Polyphenylene sulfide resin composition for plastic fasteners

Abstract

The objective is to obtain a polyphenylene sulfide resin composition for plastic fasteners that combines the chemical resistance and flame retardancy inherent in PPS resin with flexibility, fluidity, and heat aging resistance under long-term high-temperature environments, and furthermore, allows for easy fastening when used as a plastic fastener, and suppresses cracking at the hinge, during fitting, and during fastening. [Solution] A polyphenylene sulfide resin composition for plastic fasteners comprising (a) a polyphenylene sulfide resin, (b) a silicone elastomer having a crosslinked structure, and (c) a silane coupling agent, wherein the amount of (c) the silane coupling agent is 0.2 parts by mass or more and 1.9 parts by mass or less per 100 parts by mass of (a) the polyphenylene sulfide resin, and the degree of aggregation obtained by dividing the number average dispersion particle diameter of the silicone elastomer having a crosslinked structure in the resin composition by its average primary particle diameter is 10 or less.

Description

[Technical Field]

[0001] The present invention relates to a polyphenylene sulfide resin composition for plastic fasteners that combines the chemical resistance and flame retardancy inherent in polyphenylene sulfide resin with flexibility, fluidity, and heat aging resistance in long-term high-temperature environments, and furthermore, when used as a plastic fastener, allows for easy fastening and suppresses cracking at the hinge portion, during fitting, and during fastening. [Background technology]

[0002] Plastic fasteners, such as clips, clamps, cable ties, dot fasteners, wire fasteners, and hook-and-loop fasteners, have widely used polypropylene resin and polyamide resin, which have excellent flexibility and toughness, for the purpose of ease of fastening and preventing cracking of the hinge, mating, and fastening parts.

[0003] On the other hand, for plastic fasteners used in high-temperature environments or environments in contact with chemicals, the application of polyphenylene sulfide (hereinafter sometimes abbreviated as PPS) resin, which has excellent heat resistance, chemical resistance, and flame retardancy, is being considered. However, PPS resin inherently has low flexibility and toughness, and when applied to plastic fasteners, it requires force to fasten them, and cracking at the hinge, mating, and fastening becomes a problem. In addition, PPS resin has the problem of becoming brittle and degrading when exposed to high-temperature environments exceeding 150°C for a long period of time.

[0004] Examples of attempts to improve these aspects have been reported. For example, Patent Document 1 describes an injection-molded part and fastener that exhibit excellent impact strength and impact strength retention after 1000 hours at 165°C by using a composition containing PPS resin and a crosslinking impact resistance modifier. Patent Document 2 describes a plastic fastener that exhibits excellent toughness and high-temperature long-term durability at 165°C by using PPS resin and a thermoplastic resin having a melting point or glass transition temperature of 150°C or higher, wherein the thermoplastic resin forms a dispersed phase in which the number-average dispersed particle diameter is 500 nm or less. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Special Publication No. 2017-500404 [Patent Document 2] Japanese Patent Publication No. 2019-6884 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] In recent years, the applications of plastic fasteners have expanded, and the resin compositions used are expected to have excellent productivity while also possessing heat aging resistance under long-term high-temperature environments. Plastic fasteners have thin walls and long shapes, and from a productivity standpoint, it is necessary to produce a large number of fasteners per molding cycle. Therefore, the resin composition needs to be fluid, and balancing flexibility and heat aging resistance is a challenge.

[0007] However, Patent Document 1 suffers from insufficient heat resistance in long-term high-temperature environments because the crosslinked impact-modifying agent (olefin-based elastomer, etc.) blended into the PPS resin lacks sufficient heat resistance. Furthermore, in the plastic fastener described in Patent Document 2, which is made of a resin composition blended with PPS resin and a thermoplastic resin having a melting point or glass transition temperature of 150°C or higher, if ease of fastening is desired, a large amount of thermoplastic resin must be added to increase the flexibility of the resin composition, making it difficult to achieve compatibility with other properties such as fluidity.

[0008] Therefore, the present invention aims to provide a polyphenylene sulfide resin composition for plastic fasteners that combines the chemical resistance and flame retardancy inherent in PPS resin with flexibility and fluidity, possesses heat aging resistance in long-term high-temperature environments, facilitates fastening when used as a plastic fastener, and suppresses cracking at the hinge portion, during fitting, and during fastening. [Means for solving the problem]

[0009] The inventors of the present invention conducted studies to solve the above problems and found that by combining (a) polyphenylene sulfide resin and (b) a silicone elastomer having a crosslinked structure with a specific amount of (c) a silane coupling agent, and by creating a polyphenylene sulfide resin composition in which aggregation of (b) the silicone elastomer having a crosslinked structure is suppressed, the polyphenylene sulfide resin composition possesses not only the chemical resistance and flame retardancy inherent in (a) polyphenylene sulfide resin, but also flexibility, fluidity, and heat aging resistance, making it easy to fasten when used as a plastic fastener, and suppressing cracking at the hinge portion, during fitting, and during fastening. In other words, the present invention has been made to solve at least a part of the above problems and can be implemented in the following forms.

[0010] (1) A polyphenylene sulfide resin composition for plastic fasteners comprising (a) a polyphenylene sulfide resin, (b) a silicone elastomer having a crosslinked structure, and (c) a silane coupling agent, wherein the amount of (c) the silane coupling agent is 0.2 parts by mass or more and 1.9 parts by mass or less per 100 parts by mass of (a) the polyphenylene sulfide resin, and the degree of aggregation obtained by dividing the number average dispersion particle diameter of the silicone elastomer having a crosslinked structure in the resin composition by its average primary particle diameter is 10 or less. (2)(b) The polyphenylene sulfide resin composition for plastic fasteners according to (1), wherein the average primary particle size of the cross-linked silicone elastomer is 1 μm or more. (3) The polyphenylene sulfide resin composition for plastic fasteners described in (1), wherein in a bending test in accordance with ISO 178 (2010), the bending modulus of the test piece obtained by injection molding the resin composition is 3.0 GPa or less. (4) The polyphenylene sulfide resin composition for plastic fasteners described in (1), wherein the melt viscosity at a shear rate of 1216 / s is 300 Pa·s or less, as measured using a capillograph at 300°C and under the conditions of orifice length L (mm) / orifice diameter D (mm) = 10. (5)(c) The polyphenylene sulfide resin composition for plastic fasteners according to (1), wherein the silane coupling agent has one or more isocyanate groups or epoxy groups. (6)(a) The polyphenylene sulfide resin composition for plastic fasteners according to (1), wherein the nitrogen content of the polyphenylene sulfide resin is 300 ppm or more. (7) Using an amorphous film obtained by hot pressing the resin composition, the absorption spectrum obtained by infrared spectroscopy (transmission method) shows 2850 and 2920 cm⁻¹ -1 The polyphenylene sulfide resin composition for plastic fasteners according to (1), wherein the peak area derived from a methylene group having a peak top nearby is 3 or less. (8) The polyphenylene sulfide resin composition for plastic fasteners described in (1), wherein the tensile strength retention rate calculated by the following formula (A) is 90% or more when measured using an ASTM No. 4 dumbbell obtained by injection molding the resin composition under the conditions of a tensile speed of 10 mm / min, a distance between grips of 64 mm, and an ambient temperature of 23°C. (Tensile strength after heat treatment at 185°C for 1000 hours in air) / (Tensile strength before heat treatment) × 100 ... Formula (A) (9) A plastic fastener made by molding a polyphenylene sulfide resin composition for plastic fasteners described in any of (1) to (8). (10) Plastic fasteners as described in (9), which are selected from cable ties, clips, and clamps. [Effects of the Invention]

[0011] According to the present invention, a polyphenylene sulfide resin composition for plastic fasteners can be obtained that combines the chemical resistance and flame retardancy inherent in PPS resin with flexibility, fluidity, and heat aging resistance under long-term high-temperature environments, and furthermore, when used as a plastic fastener, it is easy to fasten and cracking can be suppressed at the hinge portion, during fitting, and during fastening. [Modes for carrying out the invention]

[0012] Hereinafter, embodiments of the present invention will be described in detail.

[0013] (1)(a) Polyphenylene sulfide resin The (a) polyphenylene sulfide resin used in the present invention is a polymer having a repeating unit represented by the following structural formula.

[0014] [Chemical formula]

[0015] From the viewpoint of heat resistance, a polymer containing 70 mol% or more, and further 90 mol% or more, of the repeating unit represented by the above structural formula is preferable. Further, up to about 30 mol% of the repeating unit of the (a) PPS resin may be composed of a repeating unit having the following structure or the like.

[0016] [Chemical formula]

[0017] Since the melting point of the PPS copolymer having such a structure is lower than 280°C, which is the general melting point of PPS, such a resin composition is advantageous in terms of molding processability.

[0018] Although there is no particular limitation on the weight average molecular weight of the (a) PPS resin used in the present invention, in order to balance the toughness and fluidity of the resin composition and obtain excellent heat aging resistance, the weight average molecular weight is preferably 45,000 to 75,000, more preferably 50,000 to 75,000, and particularly preferably 50,000 to 60,000. When the weight average molecular weight is small, the toughness of the (a) PPS resin itself is low, and the toughness and heat aging resistance of the resin composition are also low, and cracks are likely to occur when applied to a plastic fastener, so 45,000 or more is preferable. On the other hand, when the weight average molecular weight exceeds 75,000, the melt viscosity becomes extremely large, which is not preferable in the molding process of plastic fasteners. In the present invention, a plurality of (a) PPS resins having different weight average molecular weights may be mixed and used.

[0019] The weight-average molecular weight in this invention is calculated using gel permeation chromatography (GPC) manufactured by Senshu Scientific, and is expressed in terms of polystyrene equivalent.

[0020] The (a) PPS resin used in the present invention preferably has a cooling crystallization peak temperature (Tmc) of 200°C or less, obtained by differential scanning calorimetry (DSC). The cooling crystallization peak temperature is more preferably 195°C or less, and particularly preferably 190°C or less. There is no particular lower limit, but a practical lower limit of 100°C or more can be exemplified. The (a) PPS resin having a cooling crystallization peak temperature of 200°C or less can be obtained, for example, by treatment with alkali metals or alkaline earth metals in a post-treatment step described later. The (a) PPS resin obtained by treatment with alkali metals or alkaline earth metals is preferable because the stability of the (a) PPS resin ends during the heat treatment process is improved, thus suppressing oxidative crosslinking of the (a) PPS resin under long-term high-temperature environments exceeding 150°C, and the PPS resin composition has excellent heat aging resistance.

[0021] (a) The cooling crystallization peak temperature of PPS resin is obtained by measuring it under the following conditions in a nitrogen atmosphere using a differential scanning calorimeter (DSC, Q200; TA Instruments Inc.): (a) The PPS resin is heated from 50°C to 340°C at a rate of 20°C / min. Then, it is held at 340°C for 1 minute and cooled down to 100°C at a rate of 20°C / min. The cooling crystallization peak temperature is obtained from the value of the cooling crystallization peak top detected during the cooling process.

[0022] The method for producing the (a) PPS resin used in the present invention will be described below, but the method is not limited to the following, as long as the (a) PPS resin having the above characteristics can be obtained.

[0023] First, we will explain the polyhalogenated aromatic compounds, sulfidizing agents, polymerization solvents, molecular weight regulators, polymerization aids, and polymerization stabilizers used in the manufacturing process.

[0024] [Polyhalogenated aromatic compounds] Polyhalogenated aromatic compounds are compounds that have two or more halogen atoms in one molecule. Specific examples include polyhalogenated aromatic compounds such as p-dichlorobenzene, m-dichlorobenzene, o-dichlorobenzene, 1,3,5-trichlorobenzene, 1,2,4-trichlorobenzene, 1,2,4,5-tetrachlorobenzene, hexachlorobenzene, 2,5-dichlorotoluene, 2,5-dichloro-p-xylene, 1,4-dibromobenzene, 1,4-diiodobenzene, and 1-methoxy-2,5-dichlorobenzene, with p-dichlorobenzene being preferred. Furthermore, in order to introduce carboxyl groups, it is also a preferred embodiment to use carboxyl group-containing dihalogenated aromatic compounds such as 2,4-dichlorobenzoic acid, 2,5-dichlorobenzoic acid, 2,6-dichlorobenzoic acid, and 3,5-dichlorobenzoic acid, as well as mixtures thereof, as copolymer monomers. It is also possible to combine two or more different polyhalogenated aromatic compounds to form copolymers, but it is preferable to use p-dihalogenated aromatic compounds as the main component.

[0025] The amount of polyhalogenated aromatic compound used can be exemplified as being in the range of 0.9 to 2.0 moles, preferably 0.95 to 1.5 moles, and more preferably 1.005 to 1.2 moles per mole of sulfidizing agent, from the viewpoint of obtaining a (a) PPS resin with a viscosity suitable for processing.

[0026] [Sulfide agents] Examples of sulfidating agents include alkali metal sulfides, alkali metal hydroxides, and hydrogen sulfide.

[0027] Specific examples of alkali metal sulfides include lithium sulfide, sodium sulfide, potassium sulfide, rubidium sulfide, cesium sulfide, and mixtures of two or more of these, with sodium sulfide being particularly preferred. These alkali metal sulfides can be used as hydrates, aqueous mixtures, or in anhydrous form.

[0028] Specific examples of alkali metal hydroxides include sodium hydroxide, potassium hydroxide, lithium hydroxide, rubidium hydroxide, cesium hydroxide, and mixtures of two or more of these, with sodium hydroxide being particularly preferred. These alkali metal hydroxides can be used as hydrates, aqueous mixtures, or in anhydrous form.

[0029] Furthermore, alkali metal sulfides prepared in situ in the reaction system from alkali metal hydroxides and alkali metal hydroxides can also be used. Alternatively, alkali metal sulfides can be prepared from alkali metal hydroxides and alkali metal hydroxides and then transferred to a polymerization tank for use.

[0030] Alternatively, alkali metal sulfides prepared in situ in the reaction system from alkali metal hydroxides such as lithium hydroxide and sodium hydroxide and hydrogen sulfide can also be used. Furthermore, alkali metal sulfides can be prepared from alkali metal hydroxides such as lithium hydroxide and sodium hydroxide and hydrogen sulfide, and then transferred to a polymerization tank for use.

[0031] The amount of sulfidizing agent used in the preparation shall refer to the remaining amount after deducting any loss of sulfidizing agent before the polymerization reaction begins due to dehydration or other processes from the actual amount prepared.

[0032] Furthermore, alkali metal hydroxides and / or alkaline earth metal hydroxides can be used in combination with sulfidating agents. Specific examples of alkali metal hydroxides include, for example, sodium hydroxide, potassium hydroxide, lithium hydroxide, rubidium hydroxide, cesium hydroxide, and mixtures of two or more of these, while specific examples of alkaline earth metal hydroxides include, for example, calcium hydroxide, strontium hydroxide, and barium hydroxide, with sodium hydroxide being particularly preferred.

[0033] When using alkali metal hydroxide as a sulfidating agent, it is particularly preferable to use alkali metal hydroxide simultaneously. Examples of the amount used include 0.95 to 1.20 moles, preferably 1.00 to 1.15 moles, and more preferably 1.005 to 1.100 moles per mole of alkali metal hydroxide.

[0034] [Polymerization solvent] Organic polar solvents are preferred as polymerization solvents. Specific examples include N-alkylpyrrolidones such as N-methyl-2-pyrrolidone and N-ethyl-2-pyrrolidone, caprolactams such as N-methyl-ε-caprolactam, aprotic organic solvents such as 1,3-dimethyl-2-imidazolidinone, N,N-dimethylacetamide, N,N-dimethylformamide, hexamethylphosphate triamide, dimethyl sulfone, and tetramethylene sulfoxide, as well as mixtures thereof. These are all preferred due to their high reaction stability. Among these, N-methyl-2-pyrrolidone (hereinafter sometimes abbreviated as NMP) is particularly preferred.

[0035] The amount of organic polar solvent used is selected to be in the range of 2.0 to 10 moles, preferably 2.25 to 6.0 moles, and more preferably 2.5 to 5.5 moles per mole of sulfidating agent.

[0036] [Molecular weight regulator] A monohalogen compound (not necessarily an aromatic compound) can be used in combination with the polyhalogenated aromatic compound to form the ends of the resulting (a) PPS resin, or to adjust the polymerization reaction or molecular weight.

[0037] [Polymerization aid] In order to obtain a relatively high degree of polymerization (a) PPS resin in a shorter time, it is also preferable to use polymerization aids. Here, polymerization aids refer to substances that have the effect of increasing the viscosity of the obtained (a) PPS resin. Specific examples of such polymerization aids include, for example, organic carboxylates, water, alkali metal chlorides, organic sulfonates, alkali metal sulfates, alkaline earth metal oxides, alkali metal phosphates, and alkaline earth metal phosphates. These can be used individually or in combination of two or more. Among these, organic carboxylates, water, and alkali metal chlorides are preferred, and among organic carboxylates, alkali metal carboxylates are preferred, and among alkali metal chlorides, lithium chloride is preferred.

[0038] The alkali metal carboxylates mentioned above are those with the general formula R(COOM) n The compound is represented by the formula (wherein R is an alkyl group, cycloalkyl group, aryl group, alkylaryl group, or arylalkyl group having 1 to 20 carbon atoms; M is an alkali metal selected from lithium, sodium, potassium, rubidium, and cesium; and n is an integer from 1 to 3). Alkali metal carboxylates can also be used as hydrates, anhydrides, or aqueous solutions. Specific examples of alkali metal carboxylates include lithium acetate, sodium acetate, potassium acetate, sodium propionate, lithium valerate, sodium benzoate, sodium phenylacetate, potassium p-tolulate, and mixtures thereof.

[0039] Alkali metal carboxylates may be formed by reacting an organic acid with one or more compounds selected from the group consisting of alkali metal hydroxides, alkali metal carbonates, and alkali metal bicarbonates, in approximately equal amounts. Among the alkali metal carboxylates, lithium salts have high solubility in the reaction system and a large additive effect, but are expensive, while potassium, rubidium, and cesium salts are thought to have insufficient solubility in the reaction system. Therefore, sodium acetate, which is inexpensive and has moderate solubility in the polymerization system, is the most preferred choice.

[0040] When these alkali metal carboxylates are used as polymerization aids, the amount used is usually in the range of 0.01 to 2 moles per mole of alkali metal sulfide added, and in order to obtain a higher degree of polymerization, the range of 0.1 to 0.6 moles is preferable, and the range of 0.2 to 0.5 moles is more preferable.

[0041] Furthermore, when water is used as a polymerization aid, the amount added is usually in the range of 0.3 to 15 moles per mole of alkali metal sulfide used in the preparation. In order to obtain a higher degree of polymerization, a range of 0.6 to 10 moles is preferable, and a range of 1 to 5 moles is more preferable.

[0042] It is certainly possible to use two or more of these polymerization aids in combination. For example, using alkali metal carboxylates and water together allows for higher molecular weight synthesis with smaller amounts of each agent.

[0043] There are no specific timing requirements for adding these polymerization aids; they may be added during the pre-processing stage, at the start of polymerization, or during polymerization, as described later. They may also be added in multiple stages. However, when using alkali metal carboxylates as polymerization aids, it is preferable to add them simultaneously at the start of the pre-processing stage or at the start of polymerization, as this makes the addition easier. When using water as a polymerization aid, it is effective to add it during the polymerization reaction after charging the polyhalogenated aromatic compound.

[0044] [Polymerization stabilizer] Polymerization stabilizers can be used to stabilize the polymerization reaction system and prevent side reactions. Polymerization stabilizers contribute to the stabilization of the polymerization reaction system and suppress undesirable side reactions. One indicator of a side reaction is the formation of thiophenol, and the formation of thiophenol can be suppressed by adding a polymerization stabilizer. Specific examples of polymerization stabilizers include compounds such as alkali metal hydroxides, alkali metal carbonates, alkaline earth metal hydroxides, and alkaline earth metal carbonates. Among these, alkali metal hydroxides such as sodium hydroxide, potassium hydroxide, and lithium hydroxide are preferred. The alkali metal carboxylates mentioned above also act as polymerization stabilizers. Furthermore, as previously stated, when using alkali metal hydroxides as sulfidating agents, it is particularly preferable to use alkali metal hydroxides simultaneously. In this case, excess alkali metal hydroxides relative to the sulfidating agent can also act as polymerization stabilizers.

[0045] These polymerization stabilizers can be used individually or in combination of two or more. It is preferable to use the polymerization stabilizer in a ratio of typically 0.02 to 0.2 moles, preferably 0.03 to 0.1 moles, and more preferably 0.04 to 0.09 moles, per mole of alkali metal sulfide. If the ratio is too low, the stabilization effect will be insufficient, while conversely, if it is too high, it will be economically disadvantageous or tend to reduce the polymer yield.

[0046] There is no specific timing for adding the polymerization stabilizer; it can be added at any of the following stages: during the pre-processing stage, at the start of polymerization, or during polymerization. It can also be added in multiple stages. However, it is more preferable to add it simultaneously at the start of the pre-processing stage or at the start of polymerization, as this is easier.

[0047] Next, a preferred method for producing (a) PPS resin used in the present invention will be described in detail, step by step, including the pre-processing, polymerization reaction, recovery, and post-processing steps, but of course, the invention is not limited to this method.

[0048] [Pre-process] (a) In the method for producing PPS resin, sulfidating agents are usually used in hydrate form, but it is preferable to heat the mixture containing the organic polar solvent and the sulfidating agent before adding the polyhalogenated aromatic compound to remove excess water from the system.

[0049] Furthermore, as mentioned above, sulfidating agents prepared from alkali metal hydroxides and alkali metal hydroxides in situ within the reaction system or in a separate tank from the polymerization tank can also be used. There are no particular limitations to this method, but preferably, under an inert gas atmosphere, alkali metal hydroxides and alkali metal hydroxides are added to an organic polar solvent at a temperature range of room temperature to 150°C, preferably room temperature to 100°C, and the temperature is raised to at least 150°C, preferably 180 to 260°C, to remove the water by distillation. Polymerization aids may be added at this stage. In addition, toluene or the like may be added to accelerate the distillation of water.

[0050] In the polymerization reaction, the amount of water in the polymerization system is preferably 0.3 to 10.0 moles per mole of sulfidizing agent added. Here, the amount of water in the polymerization system is the amount of water added to the polymerization system minus the amount of water removed from the polymerization system. The water added may be in any form, such as water, aqueous solution, or crystal water.

[0051] [Polymerization reaction process] (a) PPS resin is produced by reacting a sulfidating agent and a polyhalogenated aromatic compound in an organic polar solvent at a temperature range of 200 to 290°C.

[0052] To initiate the polymerization reaction, the organic polar solvent, sulfidating agent, and polyhalogenated aromatic compound are mixed, preferably under an inert gas atmosphere, at a temperature range of room temperature to 240°C, more preferably 100 to 230°C. A polymerization aid may be added at this stage. The order in which these raw materials are added does not matter, and they can be added simultaneously.

[0053] The mixture is typically heated to a temperature in the range of 200-290°C. There are no particular restrictions on the heating rate, but a rate of 0.01-5°C / min is usually selected, with a range of 0.1-3°C / min being more preferable.

[0054] Generally, the temperature is eventually raised to 250-290°C, and the reaction is carried out at that temperature for typically 0.25-50 hours, preferably 0.5-20 hours.

[0055] A method of reacting the material at, for example, 200-260°C for a certain period of time before reaching the final temperature, and then raising the temperature to 270-290°C, is effective in obtaining a higher degree of polymerization. In this case, the reaction time at 200-260°C is usually selected in the range of 0.25-20 hours, and preferably in the range of 0.25-10 hours.

[0056] Furthermore, in order to obtain polymers with a higher degree of polymerization, it may be effective to carry out polymerization in multiple steps. When carrying out polymerization in multiple steps, it is effective to proceed when the conversion rate of the polyhalogenated aromatic compound in the system at 245°C reaches 40 mol% or more, preferably 60 mol%.

[0057] The conversion rate of polyhalogenated aromatic compounds (abbreviated here as PHA) is calculated using the following formula. The amount of remaining PHA can usually be determined by gas chromatography.

[0058] (A) When polyhalogenated aromatic compounds are added in excess in molar ratio relative to alkali metal sulfides Conversion rate = [Amount of PHA added (moles) - Amount of PHA remaining (moles)] / [Amount of PHA added (moles) - Excess PHA (moles)] (B) Cases other than those in (A) above Conversion rate = [Amount of PHA added (moles) - Amount of PHA remaining (moles)] / [Amount of PHA added (moles)]

[0059] [Recovery Process] (a) In the method for producing PPS resin, after polymerization is complete, a solid is recovered from the polymerization reaction product containing the polymer and solvent. The method for recovering (a) PPS resin in the present invention is not particularly limited. Typical recovery methods include a method of cooling and filtering the precipitated (a) PPS resin, and a method of distilling off the organic solvent. One preferred recovery method is to recover particulate polymer by slow cooling after the polymerization reaction is complete. There are no particular restrictions on the slow cooling rate at this time, but it is usually around 0.1 to 3°C / min. It is not necessary to slow cool at the same rate throughout the entire slow cooling process, and a method such as slow cooling at 0.1 to 1°C / min until the polymer particles crystallize and precipitate, and then slow cooling at a rate of 1°C / min or more may be adopted.

[0060] [Post-processing steps] (a) The PPS resin may be produced through the polymerization and recovery process described above, and then subjected to acid treatment, hot water treatment, cleaning with organic solvents, or alkali metal or alkaline earth metal treatment.

[0061] When acid treatment is performed, the following applies: (a) The acid used for acid treatment of PPS resin is not particularly limited as long as it does not have the effect of decomposing the PPS resin, and examples include acetic acid, hydrochloric acid, sulfuric acid, phosphoric acid, silicic acid, carbonate, and propyl acid, among which acetic acid and hydrochloric acid are more preferably used, but those that decompose and degrade the PPS resin, such as nitric acid, are undesirable.

[0062] Methods for acid treatment include immersing the (a) PPS resin in an acid or an aqueous solution of acid, and stirring or heating may be performed as needed. For example, when using acetic acid, sufficient effect can be obtained by immersing the PPS resin powder in an aqueous solution with a pH of 4 heated to 80-200°C and stirring for 30 minutes. The pH after treatment may be 4 or higher, for example, around pH 4-8. It is preferable to wash the acid-treated (a) PPS resin several times with water or warm water to remove any residual acid or salts. The water used for washing is preferably distilled water or deionized water so as not to impair the desirable chemical modification effect of the (a) PPS resin by the acid treatment.

[0063] When performing hot water treatment, the following applies: (a) When treating PPS resin with hot water, it is preferable to set the temperature of the hot water to 100°C or higher, more preferably 120°C or higher, even more preferably 150°C or higher, and particularly preferably 170°C or higher. Temperatures below 100°C are undesirable because the desired chemical modification effect on (a) PPS resin is small.

[0064] To achieve the desired chemical modification effect of (a)PPS resin by hot water washing, it is preferable to use distilled water or deionized water. There are no particular restrictions on the hot water treatment operation, and it can be carried out by adding a predetermined amount of (a)PPS resin to a predetermined amount of water and heating and stirring in a pressure vessel, or by continuously applying hot water treatment. A higher water ratio is preferable for (a)PPS resin to water, but typically a bath ratio of 200g or less of (a)PPS resin per liter of water is selected.

[0065] Furthermore, since the decomposition of end groups is undesirable, it is desirable to perform the treatment under an inert atmosphere to avoid this. In addition, it is preferable to wash the (a) PPS resin that has completed this hot water treatment operation several times with hot water to remove any remaining components.

[0066] When washing with an organic solvent, the following applies: (a) The organic solvent used to wash the PPS resin is not particularly limited as long as it does not have the effect of decomposing the PPS resin, for example, nitrogen-containing polar solvents such as N-methyl-2-pyrrolidone, dimethylformamide, dimethylacetamide, 1,3-dimethylimidazolidinone, hexamethylphosphorusamide, piperadinons, etc., sulfoxide / sulfone solvents such as dimethyl sulfoxide, dimethyl sulfone, sulfolane, etc., ketone solvents such as acetone, methyl ethyl ketone, diethyl ketone, acetophenone, dimethyl ether, dipropyl ether, dioxane, tetra Examples of suitable solvents include ether-based solvents such as hydrofuran, halogen-based solvents such as chloroform, methylene chloride, trichloroethylene, ethylene dichloride, perchloroethylene, monochloroethane, dichloroethane, tetrachloroethane, perchloroethane, and chlorobenzene, alcohol-phenol-based solvents such as methanol, ethanol, propanol, butanol, pentanol, ethylene glycol, propylene glycol, phenol, cresol, polyethylene glycol, and polypropylene glycol, and aromatic hydrocarbon-based solvents such as benzene, toluene, and xylene. Among these organic solvents, the use of N-methyl-2-pyrrolidone, acetone, dimethylformamide, and chloroform is particularly preferred. These organic solvents may be used individually or in mixtures of two or more.

[0067] Methods for cleaning with organic solvents include immersing (a) PPS resin in the organic solvent, and stirring or heating may be performed as needed. There are no particular restrictions on the cleaning temperature when cleaning (a) PPS resin with organic solvents; any temperature from room temperature to approximately 300°C can be selected. Cleaning efficiency tends to increase with higher cleaning temperatures, but usually sufficient results can be obtained at cleaning temperatures from room temperature to 150°C. It is also possible to clean under pressure in a pressure vessel at a temperature above the boiling point of the organic solvent. There are also no particular restrictions on the cleaning time. Depending on the cleaning conditions, sufficient results can usually be obtained by cleaning for 5 minutes or more in the case of batch cleaning. Continuous cleaning is also possible.

[0068] Methods for treating alkali metals and alkaline earth metals include adding alkali metal salts and alkaline earth metal salts before, during, or after the above-mentioned preceding process; adding alkali metal salts and alkaline earth metal salts into the polymerization vessel before, during, or after the polymerization process; or adding alkali metal salts and alkaline earth metal salts at the first, intermediate, or final stage of the above-mentioned washing process. Among these, the easiest method is to remove residual oligomers and residual salts by washing with an organic solvent or by washing with hot water or hot water, and then add the alkali metal salts and alkaline earth metal salts. It is preferable to introduce alkali metals and alkaline earth metals into PPS in the form of alkali metal ions and alkaline earth metal ions such as acetates, hydroxides, and carbonates. It is also preferable to remove excess alkali metal salts and alkaline earth metal salts by washing with hot water or the like. The alkali metal ion concentration when introducing alkali metals and alkaline earth metals is preferably 0.001 mmol or more, and more preferably 0.01 mmol or more, per 1 g of PPS. The temperature is preferably 50°C or higher, more preferably 75°C or higher, and particularly preferably 90°C or higher. There is no particular upper temperature limit, but from the viewpoint of operability, it is usually preferred to be 280°C or lower. The bath ratio (mass of washing solution relative to the mass of dry PPS) is preferably 0.5 or higher, more preferably 3 or higher, and even more preferably 5 or higher.

[0069] In the present invention, (a) in order to further suppress oxidative crosslinking of PPS resin under long-term high-temperature environments exceeding 150°C, and to ensure that the resin composition has excellent heat aging resistance while also having excellent fluidity, it is preferable to remove residual oligomers and residual salts by repeatedly washing with an organic solvent and hot water at about 80°C or the aforementioned hot water washing several times, followed by acid treatment or treatment with an alkali metal salt or alkaline earth metal salt, and in particular, treatment with an alkali metal salt or alkaline earth metal salt is even more preferable.

[0070] In addition, (a) PPS resin can also be used after its molecular weight has been increased by thermal oxidation crosslinking treatment, which involves heating in an oxygen atmosphere or by adding a crosslinking agent such as a peroxide after the polymerization reaction process is complete.

[0071] When dry heat treatment is performed for the purpose of increasing molecular weight by thermal oxidation crosslinking, the temperature is preferably 160 to 260°C, and more preferably in the range of 170 to 250°C. Furthermore, it is desirable that the oxygen concentration be 5% by volume or more, and more preferably 8% by volume or more. There is no particular upper limit to the oxygen concentration, but it is limited to about 50% by volume. The treatment time is preferably 0.5 to 100 hours, more preferably 1 to 50 hours, and even more preferably 2 to 25 hours. The heat treatment apparatus may be a normal hot air dryer, or a rotary type or heating apparatus with stirring blades, but for efficient and more uniform processing, it is more preferable to use a rotary type or heating apparatus with stirring blades.

[0072] Furthermore, dry heat treatment is also possible to suppress thermal oxidation crosslinking and remove volatile components. The temperature is preferably 130 to 250°C, and more preferably in the range of 160 to 250°C. In this case, the oxygen concentration is preferably less than 5% by volume, and more preferably less than 2% by volume. The treatment time is preferably 0.5 to 50 hours, more preferably 1 to 20 hours, and even more preferably 1 to 10 hours. The heat treatment apparatus may be a conventional hot air dryer, or a rotary or agitator-equipped heating apparatus, but for efficient and more uniform processing, it is more preferable to use a rotary or agitator-equipped heating apparatus.

[0073] Generally, PPS resins obtained by reacting a sulfidating agent with a dihalogenated aromatic compound in an organic polar solvent in the presence of an alkali metal hydroxide contain nitrogen. This is because alkali metal alkylaminoalkyl carboxylates, which are produced by the reaction of an organic polar solvent such as NMP with an alkali metal hydroxide, react with the PPS ends as a side reaction during polymerization, forming ends with nitrogen atoms. Therefore, the nitrogen content of the PPS resin can be used as an indicator of the carboxyl group or carboxylate group content. (c) In order to increase the toughness of the PPS resin composition by reaction with a silane coupling agent and suppress cracking at the hinge portion, during fitting, and during fastening when used as a plastic fastener, the nitrogen content of the (a) PPS resin used in the present invention is preferably 300 ppm or more, more preferably 500 ppm or more, and particularly preferably 600 ppm or more. Furthermore, if the nitrogen content of (a) PPS resin is too high, the amount of gas increases, which can lead to a decrease in moldability and a decrease in the heat aging resistance of the PPS resin composition. Therefore, the nitrogen content of (a) PPS resin is preferably 1000 ppm or less, more preferably 900 ppm or less, and particularly preferably 800 ppm or less.

[0074] (2)(b) Silicone elastomer having a cross-linked structure (b) Incorporating a silicone elastomer having a crosslinked structure into the PPS resin composition of the embodiment of the present invention is essential to achieving a polyphenylene sulfide resin composition for plastic fasteners that combines flexibility, fluidity, and heat aging resistance under long-term high-temperature environments, and furthermore, allows for easy fastening when used as a plastic fastener, and suppresses cracking at the hinge portion, during fitting, and during fastening.

[0075] The (b) crosslinked silicone elastomer has a main chain structure of organopolysiloxane and a molecular structure in which the intermolecules of the organopolysiloxane are linked by crosslinking. Therefore, it is infusible at the processing temperature of PPS. The degree of polymerization of the crosslinked silicone elastomer is preferably 100 or higher, and the weight-average molecular weight is preferably 10,000 or higher. Note that silicone oil and uncrosslinked silicone gum do not have a crosslinked structure and are therefore not included in the (b) crosslinked silicone elastomer.

[0076] Methods for introducing crosslinked structures include peroxide crosslinking, condensation reaction crosslinking, addition reaction crosslinking, and ultraviolet crosslinking. Peroxide crosslinking involves using organic peroxides such as alkyl peroxides or acyl peroxides to react with alkyl or vinyl groups of a silicone polymer to form crosslinks. Condensation reaction crosslinking involves a condensation reaction between the silanol groups of the silicone polymer and a crosslinking agent, with typical crosslinking agents being de-alcohol type, de-acetic acid type, de-oxime type, de-amide type, de-hydroxylamine type, and de-acetone type. Furthermore, it is preferable to use tin compounds, titanium compounds, metal fatty acids, or amino group-containing compounds as catalysts to promote the reaction. Addition reaction crosslinking involves a hydrosilylation reaction between multiple bonds such as vinyl groups of a silicone elastomer and Si-H groups. In this case, it is preferable to use transition metal compounds, particularly platinum compounds, as catalysts.

[0077] (b) Silicone elastomers having a crosslinked structure may also be in a form having copolymer components in part of their molecular structure. Specifically, this includes copolymers of organopolysiloxane components with one or more copolymer components selected from polyolefins (polyethylene, polypropylene, polybutylene, etc.), polycarbonates, polyamides, polybutylene terephthalate, polyester elastomers, polystyrene, polyetherimide, polyketones, liquid crystal polymers, polyetherketones, polyetheretherketones, polyacrylates (polymethyl methacrylate, etc.). In order to impart flexibility to the resin composition without impairing fluidity and to improve the heat aging resistance of the resin composition, it is preferable that the constituent units derived from organopolysiloxanes account for 90% by mass or more of the (b) crosslinked structure silicone elastomer.

[0078] While composites containing organopolysiloxane as a constituent unit can also be made from core-shell rubber (silicone-acrylic core-shell rubber) in which silicone elastomer particles are covered with an acrylic component, or from composite powders in which silicone elastomers are covered with silicone resin, it is preferable that the constituent units derived from organopolysiloxane account for 90% by mass or more from the viewpoint of improving the flexibility and heat aging resistance of the resin composition.

[0079] (b) The crosslinked silicone elastomer preferably has one or more hydrocarbon groups in its structure selected from C1-C8 alkyl groups (methyl group, ethyl group, propyl group, butyl group, 2-ethylbutyl group, octyl group, etc.), C3-C8 cycloalkyl groups (cyclohexyl group, cyclopentyl group, etc.), C2-C8 alkenyl groups (vinyl group, propenyl group, butenyl group, heptenyl group, hexenyl group, allyl group, etc.), and aryl groups (phenyl group, tolyl group, xylyl group, naphthyl group, diphenyl group, etc.), and among these, it is preferable to have a methyl group, a phenyl group, or a vinyl group.

[0080] Furthermore, the organopolysiloxane structure may also contain one or more functional groups selected from the following: alkoxy groups having 1 to 8 carbon atoms (methoxy, ethoxy, propoxy, butoxy, etc.), amino groups, epoxy groups, isocyanate groups, carbinol groups, methacrylic groups, ether groups, mercapto groups, carboxyl groups, phenol groups, silanol groups, acrylic groups, carboxylic acid anhydride groups, polyether groups, aralkyl groups, fluoroalkyl groups, long-chain alkyl groups, higher fatty acid ester groups, higher fatty acid amide groups, etc., at the molecular chain ends or side chains. In order to increase toughness without impairing the fluidity of the resin composition, (a) it is preferable not to include functional groups that react with the PPS resin ends, such as amino groups, epoxy groups, and isocyanate groups.

[0081] (b) The shape of the crosslinked silicone elastomer is not limited, but examples include pellets, bulk, powder, powder aggregates, and flakes. From the viewpoint of handling, processability, and dispersibility, pellets, powder, powder aggregates, and flakes are preferred.

[0082] When the shape of the cross-linked silicone elastomer is fine particles, the average primary particle diameter (number mean primary particle diameter) is preferably 1 μm or more, more preferably 2 μm or more, even more preferably 2.5 μm or more, and particularly preferably 3 μm or more. In order for the resin composition to satisfy the fluidity required for plastic fastener applications, as described later, the melt viscosity is preferably 300 Pa·s or less, but the lower the melt viscosity, the lower the shear when melt-mixing in an extruder or the like. When the average primary particle diameter of the cross-linked silicone elastomer is 1 μm or more, aggregation of particles is less likely to occur, and even when the melt viscosity of the resin composition is low and the shear during melt-mixing is low, it can be easily finely dispersed, thus improving the toughness of the resin composition and suppressing cracking at the hinge portion, fitting, and fastening when used as a plastic fastener. The upper limit of the average primary particle diameter of a cross-linked silicone elastomer is preferably 20 μm or less, more preferably 15 μm or less, even more preferably 10 μm or less, and particularly preferably 5 μm or less, from the viewpoint of preventing crack initiation and deterioration of mechanical properties. (b) The average primary particle diameter of a cross-linked silicone elastomer can be calculated by randomly identifying the diameters of 10 or more particles from a scanning electron microscope image and calculating their arithmetic mean. In the above image, if the particle is not perfectly circular, i.e., elliptical, the maximum diameter of the particle is taken as the particle diameter. Typical methods for obtaining a fine-particle cross-linked silicone elastomer include dissolving it in a soluble solvent and then precipitating it, forming an emulsion using an emulsifier and then recovering it, and mechanically crushing and micronizing a pellet or bulk cross-linked silicone elastomer.

[0083] The amount of (b) cross-linked silicone elastomer used in the present invention is preferably 1 part by mass or more, more preferably 3 parts by mass or more, even more preferably 5 parts by mass or more, and particularly preferably 10 parts by mass or more, per 100 parts by mass of (a) PPS resin. When the amount of cross-linked silicone elastomer is 1 part by mass or more per 100 parts by mass of (a) PPS resin, the flexibility, toughness, and heat aging resistance of the resin composition are improved, fixing work when used as a plastic fastener becomes easier, and cracking at the hinge portion, during fitting, and during fastening can be suppressed. Furthermore, the amount of (b) cross-linked silicone elastomer is preferably 100 parts by mass or less, more preferably 70 parts by mass or less, even more preferably 50 parts by mass or less, particularly preferably 40 parts by mass or less, and especially preferably 30 parts by mass or less, per 100 parts by mass of (a) PPS resin. If the amount of cross-linked silicone elastomer blended is 100 parts by mass or less per 100 parts by mass of PPS resin (a), the probability of aggregation in the resin composition is reduced, the toughness and heat aging resistance of the desired resin composition can be obtained, and cracking in the hinge portion, fitting, and fastening when used as a plastic fastener can be suppressed.

[0084] Furthermore, it is possible to use silicone elastomers having two or more cross-linked structures in combination.

[0085] (b) The Shore hardness A of the cross-linked silicone elastomer is preferably 60 HS or less, more preferably 50 HS or less, and even more preferably 45 HS or less. By setting the Shore hardness A of the cross-linked silicone elastomer to 60 HS or less, the flexibility, toughness, and heat aging resistance of the resin composition can be effectively improved with a small amount of compounding, and cracking can be suppressed in the hinge portion, during mating, and during fastening when used as a plastic fastener. On the other hand, there is no particular lower limit, but a significantly low Shore hardness means that it is equivalent to silicone oil and will show bleed-out when used at high temperatures for a long period of time, so it is substantially preferable to have a Shore hardness of 10 HS or more.

[0086] (3)(c) Silane coupling agent Incorporating (c) a silane coupling agent into the PPS resin composition of the embodiment of the present invention is essential to achieving a polyphenylene sulfide resin composition for plastic fasteners that enhances the toughness and heat aging resistance of the resin composition and suppresses cracking at the hinge portion, during mating, and during fastening when used as a plastic fastener. In plastic fastener applications, due to their shape, there are areas where stress tends to concentrate during actual use, and cracking may occur starting from the area with the lowest toughness in the resin composition. In other words, it is presumed that incorporating a specific amount of (c) a silane coupling agent that can react with (a) the PPS resin into the PPS resin composition of the present invention to enhance the toughness of the PPS resin composition is important for suppressing cracking at the hinge portion, during mating, and during fastening of plastic fasteners.

[0087] The amount of (c) silane coupling agent used in the present invention must be 0.2 parts by mass or more and 1.9 parts by mass or less per 100 parts by mass of (a) PPS resin. If the amount of (c) silane coupling agent is less than 0.2 parts by mass, the toughness of the resin composition will be insufficient, causing cracks in the hinge portion, during fitting and fastening when used as a plastic fastener, and also resulting in insufficient heat aging resistance, therefore 0.2 parts by mass or more is essential. If the amount of (c) silane coupling agent exceeds 1.9 parts by mass, voids and surface peeling will occur in the molded product obtained from the resin composition, causing cracks in the hinge portion, during fitting and fastening when used as a plastic fastener, and also resulting in reduced heat aging resistance, therefore 1.9 parts by mass or less is essential.

[0088] Specific examples of silane coupling agents include those having at least one functional group selected from isocyanate groups, epoxy groups, amino groups, hydroxyl groups, mercapto groups, ureido groups, and alkoxy groups. Specific examples include 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropylmethyldiethoxysilane, N-phenylaminomethyltrimethoxysilane, N-phenylaminopropyl Examples of preferred silane coupling agents include dimethoxymethyl-3-piperazinopropylsilane, 3-piperazinopropyltrimethoxysilane, 3-isocyanatopropyltrimethoxysilane, 3-isocyanatopropyltriethoxysilane, 3-isocyanatopropylmethyldimethoxysilane, 3-isocyanatopropylmethyldiethoxysilane, 3-isocyanatopropylethyldimethoxysilane, 3-hydroxypropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptomethyldimethoxysilane, and γ-ureidopropyltrimethoxysilane. These silane coupling agents can be used individually or as a mixture of two or more.

[0089] As described above, the (a) PPS resin of the present invention preferably has a nitrogen content of 300 ppm or more, which serves as an indicator of the carboxyl group or carboxylate group content at the ends of the (a) PPS resin. In the present invention, among the silane coupling agents described above, those having one or more isocyanate groups or epoxy groups are preferred because they have appropriate reactivity with the (a) PPS resin, resulting in a good balance of toughness and fluidity of the resin composition, and excellent heat aging resistance of the resin composition due to excellent chemical bond stability. 3-Isocyanatopropyltriethoxysilane and 2-(3,4-Epoxycyclohexyl)ethyltrimethoxysilane are particularly preferred. Furthermore, the bonds formed by the reaction between the (a) PPS resin and the (c) silane coupling agent are preferably amide bonds and ester bonds because they have excellent chemical bond stability.

[0090] (4)(d) Other additives The PPS resin composition of the embodiment of the present invention may contain (a) a PPS resin and (b) a silicone elastomer having a crosslinked structure, to the extent that the effects of the present invention are not impaired. Specific examples include, but are not limited to, olefin elastomers, polyamides, polybutylene terephthalate, polyethylene terephthalate, polyetherimide, poly(etherimide-siloxane) copolymers, polyketones, liquid crystal polymers, polyetherketones, polyetheretherketones, fluororesins (polytetrafluoroethylene (PTFE), ethylene-tetrafluoroethylene copolymer (ETFE), tetrafluoroethylene-perfluoro(alkyl vinyl ether) copolymer (PFA), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), ethylene-tetrafluoroethylene-hexafluoropropylene copolymer, polyvinylidene fluoride (PVDF), and polychlorotrifluoroethylene (PCTFE). The amount of such resin added is preferably less than 10 parts by mass, less than 5 parts by mass, and more preferably less than 3 parts by mass per 100 parts by mass of PPS resin. The lower limit is preferably 0 parts by mass, i.e., no resin is included.

[0091] The PPS resin composition of the embodiment of the present invention may be modified by adding the following compounds: plasticizers such as polyalkylene oxide oligomer compounds, thioether compounds, ester compounds, and organophosphorus compounds; nucleating agents such as organophosphorus compounds and polyether ether ketones; metal soaps such as montanic acid waxes, lithium stearate, and aluminum stearate; release agents such as ethylenediamine-stearic acid-sebacic acid polycondensate; and common additives such as water, lubricants, UV inhibitors, color inhibitors, colorants, foaming agents, phosphorus-based flame retardants, halogen-based flame retardants, and inorganic flame retardants. Adding any of the above compounds in amounts exceeding 10 parts by mass per 100 parts by mass of (a) PPS resin is undesirable because it impairs the inherent properties of the PPS resin composition of the present invention and reduces toughness and heat aging resistance. Addition of 5 parts by mass or less, 1 part by mass or less, and more preferably 0.3 parts by mass or less is preferable.

[0092] Furthermore, in the present invention, epoxy resin can be added to enhance the toughness of the PPS resin composition. Specific examples of epoxy resins include bisphenol A type epoxy resin, bisphenol F type epoxy resin, brominated epoxy resin, special skeleton bifunctional epoxy resins having a biphenyl skeleton or naphthalene skeleton, glycidyl ether type epoxy resins such as cresol novolac type, trisphenolmethane type, and dicyclopentadiene type polyfunctional epoxy resins, glycidylamine type epoxy resins such as aromatic amine type and aminophenol type, and glycidyl ester type epoxy resins such as hydrophthalic acid type and dimer acid type. The amount of epoxy resin added is preferably 0.1 to 5 parts by mass, and particularly preferably 0.2 to 3 parts by mass, per 100 parts by mass of PPS resin.

[0093] The PPS resin composition of the embodiment of the present invention may also be used with inorganic fillers, although these are not essential components, as long as they do not impair the effects of the present invention. Specific examples of such inorganic fillers include fibrous fillers such as glass fibers, carbon fibers, carbon nanotubes, carbon nanohorns, potassium titanate whiskers, zinc oxide whiskers, calcium carbonate whiskers, wollastonite whiskers, aluminum borate whiskers, aramid fibers, alumina fibers, silicon carbide fibers, ceramic fibers, asbestos fibers, gypsum fibers, and metal fibers, or fullerenes, talc, wollastonite, zeolite, sericite, mica, kaolin, clay, pyrophyllite, bentonite, asbestos, and alumina silica. Non-fibrous fillers such as silicates like cate, metal compounds such as silicon oxide, magnesium oxide, alumina, zirconium oxide, titanium oxide, and iron oxide, carbonates such as calcium carbonate, magnesium carbonate, and dolomite, sulfates such as calcium sulfate and barium sulfate, glass beads, glass flakes, glass powder, ceramic beads, boron nitride, silicon carbide, carbon black, and graphite can be used, with glass fibers, calcium carbonate, and carbon black being particularly preferred, and calcium carbonate and carbon black being especially preferred in terms of their anticorrosion and lubricating effects. These inorganic fillers may also be hollow, and it is possible to use two or more types in combination. Furthermore, these inorganic fillers may be pre-treated with coupling agents such as isocyanate compounds, organosilane compounds (silane coupling agents), organotitanate compounds, organoborane compounds, and epoxy compounds before use.

[0094] The amount of such inorganic filler added is selected to suppress cracking at the hinge portion, during fitting, and during fastening when the resin composition is used as a plastic fastener. (a) Per 100 parts by mass of PPS resin, the range is selected to be less than 10 parts by mass, preferably less than 5 parts by mass, more preferably less than 3 parts by mass, and even more preferably 1 part by mass or less. There is no particular lower limit, but 0.0001 parts by mass or more is preferred.

[0095] (5) PPS resin composition The PPS resin composition of the present invention preferably has a flexural modulus of 3.0 GPa or less in a bending test in accordance with ISO 178 (2010) of a test piece obtained by injection molding the resin composition. A flexural modulus of 3.0 GPa or less means excellent flexibility, which is desirable because it facilitates fastening when used as a plastic fastener and suppresses cracking at the hinge portion, fitting, and during fastening. Furthermore, a flexural modulus of 2.6 GPa or less is preferable, 2.4 GPa or less is more preferable, and 2.2 GPa or less is particularly preferable. The lower limit of the flexural modulus is not particularly limited, but from the viewpoint of practically maintaining the shape as a plastic fastener, 0.1 GPa or more is preferably exemplified, and 0.5 GPa or more is more preferably exemplified. The method for obtaining a PPS resin composition having such properties is not particularly limited, but one example is to use (a) 100 parts by mass of PPS resin and (b) 5 parts by mass or more and 100 parts by mass or less of a silicone elastomer having a crosslinked structure.

[0096] Since plastic fasteners generally have thin walls and long lengths, the PPS resin composition of the present invention preferably exhibits excellent fluidity during melting from the viewpoint of moldability. Furthermore, in plastic fastener applications, excellent fluidity of the resin composition is also preferable from the viewpoint of increasing productivity by allowing for multiple pieces to be molded per molding cycle. Fluidity can be indicated by melt viscosity, and the melt viscosity of the PPS resin composition in the present invention is measured using a capillograph at 300°C and under the conditions of orifice length L (mm) / orifice diameter D (mm) = 10, with the value at a shear rate of 1216 / s being adopted. The melt viscosity is preferably 300 Pa·s or less, more preferably 250 Pa·s or less, and particularly preferably 220 Pa·s or less. As a lower limit, the melt viscosity of the PPS resin composition in the present invention can preferably be exemplified as 150 Pa·s or more. When the melt viscosity is 150 Pa·s or more, the toughness of the resin composition is excellent, which tends to suppress cracking at the hinge portion, during fitting, and during fastening when used as a plastic fastener. The method for obtaining a PPS resin composition having such properties is not particularly limited, but examples include (a) selecting a PPS resin with a weight-average molecular weight in the range of 45,000 to 75,000, (a) blending (c) a silane coupling agent in an amount of 0.2 parts by mass to 1.9 parts by mass per 100 parts by mass of PPS resin, and (b) adding 1 part by mass to 40 parts by mass of a silicone elastomer having a cross-linked structure.

[0097] Furthermore, the PPS resin composition of the present invention achieves both excellent flexibility and fluidity by employing (b) a cross-linked silicone elastomer as a flexible component. Conventional methods of blending thermoplastic amorphous resins such as polyetherimide with PPS resin result in excellent toughness and heat aging resistance of the PPS resin composition, but the effect of modifying flexibility is insufficient. On the other hand, there is a problem that fluidity is impaired when a large amount of the aforementioned resin is blended in order to increase flexibility. A preferred embodiment of the PPS resin composition of the present invention is that, in a bending test in accordance with ISO 178 (2010), the bending modulus of elasticity of the test piece obtained by injection molding the resin composition is 3.0 GPa or less, and the melt viscosity of the resin composition at a shear rate of 1216 / s, measured using a capillograph at 300°C and under the conditions of orifice length L (mm) / orifice diameter D (mm) = 10, is 300 Pa·s or less.

[0098] Furthermore, the PPS resin composition of the present invention must have a cohesion level of 10 or less, obtained by dividing the number-average dispersion particle diameter of the silicone elastomer having a cross-linked structure in the resin composition by its average primary particle diameter. A cohesion level exceeding 10 means that the dispersion of the silicone elastomer having a cross-linked structure in the PPS resin composition is insufficient, making it difficult for the toughness and flexibility of the PPS resin composition to be expressed, and making it difficult to suppress cracking at the hinge portion, during fitting, and during fastening when used as a plastic fastener. In order for the PPS resin composition to express excellent toughness and flexibility, a cohesion level of 8 or less is preferable, more preferably 6 or less, even more preferably 4 or less, and particularly preferably 2 or less. There is no particular lower limit to the cohesion level, but 0.1 or more is preferably exemplified. In order to make the cohesion level 10 or less, for example, it is preferable to melt-mix under conditions that can obtain sufficient mixing force, and from the viewpoint of achieving compatibility with the fluidity of the PPS resin composition required for plastic fasteners, it is preferable to use a silicone elastomer having a cross-linked structure with an average primary particle diameter of 1 μm or more. (b) The number-mean dispersion particle diameter in a resin composition of silicone elastomer having a cross-linked structure is obtained by cutting a thin piece of 0.1 μm or less from the center of a molded product made of the PPS resin composition at room temperature in a cross-sectional direction perpendicular to the resin flow direction during molding, and observing it at 1000 to 5000 times magnification using a Hitachi High-Technologies SU8220 field emission scanning electron microscope. For any 10 or more silicone elastomers having a cross-linked structure (b), or their aggregated parts, the maximum and minimum diameters of each are first measured, the average value is taken as the dispersion particle diameter, and then the average value of these is calculated. In the morphology (phase structure) of the PPS resin composition of the present invention, if silicone elastomers having a cross-linked structure (b) exist in aggregated form, the aggregated parts are considered as a single dispersed phase.

[0099] The PPS resin composition of the present invention preferably has a tensile strength retention rate of 90% or more, calculated using the following formula (A) when measured under the conditions of an ASTM No. 4 dumbbell obtained by injection molding of the PPS resin composition, with a tensile speed of 10 mm / min, a grip distance of 64 mm, and an ambient temperature of 23°C.

[0100] (Tensile strength after heat treatment at 185°C for 1000 hours in air) / (Tensile strength before heat treatment) × 100 ... Formula (A)

[0101] The tensile strength retention rate of the PPS resin composition is preferably 100% or more, more preferably 105% or more, and particularly preferably 110% or more. This means that the PPS resin composition has excellent heat aging resistance under long-term high-temperature environments. The method for obtaining such a PPS resin composition is not particularly limited, but one method is to (a) blend a PPS resin with (b) a silicone elastomer having a crosslinked structure. Furthermore, as will be described later, using an amorphous film obtained by hot pressing the PPS resin composition, the absorption spectrum obtained by infrared spectroscopy (hereinafter sometimes abbreviated as FT-IR) shows 2850, 2920 cm⁻¹ -1 It can also be exemplified that the peak area originating from a methylene group with a peak top nearby is 3 or less.

[0102] Furthermore, the tensile strength (tensile strength before heat treatment) of an ASTM No. 4 dumbbell obtained by injection molding of the PPS resin composition of the present invention, measured without heat treatment, is preferably 30 MPa or higher, more preferably 40 MPa or higher, and particularly preferably 50 MPa or higher, from the viewpoint of obtaining excellent mechanical properties and high loop strength when used as a plastic fastener. The method for obtaining such a PPS resin composition is not particularly limited, but examples include (a) setting the weight-average molecular weight of the PPS resin to 45,000 or higher, (a) blending the PPS resin with (b) 1 part by mass or more and 100 parts by mass or less of a silicone elastomer having a cross-linked structure, and (c) blending with 0.2 parts by mass or more and 1.9 parts by mass or less of a silane coupling agent.

[0103] The PPS resin composition of the present invention, when an amorphous film obtained by hot pressing the resin composition is used, shows absorption spectra of 2850 and 2920 cm⁻¹ in infrared spectroscopy (transmission method). -1It is preferable that the peak area derived from methylene groups having a peak top nearby is 3 or less. This means that there are few components in the PPS resin composition that are prone to decomposition under long-term high-temperature conditions. This suppresses the degradation of oxidative crosslinking and other components of the PPS resin, and the PPS resin composition can exhibit excellent heat aging resistance even at ambient temperatures exceeding 165°C. The peak area derived from methylene groups is preferably 2 or less, more preferably 1.5 or less, and particularly preferably 1 or less. The lower limit is not particularly limited, but 0.01 or more is a preferred example. There is no particular limit to the method for obtaining a PPS resin composition having such properties, but one example is to (a) use 3 parts by mass or less, preferably 2 parts by mass or less, more preferably 1.5 parts by mass or less, and particularly preferably 1 part by mass or less, of a compound having a methylene group, such as an olefin-based elastomer, per 100 parts by mass of PPS resin. The specific measurement method can be the one described in the examples.

[0104] The PPS resin composition of the present invention preferably has a tensile elongation at break of 5% or more, measured using an ASTM No. 4 dumbbell obtained by injection molding the resin composition, under the conditions of a tensile speed of 10 mm / min, a gripping distance of 64 mm, and an ambient temperature of 23°C. A tensile elongation at break of 5% or more indicates excellent toughness of the resin composition, which tends to suppress cracking at the hinge portion, during fitting, and during fastening when used as a plastic fastener. A tensile elongation at break of 10% or more is more preferable, 12% or more is even more preferable, 15% is particularly preferable, and 20% or more is especially preferable. The method for obtaining such a PPS resin composition is not particularly limited, but examples include (a) setting the weight-average molecular weight of the PPS resin to 45,000 or more, (a) blending (b) a silicone elastomer having a cross-linked structure in an amount of 1 to 100 parts by mass with respect to the PPS resin, and (c) blending 0.2 to 1.9 parts by mass of a silane coupling agent.

[0105] (6) Method for producing PPS resin composition Methods for producing the PPS resin composition according to embodiments of the present invention include production in a molten state and production in a solution state, but from the viewpoint of simplicity, production in a molten state is preferably used. For production in a molten state, melt kneading by an extruder or melt kneading by a kneader can be used, but from the viewpoint of productivity, melt kneading by an extruder that can produce continuously is preferably used. For melt kneading by an extruder, at least one extruder such as a single-screw extruder, twin-screw extruder, quadruple-screw extruder, or twin-screw single-screw composite extruder can be used, but from the viewpoint of kneadability, reactivity and productivity improvement, a twin-screw extruder or quadruple-screw extruder can be preferably used, and melt kneading by a twin-screw extruder is the most preferred.

[0106] A more specific method for melt-kneading is, although not necessarily limited to this, preferably using a twin-screw extruder with an L / D (L: screw length, D: screw diameter) of 10 or more, preferably 20 or more, and having two or more kneading sections. There is no particular upper limit to the L / D, but 60 or less is preferable from an economic standpoint. Similarly, there is no particular upper limit to the number of kneading sections, but 10 or less is preferable from a productivity standpoint. The ratio of the kneading section to the total screw length is preferably 5% or more, more preferably 10% or more, and even more preferably 15% or more, from the viewpoint of the dispersibility of additives in the PPS resin. On the other hand, the upper limit of the ratio of the kneading section to the total screw length is preferably 40% or less from the viewpoint of preventing resin degradation due to excessive shear heat generation during kneading.

[0107] Regarding the screw rotation speed, a mixing method using conditions of 200 to 1000 revolutions / min, preferably 300 to 1000 revolutions / min, and more preferably 350 to 800 revolutions / min is preferred. When the screw rotation speed is 200 revolutions / min or higher, the mixing force is sufficient, so (b) aggregation of the cross-linked silicone elastomer and other additives is suppressed, leading to the development of the desired toughness. When the screw rotation speed exceeds 1000 revolutions / min, excessive shear heat during mixing causes deterioration of the resin and additives, which is undesirable because it leads to a decrease in toughness, a decrease in mold fouling, and the generation of burrs due to a decrease in melt viscosity.

[0108] The preferred cylinder temperature range (°C) is specifically 280 to 400°C, more preferably 280 to 360°C, and even more preferably 280 to 330°C.

[0109] There are no particular restrictions on the mixing order of the raw materials during melt-kneading, but any method may be used, such as a method in which all raw materials are combined and then melt-kneaded using the method described above, a method in which some raw materials are combined and then melt-kneaded using the method described above, and then combined with the remaining raw materials and melt-kneaded again, or a method in which some raw materials are combined and then the remaining raw materials are mixed using a side feeder while melt-kneading is performed with a twin-screw extruder.

[0110] (7) Plastic fasteners The plastic fasteners formed by molding the PPS resin composition of the present invention refer to fasteners that use resin as the material for their elements. Specifically, plastic fasteners include, for example, cable ties, clips, clamps, point fasteners such as buttons and rivets, line fasteners such as zippers, and hook-and-loop fasteners.

[0111] The plastic fasteners formed by molding the PPS resin composition of the present invention possess excellent chemical resistance and flame retardancy inherent to PPS resin, as well as superior heat aging resistance. Therefore, they can be used as plastic fasteners for bundling wiring cables, cords, tubes, and hoses, particularly in environments where they come into contact with chemicals or in long-term high-temperature environments. Furthermore, because the resin composition of the present invention combines excellent toughness, flexibility, and fluidity, the plastic fasteners formed by molding the PPS resin composition of the present invention can be applied to plastic fasteners that require fluidity in thinner-walled or longer shapes, as well as to plastic fasteners with shapes where stress tends to concentrate at specific points during fitting or fastening, or shapes with hinge portions. They are particularly suitable as fastening bands, cable ties, clips, and clamps having these shapes. As for the specific shapes of the applicable plastic fasteners, the thickness of the thinnest-walled part is preferably 2 mm or less, more preferably 1.5 mm or less, even more preferably 1.2 mm or less, and particularly preferably 1 mm or less. [Examples]

[0112] The present invention will be described in more detail below with reference to examples, but the present invention is not limited thereto.

[0113] In the examples and comparative examples, the following were used as (a) PPS resin, (b) silicone elastomer having a crosslinked structure, (c) silane coupling agent, and (d) other additives.

[0114] [(a)PPS resin] a-1: PPS resin, weight average molecular weight: 56000, nitrogen content: 620ppm, Tmc: 180℃ a-2: PPS resin, weight average molecular weight: 73000, nitrogen content: 680ppm, Tmc: 230℃ a-3: PPS resin, weight average molecular weight: 58000, nitrogen content: 630ppm, Tmc: 190℃ a-4: PPS resin, weight average molecular weight: 54000, nitrogen content: 760ppm, Tmc: 219℃

[0115] [(b) Silicone elastomer having a cross-linked structure] b-1: Cross-linked silicone elastomer (Dowsil "EP-5500" manufactured by Dow-Toray), average primary particle size: 3 μm, constituent units derived from organopolysiloxane: 90% by mass or more, Shore hardness A: 30HS b-2: Cross-linked silicone elastomer (Dowsil "EP-2601" manufactured by Dow-Toray), average primary particle size: 2 μm, constituent units derived from organopolysiloxane: 90% by mass or more, Shore hardness A: 50HS b-3: Cross-linked silicone elastomer (Shin-Etsu Chemical Co., Ltd. "KMP-597"), average primary particle size: 5 μm, constituent units derived from organopolysiloxane: 90% by mass or more, Shore hardness A: 30HS b-4: Cross-linked silicone elastomer (Kaneka Corporation "MR-01", silicone-acrylic core-shell rubber), average primary particle size: 0.13 μm, constituent units derived from organopolysiloxane: 70% by mass or more, Shore hardness A: 30HS

[0116] [(c) Silane coupling agent] c-1:3-Isocyanate-propyltriethoxysilane (Shin-Etsu Silicone Co., Ltd. "KBE9007N") c-2: 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane (Shin-Etsu Silicone Co., Ltd. "KBM303") c-3:3-mercaptopropyltrimethoxysilane (Shin-Etsu Silicone Co., Ltd. "KBM803") [(d) Other additives] d-1: Poly(etherimidosiloxane) copolymer (SABIC's "SILTEM" (registered trademark) 1500), constituent units derived from organopolysiloxane: 30% by mass d-2: Ethylene-glycidyl methacrylate copolymer ("BF-7M" (registered trademark) manufactured by Sumitomo Chemical Co., Ltd.) d-3: Sodium phosphinate monohydrate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) d-4: Polydimethylsiloxane (Dowsil "SH-200 Fluid 60,000cst" manufactured by Dow Toray)

[0117] In the following examples, the material properties were evaluated by the following method.

[0118] [GPC measurement] The number-average molecular weight (Mn) and weight-average molecular weight (Mw) of PPS resin were measured using gel permeation chromatography (GPC) manufactured by Senshu Scientific Co., Ltd. under the conditions described below, and calculated in polystyrene equivalents.

[0119] Device: Senshu Science SSC-7110 Column name: “Shodex” (registered trademark) UT806M x 2 Eluent: 1-Chloronaphthalene Detector: Differential refractive index detector Column temperature: 210℃ Pre-temperature bath temperature: 250℃ Pump constant temperature bath temperature: 50℃ Detector temperature: 210℃ Flow rate: 1.0mL / min Sample injection volume: 300 μL

[0120] [Nitrogen content] The sample was thermally decomposed and oxidized at a final temperature of 900°C using a horizontal reactor, and the nitrogen content in the polymer was measured by subjecting the generated nitric oxide to a Nitto Seiko Analytech ND-100 nitrogen detector.

[0121] [DSC measurement] (a) Using PPS resin, measurements were taken under nitrogen atmosphere using a differential scanning calorimeter (DSC, Q200; TA Instruments Corporation) under the following conditions: The temperature was increased from 50°C to 340°C at a rate of 20°C / min. Then, it was held at 340°C for 1 minute and cooled down to 100°C at a rate of 20°C / min. The cooling crystallization peak temperature (Tmc) was obtained from the value of the cooling crystallization peak top detected during the cooling process.

[0122] [IR peak area] The pellets of the PPS resin composition were dried at 120 °C for 3 hours using a hot air dryer, and then, by the following method, the peak area derived from the methylene group having a peak top at around 2850 and 2920 cm -1 was calculated in the absorption spectrum obtained by infrared spectroscopic analysis (transmission method).

[0123] Procedure 1) The pellets of the PPS resin composition were pressed at 320 °C for 2 minutes using a press machine, and then quenched by dipping in a water bath to obtain an amorphous film with a thickness of about 50 μm.

[0124] Procedure 2) Using the amorphous film as a sample, Fourier transform infrared spectroscopy (FT-IR) measurement was performed with an IR-810 type infrared spectrophotometer manufactured by JASCO Corporation (resolution: 4 cm -1 , number of integrations: 32 times).

[0125] Procedure 3) In the obtained absorption spectrum (horizontal axis: wave number (cm -1 ), vertical axis: absorbance), a baseline was drawn as a straight line from around 1850 cm -1 to around 1940 cm -1 , and the peak area (A) having a peak top at around 1900 cm -1 was determined.

[0126] Procedure 4) Subsequently, in the same manner as in Procedure 3, a baseline was drawn as a straight line from around 2825 cm -1 to around 2955 cm -1 , and the peak area (B) having a peak top at around 2850 and 2920 cm -1 was determined. When it was difficult to analyze with a single baseline, a baseline was drawn as a straight line for each peak, and the total value of the peak areas was taken as the peak area (B). The both ends of the baseline were appropriately adjusted depending on the presence of adjacent peaks etc.

[0127] Procedure 5) Calculate peak area (B) / peak area (A), and the target 2850, 2920 cm -1The peak area originating from methylene groups with peak tops in the vicinity was calculated. This serves as an indicator of the content ratio of compounds containing methylene groups relative to the PPS resin in the PPS resin composition; a smaller value indicates that there are fewer components that degrade due to oxidative decomposition under long-term high-temperature environments.

[0128] [Bending test] The PPS resin composition pellets of the present invention were dried at 120°C for 3 hours using a hot air dryer. The pellets were then supplied to a Sumitomo Heavy Industries injection molding machine (SE-75DUZ) set to a cylinder temperature of 320°C and a mold temperature of 145°C. Injection molding was performed using a mold of type A1 specimen shape as specified in ISO 20753 (2008), under conditions where the average velocity of the molten resin passing through the cross-sectional area of ​​the central parallel section was 400 ± 50 mm / s, thereby obtaining a test specimen. The central parallel section of this specimen was cut out to obtain a type B2 specimen. This specimen was conditioned for 16 hours at 23°C and 50% relative humidity, and then the flexural modulus was measured according to the ISO 178 (2010) method, with a span of 64 mm and a test speed of 2 mm / min.

[0129] [Tensile test] PPS resin composition pellets were dried in a hot air dryer at 120°C for 3 hours, and then supplied to a Sumitomo Heavy Industries injection molding machine (SE-75DUZ) set to cylinder temperature: 300°C and mold temperature: 150°C to form ASTM No. 4 dumbbells. These molded products were either subjected to no heat treatment, or heat-treated in a hot air oven at 185°C for 1000 hours under atmospheric conditions, followed by 16 hours of conditioning at an ambient temperature of 23°C and a relative humidity of 50%. The conditioned dumbbells were then tested using a Tensilon UTA2.5T tensile testing machine under the conditions of a tensile speed of 10 mm / min, grip distance of 64 mm, gauge length of 50 mm, ambient temperature of 23°C, and relative humidity of 50%. The tensile elongation at break and tensile strength were measured, and the average of five measurements was calculated. The tensile strength retention rate was calculated using the following formula (A). A higher value indicates superior heat aging resistance of the PPS resin composition. Note that "tensile strength before heat treatment" refers to the tensile strength measured using a dumbbell that has been conditioned without heat treatment.

[0130] (Tensile strength after heat treatment at 185°C for 1000 hours in air) / (Tensile strength before heat treatment) × 100 ... Formula (A)

[0131] [Melting viscosity] The PPS resin composition pellets of the present invention were measured using a "Capillograph" (registered trademark) 1B manufactured by Toyo Seiki Co., Ltd., under conditions of 300°C and orifice length L (mm) / orifice diameter D (mm) = 10. The values ​​at a shear rate of 1216 / s were adopted.

[0132] [Bleedout] ASTM No. 4 dumbbells, obtained under the same molding conditions as the tensile test, were conditioned for 16 hours at 23°C and 50% relative humidity. After that, they were placed in a gear oven set to 185°C and treated for 1000 hours. After cooling at room temperature for more than 24 hours, bleed-out was evaluated from the surface condition. Specifically, levels where discoloration different from the base material PPS resin composition was observed on the surface after heat treatment were judged as "bleed-out" and deemed defective, while levels where no discoloration was observed were judged as "bleed-out" and deemed good.

[0133] [Number of cracks and fissures evaluated] ASTM No. 4 dumbbells, obtained under the same molding conditions as the tensile test, were conditioned for 16 hours at 23°C and 50% relative humidity. Afterward, the center of each specimen was manually bent into a loop until the gripping ends of the specimen were in close contact with the same surface. Three specimens were evaluated, and the number of specimens showing cracks or breaks was counted. This test simulates the actual use of plastic fasteners and serves as an indicator of their susceptibility to cracking at the hinge, during mating, and during fastening. A smaller value indicates less cracking, and zero cracked or broken specimens signify that the plastic fastener is superior and practical.

[0134] [Cohesion degree] Using an ASTM No. 4 dumbbell obtained under molding conditions similar to those for the tensile test, thin slices of 0.1 μm or less were cut from the center at room temperature in a cross-sectional direction perpendicular to the resin flow direction during molding. For any 10 or more silicone elastomers having (b) crosslinked structures, or their aggregated parts, observed at 1000 to 5000x magnification using a Hitachi High-Technologies SU8220 field emission scanning electron microscope, the maximum and minimum diameters of each were first measured and their average values ​​were taken as the dispersed particle diameter. Then, the average of these values ​​was calculated to obtain the number-average dispersed particle diameter. If the silicone elastomers having (b) crosslinked structures were aggregated, the aggregated parts were considered as a single dispersed phase. The degree of aggregation was calculated by dividing the obtained number-average dispersed particle diameter by the average primary particle diameter of the silicone elastomers having (b) crosslinked structures.

[0135] [Examples 1-16, Comparative Examples 1-6, 9-12] After dry blending each raw material according to the formulations shown in Tables 1-5, the mixture was melt-kneaded using a TEX30α twin-screw extruder (L / D=45) manufactured by Japan Steel Works Ltd., equipped with a vacuum vent. The kneading section had two sections, with the kneading section accounting for 15% of the total screw length, and the cylinder temperature was 300°C and the rotation speed was 200 rpm. This melt-kneading method was designated as Method A. Subsequently, the mixture was pelletized using a strand cutter, and the pellets, dried at 120°C for 3 hours, were subjected to injection molding. The evaluation results are shown in Tables 1-5.

[0136] [Comparative Examples 7 and 8] Except for having three kneading sections and a kneading section ratio of 45% to the total screw length, melt mixing was performed in the same manner as in the previous section. This melt mixing method was designated as Method B. Subsequently, evaluation was performed in the same manner as in the previous section.

[0137] [Table 1]

[0138] [Table 2]

[0139] [Table 3]

[0140] [Table 4]

[0141] [Table 5]

[0142] The results of the above-mentioned examples and comparative examples will be explained in comparison.

[0143] Examples 1 to 16 show that the PPS resin composition for plastic fasteners of the present invention possesses a combination of fluidity, flexibility, and heat aging resistance, and has the property of not cracking when bent into a loop shape. Fluidity was maintained even when a relatively large amount of silicone elastomer having a cross-linked structure (b) was incorporated, as in Example 4.

[0144] On the other hand, in Comparative Example 1, which did not contain (b) the cross-linked silicone elastomer, the bending modulus was high and the flexibility was poor, resulting in cracks and breaks when bent into a loop. Similarly, in Comparative Examples 2 and 3, when the amount of (c) silane coupling agent was small, cracks and breaks also occurred. In Comparative Example 4, which contained an excessive amount of (c) silane coupling agent, peeling caused by gas occurred on the surface of the molded product, and when bent into a loop, cracks appeared to originate from these peeling points. It is believed that by incorporating an appropriate amount of (c) silane coupling agent into the PPS resin composition, the toughness necessary for practical use as a plastic fastener can be provided.

[0145] In Comparative Examples 5-8, when a thermoplastic resin (poly(etherimido-siloxane) copolymer) was added as an additional additive, flexibility improved slightly compared to Comparative Example 1, but fluidity decreased. Although some improvement in fluidity was observed by using strong mixing conditions in the melt-mixing method, the results were not as good as the PPS resin composition of the present invention in terms of achieving both flexibility and fluidity. The PPS resin composition of the present invention was found to achieve both flexibility and fluidity and is more suitable as a plastic fastener.

[0146] As shown in Table 3, it was found that PPS resin compositions exhibited excellent heat aging resistance when the peak area derived from methylene groups was below a certain level. In Comparative Example 9, where a large amount of ethylene-glycidyl methacrylate copolymer was added as an additional additive, the peak area derived from methylene groups was large, and there were many components that caused degradation due to oxidative decomposition during heat treatment, resulting in poor heat aging resistance.

[0147] As shown in Table 4, (b) when the degree of cohesion of the cross-linked silicone elastomer was 10 or less, it had the property of not cracking when bent into a loop shape.

Claims

1. A polyphenylene sulfide resin composition for plastic fasteners, comprising (a) a polyphenylene sulfide resin, (b) a silicone elastomer having a crosslinked structure, and (c) a silane coupling agent, wherein the amount of (c) the silane coupling agent is 0.2 parts by mass or more and 1.9 parts by mass or less per 100 parts by mass of (a) the polyphenylene sulfide resin, and the degree of aggregation obtained by dividing the number-average dispersion particle diameter of the silicone elastomer having a crosslinked structure in the resin composition by its average primary particle diameter is 10 or less.

2. (b) The polyphenylene sulfide resin composition for plastic fasteners according to claim 1, wherein the average primary particle diameter of the cross-linked silicone elastomer is 1 μm or more.

3. The polyphenylene sulfide resin composition for plastic fasteners according to claim 1, wherein, in a bending test in accordance with ISO 178 (2010), the flexural modulus of a test piece obtained by injection molding the resin composition is 3.0 GPa or less.

4. The polyphenylene sulfide resin composition for plastic fasteners according to claim 1, wherein the melt viscosity at a shear rate of 1216 / s, measured using a capillograph at 300°C and under conditions of orifice length L (mm) / orifice diameter D (mm) = 10, is 300 Pa·s or less.

5. (c) The polyphenylene sulfide resin composition for plastic fasteners according to claim 1, wherein the silane coupling agent has one or more isocyanate groups or epoxy groups.

6. (a) The polyphenylene sulfide resin composition for plastic fasteners according to claim 1, wherein the nitrogen content of the polyphenylene sulfide resin is 300 ppm or more.

7. An amorphous film obtained by hot-pressing a resin composition was used to obtain an absorption spectrum of 2850 and 2920 cm⁻¹ using infrared spectroscopy (transmission method). －１ The polyphenylene sulfide resin composition for plastic fasteners according to claim 1, wherein the peak area derived from a methylene group having a peak top nearby is 3 or less.

8. The polyphenylene sulfide resin composition for plastic fasteners according to claim 1, wherein the tensile strength retention rate, calculated by the following formula (A), is 90% or more when measured using an ASTM No. 4 dumbbell obtained by injection molding the resin composition under conditions of a tensile speed of 10 mm / min, a grip distance of 64 mm, and an ambient temperature of 23°C. (Tensile strength after heat treatment at 185°C for 1000 hours in air) / (Tensile strength before heat treatment) × 100 ... Equation (A)

9. A plastic fastener formed by molding a polyphenylene sulfide resin composition for plastic fasteners according to any one of claims 1 to 8.

10. The plastic fastener according to claim 9, which is selected from cable ties, clips, and clamps.

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