Method for manufacturing resin compositions

Abstract

To recycle a resin section containing hard polyvinyl chloride as a main component, and easily produce a resin composition of soft polyvinyl chloride.SOLUTION: A method for producing a resin composition produces a resin composition of soft polyvinyl chloride using a resin section containing hard polyvinyl chloride as a main component in a raw material. A method for producing a resin composition includes: a crushing step of crushing a resin section and forming a crushed material; and a mixing step of kneading the crushed material, a pellet made of soft polyvinyl chloride and a plasticizer while heating, and producing a resin composition in which the crushed material, the pellet, and the plasticizer are mixed.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method for producing a resin composition for producing a resin composition of soft polyvinyl chloride.

Background Art

[0002] In fittings such as resin windows, resin profiles mainly composed of rigid polyvinyl chloride are used. The resin profile is produced by heating and melting a resin material of rigid polyvinyl chloride and extruding the melted resin material. When such a resin profile is recycled to produce a resin composition of soft polyvinyl chloride, for example, a pulverized material obtained by pulverizing the resin profile and a liquid plasticizer are kneaded, and the rigid polyvinyl chloride of the pulverized material is softened by the plasticizer to produce a resin composition of soft polyvinyl chloride.

[0003] However, in the resin profile after production, the resin particles are crushed by extrusion molding, and almost no voids remain in the resin particles that existed before extrusion molding. Along with this, during the kneading of the pulverized material of the resin profile and the plasticizer, it becomes difficult for the plasticizer to penetrate into the pulverized material, and the pulverized materials become slippery with the plasticizer. Therefore, it becomes difficult to knead the pulverized material of the resin profile and the plasticizer, and it becomes difficult to soften the rigid polyvinyl chloride of the pulverized material with the plasticizer. On the other hand, conventionally, a method for producing a vinyl chloride-based resin composition by kneading a pulverized product of a rigid vinyl chloride-based resin molded product, a plasticizer, and an inorganic filler with a heating kneader is also known (see Patent Document 1).

[0004] In the conventional method for manufacturing vinyl chloride resin compositions described in Patent Document 1, the plasticizer is absorbed by an inorganic filler, and the plasticizer is kneaded together with the inorganic filler into the pulverized material. However, because an inorganic filler is required for the absorption of the plasticizer, the amount of plasticizer that can be added is limited, which may make it difficult to manufacture a soft vinyl chloride resin composition. Furthermore, increasing the amount of plasticizer added requires increasing the amount of inorganic filler added, which may affect the physical properties of the vinyl chloride resin composition. Since the amount of plasticizer added depends on the type of inorganic filler, the design of the vinyl chloride resin composition may also be limited. Therefore, there is room for improvement in the conventional method for manufacturing vinyl chloride resin compositions from the viewpoint of easily manufacturing vinyl chloride resin compositions. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Patent No. 5446104 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] The present invention has been made in view of the above-mentioned conventional problems, and its purpose is to easily produce a flexible polyvinyl chloride resin composition by recycling a resin profile mainly composed of rigid polyvinyl chloride. [Means for solving the problem]

[0007] The present invention A method for producing a resin composition of flexible polyvinyl chloride using a resin profile mainly composed of rigid polyvinyl chloride as a raw material, A grinding step of grinding the aforementioned resin profile to form a pulverized material, A mixing step of kneading the pulverized material, pellets made of soft polyvinyl chloride, and a plasticizer while heating them to produce the resin composition in which the pulverized material, pellets, and plasticizer are mixed, It has, In the mixing step, 1 to 30 parts by weight of the pellets are added to 100 parts by weight of the crushed material. The mixing step includes: dispersing the pulverized material and the pellets, kneading the pulverized material and the pellets while heating them to produce a mixture of the pulverized material and the pellets; adding the plasticizer to the mixture of the pulverized material and the pellets, kneading the mixture of the pulverized material and the pellets and the plasticizer while heating them to produce the resin composition; This is a method for producing a resin composition having [a certain characteristic]. [Effects of the Invention]

[0008] According to the present invention, a resin composition of flexible polyvinyl chloride can be easily produced by recycling a resin profile mainly composed of rigid polyvinyl chloride. [Brief explanation of the drawing]

[0009] [Figure 1] This flowchart shows the manufacturing procedure for the flexible polyvinyl chloride resin composition of this embodiment. [Figure 2] This diagram schematically shows the state of each stage in the manufacturing process of the flexible polyvinyl chloride resin composition of this embodiment. [Figure 3] This figure shows an example of a pulverized material that is kneaded by the heating kneader of this embodiment. [Figure 4] This figure shows another example of the resin profile of this embodiment. [Figure 5] These are the stress-strain curves for the comparative example and the example. [Modes for carrying out the invention]

[0010] One embodiment of a method for producing the resin composition of the present invention will be described with reference to the drawings. In the resin composition manufacturing method of this embodiment, a resin profile mainly composed of rigid polyvinyl chloride is used as a raw material to manufacture a resin composition of flexible polyvinyl chloride. This allows the manufactured resin profile to be reused, recycled into a new resin composition, and then a new resin composition to be generated.

[0011] Figure 1 is a flowchart showing the manufacturing procedure (process) of the flexible polyvinyl chloride resin composition of this embodiment. Figure 2 is a schematic diagram showing the state of each stage in the manufacturing process of the flexible polyvinyl chloride resin composition of this embodiment.

[0012] As shown in the figure, the discarded resin profile 10 (see Figure 2A) is recovered (S101 in Figure 1). The resin profile 10 is a profile (extruded profile) formed by resin extrusion molding. The resin is rigid polyvinyl chloride, and the resin profile 10 is a rigid polyvinyl chloride profile made of rigid polyvinyl chloride. The rigid polyvinyl chloride is polyvinyl chloride (PVC) without plasticizers, although other components (for example, various stabilizers and modifiers) may be mixed with the polyvinyl chloride. Note that Figure 2A shows a cross-section perpendicular to the longitudinal direction of the resin profile 10.

[0013] Here, the resin profile 10 is a molded resin product used in resin windows, which are building fixtures. A resin window has a resin frame and a sash that includes a resin frame, and the resin frame and resin frame are each made of the resin profile 10. In addition, the resin profile 10 is made from scraps of resin profile 10 from resin windows. The scraps of resin profile 10 are, for example, scraps from the resin window manufacturing site or scraps collected as market waste. On the other hand, the resin profile 10 may also be discarded resin profile 10.

[0014] Next, the recovered resin profile 10 is crushed by a crusher to form crushed resin profile 10 material 20 (see Figure 2B) (S102 in Figure 1). The crusher is, for example, an impact crusher. If the resin profile 10 is long or large, it is cut or otherwise modified to a size that can be crushed by the crusher before being crushed by the crusher. Alternatively, the resin profile 10 may be crushed in two stages. In this case, the resin profile 10 is roughly crushed by a first-stage coarse crusher, and then the coarse crushed material 20 is crushed into fine crushed material 20 by a second-stage fine crusher. In this way, crushed resin profile 10 material 20 is produced.

[0015] The resin molding 10 is a part of the raw material of a resin composition of soft polyvinyl chloride. Soft polyvinyl chloride is polyvinyl chloride mixed with a plasticizer and contains the plasticizer. Also, the resin composition is a composition mainly composed of soft polyvinyl chloride and serves as the raw material for a molded product of soft polyvinyl chloride. The plasticizer is an additive that imparts flexibility to rigid polyvinyl chloride and softens rigid polyvinyl chloride.

[0016] Examples of the plasticizer include phthalate plasticizers such as dibutyl phthalate (DBP), diisodecyl phthalate (DIDP), bis(2-ethylhexyl) phthalate (DOP), butyl benzyl phthalate (BBP), diisononyl phthalate (DINP), etc., aliphatic dibasic acid ester plasticizers such as tris(2-ethylhexyl) trimellitate (TOTM), bis(2-ethylhexyl) adipate (DOA), diisononyl adipate (DINA), dicyclohexyl adipate (DIDA), dibutyl sebacate (DBS), etc., phosphate ester plasticizers such as tris(2-ethylhexyl) phosphate (TOP), triphenyl phosphate (TPP), etc., or plasticizers such as polyesters, epoxidized soybean oil.

[0017] After the resin molding 10 is pulverized, the pulverized material 20 of the resin molding 10, pellets 30 made of soft polyvinyl chloride, and a liquid plasticizer 40 (see Fig. 2C) are kneaded while being heated by a heat kneader to produce a resin composition of soft polyvinyl chloride in which the pulverized material 20, pellets 30, and plasticizer 40 are mixed (S103 in Fig. 1). The heat kneader is, for example, a Banbury mixer, a kneader, or a Brabender, and applies a shearing force to the kneaded material during kneading. By the heat kneader, the pulverized material 20, pellets 30, and plasticizer 40 are heated at a predetermined temperature and kneaded at a predetermined temperature.

[0018] The pellet 30 is a granular material of soft polyvinyl chloride formed into granules, and is mainly composed of soft polyvinyl chloride. The resin composition is a mixture in which the crushed material 20 made of rigid polyvinyl chloride, the pellet 30 made of soft polyvinyl chloride, and the plasticizer 40 are mixed, and is made of soft polyvinyl chloride. The soft polyvinyl chloride is produced by mixing the rigid polyvinyl chloride contained in the crushed material 20, the soft polyvinyl chloride contained in the pellet 30, and the plasticizer 40.

[0019] When the crushed material 20 of the resin molded article 10 is 100 parts by weight (phr), the pellet 30 is 1 to 30 parts by weight, and the plasticizer 40 is 10 to 60 parts by weight. Thus, 1 to 30 parts by weight of the pellet 30 is added and kneaded with respect to 100 parts by weight of the crushed material 20, and 10 to 60 parts by weight of the plasticizer 40 is added and kneaded.

[0020] The respective parts by weight of the pellet 30 and the plasticizer 40 added to the crushed material 20 are adjusted to adjust the concentration of the plasticizer (for example, mass percentage concentration) contained in the resin composition of the soft polyvinyl chloride and the hardness of the resin composition. The concentration of the plasticizer contained in the pellet or pellets 30 made of soft polyvinyl chloride varies. Therefore, corresponding to the concentration of the plasticizer contained in the pellet 30, the respective parts by weight of the pellet 30 and the plasticizer 40 with respect to the crushed material 20 are adjusted to adjust the concentration of the plasticizer contained in the resin composition to the target concentration. Thereby, the hardness of the resin composition is adjusted to the target hardness.

[0021] FIG. 3 is a diagram showing an example of the crushed material 20 kneaded by the heat kneader of the present embodiment. As shown in the figure, crushing the resin profile 10 forms crushed material 20 of various shapes and with a maximum dimension R. The maximum dimension R of the crushed material 20 is the dimension of the largest part of the outer shape of each crushed material 20. The maximum dimension R of the crushed material 20 used for kneading is 15 mm or less. Therefore, when crushing the resin profile 10, the resin profile 10 is crushed so that the maximum dimension R of the crushed material 20 is 15 mm or less. Alternatively, after crushing the resin profile 10, crushed material 20 with a maximum dimension R larger than 15 mm is separated and removed using a separation device or the like, and crushed material 20 with a maximum dimension R of 15 mm or less is selected. The crushed material 20 with a maximum dimension R of 15 mm or less is kneaded with pellets 30 and plasticizer 40.

[0022] When kneading and mixing the crushed material 20 of the resin profile 10, the pellets 30 made of flexible polyvinyl chloride, and the plasticizer 40, first, the crushed material 20 and the pellets 30 are heated and kneaded in a heating kneader to produce a mixture of the crushed material 20 and the pellets 30 (S103-1 in Figure 1). The mixture of the crushed material 20 and the pellets 30 is an intermediate mixture of the crushed material 20 and the pellets 30, and is produced in an intermediate stage in the production of the final mixture, the flexible polyvinyl chloride resin composition. The crushed material 20 and the pellets 30 are completely mixed to produce a mixture of the crushed material 20 and the pellets 30. Since the crushed material 20 made of rigid polyvinyl chloride and the pellets 30 made of flexible polyvinyl chloride are both polyvinyl chloride, they mix easily with each other and can be easily kneaded.

[0023] Next, a plasticizer 40 is added to the mixture of crushed material 20 and pellets 30. In this state, the mixture of crushed material 20 and pellets 30 and the plasticizer 40 are heated and kneaded in a heating kneader to produce a flexible polyvinyl chloride resin composition in which the mixture of crushed material 20 and pellets 30 and the plasticizer 40 is mixed (S103-2 in Figure 1).

[0024] The mixture of crushed material 20 and pellets 30 contains the plasticizer contained in the flexible polyvinyl chloride pellets 30. The plasticizer contained in the mixture of crushed material 20 and pellets 30 and the added plasticizer 40 are both plasticizers and therefore readily mix with each other. As a result, the plasticizer 40 mixes easily with the mixture of crushed material 20 and pellets 30 via the plasticizer and can be easily incorporated into the mixture. The incorporation of the plasticizer 40 softens the mixture of crushed material 20, pellets 30, and plasticizer 40, producing a flexible polyvinyl chloride resin composition.

[0025] Here, the mixture of crushed material 20, pellets 30, and plasticizer 40 is a mixture of crushed material 20 and pellets 30 with the plasticizer mixed in. As the mixing of the plasticizer 40 into the mixture progresses, the mixture gradually softens, its viscosity gradually decreases, and it becomes difficult to mix. This slows down the mixing process. Therefore, during the mixing of the mixture, the heating temperature of the mixture is lowered while mixing. In response to the decrease in viscosity of the mixture, the heating temperature is gradually lowered to adjust the viscosity of the mixture and suppress the decrease in viscosity. By lowering the heating temperature, the viscosity of the mixture is adjusted to a viscosity suitable for mixing, and the mixing process progresses.

[0026] The mixture of crushed material 20, pellets 30, and plasticizer 40 is mixed using a heating kneader while gradually lowering the heating temperature of the mixture from a first temperature to a second temperature. The first temperature is the temperature before the heating temperature of the mixture is lowered, and the second temperature is the temperature at which the heating temperature of the mixture is lowered. The first temperature is 180-200°C. The second temperature is lower than the first temperature, 150-170°C. In this case, the first temperature is 190°C and the second temperature is 160°C.

[0027] The mixture is kneaded while being heated at a first temperature, and during the kneading process, the heating temperature of the mixture is gradually lowered from the first temperature. The mixture is then kneaded while gradually lowering the heating temperature from the first temperature to the second temperature, and the decrease in heating temperature is stopped when the heating temperature of the mixture reaches the second temperature. After that, the heating temperature of the mixture is maintained at the second temperature, and the mixture is kneaded while being heated at the second temperature until the kneading process is complete.

[0028] After the production of the flexible polyvinyl chloride resin composition is completed by kneading the mixed materials, the molten resin composition is discharged from the heating kneader and passed between parallel rolls (S104 in Figure 1). At this time, the resin composition is compressed by passing it between the outer surfaces of two or more opposing rolls. Subsequently, the resin composition is extruded using an extrusion molding machine, and the extruded resin composition is sequentially cut to form flexible polyvinyl chloride pellets (S105 in Figure 1). After that, flexible polyvinyl chloride molded products are formed using the flexible polyvinyl chloride pellets (S106 in Figure 1). Flexible polyvinyl chloride molded products are, for example, airtight materials and gaskets used in building fixtures.

[0029] In the resin composition manufacturing method described above, by adding flexible polyvinyl chloride pellets 30 to the raw materials for the flexible polyvinyl chloride resin composition, in addition to the crushed resin profile material 10 20 and plasticizer 40, the plasticizer 40 is made more easily compatible with the mixture, allowing the plasticizer to be smoothly mixed into the mixture. Therefore, a flexible polyvinyl chloride resin composition can be easily manufactured by recycling a resin profile material 10 that mainly consists of rigid polyvinyl chloride. Furthermore, the concentration of plasticizer in the resin composition can be increased, and the range of hardness of the resin composition that can be manufactured can be broadened.

[0030] By kneading the crushed material 20 and pellets 30 before adding the plasticizer 40, the crushed material 20 and pellets 30 can be easily mixed. Furthermore, by smoothly mixing the plasticizer 40 into the mixture of crushed material 20 and pellets 30, the manufacturing efficiency of the flexible polyvinyl chloride resin composition can be improved. By suppressing slippage caused by the plasticizer 40, the mixtures at each stage can be easily kneaded, and the time required for kneading the mixtures can also be shortened.

[0031] By kneading the mixture of crushed material 20, pellets 30, and plasticizer 40 while lowering the heating temperature, the decrease in viscosity of the mixture can be suppressed, ensuring that the crushed material 20, pellets 30, and plasticizer 40 are thoroughly mixed. Furthermore, a flexible polyvinyl chloride resin composition can be efficiently manufactured. When the resin profile 10 used as a raw material for the resin composition is scrap of resin profile 10 (in this case, resin profile 10 for a resin window), the scrap of resin profile 10 can be recycled, thereby reducing the cost of the resin composition.

[0032] The heating temperature of the mixture of crushed material 20, pellets 30, and plasticizer 40 is lowered from the first temperature to the second temperature. When heating the mixture at the first temperature, if the first temperature is higher than 200°C, the viscosity of the mixture will be low, which may make it difficult to mix. If the first temperature is lower than 180°C, the viscosity of the mixture will be high, which may make it difficult to mix. In contrast, if the first temperature is within the range of 180 to 200°C (180°C or higher and 200°C or lower), the mixture will have a viscosity that makes it easy to mix, allowing the mixing to proceed smoothly.

[0033] When heating the mixture to the second temperature, if the second temperature is higher than 170°C, the viscosity of the mixture will decrease, making it difficult to mix. If the second temperature is lower than 150°C, the viscosity of the mixture will increase, making it difficult to mix. In contrast, if the second temperature is within the range of 150 to 170°C (150°C or higher and 170°C or lower), the mixture will have a viscosity that makes it easy to mix, allowing the mixing process to proceed smoothly. The first temperature is more preferably within the range of 185 to 195°C, and the second temperature is more preferably within the range of 155 to 165°C. This allows the mixing of the mixture to proceed more smoothly at each stage.

[0034] When the maximum dimension R of the crushed material 20 of the resin profile 10 is greater than 15 mm, the larger size of the crushed material 20 may make it difficult to mix the crushed material 20 with the pellets 30. In contrast, when the maximum dimension R of the crushed material 20 is 15 mm or less, the crushed material 20 and pellets 30 can be dispersed and mixed smoothly. It is more preferable that the maximum dimension R of the crushed material 20 is 8 mm or less. This allows for smoother mixing of the crushed material 20 and pellets 30.

[0035] When the amount of pellets 30 is less than 1 part by weight per 100 parts by weight of crushed material 20, the total amount of plasticizer contained in the pellets 30 added to the crushed material 20 will be small, which may make it difficult for the plasticizer 40 to be mixed into the mixture. Also, when the amount of pellets 30 is more than 30 parts by weight per 100 parts by weight of crushed material 20, the ratio of pellets 30 to crushed material 20 will increase, which may make it difficult for the pellets 30 to be mixed into the crushed material 20. On the other hand, when the amount of pellets 30 is in the range of 1 to 30 parts by weight (1 part by weight or more and 30 parts by weight or less) per 100 parts by weight of crushed material 20, it is possible to easily mix the pellets 30 into the crushed material 20 and the plasticizer 40 into the mixture. It is more preferable that the amount of pellets 30 is 5 to 10 parts by weight per 100 parts by weight of crushed material 20. This makes it easier to mix the pellets 30 with the crushed material 20, and to mix the plasticizer 40 with the mixed material.

[0036] When the amount of plasticizer 40 is less than 10 parts by weight per 100 parts by weight of crushed material 20, there is a risk that the resin composition of flexible polyvinyl chloride may not be sufficiently softened. Also, when the amount of plasticizer 40 is more than 60 parts by weight per 100 parts by weight of crushed material 20, the plasticizer 40 may not be easily mixed into the mixture, and there is a risk that the plasticizer 40 may remain in liquid form. In contrast, when the amount of plasticizer 40 is within the range of 10 to 60 parts by weight (10 parts by weight or more and 60 parts by weight or less) per 100 parts by weight of crushed material 20, the plasticizer 40 can be reliably mixed into the mixture, and the resin composition can be sufficiently softened. It is more preferable that the amount of plasticizer 40 is 20 to 40 parts by weight per 100 parts by weight of crushed material 20. This allows the plasticizer 40 to be mixed into the mixture even more reliably, and the resin composition can be stably softened.

[0037] Figure 4 shows another example of the resin profile 10 of this embodiment, and shows a cross-section perpendicular to the longitudinal direction of the resin profile 10. As shown in the figure, the resin profile 10 here has a main body 11 mainly composed of rigid polyvinyl chloride and an attachment 12 mainly composed of flexible polyvinyl chloride. The attachment 12 is a flexible part attached to the rigid main body 11, and is formed to be smaller than the main body 11 and protrudes from the main body 11. When crushing the resin profile 10 (S102 in Figure 1), the resin profile 10 with the attachment 12 attached to the main body 11 is crushed without removing the attachment 12 from the main body 11 to form crushed resin profile 10 material 20.

[0038] The resulting crushed material 20 includes crushed material 20 of only the main body 11, crushed material 20 of only the accessory part 12, and crushed material 20 containing both the main body 11 and the accessory part 12. The crushed material 20 is kneaded with pellets 30 and a plasticizer 40 to produce a flexible polyvinyl chloride resin composition. In this way, the resin profile 10 can be easily recycled without separating the main body 11, which is made of rigid polyvinyl chloride, from the accessory part 12, which is made of flexible polyvinyl chloride.

[0039] Next, examples and comparative examples of methods for producing flexible polyvinyl chloride resin compositions will be described, but the present invention is not limited to the following examples. In the examples, flexible polyvinyl chloride resin compositions were produced according to the flowchart shown in Figure 1. For comparison with the examples, in the comparative examples, flexible polyvinyl chloride resin compositions were produced by kneading the crushed material 20 and the plasticizer 40 without adding the pellets 30.

[0040] [Table 1]

[0041] Table 1 shows the respective parts by weight of the crushed material 20, the flexible polyvinyl chloride pellets 30, and the plasticizer 40 for the resin profile 10 in two comparative examples (Comparative Examples 1 and 2) and four examples (Examples 1 to 4). The parts by weight of pellet 30 and plasticizer 40 are relative to 100 parts by weight of crushed material 20. Furthermore, the pellet 30 used in Examples 1-4 is the same pellet 30, and the plasticizer 40 is a phthalate ester plasticizer of bis(2-ethylhexyl) phthalate (DOP).

[0042] Test specimens were prepared using the resin composition after manufacturing, and tensile tests were performed on the specimens. The hardness of the test specimens was also measured. For the tensile tests, the test specimens were subjected to tensile testing in accordance with the Japanese Industrial Standard (JIS K 6251:2017) "Vulcanized rubber and thermoplastic rubber - Method for determining tensile properties," and the stress-strain curve (SS curve) of the test specimens was determined. For the hardness measurement, the durometer A hardness of the test specimens was measured in accordance with the Japanese Industrial Standard (JIS K 6253-3:2012) "Vulcanized rubber and thermoplastic rubber - Method for determining hardness - Part 3: Durometer hardness."

[0043] Figure 5 shows the stress-strain curves for Comparative Examples 1 and 2 and Examples 1 to 4. The symbols H1, H2, F1, F2, F3, and F4 attached to the six stress-strain curves in Figure 5 correspond to the symbols shown in Table 1, indicating that they are the stress-strain curves for Comparative Example 1, Comparative Example 2, Example 1, Example 2, Example 3, and Example 4, respectively. As shown in the figure, the resin compositions of Examples 1 to 4 were softer than the resin compositions of Comparative Examples 1 and 2. Furthermore, the tensile properties and degree of softening changed in proportion to the parts by weight of pellets 30 and plasticizer 40.

[0044] [Table 2]

[0045] Table 2 shows the hardness of Comparative Examples 1 and 2 and Examples 1 to 4. The hardness of the resin compositions in Examples 1 to 4 was lower than that of the resin compositions in Comparative Examples 1 and 2. Furthermore, the hardness changed in proportion to the parts by weight of pellets 30 and plasticizer 40.

[0046] As described above, this embodiment discloses a method for producing the resin composition described in (1) to (6) below.

[0047] (1) A method for producing a resin composition of flexible polyvinyl chloride using a resin profile mainly composed of rigid polyvinyl chloride as a raw material, A grinding step of grinding the aforementioned resin profile to form a pulverized material, A mixing step of kneading the pulverized material, pellets made of soft polyvinyl chloride, and a plasticizer while heating them to produce the resin composition in which the pulverized material, pellets, and plasticizer are mixed, A method for producing a resin composition having [the specified characteristic]. In the method for producing the resin composition described in (1), a resin composition of flexible polyvinyl chloride can be easily produced by recycling a resin profile mainly composed of rigid polyvinyl chloride.

[0048] (2) In the method for producing the resin composition described in (1), A method for producing a resin composition, comprising the mixing step of kneading the pulverized material and the pellets while heating them, and kneading the kneaded mixture of the pulverized material and the pellets and the plasticizer while heating them. In the method for producing the resin composition described in (2), the crushed material and pellets can be easily mixed by kneading them together. Furthermore, the plasticizer can be smoothly mixed into the kneaded mixture of crushed material and pellets, thereby improving the production efficiency of the flexible polyvinyl chloride resin composition.

[0049] (3) In the method for producing the resin composition described in (1) or (2), A method for producing a resin composition, comprising kneading a mixture of the pulverized material, the pellets, and the plasticizer while lowering the heating temperature during the mixing step. The method for producing the resin composition described in (3) allows for the efficient production of a flexible polyvinyl chloride resin composition by reliably mixing the crushed material, pellets, and plasticizer.

[0050] (4) In a method for producing a resin composition as described in any of (1) to (3), A method for producing a resin composition, wherein in the mixing step, 1 to 30 parts by weight of the pellets are added to 100 parts by weight of the pulverized material. The method for producing the resin composition described in (4) makes it easier to knead the pellets with the crushed material and to knead the plasticizer with the kneaded mixture.

[0051] (5) In a method for producing a resin composition as described in any of (1) to (4), A method for producing a resin composition in which the maximum size of the pulverized material is 15 mm or less in the mixing step. In the method for producing the resin composition described in (5), the crushed material and pellets can be dispersed and the crushed material and pellets can be smoothly kneaded together.

[0052] (6) In a method for producing a resin composition as described in any of (1) to (5), A method for producing a resin composition, wherein the pulverization step involves pulverizing a resin profile having a main body made primarily of rigid polyvinyl chloride and an attached part made primarily of flexible polyvinyl chloride. In the method for producing the resin composition described in (6), the resin profile can be easily recycled without separating the attached parts from the main body of the resin profile. [Explanation of Symbols]

[0053] 10... Resin profiles, 11... Main body, 12... Accessories, 20... Crushed material, 30... Pellets, 40... Plasticizer, R... Maximum dimensions.

Claims

1. A method for producing a resin composition of flexible polyvinyl chloride using a resin profile mainly composed of rigid polyvinyl chloride as a raw material, A grinding step of grinding the aforementioned resin profile to form a pulverized material, The process includes a mixing step of kneading the pulverized material, pellets made of soft polyvinyl chloride, and a plasticizer while heating them to produce the resin composition in which the pulverized material, pellets, and plasticizer are mixed, In the mixing step, 1 to 30 parts by weight of the pellets are added to 100 parts by weight of the crushed material. A method for producing a resin composition, comprising the steps of: dispersing the pulverized material and the pellets, kneading the pulverized material and the pellets while heating them to produce a mixture of the pulverized material and the pellets; and adding the plasticizer to the mixture of the pulverized material and the pellets, kneading the mixture of the pulverized material and the pellets and the plasticizer while heating them to produce the resin composition.

2. In the method for producing the resin composition described in claim 1, A method for producing a resin composition, wherein in the mixing step, the mixture of the crushed material and the pellets is mixed with the plasticizer, and the mixture is kneaded while the heating temperature is reduced.

3. In a method for producing a resin composition according to claim 1 or 2, A method for producing a resin composition in which the maximum size of the pulverized material is 15 mm or less in the mixing step.

4. In a method for producing a resin composition according to claim 1 or 2, A method for producing a resin composition, comprising grinding a resin profile having a main body made of rigid polyvinyl chloride and an attached part made of flexible polyvinyl chloride, in the grinding step.

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