KR101269178B1 - A manufacturng method of adhesive foam typed heat-radiation sheet and a adhesive foam typed heat-radiation sheet formed therefrom - Google Patents

Abstract

The present invention relates to a method for producing a pressure-sensitive adhesive heat-resistant foam sheet that is adhered to various electronic products to release heat, and a pressure-sensitive adhesive heat-resistant foam sheet formed therefrom. Method for producing a pressure-sensitive adhesive heat-resistant foam sheet according to the present invention comprises the steps of preparing a coating liquid containing a (S1) curable monomer; (S2) adding and dispersing Mg (OH) ₂ to the coating solution; And (S3) applying the resultant of the step (S2) to the substrate and then applying heat to hydrolyze the Mg (OH) ₂ and to cure the curable monomer. The heat dissipation foam sheet formed by hydrolyzing Mg (OH) ₂ according to the present invention is manufactured simply and economically, and the adhesive area and the bonding force of the electronic products are improved, thereby enabling effective heat conduction and heat dissipation. In addition, MgO produced as a hydrolyzate of Mg (OH) ₂ is present inside the bubbles to impart fire resistance to the sheet.

Description

Manufacturing method of adhesive heat-resistant foam sheet, and adhesive heat-resistant foam sheet formed therefrom TECHNICAL FIELD

The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate the presently preferred embodiments of the invention and, together with the description of the following preferred embodiments, serve to explain the principles of the invention.

1 is a schematic cross-sectional view of an adhesive heat-resistant foam sheet formed on a substrate according to a preferred manufacturing method of the present invention.

The present invention relates to a method for producing a pressure-sensitive adhesive heat-resistant foam sheet that is adhered to various electronic products to release heat, and a pressure-sensitive adhesive heat-resistant foam sheet formed therefrom.

In general, electronic products such as computers, portable personal terminals, and communication devices do not diffuse excessive heat energy generated inside the system to the outside, and have serious instability in system stability such as afterimage problems. In addition, failure to release heat energy outside of the product may shorten the life of the product, cause product failure or malfunction, and in some cases, may cause an explosion or fire. In particular, plasma display panel (PDP), LCD monitor, and the like, which are recently in increasing demand, are deteriorated in vividness and color due to generated heat, thereby affecting reliability and stability of products. Therefore, the heat energy generated inside the system of electronic products must be released to the outside or cooled by self cooling.

As a conventional method of dissipating heat of electronic products, a method of installing a heat sink or a heat radiating fan has been used. However, heat sinks have very low efficiency because they generate less heat than heat from electronics. Accordingly, a method of forcibly dissipating heat from the heat sink by installing a heat sink together with the heat sink is also used. However, the heat dissipation fan has a problem that noise and vibration are generated during use, and above all, it cannot be applied to products requiring weight reduction and slimming, such as plasma display panels (PDPs), notebook computers, portable personal terminals, and the like. .

In addition, as a method that can be used in products requiring light weight and slimness, a method of mixing a thermally conductive filler with an acrylic resin or a silicone resin and coating the same on a heating element of an electronic product has been proposed. However, such a heat dissipation coating layer is cumbersome to be applied by applying directly to the electronics.

On the other hand, Korean Patent Laid-Open No. 10-2001-0078953 discloses a heat dissipation sheet that is applied by surface contact to the heating element of the electronic product. However, when the heat dissipation sheet is laminated on the electronic product, the coupling with the heating element is not strong, and above all, there is a problem in that the contact area is small so that the heat conduction and heat dissipation functions cannot be effectively performed.

SUMMARY OF THE INVENTION The first object of the present invention is to solve the above-mentioned problems, and to improve the adhesive area and bonding force on electronic products, and to easily and economically prepare a adhesive heat-resistant foam sheet capable of effective heat conduction and heat dissipation, and adhesive heat radiation formed therefrom. To provide a foam sheet.

A second object of the present invention is to provide, in addition to the above-described first object, a method for producing a pressure-sensitive adhesive heat-resistant foam sheet provided with fire resistance of a sheet at the same time, and a pressure-sensitive adhesive heat-resistant foam sheet formed therefrom.

In order to achieve the above technical problem, the method for producing a pressure-sensitive adhesive heat-resistant foam sheet according to the present invention comprises the steps of preparing a coating liquid containing a curable monomer (S1); (S2) adding and dispersing Mg (OH) ₂ to the coating solution; And (S3) applying the resultant of the step (S2) to the substrate and then applying heat to hydrolyze the Mg (OH) ₂ and to cure the curable monomer. Heat dissipation foam sheet formed by hydrolyzing Mg (OH) ₂ in accordance with the present invention is improved adhesion area and bonding force to the electronic products can be effective heat conduction and heat dissipation.

The adhesive heat-resistant foam sheet formed by hydrolyzing Mg (OH) ₂ is a base resin sheet and a heat-dissipating foam sheet having a plurality of bubbles formed in the sheet, wherein the bubbles are hydrolyzate of Mg (OH) ₂ . Phosphorus MgO particles. The contained MgO fine particles impart fire resistance to the heat radiation foam sheet.

In the method for producing the adhesive heat-resistant foam sheet according to the present invention, the curable monomer is preferably an acrylic monomer such as an alkyl group-containing (meth) acrylic acid ester monomer having 1 to 12 carbon atoms, and the coating liquid containing the acrylic monomer is copolymerized. It is more preferred to add further possible polar monomers.

In addition, in the method of manufacturing the adhesive heat-resistant foam sheet according to the present invention, it is preferable to further add a thermally conductive filler to the coating liquid, and after the step (S1), partially polymerize the curable monomer to obtain a viscosity of the coating liquid of 1,000 to 10,000 cps. It is preferable to improve the sheet formability of the coating liquid by adjusting to.

Hereinafter, with reference to the accompanying drawings will be described in detail with respect to the present invention. Prior to this, terms or words used in the specification and claims should not be construed as having a conventional or dictionary meaning, and the inventors should properly explain the concept of terms in order to best explain their own invention. Based on the principle that can be defined, it should be interpreted as meaning and concept corresponding to the technical idea of the present invention. Therefore, the embodiments described in this specification and the configurations shown in the drawings are merely the most preferred embodiments of the present invention and do not represent all the technical ideas of the present invention. Therefore, It is to be understood that equivalents and modifications are possible.

Usually, Mg (OH) ₂ is used to impart flame retardancy to building interior materials such as wallpaper (see Japanese Patent Application Laid-Open Nos. 2003-25517, 1999-100456, 2000-95889, etc.). By the way, Mg (OH) ₂ is hydrolyzed by applying more than 100 ° C heat to generate water, MgO fine particles are produced as the hydrolyzate.

The inventors have produced such a Mg (OH) attention to the characteristics of the _two, which was added to the viscous heat dissipation sheet made of foam when Mg (OH) _2, and hydrolyzing it by heating the viscous heat dissipation sheet of the present invention form. That is, water generated by the hydrolysis of Mg (OH) ₂ is discharged as water vapor by heat to generate bubbles in the sheet, and MgO, a hydrolyzate of Mg (OH) ₂ , remains inside the bubbles to impart fire resistance to the sheet. do.

Illustrative preferred manufacturing method of the adhesive heat-resistant foam sheet of the present invention is as follows, but is not limited thereto.

First, a coating liquid containing a curable monomer is prepared (step S1). Curable monomers include both thermosetting monomers and photocurable monomers. Such a curable monomer may be used regardless of whether the curable resin of the curable monomer has its own adhesive property, but preferably, it is possible to manufacture a sheet which can be easily attached to an electronic product without a separate adhesive layer coating process. What is necessary is just to have adhesiveness.

As such a curable monomer, it is preferable to use an acrylic monomer, but as the acrylic monomer, a (meth) acrylic acid ester monomer having an alkyl group having 1 to 12 carbon atoms can be exemplified, and a polar monomer copolymerizable with this monomer is further added. Copolymerization is preferable. At this time, it is preferable that 1-20 weight part of polar monomers copolymerize with respect to 100 weight part of (meth) acrylic-ester type monomers which have a C1-C12 alkyl group. The resin in which such copolymerized acrylic monomer is cured is excellent in self-adhesion, and thus has good adhesive strength with the adherend, and has an effect of improving thermal conductivity.

As a (meth) acrylic-ester type monomer which has the said C1-C12 alkyl group, for example, butyl (meth) acrylate, hexyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) An acrylate, 2-ethylhexyl (meth) acrylate, isononyl (meth) acrylate, etc. are mentioned, These can be used individually or in mixture of 2 or more types of these, respectively. Moreover, as a polar monomer copolymerizable with the above-mentioned (meth) acrylic acid ester system monomer, For example, the monomer which has a carboxyl group like (meth) acrylic acid, maleic acid, a fumaric acid, acrylamide, N-vinylpyrrolidone, and A monomer having a nitrogen such as N-vinyl caprolactam or the like may be used alone or in combination of two or more thereof. Such polar monomers act to impart high cohesion and improve adhesion to the final cured resin.

In addition, the coating liquid containing the curable monomer may further include a thermal initiator and / or photoinitiator according to the type of the curable monomer. At this time, the degree of polymerization of the curable monomer can be adjusted according to the amount of the thermal initiator or photoinitiator. In addition, the coating solution may include both a thermal initiator and a photoinitiator, thereby enabling dual curing. In this case, photocuring may be performed initially, and then thermal curing may be sequentially performed.

It is preferable to use 0.01-10 weight part of a thermal initiator and a photoinitiator with respect to 100 weight part of curable monomers. In the case of using an acrylic monomer as the curable monomer, although not particularly limited, a thermal initiator may be an amine, a peroxide such as benzoyl peroxide, azobisisobutylonitrile, or the like, and an alpha-hydroxyaceto Phenone, 1-hydroxycyclohexylphenyl ketone, 2,2-dimethoxy-2-phenyl-acetophenone, xanthone, benzaldehyde, anthraquinone, 3-methylacetophenone, 4-chlorobenzophenone, 4,4'-dimeth Methoxy benzophenone, 4,4'-diaminobenzophenone, benzoin propyl ether, benzoin ethyl ether, 1- (4-isopropyl-phenol) -2-hydroxy-2-methyl propan-1-one, thiox Xanthone etc. can be used.

Moreover, a crosslinking agent can be further added to the coating liquid of this invention. According to the addition amount of such a crosslinking agent, the adhesive characteristic of a sheet | seat can be adjusted. It is preferable to use 0.01-10 weight part with respect to 100 weight part of curable monomers as a crosslinking agent. When using an acryl-type monomer as a curable monomer, although it does not specifically limit, A polyfunctional acrylate, a 1, 2- ethylene glycol diacrylate, a 1, 12- dodecane diol acrylate, etc. are independent, or these are mixed 2 or more types, respectively. It can be used as a crosslinking agent.

The coating liquid includes all the states that can be applied to the substrate, such as liquid, paste, and high viscosity dough.

In the method for producing a pressure-sensitive adhesive foam sheet according to the present invention, after the step (S1) described above, a polar monomer capable of copolymerizing with a curable monomer, for example, a (meth) acrylic acid ester monomer having an alkyl group having 1 to 12 carbon atoms. It is preferable to partially polymerize to adjust the viscosity of the coating liquid to 1,000 to 10,000 cps. Use of the coating liquid having an appropriate viscosity in the above-described range improves the moldability of the sheet.

Subsequently, Mg (OH) ₂ is added and dispersed in the prepared coating solution (S2 step).

Mg (OH) ₂ is to act as a blowing agent, the amount is preferably 0.01 to 50% by weight based on the total weight of the curable monomer.

  Moreover, it is preferable to further add a thermally conductive filler to the above-mentioned coating liquid. These thermally conductive fillers can be used as long as the conventional thermally conductive fillers added to the heat dissipation sheet, for example, particles (metal, aluminum, nickel or alloys thereof) having a particle diameter of 1 nm ~ 200μm, ceramics (boron carbide, etc.) ) Particles, polymer molded particles, carbon black, carbon fiber, acetylene black and the like can be used alone or in combination thereof. The amount of the thermally conductive filler added may be, for example, 0.05 to 500% by weight based on the total weight of the curable monomer.

In addition, in the coating liquid of the above-mentioned (S1) and (S2) step, the foaming agent, pigment, antioxidant, stabilizer, dispersant, antifoaming agent, thickener, plasticizer, tackifying resin, silane binder, brightener other than Mg (OH) ₂ as necessary. Additives, such as these, can be added further. As such a blowing agent, for example, sulfonylhydrazides such as p, p'-oxybis (benzenesulfonylhydrazide), benzenesulfonylhydrazide, toloenesulfonylhydrazide, and azodicarbons Azo compounds such as amide (ADCA), azobisisophthtonitrile, N, N'-dinitrosopentamethylenetetramine, N, N'-dimethyl-N, N'-dinitrosoteretamide, and the like Organic blowing agents such as nitroso compounds, inorganic blowing agents such as sodium bicarbonate, ammonium bicarbonate and the like can be exemplified, but are not limited thereto.

Then, the resultant of step (S2) is applied to the substrate, and then heat is applied to hydrolyze the Mg (OH) ₂ to cure the curable monomer (step S3).

When the coating liquid in which Mg (OH) ₂ is dispersed is applied to the surface of the substrate to a predetermined thickness and then heated at 100 ° C. or more, Mg (OH) ₂ is hydrolyzed into water and MgO fine particles. The generated water is discharged into the steam by the heat applied to the coating liquid to generate bubbles in the sheet, and MgO, a hydrolyzate of Mg (OH) ₂ , remains inside the generated bubbles to impart fire resistance to the sheet. The curable monomer applied in this process is also cured by UV irradiation or preferably heat to complete the heat dissipation foam sheet.

As the base material that is the coating object of the coating liquid in which Mg (OH) ₂ is dispersed, any material can be used as long as the sheet can be manufactured by applying a coating liquid such as PET film. It can be used as a heat dissipation sheet for electronic products. In addition, the coating liquid in which Mg (OH) ₂ is dispersed is applied to a metal sheet having excellent thermal conductivity, and can be used as a heat dissipating sheet as it is in a form in which the heat dissipating foam sheet and the metal sheet are combined.

1 is a schematic cross-sectional view of the adhesive heat-resistant foam sheet 10 of the present invention produced by the above-described method. The adhesive heat-resistant foam sheet 10 formed on one surface of the substrate 7 is a heat-resistant foam sheet 10 in which a sheet 1 made of a base resin and a plurality of bubbles 3 are formed inside the sheet 1. The bubbles 3 inside contain MgO fine particles 4 which are hydrolysates of Mg (OH) ₂ . Bubbles in the sheet 10 generated by the water vapor generated by the hydrolysis of Mg (OH) ₂ give the sheet 10 adhesiveness and cushioning. In particular, the bubbles formed on the surface are relatively large in size, and thus the cushioning property is increased, so that the adhesion to the heating element is further improved, and the contact area with the electronic heating element is also increased. This enables effective heat transfer and heat dissipation in the thickness direction and in the horizontal direction.

The base resin is preferably a resin in which the above-mentioned curable monomer is cured, but any one can be used as long as bubbles are formed by hydrolysis of Mg (OH) ₂ dispersed therein and thus can be produced as an adhesive heat-resistant foam sheet. . For example, the base resin may be acrylic resin, silicone resin, urethane resin, melamine resin, epoxy resin, natural rubber, butadiene rubber, isoprene rubber, ethylene propylene rubber ( ethylene propylene rubber, nitrile rubber, acrylonitrile butadiene rubber, isobutylene isoprene rubber, silicone rubber, etc., alone or two or more thereof. It can be mixed and used.

Although the thickness of the adhesive heat radiation foam sheet of this invention is not specifically limited, It is preferable that they are 50um-1000um. If the thickness is too thin, it is difficult to serve as an effective heat dissipation sheet, and if the thickness is too thick, it is difficult to actually apply to electronics and the economic efficiency is also lowered.

Hereinafter, examples will be described in order to describe the present invention in more detail. However, embodiments according to the present invention can be modified in many different forms, the scope of the present invention should not be construed as limited by the embodiments described below. Embodiments of the invention are provided to more fully describe the present invention to those skilled in the art.

≪ Example 1 >

96 parts by weight of 2-ethyl hexyl acrylate and 4 parts by weight of polar monomer acrylic acid were partially polymerized in a 1 liter glass reactor to obtain a syrup having a viscosity of 3,500 cps. 0.7 parts by weight of benzoyl peroxide (BPO) as a thermal initiator and 0.7 parts by weight of 1,6-hexanediol diacrylate (HDDA) as a crosslinking agent were added to 100 parts by weight of the obtained syrup and mixed, followed by stirring sufficiently to prepare a coating solution. It was. Here, as a thermally conductive filler, spherical AlOH ₂ powder having an average particle diameter of 20 um was mixed so as to be 100 vol% of the coating solution, followed by stirring until it was sufficiently uniform. Subsequently, 5 parts by weight of Mg (OH) ₂ was added thereto, stirred, and degassed under reduced pressure using a vacuum pump. Then, using a micro bar, the coating liquid containing Mg (OH) ₂ dispersed therein was It was coated with a thickness of 1 mm on a PET film, and the resultant was left in a 120 ° C. oven for 7 minutes to obtain a specimen according to this example.

<Example 2>

As a blowing agent, it was prepared in the same manner as in Example 1 except that 15 parts by weight of Mg (OH) ₂ was mixed.

<Example 3>

As a blowing agent, it was prepared in the same manner as in Example 1 except that 20 parts by weight of Mg (OH) ₂ was mixed.

<Example 4>

As a blowing agent, it was prepared in the same manner as in Example 1 except for mixing Mg (OH) ₂ in 25 parts by weight.

&Lt; Comparative Example 1 &

As a blowing agent, it was prepared in the same manner as in Example 1 except that Mg (OH) ₂ was not mixed.

The components and contents of the sheets according to the above examples and comparative examples are summarized in Table 1 below.

division Mg (OH) ₂ content Example 1 5 parts by weight Example 2 15 parts by weight Example 3 20 parts by weight Example 4 25 parts by weight Comparative Example 1 none

The physical properties of the sheet specimens according to the above-described examples and comparative examples were evaluated as follows.

1.Adhesion test

The adhesive force in the 180 degree direction with respect to the aluminum plate with respect to the sheet | seat manufactured by the said Example and the comparative example was measured based on JISZ1541. At this time, the leaving time was 30 minutes at room temperature. The measurement results are shown in Table 2 below.

2. Thermal conductivity test

The sheets prepared in Examples and Comparative Examples were cut to a size of about 60 mm x 120 mm, and the thermal conductivity of the specimen was measured using a rapid thermal conductivity meter QTM-500 manufactured by Kyoto Electronics. The measurement results are shown in Table 2 below.

3. Measurement of adhesive area of sheet

First, the sheets obtained in the above Examples and Comparative Examples were cut to a size of 150 mm X 200 mm. After laminating the cut sheet on the aluminum substrate, a 3 mm thick glass plate was placed on the sheet, and then two weights having a load of 2.9 kg were placed on the glass plate. At this time, after attaching seven protrusions of about 100 micrometers to an aluminum base material, it tested by making this protrusion contact with a sheet | seat. After 1 minute and 30 seconds had elapsed since the weight was placed, the area where the glass plate and the sheet were attached was taken with a digital camera, and the images were analyzed and measured.

Adhesive force (g / in) Adhesive Area Thermal conductivity (W / mK) Example 1 850 70% 0.44 Example 2 756 75% 0.43 Example 3 765 75% 0.43 Example 4 740 80% 0.41 Comparative Example 1 770 66% 0.45

Referring to the results of Table 2, it can be seen that the adhesive area of the adhesive heat-resistant foam sheet of the Example is significantly improved than Comparative Example 1. At this time, the thermal conductivity of the adhesive heat-resistant foam sheet of the embodiment appears to be somewhat small, but this is a measurement result of the thermal conductivity of the sheet itself. Therefore, when applied to the actual electronic products, the thermal conductivity and dispersion proceeds efficiently in the thickness and horizontal direction as the adhesion area is much wider, it has a better thermal conductivity than the comparative example.

On the other hand, when comparing Examples 1 to 4, it can be seen that the larger the content of Mg (OH) _2, the adhesion area is improved.

As described above, the adhesive heat-resistant foam sheet formed by hydrolyzing Mg (OH) ₂ according to the present invention can be produced simply and economically.

The adhesive heat-resistant foam sheet according to the present invention is firmly adhered to the heating element due to the bubbles formed on the surface, and the contact area with the electronic heating element is also increased. Accordingly, heat is effectively transmitted and distributed in the thickness direction and in the horizontal direction, thereby providing excellent heat dissipation effect.

In addition, the adhesive heat-resistant foam sheet of the present invention can be usefully applied to products requiring slimming, such as plasma display panels as well as general electronic products.

Claims (14)

(S1) preparing a coating liquid containing a curable acrylic monomer; (S2) adding and dispersing Mg (OH) ₂ to the coating solution; And (S3) Method of producing a pressure-sensitive adhesive heat-resistant foam sheet comprising the step of applying the resultant of the step (S2) to the substrate and then applying heat to hydrolyze the Mg (OH) ₂ , and curing the curable acrylic monomer. delete The method of claim 1, Said curable acrylic monomer is an alkyl group-containing (meth) acrylic acid ester monomer having 1 to 12 carbon atoms. The method of claim 3, The curable acrylic monomer is a method for producing a pressure-sensitive adhesive heat-resistant foam sheet, characterized in that it further comprises a polar monomer copolymerizable with an alkyl group-containing (meth) acrylic acid ester monomer having 1 to 12 carbon atoms in the coating liquid. The method of claim 1, The amount of the Mg (OH) ₂ is a method of producing a pressure-sensitive adhesive heat-resistant foam sheet, characterized in that 0.01 to 50% by weight based on the total weight of the curable acrylic monomer. The method of claim 1, The method of manufacturing a pressure-sensitive adhesive heat-resistant foam sheet characterized by further adding a thermally conductive filler to the coating liquid. The method of claim 6, The amount of the thermally conductive filler added is 0.05 to 500% by weight based on the total weight of the curable acrylic monomer, the method of producing a pressure-sensitive adhesive heat-resistant foam sheet. The method of claim 1, After the step (S1), by partially polymerizing the curable acrylic monomer, the method of manufacturing a pressure-sensitive adhesive foam sheet, characterized in that it further comprises the step of adjusting the viscosity of the coating solution to 1,000 to 10,000 cps. A sheet of base resin and a heat dissipating foam sheet having a plurality of bubbles formed therein, The base resin is a resin formed by curing the acrylic monomer, The bubbles are formed due to the release of water vapor formed by hydrolysis of Mg (OH) ₂ , Adhesive foamed heat-resistant foam sheet, characterized in that the plurality of bubbles contained in the MgO fine particles of the hydrolyzate of Mg (OH) ₂ . delete 10. The method of claim 9, Adhesive heat-resistant foam sheet further comprising a thermally conductive filler. 12. The method of claim 11, Content of the thermally conductive filler is a pressure-sensitive adhesive heat-resistant foam sheet, characterized in that 0.05 to 500% by weight based on the total weight of the curable acrylic monomer. 10. The method of claim 9, The pressure-sensitive adhesive heat-resistant foam sheet is characterized in that the thickness of 50um to 1000um. 10. The method of claim 9, Adhesive heat-resistant foam sheet characterized in that it further comprises a metal sheet laminated on one surface of the adhesive heat-resistant foam sheet.

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