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EP-3786224-B1 - MASTER BATCH, POLYCARBONATE RESIN COMPOSITION, INJECTION FOAM MOLDED BODY AND METHOD FOR PRODUCING SAME

EP3786224B1EP 3786224 B1EP3786224 B1EP 3786224B1EP-3786224-B1

Inventors

  • UCHIDA, SOICHI
  • SAEGUSA, KAZUNORI
  • SATO, MITSUTAKA

Dates

Publication Date
20260506
Application Date
20190424

Claims (16)

  1. A masterbatch (C) comprising: thermally expandable microcapsules (A); and a carrier resin composition (B), wherein the carrier resin composition (B) contains a carrier resin (B1) and a plasticizer (B2), the carrier resin (B1) being an acrylic resin having a weight average molecular weight, which is determined in accordance with the description, of 8,000 or more and 350,000 or less and being a solid at 20°C, and the plasticizer (B2) being a liquid at 20°C and having a weight average molecular weight of 1,000 or more and 20,000 or less, and wherein the carrier resin composition (B) is substantially compatible, as determined according to the description, with a polycarbonate resin and has a shear viscosity, which is determined in accordance with the description, of 1.0 Pa·s or more and 1.5 × 10 6 Pa·s or less at 80°C.
  2. The masterbatch according to claim 1, wherein the masterbatch (C) is used for the polycarbonate resin.
  3. The masterbatch according to claim 1 or 2, wherein the polycarbonate resin further comprises at least one other thermoplastic resin selected from the group consisting of a polyester resin, a polyester-polyether copolymer, an acrylonitrile-butadiene-styrene copolymer, an acrylonitrile-ethylene-propylene-diene-styrene copolymer, an acrylate-styrene-acrylonitrile copolymer, an acrylonitrile-styrene copolymer, a polyarylate resin, a polystyrene resin, and a polyamide resin.
  4. The masterbatch according to any one of claims 1 to 3, wherein the plasticizer (B2) is an acrylic plasticizer.
  5. The masterbatch according to any one of claims 1 to 4, wherein the carrier resin (B1) has a glass transition temperature (Tg), which is determined in accordance with the description, of -30°C or more and 150°C or less.
  6. The masterbatch according to any one of claims 1 to 5, wherein the thermally expandable microcapsules (A) have a core-shell structure and are constituted by a core comprising at least one compound having a boiling point of 10°C or more and 330°C or less and a shell that encloses the core, and wherein the shell comprises a resin having a constitutional unit derived from at least one monomer selected from the group consisting of a nitrile monomer, a (meth)acrylate monomer, an aromatic vinyl monomer, a diene monomer, a vinyl monomer having a carboxyl group, and a monomer having at least one reactive functional group selected from the group consisting of a methylol group, a hydroxyl group, an amino group, an epoxy group, and an isocyanate group.
  7. The masterbatch according to any one of claims 1 to 6, wherein the thermally expandable microcapsules (A) have a maximum expansion temperature, which is determined in accordance with the description, of 180°C or more and 300°C or less.
  8. The masterbatch according to claim 6 or 7, wherein, in the resin forming the shell, a constitutional unit derived from at least one monomer selected from the group consisting of a monomer containing a carboxyl group and a monomer containing an amino group is contained in a concentration of 12 mmol/g or less.
  9. The masterbatch according to any one of claims 1 to 8, wherein, with regard to the carrier resin (B1), acrylic resin particles (a) are coated with acrylic resin particles (b), and wherein the acrylic resin particles (a) comprise a (meth)acrylic acid ester in an amount of 30 to 100 wt% and a vinyl monomer copolymerizable with the (meth)acrylic acid ester in an amount of 0 to 70 wt%.
  10. The masterbatch according to claim 9, wherein the acrylic resin particles (b) comprise a (meth)acrylic acid ester in an amount of 30 to 100 wt% and a vinyl monomer copolymerizable with the (meth)acrylic acid ester in an amount of 0 to 70 wt%.
  11. The masterbatch according to any one of claims 9 to 10, wherein the acrylic resin particles (b) are polymer particles obtained by polymerization of 50 to 90 parts by weight of latex particles (b1) comprising a (meth)acrylic acid ester in an amount of 50 to 100 wt%, an aromatic vinyl monomer in an amount of 0 to 40 wt%, a vinyl monomer copolymerizable with the (meth)acrylic acid ester and the aromatic vinyl monomer in an amount of 0 to 10 wt%, and a multifunctional monomer in an amount of 0 to 5 wt% with 10 to 50 parts by weight of a monomer mixture (b2) comprising a (meth)acrylic acid ester in an amount of 10 to 100 wt%, an aromatic vinyl monomer in an amount of 0 to 90 wt%, a vinyl cyanate monomer in an amount of 0 to 25 wt%, and a vinyl monomer copolymerizable with the (meth)acrylic acid ester, the aromatic vinyl monomer, and the vinyl cyanate monomer in an amount of 0 to 20 wt%, and a total amount of the latex particles (b1) and the monomer mixture (b2) is 100 parts by weight.
  12. The masterbatch according to any one of claims 1 to 11, wherein the masterbatch (C) comprises the thermally expandable microcapsules (A) in an amount of 30 wt% or more and 80 wt% or less, the carrier resin (B1) in an amount of 15 wt% or more and 65 wt% or less, and the plasticizer (B2) in an amount of 5 wt% or more and 30 wt% or less, and the amount of the carrier resin (B1) is larger than the amount of the plasticizer (B2).
  13. A polycarbonate resin composition comprising the masterbatch according to any one of claims 1 to 12 in an amount of 1 to 15 wt%, a polycarbonate resin in an amount of 30 to 99 wt%, and at least one other thermoplastic resin selected from the group consisting of a polyester resin, a polyester-polyether copolymer, an acrylonitrile-butadiene-styrene copolymer, an acrylonitrile-ethylene-propylene-diene-styrene copolymer, an acrylate-styrene-acrylonitrile copolymer, an acrylonitrilestyrene copolymer, a polyarylate resin, a polystyrene resin, and a polyamide resin in an amount of 0 to 55 wt%.
  14. The polycarbonate resin composition according to claim 13, further comprising an inorganic compound.
  15. An injection molded foam that is obtained through foam injection molding of the polycarbonate resin composition according to claim 13 or 14.
  16. A method for producing an injection molded foam, the method comprising supplying the polycarbonate resin composition according to claim 13 or 14 to an injection molding machine, and moving a core of a mold backward after filling to an initial fill thickness has been completed.

Description

Technical Field The present invention relates to a masterbatch of thermally expandable microcapsules with which an injection molded foam of a polycarbonate resin composition having a good appearance can be obtained, a polycarbonate resin composition, an injection molded foam, and a method for producing an injection molded foam. Background Art In foam injection molding of resins, many thermally degradable chemical blowing agents, such as sodium bicarbonate, are used. Moreover, thermally expandable microcapsules capable of expanding and foaming when heated are also used in foam injection molding of resins. Usually, from the viewpoint of dispersibility in a base material resin and workability, a masterbatch in which a thermoplastic resin or a thermoplastic elastomer contains a chemical blowing agent or thermally expandable microcapsules in an amount of 20 to 60 wt% is often used. For example, Patent Document 1 discloses a blowing agent masterbatch mainly composed of an ethylene/α-olefin copolymer and a thermally degradable blowing agent. Also, Patent Document 2 discloses a masterbatch that contains thermally expandable microcapsules, a carrier resin containing an olefin polymer, and a lubricant. For foam injection molding of resins, physical foaming may also be employed, which is a process of directly impregnating a molten resin in a cylinder of an injection molding machine with a supercritical fluid, such as carbon dioxide or nitrogen, and thereby foaming the resin. For example, Patent Document 3 discloses production of a molded foam by melt-kneading a resin composition having a sea-island structure in an injection forming machine, the resin composition being obtained by kneading a resin (A) that forms a sea phase and a resin (B) that forms an island layer, then injecting a supercritical fluid into the resin composition in a molten state, and thereby performing injection forming. Citation List Patent Documents Patent Document 1: JP 2013-142146APatent Document 2: JP 2017-082244APatent Document 3: JP 2015-151461A Disclosure of Invention Problem to be Solved by the Invention However, when the blowing agent masterbatch disclosed in Patent Document 1 is used to foam a polycarbonate resin, the thermally degradable blowing agent such as sodium bicarbonate generates water and a metal component during gas production, and therefore, there is a problem in that hydrolysis of the polycarbonate resin is promoted, and whitening due to low molecular weight molecules generated by the hydrolysis occurs on the surface of the injection molded foam, resulting in a poor appearance. When the masterbatch of thermally expandable microcapsules disclosed in Patent Document 2 is used to foam a polycarbonate resin, since the carrier resin contains the olefin polymer, there is a problem in that whitening caused by an olefin-based incompatible component occurs on the surface of the injection molded foam, resulting in a poor appearance. When a physical foaming process such as that disclosed in Patent Document 3 is used to foam a polycarbonate resin, there is a problem in that whitening caused by the impregnating gas occurs, resulting in a poor appearance. In order to address the above-described conventional problems, the present invention provides a masterbatch of thermally expandable microcapsules with which an injection molded foam of a polycarbonate resin composition in which the occurrence of whitening is suppressed and which has a good appearance can be obtained, a polycarbonate resin composition, an injection molded foam, and a method for producing an injection molded foam. Means for Solving Problem The present invention relates to a masterbatch (C) containing thermally expandable microcapsules (A) and a carrier resin composition (B), wherein the carrier resin composition (B) contains a carrier resin (B1) and a plasticizer (B2), the carrier resin (B1) being an acrylic resin having a weight average molecular weight of 8,000 or more and 350,000 or less and being a solid at 20°C, and the plasticizer (B2) being a liquid at 20°C and having a weight average molecular weight of 1,000 or more and 20,000 or less, and the carrier resin composition (B) is substantially compatible with a polycarbonate resin and has a shear viscosity of 1.0 Pa·s or more and 1.5 × 106 Pa·s or less at 80°C. The masterbatch (C) can be suitably used for a polycarbonate resin. The polycarbonate resin may further contain at least one other thermoplastic resin selected from the group consisting of a polyester resin, a polyester-polyether copolymer, an acrylonitrile-butadiene-styrene copolymer, an acrylonitrile-ethylene-propylene-diene-styrene copolymer, an acrylate-styrene-acrylonitrile copolymer, an acrylonitrile-styrene copolymer, a polyarylate resin, a polystyrene resin, and a polyamide resin. It is preferable that the plasticizer (B2) is an acrylic plasticizer. It is preferable that the carrier resin (B1) has a glass transition temperature (Tg) of -30°C or more and 1