JP2008127408A - Resin composition containing inorganic filler and its molded article - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To minimize the demerits such as the lowering of the tensile elongation, impact strength and gloss of even a molded article composed of a thermoplastic resin filled with calcium carbonate at a high concentration. <P>SOLUTION: Good mechanical properties and gloss can be imparted to a molded article obtained by various molding methods from a thermoplastic resin kneaded with fine particles of a precipitated calcium carbonate to improve the heat-resistance and rigidity of a thermoplastic resin molded article, prevent the warpage of an injection molded article and increase the specific gravity of a sheet-formed article. Calcium carbonate can be included in the thermoplastic resin at a high concentration to impart the obtained molded article with good mechanical properties and gloss. Good mechanical properties and gloss can be imparted to a molded article produced by melting and kneading a thermoplastic resin with a precipitated calcium carbonate having an average particle diameter of 0.05-1.0 μm and molding the mixture by a conventional method for the molding of thermoplastic resins. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention is a precipitated calcium carbonate produced by blowing carbon dioxide into a calcium hydroxide slurry, wherein the calcium carbonate as an inorganic filler has an average particle size of 0.05 to 1.0 μm, Furthermore, the present invention relates to an inorganic filler-containing resin composition and a molded product thereof, wherein the resin composition is further melt-kneaded into a thermoplastic resin and further molded.

  An inorganic filler is contained in a thermoplastic resin, pelletized after melt-kneading, and further molded by extrusion, such as film for packaging, sheet for building materials, deformed extrusions such as pipes and window frames, automobile interior parts and machine parts. It is a well-known fact that many molded products can be obtained by various molding methods such as injection molded products. In addition, molded products containing inorganic fillers have mechanical properties such as improved surface appearance, improved heat resistance, tensile strength, and flexural modulus compared to molded products that do not contain fillers, that is, molded with only a thermoplastic resin. , Reduction of molded product price, reduction of combustion temperature and calorie during incineration of discarded molded product, prevention of blocking of film and sheet molded product and improvement of friction coefficient, prevention of warpage by suppressing shrinkage rate of injection molded product, It is a well-known fact that various functions such as an increase in specific gravity of a molded product are expressed.

Among the inorganic fillers, the most commonly used substances are calcium carbonate, hydrous magnesium silicate (talc), kaolin clay, barium sulfate, and zeolite. Among them, calcium carbonate is inexpensive and has many characteristics depending on the production method. Since there are many grades, they are used in many fields regardless of film, sheet, profile extrusion molding, and injection molding. However, when high concentration of calcium carbonate is added to the thermoplastic resin to improve heat resistance, rigidity, warpage of the injection molded product, and increase the specific gravity of the sheet molded product, the tensile elongation, impact value, and gloss are remarkably high depending on the grade. Since it is also a fact that it deteriorates, it is also necessary to select calcium carbonate capable of improving these disadvantages and to melt and knead it in a thermoplastic resin.
JP-A-5-139728

  The object of the present invention is to minimize the disadvantages caused by the molded article obtained by filling a thermoplastic resin with a high concentration of calcium carbonate, for example, the tensile elongation, impact value, and gloss.

  The resin composition of the present invention can be obtained by an apparatus capable of generally melt-kneading a thermoplastic resin and an inorganic filler, and the molded product of the present invention can also be produced by a general method for molding a thermoplastic resin. It is characterized by.

  The resin composition of the present invention and the molded product thereof have an average particle size of 0.05 to 1.0 μm, and use a colloidal calcium carbonate produced by blowing carbon dioxide into a calcium oxide slurry, thereby forming a thermoplastic resin. Even when melt-kneaded to a high concentration and molded, it is possible to minimize deterioration of tensile elongation, impact value, and gloss.

  First, the thermoplastic resin of the present invention will be described. The thermoplastic resin is a polymer that is solid at room temperature, has a specific melting point and softening point, and has a repeating unit obtained by polymerization of monomers (general abbreviations in parentheses). Typical thermoplastic resins include polyethylene (PE), polypropylene (PP), polyamide (PA), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyvinyl chloride (PVC), polystyrene (PS), styrene Butadiene / acrylonitryl terpolymer (ABS), polymethyl methacrylate (PMMA), polyvinyl alcohol (PVA), ionomer resin, fluororesin (PVDF PTFE, etc.), polyacetal (POM), thermoplastic elastomer (TPE) , Thermoplastic urethane (TPU), liquid crystal polymer (LCP), biodegradable resin (PLA, PBSA), polycarbonate (PC), polyphenylene ether (PPE), polyphenylene sulfide (PPS), polymethylpentene (P P), petroleum resins, cyclic polyolefin, polyimide, and a graft polymer and the like obtained by introducing a functional group such as a copolymer or a carboxylic acid or its ester of these resins with each other in the polymer backbone.

  The method of melt-kneading a material such as an inorganic filler in these thermoplastic resins is a method of melt-kneading by adding a target material while applying a shearing force by heating the thermoplastic resin to the melting point or the softening point or higher. Is generally used. The substances mentioned here are not only inorganic fillers but also various additives such as antioxidants, anti-aging agents, stabilizers, UV absorbers, light stabilizers, antistatic agents, lubricants, plasticizers, slip agents, dyes and pigments Any colorant, flame retardant, foaming agent, deodorant, antibacterial agent, antifungal agent, etc., that has been heat-processed by dispersing the thermoplastic resin may be used as long as it can withstand the melt kneading temperature of the thermoplastic resin.

    The calcium carbonate used in the present invention has the following characteristics. The classification by the production method of calcium carbonate is roughly divided into heavy calcium carbonate, which is a pulverized product of natural products, and lime milk produced by adding water to limestone (CaO) obtained by baking limestone (Ca (OH) ↓ There are two types of precipitated calcium carbonate produced after blowing carbon dioxide into 2). In particular, precipitated calcium carbonate can be produced in various average particle diameters and particle shapes by adjusting the reaction conditions at the time of production.

  The average particle size of the precipitated calcium carbonate used in the present invention is desirably 0.05 to 1.0 μm. In addition, the average particle diameter said here is a 50% passage particle system in the particle size distribution of the centrifugal sedimentation method. If the average particle size is less than 0.05 μm, the mechanical properties and gloss when added to the molded product will be improved, but the bulk density and oil absorption will be too high when melt-kneading into thermoplastic resins at high concentrations. It is not desirable to use a great deal of time and energy in order to sufficiently wet the resin during melt kneading, and if the average particle size exceeds 1.0 μm, there is a problem during melt kneading with the thermoplastic resin described above. This is because although the mechanical properties of the molded article, for example, the decrease in tensile strength and elongation when made into a film is remarkable, the gloss may be deteriorated, which is undesirable.

  The calcium carbonate used in the present invention may be subjected to a surface treatment by a universal method in order to improve the wettability with the resin when melt-kneaded into the thermoplastic resin. The surface treatment referred to here is a copolymer obtained by copolymerizing with higher fatty acids such as stearic acid, palmitic acid, oleic acid or alkyl esters, amides, α-β unsaturated carboxylic acids or esters thereof described in Patent Document 1. It is described that calcium carbonate having excellent dispersibility can be obtained by coating an organosilane compound after coating a carboxyl-modified resin on the surface of calcium carbonate.

  Next, the melt kneading method will be described. The melt kneading method mentioned here needs to have both a function of heating and plasticizing thermoplasticity and a function of kneading the above-mentioned substances by applying a shearing force and uniformly dispersing them in the thermoplastic resin. Specific examples of the batch kneader include a kneader, a two roll mill, a three roll mill, and a Banbury mixer. Examples of the continuous kneader include a single screw extruder, a twin screw extruder, an FCM, and a kneader. It is desirable that these melt kneaders be used sequentially depending on the type of resin or lot scale used and the content of the substance to be added.

[Example]
EXAMPLES The present invention will be described in more detail with reference to the following examples. However, the following examples do not limit the scope of rights of the present invention. In the examples, “%” represents “% by weight”.
[Examples 1 to 3]
With the blending composition shown in Table 1, 7 kg of the blend was previously introduced into a high-speed stirrer (super mixer FM20 type, internal volume = 20 L, manufactured by Kawata), and then mixed for 3 minutes at blade rotation speed = 2000 rpm. The obtained mixture was melt-kneaded with a twin screw extruder (caliber 30 mm, L / D = 32) at a cylinder temperature of 180 ° C. and a screw rotation speed of 280 rpm to prepare cylindrical pellets having a diameter of 3 mm and a length of 3 mm.

The obtained pellets were further processed into a high specific gravity sheet having a width of 130 mm and a thickness of 0.3 mm at a cylinder die temperature of 200 ° C. using a single-screw extruder (caliber = 30 mmL / D = 32) loaded with a full flight screw with a T die. After molding and measuring the specific gravity by the underwater substitution method, the No. 2 type tensile test piece defined in JIS K6760 is punched out, and the molded product flow direction (described as MD) and the molded product flow vertical direction (described as TD) Tensile elongation at a tensile speed = 50 mm / min was measured. Further, the gloss of the film was visually evaluated.
[Comparative Examples 1-3]
The same operation as in the example was performed with the composition shown in Table 2.

In the method shown in Table 1, the tensile elongation of the sheet is good regardless of MD and TD, and the gloss of the sheet is also good, whereas in the method shown in Table 2, the tensile elongation of the sheet is compared with the method shown in Table 1. Not only is it getting worse, but you can see that the difference between MD and TD is getting bigger. It can also be seen that the gloss is worse than the method shown in Table 1.

Claims (3)

  A resin composition comprising 40 to 85% by weight of a thermoplastic resin and 15 to 60% by weight of colloidal calcium carbonate.   2. The resin composition according to claim 1, wherein the colloidal calcium carbonate has an average particle size of 0.05 to 1.0 [mu] m. A molded article using the resin composition according to claim 1.