Resin compositions, pellets, and molded articles

Abstract

To provide a new resin composition with excellent film resistance, as well as pellets and molded articles. [Solution] A biofilm-resistant resin composition comprising a polyacetal resin and 0.1 to 5.0 parts by mass of polyalkylene glycol per 100 parts by mass of the polyacetal resin.

Description

[Technical Field]

[0001] This invention relates to resin compositions, pellets, and molded articles. In particular, it relates to resin compositions with excellent biofilm resistance. [Background technology]

[0002] A slimy, thin, film-like structure often forms on the surface of substances in water. For example, such structures, which can be found on the inside of vases or sinks, are called biofilms formed by microorganisms. Dental plaque is also known as a type of biofilm. Furthermore, efforts are being made to suppress the formation of biofilms (Patent Document 1). [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] International Publication No. 2019 / 159864 [Overview of the project] [Problems that the invention aims to solve]

[0004] As mentioned above, biofilm formation is common, and the demand for new biofilm-resistant resin compositions is increasing. The present invention aims to solve these problems and to provide a new resin composition with excellent biofilm resistance, as well as pellets and molded articles. [Means for solving the problem]

[0005] Based on the above challenges, we found that these problems can be solved by blending polyalkylene glycol with polyacetal resin. Specifically, the above problem was solved by the following means. [1] Polyacetal resin and The above-mentioned polyacetal resin contains 100 parts by mass of polyalkylene glycol, with a total of 0.1 to 5.0 parts by mass of polyalkylene glycol. Biofilm-resistant resin composition. [2] The biofilm-resistant resin composition according to [1], wherein the content of the polyalkylene glycol is 0.5 to 3.5 parts by mass per 100 parts by mass of the polyacetal resin. [3] The biofilm-resistant resin composition according to [1] or [2], wherein the polyalkylene glycol comprises polyethylene glycol. [4] The biofilm-resistant resin composition according to any one of [1] to [3], wherein the number average molecular weight determined from the hydroxyl value of the polyalkylene glycol is 1000 to 4000. [5] The biofilm-resistant resin composition according to any one of [1] to [4], wherein the water contact angle of the surface of a molded article formed from the biofilm-resistant resin composition is 45 to 69°. [6] The content of the polyalkylene glycol is 0.5 to 3.5 parts by mass per 100 parts by mass of the polyacetal resin. The polyalkylene glycol comprises polyethylene glycol, The number-average molecular weight of the polyalkylene glycol, as determined from its hydroxyl value, is between 1000 and 4000. The biofilm-resistant resin composition according to any one of [1] to [5], wherein the water contact angle of the surface of a molded article formed from the biofilm-resistant resin composition is 45 to 69°. Pellets of the biofilm-resistant resin composition described in any one of [7][1] to [6]. A molded product formed from the pellets described in [8] and [7]. A molded article formed from any one of the biofilm-resistant resin compositions described in [9], [1], to [6]. [Effects of the Invention]

[0006] The present invention makes it possible to provide a new resin composition with excellent biofilm resistance, as well as pellets and molded articles. [Modes for carrying out the invention]

[0007] The following describes in detail embodiments for carrying out the present invention (hereinafter simply referred to as "this embodiment"). Note that the following embodiment is illustrative for explaining the present invention, and the present invention is not limited to this embodiment. In this specification, "~" is used to mean that the numerical values ​​before and after it are included as the lower and upper limits. Furthermore, the upper and lower limits of the numerical values ​​in this specification are given as examples of this embodiment, regardless of the combination of upper and lower limits. In this specification, a preferred combination of embodiments is a more preferred embodiment. In this specification, all physical properties and characteristic values ​​shall be those at 23°C unless otherwise specified.

[0008] If the measurement methods, etc., described in the standards shown in this specification differ from year to year, unless otherwise specified, the standards as of January 1, 2024 shall apply. If the measurement methods, etc., described in the standards shown in this specification have been discontinued as of January 1, 2024, the standards in effect at the time of discontinuation shall apply.

[0009] The resin composition of this embodiment is a biofilm-resistant resin composition comprising a polyacetal resin and 0.1 to 5.0 parts by mass of polyalkylene glycol per 100 parts by mass of the polyacetal resin. Biofilms are slimy, thin, membrane-like structures formed by microorganisms. Therefore, the inventors aimed to improve the hydrophilicity of the surface of the molded product to prevent slime buildup. Specifically, by making the surface of the molded product hydrophilic, the adhesion of microorganisms and dirt is suppressed, making it difficult for slimy biofilms to form.

[0010] The embodiments of the present invention will be described in detail below, but the description of the constituent elements described below is merely one example of an embodiment of the present invention and is not limited to these.

[0011] <Polyacetal resin> The resin composition of this embodiment contains a polyacetal resin. The polyacetal resin is not particularly limited in terms of its type or the like, and may be a homopolymer containing only divalent oxymethylene groups as constituent units, or a copolymer containing divalent oxymethylene groups and divalent oxyalkylene groups having 2 to 6 carbon atoms as constituent units.

[0012] Examples of the oxyalkylene group having 2 to 6 carbon atoms include an oxyethylene group, an oxypropylene group, and an oxybutylene group.

[0013] In the polyacetal resin, the ratio of the divalent oxyalkylene group having 2 to 6 carbon atoms to the total number of moles of the oxymethylene group and the divalent oxyalkylene group having 2 to 6 carbon atoms is not particularly limited, and may be 0.5 to 10 mol%.

[0014] To produce the above polyacetal resin, trioxane is usually used as the main raw material. In addition, to introduce a divalent oxyalkylene group having 2 to 6 carbon atoms into the polyacetal resin, cyclic formal or cyclic ether can be used. Specific examples of cyclic formal include 1,3-dioxolane, 1,3-dioxane, 1,3-dioxepane, 1,3-dioxocane, 1,3,5-trioxepane, 1,3,6-trioxocane, etc., and specific examples of cyclic ether include ethylene oxide, propylene oxide, and butylene oxide. To introduce an oxyethylene group into the polyacetal resin, 1,3-dioxolane may be used as the main raw material, to introduce an oxypropylene group, 1,3-dioxane may be used as the main raw material, and to introduce an oxybutylene group, 1,3-dioxepane may be used as the main raw material. In the polyacetal resin, it is preferable that the amount of hemi-formal end groups, the amount of formyl end groups, and the amount of end groups unstable to heat, acid, and base are small. Here, the hemi-formal end group is represented by -OCH2OH, and the formyl end group is represented by -CHO.

[0015] The polyacetal resin used in this embodiment preferably has a melt volume rate (MVR) measured according to ISO 1133 under the conditions of a temperature of 190 °C and a load of 2.16 kg of 0.5 cm 3 / 10 minutes or more, more preferably 0.6 cm 3 / 10 minutes or more, even more preferably 0.8 cm 3 / 10 minutes or more, still more preferably 1 cm 3 / 10 minutes or more, even more preferably 5 cm 3 / 10 minutes or more, and even more preferably. By setting the lower limit value or more, the productivity of the resin composition tends to be further improved. Further, the MVR of the polyacetal resin is preferably 20 cm 3 / 10 minutes or less, more preferably 18 cm 3 [[ID=1S]] / 10 minutes or less, even more preferably 14 cm 3 / 10 minutes or less, still more preferably 10 cm 3 / 10 minutes or less, even more preferably 8 cm 3 / 10 minutes or less, and even more preferably.

[0016] As the polyacetal resin, in addition to the above, the polyacetal resins described in paragraphs 0018 to 0043 of JP-A-2015-074724 can be used, and the contents thereof are incorporated herein. The polyacetal resin used in this embodiment may be recycled products (including recycled products, material recycled products, chemical recycled products, etc.), defective products, or trimming materials during molding.

[0017] The resin composition of this embodiment preferably contains the polyacetal resin at a ratio of 90% by mass or more of the resin composition, more preferably 95% by mass or more, and even more preferably 97% by mass or more. The upper limit is the amount at which the total amount other than the polyalkylene glycol becomes the polyacetal resin. The resin composition of this embodiment may contain only one kind of polyacetal resin or two or more kinds of polyacetal resins. When two or more kinds are contained, the total amount preferably falls within the above range.

[0018] <Polyalkylene glycol> The resin composition of this embodiment contains polyalkylene glycol. The inclusion of polyalkylene glycol results in a molded article with excellent biofilm resistance.

[0019] While polyalkylene glycol is not specifically defined, examples include polyethylene glycol, polyethylene-polypropylene glycol, and polypropylene glycol, with polyethylene glycol being preferred.

[0020] Furthermore, the number-average molecular weight of the polyalkylene glycol, determined from the hydroxyl value of the polyalkylene glycol, is preferably 1000 or more, more preferably 2000 or more, even more preferably 2500 or more, preferably 5000 or less, and more preferably 4000 or less. Setting it above the lower limit tends to effectively suppress the washing away of polyalkylene glycol present on the surface. Setting it below the upper limit tends to allow the polyalkylene glycol to spread sufficiently on the surface of the molded product, further improving biofilm resistance.

[0021] The polyalkylene glycol content in the resin composition of this embodiment is preferably 0.3% by mass or more, more preferably 0.5% by mass or more, even more preferably 0.8% by mass or more, even more preferably 1.5% by mass or more, and even more preferably 2.5% by mass or more. Setting the content above the lower limit tends to make the surface of the molded product more hydrophilic and improve biofilm resistance. The upper limit of the polyalkylene glycol content is preferably 5% by mass or less, preferably 4% by mass or less, and more preferably 3.5% by mass or less. Setting the content below the upper limit tends to maintain the strength of the resulting molded product and further suppress the amount of formaldehyde emitted.

[0022] The polyalkylene glycol content in the resin composition of this embodiment is 0.1 parts by mass or more, preferably 0.3 parts by mass or more, more preferably 0.5 parts by mass or more, and 5.0 parts by mass or less, preferably 4.0 parts by mass or less, more preferably 3.5 parts by mass or less, and even more preferably 3.0 parts by mass or less, per 100 parts by mass of polyacetal resin. Setting the content above the lower limit tends to make the surface of the molded product more hydrophilic and improve biofilm resistance. The resin composition of this embodiment may contain only one type of polyalkylene glycol, or it may contain two or more types. When it contains two or more types, it is preferable that the total amount is within the above range.

[0023] <Other ingredients> The resin composition of this embodiment may contain known additives and fillers, to the extent that it does not impair the objectives of the present invention. Examples of additives and fillers that can be used in this embodiment include, as needed, known thermoplastic polymers other than polyacetal resin, weathering agents, formaldehyde scavengers, inorganic particles, antioxidants (hindered amine-based, hindered phenol-based), heat stabilizers, colorants, nucleating agents, plasticizers, fluorescent whitening agents, mold release agents, antistatic agents, ultraviolet absorbers (such as benzotriazole-based or benzophenone-based compounds), flame retardants, and flame retardant enhancers. The resin composition of this embodiment is prepared so that the total of the polyacetal resin, polyalkylene glycol, and other components added as needed is 100% by mass. Preferably, the total of the polyacetal resin and polyalkylene glycol in the resin composition of this embodiment is 90% by mass or more, more preferably 95% by mass or more, even more preferably 96% by mass or more, even more preferably 98% by mass or more, and may be 99% by mass or more.

[0024] The resin composition of this embodiment preferably contains substantially no hydrophobic substances such as silicone. "Substantially no hydrophobic substances such as silicone" means that the content of hydrophobic substances such as silicone in the resin composition is less than 20% by mass of the polyalkylene glycol content, preferably less than 10% by mass, more preferably less than 7% by mass, even more preferably less than 5% by mass, even more preferably less than 3% by mass, and may even be less than 1% by mass.

[0025] Furthermore, the resin composition of this embodiment may contain a block copolymer of ethylene oxide and propylene oxide, but it is preferable that it is substantially free of it. Substantially free means that the content of the block copolymer of ethylene oxide and propylene oxide in the resin composition is preferably less than 10% by mass of the olefin content, more preferably less than 7% by mass, even more preferably less than 5% by mass, even more preferably less than 3% by mass, and may even be less than 1% by mass.

[0026] <Physical properties of resin compositions> The resin composition of this embodiment preferably has a water contact angle of 45° or more, more preferably 69° or less, and more preferably 60° or less, as measured according to the method described in the examples below. In this embodiment, it is surprising that the biofilm resistance tends to improve as a result of having a water contact angle within this range.

[0027] <Method for producing resin compositions> The resin composition of this embodiment can be easily prepared by known methods commonly used for preparing conventional thermoplastic resin compositions. For example, (1) a method of mixing all the components constituting the resin composition, supplying it to an extruder and melt-kneading it to obtain a pelletized resin composition; (2) a method of supplying a portion of the components constituting the resin composition from the main feed port of an extruder and the remaining components from the side feed port and melt-kneading them to obtain a pelletized resin composition; (3) a method of preparing pellets (masterbatch, etc.) with different compositions by extrusion or the like, and then mixing these pellets to adjust them into a resin composition having a predetermined composition. Examples of mixing machines include kneaders, Banbury mixers, and extruders. There are no particular restrictions on the various conditions and equipment for mixing and kneading; they can be appropriately selected from any conventionally known conditions. Mixing is preferably carried out at a temperature above the melting temperature of the polyacetal resin, specifically above the melting temperature of the polyacetal resin (generally 180°C or higher).

[0028] <Molded products> The molded articles of this embodiment are formed from the resin composition or pellets of this embodiment. Pelletized resin compositions of this embodiment are molded into molded articles using various molding methods. Alternatively, the resin composition, which has been melt-kneaded in an extruder, can be directly molded into molded articles without going through pellets. There are no particular restrictions on the shape of the molded articles, and they can be appropriately selected according to the application and purpose of the molded articles. Examples include plate-shaped, rod-shaped, sheet-shaped, film-shaped, cylindrical, annular, circular, elliptical, gear-shaped, polygonal, irregularly shaped, hollow, frame-shaped, box-shaped, and panel-shaped articles. The molded articles of this embodiment may be finished products or parts.

[0029] The method for molding the molded product is not particularly limited, and conventionally known molding methods can be used. Examples include injection molding, injection compression molding, extrusion molding, shape extrusion, transfer molding, hollow molding, gas-assisted hollow molding, blow molding, extrusion blow molding, IMC (in-mold coating) molding, rotational molding, multilayer molding, two-color molding, insert molding, sandwich molding, foam molding, and pressure molding. The molded product of this embodiment is preferably an injection-molded product.

[0030] The molded product of this embodiment can be widely used as a resin component in environments where biofilms are easily formed.For example, kitchen components and utensils such as tableware, various cooking utensils, storage containers, water filter pots, water purifiers, drains, corner sink strainers, various sink parts, water storage pots, insulated pots, plastic wrap, kitchen hoods, etc.; bathroom components such as washbasins, sinks, drain plugs, hair catchers, drain traps, etc.; bathroom components such as bathroom walls, bathtubs, faucets, mirrors, etc.; laundry components; toilet components such as toilet seats, toilet seat lids, toilet bowls, etc.; various pipes; various gaskets; various water storage items and equipment such as water storage tanks, water tanks, solar water heaters, aquariums, swimming pools, etc.; various packaging materials such as food packaging and cosmetic packaging; ventilation fans, windows Various indoor equipment such as frames, screens, sashes, and artificial marble; outdoor equipment such as power lines, antennas, roofing materials, house exterior walls, and window panes; various electrical equipment and their accessories such as air conditioners, air conditioner drain pans, various hoses, heat exchangers for air conditioning equipment, humidifiers, dryers, refrigerators, dishwashers, dish dryers, washing machines, vacuum cleaners, drink dispensers, coffee dispensers, microwave ovens, irons, steamers, aroma diffusers, home cleaning machines, high-pressure washers, kettles, and wearable devices; nasal feeding tubes, wound contact layers, catheters, and tube stents. Pacemaker shells, heart valves, orthopedic implants, periodontal implants, orthodontic appliances, other orthodontic devices, dentures, crowns, face masks, contact lenses, intraocular lenses, soft tissue implants, surgical instruments, sutures, cochlear implants, tympanoplasty tubes, shunts, postoperative drainage tubes, drainage devices, endotracheal tubes, heart valves, adhesive bandages, wound dressings, other implantable devices, and other indwelling devices, artificial skin, artificial muscles, and other medical articles; fishing equipment such as ships, ropes, fishing nets, fishing gear, floats, buoys, and other fishing components; thermal and nuclear power plants. It is preferably used in underwater structures such as inlet and outlet ports of power plants; seawater utilization equipment such as seawater pumps; power generation facilities and port / harbor facilities such as mega-floats, coastal roads, and underwater tunnels; civil engineering facilities such as sludge diffusion prevention membranes for various marine civil engineering works in canals and waterways; outdoor facilities such as bridges, road mirrors, billboards, traffic signs, various display devices, advertising towers, sound barriers, bridges, guardrails, and tunnels; agricultural materials such as plant pods, soil, irrigation tubes, pipes, and greenhouses; and display devices such as televisions, smartphones, tablet PCs, personal computers, and touch panel displays. [Examples]

[0031] The present invention will be described in more detail below with reference to examples. The materials, amounts used, proportions, processing content, and processing procedures shown in the following examples can be modified as appropriate, as long as they do not depart from the spirit of the present invention. Therefore, the scope of the present invention is not limited to the specific examples shown below. If the measuring instruments used in the examples are difficult to obtain due to discontinuation or other reasons, measurements can be taken using other instruments with equivalent performance.

[0032] 1.Raw materials The raw materials used were those shown in the table below. [Table 1]

[0033] 2. Reference Example 1, Examples 1-2 <Compound> The components shown in Table 1 were blended as shown in Table 2 (the units for each component in Table 2 are parts by mass), and after being uniformly mixed using a tumbler manufactured by Seiwa Iron Works Co., Ltd., the mixture was fed into the main feed port of a 30 mm diameter twin-screw extruder with one vent port and melted and mixed (extrusion conditions: L / D=35, extrusion temperature=190°C, screw rotation speed=120 rpm, vent vacuum pressure=-0.08 MPa, discharge rate=10 kg / hr) to prepare a pelletized resin composition. The following evaluations were performed using the obtained resin composition.

[0034] <Manufacturing of test specimens> The water droplet contact angle was measured using a strip-shaped test piece measuring 145 mm in length, 13 mm in width, and 1 mm in thickness. The resin composition (pellets) obtained above was molded using an injection molding machine (Shibaura Machine Co., Ltd., EC-100S) with the cylinder temperature set to 195°C and the mold temperature to 80°C. Biofilm formation was evaluated using flat test specimens measuring 30 mm in length, 30 mm in width, and 2 mm in thickness. The resin composition (pellets) obtained above was used to form flat test specimens measuring 63 mm in length, 63 mm in width, and 2 mm in thickness using an injection molding machine (Nissei Plastic Industrial Co., Ltd., DCE140) under conditions of a resin temperature of 185°C and a mold temperature of 80°C. Subsequently, the specimens were processed using a diamond cutting machine to produce test specimens measuring 30 mm in length, 30 mm in width, and 2 mm in thickness.

[0035] <Measuring the water contact angle> The water contact angle was measured for the test specimens obtained as described above using a solid-liquid interface analyzer (DropMaster300, manufactured by Kyowa Interface Science Co., Ltd.). A specified amount of water droplets, prepared using a syringe, were dropped onto the surface of the test specimen. After taking a photograph with a camera, the water contact angle was calculated using software. This process was repeated 10 times, and the average value was calculated.

[0036] <Evaluation of biofilm formation> The test specimens obtained above were tested for antibacterial properties according to ISO 4768 (2023). Specifically, three test pieces were attached to 40mm x 40mm glass plates, and the concentration of Staphylococcus epidermidis was 10 3 The specimens were immersed in a CFU / ml solution at 35°C for 48 hours. Afterward, the specimens were washed with water and stained by immersion in a 0.1% by mass crystal violet aqueous solution for 30 minutes. The specimens were then washed with water, the stained biofilm on the specimen surface was wiped off with a water-soluble nonwoven fabric, and the nonwoven fabric was dissolved by immersion in a 1% by mass sodium dodecyl sulfate solution. The absorbance at a wavelength of 590 nm was measured. The average value of the test results (absorbance) from the three test specimens was calculated. The R-value was also calculated as follows.

number

[0037] [Table 2]

[0038] As is clear from the above results, it was found that molded articles formed from the resin composition of the present invention exhibit excellent biofilm resistance.

[0039] Although the present invention has been described in detail using specific embodiments, it will be apparent to those skilled in the art that various modifications are possible without departing from the intent and scope of the invention.

Claims

1. Polyacetal resin and The above polyacetal resin contains 100 parts by mass of polyalkylene glycol in proportion to 0.1 to 5.0 parts by mass. Biofilm-resistant resin composition.

2. The biofilm-resistant resin composition according to claim 1, wherein the content of the polyalkylene glycol is 0.5 to 3.5 parts by mass per 100 parts by mass of the polyacetal resin.

3. The biofilm-resistant resin composition according to claim 1 or 2, wherein the polyalkylene glycol comprises polyethylene glycol.

4. The biofilm-resistant resin composition according to claim 1 or 2, wherein the number average molecular weight determined from the hydroxyl value of the polyalkylene glycol is 1,000 to 4,000.

5. The biofilm-resistant resin composition according to claim 1 or 2, wherein the water contact angle of the surface of a molded article formed from the biofilm-resistant resin composition is 45 to 69°.

6. The content of the polyalkylene glycol is 0.5 to 3.5 parts by mass per 100 parts by mass of the polyacetal resin. The polyalkylene glycol comprises polyethylene glycol, The number-average molecular weight of the polyalkylene glycol, as determined from its hydroxyl value, is between 1,000 and 4,000. The biofilm-resistant resin composition according to claim 1, wherein the water contact angle of the surface of a molded article formed from the biofilm-resistant resin composition is 45 to 69°.

7. Pellets of the biofilm-resistant resin composition according to claim 1, 2, or 6.

8. A molded article formed from the pellets described in claim 7.

9. A molded article formed from the biofilm-resistant resin composition according to claim 1, 2, or 6.

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