Chlorosulfonated propylene polymer

Abstract

To provide an adhesive having good adhesiveness between a polypropylene resin and a metal, especially a polymer material enabling good adhesion even to a surface-unmodified metal-surfaced base material.　Provided is a chlorosulfonated propylene polymer in which chlorine and chlorosulfone groups are bonded to a propylene polymer, the chlorosulfonated propylene polymer having a chlorine content of 5.0-23.0 wt% and a sulfur content of 0.1-5.0 wt%, and a crystal melting energy of 5-100 J / g as measured by differential scanning calorimeter (DSC).

Description

Chlorosulfonated propylene polymer

[0001] The present invention relates to a chlorosulfonated propylene polymer in which chlorine and chlorosulfone groups are bonded to a propylene polymer.

[0002] Traditionally, welding, riveting, and bolting have been the main methods used to join metals, but with the advancement of science and technology today, the performance and functionality of materials required has become more stringent, and there is a growing demand for adhesion between dissimilar materials. In order to meet these demands, attention is being paid to and development is being made in adhesive technology.

[0003] Furthermore, technological innovations in the automotive and other fields are expected to make bonding technology for dissimilar materials such as polypropylene and metals increasingly important.

[0004] 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).

[0005] 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, packing, gaskets, rolls and escalator handrails, and is also used in applications such as adhesives, coating agents, paints and primers when dissolved in organic solvents.

[0006] However, chlorosulfonated polyethylene has insufficient adhesion to polypropylene resin, and although there are studies on chlorosulfonated polyethylene latex for treating glass fibers for use in bonding rubber (see, for example, Patent Document 1), there have been no studies on bonding to metals, etc.

[0007] On the other hand, chlorosulfonated polypropylene has also been studied (see, for example, Patent Document 2), but an aqueous emulsion was prepared as a primer for polypropylene-based resin, and the adhesion of the coating film was evaluated, and no study was made at all regarding the adhesion of dissimilar materials, such as polypropylene-based resin and metal.

[0008] Japan Adhesion Society Journal Vol. 54 No. 6 (2018) Section 212~

[0009] Japanese Patent Publication No. 2020-83918 Japanese Patent Publication No. 2008-127436

[0010] The present invention has been made in view of the above problems, and an object of the present invention is to provide a chlorosulfonated propylene polymer that can exhibit good adhesion between dissimilar materials, i.e., resins such as polypropylene and metals, while minimizing the influence of surface treatment conditions.

[0011] The present inventors have conducted extensive research to solve the above problems and have completed the present invention, which relates to the following items [1] to [6].

[0012] [1] A chlorosulfonated propylene polymer in which chlorine and chlorosulfone groups are bonded to a propylene polymer, the chlorine content being 5.0 to 23.0 wt % and the sulfur content being 0.1 to 5.0 wt %, and the crystalline melting energy measured by a differential scanning calorimeter (DSC) being 5 to 100 J / g.

[0013] [2] The chlorosulfonated propylene polymer according to [1], which has a crystalline melting point of 80 to 150°C as measured by a differential scanning calorimeter (DSC).

[0014] [3] The chlorosulfonated propylene polymer according to [1] or [2], wherein the propylene polymer is a propylene homopolymer or an ethylene-propylene copolymer.

[0015] [4] The chlorosulfonated propylene polymer according to [3], wherein the ethylene-propylene copolymer has an ethylene content of 20 mol% or less.

[0016] [5] An adhesive comprising the chlorosulfonated propylene polymer according to any one of [1] to [4].

[0017] [6] A hot melt adhesive containing the chlorosulfonated propylene polymer according to any one of [1] to [4].

[0018] The chlorosulfonated propylene polymer of the present invention makes it possible to produce an adhesive that exhibits good adhesion to dissimilar materials such as polypropylene resins and metals.

[0019] The present invention will be described in detail below.

[0020] A chlorosulfonated propylene polymer according to one embodiment of the present invention is a chlorosulfonated propylene polymer in which chlorine and chlorosulfone groups are bonded to a propylene polymer, the chlorosulfonated propylene polymer having a chlorine content of 5.0 to 23.0% by weight and a sulfur content of 0.1 to 5.0% by weight, and having a crystalline melting energy of 5 to 100 J / g as measured by a differential scanning calorimeter (DSC).

[0021] The chlorine content of the chlorosulfonated propylene polymer is 5.0% by weight or more, preferably 8.0% by weight or more, and more preferably 10.0% by weight or more, in order to obtain excellent adhesion, particularly to metals. Furthermore, the chlorine content is 23.0% by weight or less, preferably 22.0% by weight or less, more preferably 21.0% by weight or less, and even more preferably 20.0% by weight or less, in order to obtain excellent adhesion, particularly to low-polarity resins such as polypropylene.

[0022] The sulfur content of the chlorosulfonated propylene polymer is 0.1 wt % or more, preferably 0.2 wt % or more, more preferably 0.3 wt % or more, and even more preferably 0.4 wt % or more, because excellent adhesion, particularly excellent adhesion to metal, is obtained. Also, the sulfur content is 5.0 wt % or less, preferably 4.0 wt % or less, more preferably 3.0 wt % or less, and even more preferably 2.0 wt % or less, because excellent stability of the polymer is obtained.

[0023] The chlorosulfonated propylene polymer is a crystalline polymer, and has a crystalline melting energy measured by differential scanning calorimetry (DSC) of 5 to 100 J / g. In order to obtain excellent material strength and excellent adhesion to low-polarity resins such as polypropylene, the crystalline melting energy measured by DSC is 5 J / g or more, preferably 8 J / g or more, more preferably 10 J / g or more, and even more preferably 12 J / g or more. Furthermore, in order to obtain excellent adhesion, particularly excellent adhesion to metals, the crystalline melting energy measured by DSC is 100 J / g or less, preferably 80 J / g or less, more preferably 70 J / g or less, and even more preferably 60 J / g or less.

[0024] The crystalline melting point of the chlorosulfonated propylene polymer measured by DSC is preferably 80° C. or higher, more preferably 85° C. or higher, and even more preferably 90° C. or higher in order to obtain excellent adhesion to low-polarity resins such as polypropylene. Furthermore, in order to enable processing at low temperatures, the crystalline melting point measured by DSC is preferably 150° C. or lower, more preferably 140° C. or lower, even more preferably 130° C. or lower, and even more preferably 125° C. or lower.

[0025] The chlorosulfonated propylene polymer may be obtained by any method, and can be obtained, for example, by chlorosulfonating a raw material propylene polymer that constitutes the chlorosulfonated propylene polymer.

[0026] Examples of propylene polymers that are raw materials for chlorosulfonated propylene 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 an α-olefin are copolymerized, syndiotactic polypropylene, atactic polypropylene, and long-chain branched polypropylene. Examples of α-olefins 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. Products sold under the trade names Prime Polypro by Prime Polymer Co., Ltd., Novatec PP, Wintec, Newcon, and Newstrene by Japan Polypropylene Corporation, and Noblen, Excellen, and Sumitic by Sumitomo Chemical Co., Ltd. are available. These polypropylenes may be used alone or in combination of two or more. Because of their excellent adhesion to low-polarity resins such as polypropylene and to metals, the propylene-based polymers used as raw materials are preferably propylene homopolymers or ethylene-propylene copolymers, more preferably ethylene-propylene copolymers, and among ethylene-propylene copolymers, block polypropylenes in which ethylene is block copolymerized are particularly preferred. Note that block polypropylenes are also sometimes called impact-resistant polypropylenes, impact polypropylenes, impact copolymers, ICPs, and the like, and these are all encompassed by this term. The content of ethylene units copolymerized in random polypropylenes and block polypropylenes is preferably 20 mol% or less, more preferably 18 mol% or less, and even more preferably 15 mol% or less, because of their excellent adhesion to low-polarity resins such as polypropylene and to metals.

[0027] The method for obtaining a chlorosulfonated propylene polymer is not particularly limited, and examples thereof include a solution method in which a propylene polymer is uniformly dissolved in an inert solvent and reacted, a suspension method in which a propylene polymer is suspended in a solvent and reacted, a dissolution method in which a propylene polymer is dissolved in the absence of a solvent and reacted, etc. Among these, the solution method, which allows uniform chlorination and chlorosulfonation of a propylene polymer, is preferred.

[0028] The solvent used for 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, with trichloroethane being particularly preferred due to its favorable reactivity.

[0029] The chlorosulfonating agent used in chlorosulfonating a propylene polymer is not particularly limited, and sulfur dioxide, chlorine, sulfuryl chloride, and the like may be used alone or in combination. Furthermore, a catalyst that promotes the chlorosulfonation reaction may be used as needed. Examples of the catalyst include azo compounds and organic peroxides. Examples of azo compounds include α,α'-azobisisobutyronitrile, azobiscyclohexanecarbonitrile, and 2,2'-azobis(2,4-dimethylvaleronitrile). Examples of organic peroxides include benzoyl peroxide, acetyl peroxide, t-butyl peroxide, and t-butyl perbenzoate. Azo compounds are preferred because of their high handling stability, and α,α'-azobisisobutyronitrile is particularly preferred because it promotes appropriate chlorination and chlorosulfonation reactions. Furthermore, amino compounds such as pyridine and quinoline, or phosphate ester compounds may be added as co-catalysts to promote the chlorosulfonation reaction, as needed.

[0030] The chlorinating agent used in 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. Furthermore, a catalyst or the like that promotes the chlorination reaction may be used as needed. Examples of the catalyst include azo compounds and organic peroxides. Examples of azo compounds include α,α'-azobisisobutyronitrile, azobiscyclohexanecarbonitrile, and 2,2'-azobis(2,4-dimethylvaleronitrile). Examples of organic peroxides include benzoyl peroxide, acetyl peroxide, t-butyl peroxide, and t-butyl perbenzoate. Azo compounds are preferred because of their high stability in handling, and α,α'-azobisisobutyronitrile is particularly preferred because it allows for appropriate chlorination and chlorosulfonation reactions to proceed. Furthermore, amino compounds such as pyridine and quinoline, or phosphate ester compounds may be added as co-catalysts that promote the chlorination reaction, as needed.

[0031] The reaction temperature during chlorosulfonation or chlorination is not particularly limited and can be appropriately selected depending on the melting point of the raw polymer, etc., and is preferably 50 to 150° C., more preferably 60 to 130° C., taking into consideration reactivity and ease of handling. 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.

[0032] 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 in removing sulfur dioxide gas or hydrogen chloride under reduced pressure.

[0033] 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 include hindered phenol-based antioxidants such as 4-t-butylcatechol, 2,6-di-t-butyl-p-cresol, and triethylene glycol bis[3-(3-t-butyl-4-hydroxy-5-methylphenyl)propionate], and epoxy compounds such as epoxidized polybutadiene and bisphenol A resin. These may be used alone or in combination of two or more. The timing of adding the additive is not particularly limited, but considering 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 residual gas.

[0034] 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.

[0035] The chlorosulfonated propylene polymer can be used as an adhesive by adding a crosslinking agent, a crosslinking aid, an acid acceptor, a plasticizer, a solvent, a viscosity modifier, a flexibility imparting agent, an inorganic filler, an antioxidant, an antiaging agent, an adhesion promoter, a silane coupling agent, etc. The amounts of these additives to be added may be conventional amounts as long as they do not contradict the object of the present invention.

[0036] The chlorosulfonated propylene polymer can be used as an adhesive that exhibits excellent adhesion to various substrates, particularly for bonding dissimilar materials such as resins (e.g., polypropylene) to metals. For metals, such as iron, stainless steel, steel, carbon steel, and aluminum, as well as alloys thereof, metal oxides, and metal hydroxides, the adhesive exhibits excellent adhesion to substrates having such metals at least on their surfaces, regardless of whether surface treatment or surface modification, such as primer treatment, is performed. In particular, the adhesive can be used as a hot-melt adhesive. A hot-melt adhesive is an adhesive that is solid at room temperature but becomes fluid when heated, can be applied to objects such as substrates and adherends, and hardens and adheres when cooled.

[0037] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

[0038] In the examples, the ethylene content of the propylene polymer, and the chlorine content, sulfur content, melting point, heat of fusion, molecular weight, and adhesive strength of the chlorosulfonated propylene polymer were measured as follows:

[0039] [Measurement of ethylene content of propylene polymer] The ethylene content of the propylene polymer was １３ Measurement was performed by C-NMR.

[0040] The solvent was 1,1,2,2-tetrachloroethane-d ２ At 130°C 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.

[0041] Reference 2: J. C. Randall, J. Macromol. Sci., Rev. Macromol. Chem. Phys., 1989, C29, pp. 201-317 Reference 3: G. J. Ray et al., Macromolecules, 1977, 10, pp. 773-778 [Measurement of Chlorine Content and Sulfur Content] The chlorine content in a chlorosulfonated propylene polymer was determined by combusting a sample using 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 aqueous silver nitrate solution. The sulfur content was measured using an oxygen combustion flask method in accordance with JIS K6233 (1998 edition).

[0042] [Measurement of crystalline melting energy and crystalline melting point] Using a differential scanning calorimeter (DSC3500 Sirius, manufactured by NETZSCH), the temperature was repeatedly raised and lowered under the following conditions in a nitrogen gas atmosphere, and the crystalline melting energy and crystalline melting point were measured from the DSC curve measured during the second temperature rise. The crystalline melting energy was calculated by calculating the calorific value from the area of ​​the endothermic peak in the DSC curve, dividing this by the sample weight, and converting it into J / g units. The temperature at the peak top of the endothermic peak in the DSC curve was taken as the crystalline melting point.

[0043] The chlorosulfonated propylene polymers of Examples 1 to 7 and Comparative Example 1 were synthesized by the following methods using the following raw materials.

[0044] [Raw Materials] The following commercially available products were used as raw materials for the synthesis of chlorosulfonated propylene polymers.

[0045] PP1: Propylene homopolymer (manufactured by Japan Polypropylene Corporation, trade name: Novatec SA03, ethylene content: 0 mol%, melt mass-flow rate (JIS K 7210): 30 g / 10 min) PP2: Block polypropylene (manufactured by Japan Polypropylene Corporation, trade name: Novatec BC03B, ethylene content: 14 mol%, melt mass-flow rate (JIS K 7210): 30 g / 10 min) PP3: Random polypropylene (manufactured by Japan Polypropylene Corporation, trade name: Novatec MG03BD, ethylene content: 3 mol%, melt mass-flow rate (JIS K 7210): 30 g / 10 min) Sulfuryl chloride (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) α,α'-Azobisisobutyronitrile (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) Pyridine (manufactured by FUJIFILM Wako Pure Chemical Industries, Ltd.) 1,1,2-trichloroethane (manufactured by Tokyo Chemical Industry Co., Ltd.) [Synthesis of chlorosulfonated propylene polymer] In a nitrogen atmosphere, a propylene polymer and 1,1,2-trichloroethane were placed in a glass pressure reactor according to Table 1 and dissolved at 130°C. After dissolution was completed, the reaction solution was cooled to 120°C. To this polymer solution, pyridine was added according to Table 1. At 120°C, a 1,1,2-trichloroethane solution of α,α'-azobisisobutyronitrile adjusted to 2 g / L was added dropwise at a rate of 0.1 mL / min, while sulfuryl chloride was added at a rate of 0.8 mL / min, and the pressure was adjusted to 0.25 MPaG. After sulfuryl chloride was added for a predetermined time according to Table 1, the temperature and pressure were decreased, and nitrogen gas was introduced at a rate of 150 mL / min for 1 hour at 100°C and atmospheric pressure. The solvent was distilled off from the resulting reaction liquid using a double drum dryer, yielding a chlorosulfonated propylene polymer.

[0046] [Synthesis of Chlorinated Propylene Polymer] The chlorinated propylene polymers of Comparative Examples 2 and 3 were synthesized by the following method.

[0047] A propylene polymer and 1,1,2-trichloroethane were placed in a glass pressure reactor under a nitrogen atmosphere according to Table 2 and dissolved at 130°C. After dissolution was complete, the reaction solution 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 added dropwise at a rate of 0.1 mL / min at 120°C, 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 a rate of 150 mL / min at 100°C and atmospheric pressure for 1 hour. The solvent was distilled off from the resulting reaction solution using a double drum dryer, yielding a chlorinated propylene polymer.

[0048] The tensile shear adhesive strength of Examples 1 to 7 and Comparative Examples 1 to 4 was evaluated by the following evaluation method. The polymers used for the evaluation were the chlorosulfonated propylene polymers, chlorinated propylene polymers, and chlorosulfonated polyethylenes synthesized in Examples 1 to 7 and Comparative Examples 1 to 3.

[0049] [Method for evaluating tensile shear adhesive strength] The polymer to be evaluated was placed in a 0.5 mm thick mold, preheated at 140°C for 3 minutes, and subjected to a tensile shear strength of 50 kgf / cm. ２ , then 100 kgf / cm ２ , after 5 minutes of heat pressing, 50 kgf / cm at 23°C ２ The sheet was then subjected to a 160°C hot press in accordance with JIS K6850 to prepare a 0.5 mm thick sheet for adhesion testing. Tensile shear adhesive strength test specimens were prepared using the obtained sheet, and the tensile shear adhesive strength was measured. Pure aluminum (A1050P) specimens (thickness: 3.0 mm, width: 25 mm, length: 100 mm) and polypropylene specimens (thickness: 3.0 mm, width: 25 mm, length: 100 mm) were used.

[0050] The adhesiveness of the polymer to be evaluated was evaluated from the measured tensile shear adhesive strength according to Table 3. The evaluation criteria were as follows:

[0051] A: Very good, B: Good, C: Poor As can be seen from Table 4, Examples 1 to 7 received ratings of B or higher for both aluminum and polypropylene, demonstrating excellent adhesion to both polypropylene and metal. Comparative Example 1 had excellent adhesion to metal but poor adhesion to polypropylene. Comparative Examples 2 and 3 had excellent adhesion to polypropylene but poor adhesion to metal.

[0052]

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[0055]

[0056] The present invention makes it possible to provide an adhesive composition that exhibits good adhesive properties for bonding dissimilar materials, particularly polypropylene and metal, and is therefore expected to be used as a material for various structures.

[0057] While the present invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention.

[0058] The entire contents of the specification, claims and abstract of Japanese Patent Application No. 2023-148995 filed on September 14, 2023 are hereby incorporated by reference as the disclosure of the present invention.

Claims

1. A chlorosulfonated propylene polymer in which chlorine and chlorosulfone groups are bonded to a propylene polymer, the chlorine content being 5.0 to 23.0% by weight and the sulfur content being 0.1 to 5.0% by weight, and the crystalline melting energy measured by a differential scanning calorimeter (DSC) being 5 to 100 J / g.

2. The chlorosulfonated propylene polymer according to claim 1, which has a crystalline melting point of 80 to 150° C. as measured by differential scanning calorimetry (DSC).

3. The chlorosulfonated propylene polymer according to claim 1, wherein the propylene polymer is a propylene homopolymer or an ethylene-propylene copolymer.

4. The chlorosulfonated propylene polymer according to claim 3, wherein the ethylene-propylene copolymer has an ethylene content of 20 mol % or less.

5. An adhesive comprising the chlorosulfonated propylene polymer according to any one of claims 1 to 4.

6. A hot melt adhesive comprising the chlorosulfonated propylene polymer according to any one of claims 1 to 4.

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