Vinyl chloride resin molded product

Abstract

In light of the fact that conventional polyvinyl chloride resin molded articles with sufficient heat resistance for products used outdoors for extended periods have not existed, the objective is to provide a polyvinyl chloride resin molded article that is less prone to softening at high temperatures. [Solution] The extruded molded article 100 has a vinyl chloride resin as its main component and is configured such that its Vicat softening temperature is 103°C or higher. As a result, compared to general vinyl chloride resin molded articles, softening and deformation at high temperatures are less likely to occur, and the molded article 100 of the present invention has the advantage of having less impact on its structure even when used in a high-temperature environment.

Description

[Technical Field]

[0001] This invention relates to a vinyl chloride resin molded article with excellent heat resistance. [Background technology]

[0002] Traditionally, polyvinyl chloride resins have been used in a wide range of applications, including machinery, electrical products, vehicles, and building materials, due to their excellent chemical and oil resistance, adjustable hardness, and low cost. For example, in the field of architecture, polyvinyl chloride resin is used for window frames to improve the thermal insulation of buildings. Furthermore, due to its good weather resistance, it is also used for outdoor materials such as decking. In the automotive sector, it is sometimes used for exterior molding materials, etc.

[0003] However, typical polyvinyl chloride resins are susceptible to temperature changes in their physical properties; they become brittle at low temperatures, but deform and lose strength at high temperatures. Furthermore, shrinkage at high temperatures can also cause structural problems.

[0004] Therefore, to use these materials in components that reach high temperatures or in products exposed to the outdoors or sunlight, measures are taken to improve their physical properties with additives or to modify their structure. For example, a technology has been developed to create a heat-resistant vinyl chloride resin composition by adding a heat-resistant enhancer to vinyl chloride resin to improve its Vicat softening temperature.

[0005] Patent Document 1 discloses a technology relating to a vinyl chloride resin composition in which a vinyl chloride resin is added, a copolymer of a vinyl chloride resin and maleimide (maleimide), and a crosslinked acrylic rubber-based impact-resistant modifier. This vinyl chloride resin composition is said to be able to improve the flexibility temperature (corresponding to the Vicat softening temperature). [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 181853 / 1983 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] However, the technology described in Patent Document 1 achieves a maximum flexibility temperature of around 83.5°C, which is hardly sufficient for products used outdoors for extended periods. Furthermore, there is no mention of reducing the shrinkage rate at high temperatures.

[0008] This invention has been made in view of the above-mentioned problems, and its objective is to provide a vinyl chloride resin molded article that is less prone to softening at high temperatures. [Means for solving the problem]

[0009] The means employed by the inventors to solve the above problems are described below. The vinyl chloride resin molded article of the present invention is an extruded molded article having a vinyl chloride resin as its main component, and is configured such that its Vicat softening temperature is 103°C or higher.

[0010] Polyvinyl chloride resins, being polymer materials, do not immediately begin to soften upon reaching the Vicat softening temperature. The Vicat softening temperature is a threshold temperature set by a predetermined load and indenter penetration depth, and deformation can occur even below the Vicat temperature depending on the load and shape. In particular, temperatures inside automobiles in the summer can exceed 80°C, and if the Vicat softening temperature reaches 80°C or 90°C, there is a risk that the product will become non-functional due to deformation.

[0011] In this invention, by using a vinyl chloride resin as the main material and creating a molded article with a Vicat softening temperature of 103°C or higher, it is possible to use it stably for a long period of time without deformation that would cause it to lose practicality, even when used in the interior of a car or building exposed to direct sunlight.

[0012] In order to solve the aforementioned problems, the present invention employs, in addition to the above-mentioned means, a configuration that includes a cross-linked vinyl chloride resin, wherein the proportion of the gel-like cross-linked vinyl chloride resin in the total cross-linked vinyl chloride resin is 15% to 60% by mass. By incorporating a gel-like portion into the cross-linked polyvinyl chloride resin, the Vicat softening temperature can be further improved.

[0013] In order to solve the aforementioned problems, the present invention employs, in addition to the above-mentioned means, the shrinkage rate per unit length when left in a 90°C environment for 24 hours can be reduced to 1.5% or less. Vinyl chloride resins generally shrink when heated. Furthermore, once they shrink, they do not return to their original dimensions even after cooling. Therefore, using them in high-temperature environments can lead to structural problems due to deformation caused by shrinkage.

[0014] Generally, shrinkage due to heating is suppressed by adding fibrous fillers, but in this invention, in a vinyl chloride resin molded article that does not contain fibrous fillers, the shrinkage rate per unit length when left in a 90°C environment for 24 hours is set to 1.5% or less, so that the structure is not significantly affected even when used in a high-temperature environment.

[0015] Another means employed by the present invention to solve the aforementioned problems is that, in the above configuration, the specular gloss at an incident angle of 60 degrees can be set to 20% or less. When using a vinyl chloride resin molded body for products where appearance is important, the appearance quality can be improved by achieving a so-called matte finish with suppressed surface gloss. However, when reducing the gloss by adding a matting agent as commonly done, the heat resistance decreases due to the influence of the matting agent.

[0016] In the present invention, while maintaining a high Vicat softening temperature and setting the specular glossiness to 20% or less, it is possible to obtain a molded body with high heat resistance and a high-quality appearance surface. That is, even in applications exposed to high temperatures, a molded body with excellent appearance can be obtained.

[0017] As another means adopted by the present invention to solve the above problems, in addition to the above configuration, the Charpy impact strength can be 10 kJ / m 2 or more. The degree of matting and the impact strength may be in an inverse relationship. In this case, even if the product has an improved appearance quality, it may be weak against instantaneous forces and practical problems may occur.

[0018] In the present invention, by maintaining the specular glossiness at 20% or less and setting the Charpy impact strength to 10 kJ / m 2 or more, it is possible to obtain a vinyl chloride resin molded body that is excellent in appearance quality and strong against instantaneous forces.

[0019] As another means adopted by the present invention to solve the above problems, it is a coextruded molded body in which a plurality of layers of the above-mentioned vinyl chloride resin molded bodies are stacked, and is composed of an inner layer and a surface layer which is a design layer thinner than the inner layer in terms of thickness, and it is also possible to use the above-mentioned vinyl chloride resin molded body for either or both of the surface layer and the inner layer. In this configuration, it has a multi-layer structure by coextrusion molding, with the surface layer being a thin and decorative layer and the inner layer being a relatively thick layer. With such a configuration, while the surface layer allows for good visual recognition of the appearance, high heat resistance can be ensured in the inner layer that does not require design properties, enabling both appearance and heat resistance to be achieved.

[0020] Another means employed by the present invention to solve the aforementioned problems is to make the surface layer have a specular gloss of 20% or less at an incident angle of 60 degrees. In other words, in a co-extruded polyvinyl chloride resin molded article containing two or more layers, the surface layer, which is the design layer, is made of a resin molded article with low specular gloss, and the inner layer is made of the aforementioned polyvinyl chloride resin molded article.

[0021] By adopting the above configuration, it is possible to create a matte, high-quality exterior layer while making the other layers highly heat-resistant, thus making it easier to achieve both heat resistance and a good appearance. [Effects of the Invention]

[0022] As described above, the vinyl chloride resin molded article of the present invention is a molded article produced by extrusion molding, and has the effect of being less prone to softening at high temperatures because its Vicat softening temperature is 103°C or higher. [Brief explanation of the drawing]

[0023] [Figure 1] These are perspective and cross-sectional views showing a vinyl chloride resin molded article of the present invention. [Figure 2] This is a cross-sectional view showing a vinyl chloride resin molded article in Modification 1 of the present invention. [Figure 3] This is an explanatory diagram illustrating the test method for heat shrinkage testing. [Modes for carrying out the invention]

[0024] Embodiments for carrying out the present invention will be described below with reference to Figure 1. Please note that each diagram is a schematic representation for explanatory purposes, and dimensions and shapes may be exaggerated or simplified in some cases.

[0025] The vinyl chloride resin molded article (hereinafter also simply referred to as "molded article") 100 of the present invention is a molded article formed by extrusion molding, as shown in Figure 1, and is a molded article having the same cross-sectional shape in the longitudinal direction. The example in Figure 1 shows a molded product used for outdoor decking, but its applications are not limited to this. It can be used for components used in high-temperature environments, such as those exposed to direct sunlight, including building decking and jointing materials, and exterior molding materials for automobiles.

[0026] The molded article 100 of the present invention is a single-layer extruded article made of the same resin. Its specific composition can be various, but for example, additives such as heat resistance improvers, reinforcing agents, and matting agents can be added to the main material, which is a vinyl chloride resin.

[0027] For the main material, a vinyl chloride resin molded article, for example, a vinyl chloride homopolymer, a vinyl chloride-ethylene copolymer, a vinyl chloride-vinyl acetate copolymer, or an acrylic rubber-modified vinyl chloride resin can be used.

[0028] For example, α-methylstyrene resins and N-phenylmaleimide resins can be used as heat resistance improvers.

[0029] Reinforcing agents such as methyl methacrylate-butadiene-styrene copolymer (MBS) and acrylic elastomers can be used. The amount of reinforcing agent added can be between 1 and 20 parts by weight per 100 parts by weight of the main material, vinyl chloride resin.

[0030] Cross-linked polyvinyl chloride resin and cross-linked acrylic resin can be used as the matting agent. The amount added can be 10 to 70 parts by weight of the matting agent per 100 parts by weight of the main material, polyvinyl chloride resin.

[0031] The cross-linked polyvinyl chloride resin in the matting agent can be made into a gel by adjusting the cross-linking density. In the present invention, gel-like cross-linked polyvinyl chloride resin can also be added. The addition ratio can be 15% to 60% by mass of the gel-like cross-linked polyvinyl chloride resin relative to the total amount of cross-linked polyvinyl chloride resin, preferably 15% to 30% by mass.

[0032] In addition to the above, the present invention may also include fiber-based fillers, heat stabilizers, lubricants, mold release agents, fillers, external lubricants, processing aids, impact modifiers, antioxidants, light stabilizers, ultraviolet absorbers, pigments, plasticizers, and the like.

[0033] The molded article 100 of the present invention has a Vicat softening temperature of 103°C or higher, preferably 106°C or higher, more preferably 108°C or higher, and even more preferably 110°C or higher, as specified in JIS K7206. Because the Vicat softening temperature is 103°C or higher, even if the molded body 100 is used in a high-temperature environment, the possibility of it softening and deforming and affecting its structure is reduced.

[0034] Furthermore, the molded article 100 of the present invention has a shrinkage rate per unit length (hereinafter also referred to as the heat shrinkage rate) of 1.5% or less when left in a 90°C environment for 24 hours, preferably 1% or less, more preferably 0.8% or less, and even more preferably 0.5% or less. Because the heat shrinkage rate is 1.5% or less, even if the molded body 100 is used in a high-temperature environment, the possibility of dimensional shrinkage affecting the structure is reduced.

[0035] Furthermore, the specular gloss of the molded body 100 can be reduced as specified in JIS Z 8741. In this case, the specular gloss is 20% or less at an incident angle of 60 degrees, preferably 15% or less, more preferably 10% or less, and even more preferably 8% or less. By reducing the mirror-like gloss level to 20% or less, a so-called matte finish is achieved, improving the overall appearance and quality.

[0036] Furthermore, the Charpy impact strength of the molded body 100 can be increased as specified in JIS K7111. In this case, the Charpy impact strength is 10 kJ / m² at 23°C and a notch tip radius of 1 mm. 2 The above is preferable, preferably 15 kJ / m³ 2 The above is more preferable: 18 kJ / m 2 That's all. Charpy impact strength is 10 kJ / m2 As a result of the above, not only is it highly heat-resistant, but it is also less prone to cracking or deformation even when instantaneous kinetic energy is applied.

[0037] "Variations" Next, a modified example of the present invention is shown in Figure 2. As shown in the figure, the molded body 101 in the modified example of the present invention is a molded body having a surface layer 1 and an inner layer 2, and can be molded by co-extrusion molding. The surface layer 1 is made of a resin mainly composed of polyvinyl chloride resin, and has a matte appearance by lowering the specular gloss as specified in JIS Z 8741. In this modified example as well, the specular gloss is 20% or less at an incident angle of 60 degrees, preferably 15% or less, more preferably 10% or less, and even more preferably 8% or less.

[0038] The inner layer 2 is made of a resin mainly composed of polyvinyl chloride resin, and has a Vicat softening temperature of 103°C or higher as specified in JIS K7206, preferably 106°C or higher, more preferably 108°C or higher, and even more preferably 110°C or higher. In addition to the Vicat softening temperature characteristics described above, the inner layer 2, like the form shown in Figure 1, has a heat shrinkage rate of 1.5% or less, a specular gloss of 20% or less, and a Charpy impact strength of 10 kJ / m². 2 You may do the above.

[0039] In this modified example, the molded body 101 has a surface layer 1 and an inner layer 2 that is thicker than the surface layer 1, and each layer is made of a different resin. In each layer, the surface layer 1 is configured to improve the appearance quality, and the inner layer 2 is configured to improve the mechanical properties. Note that the inner layer 2 may be composed of multiple layers.

[0040] In this way, by ensuring the overall mechanical properties of the molded body 101 with the inner layer 2 and making only the thin surface layer 1 a matte layer, it is possible to create a molded body that not only has a high-quality matte appearance but also possesses sufficient mechanical properties. [Examples]

[0041] Next, the following items were evaluated for the molded articles of the present invention: "Vicat softening temperature," "heat shrinkage rate," "Charpy impact strength," and "spectral gloss." The conditions for each example and each comparative example are as follows.

[0042] "Example 1" Example 1 involves adding 10 parts by weight of MBS, a reinforcing agent, to 100 parts by weight of a mixture of polyvinyl chloride, the main material, and α-methylstyrene, a heat resistance improver. No matting agent was added in Example 1.

[0043] Example 2 Example 2 involves adding 10 parts by weight of MBS as a reinforcing agent, 50 parts by weight of crosslinked vinyl chloride resin and 10 parts by weight of crosslinked acrylic resin as matting agents to 100 parts by weight of a mixture of polyvinyl chloride as the main material and α-methylstyrene as a heat resistance improver.

[0044] "Example 3" Example 3 involves adding 10 parts by weight of MBS as a reinforcing agent, 40 parts by weight of crosslinked vinyl chloride resin and 5 parts by weight of crosslinked acrylic resin as matting agents to 100 parts by weight of a mixture of polyvinyl chloride as the main material and α-methylstyrene as a heat resistance improver.

[0045] "Example 4" Example 4 is a two-layer structure formed by co-extrusion molding. The inner layer is made by adding 8 parts by weight of MBS, a reinforcing agent, to 100 parts by weight of a mixture of polyvinyl chloride, the main material, and α-methylstyrene, a heat resistance improver. The outer layer consists of 75 parts by weight of a mixture of polyvinyl chloride, the main material, and α-methylstyrene, a heat-resistant enhancer, to which 7 parts by weight of MBS, a reinforcing agent, 25 parts by weight of cross-linked polyvinyl chloride resin and 5 parts by weight of cross-linked acrylic resin are added as matting agents. In the case of cross-linked polyvinyl chloride resin used as a matting agent, 20% by mass of the total mass of the cross-linked polyvinyl chloride resin is gel-like cross-linked polyvinyl chloride resin.

[0046] Example 5 Example 5 is a two-layer structure formed by co-extrusion molding. The inner layer is made by adding 8 parts by weight of MBS, a reinforcing agent, to 100 parts by weight of a mixture of polyvinyl chloride, the main material, and α-methylstyrene, a heat resistance improver. The outer layer consists of 75 parts by weight of a mixture of the main material, polyvinyl chloride, and a heat-resistant enhancer, to which 7 parts by weight of acrylic rubber as a reinforcing agent, 25 parts by weight of cross-linked polyvinyl chloride resin and 5 parts by weight of cross-linked acrylic resin as matting agents are added. In the case of cross-linked polyvinyl chloride resin used as a matting agent, 20% by mass of the total mass of the cross-linked polyvinyl chloride resin is gel-like cross-linked polyvinyl chloride resin.

[0047] "Comparative Example 1" Comparative Example 1 consists of 10 parts by weight of MBS, a reinforcing agent, added to 100 parts by weight of polyvinyl chloride, the main material. In Comparative Example 1, no heat resistance improver or matting agent was added.

[0048] "Comparative Example 2" Comparative Example 2 consists of 50 parts by weight of a mixture of polyvinyl chloride, the main material, and α-methylstyrene, a heat resistance improver, to which 10 parts by weight of MBS, a reinforcing agent, 50 parts by weight of crosslinked vinyl chloride resin and 22 parts by weight of crosslinked acrylic resin are added as matting agents.

[0049] The conditions for the above samples are summarized in Table 1. [Table 1]

[0050] "Evaluation Test of Vicat Softening Temperature" The Vicat softening temperatures of the samples from Examples 1-5, which are molded articles of the present invention, and the samples from Comparative Examples 1-2, which are molded articles of the prior art, were compared. The Vicat softening temperature was measured using the A50 method according to JIS K7206 (test load 10N, heating rate 50°C / h).

[0051] The test results are shown in Table 2. In Example 1, the temperature was 113°C; in Example 2, 103°C; in Example 3, 109°C; in Example 4, 112°C; and in Example 5, 116°C. In contrast, Comparative Example 1 was 86°C and Comparative Example 2 was 98°C. While all of the comparative examples were below 100°C, all of the examples were 103°C or higher, demonstrating high heat resistance. [Table 2]

[0052] "Evaluation Test of Heat Shrinkage Rate" The heat shrinkage rates of the molded articles of Examples 1 to 5, which are the present invention, and the molded articles of Comparative Examples 1 to 2, which are the conventional technology, were compared. The heat shrinkage rate was measured using the procedure shown in Figure 3.

[0053] To elaborate on the test method, first, each sample, measuring 2 mm in thickness, 20 mm in width, and 300 mm in length, is left for 24 hours in an environment with a temperature of 23°C ± 2°C and a humidity of 50% ± 10%, and the length L is measured to obtain the initial value. Next, the sample was left in an environment with increased temperature for 24 hours, then returned to an environment of 23°C ± 2°C and left for another 24 hours. After this, the length L+α was measured, and the change in length (L+α) / L*100 was calculated. The temperature was changed sequentially to 80°C, 90°C, and 100°C, and the heat shrinkage rate was calculated from the dimensional changes before and after the test under each temperature condition. In this case, the heat shrinkage rate at the 90°C condition was used for comparison.

[0054] The test results are shown in Table 3. In Example 1, it was 0.05%, in Example 2 it was 0.5%, in Example 3 it was 0.2%, in Example 4 it was 0.14%, and in Example 5 it was 0.17%. In contrast, in Comparative Example 1 it was 1.8% and in Comparative Example 2 it was 2.1%. All of the comparative examples exceeded 1.5%, while all of the examples were 1.5% or less, resulting in the conclusion that dimensional shrinkage is less likely to occur even with temperature changes.

Table 3

[0055] ‘Evaluation Test of Charpy Impact Strength’ The Charpy impact strengths of the samples of Examples 1 to 5, which are the molded bodies of the present invention, and the sample of Comparative Example 2, which is a molded body of the prior art, were compared. The Charpy impact strength test was carried out according to the method specified in JIS K7111. The test piece had a length of 80 mm, a width of 10 mm, and a thickness of 4 mm, and the notch tip radius was 1 mm. This test piece was placed with a support span of 62 mm, and the test was carried out under the condition of an environmental temperature of 23°C.

[0056] The test results are shown in Table 4. In Example 1, it was 13 kJ / m 2 , in Example 2 it was 15 kJ / m 2 , in Example 3 it was 19 kJ / m 2 , in Example 4 it was 13 kJ / m 2 , in Example 5 it was 19 kJ / m 2 . In contrast, in Comparative Example 1 it was 13 kJ / m 2 , and in Comparative Example 2 it was 9 kJ / m 2 . All of the comparative examples were less than 10 kJ / m 2 , while all of the examples were 10 kJ / m 2 or more, resulting in the conclusion that they have high impact resistance.

Table 4

[0057] ‘Evaluation Test of Mirror Gloss’ The specular gloss of the samples from Examples 2 to 5, which are molded articles of the present invention, was compared with that of the sample from Comparative Example 1, which is a molded article of the prior art. Specular gloss was measured using a gloss checker (gloss meter) conforming to JIS Z 8741, under conditions of an incident angle of 60 degrees.

[0058] The test results are shown in Table 5. While Example 2 had a gloss level of 5%, Example 3 had 10%, Example 4 had 3%, and Example 5 had 3%, Comparative Example 1 had 60%. The Comparative Example had a high gloss level of 60%, whereas all of the Examples had a gloss level of 20% or less, indicating that they had a matte appearance. [Table 5]

[0059] As described above, in the present invention, since the Vicat softening temperature is 103°C or higher, it can be said that the vinyl chloride resin molded article is less prone to softening at high temperatures. [Explanation of Symbols]

[0060] 100,101 Molded bodies 1 Surface layer 2. Inner layer

Claims

1. An extruded molded article having a vinyl chloride resin as its main component, A vinyl chloride resin molded article characterized by having a Vicat softening temperature of 103°C or higher.

2. Contains cross-linked polyvinyl chloride resin, The vinyl chloride resin molded article according to claim 1, characterized in that the proportion of gel-like cross-linked vinyl chloride resin in the total cross-linked vinyl chloride resin is 15% by mass to 60% by mass.

3. A vinyl chloride resin molded article according to claim 1 or claim 2, characterized in that the shrinkage rate per unit length when left in a 90°C environment for 24 hours is 1.5% or less.

4. A vinyl chloride resin molded article according to claim 1 or claim 2, characterized in that the specular gloss at an incident angle of 60 degrees is 20% or less.

5. Charpy impact strength is 10 kJ / m 2 A vinyl chloride resin molded article according to claim 1 or claim 2, characterized by the above.

6. A co-extruded molded article formed by stacking multiple layers of polyvinyl chloride resin molded articles, It consists of an inner layer and a surface layer which is a design layer thinner than the aforementioned content. A vinyl chloride resin molded article characterized in that either or both of the surface layer and the inner layer are vinyl chloride resin molded articles according to claim 1 or claim 2.

7. The vinyl chloride resin molded article according to claim 6, characterized in that the surface layer has a specular gloss of 20% or less at an incident angle of 60 degrees.

Images