CN111527174B

CN111527174B - Hot melt adhesive composition

Info

Publication number: CN111527174B
Application number: CN201880083866.XA
Authority: CN
Inventors: 朴容秀; 金泰润; 李镛满; 柳真英
Original assignee: LG Chem Ltd
Current assignee: LG Chem Ltd
Priority date: 2017-12-27
Filing date: 2018-12-10
Publication date: 2022-04-12
Anticipated expiration: 2038-12-10
Also published as: CN111527174A; WO2019132320A1

Abstract

The present disclosure relates to a hot melt adhesive composition. The hot melt adhesive compositions of the present disclosure retain low viscosity characteristics and thus can be melt processed at relatively low temperatures and improve processability. In addition, the composition is excellent in adhesion and heat resistance, and in mechanical properties after curing, and thus can be used in various industrial fields.

Description

Hot melt adhesive composition

Technical Field

Cross Reference to Related Applications

This application claims the rights and interests of korean patent application No. 10-2017-.

The present disclosure relates to a hot melt adhesive composition.

Background

A hot melt adhesive is an adhesive that forms an adhesive surface using a thermoplastic resin that melts when heated. Unlike conventional UV curable adhesives, hot melt adhesives are preferred as environmentally friendly high functional adhesives because they do not use volatile solvents or the like and thus the amount of harmful substances during curing is small.

Not only is the hot melt adhesive relatively inexpensive as compared with the UV curable adhesive, but it exists in a liquid state at high temperature, thereby being applied to a substrate or an adherend to promote pressure bonding, and then, it is easy to use since it exhibits adhesion when it cools and solidifies at room temperature within a few seconds.

The hot melt adhesive contains a thermoplastic polymer as a base resin, and usually a tackifier, a viscosity modifier, or the like is added thereto.

As the base resin, an olefin copolymer, an unsaturated aromatic elastic copolymer, and the like, which have excellent flexibility and low unit price, are widely used.

Since such a hot melt adhesive is applied to an adherend in a molten state and then cooled to form a hard phase having cohesion, creep resistance, and the like, it is widely used in various industrial fields such as diapers, feminine hygiene products, or pressure-sensitive adhesive tape adhesives for electronic applications such as industrial tapes, packaging tapes, and structural materials, and the like.

Since the hot melt adhesive contains a base resin and additives, etc., phase separation and bleeding may occur due to compatibility and other reasons, which may cause a problem of reduced adhesion. In addition, it has a high viscosity, and thus relatively high temperature conditions are required for adhesion during melt processing, and particularly, problems such as viscosity change, odor generation, and discoloration may occur under such processing temperature conditions, whereby the demand for low viscosity products having a relatively low melting temperature is increasing.

However, a low-viscosity hot melt adhesive capable of low-temperature processing has low viscosity retention, which tends to cause a decrease in adhesive force. Further, there is a problem in that it has low heat resistance such as softening point.

Therefore, there is a need to develop a hot melt adhesive that can maintain low viscosity characteristics and improve processability, while being excellent in adhesion and heat resistance and in mechanical properties after curing.

Disclosure of Invention

[ problem ] to provide a method for producing a semiconductor device

An object of the present disclosure is to provide a hot melt adhesive composition having a low viscosity characteristic and thus being melt-processable at a relatively low temperature and improving processability, while being excellent in adhesion and heat resistance and in mechanical properties after curing.

[ technical solution ] A

In one aspect of the present disclosure, there is provided a hot melt adhesive composition comprising:

A) a styrene-butadiene-styrene triblock copolymer having:

a1) a content of a styryl unit of 30 to 50% by weight,

a2) a diblock content of 55 wt.% or more, and

a3) a melt flow index of 30g/10min or more as measured according to ASTM D1238,

B) a tackifier; and

C) a plastic oil, which is a mixture of a plastic oil,

wherein the hot melt adhesive composition has a softening point of 75 ℃ or greater as measured according to ASTM D36.

In another aspect of the present disclosure, there is provided an adhesive member including:

a substrate; and

an adhesive layer formed on at least one surface of the substrate and formed from the hot melt adhesive composition.

[ PROBLEMS ] the present invention

The hot melt adhesive composition according to the present disclosure maintains low viscosity characteristics, and thus can be melt-processed at a relatively low temperature and improve processability, while being excellent in adhesion and heat resistance and in mechanical properties after curing, and thus can be used in various industrial fields.

Detailed Description

A hot melt adhesive composition according to one aspect of the present disclosure comprises:

A) a styrene-butadiene-styrene triblock copolymer having:

a1) a content of a styryl unit of 30 to 50% by weight,

a2) a diblock content of 55 wt.% or more, and

a3) a melt flow index of 30g/10min or more as measured according to ASTM D1238,

B) a tackifier; and

C) a plastic oil, which is a mixture of a plastic oil,

Also, according to one embodiment of the present disclosure, the melt viscosity of the hot melt adhesive composition at 120 ℃ may be about 5500cPs or less, preferably about 5200cPs or less, or about 4500cPs to about 5200cPs, and at the same time, the rate of change of the viscosity may be about 10% or less.

Also, according to another embodiment of the present disclosure, the melt viscosity of the hot melt adhesive composition at 160 ℃ may be about 800cPs or less, preferably about 750cPs or less, or about 650cPs to about 750cPs, and at the same time, the rate of change of the viscosity may be about 10% or less.

Further, the hot melt adhesive composition may have a tensile strength value of about 0.35N/mm when the test specimens are prepared according to ASTM D638²Above, preferably about 0.4N/mm²Above, more preferably about 0.5N/mm²To about 0.6N/mm²。

Further, the tackifier contained in the hot melt adhesive composition may include any one or more of an at least partially hydrogenated rosin ester-based compound and an at least partially hydrogenated dicyclopentadiene-based polymeric petroleum resin.

In addition, the tackifier may be contained in an amount of about 200 parts by weight to about 400 parts by weight, or about 250 parts by weight to about 350 parts by weight, or about 270 parts by weight to 330 parts by weight, based on 100 parts by weight of the styrene-butadiene-styrene triblock copolymer.

The plastic oil may include petroleum-based mineral oil.

In addition, the plastic oil may be contained in an amount of about 50 parts by weight to about 150 parts by weight, based on 100 parts by weight of the styrene-butadiene-styrene triblock copolymer.

Meanwhile, according to another aspect of the present disclosure, there is provided an adhesive member including:

a substrate; and

At this time, the thickness of the adhesive layer may be about 10 μm to about 100 μm, preferably about 30 μm to about 70 μm.

Further, the adhesive member has a T-peel strength value of 10N/in or greater, preferably from about 10N/in to about 15N/in, or from about 10N/in to about 12N/in, measured according to ASTM D1876.

The terms "first," "second," and the like, are used herein to describe various elements and are used merely to distinguish one element from another.

Furthermore, the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. Unless expressly stated otherwise, singular expressions include plural expressions. It will be understood that the terms "comprises," "comprising," and "having," as used herein, are intended to specify the presence of stated features, integers, steps, components, or groups thereof, but should be understood to not preclude the presence or addition of one or more other features, integers, steps, components, or groups thereof.

Further, in the present disclosure, in the case where it is mentioned that a layer or an element is formed "on" or "over" another layer or element, it means that the layer or element is directly formed on the another layer or element, or that the another layer or element may be additionally formed between layers or on an object or substrate.

In the present disclosure, in the styrene-butadiene-styrene triblock copolymer, the diblock content refers to the content of the copolymer that remains as a styrene-butadiene diblock without being coupled during the preparation of the styrene-butadiene-styrene triblock copolymer by the coupling reaction with the styrene-butadiene block copolymer.

That is, the styrene-butadiene-styrene triblock copolymer described herein may have a form in which the polymerization reaction and the coupling reaction completely proceed so as to include only the styrene-butadiene-styrene triblock, and it may be in the form of a mixture including the styrene-butadiene-styrene triblock, the above diblock, and unreacted monomers.

Further, the content of the diblock in the triblock copolymer refers to a ratio (wt%) of a styrene-butadiene diblock contained therein with respect to the total weight (100 wt%) measured by GPC or the like of the molecular weight distribution of the copolymer.

The present disclosure is susceptible to various modifications and forms, and specific embodiments thereof are shown and described in detail below. It should be understood, however, that the disclosure is not intended to be limited to any particular form disclosed, but to include all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

In general, it is very important that the hot melt adhesive composition secures physical properties related to adhesion, such as adhesion, adhesion holding power, and peel strength, depending on its use and properties. These physical properties vary greatly depending on the components of the thermoplastic resin, i.e., the base resin, contained in the hot melt adhesive composition.

When an olefin copolymer having low polarity is used, it is difficult to secure sufficient adhesion, when a thermoplastic elastic copolymer or the like is used, viscosity is high and workability may be reduced, and when an amorphous α -olefin copolymer or the like is used, there are disadvantages in that cohesion is low and workability is also poor.

In the case of a styrenic copolymer, heat resistance is excellent and viscosity is relatively low, whereby processability is also excellent, and it has an excellent advantage with other components such as a tackifier or a plasticizer (oil) used together. Among them, a styrene-butadiene-styrene triblock copolymer is most preferable.

However, these physical properties may vary depending on the structural characteristics of the styrene-butadiene-styrene triblock copolymer.

From this viewpoint, the styrene-butadiene-styrene triblock copolymer used in the hot melt adhesive composition according to one aspect of the present disclosure has:

a1) a content of a styryl unit of 30 to 50% by weight,

a2) a diblock content of 55 wt.% or more, and

a3) a melt flow index of 30g/10min or more measured according to ASTM D1238.

First, the styrene-butadiene-styrene triblock copolymer may have a styrene-based unit content of 30 to 50 wt%, preferably about 35 to about 50 wt%, more preferably about 45 to about 50 wt%.

Since the styrene-based monomer has a glass transition temperature (Tg) value higher than room temperature, it forms a hard segment unit having relative rigidity during polymerization of the copolymer. Butadiene-based monomers have a glass transition temperature value below room temperature and thus form soft segment units with relative flexibility during polymerization of the copolymer.

In view of these properties, when the content of the styrene-based unit derived from the styrene-based monomer is too low, the hardness of the hot melt adhesive composition is reduced, which may cause a problem of reduction in heat resistance. In addition, there may be a problem of deterioration of mechanical properties after adhesion and curing.

Also, when the content of the styrene-based unit derived from the styrene-based monomer is excessively high, the hardness of the hot melt adhesive composition is increased and the viscosity is also increased, which may cause problems of decreased processability and decreased adhesive force.

In addition, the styrene-butadiene-styrene triblock copolymer may have a diblock content of 55 wt% or more, preferably about 60 wt% or more, and more preferably from about 60 wt% to about 65 wt%.

In the above styrene-butadiene-styrene triblock copolymer, when the styrene-butadiene diblock content satisfies the above range, a phenomenon of viscosity reduction can be clearly confirmed, and since the tackiness is increased, the adhesive force can be improved.

Further, in order to impart a high softening point and high fluidity when preparing a hot melt adhesive composition, it is generally necessary to use polyolefin-based additives or increase the content of these additives, but in this case, there may be a problem that physical properties other than viscosity are changed. On the other hand, in the case of the present disclosure, by using the above-mentioned styrene-butadiene-styrene triblock copolymer, there is an advantage in that physical properties such as viscosity can be easily adjusted while other physical properties are not changed.

Further, the styrene-butadiene-styrene triblock copolymer may have a melt flow index of 30g/10min or more, preferably from about 40g/10min to about 50g/10min, or from about 45g/10min to about 50g/10min, as measured according to ASTM D1238.

Therefore, when the melt flow index of the styrene-butadiene-styrene triblock copolymer as the base resin of the hot melt adhesive composition falls within the above range, the low temperature fluidity of the hot melt adhesive composition is improved, and the adhesive force and the cohesive force are improved, whereby excellent processability can be achieved even at a relatively low temperature.

Further, according to one embodiment of the present disclosure, the melt viscosity of the hot melt adhesive composition at 120 ℃ may be about 5500cPs or less, preferably about 5200cPs or less, or about 4500cPs to about 5200cPs, at which time the rate of change of the viscosity may be about 10% or less.

According to another embodiment of the present disclosure, the melt viscosity of the hot melt adhesive composition at 160 ℃ may be about 800cPs or less, preferably about 750cPs or less, or about 650cPs to about 750cPs, in which case the rate of change of the viscosity may also be about 10% or less.

As described above, the hot melt adhesive composition according to one embodiment of the present disclosure has a relatively low viscosity characteristic, and the viscosity hardly changes even after aging, and thus can be melt-processed at a low temperature, and thus can have excellent adhesive force and heat resistance even while improving processability, and further achieve excellent characteristics of mechanical properties after curing.

Specifically, when a hot melt adhesive composition according to one embodiment of the present disclosure is melted and a cured specimen in a form conforming to the ASTM D638 standard is prepared, it may have a tensile strength value as described above.

The tensile strength value is a physical property that may represent durability and physical stability of an adhesive surface when the adhesive is used to form the adhesive surface, and the hot melt adhesive composition according to one embodiment of the present disclosure has the above tensile strength value, whereby excellent adhesion durability may be achieved.

Here, rosin is used as a concept including all rosin acids, dehydroabietic acid in which hydrogen is removed from rosin acid, and dihydro or tetrahydro rosin acid to which 2 or 4 hydrogens are added. Abietic acid and dihydroabietic acid to which 2 hydrogens are added are used as concepts including various isomers according to the position of the double bond.

In the case of dehydroabietic acid, it may be represented by the following chemical formula,

that is, dehydroabietic acid has the most stable form of the above rosin compound in which two hydrogens are removed and an aromatic ring is formed in the abietic acid structure containing two double bonds.

In the case of rosin acid, it can be regarded as a basic form of a rosin compound, which can be represented by the following chemical formula.

That is, rosin acid has a stable form in which two double bonds are conjugated in a tricyclic compound, and a unique color is exhibited by such conjugated double bonds. Further, in rosin acid, the position of the double bond can be easily changed in the above structure, which enables it to have various isomer forms. These isomers also mostly have conjugated double bonds and thus have a unique color.

In the case of dihydroabietic acid, two hydrogens are added to the above abietic acid isomers to have only one double bond in the molecule. The position of the double bond may vary depending on the isomer structure of the rosin acid before hydrogenation.

Further, in the case of tetrahydroabietic acid in which four hydrogens are added to abietic acid, the hydrogens are added to all double bonds to have a saturated aliphatic tricyclic form, thereby having high stability and exhibiting no color, as compared with abietic acid derivatives having double bonds.

Further, in the case of rosin acid, it can be regarded as a basic form of a rosin compound, which can be represented by the following chemical formula.

That is, rosin acids can have a stable form in which two double bonds are conjugated in a tricyclic compound. The position of the double bond can be easily changed, thereby having various isomer forms, which also have conjugated double bonds.

Further, the rosin ester-based compound mentioned herein is a rosin ester-based compound esterified by reacting a carboxyl group of a rosin acid with an OH group of an alcohol or a polyol based on the structure of the above rosin acid or hydrogenated rosin acid, and also includes all esterification products of natural or modified rosins. The alcohol or polyol is, for example, an aliphatic alcohol having 1 to 20 carbon atoms, and may be in the form of a monohydric alcohol, a glycol, a triol, a tetraol, or a pentaol. More specifically, it may be, for example, methanol, ethanol, glycerol, ethylene glycol, diethylene glycol, or pentaerythritol. When a polyol is used, the rosin acid can cause an esterification reaction with all or a portion of the hydroxyl groups of the polyol, which results in the formation of a multivalent ester, such as a mono-, di-, tertiary-or quaternary ester.

In the tackifier used in the present disclosure, the rosin ester-based compound containing at least partial hydrogenation may be interpreted as having to contain at least one selected from the group consisting of the above-mentioned rosin acid, dihydroabietic acid, and tetrahydroabietic acid.

Also, the dicyclopentadiene-based polymeric petroleum resin means C5 produced as a byproduct in a naphtha cracking process that decomposes crude oil at high temperature to obtain naphtha, i.e., a petroleum resin containing C9-dicyclopentadiene produced from cyclopentadiene oil.

Cyclopentadiene produced in the naphtha cracking process dimerizes and exists as a dicyclopentadiene structure in most cases. Cyclopentadiene and dicyclopentadiene, which is a dimer thereof, can be converted into each other by a diels-alder reaction and a retro diels-alder reaction, and particularly, cyclopentadiene can be polymerized into dicyclopentadiene by thermal polymerization or catalytic polymerization.

Thus, "a tackifier used herein includes an at least partially hydrogenated dicyclopentadiene-based polymeric petroleum resin" may refer to both dicyclopentane and dicyclopentadiene including addition of hydrogen to dicyclopentadiene which is at least a part of the dicyclopentadiene-based compound contained in the above-mentioned dicyclopentadiene-based polymeric petroleum resin.

According to one embodiment of the present disclosure, the tackifier may be contained in an amount of about 200 parts by weight to about 400 parts by weight, based on 100 parts by weight of the styrene-butadiene-styrene triblock copolymer.

When the content of the tackifier is too small, the tackifying effect is insufficient, and in the hot melt adhesive composition, there may be a problem that the physical properties related to cohesion and adhesion cannot be sufficiently expressed. When the content of the tackifier is too large, the cohesive force of the adhesive component may be reduced, which may cause a problem that physical properties related to adhesion are also deteriorated.

Further, the plastic oil contained in the hot melt adhesive composition may include petroleum-based mineral oil.

Petroleum-based mineral oils are liquid by-products, also known as liquid paraffins, produced in the process of refining crude oil into petroleum. There are generally paraffin oil based on n-paraffin, naphthenic oil based on naphthene, and aromatic oil based on aromatic hydrocarbon, and in the present disclosure, petroleum-based mineral oil is a concept including both the above-described oil and modified oil thereof.

According to one embodiment of the present disclosure, the petroleum-based mineral oil is preferably a paraffin oil, and white oil modified by hydrogen treatment and/or dewaxing in the presence of a catalyst, and the like may be more preferable.

Specifically, the paraffin oil modified by the hydrotreating and/or dewaxing treatment may include at least one selected from the group consisting of a hydrotreated heavy paraffin distillate (CAS registry number 64742-54-7) or a hydrotreated light paraffin distillate (CAS registry number 64742-55-8), a solvent dewaxed heavy paraffin distillate (CAS registry number 64742-65-0), a solvent dewaxed light paraffin distillate (CAS registry number 64742-56-9), a hydrotreated and dewaxed heavy paraffin distillate (CAS registry number 91995-39-0), and a hydrotreated and dewaxed light paraffin distillate (CAS registry number 91995-40-3), but the present disclosure is not necessarily limited thereto.

Further, the plastic oil may be contained in an amount of about 50 parts by weight to about 150 parts by weight, or about 70 parts by weight to about 130 parts by weight, or about 90 parts by weight to about 110 parts by weight, based on 100 parts by weight of the styrene-butadiene-styrene triblock copolymer. When the plastic oil content is too low, there may be a problem that fluidity and low-temperature processability are reduced, and when the plastic oil content is too large, there may be a problem that viscosity is excessively increased and adhesive properties are rather deteriorated.

Further, the hot melt adhesive composition according to an embodiment of the present disclosure may further include known additives such as a light stabilizer, a filler, an antioxidant, and an ultraviolet absorber, as needed.

These additives may be contained in an amount of about 0.1% by weight to about 10% by weight with respect to the entire composition from the viewpoint of preventing deterioration of adhesive properties, processability and mechanical properties after adhesion.

Meanwhile, according to an embodiment of the present disclosure, there is provided an adhesive member including:

a substrate; and

The adhesive member may be in the form of a film, a tape, or the like, and the substrate may be a film having a single layer or a layered structure of two or more layers.

The substrate film may be made of paper, glass or a non-woven material, but is preferably a plastic material. These plastic materials are not particularly limited, and examples thereof include polyesters such as polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, or polybutylene naphthalate; polyolefins such as polyethylene, polypropylene or ethylene-propylene copolymers; polyvinyl alcohol; polyvinylidene chloride; polyvinyl chloride; vinyl chloride-vinyl acetate copolymers; polyvinyl acetate; a polyamide; a polyimide; celluloses such as triacetyl cellulose, diacetyl cellulose, and the like; a fluorine-based resin; a polyether; a polyether amide; polyether ether ketone; polyphenylene sulfide; polystyrenic resins such as polystyrene; a polycarbonate; polyether sulfone; acrylic resins such as polymethyl methacrylate and the like. Further, the above materials may be used alone or in combination of two or more.

Among them, in view of plastic strength, workability, cost, dimensional stability and optical properties, polyester, cellulose, acrylic resin and the like may be preferable.

Further, the thickness of the adhesive layer may be about 10 μm to about 100 μm, preferably about 30 μm to about 70 μm.

According to one embodiment of the present disclosure, the adhesive member may have excellent adhesion, in which a peel strength, i.e., a T-type peel strength value according to ASTM D1876 standard, is about 10N/in or more, preferably about 10N/in to about 15N/in, or about 10N/in to about 12N/in.

Hereinafter, the action and effect of the present disclosure will be described in more detail by specific examples. However, these examples are presented for illustrative purposes only, and are not intended to thereby determine the scope of the present disclosure.

< example >

Styrene-butadiene-styrene triblock copolymers

Preparation of example 1

To the high pressure reactor was added 5000 grams of cyclohexane and 400 grams of styrene, followed by raising the temperature of the reactor to about 60 ℃ while stirring at about 400 rpm.

As catalyst, 50g of n-butyllithium (3% by weight in cyclohexane) were added at about 5kgf/cm²While the temperature is raised to about 130 c under pressure.

Approximately 5 minutes after the reaction temperature reached 130 ℃, the reaction mixture was cooled to 60 ℃ and 700 g of butadiene were added while maintaining this temperature. At about 5kgf/cm²While the temperature is again raised up to 130 c under pressure, the polymerization is carried out.

When the condensation temperature showed the highest temperature, the butadiene reaction was judged to be terminated similarly to the styrene reaction. About 5 minutes after the reaction temperature reached 130 ℃, a coupling agent (KA-22, manufacturer: Shin-Etsu) was added in the same equivalent weight as that of n-butyllithium, and the reaction was further carried out for 5 minutes, thereby preparing a triblock copolymer.

The reaction was then quenched by the addition of about 0.1 g of water.

Preparation of example 2

A styrene-butadiene-styrene triblock copolymer, Globalprene 3545(LCY Chemical Corp.) was prepared.

Preparation of example 3

A styrene-butadiene-styrene triblock copolymer, Asaprene T-439(Asahi Kasei) was prepared.

Preparation of example 4

A styrene-butadiene-styrene triblock copolymer, Taipol 4230(TSRC Corp.) was prepared.

Preparation of example 5

A styrene-butadiene-styrene triblock copolymer, Taipol 4270(TSRC Corp.) was prepared.

The characteristics of the styrene-butadiene-styrene triblock copolymers of the preparation examples are summarized in table 1 below.

[ TABLE 1 ]

Preparation of Hot melt adhesive compositions

To a1 liter glass beaker was added white mineral oil kaydol (sonneborn) as a plastic oil, hydrogenated dicyclopentadiene polymerized petroleum resin Escorez 5600(ExxonMobil) as a tackifier, Irganox 1010 as an antioxidant, Irgafos 168 as a stabilizer, and Tinuvin P (BASF above) as an ultraviolet absorber, followed by heating in a convection oven at 150 ℃ for about 30 minutes. Then, the glass beaker was fixed to a heating jacket at 150 ℃ and stirred at 100 rpm. After the temperature inside the beaker reached 150 ℃, the speed was increased to 150rpm, followed by further stirring.

The styrene-butadiene-styrene triblock copolymer of the preparation example was slowly added dropwise thereto, followed by stirring at 200rpm for 4 hours to completely dissolve the styrene-butadiene-styrene triblock copolymer, thereby preparing a hot melt adhesive composition.

The composition of the hot melt adhesive composition is shown in table 2 below.

[ TABLE 2 ]

Preparation of adhesive Member

The hot melt adhesive compositions of examples and comparative examples were heated at 180 ℃ for about 5 minutes to ensure melting, coated on a coating machine at 180 ℃ onto a PET substrate having a thickness of 25 μm, and then coated using a doctor blade to give an adhesive layer having a thickness of 50 μm. The same PET substrate was simultaneously bonded as a cover film to prepare an adhesive member.

Test examples

Measurement of viscosity

Approximately 10 grams of the hot melt adhesive composition was added to the sample chamber and the viscosity was measured using a Brookfield viscometer (model DV2+, spindle number 27) for 30 minutes at 120 ℃ and 160 ℃.

Subsequently, the hot melt adhesive composition was allowed to stand under the same conditions for 24 hours, and then the viscosity was measured by the same method to calculate the viscosity reduction rate (correlation standard: ASTM D4402).

Measurement of softening Point

The hot melt adhesive composition was sufficiently put into a ring using an automatic softening point analyzer model RB 365G and allowed to stand for 1 hour, and then a ball (diameter: 9.525mm, weight: 3.5G) was placed thereon. The temperature at which the ball sags 1 inch was measured by heating the sample while increasing the temperature at a rate of 5 deg.C/min (correlation standard: ASTM D36).

Measurement of adhesive Properties

The adhesive force of the adhesive member prepared above was measured in a T-peel manner using a Texture Analyzer (TA). The adhesive member sample was cut into a width of 1 inch and a length of 100 mm, and measured at room temperature at 0.3m/min (correlation standard: ASTM D1876).

Measurement of tensile Strength

After melting the hot melt adhesive composition, test specimens were prepared according to ASTM D638 Type-IV standard, and the tensile strength was measured (relevant standard: ASTM D638).

The measured values are summarized in table 3 below.

[ TABLE 3 ]

	Unit of	Example 1	Example 2	Comparative example 1	Comparative example 2
						Adhesive performance	N/in	11	11.2	12.2	11.4
Softening point	℃	80.8	79.7	74.2	74.2
						Viscosity (120 ℃ C.)	cPs	4863	5000	4012	5938
Rate of decrease in viscosity (120 ℃,24h)	％	2.1	2.3	8.6	5.3
						Viscosity (160 ℃ C.)	cPs	731	732.5	715	980
Rate of decrease in viscosity (160 ℃,24h)	％	7.2	7.6	14	9.2
						Tensile strength	N/mm²	0.52	0.55	0.3	0.38

Referring to table 3, it can be seen that in the case of the hot melt adhesive composition according to the examples of the present disclosure, it has a higher softening point and a lower viscosity characteristic than the comparative example.

Further, it can be clearly seen that at a temperature of about 120 ℃ or about 160 ℃ which is regarded as a use temperature of the general-purpose adhesive, the viscosity change is very small, whereby excellent adhesion stability can be achieved. Meanwhile, the tensile strength value is improved by about 40% or more compared to the comparative example, and thus the adhesive surface is expected to have excellent durability and mechanical properties.

Claims

1. A hot melt adhesive composition comprising:

A) a styrene-butadiene-styrene triblock copolymer having:

a1) a content of a styryl unit of 30 to 50% by weight,

a2) a diblock content of 55 wt.% or more, and

a3) a melt flow index of 40g/10min to 50g/10min as measured according to ASTM D1238,

B) a tackifier; and

C) a plastic oil, which is a mixture of a plastic oil,

wherein the tackifier is contained in an amount of 200 to 400 parts by weight, based on 100 parts by weight of the styrene-butadiene-styrene triblock copolymer,

wherein the plastic oil is contained in an amount of 50 to 150 parts by weight, based on 100 parts by weight of the styrene-butadiene-styrene triblock copolymer,

wherein the hot melt adhesive composition has a softening point of 75 ℃ or higher as measured according to ASTM D36,

wherein the hot melt adhesive composition has a melt viscosity of 5500cPs or less at 120 ℃ and a rate of change in the viscosity of 10% or less,

wherein the hot melt adhesive composition has a melt viscosity of 800cPs or less at 160 ℃ and a rate of change in the viscosity of 10% or less,

wherein the melt viscosity is obtained as follows: the viscosities at 120 ℃ and 160 ℃ were measured for 30 minutes using a Brookfield DV2+ model viscometer with spindle number 27,

wherein the rate of change of viscosity is obtained as follows: the hot melt adhesive composition was allowed to stand under the same conditions for 24 hours, and then the viscosity was measured by the same method to calculate the rate of change in viscosity.

2. The hot melt adhesive composition of claim 1, wherein the tensile strength value is 0.35N/mm when the test specimens are prepared according to ASTM D638 standard²The above.

3. The hot melt adhesive composition according to claim 1, wherein the tackifier comprises any one or more of an at least partially hydrogenated rosin ester-based compound and an at least partially hydrogenated dicyclopentadiene-based polymeric petroleum resin.

4. The hot melt adhesive composition of claim 1, wherein the plastic oil comprises a petroleum-based mineral oil.

5. An adhesive member comprising:

a substrate; and

an adhesive layer formed on at least one surface of the substrate and formed from the hot melt adhesive composition of claim 1.

6. The adhesive member according to claim 5, wherein the thickness of the adhesive layer is 10 μm to 100 μm.

7. The adhesive member according to claim 5, wherein a T-peel strength value according to ASTM D1876 is 10N/in or more.