KR20080102872A - A pressure-sensitive adhesive for protection film of light functionalized sheet - Google Patents

Abstract

An adhesive for sheet protective film is provided to ensure excellent initial tackiness and adhesion by including a natural rubber and synthetic rubber. A manufacturing method of an adhesive for sheet protective film comprises (a) a step for manufacturing a natural rubber solution by masticating a natural rubber containing an acid and dissolving it in an alicyclic organic solvent; (b) a step for manufacturing a synthetic rubber solution by dissolving a synthetic rubber and tackifier in a solution mixed with an aromatic organic solvent and alcohol organic solvent; and (c) a step for blending the natural rubber solution and the synthetic rubber solution by adding a hardener.

Description

Adhesive for photofunctional sheet protective film {A pressure-sensitive adhesive for protection film of light functionalized sheet}

Figure 1 shows the initial adhesive force change curve according to the synthetic rubber content of the pressure-sensitive adhesive prepared according to the present invention.

Figure 2 shows the initial adhesive force change curve according to the content of aliphatic tackifying resin.

Figure 3 shows the initial adhesive force change curve according to the content of the discipidi-based tackifying resin.

Figure 4 shows the initial adhesive force change curve of the pressure-sensitive adhesive prepared in Comparative Example 1 of the present invention.

Figure 5 shows the peeling strength change curve according to the synthetic rubber content of the pressure-sensitive adhesive prepared according to the present invention.

The present invention relates to a rubber-based pressure-sensitive adhesive composition and a method for manufacturing the same, and more particularly, to a pressure-sensitive adhesive that can be used in a photofunctional sheet protective film.

A typical component that acts as a light source in an LCD (Liquid Crystal Display) display is the Back Light Unit (BLU), which is responsible for supplying white light of FCCL (Flexible Copper Clad Laminate) to the panel from the back of the non-light-emitting LCD. .

BLU is designed to be effective in expressing various color information while maintaining the whole screen with uniform brightness in the direction of LCD panel. Although it varies depending on the size and use, BLU is generally used for prism sheet, diffusion sheet (or diffuser plate). ), A light guide sheet, and a reflection sheet, and a total of four sheets. Of the four major sheets, the diffuser sheet allows light from the light guide plate to diffuse evenly on the screen, to transmit in the front direction of the prism sheet, to widen the viewing angle, and to reduce the pattern of the light guide plate. The prism sheet is a sheet that increases brightness by refracting and condensing light that diffuses rapidly in both horizontal and vertical directions while passing through the diffusion sheet, and becomes brighter light.

The material of the prism sheet is coated by irradiating UV acrylate oligomer on a polyethylene terephthalate (PET) substrate, and the diffusion sheet is mostly coated with acrylic beads on PET. This acrylate surface property is applied to the protective film pressure-sensitive adhesive form used to protect the photo-functional sheet as an acrylate to induce a secondary bond with the polar group of the -COOH group and -OH group in the polymer, a considerable late It causes a change over time, and also causes a transfer as the width of the change in adhesion increases gradually. Therefore, a non-polar rubber-based adhesive should be used as an adhesive for protecting the photofunctional sheet.

A pressure-sensitive adhesive is a material having viscoelastic properties that can be strongly adhered in a short time with a small pressure. Adhesives are widely used in the electrical and electronics industry, automobile industry, protective film industry, wood composite materials and furniture industry, civil construction industry and coating materials, etc. Recently, with the development of the industry, the use and importance of adhesives are highlighted in many aspects. In particular, the pressure-sensitive adhesive industry for protective films for the surface protection of parts and finished products is mainly made of synthetic rubber and acrylic pressure-sensitive adhesives, and has a large import dependency.

Pressure-sensitive adhesives are largely classified into rubber, hot melt, acrylic and silicone based on their raw materials. Among them, the rubber-based pressure-sensitive adhesive is made of natural rubber and synthetic rubber, but the rubber has elasticity and thus hardly exhibits adhesive properties by itself. Therefore, a tackifier must be added.

Natural rubber used for pressure-sensitive adhesives are collected in latex form from stems of trees, but the raw rubbers obtained therefrom are of two types: smoked sheet and pale crape. Smoked sheet rubber is coagulated with latex acid, washed in water and dried in smoking room for a long time.Fail crepe is coagulated by adding a small amount of sodium bisulfite to latex and then adding acetic acid or formic acid. . The main component of natural rubber is cis-1,4-polyisoprene, which is uneven in quality depending on the type and origin of rubber tree and has a unique complexity of natural products and contains several percent of impurities. . In addition, since natural rubber has unsaturated double bonds in the main chain regardless of its type, it has a disadvantage of being easy to deteriorate in the presence of oxygen and light and poor weather resistance.

However, the packaging tapes (cellophane tape, kraft) have good compatibility with various tackifying resins and have the disadvantages of being used only in solvent type because they have excellent adhesion, cold flow resistance and cohesiveness. Tapes, OPP tapes and PVC tapes), heat-resistant masking tapes, surface protection tapes, hardening tapes for electrical insulation, fastening tapes, and medical tapes.

However, in the case of natural rubber, it is generally required to go through a separate processing process, the so-called (mastication) process to improve the processability by lowering the high viscosity due to the large molecular weight, the efficient Soviet method is still required. International application PCT / JP1999 / 03309 proposes a method of providing a pressure-sensitive adhesive that omits this Soviet process.

Synthetic rubber used in the pressure-sensitive adhesive is mainly used block copolymer (block copolymer) system. The block copolymer is a molecule composed of two or more components consisting of blocks. In the middle, polybutadiene, polyisoprene, and the like have polystyrene blocks at their ends. The lack of incompatibility causes the styrene block to act as a crosslinking point for forming domains. Therefore, since it exhibits higher cohesiveness than natural rubber adhesives, it is used as a raw material for fixing double-sided tapes, packaging tapes, diaper tapes, and the like, and is being used for special adhesives. Adhesives using synthetic rubber have different solubility parameters of polystyrene, polybutadiene, and polyisoprene, so they should be prepared in consideration of compatibility with added tackifying resins and blocks. Generally, aromatic tackifying resins dissolve well on styrene blocks and aliphatic tackifying resins dissolve well on rubber.

International Application PCT / JP2001 / 003627 proposes a tackifier obtained by polymerizing a vinyl monomer at 180 to 350 ° C. in order to provide a pressure-sensitive adhesive and weather resistant adhesive composition. In addition, Korean Patent Publication No. 10-2006-0046099 proposed a method of containing a cationic surfactant and perchlorate in the polymer for pressure-sensitive adhesive in order to provide a pressure-sensitive adhesive composition and film for a surface protection film having excellent antistatic properties.

The present invention is to provide a pressure-sensitive adhesive composition comprising a natural rubber and synthetic rubber and a method for producing the same.

In addition, to provide a pressure-sensitive adhesive composition excellent in the initial adhesive strength and adhesive force, to provide a pressure-sensitive adhesive suitable for the optical functional sheet protective film.

According to a preferred embodiment of the present invention, (a) butyric acid, valeric acid, caproic acid, caprylic acid, capric acid, lauric The natural rubber is used as a Soviet accelerator with an acid and activator selected from the group consisting of lauric acid, myristic acid, palmitic acid, stearic acid and benzoic acid. Preparing a natural rubber solution by dissolving in Soviet Union at least one aliphatic organic solvent selected from the group consisting of pentane, hexane, heptane, cyclopentane, cyclohexane, cycloheptane and cyclooctane; (b) dissolving a synthetic rubber and a tackifying resin in a mixed solution of an aromatic organic solvent and an alcohol organic solvent to prepare a synthetic rubber solution; And (c) blending the natural rubber solution with the synthetic rubber solution by adding a curing agent.

According to another suitable embodiment of the present invention, the synthetic rubber is preferably SIS synthetic rubber having a styrene content of 1 to 30% by weight, diblock content of 0 to 50% by weight.

According to another suitable embodiment of the present invention, the tackifying resin is an aliphatic hydrocarbon resin or a dicyclopentadiene resin, and the softening point is preferably 40 to 150 ° C.

According to another suitable embodiment of the present invention, the tackifying resin is an aliphatic hydrocarbon resin having a softening point of 85 to 145 ° C obtained by polymerization of an unsaturated aliphatic olefin and a diolefin obtained by pyrolytic distillation of naphtha, and specifically examples thereof. For example, A-1100, A-1100S, A-1115, C-1100, H-2100, H-2110, H-2120, H-2130, H-2140 H-2200, H-2300, R-1100, T -1080, T-1095 (above, manufactured by Kolon Oil Co., Ltd.), C-100W, and C-115R (above, manufactured by Eastman) are preferable.

According to another suitable embodiment of the invention, (a) in the group consisting of butyric acid, valeric acid, caproic acid, caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid and benzoic acid Soviet rubber with activator added to the selected acid was used to dissolve the natural rubber in at least one aliphatic organic solvent selected from the group consisting of pentane, hexane, heptane, cyclopentane, cyclohexane, cycloheptane and cyclooctane. Natural rubber solution; (b) a synthetic rubber solution obtained by dissolving a synthetic rubber and a tackifying resin in a mixed solution of an aromatic organic solvent of benzene, toluene or xylene and an alcoholic organic solvent of methanol, ethanol or propanol; And (c) an isocyanate-based curing agent, wherein a weight ratio of the natural rubber solution and the synthetic rubber solution in the pressure-sensitive adhesive is 3-9: 1-7, and the curing agent is based on the total weight of the natural rubber solution and the synthetic rubber solution. It is preferable to add 0.01-1 weight%.

The prepared pressure-sensitive adhesive composition contains 30 to 90% by weight of natural rubber solution, 10 to 70% by weight of synthetic rubber solution, and 0.01 to 1% by weight of hardener based on the total weight of natural rubber solution and synthetic rubber solution. In addition, the tackifying resin in the synthetic rubber solution is preferably 40-60% by weight relative to the weight of the pressure-sensitive adhesive.

Hereinafter, the present invention will be described in more detail.

The present invention comprises the steps of preparing a natural rubber solution by dissolving the natural rubber in the Soviet Union containing the acid (a) Soviet Union and then dissolved in an aliphatic organic solvent; (b) dissolving a synthetic rubber and a tackifying resin in a mixed solution of an aromatic organic solvent and an alcohol organic solvent to prepare a synthetic rubber solution; And (c) the pressure-sensitive adhesive composition is prepared by a method comprising the step of blending by adding a curing agent to the natural rubber solution and synthetic rubber solution.

In order to prepare a natural rubber solution, the Soviet Union must first be used to improve the plasticity of natural rubber. The Soviet process includes a mechanical Soviet process of applying mechanical force to natural rubber using a tubon roll or a Benbury mixer, or a chemical Soviet process of adding peroxide to a solution containing natural rubber.

In order to prevent the viscosity and molecular weight of natural rubber from changing rapidly during the storage period, the present invention can be added to the USSR to increase the effect of the Soviet Union and to prevent recombination between rubber and polymers after the Soviet Union to prevent an increase in molecular weight during the storage period. Provides a Soviet way to The Soviet process of the present invention adds 0.1 to 10 phr (parts per hundred) of a Soviet promoter to natural rubber, mixes for 5-20 minutes in a Benbury mixer at room temperature, and then performs Soviet Union for 5-20 minutes in a tubon roll. .

Acids added as Soviet accelerators in the USSR specifically include butyric acid, valeric acid, caproic acid, caprylic acid, capric acid, and lauric acid. lauric acid, myristic acid, palmitic acid, stearic acid, benzoic acid, struktol A 80, struktol a 82 Struktol A 82), Struktol A 86 (manufactured by Stuktol Company of America) and the like can be preferably used.

The natural rubber after the Soviet process is dissolved in an aliphatic organic solvent to prepare a natural rubber solution of 1 to 50%, preferably 1 to 30%. The aliphatic organic solvent is not particularly limited, but pentane, hexane, heptane, cyclopentane, cyclohexane, cycloheptane or cyclooctane is preferable and can be used alone or in combination. The dissolution time is preferably 5 to 100 hours, particularly preferably 10 to 30 hours. In the pressure-sensitive adhesive of the present invention, the viscosity of the preferred natural rubber solution is 1,000 to 20,000 cps (solid content of 1 to 50% by weight).

Synthetic rubber solution used in the pressure-sensitive adhesive of the present invention is preferably prepared using a styrenic block copolymer (SBC) synthetic rubber. A styrene-isoprene-styrene (SIS) -based synthetic rubber having a styrene content of 1 to 30% by weight and a diblock content of 0 to 50% by weight based on the total synthetic rubber weight is particularly preferable.

A tackifying resin is added to rubber to impart tacking performance. The tackifying resin is an amorphous oligomer having a molecular weight of several hundreds to thousands, and is a thermoplastic resin that is liquid or solid at room temperature. Although the rubber itself does not have a tackiness, the fluidity is imparted by the action of the tackifying resin to be added, so that the initial adhesive force, the adhesive force, and the holding force of the rubber-based adhesive are controlled, so the selection of the tackifying resin is very important.

Tackifying resins used in rubber-based adhesives are divided into natural resins and synthetic resins, and their adhesion performance varies depending on the type, molecular weight, and compatibility with rubber.

The rosin system, a natural resin system, has low stability because its main component has a double bond conjugated with abietic acid and its isomers and is easy to oxidize. Therefore, in order to improve this, it is used in the form of modified rosin stabilized by hydrogenation reaction, disproportionation reaction and dimer. Terpene resin, which is a natural resin, is polymerized with a Lewis acid catalyst using terpene oil obtained from pine as a raw material to obtain a terpene resin. Since it is an isoprene polymer, it is widely used because it has excellent compatibility, obtains a balance of adhesive properties in a wide resin concentration range, is easy to develop and design an adhesive, and has a remarkable effect at low temperatures.

As the synthetic resins, aliphatic (C5), aromatic (C9), and dicyclopentadiene (DCPD) systems are mainly used. Aliphatic systems are used in large quantities in kraft tapes and the like because they are used as tackifying resins for rubber-based adhesives, expressing balanced adhesion characteristics and exhibiting stable numerical values. However, since aromatics are incompatible with rubber-based adhesives, they are mainly used in the form of copolymerization with aliphatic.

The tackifying resin of the present invention uses an aliphatic hydrocarbon resin and a dicyclopentadiene hydrocarbon resin having a softening point of 40 to 150 ° C. in order to give adhesive performance to a mixture of natural rubber and synthetic rubber. In view of initial adhesive strength and peel strength, an aliphatic hydrocarbon resin having a softening point of 85 to 145 ° C is particularly preferably used.

Specific examples of aliphatic hydrocarbon resins include A-1100, A-1100S, A-1115, C-1100, C-100W, C-115R, H-2100, H-2110, H-2120, H-2130, H- 2140 H-2200, H-2300, R-1100, T-1080, T-1095, and the like, A-1100, A-1100S, C-100W, C-115R, etc. having a softening point of 90 to 120 ° C. This is particularly preferably used. Examples of the dicyclopentadiene-based hydrocarbon resins include SU-90, SU-100, SU-100S, SU-110, SU-120, SU-130, SU-200, SU-210, SU-220, SU-230, SU-400, SU-420, SU-490 (above, Kolon Oil Co., Ltd.) is mentioned, SU-90, SU-100, SU-100S etc. which have a softening point of 80-120 degreeC are especially preferable. Used.

The synthetic rubber solution is prepared by dissolving the SIS synthetic rubber and an aliphatic hydrocarbon resin or a DCPD hydrocarbon resin tackifying resin in a mixed solution of an aromatic organic solvent and an alcoholic organic solvent. The solvent is not particularly limited, but the aromatic organic solvent is preferably benzene, toluene, xylene, or the like, and the alcohol organic solvent is preferably methanol, ethanol, propanol or the like. The tackifying resin in the synthetic rubber solution is preferably included 30-70% by weight relative to the weight of the final adhesive, particularly preferably 50% by weight.

In the present invention, the pressure-sensitive adhesive is obtained by blending a curing agent in a natural rubber solution and a synthetic rubber solution. Although a hardening | curing agent is not specifically limited, The isocyanate type hardening | curing agent which does not contain a metal ion is used preferably. Among the isocyanate-based curing agents, tris (p-isocyanatophenyl) thiophospahte (tris (p-isocyanatophenyl) thiophospahte) is particularly preferably used.

Among the pressure-sensitive adhesives, the natural rubber solution is 30 to 90% by weight, the synthetic rubber solution is 10 to 70% by weight, and the curing agent is preferably in the range of 0.01 to 1% by weight based on the total weight of the synthetic rubber solution and the natural rubber solution. If the natural rubber solution is less than 30% by weight, a phenomenon occurs that the initial adhesive strength and peel strength of the pressure-sensitive adhesive decreases. If the content of the synthetic rubber solution is more than 70% by weight, the initial adhesive strength is lowered, and the stick-slip failure of cohesive fracture and interfacial fracture occurs during peeling of the prepared protective film. When the content of the curing agent is 0.01% by weight or less, the cohesive force of the pressure-sensitive adhesive is weak, and the pressure-sensitive adhesive is transferred or fibrillation occurs when the initial pressure and peel strength of the pressure-sensitive adhesive are measured. When the content of the tackifying resin is less than 30% by weight, a phenomenon in which the initial adhesive force and peeling strength of the pressure-sensitive adhesive is lowered occurs, and when the content of the tackifying resin is 70% by weight or more, a phenomenon in which the initial adhesive force and peeling strength is lowered also occurs. In addition, the strength of the adhesive (modulus) is high when the peel strength is measured, the mixed fracture occurs.

The pressure-sensitive adhesive obtained according to the production method of the present invention can be prepared with a pressure-sensitive adhesive tape for a photofunctional sheet protective film. At least one side of the pressure-sensitive adhesive tape for protective film has a pressure-sensitive adhesive layer coated with the pressure-sensitive adhesive of the present invention. Although the material of a film is not specifically limited, A polypropylene film is the most preferable. As for the thickness of the adhesive layer apply | coated to a film, 1-50 micrometers is preferable. It is suitable from the standpoint of adhesive force to dry the film to which the adhesive was apply | coated at 50-120 degreeC.

Hereinafter, a specific pressure-sensitive adhesive manufacturing method, examples and comparative examples will be described in detail the configuration and effect of the present invention, these examples are only intended to clearly understand the present invention, it is intended to limit the scope of the present invention no.

The physical properties of the pressure-sensitive adhesive obtained in Examples and Comparative Examples were evaluated in the following manner.

Measurement method of physical properties of the prepared pressure-sensitive adhesive

(a) Initial Tack

The initial adhesive strength of the natural rubber pressure-sensitive adhesive prepared through blending was measured at 20 ° C. and 50% RH using the Texture Analyzer TA-XT2i according to ASTM D2979 using a probe tack test method. The probe is made of stainless steel and 5mm in diameter. After the probe approached the pressure-sensitive adhesive surface, the force when pressed for 1 ^{second at} a pressure of 100 g _f / cm ² and peeled off at a speed of 10 mm / min was measured as the initial adhesive force.

(b) Peel strength

The test plate (adhesive: stainless steel (SUS-304)) thoroughly washed and dried with a solvent is reciprocally attached twice with a 2 kg rubber roller with the adhesive side of the 25 mm wide test piece (sample) facing down. After a certain period of time after adhesion, the adhesive force was measured using a texture analyzer at 20 ° C. and 50% RH at a measurement speed of 300 mm / min.

(c) Mooney viscosity

The Mooney Viscosity of the unvulcanized rubber was measured using a Mooney Viscometer (standard JIS K6300-1) to know the Soviet degree of natural rubber. The Mooney viscometer is capable of measuring Mooney viscosity when varying from 0.1 to 20 rpm to three stages, and measuring Mooney-relaxation generated when the rotor is momentarily stopped after Mooney viscosity measurement. Measurement can be made at a temperature of 50 to 200 ° C.

Example

Preparation of Natural Rubber Solution

Example 1

To 1 kg of natural rubber was added 0.1 phr of the Soviet promoter fatty acid Struktol A 80. After mixing for 10 minutes using a Banbury mixer at room temperature, and then moved to a tubon roll for 10 minutes through the Soviet Union process, dissolved in 4kg of cyclohexane for 24 hours in a 35 ℃ stirred tank to prepare a natural rubber solution (A1) It was. The concentration of the natural rubber solution dissolved in the solvent was 20%.

Mooney viscosity of natural rubber after the Soviet process was measured and shown in Table 1. In addition, the viscosity of the natural rubber solution after dissolving the post-Soviet natural rubber in the solvent was measured and shown in Table 2.

Example 2

0.3 phr of Soviet-promoted fatty acid Struktol A 82 was added to 1 kg of natural rubber. After mixing for 10 minutes using a Banbury mixer at room temperature, and then moved to a tubon roll for 10 minutes through the Soviet Union process, it was dissolved in 48 kg of cyclohexane for 48 hours in a 35 ℃ stirred tank to prepare a natural rubber solution (A2) It was. The concentration of the natural rubber solution dissolved in the solvent was 20%.

Mooney viscosity of natural rubber after the Soviet process was measured and shown in Table 1. In addition, the viscosity of the natural rubber solution after dissolving the post-Soviet natural rubber in the solvent was measured and shown in Table 2.

Example 3

0.5 phr of the Soviet promoter fatty acid Struktol A 86 was added to 1 kg of natural rubber. After mixing for 10 minutes using a Banbury mixer at room temperature conditions, and then moved to a two-bone roll to undergo a Soviet process for 10 minutes, and then dissolved in 4kg of cyclohexane in a 35 ℃ stirred tank for 24 hours to prepare a natural rubber solution (A3) It was. The concentration of the natural rubber solution dissolved in the solvent was 20%.

Mooney viscosity of natural rubber after the Soviet process was measured and shown in Table 1. In addition, the viscosity of the natural rubber solution after dissolving the post-Soviet natural rubber in the solvent was measured and shown in Table 2.

[Table 1] Mooney viscosity of natural rubber

Soviet accelerator content (phr) Mooney Viscosity 0 32 M 0.1 25 M 0.3 20 M 0.5 11 M

[Table 2] Viscosity of natural rubber solution according to dissolution time after Soviet process

Hour (hr)  Viscosity (cps) 24 6000-10000 48 5000-7000

Preparation of Synthetic Rubber Solution

Example 4

Synthetic rubber solution (B1) was prepared by dissolving 2 kg of aliphatic tackifying resin A-1100 and 1 kg of synthetic rubber in 12 kg of a mixed solution of benzene and ethanol. The concentration of the prepared synthetic rubber solution was 20% by weight.

Example 5

2kg of DCPD-based tackifying resin SU-100 and 1kg of synthetic rubber were dissolved in 12kg of a mixed solution of benzene and ethanol to prepare a synthetic rubber solution (B2). The concentration of the prepared synthetic rubber solution was 20% by weight.

Preparation of pressure sensitive adhesive

Example 6

50% by weight of the natural rubber solution (A1) prepared in Example 1 to 50% by weight of the pressure-sensitive adhesive, 50% by weight of synthetic rubber solution (B1) and isocyanate-based curing agent tris (para- isocyanatophenyl) thiophosphate (tris (p-isocyanatophenyl) thiophospahte) was blended at 0.5% by weight. The concentration of the prepared adhesive was 20%.

Example 7

20% by weight of the natural rubber solution (A2) prepared in Example 2, 80% by weight of the synthetic rubber solution (B1) and isocyanate-based curing agent tris (para- isocyanatophenyl) thiophosphate (tris) (p-isocyanatophenyl) thiophospahte) was blended at 0.5% by weight. The concentration of the prepared adhesive was 20%.

Example 8

The natural rubber solution (A3) prepared in Example 1 was 25% by weight based on the weight of the final adhesive, 75% by weight of the synthetic rubber solution (B2), and an isocyanate-based curing agent tris (para-isocyanatophenyl) thiophosphate (tris) (p-isocyanatophenyl) thiophospahte) was blended at 0.5% by weight. The concentration of the prepared adhesive was 20%.

[Comparative Example 1]

10 to 90% by weight of rosin was added to the natural rubber solution (A2) prepared in Example 1 to prepare a pressure-sensitive adhesive having a solid content of 20%.

[Comparative Example 2]

Aliphatic tackifying resin A-1100 and DCPD tackifying resin SU-100 are blended with a natural rubber solution (A2) in a blend ratio of 10 to 90 wt%, respectively, and the content of isocyanate curing agent is fixed at 0.5 wt% relative to the solid content. To prepare an adhesive. The concentration of the pressure-sensitive adhesive prepared by dissolving in a solvent was 20%.

Manufacture of Adhesive Tape for Protective Film

Example 9

The pressure-sensitive adhesive prepared in Examples 6 to 8 is coated on the polypropylene film to 40㎛. The coating film was dried at 70 ° C. to prepare an adhesive tape for a protective film.

[Comparative Example 3]

The pressure-sensitive adhesive prepared in Comparative Example 1 was coated on a polypropylene film at 40 μm. The coating film was dried at 70 ° C. to prepare an adhesive tape for a protective film.

Evaluation of physical properties of the prepared adhesive

1. Probe tack

Figure 1 shows the initial adhesive force change according to the synthetic rubber content of the pressure-sensitive adhesive prepared in Example 6 of the present invention. The initial adhesive strength of the pressure-sensitive adhesive increased with the addition of 20% by weight of synthetic rubber, but it was difficult to express the properties of synthetic rubber at lower contents.

Figure 2 shows the initial adhesive force change curve according to the content of the aliphatic tackifying resin having a softening point of 85 ~ 140 ℃, the content of the tackifying resin showed an almost constant initial adhesive strength value from 30 to 60% by weight, but at 70% by weight The initial adhesive force sharply decreased.

Figure 3 shows the initial adhesive force change curve according to the content of the recipe-based tackifying resin, the initial adhesive force was increased as the content of the tackifying resin was increased, but the initial adhesive strength was sharply dropped at the content of more than 70% by weight. This helps low-molecular-weight tackifying resin to develop adhesive performance up to a certain content, but at higher contents, it increases the modulus of the prepared adhesive, increasing the component of the tackifying resin on the surface of the adhesive, and thus the initial adhesive strength. This is because it cannot be expressed.

Figure 4 shows the initial adhesive force change curve of the pressure-sensitive adhesive prepared in Comparative Example 1 of the present invention. The initial adhesive strength increased up to 30% by weight of rosin, but increased after the decrease, but did not show a constant tendency. This can be interpreted as a result of the reduced rosin structure of the raw rosin, resulting in uneven and low initial cohesion.

2. Peel strength

The peel strength test of an adhesive is a method of measuring the intensity | strength when peeling a film at a fixed speed | rate at a fixed temperature and humidity conditions after attaching an adhesive film to a to-be-adhered adhesive, and intensity | strength changes according to peeling angle, peeling speed, etc. In addition, after peeling, the adhesive may be classified into cohesive failure, interfacail failure, cohesive failure and stick-slip failure, and adhesive failure.

The peeling strength of the adhesive manufactured by the method of Example 6 is shown in FIG. Peel strength increased slightly up to 40% by weight of synthetic rubber, but gradually began to decrease at higher contents. At 80% by weight of synthetic rubber, cohesive and interfacial fractures of the adhesive occurred simultaneously. It was.

In the present invention, it is difficult to constantly adjust the physical properties due to the inherent properties of natural rubber and there is a problem that fibrillation occurs when the natural rubber-based pressure-sensitive adhesive of the compounding ratio obtained above adheres to the adhesion surfaces of the adhesive films and then peels off. A pressure-sensitive adhesive was prepared by mixing a predetermined amount of synthetic rubber in place of natural rubber. As a result, the coating adhesive could be prepared in the protective film applied to the prism sheet and diffusion sheet protective applications having better physical properties in terms of initial adhesive strength and peel strength than when the adhesive was prepared from natural rubber alone.

Claims (5)

(a) a soviet promoter comprising one acid selected from the group consisting of butyric acid, valeric acid, caproic acid, caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid and benzoic acid. Dissolving the rubber in at least one aliphatic organic solvent selected from the group consisting of pentane, hexane, heptane, cyclopentane, cyclohexane, cycloheptane and cyclooctane to prepare a natural rubber solution; (b) dissolving a synthetic rubber and a tackifying resin in a mixed solution of an aromatic organic solvent, such as benzene, toluene or xylene, and an alcoholic organic solvent, such as methanol, ethanol or propanol, to prepare a synthetic rubber solution; And (C) a method of producing a pressure-sensitive adhesive comprising the step of blending by adding a curing agent to the natural rubber solution and synthetic rubber solution. The method of claim 1, wherein the synthetic rubber is a styrene-isoprene-styrene (SIS) -based synthetic rubber having a styrene content of 1 to 30% by weight and a diblock content of 0 to 50% by weight. The method of claim 1, wherein the tackifying resin is an aliphatic hydrocarbon resin or a DCPD resin, and has a softening point of 40 to 150 ° C. (a) a Soviet promoter comprising one acid selected from the group consisting of butyric acid, valeric acid, caproic acid, caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid and benzoic acid Natural rubber solution obtained by soaking natural rubber in at least one aliphatic organic solvent selected from the group consisting of pentane, hexane, heptane, cyclopentane, cyclohexane, cycloheptane and cyclooctane; (b) a synthetic rubber solution obtained by dissolving a synthetic rubber and a tackifying resin in a mixed solution of an aromatic organic solvent of benzene, toluene or xylene and an alcoholic organic solvent of methanol, ethanol or propanol; And (c) isocyanate-based curing agent, In the above, the weight ratio of the natural rubber solution and the synthetic rubber solution is 3 to 9: 1 to 7, the curing agent is an adhesive, characterized in that 0.01 to 1% by weight based on the total weight of the natural rubber solution and synthetic rubber solution. Adhesive tape for photofunctional sheet protective film to which the adhesive of Claim 4 was apply | coated.

Images