JPS6360780B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a filler-containing composition having extremely excellent practical properties such as rigidity, hardness, and impact resistance. Conventionally, many attempts have been made to fill polyolefin resins with cellulose fillers such as wood flour to improve physical properties such as rigidity, hardness, and molding shrinkage, and to reduce costs. In recent years, this technology has received increasing attention from the viewpoints of soaring resin prices, resource saving, resource utilization, and pollution prevention. However, for cellulosic materials,
It has a higher moisture content than other inorganic fillers, and when used as a composite material, it reduces moldability and significantly impairs the appearance of molded products. Furthermore, when blended at a high concentration, the mechanical properties are further impaired, and the drop in impact strength is particularly significant. This is presumed to be because cellulose fillers are hydrophilic and therefore have poor affinity with polyolefins, resulting in insufficient dispersibility and adhesion at the interface when blended. Various proposals have been made to improve these drawbacks. For example, there are methods of impregnating cellulose fillers with thermoplastic polymers, methods of blending low-molecular polyolefins, methods of using modified polyolefins, methods of impregnating processing aids after heat treatment, and methods of impregnating modified polyolefins with inorganic fillers. For example, it can be used in combination. Compositions obtained by these methods have either high rigidity but low impact resistance, or conversely, have increased impact resistance with a loss in rigidity. The present invention aims to provide a molding material having extremely excellent practical physical properties such as rigidity, hardness, and impact resistance. The present inventors have already invented a new reactive filler and a composition using the same (Japanese Patent Publication No. 1983-1999).
38581). As a result of intensive research based on this method, we found that when an active inorganic filler and an active cellulose filler are used together at a certain blending ratio, there are unexpected effects when compared to when they are used alone. It was discovered that a synergistic effect can be obtained, and the present invention was completed based on this discovery. That is, the present invention provides (a) polyolefin 20 to 90
Weight%, (b) On the powder surface of the inorganic filler, the polymerizable organic acid monomer having ethylenic double bonds forms a monomolecular ultra-thin film, and the ethylenic double bonds remain to form a powder. On the powder surface of 10 to 75% by weight of the active inorganic filler bonded to the metal element on the body surface and (c) the cellulose filler, a single molecule of a polymerizable organic acid monomer having an ethylenic double bond is present. A resin composition obtained by heating and kneading 5 to 40% by weight of an activated cellulose filler that forms a transparent film and leaves ethylenic double bonds to form ester bonds with hydroxyl groups on the powder surface. It is. The present invention will be specifically explained below. In the present invention, polyolefins mainly include polypropylene, ethylene-propylene copolymer, low density polyethylene, medium density polyethylene, high density polyethylene, polybutene-1, poly4-methylpentene-1, other olefins, and mixtures thereof. It is an ingredient. The inorganic fillers used in the present invention are oxides, hydroxides, carbonates, and silicates of metals of Groups, Groups, and Groups in the periodic table;
For example, calcium oxide, magnesium oxide, zinc oxide, aluminum oxide, beryllium oxide, titanium oxide, calcium hydroxide, magnesium hydroxide, aluminum hydroxide, calcium carbonate, magnesium carbonate, barium carbonate, basic lead carbonate, talc, mica, These include nepheline and wollastonite. These may be used alone or as a mixture, and their shape is not particularly limited, but those with an average particle size of 0.1 to 5 μm are preferable. The cellulose-based filler used in the present invention is a filler whose main component is cellulose, such as wood flour, rice husk, pulp, cellulose powder, wood chips, and mixtures thereof. For this purpose, use one finer than 20 meshes, preferably 80 meshes. In the present invention, the polymerizable organic acid monomer having ethylenic double bonds forms a monomolecular ultra-thin film on the powder surface of the inorganic filler, and the ethylenic double bonds remain. Uses an active inorganic filler that is strongly bonded to the metal elements on the powder surface. In the present invention, the polymerizable organic acid monomer having ethylenic double bonds forms a monomolecular ultra-thin film on the powder surface of the cellulose filler, and no ethylenic double bonds remain. An activated cellulose-based filler is used that forms ester bonds with hydroxyl groups on the cellulose surface. The method for producing the active inorganic filler and the active cellulosic filler includes contacting the filler with a polymerizable organic acid monomer having an ethylenic double bond;
This is done by heating the reaction. For this purpose, it is desirable to bring the filler in powder form into contact with the polymerizable organic acid in the substantial absence of liquid moisture. It is desirable that the polymerizable organic acid used be dehydrated and dried in advance to a moisture content of 5% or less.
It is desirable to keep it below % by weight. The polymerizable organic acid used in the present invention has a hydrocarbon moiety having one or more ethylenic double bonds, one or more carboxyl groups, and has 10 or less carbon atoms. unsaturated carboxylic acids such as acrylic acid, methacrylic acid, cinnamic acid, sorbic acid, acrylic acid such as α-chloroacrylic acid and its α,β substituted products, maleic acid, itaconic acid, vinyl acetic acid, allyl acetic acid,
Examples include 2-hydroxyethyl acrylate. In the present invention, higher acid strength is preferred, and acrylic acid and methacrylic acid are particularly effective in the present invention. These acids may be used alone or as a mixture of two or more. Alternatively, an acid anhydride may be used as a precursor of a polymerizable organic acid to convert it into an organic acid. In carrying out the present invention, first, the inorganic filler or cellulose filler and the polymerizable organic acid are reacted, and the polymerizable organic acid monomer is coated with ethylene on the powder surface of the filler. It is necessary to form a strongly bonded monomolecular ultra-thin film with residual double bonds. Therefore, the required amount of the polymerizable organic acid for the filler is such that the surface of the filler can be uniformly coated with a monomolecular thickness. Furthermore, the measurements for the filler
This amount is sufficient to uniformly coat the polymerizable organic acid to a thickness of 2 to 10 Å, as estimated from the BET specific surface area. For example, BET specific surface area is 1000-100
m ³ /g for 100 parts by weight of filler, from 100 to
20 parts by weight ^of an organic acid is suitable;
For 100 parts by weight of a filler having a specific surface area of 10 to 0.5 m ² /g, 2 to 0.1 parts by weight of organic acid is suitable.
However, the monomolecular ultra-thin film referred to in the present invention is one in which the filler surface and the polymerizable organic acid form a strong bond with residual ethylenic double bonds, and the filler surface is uniformly coated. It means a coating film of a polymerizable organic acid derivative. Therefore, if a reaction treatment is performed using an excess of polymerizable organic acid and free organic acids and free organic acid derivatives remain on the surface of the filler, the free organic acids and free organic acid derivatives can be removed by washing or other operations as described below. organic acids and free organic acid derivatives need to be removed. To empirically explain the properties of a monomolecular ultra-thin film of the active inorganic filler, when the active inorganic filler used in the present invention is suspended in liquid water and extracted, polymerization occurs to form a monomolecular ultra-thin film. The organic acid derivative is separated from the filler surface and extracted into water. This suggests that the bond between the organic acid and the metal on the surface of the filler is an ionic bond that can be dissociated with water. Of course, even if the residual filler obtained by extracting the active inorganic filler with liquid water is blended with polyolefin resin and melt-kneaded, it will still be as effective as the untreated filler. Never. On the other hand, even if the active inorganic filler used in the present invention is extracted with an anhydrous nonaqueous solvent that easily dissolves free polymerizable organic acids and free polymerizable organic acid metal salts, it is difficult to fill monomolecular ultrathin films. It is extremely difficult to separate and extract the agent from the surface of the agent into a solvent, and it can be said to be impossible under common-sense conditions. That is, the bond between the monomolecular ultra-thin film and the surface of the filler is a type of bond that is difficult to release by any method other than ionic dissociation by water. These facts were experimentally proven by determining the concentration of metal ions in the extract by chelate titration and by determining the concentration of ethylenic double bonds in the extract by the bromide-bromate method. Alternatively, the infrared absorption spectrum of the active inorganic filler proves that ethylenic double bonds remain on the filler surface, and the shift of the carbonyl group in the infrared absorption spectrum shows that the polymerizable organic acid is strongly bonded to the metal on the filler surface. (The carbonyl group in the infrared absorption spectrum of free polymerizable organic acid appears at around 700 cm ^-1 , whereas the carbonyl group in the infrared absorption spectrum of the active inorganic filler appears at around 1600 cm -1.) (shift low to below ^-1 ). From these experimental results, it is estimated that the bonding mode between the monomolecular ultrathin film and the filler surface is a salt-forming bond between the polymerizable organic acid and the filler metal. To further explain the properties of the monomolecular ultra-thin film of activated cellulose filler, the activated wood flour used in the present invention is thoroughly washed with an anhydrous non-aqueous solvent that easily dissolves free polymerizable organic acids, and after drying. When the expected esterification was experimentally verified using the saponification value measurement method, it was found that esterification did occur. Furthermore, as with the active inorganic filler, the presence of ethylenic double bonds on the surface of the activated wood flour was confirmed by the bromide-bromate method. From these experimental results, it is estimated that the bonding mode between the monomolecular ultra-thin film and the surface of wood flour is an ester bond between a polymerizable organic acid and a hydroxyl group, which is a functional group of wood flour. One method for producing the active inorganic filler and active cellulose filler of the present invention is to react the filler and polymerizable organic acid with high efficiency in various mixers within the above concentration range. As the mixer, various general powder mixers can be used, but high-efficiency mixers such as Henschel mixer, Mueller, and ribbon blender are particularly preferred. Furthermore, in order to increase the contact efficiency between the filler and the polymerizable organic acid,
Although it is desirable to add the polymerizable organic acid to the reaction system in the form of a mist, it is also possible to add it in the form of a gas. The atmosphere for this reaction can be normal pressure, reduced pressure, or increased pressure, but it is preferable to conduct it in the absence of liquid water, so that the water generated during the reaction can be removed from the reaction system. It is desirable to carry out the process under conditions (dehydration conditions). If the reaction is carried out in the presence of an excess of liquid water, it is difficult to produce the active filler of the present invention. The reaction temperature range for this reaction is above room temperature and below the decomposition temperature of the polymerizable organic acid, but is usually 50 to 200℃.
A range of is preferred. In addition, the reaction time range of this reaction is usually in the range of 1 minute to 2 hours, but 5 to 2 hours.
A range of 30 minutes is common. In addition, in order to avoid polymerization of the polymerizable organic acid or polymerizable organic acid salt during this reaction, the reaction atmosphere should be appropriately selected (air or oxygen atmosphere is preferable in the case of acrylic acid), or It is preferable to add a polymerization inhibitor to the organic acid. Polymerization inhibitors include hydroquinone, methoxyhadroquinone, p
- General polymerization inhibitors such as benzoquinone, naphthoquinone, and t-butylcatechol can be used, and the recommended amount is 0 to 1% by weight, especially 0.02 to 0.5% by weight based on the polymerizable organic acid. Ru. Another method for producing the active filler of the present invention is
The filler and an excess concentration of the polymerizable organic acid are reacted by the above method, and then washed with a nonaqueous solvent that easily dissolves the polymerizable organic acid and the polymerizable organic acid salt, filtered, and dried. This is a method of purification.
Suitable solvents that can be used in this method include low boiling point solvents such as methanol, ethanol, propanol, diethyl ether, acetone, methyl ethyl ketone, and ethyl acetate. Another method for producing the active filler of the present invention is
This is a method of stirring and mixing the sufficiently dried filler and polymerizable organic acid in the non-aqueous solvent, followed by filtering, washing, and drying to purify the filler. In this method, in addition to the above polar solvent, a non-polar solvent such as benzene, toluene, xylene, hexane, heptane, tetralin, decalin, chloroform, carbon tetrachloride, etc. is used to carry out a heating reaction, and then the above-mentioned polar solvent is used. Washing and purification is also possible. The active filler of the present invention may be prepared separately, or may be used by mixing an inorganic filler and a cellulose filler in advance and activating this mixture at the same time. As a device for heating and kneading the active inorganic filler, active cellulose filler, and polyolefin resin used in the present invention, general kneading machines such as various extruders, Banbury mixers, kneaders, and mixing rolls are used. A high-speed flow mixing device equipped with a heating jacket, such as a Henschel mixer, can also be used. Before feeding to the heating kneading device, a drum blender, V-type blender, ribbon blender, Henschel mixer, and other various premixing machines can be used if necessary. During heating and kneading, it is preferable to use a radical generator in order to promote the reaction between the polymer radicals of the polyolefin resin and the polymerizable organic acid monomer on the surface of the active filler. It is not a necessary condition. Radical generators that can be used in the present invention include tetravalent tin compounds such as dibutyltin oxide, 2,5-dimethyl-2,5
-di(t-butylperoxy)hexane, 2,5
-dimethyl-2,5-di(t-butylperoxy)hexyne-3, dicumyl peroxide, t
- Organic peroxides such as butyl peroxymaleic acid, lauroyl peroxide, benzoyl peroxide, t-butyl benzoate, t-butyl hydroperoxide, isopropyl peroxide, azo compounds such as azobisisobutyronitrile, It is a commonly used radical generator such as an inorganic peroxide such as ammonium sulfate, and one or a combination of two or more of these may be used. The amount of radical generator used is usually based on 100 parts by weight of the resin composition.
A range of 0.001 to 0.1 parts by weight is suitable. The blending ratio of polyolefin, active inorganic filler, and active cellulose filler in the present invention is as follows:
They are 20-90% by weight, 10-75% by weight, and 5-40% by weight, respectively. If the blending ratio of both fillers exceeds the above range, the moldability will be extremely reduced, the appearance of the molded product will be impaired, and the mechanical properties, particularly the impact strength, will be significantly reduced. In addition, if it is lower than the above range, the original purpose of filler filling effect, for example,
Not only cannot effects such as rigidity and dimensional stability be obtained, but also the synergistic effect of the combined use as referred to in the present invention cannot be obtained. In addition to the above composition, the resin composition of the present invention may contain stabilizers, plasticizers, lubricants, crosslinking agents, pigments, flame retardants, antistatic agents, thickeners, blowing agents, and other additives. . The heating kneading temperature in the present invention needs to be below the decomposition temperature of the cellulose filler and above the melting softening temperature which is the lower limit of the temperature at which polymer radicals are generated due to molecular chain scission of the polyolefin. As a result of various studies, the temperature condition is 150 to 260°C, preferably 180°C.
~240℃ range. As mentioned above, the resin composition of the present invention has excellent strength, rigidity, hardness, creep properties, friction and wear, because the inorganic filler and cellulose filler are strongly and highly efficiently bonded to the thermoplastic resin. It has extremely good mechanical properties, especially impact resistance. Furthermore, the resin composition of the present invention has extremely excellent thermal properties such as heat deformation resistance and dimensional stability, and has various properties such as surface activity such as adhesion, printability, and paintability, flame resistance, and easy incineration. Properties can also be imparted. These advantages are significant at high concentrations of filler. Furthermore, since the resin composition of the present invention does not contain excessive polymerizable organic acid salts or impurities on the surface of the active filler, the resin composition has extremely good thermal stability during melt-kneading or melt-molding. The appearance of the molded product is also extremely beautiful. Moreover, the durability of the resin composition when used at high temperatures is dramatically improved. The resin composition of the present invention has excellent moldability and has an extremely wide range of applications. For example, applications include various compression molded products, extrusion molded products, blow molded products, injection molded products, thermoformed products, rotary molded products, calendar molded products, various foam molded products, and secondary processed products such as stretched or forged products. It is possible. Furthermore, due to the synergistic effect of the active inorganic filler and the active cellulose filler, the resin composition of the present invention has an extremely high balance between strength and impact resistance (A in the drawing), as shown in the drawing. (equivalent to the part). EXAMPLES The present invention will be explained in more detail with reference to Examples below, but the present invention is not limited to the scope of these Examples. Note that parts and % in Examples and Reference Examples are parts by weight and % by weight, respectively. Moreover, the various physical property values illustrated are measured values based on the following method. Tensile yield strength; ASTM D-638 Tensile elongation at break; ASTM D-638 Bending strength; ASTM D-790 Flexural modulus; ASTM D-790 Izot impact strength; ASTM D-256 (V-notched) Heating deformation temperature; ASTM D -648 (186Kg/ ^cm2 ) Example 1 100 parts of heavy calcium carbonate with an average particle diameter of 1.2μ, a BET specific surface area of ^5.5m2 /g, and a moisture content of 0.18% was placed in a Henschel mixer and heated to 150℃. While stirring, 1 part of acrylic acid containing 700 ppm of hydroquinone was gradually added in the form of a mist using a spray addition device, and mixed at normal pressure for 30 minutes to obtain an active filler. The obtained active filler was a smooth powder with no acrylic acid odor. Water vapor and carbon dioxide gas were generated during the reaction, but both were removed from the system in gaseous form. The amount of acrylic acid used was sufficient to uniformly and uniformly coat the surface of calcium carbonate to a theoretical thickness of 18 Å. The active filler was thoroughly extracted with diethyl ether, the extract was re-extracted with water, and neutralized and titrated with caustic soda. As a result, 0.07 part of unreacted acrylic acid was analyzed in terms of acrylic acid. On the other hand, when the above active filler was thoroughly extracted with water and the extract was subjected to chelate titration with EDTA2Na solution using a BT indicator, 0.93 parts of calcium acrylate was analyzed in terms of acrylic acid. At the same time, this extract was titrated for ethylenic double bonds using the bromide-bromate method, and 0.92 parts of calcium acrylate was analyzed in terms of acrylic acid. At the same time, this extract was concentrated, recrystallized and purified using a methanol-diethyl ether mixed solvent, and calcium acrylate in an amount almost the same as the above titration value was identified by elemental analysis using infrared absorption spectroscopy. On the other hand, the active filler is washed and extracted with excess methanol, the extracted residue is dried, and then thoroughly extracted with water,
Chelate titration, as above, for the extract. Bromite-bromate titration revealed 0.21 parts of calcium acrylate in terms of acrylic acid. Therefore, it is considered that about 0.2 parts of acrylic acid is firmly bound to the surface of the active filler. In addition, 100 parts of wood flour, which has a grain size of 300 mesh and has been previously dried and whose moisture content has been adjusted to 2% or less, is placed in a Henschel mixer, heated to 150°C, and while stirring, 500 ppm of hydroquinone is added.
Using a spray addition device, 3 parts of acrylic acid containing 3 parts of acrylic acid was gradually added in the form of a mist, and mixed at normal pressure for 30 minutes to obtain an active filler. During the reaction, water vapor was generated, but it was removed from the system in gaseous form. The obtained active filler was thoroughly washed with excess methanol to remove unreacted acrylic acid, and approximately 1 g of the dried material was accurately weighed, and added to a mixture of 20 ml of 75% ethanol and 20 ml of 0.1N sodium hydroxide solution. After adding it and leaving it at 25℃ for 24 hours, the consumed sodium hydroxide was removed by 0.1N.
By back titration with sulfuric acid, 1.52 parts of acrylic ester was analyzed in terms of acrylic acid. At the same time, the obtained active filler was sufficiently washed with water and dried and subjected to the same test as above, and 2.72 parts of acrylic acid was analyzed in terms of acrylic acid. On the other hand, when we confirmed the presence of ethylenic double bonds using the bromide-bromate method using the above-mentioned activated filler that had been sufficiently washed with methanol to remove unreacted acrylic acid, 0.45 parts of acrylic acid was analyzed. did it. Therefore, it is considered that about 0.5 parts of acrylic acid is firmly bound to the surface of the active filler. Using activated heavy calcium carbonate and activated wood flour obtained by the above method, propylene-ethylene block copolymer (MI 3.0, density 0.91, ethylene content 6% by weight) was mixed in various ratios. Radical generator 2,5-dimethyl-2, as a reaction aid
0.02 5-di(t-butylperoxy)hexane
After pre-mixing, knead for 3 minutes using a Banbury mixer and form into a sheet with two rolls,
Turned into pellets. This pellet was molded into a test piece using an injection molding machine at a molding temperature of 200°C. Table 1 shows the results of evaluation using this test piece. Reference Examples 1-1 to 1-2 Table 1 shows the results of evaluation in the same manner as in Example 1, where the blending ratio exceeds the range of the present invention. Reference Example 1-3 A test piece was obtained in the same manner as in Example 1-1 using 50 parts of activated heavy calcium carbonate used in Example 1-1 and 50 parts of propylene-ethylene block copolymer. The evaluation results are shown in Table 2. Reference Example 1-4 Using 50 parts of activated wood flour and 50 parts of the propylene-ethylene block copolymer used in Example 1-1, a test piece was obtained in the same manner as in Example 1-1, and the results were evaluated. are shown in Table 2. Reference Examples 1-5 to 1-7 The blending ratio was the same as in Example 1, except that untreated wood flour that had only been dried (300 mesh passed product manufactured by Sanyo Kokusaku Pulp) was used instead of activated wood flour. Test pieces were obtained in the same manner and the evaluation results are shown in Table 2. Reference examples 1-8 to 1-10 Instead of activated wood flour and activated heavy calcium carbonate,
Test pieces were obtained in the same manner as in Example 1, except that untreated wood flour and untreated heavy calcium carbonate were used, and the evaluation results are shown in Table 2. Reference Example 1-11 to 1-13 Instead of activated heavy calcium carbonate, Reference Example 1-
Test pieces were obtained in the same manner as in Example 1, except that the untreated heavy calcium carbonate used in Example 8 was used, and the evaluation results are shown in Table 2. Reference Example 1-14 A test piece was obtained in the same manner as Reference Example 1-3, except that pre-dried wood flour was used instead of activated wood flour, and the evaluation results are shown in Table 2. Example 2 The same compounding ratio as in Example 1 was used except that high-density polyethylene (MI10, density 0.96) was used instead of the propylene-ethylene block copolymer.
Got a test piece. Table 3 shows the results of evaluation using this test piece. Reference Examples 2-1 to 2-2 Table 3 shows the results of evaluation using the same method as those in Example 2 whose blending ratios exceeded the scope of the present invention. Reference Examples 2-3 to 2-14 Performed in the same manner as Reference Examples 1-3 to 1-14 except that the high-density polyethylene used in Example 2 was used.
Test pieces were obtained and the results of evaluation are shown in Table 4. Using each of the above Examples and Reference Examples, graphs using tensile yield strength and Izot impact strength as indicators are shown in the drawings. In the drawings, A is an example of the present invention, B is a reference example containing an untreated inorganic filler and a cellulose filler, and C is an untreated inorganic filler and an active cellulose filler, or an active inorganic filler and an active inorganic filler. Reference example D shows a reference example in which an untreated cellulose filler was blended, and D shows a reference example in which only an active inorganic filler was blended.

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[Table] As can be seen from Tables 1 to 4, the polyolefin resin composition of the present invention has extremely excellent physical properties such as rigidity and impact resistance.
It can be seen that this effect is particularly excellent within the range defined by the present invention.

[Brief explanation of drawings]

The drawings use examples and reference examples of the present invention,
It is a graph using tensile yield strength and Izot impact strength as indicators.

Claims (1)

[Claims] 1. Polymerizable organic acid monomers having ethylenic double bonds form a monomolecular ultra-thin film on the powder surface of (a) 20 to 90% by weight of polyolefin and (b) inorganic filler. Active inorganic filler 10 to 75 that remains double bonds and bonds to metal elements on the powder surface
Weight% and (c) On the powder surface of the cellulose filler, the polymerizable organic acid monomer having ethylenic double bonds forms a monomolecular ultra-thin film, and the ethylenic double bonds remain. A resin composition obtained by heating and kneading 5 to 40% by weight of an active cellulose filler that forms ester bonds with hydroxyl groups on the powder surface.