KR20110049505A - Method for manufacturing of the adhesive sheet for shock absorbtion - Google Patents

Abstract

PURPOSE: A method for manufacturing an adhesive sheet for shock absorption is provided to block the access of various foreign materials by using a protection film on the gel surface and to enable reuse since the residue of gel does not remain. CONSTITUTION: A method for manufacturing an adhesive sheet for shock absorption comprises the steps of: adding 40 parts by weight of polypropylene glycol(molecular weight of 3000) to 100 parts by weight of a compound obtained by reacting polypropylene glycol(molecular weight of 650) with 4,4-diphenylmethane diisocyanate, applying the mixture on a PET film, and drying the mixture at 120°C for 3 minutes to form a polyurethane foam layer(2); coating a compound obtained by reacting polypropylene glycol(molecular weight of 3500) with 4,4-diphenylmethane diisocyanate on a PET film, and drying the mixture at 70 ~ 100°C for 4 minutes to prepare a polyurethane gel layer(1); and coating the polyurethane gel layer on the polyurethane foam layer, coating the coated material on the upper part of the PET film, and drying the material at 100°C for 4 minutes to manufacture a polyurethane elastomer.

Description

Method for manufacturing adhesive sheet for shock absorption {Method for manufacturing of the adhesive sheet for shock absorbtion}

The present invention relates to a pressure-absorbing pressure-sensitive adhesive sheet composed of a polyurethane gel layer (1), a polyurethane foam layer (2), and a PET film layer (3), and a method of manufacturing the same.

A liquid crystal display (LCD) is a device that displays a screen by inserting a liquid crystal between two thin glass substrates. In the device, when a voltage is applied through an electrode connected to the liquid crystal, the molecular arrangement of the liquid crystal is changed, and thus, the rate of light passing through the liquid crystal is changed, thereby displaying a picture or color. Such a liquid crystal display device is a display device that is currently in the spotlight in various fields because of the advantages of low power consumption and flatness.

In order to manufacture a liquid crystal display device, a liquid crystal cell and a polarizing plate including a glass substrate and the like having a liquid crystal and a transparent electrode layer are basically required, and an adhesive layer or an adhesive layer for bonding them is required. The polarizing plate includes an iodine-based compound or a dichroic polarizing material arranged in a predetermined direction, and has a multi-layered structure including a triacetyl cellulose (TAC) -based protective film for protecting the polarizer on both sides.

In addition, the polarizing plate may additionally include a functional film such as a retardation plate, a wide viewing angle compensation plate, or a brightness enhancement film in view of further function improvement. As described above, each film constituting the multilayer polarizing plate is made of a material having a different molecular structure and composition, and thus has different physical properties from each other. Thus, under high temperature and / or high humidity conditions, dimensional stability is lacking due to the difference in shrinkage or expansion behavior of materials with unidirectional molecular arrangements. Therefore, when the polarizing plate is fixed by the pressure-sensitive adhesive, stress is concentrated in the TAC layer due to shrinkage or expansion under high temperature and / or high humidity conditions, thereby causing birefringence and light leakage phenomenon. As a representative method for solving the above problems, there is a method of providing a stress relaxation characteristic by designing the pressure-sensitive adhesive to be large, easy to deform the creep to the external stress. Specifically, it is a method of mixing a low molecular weight material containing or not containing a small amount of a crosslinkable functional group with a high molecular weight polymer containing a functional group capable of reacting with a crosslinking agent (Korean Patent Publication No. 1998-79266, Japanese Patent Publication) 2002-47468 and Japanese Patent Laid-Open No. 2003-49141 and the like.

However, the pressure-sensitive adhesive composition disclosed in the above technique is inferior in cutting property, and thus, when the polarizing plate is manufactured, squeezing or squeezing of the pressure-sensitive adhesive occurs and the yield is greatly reduced. Another technique for preventing light leakage is to design the adhesive very hard. As described above, when the pressure-sensitive adhesive has hard physical properties, by minimizing the shrinkage and expansion of the polarizing plate under high temperature and / or high humidity conditions, the generated stress can be minimized, and the excellent optical properties can be realized by focusing on the outermost part of the polarizing plate. have.

However, in order to implement a hard adhesive as described above, the modulus of the bulk of the adhesive should be greatly increased, but as the modulus is greatly increased, the adhesive force is greatly lowered and durability becomes worse.

On the other hand, it is difficult to implement the bulk modulus of the level that can maintain the low light leakage characteristics and durability at the same time only with a conventional single crosslinked structure, adding a photoinitiator and a multifunctional acrylate to the existing single crosslinked structure, A method of improving is proposed (ex. Japanese Patent Laid-Open Nos. 2007-197659 and 2007-212995, etc.). In the technique disclosed in the above document, while using a carboxyl group-containing acrylic copolymer, the adhesion between the protective film (TAC) and the pressure-sensitive adhesive interface is improved, and the polyfunctional isocyanate serving as a curing agent of the acrylic copolymer is included in the composition as an essential additive. (Japanese Patent Laid-Open No. 2007-197659). However, when only the carboxyl group is used as the functional group of the acryl-based copolymer, since the reaction rate of the carboxyl group and the isocyanate group is slow at room temperature, the adhesive force is greatly increased by the residual isocyanate group, and a problem occurs in terms of re-peelability.

In addition, when the hydroxy group-containing acrylic copolymer and the carboxyl group-containing acrylic copolymer are mixed at a constant ratio to increase the reaction with the isocyanate group (Japanese Patent Laid-Open No. 2007-212995), the above-mentioned problem of the initial increase in adhesive strength is solved to some extent. However, when long-term storage at high temperature, the curing reaction is greatly promoted, causing problems in terms of high temperature durability. In addition, in the pressure-sensitive adhesive composition disclosed in the above document, haze occurs in the final pressure-sensitive adhesive material as the content of the polyfunctional acrylate is increased, and the adhesive force is greatly reduced, thereby causing problems in terms of high temperature durability.

Accordingly, the present inventors have developed a pressure-sensitive adhesive sheet for mobile phone LCD having the effect of strong adhesion and shock absorption.

The present invention relates to a pressure-absorbing adhesive foam sheet and a method of manufacturing the same.

In order to achieve the above object, the present invention (a) 40 parts by weight of polypropylene glycol (molecular weight 650) to 100 parts by weight of a compound obtained by reacting polypropylene glycol (molecular weight 3,000) and 4,4-diphenylmethane diisocyanate After the addition to apply a PET film and dried for 3 minutes at 120 ℃ to prepare a polyurethane foam layer (2); (b) Applying a compound obtained by reacting 4,4-diphenylmethane diisocyanate with a polyester polyol (molecular weight 3,500) on a PET film and dried for 4 minutes at 70 ~ 100 ℃ to prepare a polyurethane gel layer (1) step; And (c) applying a polyurethane gel layer on the prepared polyurethane foam layer, and then applying it on top of the PET film layer to dry it at 4O < 0 > C for 4 minutes to produce a polyurethane elastomer. It provides a method for producing a foam sheet.

The present invention also provides a polyurethane gel layer (1) comprising a polyester polyol (molecular weight 3,500) and 4,4-diphenylmethane diisocyanate; A polyurethane foam layer (2) comprising polypropylene glycol (molecular weight 3,000), 4,4-diphenylmethane diisocyanate and polypropylene glycol (molecular weight 650); and a PET film layer (3); It provides a pressure-sensitive adhesive foam sheet.

Preferably, the sheet has a structure in which a polyurethane foam layer (2), and a polyurethane gel layer (1) are sequentially stacked on the PET film layer (3).

Preferably, the polyurethane elastic body has a thickness of 0.20 to 1.00 mm, it is possible to further laminate a protective film or a release film (3) to the polyurethane elastic body, it is suitable as an adhesive foam sheet for a mobile phone LCD substrate.

Preferably, the polyester-based polyol or polyether-based polyol has two or more hydroxyl groups in the molecule, polyethylene glycol having a molecular weight of 200 to 3,000, polypropylene having two or more hydroxyl groups in the molecule, molecular weight of 400 to 7,000 Glycol, ethylene oxide / propylene oxide random copolymer having three hydroxyl groups in the molecule, molecular weight 3,000 ~ 7,000, polytetramethylene glycol having two hydroxyl groups in the molecule, molecular weight 600 ~ 4,000 can be used alone or in combination However, this is not limitative.

Preferably, as said polyisocyanate, aromatic, aliphatic, and alicyclic diisocyanate, dimer, trimer, etc. of these diisocyanates are mentioned. As aromatic, aliphatic and alicyclic diisocyanates, 4,4-diphenylmethylene diisocyanate, toluene diisocyanate, triylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate , Isophorone diisocyanate, hydrogenated diphenylmethane diisocyanate, 1,5-naphthylene diisocyanate, 1,3-phenylene diisocyanate, 1,4-phenylenedi isocyanate, butane-1,4-diisocyanate , 2,2,4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, cyclohexane-1,4-diisocyanate, dicyclohexylmethane-4,4-diisocyanate, 1,3 -Bis (isocyanate methyl) cyclohexane, methyl cyclohexane diisocyanate, m-tetramethyl xylylenediisocyanate The site can be like. In addition, dimers, trimers and polyphenylmethanepolyisocyanates thereof are used. An isocyanurate type, a biuret type, an allophanate type, etc. are mentioned as a trimer, It can select suitably and can use. These polyisocyanates can be used individually or in combination.

According to the above problem solving means, the adhesive sheet according to the present invention can block the access of various foreign substances by using a protective film on the surface of the gel, the residue of the gel does not remain during peeling, can be reused, strong adhesion and shock absorption Has the effect of. Therefore, it can be used for shock absorbers and adhesives (SUS, Glass, PMMA, etc.) of various applications at low cost.

Hereinafter, the present invention will be described in detail by the following examples. However, the following examples are illustrative of the present invention, and the contents of the present invention are not limited by the following examples.

Example

Example 1 Preparation of Polyurethane Foam Layers

40 parts by weight of polypropylene glycol (molecular weight 650), 1 part by weight of foam stabilizer, and 0.3 amine catalyst in 100 parts by weight of a compound obtained by reacting polypropylene glycol (molecular weight 3,000) and 4,4'-diphenylmethane diisocyanate. After adding 3 to 5 parts by weight of lyabu and black pigment, the mixture was stirred at high speed (5,200 rpm) with a mixing head and coated on PET (thickness 75㎛), and then foamed at 120 ° C for 3 minutes to make a uniform polyurethane foam layer (thickness). 150 μm, CELL size 2 μm, black).

Example 2: Preparation of Polyurethane Gel Layer

Polyurethane gel (viscosity 45,000 cps) prepared by reacting a polyester polyol (molecular weight 3,500) prepared with a reaction of ethylene glycol and adipic acid with 4,4'-diphenylmethane diisocyanate was applied onto PET (thickness 75 μm). Then, it was dried for 4 minutes at 70 ~ 100 ℃ to obtain a viscous polyurethane gel (viscoelastic, thickness 150㎛, transparent) layer of 150㎛ thickness.

Example 3: Preparation of Polyurethane Elastic Body

Applying a polyurethane gel layer (manufactured Example 2) on the polyurethane foam layer (manufactured Example 1), and then applied to the top of the PET (50㎛) layer and dried for 4 minutes at 100 ° C polyurethane foam layer and polyurethane A polyurethane elastomer was obtained, consisting of a gel (viscoelastic) layer.

Thereafter, the release paper was laminated on the elastic layer to complete a pressure-sensitive adhesive sheet of polyurethane (400 μm in total thickness). That is, as shown in FIG. 1, the adhesive sheet of this invention is comprised from the polyurethane gel layer 1, the polyurethane foam layer 2, and the PET film layer 3. As shown in FIG.

Therefore, the thickness and color of the adhesive sheet are as shown in Table 1 below, the general physical properties of the adhesive sheet was confirmed through a self test (see Table 2).

thickness color PE Film 50 μm Transparent or colored Polyurethane gel layer 150 μm Transparency Polyurethane foam layer 150 μm black PET layer 50 μm Transparency

unit value Etc Thickness mm 0.3 (± 2.2%) Self test Density Kg / m ² 0.721 25% Compress Load deflection Kgf / cm ² 1.6 Compression Set % 4.4

Comparative example

Polyurethane viscous liquid (viscosity 6,000 cps) obtained by reacting polypropylene glycol (molecular weight: 3,000) and 4,4'-diphenylmethane diisocyanate was coated on a release paper to obtain a polyurethane gel layer (thickness 200 μm). By attaching the sheet to the PC LCD substrate, cushioning was not maintained, and it was confirmed that the tip portion was damaged.

Example 4 Comparison of Shock Absorption Rate with Time

The sheet according to the present invention was attached to PMMA (Poly Methyl Meta Acrylate) and SUS (sten) plate to compare the shock absorption rate with time (see Tables 1 and 2 below).

matter PMMA (kgf / 25 mm) Condition After 20 minutes (R.T) After 72 minutes (R.T) Humi. 80 minutes (50 ℃) -20 ℃ (24 hours) SF-2 2.0 2.8 2.2 2.9

matter SUS (kgf / 25mm) Condition After 20 minutes (R.T) After 72 minutes (R.T) Humi. 80 minutes (50 ℃) -20 ℃ (24 hours) SF-2 2.2 3.0 2.2 2.9

As shown in Table 3 and Table 4 above, the sheet according to the present invention has demonstrated excellent performance in the impact absorption test with temperature and time. Therefore, the cushioning is maintained by attaching to the mobile phone LCD substrate can be effectively used without damaging the tip portion.

Example 5 Comparison with Prior Art

The sheet of 8 mm x 15 mm and the prior art (Example 1) according to the present invention were attached to the drop collision, which was dropped to measure the maximum deceleration using an accelerometer. In addition, the maximum deceleration of the drop collision without the sheet was measured.

At this time, the sheet of the present invention and the prior art was performed for the same thickness, the drop height is 20 mm, the weight of the falling collision is 5 kg, calculated in terms of 100g × 1m drop energy.

When no sheet is attached Sheet attachment Invention Prior Art (Example 1) Deceleration (m / s ² )
184 76 98 Decay rate (%) - 58% reduction 47% reduction

As shown in Table 5, the maximum deceleration, if it is not attached to the sheet showed a 184 m / s ^2, the case of 76m / s ^2, the prior art for the present invention exhibited a 98 m / s ² . Thus, the sheet according to the present invention was confirmed to be reduced by about 11% compared to the prior art.

1 shows a cross section of an adhesive sheet according to the present invention.

** Description of the main layers of the drawing **

1: polyurethane gel layer 2: polyurethane foam layer

3: PET film layer

Claims (5)

In the manufacture of a shock absorbing adhesive foam sheet, (a) 40 parts by weight of polypropylene glycol (molecular weight 650) is added to 100 parts by weight of a compound obtained by reacting polypropylene glycol (molecular weight 3,000) and 4,4-diphenylmethane diisocyanate, and then applied on a PET film to 120 ° C. Drying in 3 minutes to prepare a polyurethane foam layer (2); (b) Applying a compound obtained by reacting 4,4-diphenylmethane diisocyanate with a polyester polyol (molecular weight 3,500) on a PET film and dried for 4 minutes at 70 ~ 100 ℃ to prepare a polyurethane gel layer (1) step; And (c) applying a polyurethane gel layer on the prepared polyurethane foam layer, and then applying it on top of the PET film layer to dry for 4 minutes at 100 ℃ to prepare a polyurethane elastomer, shock-absorbing pressure-sensitive foam Manufacturing method of the sheet. The method of claim 1, Method for producing a shock-absorbing adhesive foam sheet, characterized in that the protective film or the release film (3) in addition to the polyurethane elastic body. The method of claim 1, The polyurethane elastomer is characterized in that the thickness of 0.20 ~ 1.00 mm, the method of producing a shock-absorbing adhesive foam sheet. Polyurethane gel layer (1) comprising polyester polyol (molecular weight 3,500) and 4,4-diphenylmethane diisocyanate; A polyurethane foam layer 2 comprising polypropylene glycol (molecular weight 3,000), 4,4-diphenylmethane diisocyanate and polypropylene glycol (molecular weight 650); And PET film layer (3), characterized in that the shock-absorbing adhesive foam sheet. The method of claim 4, wherein The sheet is characterized in that the polyurethane foam layer (2), and the polyurethane gel layer (1) laminated on the PET film layer (3), the shock-absorbing adhesive foam sheet.

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