Hot melt adhesive

Abstract

To provide an adhesive having excellent adhesion between various materials, including resin materials such as PP, polyolefin, and PS, and metal materials such as aluminum, aluminum alloys, and stainless steel, and particularly, a hot melt adhesive polymer material that enables excellent bonding of metal surface substrates without surface treatment, including between dissimilar materials such as resin and metal.SOLUTION: The present invention provides a hot melt adhesive comprising a chlorosulfonated propylene-based polymer in which chlorine and chlorosulfonyl groups are bonded to a propylene-based polymer.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a hot melt adhesive containing a chlorosulfonated propylene-based polymer in which chlorine and chlorosulfone groups are bonded to a propylene-based polymer. [Background technology]

[0002] Traditionally, metals have been joined mainly by welding, riveting, and bolting, but with today's advances in science and technology, the performance and functionality of materials required has become more stringent, and there is a demand for adhesion between dissimilar materials. In order to meet these demands, attention has been focused on and development has been made in adhesive technology.

[0003] Among these, hot melt adhesives are used in a wide range of fields because they are solvent-free, have a low environmental impact, and are easy to handle.

[0004] Furthermore, due to technological innovations in the automotive sector and elsewhere, it is expected that adhesion technologies for not only resin and metal components alone but also resin-metal composite materials, and especially for dissimilar materials such as polypropylene and metal, will become increasingly important in the future.

[0005] Polypropylene is widely used in a wide range of applications due to its excellent processability, physical properties, recyclability, and price. However, it is a poorly adhesive material, and it is difficult to ensure sufficient adhesive strength even when surface treatments are applied (see, for example, Non-Patent Document 1).

[0006] On the other hand, chlorosulfonated polyethylene has excellent heat resistance, weather resistance, ozone resistance, chemical resistance and bright color, and is therefore used in applications such as various hose cover materials, electric wire covering materials, packings, gaskets, rolls, and escalator handrails, and is also used in applications such as adhesives, coating agents, paints, and primers when dissolved in organic solvents.

[0007] However, chlorosulfonated polyethylene has insufficient adhesion to polypropylene resin, and although there have been studies on chlorosulfonated polyethylene latex for treating glass fibers for use in bonding rubber (see, for example, Patent Document 1), no studies have been conducted on bonding to metals, etc.

[0008] On the other hand, chlorosulfonated polypropylene has also been studied (for example, see Patent Document 2). However, an aqueous emulsion was prepared as a primer for polypropylene-based resin, and the adhesion of the coating film was evaluated, but no study was conducted on the adhesion of dissimilar materials, such as polypropylene-based resin and metal. [Prior art documents] [Non-patent literature]

[0009] [Non-Patent Document 1] Journal of the Adhesion Society of Japan Vol.54 No6(2018) Section 212~ [Patent documents]

[0010] [Patent Document 1] JP 2020-83918 A [Patent Document 2] JP 2008-127436 A Summary of the Invention [Problem to be solved by the invention]

[0011] The present invention has been made in consideration of the above problems, and an object of the present invention is to provide a hot melt adhesive that can exhibit good adhesion between various components, particularly resins such as PP, polyolefin, and PS, and metal components such as aluminum components, aluminum alloy components, and stainless steel components, as well as between different components such as resin components and metal components, while minimizing the effects of surface treatment conditions. [Means for solving the problem]

[0012] The present inventors have conducted extensive research to solve the above problems and have completed the present invention. That is, the present invention relates to the following items [1] to [4].

[0013] [1] A hot melt adhesive comprising a chlorosulfonated propylene polymer in which chlorine and chlorosulfone groups are bonded to a propylene polymer.

[0014] [2] The hot melt adhesive according to [1], wherein the chlorine content of the chlorosulfonated propylene polymer is 5.0 to 50.0%.

[0015] [3] The hot melt adhesive according to [1] or [2], wherein the sulfur content of the chlorosulfonated propylene polymer is 0.1 to 10.0%.

[0016] [4] The hot melt adhesive according to any one of [1] to [3], wherein the propylene-based polymer is a propylene homopolymer or an ethylene-propylene copolymer. Effect of the Invention

[0017] The hot melt adhesive of the present invention exhibits good adhesion to various members including resin and metal members. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] The present invention will be described in detail below.

[0019] A hot melt adhesive according to one embodiment of the present invention is a hot melt adhesive containing a chlorosulfonated propylene-based polymer in which chlorine and chlorosulfone groups are bonded to a propylene-based polymer.

[0020] In this specification, the term "hot melt adhesive" refers to an adhesive that is solid at room temperature but becomes fluid when heated, and can be applied to an object such as a substrate or adherend, and hardens and adheres when cooled.

[0021] The chlorosulfonated propylene polymer may be any propylene polymer having chlorine and chlorosulfone groups bonded thereto.

[0022] The chlorine content of the chlorosulfonated propylene polymer is preferably 5.0% by weight or more, more preferably 8.0% by weight or more, and even more preferably 10.0% by weight or more, because excellent adhesion, particularly to low-polarity resins such as polypropylene, can be obtained. Also, the chlorine content is preferably 50.0% by weight or less, more preferably 40.0% by weight or less, even more preferably 35.0% by weight or less, and especially preferably 30.0% by weight or less, because excellent adhesion, particularly to low-polarity resins such as polypropylene, can be obtained.

[0023] The sulfur content of the chlorosulfonated propylene-based polymer is preferably 0.1% by weight or more, more preferably 0.2% by weight or more, even more preferably 0.3% by weight or more, and particularly preferably 0.4% by weight or more, because excellent adhesion, particularly excellent adhesion to metal, can be obtained. In addition, the sulfur content is preferably 10.0% by weight or less, preferably 8.0% by weight or less, and even more preferably 5.0% by weight or less, because the stability of the polymer is excellent. The chlorosulfonated propylene-based polymer may be obtained by any method, and can be obtained, for example, by chlorosulfonating a raw material propylene-based polymer constituting the chlorosulfonated propylene-based polymer.

[0024] Examples of propylene-based polymers that are raw materials for chlorosulfonated propylene-based polymers include propylene homopolymers, ethylene-propylene copolymers such as random polypropylenes in which ethylene is randomly copolymerized and block polypropylenes in which ethylene is block copolymerized, polypropylene terpolymers in which ethylene and α-olefins are copolymerized, syndiotactic polypropylene, atactic polypropylene, and long-chain branched polypropylene. Examples of α-olefins that are copolymerized into polypropylene terpolymers include 1-butene, 1-pentene, 4-methyl-1-pentene, 3-methyl-1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, and 1-decene. Prime Polymer Co., Ltd. sells products under the trade name Prime Polypro, Japan Polypropylene Corporation sells products under the trade names Novatec PP, Wintech, Newcon, Waymax, and Newstrene, and Sumitomo Chemical Co., Ltd. sells products under the trade names Noblen, Excellen, and Sumitic. Such polypropylenes may be used alone or in combination of two or more types. Since the propylene-based polymer used as the raw material has excellent adhesion to low polarity resins such as polypropylene and metals, it is preferable that the propylene-based polymer is a propylene homopolymer or an ethylene-propylene copolymer, more preferably an ethylene-propylene copolymer, and among the ethylene-propylene copolymers, it is particularly preferable that the propylene-based polymer is a block polypropylene in which ethylene is block copolymerized. Note that the block polypropylene is sometimes called impact resistant polypropylene, impact polypropylene, impact copolymer, ICP, etc., but these are also included. The content of the ethylene unit copolymerized in the random polypropylene and block polypropylene is preferably 30 mol% or less, more preferably 25 mol% or less, and even more preferably 20 mol% or less, since the adhesiveness to low polarity resins such as polypropylene and metals is excellent.

[0025] The method for obtaining the chlorosulfonated propylene-based polymer is not particularly limited, and examples thereof include a solution method in which a propylene-based polymer is uniformly dissolved in an inert solvent and reacted, a suspension method in which a propylene-based polymer is suspended in a solvent and reacted, a dissolution method in which a propylene-based polymer is dissolved in a solvent and reacted, etc. Among these, the solution method, which can uniformly chlorinate and chlorosulfonate the propylene-based polymer, is preferred.

[0026] The solvent used in the chlorosulfonation by the solution method is not particularly limited, and examples thereof include carbon tetrachloride, trichloroethane, tetrachloroethane, chloroform, chlorobenzene, and the like from the viewpoints of solubility and reactivity, and trichloroethane is particularly preferred because of its favorable reactivity.

[0027] The chlorosulfonating agent used in chlorosulfonating the propylene polymer is not particularly limited, and sulfurous acid gas, chlorine, sulfuryl chloride, etc. may be used alone or in combination. In addition, a catalyst for promoting the chlorosulfonation reaction may be used as necessary. Examples of the catalyst include azo compounds and organic peroxides. Examples of the azo compounds include α,α'-azobisisobutyronitrile, azobiscyclohexanecarbonitrile, 2,2'-azobis(2,4-dimethylvaleronitrile), etc., and examples of the organic peroxides include benzoyl peroxide, acetyl peroxide, t-butyl peroxide, t-butyl perbenzoate, etc. Azo compounds are preferred because they are highly stable in handling, and α,α'-azobisisobutyronitrile is particularly preferred because they allow moderate chlorination and chlorosulfonation reactions to proceed. Furthermore, amino compounds such as pyridine and quinoline, and phosphate compounds may be added as co-catalysts for promoting the chlorosulfonation reaction as necessary.

[0028] The chlorinating agent used for chlorinating the propylene polymer is not particularly limited, and chlorinating agents such as chlorine gas, thionyl chloride, and sulfuryl chloride may be used alone or in combination. In addition, a catalyst for promoting the chlorination reaction may be used as necessary. Examples of the catalyst include azo compounds and organic peroxides. Examples of the azo compounds include α,α'-azobisisobutyronitrile, azobiscyclohexanecarbonitrile, and 2,2'-azobis(2,4-dimethylvaleronitrile), and examples of the organic peroxides include benzoyl peroxide, acetyl peroxide, t-butyl peroxide, and t-butyl perbenzoate. Azo compounds are preferred because they are highly stable in terms of handling, and α,α'-azobisisobutyronitrile is particularly preferred because they allow moderate chlorination and chlorosulfonation reactions to proceed. Furthermore, amino compounds such as pyridine and quinoline, and phosphate compounds may be added as co-catalysts for promoting the chlorination reaction as necessary.

[0029] The reaction temperature during chlorosulfonation or chlorination is not particularly limited and can be appropriately selected according to the melting point of the raw material polymer, and in particular, taking into consideration reactivity and handling, it is preferably 50 to 150° C., and more preferably 60 to 130° C. In addition, the reaction pressure during chlorosulfonation or chlorination is not particularly limited and is, for example, 0 to 1.0 MPa, and is preferably 0 to 0.6 MPa in order to allow the chlorosulfonation and chlorination reactions to proceed appropriately.

[0030] After the chlorosulfonation or chlorination reaction is completed, sulfur dioxide gas or hydrogen chloride remaining in the reaction solution can be removed by introducing nitrogen. There is no problem even if the sulfur dioxide gas or hydrogen chloride is removed under reduced pressure.

[0031] Furthermore, additives such as antioxidants and stabilizers may be added either before or after the chlorosulfonation or chlorination reaction. The type of additive is not particularly limited, and examples thereof include hindered phenol-based antioxidants such as 4-t-butylcatechol, 2,6-di-t-butyl-p-cresol, triethylene glycol bis[3-(3-t-butyl-4-hydroxy-5-methylphenyl)propionate], and epoxy compounds such as epoxidized polybutadiene and bisphenol A resin, which may be used alone or in combination of two or more. The timing of adding the additive is not particularly limited, but in consideration of the ease of operation and the efficiency of the additive, it is preferable to add the additive after the chlorosulfonation or chlorination reaction and after removing the remaining gas.

[0032] The method for separating the polymer and the solvent from the chlorosulfonated or chlorinated product polymer solution is not particularly limited, but for example, steam distillation, a drum dryer, a vented extruder, etc. can be used.

[0033] The hot melt adhesive of the present invention may further contain various additives as necessary. Examples of such various additives include tackifiers, waxes, crosslinking agents, crosslinking assistants, acid acceptors, plasticizers, viscosity regulators, flexibility imparting agents, inorganic fillers, antioxidants, antiaging agents, UV absorbers, adhesion promoters, silane coupling agents, etc., which can be added to the adhesive. The amounts of these additives may be conventional amounts as long as they do not go against the purpose of the present invention.

[0034] The hot melt adhesive of the present invention can be used as an adhesive that has excellent adhesion to various substrates, and in particular, is excellent in bonding dissimilar materials between metals and resins such as polypropylene. In the case of metals, for example, iron, stainless steel, steel, carbon steel, aluminum, etc., as well as alloys thereof, metal oxides, metal hydroxides, etc., and also substrates having these at least on the surface, it is an adhesive that exhibits excellent adhesion regardless of the presence or absence of surface treatment or surface modification such as primer treatment. EXAMPLES

[0035] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0036] In the examples, the ethylene content of the propylene polymer, and the chlorine content, sulfur content, melting point, heat of crystal fusion, molecular weight, and adhesive strength of the chlorosulfonated propylene polymer were measured as described below.

[0037] [Measurement of ethylene content in propylene polymers] The ethylene content of propylene polymers is 13 Measurements were performed using C-NMR.

[0038] The solvent was 1,1,2,2-tetrachloroethane-d2 at 130°C using an AVANCE NEO700 (Bruker). 13 C-NMR measurement was carried out, and from the obtained spectrum, each peak was assigned according to the following references 2 and 3. The ethylene content was calculated from the integral value of each assigned peak.

[0039] Reference 2: JCRandall, J.Macromol.Sci., Rev.Macromol.Chem.Phys., 1989, C29, p.201-317 Reference 3: GJ Ray et al., Macromolecules, 1977, 10, p.773-778 [Measurement of chlorine content and sulfur content] The chlorine content in the chlorosulfonated propylene polymer was determined by burning the sample in a combustion flask method, absorbing the resulting hydrochloric acid in pure water, and then quantifying it with an automatic titrator using a 0.05 mol / l silver nitrate aqueous solution. The sulfur content was measured by the oxygen combustion flask method in accordance with JIS K6233 (1998 edition).

[0040] The chlorosulfonated propylene polymers of Synthesis Examples 1 to 5 were synthesized by the following methods. The following commercially available products were used as raw materials for the synthesis of the chlorosulfonated propylene polymers. PP1: Block polypropylene (manufactured by Japan Polypropylene Corporation, product name: Novatec BC03B, ethylene content: 14 mol%, melt mass flow rate (JIS K 7210): 30 g / 10 min.) PP2: Random polypropylene, manufactured by Japan Polypropylene Co., Ltd., product name: Novatec MG03BD, ethylene content: 3 mol%, melt mass flow rate (JIS K 7210): 30 g / 10 min. Sulfuryl chloride (FUJIFILM Wako Pure Chemical Industries, Ltd.) α,α'-Azobisisobutyronitrile (FUJIFILM Wako Pure Chemical Industries, Ltd.) Pyridine (FUJIFILM Wako Pure Chemical Industries, Ltd.) 1,1,2-Trichloroethane (Tokyo Chemical Industry Co., Ltd.) [Synthesis of chlorosulfonated propylene polymer] In a nitrogen atmosphere, a propylene-based polymer and 1,1,2-trichloroethane were added in a glass pressure reactor according to Table 1, and dissolved at 130 ° C. After completion of dissolution, the reaction liquid was cooled to 120 ° C. Pyridine was added to this polymer solution according to Table 1. Under a condition of 120 ° C., sulfuryl chloride was added at a rate of 0.8 mL / min while dropping a 1,1,2-trichloroethane solution of α,α'-azobisisobutyronitrile adjusted to 2 g / L at a rate of 0.1 mL / min, and the pressure was adjusted to 0.25 MPaG. After adding sulfuryl chloride for a predetermined time according to Table 1, the temperature and pressure were lowered, and nitrogen gas was introduced at a rate of 150 mL / min at 100 ° C. and normal pressure for 1 hour. The solvent was distilled off from the obtained reaction liquid using a double drum dryer, and a chlorosulfonated propylene-based polymer was obtained.

[0041] [Synthesis of chlorinated propylene polymers] The chlorinated propylene polymer of Synthesis Example 6 was synthesized by the following method.

[0042] In a nitrogen atmosphere, a propylene-based polymer and 1,1,2-trichloroethane were added in a glass pressure reactor according to Table 2, and dissolved at 130 ° C. After completion of dissolution, the reaction liquid was cooled to 120 ° C. To this polymer solution, a 1,1,2-trichloroethane solution of α,α'-azobisisobutyronitrile adjusted to 0.5 g / L was dropped at a rate of 0.1 mL / min under 120 ° C. conditions, while chlorine gas was added at a rate of 50 mL / min, and the pressure was adjusted to 0.1 MPaG. After adding chlorine gas for a predetermined time according to Table 1, the temperature and pressure were lowered, and nitrogen gas was introduced at 100 ° C. and normal pressure at a rate of 150 mL / min for 1 hour. The solvent was distilled off from the obtained reaction liquid using a double drum dryer, and a chlorinated propylene-based polymer was obtained.

[0043] The chlorosulfonated polyethylene used in Comparative Example 2 was the product shown below.

[0044] CSM: Chlorosulfonated polyethylene (manufactured by Tosoh Corporation, product name: TOSO-CSM TS-320) Hot melt adhesives were prepared by the following method using chlorosulfonated propylene polymers, chlorinated propylene polymers, and chlorosulfonated polyethylene.

[0045] [How to make hot melt adhesive] Chlorosulfonated propylene polymer or chlorinated propylene polymer, chlorosulfonated polyethylene is placed in a 0.5mm thick mold and preheated at 140℃ for 3 minutes at 50kgf / cm 2 , then 100kgf / cm 2 After 5 minutes of heat pressing, 50kgf / cm at 23℃ 2 The mixture was then cooled and pressed for 3 minutes to prepare a 0.5 mm sheet of hot melt adhesive.

[0046] The resulting hot melt adhesive was evaluated for adhesive strength by the following adhesive strength evaluation method.

[0047] [Method for evaluating tensile shear adhesive strength] Using hot melt adhesive, test pieces for measuring tensile shear adhesive strength were prepared under heat press conditions of 160°C in accordance with JIS K6850, and the tensile shear adhesive strength was measured. The test pieces used were pure aluminum (A1050P) (thickness 3.0 mm, width 25 mm, length 100 mm) and polypropylene (thickness 3.0 mm, width 25 mm, length 100 mm).

[0048] The adhesiveness of the polymer was evaluated based on the measured tensile shear adhesive strength according to Table 3. The evaluation criteria were as follows:

[0049] A: Very good, B: Good, C: Poor As shown in Table 4, Examples 1 to 5 were rated B or higher for both metal and polypropylene, and showed excellent adhesion to both polypropylene and metal. Comparative Example 1 showed excellent adhesion to polypropylene but poor adhesion to metal. Comparative Example 2 showed poor adhesion to both metal and polypropylene.

[0050] [Table 1]

[0051] [Table 2]

[0052] [Table 3]

[0053] [Table 4] [Industrial Applicability]

[0054] The present invention makes it possible to provide an adhesive composition that exhibits good adhesion to various components, particularly to resins such as PP, polyolefin, and PS, and metal components such as aluminum components, aluminum alloy components, and stainless steel components, as well as between dissimilar components such as resin components and metal components, and is therefore expected to be applicable as a material for various structures.

Claims

1. A hot melt adhesive comprising a chlorosulfonated propylene-based polymer in which chlorine and chlorosulfone groups are bonded to a propylene-based polymer.

2. 2. The hot melt adhesive according to claim 1, wherein the chlorine content of the chlorosulfonated propylene polymer is 5.0 to 50.0%.

3. 2. The hot melt adhesive according to claim 1, wherein the sulfur content of the chlorosulfonated propylene polymer is 0.1 to 10.0%.

4. The hot melt adhesive according to any one of claims 1 to 3, wherein the propylene-based polymer is a propylene homopolymer or an ethylene-propylene copolymer.

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