JPH032383B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention is a vinylidene fluoride resin composition that is newly endowed with other excellent properties by adding potassium titanate fibers to the vinylidene fluoride resin without impairing the inherent properties of the resin. Regarding. Polyvinylidene fluoride (hereinafter referred to as PVDF)
Like other fluororesins such as polytetrafluoroethylene, vinylidene fluoride resins have excellent properties such as chemical resistance, weather resistance, oil resistance, and radiation resistance. Since it has the best mechanical properties such as creep resistance among fluororesins, it is used as an industrial material for pipes, gaskets, packing, paints, etc. However, in terms of moldability, although it is very easy compared to polytetrafluoroethylene etc., it has a high molding shrinkage rate when compared to general thermoplastic resins, and its heat resistance is not necessarily sufficient. At present, the field of use is actually limited for reasons such as the fact that the mechanical strength is still not at a satisfactory level for use as a structural material. Various studies have been carried out in the past to solve this problem, and only by adding carbon fiber or graphite fiber with a fiber length of 0.1 to 5 mm within a range of 30% (weight %, the same hereinafter) or less. It has been found that heat resistance is improved, molding shrinkage is improved, and mechanical properties are strengthened. However, the effect of improving mechanical properties by adding carbon fiber or graphite fiber is not sufficient;
The tensile strength and flexural strength are at most 1.5 times that of the unfilled case, and the flexural modulus, which is a feature of the effect of adding carbon fiber or graphite fiber, is at most 2.5.
Stay double. Furthermore, since carbon fibers or graphite fibers are relatively long fibrous materials with an average fiber diameter of 7 to 12 μm and an average fiber length of 100 μm or more, they tend to become oriented during molding and cause anisotropy in mold shrinkage. As a result, anisotropy occurs in terms of strength, and in products with complex shapes, there are parts that are hardly reinforced, resulting in a major problem in that the desired product cannot be obtained. In view of the above-mentioned circumstances, the inventors of the present invention have made extensive studies and have solved all of the above problems by using potassium titanate fibers, which are more than an order of magnitude smaller in size than carbon fibers or graphite fibers. The inventors have discovered that the present invention can be achieved. That is, the present invention relates to a vinylidene fluoride resin composition characterized in that 5 to 40% of potassium titanate fibers are added to the vinylidene fluoride resin. Vinylidene fluoride resins that can be used in the present invention include only vinylidene fluoride homopolymers obtained by producing vinylidene fluoride monomers by suspension polymerization, emulsion polymerization, solution polymerization, or any other method. First, it also refers to a vinylidene fluoride copolymer containing 90 mol% or more of a vinylidene fluoride component that has essentially the same properties as such a homopolymer. In the case of such a copolymer, monomers copolymerizable with the vinylidene fluoride monomer include, for example, ethylene tetrafluoride, propylene hexafluoride, ethylene monochloride trifluoride, and vinyl fluoride. The degree of polymerization of vinylidene fluoride resin is expressed as intrinsic viscosity ηinh, which is approximately 0.5 to 2.0, especially 0.8 to 1.5.
Preferably. ηinh described here is expressed by the formula: ηinh=1/Cln [η/ηo] (where c is the concentration of the polymer dimethylformamide solution (0.4 g/dl), η is the viscosity of the polymer dimethylformamide solution, and ηo is dimethyl These values represent the viscosity of formamide alone, and are measured at 30°C. If the ηinh is less than 0.5, the mechanical properties of the vinylidene fluoride resin will be low, while if it exceeds 2.0, the melt viscosity will be too high, causing problems in moldability, both of which are unfavorable. The potassium titanate fiber that can be used in the present invention has the general formula: K ₂ O.n (TiO ₂ ) or K ₂ O.n (TiO ₂ ).1/2H ₂ O (wherein, n is 2 to 8 represents an integer of ), specifically, for example, potassium 4 titanate fiber, potassium 6 titanate fiber, 8
Potassium titanate fiber alone or a mixture thereof, with an average fiber diameter of 0.1 to 2 μm, an average fiber length of 5 to 100 μm, and an average fiber length/average fiber diameter (aspect ratio) of 10 to 200 is preferable. used for. The average fiber diameter and average fiber length of the potassium titanate fibers referred to herein were measured using a scanning electron microscope for at least 5 or more fields of view, and measured for at least 10 or more fibers per field of view. The aspect ratio is the average fiber length of such fibers divided by the average fiber diameter. If the average fiber diameter, average fiber length, and aspect ratio of the potassium titanate fibers are outside the above ranges, for example, the average fiber diameter is larger than 1 μm and the average fiber length is smaller than 5 μm, that is, the aspect ratio is 5. If it is smaller than 10, the reinforcing effect will be reduced, which is not preferable. In addition, ultra-fine fibers with an average fiber diameter of 0.1 μm or less or fiber length of 100 μm
It is difficult to industrially produce fibers longer than this, and they are impractical. The amount of potassium titanate fiber is 5 to 40.
% is appropriate. If it is less than 5%, the reinforcing effect will be poor, while if it exceeds 40%, the effect of improving physical properties will not be significant considering the amount filled, and the melt viscosity will become too high, causing problems in moldability, both of which are unfavorable. The potassium titanate fibers used in the present invention are preferably surface-treated with a silane coupling agent, a titanate coupling agent, an epoxy resin, an epoxy urethane resin, etc. in order to improve adhesion to the vinylidene fluoride resin. used for. Furthermore, untreated titanium fluoride resin and untreated potassium titanate fibers can be mixed and extruded to produce a resin composition (pellet) by adding a silane coupling agent. There is a tendency for the effect of improving physical properties to be even greater than when the potassium acid fibers are used as they are. Various methods can be applied to the production of the resin composition of the present invention, including (1) a method in which potassium titanate fibers are blended from the beginning of polymerizing vinylidene fluoride monomer, and (2) a method in which potassium titanate fibers are blended during polymerization or polymer removal. (3) At the step of pelletizing vinylidene fluoride resin after polymerization, extraction, and drying, potassium titanate fiber is kneaded with the resin using an extruder or the like, and extrusion is carried out. After that, methods such as water cooling and cutting to form pellets can be applied, and method (3) is particularly the most practical. In addition, Ca, Ba,
Additives such as hydroxides such as Zn and Mg, heat stabilizers such as carbonates, crystallinity improvers (crystal nucleating agents) such as terephthalic acid, kaolin, talc, and diatomaceous earth, and crosslinking agents such as tripropargyl cyanurate. It may be added as appropriate depending on the purpose. The resin composition of the present invention has a fiber size of approximately 1/10 to 1/10 of that of conventionally known carbon fiber reinforced products.
Despite using potassium titanate fiber, which is a 1/100 micro fiber material, as a reinforcing material, no other plastic material has been found to have a greater effect on improving mechanical properties than the carbon reinforced product. This is a unique phenomenon. Moreover, the characteristics of microfiber filling are that the orientation during molding (anisotropy of molding shrinkage rate) is small, the dimensional accuracy is greatly improved, and the molding of parts with complex shapes or extremely small and thin walls is possible. Its practical value is extremely great, as it enables the use of carbon fiber-reinforced products, has better surface smoothness and gloss, and has an extremely superior product appearance compared to conventional carbon fiber-reinforced products. Mechanical parts such as gears and bearings, precision parts such as small gears, sliding parts that require surface precision such as rolls, etc.), as well as traditionally used lining sheets and lining powder coatings. can be applied, and the effect of improving the above-mentioned physical properties can be expected. Hereinafter, the present invention will be explained in more detail based on Examples, but the present invention is not limited to these Examples. Examples 1 to 5 and Comparative Example 1 PVDF powder (trade name, KF Polymer #1000, manufactured by Kureha Chemical Industry Co., Ltd., ηinh = 1.00) was treated with epoxy silane, with an average fiber diameter of 0.3 μm and an average fiber length of 15 μm.
m potassium titanate fiber (product name, Teismo)
D102 (manufactured by Otsuka Chemical Co., Ltd.) was added in a range of 5 to 40% as shown in Table 1, and for comparison, it was not added. The mixture was melted and kneaded at a temperature of 100 ml, and then cooled with water to form pellets. Then, using the pellets obtained, the injection temperature is
Injection molding was carried out under the conditions of 220° C., mold temperature 90° C., and injection pressure 800 Kg/cm ² to prepare the following test pieces. The test pieces were used to measure the physical properties shown below. The results are summarized in Table 1. (1) Tensile strength: JIS K7113 No. 1 test piece (4mm
Thickness), chuck distance 100mm, test speed 10mm/min (2) Bending strength and bending modulus: JIS K7203 (length 185mm, width 10mm, height 4mm), distance between fulcrums 60
mm, test speed 5 mm/min (3) Mold shrinkage rate and surface smoothness: length 60 mm, width
The molding shrinkage rate was determined using a micrometer using three side gate flat plates of 50 mm and height 3 mm, and the surface smoothness was determined by the naked eye.

【table】

[Table] From Table 1, the filling effect of potassium titanate fibers is clearly visible at 5 to 40%.
It can be seen that at 40%, it is difficult to significantly improve the physical properties even if the content exceeds this amount. Comparative Examples 2 to 5 Average fiber diameter instead of potassium titanate fiber
Carbon fiber (product name,
5 to 30% of the carbon fiber as shown in Table 2.
Resin compositions and test pieces were prepared in the same manner as in Examples 1 to 5, except that each of these resins was added in the following ranges, and various physical properties were measured. The results are shown in Table 2.

[Table] Comparing the measurement results in Tables 1 and 2,
It was found that the resin composition of the present invention has a greater effect on improving physical properties than the carbon fiber filled product, which was conventionally thought to have a large effect on improving physical properties, and the anisotropy of molding shrinkage rate is significantly reduced. Useful effects such as ease of mold design and small internal distortion of the molded product are obtained.

Claims (1)

[Scope of Claims] 1. A vinylidene fluoride resin composition comprising 5 to 40% by weight of potassium titanate fibers added to a vinylidene fluoride resin. 2. The vinylidene fluoride resin contains 90 mol% or more of vinylidene fluoride component and has an intrinsic viscosity ηinh.
2. The vinylidene fluoride resin composition according to claim 1, which is a vinylidene fluoride homopolymer or copolymer of 0.5 to 2.0. 3. Average fiber diameter of potassium titanate fiber is 0.1~
2 μm, an average fiber length of 5 to 100 μm, and an average fiber length/average fiber diameter (aspect ratio) of 10 to 200.