JP7410759B2 - multilayer pipe - Google Patents

Description

The present invention relates to multilayer pipes.

A multilayer pipe made of resin is used as an air conditioning drain pipe. Air conditioning drain pipes are required to have high thermal insulation properties. Air conditioning drain pipes with a foam layer are sometimes used to increase insulation.

Patent Document 1 below describes a cylindrical foam layer containing a vinyl chloride resin, a non-foamed inner layer provided on the inner surface of the foam layer and containing a vinyl chloride resin, and a non-foamed inner layer provided on the outer surface of the foam layer, An air conditioning drain pipe is disclosed that includes a non-foamed outer layer comprising a vinyl chloride resin. In this air conditioning drain pipe, the foam layer has a foaming ratio of 3.5 times or more and 10 times or less, a closed cell ratio of the foam layer is 45% or more, and the foam layer and the non-foam inner layer are fused. The adhesion strength is 1.5 MPa or more.

JP2018-059707A

As described in Patent Document 1, an air conditioning drain pipe is known that includes a foam layer and a non-foam layer and has a multilayer structure. In a conventional air conditioning drain pipe, the shapes of the outer peripheral edge and inner peripheral edge of all layers are perfectly circular in cross section along the radial direction.

There are almost no situations in which the inside of an air conditioning drain pipe is filled with liquid. Therefore, dew condensation hardly occurs on the upper outer surface of the air conditioning drain pipe. On the other hand, condensation is likely to occur on the lower outer surface of the air conditioning drain pipe due to the temperature difference between the liquid flowing inside and the outside air. In particular, if the air conditioner drain pipe is installed in a place or region with high outside temperature, or if the outside temperature increases due to abnormal weather, the temperature difference between the liquid flowing inside the pipe and the outside air will become large, causing the air conditioner drain to drain. Condensation is more likely to occur on the outer surface of the lower side of the pipe.

In addition, when attempting to simply increase the thickness of the air conditioning drain pipe in order to prevent the occurrence of dew condensation, the amount of resin used increases, which reduces moldability and tends to cause the resin to stagnate in the mold. In this case, resin burned due to thermal history gets mixed into the air conditioning drain pipe, causing cracks and reducing impact performance.

An object of the present invention is to provide a multilayer pipe that does not reduce impact performance and can suppress the occurrence of dew condensation.

According to a broad aspect of the present invention, the invention comprises an inner layer, a foam layer disposed outside the inner layer, and an outer layer disposed outside the foam layer, and a cross section of the foam layer along the radial direction of the multilayer pipe. A multilayer pipe is provided, in which the shape of the outer peripheral edge is oval, the thickness of the foam layer is partially different, and the maximum thickness of the foam layer is 3.0 mm or more and 9.0 mm or less.

In a particular aspect of the multilayer pipe according to the present invention, the thickness of the multilayer pipe at the maximum thickness position of the foam layer is _T0 , and the maximum thickness position of the foam layer is the 0 o'clock position, and the axis of the outer layer is When the thickness of the multilayer tube in the 3 o'clock direction is T ₃ , the thickness of the multilayer tube in the 6 o'clock direction is T ₆ , and the thickness of the multilayer tube in the 9 o'clock direction is T ₉ , T ₀ /T ₃ , T ₀ /T ₆ and T ₀ / T ₉ are each 1.5 or more and 4.0 or less.

In a particular aspect of the multilayer pipe according to the present invention, the foam layer includes a vinyl chloride resin.

In a particular aspect of the multilayer pipe according to the present invention, the multilayer pipe is installed and used with the maximum thickness portion of the foam layer located at the bottom.

In a specific aspect of the multilayer pipe according to the present invention, the multilayer pipe is an air conditioning drain pipe.

The multilayer pipe according to the present invention includes an inner layer, a foam layer disposed outside the inner layer, and an outer layer disposed outside the foam layer, and has a cross section of the foam layer along the radial direction of the multilayer pipe. The shape of the outer periphery is oval, the thickness of the foam layer is partially different, and the maximum thickness of the foam layer is 3.0 mm or more and 9.0 mm or less. Since the multilayer tube according to the present invention has the above-mentioned configuration, it is possible to suppress the occurrence of dew condensation without reducing the impact performance.

FIG. 1 is a cross-sectional view schematically showing a multilayer pipe according to an embodiment of the present invention. FIG. 2 is a plan view schematically showing a manufacturing apparatus used for manufacturing a multilayer pipe according to an embodiment of the present invention. FIG. 3 is a front view schematically showing a manufacturing apparatus used for manufacturing a multilayer pipe according to an embodiment of the present invention. FIG. 4 is an enlarged sectional view showing a mold part and a tube outer surface forming tube part in the manufacturing apparatus. FIG. 5 is a diagram schematically showing the experimental apparatus used in the evaluation of dew condensation in the example.

The present invention will be explained in detail below.

The multilayer pipe according to the present invention includes an inner layer, a foam layer disposed outside the inner layer, and an outer layer disposed outside the foam layer, and has a cross section of the foam layer along the radial direction of the multilayer pipe. The shape of the outer periphery is oval, the thickness of the foam layer is partially different, and the maximum thickness of the foam layer is 3.0 mm or more and 9.0 mm or less.

Since the multilayer tube according to the present invention has the above-mentioned configuration, it is possible to suppress the occurrence of dew condensation without reducing the impact performance. The multilayer pipe according to the present invention is suitably used as an air conditioning drain pipe. The multilayer pipe according to the present invention is preferably an air conditioning drain pipe.

When the multilayer pipe according to the present invention is used as an air conditioning drain pipe, it is preferable that the multilayer pipe is installed and used with the maximum thickness portion of the foam layer located on the lower side. The maximum thickness portion of the foam layer is preferably the maximum thickness portion of the multilayer pipe (air conditioning drain pipe). Therefore, it is preferable that the multilayer pipe (air conditioning drain pipe) is installed and used with the maximum thickness part located at the bottom. By installing and using it in this manner, it is possible to suppress the occurrence of dew condensation at the bottom of the air conditioning drain pipe due to the temperature difference between the liquid flowing inside and the outside air. Therefore, for example, it is possible to prevent condensed water droplets from dripping down and causing stains on the surrounding floor, walls, etc. Note that the multilayer pipe does not need to be installed and used with the maximum thickness portion of the foam layer located at the bottom. For example, the multilayer pipe may be installed perpendicular to the ground.

If the overall thickness of the multilayer tube is simply increased, the amount of resin increases, which tends to reduce moldability and impact performance of the resulting multilayer tube. In addition, the fluidity of the resin within the mold decreases, and the resin decomposes due to heat during molding, which may cause discoloration on the plated surface of the mold. In contrast, in the present invention, instead of increasing the overall thickness of the multilayer pipe, the foam layer has a specific shape, so that the foam layer and the multilayer pipe have thicker parts and thinner parts. has been established. In the present invention, since there is no need to increase the amount of resin, good molding can be achieved, and as a result, the impact performance of the multilayer pipe can be maintained at a high level. Moreover, the occurrence of discoloration of the mold can be effectively suppressed.

Moreover, in the multilayer pipe according to the present invention, the heat insulation properties can be improved.

The multilayer pipe includes an inner layer, a foam layer, and an outer layer in this order from the center toward the outside. The multilayer pipe may have a three-layer structure including an inner layer, a foam layer, and an outer layer, or may have a four-layer structure or more. The inner layer may or may not be the innermost layer. Other layers may be arranged inside the inner layer. However, the inner layer is preferably the innermost layer. The outer layer may or may not be the outermost layer. Other layers may be arranged outside the outer layer. However, the outer layer is preferably the outermost layer. Another layer may be arranged between the inner layer and the foam layer or between the outer layer and the foam layer. However, it is preferable that no other layer is disposed between the inner layer and the foam layer and between the outer layer and the foam layer.

Hereinafter, specific embodiments of the present invention will be described with reference to the drawings. In addition, in the following drawings, the size, thickness, shape, etc. may differ from the actual size, thickness, shape, etc. for convenience of illustration.

FIG. 1 is a cross-sectional view schematically showing a multilayer pipe according to an embodiment of the present invention. FIG. 1 shows a radial cross-sectional view of a multilayer tube.

The multilayer pipe 10 shown in FIG. 1 includes an inner layer 1, a foam layer 2, and an outer layer 3. The multilayer tube 10 has a three-layer structure. A foam layer 2 is arranged outside the inner layer 1. An outer layer 3 is arranged outside the foam layer 2. The foam layer 2 is arranged on the outer surface of the inner layer 1 and is laminated. The outer layer 3 is arranged on the outer surface of the foam layer 2 and is laminated. Inner layer 1 is the innermost layer and the surface layer. Foam layer 2 is an intermediate layer. The outer layer 3 is the outermost layer and a surface layer. Inner layer 1, foam layer 2, and outer layer 3 are each tubular.

The shape of the outer peripheral edge and the shape of the inner peripheral edge of the cross section of the inner layer 1 along the radial direction of the multilayer pipe 10 are each a perfect circle. The shape of the outer circumferential edge of the cross section of the outer layer 3 along the radial direction of the multilayer tube 10 is a perfect circle, and the shape of the inner circumferential edge is a shape that follows the foam layer 2, specifically, an oval shape. The outer peripheral edge of the cross section of the foam layer 2 along the radial direction of the multilayer tube 10 has an oval shape, and the inner peripheral edge has a perfect circular shape. The oval-shaped periphery extends smoothly over the entire circumference without any steps. The axis of the inner layer 1 and the axis of the foam layer 2 do not coincide. The axis of the outer layer 3 and the axis of the foam layer 2 do not coincide.

The thickness of the foam layer 2 differs partially. The thickness of the foam layer 2 is not uniform. The foam layer 2 has a thicker portion and a thinner portion. Therefore, in the foamed layer 2, the thickness of the portion having the maximum thickness is different from the thickness of the other portion.

The thickness of the outer layer 3 differs partially. The thickness of the outer layer 3 is not uniform. The outer layer 3 has a thicker portion and a thinner portion.

Since the shape of the outer periphery of the cross section of the outer layer 3 is a perfect circle, it is possible to easily connect the multilayer pipe with a commercially available joint, and the thickness of the foam layer is thick at the position where the liquid flows. This allows the insulation to be improved.

The maximum thickness of the foam layer 2 is 3.0 mm or more and 9.0 mm or less. The maximum thickness of the foam layer 2 is preferably 4.5 mm or more, more preferably 6.0 mm or more, and preferably 8.0 mm or less. When the maximum thickness of the foamed layer 2 is equal to or greater than the lower limit, the heat of the liquid flowing inside becomes difficult to be transmitted to the outer layer 3, and the occurrence of dew condensation can be effectively suppressed. When the maximum thickness of the foam layer 2 is below the above upper limit, the impact resistance of the multilayer pipe can be improved. If the maximum thickness of the foamed layer 2 exceeds 9.0 mm, the amount of resin extruded during molding will increase, which will increase the load on the motor of the molding machine and reduce moldability.

Let the thickness of the multilayer pipe 10 at the maximum thickness position of the foam layer 2 be _T0 , and let the maximum thickness position of the foam layer 2 be the 0 o'clock position. Centering on the axis O of the outer layer 3, the thickness of the multilayer tube 10 in the 3 o'clock direction is T ₃ , the thickness of the multilayer tube 10 in the 6 o'clock direction is T ₆ , and the thickness of the multilayer tube 10 in the 9 o'clock direction is T ₉ .

T ₀ /T ₃ (ratio of T ₀ to T ₃ ) is preferably 1.5 or more, more preferably 2.0 or more, preferably 4.0 or less, and more preferably 3.5 or less. When the above T ₀ /T ₃ is greater than or equal to the above lower limit and less than or equal to the above upper limit, generation of dew condensation can be effectively suppressed. When the above-mentioned T ₀ /T ₃ is equal to or greater than the above-mentioned lower limit, the heat insulation properties can be further improved. When the above-mentioned T ₀ /T ₃ is below the above-mentioned upper limit, the moldability can be improved and the impact resistance of the multilayer pipe can be improved.

T ₀ /T ₆ (ratio of T ₀ to T ₆ ) is preferably 1.5 or more, more preferably 2.0 or more, preferably 4.0 or less, and more preferably 3.5 or less. When the above-mentioned T ₀ /T ₆ is above the above-mentioned lower limit and below the above-mentioned upper limit, generation of dew condensation can be effectively suppressed. When the above-mentioned T ₀ /T ₆ is equal to or greater than the above-mentioned lower limit, the heat insulation properties can be further improved. When the above-mentioned T ₀ /T ₆ is below the above-mentioned upper limit, the moldability can be improved and the impact resistance of the multilayer pipe can be improved.

T ₀ /T ₉ (ratio of T ₀ to T ₉ ) is preferably 1.5 or more, more preferably 2.0 or more, preferably 4.0 or less, and more preferably 3.5 or less. When the above-mentioned T ₀ /T ₉ is above the above-mentioned lower limit and below the above-mentioned upper limit, generation of dew condensation can be effectively suppressed. When the above-mentioned T ₀ /T ₉ is equal to or greater than the above-mentioned lower limit, the heat insulation properties can be further improved. When the above-mentioned T ₀ /T ₉ is below the above-mentioned upper limit, the moldability can be improved and the impact resistance of the multilayer pipe can be improved.

The thickness (T ₀ ) of the multilayer tube at the maximum thickness position of the foam layer is preferably 5.4 mm or more, more preferably 5.9 mm or more, preferably 11.5 mm or less, and more preferably 11.0 mm or less.

Note that T ₀ , T ₃ , T ₆ , and T ₉ can be controlled by adjusting the mold size or adjusting the amount of foam layer material filled into the mold.

The multilayer tube may or may not have a maximum thickness at the position of the maximum thickness of the foam layer. Preferably, the multilayer tube has a maximum thickness at the location of the maximum thickness of the foam layer. It is preferable that the maximum thickness position of the foam layer is the maximum thickness position of the multilayer pipe. That is, it is preferable that the thickness T ₀ of the multilayer pipe is the maximum thickness of the multilayer pipe.

The multilayer tube may or may not have a minimum thickness at the minimum thickness position of the foam layer. Preferably, the multilayer tube has a minimum thickness at the location of the minimum thickness of the foam layer. It is preferable that the minimum thickness position of the foam layer is the minimum thickness position of the multilayer pipe.

The maximum thickness of the multilayer tube is preferably 8.0 mm or more, more preferably 8.5 mm or more, preferably 11.5 mm or less, and more preferably 11.0 mm or less.

The minimum thickness of the multilayer tube is preferably 5.4 mm or more, more preferably 5.9 mm or more, preferably 6.9 mm or less, and more preferably 6.4 mm or less.

The shape of the outer peripheral edge and the shape of the inner peripheral edge of the cross section of the inner layer along the radial direction of the multilayer pipe may or may not be perfectly circular. It is preferable that the shape of the outer peripheral edge and the shape of the inner peripheral edge of the cross section of the inner layer along the radial direction of the multilayer pipe are each perfectly circular.

The shape of the outer periphery and the shape of the inner periphery of the cross section of the outer layer along the radial direction of the multilayer pipe may or may not be perfectly circular. It is preferable that the shape of the outer peripheral edge and the shape of the inner peripheral edge of the cross section of the outer layer along the radial direction of the multilayer pipe are each perfectly circular. In addition, when an outer layer is directly laminated|stacked on the outer surface of a foam layer, the shape of the inner peripheral edge of the cross section of the outer layer along the radial direction of a multilayer pipe|tube is oval shape.

The average thickness of the inner layer is preferably 1.0 mm or more, more preferably 1.2 mm or more, preferably 2.6 mm or less, and more preferably 2.4 mm or less. When the average thickness of the inner layer is not less than the above lower limit and not more than the above upper limit, the strength of the multilayer pipe can be increased.

The maximum thickness of the outer layer is preferably 1.0 mm or more, more preferably 1.2 mm or more, preferably 2.6 mm or less, and more preferably 2.4 mm or less. When the maximum thickness of the outer layer is not less than the lower limit and not more than the upper limit, the surface hardness of the multilayer pipe can be increased, surface damage can be effectively suppressed, and adhesive strength can be increased.

Moreover, the multilayer pipe cannot be constructed unless it has sufficient strength as a piping material. The impact performance of the multilayer pipe decreases as the moldability deteriorates and the resin, which has been burned due to thermal history due to stagnation in the mold, is mixed into the multilayer pipe. In the present invention, since a foam layer having a specific thickness and a specific shape is provided, a multilayer pipe with stable moldability and sufficient strength can be obtained.

The foaming ratio of the foam layer is preferably 2 times or more, more preferably 3 times or more, preferably 8 times or less, and more preferably 6 times or less. When the expansion ratio is equal to or higher than the lower limit, the heat insulation properties can be further improved. When the expansion ratio is equal to or less than the upper limit, the cell diameter can be made uniform and the closed cell ratio can be increased. When the closed cell ratio is high, for example, when water infiltrates into the foam layer from the end of the multilayer pipe due to capillary action, it is possible to reduce the risk of water permeating the entire foam layer through the air bubbles. Therefore, deterioration in heat insulation performance can be suppressed.

The foaming ratio of the foamed layer is measured as follows.

The multilayer tube is cut to have an axial length of 50 mm. After cutting the cut multilayer pipe along the axial direction so that it is evenly divided into four parts in the circumferential direction, the inner layer and outer layer are cut and removed, and a plate shape of 50 mm in length is made of only the foam layer. Prepare four body test pieces. The apparent density of each of the four test pieces at 23° C.±2° C. is determined to three digits after the decimal point using a water displacement type specific gravity meter in accordance with JIS K7112:1999. The foaming ratio for one test piece is calculated using the following formula (X), and the average value of the foaming ratios of the four test pieces is taken as the foaming ratio of the foam layer.

m=γo/γ...(X)

In the above formula (X), m represents the expansion ratio, γ represents the apparent density (g/cm ³ ) of the test piece, and γo represents the density (g/cm ³ ) of the material of the foam layer. γo is the density of the material of the foamed layer before forming the foamed layer, and is the density when not foamed.

The density (γo) of the material of the foam layer varies by about 0.1 g/ ^cm3 from the density of the thermoplastic resin when the material of the foam layer contains other components (additives) other than the thermoplastic resin described below. There are things to do. As the density (γo) of the material of the foam layer, for example, the density of a thermoplastic resin described in the Chemical Handbook (Applied Chemistry Edition II Materials Edition) may be used. For example, when the foam layer material contains 75% by weight or more of vinyl chloride resin, the density of the vinyl chloride resin described in the above-mentioned Chemistry Handbook (Applied Chemistry Section II Materials Section) is 1.54 g/ ^cm3 . , may be adopted as the density (γo) of the material of the foam layer.

(Other details of inner layer, foam layer and outer layer)
The inner layer preferably contains a thermoplastic resin. The foam layer preferably contains a thermoplastic resin. The outer layer preferably contains a thermoplastic resin. The thermoplastic resins contained in the inner layer, the foamed layer, and the outer layer may be the same or different. Only one kind of the above-mentioned thermoplastic resin may be used, or two or more kinds thereof may be used in combination.

The thermoplastic resins include polyvinyl chloride (PVC); olefin resins such as polyethylene, polypropylene, polybutene, ethylene-vinyl acetate copolymer, and ethylene-α-olefin copolymer; polystyrene resin; polyethylene terephthalate; ABS Resin: Examples include acrylic resin.

The polyvinyl chloride (PVC) is not particularly limited, and conventionally known vinyl chloride resins can be used. The vinyl chloride resin mentioned above includes (1) a homopolymer of a vinyl chloride monomer, (2) a copolymer of a vinyl chloride monomer and a monomer having an unsaturated bond copolymerizable with the vinyl chloride monomer, and (3) a chlorinated resin. Examples include graft polymers in which vinyl chloride is graft-polymerized to polymers and copolymers other than vinyl. The above-mentioned vinyl chloride resins may be used alone or in combination of two or more.

Monomers having unsaturated bonds that can be copolymerized with the vinyl chloride monomer are not particularly limited, and include α-olefin compounds such as ethylene, propylene, butylene; compounds having vinyl groups such as allyl chloride and acrylonitrile; vinyl acetate, propion Vinyl ester compounds such as vinyl acid; vinyl ether compounds such as butyl vinyl ether and cetyl vinyl ether; (meth)acrylic acid ester compounds such as methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate; styrene, α-methyl Examples include aromatic vinyl compounds such as styrene; dicarboxylic acid compounds such as maleic anhydride; and N-substituted maleimide compounds such as N-phenylmaleimide and N-cyclohexylmaleimide. Only one type of monomer having an unsaturated bond copolymerizable with the above-mentioned vinyl chloride monomer may be used, or two or more types may be used in combination.

The above copolymer may be a random copolymer or a block copolymer.

The polymers and copolymers to be graft copolymerized with vinyl chloride are not particularly limited, and include ethylene-vinyl acetate copolymer, ethylene-vinyl acetate-carbon monoxide copolymer, ethylene-ethyl acrylate copolymer, ethylene Examples include -butyl acrylate-carbon monoxide copolymer, acrylonitrile-butadiene copolymer, polyurethane, chlorinated polyethylene, and chlorinated polypropylene. Only one kind of the above-mentioned polymers and copolymers for graft copolymerizing vinyl chloride may be used, or two or more kinds thereof may be used in combination.

The content of structural units derived from vinyl chloride in 100% by weight of the vinyl chloride resin is preferably 40% by weight or more.

The degree of polymerization of the vinyl chloride resin is preferably 400 or more, and preferably 3000 or less. When the degree of polymerization of the vinyl chloride resin is equal to or higher than the lower limit, long-term performance such as thermal stability and fatigue properties will not be easily impaired. When the degree of polymerization of the vinyl chloride resin is below the above upper limit, there is no need to use high temperature during molding, and processability becomes even better.

The vinyl chloride resin may be a chlorinated vinyl chloride resin.

From the viewpoint of improving flame retardancy, the thermoplastic resin contained in the inner layer is preferably a vinyl chloride resin, more preferably a chlorinated vinyl chloride resin. When the thermoplastic resin contained in the inner layer is a chlorinated vinyl chloride resin, flame retardancy and heat deformation resistance can be further improved.

From the viewpoint of improving flame retardancy, the thermoplastic resin contained in the foamed layer is preferably a vinyl chloride resin, more preferably a chlorinated vinyl chloride resin. When the thermoplastic resin contained in the foamed layer is a chlorinated vinyl chloride resin, flame retardancy and heat deformation resistance can be further improved.

From the viewpoint of increasing flame retardance and facilitating connection with a joint, the thermoplastic resin contained in the outer layer is preferably a vinyl chloride resin, more preferably a chlorinated vinyl chloride resin. . When the thermoplastic resin contained in the outer layer is a chlorinated vinyl chloride resin, flame retardancy and heat deformation resistance can be further improved.

It is also preferable that the foamed layer contains the vinyl chloride resin and a thermoplastic resin other than the vinyl chloride resin. Thermoplastic resins other than the vinyl chloride resins mentioned above include acrylic resins, polyethylene, polypropylene, polystyrene, polybutene, chlorinated polyethylene, ethylene-propylene copolymers, ethylene-ethyl acrylate copolymers, polyethylene terephthalate, and ABS resins. etc. From the viewpoint of improving melt tension and improving expansion ratio, the thermoplastic resin other than the vinyl chloride resin is preferably an acrylic resin, and the acrylic resin has a molecular weight of 3 million or more. is more preferable.

The content of the thermoplastic resin in 100% by weight of the inner layer is preferably 90% by weight or more, more preferably 95% by weight or more, and still more preferably 99% by weight or more.

The content of the thermoplastic resin in 100% by weight of the foamed layer is preferably 90% by weight or more, more preferably 95% by weight or more, and still more preferably 99% by weight or more.

The content of the thermoplastic resin in 100% by weight of the outer layer is preferably 90% by weight or more, more preferably 95% by weight or more, and still more preferably 99% by weight or more.

The foaming method used to form the foam layer is not particularly limited, and any conventional foaming method may be employed. Examples of the foaming method include a chemical foaming method and a physical foaming method.

When the foam layer is formed by the chemical foaming method, the material of the foam layer preferably contains a pyrolytic foaming agent. Only one kind of the above-mentioned thermally decomposable foaming agent may be used, or two or more kinds thereof may be used in combination.

Examples of the thermally decomposable blowing agents include baking soda (sodium hydrogen carbonate) blowing agents, ADCA (azodicarbonamide), DPT (N,N'-dinitrosopentamethylenetetramine), and OBSH (4,4'-oxybis( Examples include benzenesulfonyl hydrazide)).

From the viewpoint of increasing the closed cell ratio, the thermally decomposable foaming agent preferably contains ADCA.

When the foam layer is formed by the physical foaming method, the material of the foam layer preferably contains thermally expandable microcapsules (microscopic plastic spheres). The above thermally expandable microcapsules may be used alone or in combination of two or more.

The thermally expandable microcapsules preferably contain a low boiling point hydrocarbon. The thermally expandable microcapsules preferably include a shell made of a thermoplastic resin and a low-boiling hydrocarbon as an inclusion. The volatilization temperature of the low-boiling hydrocarbon is preferably 140°C or higher, and preferably 210°C or lower.

Commercially available products of the thermally expandable microcapsules include "Advancel" manufactured by Tokuyama Sekisui Kogyo Co., Ltd., and the like.

The inner layer, the foamed layer, and the outer layer may each contain various additives, if necessary. The above additives include stabilizers, stabilizing aids, lubricants, processing aids, impact modifiers, heat resistance improvers, antioxidants, ultraviolet absorbers, light stabilizers, fillers, pigments, and plasticizers. Can be mentioned. The above additives may be used alone or in combination of two or more.

The above-mentioned stabilizer is not particularly limited, and includes heat stabilizers, heat stabilization aids, and the like. The above heat stabilizer is not particularly limited, and examples thereof include organotin stabilizers, lead stabilizers, calcium-zinc stabilizers, barium-zinc stabilizers, barium-cadmium stabilizers, and the like. The organic tin stabilizers include dibutyltin mercapto, dioctyltin mercapto, dimethyltin mercapto, dibutyltin mercapto, dibutyltin maleate, dibutyltin maleate polymer, dioctyltin maleate, dioctyltin maleate polymer, dibutyltin laurate, and Examples include dibutyltin laurate polymer. The above stabilizers may be used alone or in combination of two or more. The thermal stabilization aid is not particularly limited, and examples thereof include epoxidized soybean oil, phosphate ester, polyol, hydrotalcite, and zeolite. The above heat stabilizing aids may be used alone or in combination of two or more.

The above-mentioned lubricant is not particularly limited, and includes internal lubricants and external lubricants. The internal lubricant is used for the purpose of lowering the flow viscosity of the molten resin during molding and preventing frictional heat generation. The internal lubricant is not particularly limited, and includes butyl stearate, lauryl alcohol, stearyl alcohol, epoxy soybean oil, glycerin monostearate, stearic acid, bisamide, and the like. The external lubricant is used for the purpose of increasing the sliding effect between the molten resin and the metal surface during molding. The external lubricant is not particularly limited, and examples include paraffin wax, polyolefin wax, ester wax, and montan acid wax. The above lubricants may be used alone or in combination of two or more.

The processing aid is not particularly limited, and examples thereof include acrylic processing aids and the like. Examples of the acrylic processing aids include alkyl acrylate-alkyl methacrylate copolymers having a weight average molecular weight of 100,000 to 2,000,000, and specifically, n-butyl acrylate-methyl methacrylate copolymers, and Examples include 2-ethylhexyl acrylate-methyl methacrylate-butyl methacrylate copolymer. The above-mentioned processing aids may be used alone or in combination of two or more.

The impact modifier is not particularly limited, and examples include methyl methacrylate-butadiene-styrene copolymer (MBS), chlorinated polyethylene, and acrylic rubber. The above-mentioned impact modifiers may be used alone or in combination of two or more.

The heat resistance improver is not particularly limited, and examples include α-methylstyrene resins and N-phenylmaleimide resins. Only one kind of the above-mentioned heat resistance improver may be used, or two or more kinds thereof may be used in combination.

The above-mentioned antioxidant is not particularly limited, and includes phenolic antioxidants and the like. The above antioxidants may be used alone or in combination of two or more.

The UV absorber is not particularly limited, and examples include salicylic acid ester UV absorbers, benzophenone UV absorbers, benzotriazole UV absorbers, and cyanoacrylate UV absorbers. The above ultraviolet absorbers may be used alone or in combination of two or more.

The light stabilizer is not particularly limited, and examples thereof include hindered amine light stabilizers. The above light stabilizers may be used alone or in combination of two or more.

The filler is not particularly limited, and examples thereof include calcium carbonate and talc. The above-mentioned fillers may be used alone or in combination of two or more.

The above-mentioned pigment is not particularly limited, and includes organic pigments and inorganic pigments. Examples of the organic pigments include azo organic pigments, phthalocyanine organic pigments, threne organic pigments, and dye lake organic pigments. Examples of the inorganic pigments include oxide-based inorganic pigments, molybdenum chromate-based inorganic pigments, sulfide/selenide-based inorganic pigments, and ferrocyanide-based inorganic pigments. The above pigments may be used alone or in combination of two or more.

The above plasticizer may be added for the purpose of improving processability during molding. Since the addition of a plasticizer may reduce the heat resistance of the molded article, it is preferable that the amount of plasticizer added be small. The plasticizer is not particularly limited, and examples include dibutyl phthalate, di-2-ethylhexyl phthalate, and di-2-ethylhexyl adipate. Only one type of the above plasticizer may be used, or two or more types may be used in combination.

(Manufacturing method of multilayer pipe)
FIG. 2 is a plan view schematically showing a manufacturing apparatus used for manufacturing a multilayer pipe according to an embodiment of the present invention. FIG. 3 is a front view schematically showing a manufacturing apparatus used for manufacturing a multilayer pipe according to an embodiment of the present invention. 2 and 3 are diagrams schematically showing a manufacturing apparatus for manufacturing the multilayer pipe 10.

The manufacturing apparatus 20 includes a gas cylinder 18 , a metering pump 19 , an inner and outer layer extruder 11 , a foam layer extruder 12 , a mold 13 , a cooling water tank 15 , a take-up machine 16 , and a cutting machine 17 . A foam layer extruder 12 is connected to the gas cylinder 18 and metering pump 19 . A mold 13 is connected to the inner and outer layer extruder 11 and the foam layer extruder 12. A cooling water tank 15 is connected to the mold 13. A take-up machine 16 is connected to the cooling water tank 15. A cutting machine 17 is connected to the taking machine 16.

The material for the inner layer and the material for the outer layer are charged from a hopper, melted and kneaded in the inner and outer layer extruder 11, and extruded into the mold 13.

Materials for the foam layer are charged from a hopper, melted and kneaded in a foam layer extruder 12, and extruded into a mold 13. When a gas blowing agent is used as the blowing agent, the metering pump 19 supplies the gas blowing agent contained in the gas cylinder 18 to the foam layer extruder 12 through the vent hole. Note that when a solid or liquid foaming agent is used as the foaming agent, the foaming agent may be mixed in advance with the material of the foaming layer, and the metering pump 19 and the gas cylinder 18 may not be used.

An uncured multilayer tube having a three-layer structure is extruded from the outlet of the mold 13.

A tube outer surface forming tube 14 for forming the uncured multilayer tube into a predetermined size is attached to the cooling water tank 15, and the outer surface of the uncured multilayer tube is in contact with the tube outer surface forming tube 14. Cool it down.

FIG. 4 is an enlarged sectional view showing a mold part and a tube outer surface forming tube part in the manufacturing apparatus.

As shown in FIG. 4, the inner layer material 21 and the outer layer material 23 melt-kneaded by the inner and outer layer extruder 11 and the foam layer material 22 melt-kneaded by the foam layer extruder 12 are combined into a cross section of the foam layer. The mixture is injected into a mold 13 designed so that the outer periphery thereof has an oval shape to form an uncured multilayer pipe 10X. The unhardened multilayer pipe 10X includes an unhardened inner layer 31, an unhardened outer layer 33, and a layer formed of the foam layer material 22.

When the uncured multilayer pipe 10X is discharged from the mold 13, the material 22 of the foam layer foams, and an uncured foam layer 32 is formed. The unhardened multilayer tube 10X is inserted into the tube outer surface forming tube 14, and the unhardened multilayer tube 10X is cooled in the cooling water tank 15 while being molded into a predetermined size.

Next, as shown in FIGS. 2 and 3, the multilayer pipe 10 cooled in the cooling water tank 15 is taken off using the take-off machine 16, and the multi-layer pipe 10 sent from the take-off machine 16 is taken off using the cutting machine 17. 10 is cut to a predetermined length. In this way, a multilayer tube 10 having a predetermined length is obtained.

The heating temperature in the mold 13 is preferably 140°C or higher, more preferably 160°C or higher, preferably 200°C or lower, and more preferably 190°C or lower. The heating time in the mold 13 is preferably 10 minutes or more, preferably 30 minutes or less, and more preferably 20 minutes or less.

Hereinafter, the present invention will be explained in more detail with reference to Examples. The present invention is not limited only to the following examples.

(Example 1)
Inner layer material and outer layer material:
Materials having the following compositions were prepared as the material for the inner layer and the material for the outer layer.

100 parts by weight of polyvinyl chloride resin (“TS-1000R” manufactured by Tokuyama Sekisui Kogyo Co., Ltd.) 3 parts by weight of Ca/Zn stabilizer (“TVS-8832” manufactured by Nitto Kasei Co., Ltd.) MBS resin (“B-564” manufactured by Kaneka Corporation) 5 parts by weight Acrylic resin with a molecular weight of 3 million or more (“PA-40” manufactured by Kaneka Corporation) 3 parts by weight Lubricant (“Hiwax 220RKT” manufactured by Mitsui Chemicals) 1 part by weight Lubricant (“Roxiol 259” manufactured by Emery Oleochemicals Japan Co., Ltd.) ”) 1 part by weight Calcium carbonate (“CCR” manufactured by Shiraishi Kogyo Co., Ltd.) 2 parts by weight Coloring agent (“Gray NS-R1875-J” manufactured by Resino Color Co., Ltd.) 0.6 parts by weight

Foam layer material:
A material having the following composition was prepared as a material for the foam layer.

100 parts by weight of polyvinyl chloride resin (“TS-800E” manufactured by Tokuyama Sekisui Kogyo Co., Ltd.) 10 parts by weight of acrylic resin with a molecular weight of 3 million or more (“PA-40” manufactured by Kaneka Corporation) Baking soda (“Celvon SC” manufactured by Eiwa Kasei Kogyo Co., Ltd.) -855") 2 parts by weight ADCA ("Vinihole AC#3" manufactured by Eiwa Kasei Co., Ltd.) 0.5 parts by weight Organotin stabilizer ("TVS-8832" manufactured by Nitto Kasei Co., Ltd.) 3 parts by weight Lubricant (Mitsui Chemicals, Inc.) 1 part by weight of lubricant (Roxiol 259, manufactured by Emery Oleochemicals Japan) 2 parts by weight of calcium carbonate (CCR, manufactured by Shiraishi Kogyo Co., Ltd.) Colorant (IV-, manufactured by Hexa Chemical Company) D-13486”) 0.4 parts by weight

Manufacture of multilayer pipes (air conditioning drain pipes):
Using a manufacturing device comprising an inner and outer layer extruder, a foam layer extruder, a mold, a cooling water tank to which a tube for forming the outer surface of the tube is attached, a take-up machine, and a cutting machine, the following steps are carried out: Extrusion molding was performed. Note that a mold capable of molding the outer peripheral edge of the cross section of the foam layer along the radial direction of the multilayer pipe into an oval shape was used as the mold.

The material for the foam layer was kneaded at 170° C. using a foam layer extruder, and the mixture was injected into a mold at an extrusion rate of 20 kg/h. The material for the inner layer and the material for the outer layer were kneaded at 180° C. using an inner/outer layer extruder, and the mixture was injected into a mold at 40 kg/h. Each material discharged from the mold was inserted into a tube for forming the outer surface of the tube, cooled in a cooling water tank, taken out by a pulling machine, and then cut into a predetermined length by a cutting machine. In this way, two multilayer pipes (air conditioning drain pipes) having the following dimensions and shapes were manufactured. Furthermore, in the obtained multilayer pipe, the maximum thickness of the multilayer pipe existed at the position of the maximum thickness of the foam layer.

<Multilayer pipe>
Thickness T ₀ (maximum thickness of multilayer pipe): 8.0mm
Thickness _T3 : 4.0mm
Thickness T ₆ : 4.0mm
Thickness _T9 : 4.0mm
Axial length: 1m

<Inner layer>
Average thickness: 1.5mm

<Outer layer>
Maximum thickness: 1.5mm
Minimum thickness: 1.0mm

<Foam layer>
Maximum thickness: 5.0mm
Thickness at _T3 position: 1.5mm
Thickness at _T6 position: 1.5mm
Thickness at _T9 position: 1.5mm

(Examples 2 and 3 and Comparative Examples 1 and 2)
Two multilayer pipes (air conditioning drain pipes) having the dimensions and shapes shown in Table 1 were manufactured in the same manner as in Example 1, except that the shape of the mold was changed.

(evaluation)
(1) Condensation The experimental apparatus shown in FIG. 5 was manufactured. The experimental device 50 includes the obtained multilayer pipe (air conditioning drain pipe) 51, a chiller pump 52, a circulation bucket pump 53, a joint 54, and a hose 55. The chiller pump 52 has a function of adjusting the water temperature to a constant level, and the circulation bucket pump 53 has a function of returning flowing water to the chiller pump. In the experimental apparatus 50, the multilayer tube 51 is installed with the maximum thickness portion of the foam layer located at the bottom. Moreover, the multilayer pipe 51 is installed at a slope of 1/100.

The circulation bucket pump 53 was driven to circulate 5° C. tap water at 6 L/h for 15 minutes. In Examples 1 to 3, tests were conducted at an outside temperature of 25°C and 35°C, and in Comparative Examples 1 and 2, tests were performed at an outside temperature of 25°C.

After circulating tap water at 5° C. for 15 minutes, the outer surface of the bottom (lower side) of the multilayer pipe 51 was touched with a hand to check for the presence or absence of dew condensation.

[Condensation criteria]
○: No condensation occurs ×: Condensation occurs

(2) Impact performance The obtained multilayer pipe (air conditioning drain pipe) was dropped from a height of 3 m in an environment at room temperature. The multilayer pipe was visually confirmed after the fall.

[Criteria for impact performance]
○: No cracks or cracks ×: There are cracks or cracks

Table 1 shows the structure and results of the multilayer pipe (air conditioning drain pipe).

1... Inner layer 2... Foaming layer 3... Outer layer 10... Multilayer pipe 10X... Uncured multilayer pipe 11... Inner and outer layer extruder 12... Foaming layer extruder 13... Mold 14... Tube for forming the tube outer surface 15... Cooling water tank 16... Taking-off machine 17... Cutting machine 18... Gas cylinder 19... Metering pump 20... Manufacturing device 21... Inner layer material 22... Foam layer material 23... Outer layer material 31... Uncured inner layer 32... Uncured foam layer 33... Uncured Outer layer 50... Experimental equipment 51... Multilayer pipe 52... Chiller pump 53... Circulating bucket pump 54... Coupling 55... Hose

Claims (4)

inner layer and
a foam layer disposed outside the inner layer;
an outer layer disposed outside the foam layer,
The outer peripheral edge of the cross section of the foam layer along the radial direction of the multilayer pipe has an oval shape,
The thickness of the foam layer is partially different,
The maximum thickness of the foam layer is 3.0 mm or more and 9.0 mm or less,
A multilayer pipe that is installed and used with the maximum thickness portion of the foam layer located at the bottom . Assuming that the thickness of the multilayer pipe at the maximum thickness position of the foam layer is T ₀ and the maximum thickness position of the foam layer is the 0 o'clock position, the thickness of the multilayer pipe in the 3 o'clock direction when viewed from the axis of the outer layer is T ₃ , the thickness of the multilayer tube in the 6 o'clock direction is T ₆ , and the thickness of the multilayer tube in the ₉ o'clock direction is T 9 , T ₀ /T ₃ , T ₀ /T ₆ , and T ₀ / T ₉ are respectively , 1.5 or more and 4.0 or less. The multilayer pipe according to claim 1 or 2, wherein the foam layer contains a vinyl chloride resin. The multilayer pipe according to any one of claims 1 to 3 , which is an air conditioning drain pipe.

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