JP5927876B2 - Case for storing information recording media - Google Patents

Description

  The present invention relates to a case for storing an information recording medium, and relates to a case for storing an information recording medium that is highly fluid, has a good balance of rigidity and impact resistance, does not easily warp a molded product, and does not contaminate the information recording medium. Is.

Propylene polymers are used in various applications by taking advantage of their excellent safety and hygiene, molding processability, cleanliness, colorability, mechanical properties, and barrier properties. In recent years, polypropylene having improved cleanliness has been developed, and expectations for new applications are increasing.
For example, Patent Document 1 proposes a semiconductor transport case using a propylene-based resin composition having a volatile component content of 10 ppm by weight or less.

Another expected use is an information recording medium storage case.
As a typical example of the information recording medium storage case, for example, a pair of resin covers (cases) as shown in FIG. 1 can be freely opened and closed via hinges provided on one side surface thereof. Cases provided are listed, and representatives are CD-ROM, CD, CD-R, DVD, BD (Blu-ray disc), OD (optical disc), MD, MO (magneto-optical disc) between the pair of covers. A disc-shaped information recording medium or a tape-shaped recording medium such as DAT is detachably stored. Information recorded on the information recording medium includes game software, video information such as photographs and movies, and various other information.

  Cases for storing information recording media often have a printed material inserted into the case together with the information recording medium, have excellent transparency for the visibility of the information recording medium itself, and the case is rigid / dimensionally stable. The material is required to have excellent properties, and there is a demand for a material having almost no precipitation component, volatile component, or the like that contaminates the information recording medium. However, none of the conventional polypropylene resins contaminates the storage of the information recording medium or satisfies all the above performance as a case.

In addition, on the other hand, in recent years, there has been a very strong tendency to reduce the thickness of products from the viewpoint of cost reduction and ecology. For example, as a case for storing information recording media, the thickness is less than 1.2 mm. In the case of such a thin-walled case, it is very difficult to find a resin material that satisfies the performance sufficiently at a low cost.
The present invention relates to an information recording medium storage case that does not contaminate the information recording medium storage and satisfies the performance (rigidity, impact resistance, warpage, high fluidity, etc.) as a case.

JP 2011-162210 A

The goal of the present invention is a high flow, rigidity, excellent balance between impact resistance, warpage of the molded product using the hard pro propylene polymer occurs, does not contaminate the information recording medium itself, that is thin It is to provide a case for storing a recording medium.

The present inventor has studied to solve the above problems, the use of the specific propylene polymer, rigid, excellent balance between impact resistance, warpage occurs hardly pro propylene-based polymer molded article The present inventors have found that a thin information storage medium storage case having a thickness of 1.2 mm or less that does not contaminate the used information recording medium can be obtained, and the present invention has been completed.
That is, the present invention provides the following case for storing an information recording medium.

[1] A polypropylene polymer component (A1) having a comonomer content selected from ethylene or an α-olefin having 4 or more carbon atoms of 2% by weight or less and 70 to 99% by weight and an ethylene content of 15 to 85% by weight. The ethylene / propylene copolymer component (A2) is 1 to 30% by weight, the total ethylene content is 0.5 to 20% by weight, and the melt flow rate (230 ° C., 2.16 kg load) is 50 to 150 g / 10. The thickness obtained by molding using a propylene-ethylene block copolymer (A) having a bending elastic modulus (measured in accordance with JIS K7171) of 750 MPa or more and containing no conductive carbon is 1. A case for storing an information recording medium, comprising a pair of cover members of less than 2 mm.
[2] The case for storing an information recording medium according to the above [1], wherein the propylene-ethylene block copolymer (A) is obtained using a Ziegler-Natta catalyst.
[3] The ratio of the vertical / horizontal ratio of the shrinkage (measured in accordance with ASTM-D-955-73) of the propylene-ethylene block copolymer (A) is 0.8 to 1.2 [ The case for storing an information recording medium according to [1] or [2].
[4] The propylene-ethylene block copolymer (A) contains an antistatic agent and / or a lubricant in an amount of less than 0.01 parts by weight with respect to 100 parts by weight of the propylene-ethylene block copolymer (A). The case for storing an information recording medium according to any one of [1] to [3].
[5] The method for producing the information recording medium accommodating case according to the pair of cover members to [1] comprising the resulting Rukoto by injection molding.

  The information recording medium storage case of the present invention has an excellent balance between rigidity and impact resistance even if it is a thin wall of 1.2 mm or less, is less likely to warp a molded product, and does not contaminate the information recording medium storage. This is a medium storage case.

FIG. 3 is a front view, a side view, and a cross-sectional view of an information recording medium storage case molded in the example, showing an example of an information recording medium storage case.

The case for storing an information recording medium of the present invention comprises a polypropylene polymer component (A1) and 1 to 30% by weight of an ethylene / propylene copolymer component (A2), and the total ethylene content is 0.5 to 20% by weight. %, A propylene-ethylene block copolymer (A) having a melt flow rate (230 ° C., 2.16 kg load) of 50 to 150 g / 10 min and a flexural modulus (measured in accordance with JIS K7171) of 750 MPa or more. It is characterized by comprising a pair of cover members having a wall thickness obtained by molding using less than 1.2 mm.
Hereinafter, the present invention will be described in detail.

[Propylene-ethylene block copolymer (A)]
In the present invention, the “block copolymer” does not necessarily have to form a real block copolymer structure, and is a “block copolymer” in the meaning commonly called in the polypropylene business field, preferably Is composed of a crystalline polypropylene polymer component (A1) and a low crystalline or amorphous ethylene / propylene copolymer component (A2), and is preferably obtained by continuous polymerization. Is a composition of a polypropylene polymer component (A1) and an ethylene / propylene copolymer component (A2).
In the present invention, the propylene-ethylene block copolymer (A) includes those obtained by mechanically mixing the component (A1) and the component (A2). However, when the propylene-ethylene block copolymer (A2) is obtained by sequential polymerization, after the components (A1) and (A2) are produced in independent reactors, the obtained components are mechanically treated. Compared to the composition mixed in the above, it is preferable because it has a micro phase separation structure or a co-continuous structure.

[Polypropylene polymer component (A1)]
Component (A1) is a propylene polymer, preferably a propylene homopolymer, but may contain a small amount of a comonomer selected from ethylene and an α-olefin having 4 or more carbon atoms, and its content is It is preferably 2% by weight or less, more preferably 0 to 1% by weight or less, further 0 to 0.5% by weight, and particularly 0% by weight.
The α-olefin having 4 or more carbon atoms is preferably an α-olefin having 4 to 12 carbon atoms, and 1-butene, 1-pentene, 1-hexene, 1-octene, 1-heptene and the like can be preferably exemplified. In particular, ethylene, 1-butene, 1-hexene and 1-octene are preferable.

  The melting point of the polypropylene polymer component (A1) is not limited, but the melting peak temperature (Tm) measured by the DSC method is preferably 135 to 175 ° C.

In order to obtain the polypropylene polymer component (A1), a Ziegler-Natta catalyst or a metallocene catalyst may be used. The metallocene catalyst is not particularly limited, and (i) a group 4 transition metal compound (so-called metallocene compound) containing a ligand having a cyclopentadienyl skeleton and (ii) a metallocene compound reacts with the metallocene catalyst. It is a catalyst comprising a cocatalyst that can be activated to a stable ionic state and, if necessary, (iii) an organoaluminum compound, and any known catalyst can be used.
The polymerization process used for obtaining the component (A1) is not particularly limited, and a known polymerization process can be used. For example, a slurry polymerization method, a bulk polymerization method, a gas phase polymerization method and the like can be used.

[Ethylene / propylene copolymer component (A2)]
Component (A2) is an ethylene / propylene copolymer. The ethylene content of the component (A2) is preferably 15 to 85% by weight, more preferably 25 to 75% by weight, particularly 35 to 65% by weight.
If it is less than 15% by weight, the impact resistance of the product is not sufficient, which is not preferable. Moreover, when it exceeds 85 weight%, there exists a possibility that the impact resistance of a product may deteriorate.

The catalyst used for obtaining the ethylene / propylene copolymer component (A2) is a Ziegler-Natta catalyst or a metallocene catalyst. There is no restriction | limiting in particular as a metallocene catalyst, A well-known thing can be used like the above.
The polymerization process used for obtaining the component (A2) is not particularly limited, and a known polymerization process can be used. For example, a slurry polymerization method, a bulk polymerization method, a gas phase polymerization method and the like can be used.

The propylene-ethylene block copolymer (A) used in the present invention contains a polypropylene polymer component (A1) and an ethylene / propylene copolymer component (A2), and the quantity ratio thereof is determined between the component (A1) and the component. The component (A2) is 1 to 30% by weight based on the total of 100% by weight of (A2). If the component (A2) is less than 1% by weight, the impact resistance of the product is not sufficient, and if the component (A2) exceeds 30% by weight, the product has low rigidity and may not be sufficient.
The preferred composition is 99 to 70% by weight of component (A1), 1 to 30% by weight of component (A2), more preferably 95 to 75% by weight of component (A1) and 5 to 25% by weight of component (A2). .

(Melt blend)
As described above, the propylene-ethylene block copolymer (A) can also be produced by melt blending the component (A1) and the component (A2).
There is no restriction | limiting in the manufacturing method by a melt blend, A well-known method can be employ | adopted widely. Specific examples include component (A1) and component (A2) according to the present invention, and other components blended as necessary, for example, ribbon blender, Henschel mixer, Banbury mixer, single screw or twin screw Examples thereof include a melt kneading method using an extruder, a kneader and the like.

(Sequential polymerization)
The production method of the propylene-ethylene block copolymer (A) used in the present invention may be the above melt blend, but is obtained by sequentially polymerizing the component (A1) and the component (A2) from the viewpoint of physical property balance. It is preferable.
The sequential polymerization method is publicly known, and there is no particular limitation on the specific method. In the first step, 70 to 99% by weight of the component (A1) is polymerized, and then in the second step, the component (A2) is changed to 1 to 1. It can be obtained by sequential polymerization of 30% by weight.
When performing sequential polymerization, either a batch method or a continuous method can be used, but it is generally desirable to use a continuous method from the viewpoint of productivity.

In the case of a batch method, it is possible to polymerize component (A1) and component (A2) separately using a single reactor by changing the polymerization conditions with time. As long as the effect of the present invention is not impaired, a plurality of reactors may be connected in parallel.
In the case of a continuous process, since it is necessary to polymerize component (A1) and component (A2) separately, it is necessary to use a production facility in which two or more reactors are connected in series, but this does not impair the effects of the present invention. As long as each of the component (A1) and the component (A2) is used, a plurality of reactors may be connected in series and / or in parallel.

As the polymerization process, any polymerization method such as a slurry method, a bulk method, or a gas phase method can be used. Since component (A2) is readily soluble in organic solvents such as hydrocarbons and liquefied propylene, it is desirable to use a gas phase method in the production of component (A2). There are no particular problems with the production of component (A1), but in order to produce component (A1) with relatively low crystallinity, a vapor phase method is used to avoid problems such as adhesion. It is desirable to use
Therefore, it is most desirable to first polymerize the component (A1) by the bulk method or the gas phase method using the continuous method and then polymerize the component (A2) by the gas phase method.

The polymerization temperature can be used without any particular problem as long as it is in a commonly used temperature range. Specifically, a range of 0 ° C. to 200 ° C., more preferably 40 ° C. to 100 ° C. can be used.
The polymerization pressure varies depending on the process to be selected, but can be applied without any problem as long as it is in a pressure range usually used. Specifically, a range of greater than 0 to 200 MPa, more preferably 0.1 MPa to 50 MPa can be used. At this time, an inert gas such as nitrogen may coexist.

[Characteristics of propylene-ethylene block copolymer (A)]
The propylene-ethylene block copolymer (A) needs to have a total ethylene content of 0.5 to 20% by weight. If the total ethylene content is less than 0.5% by weight, the impact resistance is insufficient, and if it exceeds 20% by weight, the rigidity may be insufficient. The total ethylene content is preferably 3 to 18% by weight, more preferably 5 to 15% by weight.

  Further, the propylene-ethylene block copolymer (A) is required to have a flexural modulus of 750 MPa or more, preferably 900 MPa or more, more preferably 1100 MPa or more in terms of rigidity, in accordance with JIS K7171. The upper limit is preferably 1800 MPa or less, more preferably 1600 MPa or less. If the flexural modulus is less than 750 MPa, the rigidity is low, so that it easily deforms and may not fulfill the function as a case.

  Further, the propylene-ethylene block copolymer (A) needs to have a high MFR with a melt flow rate (MFR) based on JIS K7120 (230 ° C., 2.16 kg load) of 50 to 150 g / 10 min. Yes, 70 to 120 g / 10 min is preferable, and 75 to 100 g / 10 min is more preferable. If the MFR is less than 50 g / 10 minutes, the molding processability is deteriorated, and it is difficult to obtain a satisfactory product. If it exceeds 150 g / 10 minutes, there is a concern that the mechanical properties are deteriorated.

  Moreover, it is preferable that ratio of the length direction / width direction of the shrinkage | contraction rate based on ASTM-D-955-73 is 0.8-1.2. By setting it within this range, it is easy to obtain an information recording medium storage case with almost no warp deformation.

[Additive]
The propylene-ethylene block copolymer (A) used in the present invention has various antioxidants, ultraviolet absorbers, light stabilizers, nucleating agents, neutralization, etc., which are used as stabilizers for propylene polymers. An additive such as an agent can be blended.

In particular, regarding the antistatic agent and the lubricant, it is preferable that the antistatic agent and the lubricant are each less than 0.01 parts by weight with respect to 100 parts by weight of the propylene-ethylene block copolymer (A). By making the amount less than 0.01 parts by weight, an information recording medium storage case that does not contaminate the information recording medium can be obtained.
Antistatic agents are known antistatic agents and include, for example, stearic acid monoglyceride, alkyldiethanolamine, etc., but preferably not included.
The lubricant is a known lubricant and includes, for example, oleic acid amide, erucic acid amide, butyl stearate, silicone oil, and the like, and is preferably not included.

  Antioxidants include bis (2,6-di-t-butyl-4-methylphenyl) pentaerythritol-di-phosphite, di-stearyl-pentaerythritol-di-phosphite, bis (2,4-diphenyl). -T-butylphenyl) pentaerythritol di-phosphite, tris (2,4-di-t-butylphenyl) phosphite, tetrakis (2,4-di-t-butylphenyl) -4,4'-biphenylene -Phosphorous antioxidants such as di-phosphonite, tetrakis (2,4-di-t-butyl-5-methylphenyl) -4,4'-biphenylene-di-phosphonite, 2,6-di -T-butyl-p-cresol, tetrakis [methylene (3,5-di-t-butyl-4-hydroxyhydrocinnamate)] methane, 1,3,5-to Phenolic compounds such as methyl-2,4,6-tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene, tris (3,5-di-t-butyl-4-hydroxybenzyl) isocyanurate Thio systems such as antioxidants, di-stearyl-ββ'-thio-di-propionate, di-myristyl-β, β'-thio-di-propionate, di-lauryl-β, β'-thio-di-propionate An antioxidant etc. are mentioned.

  Examples of the ultraviolet absorber include 2-hydroxy-4-n-octoxybenzophenone, 2- (2′-hydroxy-3 ′, 5′-di-t-butylphenyl) -5-chlorobenzotriazole, 2- (2 And ultraviolet absorbers such as' -hydroxy-3'-t-butyl-5'-methylphenyl) -5-chlorobenzotriazole.

  Examples of the light stabilizer include n-hexadecyl-3,5-di-t-butyl-4-hydroxybenzoate, 2,4-di-t-butylphenyl-3 ′, 5′-di-t-butyl-4 ′. -Hydroxybenzoate, bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, dimethyl-2- (4-hydroxy-2,2,6,6-tetramethyl-1-piperidyl) succinate ) Ethanol condensate, poly {[6-[(1,1,3,3-tetramethylbutyl) amino] -1,3,5-triazine-2,4diyl] [(2,2,6,6- Tetramethyl-4-piperidyl) imino] hexamethylene [(2,2,6,6-tetramethyl-4-piperidyl) imino]}, N, N′-bis (3-aminopropyl) ethylenediamine-2,4- Bis [N-butyl-N- ( , Mention may be made of a light stabilizer such as 2,2,6,6-pentamethyl-4-piperidyl) amino] -6-chloro-1,3,5-triazine condensate.

  Further, amine-based antioxidants represented by the following chemical formula (1) and the following general formula (2) having good NOx gas discoloration resistance, 5,7-di-t-butyl-3- (3,4-di Examples include lactone antioxidants such as -methyl-phenyl) -3H-benzofuran-2-one, and vitamin E antioxidants such as the following chemical formula (3).

（式中、Ｒ１とＲ２は、炭素数１４〜２２のアルキル基を示す。）

(In the formula, R1 and R2 represent an alkyl group having 14 to 22 carbon atoms.)

  Specific examples of the nucleating agent are commercially available products such as Hyperform HPN68L manufactured by Meriken Co., Ltd., sorbitol nucleating agent, organic phosphate nucleating agent and aromatic phosphate esters, A known nucleating agent such as talc can be added within a range that does not significantly impair the effects of the present invention. However, it is preferable that talc or sorbitol nucleating agent is blended or not blended. By using these, it becomes easy to make the ratio of shrinkage ratios in the range of 0.8 to 1.2, and warp deformation is easily suppressed.

  Specific examples of the neutralizer include metal fatty acid salts such as calcium stearate, zinc stearate, and magnesium stearate, hydrotalcite (trade name: magnesium aluminum composite hydroxide salt of Kyowa Chemical Industry Co., Ltd.), Mizukarak ( Product name: Lithium aluminum composite hydroxide salt of Mizusawa Chemical Co., Ltd.).

  In addition, an antistatic agent, a dispersant such as a fatty acid metal salt, a dye, a pigment, polyethylene, an olefin elastomer, and the like can be blended within a range that does not impair the effects of the present invention.

[Method for manufacturing case for storing information recording medium]
In order to manufacture a case for storing information recording media, a propylene-ethylene block copolymer (A) and, if necessary, an antioxidant, a neutralizing agent, etc., are added to a Henschel mixer, a super mixer, a ribbon blender, etc. After mixing, the mixture is melt-kneaded in a temperature range of 190 to 260 ° C. with a normal single-screw extruder, twin-screw extruder, Banbury mixer, plastic bender, roll, or the like, and first formed into resin pellets.
The information recording medium storage case is obtained by using the above resin composition pellets, using a mold designed to have a wall thickness of less than 1.2 mm, and preferably by injection molding. The molding temperature is preferably about 200 to 250 ° C.

A typical example of the specific shape is as shown in FIG. 1, and a flat case with a hinge portion provided on one side surface is molded and combined with each other through both hinge portions so that it can be opened and closed. Can be manufactured.
The storage case thus obtained has a disk shape represented by CD-ROM, CD, CD-R, DVD, BD (Blu-ray disc), OD (optical disc), MD, and MO (magneto-optical disc). Or a tape-like recording medium such as DAT is detachably stored.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited at all by these description. In each example and comparative example, the physical properties used were measured by the following method, and the following was used as the propylene-ethylene block copolymer (A).

[Measurement method]
(1) Calculation of amount of each component It calculated using the method as described in the Example of Unexamined-Japanese-Patent No. 2011-98762 using TREF (temperature rise solubility fractionation).
(2) Calculation of ethylene content
The ethylene content in the random copolymer was measured by infrared spectroscopy using a characteristic absorber of 733 cm ⁻¹ with an ethylene / propylene random copolymer whose composition was verified by ¹³ C-NMR as a reference substance. The pellets were formed into a film having a thickness of about 500 microns by press molding.
(3) MFR: Measured according to JIS K7210 at a heating temperature of 230 ° C. and a load of 21.2 N.

(4) Flexural modulus:
The value was measured according to JIS K7171.
(5) Shrinkage ratio:
The shrinkage rate based on ASTM-D-955-73 was measured, and the ratio in the vertical / horizontal direction was calculated.
(6) In each material, the wall thickness is 0.9 mm (however, the hinge wall thickness is 0.4 mm), the length is 150 mm × the width is 150 mm, and the side height is 5 mm (details of the shape and dimensions are shown in FIG. 1) The information recording medium storage case was molded, and the moldability and the state of the molded product were confirmed.

[Materials used]
(1) Propylene-ethylene block copolymer (A)
[PP-1]
Propylene-ethylene block copolymer manufactured by Nippon Polypro Co., Ltd., trade name “BC08F”
Using Ziegler-Natta catalyst MFR: 75 g / 10 min Total ethylene content: 8% by weight
Ethylene / propylene copolymer component (A2) amount: 20% by weight
Flexural modulus: 1,300 MPa
Vertical / horizontal ratio of shrinkage rate: 0.87
[PP-2]
Propylene-ethylene block copolymer manufactured by Nippon Polypro Co., Ltd., trade name “BC10HRF”
Using Ziegler-Natta catalyst MFR: 100 g / 10 min Total ethylene content: 8% by weight
Ethylene / propylene copolymer component (A2) amount: 20% by weight
Flexural modulus: 1,200 MPa
Vertical / horizontal ratio of shrinkage rate: 1.0

[PP-3]
Propylene-ethylene block copolymer manufactured by Nippon Polypro Co., Ltd., trade name “BC3LS”
Using Ziegler-Natta catalyst MFR: 10 g / 10 min Total ethylene content: 7% by weight
Ethylene / propylene copolymer component (A2) amount: 14% by weight
Flexural modulus: 1,500 MPa
Vertical / horizontal ratio of shrinkage rate: 1.13
PP-3 is a propylene-ethylene block copolymer that does not satisfy the requirements as the propylene-ethylene block copolymer (A) in the present invention.

(Examples 1-2, Comparative Example 1)
Using the propylene-ethylene block copolymers PP-1 to PP-3, the above-described information recording medium storage case is manufactured at an injection molding machine IS100GN manufactured by Toshiba Machine Co., Ltd. at a resin temperature of 230 ° C. and an injection pressure of 50 MPa. As a result of molding, a good case was obtained using PP-1 and PP-2. On the other hand, when PP-3 was used, the fluidity was poor, and the resulting case was found to warp the case plane.
The evaluation results are shown in the following table.

  The information recording medium storage case of the present invention is useful as a storage case for various information recording media, and has very high industrial applicability.

Claims (5)

  Ethylene / propylene having 70 to 99% by weight of a polypropylene polymer component (A1) having a comonomer content of 2% by weight or less selected from ethylene or an α-olefin having 4 or more carbon atoms and 15 to 85% by weight of ethylene content Copolymer component (A2) 1-30 wt%, total ethylene content 0.5-20 wt%, melt flow rate (230 ° C., 2.16 kg load) 50-150 g / 10 min, bending The elastic modulus (measured in accordance with JIS K7171) is 750 MPa or more, and the wall thickness obtained by molding using the propylene-ethylene block copolymer (A) containing no conductive carbon is less than 1.2 mm A case for storing an information recording medium comprising a pair of cover members. Propylene - ethylene block copolymer according to claim 1 ratio in the longitudinal direction / transverse direction is 0.8 to 1.2 of shrinkage (A) (measured in accordance with ASTM-D-955-73) Case for storing information recording media. Propylene - ethylene block copolymer (A), antistatic agents and / or lubricants, propylene - ethylene block copolymer (A) with respect to 100 parts by weight, or claim 1 containing less than 0.01 part by weight 2. A case for storing an information recording medium according to 2 . The case for storing an information recording medium according to any one of claims 1 to 3, wherein the propylene-ethylene block copolymer (A) is obtained using a Ziegler-Natta catalyst. Manufacturing method .   The method for manufacturing the case for storing an information recording medium according to claim 1, comprising obtaining the pair of cover members by injection molding.

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