow and fall out from the bottom of the cylindrical section of the funnel.

[0091] In some cases, all granules fell through the bottom of the cylindrical section of the funnel. In other cases, the flow of the granules stopped (clogging). When the flow of the granules stopped, the funnel was tapped to restart the flowing of the granules. The number of times required for all granules to fall through the bottom of the funnel was recorded. Evaluation was performed five times for each formulation. Table 1 (amounts of components in weight part)Ex 1Ex 2Ex 3CEx 4A-165656565B-135353535C-10.3250.325C-20.3250.325D-10.650.650.650.65number of tapping0000001100200100000> 10

[0092] It can be understood that heavy clogging problem occurred in the granules of CEx 4 made without any lubricant. This clogging problem was substantially eliminated by the use of behenamide (Ex 2) or erucamide (Ex 3), and completely eliminated by the use of both behenamide and erucamide (Ex 1).

Claims

1. A granule for a granule dishwasher, wherein the granule comprises a polymer composition comprising (A) a polyhydroxyalkanoate, (B) an inorganic filler and (C) a lubricant, wherein the amount of (B) the inorganic filler with respect to the total weight of the polymer composition is at least 15 wt.%.

2. The granule according to claim 1, wherein the amount of the polyhydroxyalkanoate (A) with respect to the total weight of the polymer composition is at least 20 wt.% and less than 85 wt.%, preferably 30 to 83 wt.%, more preferably 40 to 80 wt.%, more preferably 50 to 77 wt.%, more preferably 55 to 75 wt.%, more preferably 60 to 70 wt.%.

3. The granule according to any one of the preceding claims, wherein the amount of the inorganic filler (B) with respect to the total weight of the polymer composition is 15 to 49 wt.%, preferably 20 to 45 wt.%, more preferably 25 to 43 wt.%, more preferably 30 to 40 wt.%.

4. The granule according to any one of the preceding claims, wherein the total amount of the polyhydroxyalkanoate (A) and the inorganic filler (B) combined with respect to the total weight of the polymer composition is at least 50 wt.%, at least 60 wt.%, at least 70 wt.%, at least 80 wt.%, at least 90 wt.%, at least 95 wt.%, preferably at least 97 wt.%, more preferably at least 98 wt.%.

5. The granule according to any one of the preceding claims, wherein the inorganic filler (B) is selected from the group consisting of silicates, carbonates, sulfates, phosphates, oxides, hydroxides, nitrides and carbon black and combinations thereof, preferably wherein the inorganic filler (B) is selected from the group consisting of talc, mica, kaolinite, calcium carbonate, barium sulfate, titanium oxide, boron nitride, and carbon black and combinations thereof, preferably the inorganic filler is or comprises barium sulfate.

6. The granule according to any one of the preceding claims, wherein the amount of the lubricant (C) is 0.01 to 5 parts by weight, more preferably from 0.05 to 3 parts by weight, more preferably from 0.1 to 1.5 parts by weight, per 100 parts by weight of the polyhydroxyalkanoate (A).

7. The granule according to any one of the preceding claims, wherein the lubricant (C) comprises an external lubricant, an internal lubricant or a combination of an external lubricant and an internal lubricant, preferably the lubricant comprises an external lubricant or a combination of an external lubricant and an internal lubricant, more preferably the lubricant comprises a combination of an external lubricant and an internal lubricant.

8. The granule according to any one of the preceding claims, wherein the lubricant comprises behenamide, oleamide, erucamide, stearamide, palmitamide, N-stearyl behenamide, N-stearyl erucamide, ethylenebisstearamide, ethylenebisoleamide, ethylenebiserucamide, ethylenebislauramide, ethylenebiscapramide, p-phenylenebisstearamide, and a polycondensation product of ethylenediamine, stearic acid, and sebacic acid, and combinations thereof, preferably the lubricant is or comprises erucamide and / or behenamide, preferably the lubricant is or comprises a combination of erucamide and behenamide.

9. The granule according to any one of the preceding claims, wherein the composition further comprise (D) a nucleating agent, preferably wherein the nucleating agent (D) is or comprises pentaerythritol, preferably wherein the amount of the nucleating agent (D) is 0.05 to 20 parts by weight, more preferably 0.1 to 10 parts by weight, even more preferably 0.3 to 5 parts by weight, per 100 parts by weight of the polyhydroxyalkanoate (A).

10. The granule according to any one of the preceding claims, wherein the granule has a density of 1.30 to 1.65 g / cm3, preferably 1.32 to 1.60 g / cm3, more preferably 1.35 to 1.55 g / cm3.

11. The granule according to any one of the preceding claims, wherein the granule has a spherical shape or a cylindrical shape.

12. The granule according to any one of the preceding claims, wherein the granule has a size of 2.0 to 5.0 mm, preferably 2.8 to 4.5 mm, more preferably 3.0 to 4.0 mm, more preferably 3.2 to 3.8 mm.

13. Use of the granule according to any one of the preceding claims for cleaning tableware and kitchen utensils such as dishes, pots and pans, trays and cutleries in a granule dishwasher.

14. A process for making the granule according to any one of the preceding claims, comprising i) melt mixing (A), (B) and (C) and optional components to obtain a melt mixture, ii) extruding the melt mixture for solidification in air or water and iii) cutting the solidified product obtained by step ii) to obtain the granule.

15. Use of a lubricant in a granule for a granule dishwasher for reducing clogging of the granule in an ejection nozzle of a granule dishwasher, wherein the granule comprises a polymer composition comprising (A) a polyhydroxyalkanoate, (B) an inorganic filler and (C) the lubricant, wherein the amount of the inorganic filler (B) with respect to the total weight of the polymer composition is at least 15 wt.%.

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