Hollow fiber membrane module and method for manufacturing same

Abstract

The purpose of the present invention is to provide: a hollow fiber membrane module provided with durability such that no leakage occurs when heat sterilization at 125°C or higher using high-temperature hot water is repeatedly performed; and a method for manufacturing the same. A hollow fiber membrane module comprising a cylindrical case, a hollow fiber membrane bundle which is accommodated in the cylindrical case and which has a plurality of hollow fiber membranes, and at least one binding part in which the plurality of hollow fiber membranes are bound using an adhesive, wherein: the adhesive contains a bisphenol-A epoxy resin, an imidazole curing agent, and rubber particles, has a non-imidazole curing agent content of less than 15.0 parts by mass with respect to 100 parts by mass of the bisphenol-A epoxy resin, and has a glass transition temperature of not lower than 125°C but lower than 180°C; and in a cross-section of the adhesive, the rubber particles have a diameter of 10.0 μm or less, the rubber particle ratio is 3.0-25.0%, and the rubber particles have a dispersity of 2.0 or less.

Description

Hollow fiber membrane module and method for manufacturing the same

[0001] This invention relates to a hollow fiber membrane module and a method for manufacturing the same, for use in fields such as water treatment, fermentation industry, pharmaceutical and medical fields, and food industry.

[0002] Hollow fiber membrane modules used in food and pharmaceutical applications can be used in membrane processing systems that handle biologically active filtration stocks by performing sterilization using hot water, sterilization using saturated steam, and chemical washing using acids or alkalis. In recent years, in sterilization processes that remove bacteria from filtration stocks using hollow fiber membrane modules, there has been a demand for hollow fiber membrane modules that can be sterilized with hot water temperatures of 125°C or higher, which have a higher heat load than conventional 125°C steam sterilization or 80-90°C hot water sterilization, when heating and sterilizing bacteria attached to the hollow fiber membrane module.

[0003] Generally, a hollow fiber membrane module consists of a hollow fiber membrane bundle containing approximately several hundred to tens of thousands of hollow fiber membranes bound together at a binding point, housed in a cylindrical case. At least one end of the hollow fiber membrane bundle is bound together and housed in the cylindrical case. Here, the bound hollow fiber membrane has an opening at at least one end, and the hollow portion serves as a flow path for the filtrate or filtrate stock. The binding point serves to bundle the membranes and also to separate the filtrate from the filtrate stock.

[0004] From the viewpoint of heat resistance and chemical resistance, hollow fiber membrane modules in which hollow fiber membrane bundles are fixed with an adhesive resin mainly composed of heat-resistant epoxy resin are preferably used.

[0005] Patent Document 1 discloses a hollow fiber membrane module that can withstand 95°C hot water filtration by using imidazole and polyamine in combination as curing agents for the epoxy resin used in the binding portion.

[0006] Patent Document 2 discloses a hollow fiber membrane module that can withstand 80°C hot water filtration by using polyamine as a curing agent for the epoxy resin used in the binding portion and adding rubber particles.

[0007] JP-A-58-166902 JP-A-08-206466

[0008] However, the hollow fiber membrane module described in Patent Document 1 has a problem in that the epoxy resin is brittle and lacks flexibility, so repeated heat sterilization with hot water at a higher temperature of 125°C causes cracks to spread within the binding area, resulting in leakage. Furthermore, while the hollow fiber membrane module described in Patent Document 2 has increased flexibility of the epoxy resin by adding rubber particles, if heat resistance to 125°C hot water for this application is to be obtained using a polyamine curing agent, it is necessary to select a polyamine curing agent that generates a large amount of heat during epoxy curing, which can damage the hollow fiber membrane.

[0009] Therefore, the present invention aims to provide a hollow fiber membrane module and a method for manufacturing the same that have durability to prevent leakage when repeatedly subjected to heat sterilization with hot water at a high temperature of 125°C or higher.

[0010] To solve the above problems, the present invention includes the following configurations [1] to

[12] . [1] A hollow fiber membrane module comprising a cylindrical case, a hollow fiber membrane bundle having a plurality of hollow fiber membranes housed in the cylindrical case, and at least one binding portion in which the plurality of hollow fiber membranes are bound together with an adhesive, wherein the adhesive contains a bisphenol A type epoxy resin, an imidazole curing agent and rubber particles, the content of the non-imidazole curing agent is less than 15.0 parts by mass per 100 parts by mass of the bisphenol A type epoxy resin, and the glass transition temperature is 125°C or more and less than 180°C, the diameter of the rubber particles in the cross-section of the adhesive is 10.0 μm or less, the rubber particle ratio is 3.0% or more and 25.0% or less, and the dispersion degree of the rubber particles is 2.0 or less. [2] The adhesive has an elastic modulus of less than 3.2 GPa at 23°C and a strain energy release rate G ＩＣ [1] Hollow fiber membrane module, wherein the coefficient of thermal expansion is 100 N / m or more. [3] The adhesive has a linear expansion coefficient of 10.0 × 10 －５A hollow fiber membrane module according to [1] or [2], wherein the temperature is less than / ℃. [4] A hollow fiber membrane module according to any one of [1] to [3], wherein the rubber particles are core-shell rubber particles or epoxy group-containing rubber particles. [5] A hollow fiber membrane module according to any one of [1] to [4], wherein the rubber particles are silicone. [6] A hollow fiber membrane module according to any one of [1] to [5], wherein the non-imidazole curing agent is a polyetheramine curing agent, the content of the polyetheramine curing agent in the adhesive is 1.0 part by mass or more and 7.0 parts by mass or less per 100 parts by mass of the bisphenol A type epoxy resin, and the weight-average molecular weight of the polyetheramine curing agent is 100 or more and 450 or less. [7] A method for manufacturing a hollow fiber membrane module, comprising: (a) a potting step of restraining at least one end face of a plurality of hollow fiber membranes with an adhesive; and (b) a step of curing the adhesive, wherein the adhesive in step (a) comprises a bisphenol A type epoxy resin, an imidazole curing agent, and rubber particles, the content of the non-imidazole curing agent is less than 15.0 parts by mass per 100 parts by mass of the bisphenol A type epoxy resin, the glass transition temperature after step (b) is 125°C or more and less than 180°C, the diameter of the rubber particles in the cross-section of the adhesive is 10.0 μm or less, the rubber particle ratio is 3.0% or more and 25.0% or less, and the dispersion of the rubber particles is 2.0 or less. [8] The adhesive used in step (a) has an elastic modulus of less than 3.2 GPa at 23°C after step (b), and a strain energy release rate G ＩＣ A method for manufacturing a hollow fiber membrane module according to [7], wherein the coefficient of thermal expansion after step (b) is 100 N / m or more. [9] The adhesive used in step (a) has a coefficient of thermal expansion of 10.0 × 10 －５A method for producing a hollow fiber membrane module according to [7] or [8], wherein the temperature is less than / ℃.

[10] A method for producing a hollow fiber membrane module according to any one of [7] to [9], wherein the rubber particles used in step (a) are core-shell rubber particles or epoxy group-containing rubber particles.

[11] A method for producing a hollow fiber membrane module according to any one of [7] to

[10] , wherein the rubber particles used in step (a) are silicone.

[12] A method for producing a hollow fiber membrane module according to any one of [7] to

[11] , wherein the non-imidazole curing agent used in step (a) is a polyetheramine curing agent, the content of the polyetheramine curing agent in the adhesive is 1.0 part by mass or more and 7.0 parts by mass or less per 100 parts by mass of the bisphenol A type epoxy resin, and the weight-average molecular weight of the polyetheramine curing agent is 100 or more and 450 or less.

[0011] According to the present invention, a hollow fiber membrane module is obtained that has durability to prevent leakage even when repeatedly subjected to heat sterilization with hot water at a high temperature of 125°C or higher.

[0012] Figure 1 is a schematic longitudinal cross-sectional view of a cartridge-type hollow fiber membrane module according to this embodiment. Figure 2 is a schematic diagram of a hollow fiber membrane cartridge of the hollow fiber membrane module according to this embodiment. Figure 3 is a flowchart showing an example of a method for manufacturing the hollow fiber membrane module according to this embodiment. Figure 4 is a schematic cross-sectional view illustrating an example of a method for manufacturing the hollow fiber membrane module according to this embodiment.

[0013] The form of a hollow fiber membrane module according to one embodiment of the present invention (hereinafter referred to as "this embodiment") will be described in detail below with reference to the figures. In this specification, "up" and "down" are for convenience based on the state shown in the figures, with the side into which the filtration stock flows being the "down" direction and the side out which the filtrate flows being the "up" direction. The direction from "down" to "up" will be conveniently referred to as the "height direction". Normally, when the hollow fiber membrane module is in use, the up and down direction coincides with the up and down direction in the figures.

[0014] <Hollow Fiber Membrane Module> The hollow fiber membrane module of the present invention comprises a bundle of hollow fiber membranes having a plurality of hollow fiber membranes housed in a cylindrical case, and at least one binding portion in which the plurality of hollow fiber membranes are bound together with an adhesive.

[0015] As an example of a hollow fiber membrane module according to this embodiment, the configuration of the hollow fiber membrane module shown in Figures 1 and 2 will be described below. In Figures 1 and 2, a cartridge-type hollow fiber membrane module in which the hollow fiber membrane cartridge can be attached to and detached from the housing will be described as an example, but the method is also applicable to hollow fiber membrane modules in which the hollow fiber membrane is adhesively fixed to the housing.

[0016] As shown in Figures 1 and 2, the cartridge-type hollow fiber membrane module 100 comprises a cylindrical case 1 and a hollow fiber membrane cartridge 101 housed within the cylindrical case 1. The hollow fiber membrane cartridge 101 has a hollow fiber membrane bundle 2 having a plurality of hollow fiber membranes, and the hollow fiber membranes are bonded together with adhesive at both ends of the hollow fiber membrane bundle 2 by a first binding portion 3 located on the filtrate outlet 9 side of the cylindrical case 1 and a second binding portion 4 located on the filtrate inlet 10 side of the cylindrical case 1.

[0017] The cartridge-type hollow fiber membrane module 100 consists of a hollow cylindrical case 1 and upper caps 7 and lower caps 8 provided at both ends of the cylindrical case 1. The upper caps 7 and lower caps 8 are fixed to the cylindrical case 1 using, for example, gaskets 11 and clamps.

[0018] The cylindrical case 1 has flanges 1A and 1B at its upper and lower ends, extending around its entire circumference. Additionally, a filter liquid outlet 12 is provided on the side of the cylindrical case 1, closer to the filter liquid outlet 9.

[0019] The upper cap 7 has an inner diameter approximately equal to the inner diameter of the cylindrical case 1, and its upper end is tapered to form the filtration liquid outlet 9. A stepped portion 7A is formed around the entire circumference of the lower end of the upper cap 7 to form a groove when connected to the cylindrical case 1. When the cylindrical case 1 and the upper cap 7 are connected, the lower end of the upper cap 7 abuts against the flange portion 1A of the cylindrical case 1 to form a groove (fixing portion), and the flange portion 3A of the first fastening portion 3 and the sealing material 13 are sandwiched in this groove (fixing portion) and fixed in place.

[0020] The lower cap 8 has an inner diameter approximately equal to the inner diameter of the cylindrical case 1, and its lower end is tapered to form the filtration liquid inlet 10.

[0021] A sealing material 14 is placed between the stepped portion 3B of the first binding portion 3 and the cylindrical case 1. The first binding portion 3 is fixed in a liquid-tight and airtight manner by crushing the sealing material 14 in the radial direction (lateral direction in Figure 1) of the hollow fiber membrane module. In this way, the first binding portion 3 is not directly bonded to the cylindrical case 1, but is fixed in a liquid-tight and airtight manner by the sealing material 14.

[0022] <Binding Section> In the hollow fiber membrane module according to this embodiment, the binding section is the part where multiple hollow fiber membranes are bound together with adhesive. The first binding section and the second binding section shown in Figures 1 and 2 are usually formed in a shape close to a cylinder, but they may also be in a shape close to a rectangular parallelepiped or cube. A shape close to a cylinder is preferable because it simplifies the shape of the sealing material used when loading it into a cylindrical case, and allows the use of commercially available sealing materials that are generally available. The binding section formed in a cylindrical shape preferably has an outer diameter of 70 mm or more and less than 250 mm. If the outer diameter of the binding section is 70 mm or more, the membrane area per unit volume of the hollow fiber membrane module can be increased, and the manufacturing cost per unit membrane area can be suppressed.

[0023] The adhesive used for the hollow fiber membrane module according to this embodiment has high heat resistance and suppresses heat generation during curing. Therefore, even if the outer diameter of the binding portion is large, such as 70 mm or more, excessive temperature rise does not occur during curing. Furthermore, if the outer diameter of the binding portion is less than 250 mm, the mass of the hollow fiber membrane module itself does not become too heavy, which can suppress the load on the connected piping and other components.

[0024] Furthermore, considering the ease of manufacturing the cartridge-type hollow fiber membrane module 100 and the ease of cleaning the hollow fiber membrane bundle 2 during cleaning of the hollow fiber membrane module, it is preferable that the hollow fiber membrane bundle 2 is housed in a cylindrical case 1 via the first binding portion 3 or the second binding portion 4 at both ends in a loose state. Looseness means that the length of the hollow fiber membrane bundle 2 in that portion is longer than the straight-line distance from the lower end face of the first binding portion 3 to the upper end face of the second binding portion 4.

[0025] The adhesive used in the binding portion of the hollow fiber membrane module of the present invention comprises a bisphenol A type epoxy resin, an imidazole curing agent, and rubber particles, wherein the content of the non-imidazole curing agent is less than 15.0 parts by mass per 100 parts by mass of the bisphenol A type epoxy resin, and the glass transition temperature is 125°C or higher and less than 180°C. In addition, the diameter of the rubber particles in the cross-section of the adhesive is 10.0 μm or less, the rubber particle ratio is 3.0% or higher and 25.0% or lower, and the dispersion degree of the rubber particles is 2.0 or lower.

[0026] By using bisphenol A type epoxy resin as the main component of the adhesive, a bonded section with a high glass transition temperature can be obtained. Furthermore, since bisphenol A type epoxy resin has a low risk of mutagenic substance leaching, unlike adhesives that use polyfunctional epoxy resins as the main component, it can be suitably used in water treatment fields such as sewage reuse, fermentation industries, pharmaceutical and medical fields, and food industries, where the filtered liquid may be taken into the human body.

[0027] The adhesive used in the binding portion of the hollow fiber membrane module of the present invention uses an imidazole curing agent. Examples of imidazole curing agents include 2-methylimidazole and 2-ethyl-4-methylimidazole. When curing epoxy resin to obtain an adhesive with a high glass transition temperature, a large amount of heat is generated during curing. This heat generation is particularly significant when curing several hundred grams or more of epoxy resin. By using an imidazole curing agent as the main curing agent, the polymerization of the epoxy resin occurs sequentially, which allows for control of the heat generation behavior during curing and reduces the maximum temperature during curing.

[0028] The amount of imidazole curing agent is preferably 0.5 parts by mass to 7.0 parts by mass, and more preferably 1.5 parts by mass to 4.0 parts by mass, when the main component, bisphenol A type epoxy resin, is 100 parts by mass. If the amount of imidazole curing agent is 0.5 parts by mass or more, the curing reaction of the epoxy resin will proceed, and if it is 1.5 parts by mass or more, the curing time can be shortened. Furthermore, if the amount of imidazole curing agent is 7.0 parts by mass or less, the elution of remaining unreacted imidazole curing agent can be prevented, and if it is 4.0 parts by mass or less, the curing exothermic temperature can be easily adjusted by temperature control.

[0029] The content of the non-imidazole curing agent in the adhesive at the binding portion of the hollow fiber membrane module of the present invention is less than 15.0 parts by mass per 100 parts by mass of bisphenol A type epoxy resin. If the adhesive contains 15.0 parts by mass or more of the non-imidazole curing agent, the imidazole curing agent functions as an accelerator to promote polymerization between the non-imidazole curing agent, such as polyamines or acid anhydrides, and the epoxy resin, resulting in a significantly increased heat generation during curing. By keeping the content of the non-imidazole curing agent in the adhesive to less than 15 parts by mass per 100 parts by mass of bisphenol A type epoxy resin, the heat generation during curing can be suppressed, and the properties of the resulting adhesive exhibit characteristics due to the curing component of the imidazole curing agent. From the above viewpoint, the content of the non-imidazole curing agent is preferably 12.0 parts by mass or less, and more preferably 10.0 parts by mass or less, per 100 parts by mass of bisphenol A type epoxy resin.

[0030] The ratio of non-imidazole curing agent to bisphenol A epoxy resin in an adhesive can be measured, for example, by GC / MS analysis. Specifically, a cross-section of the adhesive is taken from the surface of the binding portion of the hollow fiber membrane module and from the inside of the binding portion at least 1 mm inward from the hollow fiber membrane surface. The adhesive is then thermally desorbed and thermally decomposed using a pyrolysis apparatus, and the resulting gas is introduced into a GC / MS to obtain spectral data. The non-imidazole curing agent is identified from the spectral data, and the ratio of the non-imidazole curing agent to the bisphenol A epoxy resin can be calculated from the peak intensity derived from the identified non-imidazole curing agent and the peak intensity derived from the bisphenol A epoxy resin.

[0031] The glass transition temperature of the adhesive in the hollow fiber membrane module of the present invention is 125°C or higher and less than 180°C. The glass transition temperature is the transition midpoint temperature of the reversible heat flow curve measured using temperature-modulated differential scanning calorimetry. A glass transition temperature of 125°C or higher allows for use under high-temperature conditions such as filtration of high-temperature liquids, hot water sterilization, and steam sterilization. Furthermore, a glass transition temperature of less than 180°C allows for the curing and molding of large volumes of adhesive without deterioration of the hollow fiber membrane due to the heat generated during the curing of the epoxy resin. A glass transition temperature of 135°C or higher and less than 180°C is more preferable because it can withstand drifts in the hot water temperature during hot water sterilization that exceed the set temperature, and the control of the hot water sterilization system can be simplified.

[0032] The glass transition temperature can be controlled, for example, by changing the type of non-imidazole curing agent or by adjusting the amounts of imidazole and non-imidazole curing agents.

[0033] The rubber particles contained in the adhesive of the hollow fiber membrane module of the present invention are dispersed in a particulate state. By dispersing rubber particles in the adhesive, flexibility can be achieved without reducing the heat resistance temperature.

[0034] The hollow fiber membrane module of the present invention has a diameter of 10.0 μm or less of rubber particles in the cross-section of the adhesive. Here, "diameter of rubber particles in the cross-section of the adhesive" refers to the equivalent diameter of a circle calculated by the method described in "Measurement of the diameter of rubber particles in the cross-section of the adhesive" in the examples described later. Therefore, this value differs from the diameter of the rubber particles added to the adhesive. By having a diameter of 10.0 μm or less of rubber particles in the cross-section of the adhesive, it is possible to prevent bridging between the hollow fiber membranes and aggregation of rubber particles when the adhesive is filled between the hollow fiber membranes before curing. From the viewpoint of improving dispersibility and adjusting the viscosity of the adhesive that penetrates between the hollow fiber membranes, the diameter of rubber particles in the cross-section of the adhesive is preferably 0.1 μm or more and 5.5 μm or less, more preferably 0.2 μm or more and 3.0 μm or less, and even more preferably 0.2 μm or more and 1.0 μm or less.

[0035] Further, the diameter of the rubber particles added to the adhesive is preferably 0.1 µm or more and 12.1 µm or less, more preferably 0.1 µm or more and 6.7 µm or less, and still more preferably 0.2 µm or more and 3.6 µm or less.

[0036] Examples of the material of the rubber particles include silicone rubber, butadiene rubber, acrylic rubber and the like, and core-shell structured rubber particles containing these materials (hereinafter referred to as "core-shell rubber particles") may also be used. Among these, rubber particles containing silicone rubber are preferable because an increase in the linear expansion coefficient can be suppressed.

[0037] In the hollow fiber membrane module of the present invention, the rubber particle ratio in the cross-section of the adhesive is 3.0% or more and 25.0% or less. The rubber particle ratio in the cross-section of the adhesive refers to the ratio of the total cross-sectional area of the rubber particles to the cross-sectional area of the adhesive in one field of view observed with a scanning electron microscope, and is measured by the method described in the Examples below.

[0038] When the rubber particle ratio is 3.0% or more, the effect of softening the adhesive by the rubber particles can be obtained, and the occurrence of cracks and the like during cutting processing can be suppressed. On the other hand, when the rubber particle ratio is 25.0% or less, a significant decrease in adhesive strength caused by insufficient proportion of the epoxy resin in the adhesive can be avoided. From the above viewpoints, the rubber particle ratio is preferably 5.0% or more and 20.0% or less, and more preferably 9.0% or more and 15.0% or less. The rubber particle ratio can be controlled by adjusting the content of the rubber particles.

[0039] In the hollow fiber membrane module of the present invention, the dispersion degree of the rubber particles in the cross-section of the adhesive is 2.0 or less. The dispersion degree of rubber particles means the degree of uniform dispersion of the rubber particles, and is 1 when completely uniform. The dispersion degree of the rubber particles is calculated by the method described in the Examples below.

[0040] An adhesive obtained by curing an epoxy resin with an imidazole curing agent is characterized by lower toughness than an adhesive obtained by curing an epoxy resin with a non-imidazole curing agent such as a polyamine or an acid anhydride. Therefore, if there is a region containing no rubber particles in the cross-section of the adhesive, cracks propagate through that region, resulting in cracking. When the dispersion degree of rubber particles is 2.0 or less, the region in the adhesive where no rubber particles are present (hereinafter referred to as "resin region") becomes small, and the propagation of cracks is suppressed even when stress is generated. From the perspective of suppressing crack propagation even against large generated stress, the dispersion degree of rubber particles is preferably 1.7 or less, more preferably 1.5 or less.

[0041] The dispersion degree of rubber particles can be controlled, for example, by bringing the rubber particles into a more uniformly dispersed state when preparing the adhesive before curing. More specifically, since an adhesive using an imidazole curing agent as the main curing agent has high viscosity and makes rubber particles difficult to disperse, the temperature of the epoxy resin, which is the main agent, is increased to lower the viscosity, and after dispersing the rubber particles with a strong dispersing force, the temperature is lowered and then the imidazole curing agent is mixed. This allows the rubber particles to be uniformly dispersed without curing progressing during preparation.

[0042] Among these, epoxy group-containing rubber particles containing an epoxy group having affinity with bisphenol A type epoxy resin, and core-shell rubber particles having, as a shell, a compound having a functional group with affinity for epoxy resin, are particularly preferable because the rubber particles are easily uniformly dispersed in the epoxy resin and the dispersion degree of the rubber particles can be easily adjusted to 2.0 or less. Examples of the compound having a functional group with affinity for epoxy resin include compounds having an acrylic copolymer, an epoxy group, an ether group, and the like.

[0043] The adhesive for the hollow fiber membrane module according to this embodiment contains a polyetheramine curing agent as a non-imidazole curing agent, and it is preferable that the content of the polyetheramine curing agent is 1.0 part by mass or more and less than 15.0 parts by mass per 100 parts by mass of bisphenol A type epoxy resin. An adhesive containing a polyetheramine curing agent as a non-imidazole curing agent in an amount of 1.0 part by mass or more and less than 15.0 parts by mass per 100 parts by mass of bisphenol A type epoxy resin has a lower heat generation temperature during curing and a shorter curing time, thereby suppressing damage to the hollow fiber membrane and improving productivity. When the content of the polyetheramine curing agent, which is a non-imidazole curing agent, is 1.0 part by mass or more, the toughness of the resin region of the adhesive is improved. Furthermore, when the content of the polyetheramine curing agent is less than 15.0 parts by mass, deformation is less likely to occur when subjected to sterilization with hot water at 125°C. Since deformation is less likely to occur even when subjected to hot water at high temperatures such as 135°C, it is more preferable that the polyetheramine content is 1.0 part by mass or more and 7.0 parts by mass or less.

[0044] Examples of polyetheramine curing agents include polyetheramines having a polyether portion composed of propylene oxide, ethylene oxide, or both propylene oxide and ethylene oxide, with different numbers of amine functional groups and molecular weights. The weight-average molecular weight of the polyetheramine curing agent is preferably 100 to 450, and more preferably 200 to 300, as this allows the polyetheramine to polymerize uniformly within the resin region of the adhesive, making it easier to obtain a softening effect.

[0045] In this embodiment, the adhesive for the hollow fiber membrane module preferably has an elastic modulus of less than 3.2 GPa at 23°C, and more preferably 2.2 GPa or more and less than 3.0 GPa, from the viewpoint of suppressing the occurrence of chipping and cracks that can become the starting point of cracking during hot water sterilization in the cutting process. ＩＣ It is preferable that the elastic modulus and strain energy release rate G of the adhesive be 100 N / m or more, and more preferably 130 N / m or more and less than 500 N / m. ＩＣ It is particularly preferable that both conditions are simultaneously within the above range.

[0046] The elastic modulus of the adhesive can be lowered, for example, by increasing the content of rubber particles in the adhesive. However, if the content of rubber particles is excessively increased to lower the elastic modulus, the permeability of the adhesive between hollow fiber membranes deteriorates, which may reduce the durability against hot water of 125°C or higher.

[0047] "Strain energy release rate G ＩＣ " refers to the energy required for crack propagation in a bundled portion where crack initiation points such as scratch marks and voids exist. A higher strain energy release rate G ＩＣ means that even if crack initiation points exist, the bundled portion can resist cracking. In addition, when repeated loads are applied to the bundled portion at high temperatures, a high strain energy release rate G ＩＣ improves the resistance to fatigue fracture and enhances durability in an environment where hot water and water are filtered repeatedly. The strain energy release rate G ＩＣ can be increased, for example, by reducing the dispersion degree of rubber particles in the adhesive, reducing the diameter of rubber particles, and increasing the content of rubber particles or the addition amount of polyetheramine. However, reducing the diameter of rubber particles or increasing the addition amount of rubber particles will deteriorate the permeability of the adhesive between hollow fiber membranes, which may reduce the durability against hot water of 125°C or higher. In addition, increasing the addition amount of polyetheramine may lower the glass transition temperature, resulting in insufficient heat resistance.

[0048] In addition, the adhesive of the hollow fiber membrane module according to the present embodiment has a linear expansion coefficient of 10.0×10 －５ / °C, more preferably 9.0×10 －５ / °C or less. When the linear expansion coefficient is less than 10.0×10 －５ / °C, when the adhesive in the bundled portion thermally expands during hot water sterilization, the stress generated by the difference in thermal expansion between the adhesive and the cylindrical case is reduced, so that the durability is further improved.

[0049] The coefficient of linear expansion can be reduced, for example, by reducing the amount of rubber particles in the adhesive or the amount of polyetheramine added. However, if the amount of rubber particles in the adhesive or the amount of polyetheramine added is reduced too much, the occurrence of chips and cracks that can become the starting point of cracks during hot water sterilization in the cutting process will increase, and the material may not be able to withstand cracks arising from these starting points.

[0050] Since a hollow fiber membrane module with higher durability against hot water above 135°C can be obtained, it is particularly preferable that the curing exothermic temperature of the adhesive is low and that the elastic modulus, strain energy release rate, and linear expansion coefficient at 23°C all meet the above range.

[0051] <Hollow Fiber Membrane> The hollow fiber membrane module of the present invention comprises a hollow fiber membrane bundle 2, which is a bundle of hollow fiber membranes, as a separation membrane. Hollow fiber membranes generally have a larger specific surface area than flat membranes and are advantageous because they can filter a larger volume of liquid per unit time. Examples of hollow fiber membrane structures include symmetrical membranes with uniform pore sizes throughout, asymmetrical membranes where the pore size changes in the thickness direction of the membrane, and composite membranes having a support layer to maintain strength and a separation functional layer for separating target substances.

[0052] The appropriate pore size can be selected depending on the target of isolation, but for the purpose of isolating microorganisms such as bacteria and fungi or animal cells, an average pore size of 10 nm to 600 nm is preferable for the hollow fiber membrane. If the average pore size is less than 10 nm, the water permeability will be low, and if it exceeds 600 nm, there is a possibility that microorganisms may leak out. In this specification, the average pore size refers to the pore size of the dense layer with the smallest pore size.

[0053] Examples of materials for hollow fiber membranes include fluorine-based polymers such as polytetrafluoroethylene, polyvinylidene fluoride, polyvinyl fluoride, tetrafluoroethylene / hexafluoropropylene copolymer, and ethylene / tetrafluoroethylene copolymer; cellulose esters such as cellulose acetate, cellulose acetate propionate, and cellulose acetate butyrate; polysulfone-based polymers such as polysulfone and polyethersulfone; and polymers such as polyacrylonitrile, polyimide, and polypropylene.

[0054] In particular, hollow fiber membranes made of fluorine-based polymers and polysulfone-based polymers are suitable for use in hollow fiber membrane modules in fields such as fermentation, pharmaceutical manufacturing, food processing, and water treatment, where steam sterilization or hot water sterilization is required, due to their high heat resistance, physical strength, and chemical durability.

[0055] Furthermore, the hollow fiber membrane may contain a hydrophilic polymer in addition to the fluorine-based polymer and the polysulfone-based polymer. The hydrophilic polymer enhances the hydrophilicity of the hollow fiber membrane, thereby improving the membrane's water permeability.

[0056] The hydrophilic polymer can be any polymer that can impart hydrophilicity to the hollow fiber membrane. For example, cellulose esters, fatty acid vinyl esters, vinylpyrrolidone, ethylene oxide, propylene oxide, polymethacrylate polymers, polyacrylic acid polymers, and the like are preferably used.

[0057] Polymer hollow fiber membranes have inferior heat resistance compared to ceramic hollow fiber membranes, but they can be manufactured inexpensively and are easily used industrially. When thermal degradation occurs in polymer hollow fiber membranes, problems such as leakage of the filtration solution can occur. Therefore, it is preferable that the temperature during the curing of the adhesive is below the Vicat softening temperature of the hollow fiber membrane. When the temperature during the curing of the adhesive is below the Vicat softening temperature of the hollow fiber membrane, the polymer hollow fiber membrane can maintain its strength, water permeability, and separation performance. The temperature during the curing of the adhesive can be measured by methods such as installing a thermocouple inside the hollow fiber membrane. The Vicat softening temperature of the hollow fiber membrane can be measured in accordance with JIS K 7206. The Vicat softening temperature of the hollow fiber membrane can be measured by melting a section of the raw material of the hollow fiber membrane or the hollow fiber membrane itself and forming it into a plate shape.

[0058] When fabricating hollow fiber membrane modules, it is preferable to dry the hollow fiber membranes beforehand due to handling and adhesion issues. However, since many hollow fiber membranes shrink when dried, reducing their water permeability, it is also possible to use membranes that have been immersed in an aqueous glycerin solution and then dried. When immersed in an aqueous glycerin solution and then dried, the glycerin remains in the pores, preventing shrinkage due to drying, and water permeability can be restored by subsequently immersing them in a solvent such as ethanol.

[0059] In the radial cross-section of the first binding portion, the area occupied by the hollow fiber membrane is preferably 30% or more and less than 90%. Here, the area occupied by the hollow fiber membrane is expressed as the total area enclosed by the outer diameter of the hollow fiber membrane / the area of ​​the radial cross-section of the first binding portion. When the area occupied by the hollow fiber membrane is 30% or more, the membrane area per unit volume of the hollow fiber membrane module is large, and the manufacturing cost per unit area of ​​membrane can be reduced. In addition, the heat generated by the curing reaction of the adhesive during the molding of the first binding portion can be dissipated by the hollow fiber membrane, thus suppressing excessive temperature rise. Furthermore, when the area occupied by the hollow fiber membrane is less than 90%, it is possible to prevent the hollow fiber membranes from being crushed by pressing against each other during the manufacturing of the hollow fiber membrane module.

[0060] While hollow fiber membrane modules can be used after steam sterilization or hot water sterilization, some types of hollow fiber membranes may shrink due to steam sterilization or hot water sterilization. If steam sterilization or hot water sterilization is performed after the hollow fiber membrane module has been manufactured, the shrinkage of the hollow fiber membrane may damage it or cause it to detach from the binding part. Therefore, it is desirable to treat the hollow fiber membrane with steam or hot water at a temperature above the intended operating temperature to shrink it beforehand, then create the binding part and manufacture the hollow fiber membrane module.

[0061] <Sealing Material> The sealing material used in cartridge-type hollow fiber membrane modules, such as O-rings and gaskets, only needs to meet the requirements for heat resistance, chemical durability, etc. For example, fluororubber, silicone rubber, ethylene propylene diene rubber, etc., can be used.

[0062] <Material of the cylindrical case> The material of the cylindrical case used in the cartridge-type hollow fiber membrane module only needs to meet the requirements of heat resistance, chemical durability, etc. Examples include polysulfone polymers, polytetrafluoroethylene, perfluoroalkoxyfluoropolymers and other fluorine-based polymers, polymethylpentene, polyphenylene sulfide, polyetherketone, stainless steel, aluminum, etc.

[0063] <Method for Manufacturing Hollow Fiber Membrane Modules> The method for manufacturing a hollow fiber membrane module of the present invention comprises the following steps: (a) a potting step in which at least one end face of a plurality of hollow fiber membranes is restrained with an adhesive; (b) a step in which the adhesive is cured. Below, an example of the method for manufacturing a cartridge-type hollow fiber membrane module 100 shown in Figures 1 and 2 will be described with reference to the flowchart in Figure 3 and Figure 4. In Figures 1 and 2, a cartridge-type hollow fiber membrane module in which the hollow fiber membrane cartridge is detachable from the housing is described as an example, but the method is also applicable to hollow fiber membrane modules in which the hollow fiber membrane is adhesively fixed to the housing.

[0064] In step (a), the hollow fiber membrane bundle 2 is placed in a potting device and potting is performed to form the first binding portion 3 and the second binding portion 4. In this embodiment, the first binding portion 3 and the second binding portion 4 are formed, but it is sufficient that at least the first binding portion in which the hollow fiber membrane opens is formed, and instead of forming the second binding portion 4, the open end of the hollow fiber membrane bundle 2 on the second binding portion 4 side may be sealed by heat sealing or resin.

[0065] As for the potting method, either the centrifugal potting method, which uses centrifugal force to penetrate the liquid adhesive between the hollow fiber membranes and then cure it, or the static potting method, which uses a metering pump or head to deliver the liquid adhesive and allows it to flow naturally, penetrating between the two bundles of hollow fiber membranes and then curing it, may be used. In the centrifugal potting method, the adhesive penetrates between the hollow fiber membranes easily due to the centrifugal force, and high-viscosity adhesives can also be used. On the other hand, static potting does not require large equipment such as centrifugal molding machines.

[0066] As shown in Figure 4, the first binding portion 3 of the hollow fiber membrane bundle 2 is inserted into the first binding portion forming jig 15, and the second binding portion 4 of the hollow fiber membrane bundle 2 is inserted into the second binding portion forming jig 16. A pin 17 is inserted into the through hole at the bottom of the second binding portion forming jig 16. The end of the hollow fiber membrane bundle 2 on the side forming the first binding portion 3 is sealed in advance with silicone adhesive or the like.

[0067] The adhesive is supplied from the adhesive dispenser 18 to the first binding section forming jig 15 and the second binding section forming jig 16. The adhesive may be supplied to the first binding section forming jig 15 and the second binding section forming jig 16 simultaneously or separately.

[0068] When forming the binding portion using the static potting method, the forming jig shown in Figure 4 is set up vertically, and typically, either the first binding portion or the second binding portion is formed first, and then the other is formed.

[0069] The process of forming the bonded portion may be divided into two stages: an inner layer and an outer layer in the circumferential direction. Dividing it into two stages allows for the dimensional distortion caused by the curing shrinkage of the inner layer adhesive to be eliminated by the formation of the outer layer adhesive. In this case, it is preferable to cover the area where the hollow fiber membrane exists with the inner layer adhesive in the first stage, thereby avoiding the formation of an interface between the inner and outer layers between the hollow fiber membrane.

[0070] The thickness of the outer layer of the binding portion is preferably 2 mm to 8 mm, and more preferably 4 mm to 6 mm. When the thickness of the outer layer is 2 mm or more, the liquid adhesive can easily penetrate when forming the outer layer of the binding portion, making it easier to suppress the retention of air bubbles. In addition, dimensional changes due to curing shrinkage of the outer layer of the binding portion can be reduced, improving dimensional stability.

[0071] The adhesive used for the bonding portion contains bisphenol A type epoxy resin, an imidazole curing agent, a non-imidazole curing agent, and rubber particles. However, to improve the dispersion of the rubber particles, it is preferable to add the imidazole curing agent and the non-imidazole curing agent after mixing the bisphenol A type epoxy and the rubber particles. In this case, the temperature at which the bisphenol A type epoxy and rubber particles are mixed should be 10°C or more higher than the temperature at which the imidazole curing agent and the non-imidazole curing agent are mixed. This lowers the viscosity of the bisphenol A type epoxy and improves the dispersion of the rubber particles. A temperature of 20°C or more is even more preferable. The timing of mixing the imidazole curing agent and the non-imidazole curing agent can be any order as long as they are mixed after the bisphenol A type epoxy and rubber particles have been mixed.

[0072] When the non-imidazole curing agent content in the adhesive is less than 15.0 parts by mass per 100 parts by mass of bisphenol A type epoxy resin, viscosity reduction by the low-viscosity non-imidazole curing agent is generally not achieved, resulting in a high viscosity of the uncured adhesive. Adding rubber particles further increases the viscosity of the adhesive, making it difficult for the adhesive to penetrate between the hollow fiber membranes.

[0073] One method to improve the penetration of adhesives into the hollow fiber membranes is to perform potting in two stages, a first stage and a second stage, at different temperatures. Specifically, by making the temperature of the first stage 10°C or more higher than that of the second stage, the penetration of the adhesive into the hollow fiber membranes before curing is improved, and the curing exothermic temperature can also be suppressed.

[0074] When using a polyamine curing agent, which is a non-imidazole curing agent, applying the potting method described above can lead to rapid curing of the adhesive in the first stage, resulting in uneven distribution of the adhesive between the hollow fiber membranes and resulting in unpenetration. On the other hand, by using an imidazole curing agent as the main curing agent, as in the hollow fiber membrane module of the present invention, the curing of the adhesive in the first stage becomes slower, and unpenetration can be suppressed. When potting is performed in two stages with different temperatures, the temperature of the second stage is preferably 20°C to 60°C, and more preferably 20°C to 50°C. A temperature of 20°C or higher in the second stage can accelerate the curing of the adhesive. Furthermore, a temperature of 60°C or lower in the second stage can suppress excessive heat generation during curing, and a temperature of 50°C or lower allows for less heat protection measures for the worker, improving work efficiency.

[0075] Furthermore, when polyetheramine is added as a non-imidazole curing agent, in addition to the viscosity reduction caused by the polyetheramine, the reaction heat between the main component, bisphenol A type epoxy resin, and the polyetheramine causes a temperature increase of about 10°C. This lowers the viscosity of the adhesive before curing, making it easier for the adhesive to penetrate between the hollow fiber membranes. Even when polyetheramine is added as a non-imidazole curing agent, a method of potting in two stages with different temperatures can be used in combination.

[0076] The cured adhesive can be further strengthened by curing in step (b). Specifically, it is preferable to heat-treat the cured adhesive at 120°C or higher, and more preferably at 140°C or higher. By heat-treating the cured adhesive at 120°C or higher, the adhesive will exhibit sufficient strength even during high-temperature operations such as hot water sterilization at 125°C. Furthermore, by heat-treating the cured adhesive at 140°C or higher, the adhesive will exhibit sufficient strength over a long period of time even during high-temperature operations such as hot water sterilization at 135°C or higher.

[0077] Furthermore, it is preferable to gradually increase the temperature during heat treatment. For example, one method is to gradually increase the heat treatment temperature, starting with 60°C for a certain period of time, then increasing to 100°C, 120°C, and so on.

[0078] After the adhesive has hardened, remove the first binding section forming jig 15, the second binding section forming jig 16, and the pin 17. The time and temperature required for hardening vary depending on the components of the adhesive, so appropriate conditions should be applied as needed.

[0079] The C-C line portion of the first binding portion 3 in Figure 4 is cut with a circular saw blade, opening the end of the hollow fiber membrane bundle 2 of the first binding portion 3 (step S2).

[0080] Through the above process, a hollow fiber membrane cartridge 101 is obtained in which a first binding portion 3 and a second binding portion 4 are formed at the ends of the hollow fiber membrane bundle 2.

[0081] Finally, the obtained hollow fiber membrane cartridge 101 is inserted into the cylindrical case 1, and the upper cap 7 is fixed to the first end side of the cylindrical case 1 and the lower cap 8 is fixed to the second end side to manufacture the cartridge-type hollow fiber membrane module 100 (step S3).

[0082] The above-described additional heat treatment may be performed after removing the binding portion forming jig and pins, or after cutting the C-C line portion and opening the first end of the hollow fiber membrane bundle 2 of the first binding portion 3.

[0083] The material of the jig for forming the binding portion is not particularly limited as long as it satisfies the requirements of heat resistance, chemical durability, etc., but for example, vinyl chloride polymers, nylon polymers, fluorine polymers, polypropylene polymers, polyacetal polymers, polyethylene polymers, silicone polymers, etc. are preferably used because they also have excellent release properties. The jig for forming the potting portion may use a single material or a combination of multiple materials including at least one of the materials described above.

[0084] Furthermore, the material of the pins is not particularly limited as long as it satisfies heat resistance, chemical durability, etc., but for example, the same material as that used for the binding part forming jig can be used. If metal is used, a coating of a fluorine-based polymer may be applied to improve release properties.

[0085] <Operation Method of Hollow Fiber Membrane Module> In filtration operation using the cartridge-type hollow fiber membrane module 100, the filtration stock enters from the filtration stock inlet 10, passes through the holes 5 formed in the second binding section 4 from bottom to top, and is introduced between the hollow fiber membrane bundles 2. The filtration stock is filtered by the hollow fiber membrane and moves as filtrate into the space surrounded by the first binding section 3 and the upper cap 7, and is then removed from the hollow fiber membrane module through the filtrate outlet 9.

[0086] When performing dead-end filtration, the filtration stock outlet 12 should be closed. When performing cross-flow filtration, a portion of the filtration stock introduced into the cylindrical case 1 should be removed from the filtration stock outlet 12. Alternatively, the filtration stock removed from the filtration stock outlet 12 may be reintroduced into the hollow fiber membrane module through the filtration stock inlet 10.

[0087] Cross-flow filtration facilitates flow within the hollow fiber membrane module, resulting in reduced turbidity buildup and membrane surface cleaning due to flow near the membrane surface. Cross-flow filtration is widely used, particularly in the fermentation industry, pharmaceutical and medical fields, and the food industry.

[0088] Generally, after performing filtration using a hollow fiber membrane module for a certain period, a process is provided to clean the inside of the hollow fiber membrane module, and water, chemicals, gas, etc. are supplied from the filtration stock inlet 10. In processes requiring high-temperature hot water sterilization, pressurized hot water at about 125°C is supplied.

[0089] In the washing process, for example, a method may be used in which filtrate, water, or washing solution is introduced from the filtrate outlet 9 and discharged to the outside from the hollow portion of the hollow fiber membrane bundle 2, or a method may be used in which hot water is flowed from the top to the bottom of the holes 5 and the hot water is discharged outside the hollow fiber membrane module from the filtrate inlet 10.

[0090] The present invention will be described below with reference to specific examples, but the present invention is not limited in any way by these examples.

[0091] <Materials used in the adhesive> Bisphenol A type epoxy resin: jER (registered trademark) 828, manufactured by Mitsubishi Chemical Corporation 2-ethyl-4-methylimidazole: manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. Silicone core-shell rubber particles: Kaneace (registered trademark) MX-962, manufactured by Kaneka Corporation, particle size 0.2 μm, core-shell rubber particle content 25% by mass Epoxy-modified silicone particles: DOWSIL (registered trademark) EP2601, manufactured by Dow Ltd., particle size 2 μm Silicone particles: KMP-600, manufactured by Shin-Etsu Chemical Co., Ltd., particle size 5 μm Polyetheramine: JEFFAMINE (registered trademark) D230, manufactured by Huntsman Japan Co., Ltd., Mw230

[0092] <Measurement of Glass Transition Temperature> Adhesive cut from a hollow fiber membrane module was used as the measurement sample. A temperature-modulated differential scanning calorimetry device (DSC 2500SR, manufactured by TA Corporation) was used to measure the temperature at a heating rate of 5°C / min, a temperature modulation of ±1°C, a modulation period of 60 seconds, and under a nitrogen atmosphere. The reversible heat flow curve was measured. In accordance with JIS K 7121-1987, the transition midpoint temperature was determined as the glass transition temperature from the measured reversible heat flow curve.

[0093] <Measurement of Rubber Particle Diameter in Adhesive Cross-Sections> Using a scanning electron microscope (Hitachi, Ltd. S-5500), images of the cross-section of the adhesive cut from a hollow fiber membrane module were taken at five randomly different locations, magnified to a magnification such that the rubber particles appeared at approximately 1 / 10th of their size relative to the short side of the field of view. The adhesive cross-sections were taken from the surface of the binding portion of the hollow fiber membrane module and from the adhesive at least 1 mm inside the hollow fiber membrane surface within the binding portion, and these were used as measurement samples. Using the image software Paint, the rubber particles were colored black along their shape on the captured cross-sectional images of the adhesive. Next, using the image processing software ImageJ, the images with the rubber particles colored black were binarized (Threshold processing) to obtain rubber particle detection images in which only the rubber particles were detected. The area of ​​each rubber particle in the rubber particle detection image was calculated using area calculation processing (Analyze Particle processing), and the equivalent diameter of a circle was calculated from the area. During the area calculation process, rubber particles included at the edges of the images were excluded from the calculation using the "Exclude on edges" function of the image processing software. The average of the circular equivalent diameters of all rubber particles in the five images was rounded to two decimal places to obtain the diameter of the rubber particles.

[0094] <Measurement of Rubber Particle Ratio in Adhesive Cross-Sections> The area of ​​each rubber particle was calculated using the same method as described above for "Measurement of Rubber Particle Diameter in Adhesive Cross-Sections," except that the Exclude on edges function was not used during the area calculation process, and rubber particles included in the edges of the image were also included in the measurement. For the adhesive cross-sections, samples were taken from the surface of the binding portion of the hollow fiber membrane module and from the adhesive at least 1 mm inside the hollow fiber membrane surface within the binding portion. The areas of all rubber particles obtained in one image were summed, and the ratio to the area of ​​that image was calculated to determine the rubber particle ratio. The rubber particle ratio was calculated similarly for five different images, and the average value was rounded to two decimal places to determine the rubber particle ratio.

[0095] <Measurement of the dispersion of rubber particles in the cross-section of adhesive> Using a scanning electron microscope (Hitachi, Ltd. S-5500), images of the cross-section of the adhesive cut from the hollow fiber membrane module were taken at five randomly selected locations, magnified to a level where the rubber particles appeared approximately 1 / 50th of their original size relative to the short side of the field of view. Similar to the "Measurement of the diameter of rubber particles in the cross-section of adhesive" described above, the images in which the rubber particles were blacked out were binarized to obtain rubber particle detection images. For the adhesive cross-section, samples were taken from the surface of the binding portion of the hollow fiber membrane module and from the adhesive more than 1 mm inside the hollow fiber membrane surface within the binding portion. After contrast inversion processing (Invert processing) of the rubber particle detection images, division processing (Voronoi processing) was performed using the Voronoi division function. The dividing lines between the divided Voronoi regions were binarized (Threshold process) within the Voronoi regions, and then the area of ​​each divided Voronoi region was calculated using the area calculation process (Analyze Particle process). In the area calculation process, Voronoi regions at the edges of the image were excluded from the calculation using the Exclude on edges function of the image software. Using the area of ​​each Voronoi region, the particle occupancy polydispersity D was calculated from equations 1 to 3 below. Here, An is the average area by number of pixels of the Voronoi region, Aw is the average area by pixel weight of the Voronoi region, Nx is the number of Voronoi regions, and Ax is the pixel area of ​​each Voronoi region. The particle occupancy polydispersity D was taken as the dispersion degree of rubber particles in the cross-section of the adhesive. The dispersion of rubber particles was calculated for each of the five images taken, and the average value was rounded to two decimal places to represent the dispersion of rubber particles.

[0096]

[0097] <Measurement of Elastic Modulus at 23°C> Adhesive was cut from the binding portion of the hollow fiber membrane module to create a 10 mm x 10 mm x 5 mm test specimen. The elastic modulus was measured using the continuous stiffness measurement method with a KLA Tencor Nano Indenter G200X (Infore 1000) ultramicrohardness tester in a room controlled to a 23°C atmosphere. For the adhesive cutting, the adhesive from the surface of the binding portion of the hollow fiber membrane module and the adhesive from more than 1 mm inside the hollow fiber membrane surface within the binding portion were cut and used as the measurement sample.

[0098] <Measurement of Linear Expansion Coefficient> Two test specimens were prepared from adhesive cut to 10 mm x 10 mm x 5 mm from the binding portion of the hollow fiber membrane module, and the linear expansion coefficient was measured in accordance with JIS K 7197. The adhesive was cut from the surface of the binding portion of the hollow fiber membrane module and from the adhesive at least 1 mm inside the hollow fiber membrane surface within the binding portion to be used as measurement samples. A TMA8311 (manufactured by Rigaku Corporation) was used, and the measurement conditions were 23°C to 200°C at a speed of 5°C / min, in a nitrogen atmosphere (50 ml / min), and N=2. The tangent intersection point was determined from the obtained measurement results, and the linear expansion coefficient in the temperature range below the tangent intersection point was calculated.

[0099] <Strain energy release rate G> ＩＣ Measurement > Five 60mm x 12mm x 6mm test pieces were prepared by cutting adhesive from the binding portion of a hollow fiber membrane module and pre-cracking the notched portion. A 60mm x 12mm x 6mm blank test piece without the notched portion or pre-crack was also prepared. The cross-section of the adhesive was measured by cutting adhesive from the surface of the binding portion of the hollow fiber membrane module and from the inside of the binding portion at least 1mm inward from the hollow fiber membrane surface. In accordance with ASTM D5045-14, a bending test was performed in a controlled room at 23°C using a universal testing machine 59R5582 (manufactured by Instron Co., Ltd.) at a speed of 1mm / min and N=5. Next, as a blank test, an indentation test was performed on the blank test piece. From the results of the sample test and the blank test, the strain energy release rate G was calculated. ＩＣ The result was calculated.

[0100] <Evaluation of Hot Water Filtration Durability> The obtained hollow fiber membrane modules were subjected to a total of 50 thermal cycle tests, each cycle consisting of passing hot water at 125°C or 135°C for 30 minutes, followed by passing water at 25°C for 30 minutes. An air leak test was performed every 10 thermal cycle tests to evaluate the sealing performance of the hollow fiber membrane modules. With the filtration liquid inlet sealed and the filtrate outlet open, compressed air at 100 kPa was supplied from the filtration liquid outlet. After all the water present on the filtration liquid side of the hollow fiber membrane module had been filtered, the filtration liquid outlet was sealed, and the pressure change on the filtration liquid side of the hollow fiber membrane module was measured over 5 minutes. If the sealing performance of the first binding section is insufficient, air leaks to the filtrate side, causing the pressure on the module filtration liquid side to drop by 5 kPa or more in 5 minutes.

[0101] [Example 1] (a) Preparation of hollow fiber membrane 38 parts by mass of vinylidene fluoride homopolymer with a weight-average molecular weight of 417,000 and 62 parts by mass of γ-butyrolactone were mixed and dissolved at 160°C. This polymer solution was discharged from the nozzle of a double-walled tube while an 85% by mass aqueous solution of γ-butyrolactone was added as a hollow-forming liquid, and the solution was solidified in a cooling bath consisting of an 85% by mass aqueous solution of γ-butyrolactone at a temperature of 20°C, which was placed 30 mm below the nozzle, to prepare a hollow fiber membrane with a spherical structure. Next, 14 parts by mass of vinylidene fluoride homopolymer with a weight-average molecular weight of 284,000, 1 part by mass of cellulose acetate propionate (Eastman Chemical Company, CAP482-0.5), 77 parts by mass of N-methyl-2-pyrrolidone, 5 parts by mass of polyoxyethylene sorbitan fatty acid ester (Sanyo Chemical Industries, Ltd., IONET® T-20C), and 3 parts by mass of water were mixed and dissolved at 95°C to prepare a polymer solution. This film-forming stock solution was uniformly applied to the surface of the hollow fiber membrane consisting of the spherical structure obtained above, and immediately solidified in a water bath to prepare a hollow fiber membrane in which a three-dimensional mesh structure was formed on the spherical structure layer. The obtained hollow fiber membrane had an outer diameter of 1350 μm and an inner diameter of 800 μm, with an average pore size of 40 nm on the membrane surface. When a section of the hollow fiber membrane was melted and formed into a plate, the Vicat softening temperature was measured using an HDT test apparatus (Toyo Seiki Seisakusho 3M-2 model), and it was found to be 170°C.

[0102] (b) Preparation of hollow fiber membrane cartridges The hollow fiber membrane obtained in (a) above was cut to a length of 1800 mm, immersed in a 30% by mass glycerin aqueous solution for 1 hour, and then air-dried. This hollow fiber membrane was heat-treated with steam at 135°C for 1 hour and air-dried, and then cut to a length of 1200 mm. After that, the ends of the hollow fiber membranes that would form the first binding part were sealed with silicone adhesive (SH850A / B manufactured by Toray Dow Corning Co., Ltd., mixed with the two components in a mass ratio of 50:50). Then, 2000 hollow fiber membranes were bundled together to form a hollow fiber membrane bundle, and a jig for forming the first binding part and a jig for forming the second binding part were placed at each end. A pin for forming a through hole was inserted into the bottom of the jig for forming the second binding part.

[0103] As an adhesive for forming the binding portion, a total of 400 g was mixed for the first binding portion and a total of 150 g for the second binding portion, according to the formulation shown in Table 1. The adhesive was mixed by heating the bisphenol A type epoxy resin to 60°C to reduce its viscosity, then adding rubber particles, and mixing for 10 minutes using an ARV-310P rotary mixer at a rotational speed of 2000 rpm and a vacuum of 0.7 kPa. After the resulting mixture was allowed to cool to 25°C, a curing agent was added, and the mixture was mixed again for 1 minute at a rotational speed of 2000 rpm and a vacuum of 0.7 kPa.

[0104] Next, in the potting process, the mixed adhesive was placed in an adhesive dispenser, and the centrifugal molding machine was rotated at 350 rpm to fill the adhesive into the binding parts forming jigs at both ends. At this time, the machine was operated at the first stage temperature listed in Table 1 for 1 hour and at the second stage temperature for 20 hours to cure the adhesive, thereby forming the first and second binding parts. Furthermore, after the adhesive had cured, it was heat-treated at 100°C for 24 hours, and then heat-treated again at 140°C for 24 hours in a sealed container filled with water. After that, the binding part forming jigs and pins were removed, and the ends of the first binding part were cut with a circular saw blade to open the end faces of the hollow fiber membrane and produce a hollow fiber membrane cartridge.

[0105] The maximum heat generated by the adhesive was measured by curing 400g of adhesive in a container in a constant temperature chamber controlled to the first and second stage temperatures of the potting process described above. The maximum value of the temperature profile measured by a thermocouple placed in the center of the adhesive in the container was defined as the maximum heat generated by the adhesive.

[0106] (c) Preparation of hollow fiber membrane module The obtained hollow fiber membrane cartridge was inserted into a cylindrical case, and upper and lower caps were attached to both ends to form a hollow fiber membrane module. Then, ethanol was injected into the hollow fiber membrane module and filtered to fill the pores of the hollow fiber membrane with ethanol. Subsequently, water that had permeated through an RO membrane (hereinafter referred to as "RO water") was injected and filtered to replace the ethanol with RO water and obtain a hollow fiber membrane module.

[0107] [Example 2] The adhesive formulation for forming the binding portion was changed to the formulation shown in Table 1, and polyetheramine was mixed at the same time as 2-ethyl-4-methylimidazole. Furthermore, a hollow fiber membrane module was fabricated in the same manner as in Example 1, except that the potting process was carried out continuously for 15 hours at the first-stage temperature as shown in Table 1.

[0108] [Example 3] A hollow fiber membrane module was prepared in the same manner as in Example 2, except that the composition of the adhesive used to form the binding portion was changed to the composition shown in Table 1.

[0109] [Example 4] A hollow fiber membrane module was prepared in the same manner as in Example 2, except that the composition of the adhesive used to form the binding portion was changed to the composition shown in Table 1.

[0110] [Example 5] A hollow fiber membrane module was prepared in the same manner as in Example 1, except that the composition of the adhesive used to form the binding portion was changed to the composition shown in Table 1. Here, MX-962 is a bisphenol A type epoxy dispersion containing 25% by mass of core-shell particles, and the mass portion of rubber particles shown in Table 1 is the mass portion of core-shell particles in the final adhesive obtained by adding bisphenol A type epoxy resin.

[0111] [Example 6] A hollow fiber membrane module was prepared in the same manner as in Example 5, except that the composition of the adhesive used to form the binding portion was changed to the composition shown in Table 1.

[0112] [Example 7] A hollow fiber membrane module was prepared in the same manner as in Example 5, except that the composition of the adhesive used to form the binding portion was changed to the composition shown in Table 1.

[0113] [Example 8] The adhesive formulation for forming the binding portion was changed to the formulation shown in Table 1, and polyetheramine was mixed at the same time as 2-ethyl-4-methylimidazole. Furthermore, a hollow fiber membrane module was fabricated in the same manner as in Example 3, except that the potting process was carried out continuously for 15 hours at the first-stage temperature as shown in Table 1. The proportion of rubber particles shown in Table 1 is the same as in Example 5.

[0114] [Example 9] A hollow fiber membrane module was fabricated in the same manner as in Example 1, except that the first-stage temperature of the potting process was set to 40°C.

[0115] [Comparative Examples 1-2] Hollow fiber membrane modules were prepared in the same manner as in Example 1, except that the composition of the adhesive used to form the binding portion was changed to the composition shown in Table 1.

[0116] [Comparative Example 3] A hollow fiber membrane module was prepared in the same manner as in Example 1, except that in the mixing of the adhesive, rubber particles and 2-ethyl-4-methylimidazole were added to the bisphenol A type epoxy resin at 25°C without heating to reduce its viscosity, and the mixture was then mixed for 1 minute using a rotational mixer ARV-310P at a rotational speed of 2000 rpm and a vacuum of 0.7 kPa.

[0117] [Comparative Example 4] A hollow fiber membrane module was prepared in the same manner as in Example 2, except that the composition of the adhesive used to form the binding portion was changed to the composition shown in Table 1.

[0118]

[0119]

[0120] The hollow fiber membrane module of the present invention can be used in a high temperature range and can be applied in particular when the liquid to be filtered is at a high temperature, or in processes requiring hot water sterilization or steam sterilization.

[0121] 100: Hollow fiber membrane module 101: Hollow fiber membrane cartridge 1: Cylindrical case 1A: Flange 1B: Flange 2: Hollow fiber membrane bundle 3: First binding section 4: Second binding section 5: Hole 6: Adhesive 7: Upper cap 7A: Step 8: Lower cap 9: Filtrate outlet 10: Filtration liquid inlet 11: Gasket 12: Filtration liquid outlet 13: Sealing material 14: Sealing material 15: Jig for forming the first binding section 16: Jig for forming the second binding section 17: Pin 18: Adhesive dispenser

Claims

1. A hollow fiber membrane module comprising: a cylindrical case; a hollow fiber membrane bundle having a plurality of hollow fiber membranes housed within the cylindrical case; and at least one binding portion in which the plurality of hollow fiber membranes are bound together with an adhesive, wherein the adhesive contains a bisphenol A type epoxy resin, an imidazole curing agent, and rubber particles, the content of the non-imidazole curing agent is less than 15.0 parts by mass per 100 parts by mass of the bisphenol A type epoxy resin, and the glass transition temperature is 125°C or higher and less than 180°C; the diameter of the rubber particles in the cross-section of the adhesive is 10.0 μm or less, the rubber particle ratio is 3.0% or higher and 25.0% or lower, and the dispersion degree of the rubber particles is 2.0 or lower.

2. The adhesive has an elastic modulus of less than 3.2 GPa at 23°C and a strain energy release rate G ＩＣ The hollow fiber membrane module according to claim 1, wherein the density is 100 N / m or more.

3. The adhesive has a linear expansion coefficient of 10.0 × 10 －５ The hollow fiber membrane module according to claim 1 or 2, wherein the temperature is less than / ℃.

4. The hollow fiber membrane module according to claim 1 or 2, wherein the rubber particles are core-shell rubber particles or epoxy group-containing rubber particles.

5. The hollow fiber membrane module according to claim 1 or 2, wherein the rubber particles are silicone.

6. The hollow fiber membrane module according to claim 1 or 2, wherein the non-imidazole curing agent is a polyetheramine curing agent, the content of the polyetheramine curing agent in the adhesive is 1.0 part by mass or more and 7.0 parts by mass or less per 100 parts by mass of the bisphenol A type epoxy resin, and the weight-average molecular weight of the polyetheramine curing agent is 100 or more and 450 or less.

7. A method for manufacturing a hollow fiber membrane module, comprising: (a) a potting step of restraining at least one end face of a plurality of hollow fiber membranes with an adhesive; and (b) a step of curing the adhesive, wherein the adhesive in step (a) comprises a bisphenol A type epoxy resin, an imidazole curing agent, and rubber particles, the content of the non-imidazole curing agent is less than 15.0 parts by mass per 100 parts by mass of the bisphenol A type epoxy resin, the glass transition temperature after step (b) is 125°C or higher and less than 180°C, and the diameter of the rubber particles in the cross-section of the adhesive is 10.0 μm or less, the rubber particle ratio is 3.0% or higher and 25.0% or lower, and the dispersion degree of the rubber particles is 2.0 or lower.

8. The adhesive used in step (a) has an elastic modulus of less than 3.2 GPa at 23°C after step (b), and a strain energy release rate G ＩＣ A method for manufacturing a hollow fiber membrane module according to claim 7, wherein the density is 100 N / m or more.

9. The adhesive used in step (a) has a linear expansion coefficient of 10.0 × 10 after step (b). －５ A method for manufacturing a hollow fiber membrane module according to claim 7 or 8, wherein the temperature is less than / ℃.

10. The method for manufacturing a hollow fiber membrane module according to claim 7 or 8, wherein the rubber particles used in step (a) are core-shell rubber particles or epoxy group-containing rubber particles.

11. The method for manufacturing a hollow fiber membrane module according to claim 7 or 8, wherein the rubber particles used in step (a) are silicone.

12. The method for producing a hollow fiber membrane module according to claim 7 or 8, wherein the non-imidazole curing agent used in step (a) is a polyetheramine curing agent, the content of the polyetheramine curing agent in the adhesive is 1.0 part by mass or more and 7.0 parts by mass or less per 100 parts by mass of the bisphenol A type epoxy resin, and the weight-average molecular weight of the polyetheramine curing agent is 100 or more and 450 or less.

Images