JP2003323781A - Molding method of hot-melt type resin composition, method for sealing hard disk drive using the same and hot-melt type sealing agent composition for hard disk drive cover - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a molding method of hot-melt type resin composition which is excellent in dimensional accuracy. <P>SOLUTION: A mold (upper mold) 5 is formed with a prescribed shape of a sealing agent and set up on a lid for a housing of a hard disk device, a mold (lower mold) 6 is put to the back of the lid to sandwich the lid, and the lid is imposed with loads to fix and then clamped. The molds are kept at a prescribed temperature not higher than the softening point of the sealing agent, and then the hot-melt type sealing agent composition thus melted is poured into the molds from a filling port adjacent to a molding section by using the hot runner system 4 of a molding machine. After the pouring is finished, the hot-melt type sealing agent composition is cooled to a set temperature of the molds to be hardened. Then, the hardened sealing agent is separated from the mold (upper mold) 5. At that time, the separation is easily made by coating the mold with a florine resin, while the mold can be coated with a mold- releasing agent. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for molding a hot melt type resin composition and a method for sealing a hard disk drive using the same. The present invention also relates to a hot-melt type sealant composition having an improved composition as a hard disk drive sealant.

[0002]

2. Description of the Related Art Hot melt resin compositions have been used for various purposes, such as adhesives, pressure sensitive adhesives and sealing agents. In recent years, various electric and electronic devices have become smaller and higher in performance, and there is a demand for performance that allows them to be used in a harsh environment. Many of these electric and electronic devices are provided with a sealing agent for blocking the inside and the outside of the device.

Examples of the material of the sealing agent include rubber and plastics, but the demand for dimensional accuracy thereof is becoming more and more strict with the miniaturization and precision of the apparatus. A hard disk device is one of such electric and electronic devices. In the hard disk device, a hard disk having a magnetic material fixed in a disk shape formed of aluminum alloy or the like is housed in a closed container, and a magnetic head is attached to the hard disk via a gap of about 0.001 to 0.050 μm. This is a device for recording and reading information with the magnetic head. However, if dust is generated in the closed container or dust enters from the outside, the magnetic surface of the disk or the magnetic head may be destroyed. Therefore,
Regarding this, an air circulator having a high-performance filter is installed in the closed container to collect dust from inside and outside to keep the inside air clean.

In addition, in order to prevent the invasion of dust and the like from the outside, a sealing agent is provided to block the gap between the cover and the container forming the closed vessel, but the sealing agent itself does not Since it should not generate cohesive gas or liquid (called outgas), it is conventionally used as fluororubber, urethane rubber, neoprene rubber, silicone rubber, NBR rubber, or foamed rubber thereof, or foamed polyolefin. Rubber was used.

[0005]

Since the above-mentioned sealing agent is used as a punching sealing agent obtained by punching a molded sheet into a predetermined shape, a die and a punch for punching the molded sheet are required. In addition, there are drawbacks that cut loss occurs, the manufacturing cost becomes high, and a problem of disposal processing of the generated material occurs.

Further, the above-mentioned sealing agent is attached to the lid portion by using an adhesive, or an adhesive and a release paper are sequentially provided on one side in advance, and the release paper is peeled off and attached to the lid portion before use. Therefore, there is a drawback that the work is complicated and that it requires skill to accurately attach the sealing agent to the predetermined position of the lid portion, and the manufacturing cost becomes high. In addition, the adhesive and the adhesive have also been a cause of dust and the like. In addition, it has been known that the internal temperature rises up to around 90 ° C. due to the high performance of the hard disk device in recent years, so that the low molecular weight compound is volatilized from the sealing agent. Volatile components are usually called outgas, but sulfur,
Corrosive gas such as bromine and chlorine, siloxane gas, unreacted monomer such as acrylic monomer and styrene monomer,
There are low molecular weight hydrocarbons, organotin catalysts, etc., which may be adsorbed on the hard disk head to impede the floating stability of the head, or may adversely affect other materials.

In order to solve these drawbacks and problems, EP
A gasket for a hard disk drive unit has been proposed which uses an annular seal member obtained by vulcanizing and adhering DM rubber or the like on both sides of an annular core plate (see, for example, Patent Document 1). Further, a hot-melt type sealing agent containing a thermoplastic block copolymer elastomer, a tackifier and a softening agent is directly melt-coated with a coating robot using a coating robot, and is cooled to form a sealing agent (hereinafter, bead). Method) has been proposed (for example, refer to Patent Document 2). However, even in these methods, there is a limit in accurately controlling the sealing agent to a predetermined size. [Patent Document 1] JP-A-4-341986 (paragraph

[0009], FIGS. 1 to 4) [Patent Document 2] Japanese Patent Laid-Open No. 2001-57065 (paragraphs [0009 to 0011], FIG. 1)

The bead method uses a coating robot or the like,
The molten hot melt type sealing agent composition sent from the applicator is directly applied to the lid part of the hard disk storage container from the application nozzle attached to the tip of the robot arm, cooled and solidified, and the sealing agent formed into a predetermined shape is applied. Although it is a method of obtaining, due to the pulsation of the gear pump when sending the hot melt type sealing agent from the applicator, the amount of the sealing agent supplied cannot be controlled,
The size of the molding sealing agent varies, and it is difficult to control the temperature of the hot melt hot-melt type sealing agent at the coating nozzle part.Therefore, the molding sealing agent varies in size. At the same time, the internal pressure rises temporarily and a thick liquid pool (hammerhead phenomenon) occurs. At the end of coating, stringing and thinning phenomena that are characteristics of the hot-melt type sealing agent occur and the dimensional accuracy of the joint of the molding sealing agent decreases. Due to such causes, the dimensional accuracy of the molding sealing agent has been limited.

On the other hand, due to the high performance of the hard disk drive in recent years, frictional heat is generated due to the improvement of the number of rotations of the motor, and the heat dissipation failure of the hard disk drive due to the demand for space saving in the design of the personal computer causes the hard disk drive to fail. It is becoming a reality that it is used in increasingly hot environments. Therefore, hot-melt type sealing agents used in hard disk drives are required to withstand use at higher temperatures and retain elasticity, but in general, these hot-melt type sealing agents have a high melting temperature and Due to its high viscosity, it was difficult to obtain accurate dimensional accuracy by coating using the bead method. Therefore, when the hard disk drive storage container lid is fastened to the storage container main body with a screw or the like, if the tightening force is insufficient, there is a problem in that the sealing property becomes difficult. In order to improve this sealing difficulty, if the tightening force with screws etc. is increased, the lid part of the hard disk drive storage container is likely to deform, and due to excessive deformation of the sealing agent itself, sealing from the end part of the hard disk drive storage container The medicine sometimes spilled out. This protrusion also makes it difficult to insert the hard disk drive storage container into the hard disk drive storage section (drive bay) of the computer body.

Therefore, an object of the present invention is to provide a molding method with excellent dimensional accuracy in a method for molding a hot-melt type resin composition, and at the same time, it is necessary to attach a sealing agent at the time of assembly using the method. Another object of the present invention is to provide a method for sealing a hard disk drive, which can accurately control a sealing agent to a predetermined dimensional accuracy.
Further, the object of the present invention is to prevent the floating stability of the hard disk head from being outgassed or the like and to not adversely affect other materials. In addition, it is particularly excellent in heat resistance and has elasticity in a high temperature environment. It is particularly suitable for holding and molding a sealing agent by the above-mentioned novel sealing method,
An object is to provide an improved hot melt type sealant composition for hard disk drive covers.

[0011]

The present invention is a method for molding a hot melt resin composition on the surface of an adherend, which comprises (1) contacting the adherend with the surface of the adherend. A step of installing a die processed into a shape that forms a predetermined space when contacted. (2) Step of injecting the melted hot melt resin composition into the space formed between the surface of the die and the adherend (3) Cooling and solidifying the injected hot melt resin composition A step of adhering the solidified hot melt type resin solid on the surface of the adherend; and (4) releasing the solidified hot melt type resin composition from only the mold, The present invention relates to a molding method including a step of removing the bonded article from the surface.

Further, according to the present invention, the hot-melt type sealing agent composition is melt-molded on the cover surface of a hard disk drive, then solidified by cooling, and mounted on the main body of the hard disk drive to assemble the hard disk drive. (1) a step of installing a mold processed into a shape that forms a space on the cover surface of the hard disk drive when it comes into contact with the sealing agent enclosing groove for the hard disk drive (2) ) Injecting the melted hot melt type sealing agent composition into the space formed between the mold and the cover surface of the hard disk drive (3) Cooling and solidifying the injected hot melt type sealing agent composition On the cover surface of the hard disk drive, the solidified A step of adhering a sealing agent (4) a step of releasing the solidified hot-melt type sealing agent from only the mold and removing the mold from the cover surface of the hard disk drive, and (5) the main body of the hard disk drive In, including the step of mounting the cover surface of the hard disk drive,
This relates to a method of sealing a hard disk drive.

The present invention also provides (a) a styrene-based thermoplastic block copolymer obtained by mixing a styrene-isoprene block copolymer, a styrene-butadiene-styrene block copolymer, or a hydrogenated polymer thereof with an olefin resin to strengthen the hard segment. An olefinic thermoplastic block copolymer elastomer having a high molecular weight crystalline polyolefin in the molecule and a weight average molecular weight of 200,000 to 400, with a combined elastomer being 15 to 75% in the total composition, and (b) a hard segment. 00
1 of 0 styrenic thermoplastic block copolymer elastomer
The present invention relates to a hot-melt type sealant composition for hard disk drive covers, which contains 5 to 65% by weight of the total composition. Further, the present invention provides (a) a styrene-based thermoplastic block copolymer elastomer having a hard segment reinforced by mixing an olefin-based resin with a styrene-isoprene block copolymer, a styrene-butadiene-styrene block copolymer, or a hydrogenated polymer thereof. Two
0-50% (b) As a hard segment, an olefinic thermoplastic block copolymer elastomer having a high molecular weight crystalline polyolefin in the molecule and a weight average molecular weight of 200,
7 to 29% of one or more styrene-based thermoplastic block copolymer elastomers of 000 to 400,000 (c) Styrene content of 15% or more, coupling ratio of 50% or more, weight average molecular weight of 50, 000-1
1 to 17% of the hydrogenated polymer of the styrene-based thermoplastic block copolymer of 00000 (d) 1 of the olefin-based oligomer or its acid-modified product
9-30% (e) A hot-melt type sealant composition for a hard disk drive cover, containing 13 to 30% of a softening agent having a vapor pressure at 50 ° C. of 1.5 × 10 ⁻² Pa or less.

Further, according to the present invention, the adhesive strength to stainless steel is 1 N / 5 mm or more and the Shore A hardness is 25 to 7.
The present invention relates to a hot-melt type sealant composition for hard disk drive covers, which has a compression set of 70% or less at 60 ° C. and an outgas generation amount of 5 μg / g or less.

The inventors of the present invention have made various studies on a method of molding a hot-melt type resin capable of eliminating the disadvantages of the prior art and a method of manufacturing a cover / sealing agent assembly for a hard disk drive using the same, and as a result, the method described above is obtained. According to
It can be efficiently produced with a simple device, overcomes various drawbacks of the above-mentioned coating method by the bead method, and any size can be strictly defined, so it is suitable for any shape of adherend It has been found that, at the same time, it is possible to obtain a product that is inexpensive and rich in formability. In addition, the present inventors have conducted various studies on an improved hot-melt type sealant composition for a hard disk cover, which is particularly suitable for molding a sealing agent by the above-mentioned novel sealing method, and as a result, the above-mentioned composition or property was obtained. The hot-melt type sealant that it has does not interfere with the floating stability of the hard disk head or adversely affect other materials due to the generation of outgas, etc., and also has excellent heat resistance and elasticity in high temperature environments. Found to hold.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION The hot-melt resin composition used in the present invention is a resin composition which is melted by heating and solidified by cooling, and has self-adhesiveness. means. More specifically, it is used as an adhesive, a pressure-sensitive adhesive, a sealing agent and the like. In the present invention, what is used as a sealing agent is referred to as a hot melt type sealing agent composition.
The hot melt type resin composition used in the present invention can be used as a hot melt type sealant composition for a hard disk device.

Further, in the method of manufacturing a cover / sealing agent assembly for a hard disk device, the present inventors
A mold is installed on the surface of the lid of the storage container for the hard disk device, and the hot-melt type sealing agent in a molten state is poured into the mold to be solidified, and the sealing agent molded into a predetermined shape is molded into the mold. It was found that after the mold was released from the mold, the lid of the storage container for a hard disk device in which the hot-melt type sealing agent was molded into a predetermined shape was assembled into the storage container for the hard disk device to form an assembly. According to this, it is found that the sealing agent can be molded on the lid part of the storage container for the hard disk device in an arbitrary shape with high dimensional accuracy, and when this is assembled into the hard disk container body, the sealing property of the assembly becomes good. It is not necessary to mold only the molded product with a mold or punch from the sheet. This molded product, the adhesive of the punched product, the release agent treatment,
Since the process of bonding the cover to the molded product and punched product is also unnecessary, the cleanliness of the sealing agent itself is improved, the cover contamination due to the adhesive and the adhesive is eliminated, and the assembly can be washed. Found.

The material to be adhered used in the present invention is not particularly limited as long as it is a material that can withstand the mold clamping force of the mold, but is preferably made of metal. As the adherend, for example, a base of a motor portion of various electric and electronic products can be exemplified. By using the method of the present invention, it becomes possible to form a member having an arbitrary shape for locking a motor or the like on these substrates. As another object to be adhered, a base of a mobile phone or a cover thereof can be cited, and a sealing agent can be molded on the base of a mobile phone or its cover by using the molding method of the present invention. In addition, it is also possible to form a sealing agent having an electromagnetic wave shielding property on various electric / electronic parts (for example, on the base of a mobile phone or on the cover thereof) by kneading an electromagnetic wave shielding agent into a hot melt type sealing agent composition. it can.

Above all, in the hard disk device,
The container main body and the lid part to be used can be appropriately selected and used from known storage containers for hard disk devices. Examples of the material thereof include stainless steel, aluminum, and nickel-phosphorus plated steel plate, but the material is not limited to these.

The hot-melt type resin composition used in the present invention is not particularly limited, and for example, a hot-melt resin composition suitable for the required performance such as sealing property of a device to which a sealing agent is applied can be appropriately selected and used. You can The basic composition of the hot-melt type resin composition is usually a thermoplastic resin and / or a thermoplastic elastomer (base resin) as a main component, and a tackifier (tackifier) and a softening agent, Furthermore, an antioxidant, an oil retaining agent, and various fillers (colorants, electromagnetic wave shielding agents, etc.) may be appropriately added to the above composition.

The thermoplastic block copolymer elastomer used in the present invention is a viscoelastic thermoplastic elastomer having a soft segment and a hard segment in the same molecule (hereinafter referred to as Thermoplastic).
Elastomer, referred to as TPE) can be used.
As such TPE, styrene-based TPE, olefin-based TPE, vinyl chloride-based TPE, urethane-based TPE,
Examples include amide-based TPE and fluorine-based TPE.
Considering viscoelasticity, the amount of outgas, and versatility, styrene-based TPE or olefin-based TPE is preferable.

Among them, in the styrene type TPE, styrene isoprene block copolymer (SIS), styrene butadiene styrene block copolymer (SB
S), or their hydrogenated polymers (SEBS,
(SEPS etc.) are preferably used. More preferably, a styrene-based TPE in which an olefin resin such as polypropylene or polyethylene is mixed with the hydrogenated polymer to strengthen the hard segment (hereinafter referred to as a hard segment-reinforced styrene-based TPE) is preferably used.
In addition, as the other styrene-based TPE, TPE having a weight average molecular weight of 200,000 to 400,000 is preferably used.

As the olefin-based TPE, TPE having a high molecular weight crystalline polyolefin in the molecule as a hard segment is preferably used. Here, the high molecular weight means gel permeation chromatography (GP
Approximately 50.0 as measured by method C (polystyrene standard conversion)
It has a molecular weight of about 00 to 500,000.

The reason why the above-mentioned hard segment reinforced styrene type TPE or olefin type TPE having a high molecular weight crystalline polyolefin in the molecule is used is that the hard segment is reinforced, so that the molecular shift due to heat is less likely to occur. Further, it is because the hard segment is not swollen or embrittled by the influence of other components of the hot-melt type sealing agent, for example, a tackifier or a softening agent, and therefore the elasticity can be maintained even when exposed to a high temperature after molding. . As a result, even when the hard disk drive (HDD) generates heat, deformation of the sealant due to heat, adhesion with the HDD body, and protrusion to the outside do not easily occur, and even after being exposed to high temperature, the permanent compression occurs. Since the strain is small and the rubber elasticity can be semi-permanently retained, the sealing property is retained and the lid part of the storage container for the hard disk device can be reused. Further, when the above TPE is used, there is an advantage that the entire hot-melt type sealing agent composition has a low viscosity when melted and the sealing agent can be easily injected into the mold. The hot-melt type sealing agent composition containing TPE as a main component preferably has good mold releasability from the mold and good flowability upon injection into the mold. As an index of releasability, cohesive force, that is, tensile strength (JIS-K
Measured according to 6301) is 0.8 N / mm ²
Or more, more preferably 1.1 to 3.5 N / m
m ² . The melt flow rate (measured by JIS-K7210) can be used as an index of fluidity,
The value is 1 to 100 g / 10 min (190 ° C, 325
g) is preferable, and more preferably 5 to 50 g / 10 m.
in (190 ° C., 325 g).

The above-mentioned hard segment-reinforced styrene-based TPE and TPE having a polymer crystalline polyolefin as a hard segment in the molecule may be used alone, but may be used in combination with other TPE. Examples of TPE used in combination include styrene-based TPE, olefin-based TPE, vinyl chloride-based TPE, urethane-based TP
E, amide-based TPE, fluorine-based TPE and the like are mentioned, but styrene-based TPE or olefin-based TPE is preferable in consideration of viscoelasticity, outgas amount and versatility.

Among them, in the styrene type TPE, the styrene content is 15% or more, preferably 15 to 35% and the coupling rate is 50% or more, preferably 90 to 100.
% Styrene isoprene block copolymer (SIS)
Styrene butadiene styrene block copolymer (SB
S), or their hydrogenated polymers (SEBS,
(SEPS etc.) are preferably used. The weight average molecular weight of these styrene-based TPEs is 50000.
Those of 0 to 100,000 are preferable.

As the TPE used in the present invention, various types of Lavalon (manufactured by Mitsubishi Chemical Co., Ltd.), various types of Thermoran (manufactured by Mitsubishi Chemical Co., Ltd.), DYNARON-4600P, 6200P (J
Examples thereof include SR (manufactured by SR Company), Septon (manufactured by Kuraray Co., Ltd.), High Blur (manufactured by Kuraray Co., Ltd.), Clayton (manufactured by JSR Clayton Elastomer Co., Ltd.), and Tuftec H series (manufactured by Asahi Kasei Co., Ltd.).

T in the hot melt type sealant composition
The total amount of PE is preferably 20 to 80% (same as the weight% or less), and more preferably 30 to 70% of the total amount of the hot-melt type sealing agent. The amount of the hard segment reinforced styrenic TPE used in the present invention or the TPE having a high molecular weight crystalline polyolefin as a hard segment in the molecule is preferably 20 to 80% with respect to the total amount of the hot melt type sealing agent composition, and more preferably Is 2
It is 0 to 40%. The styrene-based TPE used in combination is preferably 10 to 50%, more preferably 10 to 30%.

The sealing agent used in the present invention contains a tackifier (tackifier) and a softening agent. Further, if necessary, calcium carbonate, a filler such as magnesium hydroxide or titanium white, a pigment, or the like can be added. Further, preferably, by using a compound in which a low molecular weight component is not present in those compositions, it becomes difficult for dust, cohesive gas or liquid (outgas) to be generated from the sealing agent itself.

The reason why the tackifier is used as the sealing agent is that when the sealing agent is molded on the lid of the hard disk device storage container, it has adhesiveness when the sealing agent melts and has self-adhesiveness after being left to cool and solidify. This is to have a function of eliminating surface tack. The tackifier is not limited to petroleum resin type and natural resin type, but it cuts low molecular weight compounds as much as possible, does not have a softening point or glass transition point within the temperature when the hard disk heats up, and does not have tack after cooling and solidification. It is desirable that they have no odor. More desirably, the grade in which cohesive gas molecules are removed by hydrogenation treatment or steam distillation is the best. When an olefin oligomer or an acid-modified product thereof is used in combination with such a resin or in place of such a resin, the adhesiveness is further improved and the occurrence of tack is further reduced. As an olefin oligomer,
Ethylene, propylene, butylene, pentene and C ₆
To C ₈ α-olefin-based oligomers, etc., whose melting point is 1
Those having a temperature of from 0 to 190 ° C., preferably from 120 to 170 ° C. can be used, but a propylene-based oligomer is most preferable in terms of heat resistance and compatibility with other components. As the acid-modified product, a maleic anhydride-modified product can be usually cited. Alternatively, for example, ozone oxidation is used as a means for acid modification. Also for these olefin-based oligomers or acid-modified products thereof, it is desirable to use a grade that has been subjected to a treatment for removing cohesive gas molecules before use, from the viewpoint of suppressing outgassing.

The amount of tackifier in the sealant composition is preferably 1 to 50% of the total amount, and more preferably 5 to 40%. When the tackifier is not used, the self-adhesive property is deteriorated and the workability is deteriorated, for example, the sealing agent comes off from the lid of the hard disk storage container. Further, when the amount of the tackifier is too large, the heat resistance decreases and the elasticity of the sealing agent also decreases, so that the airtightness tends to deteriorate.

The reason why the softening agent is used as the sealing agent is that when the sealing agent is molded on the lid of the hard disk device storage container, the melt viscosity of the sealing agent is lowered to improve the workability and the molding accuracy is good. This is because Similarly, as the softening agent, it is desirable that the amount of the low molecular weight compound is as small as possible and the vapor pressure is as low as possible. In particular, it is preferable that the vapor pressure at 50 ° C. such as oil for vacuum pump is 1.5 × 10 ⁻² Pa or less. .

The amount of the softening agent in the sealant composition is preferably 10 to 40% of the total amount, and particularly preferably 12 to 35%. If the amount of the softening agent is too small, the melting temperature of the sealing agent rises, the production efficiency at the time of molding the sealing agent on the lid of the hard disk device storage container decreases, and the dimensional accuracy tends to deteriorate. On the other hand, if the amount of the softening agent is too much, the heat resistance is lowered, and the sealing agent may be deformed or flow out when the hard disk heats up.

Other components include sealability, heat resistance,
Various additives known per se can be added as long as they do not adversely affect the moldability and outgas outflow.
For example, an anti-aging agent, an inorganic dispersant such as calcium carbonate, magnesium hydroxide, or carbon black for the purpose of improving cohesive strength, heat resistance, and light resistance, a pigment, and the like can be added as necessary. Next, the hot-melt type sealant composition for a hard disk drive cover having the improved composition will be described in detail.

The hot-melt type sealant composition for a hard disk drive cover of the present invention has the following (a) and (b):
It contains each component of. That is, (a) a styrene-based thermoplastic block copolymer elastomer (hard segment reinforced type) in which an olefin resin is mixed with a styrene isoprene block copolymer, a styrene butadiene styrene block copolymer, or a hydrogenated polymer thereof to strengthen a hard segment. Styrenic TPE) is contained in the total composition in an amount of 15 to 75%, preferably 20 to 50%. This component a has the effect of improving the elasticity of the hot-melt type sealant composition at high temperatures. If the amount is less than the above amount, the high temperature recovery power decreases, and if it is too large, the fluidity decreases. As a result, poor flow of molten metal occurs when the hot melt type sealing agent composition is poured into a mold, resulting in deterioration of moldability. In addition, the compatibility with other components decreases, which causes cracks and bleeding when the molded product is compressed.

(B) As a hard segment, an olefinic thermoplastic block copolymer elastomer having a high molecular weight crystalline polyolefin in the molecule, or a styrene-based T having a weight average molecular weight of 200,000 to 400,000.
PE is included in the total composition in an amount of 5 to 65%, preferably 7 to 29%. The component b has a structure of softening the hard segment at high temperature or having a structure in which the hard segment does not easily swell due to a component such as a softening agent, and thus has the action of lowering the hardness while maintaining the compression recovery force at a relatively low temperature. When the amount is less than the above amount, the compression recovery force is insufficient, and when the amount is too large, the cohesive force of the hot melt type sealing agent decreases, so that the mold releasability from the mold during molding decreases. Further, as in the case of the component a, when the amount is too much, the compatibility with other components is reduced, which causes cracks and bleeding during compression.

The preferred hot melt type sealant composition for hard disk drive covers of the present invention contains the following components (c), (d) and (e) in addition to the components (a) and (b). That is, the component (a) is added in an amount of 20 to 50
%, Preferably 30-38%. The component (b) is contained in an amount of 7 to 29%, preferably 10 to 16%. (C) The styrene content is 15% or more, the coupling rate is 50% or more, and the weight average molecular weight is 50,000 to 100,
1 to 17%, preferably 6 to 15%, of hydrogenated polymer of styrene-based thermoplastic block copolymer. The component c is blended for the purpose of maintaining the compatibility of the TPE components a and b. When the amount of the present c component is small, the compatibility of the softening agent of the following d component decreases, which causes the bleeding of the softening agent. On the other hand, if the amount is too large, the compression recovery force decreases, which is not preferable.

Next, (d) the olefinic oligomer or its acid-modified product is 19 to 30%, preferably 22 to 25%.
%contains. The component d has the effect of reducing tack at low temperatures while increasing self-adhesion, and also improves the cohesive force of the hot melt type sealing agent during molding and improves the releasability from the mold. Therefore, if the amount is too small, the releasability from the mold is lowered, and if the amount is too large, the hardness of the whole sealing agent is increased and the elasticity is also lowered, so that the airtightness is deteriorated. From the above viewpoint, the olefin oligomer is preferably a propylene oligomer, and its maleic anhydride-modified product is preferable. Further, as described above, in order to suppress the generation of outgas, it is desirable to perform an operation of removing the outgas component before blending.

(E) Vapor pressure at 50 ° C. is 1.5 × 1
0 ^-2 Pa the following softener 13 to 30%, preferably 1
Contains 7 to 22%. The component e has an action of lowering the hardness of the hot melt type sealing agent composition, and if it is too small, the hardness of the hot melt type sealing agent increases, and the flow of the hot melt type sealing agent composition at the time of molding is also increased. As a result, the flowability is deteriorated, which causes poor flow of molten metal during molding and inclusion of bubbles. If the blending amount is more than the above amount, the cohesive force is lowered, the releasability at the time of molding is lowered, and the component e is easily bleeded from the hot melt type sealing agent, which is not preferable.

The hot melt type sealant composition for hard disk drive covers of the present invention preferably has the following properties. That is, the adhesive force to the cover of the hard disk drive is 1 N / 5 mm or more, preferably 3 to 8 N / using the adhesive force to stainless steel as an index.
5 mm (measured according to JIS-K6854),
Hardness (Shore A hardness: JIS-K6253A, 20 ° C)
Is 25 to 75, preferably 35 to 65, the compression set at 60 ° C. (measured according to JIS-K6301) is 70% or less, preferably 60% or less, and the amount of outgas generated is 5 μg / g. Below, preferably 0-2μ
g / g (outgas detection: quantified organic matter by headspace gas chromatography analyzing vapor at 120 ° C.). If the adhesive strength is low, the sealing agent formed on the hard disk drive cover is undesirably peeled off by ultrasonic cleaning treatment or the like. If the hardness is too high, the cover may be deformed when the hard disk drive cover and the hard disk drive container body are assembled. If the hardness is too low, the shape becomes unstable after the sealing agent is molded on the cover of the hard disk drive. Compression set is the compression recovery force at high temperature,
That is, it is an index of heat resistance, and a low value is preferable. For example, 0% indicates that there is no distortion, and this value is 10
At 0%, the temperature inside the hard disk drive container is high (6
When exposed to 0 ° C), it represents a state in which it deforms and does not recover.
If the compression set exceeds 70%, the compression recovery force decreases and the heat resistance becomes extremely poor. Further, if the amount of outgas generated is higher than the above amount, these are adsorbed to the hard disk head to impede the floating stability of the head and adversely affect other materials. The hot-melt type sealant composition for a hard disk drive cover of the present invention is usually 120 ° C.
As described above, it preferably has a softening point of 140 ° C. or higher.

In the present invention, a hot-melt type resin can be obtained by using an apparatus (hereinafter referred to as a mold molding machine) to which a molding method (hereinafter referred to as a molding method), which is an improvement of a known resin molding method (outsert molding method), is applied. The composition can be molded onto the adherend. For example, in the case of a hard disk device, it can be molded on the lid part of the storage container for the hard disk device and can be bonded to the lid part at the same time.

FIG. 1 shows an outline of the molding machine. The molding machine has the following devices. That is,
A device for melting the hot melt type resin composition, a device for transporting the molten hot melt type resin composition to the main body of the molding machine, a mold processed into a predetermined shape, and a molten hot melt type resin composition is injected into the mold. A device for controlling the injection pressure and temperature during injection, a cylinder for hydraulically or pneumatically applying a mold clamping force to the mold, and a device for controlling the temperature of the mold.

As the mold used in the present invention, it is desirable to use a mold suitable for the hot runner system.
As a result, the amount of the hot-melt type resin composition used in one molding can be small as compared with the case of using a normal runner system, and it takes time and effort to remove the molding resin in the excess runner part. Eliminates need to improve productivity.

There is no particular limitation on the apparatus for supplying the hot melt type resin composition to the molding machine, but since the hot melt type resin composition can generally be pumped in a molten state, it is well known to apply hot melt coating composition. It is desirable to use an applicator that can be used with the machine. Preferably, the performance of the resin composition can be prevented from deteriorating due to thermal deterioration or the like by melting under nitrogen filling or by using a drum melter type feeder to melt only the amount used. Depending on the molten state of the hot melt type resin composition, a well-known injection molding machine for resin molding or extrusion molding machine can be used. Further, if there is a loss in the liquid-feeding pressure of the hot-melt type resin composition between the applicator and the hot runner system, a pressurizing device may be provided between them.

Hereinafter, the embodiment of the method of the present invention will be described by taking the molding of the hot-melt type sealing agent on the lid of the hard disk device storage container as an example, but the invention is not limited thereto. First, a mold (upper mold) 5 processed into a predetermined shape of a sealing agent is attached to a storage container lid 1 for a hard disk device.
3 and place the mold (lower mold) 6 from the back side of the lid,
The lid is sandwiched between both dies, a load is applied and fixed, and the dies are clamped. The mold is kept at a predetermined temperature equal to or lower than the softening point of the sealing agent, and then the hot runner system 4 of the mold molding machine is used to melt the hot melt type seal into the mold from the injection port 11 near the molding part. The agent composition is injected. After the injection is completed, the hot-melt type sealing agent composition is cooled to the set temperature of the mold and solidified. afterwards,
The solidified sealing agent is released from the mold (upper mold). At this time, a mold releasing agent may be applied to the mold, but if the mold is coated with a fluororesin, the mold can be easily separated. As the release agent, one that does not generate outgas can be appropriately selected, but silicone and a halogen-free fluorine-based release agent are preferable. Examples of such a release agent include a fluorine-based release agent manufactured by Kozai Co., Ltd. Examples of the fluororesin used for the fluororesin coat include tetrafluoroethylene resin (PTFE), tetrafluoroethylene perfluoroalkyl vinyl ether copolymer resin (PFA) and tetrafluoroethylene-hexafluoropropylene copolymer resin (PFEP). And so on.

Thus, the sealing agent having a predetermined shape is molded on the lid of the storage container for the hard disk device in a state of being adhered thereto, which is referred to as a "cover sealing agent assembly". In such a method, the dimensional accuracy of the molded sealing agent can be defined very accurately. Also, there is no occurrence of burrs or protrusions during molding. In addition, if necessary, clean treatment such as water washing, air washing, and drying can be performed.

The cover sealing agent assembly thus obtained is integrated with a hard disk device accommodating container by fastening it with screws or the like to manufacture a hard disk device. At this time, the composition constituting the sealing agent is Since it has an appropriate hardness, the stress applied to the cover is effectively reduced. Further, the sealing agent of the present invention has extremely low gas permeability and moisture permeability, and has good sealing property.

[0048]

The present invention will be described in detail below with reference to examples and comparative examples, but the invention is not limited thereto. In addition, simply indicates parts by weight.

Example 1 A hard-arm reinforced styrene-based TPE (manufactured by Mitsubishi Chemical Corporation: Lavalon MJ-4) was used as a thermoplastic block copolymer (TPE) in a dual-arm kneader capable of heating up to 200 ° C.
300) 300 parts, and TPE having a high molecular weight crystalline polyolefin in the hard segment (manufactured by JSR; DYN
100 parts of ARON6200P) and 100 parts of styrene-based TPE (Septon 2002 manufactured by Kuraray Co., Ltd.) having a weight average molecular weight of about 60,000 and maleic anhydride modified polypropylene oligomer (Sanyo Chemical Co., Ltd.) from which low molecular weight substances have been removed under vacuum at 190 ° C. Industrial: Yumex 110T
S) (200 parts) was added, and the mixture was heated and kneaded at 180 ° C. for 2 hours in a nitrogen atmosphere. With the contents being uniform, 150 parts of a specially refined mineral oil (MR-200 manufactured by Matsumura Oil Research Institute) used as a vacuum pump oil was added as a softening agent. After further heating and stirring under a reduced pressure of 8 mmHg for 1 hour, the contents were taken out from the kneader to prepare a sealing agent.

Example 2 Similar to Example 1, thermoplastic block copolymer (TPE)
As hard segment reinforced styrene-based TPE (Mitsubishi Chemical Corporation: Lavalon MJ-4300) 330 parts, and styrene-based TPE having a weight average molecular weight of about 260,000
100 parts of (Kuraray Septon 2005) and a styrene-based TPE having a weight average molecular weight of about 60,000.
(Kuraray: Septon 2002) 150 parts and 19 parts
250 parts of maleic anhydride-modified polypropylene oligomer (manufactured by Sanyo Kasei: Umex 110TS) from which low molecular weight substances were removed under vacuum at 0 ° C. was added, and the mixture was heated and kneaded at 180 ° C. for 2 hours under a nitrogen atmosphere. Specially refined mineral oil used as a vacuum pump oil as a softening agent (MR-Matsumura Petroleum Institute Co., Ltd .: MR-
290 parts of 200) were added. 1 hour, 8 mmHg
After heating and stirring under reduced pressure, the contents were taken out from the kneader to prepare a sealing agent.

Example 3 Similar to Example 1, thermoplastic block copolymer (TPE)
As hard segment-reinforced styrene-based TPE (Mitsubishi Chemical Corporation: Lavalon MJ-4300) 250 parts, and TPE having a high molecular weight crystalline polyolefin in the hard segment (JSR; DYNARON 4200P) 15
0 parts, and a styrene-based TPE having a weight average molecular weight of about 100,000 (Kuraray Co., Ltd .: Hybler 7125) 10
0 part, and 200 parts of a polypropylene-based oligomer (manufactured by Sanyo Kasei: Hymer 330P) from which low molecular weight substances have been removed under vacuum at 190 ° C. are charged, and a nitrogen atmosphere is used for 18
The mixture was heated and kneaded at 0 ° C. for 2 hours. With the contents being uniform, 130 parts of a special refined mineral oil (MR-100 manufactured by Matsumura Oil Research Institute) used as a vacuum pump oil was added as a softening agent. After further heating and stirring under a reduced pressure of 8 mmHg for 1 hour, the contents were taken out from the kneader to prepare a sealing agent.

Example 4 Similar to Example 1, thermoplastic block copolymer (TPE)
As hard segment reinforced styrene type TPE (Mitsubishi Chemical Corporation: Lavalon MJ-4300) 250 parts, and TPE having a high molecular weight crystalline polyolefin in the hard segment (JSR; DYNARON 6200P) 12
0 parts, and a styrene-based TPE having a weight average molecular weight of about 60,000 (Kuraray: Septon 2002) 100
Part, and maleic anhydride-modified polypropylene oligomer (manufactured by Sanyo Kasei: Umex 110TS) from which low molecular weight substances have been removed under vacuum at 190 ° C., 150 parts, 190
Polypropylene oligomer from which low molecular weight substances have been removed under vacuum at ℃ (Sanyo Chemical Co., Ltd .: Hymer 330P) 50
Part, and heated at 180 ° C. for 2 hours in a nitrogen atmosphere,
Kneaded With the contents being uniform, 100 parts of a specially refined mineral oil (MR-200, manufactured by Matsumura Oil Research Institute) used as a vacuum pump oil was added as a softening agent.
After further heating and stirring under a reduced pressure of 8 mmHg for 1 hour, the contents were taken out from the kneader to prepare a sealing agent.

Comparative Example 1 Similar to Example 1, a thermoplastic block copolymer (TPE)
As hard segment reinforced styrene-based TPE (Mitsubishi Chemical Corporation: Lavalon MJ-4300), and TPE having a high molecular weight crystalline polyolefin in the hard segment (JSR; DYNARON 6200P) 11
0 parts, and 120 parts of maleic anhydride-modified polypropylene oligomer (Sanyo Kasei: Umex 110TS) from which low molecular weight substances have been removed under vacuum at 190 ° C. are added, and the mixture is heated and kneaded at 180 ° C. for 2 hours under a nitrogen atmosphere. did. With the contents being uniform, 100 parts of a specially refined mineral oil (MR-200, manufactured by Matsumura Oil Research Institute) used as a vacuum pump oil was added as a softening agent. After further heating and stirring under a reduced pressure of 8 mmHg for 1 hour, the contents were taken out from the kneader to prepare a sealing agent.

Comparative Example 2 As in Example 1, a thermoplastic block copolymer (TPE)
As hard segment reinforced styrene-based TPE (Mitsubishi Chemical Corporation: Lavalon MJ-4300) 140 parts, and styrene-based TPE having a weight average molecular weight of about 60,000
(Kuraray: Septon 2002) 100 parts, and 1
120 parts of a maleic anhydride-modified polypropylene oligomer (manufactured by Sanyo Kasei: Umex 110TS) from which low molecular weight substances were removed under vacuum at 90 ° C. was added, and the mixture was heated and kneaded at 180 ° C. for 2 hours in a nitrogen atmosphere. Specially refined mineral oil used as vacuum pump oil as a softening agent in the state where the contents are uniform (Matsumura Oil Research Institute: MR-2
00) was put in 100 parts. After further heating and stirring under a reduced pressure of 8 mmHg for 1 hour, the contents were taken out from the kneader to prepare a sealing agent.

Comparative Example 3 As in Example 1, hydrogenated C ₉ was added as a tackifier to the kneader.
100 parts of a distillate polymer (ECR-228F manufactured by Tonex Co., Ltd.), 150 parts of a hard segment-reinforced styrene-based TPE (manufactured by Mitsubishi Chemical Corporation: Lavalon MJ-4300) as a thermoplastic block copolymer (TPE), and weight 110 parts of styrene-based TPE (Kuraray: Septon 2002) having an average molecular weight of about 60,000, and 190 ° C.
10 parts of maleic anhydride-modified polypropylene oligomer (manufactured by Sanyo Kasei Kogyo Co., Ltd .: Umex 110TS) from which low molecular weight substances were removed under vacuum was added, and 180 parts under a nitrogen environment were added.
The mixture was heated and kneaded at 2 ° C. for 2 hours. With the content being uniform, 120 parts of a special refined mineral oil (MR-200 manufactured by Matsumura Oil Research Institute) was added as a softening agent. Another hour,
After heating and stirring under a reduced pressure of 8 mmHg, the contents were taken out from the kneader to prepare a sealing agent.

Comparative Example 4 Similar to Example 1, thermoplastic block copolymer (TPE)
As hard segment reinforced styrene-based TPE (Mitsubishi Chemical Corporation: Lavalon MJ-4300) 200 parts, and styrene-based TPE having a weight average molecular weight of 260,000 (Kuraray; Septon 4055), and a weight average molecular weight of about 100. 1,000 parts of styrene-based TPE (Kuraray Co., Ltd .: Hybler 7125), and 190 ° C.
150 parts of polypropylene-based oligomers (manufactured by Sanyo Kasei: Hymer 330P) from which low-molecular weight substances were removed under vacuum were charged, and heated and kneaded at 180 ° C. for 2 hours in a nitrogen atmosphere. With the contents even, as a softener,
150 parts of specially refined mineral oil (MR-200 manufactured by Matsumura Oil Research Institute) used as a vacuum pump oil was added. After further heating and stirring under reduced pressure of 8 mmHg for 1 hour,
The contents were taken out from the kneader to prepare a sealing agent.

Comparative Example 5 As in Example 1, hydrogenated C ₉ as a tackifier was added to the kneader.
100 parts of distillate polymer (manufactured by Tonex Co .: ECR-228F), 100 parts of hard segment reinforced styrene-based TPE (manufactured by Mitsubishi Chemical: Lavalon MJ-4300) as a thermoplastic block copolymer (TPE), and weight 100 parts of styrene-based TPE having an average molecular weight of about 60,000 (Kuraray: Septon 2002), and 190 ° C.
50 parts of a maleic anhydride-modified polypropylene oligomer (manufactured by Sanyo Kasei Kogyo Co., Ltd .: Umex 110TS) from which low molecular weight substances have been removed under vacuum is charged, and the mixture is allowed to stand at 18 under a nitrogen atmosphere.
The mixture was heated and kneaded at 0 ° C. for 2 hours. With the contents being uniform, 150 parts of a specially refined mineral oil (MR-200 manufactured by Matsumura Oil Research Institute) used as a vacuum pump oil was added as a softening agent. After further heating and stirring under a reduced pressure of 8 mmHg for 1 hour, the contents were taken out from the kneader to prepare a sealing agent.

Comparative Example 6 As in Example 1, hydrogenated C ₉ as a tackifier was added to the kneader.
100 parts of a distillate polymer (ECR-228F manufactured by Tonex Co.) and a styrene-based TPE having a weight average molecular weight of about 70,000 (Tuftec H1052 manufactured by Asahi Kasei).
240 parts, and maleic anhydride-modified polypropylene oligomer (manufactured by Sanyo Chemical Industries: Umex 110TS) 130 from which low molecular weight substances have been removed under vacuum at 190 ° C. 130
Part, and heated at 180 ° C. for 2 hours in a nitrogen atmosphere,
Kneaded With the contents being uniform, 200 parts of a specially refined mineral oil (MR-200 manufactured by Matsumura Oil Research Institute) used as a vacuum pump oil was added as a softening agent.
After further heating and stirring under a reduced pressure of 8 mmHg for 1 hour, the contents were taken out from the kneader to prepare a sealing agent.

Comparative Example 7 Hydrogenated C ₉ as a tackifier was added to the kneader as in Example 1.
TPE having 100 parts of a distillate polymer (ECR-228F manufactured by Tonex Co., Ltd.) and a hard segment of a high molecular weight crystalline polyolefin (DYNARON manufactured by JSR)
6200P) 140 parts, and a weight average molecular weight of about 7
140 parts of styrene-based TPE (made by Asahi Kasei: Tuftec H1052) of 0000, and maleic anhydride-modified polypropylene oligomer (manufactured by Sanyo Chemical Industries: Umex 110) from which low molecular weight substances have been removed under vacuum at 190 ° C.
TS) 140 parts, and at 180 ° C. under nitrogen atmosphere for 2
It was heated and kneaded for a time. With the contents even,
As a softening agent, 170 parts of a specially refined mineral oil (MR-200 manufactured by Matsumura Oil Research Institute) used as a vacuum pump oil was added. After further heating and stirring under a reduced pressure of 8 mmHg for 1 hour, the contents were taken out from the kneader to prepare a sealing agent.

Example 5 An upper mold in which a hot runner system (manufactured by Century Co., Ltd .: valve gate system) was incorporated into a mold (manufactured by Tokui Mold Mfg. Co., Ltd.) processed into a groove shape containing a coating sealing agent by a molding method. , Resin molding machine (made by Yamashiro Seiki) that controls temperature control and opening / closing of mold
Installed in. The hot-melt type sealing agent was supplied from a hot-melt applicator (MX-3006 manufactured by Nordson Co., Ltd.) via a liquid resin injection machine (Yamashiro Seiki Seisakusho) and a hot runner. Place the lid of the hard disk storage container on the lower mold so that a space is formed by the upper mold and the lid of the hard disk drive storage container. The melt sealing agent was injected to mold the sealing agent. Molding conditions are: mold temperature 80 ° C, hot melt melting temperature and hot runner temperature 180 ° C, mold clamping force 15t / piece, injection pressure 110kg / cm ² , injection time 5
Seconds, and the total of the pressure holding time and the cooling time was 10 seconds. The mold has an arc-shaped groove with a height of 1.5 mm and a width of 1.5 mm, and is coated with a fluororesin to assist the mold-sealant release. After curing by cooling, release the sealing agent from the mold, height 1.5mm, width 1.5mm
As a result, a lid portion of a hard disk drive storage container was obtained in which a sealing agent having an arcuate section was adhered onto the hard disk drive lid portion.

Comparative Example 8 A coating soldering robot by a bead method (scalar arm robot: MOTOMAN manufactured by Yasukawa Electric Co., Ltd.), a hot melt applicator (HM3500V by Nordson Co., Ltd.),
Using a coating system equipped with a coating head (H-200, Nordson Co., Ltd.), the hot-melt type sealing agent was coated on the lid part of the hard disk storage container according to a pre-stored pattern. The coating conditions are 1.0mm inside diameter of dispenser nozzle, 18 inside temperature of applicator.
0 ° C, coating temperature 190 ° C, coating speed 50 mm / sec,
After completion of the coating, it was left to cool for about 2 seconds to be cured. After curing, a sealing agent having an arcuate cross section with a height of 1.5 mm and a width of 1.5 mm was formed.

Evaluation method 1: Moldability and sealing property according to the molding method of the present invention The sealing agents obtained in Examples 1 to 4 and Comparative Examples 1 and 4 were placed on the lid member according to Example 5 and Comparative Example 8. After molding, the following evaluation items were evaluated. Regarding the evaluation of the sealing property, the assembly of the lid member molded with the sealing agent and the hard disk storage container body according to Example 5 and Comparative Example 8 was evaluated. Sealing property: A humidity sensor (Sato Keiki Seisakusho SK-L200TH) is embedded in a hard disk storage container, and the change in internal relative humidity is measured under the environment of a temperature of 60 ° C. and a relative humidity (RH) of 90%, and the sealing property is obtained. , And the moisture permeability of the sealing agent were evaluated. Molding accuracy: The dimensional accuracy of the molded sealing agent was evaluated by a laser type step difference meter (LK-030 manufactured by Keyence Corporation). The results corresponding to each measurement item are shown in Table 1.

[0063]

[Table 1]

The evaluation criteria are shown below. Sealability: ◎ No change in relative humidity inside the hard disk storage container, ○ Relative humidity change less than 10%, △ Relative humidity pressure change 10% or more Molding accuracy: ◎ Dimensional accuracy including sealing agent injection port and coating joint is 5 / 100 or less. ○ The dimensional accuracy has a variation of 5/100 or more, but the sealing performance is comparable. △ A dimensional error is sufficiently observed even visually, and there is a variation such that a sufficient sealing property cannot be exhibited.

From the findings of Example 5 and Comparative Example 8, the mold forming method of the present invention is remarkably improved in the dimensional accuracy of the molding sealant as compared with the conventional coating method by the bead method, and This shows that the sealability of the hard disk drive assembly has been remarkably improved.

Evaluation method 2: Properties of sealing agent of the present invention The sealing agents of Examples 1 to 4 and Comparative Examples 1 to 7 were evaluated for the following evaluation items. Adhesion: Stainless steel of each sealant (SUS30
The adhesive force to 4) was measured according to JIS-K6854. Hardness: JI is the Shore A hardness of each sealing agent at 20 ° C.
It measured based on S-K6253A. Compression set: The compression set of each sealant at 60 ° C. was measured according to JIS-K6301. Amount of generated outgas: The amount of generated organic matter was quantified by headspace gas chromatography which analyzes vapor at 120 ° C. Releasability: The tensile strength of each sealant is JIS-K630.
It was measured by the method according to 1. Flowability: The melt flow rate of each sealant is JIS-K
It measured according to 7210 (condition; 190 degreeC, 325g).

Tables 2 to 3 show Examples 1 to 4 and Comparative Examples 1 to 7.
The composition and measurement results of are shown below. The details of each component in Tables 2 and 3 are shown below. a: Hard segment reinforced SEBS (styrene-ethylene / butylene-styrene block copolymer); Lavalon MJ4300 b1: CEBC (crystal olefin-ethylene / butylene-crystal olefin block copolymer) having high molecular weight crystalline polyethylene as a hard segment. ); Dynaron 6200P b2: SEPS having an average molecular weight of 260,000 (styrene-ethylene / propylene-styrene block copolymer); Septon 2005 b3: SEBC (styrene-ethylene / butylene-crystal) having a high molecular weight crystalline polyethylene as a hard segment. Olefin block copolymer); Dynaron 42
00P b4: SEBPS (styrene-ethylene-butylene-propylene-styrene block copolymer) having an average molecular weight of 260,000; Septon 4055 c1: average molecular weight of about 60,000 and styrene content 3
SEPS with 0% and 100% coupling rate; Septon 2
002 c2: Hydrogenated SVIS (styrene-vinylisoprene-styrene block copolymer) having an average molecular weight of about 100,000, a styrene content of 20%, and a coupling rate of 100%; Hybler 7125 c3: an average molecular weight of about 70,000. Styrene content is 2
SEBS with 0% and 100% coupling ratio; Tuftec H1052 d1: Maleic anhydride modified polypropylene oligomer;
Umex 110TS d2: polypropylene oligomer; Hymer 330P e1: softening agent (vapor pressure at 50 ° C. is 1.3 × 10 ⁻³ Pa)
MR-200 e2: Softener (vapor pressure at 50 ° C. is 1.3 × 10 ⁻² Pa).
MR-100 x: tackifier (hydrogenated C ₉ distillate polymer); ECR228
F

[0068]

[Table 2]

[0069]

[Table 3]

From the knowledge of Examples and Comparative Examples, Comparative Examples 2, 3, 5 and 6 not containing the component b have high compression set and high heat resistance, and Comparative Examples 6, 7 not containing the component a. It can be seen that the compression set is high and the amount of outgas is also high. It can be seen that also in Comparative Example 1 containing no c component, the compression set is high and the heat resistance is difficult. In Comparative Example 4 in which the amount of the b component is small, there is a drawback that the hardness is high. It can be seen that the improved hot-melt sealant composition for a hard disk drive cover of the present invention has a high adhesive force to the cover, an appropriate hardness, an extremely small amount of outgas, and excellent heat resistance. Further, it can be seen from the mold releasability and fluidity that the sealant composition is suitable for the molding method of the present invention. It also has sufficient tensile strength, and can be said to be superior in mold releasability from the mold. Furthermore, since the melt flow rate is in an appropriate range, the fluidity at the time of injection into the mold is appropriate, short-cut (molding failure due to insufficient molten metal flow) is unlikely to occur in the molding sealing agent, and burr is less likely to occur during molding. It has an excellent effect.

[0071]

According to the molding method of the present invention, a hot-melt type resin composition can be molded in an arbitrary shape on an object to be bonded with high dimensional accuracy. For example, when applied to a precision device such as an electric or electronic device, the dimensional accuracy of the sealant can be regulated extremely strictly. Particularly, the assembly in which the lid portion of the hard disk storage container and the sealing agent are integrated has a good sealing property when the dimensional accuracy of the molding sealing agent is strictly controlled and the main body of the hard disk storage container and the lid portion are assembled. According to the method of the present invention, it is possible to seal the hard disk drive by accurately controlling the sealing agent to a predetermined dimensional accuracy without attaching the sealing agent during assembly. Further, according to the present invention, a hot melt type sealing for a hard disk drive cover improved in that it has a high adhesive force to a hard disk storage container cover, an appropriate hardness, an extremely small amount of outgas, and an excellent heat resistance. An agent composition can be provided. Also, a sealing agent composition suitable for the molding method of the present invention is provided from the viewpoint of mold releasability and fluidity.

[Brief description of drawings]

FIG. 1 is a schematic view of a molding machine used in the method of the present invention.

FIG. 2 is a top view of an upper mold used in the present invention.

FIG. 3 is a top view of a sealing agent-integrated storage container lid.

4 is a cross-sectional view taken along the line AA of FIG.

[Explanation of symbols]

1 Mold clamping press 2 hydraulic cylinder 3 hydraulic pump system 4 hot runner system 5 Mold (upper mold) 6 mold (lower mold) 7 Heat-retaining hose for liquid delivery pipe 8 melting tank 9 gear pump 10 Applicator control section 11 Inlet 12 Molding groove 13 Hard disk storage container lid 14 Sealant

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Kenta Adachi             5-5-3 Minamijimaminami-cho, Chuo-ku, Kobe-shi, Hyogo Prefecture             No. Matsumura Oil Research Institute Co., Ltd. (72) Inventor Tamao Akada             5-5-3 Minamijimaminami-cho, Chuo-ku, Kobe-shi, Hyogo Prefecture             No. Matsumura Oil Research Institute Co., Ltd. F-term (reference) 4H017 AA03 AA31 AB17 AC11 AC17                       AD03 AE05

Claims (9)

[Claims] 1. A method for molding a hot-melt type resin composition on the surface of an adherend, which comprises: (1) forming a predetermined space on the surface of the adherend when contacting the adherend. Step (2) of installing a die processed into a shape to be formed Step (3) of injecting a molten hot melt type resin composition into the space formed between the die and the surface of the adherend (3) A step of cooling and solidifying the hot melt type resin composition and adhering the solidified hot melt type resin solid material to the surface of the adherend; and (4) the solidified hot melt type resin composition from only the mold. A molding method including a step of releasing the mold and removing the mold from the surface of the adherend. 2. A method for sealing a hard disk drive, which comprises assembling a hard disk drive by melt-molding a hot-melt type sealant composition on a cover surface of the hard disk drive, then solidifying by cooling, and mounting the hard disk drive in a main body of the hard disk drive. (1) a step of installing a die processed into a shape that forms a space on the cover surface of the hard disk drive when it comes into contact with the sealing agent enclosing groove for the hard disk drive (2) the die And (3) injecting the melted hot-melt type sealing agent composition into the space formed on the cover surface of the hard disk drive, (3) cooling and solidifying the injected hot-melt type sealing agent composition and covering the hard disk drive Contact the solidified sealing agent on the surface And (4) a step of releasing the solidified hot-melt type sealing agent from only the mold and removing the mold from the cover surface of the hard disk drive, and (5) the hard disk drive body with the hard disk. Including the step of mounting the cover surface of the drive,
Hard disk drive sealing method. 3. A hot melt type sealant composition comprising one of a styrene type thermoplastic block copolymer elastomer and an olefin type thermoplastic block copolymer elastomer.
The method for sealing a hard disk drive according to claim 2, wherein the sealing method includes one or more kinds. 4. A styrene-based thermoplastic block copolymer obtained by mixing a styrene-isoprene block copolymer, a styrene-butadiene-styrene block copolymer, or a hydrogenated polymer thereof with an olefin-based resin to obtain a hard segment, which is a hot-melt type sealant composition. The method for sealing a hard disk drive according to claim 3, which comprises a polymer elastomer. 5. The method for sealing a hard disk drive according to claim 3, wherein the hot-melt type sealant composition contains, as a hard segment, an olefinic thermoplastic block copolymer elastomer having a high molecular weight crystalline polyolefin in the molecule. . 6. The hot melt type sealant composition has a tensile strength of 0.8 N / mm ² or more and a tensile strength of 1 to 100.
The method of sealing a hard disk drive according to claim 3, wherein the method has a melt flow rate of g / 10 min (190 ° C., 325 g). 7. A (a) styrene-isoprene block copolymer, styrene-butadiene-styrene block copolymer, or a hydrogenated polymer thereof is mixed with an olefin resin to obtain a styrene-based thermoplastic block copolymer elastomer in which hard segments are reinforced. 15-75% in the composition, and (b) an olefinic thermoplastic block copolymer elastomer having a high molecular weight crystalline polyolefin in the molecule as a hard segment and a weight average molecular weight of 200,
A hot-melt type sealant composition for hard disk drive covers, which contains 5 to 65% of one or more 000 to 400,000 styrene-based thermoplastic block copolymer elastomers in the total composition. 8. A styrene-based thermoplastic block copolymer elastomer in which (a) a styrene-isoprene block copolymer, a styrene-butadiene-styrene block copolymer, or a hydrogenated polymer thereof is mixed with an olefin resin to strengthen a hard segment. ~ 50
% (B) An olefinic thermoplastic block copolymer elastomer having a high molecular weight crystalline polyolefin in the molecule as a hard segment and a weight average molecular weight of 200,
7 to 29% of one or more styrene-based thermoplastic block copolymer elastomers of 000 to 400,000 (c) Styrene content of 15% or more, coupling ratio of 50% or more, weight average molecular weight of 50, 000-1
1 to 17% of the hydrogenated polymer of the styrene-based thermoplastic block copolymer of 00000 (d) 1 of the olefin-based oligomer or its acid-modified product
9-30% (e) A hot-melt type sealant composition for a hard disk drive cover, containing 13 to 30% of a softening agent having a vapor pressure at 50 ° C. of 1.5 × 10 ⁻² Pa or less. 9. The adhesive strength to stainless steel is 1 N /
The hard disk drive cover hot according to claim 7 or 8, having a property of 5 mm or more, a Shore A hardness of 25 to 75, a compression set of 70% or less at 60 ° C, and an outgas generation amount of 5 µg / g or less. Melt type sealing agent composition.