Method for manufacturing cap

Abstract

To provide a method for manufacturing a cap that exhibits required performance as a cap while using container waste materials that are defective products rejected during container manufacturing.SOLUTION: A method for manufacturing a cap includes injection-molding a resin composition containing (A) polypropylene and (B) a container waste material containing (b1) polyethylene and (b2) an ethylene-vinyl alcohol copolymer. The content of the (B) container waste material in the resin composition is 5.0 pts.mass or more and 20.0 pts.mass or less per 100 pts.mass of the resin composition.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a cap.

Background Art

[0002] Containers for food, drugs, etc. and caps often use containers mainly composed of synthetic resin.

[0003] As the container body, for example, blow bottles, blow tubes, etc. are known. Blow bottles, blow tubes, etc. have a plurality of layers with different functions laminated thereon, and it is easy to exhibit container characteristics according to the contents, and they can be manufactured at high efficiency and low cost by blow molding, so they are widely used as containers for beverages, seasonings, cosmetics, etc.

[0004] On the other hand, as a material for caps, for example, it is known to use a resin composition containing polyolefin. For example, Patent Document 1 describes manufacturing a container cap using a resin composition containing polypropylene excellent in thermoplasticity and ethylene-vinyl alcohol copolymer excellent in gas barrier properties.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] When molding a synthetic resin or its composition into the shape of a container body, problems such as uneven wall thickness, burrs, air bubbles, cracks, foreign matters, etc. may occur. Containers in which such inconveniences occur are excluded as defective products in the product inspection of the containers.

[0007] Defective products excluded in container manufacturing are not shipped as products. Most defective products are treated as container waste materials sold cheaply to recyclers (resource recycling operators) or container waste materials discarded for a fee. In particular, multi-layer containers have multiple layers of materials with different functions laminated together, and since it is difficult to separate each layer, it is not easy to mix and use them with virgin materials.

[0008] Also, since the material of the cap is required to have the mechanical and chemical properties required for the cap of the container, there is a concern that blending recycled products may impair the required performance of the cap.

[0009] The present invention has been made in view of the above circumstances. An object of the present invention is to provide a method for manufacturing a cap that exhibits the required performance as a cap while using container waste materials that are defective products excluded in container manufacturing.

Means for Solving the Problems

[0010] The present invention is as follows. 《Aspect 1》(A) Polypropylene and, (B) A container waste material containing (b1) polyethylene and (b2) an ethylene-vinyl alcohol copolymer are injection molded to include, the content ratio of the (B) container waste material in the resin composition is 5.0 parts by mass or more and 20.0 parts by mass or less with respect to 100 parts by mass of the resin composition, A method for manufacturing a cap. 《Aspect 2》The manufacturing method according to Aspect 1, wherein the (B) container waste material further contains (b3) acid-modified polyethylene. 《Aspect 3》The content ratio of the (b1) polyethylene in the (B) container waste material is 80.0% by mass or more and 97.0% by mass or less based on the total mass of the (B) container waste material, the content ratio of the (b2) ethylene-vinyl alcohol copolymer in the (B) container waste material is 3.0 parts by mass or more and 20% by mass or less based on the total mass of the (B) container waste material, The manufacturing method according to Aspect 1. 《Aspect 4》The content ratio of the (b1) polyethylene in the (B) container waste material is 80.0% by mass or more and 97.0% by mass or less based on the total mass of the (B) container waste material, the content ratio of the (b2) ethylene-vinyl alcohol copolymer in the (B) container waste material is 3.0% by mass or more and 20% by mass or less based on the total mass of the (B) container waste material, and the mass ratio of the (b3) acid-modified polyethylene in the (B) container waste material is 0.3% by mass or more and 5.0% by mass or less based on the total mass of the (B) container waste material. The manufacturing method according to Aspect 2. 《Aspect 5》The manufacturing method according to any one of Aspects 1 to 4, wherein the (A) polypropylene is a random copolymer type polypropylene. 《Aspect 6》The manufacturing method according to any one of Aspects 1 to 4, wherein the cap is a hinge cap. 《Aspect 7》(A) Polypropylene and (B) A container waste material containing (b1) polyethylene and (b2) ethylene-vinyl alcohol copolymer, and composed of a resin composition containing wherein the content ratio of the (B) container waste material in the resin composition is 5.0 parts by mass or more and 20.0 parts by mass or less with respect to 100 parts by mass of the resin composition. Cap. 《Aspect 8》The cap according to Aspect 7, wherein the (B) container waste material further contains (b3) acid-modified polyethylene. 《Aspect 9》The content ratio of the (b1) polyethylene in the (B) container waste material is 80.0% by mass or more and 97.0% by mass or less based on the total mass of the (B) container waste material, the content ratio of the (b2) ethylene-vinyl alcohol copolymer in the (B) container waste material is 3.0% by mass or more and 20% by mass or less based on the total mass of the (B) container waste material, The cap according to Aspect 7. 《Aspect 10》The content ratio of the (b1) polyethylene in the (B) container waste material is 80.0 mass% or more and 97.0 mass% or less based on the total mass of the (B) container waste material, the content ratio of the (b2) ethylene-vinyl alcohol copolymer in the (B) container waste material is 3.0 mass parts or more and 20 mass% or less based on the total mass of the (B) container waste material, the mass ratio of the (b3) acid-modified polyethylene in the (B) container waste material is 0.3 mass% or more and 5.0 mass% or less based on the total mass of the (B) container waste material, The cap according to aspect 8. 《Aspect 11》(A) Polypropylene 80.0 mass% or more and 95.0 mass% or less, (b1) Polyethylene 4.0 mass% or more and 19.5 mass% or less, (b2) Ethylene-vinyl alcohol copolymer 0.15 mass% or more and 4.0 mass% or less A cap made of a resin composition containing. 《Aspect 12》The resin composition further contains (b3) acid-modified polyethylene of 1.0 mass% or less, the cap according to aspect 11. 《Aspect 13》The (A) polypropylene is a random copolymer type polypropylene, the cap according to any one of aspects 7 to 12. 《Aspect 14》A hinge cap, the cap according to any one of aspects 7 to 12.

Advantages of the Invention

[0011] According to the present invention, there is provided a method for manufacturing a cap that exhibits the required performance as a cap while using container waste materials that are defective products excluded in container manufacturing. The cap manufactured by the method for manufacturing a cap of the present invention may be, for example, a hinge cap.

Brief Description of the Drawings

[0012]

Figure 1

Mode for Carrying Out the Invention

[0013] 《Method for Manufacturing a Cap》 According to a first aspect of the present invention, a method for manufacturing a cap is provided.

[0014] The method for manufacturing a cap according to the first aspect of the present invention (A) polypropylene, and (B) a resin composition containing (b1) polyethylene and (b2) a container waste material containing an ethylene-vinyl alcohol copolymer including injection molding. The content ratio of the (B) container waste material in the resin composition is 5.0 parts by mass or more and 20.0 parts by mass or less with respect to 100 parts by mass of the resin composition. It is a manufacturing method.

[0015] In the resin composition constituting the cap of the present invention, a container waste material containing (A) polypropylene (PP), (B) (b1) polyethylene (PE), and (b2) an ethylene-vinyl alcohol copolymer (EVOH) is blended. This container waste material is a waste material of a container having a multilayer structure in which (A) polypropylene (PP), (B) (b1) polyethylene (PE), and (b2) an ethylene-vinyl alcohol copolymer (EVOH) are laminated in layers. Therefore, the components in this container waste material are mixed. This container waste material may further contain (b3) acid-modified polyethylene (PE-A) in addition to (b1) polyethylene (PE) and (b2) an ethylene-vinyl alcohol copolymer (EVOH).

[0016] Container waste materials often have multiple layers of materials with different functions laminated together. Therefore, when blending container waste materials with PP, there is a concern that the original functions of PP may be impaired. However, in the present invention, by selecting container waste materials containing specific components as the container waste materials and adjusting the blending amount, the resulting cap has the original dimensional accuracy of PP, good appearance, etc. For example, when the present invention is applied to a hinge cap, it exhibits appropriate opening and closing strengths and can give the user a comfortable opening and closing feeling.

[0017] Hereinafter, the components contained in the resin composition used in the method for manufacturing the cap of the present invention will be described in order.

[0018] 〈(A) Polypropylene (PP)〉 (A) PP may be a homopolymer of propylene or a copolymer of propylene and other monomers. As other monomers, olefins other than propylene can be preferably used. Specifically, for example, α-olefins having 2 or 4 to 10 carbon atoms can be exemplified, and preferably ethylene, 1-butene, 1-pentene, or 1-hexene.

[0019] (A) When PP is a copolymer of propylene and other monomers, the form of copolymerization may be any of a block copolymer, a random copolymer, and a mixture thereof. Also, a mixture of a propylene homopolymer and a copolymer of propylene and other monomers is acceptable.

[0020] The crystal structure of the PP portion may be any of isotactic, syndiotactic, and atactic.

[0021] (A) PP used in the present invention may be a random copolymer type polypropylene. Random copolymer type polypropylene is suitable in that it has high transparency, so that the degree of freedom in the color of the cap is high and a cap with excellent design can be obtained.

[0022] The (A)PP used in the present invention may be, for example, a random copolymer of propylene and ethylene. Particularly preferably, it is a random copolymer of propylene and ethylene, and the crystal structure of the PP portion is isotactic.

[0023] The (A)PP used in the present invention may have a relatively high MFR in order to ensure molding accuracy. For example, in accordance with JIS K 6921-2, the melt mass flow rate (MFR) measured at a temperature of 230 °C and a load of 2.16 kg may be 8.0 g / 10 min or more, 10.0 g / 10 min or more, 12.0 g / 10 min or more, 15.0 g / 10 min or more, 17.0 g / 10 min or more, or 20.0 g / 10 min or more. On the other hand, in order to ensure moldability and heat resistance, the above MFR may be 80.0 g / 10 min or less, 60.0 g / 10 min or less, 50.0 g / 10 min or less, 40.0 g / 10 min or less, 30.0 g / 10 min or less, or 20.0 g / 10 min or less.

[0024] The density of (A)PP may be about 890 kg / m3 or more and 910 kg / m3 or less, and the tensile modulus may be about 500 MPa or more and 1,000 MPa or less.

[0025] The above characteristics regarding (A)PP are the characteristics of the entire mixture when the (A) component is a mixture of two or more kinds of PP.

[0026] 〈(B) Container waste material〉 The container waste material of the (B) component contains (b1) polyethylene and (b2) ethylene-vinyl alcohol copolymer. This container waste material may further contain (b3) acid-modified polyethylene.

[0027] ((b1) Polyethylene (PE)) The polyethylene (PE) contained in the (B) container waste material may be a homopolymer of ethylene or a copolymer of ethylene and other olefins. PE may be any of low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), and high-density polyethylene (HDPE).

[0028] The (b1) PE contained in the (B) container waste material used in the present invention may be LDPE. This LDPE may be polyethylene containing 80 mol% or more, 90 mol% or more, 95 mol% or more, or 98 mol% or more of repeating units of methylene groups including branched chains, or substantially all repeating units are methylene groups.

[0029] The density of LDPE may be less than 0.930 g / cm 3 and may be less than 0.925 g / cm 3 or less, or may be less than 0.923 g / cm 3 or less, and may also be 0.870 g / cm3 or more, 0.875 g / cm 3 or more, 0.880 g / cm 3 or more, 0.900 g / cm 3 or more, 0.910 g / cm 3 or more, or may be 0.915 g / cm 3 or more.

[0030] The thermal properties of LDPE are not particularly limited. For example, when its melt mass flow rate is measured in accordance with JIS K6922-1 and -2, and JIS K7210-1 under the conditions of a temperature of 190 °C and a load of 21.18 N, it may be 0.05 g / 10 min or more, 0.1 g / 10 min or more, 0.2 g / 10 min or more, 0.3 g or more, or 0.4 g / 10 min or more, and may be 10 g / 10 min or less, 5.0 g / 10 min or less, 3.0 g / 10 min or less, or 1.0 g / 10 min or less.

[0031] ((b2) Ethylene-vinyl alcohol copolymer (EVOH)) The (B) EVOH used in the present invention is a copolymer of ethylene and vinyl alcohol. The copolymerization ratio of ethylene in the (b2) EVOH may be 20 mol% or more and 47 mol% or less, and may be 25 mol% or more and 32 mol% or less.

[0032] (b2) EVOH may be obtained, for example, by saponifying a copolymer of ethylene and a vinyl carboxylate (e.g., vinyl acetate). In this case, the saponification degree of (B) EVOH may be 75 mol% or more, 80 mol% or more, 85 mol% or more, 90 mol% or more, or 95 mol% or more, or it may be a completely saponified product with a saponification degree of 100 mol%. Here, the saponification degree refers to the ratio of the number of moles of vinyl alcohol units to the total number of moles of vinyl alcohol units and vinyl carboxylate units in (b2) EVOH.

[0033] (b2) For EVOH, the melt mass flow rate (MFR) measured at a temperature of 190 °C and a load of 2.16 kg in accordance with JIS K 6921-2 may be about 1.5 g / 10 min or more and 8.0 g / 10 min or less. The density of (b2) EVOH is 1,100 kg / m 3 or more and 1,200 kg / m 3 or less.

[0034] ((b3)) Acid-modified polyethylene (PE-A) The (b3) PE-A used in the present invention may be obtained, for example, by a method of graft-polymerizing an unsaturated carboxylic acid onto polyethylene (PE) as a base resin. By including (b3) PE-A in the resin composition, it is considered that (A) polypropylene (PP), (B) (b1) polyethylene (PE), and (b2) ethylene-vinyl alcohol copolymer (EVOH) will mix better.

[0035] The base resin PE may be a homopolymer of ethylene or a copolymer of ethylene and other olefins.

[0036] The unsaturated carboxylic acid grafted onto the base resin PE may be one or more selected from, for example, unsaturated carboxylic acids such as acrylic acid, maleic acid, fumaric acid, tetrahydrophthalic acid, itaconic acid, crotonic acid, citraconic acid, and acid anhydrides thereof.

[0037] (b3) The grafting rate of the unsaturated carboxylic acid in PE-A may be evaluated by oxidation measured in accordance with JIS K 0070. This oxidation is the number of milligrams (mg) of potassium hydroxide required to neutralize the acid groups and acid anhydride groups in 1 g of (b3) PE-A. The acid value of (b3) PE-A may be, for example, about 0.15 or more and 10 or less.

[0038] (b3) For PE-A, the melt mass flow rate (MFR) measured at a temperature of 190 °C and a load of 21.2 N in accordance with JIS K 6921-2 may be about 1.0 g / 10 min or more and 30 g / 10 min or less. The density of (b3) PE-A is 0.925 g / cm 3 or more and 0.935 g / cm 3 or less.

[0039] 〈Optional component〉 In addition to the above-mentioned (A) PP and (B) container waste materials, the resin composition used in the present invention may contain optional components. The optional components may be, for example, one or more selected from dyes, antioxidants, antistatic agents, thickeners, defoaming agents, surface modifiers, fillers, etc.

[0040] ((Content ratio of each component in (B) container waste material)) The content ratio of (b1) PE in (B) container waste material may be 80.0% by mass or more, 82.5% by mass or more, 85.0% by mass or more, or 90.0% by mass or more, based on the total mass of (B) container waste material, and may be 97.0% by mass or less, 95.0% by mass or less, 93.0% by mass or less, or 92.0% by mass or less.

[0041] The content ratio of (b2) EVOH in (B) container waste material may be 3.0 parts by mass or more, 5.0 parts by mass or more, 6.0 parts by mass or more, 7.0 parts by mass or more, or 8.0 parts by mass or more, based on the total mass of the (B) container waste material, and may be 20% by mass or less, 18% by mass or less, 16% by mass or less, 14% by mass or less, 12% by mass or less, 10% by mass or less, or 9.0% by mass or less.

[0042] (B) When the container waste material contains (b3) PE-A, the content ratio may be 0.3% by mass or more, 0.5% by mass or more, 0.7% by mass or more, 1.0% by mass or more, or 1.2% by mass or more based on the total mass of the (B) container waste material, and may be 5.0% by mass or less, 4.0% by mass or less, 3.0% by mass or less, 2.0% by mass or less, or 1.5% by mass or less.

[0043] In the present invention, by using a predetermined amount of the (B) container waste material containing each component in the above ratio, the obtained cap has the original dimensional accuracy of (A) PP, good appearance, etc.

[0044] ((Origin of the (B) container waste material)) As long as the (B) container waste material used in the present invention has the above composition, it may be waste material of any container. The (B) container waste material used in the present invention may be, for example, a blow bottle, a blow tube, etc. having a PE layer, an EVOH layer, and an adhesive layer (PE-A layer).

[0045] When the (B) container waste material is waste material of a food container, the materials contained in the container waste material are likely to be materials listed in the "Positive List" determined by, for example, the Sanitary Council for Polyolefins and the like. Therefore, when the resin composition in the present invention contains such a container waste material, there is an advantage that it becomes easy to apply the obtained cap to food applications.

[0046] ((Content ratio of the (B) container waste material in the resin composition)) The content ratio of the (B) container waste material in the resin composition used in the present invention is 5.0 parts by mass or more and 20.0 parts by mass or less with respect to 100 parts by mass of the resin composition.

[0047] If the content ratio of the (B) container waste material with respect to 100 parts by mass of the resin composition is 5.0 parts by mass or more, container waste material recycling becomes effective. From this viewpoint, the content ratio of the (B) container waste material in the resin composition is 5.0 parts by mass or more with respect to 100 parts by mass of the resin composition, and may be 7.5 parts by mass or more, 10.0 parts by mass or more, 12.5 parts by mass or more, or 15.0 parts by mass or more.

[0048] On the other hand, if this ratio is 20.0 parts by mass or less, the properties that (A) PP originally has are hardly impaired even by blending the container waste material. From this viewpoint, the content ratio of (B) the container waste material in the resin composition is 20.0 parts by mass or less, 17.5 parts by mass or less, 15.0 parts by mass or less, 12.5 parts by mass or less, or 10.0 parts by mass or less with respect to 100 parts by mass of the resin composition. In addition, when the content ratio of (B) the container waste material in the resin composition is 15.0 parts by mass or less, 12.5 parts by mass or less, or 10.0 parts by mass or less with respect to 100 parts by mass of the resin composition, in addition to the fact that the properties of (A) PP are hardly impaired, there is also an advantage that the impact resistance of the obtained cap is improved.

[0049] (Injection molding) In the present invention, the injection molding when forming a cap from the above resin composition may be carried out by a known method or a method obtained by making any modifications thereto by those skilled in the art. Specifically, general conditions for injection molding of polypropylene resin may be adopted. For example, it may be injection molding at a temperature of 180°C or higher and 280°C or lower, or 200°C or higher and 250°C or lower.

[0050] (The cap to be manufactured) The form of the cap manufactured by the method of the present invention may be arbitrary. The cap can be, for example, a hinge cap, a screw cap, etc., and may also be a cap with an anti-tampering function. Among these caps, the hinge cap is significant from the viewpoints of easy opening and closing of the lid and difficulty in losing the lid.

[0051] Hereinafter, an example of the structure of the cap manufactured by the method of the present invention will be described with reference to the drawings, taking a hinge cap as an example. However, the cap manufactured by the method of the present invention is not limited thereto.

[0052] FIG. 1 shows a schematic perspective view for explaining an example of the configuration of a cap (hinge cap) manufactured by the method of the present invention.

[0053] The hinge cap (100) in FIG. 1 has a cap base body (10) and a lid body (30) connected to the cap base body (10) via a hinge (20).

[0054] The cap base body (10) may have a cap base body flat portion (11) and a cap base body hanging portion (15) held on the cap base body flat portion (11) and extending in a cylindrical shape. A nozzle (12) is formed on the cap base body flat portion (11). The nozzle (12) may be formed to protrude substantially at the center of the cap base body flat portion (11) in a direction opposite to the extending direction of the cap base body hanging portion (15). A nozzle opening (13) for discharging the content of the container body (not shown) is opened in the nozzle (12). Further, the nozzle (12) may have a nozzle engaging protrusion (14) for engaging with an outer ring engaging protrusion (36) described later to maintain the closed state when the lid body (30) is in the closed state.

[0055] The lid body (30) can be swung by the hinge (20) to open and close the cap. In FIG. 1, a hinge cap (100) with the lid body (30) in the open state is shown. The lid body (30) may have a lid hanging portion (31) rising from the hinge (20) and a lid flat portion (32) held on the lid hanging portion (31). The lid body (30) may have an outer ring (35) for forming a seal together with the nozzle (12) when in the closed state. The outer ring (35) may have, for example, a ring, a pin, etc. (not shown) for contacting the tip of the nozzle (12) to form a seal when the lid body (30) is in the closed state for forming the seal. Further, the outer ring (35) may have an outer ring engaging protrusion (36) for engaging with the nozzle engaging protrusion (14) to maintain the closed state when the lid body (30) is in the closed state.

[0056] The hinge (20) has a function of swinging the lid body (30) with respect to the cap base body (10), and may be any type of hinge such as a three-point hinge, a butterfly hinge, a strip hinge, etc.

[0057] Note that the hinge cap (100) is to be used by being connected to the mouth of the container body (not shown) on the back side of the cap base (10) (the area surrounded by the cap base hanging portion (15) and not shown). The form of connection between the back side of the cap base (10) and the mouth of the container body is arbitrary, and may be, for example, a screw-in type, a plugging type, or the like.

[0058] 《Cap》 According to a second aspect of the present invention, (A) Polypropylene and (B) A resin composition containing (b1) polyethylene and (b2) an ethylene-vinyl alcohol copolymer as container waste materials and composed of, wherein the content ratio of the (B) container waste material in the resin composition is 5.0 parts by mass or more and 20.0 parts by mass or less with respect to 100 parts by mass of the resin composition, a cap is provided.

[0059] The cap according to the second aspect of the present invention may be manufactured, for example, by the manufacturing method of the cap of the present invention described above. Therefore, regarding the details of the resin composition constituting the cap according to the second aspect of the present invention, the description of the resin composition in the manufacturing method of the cap of the present invention may be applied as it is.

[0060] Therefore, the (B) container waste material may further contain (b3) acid-modified polyethylene.

[0061] Also, the content ratio of the (b1) polyethylene in the (B) container waste material may be 80.0% by mass or more and 97.0% by mass or less based on the total mass of the (B) container waste material, and the content ratio of the (b2) ethylene-vinyl alcohol copolymer in the (B) container waste material may be 3.0 parts by mass or more and 20% by mass or less based on the total mass of the (B) container waste material. (B) The mass ratio of (b3) acid-modified polyethylene in the container waste material may be 0.3% by mass or more and 5.0% by mass or less based on the total mass of the (B) container waste material. Regarding the preferred content ratios of these components, the description of the resin composition in the method for manufacturing the cap of the present invention may be applied as it is.

[0062] According to a third aspect of the present invention, (A) 80.0% by mass or more and 95.0% by mass or less of polypropylene, (b1) 4.0% by mass or more and 19.5% by mass or less of polyethylene, (b2) 0.15% by mass or more and 4.0% by mass or less of an ethylene-vinyl alcohol copolymer A cap made of a resin composition containing the above is provided.

[0063] The resin composition constituting the cap according to the third aspect of the present invention may further contain 1.0% by mass or less of (b3) acid-modified polyethylene.

[0064] The cap according to the third aspect of the present invention may be manufactured, for example, by the method for manufacturing the cap of the present invention described above. Therefore, regarding each component in the resin composition constituting the cap according to the third aspect of the present invention, the description of each component in the resin composition in the method for manufacturing the cap of the present invention may be applied as it is.

[0065] The content ratios of the respective components of the resin composition constituting the cap according to the third aspect of the present invention may be as follows, respectively.

[0066] The content ratio of (A) polypropylene in the resin composition is 80.0% by mass or more, and may be 82.5% by mass or more, 85.0% by mass or more, 87.5% by mass or more, or 90.0% by mass or more. The content ratio of (A) polypropylene in the resin composition is 95.0% by mass or less, and may be 92.5% by mass or less, 90.0% by mass or less, 87.5% by mass or less, or 85.0% by mass or less.

[0067] The content ratio of (b1) polyethylene in the resin composition is 4.0% by mass or more, and may be 6.0% by mass or more, 8.0% by mass or more, 10.0% by mass or more, 12.0% by mass or more, or 15.0% by mass or more. The content ratio of (b1) polyethylene in the resin composition is 19.5% by mass or less, and may be 18.0% by mass or less, 15.0% by mass or less, 12.0% by mass or less, 10.0% by mass or less, 8.0% by mass or less, or 6.0% by mass or less.

[0068] The content ratio of (b2) ethylene-vinyl alcohol copolymer in the resin composition is 0.15% by mass or more, and may be 0.5% by mass or more, 1.0% by mass or more, 2.0% by mass or more, or 3.0% by mass or more. The content ratio of (b2) ethylene-vinyl alcohol copolymer in the resin composition is 4.0% by mass or less, and may be 3.5% by mass or less, 3.0% by mass or less, 2.5% by mass or less, 2.0% by mass or less, 1.5% by mass or less, or 1.0% by mass or less.

[0069] The resin composition may not contain (b3) acid-modified polyethylene. When the resin composition contains (b3) acid-modified polyethylene, its content ratio may be 0.05% by mass or more, 0.10% by mass or more, 0.20% by mass or more, 0.50% by mass or more, or 0.70% by mass or more. The content ratio of (b3) acid-modified polyethylene in the resin composition is 1.0% by mass or less, and may be 0.80% by mass or less, 0.60% by mass or less, 0.50% by mass or less, 0.30% by mass or less, or 0.20% by mass or less.

[0070] The cap according to the second and third aspects of the present invention may be a hinge cap.

Examples

[0071] 《Example 1》 (1) Manufacture of the cap (B) As the waste container material, a pulverized material obtained by pulverizing a multilayer PE blow bottle waste material to a diameter of about 4 mm was used. This waste material contained the following components (b1) to (b3) in the following ratios. (b1) Component: LDPE (MFR 0.4 g / 10 min (JIS K 7210-1, 190 °C, 2.16 kg)) 90.00 mass % (b2) Component: EVOH (ethylene copolymerization ratio: 32 mol%, MFR: 4.1 g / 10 min (JIS K 6921-2, 190 °C, 2.16 kg), density: 1,180 kg / m 3 ) 8.75 mass % (b3) Component: maleic acid-modified PE (PE-A) 1.25 mass %

[0072] As the PP of component (A), a random copolymer type PP (product name "PM931V" (MFR: 25 g / 10 min (JIS K 6921-2, 230 °C, 2.16 kg), density: 900 kg / m 3 ) produced by Sun Allomer Co., Ltd., pellets) 90 mass %, and (B) Container waste material 10 mass % were dry blended, and the blend was put into an injection molding machine equipped with a mold for cap production, and kneading and injection molding were carried out in the temperature range of 180 °C to 250 °C to produce a hinge cap having the shape shown in Figure 1. This cap has a screw that engages with the mouth of the tube container inside the skirt of the cap body.

[0073] The composition of the obtained cap was as follows. (A) Component: PP, 90.0 mass % (b1) Component: LDPE, 9.00 mass % (b2) Component: EVOH, 0.875 mass % (b3) Component: PE-A, 0.125 mass %

[0074] (2) Evaluation of the cap i) Opening and closing strength The opening strength and closing strength of the obtained cap were measured as follows, respectively, and the opening / closing strength difference was calculated. The "opening strength" refers to the maximum strength when, with the lid body closed, the hook on the pull side of a push-pull gauge is hooked on the flange part of the hinge, the cap is placed on a table, the push-pull gauge is pulled in a direction parallel to the plane of the table (horizontal direction), and the engagement between the nozzle engagement protrusion and the outer ring engagement protrusion is disengaged. On the other hand, the "closing strength" refers to the maximum strength when, with the lid body open, the protruding part on the push side of the push-pull gauge is applied to the center of the flat part of the lid body, the push-pull gauge is pushed in, and the strength when the nozzle engagement protrusion and the outer ring engagement protrusion engage is measured. The "opening / closing strength difference" is the value obtained by subtracting the value of the opening strength from the value of the closing strength. The smaller this value is, the more it can be evaluated that the hinge cap has the characteristic of "being easy to close and difficult to loosen".

[0075] ii) Drop resistance The obtained cap was combined with a 270 mL tube container filled with 270 g of water in a closed state and sealed. After cooling this water-filled container to 5°C, it was dropped onto a concrete floor from a height of 1 m in the direction with the cap on. The cap after dropping was visually observed to check for cracks.

[0076] 《Example 2》 (A) PP and (B) the container waste material were mixed at a ratio of 80% by mass and 20% by mass, and otherwise, in the same manner as in Example 1, a hinge cap was manufactured and evaluated.

[0077] The composition of the obtained cap was as follows. (A) component: PP, 80.0% by mass (b1) component: LDPE, 18.0% by mass (b2) component: EVOH, 1.75% by mass (b3) component: PE-A, 0.25% by mass

[0078] 《Reference Example 1》 A hinge cap was manufactured and evaluated in the same manner as in Example 1, except that (B) the container waste material was not used and only (A) PP was used.

[0079] The above results are shown in Table 1.

[0080]

Table 1

[0081] Referring to Table 1, the following can be understood.

[0082] The cap of Comparative Example 1 with a composition of 100% by mass of (A) PP has appropriate opening strength and closing strength, and gives a comfortable click feeling to the user when opening and closing. However, the cap of Comparative Example 1 is inferior in drop resistance and cracks occurred due to dropping from a height of 1 m.

[0083] On the other hand, the caps of Examples 1 and 2 containing a predetermined amount of (b1) LDPE, (b2) EVOH, and (b3) PE-A derived from (B) container waste material in addition to (A) PP showed opening strength and closing strength equivalent to those of the cap of Comparative Example 1, and were also excellent in drop resistance.

[0084] Furthermore, the caps of Examples 1 and 2 can be evaluated as having the characteristic of "easy to close and difficult to loosen" because the opening and closing strength difference, which is the difference between the closing strength and the opening strength, is smaller compared to the cap of Comparative Example 1.

Explanation of Reference Signs

[0085] 10 Cap base 11 Plane portion of cap base 12 Nozzle 13 Nozzle opening 15 Suspension portion of cap base 14 Nozzle engaging projection 20 Hinge 30 Lid body 31 Lid suspension portion 32 Lid plane portion 35 Outer ring 36 Outer ring engaging projection 100 Hinge cap

Claims

Claim 1 (A) Polypropylene, and (B) A container waste material containing (b1) polyethylene and (b2) an ethylene-vinyl alcohol copolymer, and Injecting and molding a resin composition containing the same, The content ratio of the (B) container waste material in the resin composition is 5.0 parts by mass or more and 20.0 parts by mass or less with respect to 100 parts by mass of the resin composition, A method for manufacturing a cap. Claim 2 The manufacturing method according to claim 1, wherein the (B) container waste material further contains (b3) acid-modified polyethylene. Claim 3 The content ratio of the (b1) polyethylene in the (B) container waste material is 80.0% by mass or more and 97.0% by mass or less based on the total mass of the (B) container waste material, The content ratio of the (b2) ethylene-vinyl alcohol copolymer in the (B) container waste material is 3.0 parts by mass or more and 20% by mass or less based on the total mass of the (B) container waste material, The manufacturing method according to claim 1. Claim 4 The content ratio of the (b1) polyethylene in the (B) container waste material is 80.0% by mass or more and 97.0% by mass or less based on the total mass of the (B) container waste material, The content ratio of the (b2) ethylene-vinyl alcohol copolymer in the (B) container waste material is 3.0 parts by mass or more and 20% by mass or less based on the total mass of the (B) container waste material, The mass ratio of the (b3) acid-modified polyethylene in the (B) container waste material is 0.3% by mass or more and 5.0% by mass or less based on the total mass of the (B) container waste material, The manufacturing method according to claim 2. Claim 5 The manufacturing method according to any one of claims 1 to 4, wherein the (A) polypropylene is a random copolymer type polypropylene. Claim 6 The manufacturing method according to any one of claims 1 to 4, wherein the cap is a hinge cap. Claim 7 (A) Polypropylene, and (B) A container waste material containing (b1) polyethylene and (b2) an ethylene-vinyl alcohol copolymer, and Composed of a resin composition containing the same, The content ratio of the (B) container waste material in the resin composition is 5.0 parts by mass or more and 20.0 parts by mass or less with respect to 100 parts by mass of the resin composition, A cap. Claim 8 The cap according to claim 7, wherein the (B) container waste material further contains (b3) acid-modified polyethylene. Claim 9 The content ratio of the (b1) polyethylene in the (B) container waste material is 80.0% by mass or more and 97.0% by mass or less based on the total mass of the (B) container waste material, The content ratio of the (b2) ethylene-vinyl alcohol copolymer in the (B) container waste material is 3.0 parts by mass or more and 20% by mass or less based on the total mass of the (B) container waste material. The cap according to claim 7.

10. The content ratio of the (b1) polyethylene in the (B) container waste material is 80.0% by mass or more and 97.0% by mass or less based on the total mass of the (B) container waste material. The content ratio of the (b2) ethylene-vinyl alcohol copolymer in the (B) container waste material is 3.0 parts by mass or more and 20% by mass or less based on the total mass of the (B) container waste material. The mass ratio of the (b3) acid-modified polyethylene in the (B) container waste material is 0.3% by mass or more and 5.0% by mass or less based on the total mass of the (B) container waste material. The cap according to claim 8.

11. 80.0% by mass or more and 95.0% by mass or less of (A) polypropylene, 4.0% by mass or more and 19.5% by mass or less of (b1) polyethylene, 0.15% by mass or more and 4.0% by mass or less of (b2) ethylene-vinyl alcohol copolymer A cap made of a resin composition containing the above.

12. The cap according to claim 11, wherein the resin composition further contains 1.0% by mass or less of (b3) acid-modified polyethylene.

13. The cap according to any one of claims 7 to 12, wherein the (A) polypropylene is a random copolymer type polypropylene.

14. The cap according to any one of claims 7 to 12, which is a hinge cap.

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