Resin molding and molding method

Abstract

To achieve a resin molding that easily stabilizes its thermal insulation property for each individual piece.SOLUTION: A resin molding 1, which includes a polyvinyl chloride resin composition, comprises a main body portion 14, a cavity portion 15 isolated from outside by the main body portion 14, and a reinforcement portion disposed in the cavity portion 15 and connected to the main body portion 14 at two locations or more.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a resin molded body and a molding method.

Background Art

[0002] Resin molded bodies having a structure for enhancing heat insulation are widely used. For example, International Publication No. 2019 / 065834 (Patent Document 1) and Japanese Patent Application Laid-Open No. 11-201382 (Patent Document 2) disclose joints having a foamed resin layer. In these joints, the foamed resin layer provided in the joint functions as a heat insulation layer, and can prevent heat transfer between the fluid flowing through the joint and the air outside the joint. Thereby, problems such as condensation occurring in the joint can be solved.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the method of providing a heat insulation layer by a foaming molding technique as in Patent Document 1 and Patent Document 2, it has been difficult to control the foaming phenomenon when molding a resin molded body. Therefore, the resin molded bodies obtained by the foaming molding technique have a problem that the heat insulation property varies from one individual to another due to variations in the distribution of bubbles and the foaming ratio, etc. In addition, it has been difficult to adjust the level of heat insulation of the resin molded bodies obtained by the foaming molding technique to an arbitrary value for each individual.

[0005] Therefore, there is a demand for realizing a resin molded body in which the heat insulation property for each individual is likely to be stable and the adjustment of the heat insulation property is easy.

Means for Solving the Problems

[0006] The resin molded body according to the present invention is a resin molded body containing a polyvinyl chloride resin composition, and includes a main body portion, a cavity portion isolated from the outside by the main body portion, and a reinforcing portion disposed in the cavity portion and connected to the main body portion at at least two locations.

[0007] The molding method according to the present invention is a molding method for molding a resin molded body including a main body portion, a cavity portion isolated from the outside by the main body portion, and a reinforcing portion disposed in the cavity portion and connected to the main body portion at at least two locations, and containing a polyvinyl chloride resin composition, using a three-dimensional printing apparatus. The molding method includes a data creation step of creating three-dimensional data of the resin molded body, the three-dimensional data including information regarding at least the positions of the main body portion and the cavity portion, and a molding step of performing additive molding of the polyvinyl chloride resin composition based on the three-dimensional data using the three-dimensional printing apparatus. In the molding step, the cavity portion is formed as a location where the main body portion and the reinforcing portion do not exist by forming the main body portion and the reinforcing portion based on the three-dimensional data.

[0008] According to these configurations, a resin molded body having a cavity portion with a freely designable shape can be supplied. Therefore, the heat insulation property of each individual resin molded body is likely to be stable, and the level of heat insulation can be adjusted to an arbitrary value for each individual.

[0009] Hereinafter, preferred embodiments of the present invention will be described. However, the scope of the present invention is not limited by the preferred embodiment examples described below.

[0010] The resin molded body according to the present invention is preferably, as one aspect, a pipe member capable of forming a pipe through which a fluid flows.

[0011] According to this configuration, problems such as dew condensation caused by the temperature difference between the fluid flowing through the pipe and the outside air of the pipe can be solved.

[0012] The resin molded body according to the present invention, in one aspect, is preferably configured such that the cavity portion is provided around at least a part of a flow path through which the fluid flows, and a plurality of reinforcing portions are provided in both the direction along the flow path and the direction away from the flow path.

[0013] According to this configuration, having a plurality of reinforcing portions tends to increase the strength of the resin molded body.

[0014] The resin molded body according to the present invention, in one aspect, preferably has unit cavities partitioned by a plurality of the reinforcing portions, and the interval between the plurality of the reinforcing portions in the unit cavity is preferably 0.5 mm or more and 15 mm or less.

[0015] According to this configuration, it is more suitable from the viewpoint of increasing the strength of the resin molded body.

[0016] The resin molded body according to the present invention, in one aspect, preferably includes a polyvinyl chloride resin and a tin-based stabilizer containing a tin compound.

[0017] According to this configuration, since decomposition and coloring of the polyvinyl chloride resin composition during molding of the resin molded body can be easily prevented, the quality of the resin molded body can be improved.

[0018] The resin molded body according to the present invention, in one aspect, preferably contains 1 to 8 parts by weight of a tin-based stabilizer with respect to 100 parts by weight of the polyvinyl chloride resin.

[0019] Since a polyvinyl chloride resin composition containing a tin-based stabilizer is excellent in static thermal stability, according to this configuration, the moldability during molding of the resin molded body is good. Therefore, a resin molded body with good physical properties and appearance can be easily obtained.

[0020] The resin molded body according to the present invention, in one aspect, preferably contains at least a liquid in the tin-based stabilizer.

[0021] According to this configuration, the moldability when molding the resin molded body is further improved.

[0022] As one aspect, the molding method according to the present invention preferably further includes information regarding the position of the reinforcing portion in the three-dimensional data.

[0023] According to this configuration, even if the shape of the cavity portion is relatively complex, molding is easy to achieve.

[0024] As one aspect, the molding method according to the present invention further includes information regarding the position and filling rate of the cavity portion in the three-dimensional data, and the molding step is based on the information regarding the position and filling rate of the cavity portion included in the three-dimensional data. It preferably includes a first step of generating information regarding the position of the reinforcing portion arranged in the cavity portion, and a second step of forming the main body portion and the reinforcing portion based on the information regarding the position of the main body portion included in the three-dimensional data and the information regarding the position of the reinforcing portion generated in the first step.

[0025] According to this configuration, it is relatively easy to create three-dimensional data. In addition, since it is easy to control the filling rate of the cavity portion, it is easy to adjust the heat insulation property. Note that the filling rate is the volume ratio of the portion occupied by the reinforcing portion in the volume of the cavity portion.

[0026] As one aspect, the molding method according to the present invention preferably further includes information regarding the thickness of the portion of the main body portion that defines the cavity portion.

[0027] According to this configuration, since the structure of the cavity portion can be specified using at least two variables, namely the filling rate of the cavity portion itself and the thickness of the portion that defines the cavity portion, it is even easier to adjust the heat insulation property.

[0028] Further features and advantages of the present invention will become clearer from the following description of exemplary and non-limiting embodiments described with reference to the drawings.

Brief Description of the Drawings

[0029]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Mode for Carrying Out the Invention

[0030] Embodiments of the resin molded body and the molding method according to the present invention will be described with reference to the drawings. Hereinafter, an example in which the resin molded body according to the present invention is applied to the joint 1 will be described.

[0031] 〔Materials Constituting the Joint〕 The joint 1 according to the present embodiment is made of a polyvinyl chloride resin composition. The polyvinyl chloride resin composition is a resin composition mainly composed of a polyvinyl chloride resin, and contains additives such as a stabilizer and a lubricant in addition to the polyvinyl chloride resin. Here, the "main component" means a component that occupies 50% by mass or more in the resin composition.

[0032] The polyvinyl chloride resin is not particularly limited, and commercially available products can be used. Examples of such commercially available products include, but are not limited to, Kanevinyll (registered trademark) S series (manufactured by Kaneka Corporation).

[0033] The polyvinyl chloride resin composition preferably contains a chlorinated polyethylene resin. Since the chlorinated polyethylene resin does not have double bonds in the main chain, it is excellent in weather resistance, ozone resistance, heat aging resistance, etc. The content of the chlorinated polyethylene resin is preferably 2 to 6 parts by weight with respect to 100 parts by weight of the polyvinyl chloride resin.

[0034] The polyvinyl chloride resin composition preferably contains a tin-based stabilizer containing a tin compound. Since the polyvinyl chloride resin composition containing a tin-based stabilizer is excellent in static thermal stability, the moldability when molding the joint 1 is good. Therefore, it is easy to obtain a joint 1 with good physical properties and appearance. As the tin-based stabilizer, both solid and liquid ones can be used, but it is preferably at least a liquid-containing one, and more preferably only a liquid one. This is because the liquid tin-based stabilizer has the properties of internal lubrication and external lubrication, so the effect as a lubricant can be expected, and thereby the moldability when molding the joint 1 is improved.

[0035] Examples of the tin compound contained in the tin-based stabilizer include, but are not limited to, dimethyltin mercapto, dibutyltin mercapto, dioctyltin mercapto, dibutyltin mercapto, dibutyltin maleate, dibutyltin maleate polymer, dioctyltin maleate, dioctyltin maleate polymer, dibutyltin laurate, and dibutyltin laurate polymer. The tin-based tin compound contained in the stabilizer may be one kind or a plurality of kinds.

[0036] The polyvinyl chloride resin composition preferably contains 1 to 8 parts by weight of a tin-based stabilizer with respect to 100 parts by weight of the polyvinyl chloride resin. When the content of the tin-based stabilizer is within the above range, the static thermal stability of the polyvinyl chloride resin composition is particularly improved. The content of the tin-based stabilizer is more preferably 4 to 8 parts by weight with respect to 100 parts by weight of the polyvinyl chloride resin.

[0037] The polyvinyl chloride resin composition preferably contains a lubricant. Examples of the lubricant include, but are not limited to, fatty acid esters, fatty acids, fatty alcohols, fatty alcohol esters, fatty acid amides, polyol esters, polyethylene wax, oxidized polyethylene wax, polypropylene wax, Fischer-Tropsch paraffin, paraffin wax, oligomer esters ( "complex esters"), montanic acid esters, soaps, metal soaps of fatty acids, and metal soaps of montanic acid. The content of the lubricant is preferably 0.8 to 1.6 parts by weight with respect to 100 parts by weight of the polyvinyl chloride resin.

[0038] There is no hindrance to the polyvinyl chloride resin composition containing additives other than those described above. Examples of such additives include, but are not limited to, processing aids, antioxidants, reinforcing agents such as fiber materials, and pigments. Commercially available products can be used for any type of additive.

[0039] When the polyvinyl chloride resin composition contains a fiber material, the content of the fiber material is preferably 10% by mass or less of the entire polyvinyl chloride resin composition. When the content of the fiber material is within this range, clogging of the nozzle is less likely to occur when molding the resin molded body, and the dimensional accuracy is improved, so that the processability is generally good. When molding the joint 1 using a three-dimensional printing apparatus, it is particularly preferable that the content of the fiber material is within the above range.

[0040] 〔Configuration of Joint〕 The joint 1 according to the present embodiment is a so-called 90° elbow joint that connects two pipes at a crossing angle of 90°. The joint 1 includes two sockets 11 to which the pipes are respectively connected, and an elbow portion 12 that connects the two sockets 11 (FIGS. 1 and 2). There is a flow path 13 through which fluid flows in the socket 11 and the elbow portion 12.

[0041] The receiving port 11 is a cylindrical part and has an inner diameter corresponding to the outer diameter of the pipe to be connected. When the joint 1 is connected to the pipe, the end of the pipe is inserted into the receiving port 11, and the receiving port 11 and the pipe are adhered by an adhesive. When the joint 1 and the pipe are connected, a pipe through which fluid flows is formed. The joint 1 and the pipe are pipe members forming the pipe.

[0042] The elbow part 12 is a part connecting two receiving ports 11 and defines a portion where the flow path 13 bends at 90°. The portion defining the flow path 13 in the elbow part 12 has a main body part 14, a cavity part 15 isolated from the outside by the main body part, and a reinforcing part 16 arranged in the cavity part 15. The main body part 14 is a solid part defining the flow path 13 and the cavity part 15 and is made of a polyvinyl chloride resin composition.

[0043] The cavity part 15 is a space isolated from the space outside the joint 1 by the main body part 14. In the present embodiment, the cavity part 15 is provided around the flow path 13. The cavity part 15 serves to suppress heat conduction between the fluid flowing through the flow path 13 and the outside of the pipe. Therefore, the pipe formed using the joint 1 has higher heat insulation than the pipe formed using a solid joint.

[0044] The reinforcing part 16 is a structure arranged in the cavity part 15 and connected to the main body part 14 at at least two locations. The reinforcing part 16 serves to support the main body part 14 defining the cavity part 15 inside the cavity part 15. In the present embodiment, the cavity part 15 is provided to impart heat insulation to the joint 1, but providing the cavity part 15 may impair the strength of the joint 1 (main body part 14). The reinforcing part 16 prevents such a decrease in strength and realizes the coexistence of heat insulation and strength in the joint 1.

[0045] In this embodiment, a plurality of reinforcing portions 16 including two groups of a first reinforcing portion 16a and a second reinforcing portion 16b are provided (FIG. 3). The first reinforcing portion 16a extends in the tangential direction of the outer arc of the flow path 13 that bends at 90° in the elbow portion 12 and in a direction parallel to the tangential direction. The plurality of first reinforcing portions 16a are provided in parallel at intervals of 2 mm. The second reinforcing portion 16b extends in a direction orthogonal to the first reinforcing portion 16a in FIG. 1. The plurality of second reinforcing portions 16b are provided in parallel at intervals of 2 mm. As shown in FIG. 1, a plurality of first reinforcing portions 16a and second reinforcing portions 16b are provided respectively, and both form a lattice. Therefore, it can be said that a plurality of reinforcing portions 16 are provided in both the direction along the flow path 13 and the direction away from the flow path 13.

[0046] When a plurality of reinforcing portions 16 are provided as in this embodiment, the mode is not limited to a lattice shape. As described above, the reinforcing portion 16 is a structure connected to the main body portion 14 at at least two locations, and can be provided in any shape and structure as long as it can prevent a decrease in the strength of the joint 1 by providing the cavity portion 15. The reinforcing portion 16 can be, for example, lattice-shaped, mesh-shaped, honeycomb-shaped, corrugated, linear, or the like.

[0047] Due to the provision of the reinforcing portion 16, the cavity portion 15 is partitioned into a plurality of unit cavities 17. Corresponding to the installation intervals of both the first reinforcing portion 16a and the second reinforcing portion 16b being 2 mm, the interval between the reinforcing portions 16 in the unit cavity 17 is 2 mm. Therefore, in this embodiment, the unit cavity 17 is a space of approximately 2 mm square extending in the depth direction of the drawing of FIG. 2. As in this example, when the interval between the reinforcing portions 16 in the unit cavity 17 is 0.5 mm or more and 15 mm or less, it is preferable because it is easy to balance the ease of production and the strength of the joint 1. The lower limit of the preferable range of the interval between the reinforcing portions 16 in the unit cavity 17 is derived from, for example, the minimum dimension of a structure that can be realized when forming the joint 1 by additive molding using a three-dimensional printing device.

[0048] The upper limit of the suitable range of the intervals of the reinforcing portions 16 in the unit cavities 17 can vary depending on the structure of the cavity portion 15 and the main body portion 14 that defines the cavity portion 15. Therefore, depending on the structure of the main body portion 14 that defines the cavity portion 15, even if the intervals of the reinforcing portions 16 in the unit cavities 17 are 15 mm or more, it may be possible to achieve both ease of production and strength of the joint 1. For example, when it is necessary for the reinforcing portions 16 to support most of the mass of the main body portion 14, from the viewpoint of easily ensuring the required strength, it is preferable that the intervals of the reinforcing portions 16 are 15 mm or less as described above. For example, the reinforcing portions 16 that reinforce the cavity portion 15 extending in the horizontal direction correspond to this case. On the other hand, when the main body portion 14 can partially support its own mass, the upper limit of the suitable range of the intervals of the reinforcing portions 16 can be a value greater than 15 mm. This is because when the main body portion 14 can partially support its own mass, the burden on the reinforcing portions 16 is reduced, and thus the installation density of the reinforcing portions 16 can be relatively small. For example, the reinforcing portions 16 that reinforce the cavity portion 15 extending in the vertical direction or the diagonal direction correspond to this case.

[0049] 〔Method of molding the joint〕 The joint 1 according to the present embodiment can be molded using, for example, a three-dimensional printing apparatus. Hereinafter, as an embodiment of the manufacturing method according to the present invention, a molding method for molding the joint 1 using a three-dimensional printing apparatus will be described. The molding method according to the present embodiment includes a data creation step of creating three-dimensional data of the joint 1 and a molding step of performing additive molding of a polyvinyl chloride resin composition based on the three-dimensional data.

[0050] (1) Data creation step The data creation step is a step of creating three-dimensional data of the joint 1. The three-dimensional data is data that specifies, for a three-dimensional printing apparatus, the positions where a resin material (which is a polyvinyl chloride resin composition in the present embodiment) should be added, etc. The three-dimensional data includes information regarding the positions of the main body portion 14 and the cavity portion 15.

[0051] The mode of the information regarding the position of the reinforcing part 16 included in the three-dimensional data is not limited, but here two typical examples will be described. The first mode is the mode in which the three-dimensional data includes the information regarding the position of the reinforcing part 16. In this mode, the position where the resin material should be added to form the reinforcing part 16 will be directly specified to the three-dimensional printing apparatus. The second mode is the mode in which the three-dimensional data includes the information of the position of the cavity part 15, the thickness of the part of the main body part 14 that defines the cavity part 15, and the filling rate in the cavity part 15 (which is the volume ratio of the part occupied by the reinforcing part 16 in the volume of the cavity part 15). In this mode, the three-dimensional printing apparatus determines the position where the resin material should be added to form the reinforcing part 16 based on the above information.

[0052] The first mode and the second mode are not in an exclusive relationship. That is, in one piece of three-dimensional data, the cavity part 15 where the position of the reinforcing part 16 is specified in the first mode and the cavity part 15 where the position of the reinforcing part 16 is specified in the second mode can coexist. Generally speaking, the first mode tends to be more complicated in creating the three-dimensional data than the second mode, but it is easier to specify a complicated shape instead. Therefore, the first mode is suitable when the shape of the cavity part 15 is relatively complicated, and the second mode is suitable when the shape of the cavity part 15 is relatively simple. However, either mode is applicable regardless of the structure of the reinforcing part 16.

[0053] (2) Molding process The molding process is a process of performing additive molding of the polyvinyl chloride resin composition based on the three-dimensional data using a three-dimensional printing apparatus. The main body part 14 is formed in such a mode that the polyvinyl chloride resin composition is added to the location specified as the position of the main body part 14 in the three-dimensional data.

[0054] When the position of the reinforcing part 16 is specified in the above first mode, the formation of the reinforcing part 16 is performed in the same manner as the formation of the main body part 14. That is, the reinforcing part 16 is formed in such a mode that the polyvinyl chloride resin composition is added to the location specified as the position of the reinforcing part 16 in the three-dimensional data.

[0055] When the position of the reinforcing portion 16 is specified in the above-described second aspect, the reinforcing portion 16 is formed through the following two-step procedure. In the first step, information regarding the position of the reinforcing portion 16 disposed in the cavity portion 15 is generated based on the information regarding the position and the filling rate of the cavity portion 15 included in the three-dimensional data. This arithmetic processing is performed, for example, by a three-dimensional printing apparatus. In the second step, the main body portion 14 and the reinforcing portion 16 are formed based on the information regarding the position of the main body portion 14 included in the three-dimensional data and the information regarding the position of the reinforcing portion 16 generated in the first step. The mode of this step is the same as that when the position of the reinforcing portion 16 is specified in the first aspect.

[0056] 〔Modification Example〕 The resin molded body according to the present invention is not limited to the joint 1 which is the 90° elbow joint exemplified above. As a first modification example of the resin molded body according to the present invention, a joint 2 which is a T-shaped joint is shown (FIGS. 4 and 5). The joint 2 includes three receiving ports 21 to which pipes are respectively connected, and a body portion 22 that connects the three receiving ports 21. The receiving ports 21 and the body portion 22 have a flow path 23 through which fluid flows, and a three-way pipe in which the fluid branches or merges can be formed. The joint 2 is also an example of a pipe member.

[0057] Also in the joint 2 according to the first modification example, the portion that defines the flow path 23 has a main body portion 24, a cavity portion 25 that is isolated from the outside by the main body portion 24, and a reinforcing portion 26 disposed in the cavity portion 25. In this modification example, an example in which the reinforcing portion 26 has a honeycomb structure is shown.

[0058] As a second modification example of the resin molded body according to the present invention, a pipe 3 is shown (FIGS. 6 to 8). The pipe 3 is a cylindrical molded body and has a flow path 31 inside. The portion that defines the flow path 31 of the pipe 3 has a main body portion 32, a cavity portion 33 that is isolated from the outside by the main body portion 32, and a reinforcing portion 34 disposed in the cavity portion 33. The cavity portion 33 and the reinforcing portion 34 extend along the longitudinal direction of the pipe 3, that is, along the flow path 31. The pipe 3 is also an example of a pipe member.

[0059] In the modified example, the structure of the reinforcing portion 34 differs depending on the longitudinal portion of the pipe 3. In the first portion (FIG. 6), the reinforcing portions 34 are arranged radially. In the second portion (FIG. 7), the reinforcing portions 34 are arranged in a lattice pattern. Since the structures of the two portions are different in the reinforcing portion 34 and the filling rate of the cavity portion 33 is smaller in the first portion than in the second portion, the first portion has higher heat insulation than the second portion. Thus, the pipe 3 has two portions with different heat insulation rates. Since conventional pipes are typically manufactured by extrusion and obtained as a continuum with the same cross-sectional shape, it has been difficult to provide portions with different structures (i.e., different heat insulation rates) partially as in this modified example. However, when the resin molded body according to the present invention is in the shape of a pipe or the like, it is not necessarily prevented from having a structure with a continuously identical cross-sectional shape.

[0060] As a third modified example of the resin molded body according to the present invention, a heat insulating plate 4 is shown (FIGS. 8 and 9). The heat insulating plate is a rectangular plate-like body in a plan view. The heat insulating plate 4 has a main body portion 41, a cavity portion 42 isolated from the outside by the main body portion 41, and a reinforcing portion 43 arranged in the cavity portion 42. In this modified example, an example in which the reinforcing portion 43 is linear is shown. As in this example, the resin molded body according to the present invention is not limited to a pipe member.

[0061] The resin molded body according to any of the modified examples can be molded using a three-dimensional printing apparatus, similarly to the joint 1 according to the embodiment. Also, in any case of the resin molded body, the resin molded body can be obtained through a data creation step of creating three-dimensional data of the resin molded body and a molding step of performing additive molding of a polyvinyl chloride resin composition based on the three-dimensional data.

[0062] 〔Other Embodiments〕 Regarding other configurations as well, it should be understood that all the embodiments disclosed in this specification are illustrative in all respects and the scope of the present invention is not limited thereby. Those skilled in the art will easily understand that appropriate modifications can be made without departing from the spirit of the present invention. Therefore, other embodiments modified without departing from the spirit of the present invention are naturally included in the scope of the present invention.

Example

[0063] Hereinafter, the present invention will be further described by showing examples. However, the following examples do not limit the present invention.

[0064] (1) Evaluation of heat insulation 〔Preparation of test piece〕 Regarding the heat insulation plate according to the third modification example (FIGS. 8 and 9), a plurality of test pieces with modified cavity creation conditions were prepared as each example. The outer dimensions of each test piece were 100 mm in length, 100 mm in width, and 12 mm in thickness. The cavity was provided so as to be located at the center of the test piece in any of the vertical direction, horizontal direction, and thickness direction. Each test piece was prepared according to the method of carrying out the molding process in the second aspect among the molding methods according to the above-described embodiment. The polyvinyl chloride resin composition used was the same as that in the above-described embodiment.

[0065] (Example 1-1) As the three-dimensional data for Example 1-1, three-dimensional data having information on the position of the cavity, the thickness of the main body portion defining the cavity, and the filling rate of the cavity was created. In Example 1-1, the thickness of the main body portion defining the cavity was 0.9 mm, and the filling rate of the cavity was 20%. The three-dimensional data was input into a three-dimensional printing device for molding, and a test piece with dimensions according to the three-dimensional data was obtained. The thickness of the cavity in the obtained test piece was 10.2 mm.

[0066] (Example 1-2) A test piece of Example 1-2 was obtained in the same manner as in Example 1-1 except that the filling rate of the cavity was 40%. The thickness of the cavity in the obtained test piece was 10.2 mm.

[0067] (Examples 1-3) Test pieces of Example 1-3 were obtained in the same manner as in Example 1-1, except that the filling rate of the cavity was 60%. The thickness of the cavity in the obtained test pieces was 10.2 mm.

[0068] (Examples 1-4) Test pieces of Example 1-4 were obtained in the same manner as in Example 1-1, except that the filling rate of the cavity was 80%. The thickness of the cavity in the obtained test pieces was 10.2 mm.

[0069] (Examples 1-5) Test pieces of Example 1-5 were obtained in the same manner as in Example 1-1, except that the thickness of the main body portion defining the cavity was 1.5 mm. The thickness of the cavity in the obtained test pieces was 9.0 mm.

[0070] (Examples 1-6) Test pieces of Example 1-6 were obtained in the same manner as in Example 1-1, except that the thickness of the main body portion defining the cavity was 2.1 mm. The thickness of the cavity in the obtained test pieces was 7.8 mm.

[0071] (Examples 1-7) Test pieces of Example 1-7 were obtained in the same manner as in Example 1-1, except that the thickness of the main body portion defining the cavity was 2.7 mm. The thickness of the cavity in the obtained test pieces was 6.6 mm.

[0072] (Examples 1-8) Test pieces of Example 1-8 were obtained in the same manner as in Example 1-1, except that the thickness of the main body portion defining the cavity was 3.3 mm. The thickness of the cavity in the obtained test pieces was 5.4 mm.

[0073] 〔Evaluation〕 A test piece related to an example to be evaluated was placed on a hot plate with a 100 mm square surface as the ground plane, and the hot plate was heated to a set temperature of 80°C. As a control sample, a plate piece (made of polyvinyl chloride resin) having the same outer dimensions as the test piece related to each example and no cavity was prepared and placed on the hot plate in the same manner as the test piece. Thermocouples were installed on the opposing surfaces (100 mm square surfaces) of the ground planes of both the test piece and the control sample to measure the surface temperature. Sixty minutes after the start of heating, the surface temperatures of the test piece and the control sample were read, and the temperature difference was determined.

[0074] For each test piece related to Examples 1-1 to 1-8, the conditions for creating the cavity and the temperature difference from the control sample are shown in Table 1. In the tests of all examples, the surface temperature of the control sample was in the range of 50 to 55°C.

[0075] For all examples, in the test piece having a cavity, the surface temperature was lower than that of the control sample having no cavity. It can be seen that the test piece having a cavity inside functioned as a heat insulating material. From Examples 1-1 to 1-4, it was confirmed that the lower the filling rate of the cavity, the greater the temperature difference from the control sample, that is, the higher the heat insulation performance. From Examples 1-1 and 1-5 to 1-8, it was confirmed that the greater the thickness of the cavity, the greater the temperature difference from the control sample, that is, the higher the heat insulation performance.

[0076] Table 1: Evaluation of heat insulation performance

Table 1

[0077] (2) Evaluation of the resin composition (Formulation of the resin composition) Filaments for three-dimensional laminated modeling were prepared by blending various additives with polyvinyl chloride resin, and their respective thermal stabilities were evaluated. For PVC, Kanevinyll S1006 (manufactured by Kaneka Corporation) was used. The formulations of each example are listed in Table 2 shown below.

[0078] In Examples 2-1 to 2-3, a liquid tin-based stabilizer (AT5300 (manufactured by Nitto Kasei Co., Ltd.)), a solid tin-based stabilizer (TVS-8813 (manufactured by Nitto Kasei Co., Ltd.)), a solid lubricant (EW100 (manufactured by Riken Vitamin Co., Ltd.)), a liquid lubricant (AC-316A (manufactured by Honeywell International Inc.)), and a chlorinated polyethylene resin (CPE3516: manufactured by Weihai Jinhong Polymer Co., Ltd.) were respectively blended.

[0079] Furthermore, in Examples 2-1 to 2-3, calcium stearate (NS-A: (manufactured by Nitto Kasei Co., Ltd.)), a processing aid (acrylic polymer PA40: manufactured by Kaneka Corporation), and an antioxidant (hindered phenol-based AO-60P: manufactured by ADEKA CORPORATION) were also blended. Table 2 shows the blending ratios (parts per hundred parts of rubber phr) of each additive with respect to 100 parts by weight of polyvinyl chloride.

[0080] On the other hand, in Example 2-4, the above additives were not blended, and a lead-based stabilizer (lead stearate), a reinforcing agent (methyl methacrylate-butadiene-styrene copolymer (MBS)), and an internal lubricant (oxidized polyethylene wax) were blended.

[0081] (Evaluation of Thermal Stability of Resin Composition) The thermal stability of the resin composition was evaluated by the following test method. (1) A filament is fed into a nozzle heated to 220°C. (2) The state where the nozzle is filled with the filament is maintained for a predetermined time (1 to 5 minutes). (3) After the lapse of the predetermined time, the filament is taken out from the nozzle, and the presence or absence of changes such as discoloration and charring is examined.

[0082] The evaluation results of each example are listed in Table 2 shown below. The criteria for each level of A to D described in Table 2 are as follows. Note that the presence or absence of practical problems was judged in consideration of the actual use and transactions of resin molded product such as joints. A: No change in appearance was observed before and after heating. B: Slight discoloration was observed after heating. C: Clear discoloration was observed after heating within a range where there is no practical problem. D: Discoloration to a certain extent that may cause practical problems was observed after heating.

[0083] In Example 2-1 (tin-based stabilizer: liquid + solid), discoloration occurred after 3 to 5 minutes, but remained slight after 1 minute. Also, in Example 2-2 (tin-based stabilizer: liquid + solid), discoloration occurred after 5 minutes, but there was no change after 1 minute and it remained slight after 3 minutes. Furthermore, in Example 2-3 (tin-based stabilizer: liquid), slight discoloration occurred after 5 minutes, but there was no change after 1 to 3 minutes. In Example 2-4, although the discoloration was within a practical range when the holding time was short, discoloration to a certain extent that caused practical problems was observed when the holding time was long.

[0084] From this, it was recognized that by blending a tin-based stabilizer (liquid, solid), the thermal stability (static thermal stability) of the filament is improved, and the burning and decomposition of the filament can be made difficult to occur. That is, it is preferable that the concentration of the tin-based stabilizer (solid) is 1 to 4 parts by weight with respect to 100 parts by weight of polyvinyl chloride, and more preferably 4 to 5 parts by weight.

[0085] In particular, it was found that by increasing the amount of the liquid tin-based stabilizer to 4 to 5 parts by weight, the static thermal stability is significantly improved. Since the liquid tin-based stabilizer has the properties of internal lubrication and external lubrication, an effect as a lubricant can also be expected. That is, it was considered that not only the viscosity during melt-kneading can be reduced, but also the slipperiness between the material particles can be improved, and the slipperiness with the inner surface of the nozzle existing on the surface of the material can be improved.

[0086] Table 2: Evaluation of the resin composition

Table 2

Industrial Applicability

[0087] The present invention can be used for piping members such as joints and pipes, and heat insulating materials of various shapes.

Explanation of Signs

[0088] 1: Joint 11: Socket 12: Elbow part 13: Flow path 14: Main body part 15: Cavity part 16: Reinforcement part 17: Unit cavity

Claims

1. A resin molded body comprising a polyvinyl chloride resin composition, a main body portion, a cavity portion isolated from the outside by the main body portion, and a reinforcing portion disposed in the cavity portion and connected to the main body portion at least at two locations.

2. The resin molded body according to claim 1, which is a pipe member capable of forming a pipe through which a fluid flows.

3. The cavity portion is provided around at least a part of a flow path through which the fluid flows, and a plurality of the reinforcing portions are provided in both a direction along the flow path and a direction away from the flow path. The resin molded body according to claim 2.

4. The cavity portion has unit cavities partitioned by a plurality of the reinforcing portions, and the interval between the plurality of the reinforcing portions in the unit cavity is 0.5 mm or more and 15 mm or less. The resin molded body according to claim 1.

5. The resin molded body according to claim 1, wherein the polyvinyl chloride resin composition contains a polyvinyl chloride resin and a tin-based stabilizer containing a tin compound.

6. The resin molded body according to claim 5, wherein the polyvinyl chloride resin composition contains 1 to 8 parts by weight of a tin-based stabilizer with respect to 100 parts by weight of the polyvinyl chloride resin.

7. The resin molded body according to claim 5, wherein the tin-based stabilizer contains at least a liquid.

8. A molding method for molding a resin molded body comprising a main body portion, a cavity portion isolated from the outside by the main body portion, and a reinforcing portion disposed in the cavity portion and connected to the main body portion at least at two locations, and containing a polyvinyl chloride resin composition, using a three-dimensional printing apparatus, a data creation step of creating three-dimensional data of the resin molded body, the three-dimensional data including information regarding at least the position of the main body portion and the position of the cavity portion, and a molding step of performing additive molding of the polyvinyl chloride resin composition based on the three-dimensional data using the three-dimensional printing apparatus, wherein in the molding step, the cavity portion is formed as a location where the main body portion and the reinforcing portion do not exist by forming the main body portion and the reinforcing portion based on the three-dimensional data.

9. The molding method according to claim 8, wherein the three-dimensional data further includes information regarding the position of the reinforcing portion.

10. The three-dimensional data further includes information regarding the position and filling rate of the cavity portion, and the molding step is A first step of generating information regarding the position of the reinforcing part arranged in the cavity part based on the information regarding the position and filling rate of the cavity part included in the three-dimensional data; A forming method according to claim 8, comprising: a second step of forming the main body part and the reinforcing part based on the information regarding the position of the main body part included in the three-dimensional data and the information regarding the position of the reinforcing part generated in the first step. **Claim 11** The forming method according to claim 10, wherein the three-dimensional data further includes information regarding the thickness of a portion of the main body part that defines the cavity part.

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