Foam pipe fittings and piping structures

Abstract

To provide a foaming resin molding which is excellent in heat resistance and chemical resistance.SOLUTION: A foaming pipe joint 1 has a tubular main body part 10 having a flow passage therein, and one or more socket parts 20a, 20b which are formed at the main body part 10 integrally therewith. A peripheral edge of an opening part 12a of the main body part 10 functions as a stopper 13a, the main body part 10 has a foaming resin layer 30 and a non-foaming resin layer 50 covering the foaming resin layer 30, the foaming resin layer 30 includes a specified resin, a content of a rubber component of the foaming resin layer 30 acquired from a thermal decomposition gas chromatography mass spectrometry method (PGC / MS) is within a specified range, the non-foaming resin layer 50 includes a specified resin, a content of a rubber component of the non-foaming resin layer 50 acquired from the PGC / MS is within a specified range, and a ratio expressed by [a length L1 from a socket end part 22a of the socket part 20a up to the stopper 13a] / [a thickness d1 of the socket part 20a in the vicinity of the stopper 13a] is 3.5 or higher and 10 or lower.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a foamed resin molded product used for connecting drain pipes and the like. This application claims priority based on Japanese Patent Application No. 2017-189562, filed on September 29, 2017, the contents of which are incorporated herein by reference. [Background technology]

[0002] 2. Description of the Related Art Conventionally, it has been common to prevent condensation and the like around pipes made of steel pipes or synthetic resin pipes by covering the pipes with a heat insulating material such as glass wool. However, the conventional method requires wrapping or covering the pipes with heat-insulating material in addition to the piping work, which results in poor work efficiency and may make it impossible to carry out the work in a small work space. In response to this, resin pipes and pipe joints have been proposed that have a foamed resin layer that acts as a thermal insulation layer. By providing a thermal insulation layer, it becomes possible to prevent condensation without covering the pipe with a thermal insulation material after installation.

[0003] Patent Document 1 proposes a pipe joint with a thermal insulation layer, in which the inside of the main body is provided with a thermal insulation layer made of foamed resin, and the inner and outer walls of the main body surrounding this thermal insulation layer and the connection part are integrally molded by injection molding. Examples of resins that can be used for the pipe joint in Patent Document 1 include polyvinyl chloride, acrylonitrile-butadiene-styrene copolymer (ABS resin), polyethylene, polypropylene, etc., and current products use ABS resin, which has excellent impact resistance and heat resistance. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 3699579 Summary of the Invention [Problem to be solved by the invention]

[0005] ABS resin has excellent initial performance in terms of impact resistance and heat resistance, but poor chemical resistance. Therefore, if organic solvents or oils are present in the drain piping, the inner and outer walls of the body of the ABS resin fitting may deteriorate, causing a decrease in insulation. SUMMARY OF THE PRESENT EMBODIMENT An object of the present invention is to provide a foamed resin molded article having excellent heat insulating properties and chemical resistance. [Means for solving the problem]

[0006] As a result of extensive investigations, the present inventors have found that chemical resistance can be improved by reducing the content of rubber components such as butadiene contained in the ABS resin or the like that constitutes the foamed resin molded product. In addition, they discovered that by adding acrylic resin, the foamed resin molded product can be made transparent, making it easier to see the connection between the pipe and the pipe joint.

[0007] In order to solve the above problems, the present invention has the following aspects. [1] A tubular body having a flow passage therein, and one or more receiving ports formed integrally with the body, The periphery of the opening of the main body portion serves as a stopper, The main body portion has a foamed resin layer and a non-foamed resin layer covering the foamed resin layer, the foamed resin layer contains a rubber component and a resin which is a copolymer containing a vinyl cyanide monomer unit and an aromatic vinyl monomer unit, and the content of the rubber component in the foamed resin layer, as determined by pyrolysis gas chromatography mass spectrometry (PGC / MS), is 1 mass % or more and 30 mass % or less with respect to the total mass of the resin contained in the foamed resin layer; the non-foamed resin layer contains a rubber component and a resin which is a copolymer containing a vinyl cyanide monomer unit and an aromatic vinyl monomer unit, and the content of the rubber component in the non-foamed resin layer, as determined by pyrolysis gas chromatography mass spectrometry (PGC / MS), is 1 mass% or more and 30 mass% or less with respect to the total mass of the resin contained in the non-foamed resin layer; A foamed pipe joint, in which the ratio expressed as [length from the receiving end of the receiving portion to the stopper] / [thickness of the receiving portion in the vicinity of the stopper] is 3.5 or more and 10 or less. [2] A tubular body having a curved flow path therein, and one or more receiving ports formed integrally with the body, The periphery of the opening of the main body portion serves as a stopper, The main body portion has a foamed resin layer and a non-foamed resin layer covering the foamed resin layer, the foamed resin layer contains a rubber component and a resin which is a copolymer containing a vinyl cyanide monomer unit and an aromatic vinyl monomer unit, and the content of the rubber component in the foamed resin layer, as determined by pyrolysis gas chromatography mass spectrometry (PGC / MS), is 1 mass % or more and 30 mass % or less with respect to the total mass of the resin contained in the foamed resin layer; The non-foamed resin layer contains a resin which is a copolymer containing a rubber component and a vinyl cyanide monomer unit and an aromatic vinyl monomer unit, and the content of the rubber component in the non-foamed resin layer, as determined by pyrolysis gas chromatography mass spectrometry (PGC / MS), is 1 mass % or more and 30 mass % or less with respect to the total mass of the resin contained in the non-foamed resin layer. [3] A tubular body having a flow passage therein, and one or more receiving ports formed integrally with the body, The main body portion has a foamed resin layer and a non-foamed resin layer covering the foamed resin layer, the foamed resin layer contains a rubber component and a resin which is a copolymer containing a vinyl cyanide monomer unit and an aromatic vinyl monomer unit, and the content of the rubber component in the foamed resin layer, as determined by pyrolysis gas chromatography mass spectrometry (PGC / MS), is 1 mass % or more and 30 mass % or less with respect to the total mass of the resin contained in the foamed resin layer; A foamed pipe joint, wherein the resin constituting the non-foamed resin layer is the same as the resin constituting the foamed resin layer. [4] A foamed pipe joint according to any one of [1] to [3], which can be stretched 200 times or more before breaking in the following stretch fatigue test. [Stretch fatigue test] Two foam pipe joints are connected to a horizontally placed pipe, and one of the foam pipe joints is pulled vertically upwards while a stress F of 700 kg (6,865 N) is applied once per second. This is continued until one of the foam pipe joints breaks from expansion and contraction or until the stress F is applied 1,000 times, and the number of times that the stress F can be applied until the foam pipe joint breaks from expansion and contraction is measured. [5] A piping structure comprising: the foam pipe joint according to any one of [1] to [4]; and a pipe member with a foam layer that is inserted and connected to a receiving portion of the foam pipe joint. Effect of the Invention

[0008] The foamed resin molded article of the present invention has excellent heat insulating properties and chemical resistance. [Brief description of the drawings]

[0009] [Figure 1] 1 is a side view showing a foamed resin molded product according to one embodiment of the present invention. [Diagram 2] FIG. 2 is a vertical sectional view of the foamed resin molded product shown in FIG. [Diagram 3] FIG. 4 is a partial cross-sectional view showing a foamed resin molded product according to another embodiment of the present invention. [Figure 4] FIG. 1 is a side view showing a piping structure for an expansion and contraction fatigue test. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] [Polyfoam plastic moldings] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a foamed resin molded product according to an embodiment of the present invention will be described with reference to the drawings. As shown in Fig. 1, the foamed resin molded product 1 according to this embodiment is an example of a joint (an L-shaped pipe joint generally called an "elbow") used to connect a drain pipe. The foamed resin molded product 1 has a flow path that bends inside and includes a main body 10 having an opening 12a and an opening 12b at both ends. The foamed resin molded product 1 has a cylindrical receiving portion 20a that surrounds the periphery of the opening 12a of the main body 10, and a cylindrical receiving portion 20b that surrounds the periphery of the opening 12b of the main body 10. The main body 10, the receiving portion 20a, and the receiving portion 20b are integrally formed.

[0011] Fig. 2 is a vertical cross-sectional view of the foamed resin molded product 1 shown in Fig. 1. As shown in Fig. 2, the main body 10 includes a foamed resin layer 30 and a non-foamed resin layer 50. Both sides of the foamed resin layer 30 are covered with the non-foamed resin layer 50. The receiving portion 20a and the receiving portion 20b are formed of the non-foamed resin layer 50. A part of the foamed resin layer 30 is embedded in the non-foamed resin layer 50 of the receiving portion 20a. In addition, a part of the foamed resin layer 30 is embedded in the non-foamed resin layer 50 of the receiving portion 20b.

[0012] A stopper 13a is formed on the periphery of the opening 12a of the main body 10. The length from the socket end 22a of the socket 20a to the stopper 13a is L1. The thickness of the socket portion 20a near the stopper 13a is d1. The structure of the socket portion 20b is similar to the structure of the socket portion 20a.

[0013] The foamed resin molded article according to the embodiment of the present invention may be a joint (a three-way branched T-shaped pipe joint commonly called "tees"). 3, the foamed resin molded product 2 has a first tube axis O1 and a second tube axis O2. The two tube axes O1 and O2 are linear and intersect with each other at an angle of 90.0° to 91.1°. The foamed resin molded product 2 has a tubular main body 210 having a flow path (e.g., a drain flow path) therein, and three sockets 220a, 220b, and 220c formed integrally with an opening of the main body 210. The inner diameters of the three sockets 220a, 220b, and 220c are larger than the inner diameter of the main body 210 so that a tube member with a foam layer can be inserted and connected.

[0014] The foamed resin molded product 2 constitutes a tee member in which receiving portions 220a, 220b, 220c are provided at each of three openings, namely, at both ends 212a, 212b of a main body 210 forming a straight tube and at a branch end 212c that opens in the direction of the second tube axis O2. In the main body portion 210, an injection gate portion 214 is provided at a position facing the branch end portion 212c across the first tube axis O1, which is a position where injection is performed during molding. A stopper 213a is formed on the periphery of the open end 212a of the main body 210 and is connected to the inner circumferential surface of the main body 210. A stopper 213c is formed on the periphery of the branched end 212c of the main body 210.

[0015] The main body 210 includes a foamed resin layer 230 and a non-foamed resin layer 250. Both sides of the foamed resin layer 230 are covered with the non-foamed resin layer 250. The sockets 220a, 220b, and 220c are formed of the non-foamed resin layer 250.

[0016] The length from socket end 222a of socket 220a to open end 212a of body 210 is L2. Length L2 is equal to the length from socket end 222a to stopper 213a. Socket 220a has a thickness d2 near stopper 213a. Socket 220b has a structure similar to that of socket 220a. That is, the length from socket end 222b to open end 212b is L2. Furthermore, the length from socket end 222c of socket portion 220c to branch end 212c of body portion 210 is L3. Length L3 is equal to the length from socket end 222c to stopper 213c. Socket portion 220c has a thickness of d3 near stopper 213c.

[0017] <Foamed resin layer> The foamed resin layer 30 is formed by foaming and molding a foamable resin composition. The foamed resin molded article 1 of the present invention has the foamed resin layer 30 and is therefore excellent in heat insulation.

[0018] The expansion ratio of the foamed resin layer 30 is preferably 1.0 to 8.0 times, more preferably 1.1 to 5.0 times, and even more preferably 1.2 to 3.0 times. By setting the expansion ratio within the above range, high heat insulating performance can be imparted. The expansion ratio can be adjusted by the type or amount of resin, the type or amount of foaming agent, production conditions, and the like. The expansion ratio can be measured by the following method.

[0019] (Method of measuring foaming ratio) A test piece is prepared by cutting out a portion of 10 mm or more in the circumferential direction and 50 mm in the axial direction from the main body 10 of the foamed resin molded product 1, cutting the non-foamed resin layer 50 with a milling cutter, and processing only the foamed resin layer 30 into a plate of about 50 mm in length. Four test pieces are prepared by dividing the circumference into four equal parts at the center. In accordance with JIS K 7122, the apparent density of the test piece is measured to three decimal places using a water displacement specific gravity meter at 23°C ± 2°C, and the expansion ratio is calculated using the following formula (1). m = γc / γ (1) [In formula (1), m is the expansion ratio, γ is the apparent density of the foamed resin layer (g / cm 3 ) and γc is the density of the foamed resin layer when unfoamed (g / cm 3 The density of the foamed resin layer when it is not foamed can be measured by melting the foamed resin layer.

[0020] In the foamed resin layer 30, a plurality of bubbles are formed, the walls of the bubbles are substantially free of pores, and at least a portion of the bubbles are closed bubbles that do not communicate with each other. The closed bubble ratio is preferably 85% or more, and more preferably 90% or more. The upper limit is not particularly limited, but is substantially 99% or less. Within the above numerical range, low thermal conductivity can be maintained for a long period of time, and heat insulation is excellent. The closed cell ratio is measured in accordance with JIS K 7138:2006.

[0021] <Foamable resin composition> The foamable resin composition of the present embodiment contains a rubber component, a first resin which is a copolymer containing vinyl cyanide monomer units and aromatic vinyl monomer units, and a foaming agent. In this specification, the term "unit" refers to a structural portion derived from a monomer compound (monomer) before polymerization, for example, a "vinyl cyanide monomer unit" refers to a "structural portion derived from a vinyl cyanide monomer (acrylonitrile)." The content ratio of each monomer unit in a polymer corresponds to the content ratio of the monomer in the monomer mixture used in the production of the polymer. In addition, "(meth)acrylic" refers to either or both of "acrylic" and "methacrylic", and "acrylonitrile" refers to either or both of "acrylonitrile" and "methacrylonitrile".

[0022] (First Resin) The first resin is a copolymer containing a rubber component, a vinyl cyanide monomer unit, and an aromatic vinyl monomer unit. The copolymer containing a rubber component, a vinyl cyanide-based monomer unit, and an aromatic vinyl-based monomer unit is a resin obtained by polymerizing an aromatic vinyl-based monomer and a vinyl cyanide-based monomer in the presence of the rubber component. In this specification, the rubber component refers to a monomer component that is a raw material for diene rubbers such as polybutadiene and polyisoprene, or a raw material for acrylic rubber. Examples of the rubber component include, in the case of diene rubber, monomers of diene rubber such as butadiene, isoprene, ethylene, and propylene, or polymers thereof, and in the case of acrylic rubber, acrylic ester monomers such as ethyl acrylate, butyl acrylate, butoxyethyl acrylate, and methoxyethyl acrylate, or polymers thereof. Examples of the vinyl cyanide monomer include acrylonitrile and methacrylonitrile, with acrylonitrile being preferred. Examples of the aromatic vinyl monomer include styrene, α-methylstyrene, β-methylstyrene, 4-methylstyrene, β-bromostyrene, and the like, with styrene and α-methylstyrene being preferred. Specific examples of the first resin include acrylonitrile-butadiene-styrene copolymer (ABS resin), acrylonitrile-ethylene propylene diene-styrene copolymer (AES resin), acrylonitrile-acrylic rubber-styrene copolymer (AAS resin), etc., and further, a mixture of these may be used.

[0023] The content of the rubber component in the first resin is not particularly limited, and is preferably from 1 mass % to 30 mass % with respect to the total mass of the first resin.

[0024] The first resin preferably has a vinyl cyanide monomer unit content of 10% by mass or more and 50% by mass or less, more preferably 15% by mass or more and 45% by mass or less, based on the total mass of the first resin. When the vinyl cyanide monomer unit content is equal to or more than the lower limit, the tensile strength can be improved. When the vinyl cyanide monomer unit content is equal to or less than the upper limit, the impact strength can be improved.

[0025] The first resin preferably has an aromatic vinyl monomer unit content of 15% by mass or more and 60% by mass or less, more preferably 20% by mass or more and 50% by mass or less, based on the total mass of the first resin. When the aromatic vinyl monomer unit content is equal to or more than the lower limit, the indentation hardness can be improved. When the aromatic vinyl monomer unit content is equal to or less than the upper limit, the impact strength can be improved. The first resin may contain any monomer unit other than the vinyl cyanide monomer unit and the aromatic vinyl monomer unit, and examples thereof include a polycarbonate resin and its monomers.

[0026] The content of each component in the first resin is determined by analysis using pyrolysis gas chromatography mass spectrometry (PGC / MS). An example of measurement conditions using PGC / MS is shown below. [Measurement conditions] ·Device Pyrolysis apparatus: PY-2020iD (Frontier Labs). Gas chromatograph: GC 2010 (Shimadzu Corporation). Mass spectrometer: GCMS-QP 2010 (Shimadzu Corporation). Pyrolysis conditions Pyrolysis temperature: 550℃. Interface temperature: 250℃. Gas chromatographic conditions. Carrier flow rate: 1 ml / min (He). Split ratio: 100:1. Separation column: DB-1 (1.00 μm, 0.25 mm φ × 30 m). Oven temperature: 40℃(3min)-320℃(10min). ·Mass spectrometry conditions Interface temperature: 250℃. Ionization temperature: 220℃. Mass range: 28-700 m / z. Voltage: 1.2kV.

[0027] A method for calculating the content of each component in the first resin by PGC / MS measurement will be described. First, each component constituting the first resin is pyrolyzed and separated by pyrolysis gas chromatography, and a pyrolysis pattern (pyrogram) is obtained in which each component is recorded as a peak. Next, for each peak in the pyrolysis pattern, the acrylonitrile, rubber component, and styrene component are identified by a mass spectrum obtained by a mass spectrometer. Here, since the depolymerization rate (the rate at which a polymer decomposes into monomers) due to thermal decomposition differs for each component, acrylonitrile, rubber component, and styrene, the peak area (Z) of each component is calculated by dividing the area (X) of each peak in the pyrogram by the depolymerization rate (Y) of each component due to thermal decomposition. The depolymerization rates (Y) of each component are 0.15 for acrylonitrile, 0.10 for rubber component, and 1.0 for styrene. For example, when an acrylic resin such as polymethyl methacrylate is included as another resin, the depolymerization rate of the acrylic resin is 1.0. The ratio (Z / T) of the peak area (Z) of each component in the thermal decomposition pattern to the sum (T) is defined as the content (mass %) of each component in the first resin.

[0028] Table 1 shows an example of the content of each component obtained by PGC / MS measurement of acrylonitrile-butadiene-styrene copolymer (ABS resin) containing acrylic resin. In Table 1, "retention time" means the time at which each component is thermally decomposed and appears as a peak in the pyrogram. "Sample amount" is the mass of the ABS resin subjected to analysis.

[0029] [Table 1]

[0030] In the foamable resin composition, the content of the first resin relative to the total mass of the foamable resin composition is preferably from 45 to 90 mass%, more preferably from 50 to 85 mass%.

[0031] The foamable resin composition of the present embodiment may contain a resin other than the first resin. Examples of the other resins include acrylic resins such as polymethyl acrylate, polyethyl acrylate, polyglycidyl acrylate, polymethyl methacrylate, polyethyl methacrylate, and polyglycidyl methacrylate, polyvinyl resins, polyester resins, polyether resins, polyimide resins, etc. These may be used alone or in combination of two or more kinds.

[0032] In the foamable resin composition, the content of the first resin is preferably from 70 to 100% by mass, and more preferably from 85 to 100% by mass, based on the total mass of the resins in the foamable resin composition.

[0033] (foaming agent) As the foaming agent, either a volatile foaming agent or a decomposition type foaming agent may be used. Examples of the volatile blowing agent include aliphatic hydrocarbons, alicyclic hydrocarbons, halogenated hydrocarbons, ethers, ketones, etc. Among these, examples of the aliphatic hydrocarbons include propane, butane (normal butane, isobutane), pentane (normal pentane, isopentane, etc.), etc., and examples of the alicyclic hydrocarbons include cyclopentane, cyclohexane, etc. Examples of the halogenated hydrocarbons include one or more halogenated hydrocarbons such as trichlorofluoromethane, trichlorotrifluoroethane, tetrafluoroethane, chlorodifluoroethane, difluoroethane, etc. Furthermore, examples of the ethers include dimethyl ether, diethyl ether, etc., and examples of the ketones include acetone, methyl ethyl ketone, etc.

[0034] Examples of decomposition type foaming agents include inorganic foaming agents such as sodium bicarbonate (sodium hydrogen carbonate), sodium carbonate, ammonium bicarbonate, ammonium nitrite, azide compounds, and sodium borohydride, and organic foaming agents such as azodicarbonamide, barium azodicarboxylate, and dinitrosopentamethylenetetramine. Other gases such as carbon dioxide, nitrogen, and air may also be used as the foaming agent. From the viewpoint of excellent foaming performance, the decomposition type foaming agents are preferred, and among them, sodium bicarbonate and azodicarbonamide are more preferred. These may be used alone or in combination of two or more. The content of the foaming agent is preferably from 0.1 to 8 parts by mass, more preferably from 1 to 5 parts by mass, and even more preferably from 1 to 3 parts by mass, relative to 100 parts by mass of the first resin.

[0035] The foamable resin composition of the present invention may contain other components (optional components) in addition to the first resin and the foaming agent, as long as the effects of the present invention are not impaired.

[0036] The content of the optional component is preferably 50 parts by mass or less, more preferably 30 parts by mass or less, and even more preferably 20 parts by mass or less, based on 100 parts by mass of the first resin.

[0037] The foamable resin composition of the present invention can include a first resin, a foaming agent, and an optional component. The foamable resin composition may be a mixture in which all components are mixed in advance, or may be a form in which all or a part of all components are mixed in a molding machine. The mixture in which all components are mixed in advance may be in the form of a powder or pellets.

[0038] <Non-foamed resin layer> The non-foamed resin layer of the present embodiment is formed by molding a non-foamable resin composition. By having the non-foamed resin layer, the foamed resin molded article of the present invention can have an increased strength. The non-foamed resin layer covers the foamed resin layer.

[0039] <Non-foamable resin composition> The non-foamable resin composition of the present embodiment contains a rubber component and a second resin which is a copolymer containing vinyl cyanide monomer units and aromatic vinyl monomer units.

[0040] (Second Resin) The second resin is a copolymer containing a rubber component, a vinyl cyanide monomer unit, and an aromatic vinyl monomer unit. The second resin may be the same as the first resin or may be different.

[0041] The second resin has a rubber component content of 1% by mass or more and 30% by mass or less, preferably 1% by mass or more and 25% by mass or less, more preferably 3% by mass or more and 20% by mass or less, even more preferably 5% by mass or more and 15% by mass or less, and particularly preferably 5% by mass or more and 10% by mass or less, based on the total mass of the second resin. When the rubber component content is equal to or more than the lower limit, the strength of the foamed resin molded product is easily increased. When the rubber component content is equal to or less than the upper limit, the chemical resistance is easily improved.

[0042] The second resin preferably has a vinyl cyanide monomer unit content of 10% by mass or more and 50% by mass or less, more preferably 15% by mass or more and 45% by mass or less, based on the total mass of the second resin. When the vinyl cyanide monomer unit content is equal to or more than the lower limit, the tensile strength can be improved. When the vinyl cyanide monomer unit content is equal to or less than the upper limit, the impact strength can be improved.

[0043] The content of the aromatic vinyl monomer unit in the second resin is preferably 15% by mass or more and 60% by mass or less, more preferably 20% by mass or more and 50% by mass or less, based on the total mass of the second resin. When the content of the aromatic vinyl monomer unit is equal to or more than the lower limit, the indentation hardness can be improved. When the content of the aromatic vinyl monomer unit is equal to or less than the upper limit, the impact strength can be improved.

[0044] The content of each component in the second resin is determined by pyrolysis gas chromatography mass spectrometry (PGC / MS) under the same measurement conditions as those for the first resin.

[0045] In the non-foamable resin composition, the content of the second resin relative to the total mass of the non-foamable resin composition is preferably from 45 to 90 mass %, more preferably from 50 to 85 mass %.

[0046] The non-foamable resin composition of the present embodiment may contain a resin other than the second resin. Examples of the other resins include polyvinyl resins, polyester resins, polyether resins, acrylic resins, polyimide resins, etc. These may be used alone or in combination of two or more kinds.

[0047] The non-foamable resin composition of the present embodiment preferably further contains an acrylic resin. Examples of the acrylic resin include polymers of acrylic acid esters and polymers of methacrylic acid esters. Examples of the polymers of acrylic acid esters include polymethyl acrylate, polyethyl acrylate, and polyglycidyl acrylate. Examples of the polymers of methacrylic acid esters include polymethyl methacrylate, polyethyl methacrylate, and polyglycidyl methacrylate. The content of the acrylic resin is preferably 20% by mass or more and 60% by mass or less, more preferably 30% by mass or more and 50% by mass or less, based on the total mass of the resin in the non-foamable resin composition. When the content of the acrylic resin is within the above numerical range, the strength and transparency of the foamed resin molded product can be easily increased. The content of the acrylic resin is preferably from 10% by mass to 55% by mass, and more preferably from 20% by mass to 50% by mass, based on the total mass of the non-foamable resin composition.

[0048] The content of each component in the non-foamable resin composition containing the second resin and other resins is determined by analysis using pyrolysis gas chromatography mass spectrometry (PGC / MS). The measurement conditions can be the same as those for the first resin. The content of each component in the second resin can be calculated using the same calculation method as the content of each component in the first resin. The depolymerization rates of acrylonitrile, rubber component, styrene, and acrylic resin are 0.15 for acrylonitrile, 0.10 for rubber component, 1.0 for styrene, and 1.0 for acrylic resin.

[0049] In the non-foamable resin composition, the content of the second resin is preferably 40 mass% or more and 100 mass% or less, more preferably 45 mass% or more and 100 mass% or less, and even more preferably 50 mass% or more and 100 mass% or less, based on the total mass of the resins in the non-foamable resin composition.

[0050] The non-foamable resin composition of the present embodiment may contain other components (optional components) in addition to the second resin, as long as the effects of the present invention are not impaired. Optional components include colorants, flame retardants, antioxidants, ultraviolet absorbers, and light stabilizers.

[0051] The content of the optional component is preferably 50 parts by mass or less, more preferably 30 parts by mass or less, and even more preferably 20 parts by mass or less, based on 100 parts by mass of the second resin. The non-foamed resin layer does not need to contain the foaming agent, but may contain the foaming agent. The amount of the foaming agent contained in the non-foamed resin layer is preferably 0 parts by mass or more and 8 parts by mass or less, more preferably 0 parts by mass or more and 5 parts by mass or less, and even more preferably 0 parts by mass or more and 3 parts by mass or less, relative to 100 parts by mass of the second resin. The expansion ratio in the non-foamed resin layer is preferably 0 times, but low expansion ratios of 1.5 times or less are not excluded from the present invention.

[0052] The non-foamable resin composition of the present embodiment may contain a second resin and an optional component. The non-foamable resin composition may be a mixture in which all components are mixed in advance, or may be a form in which all or a part of all components are mixed in a molding machine. The mixture in which all components are mixed in advance may be in the form of a powder or pellets. The non-foamable resin composition of the present embodiment forms a non-foamable resin layer and covers the outer surface of the foamed resin molded article of the present invention. In addition, the non-foamable resin composition of the present embodiment has a rubber component content of 1% by mass or more and 30% by mass or less with respect to the total mass of the second resin. Therefore, the non-foamable resin layer has excellent chemical resistance, and the foamed resin molded article of the present invention has excellent chemical resistance.

[0053] <Method of manufacturing foamed resin molded products> The foamed resin molded product is produced by injection molding or extrusion molding. For example, a foamable resin composition is heated and melted, injected into a mold, heated at a desired temperature for a desired time, and cooled at a desired temperature for a desired time to obtain a foamed resin molded product having a desired expansion ratio. In the case of extrusion molding, the foamable resin composition is heated and melted, injected from an extruder into a mold, and heated at a desired temperature for a desired time to foam and mold the foamable resin composition. After cooling at a desired temperature for a desired time, the composition is cut to a desired length to obtain a foamed resin molded product having a desired expansion ratio.

[0054] In an injection molding machine, the temperature of the foamable resin composition immediately before being injected into a mold (molding temperature) is preferably from 200° C. to 280° C., more preferably from 220° C. to 260° C. When the molding temperature is within the above range, thermal decomposition of the thermoplastic resin is suppressed to prevent a decrease in transparency, and the foamable resin composition is sufficiently melted to obtain good flowability. The time for molding in a mold is preferably from 1 minute to 10 minutes. If it is equal to or more than the lower limit, sufficient curing can be achieved, and if it is equal to or less than the upper limit, the productivity of foamed resin molded products can be easily improved.

[0055] The foamed resin molded product of the present invention has been described in detail above, but the present invention is not limited to the above-described embodiment and can be modified as appropriate without departing from the spirit of the present invention. For example, the foamed resin molded product may have only a foamed resin layer without a non-foamed resin layer. In that case, the foamed resin layer may have a rubber component content of 1% by mass or more and 30% by mass or less with respect to the total mass of the first resin. When the foamed resin molded product is formed only with a foamed resin layer, the outer surface of the foamed resin layer may form a high-density layer similar to the non-foamed resin layer.

[0056] The foamed resin molded article of the present invention may be a multi-layer molded article having a foamed resin layer, and may further include a different resin layer. Examples of the other resin layer include a non-foamed resin layer, a foamed resin layer that is the same as the outer surface, and a foamed resin layer that is different from the outer surface. The resins that are the raw materials for these resin layers may be the same thermoplastic resin as the foamed resin layer that forms the outer surface, or may be different thermoplastic resins. From the viewpoint of suppressing peeling between the resin layers, it is preferable that the resins that are the raw materials for these resin layers are the same thermoplastic resin as the foamed resin layer that forms the outer surface.

[0057] When the foamed resin molded product is a foamed pipe fitting (elbow) as shown in FIG. 2, the ratio of length L1 from receiving end 22a of receiving portion 20a to stopper 13a to thickness d1 of receiving portion 20a in the vicinity of stopper 13a (hereinafter also referred to as "L1 / d1 ratio") is preferably 3.5 or more and 10 or less, more preferably 4.0 or more and 9.0 or less, and even more preferably 4.5 or more and 8.0 or less. When the L1 / d1 ratio is equal to or greater than the lower limit, the foamed resin layer 30 is easily prevented from penetrating the receiving portion 20a, and the strength of the receiving portion 20a is easily prevented from decreasing. Therefore, the foamed pipe joint is less likely to be broken due to expansion and contraction fatigue caused by expansion and contraction. In addition, when the L1 / d1 ratio is equal to or greater than the lower limit, the length L1 of the receiving portion 20a is sufficiently long, and water leakage due to insufficient insertion of a pipe or the like into the foamed pipe joint is easily prevented. When the L1 / d1 ratio is equal to or less than the upper limit, the thickness d1 is sufficiently large, and the foamed pipe joint is less likely to break due to expansion and contraction fatigue. In addition, when the L1 / d1 ratio is equal to or less than the upper limit, the length L1 is not too long, and it is easy to prevent the stress due to expansion and contraction from concentrating at the base of the receiving portion 20a, and the foamed pipe joint is less likely to break due to expansion and contraction fatigue. The L1 / d1 ratio is also the same for the receiving portion 20b of the foamed resin molded product 1.

[0058] When the foamed resin molded product is a foamed pipe fitting (tee) as shown in Figure 3, the ratio of the length L2 from the receiving end 222a of the receiving portion 220a to the stopper 213a to the thickness d2 of the receiving portion 220a near the stopper 213a (hereinafter also referred to as the "L2 / d2 ratio") is the same as the L1 / d1 ratio described above. The L2 / d2 ratio is also the same in the receiving portion 220b of the foamed resin molded product 2. Furthermore, the ratio of length L3 from socket end 222c of socket portion 220c to stopper 213c to thickness d3 of socket portion 220c near stopper 213c is the same as the above-mentioned L1 / d1 ratio.

[0059] The foamed resin molded product of the present invention is not limited to the above-described embodiment, and may be a foamed pipe joint having another shape, such as a nipple or a valve socket. Furthermore, the foamed resin molded product is not limited to a foamed pipe joint, but may be a foamed resin cover manufactured by injection molding, a foamed resin pipe manufactured by extrusion molding, or the like.

[0060] As described above, the foamed resin molded product of the present invention has a foamed resin layer and therefore has excellent heat insulation properties. In addition, the foamed resin molded product of the present invention has a smaller content of rubber components in the outer surface than ordinary ABS resins or ordinary AES resins. Therefore, the foamed resin molded product of the present invention has excellent chemical resistance. EXAMPLES

[0061] Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. The raw materials and evaluation methods used in each of the examples and comparative examples are as follows.

[0062] [Raw materials used] <First Resin> ABS resin (butadiene content 15% by mass). <Second resin> ABS resin (ABS resin having the composition shown in Tables 2 to 3). <Other resins> Acrylic resin (polymethyl methacrylate). <Foaming agent> ADCA (manufactured by Otsuka Chemical Co., Ltd., product name "AZ-HM", azodicarbonamide).

[0063] [Examples 1 to 6] A resin composition obtained by kneading polymethyl methacrylate into ABS resin was used as a non-foamable resin composition. At this time, the non-foamable resin composition was kneaded at such a ratio that the peak area ratio of each component obtained by measuring the non-foamable resin composition by PGC was as shown in Table 2. This non-foamable resin composition was mixed with azodicarbonamide as a foaming agent to obtain a foamable resin composition, which was injection molded to produce a DV joint type elbow with an inner diameter of 30 mm as shown in FIG. 2, which has a solid receiving portion made of a non-foamed resin layer, a thickness between the inner and outer wall surfaces of the receiving portion of 3 mm, a length of the receiving portion of 23 mm, a thickness between the inner and outer walls of the main body of 8 mm, and a foamed resin layer with a foaming ratio of 2.0 times. However, Examples 4 and 5 are reference examples.

[0064] [Example 7] An elbow was manufactured in the same manner as in Example 6, except that the length of the socket was 13 mm.

[0065] [Example 8] An elbow was manufactured in the same manner as in Example 1, except that the thickness between the inner and outer wall surfaces of the socket portion was 3.2 mm and the length of the socket portion was 30 mm.

[0066] [Example 9] An elbow was produced in the same manner as in Example 1, except that the non-foamable resin composition was kneaded in such a ratio that the peak area ratio of each component obtained by PGC measurement was as shown in Table 3.

[0067] [Example 10] An elbow was manufactured in the same manner as in Example 1, except that the thickness between the inner and outer wall surfaces of the socket portion was 2.6 mm and the length of the socket portion was 30 mm.

[0068] [Example 11] An elbow was manufactured in the same manner as in Example 6, except that the thickness between the inner and outer wall surfaces of the socket portion was 5.5 mm and the length of the socket portion was 18 mm.

[0069] [Comparative Examples 1 and 2] An elbow was produced in the same manner as in Example 1, except that the ABS resin and polymethyl methacrylate were kneaded in such a ratio that the peak area ratio of each component obtained by measuring the non-foamable resin composition with PGC was as shown in Table 3.

[0070] [Evaluation of chemical resistance] For each of the elbows obtained in the above examples and comparative examples, the receiving portion was cut into a dumbbell shape in the pipe axial direction to obtain a test piece. The obtained test piece was fixed to a bending jig prepared so that an expansion and contraction stress of 3 MPa was applied in a room at 23°C, and a cotton of 10 mm x 20 mm size soaked in 2 mL of polyethylene glycol was placed on the center of the test piece. Three test pieces were prepared for each example, and one of the three test pieces was left for 36 hours, after which the cotton was removed and visually confirmed. The other two of the three test pieces were left for 72 hours, after which the cotton was removed and visually confirmed to evaluate the chemical resistance. The chemical resistance was evaluated by the presence or absence of cracks in the test piece according to the following evaluation criteria. The results are shown in Tables 2 to 3. (Evaluation Criteria) ◯: No breakage or cracks occurred even after 72 hours. △: Fracture or cracks occurred after being left for 1 hour or more but less than 72 hours. ×: Breakage or cracking occurred within 1 hour of placement.

[0071] [Evaluation of stretch fatigue resistance] As shown in FIG. 4, using a hydraulic fatigue tester (Shimadzu Corporation, serial type fatigue tester EHF-ED10-70L) 300, the manufactured elbow 3 was connected to the pipe 40 and fixed to the fixing jig 60 and the fixing jig 62. A stress F of 700 kg (6865 N) was applied once per second to the elbow 3, pulling it vertically upward, to perform a stretching fatigue test. The stretching fatigue test was performed until the elbow 3 broke by stretching or until the stress F was applied 1000 times, and the number of times the stress F was applied until the elbow 3 broke by stretching was measured. The elbow 3 had the same shape as the foamed resin molded product 1 shown in FIGS. 1 and 2. The stretching fatigue resistance was evaluated according to the following evaluation criteria. The results are shown in Tables 2 to 3. (Evaluation Criteria) ○: More than 1000 times. △: More than 200 times but less than 1000 times. ×: Less than 200 times.

[0072] [Table 2]

[0073] [Table 3]

[0074] As shown in Tables 2 and 3, Examples 1 to 4 to which the present invention was applied were evaluated as having excellent chemical resistance, with a rating of "○." In addition, the results of the stretch fatigue test showed that the materials had sufficient strength against stretching. It was found that Examples 5 to 7 and 9, in which the content of the rubber component (butadiene) in the non-foamed resin layer was 15% by mass or more, were inferior to Examples 1 to 4, but had chemical resistance and strength. It was found that Example 8, in which the length of the socket portion is long, is inferior to Examples 1 to 4, but has a certain degree of strength. In Examples 10 and 11, the content of the rubber component (butadiene) in the non-foamed resin layer was 30 mass% or less, so the chemical resistance was sufficient. However, the L1 / d1 ratio was outside the above-mentioned preferred range, so the stretch fatigue resistance was poor. On the other hand, Comparative Examples 1 and 2, in which the rubber component content was outside the range of the present invention, were inferior in chemical resistance.

[0075] It was found that the foamed resin molded article of the present invention has excellent heat insulating properties and chemical resistance. [Explanation of symbols]

[0076] 1, 2 Foam resin molding 3 Elbow 10, 210 Main body 12a, 12b opening 13a, 213a, 213c stopper 20a, 20b, 220a, 220b, 220c socket 22a, 222a, 222b, 222c socket end 212a, 212b open end 212c Branch end 30, 230 Foam resin layer 50, 250 Non-foamed resin layer 40 Pipe 60, 62 Fixture 300 Hydraulic Fatigue Testing Machine

Claims

1. a tubular body having an internal flow passage and one or more receiving ports integrally formed with the body, The periphery of the opening of the main body portion serves as a stopper, The main body portion has a foamed resin layer foamed with a foaming agent and a non-foamed resin layer covering the foamed resin layer, the foamed resin layer includes a rubber component, a resin which is a copolymer including a vinyl cyanide monomer unit and an aromatic vinyl monomer unit, and an acrylic resin, and the content of the rubber component in the foamed resin layer, which is determined by pyrolysis gas chromatography mass spectrometry (PGC / MS), is 1 mass% or more and 26 mass% or less with respect to the total mass of the resins included in the foamed resin layer, The foamed resin layer has an acrylic resin content of 20% by mass or more and 50% by mass or less, based on the total mass of resins contained in the foamed resin layer, as determined by pyrolysis gas chromatography mass spectrometry (PGC / MS); the non-foamed resin layer includes a resin which is a copolymer including a rubber component, a vinyl cyanide monomer unit, and an aromatic vinyl monomer unit, and an acrylic resin, and the content of the rubber component in the non-foamed resin layer, which is determined by pyrolysis gas chromatography mass spectrometry (PGC / MS), is 1 mass% or more and 26 mass% or less with respect to the total mass of the resins included in the non-foamed resin layer, the non-foamed resin layer has an acrylic resin content of 20% by mass or more and 50% by mass or less, based on the total mass of resins contained in the non-foamed resin layer, as determined by pyrolysis gas chromatography mass spectrometry (PGC / MS); A foamed pipe joint, in which the ratio represented by [length from the receiving end of the receiving portion to the stopper] / [thickness of the receiving portion in the vicinity of the stopper] is 3.5 or more and 10 or less.

2. A tubular body having an internally curved flow passage and one or more receiving ports integrally formed with the body, The periphery of the opening of the main body portion serves as a stopper, The main body portion has a foamed resin layer foamed with a foaming agent and a non-foamed resin layer covering the foamed resin layer, the foamed resin layer includes a rubber component, a resin which is a copolymer including a vinyl cyanide monomer unit and an aromatic vinyl monomer unit, and an acrylic resin, and the content of the rubber component in the foamed resin layer, which is determined by pyrolysis gas chromatography mass spectrometry (PGC / MS), is 1 mass% or more and 26 mass% or less with respect to the total mass of the resins included in the foamed resin layer, The foamed resin layer has an acrylic resin content of 20% by mass or more and 50% by mass or less, based on the total mass of resins contained in the foamed resin layer, as determined by pyrolysis gas chromatography mass spectrometry (PGC / MS); the non-foamed resin layer contains a resin which is a copolymer containing a rubber component and a vinyl cyanide monomer unit and an aromatic vinyl monomer unit, and the content of the rubber component in the non-foamed resin layer, as determined by pyrolysis gas chromatography mass spectrometry (PGC / MS), is 1 mass% or more and 26 mass% or less with respect to the total mass of the resin contained in the non-foamed resin layer; A foamed pipe joint, wherein the content of the acrylic resin in the non-foamed resin layer, as determined by pyrolysis gas chromatography mass spectrometry (PGC / MS), is 20 mass% or more and 50 mass% or less relative to the total mass of the resin contained in the non-foamed resin layer.

3. a tubular body having an internal flow passage and one or more receiving ports integrally formed with the body, The main body portion has a foamed resin layer foamed with a foaming agent and a non-foamed resin layer covering the foamed resin layer, the foamed resin layer includes a rubber component, a resin which is a copolymer including a vinyl cyanide monomer unit and an aromatic vinyl monomer unit, and an acrylic resin, and the content of the rubber component in the foamed resin layer, which is determined by pyrolysis gas chromatography mass spectrometry (PGC / MS), is 1 mass% or more and 26 mass% or less with respect to the total mass of the resins included in the foamed resin layer, The foamed resin layer has an acrylic resin content of 20% by mass or more and 50% by mass or less, based on the total mass of resins contained in the foamed resin layer, as determined by pyrolysis gas chromatography mass spectrometry (PGC / MS); A foamed pipe joint, wherein the resin constituting the non-foamed resin layer is the same as the resin constituting the foamed resin layer.

4. A piping structure comprising: the foam pipe joint according to any one of claims 1 to 3; and a pipe member with a foam layer that is inserted and connected to a receiving portion of the foam pipe joint.

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