KR102266586B1 - Polyurethane-based adhesive capable of controlling adhesion through molecular design and method for manufacturing the same - Google Patents

Abstract

The present invention relates to a polyurethane-based adhesive capable of controlling adhesion through molecular design and a method for manufacturing the same, wherein various adhesive strength can be adjusted according to the selection of a prepolymer and a curing agent, and the adhesive can be used by adjusting adhesive force according to the type and use of various adherends.

Description

Polyurethane-based adhesive capable of controlling adhesion through molecular design and method for manufacturing the same}

The present invention relates to a polyurethane-based pressure-sensitive adhesive and a method for manufacturing the same, and more particularly, to a polyurethane-based pressure-sensitive adhesive capable of controlling adhesive force through molecular design and a method for manufacturing the same, as a result of research by Pusan National University Basic Research Support Project (2 years) to be.

Background to the present disclosure is provided herein, which does not necessarily imply known art.

Adhesive refers to a material that can be easily attached and removed with little force. Adhesives with various adhesive strengths are widely used throughout the industry because of the advantages of repeatable adhesion and easy attachment and detachment. It is widely used in parts that are useful but require easy use and removal by users, such as temporary protective films for electronic devices, coating films for smartphones, and post-it notes for office supplies.

As an adhesive used in the above-mentioned fields, the most important physical properties are the mutual force between the adhesive and the mutual force between the adhesive and the epidermis, aiming to minimize the damage to the epidermis and leave no transfer (residue) when removed after use ( Adequate force balance of adhesive force) is required. According to this demand, it is necessary to develop and study adhesives that can control various adhesive strengths utilizing the wetting characteristics of urethane.

1. Korean Patent No. 10-1784727 (2017.09.28) 2. Korean Patent No. 10-1494660 (2015.02.10)

The present invention is to provide a polyurethane-based pressure-sensitive adhesive that can control the adhesive force and does not leave a transfer (residue) when removed after use and a manufacturing method thereof.

However, the objects of the present invention are not limited to the above-mentioned objects, and other objects not mentioned will be clearly understood by those skilled in the art from the following description.

The present invention provides a step of synthesizing a prepolymer by adding a crosslinking agent to at least two or more polyols, raising the temperature and stirring, and then adding a solvent and a chain extender; and adding a crosslinking agent and a solvent to the synthesized prepolymer and stirring to prepare an adhesive.

In addition, the step of synthesizing the prepolymer includes at least two kinds of polyalkylene polyols having a molecular weight of 200 to 500 and one or more kinds of polyethylene glycol (PEG) having a molecular weight of 600 to 2000. In the step of synthesizing the polyol and the prepolymer, 5 to 17 parts by weight of the polyethylene glycol, 30 to 40 parts by weight of the crosslinking agent, and 45 to 55 parts by weight of the solvent are added based on 100 parts by weight of the polyalkylene polyol. and 3 to 7 parts by weight of the chain extender is added.

In addition, in the step of preparing the pressure-sensitive adhesive, 10 to 20 parts by weight of the crosslinking agent is added based on 100 parts by weight of the prepolymer, and 90 to 110 parts by weight of the solvent is added based on 100 parts by weight of the polyol added in the previous step. do.

In addition, the crosslinking agent introduced in the step of preparing the pressure-sensitive adhesive is characterized in that at least two or more crosslinking agents including one type of aliphatic crosslinking agent and one type of trimer thereof are mixed and added.

In addition, the present invention is an adhesive comprising a structure derived from at least two or more polyols, crosslinking agents and chain extenders, wherein the polyol has at least one polyalkylene polyol having a molecular weight of 200 to 500 and a molecular weight of 600 to It provides a polyurethane-based pressure-sensitive adhesive comprising at least one of 2000 polyethylene glycol (PEG).

In addition, the polyurethane-based pressure-sensitive adhesive is characterized in that it is possible to control the adhesive force by increasing the molecular weight within the molecular weight range of the polyethylene glycol to decrease the adhesive force or to decrease the molecular weight to increase the adhesive force.

In addition, the crosslinking agent includes one type of crosslinking agent and a trimer thereof, and the polyurethane pressure-sensitive adhesive increases the adhesive strength by increasing the content ratio containing the trimer or decreases the content ratio to decrease the adhesive force. is characterized as possible.

According to the present invention, various adhesive strength can be controlled by molecular design by controlling the molecular weight of the polyol and the composition of the crosslinking agent according to the selection of the prepolymer and the curing agent, and the adhesive strength can be adjusted according to the type and use of various adherends. to provide.

1 shows a schematic diagram of controlling the adhesive force through molecular design according to an embodiment of the present invention.
2 shows the structure of a prepolymer according to an embodiment of the present invention.
3 to 8 show the results of measuring the adhesive force of the pressure-sensitive adhesive prepared according to an embodiment of the present invention.
9 shows the transmittance measurement results of the pressure-sensitive adhesive prepared according to an embodiment of the present invention.

All technical and scientific terms used herein have the same meanings as commonly understood by those of ordinary skill in the art, unless otherwise stated. Also throughout this specification and claims, unless stated otherwise, the term comprise, comprises, comprising is meant to include the recited object, step or group of objects, and steps, and any other It is not used in the sense of excluding an object, step, or group of objects or groups of steps.

Prior to describing the present invention in detail below, it is to be understood that the terminology used herein is for the purpose of describing specific embodiments and is not intended to limit the scope of the present invention, which is limited only by the appended claims. shall.

On the other hand, various embodiments of the present invention may be combined with any other embodiments unless clearly indicated to the contrary. Any feature indicated as particularly preferred or advantageous may be combined with any other feature and features indicated as preferred or advantageous. Hereinafter, embodiments of the present invention and effects thereof will be described with reference to the accompanying drawings.

The method for producing a polyurethane-based pressure-sensitive adhesive according to an embodiment of the present invention is a method for preparing an adhesive by further synthesizing a cross-linking agent after synthesizing a prepolymer, adding a cross-linking agent and a catalyst to at least two or more polyols, raising the temperature and stirring, and then a solvent and a chain It includes the step of synthesizing the prepolymer by adding an extender (S1), and adding a crosslinking agent and a solvent to the synthesized prepolymer and stirring to prepare a pressure-sensitive adhesive (S2).

Polyol is an abbreviation of "Polyhydric alcohol", meaning an alcohol having three or more hydroxyl groups (-OH), but propylene oxide (PO) and ethylene oxide ( It refers to a compound that can make urethane by reacting with isocyanate, a compound having an isocyanate group (-NCO) at the end, with a molecular weight of hundreds to thousands by adding Ethylene Oxide (EO).

Polyols are largely classified into polyether polyols and polyester polyols, and can be used by changing the molecular weight of the initiator and the product to suit the intended use.

The step (S1) of synthesizing the prepolymer is a step of synthesizing the prepolymer by adding a crosslinking agent and a catalyst to at least two or more polyols, raising the temperature and stirring, and then adding a solvent and a chain extender. Step (S11) of adding the above polyol, crosslinking agent and catalyst, raising the temperature to 65 °C to 75 °C over 25 to 35 minutes and stirring at 100 rpm to 150 rpm (S12), 15 minutes to 30 minutes after completion of temperature increase When a large amount of air bubbles start to occur in between, the step of adding a solvent (S13), adding a chain extender after 100 to 150 minutes after the solvent is added, and terminating the reaction after 100 to 150 minutes (S14) to synthesize the prepolymer.

The at least two or more polyols include at least one polyalkylene polyol having a molecular weight of 200 to 500 and at least one polyethylene glycol (PEG) having a molecular weight of 600 to 2000.

As the polyalkylene polyol having a molecular weight of 200 to 500, a hydroxyl value (mgKOH/g) of 385 to 415 is used. For example, a KONIX HD-401 from KPX is used.

Polyethylene glycol having a molecular weight of 600 to 2000 can control adhesive strength by adjusting the molecular weight within the above range. A schematic diagram of controlling the adhesive force through molecular design in the present invention is shown in FIG. 1 . As shown in FIG. 1 , as the molecular weight of PEG increases, the number of urethane functional groups per area decreases, thereby reducing adhesion, and as the molecular weight of PEG decreases, the number of urethane functional groups per area increases, thereby increasing adhesion.

The crosslinking agent is an isocyanate compound, hexamethylene diisocyanate (HDI), tetramethylene diisocyanate (Tetramethylene diisocyanate), toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), isophorone and at least one selected from the group consisting of diisocyanate (Isophorone diisocyanate; IPDI), tetramethylxylene diisocyanate (TMXDI), and naphthalene diisocyanate (NDI). Preferably, it is good to include at least one of hexamethylene diisocyanate (HDI) and tetramethylene diisocyanate, which are aliphatic diisocyanates.

The catalyst uses a tin-based catalyst such as dibutyltin dilaurate (DBTDL) and dioctyltin dilaurate (DOTDL).

The solvent is at least one selected from the group consisting of methyl ethyl ketone, acetone, ethyl acetate, tetrahydrofuran, ethanol, dioxane, cyclohexanone, n-hexane, toluene, xylene, n-propanol and isopropanol. do. Preferably, the use of ethyl acetate, tetrahydrofuran or ethanol has a low boiling point, so that evaporation of the solvent may occur easily during drying or aging.

The chain extender is 1,4-butanediol, 1,5-pentanediol, dimethylol butanoic acid (DMBA), ethylene glycol, diethylene glycol, At least one selected from the group consisting of propylene glycol, dipropylene glycol, and isosorbide is used.

The content of the components added in the step (S1) of synthesizing the prepolymer is 5 to 17 parts by weight of polyethylene glycol (PEG) having a molecular weight of 600 to 2000 based on 100 parts by weight of a polyalkylene polyol having a molecular weight of 200 to 500 Parts, 30 to 40 parts by weight of the crosslinking agent, 3 to 7 parts by weight of the catalyst (based on the diluted weight of 25 ppm organic solvent) (S11), 45 to 55 parts by weight of the solvent (S13), 3 to 7 parts by weight of the chain extender A negative input (S14).

The prepolymer synthesized in the step (S1) of synthesizing the prepolymer is cross-linked through a urethane functional group (-NH-CO-O) to the hydroxyl group of the polyalkylene polyol (polyol1) having a molecular weight of 200 to 500, respectively, as shown in FIG. 2 . It has a structure in which a chain extender (CE) and polyethylene glycol (polyol2) having a molecular weight of 600 to 2000 are combined.

The step of preparing the pressure-sensitive adhesive (S2) is a step of preparing the pressure-sensitive adhesive by adding a crosslinking agent and a solvent to the synthesized prepolymer and stirring. More specifically, 10 to 20 parts by weight of the crosslinking agent is added based on 100 parts by weight of the prepolymer, and 90 to 110 parts by weight of the solvent is added based on 100 parts by weight of the polyol used in the previous step, followed by sufficient stirring.

The crosslinking agent input in the step (S2) of preparing the pressure-sensitive adhesive is added by mixing at least two types of crosslinking agents, and the adhesive strength is controlled by adjusting the mixing ratio of the two types of crosslinking agents within the content range. More specifically, the mixed crosslinking agent is a mixture of one aliphatic crosslinking agent and one trimer thereof. For example, a mixture of HDI and HDI trimmer is used. Here, as the ratio of the trimer in the crosslinking agent increases, the number of urethane functional groups per area increases, thereby increasing adhesive strength. However, when the proportion of the trimer is out of the appropriate point, the adhesive strength is improved but the re-adhesiveness disappears. Therefore, the proportion of the trimer within the content range is preferably 25 to 80 wt%, more preferably 40 to 60 wt%.

In another aspect, the polyurethane-based pressure-sensitive adhesive according to an embodiment of the present invention is an pressure-sensitive adhesive having a structure derived from at least two or more types of polyols, crosslinking agents and chain extenders as an adhesive capable of controlling adhesive force through molecular design.

Polyurethane-based pressure-sensitive adhesive according to an embodiment of the present invention can control the adhesive force by designing the molecular structure by adjusting the molecular weight of the included polyol and the composition of the cross-linking agent.

The polyol includes at least one polyalkylene polyol having a molecular weight of 200 to 500 and at least one polyethylene glycol (PEG) having a molecular weight of 600 to 2000.

To increase the molecular weight within the molecular weight range of the polyethylene glycol to decrease the adhesive strength or to decrease the molecular weight to increase the adhesive strength.

In addition, the crosslinking agent includes one type of crosslinking agent and a trimer thereof, and increases the adhesive strength by increasing the content ratio in which the trimer is included or decreases the adhesive strength by decreasing the content ratio.

<Examples and Experimental Examples>

(1) Example A

First, 20 g of KONIX HD-401, 7 g of HDI, 3.33 g of PEG[a], and 1 g of DBTDL (diluted in EA) 1 g were added to the reactor with only cooling water flowing through the reflux system without filling with nitrogen. At this time, the molecular weight of PEG is as shown in Table 1 below. The temperature was gradually raised to 70° C. over 30 minutes and stirred at 120 rpm. When a large amount of bubbles started to occur between 15 and 30 minutes after the completion of the temperature increase, 12cc (10.8g) of Ethyl Acetate was added. 1g of 1,4-BD was added when 2 hours had elapsed after the solvent was added, and the reaction was terminated after 2 hours. In a sealed container at room temperature, bubbles were removed after one day, and the synthesis was completed to prepare a prepolymer. The prepared prepolymer was sealed and stored at room temperature.

Next, EA was added as much as 100 wt% of the base polyol to the prepared prepolymer. [b] wt% of the prepolymer and AH-2100 (HDI TRIMER) were added as much as [c] wt% of the prepolymer here, and the mixture was sufficiently stirred. At this time, the input amounts of HDI and AH-2100 are as shown in Table 1 below. In the sample after the stirring, the pressure-sensitive adhesive was prepared by leaving it until the bubbles disappeared.

- KONIX HD-401: polyoxyalkylene polyol (Hydroxyl value (mgKOH/g) 385~415, viscosity (25℃ cps) 315~415)

- AH-2100: HDI based polyisocyanate (Trimer) (NCO content 21.2±0.7%, viscosity (mPa.s@25℃) 3,000±1,000)

[a] [b] [c] Example A-1 600 5 5 Example A-2 1500 2 8 Example A-3 1500 3.5 6.5 Example A-4 1500 5 5 Example A-5 2000 2 8 Example A-6 2000 3.5 6.5 Example A-7 2000 5 5 Example A-8 2000 15 5

A sample was prepared for measuring the adhesive force of the prepared adhesive (180° Peel Test). After applying the prepared adhesive to a thickness of 15 μm on a PET film having a thickness of 50 μm using an applicator, it was dried in an oven at 120° C. for 2 minutes. After leaving it at room temperature for 30 minutes, it was covered with a silicone release paper having a thickness of 50 μm, and then aged in an oven at 60° C. for 72 hours to obtain a sample having an adhesive. The adhesive force was measured using UTM equipment (width 25 cm, pulling speed 300 mm/min, length 20 cm), and the results are shown in Table 2 and FIG. 3 below.

Max Load(N) Average Load(N) Warrior or not Example A-1 1.246 0.717 X Example A-2 0.835 0.570 X Example A-3 0.600 0.414 X Example A-4 0.355 0.180 X Example A-5 0.862 0.480 X Example A-6 0.625 0.336 X Example A-7 0.298 0.234 X Example A-8 0.046 0.024 X

As shown in Table 2 and Figure 3, it can be seen that the adhesive strength decreases as the molecular weight of PEG increases, and it can be confirmed that the adhesive strength increases as the ratio of the HDI trimer increases. That is, the number of urethane functional groups can be controlled according to the molecular weight of the PEG, and as the number increases, it can be seen that the adhesive strength increases.

(2) Target sample

A polyurethane-based pressure-sensitive adhesive prepared by a conventional method was prepared as a reference for comparison of the physical properties of the pressure-sensitive adhesive according to Examples to be described later. It was confirmed that the polyurethane-based pressure-sensitive adhesive was prepared from the following components.

- Polyol-1: Glycerin + PO (Propylene Oxide) + EO (Ethylene Oxide)

- Polyol-2: PEG (Poly Ethylene Glycol) 600

- Isocyanate: HDI (Hexamethylene Diisocyanate)

- Hardener: HDI biuret-TMP reactant

A sample was prepared for measuring the adhesive force of the prepared polyurethane-based pressure-sensitive adhesive (room temperature/high temperature 180 ° Peel Test). After applying an adhesive to a thickness of 15 μm on a PET film of 50 μm using an applicator, it was dried in an oven at 120° C. for 2 minutes. After leaving it at room temperature for 30 minutes, it was covered with a silicone release paper having a thickness of 50 μm, and then aged in an oven at 60° C. for 72 hours to obtain a sample having an adhesive. UTM equipment (width 25cm, pulling speed 300mm/min, length 20cm) was used, and 2kg, 200mm/min reciprocating attachment (25℃, humidity 70%) to stainless steel and adhesive strength under 20min (room temperature)/30min (150℃) conditions was measured and the results are shown in Table 3 and FIG. 4 below.

room temperature high temperature (150℃) Max
Load(N) Average
Load(N) Max
Load(N) Average
Load(N) target sample 0.046 0.036 4.894 4.872

(3) Example B

First, 20 g of KPX HD-401, 7 g of HDI, 1 g of PEG600, and 1 g of DBTDL 25 ppm (diluted in EA) were added to the reactor in a state where only cooling water was allowed to flow through the reflux system without filling with nitrogen. The temperature was gradually raised to 70° C. over 30 minutes and stirred at 120 rpm. When a large amount of bubbles started to occur between 15 and 30 minutes after the completion of the temperature increase, 12cc (10.8g) of EA was added. The reaction was terminated 2 hours after the solvent was added. In a sealed container at room temperature, bubbles were removed after one day, and the synthesis was completed to prepare a prepolymer. The prepared prepolymer was sealed and stored at room temperature.

Next, EA was added as much as 100 wt% of the base polyol to the prepared prepolymer. [d] wt% of HDI, [e] wt% of prepolymer, and [f] wt% of catalyst, HDI biuret-TMP reaction product of the prepolymer were added here, and the mixture was sufficiently stirred. At this time, the input amounts of HDI, HDI biuret-TMP, and catalyst are as shown in Table 4 below. In the sample after the stirring, the pressure-sensitive adhesive was prepared by leaving it until the bubbles disappeared.

[d] [e] [f] Example B-1 10 - - Example B-2 20 - - Example B-3 10 - 0.1 Example B-4 - 20 - Example B-5 - 10 0.1

A sample was prepared for measuring the adhesive force of the prepared pressure-sensitive adhesive (room temperature/high temperature 180° Peel Test). After applying the prepared adhesive to a thickness of 15 μm on a PET film having a thickness of 50 μm using an applicator, it was dried in an oven at 120° C. for 2 minutes. After leaving it at room temperature for 30 minutes, it was covered with a silicone release paper having a thickness of 50 μm, and then aged in an oven at 60° C. for 72 hours to obtain a sample having an adhesive. UTM equipment (width 25cm, pulling speed 300mm/min, length 20cm) was used, and 2kg, 200mm/min reciprocating attachment (25℃, humidity 70%) to stainless steel and adhesive strength under 20min (room temperature)/30min (150℃) conditions was measured and the results are shown in Table 5 and FIG. 5 (room temperature) and FIG. 6 (high temperature).

room temperature high temperature (150℃) Max
Load(N) Average
Load(N) Max
Load(N) Average
Load(N) target sample 0.046 0.036 4.894 4.872 Example B-1 0.096 0.056 0.172 0.095 Example B-2 0.679 0.280 0.219 0.096 Example B-3 0.352 0.190 19.951 6.041 Example B-4 1.246 0.717 5.560 1.903 Example B-5 0.376 0.253 15.857 8.521

At room temperature, when the amount of the curing agent was increased, the adhesive strength was improved, but there was a problem that a residue remained at a high temperature condition.

(4) Example C

First, 20 g of KPX HD-401, 7 g of HDI, 1 g of PEG600, and 1 g of DBTDL 25 ppm (diluted in EA) were added to the reactor in a state where only cooling water was allowed to flow through the reflux system without filling with nitrogen. The temperature was gradually raised to 70° C. over 30 minutes and stirred at 120 rpm. When a large amount of bubbles started to occur between 15 and 30 minutes after the completion of the temperature increase, 12cc (10.8g) of EA was added. 1g of 1,4-BD was added when 2 hours had elapsed after the solvent was added, and the reaction was terminated after 2 hours. In a sealed container at room temperature, bubbles were removed after one day, and the synthesis was completed to prepare a prepolymer. The prepared prepolymer was sealed and stored at room temperature.

Next, EA was added as much as 100 wt% of the base polyol to the prepared prepolymer. [g] wt% of the prepolymer HDI, [h] wt% of the prepolymer of Aekyung Chemical AH-2100, and [i] wt% of the catalyst as the prepolymer were added and thoroughly stirred. At this time, the input amounts of HDI, AH-2100, and catalyst are as shown in Table 6 below. In the sample after the stirring, the pressure-sensitive adhesive was prepared by leaving it until the bubbles disappeared.

[g] [h] [i] Example C-1 9 One 0.1 Example C-2 8 2 0.1 Example C-3 5 5 0.1 Example C-4 18 2 0.1

A sample was prepared for measuring the adhesive force of the prepared pressure-sensitive adhesive (room temperature/high temperature 180° Peel Test). After applying the prepared adhesive to a thickness of 15 μm on a PET film having a thickness of 50 μm using an applicator, it was dried in an oven at 120° C. for 2 minutes. After leaving it at room temperature for 30 minutes, it was covered with a silicone release paper having a thickness of 50 μm, and then aged in an oven at 60° C. for 72 hours to obtain a sample having an adhesive. UTM equipment (width 25cm, pulling speed 300mm/min, length 20cm) was used, and 2kg, 200mm/min reciprocating attachment (25℃, humidity 70%) to stainless steel and adhesive strength under 20min (room temperature)/30min (150℃) conditions was measured and the results are shown in Table 7 and FIG. 7 (room temperature) and FIG. 8 (high temperature).

room temperature high temperature (150℃) Max
Load(N) Average
Load(N) Max
Load(N) Average
Load(N) target sample 0.046 0.036 4.894 4.872 Example C-1 1.580 0.411 2.641 0.516 Example C-2 0.293 0.102 0.475 0.108 Example C-3 1.056 0.810 5.446 5.368 Example C-4 0.192 0.063 0.372 0.279

As shown in Table 7 and FIGS. 7 and 8, in the case of Example C-3, it can be confirmed that the adhesion is excellent compared to the test sample and no residue is left at high temperature. The transmittance was additionally measured for the sample of Example C-3, and the results are shown in FIG. 9 . As shown in FIG. 9 , it can be seen that the 550 nm transmittance similar to that of the reference sample has high transparency.

Features, structures, effects, etc. exemplified in each of the above-described embodiments may be combined or modified for other embodiments by those of ordinary skill in the art to which the embodiments belong. Accordingly, the contents related to such combinations and modifications should be interpreted as being included in the scope of the present invention.

Claims (8)

synthesizing a prepolymer by adding a crosslinking agent to two or more polyols, raising the temperature and stirring, and then adding a solvent and a chain extender; and
adding a crosslinking agent and a solvent to the synthesized prepolymer and stirring to prepare a pressure-sensitive adhesive;
The method for producing a polyurethane-based pressure-sensitive adhesive, characterized in that the cross-linking agent added in the step of preparing the pressure-sensitive adhesive is added by mixing two or more cross-linking agents including one type of aliphatic cross-linking agent and one type of trimer thereof.
delete According to claim 1,
The step of synthesizing the prepolymer is a step of adding two or more types of polyols including at least one type of polyalkylene polyol and at least one type of polyethylene glycol (PEG),
Based on 100 parts by weight of the polyalkylene polyol, 5 to 17 parts by weight of the polyethylene glycol, 30 to 40 parts by weight of the crosslinking agent, 45 to 55 parts by weight of the solvent, and 3 to 7 parts by weight of the chain extender are added A method for producing a polyurethane-based pressure-sensitive adhesive, characterized in that the input by weight.
According to claim 1,
In the step of preparing the pressure-sensitive adhesive, 10 to 20 parts by weight of the crosslinking agent is added based on 100 parts by weight of the prepolymer, and 90 to 110 parts by weight of the solvent is added based on 100 parts by weight of the polyol added in the previous step. A method for manufacturing a polyurethane-based adhesive.
delete a structure derived from at least two polyols, a crosslinking agent and a chain extender;
The polyol includes at least one polyalkylene polyol and at least one polyethylene glycol (PEG),
The crosslinking agent is a polyurethane-based pressure-sensitive adhesive comprising at least two crosslinking agents including one type of aliphatic crosslinking agent and one type of trimer thereof.
delete 7. The method of claim 6,
The polyurethane-based pressure-sensitive adhesive is a polyurethane-based pressure-sensitive adhesive, characterized in that it is possible to control the adhesive strength by increasing the content ratio in which the trimer is included to increase the adhesive strength or to reduce the adhesive strength by decreasing the content ratio.

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