Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J9/00—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof
  • C08J9/0061—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof characterized by the use of several polymeric components
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J9/00—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof
  • C08J9/16—Making expandable particles
  • C08J9/18—Making expandable particles by impregnating polymer particles with the blowing agent
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J9/00—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof
  • C08J9/22—After-treatment of expandable particles; Forming foamed products
  • C08J9/228—Forming foamed products
  • C08J9/232—Forming foamed products by sintering expandable particles
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2203/00—Foams characterized by the expanding agent
  • C08J2203/06—CO2, N2 or noble gases
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2367/00—Characterised by the use of polyesters obtained by reactions forming a carboxylic ester link in the main chain; Derivatives of such polymers
  • C08J2367/04—Polyesters derived from hydroxy carboxylic acids, e.g. lactones
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2467/00—Characterised by the use of polyesters obtained by reactions forming a carboxylic ester link in the main chain; Derivatives of such polymers
  • C08J2467/04—Polyesters derived from hydroxy carboxylic acids, e.g. lactones
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J9/00—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof
  • C08J9/04—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof using blowing gases generated by a previously added blowing agent
  • C08J9/12—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof using blowing gases generated by a previously added blowing agent by a physical blowing agent
  • C08J9/122—Hydrogen, oxygen, CO2, nitrogen or noble gases

Definitions

• the present invention relates to expanded poly(3-hydroxyalkanoate) resin particles and molded articles thereof.
• Biodegradable plastics are being used in a wide range of applications, including agricultural, forestry and fisheries materials that are used in the environment, as well as food containers, packaging materials, sanitary products, garbage bags, etc. that are difficult to collect and reuse after use. Development is underway. Furthermore, foams made of biodegradable plastics are expected to be used in cushioning materials for packaging, agricultural boxes, fish boxes, automobile parts, building materials, civil engineering materials, and the like.
• poly(3-hydroxyalkanoate) hereinafter also referred to as "P3HA"
• P3HA poly(3-hydroxyalkanoate)
• Patent Document 1 discloses foamed particles obtained using a biodegradable P3HA-based resin and a foamed molded article obtained by in-mold foam molding of the foamed particles.
• an object of one embodiment of the present invention is to provide expanded particles of P3HA-based resin that can provide a foamed molded product of P3HA-based resin that has excellent strength in a cryogenic environment.
• the present inventors have found that in foamed P3HA-based resin particles formed by foaming resin particles containing a P3HA-based resin, the resin particles have two different compositions of constituent units.
• the P3HA-based resin has excellent strength even when used in an extremely low temperature environment. It was discovered that a foamed molded article could be obtained, and the present invention was completed.
• one aspect of the present invention is expanded P3HA-based resin particles formed by foaming resin particles containing a P3HA-based resin, wherein the resin particles contain two or more types of P3HA-based resins having different compositions of constituent units.
• the expanded P3HA resin particles have a glass transition temperature of 2.0° C. or lower.
• the present inventors found that in the production of expanded P3HA-based resin particles obtained by foaming resin particles containing P3HA-based resin, two By using resin particles containing more than 100% of P3HA-based resins and by setting the glass transition temperature of the expanded P3HA-based resin particles to 2.0°C or less, they have excellent strength even when used in extremely low temperature environments. It was discovered for the first time that a foamed molded article of P3HA-based resin can be obtained. Even for those skilled in the art, the improvement in strength in a cryogenic environment cannot be predicted from the structural units of the P3HA-based resin and the glass transition temperature of the expanded P3HA-based resin particles, and can be said to be a surprising effect.
• the expanded P3HA-based resin particles according to one aspect of the present invention can provide a P3HA-based resin foam molded product that has excellent strength in an extremely low-temperature environment, and is therefore extremely useful particularly in applications under an extremely low-temperature environment.
• under a cryogenic environment refers to an environment at ⁇ 20° C. or lower.
• the expanded P3HA-based resin particles according to an embodiment of the present invention are formed by foaming resin particles containing a P3HA-based resin, and the resin particles include two or more types of P3HA-based resins having different compositions of constituent units, and the The glass transition temperature of the expanded P3HA resin particles is 2.0°C or less.
• P3HA-based resin expanded particles are also referred to as “expanded particles.”
• the P3HA-based resin is a polymer having a 3-hydroxyalkanoate unit as an essential constituent unit (monomer unit).
• 3-hydroxyalkanoate is sometimes referred to as "3HA.”
• a polymer containing a repeating unit represented by the following general formula (1) is preferable: [-CHR-CH 2 -CO-O-]...(1).
• R represents an alkyl group represented by CnH2n+1, and n represents an integer of 1 to 15.
• R include linear or branched alkyl groups such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, t-butyl, pentyl, and hexyl.
• n is preferably 1 to 10, more preferably 1 to 8.
• P3HA-based resin P3HA-based resins produced from microorganisms are particularly preferred.
• P3HA-based resin produced from microorganisms is poly[(R)-3HA] in which all 3HA units are (R)-3HA.
• the P3HA-based resin preferably contains 50 mol% or more, more preferably 70 mol% or more of 3HA units (particularly repeating units of general formula (1)) out of 100 mol% of all repeating units of the P3HA-based resin. , more preferably 80 mol% or more.
• the repeating unit (monomer unit) may be only a 3HA unit, or in addition to the 3HA unit, a repeating unit derived from a monomer other than 3HA (for example, a 4-hydroxyalkanoate unit, etc.) may be used. May contain.
• 3HA units include 3-hydroxybutyrate units, 3-hydroxyvalerate units, and 3-hydroxyhexanoate units.
• 3-Hydroxybutyrate has a melting point and tensile strength close to propylene. Therefore, the P3HA-based resin according to one embodiment of the present invention preferably contains 3-hydroxybutyrate units.
• 3-hydroxybutyrate is also referred to as "3HB” below.
• the P3HA-based resin preferably contains 3HB units (monomer units) in an amount of 65 mol% or more, more preferably 70 mol% or more, based on 100 mol% of all repeating units of the P3HA-based resin.
• 3HB monomer units
• a polymer a polymer produced by a microorganism
• all 3HBs are (R)-3HB is particularly preferred.
• the monomer from which repeating units other than the repeating unit with the largest content originates is referred to as a comonomer.
• the "repeating unit derived from a comonomer” is also referred to as a “comonomer unit” below.
• the comonomer is not particularly limited, but 3-hydroxyhexanoate (hereinafter also referred to as 3HH) or 4-hydroxybutyrate (hereinafter also referred to as 4HB) is preferred.
• P3HA-based resins include poly(3-hydroxybutyrate), poly(3-hydroxybutyrate-co-3-hydroxypropionate), poly(3-hydroxybutyrate-co-3- hydroxyvalerate) (hereinafter sometimes referred to as "P3HB3HV”), poly(3-hydroxybutyrate-co-3-hydroxyvalerate-3-hydroxyhexanoate), poly(3-hydroxybutyrate-co-3-hydroxyvalerate-3-hydroxyhexanoate) poly(3-hydroxybutyrate-co-3-hydroxyheptanoate) (hereinafter sometimes referred to as "P3HB3HH”), poly(3-hydroxybutyrate-co-3-hydroxyheptanoate), poly(3-hydroxybutyrate-co-3-hydroxyheptanoate), -3-hydroxyoctanoate), poly(3-hydroxybutyrate-co-3-hydroxynonanoate), poly(3-hydroxybutyrate-co-3-hydroxydecanoate), poly(3-hydroxybutyrate-co
• poly(3-hydroxybutyrate), poly(3-hydroxybutyrate-co-3-hydroxyvalerate), poly(3-hydroxybutyrate-co- -3-hydroxyvalerate-co-3-hydroxyhexanoate), poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) or poly(3-hydroxybutyrate-co-4-hydroxybutyrate) ) is preferred, and poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) is more preferred.
• P3HA-based resins have the same name (compound name)
• the content ratio (monomer ratio) of the constituent units (monomer units and comonomer units) that constitute the P3HA-based resin differs, are considered to be different types of P3HA-based resins. Therefore, among the P3HA-based resins mentioned above, only P3HA-based resins with the same name (compound name) with different monomer ratios may be used as the P3HA-based resin, or P3HA-based resins with different names may be used in combination. Good too.
• the P3HA-based resin has a 3HB unit as an essential structural unit and also has a comonomer unit. That is, the P3HA-based resin is preferably a copolymer having 3HB units and comonomer units.
• the ratio of the 3HB unit to the comonomer unit (3HB unit/comonomer unit) in 100 mol% of the total structural units in the P3HA-based resin is 99.0/1. 0 (mol%/mol%) to 69.0/31.0 (mol%/mol%) is preferable, and 98.5/1.5 (mol%/mol%) to 69.5/30.5 (mol%).
• the ratio of comonomer units to 100 mol% of all constituent units of the P3HA-based resin is 1.0 mol% or more, the temperature range where the P3HA-based resin can be melt-kneaded and the thermal decomposition temperature range are sufficiently separated, It has the advantage that the preferred molding process range is wide. On the other hand, if the ratio of comonomer units to 100 mol% of all constituent units of the P3HA-based resin is 31.0 mol% or less, the P3HA-based resin composition will crystallize quickly during melt-kneading, resulting in high productivity.
• the content ratio of each monomer unit in the P3HA-based resin can be determined by a method known to those skilled in the art, for example, the method described in International Publication No. 2013/147139.
• the melting point of the P3HA-based resin is not particularly limited, but is preferably 110.0°C to 165.0°C, more preferably 120.0°C to 155.0°C, and preferably 130.0°C to 145.0°C. More preferred. If the melting point of the P3HA-based resin is 110.0°C or higher, there is no fear that the heating dimensions of the resulting foamed molded product will change. On the other hand, if the melting point of the P3HA-based resin is 165.0°C or lower, it will not change during the foaming process. There is no risk of hydrolysis occurring.
• the melting point of the P3HA-based resin is measured by differential scanning calorimetry (hereinafter also referred to as "DSC method").
• DSC method differential scanning calorimetry
• the specific operating procedure is as follows: (1) Weigh out 5 mg to 6 mg of P3HA; (2) Increase the temperature of P3HA from 10.0°C to 190.0°C at a heating rate of 10.0°C/min. The temperature is increased to melt P3HA; (3) The temperature of the highest melting peak in the DSC curve of P3HA obtained in the step (2) above can be determined as the melting point of P3HA.
• the weight average molecular weight of the P3HA-based resin is not particularly limited, but is preferably from 200,000 to 2,000,000, more preferably from 250,000 to 1,500,000, and even more preferably from 300,000 to 1,000,000.
• the weight average molecular weight of P3HA is 200,000 or more, there is no fear that the closed cell ratio of the resulting expanded particles will be low.
• the weight average molecular weight is 2 million or less, the load on the machine during melt-kneading of the P3HA composition will be low, resulting in good productivity.
• the weight average molecular weight of P3HA can be measured from the molecular weight distribution in terms of polystyrene using gel permeation chromatography (HPLC GPC system manufactured by Shimadzu Corporation) using a chloroform solution.
• gel permeation chromatography HPLC GPC system manufactured by Shimadzu Corporation
• a column in the gel permeation chromatography a known column suitable for measuring weight average molecular weight may be used.
• the method for producing the P3HA-based resin is not particularly limited, and may be a production method using chemical synthesis or a production method using microorganisms. Among these, a production method using microorganisms is preferred.
• known methods such as those described in International Publication No. 2009/145164 and International Publication No. 2019/142845 can be applied.
• microorganisms produced by microorganisms are not particularly limited as long as they have the ability to produce P3HAs.
• the first P3HB-producing bacterium was Bacillus megaterium, which was discovered in 1925, and other bacteria include Cupriavidus necator (former classification: Alcaligenes eutrophus), Ralstonia eutrophus Hua (Ralstonia eutropha)) , Alcaligenes latus, and other natural microorganisms. It is known that P3HB accumulates within the cells of these microorganisms.
• bacteria producing copolymers of 3HB and other hydroxyalkanoates include Aeromonas caviae, which produces P3HB3HV and P3HB3HH, Alcaligenes eutrophus, which produces P3HB4HB, etc. can be mentioned.
• P3HB3HH, Alcaligenes eutrophus AC32 strain (FERM BP-6038), which has improved the productivity of P3HB3HH by introducing genes of the P3HA synthase group (T. Fukui, Y. Doi, J. Bateriol., 179, p4821-4830 (1997)) and the like are more preferred.
• microbial cells such as Alcaligenes eutrophus strain AC32 are cultured under appropriate conditions to accumulate P3HB3HH inside the cells.
• genetically modified microorganisms into which various genes related to P3HA synthesis have been introduced may be used depending on the type of P3HA desired to be produced.
• various culture conditions including the type of substrate may be optimized depending on the P3HA to be produced.
• the P3HA-based resin particles in the present invention are particles composed of a composition containing P3HA as an essential component (P3HA-based composition), and include two or more types of P3HA-based resins having different compositions of constituent units.
• the compositions of the structural units of the P3HA-based resins are different refers to "a case where the types of structural units constituting the P3HA-based resins are different" and "a case where two or more types of the same type of P3HA-based resins are used. , but the content ratios (monomer ratios) of the structural units are different.”
• the composition usually contains a P3HA-based resin and additives as necessary.
• P3HA-based resin particles are also referred to as "resin particles.”
• resin particles refer to particles that have not yet been foamed before being subjected to a foaming process.
• the content of P3HA-based resin in the resin particles is not particularly limited, but it is preferably 70% by weight or more, based on 100% by weight of the expanded particles, since the obtained expanded particles and foamed molded products have excellent biodegradability. More preferably, the amount is % by weight or more.
• the average content ratio of comonomer units in 100 mol% of all repeating units in the copolymer is 6.5 to 12 It is preferably .0 mol%, more preferably 6.6 to 11.8 mol%, even more preferably 6.7 to 11.6 mol%. If the average content of comonomer units in 100 mol% of all repeating units in the copolymer is 6.5 to 12.0 mol%, it has the advantage of excellent low-temperature strength.
• the resin particles according to the present invention preferably contain P3HB3HH as the P3HA-based resin.
• the resin particles may include P3HB3HH and a P3HA-based resin other than P3HB3HH, and include P3HB3HH (A ) and P3HB3HH (B).
• the copolymer has a copolymer containing 1.0 to 6.0 mol% of comonomer units in 100 mol% of all repeating units. It is preferable to include a polymer (A) and a copolymer (B) in which the content of comonomer units in 100 mol% of all repeating units is 13.0 mol% or more.
• the content ratio of comonomer units in 100 mol% of all repeating units in the copolymer (A) is preferably 1.0 to 6.0 mol%, and 1.2% from the viewpoint of stability of crystal acceleration.
• the content ratio of comonomer units in 100 mol% of all repeating units in the copolymer (B) is preferably 13.0 mol% or more, and 14.0 mol% or more, from the viewpoint of ensuring strength at low temperatures. It is more preferably mol % or more, and even more preferably 15.0 mol % or more.
• the weight of the copolymer (A) contained in the resin particles is preferably 65% or more, and 70% or more based on the total 100% by weight of the copolymer (A) and the copolymer (B). More preferably, it is 75% or more. This configuration has the advantage that the physical properties of the resulting foam molded product can be adjusted.
• the resin particles according to one embodiment of the present invention may contain additives to the extent that the effects of the present invention are not impaired.
• additives include crystal nucleating agents, bubble regulators, lubricants, plasticizers, antistatic agents, flame retardants, conductive agents, heat insulating agents, crosslinking agents, antioxidants, ultraviolet absorbers, colorants, and inorganic fillers. , organic fillers, hydrolysis inhibitors, etc. can be used depending on the purpose.
• the additive particularly biodegradable additives are preferred.
• the "crystal nucleating agent” is also referred to as a "crystallization nucleating agent.”
• the types of additives, the amount of additives, and other usage methods the types and usage methods described in International Publication No. 2021/002092 can be used, as an example.
• crystal nucleating agent examples include pentaerythritol, orotic acid, aspartame, cyanuric acid, glycine, zinc phenylphosphonate, and boron nitride.
• pentaerythritol is preferred because it has a particularly excellent effect of promoting crystallization of P3HA.
• the content of the crystal nucleating agent in the resin particles is not particularly limited, but is preferably 0.1 to 5.0 parts by weight, and preferably 0.5 to 3.0 parts by weight, based on 100 parts by weight of P3HA. is more preferable, and even more preferably 0.7 to 1.5 parts by weight.
• One type of crystal nucleating agent may be used alone, or two or more types may be used in combination. When using a mixture of two or more types of crystal nucleating agents, the mixing ratio may be adjusted as appropriate depending on the purpose.
• bubble control agent examples include talc, silica, calcium silicate, calcium carbonate, aluminum oxide, titanium oxide, diatomaceous earth, clay, baking soda, alumina, barium sulfate, aluminum oxide, bentonite, and the like.
• talc is preferred because it has particularly excellent dispersibility in P3HA.
• the content of the bubble regulator in the resin particles is not particularly limited, but it is preferably 0.01 to 1.0 parts by weight, and preferably 0.03 to 0.5 parts by weight, based on 100 parts by weight of P3HA. is more preferable, and even more preferably 0.05 to 0.3 parts by weight.
• the foam regulator may be used alone or in combination of two or more. When using a mixture of two or more types of bubble control agents, the mixing ratio may be adjusted as appropriate depending on the purpose.
• the lubricant examples include behenic acid amide, oleic acid amide, erucic acid amide, stearic acid amide, palmitic acid amide, N-stearyl behenic acid amide, N-stearyl erucic acid amide, ethylene bisstearic acid amide, and ethylene bis olein.
• examples include acid amide, ethylene biserucic acid amide, ethylene bislauric acid amide, ethylene biscapric acid amide, p-phenylene bis stearic acid amide, and polycondensates of ethylene diamine, stearic acid, and sebacic acid.
• behenic acid amide and/or erucic acid amide are preferred since they have particularly excellent lubricant effects on P3HA.
• the content of the lubricant in the resin particles is not particularly limited, but it is preferably 0.01 to 5.0 parts by weight, more preferably 0.05 to 3.0 parts by weight, based on 100 parts by weight of P3HA.
• the amount is preferably 0.1 to 1.5 parts by weight, and more preferably 0.1 to 1.5 parts by weight.
• One type of lubricant may be used alone, or two or more types may be used in combination. When using a mixture of two or more types of lubricants, the mixing ratio may be adjusted as appropriate depending on the purpose.
• the resin particles according to one embodiment of the present invention may further contain resin components other than P3HA (also referred to as "other resin components").
• resin components include, for example, (a) aliphatic polyesters such as polylactic acid, polybutylene succinate, polybutylene succinate adipate, polybutylene adipate terephthalate, polybutylene succinate terephthalate, and polycaprolactone; or (b) fatty acids. Examples include aromatic polyesters.
• the content of other resin components in the resin particles is not particularly limited, but is preferably 10 to 400 parts by weight, more preferably 50 to 150 parts by weight, based on 100 parts by weight of P3HA.
• One type of other resin components may be used alone, or two or more types may be used in combination.
• the glass transition temperature of the resin particles is 1.0°C or lower, preferably 0.8°C or lower, and more preferably 0.6°C or lower. Since the glass transition temperature of the resin particles is 1.0° C. or less, a foam molded product of P3HA-based resin can be obtained that has excellent strength even when used in an extremely low temperature environment.
• the lower limit of the glass transition temperature of the resin particles is not particularly limited, but is, for example, -8.0°C or higher, preferably -7.5°C or higher, and preferably -7.0°C or higher. More preferably, the temperature is ⁇ 6.5° C. or higher. In particular, when the lower limit of the glass transition temperature of the resin particles is ⁇ 6.5° C. or higher, the shrinkage rate is excellent.
• the melting point (hereinafter sometimes referred to as "Tmp") of the resin particles is not particularly limited, but is preferably 110.0°C to 165.0°C, more preferably 120.0°C to 155.0°C, and 130°C. .0°C to 145.0°C is more preferred.
• Tmp The melting point of the resin particles
• the melting point of the resin particles is 110.0° C. or higher, it is possible to suppress changes in dimensions due to heating during molding of the resulting expanded particles.
• the melting point of the resin particles is 165.0° C. or lower, there is no fear that P3HA will be hydrolyzed during foaming of the resin particles.
• components other than P3HA contained in the resin particles such as additives have almost no effect on the melting point of the resin particles.
• the melting point of the resin particles can also be said to be the melting point of P3HA contained in the resin particles.
• the melting point (Tmp) of the resin particles is measured by differential scanning calorimetry (hereinafter referred to as "DSC method").
• DSC method differential scanning calorimetry
• the specific operating procedure is as follows: (1) Weigh out 5 mg to 6 mg of resin particles; (2) Raise the temperature of the resin particles from 10 °C to 190 °C at a heating rate of 10 °C/min. (3) The temperature of the highest melting peak of the DSC curve of the resin particles obtained in the step (2) above can be determined as the melting point of the resin particles.
• the melt flow rate (hereinafter also referred to as MFR) of the resin particles at 165°C is preferably 1.0 to 20.0 g/10 min, more preferably 1.0 to 17.0 g/10 min, and Preferably it is 1.0 to 15.0 g/10 min.
• MFR melt flow rate
• the MFR is 1.0 g/10 min or more, foamed particles with high apparent density can be obtained by only one foaming.
• the MFR is 20.0 g/10 min or less, the strength of the foamed molded product obtained will be high.
• the MFR of the resin particles was measured using a melt flow index tester (manufactured by Yasuda Seiki Seisakusho Co., Ltd.) in accordance with JIS K7210, at a load of 5 kg, and the measurement temperature was the melting temperature read from the DSC curve obtained by measuring the melting point of the resin particles above. It is determined by measuring at the end temperature +5 to 10°C.
• the weight of each resin particle is not particularly limited, but is preferably 0.3 mg to 10.0 mg, more preferably 0.5 mg to 5.0 mg. When the weight of each resin particle is 0.3 mg or more, the resin particles can be stably manufactured with high productivity. On the other hand, if the weight of each resin particle is 10.0 mg or less, the foamed particles obtained from the resin particles can easily provide a thinned foamed molded article.
• the shape of the resin particles is not particularly limited, but the ratio of length to diameter (length/diameter) is preferably 0.5 to 3.0, more preferably 1.5 to 2.7, and 2.0 to 2. .5 is more preferred. If the length/diameter of the resin particles is 0.5 to 3.0, the shape of the resulting expanded particles will not be flat and will tend to be spherical or approximately spherical. Spherical or approximately spherical foamed particles have good filling properties into the molding space of a mold of a molding machine, and can provide a foamed molded product with good surface beauty.
• the length of the resin particle is intended to be the maximum value of the distance between two cut surfaces that appear (occur) on the resin particle when cutting the resin particle during the manufacturing process of the resin particle.
• the length direction of the resin particle is the x direction
• an arbitrary straight line y and a straight line z perpendicular to the straight line y are drawn on a cross section (cross section x) perpendicular to the x direction.
• the line segment obtained by cutting straight line y at cross section x is called line segment y
• the line segment obtained by cutting straight line z at cross section x is called line segment z.
• the diameter of the resin particle is intended to be the average value of the length of the line segment y and the length of the line segment z.
• the step of preparing resin particles according to one embodiment of the present invention is a step of preparing P3HA-based resin particles containing P3HA and, if necessary, additives.
• the resin particle preparation step may be performed before the foaming step described below.
• the step of preparing resin particles can also be said to be a step of molding a resin composition containing P3HA into a shape that can be easily used for foaming.
• the mode of the resin particle preparation process is not particularly limited as long as resin particles can be obtained.
• the resin particle preparation process is (a) a melt-kneading step of melt-kneading a resin composition containing P3HA and additives as necessary; (b) It is preferable to include a particle forming step of forming the melt-kneaded resin composition into a shape that can be easily used for foaming.
• the mode of the melt-kneading step is not particularly limited as long as a melt-kneaded resin composition can be obtained.
• Specific examples of the melt-kneading step include the following methods (a1) and (a2): (a1) P3HA and, if necessary, additives are mixed or blended using a mixing device or the like to prepare a resin composition.
• the order in which P3HA and optional additives are mixed or blended (dry blend) is not particularly limited.
• the order in which P3HA and, if necessary, additives are supplied to the melt-kneading apparatus is not particularly limited.
• the mixing device is not particularly limited, and examples thereof include a ribbon blender, flash blender, tumbler mixer, super mixer, and the like.
• the melt-kneading device is not particularly limited, and examples thereof include an extruder, a kneader, a Banbury mixer, a roll, and the like.
• an extruder is preferable, and a twin-screw extruder is more preferable because of its excellent productivity and convenience.
• the types and amounts of P3HA and additives used for mixing or blending determine the types and amounts of P3HA and additives in the resulting resin particles. Furthermore, in the method (a2) above, the types and amounts of P3HA and additives supplied to the melt-kneading device become the types and contents of P3HA and additives in the resulting resin particles. Furthermore, the types and contents of P3HA and additives in the resin particles are the types and contents of P3HA and additives in expanded particles obtained using the resin particles. Therefore, regarding the type, usage amount, supply amount, etc. of the additive, the description in the above-mentioned (Additives) section is incorporated.
• the subsequent foaming step is performed without using all or part of the additives (for example, crosslinking agents, etc.) used in the method for producing expanded particles in the resin particle preparation step, that is, without incorporating them into the resin particles. It may be added to the dispersion liquid during the dispersion process (for example, in the dispersion process).
• the temperature at which the resin composition is melt-kneaded cannot be unconditionally defined because it depends on the physical properties of P3HA (melting point, weight average molecular weight, etc.) and the types of additives used.
• the temperature when melt-kneading the resin composition for example, the temperature of the melt-kneaded resin composition discharged from the nozzle of the die (hereinafter sometimes referred to as composition temperature) may be 150°C to 200°C.
• the temperature is preferably 160°C to 195°C, and even more preferably 170°C to 190°C.
• the composition temperature is 150° C. or higher, there is no risk that the resin composition will be insufficiently melted and kneaded.
• the composition temperature is 200° C. or lower, there is no fear that P3HA will thermally decompose.
• the mode of the particle molding step is not particularly limited as long as the melt-kneaded resin composition can be molded into a desired shape.
• the melt-kneaded resin composition can be easily molded into a desired shape in the particle molding step.
• the melt-kneaded resin composition is discharged from a nozzle of a die provided in a melt-kneading device, and the resin composition is cut into a desired shape by a cutting device simultaneously with or after the discharge.
• the shape of the resulting resin particles is not particularly limited, but cylinders, elliptical cylinders, spheres, cubes, rectangular parallelepipeds, and the like are preferred because they can be easily used for foaming.
• the resin composition discharged from the nozzle of the die may be cooled.
• the resin composition may be cut by a cutting device simultaneously with or after cooling of the resin composition.
• the temperature exhibited by the cooled resin composition (hereinafter sometimes referred to as cooling temperature) is not particularly limited.
• the cooling temperature is preferably 20°C to 80°C, more preferably 30°C to 70°C, even more preferably 40°C to 60°C. According to this configuration, since the melt-kneaded resin composition crystallizes sufficiently quickly, it has the advantage that the productivity of resin particles is improved.
• the glass transition temperature of the expanded particles is 2.0°C or lower, preferably 1.8°C or lower, and more preferably 1.6°C or lower. Since the glass transition temperature of the foamed particles is 2.0° C. or lower, a foamed molded product of P3HA resin that has excellent strength even when used in an extremely low temperature environment can be obtained.
• the lower limit of the glass transition temperature of the expanded particles is not particularly limited, but is, for example, -6.5°C or higher, preferably -6.0°C or higher, and preferably -5.5°C or higher. More preferably, the temperature is ⁇ 5.0° C. or higher. In particular, when the lower limit of the glass transition temperature of the expanded particles is ⁇ 5.0° C. or higher, the shrinkage rate is excellent.
• the expansion ratio of the expanded particles is preferably 20 to 60 times, more preferably 20 to 50 times, even more preferably 23 to 50 times, and particularly preferably 25 to 40 times.
• Expanded particles have a crosslinked structure.
• the crosslinked structure of foamed particles is evaluated by the gel fraction of the foamed particles.
• the gel fraction of the foamed particles is 1% by weight or more based on 100% by weight of the foamed particles.
• the method for crosslinking the foamed particles is not particularly limited, but includes a method of adding a crosslinking agent during the production of the foamed particles, as described below.
• the gel fraction of the foamed particles is preferably 65 to 90% by weight, more preferably 70 to 85% by weight, and even more preferably 72 to 83% by weight, based on 100% by weight of the expanded particles. preferable.
• the gel fraction of the expanded particles is 65% by weight or more based on 100% by weight of the expanded particles, when forming a foamed molded product, the molding temperature range of the expanded particles that can provide a high quality foamed molded product is wide. This has the advantage of improving productivity, and when it is 90% by weight or less, a foamed molded product with excellent surface beauty can be obtained.
• the gel fraction of expanded particles is an index indicating the degree of crosslinking of P3HA in the expanded particles.
• the gel fraction of the expanded particles can be controlled by the type of crosslinking agent and/or its usage amount.
• the method of measuring the gel fraction of expanded particles please refer to Examples of the present application.
• the average cell diameter of the expanded particles is not particularly limited, but is preferably 270 ⁇ m or less, more preferably 250 ⁇ m or less. If the average cell diameter of the expanded particles is 270 ⁇ m or less, there is an advantage that the molding cycle tends to be good. Further, the lower limit of the average cell diameter of the expanded particles is not particularly limited, but is preferably 50 ⁇ m or more, more preferably 100 ⁇ m or more, and even more preferably 140 ⁇ m or more. When the average cell diameter of the foamed particles is 50 ⁇ m or more, there is an advantage that a foamed molded product with excellent surface beauty can be obtained by molding the foamed particles.
• the bulk density of the expanded particles is not particularly limited, but is preferably 20.0 g/L to 600.0 g/L, more preferably 30.0 g/L to 300.0 g/L, and 32.0 g/L. /L to 100.0g/L is more preferable.
• the bulk density of the foamed particles is (a) 20.0 g/L or more, there is an advantage that a foam molded article with excellent cushioning properties and/or mechanical strength tends to be obtained, and (b) 60.0 g/L or more. When it is 0 g/L or less, there is an advantage that a foamed molded article with excellent lightness tends to be obtained.
• the method of measuring the bulk density of expanded particles please refer to the Examples of the present application.
• the expanded P3HA-based resin particles of the present invention are obtained by foaming the above-mentioned P3HA-based resin particles.
• the foaming step in the manufacturing method is (a) a dispersion step of dispersing resin particles, an aqueous dispersion medium, a crosslinking agent, a blowing agent, and, if necessary, a dispersant and/or a dispersion aid in a container; (b) a heating-pressure raising step of raising the temperature inside the container to a constant temperature and raising the pressure inside the container to a constant pressure; (c) a holding step of maintaining the temperature and pressure inside the container at a constant temperature and constant pressure; (d) It is preferable to include the step of releasing one end of the container and releasing the dispersion liquid in the container into a region (space) having a pressure lower than the foaming pressure (namely, the pressure inside the container).
• (a) Dispersion process for example, resin particles, a crosslinking agent, a blowing agent, and, if necessary, a dispersant, a crosslinking aid, a dispersion aid, and/or a plasticizer are dispersed in an aqueous dispersion medium. It can also be said to be a process of preparing a dispersion liquid.
• the crosslinking agent and the crosslinking aid are consumed by the reaction with P3HA in the resin particles and do not need to be present, and the blowing agent and plasticizer are impregnated and dispersed in the resin particles. It does not have to exist in any state.
• the container is not particularly limited, it is preferably a container that can withstand the foaming temperature and foaming pressure described below, and is preferably a pressure-resistant container, for example.
• the aqueous dispersion medium is not particularly limited as long as it can uniformly disperse resin particles, crosslinking agents, blowing agents, etc.
• As the aqueous dispersion medium for example, tap water and/or industrial water can also be used. Since stable production of expanded particles is possible, aqueous dispersion media such as RO water (water purified by reverse osmosis membrane method), distilled water, deionized water (water purified by ion exchange resin), etc. It is preferable to use pure water, ultrapure water, or the like.
• the amount of the aqueous dispersion medium used is not particularly limited, but is preferably 100 parts by weight to 1000 parts by weight based on 100 parts by weight of the resin particles.
• a crosslinking agent is used in the method for producing expanded particles.
• P3HA in the obtained expanded particles becomes P3HA having a crosslinked structure. That is, expanded P3HA particles having an excellent gel fraction can be obtained.
• the foaming process the crosslinking reaction of P3HA in the resin particles also proceeds, so the foaming process can also be called a crosslinking process.
• the crosslinking agent is not particularly limited as long as it can crosslink P3HA.
• organic peroxides are preferred.
• the P3HA-based expanded particles are preferably crosslinked with an organic peroxide.
• the organic peroxide may be used in the resin particle manufacturing process, in the dispersion process, or in the resin particle manufacturing process and the dispersion process. More specifically, in order to react the organic peroxide with P3HA, the organic peroxide and P3HA may be melt-kneaded in the resin particle production process, and the resin particles and organic peroxide may be mixed in an aqueous solution in the dispersion process.
• the organic peroxide and P3HA may be melt-kneaded and the resin particles and the organic peroxide may be further dispersed in an aqueous dispersion medium.
• the dispersion step by dispersing the resin particles produced in the resin particle production step and the organic peroxide in an aqueous dispersion medium, the resin particles can be impregnated and reacted with the organic peroxide.
• organic peroxides are preferred as the crosslinking agent in the method for producing expanded particles. Note that when an organic peroxide is used as a crosslinking agent, a crosslinked structure is formed by directly bonding the molecular chains of P3HA (without intervening a structure derived from the crosslinking agent).
• the organic peroxide used as a crosslinking agent is preferably an organic peroxide with a 1-hour half-life temperature of 90°C to 160°C, and an organic peroxide with a 1-hour half-life temperature of 105°C to 125°C.
• An organic peroxide having a temperature of 1 hour half-life of 110°C to 125°C is more preferred.
• benzoyl peroxide BPO, 1-hour half-life temperature: 92°C
• TBEC t-butylperoxy-2-ethylhexyl carbonate
• TBIC t-butylperoxyisopropyl carbonate
• TAEC t-amylperoxy-2-ethylhexyl carbonate
• TAIC t-amylperoxyisopropyl carbonate
• TAIC 1 hour half-life temperature: 117°C
• organic peroxide used as a crosslinking agent an organic peroxide having a t-butoxy group and/or a cumyloxy group is more preferable because the crosslinking of P3HA in the resulting expanded particles approaches uniform crosslinking.
• peroxides having a t-butoxy group and/or cumyloxy group include t-butyl peroxy-2-ethylhexyl carbonate (TBEC), t-butyl peroxyisopropyl carbonate (TBIC), and t-butyl peroxy-2-ethylhexyl carbonate (TBEC), t-butyl peroxyisopropyl carbonate (TBIC), Oxyisobutyrate, t-butylperoxy-2-ethylhexanoate, t-butylperoxyisononanoate, t-butylperoxyacetate, t-butylperoxydibenzoate, dicumyl peroxide, 2,5 -dimethyl-2,5-di(t-butylperoxy)hexane, di-t-butylperoxide, 1,1-bis(t-butylperoxy)cyclohexane (TBCH), 2,2-di(t-but
• an organic peroxide having a t-butoxy group and/or a cumyloxy group when using an organic peroxide having a t-butoxy group and/or a cumyloxy group, the environmental impact will be lower than that of an organic peroxide (for example, BPO) that does not have a t-butoxy group and/or a cumyloxy group. It also has the advantage of having less Among organic peroxides having a t-butoxy group and/or a cumyloxy group, those having a t-butoxy group and/or a cumyloxy group, and Organic peroxides having peroxycarbonate groups are preferred.
• the present inventors have found that when using an organic peroxide having a t-butoxy group and/or a cumyloxy group as a crosslinking agent, it is possible to easily obtain foamed particles whose internal pressure is difficult to reduce. I independently found out that it is possible. Therefore, when an organic peroxide having a t-butoxy group and/or a cumyloxy group is used as a crosslinking agent, it is easy to form foamed particles that can provide a foamed molded product with excellent fusion properties by applying a lower internal pressure than in the conventional technology. can be obtained.
• the amount of the crosslinking agent used is not particularly limited, but it is preferably 0.1 parts by weight to 5.0 parts by weight, and 0.3 parts by weight to 3.0 parts by weight, based on 100 parts by weight of the resin particles.
• the amount is more preferably 0.5 parts by weight to 3.0 parts by weight, even more preferably 1.0 parts by weight to 3.0 parts by weight.
• the amount of the crosslinking agent used is 0.1 part by weight or more based on 100 parts by weight of the resin particles, (a) the obtained expanded particles can be sufficiently crosslinked, and (b) the obtained expanded particles can become independent. It is possible to obtain a foamed molded article with a high cell content, good surface beauty, and a low molding shrinkage rate.
• the amount of crosslinking agent used is 5.0 parts by weight or less based on 100 parts by weight of the resin particles, an effect corresponding to the amount of crosslinking agent used can be obtained, so there is no risk of economic waste. .
• the amount of crosslinking agent used has a positive correlation with the gel fraction of the foamed particles, and greatly influences the value of the gel fraction of the foamed particles. Therefore, it is desirable to strictly set the amount of crosslinking agent to be used in consideration of the gel fraction of the resulting expanded particles.
• the resin particles used in the dispersion process may already contain a crosslinking agent, but in that case, the amount of crosslinking agent that the resin particles already contain before the dispersion process and the amount of crosslinking agent used in the dispersion process It is preferable that the total amount satisfies the above range.
• blowing agents inorganic gases such as nitrogen, carbon dioxide, and air; saturated hydrocarbons having 3 to 5 carbon atoms such as propane, normal butane, isobutane, normal pentane, isopentane, and neopentane; dimethyl ether, diethyl ether, and methyl ethyl ether ethers such as; halogenated hydrocarbons such as monochloromethane, dichloromethane, dichlorodifluoroethane; and water.
• saturated hydrocarbons having 3 to 5 carbon atoms, ethers, halogenated hydrocarbons, and water can be used.
• nitrogen or carbon dioxide as the foaming agent.
• One type of these blowing agents may be used alone, or two or more types may be used in combination. Furthermore, when two or more types of blowing agents are mixed and used, the mixing ratio may be adjusted as appropriate depending on the purpose.
• the amount of the blowing agent used is not particularly limited, but is preferably 2 parts by weight to 10,000 parts by weight, more preferably 5 parts by weight to 5,000 parts by weight, and 10 parts by weight to 1,000 parts by weight, based on 100 parts by weight of the resin particles. More preferred. When the amount of the foaming agent used is 2 parts by weight or more per 100 parts by weight of the resin particles, foamed particles with a suitable density can be obtained. On the other hand, when the amount of the blowing agent used is 10,000 parts by weight or less based on 100 parts by weight of the resin particles, an effect corresponding to the amount of the blowing agent used is obtained, so that no economic waste occurs.
• a dispersant In the method for producing expanded particles, it is preferable to use a dispersant.
• the use of a dispersant has the advantage that coalescence (sometimes referred to as blocking) between resin particles can be suppressed and expanded particles can be stably produced.
• the dispersant include inorganic substances such as tribasic calcium phosphate, tribasic magnesium phosphate, basic magnesium carbonate, calcium carbonate, barium sulfate, kaolin, talc, clay, aluminum oxide, titanium oxide, and aluminum hydroxide.
• One type of these dispersants may be used alone, or two or more types may be used in combination.
• the mixing ratio may be adjusted as appropriate depending on the purpose.
• the amount of the dispersant used is not particularly limited, but is preferably from 0.1 parts by weight to 3.0 parts by weight, more preferably from 0.5 parts by weight to 1.5 parts by weight, based on 100 parts by weight of the resin particles.
• the oxygen concentration in the container and the amount of dissolved oxygen in the dispersion liquid are lowered in order to increase the crosslinking efficiency of P3HA. It is preferable.
• Methods for lowering the oxygen concentration in the container and the amount of dissolved oxygen in the dispersion include replacing the gas in the container and the gas dissolved in the dispersion with inorganic gases such as carbon dioxide and nitrogen; One example is to evacuate the gas inside.
• a dispersion aid may be used to improve the effect of suppressing coalescence between resin particles.
• the dispersion aid include anionic surfactants such as sodium alkanesulfonate, sodium alkylbenzenesulfonate, and sodium ⁇ -olefinsulfonate.
• anionic surfactants such as sodium alkanesulfonate, sodium alkylbenzenesulfonate, and sodium ⁇ -olefinsulfonate.
• One type of these dispersion aids may be used alone, or two or more types may be used in combination.
• the mixing ratio may be adjusted as appropriate depending on the purpose.
• the amount of the dispersion aid used is not particularly limited, but is preferably 0.001 part by weight to 0.5 part by weight, more preferably 0.01 part to 0.2 part by weight, based on 100 parts by weight of the resin particles. . In order to further improve the effect of suppressing coalescence between resin particles, it is preferable to use the dispersant and the dispersion aid together.
• the temperature-raising-pressure step is preferably carried out after the dispersion step, and the holding step is preferably carried out after the temperature-raising step.
• the constant temperature in the heating-pressure increasing step and the holding step may be referred to as the foaming temperature
• the constant pressure may be referred to as the foaming pressure.
• the foaming temperature is preferably lower than the melting point (Tmp) of the resin particles before foaming.
• the foaming temperature is, for example, preferably (Tmp-40)°C to Tmp°C, more preferably (Tmp-30)°C to (Tmp-10)°C, and even more preferably (Tmp-20)°C to (Tmp-15)°C.
• Tmp-19)°C to (Tmp-16)°C is most preferred.
• the foaming temperature preferably satisfies the above temperature range and is 130.0°C or higher.
• the foaming temperature satisfies the above-mentioned temperature range and is 130.0° C. or higher, foamed particles with good bulk density can be obtained and the holding time can be shortened.
• components other than P3HA contained in the resin particles such as additives have almost no effect on the melting point of the resin particles.
• the melting point of the resin particles can also be said to be the melting point of P3HA contained in the resin particles.
• the rate at which the temperature is raised to the desired foaming temperature (hereinafter sometimes referred to as temperature raising rate) is preferably 1.0°C/min to 3.0°C/min. More preferably 5°C/min to 3.0°C/min. If the temperature increase rate is 1.0° C./min or more, productivity is excellent. On the other hand, if the temperature increase rate is 3.0° C./min or less, there is no fear that the impregnation of the resin particles with the blowing agent and the reaction between the crosslinking agent and P3HA become insufficient during the temperature increase.
• the foaming pressure is, for example, preferably 1.0 MPa (gauge pressure) to 10.0 MPa (gauge pressure), more preferably 2.0 MPa (gauge pressure) to 5.0 MPa (gauge pressure), and 2.5 MPa (gauge pressure). ⁇ 4.5 MPa (gauge pressure) is more preferred, 3.0 MPa (gauge pressure) ⁇ 4.0 MPa (gauge pressure) is even more preferred, and 3.1 MPa (gauge pressure) ⁇ 3.5 MPa (gauge pressure) is even more preferred. , 3.2 MPa (gauge pressure) to 3.4 MPa (gauge pressure) is particularly preferred. When the foaming pressure is 1.0 MPa (gauge pressure) or higher, foamed particles with a suitable density can be obtained.
• the time (holding time) for holding the dispersion in the container near the foaming temperature and foaming pressure is not particularly limited.
• the holding time is preferably 1 minute to 120 minutes, more preferably 5 minutes to 100 minutes, even more preferably 10 minutes to 80 minutes, particularly preferably 15 minutes to 70 minutes.
• the holding time is 1 minute or more, there is no risk of unreacted crosslinking agent remaining.
• the heating time is 120 minutes or less, there is no risk of excessive hydrolysis of P3HA contained in the resin particles.
• the release step is preferably carried out after the temperature and pressure increase step or after the holding step.
• the ejection step allows the resin particles to be foamed, resulting in expanded particles.
• area with a pressure lower than the foaming pressure is intended to mean “an area under a pressure lower than the foaming pressure” or “a space under a pressure lower than the foaming pressure”, and "an atmosphere with a pressure lower than the foaming pressure”. It can also be said to be “lower”.
• the region of pressure lower than the foaming pressure is not particularly limited as long as it is lower than the foaming pressure, and may be, for example, a region under atmospheric pressure.
• the dispersion liquid In the discharge process, when the dispersion liquid is discharged into a region with a pressure lower than the foaming pressure, the dispersion liquid is passed through an opening orifice with a diameter of 1 mm to 5 mm for the purpose of adjusting the flow rate of the dispersion liquid and reducing the variation in the expansion ratio of the resulting expanded particles. can also be released. Further, when using resin particles having a relatively high melting point, the low pressure region (space) may be filled with saturated water vapor for the purpose of improving foamability.
• the method for producing expanded beads may further include a two-stage foaming step in which the expanded beads obtained in the foaming step are further expanded.
• the two-stage foaming step is not particularly limited as long as the foamed particles obtained in the foaming step can be further expanded to obtain foamed particles having an apparent density that is even smaller than the apparent density of the foamed particles obtained in the foaming step.
• Examples of the two-stage foaming process include the following aspects: (s1) Feeding the expanded particles obtained in the foaming process into a container; (s2) Supplying air or an inorganic gas such as carbon dioxide into the container.
• the foamed particles are impregnated with the inorganic gas to make the pressure inside the foamed particles higher than normal pressure; (s4) Then, the foamed particles are The particles are further expanded by heating with water vapor or the like to obtain expanded particles having a desired apparent density.
• the foamed particles obtained in the two-stage foaming process are sometimes referred to as two-stage foamed particles.
• the foaming process may be referred to as a single-stage foaming process, and the foamed particles obtained in the single-stage foaming process may be referred to as single-stage foamed particles.
• the gel fraction of the two-stage expanded particles is preferably the same as the gel fraction of the expanded particles. That is, as for the gel fraction of the two-stage expanded particles, the description in the above section (gel fraction) can be used as appropriate.
• a P3HA-based resin foam molded article according to an embodiment of the present invention is obtained by molding the above-mentioned P3HA-based resin foam particles.
• the process of molding the expanded P3HA-based resin particles includes a pressurizing process, a filling process, and a foam molding process.
• the "poly(3-hydroxyalkanoate) foam molded product” is also referred to as the "foam molded product” below.
• the method for producing the present foamed molded product ie, the method for molding expanded particles
• any known method can be applied.
• the following in-mold foaming methods (A) to (D) may be mentioned, but are not particularly limited: (A) pressurize the foamed particles with an inorganic gas in a container to impregnate the foamed particles with the inorganic gas, apply a predetermined internal pressure to the foamed particles, and then fill a mold with the foamed particles; Method of heating with steam; (B) A method in which the expanded particles are filled into a mold, compressed to reduce the volume within the mold by 10% to 75%, and heated with steam; (C) A method in which the foamed particles are compressed using gas pressure, filled into a mold, and heated with steam using the recovery power of the foamed particles; (D) A method in which the foamed particles are filled into a mold without any particular pretreatment and heated with steam.
• the pressure of the water vapor for heating the present foamed particles (hereinafter sometimes referred to as molding pressure) varies depending on the characteristics of the foamed particles used, etc., and cannot be unconditionally defined.
• the molding pressure is preferably 0.05 MPa to 0.30 MPa (gauge pressure), more preferably 0.08 MPa to 0.25 MPa (gauge pressure), and even more preferably 0.10 MPa to 0.20 MPa (gauge pressure).
• the inorganic gas in the method (A) of the present method for producing a foamed molded article at least one selected from the group consisting of air, nitrogen, oxygen, carbon dioxide, helium, neon, argon, etc. can be used.
• air and/or carbon dioxide are preferred.
• the temperature inside the container when impregnating expanded particles with inorganic gas in method (A) of the present foam molded manufacturing method is preferably 10°C to 90°C, more preferably 20°C to 90°C, and 30°C to 90°C. C. to 90.degree. C. is more preferable, and 40.degree. C. to 90.degree. C. is even more preferable.
• the internal pressure of the foamed particles in the method (A) is preferably 0.10 MPa to 0.30 MPa (absolute pressure), more preferably 0.11 MPa to 0.25 MPa (absolute pressure), More preferably 0.12 MPa to 0.20 MPa (absolute pressure).
• the internal pressure of the foamed particles may be measured according to the measuring method described in Examples described later.
• the expansion ratio of the P3HA resin foam molded product obtained as described above is preferably 20 to 60 times, more preferably 23 to 50 times, and even more preferably 25 to 40 times. . Within the above range, it is possible to provide a foamed molded article with a good balance between mechanical strength and light weight.
• For the method of calculating the expansion ratio please refer to the Examples of the present application.
• the P3HA-based resin foam molding according to an embodiment of the present invention can be used for various purposes, such as food containers, packaging cushioning materials, agricultural boxes, fish boxes, low-temperature transportation containers, etc. It can also be used suitably when used.
• one aspect of the present invention includes the following. ⁇ 1> Poly(3-hydroxyalkanoate)-based resin foam particles obtained by foaming resin particles containing a poly(3-hydroxyalkanoate)-based resin,
• the resin particles include two or more types of poly(3-hydroxyalkanoate)-based resins having different compositions of constituent units,
• the foamed poly(3-hydroxyalkanoate) resin particles have a glass transition temperature of 2.0° C. or lower.
• the resin particles include a copolymer having a 3-hydroxybutyrate unit and a comonomer unit as the poly(3-hydroxyalkanoate)-based resin,
• the resin particles include a copolymer having a 3-hydroxybutyrate unit and a comonomer unit as the poly(3-hydroxyalkanoate)-based resin, A copolymer (A) in which the resin particles have a content of comonomer units of 1.0 to 6.0 mol%, and a copolymer (B) in which the content of comonomer units is 13.0 mol% or more,
• the proportion of the copolymer (A) is 65% by weight or more with respect to the total of 100% by weight of the copolymer (A) and the copolymer (B).
• Poly(3-hydroxyalkanoate) resin foam particles ⁇ 5> The poly(3-hydroxyalkanoate) according to any one of ⁇ 1> to ⁇ 4>, wherein the resin particles are poly(3-hydroxybutyrate-co-3-hydroxyhexanoate). foamed resin particles.
• the gel fraction is 65 to 90% by weight based on 100% by weight of the expanded poly(3-hydroxyalkanoate) resin particles.
• Poly(3-hydroxyalkanoate) resin foam particles are Poly(3-hydroxyalkanoate) resin foam particles.
• crystal nucleating agent ⁇ Pentaerythritol (Mitsubishi Chemical Co., Ltd., Neulyser P) (Bubble regulator) ⁇ Talc (manufactured by Nippon Talc Co., Ltd., Micro Ace K1) (Lubricant) ⁇ Behenic acid amide (manufactured by Nippon Fine Chemical Co., Ltd., BNT-22H) ⁇ Erucic acid amide (manufactured by Nippon Fine Chemical Co., Ltd., Neutron-S) (foaming agent) ⁇ Carbon dioxide (manufactured by Air Water Co., Ltd.) ⁇ Nitrogen (manufactured by Air Water Co., Ltd.) (Crosslinking agent) ⁇ 1,1-di(t-butylperoxy)cyclohexane (TBCH: Perhexa C manufactured by NOF Corporation) (dispersant) ⁇ Tricalcium phosphate (manufactured by Taihei
• the glass transition temperature of the P3HA-based resin particles and expanded P3HA-based resin particles was measured using a differential scanning calorimeter (Model DSC6200, manufactured by Seiko Instruments). The specific operating procedure is as follows: (1) Weigh out 2 mg of P3HA; (2) Increase the temperature of P3HA from -50°C to 190°C at a heating rate of 10°C/min. (3) In the DSC curve of P3HA obtained in the process of (2) above, a straight line that is equidistant in the vertical axis direction from the extended straight line of the low-temperature side baseline and the high-temperature side baseline, and the glass The point where the curve of the stepped transition portion intersects is defined as the glass transition temperature.
• the destructive test was conducted as follows: (1) The sample was placed on a table and the weight was lifted to a height of 885 mm from the sample (fall height); (2) the stopper supporting the weight was removed; A weight was allowed to fall freely onto the sample.
• the expansion ratio of the expanded P3HA-based resin particles was calculated by the following formula using the above bulk density: specific gravity (1200)/bulk density of expanded P3HA-based resin particles.
• DSC peak area heat of fusion
• the DSC peak area was measured using the following steps (1) to (4): (1) Approximately 2 mg of expanded particles were weighed; (2) using a differential scanning calorimeter (DSC6200 model manufactured by Seiko Instruments). (3) In the DSC curve obtained in the process of (2) above, the temperature at the start of melting was A baseline was created by connecting the point representing (80°C) and the point representing the melting end temperature with a straight line; (4) The area surrounded by the created baseline and the DSC curve was defined as the DSC peak area, and the DSC peak area The amount of heat calculated from the above was taken as the amount of heat of fusion of the expanded particles.
• Example 1 ⁇ Resin particle manufacturing process> A twin-screw extruder (TEM-26SX manufactured by Toshiba Machinery Co., Ltd.) was used for melt-kneading the P3HA-based composition. Based on 100 parts by weight of the P3HA-based resin composition, 86 parts by weight of P3HA-1, 7 parts by weight of P3HA-2, 7 parts by weight of P3HA-3, and 0.10 parts by weight of talc as a foam regulator.
• TEM-26SX manufactured by Toshiba Machinery Co., Ltd.
• P3HA-based composition 1.0 parts of pentaerythritol as a crystal nucleating agent, 0.50 parts by weight of behenic acid amide and 0.5 parts by weight of erucic acid amide as lubricants were weighed and dry blended to obtain a P3HA-based composition.
• the prepared P3HA-based composition was supplied to a twin-screw extruder, and the P3HA-based composition was melt-kneaded at a cylinder set temperature of 130.0° C. to 160° C. (melt-kneading step). A melt-kneaded P3HA composition at 180° C. was discharged from the nozzle of a die attached to the tip of the extruder.
• the discharged P3HA-based composition was cooled with water at 43° C. and then cut to obtain cylindrical P3HA-based resin particles having a length/diameter of 2.5 (particle molding step).
• the melting point of the obtained resin particles was 148.4°C. Thereafter, the glass transition temperature of the obtained resin particles was measured by the method described above.
• ⁇ Expanded particle manufacturing process 100 parts by weight of the P3HA-based resin particles obtained in the above (resin particle manufacturing process), 1.8 parts by weight of TBCH as a crosslinking agent, 350 parts by weight of pure water, and 1.8 parts by weight of TBCH as a dispersant.
• Calcium triphosphate and 0.15 parts by weight of sodium alkanesulfonate as a dispersion aid were fed into a pressure vessel. The raw materials in the pressure vessel were stirred. Thereafter, the contents (dispersion liquid) in the pressure container were continued to be stirred until the release of the dispersion liquid was completed.
• the pressure vessel was sufficiently ventilated with carbon dioxide gas to remove oxygen inside the pressure vessel. Furthermore, carbon dioxide was supplied as a foaming agent into the pressure container to prepare a dispersion liquid (dispersion step). Thereafter, the temperature inside the pressure container was raised to the foaming temperature of 131.0°C. Further, carbon dioxide was supplied to the pressure container to increase the pressure inside the pressure container to a foaming pressure of 3.3 MPa (gauge pressure) (temperature increase-pressure increase step). Next, the temperature and pressure in the pressure container were maintained at around the foaming temperature and foaming pressure, respectively, for 20 minutes (holding step).
• the valve at the bottom of the pressure container was opened and the dispersion in the pressure container was released under atmospheric pressure through an opening orifice with a diameter of 3.6 mm to obtain expanded P3HA particles (discharge step).
• discharge step After washing off the dispersant and the like adhering to the surface of the foamed particles with water, the foamed particles were dried at 75°C.
• the glass transition temperature, gel fraction, bulk density, expansion ratio calculation, and heat of fusion were measured by the methods described above.
• ⁇ Foam molded body manufacturing process> The expanded particles were supplied to a pressure container at 80°C. While the temperature inside the pressure container was maintained at 80° C., the foamed particles in the pressure container were pressurized using air to bring the internal pressure of the foamed particles to 0.16 MPa (absolute pressure). The pressure container was cooled to room temperature, and the foamed particles (foamed particles to which internal pressure was applied) inside the pressure container were taken out (pressurization step).
• the mold used was a mold that was mounted on a molding machine (EP-900 manufactured by DAISEN) and had a molding space of 370 mm long x 320 mm wide x 80 mm thick.
• a filling machine was used to fill the molding space of the mold with cracking of 4.0 mm with foamed particles to which internal pressure was applied in the pressurizing process (filling process).
• the movable mold is driven toward the fixed mold, and after the mold is completely closed, the mold is preheated with steam, and then the mold is heated with steam on one side and the other on the other side, and then the mold is heated. Both sides were heated with steam.
• the filled foam particles were fused and a foam molded article was obtained (foam molding step).
• the steam pressure (steam pressure A) during one-sided heating and reverse one-sided heating is 0.06 MPa (gauge pressure)
• steam pressure (steam pressure B) during double-sided heating is 0.13 MPa (gauge pressure). did.
• the obtained foamed molded article was taken out from the mold and dried at 75°C.
• the foamed molded product after drying was subjected to a dynamic test to measure the passing temperature of the dynamic drop test, and the shrinkage rate was also measured.
• Example 2 Production of resin particles in the same manner as in Example 1, except that P3HA-1 used in the melt-kneading step was 80 parts by weight, P3HA-2 was 10 parts by weight, and P3HA-3 was 10 parts by weight. Expanded particles and expanded molded articles were manufactured. The melting point of the obtained resin particles was 149.5°C. Further, in the same manner as in Example 1, the glass transition temperature, gel fraction, bulk density, expansion ratio, and heat of fusion of the obtained expanded particles were measured. In addition, for the obtained foamed molded product, the dynamic drop test passing temperature was measured in the same manner as in Example 1, and the shrinkage rate was also measured.
• Example 3 Production of resin particles in the same manner as in Example 1, except that P3HA-1 used in the melt-kneading step was 60 parts by weight, P3HA-2 was 20 parts by weight, and P3HA-3 was 20 parts by weight. Expanded particles and expanded molded articles were manufactured. The melting point of the obtained resin particles was 152.9°C. Further, in the same manner as in Example 1, the glass transition temperature, gel fraction, bulk density, expansion ratio, and heat of fusion of the obtained expanded particles were measured. In addition, for the obtained foamed molded product, the dynamic drop test passing temperature was measured in the same manner as in Example 1, and the shrinkage rate was also measured.
• Example 4 Production of resin particles in the same manner as in Example 1, except that P3HA-1 used in the melt-kneading step was 40 parts by weight, P3HA-2 was 30 parts by weight, and P3HA-3 was 30 parts by weight. Expanded particles and expanded molded articles were manufactured. The melting point of the obtained resin particles was 155.0°C. Further, in the same manner as in Example 1, the glass transition temperature, gel fraction, bulk density, expansion ratio, and heat of fusion of the obtained expanded particles were measured. In addition, for the obtained foamed molded product, the dynamic drop test passing temperature was measured in the same manner as in Example 1, and the shrinkage rate was also measured.
• the P3HA-based resin expanded particles used are P3HA-based resin expanded particles obtained by foaming resin particles containing a P3HA-based resin containing structural units having two or more different compositions, and the P3HA-based resin expanded particles are It has been revealed that if the glass transition temperature of the particles is 2.0°C or lower, the resulting foam molded product can obtain sufficient strength when used in an extremely low temperature (-20°C or lower) environment. . Furthermore, it has become clear that the above-mentioned P3HA-based resin expanded particles tend to reduce the shrinkage rate of the obtained foamed molded product, that is, the performance of the foamed molded product tends to improve.
• One embodiment of the present invention can be suitably used for food containers, packaging cushioning materials, agricultural boxes, fish boxes, low-temperature transportation containers, and the like.

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• 2023
  • 2023-02-16 WO PCT/JP2023/005350 patent/WO2023188942A1/ja not_active Ceased
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