JP2009040427A - Shock-absorbing material and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a shock-absorbing material which is excellent in operability such as mountability, is easily manufactured, has high adhesiveness to electronic components, and also has a function of gas-barrier properties. <P>SOLUTION: The shock-absorbing material is fitted to the outer face of an electronic device under a condition covering to protect the electronic device. The shock-absorbing material is formed of a thermoplastic elastomer composition and is characterized in that the adhesiveness of the outer peripheral part are less than that of the inner peripheral part brought into contact with the electronic device. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a cushioning material and a manufacturing method thereof, and more particularly to a cushioning material that protects an electronic device such as a hard disk device from impact and vibration and a manufacturing method thereof.

In order to protect an electronic device such as a hard disk device from impact or vibration, a buffer material using an elastic material or the like is used. Usually, the cushioning material is designed to be smaller than the electronic device and prevents it from coming off the electronic device.
As a material for forming the buffer material, a gelatin resin in which the oil component is included in the gap between the network structure of the base polymer to lose the fluidity is used. Such a glue resin can effectively relieve impact and vibration, and can also provide airtightness to an electronic device such as a hard disk device.
However, since the glue resin has adhesiveness on the surface, workability may be impaired. That is, when an electronic device such as a hard disk device is disposed in the accommodation space, if the buffer material is formed of a gelatin resin, insertion and removal of the electronic device may be extremely difficult due to the adhesiveness of the surface. there were. In addition, dust and the like are easily attached, and there is a problem particularly in precision equipment such as electronic devices.

From the above-mentioned problems, a gelatinous portion made of a gelatinous resin material to which a softening agent imparting flexibility is added to a thermoplastic resin as a main component, and a non-glueous resin material A structure having a function as a cushioning material or packing provided with a non-glue-like part is proposed (see Patent Document 1). According to Patent Document 1, the range to be a non-glue-like part is appropriately adjusted so that the non-glue-like part comes into contact with a place where contact with the glue-like part becomes a problem. By arranging, problems such as workability caused by contact with the gelatinous body portion can be avoided.
However, in the structure disclosed in Patent Document 1, a gelatinous resin material and a non-gelatinous resin material are respectively prepared, for example, a film or the like is manufactured in advance using the non-gelatinous resin material. Since a manufacturing method such as injecting this into a mold and injecting a gelatinous resin material is employed, there is a problem that the manufacturing is complicated.

In addition, a structure having an embossed surface in which an embossing process is further applied to the gelatinous portion of the structure disclosed in Patent Document 1 has been proposed (see Patent Document 2). According to Patent Document 2, since the adhesiveness of the surface of the gelatinous body portion is reduced, the workability is improved and it is difficult to adhere to the hand or the like during the work. Further, the embossing makes it difficult for the fluid component of the gelatinous resin to ooze out on the surface.
However, the structure disclosed in Patent Document 2 also requires a manufacturing method similar to that of Patent Document 1 and has an embossing process, which is further complicated.

Moreover, the protective material which combined the buffer member and different materials is proposed for the purpose of improving the attachment property of a buffer material (refer patent document 3). According to the description in Patent Document 3, the protective material is formed of a buffer member and a molded product made of a material different from the buffer member, and the molded product is inserted into the buffer member in a state in which a part thereof is exposed from the buffer member. The molded product is designed to come into contact with the outer surface of the electronic device when attached to the electronic device. Since this protective material can make the frictional resistance smaller than that of the buffer member at the portion where the molded product comes into contact with the outer surface of the electronic device, smooth attachment is possible and accurate attachment can be realized.
However, since the protective material disclosed in Patent Document 3 is manufactured by molding a molded product by injection molding or the like, putting it in a mold, and insert-molding a buffer member, it is said that the manufacturing is complicated. There is a problem.
In addition, electronic devices such as hard disk devices are sealed with gaskets and the like in order to dislike gas and water vapor from the outside, but if the same gas barrier property can be given to the buffer material, more electronic devices can be obtained. A gas barrier property can be completely applied, which is preferable. However, although the protective material can improve the effect as a cushioning material and the mounting property, it cannot provide the gas barrier effect.

JP 2001-30431 A JP 2001-19772 A JP 2007-118977 A

  Under such circumstances, the present invention provides a cushioning material that is excellent in workability such as attachment, is easy to manufacture, has high adhesion to electronic components, and also has a gas barrier function, and a method for manufacturing the same. It is intended to do.

The inventors of the present invention have made extensive studies in order to achieve the above object, and have found that the above-described problems can be solved by subjecting the outer peripheral portion of the formed cushioning material to embossing. The present invention has been completed based on such findings.
That is, the present invention is a cushioning material that is attached to an outer surface of an electronic device so as to cover the electronic device and protects the electronic device, and is formed of a thermoplastic elastomer composition, and the adhesiveness of the outer peripheral portion is the electronic device. The shock absorbing material characterized by being small with respect to the adhesiveness of the inner peripheral part which contact | connects is provided.

  According to the present invention, it is possible to effectively protect an electronic device from impact and vibration, excellent workability such as attachment, easy manufacture, high adhesion to electronic components, and excellent gas barrier properties. A cushioning material and a method for manufacturing the same can be provided.

The shock-absorbing material of the present invention is a shock-absorbing material that is attached to the outer surface of the electronic device so as to cover the electronic device and protects the electronic device, and is formed of a thermoplastic elastomer composition. It is characterized by being small with respect to the adhesiveness of the inner peripheral part in contact with the.
Hereinafter, a mode in which the cushioning material of the present invention is attached to an electronic device such as a hard disk device will be described with reference to FIGS.
FIG. 1 is a conceptual diagram showing an electronic device which is an object to be protected from impact and vibration in the present invention. The electronic device 10 such as a hard disk is covered and protected by a cover plate 11 and a base plate 12 so as to sandwich a sealing material 13 such as a gasket. The sealing material 13 functions to block gas, water vapor, and the like from the outside. As shown in FIGS. 2 and 3, the cushioning material of the present invention covers the entire edge portion of the electronic device 10 along the sealing material 13.
In addition, although the inner peripheral part in the shock absorbing material of this invention means the inner part which contacts the sealing material 13 shown by the code | symbol 3, here includes the part 4 which contacts the top plate part of the cover plate 11 or the base plate 12 be able to. On the other hand, the outer peripheral portion in the cushioning material of the present invention refers to a surface in a direction orthogonal to the sealing material 11 indicated by reference numeral 2, but may include a surface 5 parallel to the sealing material 11.

The cushioning material 1 of the present invention is characterized in that the adhesiveness of the outer peripheral portion 2 is smaller than the adhesiveness of the inner peripheral portion 3. By adopting such a structure, it is difficult for the cushioning material to adhere to the hand or the like during work, and workability is greatly improved. In addition, when an electronic device such as a hard disk device is disposed in the accommodation space, since the adhesiveness of the surface is low, the electronic device can be easily inserted and removed, and the workability is remarkably improved.
On the other hand, since the inner peripheral portion 3 of the cushioning material 1 of the present invention has high adhesiveness, the gas barrier property can be improved, and in addition to the function as a cushioning material, it can have a function as a sealing material. it can. In particular, as shown in FIGS. 2 and 3, the cushioning material of the present invention is attached in a state of covering the electronic device 10, so that the gas barrier property can be improved.

In the buffer material of the present invention, the adhesiveness of the outer peripheral portion is preferably 8N or less, more preferably 5N or less, when measured by the following method. Adhesiveness is suppressed as it is 8 N or less, and the effect of the present invention can be sufficiently achieved.
On the other hand, the adhesiveness of the inner periphery is preferably in the range of more than 8 to 12N. If it exceeds 8N, there is sufficient adhesiveness, and sufficient sealing properties, gas barrier properties, etc. can be imparted to the electronic device.
(Measurement method of adhesiveness)
Using a tack meter ("Pikkuma Tac Tester" manufactured by Toyo Seisakusho Co., Ltd.), with a crimping load of 500 g, a test speed (rising speed) of 50 cm / min, a crimping speed (descending speed) of 50 cm / min, and a crimping time of 10 seconds. Measurements were made.

  Although various methods can be taken as a method of reducing the adhesiveness of the outer peripheral portion 2, in the present invention, it is possible to reduce the adhesiveness of the outer peripheral portion by subjecting the outer peripheral portion 2 to embossing. Easy and preferred. There are various kinds of texture patterns such as leather patterns, but not particularly limited.

  As a method for embossing the outer periphery of the cushioning material of the present invention, there is a method of producing the cushioning material of the present invention by injection molding and embossing the portion that contacts the outer periphery of the cushioning material of the mold used for injection molding It is preferable from the viewpoint of productivity. Here, the wrinkle processing means that after drawing the basic pattern of the wrinkle pattern with acid-resistant ink on the cavity defining surface of the mold, the cavity defining surface is corroded with an acidic liquid, etc. The process is to adjust the gloss with sand blast or glass beads if necessary, and to form irregularities on the cavity surface by these processes.

Moreover, it is preferable to make the size of the cushioning material of the present invention smaller than the size of the electronic device to be protected. More specifically, as shown in FIG. 4, it means that the lengths of the portions x2, y2, and z1 of the cushioning material that are in contact with the electronic device are shorter than the width, length, and thickness of the electronic device, respectively. .
Then, when mounting the buffer material on the electronic device, the buffer material of the present invention formed of the thermoplastic elastomer composition is stretched and mounted on the electronic device. By taking such an aspect, adhesiveness with an electronic device can be improved and higher sealing performance can be obtained.

  The specific size of the cushioning material is not particularly limited as long as the cushioning material can be easily mounted according to the size of the electronic device and the like and a sufficient sealing property can be obtained, but x2, y2, and z1 are not limited. The width and length of the electronic device are each preferably about 0.1 to 0.5 mm smaller.

As the thermoplastic elastomer composition for forming the cushioning material of the present invention, a material known as a sealing material such as a gasket can be suitably used. In particular, the following (a) to (c) A thermoplastic elastomer composition comprising the components is preferred from the viewpoints of high impact resistance as a cushioning material and excellent sealing properties. That is, (a) hydrogenation obtained by hydrogenating a block copolymer comprising at least one polymer block mainly composed of a vinyl aromatic compound and at least one polymer block mainly composed of a conjugated diene compound. 100 parts by mass of a hydrogenated block copolymer having a block copolymer and a number average molecular weight of 60000 or more, (b) a non-aromatic rubber softener 1 having a kinematic viscosity at 40 ° C. of 100 mm ² / s or more A thermoplastic elastomer composition comprising ˜3000 parts by mass and (c) 0-50 parts by mass of a polyolefin-based resin mainly composed of polypropylene.

  Examples of the hydrogenated block copolymer in the component (a) include a block copolymer of polybutadiene and polystyrene, a block copolymer of polyisoprene and polystyrene, or a polybutadiene or ethylene-butadiene random copolymer. Obtained by hydrogenating a block copolymer of polystyrene and polystyrene, for example, diblock copolymer of crystalline polyethylene and polystyrene, styrene-ethylene / butylene-styrene triblock copolymer (SEBS), styrene- Examples thereof include triblock copolymer (SEPS) of ethylene / propylene-styrene, and styrene-ethylene / butylene-styrene block copolymer or styrene-ethylene / propylene-styrene block copolymer. As the component (a), a block copolymer having at least two polymer blocks mainly composed of vinyl aromatic compounds and at least one polymer block mainly composed of conjugated diene compounds (for example, styrene-butadiene- A hydrogenated block copolymer obtained by hydrogenating a styrene block copolymer, a styrene-isoprene-styrene block copolymer, or the like) is more preferable. These hydrogenated block copolymers preferably have a number average molecular weight of 60000 or more. When the number average molecular weight is 60000 or more, bleeding of the softening agent is suppressed and compression set is small. The upper limit of the number average molecular weight is not particularly limited, but is usually about 400,000.

  The content of the amorphous styrene block in the hydrogenated block copolymer is 10 to 70% by mass, preferably 15 to 60% by mass. The glass transition temperature (Tg) of the amorphous styrene block portion is 60 ° C. or higher, preferably 80 ° C. or higher. Also, the polymer at the portion connecting the amorphous styrene blocks at both ends is preferably amorphous, and examples thereof include an ethylene-butylene copolymer, a butadiene polymer, and an isoprene polymer. These blocks or random copolymers may be used. In addition, although these hydrogenated block copolymers are mainly used independently, you may blend and use 2 or more types.

In the thermoplastic elastomer composition, the non-aromatic rubber having a kinematic viscosity of 100 mm ² / s or more at 40 ° C. as the component (b) for the purpose of reducing the hardness of the thermoplastic elastomer of the component (a). Formulate softener. It is preferable that the kinematic viscosity of the softening agent at 40 ° C. is 100 mm ² / s or more because there is no weight loss or bleeding due to volatilization of the composition. The kinematic viscosity, in terms of practical use and manufacturing, preferably from 100~10000mm ² / s at 40 ° C., in particular 200~5000mm ² / s are preferred. Further, from the viewpoint of molecular weight, the number average molecular weight is preferably less than 20,000, particularly 10,000 or less, particularly 5000 or less. As such a softening agent, usually a liquid or liquid at room temperature is preferably used. Moreover, both hydrophilic and hydrophobic softeners can be used. The softener having such properties can be appropriately selected from various non-aromatic rubber softeners such as mineral oil, vegetable oil, and synthetic. Here, examples of mineral oils include process oils such as naphthenic and paraffinic, and vegetable oils include castor oil, cottonseed oil, linseed oil, rapeseed oil, soybean oil, palm oil, coconut oil, peanut oil, Examples include wax, pine oil, and olive oil. Especially, it is 1 type, or 2 or more types selected from mineral oil type paraffin oil, naphthenic oil, or synthetic polyisobutylene type oil, and the number average molecular weight is 450-5000.

  The above softeners may be used alone or in combination of two or more as long as the compatibility with each other is good. Although the compounding quantity of these softeners is 1-3000 mass parts with respect to 100 mass parts of said (a) component, Preferably it is 50-1000 mass parts, Most preferably, it is 100-300 mass parts. When the blending amount is 1 part by mass or more, sufficient hardness reduction can be achieved, and sufficient flexibility of the thermoplastic elastomer composition can be obtained. On the other hand, when the amount is 3000 parts by mass or less, the softener does not bleed and sufficient mechanical strength of the thermoplastic elastomer composition can be obtained. The amount of the softening agent is appropriately selected within the above range depending on the molecular weight of the hydrogenated block copolymer (a) and the type of other components added to the hydrogenated block copolymer. It is preferable.

  In order to improve the workability and heat resistance of the composition, a polyolefin-based hydrocarbon resin mainly composed of polypropylene can be added to the thermoplastic emulsomer composition. Examples of the resin include isotactic polypropylene, a copolymer of propylene and a small amount of other α-olefin (for example, propylene-ethylene copolymer, propylene / 4-methyl-1-pentene copolymer), and the like. be able to. When a copolymer of isotactic polypropylene is used as the polyolefin resin, those having an MFR (JIS K7210) in the range of 0.1 to 100 g / 10 minutes, particularly 0.5 to 50 g / 10 minutes can be preferably used. (C) Although the compounding quantity of a component is 0-50 mass parts with respect to 100 mass parts of said (a) component, Preferably it is 0-30 mass parts, Most preferably, it is 5-20 mass parts. When the blending amount is 50 parts by mass or less, the thermoplastic elastomer composition obtained does not have too high hardness.

  In the thermoplastic elastomer composition, a polystyrene resin can be used in combination with the component (c) in order to improve the processability and heat resistance of the composition. As the polystyrene resin, those obtained by either a radical polymerization method or an ionic polymerization method can be suitably used as long as they are obtained by a known production method. The number average molecular weight of the polystyrene resin is preferably selected from the range of 5,000 to 500,000, more preferably 10,000 to 200,000, and the molecular weight distribution [ratio of weight average molecular weight (Mw) to number average molecular weight (Mn) (Mw / Mn) ] Is preferably 5 or less. Examples of the polystyrene resin include polystyrene, styrene-butadiene block copolymer having a styrene unit content of 60% by mass or more, rubber-reinforced polystyrene, poly α-methylstyrene, polypt-butylstyrene, and the like. May be used alone or in combination of two or more. Furthermore, a copolymer obtained by polymerizing a mixture of monomers constituting these polymers can also be used. In the thermoplastic elastomer composition of the present invention, when a polystyrene resin is used in combination with the component (c), the hardness of the resulting composition tends to be higher than when no polystyrene resin is used in combination. Therefore, the hardness of the thermoplastic elastomer composition obtained can also be adjusted by selecting these compounding ratios. In this case, the ratio of polyolefin resin / polystyrene resin is preferably selected from the range of 95/5 to 5/95 (mass ratio).

  In the above thermoplastic elastomer composition, the polymer organic material constituting the thermoplastic elastomer composition preferably has a three-dimensional continuous network skeleton structure, and the formed three-dimensional continuous network skeleton structure has an average diameter of the skeleton. 50 μm or less, preferably 30 μm or less, and the average diameter of the cells (mesh) is 500 μm or less, preferably 300 μm or less. The volume fraction of the polymer organic material is expressed as [volume of polymer organic material / (polymer organic material of Volume + volume of softening agent)] × 100 (%), the volume fraction of the polymer organic material is preferably 50% or less, particularly 33% or less.

The thermoplastic elastomer composition may be blended with a polyphenylene ether resin as desired for the purpose of improving the compression set of the composition. The compounding quantity of polyphenylene ether resin can be suitably selected in the range of 10-250 mass parts with respect to 100 mass parts of thermoplastic elastomer compositions. If the blending amount is 10 parts by mass or more, the effect of improving compression set is sufficient, and if it is 250 parts by mass or less, the hardness of the thermoplastic elastomer composition becomes appropriate.
Further, the thermoplastic elastomer composition includes clay, diatomaceous earth, silica, talc, barium sulfate, calcium carbonate, magnesium carbonate, metal oxide, mica, graphite, flaky inorganic additives such as aluminum hydroxide, Metal powder, wood chips, glass powder, ceramic powder, granular or powdered solid filler such as granular or powder polymer, and other various natural or artificial short fibers, long fibers (eg, straw, hair, glass fiber, metal fiber) And various other polymer fibers).

Moreover, weight reduction can be attained by mix | blending an organic hollow filler which consists of a hollow filler, for example, inorganic hollow fillers, such as a glass balloon and a silica balloon, a polyvinylidene fluoride, a polyvinylidene fluoride copolymer, etc. Furthermore, in order to improve various physical properties such as weight reduction, it is possible to mix various foaming agents, and it is also possible to mix gas mechanically during mixing.
Furthermore, as other additives, flame retardants, antibacterial agents, hindered amine light stabilizers, ultraviolet absorbers, antioxidants, colorants, silicone oils, silicone polymers, coumarone resins, coumarone-indene resins, Various tackifiers such as phenol terpene resins, petroleum hydrocarbons, rosin derivatives, etc., adhesive elastomers such as Rheostomer B (trade name: manufactured by Riken Vinyl Co., Ltd.), Hibler (trade name: manufactured by Kuraray Co., Ltd.) Other thermoplastic elastomers such as a block copolymer in which polystyrene blocks are linked to both ends of a vinyl-polyisoprene block) and Norex (trade name: polynorbornene obtained by ring-opening polymerization of norbornene). Or resin etc. can be used together.

  The manufacturing method of a thermoplastic elastomer composition is not specifically limited, A well-known method is applicable. For example, the above-mentioned components and optional additive components are melt-mixed using a heating kneader, such as a single screw extruder, twin screw extruder, roll, Banbury mixer, plastic bender, kneader, high shear mixer, etc. It can be easily produced by kneading and further adding a crosslinking agent such as an organic peroxide, a crosslinking aid, etc., if necessary, or mixing these necessary components at the same time and heating and kneading. . Further, a thermoplastic elastomer composition prepared by kneading a polymer organic material and a softening agent is prepared in advance, and this composition is further added to one or more polymer organic materials of the same type or different types from those used here. It can also be produced by mixing. Further, the thermoplastic elastomer composition of the present invention can be crosslinked by adding a crosslinking agent such as an organic peroxide, a crosslinking aid or the like.

EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited at all by these examples.
Evaluation in the following examples and comparative examples was performed by the following methods.
(Evaluation methods)
Adhesiveness: About the buffer material obtained in each Example and Comparative Example, the adhesiveness of an outer peripheral part and an inner peripheral part was evaluated by the method described in the specification text.

Example 1
100 parts by mass of SEPS having a number average molecular weight of 100,000 and a styrene content of 30% by mass, a paraffinic oil having a kinematic viscosity of 380 mm ² / s at 40 ° C. (trade name: Diana Process Oil PW380, manufactured by Idemitsu Kosan Co., Ltd.) 150 parts by mass of average molecular weight 750) and 12.5 parts by mass of polypropylene were blended to obtain a thermoplastic elastomer composition.
Next, using a mold that has been subjected to texture processing on the portion that contacts the outer periphery of the buffer material, and using the thermoplastic elastomer composition, a buffer material having a shape as shown in FIG. 4 is formed by injection molding. Manufactured. As for the size of the cushioning material, x, x1, x2, y, y1, y2, z, and z1 shown in FIG. 4 are as follows, and the outer periphery of the cushioning material was subjected to embossing.
x = 61mm, x1 = 4mm, x2 = 53mm
y = 78mm, y1 = 4mm, y2 = 70mm
z = 11mm, z1 = 3mm
When the adhesiveness of this buffer material was evaluated by the above method, the outer peripheral portion was 8.0 N and the inner peripheral portion was 10.0 N. Further, in the work of mounting the cushioning material on the 1.8-inch hard disk device, the work could be easily performed without sticking to the hand.

Comparative Example 1
In Example 1, a cushioning material was manufactured in the same manner as in Example 1 except that the embossing process was not performed. The adhesiveness of the cushioning material is 10.0 N for both the outer peripheral part and the inner peripheral part, and when the cushioning material is attached to a 1.8-inch hard disk device, the adhesiveness to the hand is improved. It was bad.

  The cushioning material of the present invention is excellent in workability such as attachment properties, is easy to manufacture, has high adhesion to electronic components, and has a gas barrier function. Moreover, according to the manufacturing method of this invention, the buffer material of this invention can be manufactured easily with high productivity.

It is a conceptual diagram which shows the protector which protects an electronic device. It is a figure which shows the aspect which covered the electronic device with the buffer material. It is a figure which shows the aspect which covered the electronic device with the buffer material. It is a conceptual diagram which shows a buffer material.

Explanation of symbols

1. 1. Buffer material 2. Outer peripheral part Inner peripheral part 4. Inner peripheral part 5. Outer peripheral part 10. Electronic device 11. Cover plate 12. Base plate 13. Gasket x, x1, x2, y, y1, y2, z, z1; the length of each part is shown.

Claims (6)

  A cushioning material that is attached to the outer surface of the electronic device so as to cover the electronic device and protects the electronic device, is formed of a thermoplastic elastomer composition, and the adhesiveness of the outer peripheral portion is in contact with the electronic device. A cushioning material characterized by being small in tackiness.   The shock-absorbing material according to claim 1, wherein the outer peripheral portion is embossed.   The cushioning material according to claim 2, which is obtained by injection molding.   The cushioning material according to claim 1, wherein a size of the cushioning material is smaller than a size of the electronic device. The thermoplastic elastomer composition is obtained by hydrogenating a block copolymer comprising (a) at least one polymer block mainly composed of a vinyl aromatic compound and at least one polymer block mainly composed of a conjugated diene compound. 100 parts by weight of a hydrogenated block copolymer having a number average molecular weight of 60000 or more, and (b) a non-aromatic having a kinematic viscosity at 40 ° C. of 100 mm ² / s or more. The cushioning material according to any one of claims 1 to 4, which is a thermoplastic elastomer composition comprising 1 to 3000 parts by mass of a softener for rubber based rubber and (c) 0 to 50 parts by mass of a polyolefin resin mainly composed of polypropylene. .   A method of manufacturing a buffer material for protecting an electronic device by injection molding, wherein a portion of the mold used for injection molding that is in contact with the outer peripheral portion of the buffer material is subjected to crimping.

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