KR102842765B1 - Hot-melt adhesive composition - Google Patents

Abstract

The present invention relates to a hot melt adhesive composition comprising an amorphous polyalpha olefin and an ethylene-propylene copolymer, wherein the ethylene-propylene copolymer is characterized in that the ethylene content is 35 to 55 mol%.

Description

Hot-melt adhesive composition

The present invention relates to a hot melt adhesive composition having excellent adhesive properties, low-temperature flexibility and heat resistance, and having high viscosity, making it suitable for automobiles or woodworking applications.

Hot melt adhesives are adhesives that melt with heat, are applied to the adherend, and then cool and solidify by releasing heat to the surface and surroundings of the adherend to form an adhesive. Compared to other adhesives, they are economical, bond very quickly, and are environmentally friendly adhesives that do not contain solvents.

Amorphous poly alpha olefin (APAO), a type of hot melt adhesive, is primarily used for assembling components for automobiles, filters, furniture, batteries, and other applications. Its wide softening point distribution allows it to be applied in applications requiring both cold and heat resistance. Its odorlessness also makes it suitable for applications such as air filters. Its adhesion to nonpolar surfaces, such as polyethylene and polypropylene, is particularly superior to that of other resins.

Conventional general-purpose APAO hot melt adhesives are typically composed of an amorphous polyalphaolefin as a base resin and wax or the like added as a tackifier or viscosity modifier. However, when the tackifier and wax are mixed with an amorphous polyalphaolefin resin, the adhesive strength and heat resistance are improved, but there is a disadvantage in that low-temperature flexibility is reduced.

Accordingly, there is a need to develop a hot melt adhesive that can maintain excellent heat resistance while improving adhesion and low-temperature flexibility.

Meanwhile, a similar prior art document on this subject is presented in Korean Patent Publication No. 10-1174019.

Republic of Korea Patent Publication No. 10-1174019 (August 8, 2012)

In order to solve the above problems, the present invention aims to provide a hot melt adhesive composition having improved adhesive properties and low-temperature flexibility, while maintaining a softening point and thus having excellent heat resistance and high viscosity, making it suitable for automobiles or woodworking applications.

However, the above purpose is exemplary, and the technical idea of the present invention is not limited thereto.

One aspect of the present invention for achieving the above object relates to a hot melt adhesive composition comprising an amorphous polyalpha olefin and an ethylene-propylene copolymer, wherein the ethylene-propylene copolymer is characterized in that the ethylene content is 35 to 55 mol%.

In the above aspect, the hot melt adhesive composition may have a weight ratio of amorphous poly alpha olefin: ethylene-propylene copolymer of 100:1 to 30.

In the above aspect, the amorphous polyalpha olefin may have a melting viscosity of 1,000 to 200,000 cps at 190°C, a softening point of 130°C or higher, a glass transition temperature of -10°C or lower, and a needle penetration degree of 45 dmm or lower.

In the above aspect, the ethylene-propylene copolymer may have a number average molecular weight (Mn) of 20,000 to 50,000 g/mol and a viscosity at 190°C of 10,000 to 100,000 cps.

In the above aspect, the glass transition temperature of the hot melt adhesive composition may be 0.3°C or more lower than the glass transition temperature of the amorphous poly alpha olefin, and the softening point of the hot melt adhesive composition may be 1°C or more higher than the softening point of the amorphous poly alpha olefin.

In the above aspect, the hot melt adhesive composition may have a needle penetration of 45 dmm or less and an adhesive strength of 2,500 gf/g or more.

In the above aspect, the hot melt adhesive composition may be for woodworking or automotive use.

The hot melt adhesive composition according to the present invention has the advantage of having an improved low-temperature flexibility by having a lower glass transition temperature by mixing an ethylene-propylene copolymer having an ethylene content of 35 to 55 mol% into an amorphous polyalpha olefin, while maintaining a high softening point to have excellent heat resistance, and also having excellent adhesive properties.

In addition, the hot melt adhesive composition can have high viscosity by mixing a high-viscosity ethylene-propylene copolymer into an amorphous polyalpha olefin, so that adhesive construction using a hot glue gun or roll method is possible, and thus it can be used for woodworking or automobiles such as headliners.

Hereinafter, a hot melt adhesive composition according to the present invention will be described in detail. In this context, unless otherwise defined, the technical and scientific terms used herein have the meanings commonly understood by those of ordinary skill in the art to which this invention pertains. In the following description and accompanying drawings, descriptions of well-known functions and configurations that may unnecessarily obscure the gist of the present invention will be omitted.

One aspect of the present invention relates to a hot melt adhesive composition comprising an amorphous polyalpha olefin and an ethylene-propylene copolymer, wherein the ethylene-propylene copolymer is characterized in that the ethylene content is 35 to 55 mol%.

In this way, the hot melt adhesive composition according to the present invention has the advantage of having an improved low-temperature flexibility by having a lower glass transition temperature by mixing an ethylene-propylene copolymer having an ethylene content of 35 to 55 mol% into an amorphous polyalpha olefin, while maintaining a high softening point to have excellent heat resistance, and also having excellent adhesive properties.

As a specific example, a hot melt adhesive composition according to an embodiment of the present invention may have a glass transition temperature that is 0.3°C or more lower than the glass transition temperature of an amorphous poly alpha olefin, and a softening point that is 1°C or more higher than the softening point of the amorphous poly alpha olefin. More specifically, the glass transition temperature of the hot melt adhesive composition may be 2 to 20°C lower than the glass transition temperature of the amorphous poly alpha olefin, and the softening point may be 1.5 to 5°C higher than the softening point of the amorphous poly alpha olefin.

In addition, the hot melt adhesive composition according to an example of the present invention may have a needle penetration of 45 dmm or less, more preferably 35 dmm or less, and even more preferably 30 dmm or less. In addition, the adhesive strength may be 2,500 gf/g or more, more preferably 3,000 gf/g or more, and even more preferably 3,500 gf/g or more. In this case, the needle penetration may be measured according to ASTM D 1321 and the lower limit may be 10 dmm, and the adhesive strength may be measured according to ASTM D1876-08 and the upper limit may be 6,000 gf/g.

Additionally, the viscosity of the base resin, which is a mixture of an amorphous polyalphaolefin and an ethylene-propylene copolymer, at 190°C may be 9,000 cps or higher, and more preferably 9,500 cps or higher. Within this range, when mixed with tackifiers and waxes, it may be suitable for woodworking or automotive headliners.

Hereinafter, each component of a hot melt adhesive composition according to an example of the present invention will be described in more detail.

In one example of the present invention, the amorphous poly alpha olefin (APAO) may be a homopolymer or copolymer polymerized with one or more alpha olefin monomers having 2 to 20 carbon atoms, and specifically, may be a polymerized with one or more alpha olefin monomers such as ethene, propene, 1-butene, 1-hexene, and 1-octene.

More specifically, the amorphous polyalpha olefin suitable for the present invention may have a melt viscosity at 190°C of 1,000 to 200,000 cps, more preferably 3,000 to 180,000 cps, even more preferably 5,000 to 100,000 cps, and even more preferably 8,000 to 50,000 cps. In addition, the amorphous polyalpha olefin may have a softening point of 130°C or higher, more preferably 135°C or higher, and even more preferably 140°C or higher, a glass transition temperature of -10°C or lower, and even more preferably -15°C or lower, and a needle penetration of 45 dmm or lower, more preferably 35 dmm or lower, and even more preferably 30 dmm or lower. When an ethylene-propylene copolymer satisfying the properties described below is mixed in an appropriate ratio within this range, excellent adhesive properties and thermal stability can be secured. At this time, the glass transition temperature (Tg) may be measured by differential scanning calorimetry (DSC) and the lower limit may be -30°C, the softening point may be measured according to ASTM E 28 & D36 and the upper limit may be 160°C, and the needle penetration may be measured according to ASTM D 1321 and the lower limit may be 10 dmm.

In one example of the present invention, the ethylene-propylene copolymer is added to maintain a high softening point of the hot melt adhesive composition to improve both excellent heat resistance and low-temperature flexibility, and as described above, it is preferable to use an ethylene content of 35 to 55 mol%, more preferably 35 to 50 mol%, and even more preferably 35 to 45 mol%. On the other hand, when the ethylene content of the ethylene-propylene copolymer is less than 35 mol%, the effect of lowering the glass transition temperature is insufficient, so that an improvement in low-temperature flexibility cannot be expected, and the softening point may decrease, resulting in a decrease in heat resistance. Conversely, when the ethylene content exceeds 55 mol%, a problem of poor compatibility with an amorphous polyalpha olefin resin may occur.

More specifically, the ethylene-propylene copolymer suitable for the present invention may have a number average molecular weight (Mn) of 20,000 to 50,000 g/mol, more preferably 25,000 to 45,000 mol/g, and even more preferably 30,000 to 40,000 g/mol. In addition, the viscosity at 190°C may be 10,000 to 100,000 cps, more preferably 30,000 to 80,000 cps, and even more preferably 40,000 to 60,000 cps, and the glass transition temperature may be -40°C or lower, more preferably -45°C or lower, and even more preferably -50°C or lower. Within this range, the adhesive strength and low-temperature flexibility of the hot melt adhesive can be more effectively maintained. In addition, by mixing an ethylene-propylene copolymer having a high viscosity of 10,000 to 100,000 cps into the amorphous poly alpha olefin, the hot melt adhesive composition can have a high viscosity, so that adhesive construction using a hot glue gun, etc. can be possible, and excellent adhesive strength can be exhibited when used for woodworking or automobile headliners. At this time, the glass transition temperature (Tg) may be measured by differential scanning calorimetry (DSC) and the lower limit may be -75°C, and the viscosity may be measured according to ASTM D 445.

Meanwhile, in order to secure a hot melt adhesive composition having excellent properties as described above, it is preferable to mix the amorphous poly alpha olefin and the ethylene-propylene copolymer at an appropriate ratio. Specifically, for example, the hot melt adhesive composition may have a weight ratio of the amorphous poly alpha olefin: the ethylene-propylene copolymer of 100:1 to 30, more preferably 100:3 to 25, and even more preferably 100:5 to 15. In this range, superior thermal stability and adhesive properties can be secured.

In addition, the hot melt adhesive composition according to one embodiment of the present invention may further include one or more additives selected from the group consisting of a tackifier and wax.

The above tackifier is used to lower the melt viscosity of the hot melt adhesive composition to improve workability, increase adhesion, and control open time, and may generally have a low molecular weight of 3,000 g/mol or less. Such tackifier may be used without particular limitation as long as it is commonly used in the art, and specifically, for example, it may be at least one selected from the group consisting of a natural resin including a rosin derivative such as gum rosin, modified rosin, or rosin ester; a C5 petroleum resin using an aliphatic C5 fraction such as pentadiene or isoprene as a raw material, a C9 petroleum resin using an aromatic C9 fraction such as styrene, vinyltoluene, or indene as a raw material, or a DCPD petroleum resin using dicyclopentadiene (DCPD) as a main raw material; and the like. At this time, the adhesive agent may be fully hydrogenated or partially hydrogenated.

The above wax is used to lower the melting viscosity of the hot melt adhesive composition to improve workability and to increase the surface energy of the surface of the adherend to facilitate adhesion, as well as to control the open time. Any wax commonly used in the art may be used without particular limitation. Specifically, for example, the wax may be at least one selected from the group consisting of paraffin wax, microcrystalline wax, polyethylene wax, polypropylene wax, and Fischer-Tropsch wax. Preferably, the wax suitable for the present invention may be Fischer-Tropsch wax.

In addition, the tackifier may be added in an amount of 10 to 30 wt%, more preferably 15 to 25 wt%, and even more preferably 18 to 23 wt%, based on the total weight of the hot melt adhesive composition. The wax may be added in an amount of 3 to 20 wt%, more preferably 5 to 15 wt%, and even more preferably 8 to 13 wt%, based on the total weight of the hot melt adhesive composition. The remainder not mentioned may be the amorphous poly alpha olefin and ethylene-propylene copolymer described above.

Hereinafter, the hot melt adhesive composition according to the present invention will be described in more detail through examples. However, the following examples are merely references for explaining the present invention in detail, and the present invention is not limited thereto, and may be implemented in various forms.

Additionally, unless otherwise defined, all technical and scientific terms have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein is solely for the purpose of effectively describing specific embodiments and is not intended to limit the invention. Furthermore, the unit of additives not specifically described in the specification may be weight percent.

[Characteristic evaluation method]

1) Melting viscosity (cps): Brookfield viscosity at 190℃ was measured according to ASTM D 3236-15.

2) Glass transition temperature (℃): Refers to the value measured by differential scanning calorimetry (DSC). Specifically, the measurement was performed at a heating rate of 10℃/min in accordance with ASTM D 3417.

3) Softening point (Ring and Ball Softening Point, RBSP, ℃): Measured according to ASTM E 28 & D36.

4) Needle Penetration (N.P, dmm): Needle penetration was measured according to ASTM D 1321.

5) Adhesion (gf/g): Hot melt adhesive was applied to Kraft paper at a certain thickness, pressed at 190℃ for 7 seconds, and a peel test was conducted using a Universal Testing Machine (UTM) according to ASTM D1876-08.

[Manufacturing Example 1]

A base resin was prepared by mixing 5 parts by weight of ethylene-propylene copolymer 1 (EPO-1, ethylene content 38 mol%, viscosity at 190°C 53,000 cps, glass transition temperature -52°C, number average molecular weight (Mn) 32,300 g/mol) with 100 parts by weight of amorphous polyalphaolefin (APAO, melting viscosity at 190°C 9,000 cps, needle penetration 20 dmm, softening point 141°C, glass transition temperature -19°C, open time 20 sec, tensile strength 0.80 MPa).

[Manufacturing Examples 2 to 5]

The base resin was prepared by mixing APAO and EPO-1 in different mixing ratios (parts by weight) as shown in Table 1 below.

[Comparative Manufacturing Example 1]

APAO was used as is without mixing EPO-1 into APAO.

[Comparative Manufacturing Example 2]

A base resin was prepared by mixing 20 parts by weight of ethylene-propylene copolymer 2 (EPO-2, viscosity 450 cps at 190°C) having an ethylene content of 5.5 mol% with 100 parts by weight of APAO.

[Comparative Manufacturing Example 3]

A base resin was prepared by mixing 20 parts by weight of ethylene-propylene copolymer 3 (EPO-3, melt index (MI, 190°C/2.16 kg) 21 g/10 min) having an ethylene content of 13 mol% with 100 parts by weight of APAO.

Base resin (by weight) Characteristic evaluation APAO EPO viscosity
(cps) Tg
(℃) RBSP
(℃) NP
(dmm) Manufacturing Example 1 100 EPO-1, 5 9,613 -19.4 144.9 21.1 Manufacturing Example 2 100 EPO-1, 10 9,825 -22.0 144.1 22.6 Manufacturing Example 3 100 EPO-1, 15 10,200 -24.4 143.8 24.1 Manufacturing Example 4 100 EPO-1, 20 11,300 -26.5 143.4 26.6 Manufacturing Example 5 100 EPO-1, 25 12,150 -34.2 142.8 28.1 Comparative Manufacturing Example 1 100 - 9,000 -19.0 141.0 20.0 Comparative Manufacturing Example 2 100 EPO-2, 20 2,968 -25.0 141.0 29.0 Comparative manufacturing example 3 100 EPO-3, 20 23,030 -19.0 114.6 17.5

Referring to Table 1 above, in the case of the base resins of Manufacturing Examples 1 to 5 in which EPO-1 having an ethylene content of 38 mol% was mixed with APAO according to the present invention, the Tg was lowered by 0.4°C or more and the RBSP was increased by 1.8°C or more compared to Comparative Manufacturing Example 1, so that both low-temperature flexibility and heat resistance were improved, and the needle penetration was increased by 1.1 dmm or more.

On the other hand, in the case of Comparative Manufacturing Example 2, which mixed EPO-2 with an ethylene content of 5.5 mol% and a viscosity of 450 cps, the glass transition temperature was lowered, so low-temperature flexibility was improved, but heat resistance was not improved. In addition, in the case of Comparative Manufacturing Example 3, which mixed EPO-3 with an ethylene content of 13 mol% and a viscosity of 810,000 cps, the glass transition temperature did not change, so low-temperature flexibility was not improved, and there was a problem that the softening point was lowered, so heat resistance was lowered.

[Examples 1 to 5 and Comparative Examples 1 to 3]

A hot melt adhesive composition was prepared by mixing 70 wt% of each of the base resins of the above-described Manufacturing Examples 1 to 5 and Comparative Manufacturing Examples 1 to 3, 20 wt% of a tackifier (trade name SU-90), and 10 wt% of a wax (trade name C105, Fischer-Tropsch wax).

Adhesion (gf/g) Example 1 4,043 Example 2 3,873 Example 3 4,208 Example 4 3,687 Example 5 3,755 Comparative Example 1 2,111 Comparative Example 2 2,259 Comparative Example 3 3,148

Referring to Table 2 above, Examples 1 to 5, in which EPO-1 having an ethylene content of 38 mol% was mixed with APAO, showed significantly improved adhesive strength compared to Comparative Example 1.

Although the present invention has been described through specific matters and limited examples as described above, these are provided only to help a more general understanding of the present invention, and the present invention is not limited to the above examples, and those skilled in the art to which the present invention pertains can make various modifications and variations based on this description.

Therefore, the idea of the present invention should not be limited to the described embodiments, and all things that are equivalent or equivalent to the claims described below as well as the claims are considered to fall within the scope of the idea of the present invention.

Claims (13)

Includes amorphous polyalphaolefins and ethylene-propylene copolymers,
The above amorphous polyalpha olefin has a melting viscosity of 1,000 to 200,000 cps at 190°C, a softening point of 130°C or higher, and a glass transition temperature of -10°C or lower.
A hot melt adhesive composition, characterized in that the ethylene-propylene copolymer has an ethylene content of 35 to 55 mol%, a number average molecular weight (Mn) of 20,000 to 50,000 g/mol, a viscosity at 190°C of 10,000 to 100,000 cps, and a glass transition temperature of -50°C or lower. In paragraph 1,
The hot melt adhesive composition is characterized in that the weight ratio of the amorphous poly alpha olefin: ethylene-propylene copolymer is 100:1 to 30. delete delete delete In paragraph 1,
A hot melt adhesive composition, characterized in that the above amorphous polyalpha olefin has a needle penetration of 45 dmm or less. delete delete delete In paragraph 1,
A hot melt adhesive composition, characterized in that the glass transition temperature of the hot melt adhesive composition is 0.3°C or more lower than the glass transition temperature of the amorphous poly alpha olefin, and the softening point of the hot melt adhesive composition is 1°C or more higher than the softening point of the amorphous poly alpha olefin. In paragraph 1,
A hot melt adhesive composition, characterized in that the above hot melt adhesive composition has a needle penetration rate of 45 dmm or less. In paragraph 1,
A hot melt adhesive composition, characterized in that the hot melt adhesive composition has an adhesive strength of 2,500 gf/g or more. In paragraph 1,
A hot melt adhesive composition characterized in that the hot melt adhesive composition is for woodworking or automotive use.