Hot melt adhesive

Abstract

To provide a hot melt adhesive which has good workability due to its moderate melt viscosity, cushioning properties due to its appropriate hardness, is easy to handle due to its good tackiness, has excellent metal adhesion, and is inhibited from bleeding out of oil and fat components after application. [Solution] A hot melt adhesive comprising a styrene-based block copolymer (A), a tackifier (B), and a softener (C), wherein the styrene-based block copolymer (A) comprises a styrene-based block copolymer (a1) having a styrene content of 50% by weight or less and a diblock content of 35% by weight or less, and a styrene-based block copolymer (a2) having a styrene content of 50% by weight or less and a diblock content of 40% by weight or more.

Description

[Technical Field]

[0001] The present invention relates to hot melt adhesives. [Background technology]

[0002] Research and development of hot melt adhesives has been extensively conducted for some time. Generally, hot melt adhesives melt when heated and solidify when cooled to room temperature of around 23°C, allowing them to bond. Hot melt adhesives are characterized by their solvent-free nature, environmental friendliness, ability to solidify in a short time, and ease of handling. They are also widely used in a variety of fields because they can improve the working environment at manufacturing sites.

[0003] Previously, the applicant of the present application invented a hot melt composition comprising a styrene block copolymer (A) and a tackifier (B), wherein the styrene block copolymer (A) comprises a styrene block copolymer (a1) having a styrene content of less than 20% by weight and a diblock content of less than 22% by weight, and a styrene block copolymer (a2) having a styrene content of 20% by weight or more and a diblock content of 22% by weight or more (Patent Document 1). This hot melt composition maintained stability after solidification and exhibited good coatability, preventing uneven application or clumping, and exhibited excellent adhesive strength and heat resistance. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6906596

[0005] Traditionally, various adhesives have been used in the construction industry to secure components and improve water resistance, but the use of hot melt adhesives is increasing because they are very easy to handle, do not require a drying process, and have excellent adhesive stability at room temperature of around 23°C.

[0006] Here, when attaching inorganic decorative materials as exterior materials, conventional hot melt adhesives have a problem of being difficult to apply because they are somewhat hard and lack cushioning. Furthermore, to improve the ease of handling of hot melt adhesives, it is necessary for the surface to be low in stickiness and have good tackiness. Furthermore, metal decorative materials are sometimes selected as exterior materials, and adhesion to these materials is also required. After application, deterioration over time can cause the oil and fat components contained in the hot melt adhesive's softener to bleed out, changing the adhesive's properties and gradually reducing its cushioning, leaving room for improvement. Summary of the Invention [Problem to be solved by the invention]

[0007] The problem to be solved by the present invention is to provide a hot melt adhesive that has good workability due to its moderate melt viscosity, cushioning properties due to its appropriate hardness, ease of handling due to its good tackiness, excellent metal adhesion, and suppressed bleeding of oil and fat components after application. [Means for solving the problem]

[0008] The present invention provides a hot melt adhesive comprising a styrene-based block copolymer (A), a tackifier (B), and a softener (C), wherein the styrene-based block copolymer (A) comprises a styrene-based block copolymer (a1) having a styrene content of 50% by weight or less and a diblock content of 35% by weight or less, and a styrene-based block copolymer (a2) having a styrene content of 50% by weight or less and a diblock content of 40% by weight or more. [Effects of the Invention]

[0009] The hot melt adhesive of the present invention has the following advantages: it has a moderate melt viscosity, which makes it easy to work with; it has appropriate hardness, which provides cushioning; it has good tackiness, which makes it easy to handle; it has excellent adhesion to metal; and it suppresses the seepage of oil and fat components after application. DETAILED DESCRIPTION OF THE INVENTION

[0010] <Styrene-based block copolymer> In the present invention, a styrene-based block copolymer (A) is used as the base polymer of the hot melt adhesive according to the present invention.

[0011] Component (A) is composed of a hard block derived from a styrene compound and a soft block derived from a diene compound. The bonding configuration of each block can be linear, branched, or radial, but linear bonding is more common.

[0012] Component (A) can be divided into two types: "unhydrogenated styrene-based block copolymers" in which the soft block is not hydrogenated, and "hydrogenated styrene-based block copolymers" in which the soft block is hydrogenated.

[0013] Examples of unhydrogenated styrene block copolymers include styrene-isoprene-styrene block copolymer (SIS) and styrene-butadiene-styrene block copolymer (SBS), while examples of hydrogenated styrene block copolymers include styrene-ethylene / butylene-styrene block copolymer (SEBS), styrene-ethylene / propylene-styrene block copolymer (SEPS), and styrene-ethylene-ethylene / propylene-styrene block copolymer (SEEPS). Among these, in the present invention, it is preferable to use hydrogenated styrene block copolymers because they have excellent adhesive stability and durability.

[0014] In the present invention, it is necessary to use, as the component (A), a styrene-based block copolymer (a1) having a styrene content of 50% by weight or less and a diblock content of 35% by weight or less, and a styrene-based block copolymer (a2) having a styrene content of 50% by weight or less and a diblock content of 40% by weight or more.

[0015] By appropriately adjusting the blending ratio of the hard block derived from a styrene compound and the soft block derived from a diene compound, hot melt adhesives with a variety of properties can be produced using the (A) component. Generally, a higher styrene content tends to increase rigidity, while a lower styrene content tends to increase flexibility. In the present invention, the styrene content of the (A) component must be 50% by weight or less, preferably 10 to 45% by weight, more preferably 15 to 40% by weight, and particularly preferably 20 to 35% by weight. By keeping the styrene content within this range, it is possible to produce a hot melt adhesive that is highly flexible while maintaining a certain degree of rigidity.

[0016] Furthermore, component (A) can be classified as a diblock structure or a triblock structure, depending on the bonding configuration of the hard block derived from the styrene compound and the soft block derived from the diene compound. Specifically, a "hard block-soft block" structure is classified as a diblock structure, while a "hard block-soft block-hard block" structure is classified as a triblock structure. For example, the above-mentioned styrene-ethylene / butylene-styrene block copolymer (SEBS) has an "S-EB-S" bonding configuration, so it is basically a triblock structure. However, some raw materials are beginning to be provided that contain both a triblock structure component and a diblock structure component.

[0017] The diblock ratio of component (A) can be expressed as the percentage of the diblock structure contained in a total of 100% by weight of the diblock structure and triblock structure. The inventors of the present invention attempted to improve the properties of hot melt adhesives by combining two types of raw materials having a specific diblock ratio in component (A).

[0018] First, the diblock ratio of the component (a1) must be 35% by weight or less, preferably 25% by weight or less, more preferably 15% by weight or less, and particularly preferably 5% by weight or less. By keeping the ratio within this range, surface stickiness is kept low and tackiness tends to be improved.

[0019] Specific examples of the component (a1) include Taipol 6152 (trade name, manufactured by TSRC, styrene-ethylene / butylene-styrene block copolymer (SEBS), styrene content: 30% by weight, diblock content: less than 1% by weight).

[0020] The diblock ratio of component (a2) must be at least 40% by weight, preferably at least 50% by weight, more preferably at least 55% by weight, and particularly preferably at least 60% by weight. By keeping the ratio within this range, adhesion to metals becomes easier, and metal adhesion tends to improve.

[0021] Specific examples of the component (a2) include GLOBALPRENE 9526D (trade name, manufactured by LCY, styrene-ethylene / butylene-styrene block copolymer (SEBS), styrene content: 30 wt %, diblock content: 70 wt %).

[0022] The inventors of the present invention discovered that the use of both components (a1) and (a2) results in an appropriate hardness, resulting in cushioning properties, good tackiness, easy handling, and excellent metal adhesion, leading to the completion of the present invention. One of the factors contributing to these effects is presumably that the combined use of components (a1) and (a2) results in a structure that combines a diblock polymer having a soft block derived from a diene compound at one end of the polymer with a triblock polymer in which both ends of the polymer are hard blocks derived from a styrene compound, thereby achieving a balance between the cohesive strength due to the pseudo-crosslinking of the styrene phase and the wettability of the substrate, resulting in appropriate elasticity and metal adhesion.

[0023] The content of the (A) component is preferably 10 to 40 parts by weight, more preferably 15 to 35 parts by weight, and particularly preferably 20 to 30 parts by weight, per 100 parts by weight of the total of the (A) to (C) components.

[0024] The blending ratio (parts by weight) of component (a1) to component (a2) in component (A) is preferably 1:0.1 to 10, more preferably 1:0.2 to 5, and particularly preferably 1:0.25 to 4. Blending within this range tends to further improve the physical properties of the hot melt adhesive according to the present invention.

[0025] <Tackifier> In the present invention, a tackifier (B) is used. Examples of the component (B) include a styrene-based tackifier (b1) and a non-styrene-based tackifier (b2).

[0026] (styrene-based tackifier) In the present invention, a styrene-based tackifier (b1) can be used. Examples of the (b1) component include polymers of styrene-based monomers, and it is particularly preferable to use those synthesized from styrene or α-methylstyrene, etc., in order to improve stability in high temperature regions.

[0027] In particular, in the present invention, by using the component (b1), both tackiness and exudation suppression are improved, and it tends to be easier to achieve both of these properties.

[0028] The softening point of the component (b1) is preferably 80 to 200°C, more preferably 90 to 190°C, and particularly preferably 100 to 180°C.

[0029] Specific examples of the component (b1) include FMR 0150 (trade name, manufactured by Mitsui Chemicals, Inc., styrene-based, softening point: 145°C), Endex 155 (trade name, manufactured by Eastman Co., Ltd., α-methylstyrene-based, softening point: 153°C), and MK-115 (trade name, manufactured by Kolon Co., Ltd., styrene / α-methylstyrene-based, softening point: 110 to 120°C).

[0030] (Non-styrene tackifier) In addition, the present invention can use a non-styrene-based tackifier (b2). The component (b2) can be any compound other than the component (b1), such as terpene resins, terpene phenol resins, rosin resins, C5 petroleum resins, C9 petroleum resins, C5-C9 petroleum resins, DCPD petroleum resins, and hydrogenated or modified products thereof.

[0031] The softening point of the component (b2) is preferably 60 to 160°C, more preferably 70 to 150°C, and particularly preferably 80 to 145°C.

[0032] Specific examples of the component (b2) include HM-1000 (trade name, manufactured by Henghe Co., Ltd., hydrogenated C9 petroleum resin, softening point: 100°C), T-REZ HA125 (trade name, manufactured by Eneos Corporation, hydrogenated DCPD petroleum resin, softening point: 120°C to 130°C), Eastotac H-142W (trade name, manufactured by Eastman Co., Ltd., hydrogenated C5 petroleum resin, softening point: 142°C), Pine Crystal KE-311 (trade name, manufactured by Arakawa Chemical Industries, Ltd., rosin-based resin, softening point: 90°C to 100°C, acid value: 2 to 10), and YS Resin PX1250 (trade name, manufactured by Yasuhara Chemical Co., Ltd., terpene-based resin, softening point: 120°C to 130°C).

[0033] The content of the (B) component is preferably 5 to 35 parts by weight, more preferably 10 to 30 parts by weight, and particularly preferably 15 to 25 parts by weight, per 100 parts by weight of the total of the (A) to (C) components.

[0034] Furthermore, when the (b1) component and the (b2) component are used in combination within the (B) component, the weight ratio thereof is preferably 1:0.01-10, more preferably 1:0.05-5, and particularly preferably 1:0.1-3.

[0035] <Softener> In the present invention, a softener (C) is used. The use of component (C) improves the dispersibility of components (A) and (B), thereby increasing the wettability of the adherend surface and enabling improved interlayer adhesion.

[0036] Examples of the component (C) include organic compounds that are liquid at room temperature (23°C). Specific examples include paraffinic oil, naphthenic oil, polybutene, polyisobutylene, and liquid paraffin. Among these, oil and polybutene are preferred because they are highly stable and easy to handle. In particular, when paraffinic oil is used, there is a tendency for the bleeding of oil and fat components to be effectively suppressed.

[0037] A specific example of the component (C) is Nippon Oil Polybutene HV-100 (trade name, manufactured by Eneos Corporation, polybutene, kinematic viscosity (40°C): 9,500 mm 2 / s), Nippon Oil Polybutene HV-300 (trade name, manufactured by Eneos Corporation, polybutene, kinematic viscosity (40°C): 26,000 mm 2 / s), Diana Process Oil PW-90 (product name, manufactured by Idemitsu Kosan Co., Ltd., paraffin oil, kinematic viscosity (40°C): 90 mm 2 / s), Lily 500 (trade name, manufactured by Kudong, paraffinic oil, kinematic viscosity (40°C): 107mm 2 / s) are some examples.

[0038] The content of the (C) component is preferably 40 to 70 parts by weight, more preferably 45 to 65 parts by weight, and particularly preferably 50 to 60 parts by weight, per 100 parts by weight of the total of the (A) to (C) components.

[0039] <Other ingredients> In the present invention, in addition to the above-mentioned components (A) to (C), wax can be used. Types of wax include natural wax and synthetic wax, and examples of natural wax include paraffin wax and microcrystalline wax, and examples of synthetic wax include polyethylene wax and polypropylene wax.

[0040] Specific examples of waxes include Hiwax NP500 (trade name, manufactured by Mitsui Chemicals, Inc., polypropylene wax, melting point: 161°C), H-110 (trade name, manufactured by SQI Thailand, polyethylene wax, melting point: 110°C), and Umex 1010 (trade name, manufactured by Sanyo Chemical Industries, Ltd., maleic anhydride-modified polypropylene wax, melting point: 135°C).

[0041] In the present invention, various additives can be used. Examples of the additives include primary antioxidants, secondary antioxidants, light stabilizers, and ultraviolet absorbers. Examples of the primary antioxidants include hindered phenol compounds, a specific example of which is Irganox 1010 (trade name, manufactured by BASF). Examples of the secondary antioxidants include phosphite and thioether compounds, a specific example of which is Irgafos 168 (trade name, manufactured by BASF).

[0042] In addition, in the present invention, various adjuvants such as fillers such as calcium carbonate, talc, and clay, preservatives, and colorants may also be contained.

[0043] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to these descriptions. [Example]

[0044] <Examples and Comparative Examples> The hot melt adhesives of the Examples and Comparative Examples were produced by thoroughly kneading the ingredients in the formulations shown in Table 1 in a flask adjusted to 150°C. Here, the values ​​in Table 1 represent parts by weight. The raw materials used are listed below. Raw materials for styrene block copolymer (A) Taipol 6152 (product name, manufactured by TSRC, styrene-ethylene / butylene-styrene block copolymer (SEBS), styrene content: 30% by weight, diblock content: less than 1% by weight) GLOBALPRENE 9526D (product name, manufactured by LCY, styrene-ethylene / butylene-styrene block copolymer (SEBS), styrene content: 30% by weight, diblock content: 70% by weight) Raw materials for tackifier (B) MK-115 (product name, manufactured by Kolon, styrene / α-methylstyrene type, softening point: 110-120°C) HM-1000 (Product name, manufactured by Henghe, hydrogenated C9 petroleum resin, softening point: 100℃) Raw materials for softener (C) Diana Process Oil PW-90 (product name, manufactured by Idemitsu Kosan Co., Ltd., paraffin oil, kinematic viscosity (40°C): 90 mm) 2 / s) Other Ingredients Chinox 1010 (trade name, manufactured by Double Bond Chemical, antioxidant)

[0045] [Table 1]

[0046] The hot melt adhesives produced in the above examples were evaluated for various physical properties in the following manner. The results are shown in Table 2.

[0047] <Melt viscosity> Using a Brookfield viscometer, the hot melt adhesive was melted at 150°C and left to stand for 10 minutes, then rotation was started at 10-50 rpm with a No. 27 spindle, and the melt viscosity (mPa·s) was measured after 10 minutes. A melt viscosity of 7,000 mPa·s or less was considered to have good workability.

[0048] <Softening point> The softening point (°C) of the hot melt adhesive was measured in accordance with JIS K 6863.

[0049] <Hardness> The molten hot melt adhesive was poured into a mold and cured at 23°C and 50% humidity for 24 hours to solidify, then processed into a 12mm thick sheet. The sheet was then placed on a flat workbench and a 5kg load was applied from above using an ASKER hardness tester type C. The hardness was measured by reading the scale after 5 seconds. A hardness of 28-42 was considered to have good cushioning properties.

[0050] <Tackiness> The molten hot melt adhesive was dropped onto a smooth release paper and cured at a temperature of 23°C and humidity of 50% for 24 hours to harden. After that, the surface of the solidified hot melt adhesive was pressed firmly with a finger, and the sensation when released was checked using a sensory evaluation. If there was no feeling left on the finger and there was almost no stickiness, it was rated as ◎; if there was a slight feeling of sticking to the finger, it was rated as 〇; if there was a strong stickiness, it was rated as ×.

[0051] <Metal adhesion> The molten hot melt adhesive was cured at 23°C and 50% humidity for 24 hours to solidify, then processed into a 1mm thick sheet and cut into a 25mm wide x 120mm long piece. This was placed on a 25mm wide x 100mm long stainless steel plate, covered with release paper, and rolled twice with a 2kg roller. The edge of the hot melt sheet was then gripped and pulled at a 90° angle to the stainless steel plate using a tensile tester to measure the maximum strength. A maximum strength of 1.2N or greater was evaluated as ◯, a maximum strength of 0.6N or greater but less than 1.2N as △, and a maximum strength of less than 0.6N as ×.

[0052] <Exudation test> The molten hot melt adhesive was cured at 23°C and 50% humidity for 24 hours to solidify, then processed into a 1 mm thick sheet and cut into 35 mm diameter circles. Two circular No. 2 qualitative filter papers (diameter: 50 mm) were then prepared, one on top of the other, and the cut hot melt adhesive was sandwiched between them and placed on a smooth plate. A 1 kg weight was then placed on top of the filter paper and the plate was left to stand in an incubator at 80°C for 24 hours. The plate was then removed and visually inspected for seepage into the filter paper. Filter paper with almost no discoloration was evaluated as ◯, filter paper with slight discoloration as △, and filter paper with significant discoloration as ×.

[0053] [Table 2]

[0054] When various styrene-based block copolymers were used to manufacture the hot melt adhesives of the Examples and Comparative Examples, the Examples had better workability due to their moderate melt viscosity, cushioning properties due to their appropriate hardness, good tackiness for ease of handling, excellent metal adhesion, and suppressed bleeding of oil and fat components after application.

Claims

[Claim 1] The composition contains a styrene-based block copolymer (A), a tackifier (B), and a softener (C), The styrene-based block copolymer (A) is a hydrogenated styrene-based block copolymer (a1) having a styrene content of 50% by weight or less and a diblock content of 35% by weight or less; and a hydrogenated styrene-based block copolymer (a2) having a styrene content of 50% by weight or less and a diblock content of 40% by weight or more, the blending ratio (parts by weight) of the copolymer (a2) and the copolymer (a2) is 1:0.1 to 10, The tackifier (B) contains a styrene-based tackifier (b1), A hot melt adhesive for decorative materials, characterized in that it contains paraffin oil as the softener (C).

Images