Resin composition and resin molded article

Abstract

To provide a resin composition that resists color fading.SOLUTION: A resin composition comprises an ethylene vinyl acetate copolymer resin, a pigment, and a hydrolysis inhibitor that inhibits the hydrolysis of the ethylene vinyl acetate copolymer resin.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a resin composition and a resin molded article produced from the resin composition. [Background technology]

[0002] Ethylene vinyl acetate copolymer resin (hereinafter sometimes referred to as "EVA resin") is a resin obtained by copolymerizing ethylene and vinyl acetate, and is used, for example, as the main raw material for floats for swimming pool lane ropes (Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 06-043109 Summary of the Invention [Problem to be solved by the invention]

[0004] Since EVA resin is naturally colorless and transparent, when it is used to manufacture pool lane rope floats, the EVA resin is colored. Colored lane rope floats can fade if used over a long period of time in water containing chlorine (for example, in an indoor heated pool with a water temperature of approximately 29°C to 31°C).

[0005] An object of the present invention is to provide a resin composition that is inhibited from fading, and a resin molded article made from the resin composition. [Means for solving the problem]

[0006] The present invention provides the following aspects. (Item 1) an ethylene vinyl acetate copolymer resin; A pigment, a hydrolysis inhibitor that inhibits hydrolysis of the ethylene vinyl acetate copolymer resin; A colored resin composition comprising:

[0007] (Item 2) The hydrolysis inhibitor includes a carbodiimide compound. Item 1. The resin composition according to item 1.

[0008] (Item 3) Prevents fading in chlorinated water Item 3. The resin composition according to item 1 or 2.

[0009] (Item 4) further comprising a phenolic antioxidant, 4. The resin composition according to any one of items 1 to 3.

[0010] (Item 5) 5. A resin molded article made from the resin composition according to any one of items 1 to 4.

[0011] (Item 6) It is a float for the pool lane rope, Item 5. A resin molded product according to item 5. [Effects of the Invention]

[0012] According to the present invention, it is possible to provide a resin composition and a resin molded article in which discoloration is suppressed. DETAILED DESCRIPTION OF THE INVENTION

[0013] The resin composition and the resin molded article of the present invention will now be described.

[0014] The resin composition contains an EVA resin, a pigment, and a hydrolysis inhibitor that inhibits hydrolysis of the EVA resin.

[0015] The EVA resin may be used alone or in combination with two or more different types with different properties. It is known that the flexibility of an EVA resin increases as the mass proportion of vinyl acetate increases. Therefore, for example, the flexibility of the resin composition may be adjusted by using two or more EVA resins with different mass proportions of vinyl acetate in combination.

[0016] Pigments are used to color EVA resin, for example, red, blue, yellow, etc. The pigments are not particularly limited as long as they can color EVA resin, and may be inorganic or organic pigments. One type of pigment may be used alone, or two or more types may be used in combination. For example, a mixture of inorganic and organic pigments may be used as the pigment.

[0017] The hydrolysis inhibitor is not particularly limited as long as it is a substance capable of inhibiting the hydrolysis of EVA resin. It is believed that inhibiting the hydrolysis of EVA resin can inhibit degradation of the EVA resin, thereby inhibiting discoloration of the resin composition. One hydrolysis inhibitor may be used alone, or two or more may be used in combination. The hydrolysis inhibitor preferably contains a carbodiimide compound. A carbodiimide compound refers to a compound having the functional group -N=C=N-. The carbodiimide compound is not particularly limited as long as it can inhibit the hydrolysis of EVA resin, and may be a low-molecular-weight compound or a high-molecular-weight compound. The blending ratio of the carbodiimide compound is preferably 0.1 to 1.0 mass%, more preferably 0.4 to 0.6 mass%.

[0018] The resin composition may further contain a phenolic antioxidant. The phenolic antioxidant is, for example, a hindered phenolic antioxidant. By including the phenolic antioxidant in the resin composition, discoloration of the resin composition can be suppressed for a longer period of time.

[0019] The resin composition can be prepared, for example, by dry-mixing the above-mentioned materials and then heating and melting them.

[0020] The resin molded article can be produced by molding a resin composition. An example of the resin molded article is a float for a pool lane rope. The float is for use in an indoor heated pool (for example, with a water temperature of about 29°C to 31°C). There are no particular limitations on the molding method for the resin molded article, and examples of methods that can be used include injection molding, blow molding, and foam molding.

[0021] In order to prevent the float from fading, it is preferable that the float rotate on the water surface so that the same part of the float is not submerged in water for a long period of time. As an example, the float includes a cylindrical portion, multiple vanes, and a wall portion. The cylindrical portion is located at the center of the float and is the portion into which a rope for connecting multiple floats is inserted. Each vane extends radially from the side of the cylindrical portion. The wall portion is connected to the side end of the vane and covers the vane. An opening surrounded by the vanes and the wall portion is formed inside the float. When water enters the opening and hits the vane, the force of the water causes the float to rotate around the rope. This prevents the same part of the float from being submerged in water for a long period of time, further preventing the float from fading.

[0022] The flexural modulus of the float, as measured by a test method conforming to JIS K 6924-2, is preferably 10 to 200 MPa, and more preferably 30 to 120 MPa. Furthermore, the hardness of the float, as measured by a durometer type A test method conforming to JIS K 6253-3, is preferably 75 to 95, and more preferably 89 to 91. Having the flexural modulus and hardness of the float within the above ranges can more effectively prevent manufacturing problems, such as the float not being easily released from the mold during injection molding, and management problems, such as the float losing its shape during storage after molding. Furthermore, the float is easily elastically deformed, and can effectively prevent injury even if a swimmer's body part collides with the float. [Example]

[0023] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. Table 1 shows the blending ratios of the raw materials used in Examples 1 and 2 and the comparative example, as well as the test results.

[0024] <Preparation of Resin Composition> The raw materials listed below were dry-mixed to produce a mixture. The mixture was placed in an injection molding machine, melted at 200°C, and then injection-molded into a plate-shaped product approximately 1 mm thick. The following raw materials were used: (A)EVA resin (B) Pigment (C) Carbodiimide compound (D) Phenolic antioxidants

[0025] <Test Method> (1) A rectangular sample measuring 20 mm x 25 mm was cut out from the plate-shaped molded product. (2) The sample was placed in a sodium hypochlorite solution with a temperature of 50°C and a chlorine concentration of 1200 ppm, and the water temperature was maintained at 50°C to conduct an accelerated test on temperature and chlorine concentration. The test was conducted in a dark environment. (3) After a predetermined number of days had passed, the sample was removed from the aqueous sodium hypochlorite solution, the moisture on the surface of the sample was wiped off, and the sample was subjected to an evaluation test.

[0026] <Evaluation test> (1) Using a colorimeter, measure the L * a * b * Color difference ΔE in color space * was measured. * is the color difference from the color (red) of the product (reference sample) in its initial state (new condition). Measuring device name: CR-400 (Konica Minolta Japan, Inc.) Measurement light source: C light source Measurement part: φ5mm (2) Measure three arbitrary points on each sample, and calculate the arithmetic mean value of the measurements as ΔE * was adopted as. (3) ΔE after a certain number of days have passed * is ΔE on day 0 * To make it easier to understand how much the value has changed since the start of the experiment, we use the ΔE * ΔE on day 0 * The value obtained by subtracting ΔE * For example, the change in ΔE on day 0 * ΔE * 0, ΔE on the 3rd day * ΔE * When 3 is set, "ΔE on the third day" * The change in ΔE * 3-ΔE * 0". Note that "ΔE on day 0" * " is the color difference measured on the same day the sample was prepared without immersing the sample in chlorine water. (4) For the comparative sample, after 15 days, "ΔE * The "change in color" was 23.7, and fading was clearly more advanced than in the samples of Examples 1 and 2, so the test was stopped at this point.

[0027] TIFF0007745244000001.tif44170

[0028] <Result> As is clear from Table 1, the samples of Examples 1 and 2 containing a carbodiimide compound both had a ΔE * It can be seen that the change in color is suppressed, and fading in chlorine water is suppressed. It can also be seen that the sample of Example 2 containing a phenolic antioxidant can suppress fading for a long period of time compared to the sample of Example 1 which does not contain a phenolic antioxidant.

[0029] It is believed that the inclusion of a carbodiimide compound in the resin composition inhibits hydrolysis of the EVA resin, suppressing deterioration of the EVA resin. As a result, it is possible to suppress the penetration of chlorine into the sample, prevent damage to the pigment caused by chlorine, and suppress fading.

Claims

1. A resin molded article made from a resin composition for use in chlorine-containing water, the resin composition comprising: an ethylene vinyl acetate copolymer resin; A pigment, a hydrolysis inhibitor comprising a carbodiimide compound that inhibits hydrolysis of the ethylene vinyl acetate copolymer resin; and the content of the hydrolysis inhibitor is 0.1 to 1.0 mass %.

2. A resin molded product as described in claim 1, wherein the resin composition further contains a phenolic antioxidant.

3. 3. The resin molded article according to claim 1, which is a float for a lane rope of a swimming pool.

Images