Molded article of vinyl chloride-based resin composition

Abstract

The present invention provides a molded article of a vinyl chloride-based resin composition excellent in mechanical properties such as tensile elongation at break while containing two or more kinds of calcium carbonate materials having different characteristics as a filler. The molded article of a vinyl chloride-based resin composition according to the present invention is obtained by blending a vinyl chloride-based resin and a filler. The filler includes a first calcium carbonate material and a second calcium carbonate material having different aspect ratios. The first calcium carbonate material is preferably a pulverized product of scallop shells.

Description

Molded products of vinyl chloride resin compositions

[0001] The present invention relates to a molded article made of a vinyl chloride resin composition containing calcium carbonate.

[0002] Currently, CO ２ In order to reduce emissions, efforts to achieve carbon neutrality are being strengthened. ２ Controlling emissions is important.

[0003] Scallop shells are known to contain a large amount of calcium carbonate. However, although some scallop shells are used as construction materials, the majority of them are discarded, which has become a social problem.

[0004] In vinyl chloride resin compositions, calcium carbonate is sometimes added to the vinyl chloride resin as a filler. Therefore, Patent Document 1 discloses a synthetic resin that uses crushed scallop shells as a filler, aiming to reduce the amount of scallop shells that become industrial waste.

[0005] Japanese Patent Application Laid-Open No. 2004-75964

[0006] However, it has been found that molded articles made from vinyl chloride resin compositions using ground scallop shells of biological origin as a filler have lower tensile elongation at break than molded articles made using only virgin vinyl chloride resin raw materials. Molded articles using lime-derived calcium carbonate as a filler also experience a decrease in tensile elongation at break, but both fully satisfy the JIS K6741:2016 standard performance and are usable without any problems. However, the inventors have discovered that the decrease in tensile elongation at break can be suppressed by including two or more calcium carbonates with different properties in the filler.

[0007] An object of the present invention is to provide a molded article of a vinyl chloride resin composition which contains two or more types of calcium carbonate materials with different properties as fillers and which has excellent mechanical properties such as tensile elongation at break.

[0008] The molded article of the vinyl chloride resin composition of the present invention is a molded article of the vinyl chloride resin composition obtained by blending a vinyl chloride resin and a filler, wherein the filler includes a first calcium carbonate material and a second calcium carbonate material having different aspect ratios.

[0009] The first calcium carbonate material is preferably a long fiber material.

[0010] The first calcium carbonate material preferably has an aspect ratio of 2 or more.

[0011] The first calcium carbonate material preferably has a fiber length of 2 μm or more.

[0012] The second calcium carbonate material preferably has an aspect ratio of 2 or less.

[0013] The second calcium carbonate material preferably has an average particle size of 20 μm or less.

[0014] The amount of the filler is preferably 0.5 parts by mass or more and 15 parts by mass or less relative to 100 parts by mass of the vinyl chloride resin.

[0015] The filler preferably has a mass ratio of the first calcium carbonate material to the second calcium carbonate material of 1:3 to 5:1.

[0016] The first calcium carbonate material is preferably a biologically derived material.

[0017] The first calcium carbonate material is preferably pulverized scallop shells.

[0018] The second calcium carbonate material is preferably a mineral- or biological-derived material.

[0019] The molded article is preferably a pipe or a pipe joint.

[0020] The molded article of the vinyl chloride resin composition of the present invention can improve the tensile elongation at break and the secondary processability by using the first calcium carbonate material and the second calcium carbonate material having different properties as fillers. The use of calcium carbonate derived from living organisms such as scallop shells as the first calcium carbonate material can also promote carbon neutrality.

[0021] FIG. 1 is an enlarged photograph of the first calcium carbonate material.

[0022] Hereinafter, one embodiment of a molded article made from the vinyl chloride resin composition of the present invention will be described.

[0023] The vinyl chloride resin composition of the present invention is characterized in that it contains two or more types of calcium carbonate materials with different properties as fillers in a rigid vinyl chloride resin (hereinafter simply referred to as "vinyl chloride resin").

[0024] <Vinyl chloride resin> Vinyl chloride resin (PVC) is a hard synthetic resin obtained by polymerizing vinyl chloride. Vinyl chloride resin can be obtained in the form of PVC powder or pellets. It is preferable to use a vinyl chloride resin with an average degree of polymerization of 650 or more, preferably 2000 or less. If the average degree of polymerization of the vinyl chloride resin is less than 650, thermal stability and fatigue resistance tend to decrease, and if the average degree of polymerization is more than 2000, molding at a general molding temperature becomes difficult, and the vinyl chloride resin decomposes.

[0025] <Filler> The filler (filling material) is a calcium carbonate material and is contained to improve mechanical properties and secondary processability. In the present invention, two types of calcium carbonate materials are used as fillers. In this specification, one calcium carbonate material is referred to as the first calcium carbonate material and the other calcium carbonate material is referred to as the second calcium carbonate material. The first calcium carbonate material and the second calcium carbonate material are calcium carbonate materials with different properties. The different properties include, for example, shape properties (e.g., aspect ratio, fiber length) and material properties derived from (biological or mineral origin).

[0026] -First calcium carbonate material- The first calcium carbonate material is a calcium carbonate material containing long fibers having, as shape characteristics, at least an aspect ratio of 2 or more and / or a fiber length of 2 μm or more. Note that the long fibers contained in the first calcium carbonate material preferably have an aspect ratio of 3 or more and a fiber length of 3 μm or more.

[0027] The first calcium carbonate material preferably contains 5% by mass or more, and more preferably 10% by mass or more, of long fibers satisfying the above-mentioned properties. Use of the first calcium carbonate material containing long fibers improves the tensile elongation at break, and provides a material that is excellent in secondary processability and earthquake resistance.

[0028] The aspect ratio of the long fibers is preferably 12 or less, and more preferably 10 or less. The fiber length of the long fibers is preferably 18 μm or less, and more preferably 15 μm or less. Note that long fibers with an aspect ratio or fiber length greater than the above will be crushed during molding, so it is acceptable for the aspect ratio to exceed 12 and the fiber length to exceed 18 μm.

[0029] The average particle size of the first calcium carbonate material containing long fibers is preferably 15 μm or less, more preferably 10 μm or less. Particle size classification: 50% particle size (median size) is used, and the measurement method can be measured by wet (water) laser diffraction.

[0030] The first calcium carbonate material can be a material derived from a living organism having material properties. Examples of living organism-derived calcium carbonate materials include shells such as scallop shells, oyster shells, and surf clam shells. Using living organism-derived materials as calcium carbonate materials can reduce industrial waste and also promote carbon neutrality. The first calcium carbonate material can be obtained by crushing these shells. Among the exemplified shells, scallop shells are most preferably used as a living organism-derived material because they are easy to crush to obtain long fibers with an aspect ratio and fiber length that satisfy the above requirements.

[0031] - Second calcium carbonate material - The second calcium carbonate material is a calcium carbonate material having, as shape characteristics, an aspect ratio of 2 or less and / or an average particle size of 20 μm or less. The aspect ratio of the second calcium carbonate material is preferably 1 or more, more preferably 1.2 or more, and even more preferably 1.8 or less, and the average particle size is more preferably 15 μm or less, and even more preferably 10 μm or less. The average particle size was measured by the method described above. Use of the second calcium carbonate material can promote mixing of each component during mixing in the vinyl chloride resin composition, thereby improving the uniformity of the compound.

[0032] The second calcium carbonate material may be derived from a material having material properties of mineral origin or a material of biological origin. An example of a mineral-derived calcium carbonate material is limestone, which can be crushed and classified to obtain the second calcium carbonate material. An example of a biological calcium carbonate material is seashells such as scallop shells, oyster shells, and surf clam shells. Using a biological material as the calcium carbonate material can reduce industrial waste and also promote carbon neutrality. The second calcium carbonate material can be obtained by crushing these shells. Among the shells listed above, scallop shells are most preferably used as the biological material because they are easy to crush to obtain long fibers with an aspect ratio and fiber length that satisfy the above requirements.

[0033] The second calcium carbonate material may be subjected to a surface treatment, if necessary. An example of the surface treatment is a fatty acid treatment. By subjecting the second calcium carbonate material to a surface treatment, dispersibility is improved.

[0034] It is desirable that the first calcium carbonate material and the second calcium carbonate material have different particle size distributions as a shape characteristic. That is, it is desirable that a filler obtained by mixing the first calcium carbonate material and the second calcium carbonate material has two particle size peaks. For example, the first calcium carbonate material has a smaller average particle size than the second calcium carbonate material. This allows a molded product with a high tensile elongation at break to be obtained. Alternatively, the first calcium carbonate material has a larger average particle size than the second calcium carbonate material. This allows the effect of the aspect ratio to be exerted, resulting in a molded product with high tensile strength and bending strength.

[0035] The blending ratio of the first calcium carbonate material to the second calcium carbonate material in the filler is preferably 1:3 or more by mass and 5:1 or less by mass, and more preferably 1:2 or more by mass and 4:1 or less by mass.

[0036] For the sake of convenience in explaining the invention, the first calcium carbonate material and the second calcium carbonate material in the filler are described as two types of calcium carbonate material, but this is not limited thereto. The filler may be composed of two or more types of calcium carbonate material, or may be composed of a single type of calcium carbonate material with different morphological characteristics. When the filler is composed of a single type of calcium carbonate material, the first calcium carbonate material and the second calcium carbonate material may be contained from the beginning, or the first calcium carbonate material and the second calcium carbonate material may be mixed before use to form a single type of calcium carbonate material. Furthermore, the first calcium carbonate material and the second calcium carbonate material may be calcium carbonate materials with the same composition or origin.

[0037] By increasing the mass ratio of the first calcium carbonate material containing long fibers having a large aspect ratio and / or a long fiber length, a molded product with higher tensile strength can be obtained. Therefore, the preferable lower limit of the mass ratio of the first calcium carbonate material to the second calcium carbonate material is set as described above. Furthermore, when a biological material is used as the first calcium carbonate material, a larger mass ratio of the first calcium carbonate material in the filler has the advantage of contributing to the promotion of carbon neutrality.

[0038] On the other hand, if the mass ratio of the first calcium carbonate material is too large, the tensile elongation at break of the molded article decreases and secondary processability also decreases. Therefore, the preferred upper limit of the mass ratio of the first calcium carbonate material to the second calcium carbonate material in the filler is set as described above.

[0039] <Other Additives> The vinyl chloride resin composition can contain a stabilizer to improve moldability and mechanical properties. Examples of stabilizers include Ca-Zn, Ba-Zn, Sn, and Pb-based stabilizers. Among these stabilizers, Pb-based stabilizers place a heavy burden on the environment and human body, so it is desirable to use other stabilizers. Among these, Ca-Zn-based stabilizers are preferred as stabilizers because they place less burden on the environment and human body than Pb-based stabilizers, and the addition of a filler does not affect the effects on tensile strength performance and tensile elongation at break.

[0040] In addition to stabilizers, the vinyl chloride resin composition may also contain lubricants, plasticizers, colorants, modifiers, ultraviolet protection agents, flame retardants, antibacterial and antifungal agents, deodorizers, colorants, and various additives used in molding vinyl chloride resins. These additives may be added within a range that does not impair the properties of the vinyl chloride resin composition, and are preferably added in an amount of 1.5% by mass or less, more preferably 1% by mass or less, and more preferably 0.5% by mass or less, of the total amount of the vinyl chloride resin composition.

[0041] <Vinyl chloride resin composition> The vinyl chloride resin composition of the present invention can be in the form of a powder obtained by blending and kneading the above-mentioned vinyl chloride resin, a filler, and, if necessary, a stabilizer and other additives. The vinyl chloride resin composition of the present invention may also be in the form of pellets obtained by heating and molding the powder in an extruder.

[0042] The filler is preferably contained in an amount of 0.5 parts by mass or more, more preferably 1 part by mass or more, per 100 parts by mass of the vinyl chloride resin. By containing 0.5 parts by mass or more of the filler, the moldability of molded articles of the vinyl chloride resin composition can be improved. On the other hand, since the addition of an excessive amount of filler leads to a decrease in mechanical properties, the filler is preferably contained in an amount of 15 parts by mass or less, more preferably 12 parts by mass or less, per 100 parts by mass of the vinyl chloride resin.

[0043] <Molded Articles of Vinyl Chloride Resin Composition> Various molded articles of vinyl chloride resin compositions are produced by subjecting the vinyl chloride resin composition to rolling, extrusion, injection molding, blow molding, etc. Suitable molded articles include plates, pipes, and pipe joints for connecting pipes, and other uses include, but are not limited to, sashes, gutters, films, sheets, various building materials, agricultural materials, and pipe rehabilitation materials.

[0044] The molded article of the vinyl chloride resin composition of the present invention employs a calcium carbonate material consisting of the first calcium carbonate material and the second calcium carbonate material as a filler, and as shown in the examples, can have a tensile strength and tensile elongation at break that are equal to or greater than those of a molded article using only the second calcium carbonate material.

[0045] By using a biological material such as scallop shell as the first calcium carbonate material, the amount of mineral-derived calcium carbonate used in molded articles of vinyl chloride resin compositions can be reduced. Specifically, when the mass ratio of the first calcium carbonate material to the second calcium carbonate material is 1:3 or more, the substitution rate of the biologically derived first calcium carbonate material in the calcium carbonate materials used is 25% or more, which contributes to the promotion of carbon neutrality. Furthermore, the biomass content of molded articles of vinyl chloride resin compositions can be increased.

[0046] Example 1 Molded vinyl chloride resin compositions were prepared from vinyl chloride resin compositions of the invention and comparative examples, each containing the filler shown in Table 1, and the mechanical properties were compared.

[0047]

[0048] The vinyl chloride resin used was a vinyl chloride resin powder (Vinyl chloride homopolymer S1001 manufactured by Kaneka Corporation) having an average degree of polymerization of 1050 and an average particle size of 165 μm.

[0049] The fillers used were a first calcium carbonate material and a second calcium carbonate material.

[0050] The first calcium carbonate material is a pulverized product of biologically derived scallop shells, has an average particle size of 4 μm, and contains 10% by mass of long fibers with an aspect ratio of at least 3 and a fiber length of at least 3 μm. FIG. 1 is an enlarged photograph of the first calcium carbonate material. As shown in the figure, the first calcium carbonate material contains long fibers with a large aspect ratio and long fiber length in the pulverized product. The average particle size was measured using a particle size classification: 50% particle size (median diameter) and by wet (water) laser diffraction. In the present invention, the average particle size was measured using a particle analyzer SYNC manufactured by Microtrac.

[0051] As the second calcium carbonate material, crushed and classified limestone (LW600: manufactured by Shimizu Kogyo Co., Ltd., hereinafter referred to as the second calcium carbonate material) was used.

[0052] The stabilizer used was a Ca-Zn composite stabilizer, added in an amount of 2.2 parts by mass per 100 parts by mass of vinyl chloride resin. The Ca-Zn composite stabilizer is a mixture of a thermal stabilizer and a lubricant, and there are no particular restrictions on the type of additive or its component composition, as long as it has the thermal stability and lubricity appropriate for the molding method.

[0053] Powdered vinyl chloride resin compositions were prepared by adding each of the above materials to 100 parts by mass of vinyl chloride resin in the amounts shown in Table 1. Inventive Example 1-5 used the first calcium carbonate material and the second calcium carbonate material as fillers, while Comparative Example 1-7 used either the first calcium carbonate material or the second calcium carbonate material as filler.

[0054] The obtained vinyl chloride resin composition was melted while being kneaded between rolls heated to 180°C for 7 minutes using a mixing roll machine (No. 191-TM) manufactured by Yasuda Seiki Seisakusho Co., Ltd., to produce a roll sheet with a final thickness of approximately 1.0 mm. Several of the obtained roll sheets were stacked, and for Invention Examples 1-3, 5, and 6 and Comparative Examples 1-6, they were pressed at 190°C for 6 minutes (4 minutes without pressure, 15 kgf / cm) using a press machine (PEW-3030) manufactured by Kansai Roll Co., Ltd. ２ Inventive Example 4, the same roll sheet as in Inventive Example 2 was used, and the same press was used at 190°C for 5 minutes (1 minute without pressure, 50 kgf / cm) to prepare a test plate with a final thickness of 4.0 mm. ２ 2 minutes, 100 kgf / cm ２ The test plate was then pressed for 2 minutes and shaved to a final thickness of 3.0 mm.

[0055] The test plates of Examples 1-6 and Comparative Examples 1-6 were subjected to tensile tests, bending tests, and Charpy impact tests. The results are shown below and in Table 1. The measured values ​​for both the tensile tests and bending tests are the average of five test pieces. The measured values ​​for the Charpy impact test are the average of seven measurements, excluding the highest and lowest values.

[0056] <Tensile Test> The tensile test measured the yield stress and tensile elongation at break. According to JIS K6741:2016, the yield stress of molded articles made of vinyl chloride resin compositions is preferably 45 MPa or more. Referring to Table 1, all of the inventive examples had a tensile yield stress exceeding 45 MPa, and exhibited performance comparable to that of the comparative examples except for comparative examples 4 and 6. It is believed that the large filler content of 15 parts by mass in comparative examples 4 and 6 led to a decrease in the tensile yield stress. No significant difference was observed between inventive example 2 and inventive example 4, which had different press conditions.

[0057] The tensile breaking elongation, measured according to JIS K6815-1:2000, is preferably 120% or more. Referring to Table 1, all of the inventive examples have a tensile breaking elongation of 120% or more, providing good tensile breaking elongation and excellent secondary processability. Therefore, all of the inventive examples 1-6 can be applied to rigid polyvinyl chloride pipes. On the other hand, the comparative examples all have a tensile breaking elongation of less than 120%, which means that they do not have sufficient secondary processability and are unsuitable for rigid polyvinyl chloride pipes.

[0058] <Bending test> In the bending test, the elastic modulus and strength of each test piece were measured. Looking at the invention examples and comparative examples, no significant difference in elastic modulus was observed between the invention examples and comparative examples. On the other hand, the strength of the invention examples was comparable to that of the comparative examples, except for comparative examples 4 and 7. It is believed that the large filler content of 15 parts by mass in comparative examples 4 and 6 led to a decrease in elongation.

[0059] <Charpy Impact Test> The Charpy impact test was carried out in accordance with JIS K7111:2012 (V-notch). The Charpy impact value was practically 2.5 KJ / m ２ It is desirable that the value be 2.5 KJ / m or more. ２ As a result, sufficient impact resistance was obtained.

[0060] <Summary> From the above test results, all of the inventive examples have superior tensile elongation at break to those of Comparative Examples 1 to 4 in which the first biological calcium carbonate material was used alone as a filler, and have superior secondary processability to those of the comparative examples in which the second mineral-derived calcium carbonate material was used alone as a filler.

[0061] Furthermore, all of the inventive examples have superior mechanical properties to those of comparative examples 5 and 6, which use only the mineral-derived second calcium carbonate material as a filler. By mixing the mineral-derived second calcium carbonate material with the biologically derived first calcium carbonate material, all of the inventive examples can maintain tensile breaking elongation and have suitable secondary processability, while contributing to the promotion of carbon neutrality through the use of the first calcium carbonate material.

[0062] The above description of the embodiment is for the purpose of explaining the present invention, and should not be construed as limiting the invention described in the claims or narrowing its scope. Furthermore, the configuration of each part of the present invention is not limited to the above embodiment, and various modifications are possible within the technical scope described in the claims.

Claims

1. A molded article of a vinyl chloride resin composition comprising a vinyl chloride resin and a filler, the filler comprising a first calcium carbonate material and a second calcium carbonate material having different aspect ratios.

2. A molded article of a vinyl chloride resin composition according to claim 1, wherein the first calcium carbonate material is a long fiber body.

3. A molded article of a vinyl chloride resin composition according to claim 2, wherein the first calcium carbonate material has an aspect ratio of 2 or more.

4. A molded article of a vinyl chloride resin composition according to claim 3, wherein the first calcium carbonate material has a fiber length of 2 μm or more.

5. A molded article of a vinyl chloride resin composition according to claim 4, wherein the second calcium carbonate material has an aspect ratio of 2 or less.

6. A molded article of a vinyl chloride resin composition according to claim 5, wherein the second calcium carbonate material has an average particle size of 20 μm or less.

7. A molded article of a vinyl chloride resin composition according to claim 6, wherein the total number of parts of the filler is 0.5 parts by mass or more and 15 parts by mass or less per 100 parts by mass of the vinyl chloride resin.

8. The molded article of vinyl chloride resin composition according to claim 7, wherein the mass ratio of the first calcium carbonate material to the second calcium carbonate material in the filler is 1:3 to 5:

1.

9. The molded article of a vinyl chloride resin composition according to claim 8, wherein the first calcium carbonate material is a material of biological origin.

10. A molded article made of a vinyl chloride resin composition according to claim 9, wherein the first calcium carbonate material is crushed scallop shells.

11. The molded article of a vinyl chloride resin composition according to claim 10, wherein the second calcium carbonate material is a mineral-derived or biological-derived material.

12. A molded article made of a vinyl chloride resin composition according to any one of claims 1 to 11, wherein the molded article is a pipe or a pipe joint.

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